COMMISSION IMPLEMENTING DECISION (EU) 2021/2326
of 30 November 2021
establishing best available techniques (BAT) conclusions, under Directive 2010/75/EU of the European Parliament and of the Council, for large combustion plants
(notified under document C (2021) 8580)
(Text with EEA relevance)
Article 1
Article 2
Article 3
ANNEX
BEST AVAILABLE TECHNIQUES (BAT) CONCLUSIONS
SCOPE
DEFINITIONS
Term used |
Definition |
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General terms |
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Boiler |
Any combustion plant with the exception of engines, gas turbines, and process furnaces or heaters |
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Combined-cycle gas turbine (CCGT) |
A CCGT is a combustion plant where two thermodynamic cycles are used (i.e. Brayton and Rankine cycles). In a CCGT, heat from the flue-gas of a gas turbine (operating according to the Brayton cycle to produce electricity) is converted to useful energy in a heat recovery steam generator (HRSG), where it is used to generate steam, which then expands in a steam turbine (operating according to the Rankine cycle to produce additional electricity). For the purpose of these BAT conclusions, a CCGT includes configurations both with and without supplementary firing of the HRSG |
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Combustion plant |
Any technical apparatus in which fuels are oxidised in order to use the heat thus generated. For the purposes of these BAT conclusions, a combination formed of:
is considered as a single combustion plant. For calculating the total rated thermal input of such a combination, the capacities of all individual combustion plants concerned, which have a rated thermal input of at least 15 MW, shall be added together |
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Combustion unit |
Individual combustion plant |
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Continuous measurement |
Measurement using an automated measuring system permanently installed on site |
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Direct discharge |
Discharge (to a receiving water body) at the point where the emission leaves the installation without further downstream treatment |
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Flue-gas desulphurisation (FGD) system |
System composed of one or a combination of abatement technique(s) whose purpose is to reduce the level of SOX emitted by a combustion plant |
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Flue-gas desulphurisation (FGD) system – existing |
A flue-gas desulphurisation (FGD) system that is not a new FGD system |
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Flue-gas desulphurisation (FGD) system – new |
Either a flue-gas desulphurisation (FGD) system in a new plant or a FGD system that includes at least one abatement technique introduced or completely replaced in an existing plant following the publication of these BAT conclusions |
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Gas oil |
Any petroleum-derived liquid fuel falling within CN code 2710 19 25 , 2710 19 29 , 2710 19 47 , 2710 19 48 , 2710 20 17 or 2710 20 19 . Or any petroleum-derived liquid fuel of which less than 65 vol-% (including losses) distils at 250 °C and of which at least 85 vol-% (including losses) distils at 350 °C by the ASTM D86 method |
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Heavy fuel oil (HFO) |
Any petroleum-derived liquid fuel falling within CN code 2710 19 51 to 2710 19 68 , 2710 20 31 , 2710 20 35 , 2710 20 39 . Or any petroleum-derived liquid fuel, other than gas oil, which, by reason of its distillation limits, falls within the category of heavy oils intended for use as fuel and of which less than 65 vol-% (including losses) distils at 250 °C by the ASTM D86 method. If the distillation cannot be determined by the ASTM D86 method, the petroleum product is also categorised as a heavy fuel oil |
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Net electrical efficiency (combustion unit and IGCC) |
Ratio between the net electrical output (electricity produced on the high-voltage side of the main transformer minus the imported energy – e.g. for auxiliary systems’ consumption) and the fuel/feedstock energy input (as the fuel/feedstock lower heating value) at the combustion unit boundary over a given period of time |
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Net mechanical energy efficiency |
Ratio between the mechanical power at load coupling and the thermal power supplied by the fuel |
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Net total fuel utilisation (combustion unit and IGCC) |
Ratio between the net produced energy (electricity, hot water, steam, mechanical energy produced minus the imported electrical and/or thermal energy (e.g. for auxiliary systems’ consumption)) and the fuel energy input (as the fuel lower heating value) at the combustion unit boundary over a given period of time |
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Net total fuel utilisation (gasification unit) |
Ratio between the net produced energy (electricity, hot water, steam, mechanical energy produced, and syngas (as the syngas lower heating value) minus the imported electrical and/or thermal energy (e.g. for auxiliary systems’ consumption)) and the fuel/feedstock energy input (as the fuel/feedstock lower heating value) at the gasification unit boundary over a given period of time |
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Operated hours |
The time, expressed in hours, during which a combustion plant, in whole or in part, is operated and is discharging emissions to air, excluding start-up and shutdown periods |
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Periodic measurement |
Determination of a measurand (a particular quantity subject to measurement) at specified time intervals |
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Plant – existing |
A combustion plant that is not a new plant |
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Plant – new |
A combustion plant first permitted at the installation following the publication of these BAT conclusions or a complete replacement of a combustion plant on the existing foundations following the publication of these BAT conclusions |
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Post-combustion plant |
System designed to purify the flue-gases by combustion which is not operated as an independent combustion plant, such as a thermal oxidiser (i.e. tail gas incinerator), used for the removal of the pollutant(s) (e.g. VOC) content from the flue-gas with or without the recovery of the heat generated therein. Staged combustion techniques, where each combustion stage is confined within a separate chamber, which may have distinct combustion process characteristics (e.g. fuel to air ratio, temperature profile), are considered integrated in the combustion process and are not considered post-combustion plants. Similarly, when gases generated in a process heater/furnace or in another combustion process are subsequently oxidised in a distinct combustion plant to recover their energetic value (with or without the use of auxiliary fuel) to produce electricity, steam, hot water/oil or mechanical energy, the latter plant is not considered a post-combustion plant |
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Predictive emissions monitoring system (PEMS) |
System used to determine the emissions concentration of a pollutant from an emission source on a continuous basis, based on its relationship with a number of characteristic continuously monitored process parameters (e.g. the fuel gas consumption, the air to fuel ratio) and fuel or feed quality data (e.g. the sulphur content) |
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Process fuels from the chemical industry |
Gaseous and/or liquid by-products generated by the (petro-)chemical industry and used as non-commercial fuels in combustion plants |
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Process furnaces or heaters |
Process furnaces or heaters are:
As a consequence of the application of good energy recovery practices, process heaters/furnaces may have an associated steam/electricity generation system. This is considered to be an integral design feature of the process heater/furnace that cannot be considered in isolation |
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Refinery fuels |
Solid, liquid or gaseous combustible material from the distillation and conversion steps of the refining of crude oil. Examples are refinery fuel gas (RFG), syngas, refinery oils, and pet coke |
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Residues |
Substances or objects generated by the activities covered by the scope of this document, as waste or by-products |
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Start-up and shut-down period |
The time period of plant operation as determined pursuant to the provisions of Commission Implementing Decision 2012/249/EU(1), concerning the determination of start-up and shut-down periods for the purposes of Directive 2010/75/EU of the European Parliament and the Council on industrial emissions |
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Unit – existing |
A combustion unit that is not a new unit |
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Unit- new |
A combustion unit first permitted at the combustion plant following the publication of these BAT conclusions or a complete replacement of a combustion unit on the existing foundations of the combustion plant following the publication of these BAT conclusions |
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Valid (hourly average) |
An hourly average is considered valid when there is no maintenance or malfunction of the automated measuring system |
Term used |
Definition |
Pollutants/parameters |
|
As |
The sum of arsenic and its compounds, expressed as As |
C3 |
Hydrocarbons having a carbon number equal to three |
C4+ |
Hydrocarbons having a carbon number of four or greater |
Cd |
The sum of cadmium and its compounds, expressed as Cd |
Cd+Tl |
The sum of cadmium, thallium and their compounds, expressed as Cd+Tl |
CH4 |
Methane |
CO |
Carbon monoxide |
COD |
Chemical oxygen demand. Amount of oxygen needed for the total oxidation of the organic matter to carbon dioxide |
COS |
Carbonyl sulphide |
Cr |
The sum of chromium and its compounds, expressed as Cr |
Cu |
The sum of copper and its compounds, expressed as Cu |
Dust |
Total particulate matter (in air) |
Fluoride |
Dissolved fluoride, expressed as F- |
H2S |
Hydrogen sulphide |
HCl |
All inorganic gaseous chlorine compounds, expressed as HCl |
HCN |
Hydrogen cyanide |
HF |
All inorganic gaseous fluorine compounds, expressed as HF |
Hg |
The sum of mercury and its compounds, expressed as Hg |
N2O |
Dinitrogen monoxide (nitrous oxide) |
NH3 |
Ammonia |
Ni |
The sum of nickel and its compounds, expressed as Ni |
NOX |
The sum of nitrogen monoxide (NO) and nitrogen dioxide (NO2), expressed as NO2 |
Pb |
The sum of lead and its compounds, expressed as Pb |
PCDD/F |
Polychlorinated dibenzo-p-dioxins and -furans |
RCG |
Raw concentration in the flue-gas. Concentration of SO2 in the raw flue-gas as a yearly average (under the standard conditions given under General considerations) at the inlet of the SOX abatement system, expressed at a reference oxygen content of 6 vol-% O2 |
Sb+As+Pb+Cr+Co+Cu+Mn+Ni+V |
The sum of antimony, arsenic, lead, chromium, cobalt, copper, manganese, nickel, vanadium and their compounds, expressed as Sb+As+Pb+Cr+Co+Cu+Mn+Ni+V |
SO2 |
Sulphur dioxide |
SO3 |
Sulphur trioxide |
SOX |
The sum of sulphur dioxide (SO2) and sulphur trioxide (SO3), expressed as SO2 |
Sulphate |
Dissolved sulphate, expressed as SO4 2- |
Sulphide, easily released |
The sum of dissolved sulphide and of those undissolved sulphides that are easily released upon acidification, expressed as S2- |
Sulphite |
Dissolved sulphite, expressed as SO3 2- |
TOC |
Total organic carbon, expressed as C (in water) |
TSS |
Total suspended solids. Mass concentration of all suspended solids (in water), measured via filtration through glass fibre filters and gravimetry |
TVOC |
Total volatile organic carbon, expressed as C (in air) |
Zn |
The sum of zinc and its compounds, expressed as Zn |
ACRONYMS
Acronym |
Definition |
ASU |
Air supply unit |
CCGT |
Combined-cycle gas turbine, with or without supplementary firing |
CFB |
Circulating fluidised bed |
CHP |
Combined heat and power |
COG |
Coke oven gas |
COS |
Carbonyl sulphide |
DLN |
Dry low-NOX burners |
DSI |
Duct sorbent injection |
ESP |
Electrostatic precipitator |
FBC |
Fluidised bed combustion |
FGD |
Flue-gas desulphurisation |
HFO |
Heavy fuel oil |
HRSG |
Heat recovery steam generator |
IGCC |
Integrated gasification combined cycle |
LHV |
Lower heating value |
LNB |
Low-NOX burners |
LNG |
Liquefied natural gas |
OCGT |
Open-cycle gas turbine |
OTNOC |
Other than normal operating conditions |
PC |
Pulverised combustion |
PEMS |
Predictive emissions monitoring system |
SCR |
Selective catalytic reduction |
SDA |
Spray dry absorber |
SNCR |
Selective non-catalytic reduction |
GENERAL CONSIDERATIONS
Best Available Techniques
Emission levels associated with the best available techniques (BAT-AELs)
BAT-AELs for emissions to air
Activity |
Reference oxygen level (OR) |
Combustion of solid fuels |
6 vol-% |
Combustion of solid fuels in combination with liquid and/or gaseous fuels |
|
Waste co-incineration |
|
Combustion of liquid and/or gaseous fuels when not taking place in a gas turbine or an engine |
3 vol-% |
Combustion of liquid and/or gaseous fuels when taking place in a gas turbine or an engine |
15 vol-% |
Combustion in IGCC plants |
Averaging period |
Definition |
Daily average |
Average over a period of 24 hours of valid hourly averages obtained by continuous measurements |
Yearly average |
Average over a period of one year of valid hourly averages obtained by continuous measurements |
Average over the sampling period |
Average value of three consecutive measurements of at least 30 minutes each(2) |
Average of samples obtained during one year |
Average of the values obtained during one year of the periodic measurements taken with the monitoring frequency set for each parameter |
BAT-AELs for emissions to water
Energy efficiency levels associated with the best available techniques (BAT-AEELs)
Categorisation of combustion plants/units according to their total rated thermal input
1. GENERAL BAT CONCLUSIONS
1.1.
Environmental management systems
BAT 1.
In order to improve the overall environmental performance, BAT is to implement and adhere to an environmental management system (EMS) that incorporates all of the following features:
Applicability
1.2.
Monitoring
BAT 2.
BAT is to determine the net electrical efficiency and/or the net total fuel utilisation and/or the net mechanical energy efficiency of the gasification, IGCC and/or combustion units by carrying out a performance test at full load(
1
), according to EN standards, after the commissioning of the unit and after each modification that could significantly affect the net electrical efficiency and/or the net total fuel utilisation and/or the net mechanical energy efficiency of the unit. If EN standards are not available, BAT is to use ISO, national or other international standards that ensure the provision of data of an equivalent scientific quality.
BAT 3.
BAT is to monitor key process parameters relevant for emissions to air and water including those given below.
Stream |
Parameter(s) |
Monitoring |
Flue-gas |
Flow |
Periodic or continuous determination |
Oxygen content, temperature, and pressure |
Periodic or continuous measurement |
|
Water vapour content(3) |
||
Waste water from flue-gas treatment |
Flow, pH, and temperature |
Continuous measurement |
BAT 4.
BAT is to monitor emissions to air with at least the frequency given below and in accordance with EN standards. If EN standards are not available, BAT is to use ISO, national or other international standards that ensure the provision of data of an equivalent scientific quality.
Substance/Parameter |
Fuel/Process/Type of combustion plant |
Combustion plant total rated thermal input |
Standard(s) (4) |
Minimum monitoring frequency (5) |
Monitoring associated with |
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NH3 |
|
All sizes |
Generic EN standards |
Continuous(6) (7) |
BAT 7 |
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NOX |
|
All sizes |
Generic EN standards |
Continuous(6) (8) |
BAT 20 BAT 24 BAT 28 BAT 32 BAT 37 BAT 41 BAT 42 BAT 43 BAT 47 BAT 48 BAT 56 BAT 64 BAT 65 BAT 73 |
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|
All sizes |
EN 14792 |
Once every year(9) |
BAT 53 |
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N2O |
|
All sizes |
EN 21258 |
Once every year(10) |
BAT 20 BAT 24 |
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CO |
|
All sizes |
Generic EN standards |
Continuous(6) (8) |
BAT 20 BAT 24 BAT 28 BAT 33 BAT 38 BAT 44 BAT 49 BAT 56 BAT 64 BAT 65 BAT 73 |
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|
All sizes |
EN 15058 |
Once every year(9) |
BAT 54 |
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SO2 |
|
All sizes |
Generic EN standards and EN 14791 |
Continuous(6) (11) (12) |
BAT 21 BAT 25 BAT 29 BAT 34 BAT 39 BAT 50 BAT 57 BAT 66 BAT 67 BAT 74 |
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SO3 |
|
All sizes |
No EN standard available |
Once every year |
— |
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Gaseous chlorides, expressed as HCl |
|
All sizes |
EN 1911 |
Once every three months(6) (13) (14) |
BAT 21 BAT 57 |
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|
All sizes |
Generic EN standards |
Continuous(15) (16) |
BAT 25 |
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|
All sizes |
Generic EN standards |
Continuous(6) (16) |
BAT 66 BAT 67 |
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HF |
|
All sizes |
No EN standard available |
Once every three months(6) (13) (14) |
BAT 21 BAT 57 |
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|
All sizes |
No EN standard available |
Once every year |
BAT 25 |
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|
All sizes |
Generic EN standards |
Continuous(6) (16) |
BAT 66 BAT 67 |
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Dust |
|
All sizes |
Generic EN standards and EN 13284-1 and EN 13284-2 |
Continuous(6) (17) |
BAT 22 BAT 26 BAT 30 BAT 35 BAT 39 BAT 51 BAT 58 BAT 75 |
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Waste co-incineration |
All sizes |
Generic EN standards and EN 13284-2 |
Continuous |
BAT 68 BAT 69 |
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Metals and metalloids except mercury (As, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sb, Se, Tl, V, Zn) |
|
All sizes |
EN 14385 |
Once every year(18) |
BAT 22 BAT 26 BAT 30 |
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|
< 300 MWth |
EN 14385 |
Once every six months(13) |
BAT 68 BAT 69 |
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≥ 300 MWth |
EN 14385 |
Once every three months(19) (13) |
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|
≥ 100 MWth |
EN 14385 |
Once every year(18) |
BAT 75 |
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Hg |
|
< 300 MWth |
EN 13211 |
Once every three months(13) (20) |
BAT 23 |
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≥ 300 MWth |
Generic EN standards and EN 14884 |
Continuous(16) (21) |
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|
All sizes |
EN 13211 |
Once every year(22) |
BAT 27 |
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|
All sizes |
EN 13211 |
Once every three months(13) |
BAT 70 |
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|
≥ 100 MWth |
EN 13211 |
Once every year(23) |
BAT 75 |
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TVOC |
|
All sizes |
EN 12619 |
Once every six months(13) |
BAT 33 BAT 59 |
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|
All sizes |
Generic EN standards |
Continuous |
BAT 71 |
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Formaldehyde |
|
All sizes |
No EN standard available |
Once every year |
BAT 45 |
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CH4 |
|
All sizes |
EN ISO 25139 |
Once every year(24) |
BAT 45 |
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PCDD/F |
|
All sizes |
EN 1948-1, EN 1948-2, EN 1948-3 |
Once every six months(13) (25) |
BAT 59 BAT 71 |
BAT 5.
BAT is to monitor emissions to water from flue-gas treatment with at least the frequency given below and in accordance with EN standards. If EN standards are not available, BAT is to use ISO, national or other international standards that ensure the provision of data of an equivalent scientific quality.
Substance/Parameter |
Standard(s) |
Minimum monitoring frequency |
Monitoring associated with |
|
Total organic carbon (TOC)(26) |
EN 1484 |
Once every month |
BAT 15 |
|
Chemical oxygen demand (COD)(26) |
No EN standard available |
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Total suspended solids (TSS) |
EN 872 |
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Fluoride (F-) |
EN ISO 10304-1 |
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Sulphate (SO4 2-) |
EN ISO 10304-1 |
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Sulphide, easily released (S2-) |
No EN standard available |
|||
Sulphite (SO3 2-) |
EN ISO 10304-3 |
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Metals and metalloids |
As |
Various EN standards available (e.g. EN ISO 11885 or EN ISO 17294-2) |
||
Cd |
||||
Cr |
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Cu |
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Ni |
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Pb |
||||
Zn |
||||
Hg |
Various EN standards available (e.g. EN ISO 12846 or EN ISO 17852) |
|||
Chloride (Cl-) |
Various EN standards available (e.g. EN ISO 10304-1 or EN ISO 15682) |
— |
||
Total nitrogen |
EN 12260 |
— |
1.3.
General environmental and combustion performance
BAT 6.
In order to improve the general environmental performance of combustion plants and to reduce emissions to air of CO and unburnt substances, BAT is to ensure optimised combustion and to use an appropriate combination of the techniques given below.
Technique |
Description |
Applicability |
|
a. |
Fuel blending and mixing |
Ensure stable combustion conditions and/or reduce the emission of pollutants by mixing different qualities of the same fuel type |
Generally applicable |
b. |
Maintenance of the combustion system |
Regular planned maintenance according to suppliers’ recommendations |
|
c. |
Advanced control system |
See description in Section 8.1 |
The applicability to old combustion plants may be constrained by the need to retrofit the combustion system and/or control command system |
d. |
Good design of the combustion equipment |
Good design of furnace, combustion chambers, burners and associated devices |
Generally applicable to new combustion plants |
e. |
Fuel choice |
Select or switch totally or partially to another fuel(s) with a better environmental profile (e.g. with low sulphur and/or mercury content) amongst the available fuels, including in start-up situations or when back-up fuels are used |
Applicable within the constraints associated with the availability of suitable types of fuel with a better environmental profile as a whole, which may be impacted by the energy policy of the Member State, or by the integrated site’s fuel balance in the case of combustion of industrial process fuels. For existing combustion plants, the type of fuel chosen may be limited by the configuration and the design of the plant |
BAT 7.
In order to reduce emissions of ammonia to air from the use of selective catalytic reduction (SCR) and/or selective non-catalytic reduction (SNCR) for the abatement of NO
X
emissions, BAT is to optimise the design and/or operation of SCR and/or SNCR (e.g. optimised reagent to NO
X
ratio, homogeneous reagent distribution and optimum size of the reagent drops).
BAT-associated emission levels
BAT 8.
In order to prevent or reduce emissions to air during normal operating conditions, BAT is to ensure, by appropriate design, operation and maintenance, that the emission abatement systems are used at optimal capacity and availability.
BAT 9.
In order to improve the general environmental performance of combustion and/or gasification plants and to reduce emissions to air, BAT is to include the following elements in the quality assurance/quality control programmes for all the fuels used, as part of the environmental management system (see BAT 1):
Description
Fuel(s) |
Substances/Parameters subject to characterisation |
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Biomass/peat |
|
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|
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Coal/lignite |
|
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|
|||||||||
|
|||||||||
HFO |
|
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Gas oil |
|
||||||||
Natural gas |
|
||||||||
Process fuels from the chemical industry(27) |
|
||||||||
Iron and steel process gases |
|
||||||||
Waste(28) |
|
BAT 10.
In order to reduce emissions to air and/or to water during other than normal operating conditions (OTNOC), BAT is to set up and implement a management plan as part of the environmental management system (see BAT 1), commensurate with the relevance of potential pollutant releases, that includes the following elements:
BAT 11.
BAT is to appropriately monitor emissions to air and/or to water during OTNOC.
Description
1.4.
Energy efficiency
BAT 12.
In order to increase the energy efficiency of combustion, gasification and/or IGCC units operated ≥ 1 500 h/yr, BAT is to use an appropriate combination of the techniques given below.
Technique |
Description |
Applicability |
|||||||
a. |
Combustion optimisation |
See description in Section 8.2. Optimising the combustion minimises the content of unburnt substances in the flue-gases and in solid combustion residues |
Generally applicable |
||||||
b. |
Optimisation of the working medium conditions |
Operate at the highest possible pressure and temperature of the working medium gas or steam, within the constraints associated with, for example, the control of NOX emissions or the characteristics of energy demanded |
|||||||
c. |
Optimisation of the steam cycle |
Operate with lower turbine exhaust pressure by utilisation of the lowest possible temperature of the condenser cooling water, within the design conditions |
|||||||
d. |
Minimisation of energy consumption |
Minimising the internal energy consumption (e.g. greater efficiency of the feed-water pump) |
|||||||
e. |
Preheating of combustion air |
Reuse of part of the heat recovered from the combustion flue-gas to preheat the air used in combustion |
Generally applicable within the constraints related to the need to control NOX emissions |
||||||
f. |
Fuel preheating |
Preheating of fuel using recovered heat |
Generally applicable within the constraints associated with the boiler design and the need to control NOX emissions |
||||||
g. |
Advanced control system |
See description in Section 8.2. Computerised control of the main combustion parameters enables the combustion efficiency to be improved |
Generally applicable to new units. The applicability to old units may be constrained by the need to retrofit the combustion system and/or control command system |
||||||
h. |
Feed-water preheating using recovered heat |
Preheat water coming out of the steam condenser with recovered heat, before reusing it in the boiler |
Only applicable to steam circuits and not to hot boilers. Applicability to existing units may be limited due to constraints associated with the plant configuration and the amount of recoverable heat |
||||||
i. |
Heat recovery by cogeneration (CHP) |
Recovery of heat (mainly from the steam system) for producing hot water/steam to be used in industrial processes/activities or in a public network for district heating. Additional heat recovery is possible from:
|
Applicable within the constraints associated with the local heat and power demand. The applicability may be limited in the case of gas compressors with an unpredictable operational heat profile |
||||||
j. |
CHP readiness |
See description in Section 8.2. |
Only applicable to new units where there is a realistic potential for the future use of heat in the vicinity of the unit |
||||||
k. |
Flue-gas condenser |
See description in Section 8.2. |
Generally applicable to CHP units provided there is enough demand for low-temperature heat |
||||||
l. |
Heat accumulation |
Heat accumulation storage in CHP mode |
Only applicable to CHP plants. The applicability may be limited in the case of low heat load demand |
||||||
m. |
Wet stack |
See description in Section 8.2. |
Generally applicable to new and existing units fitted with wet FGD |
||||||
n. |
Cooling tower discharge |
The release of emissions to air through a cooling tower and not via a dedicated stack |
Only applicable to units fitted with wet FGD where reheating of the flue-gas is necessary before release, and where the unit cooling system is a cooling tower |
||||||
o. |
Fuel pre-drying |
The reduction of fuel moisture content before combustion to improve combustion conditions |
Applicable to the combustion of biomass and/or peat within the constraints associated with spontaneous combustion risks (e.g. the moisture content of peat is kept above 40 % throughout the delivery chain). The retrofit of existing plants may be restricted by the extra calorific value that can be obtained from the drying operation and by the limited retrofit possibilities offered by some boiler designs or plant configurations |
||||||
p. |
Minimisation of heat losses |
Minimising residual heat losses, e.g. those that occur via the slag or those that can be reduced by insulating radiating sources |
Only applicable to solid-fuel-fired combustion units and to gasification/IGCC units |
||||||
q. |
Advanced materials |
Use of advanced materials proven to be capable of withstanding high operating temperatures and pressures and thus to achieve increased steam/combustion process efficiencies |
Only applicable to new plants |
||||||
r. |
Steam turbine upgrades |
This includes techniques such as increasing the temperature and pressure of medium-pressure steam, addition of a low-pressure turbine, and modifications to the geometry of the turbine rotor blades |
The applicability may be restricted by demand, steam conditions and/or limited plant lifetime |
||||||
s. |
Supercritical and ultra-supercritical steam conditions |
Use of a steam circuit, including steam reheating systems, in which steam can reach pressures above 220,6 bar and temperatures above 374 °C in the case of supercritical conditions, and above 250 – 300 bar and temperatures above 580 – 600 °C in the case of ultra-supercritical conditions |
Only applicable to new units of ≥ 600 MWth operated > 4 000 h/yr. Not applicable when the purpose of the unit is to produce low steam temperatures and/or pressures in process industries. Not applicable to gas turbines and engines generating steam in CHP mode. For units combusting biomass, the applicability may be constrained by high-temperature corrosion in the case of certain biomasses |
1.5.
Water usage and emissions to water
BAT 13.
In order to reduce water usage and the volume of contaminated waste water discharged, BAT is to use one or both of the techniques given below.
Technique |
Description |
Applicability |
|
a. |
Water recycling |
Residual aqueous streams, including run-off water, from the plant are reused for other purposes. The degree of recycling is limited by the quality requirements of the recipient water stream and the water balance of the plant |
Not applicable to waste water from cooling systems when water treatment chemicals and/or high concentrations of salts from seawater are present |
b. |
Dry bottom ash handling |
Dry, hot bottom ash falls from the furnace onto a mechanical conveyor system and is cooled down by ambient air. No water is used in the process. |
Only applicable to plants combusting solid fuels. There may be technical restrictions that prevent retrofitting to existing combustion plants |
BAT 14.
In order to prevent the contamination of uncontaminated waste water and to reduce emissions to water, BAT is to segregate waste water streams and to treat them separately, depending on the pollutant content.
Description
Applicability
BAT 15.
In order to reduce emissions to water from flue-gas treatment, BAT is to use an appropriate combination of the techniques given below, and to use secondary techniques as close as possible to the source in order to avoid dilution.
Technique |
Typical pollutants prevented/abated |
Applicability |
|
|
Primary techniques |
||
a. |
Optimised combustion (see BAT 6) and flue-gas treatment systems (e.g. SCR/SNCR, see BAT 7) |
Organic compounds, ammonia (NH3) |
Generally applicable |
|
Secondary techniques (29) |
||
b. |
Adsorption on activated carbon |
Organic compounds, mercury (Hg) |
Generally applicable |
c. |
Aerobic biological treatment |
Biodegradable organic compounds, ammonium (NH4 +) |
Generally applicable for the treatment of organic compounds. Aerobic biological treatment of ammonium (NH4 +) may not be applicable in the case of high chloride concentrations (i.e. around 10 g/l) |
d. |
Anoxic/anaerobic biological treatment |
Mercury (Hg), nitrate (NO3 -), nitrite (NO2 -) |
Generally applicable |
e. |
Coagulation and flocculation |
Suspended solids |
Generally applicable |
f. |
Crystallisation |
Metals and metalloids, sulphate (SO4 2-), fluoride (F-) |
Generally applicable |
g. |
Filtration (e.g. sand filtration, microfiltration, ultrafiltration) |
Suspended solids, metals |
Generally applicable |
h. |
Flotation |
Suspended solids, free oil |
Generally applicable |
i. |
Ion exchange |
Metals |
Generally applicable |
j. |
Neutralisation |
Acids, alkalis |
Generally applicable |
k. |
Oxidation |
Sulphide (S2-), sulphite (SO3 2-) |
Generally applicable |
l. |
Precipitation |
Metals and metalloids, sulphate (SO4 2-), fluoride (F-) |
Generally applicable |
m. |
Sedimentation |
Suspended solids |
Generally applicable |
n. |
Stripping |
Ammonia (NH3) |
Generally applicable |
Substance/Parameter |
BAT-AELs |
|
Daily average |
||
Total organic carbon (TOC) |
20 –50 mg/l(30) (31) (32) |
|
Chemical oxygen demand (COD) |
60 –150 mg/l(30) (31) (32) |
|
Total suspended solids (TSS) |
10 –30 mg/l |
|
Fluoride (F-) |
10 –25 mg/l(32) |
|
Sulphate (SO4 2-) |
1,3 –2,0 g/l(32) (33) (34) (35) |
|
Sulphide (S2-), easily released |
0,1 –0,2 mg/l(32) |
|
Sulphite (SO3 2-) |
1 –20 mg/l(32) |
|
Metals and metalloids |
As |
10 –50 μg/l |
Cd |
2 –5 μg/l |
|
Cr |
10 –50 μg/l |
|
Cu |
10 –50 μg/l |
|
Hg |
0,2 –3 μg/l |
|
Ni |
10 –50 μg/l |
|
Pb |
10 –20 μg/l |
|
Zn |
50 –200 μg/l |
1.6.
Waste management
BAT 16.
In order to reduce the quantity of waste sent for disposal from the combustion and/or gasification process and abatement techniques, BAT is to organise operations so as to maximise, in order of priority and taking into account life-cycle thinking:
Technique |
Description |
Applicability |
|
a. |
Generation of gypsum as a by-product |
Quality optimisation of the calcium-based reaction residues generated by the wet FGD so that they can be used as a substitute for mined gypsum (e.g. as raw material in the plasterboard industry). The quality of limestone used in the wet FGD influences the purity of the gypsum produced |
Generally applicable within the constraints associated with the required gypsum quality, the health requirements associated to each specific use, and by the market conditions |
b. |
Recycling or recovery of residues in the construction sector |
Recycling or recovery of residues (e.g. from semi-dry desulphurisation processes, fly ash, bottom ash) as a construction material (e.g. in road building, to replace sand in concrete production, or in the cement industry) |
Generally applicable within the constraints associated with the required material quality (e.g. physical properties, content of harmful substances) associated to each specific use, and by the market conditions |
c. |
Energy recovery by using waste in the fuel mix |
The residual energy content of carbon-rich ash and sludges generated by the combustion of coal, lignite, heavy fuel oil, peat or biomass can be recovered for example by mixing with the fuel |
Generally applicable where plants can accept waste in the fuel mix and are technically able to feed the fuels into the combustion chamber |
d. |
Preparation of spent catalyst for reuse |
Preparation of catalyst for reuse (e.g. up to four times for SCR catalysts) restores some or all of the original performance, extending the service life of the catalyst to several decades. Preparation of spent catalyst for reuse is integrated in a catalyst management scheme |
The applicability may be limited by the mechanical condition of the catalyst and the required performance with respect to controlling NOX and NH3 emissions |
1.7.
Noise emissions
BAT 17.
In order to reduce noise emissions, BAT is to use one or a combination of the techniques given below.
Technique |
Description |
Applicability |
|||||||||||
a. |
Operational measures |
These include:
|
Generally applicable |
||||||||||
b. |
Low-noise equipment |
This potentially includes compressors, pumps and disks |
Generally applicable when the equipment is new or replaced |
||||||||||
c. |
Noise attenuation |
Noise propagation can be reduced by inserting obstacles between the emitter and the receiver. Appropriate obstacles include protection walls, embankments and buildings |
Generally applicable to new plants. In the case of existing plants, the insertion of obstacles may be restricted by lack of space |
||||||||||
d. |
Noise-control equipment |
This includes:
|
The applicability may be restricted by lack of space |
||||||||||
e. |
Appropriate location of equipment and buildings |
Noise levels can be reduced by increasing the distance between the emitter and the receiver and by using buildings as noise screens |
Generally applicable to new plants. In the case of existing plants, the relocation of equipment and production units may be restricted by lack of space or by excessive costs |
2. BAT CONCLUSIONS FOR THE COMBUSTION OF SOLID FUELS
2.1.
BAT conclusions for the combustion of coal and/or lignite
2.1.1.
General environmental performance
BAT 18.
In order to improve the general environmental performance of the combustion of coal and/or lignite, and in addition to BAT 6, BAT is to use the technique given below.
Technique |
Description |
Applicability |
|
a. |
Integrated combustion process ensuring high boiler efficiency and including primary techniques for NOX reduction (e.g. air staging, fuel staging, low-NOX burners (LNB) and/or flue-gas recirculation) |
Combustion processes such as pulverised combustion, fluidised bed combustion or moving grate firing allow this integration |
Generally applicable |
2.1.2.
Energy efficiency
BAT 19.
In order to increase the energy efficiency of the combustion of coal and/or lignite, BAT is to use an appropriate combination of the techniques given in BAT 12 and below.
Technique |
Description |
Applicability |
|
a. |
Dry bottom ash handling |
Dry hot bottom ash falls from the furnace onto a mechanical conveyor system and, after redirection to the furnace for reburning, is cooled down by ambient air. Useful energy is recovered from both the ash reburning and ash cooling |
There may be technical restrictions that prevent retrofitting to existing combustion units |
Type of combustion unit |
BAT-AEELs (36) (37) |
||
Net electrical efficiency (%) (38) |
Net total fuel utilisation (%) (38) (39) (40) |
||
New unit (41) (42) |
Existing unit (41) (43) |
New or existing unit |
|
Coal-fired, ≥ 1 000 MWth |
45 – 46 |
33,5 – 44 |
75 – 97 |
Lignite-fired, ≥ 1 000 MWth |
42 – 44 (44) |
33,5 – 42,5 |
75 – 97 |
Coal-fired, < 1 000 MWth |
36,5 – 41,5 (45) |
32,5 – 41,5 |
75 – 97 |
Lignite-fired, < 1 000 MWth |
36,5 – 40 (46) |
31,5 – 39,5 |
75 – 97 |
2.1.3.
NO
X
, N
2
O and CO emissions to air
BAT 20.
In order to prevent or reduce NO
X
emissions to air while limiting CO and N
2
O emissions to air from the combustion of coal and/or lignite, BAT is to use one or a combination of the techniques given below.
Technique |
Description |
Applicability |
|
a. |
Combustion optimisation |
See description in Section 8.3. Generally used in combination with other techniques |
Generally applicable |
b. |
Combination of other primary techniques for NOX reduction (e.g. air staging, fuel staging, flue-gas recirculation, low-NOX burners (LNB)) |
See description in Section 8.3 for each single technique. The choice and performance of (an) appropriate (combination of) primary techniques may be influenced by the boiler design |
|
c. |
Selective non-catalytic reduction (SNCR) |
See description in Section 8.3. Can be applied with ‘slip’ SCR |
The applicability may be limited in the case of boilers with a high cross-sectional area preventing homogeneous mixing of NH3 and NOX. The applicability may be limited in the case of combustion plants operated < 1 500 h/yr with highly variable boiler loads |
d. |
Selective catalytic reduction (SCR) |
See description in Section 8.3 |
Not applicable to combustion plants of < 300 MWth operated < 500 h/yr. Not generally applicable to combustion plants of < 100 MWth. There may be technical and economic restrictions for retrofitting existing combustion plants operated between 500 h/yr and 1 500 h/yr and for existing combustion plants of ≥ 300 MWth operated < 500 h/yr |
e. |
Combined techniques for NOX and SOX reduction |
See description in Section 8.3 |
Applicable on a case-by-case basis, depending on the fuel characteristics and combustion process |
Combustion plant total rated thermal input (MWth) |
BAT-AELs (mg/Nm3) |
|||
Yearly average |
Daily average or average over the sampling period |
|||
New plant |
Existing plant (47) |
New plant |
Existing plant (48) (49) |
|
< 100 |
100 –150 |
100 –270 |
155 –200 |
165 –330 |
100 –300 |
50 –100 |
100 –180 |
80 –130 |
155 –210 |
≥ 300, FBC boiler combusting coal and/or lignite and lignite-fired PC boiler |
50 – 85 |
< 85 – 150 (50) (51) |
80 – 125 |
140 – 165 (52) |
≥ 300, coal-fired PC boiler |
65 – 85 |
65 – 150 |
80 – 125 |
< 85 – 165 (53) |
Combustion plant total rated thermal input (MWth) |
CO indicative emission level (mg/Nm3 |
< 300 |
< 30 –140 |
≥ 300, FBC boiler combusting coal and/or lignite and lignite-fired PC boiler |
< 30 –100 (54) |
≥ 300, coal-fired PC boiler |
< 5 –100 (54) |
2.1.4.
SO
X
, HCl and HF emissions to air
BAT 21.
In order to prevent or reduce SO
X
, HCl and HF emissions to air from the combustion of coal and/or lignite, BAT is to use one or a combination of the techniques given below.
Technique |
Description |
Applicability |
|
a. |
Boiler sorbent injection (in-furnace or in-bed) |
See description in Section 8.4 |
Generally applicable |
b. |
Duct sorbent injection (DSI) |
See description in Section 8.4. The technique can be used for HCl/HF removal when no specific FGD end-of-pipe technique is implemented |
|
c. |
Spray dry absorber (SDA) |
See description in Section 8.4 |
|
d. |
Circulating fluidised bed (CFB) dry scrubber |
||
e. |
Wet scrubbing |
See description in Section 8.4. The techniques can be used for HCl/HF removal when no specific FGD end-of-pipe technique is implemented |
|
f. |
Wet flue-gas desulphurisation (wet FGD) |
See description in Section 8.4 |
Not applicable to combustion plants operated < 500 h/yr. There may be technical and economic restrictions for applying the technique to combustion plants of < 300 MWth, and for retrofitting existing combustion plants operated between 500 h/yr and 1 500 h/yr |
g. |
Seawater FGD |
||
h. |
Combined techniques for NOX and SOX reduction |
Applicable on a case-by-case basis, depending on the fuel characteristics and combustion process |
|
i. |
Replacement or removal of the gas-gas heater located downstream of the wet FGD |
Replacement of the gas-gas heater downstream of the wet FGD by a multi-pipe heat extractor, or removal and discharge of the flue-gas via a cooling tower or a wet stack |
Only applicable when the heat exchanger needs to be changed or replaced in combustion plants fitted with wet FGD and a downstream gas-gas heater |
j. |
Fuel choice |
See description in Section 8.4. Use of fuel with low sulphur (e.g. down to 0,1 wt-%, dry basis), chlorine or fluorine content |
Applicable within the constraints associated with the availability of different types of fuel, which may be impacted by the energy policy of the Member State. The applicability may be limited due to design constraints in the case of combustion plants combusting highly specific indigenous fuels |
Combustion plant total rated thermal input (MWth) |
BAT-AELs (mg/Nm3) |
|||
Yearly average |
Daily average |
Daily average or average over the sampling period |
||
New plant |
Existing plant (55) |
New plant |
Existing plant (56) |
|
< 100 |
150 –200 |
150 –360 |
170 –220 |
170 –400 |
100 –300 |
80 –150 |
95 –200 |
135 –200 |
135 –220 (57) |
≥ 300 , PC boiler |
10 –75 |
10 –130 (58) |
25 –110 |
25 –165 (59) |
≥ 300 , Fluidised bed boiler(60) |
20 –75 |
20 –180 |
25 –110 |
50 –220 |
Pollutant |
Combustion plant total rated thermal input (MWth) |
BAT-AELs (mg/Nm3) |
|
Yearly average or average of samples obtained during one year |
|||
New plant |
Existing plant (61) |
||
HCl |
< 100 |
1 –6 |
2 –10 (62) |
≥ 100 |
1 –3 |
1 –5 (62) (63) |
|
HF |
< 100 |
< 1 –3 |
< 1 –6 (64) |
≥ 100 |
< 1 –2 |
< 1 –3 (64) |
2.1.5.
Dust and particulate-bound metal emissions to air
BAT 22.
In order to reduce dust and particulate-bound metal emissions to air from the combustion of coal and/or lignite, BAT is to use one or a combination of the techniques given below.
Technique |
Description |
Applicability |
|
a. |
Electrostatic precipitator (ESP) |
See description in Section 8.5 |
Generally applicable |
b. |
Bag filter |
||
c. |
Boiler sorbent injection (in-furnace or in-bed) |
See descriptions in Section 8.5. The techniques are mainly used for SOX, HCl and/or HF control |
|
d. |
Dry or semi-dry FGD system |
||
e. |
Wet flue-gas desulphurisation (wet FGD) |
See applicability in BAT 21 |
Combustion plant total rated thermal input (MWth) |
BAT-AELs (mg/Nm3) |
|||
Yearly average |
Daily average or average over the sampling period |
|||
New plant |
Existing plant (65) |
New plant |
Existing plant (66) |
|
< 100 |
2 –5 |
2 –18 |
4 –16 |
4 –22 (67) |
100 –300 |
2 –5 |
2 –14 |
3 –15 |
4 –22 (68) |
300 –1 000 |
2 –5 |
2 –10 (69) |
3 –10 |
3 –11 (70) |
≥ 1 000 |
2 –5 |
2 –8 |
3 –10 |
3 –11 (71) |
2.1.6.
Mercury emissions to air
BAT 23.
In order to prevent or reduce mercury emissions to air from the combustion of coal and/or lignite, BAT is to use one or a combination of the techniques given below.
Technique |
Description |
Applicability |
|
Co-benefit from techniques primarily used to reduce emissions of other pollutants |
|||
a. |
Electrostatic precipitator (ESP) |
See description in Section 8.5. Higher mercury removal efficiency is achieved at flue-gas temperatures below 130 °C. The technique is mainly used for dust control |
Generally applicable |
b. |
Bag filter |
See description in Section 8.5. The technique is mainly used for dust control |
|
c. |
Dry or semi-dry FGD system |
See descriptions in Section 8.5. The techniques are mainly used for SOX, HCl and/or HF control |
|
d. |
Wet flue-gas desulphurisation (wet FGD) |
See applicability in BAT 21 |
|
e. |
Selective catalytic reduction (SCR) |
See description in Section 8.3. Only used in combination with other techniques to enhance or reduce the mercury oxidation before capture in a subsequent FGD or dedusting system. The technique is mainly used for NOX control |
See applicability in BAT 20 |
Specific techniques to reduce mercury emissions |
|||
f. |
Carbon sorbent (e.g. activated carbon or halogenated activated carbon) injection in the flue-gas |
See description in Section 8.5. Generally used in combination with an ESP/bag filter. The use of this technique may require additional treatment steps to further segregate the mercury-containing carbon fraction prior to further reuse of the fly ash |
Generally applicable |
g. |
Use of halogenated additives in the fuel or injected in the furnace |
See description in Section 8.5 |
Generally applicable in the case of a low halogen content in the fuel |
h. |
Fuel pretreatment |
Fuel washing, blending and mixing in order to limit/reduce the mercury content or improve mercury capture by pollution control equipment |
Applicability is subject to a previous survey for characterising the fuel and for estimating the potential effectiveness of the technique |
i. |
Fuel choice |
See description in Section 8.5 |
Applicable within the constraints associated with the availability of different types of fuel, which may be impacted by the energy policy of the Member State |
Combustion plant total rated thermal input (MWth) |
BAT-AELs (μg/Nm3) |
|||
Yearly average or average of samples obtained during one year |
||||
New plant |
Existing plant (72) |
|||
coal |
lignite |
coal |
lignite |
|
< 300 |
< 1 –3 |
< 1 –5 |
< 1 –9 |
< 1 –10 |
≥ 300 |
< 1 –2 |
< 1 –4 |
< 1 –4 |
< 1 –7 |
2.2.
BAT conclusions for the combustion of solid biomass and/or peat
2.2.1.
Energy efficiency
Type of combustion unit |
BAT-AEELs (73) (74) |
|||
Net electrical efficiency (%) (75) |
Net total fuel utilisation (%) (76) (77) |
|||
New unit (78) |
Existing unit |
New unit |
Existing unit |
|
Solid biomass and/or peat boiler |
33,5 –to > 38 |
28 –38 |
73 –99 |
73 –99 |
2.2.2.
NO
X
, N
2
O and CO emissions to air
BAT 24.
In order to prevent or reduce NO
X
emissions to air while limiting CO and N
2
O emissions to air from the combustion of solid biomass and/or peat, BAT is to use one or a combination of the techniques given below.
Technique |
Description |
Applicability |
|
a. |
Combustion optimisation |
See descriptions in Section 8.3 |
Generally applicable |
b. |
Low-NOX burners (LNB) |
||
c. |
Air staging |
||
d. |
Fuel staging |
||
e. |
Flue-gas recirculation |
||
f. |
Selective non-catalytic reduction (SNCR) |
See description in Section 8.3. Can be applied with ‘slip’ SCR |
Not applicable to combustion plants operated < 500 h/yr with highly variable boiler loads. The applicability may be limited in the case of combustion plants operated between 500 h/yr and 1 500 h/yr with highly variable boiler loads. For existing combustion plants, applicable within the constraints associated with the required temperature window and residence time for the injected reactants |
g. |
Selective catalytic reduction (SCR) |
See description in Section 8.3. The use of high-alkali fuels (e.g. straw) may require the SCR to be installed downstream of the dust abatement system |
Not applicable to combustion plants operated < 500 h/yr. There may be economic restrictions for retrofitting existing combustion plants of < 300 MWth. Not generally applicable to existing combustion plants of < 100 MWth |
Combustion plant total rated thermal input (MWth) |
BAT-AELs (mg/Nm3) |
|||
Yearly average |
Daily average or average over the sampling period |
|||
New plant |
Existing plant (79) |
New plant |
Existing plant (80) |
|
50 –100 |
70 –150 (81) |
70 –225 (82) |
120 –200 (83) |
120 –275 (84) |
100 –300 |
50 –140 |
50 –180 |
100 –200 |
100 –220 |
≥ 300 |
40 –140 |
40 –150 (85) |
65 –150 |
95 –165 (86) |
2.2.3.
SO
X,
HCl and HF emissions to air
BAT 25.
In order to prevent or reduce SO
X
, HCl and HF emissions to air from the combustion of solid biomass and/or peat, BAT is to use one or a combination of the techniques given below.
Technique |
Description |
Applicability |
|
a. |
Boiler sorbent injection (in-furnace or in-bed) |
See descriptions in Section 8.4 |
Generally applicable |
b. |
Duct sorbent injection (DSI) |
||
c. |
Spray dry absorber (SDA) |
||
d. |
Circulating fluidised bed (CFB) dry scrubber |
||
e. |
Wet scrubbing |
||
f. |
Flue-gas condenser |
||
g. |
Wet flue-gas desulphurisation (wet FGD) |
Not applicable to combustion plants operated < 500 h/yr. There may be technical and economic restrictions for retrofitting existing combustion plants operated between 500 h/yr and 1 500 h/yr |
|
h. |
Fuel choice |
Applicable within the constraints associated with the availability of different types of fuel, which may be impacted by the energy policy of the Member State |
Combustion plant total rated thermal input (MWth) |
BAT-AELs for SO2 (mg/Nm3) |
|||
Yearly average |
Daily average or average over the sampling period |
|||
New plant |
Existing plant (87) |
New plant |
Existing plant (88) |
|
< 100 |
15 –70 |
15 –100 |
30 –175 |
30 –215 |
100 –300 |
< 10 –50 |
< 10 –70 (89) |
< 20 –85 |
< 20 –175 (90) |
≥ 300 |
< 10 –35 |
< 10 –50 (89) |
< 20 –70 |
< 20 –85 (91) |
Combustion plant total rated thermal input (MWth) |
BAT-AELs for HCl (mg/Nm3) (92) (93) |
BAT-AELs for HF (mg/Nm3) |
||||
Yearly average or average of samples obtained during one year |
Daily average or average over the sampling period |
Average over the sampling period |
||||
New plant |
Existing plant (94) (95) |
New plant |
Existing plant (96) |
New plant |
Existing plant (96) |
|
< 100 |
1 –7 |
1 –15 |
1 –12 |
1 –35 |
< 1 |
< 1,5 |
100 –300 |
1 –5 |
1 –9 |
1 –12 |
1 –12 |
< 1 |
< 1 |
≥ 300 |
1 –5 |
1 –5 |
1 –12 |
1 –12 |
< 1 |
< 1 |
2.2.4.
Dust and particulate-bound metal emissions to air
BAT 26.
In order to reduce dust and particulate-bound metal emissions to air from the combustion of solid biomass and/or peat, BAT is to use one or a combination of the techniques given below.
Technique |
Description |
Applicability |
|
a. |
Electrostatic precipitator (ESP) |
See description in Section 8.5 |
Generally applicable |
b. |
Bag filter |
||
c. |
Dry or semi-dry FGD system |
See descriptions in Section 8.5 The techniques are mainly used for SOX, HCl and/or HF control |
|
d. |
Wet flue-gas desulphurisation (wet FGD) |
See applicability in BAT 25 |
|
e. |
Fuel choice |
See description in Section 8.5 |
Applicable within the constraints associated with the availability of different types of fuel, which may be impacted by the energy policy of the Member State |
Combustion plant total rated thermal input (MWth) |
BAT-AELs for dust (mg/Nm3) |
|||
Yearly average |
Daily average or average over the sampling period |
|||
New plant |
Existing plant (97) |
New plant |
Existing plant (98) |
|
< 100 |
2 –5 |
2 –15 |
2 –10 |
2 –22 |
100 –300 |
2 –5 |
2 –12 |
2 –10 |
2 –18 |
≥ 300 |
2 –5 |
2 –10 |
2 –10 |
2 –16 |
2.2.5.
Mercury emissions to air
BAT 27.
In order to prevent or reduce mercury emissions to air from the combustion of solid biomass and/or peat, BAT is to use one or a combination of the techniques given below.
Technique |
Description |
Applicability |
|
Specific techniques to reduce mercury emissions |
|||
a. |
Carbon sorbent (e.g. activated carbon or halogenated activated carbon) injection in the flue-gas |
See descriptions in Section 8.5 |
Generally applicable |
b. |
Use of halogenated additives in the fuel or injected in the furnace |
Generally applicable in the case of a low halogen content in the fuel |
|
c. |
Fuel choice |
Applicable within the constraints associated with the availability of different types of fuel, which may be impacted by the energy policy of the Member State |
|
Co-benefit from techniques primarily used to reduce emissions of other pollutants |
|||
d. |
Electrostatic precipitator (ESP) |
See descriptions in Section 8.5. The techniques are mainly used for dust control |
Generally applicable |
e. |
Bag filter |
||
f. |
Dry or semi-dry FGD system |
See descriptions in Section 8.5. The techniques are mainly used for SOX, HCl and/or HF control |
|
g. |
Wet flue-gas desulphurisation (wet FGD) |
See applicability in BAT 25 |
3. BAT CONCLUSIONS FOR THE COMBUSTION OF LIQUID FUELS
3.1.
HFO- and/or gas-oil-fired boilers
3.1.1.
Energy efficiency
Type of combustion unit |
BAT-AEELs (99) (100) |
|||
Net electrical efficiency (%) |
Net total fuel utilisation (%) (101) |
|||
New unit |
Existing unit |
New unit |
Existing unit |
|
HFO- and/or gas-oil-fired boiler |
> 36,4 |
35,6 –37,4 |
80 –96 |
80 –96 |
3.1.2.
NO
X
and CO emissions to air
BAT 28.
In order to prevent or reduce NO
X
emissions to air while limiting CO emissions to air from the combustion of HFO and/or gas oil in boilers, BAT is to use one or a combination of the techniques given below.
Technique |
Description |
Applicability |
|
a. |
Air staging |
See descriptions in Section 8.3 |
Generally applicable |
b. |
Fuel staging |
||
c. |
Flue-gas recirculation |
||
d. |
Low-NOX burners (LNB) |
||
e. |
Water/steam addition |
Applicable within the constraints of water availability |
|
f. |
Selective non-catalytic reduction (SNCR) |
Not applicable to combustion plants operated < 500 h/yr with highly variable boiler loads. The applicability may be limited in the case of combustion plants operated between 500 h/yr and 1 500 h/yr with highly variable boiler loads |
|
g. |
Selective catalytic reduction (SCR) |
See descriptions in Section 8.3 |
Not applicable to combustion plants operated < 500 h/yr. There may be technical and economic restrictions for retrofitting existing combustion plants operated between 500 h/yr and 1 500 h/yr. Not generally applicable to combustion plants of < 100 MWth |
h. |
Advanced control system |
Generally applicable to new combustion plants. The applicability to old combustion plants may be constrained by the need to retrofit the combustion system and/or control command system |
|
i. |
Fuel choice |
Applicable within the constraints associated with the availability of different types of fuel, which may be impacted by the energy policy of the Member State |
Combustion plant total rated thermal input (MWth) |
BAT-AELs (mg/Nm3) |
|||
Yearly average |
Daily average or average over the sampling period |
|||
New plant |
Existing plant (102) |
New plant |
Existing plant (103) |
|
< 100 |
75 –200 |
150 –270 |
100 –215 |
210 –330 (104) |
≥ 100 |
45 –75 |
45 –100 (105) |
85 –100 |
85 –110 (106) (107) |
3.1.3.
SO
X
, HCl and HF emissions to air
BAT 29.
In order to prevent or reduce SO
X
, HCl and HF emissions to air from the combustion of HFO and/or gas oil in boilers, BAT is to use one or a combination of the techniques given below.
Technique |
Description |
Applicability |
|
a. |
Duct sorbent injection (DSI) |
See description in Section 8.4 |
Generally applicable |
b. |
Spray dry absorber (SDA) |
||
c. |
Flue-gas condenser |
||
d. |
Wet flue-gas desulphurisation (wet FGD) |
There may be technical and economic restrictions for applying the technique to combustion plants of < 300 MWth. Not applicable to combustion plants operated < 500 h/yr. There may be technical and economic restrictions for retrofitting existing combustion plants operated between 500 h/yr and 1 500 h/yr |
|
e. |
Seawater FGD |
There may be technical and economic restrictions for applying the technique to combustion plants of < 300 MWth. Not applicable to combustion plants operated < 500 h/yr. There may be technical and economic restrictions for retrofitting existing combustion plants operated between 500 h/yr and 1 500 h/yr |
|
f. |
Fuel choice |
Applicable within the constraints associated with the availability of different types of fuel, which may be impacted by the energy policy of the Member State |
Combustion plant total rated thermal input (MWth) |
BAT-AELs for SO2 (mg/Nm3) |
|||
Yearly average |
Daily average or average over the sampling period |
|||
New plant |
Existing plant (108) |
New plant |
Existing plant (109) |
|
< 300 |
50 –175 |
50 –175 |
150 –200 |
150 –200 (110) |
≥ 300 |
35 –50 |
50 –110 |
50 –120 |
150 –165 (111) (112) |
3.1.4.
Dust and particulate-bound metal emissions to air
BAT 30.
In order to reduce dust and particulate-bound metal emissions to air from the combustion of HFO and/or gas oil in boilers, BAT is to use one or a combination of the techniques given below.
Technique |
Description |
Applicability |
|
a. |
Electrostatic precipitator (ESP) |
See description in Section 8.5 |
Generally applicable |
b. |
Bag filter |
||
c. |
Multicyclones |
See description in Section 8.5. Multicyclones can be used in combination with other dedusting techniques |
|
d. |
Dry or semi-dry FGD system |
See descriptions in Section 8.5. The technique is mainly used for SOX, HCl and/or HF control |
|
e. |
Wet flue-gas desulphurisation (wet FGD) |
See description in Section 8.5. The technique is mainly used for SOX, HCl and/or HF control |
See applicability in BAT 29 |
f. |
Fuel choice |
See description in Section 8.5 |
Applicable within the constraints associated with the availability of different types of fuel, which may be impacted by the energy policy of the Member State |
Combustion plant total rated thermal input (MWth) |
BAT-AELs for dust (mg/Nm3) |
|||
Yearly average |
Daily average or average over the sampling period |
|||
New plant |
Existing plant (113) |
New plant |
Existing plant (114) |
|
< 300 |
2 –10 |
2 –20 |
7 –18 |
7 –22 (115) |
≥ 300 |
2 –5 |
2 –10 |
7 –10 |
7 –11 (116) |
3.2.
HFO- and/or gas-oil-fired engines
3.2.1.
Energy efficiency
BAT 31.
In order to increase the energy efficiency of HFO and/or gas oil combustion in reciprocating engines, BAT is to use an appropriate combination of the techniques given in BAT 12 and below.
Technique |
Description |
Applicability |
|
a. |
Combined cycle |
See description in Section 8.2 |
Generally applicable to new units operated ≥ 1 500 h/yr. Applicable to existing units within the constraints associated with the steam cycle design and the space availability. Not applicable to existing units operated < 1 500 h/yr |
Type of combustion unit |
BAT-AEELs (117) |
|
Net electrical efficiency (%) (118) |
||
New unit |
Existing unit |
|
HFO- and/or gas-oil-fired reciprocating engine – single cycle |
41,5 –44,5 (119) |
38,3 –44,5 (119) |
HFO- and/or gas-oil-fired reciprocating engine – combined cycle |
> 48 (120) |
No BAT-AEEL |
3.2.2.
NO
X
, CO and volatile organic compound emissions to air
BAT 32.
In order to prevent or reduce NO
X
emissions to air from the combustion of HFO and/or gas oil in reciprocating engines, BAT is to use one or a combination of the techniques given below.
Technique |
Description |
Applicability |
|
a. |
Low-NOX combustion concept in diesel engines |
See descriptions in Section 8.3 |
Generally applicable |
b. |
Exhaust-gas recirculation (EGR) |
Not applicable to four-stroke engines |
|
c. |
Water/steam addition |
Applicable within the constraints of water availability. The applicability may be limited where no retrofit package is available |
|
d. |
Selective catalytic reduction (SCR) |
Not applicable to combustion plants operated < 500 h/yr. There may be technical and economic restrictions for retrofitting existing combustion plants operated between 500 h/yr and 1 500 h/yr. Retrofitting existing combustion plants may be constrained by the availability of sufficient space |
BAT 33.
In order to prevent or reduce emissions of CO and volatile organic compounds to air from the combustion of HFO and/or gas oil in reciprocating engines, BAT is to use one or both of the techniques given below.
Technique |
Description |
Applicability |
|
a. |
Combustion optimisation |
|
Generally applicable |
b. |
Oxidation catalysts |
See descriptions in Section 8.3 |
Not applicable to combustion plants operated < 500 h/yr. The applicability may be limited by the sulphur content of the fuel |
Combustion plant total rated thermal input (MWth) |
BAT-AELs (mg/Nm3) |
|||
Yearly average |
Daily average or average over the sampling period |
|||
New plant |
Existing plant (121) |
New plant |
Existing plant (122) (123) |
|
≥ 50 |
115 –190 (124) |
125 –625 |
145 –300 |
150 –750 |
3.2.3.
SO
X
, HCl and HF emissions to air
BAT 34.
In order to prevent or reduce SO
X
, HCl and HF emissions to air from the combustion of HFO and/or gas oil in reciprocating engines, BAT is to use one or a combination of the techniques given below.
Technique |
Description |
Applicability |
|
a. |
Fuel choice |
See descriptions in Section 8.4 |
Applicable within the constraints associated with the availability of different types of fuel, which may be impacted by the energy policy of the Member State |
b. |
Duct sorbent injection (DSI) |
There may be technical restrictions in the case of existing combustion plants Not applicable to combustion plants operated < 500 h/yr |
|
c. |
Wet flue-gas desulphurisation (wet FGD) |
There may be technical and economic restrictions for applying the technique to combustion plants of < 300 MWth. Not applicable to combustion plants operated < 500 h/yr. There may be technical and economic restrictions for retrofitting existing combustion plants operated between 500 h/yr and 1 500 h/yr |
Combustion plant total rated thermal input (MWth) |
BAT-AELs for SO2 (mg/Nm3) |
|||
Yearly average |
Daily average or average over the sampling period |
|||
New plant |
Existing plant (125) |
New plant |
Existing plant (126) |
|
All sizes |
45 –100 |
100 –200 (127) |
60 –110 |
105 –235 (127) |
3.2.4.
Dust and particulate-bound metal emissions to air
BAT 35.
In order to prevent or reduce dust and particulate-bound metal emissions from the combustion of HFO and/or gas oil in reciprocating engines, BAT is to use one or a combination of the techniques given below.
Technique |
Description |
Applicability |
|
a. |
Fuel choice |
See descriptions in Section 8.5 |
Applicable within the constraints associated with the availability of different types of fuel, which may be impacted by the energy policy of the Member State |
b. |
Electrostatic precipitator (ESP) |
Not applicable to combustion plants operated < 500 h/yr |
|
c. |
Bag filter |
Combustion plant total rated thermal input (MWth) |
BAT-AELs for dust (mg/Nm3) |
|||
Yearly average |
Daily average or average over the sampling period |
|||
New plant |
Existing plant (128) |
New plant |
Existing plant (129) |
|
≥ 50 |
5 –10 |
5 –35 |
10 –20 |
10 –45 |
3.3.
Gas-oil-fired gas turbines
3.3.1.
Energy efficiency
BAT 36.
In order to increase the energy efficiency of gas oil combustion in gas turbines, BAT is to use an appropriate combination of the techniques given in BAT 12 and below.
Technique |
Description |
Applicability |
|
a. |
Combined cycle |
See description in Section 8.2 |
Generally applicable to new units operated ≥ 1 500 h/yr. Applicable to existing units within the constraints associated with the steam cycle design and the space availability. Not applicable to existing units operated < 1 500 h/yr |
Type of combustion unit |
BAT-AEELs (130) |
|
Net electrical efficiency (%) (131) |
||
New unit |
Existing unit |
|
Gas-oil-fired open-cycle gas turbine |
> 33 |
25 –35,7 |
Gas-oil-fired combined cycle gas turbine |
> 40 |
33 –44 |
3.3.2.
NO
X
and CO emissions to air
BAT 37.
In order to prevent or reduce NO
X
emissions to air from the combustion of gas oil in gas turbines, BAT is to use one or a combination of the techniques given below.
Technique |
Description |
Applicability |
|
a. |
Water/steam addition |
See description in Section 8.3 |
The applicability may be limited due to water availability |
b. |
Low-NOX burners (LNB) |
Only applicable to turbine models for which low-NOX burners are available on the market |
|
c. |
Selective catalytic reduction (SCR) |
Not applicable to combustion plants operated < 500 h/yr. There may be technical and economic restrictions for retrofitting existing combustion plants operated between 500 h/yr and 1 500 h/yr. Retrofitting existing combustion plants may be constrained by the availability of sufficient space |
BAT 38.
In order to prevent or reduce CO emissions to air from the combustion of gas oil in gas turbines, BAT is to use one or a combination of the techniques given below.
Technique |
Description |
Applicability |
|
a. |
Combustion optimisation |
See description in Section 8.3 |
Generally applicable |
b. |
Oxidation catalysts |
Not applicable to combustion plants operated < 500 h/yr. Retrofitting existing combustion plants may be constrained by the availability of sufficient space |
3.3.3.
SO
X
and dust emissions to air
BAT 39.
In order to prevent or reduce SO
X
and dust emissions to air from the combustion of gas oil in gas turbines, BAT is to use the technique given below.
Technique |
Description |
Applicability |
|
a. |
Fuel choice |
See description in Section 8.4 |
Applicable within the constraints associated with the availability of different types of fuel, which may be impacted by the energy policy of the Member State |
Type of combustion plant |
BAT-AELs (mg/Nm3) |
|||
SO2 |
Dust |
|||
Yearly average (132) |
Daily average or average over the sampling period (133) |
Yearly average (132) |
Daily average or average over the sampling period (133) |
|
New and existing plants |
35 –60 |
50 –66 |
2 –5 |
2 –10 |
4. BAT CONCLUSIONS FOR THE COMBUSTION OF GASEOUS FUELS
4.1.
BAT conclusions for the combustion of natural gas
4.1.1.
Energy efficiency
BAT 40.
In order to increase the energy efficiency of natural gas combustion, BAT is to use an appropriate combination of the techniques given in BAT 12 and below.
Technique |
Description |
Applicability |
|
a. |
Combined cycle |
See description in Section 8.2 |
Generally applicable to new gas turbines and engines except when operated < 1 500 h/yr. Applicable to existing gas turbines and engines within the constraints associated with the steam cycle design and the space availability. Not applicable to existing gas turbines and engines operated < 1 500 h/yr. Not applicable to mechanical drive gas turbines operated in discontinuous mode with extended load variations and frequent start-ups and shutdowns. Not applicable to boilers |
Type of combustion unit |
BAT-AEELs (134) (135) |
||||
Net electrical efficiency (%) |
Net total fuel utilisation (%) (136) (137) |
Net mechanical energy efficiency (%) (137) (138) |
|||
New unit |
Existing unit |
New unit |
Existing unit |
||
Gas engine |
39,5 –44 (139) |
35 –44 (139) |
56 –85 (139) |
No BAT-AEEL. |
|
Gas-fired boiler |
39 –42,5 |
38 –40 |
78 –95 |
No BAT-AEEL. |
|
Open cycle gas turbine, ≥ 50 MWth |
36 –41,5 |
33 –41,5 |
No BAT-AEEL |
36,5 –41 |
33,5 –41 |
Combined cycle gas turbine (CCGT) |
|||||
CCGT, 50–600 MWth |
53 –58,5 |
46 –54 |
No BAT-AEEL |
No BAT-AEEL |
|
CCGT, ≥ 600 MWth |
57 –60,5 |
50 –60 |
No BAT-AEEL |
No BAT-AEEL |
|
CHP CCGT, 50–600 MWth |
53 –58,5 |
46 –54 |
65 –95 |
No BAT-AEEL |
|
CHP CCGT, ≥ 600 MWth |
57 –60,5 |
50 –60 |
65 –95 |
No BAT-AEEL |
4.1.2.
NO
X
, CO, NMVOC and CH
4
emissions to air
BAT 41.
In order to prevent or reduce NO
X
emissions to air from the combustion of natural gas in boilers, BAT is to use one or a combination of the techniques given below.
Technique |
Description |
Applicability |
|
a. |
Air and/or fuel staging |
See descriptions in Section 8.3. Air staging is often associated with low-NOX burners |
Generally applicable |
b. |
Flue-gas recirculation |
See description in Section 8.3 |
|
c. |
Low-NOX burners (LNB) |
||
d. |
Advanced control system |
See description in Section 8.3. This technique is often used in combination with other techniques or may be used alone for combustion plants operated < 500 h/yr |
The applicability to old combustion plants may be constrained by the need to retrofit the combustion system and/or control command system |
e. |
Reduction of the combustion air temperature |
See description in Section 8.3 |
Generally applicable within the constraints associated with the process needs |
f. |
Selective non–catalytic reduction (SNCR) |
Not applicable to combustion plants operated < 500 h/yr with highly variable boiler loads. The applicability may be limited in the case of combustion plants operated between 500 h/yr and 1 500 h/yr with highly variable boiler loads |
|
g. |
Selective catalytic reduction (SCR) |
Not applicable to combustion plants operated < 500 h/yr. Not generally applicable to combustion plants of < 100 MWth. There may be technical and economic restrictions for retrofitting existing combustion plants operated between 500 h/yr and 1 500 h/yr |
BAT 42.
In order to prevent or reduce NO
X
emissions to air from the combustion of natural gas in gas turbines, BAT is to use one or a combination of the techniques given below.
Technique |
Description |
Applicability |
|
a. |
Advanced control system |
See description in Section 8.3. This technique is often used in combination with other techniques or may be used alone for combustion plants operated < 500 h/yr |
The applicability to old combustion plants may be constrained by the need to retrofit the combustion system and/or control command system |
b. |
Water/steam addition |
See description in Section 8.3 |
The applicability may be limited due to water availability |
c. |
Dry low-NOX burners (DLN) |
The applicability may be limited in the case of turbines where a retrofit package is not available or when water/steam addition systems are installed |
|
d. |
Low-load design concept |
Adaptation of the process control and related equipment to maintain good combustion efficiency when the demand in energy varies, e.g. by improving the inlet airflow control capability or by splitting the combustion process into decoupled combustion stages |
The applicability may be limited by the gas turbine design |
e. |
Low-NOX burners (LNB) |
See description in Section 8.3 |
Generally applicable to supplementary firing for heat recovery steam generators (HRSGs) in the case of combined-cycle gas turbine (CCGT) combustion plants |
f. |
Selective catalytic reduction (SCR) |
Not applicable in the case of combustion plants operated < 500 h/yr. Not generally applicable to existing combustion plants of < 100 MWth. Retrofitting existing combustion plants may be constrained by the availability of sufficient space. There may be technical and economic restrictions for retrofitting existing combustion plants operated between 500 h/yr and 1 500 h/yr |
BAT 43.
In order to prevent or reduce NO
X
emissions to air from the combustion of natural gas in engines, BAT is to use one or a combination of the techniques given below.
Technique |
Description |
Applicability |
|
a. |
Advanced control system |
See description in Section 8.3. This technique is often used in combination with other techniques or may be used alone for combustion plants operated < 500 h/yr |
The applicability to old combustion plants may be constrained by the need to retrofit the combustion system and/or control command system |
b. |
Lean-burn concept |
See description in Section 8.3. Generally used in combination with SCR |
Only applicable to new gas-fired engines |
c. |
Advanced lean-burn concept |
See descriptions in Section 8.3 |
Only applicable to new spark plug ignited engines |
d. |
Selective catalytic reduction (SCR) |
Retrofitting existing combustion plants may be constrained by the availability of sufficient space. Not applicable to combustion plants operated < 500 h/yr. There may be technical and economic restrictions for retrofitting existing combustion plants operated between 500 h/yr and 1 500 h/yr |
BAT 44.
In order to prevent or reduce CO emissions to air from the combustion of natural gas, BAT is to ensure optimised combustion and/or to use oxidation catalysts.
Description
Type of combustion plant |
Combustion plant total rated thermal input (MWth) |
BAT-AELs (mg/Nm3) (140) (141) |
|
Yearly average (142) (143) |
Daily average or average over the sampling period |
||
Open-cycle gas turbines (OCGTs) (144) (145) |
|||
New OCGT |
≥ 50 |
15 –35 |
25 –50 |
Existing OCGT (excluding turbines for mechanical drive applications) – All but plants operated < 500 h/yr |
≥ 50 |
15 –50 |
25 –55 (146) |
Combined-cycle gas turbines (CCGTs) (144) (147) |
|||
New CCGT |
≥ 50 |
10 –30 |
15 –40 |
Existing CCGT with a net total fuel utilisation of < 75 % |
≥ 600 |
10 –40 |
18 –50 |
Existing CCGT with a net total fuel utilisation of ≥ 75 % |
≥ 600 |
10 –50 |
18 –55 (148) |
Existing CCGT with a net total fuel utilisation of < 75 % |
50 –600 |
10 –45 |
35 –55 |
Existing CCGT with a net total fuel utilisation of ≥ 75 % |
50 –600 |
25 –50 (149) |
35 –55 (150) |
Open- and combined-cycle gas turbines |
|||
Gas turbine put into operation no later than 27 November 2003, or existing gas turbine for emergency use and operated < 500 h/yr |
≥ 50 |
No BAT-AEL |
60 –140 (151) (152) |
Existing gas turbine for mechanical drive applications – All but plants operated < 500 h/yr |
≥ 50 |
15 –50 (153) |
25 –55 (154) |
Type of combustion plant |
BAT-AELs (mg/Nm3) |
|||
Yearly average (155) |
Daily average or average over the sampling period |
|||
New plant |
Existing plant (156) |
New plant |
Existing plant (157) |
|
Boiler |
10 –60 |
50 –100 |
30 –85 |
85 –110 |
Engine(158) |
20 –75 |
20 –100 |
55 –85 |
55 –110 (159) |
BAT 45.
In order to reduce non-methane volatile organic compounds (NMVOC) and methane (CH
4
) emissions to air from the combustion of natural gas in spark-ignited lean-burn gas engines, BAT is to ensure optimised combustion and/or to use oxidation catalysts.
Description
Combustion plant total rated thermal input (MWth) |
BAT-AELs (mg/Nm3) |
||
Formaldehyde |
CH4 |
||
Average over the sampling period |
|||
New or existing plant |
New plant |
Existing plant |
|
≥ 50 |
5 –15 (160) |
215 –500 (161) |
215 –560 (160) (161) |
4.2.
BAT conclusions for the combustion of iron and steel process gases
4.2.1.
Energy efficiency
BAT 46.
In order to increase the energy efficiency of the combustion of iron and steel process gases, BAT is to use an appropriate combination of the techniques given in BAT 12 and below.
Technique |
Description |
Applicability |
|
a. |
Process gas management system |
See description in Section 8.2 |
Only applicable to integrated steelworks |
Type of combustion unit |
BAT-AEELs (162) (163) |
|
Net electrical efficiency (%) |
Net total fuel utilisation (%) (164) |
|
Existing multi-fuel firing gas boiler |
30 –40 |
50 –84 |
New multi-fuel firing gas boiler(165) |
36 –42,5 |
50 –84 |
Type of combustion unit |
BAT-AEELs (166) (167) |
||
Net electrical efficiency (%) |
Net total fuel utilisation (%) (168) |
||
New unit |
Existing unit |
||
CHP CCGT |
> 47 |
40 –48 |
60 –82 |
CCGT |
> 47 |
40 –48 |
No BAT-AEEL |
4.2.2.
NO
X
and CO emissions to air
BAT 47.
In order to prevent or reduce NO
X
emissions to air from the combustion of iron and steel process gases in boilers, BAT is to use one or a combination of the techniques given below.
Technique |
Description |
Applicability |
|
a. |
Low-NOX burners (LNB) |
See description in Section 8.3. Specially designed low-NOX burners in multiple rows per type of fuel or including specific features for multi-fuel firing (e.g. multiple dedicated nozzles for burning different fuels, or including fuels premixing) |
Generally applicable |
b. |
Air staging |
See descriptions in Section 8.3 |
|
c. |
Fuel staging |
||
d. |
Flue-gas recirculation |
||
e. |
Process gas management system |
See description in Section 8.2. |
Generally applicable within the constraints associated with the availability of different types of fuel |
f. |
Advanced control system |
See description in Section 8.3. This technique is used in combination with other techniques |
The applicability to old combustion plants may be constrained by the need to retrofit the combustion system and/or control command system |
g. |
Selective non-catalytic reduction (SNCR) |
See descriptions in Section 8.3 |
Not applicable to combustion plants operated < 500 h/yr |
h. |
Selective catalytic reduction (SCR) |
Not applicable to combustion plants operated < 500 h/yr. Not generally applicable to combustion plants of < 100 MWth. Retrofitting existing combustion plants may be constrained by the availability of sufficient space and by the combustion plant configuration |
BAT 48.
In order to prevent or reduce NO
X
emissions to air from the combustion of iron and steel process gases in CCGTs, BAT is to use one or a combination of the techniques given below.
Technique |
Description |
Applicability |
|
a. |
Process gas management system |
See description in Section 8.2 |
Generally applicable within the constraints associated with the availability of different types of fuel |
b. |
Advanced control system |
See description in Section 8.3. This technique is used in combination with other techniques |
The applicability to old combustion plants may be constrained by the need to retrofit the combustion system and/or control command system |
c. |
Water/steam addition |
See description in Section 8.3. In dual fuel gas turbines using DLN for the combustion of iron and steel process gases, water/steam addition is generally used when combusting natural gas |
The applicability may be limited due to water availability |
d. |
Dry low-NOX burners(DLN) |
See description in Section 8.3. DLN that combust iron and steel process gases differ from those that combust natural gas only |
Applicable within the constraints associated with the reactiveness of iron and steel process gases such as coke oven gas. The applicability may be limited in the case of turbines where a retrofit package is not available or when water/steam addition systems are installed |
e. |
Low-NOX burners (LNB) |
See description in Section 8.3 |
Only applicable to supplementary firing for heat recovery steam generators (HRSGs) of combined-cycle gas turbine (CCGT) combustion plants |
f. |
Selective catalytic reduction (SCR) |
Retrofitting existing combustion plants may be constrained by the availability of sufficient space |
BAT 49.
In order to prevent or reduce CO emissions to air from the combustion of iron and steel process gases, BAT is to use one or a combination of the techniques given below.
|
Technique |
Description |
Applicability |
a. |
Combustion optimisation |
See descriptions in Section 8.3 |
Generally applicable |
b. |
Oxidation catalysts |
Only applicable to CCGTs. The applicability may be limited by lack of space, the load requirements and the sulphur content of the fuel |
Type of combustion plant |
O2 reference level (vol-%) |
BAT-AELs (mg/Nm3) (169) |
|
Yearly average |
Daily average or average over the sampling period |
||
New boiler |
3 |
15 –65 |
22 –100 |
Existing boiler |
3 |
20 –100 (170) (171) |
22 –110 (170) (172) (173) |
New CCGT |
15 |
20 –35 |
30 –50 |
Existing CCGT |
15 |
20 –50 (170) (171) |
30 –55 (173) (174) |
4.2.3.
SO
X
emissions to air
BAT 50.
In order to prevent or reduce SO
X
emissions to air from the combustion of iron and steel process gases, BAT is to use a combination of the techniques given below.
Technique |
Description |
Applicability |
|||||||||||||||
a. |
Process gas management system and auxiliary fuel choice |
See description in Section 8.2. To the extent allowed by the iron- and steel-works, maximise the use of:
Use of a limited amount of fuels with a higher sulphur content |
Generally applicable within the constraints associated with the availability of different types of fuel |
||||||||||||||
b. |
Coke oven gas pretreatment at the iron- and steel-works |
Use of one of the following techniques:
|
Only applicable to coke oven gas combustion plants |
Type of combustion plant |
O2 reference level (%) |
BAT-AELs for SO2 (mg/Nm3) |
|
Yearly average (175) |
Daily average or average over the sampling period (176) |
||
New or existing boiler |
3 |
25 –150 |
50 –200 (177) |
New or existing CCGT |
15 |
10 –45 |
20 –70 |
4.2.4.
Dust emissions to air
BAT 51.
In order to reduce dust emissions to air from the combustion of iron and steel process gases, BAT is to use one or a combination of the techniques given below.
Technique |
Description |
Applicability |
|
a. |
Fuel choice/management |
Use of a combination of process gases and auxiliary fuels with a low averaged dust or ash content |
Generally applicable within the constraints associated with the availability of different types of fuel |
b. |
Blast furnace gas pretreatment at the iron- and steel-works |
Use of one or a combination of dry dedusting devices (e.g. deflectors, dust catchers, cyclones, electrostatic precipitators) and/or subsequent dust abatement (venturi scrubbers, hurdle-type scrubbers, annular gap scrubbers, wet electrostatic precipitators, disintegrators) |
Only applicable if blast furnace gas is combusted |
c. |
Basic oxygen furnace gas pretreatment at the iron- and steel-works |
Use of dry (e.g. ESP or bag filter) or wet (e.g. wet ESP or scrubber) dedusting. Further descriptions are given in the Iron and Steel BREF |
Only applicable if basic oxygen furnace gas is combusted |
d. |
Electrostatic precipitator (ESP) |
See descriptions in Section 8.5 |
Only applicable to combustion plants combusting a significant proportion of auxiliary fuels with a high ash content |
e. |
Bag filter |
Type of combustion plant |
BAT-AELs for dust (mg/Nm3) |
|
Yearly average (178) |
Daily average or average over the sampling period (179) |
|
New or existing boiler |
2 –7 |
2 –10 |
New or existing CCGT |
2 –5 |
2 –5 |
4.3.
BAT conclusions for the combustion of gaseous and/or liquid fuels on offshore platforms
BAT 52.
In order to improve the general environmental performance of the combustion of gaseous and/or liquid fuels on offshore platforms, BAT is to use one or a combination of the techniques given below.
Techniques |
Description |
Applicability |
|
a. |
Process optimisation |
Optimise the process in order to minimise the mechanical power requirements |
Generally applicable |
b. |
Control pressure losses |
Optimise and maintain inlet and exhaust systems in a way that keeps the pressure losses as low as possible |
|
c. |
Load control |
Operate multiple generator or compressor sets at load points which minimise emissions |
|
d. |
Minimise the ‘spinning reserve’ |
When running with spinning reserve for operational reliability reasons, the number of additional turbines is minimised, except in exceptional circumstances |
|
e. |
Fuel choice |
Provide a fuel gas supply from a point in the topside oil and gas process which offers a minimum range of fuel gas combustion parameters, e.g. calorific value, and minimum concentrations of sulphurous compounds to minimise SO2 formation. For liquid distillate fuels, preference is given to low-sulphur fuels |
|
f. |
Injection timing |
Optimise injection timing in engines |
|
g. |
Heat recovery |
Utilisation of gas turbine/engine exhaust heat for platform heating purposes |
Generally applicable to new combustion plants. In existing combustion plants, the applicability may be restricted by the level of heat demand and the combustion plant layout (space) |
h. |
Power integration of multiple gas fields/oilfields |
Use of a central power source to supply a number of participating platforms located at different gas fields/oilfields |
The applicability may be limited depending on the location of the different gas fields/oilfields and on the organisation of the different participating platforms, including alignment of time schedules regarding planning, start-up and cessation of production |
BAT 53.
In order to prevent or reduce NO
X
emissions to air from the combustion of gaseous and/or liquid fuels on offshore platforms, BAT is to use one or a combination of the techniques given below.
Technique |
Description |
Applicability |
|
a. |
Advanced control system |
See descriptions in Section 8.3 |
The applicability to old combustion plants may be constrained by the need to retrofit the combustion system and/or control command system |
b. |
Dry low-NOX burners (DLN) |
Applicable to new gas turbines (standard equipment) within the constraints associated with fuel quality variations. The applicability may be limited for existing gas turbines by: availability of a retrofit package (for low-load operation), complexity of the platform organisation and space availability |
|
c. |
Lean-burn concept |
Only applicable to new gas-fired engines |
|
d. |
Low-NOX burners (LNB) |
Only applicable to boilers |
BAT 54.
In order to prevent or reduce CO emissions to air from the combustion of gaseous and/or liquid fuels in gas turbines on offshore platforms, BAT is to use one or a combination of the techniques given below.
Technique |
Description |
Applicability |
|
a. |
Combustion optimisation |
See descriptions in Section 8.3 |
Generally applicable |
b. |
Oxidation catalysts |
Not applicable to combustion plants operated < 500 h/yr. Retrofitting existing combustion plants may be constrained by the availability of sufficient space and by weight restrictions |
Type of combustion plant |
BAT-AELs (mg/Nm3) (180) |
Average over the sampling period |
|
New gas turbine combusting gaseous fuels(181) |
15 –50 (182) |
Existing gas turbine combusting gaseous fuels(181) |
< 50 –350 (183) |
5. BAT CONCLUSIONS FOR MULTI-FUEL-FIRED PLANTS
5.1.
BAT conclusions for the combustion of process fuels from the chemical industry
5.1.1.
General environmental performance
BAT 55.
In order to improve the general environmental performance of the combustion of process fuels from the chemical industry in boilers, BAT is to use an appropriate combination of the techniques given in BAT 6 and below.
Technique |
Description |
Applicability |
|
a. |
Pretreatment of process fuel from the chemical industry |
Perform fuel pretreatment on and/or off the site of the combustion plant to improve the environmental performance of fuel combustion |
Applicable within the constraints associated with process fuel characteristics and space availability |
5.1.2.
Energy efficiency
Type of combustion unit |
BAT-AEELs (184) (185) |
|||
Net electrical efficiency (%) |
Net total fuel utilisation (%) (186) (187) |
|||
New unit |
Existing unit |
New unit |
Existing unit |
|
Boiler using liquid process fuels from the chemical industry, including when mixed with HFO, gas oil and/or other liquid fuels |
> 36,4 |
35,6 –37,4 |
80 –96 |
80 –96 |
Boiler using gaseous process fuels from the chemical industry, including when mixed with natural gas and/or other gaseous fuels |
39 –42,5 |
38 –40 |
78 –95 |
78 –95 |
5.1.3.
NO
X
and CO emissions to air
BAT 56.
In order to prevent or reduce NO
X
emissions to air while limiting CO emissions to air from the combustion of process fuels from the chemical industry, BAT is to use one or a combination of the techniques given below.
Technique |
Description |
Applicability |
|
a. |
Low-NOX burners (LNB) |
See descriptions in Section 8.3 |
Generally applicable |
b. |
Air staging |
||
c. |
Fuel staging |
See description in Section 8.3. Applying fuel staging when using liquid fuel mixtures may require a specific burner design |
|
d. |
Flue-gas recirculation |
See descriptions in Section 8.3 |
Generally applicable to new combustion plants. Applicable to existing combustion plants within the constraints associated with chemical installation safety |
e. |
Water/steam addition |
The applicability may be limited due to water availability |
|
f. |
Fuel choice |
Applicable within the constraints associated with the availability of different types of fuel and/or an alternative use of the process fuel |
|
g. |
Advanced control system |
The applicability to old combustion plants may be constrained by the need to retrofit the combustion system and/or control command system |
|
h. |
Selective non-catalytic reduction (SNCR) |
Applicable to existing combustion plants within the constraints associated with chemical installation safety. Not applicable to combustion plants operated < 500 h/yr. The applicability may be limited in the case of combustion plants operated between 500 h/yr and 1 500 h/yr with frequent fuel changes and frequent load variations |
|
i. |
Selective catalytic reduction (SCR) |
Applicable to existing combustion plants within the constraints associated with duct configuration, space availability and chemical installation safety. Not applicable to combustion plants operated < 500 h/yr. There may be technical and economic restrictions for retrofitting existing combustion plants operated between 500 h/yr and 1 500 h/yr. Not generally applicable to combustion plants of < 100 MWth |
Fuel phase used in the combustion plant |
BAT-AELs (mg/Nm3) |
|||
Yearly average |
Daily average or average over the sampling period |
|||
New plant |
Existing plant (188) |
New plant |
Existing plant (189) |
|
Mixture of gases and liquids |
30 –85 |
80 –290 (190) |
50 –110 |
100 –330 (190) |
Gases only |
20 –80 |
70 –100 (191) |
30 –100 |
85 –110 (192) |
5.1.4.
SO
X
, HCl and HF emissions to air
BAT 57.
In order to reduce SO
X
, HCl and HF emissions to air from the combustion of process fuels from the chemical industry in boilers, BAT is to use one or a combination of the techniques given below.
Technique |
Description |
Applicability |
|
a. |
Fuel choice |
See descriptions in Section 8.4 |
Applicable within the constraints associated with the availability of different types of fuel and/or an alternative use of the process fuel |
b. |
Boiler sorbent injection (in-furnace or in-bed) |
Applicable to existing combustion plants within the constraints associated with duct configuration, space availability and chemical installation safety. Wet FGD and seawater FGD are not applicable to combustion plants operated < 500 h/yr. There may be technical and economic restrictions for applying wet FGD or seawater FGD to combustion plants of < 300 MWth, and for retrofitting combustion plants operated between 500 h/yr and 1 500 h/yr with wet FGD or seawater FGD |
|
c. |
Duct sorbent injection (DSI) |
||
d. |
Spray dry absorber (SDA) |
||
e. |
Wet scrubbing |
See description in Section 8.4. Wet scrubbing is used to remove HCl and HF when no wet FGD is used to reduce SOX emissions |
|
f. |
Wet flue-gas desulphurisation (wet FGD) |
See descriptions in Section 8.4 |
|
g. |
Seawater FGD |
Type of combustion plant |
BAT-AELs (mg/Nm3) |
|
Yearly average (193) |
Daily average or average over the sampling period (194) |
|
New and existing boilers |
10 –110 |
90 –200 |
Combustion plant total rated thermal input (MWth) |
BAT-AELs (mg/Nm3) |
|||
HCl |
HF |
|||
Average of samples obtained during one year |
||||
New plant |
Existing plant (195) |
New plant |
Existing plant (195) |
|
< 100 |
1 –7 |
2 –15 (196) |
< 1 –3 |
< 1 –6 (197) |
≥ 100 |
1 –5 |
1 –9 (196) |
< 1 –2 |
< 1 –3 (197) |
5.1.5.
Dust and particulate-bound metal emissions to air
BAT 58.
In order to reduce emissions to air of dust, particulate-bound metals, and trace species from the combustion of process fuels from the chemical industry in boilers, BAT is to use one or a combination of the techniques given below.
Technique |
Description |
Applicability |
|
a. |
Electrostatic precipitator (ESP) |
See descriptions in Section 8.5 |
Generally applicable |
b. |
Bag filter |
||
c. |
Fuel choice |
See description in Section 8.5. Use of a combination of process fuels from the chemical industry and auxiliary fuels with a low averaged dust or ash content |
Applicable within the constraints associated with the availability of different types of fuel and/or an alternative use of the process fuel |
d. |
Dry or semi-dry FGD system |
See descriptions in Section 8.5. The technique is mainly used for SOX, HCl and/or HF control |
See applicability in BAT 57 |
e. |
Wet flue-gas desulphurisation (wet FGD) |
Combustion plant total rated thermal input (MWth) |
BAT-AELs for dust (mg/Nm3) |
|||
Yearly average |
Daily average or average over the sampling period |
|||
New plant |
Existing plant (198) |
New plant |
Existing plant (199) |
|
< 300 |
2 –5 |
2 –15 |
2 –10 |
2 –22 (200) |
≥ 300 |
2 –5 |
2 –10 (201) |
2 –10 |
2 –11 (200) |
5.1.6.
Emissions of volatile organic compounds and polychlorinated dibenzo-dioxins and -furans to air
BAT 59.
In order to reduce emissions to air of volatile organic compounds and polychlorinated dibenzo-dioxins and -furans from the combustion of process fuels from the chemical industry in boilers, BAT is to use one or a combination of the techniques given in BAT 6 and below.
Technique |
Description |
Applicability |
|
a. |
Activated carbon injection |
See description in Section 8.5 |
Only applicable to combustion plants using fuels derived from chemical processes involving chlorinated substances. For the applicability of SCR and rapid quenching see BAT 56 and BAT 57 |
b. |
Rapid quenching using wet scrubbing/flue-gas condenser |
See description of wet scrubbing/flue-gas condenser in Section 8.4 |
|
c. |
Selective catalytic reduction (SCR) |
See description in Section 8.3. The SCR system is adapted and larger than an SCR system only used for NOX reduction |
Pollutant |
Unit |
BAT-AELs |
Average over the sampling period |
||
PCDD/F(202) |
ng I-TEQ/Nm3 |
< 0,012 –0,036 |
TVOC |
mg/Nm3 |
0,6 –12 |
6. BAT CONCLUSIONS FOR THE CO-INCINERATION OF WASTE
6.1.1.
General environmental performance
BAT 60.
In order to improve the general environmental performance of the co-incineration of waste in combustion plants, to ensure stable combustion conditions, and to reduce emissions to air, BAT is to use technique BAT 60 (a) below and a combination of the techniques given in BAT 6 and/or the other techniques below.
Technique |
Description |
Applicability |
|
a. |
Waste pre-acceptance and acceptance |
Implement a procedure for receiving any waste at the combustion plant according to the corresponding BAT from the Waste Treatment BREF. Acceptance criteria are set for critical parameters such as heating value, and the content of water, ash, chlorine and fluorine, sulphur, nitrogen, PCB, metals (volatile (e.g. Hg, Tl, Pb, Co, Se) and non-volatile (e.g. V, Cu, Cd, Cr, Ni)), phosphorus and alkali (when using animal by-products). Apply quality assurance systems for each waste load to guarantee the characteristics of the wastes co-incinerated and to control the values of defined critical parameters (e.g. EN 15358 for non-hazardous solid recovered fuel) |
Generally applicable |
b. |
Waste selection/limitation |
Careful selection of waste type and mass flow, together with limiting the percentage of the most polluted waste that can be co-incinerated. Limit the proportion of ash, sulphur, fluorine, mercury and/or chlorine in the waste entering the combustion plant. Limitation of the amount of waste to be co-incinerated |
Applicable within the constraints associated with the waste management policy of the Member State |
c. |
Waste mixing with the main fuel |
Effective mixing of waste and the main fuel, as a heterogeneous or poorly mixed fuel stream or an uneven distribution may influence the ignition and combustion in the boiler and should be prevented |
Mixing is only possible when the grinding behaviour of the main fuel and waste is similar or when the amount of waste is very small compared to the main fuel |
d. |
Waste drying |
Pre-drying of the waste before introducing it into the combustion chamber, with a view to maintaining the high performance of the boiler |
The applicability may be limited by insufficient recoverable heat from the process, by the required combustion conditions, or by the waste moisture content |
e. |
Waste pretreatment |
See techniques described in the Waste Treatment and Waste Incineration BREFs, including milling, pyrolysis and gasification |
See applicability in the Waste Treatment BREF and in the Waste incineration BREF |
BAT 61.
In order to prevent increased emissions from the co-incineration of waste in combustion plants, BAT is to take appropriate measures to ensure that the emissions of polluting substances in the part of the flue-gases resulting from waste co-incineration are not higher than those resulting from the application of BAT conclusions for the incineration of waste.
BAT 62.
In order to minimise the impact on residues recycling of the co-incineration of waste in combustion plants, BAT is to maintain a good quality of gypsum, ashes and slags as well as other residues, in line with the requirements set for their recycling when the plant is not co-incinerating waste, by using one or a combination of the techniques given in BAT 60 and/or by restricting the co-incineration to waste fractions with pollutant concentrations similar to those in other combusted fuels.
6.1.2.
Energy efficiency
BAT 63.
In order to increase the energy efficiency of the co-incineration of waste, BAT is to use an appropriate combination of the techniques given in BAT 12 and BAT 19, depending on the main fuel type used and on the plant configuration.
6.1.3.
NO
X
and CO emissions to air
BAT 64.
In order to prevent or reduce NO
X
emissions to air while limiting CO and N
2
O emissions from the co-incineration of waste with coal and/or lignite, BAT is to use one or a combination of the techniques given in BAT 20.
BAT 65.
In order to prevent or reduce NO
X
emissions to air while limiting CO and N
2
O emissions from the co-incineration of waste with biomass and/or peat, BAT is to use one or a combination of the techniques given in BAT 24.
6.1.4.
SO
X
, HCl and HF emissions to air
BAT 66.
In order to prevent or reduce SO
X
, HCl and HF emissions to air from the co-incineration of waste with coal and/or lignite, BAT is to use one or a combination of the techniques given in BAT 21.
BAT 67.
In order to prevent or reduce SO
X
, HCl and HF emissions to air from the co-incineration of waste with biomass and/or peat, BAT is to use one or a combination of the techniques given in BAT 25.
6.1.5.
Dust and particulate-bound metal emissions to air
BAT 68.
In order to reduce dust and particulate-bound metal emissions to air from the co-incineration of waste with coal and/or lignite, BAT is to use one or a combination of the techniques given in BAT 22.
Combustion plant total rated thermal input (MWth) |
BAT-AELs |
Averaging period |
|
Sb+As+Pb+Cr+Co+Cu+Mn+Ni+V (mg/Nm3 |
Cd+Tl (μg/Nm3 |
||
< 300 |
0,005 –0,5 |
5 –12 |
Average over the sampling period |
≥ 300 |
0,005 –0,2 |
5 –6 |
Average of samples obtained during one year |
BAT 69.
In order to reduce dust and particulate-bound metal emissions to air from the co-incineration of waste with biomass and/or peat, BAT is to use one or a combination of the techniques given in BAT 26.
BAT-AELs (average of samples obtained during one year) |
|
Sb+As+Pb+Cr+Co+Cu+Mn+Ni+V (mg/Nm3 |
Cd+Tl (μg/Nm3 |
0,075 –0,3 |
< 5 |
6.1.6.
Mercury emissions to air
BAT 70.
In order to reduce mercury emissions to air from the co-incineration of waste with biomass, peat, coal and/or lignite, BAT is to use one or a combination of the techniques given in BAT 23 and BAT 27.
6.1.7.
Emissions of volatile organic compounds and polychlorinated dibenzo-dioxins and -furans to air
BAT 71.
In order to reduce emissions of volatile organic compounds and polychlorinated dibenzo-dioxins and -furans to air from the co-incineration of waste with biomass, peat, coal and/or lignite, BAT is to use a combination of the techniques given in BAT 6, BAT 26 and below.
Technique |
Description |
Applicability |
|
a. |
Activated carbon injection |
See description in Section 8.5. This process is based on the adsorption of pollutant molecules by the activated carbon |
Generally applicable |
b. |
Rapid quenching using wet scrubbing/flue-gas condenser |
See description of wet scrubbing/flue-gas condenser in Section 8.4 |
|
c. |
Selective catalytic reduction (SCR) |
See description in Section 8.3. The SCR system is adapted and larger than an SCR system only used for NOX reduction |
See applicability in BAT 20 and in BAT 24 |
Type of combustion plant |
BAT-AELs |
||
PCDD/F (ng I-TEQ/Nm3) |
TVOC (mg/Nm3) |
||
Average over the sampling period |
Yearly average |
Daily average |
|
Biomass-, peat-, coal- and/or lignite-fired combustion plant |
< 0,01 –0,03 |
< 0,1 –5 |
0,5 –10 |
7. BAT CONCLUSIONS FOR GASIFICATION
7.1.1.
Energy efficiency
BAT 72.
In order to increase the energy efficiency of IGCC and gasification units, BAT is to use one or a combination of the techniques given in BAT 12 and below.
Technique |
Description |
Applicability |
|||||
a. |
Heat recovery from the gasification process |
As the syngas needs to be cooled down to be cleaned further, energy can be recovered for producing additional steam to be added to the steam turbine cycle, enabling additional electrical power to be produced |
Only applicable to IGCC units and to gasification units directly associated to boilers with syngas pretreatment that requires cooling down of the syngas |
||||
b. |
Integration of gasification and combustion processes |
The unit can be designed with full integration of the air supply unit (ASU) and the gas turbine, with all the air fed to the ASU being supplied (extracted) from the gas turbine compressor |
The applicability is limited to IGCC units by the flexibility needs of the integrated plant to quickly provide the grid with electricity when renewable power plants are not available |
||||
c. |
Dry feedstock feeding system |
Use of a dry system for feeding the fuel to the gasifier, in order to improve the energy efficiency of the gasification process |
Only applicable to new units |
||||
d. |
High-temperature and -pressure gasification |
Use of gasification technique with high-temperature and -pressure operating parameters, in order to maximise the efficiency of energy conversion |
Only applicable to new units |
||||
e. |
Design improvements |
Design improvements, such as:
|
Generally applicable to IGCC units |
Type of combustion unit configuration |
BAT-AEELs |
||
Net electrical efficiency (%) of an IGCC unit |
Net total fuel utilisation (%) of a new or existing gasification unit |
||
New unit |
Existing unit |
||
Gasification unit directly associated to a boiler without prior syngas treatment |
No BAT-AEEL |
> 98 |
|
Gasification unit directly associated to a boiler with prior syngas treatment |
No BAT-AEEL |
> 91 |
|
IGCC unit |
No BAT-AEEL |
34 –46 |
> 91 |
7.1.2.
NO
X
and CO emissions to air
BAT 73.
In order to prevent and/or reduce NO
X
emissions to air while limiting CO emissions to air from IGCC plants, BAT is to use one or a combination of the techniques given below.
Technique |
Description |
Applicability |
|
a. |
Combustion optimisation |
See description in Section 8.3 |
Generally applicable |
b. |
Water/steam addition |
See description in Section 8.3. Some intermediate-pressure steam from the steam turbine is reused for this purpose |
Only applicable to the gas turbine part of the IGCC plant. The applicability may be limited due to water availability |
c. |
Dry low-NOX burners (DLN) |
See description in Section 8.3 |
Only applicable to the gas turbine part of the IGCC plant. Generally applicable to new IGCC plants. Applicable on a case-by-case basis for existing IGCC plants, depending on the availability of a retrofit package. Not applicable for syngas with a hydrogen content of > 15 % |
d. |
Syngas dilution with waste nitrogen from the air supply unit (ASU) |
The ASU separates the oxygen from the nitrogen in the air, in order to supply high-quality oxygen to the gasifier. The waste nitrogen from the ASU is reused to reduce the combustion temperature in the gas turbine, by being premixed with the syngas before combustion |
Only applicable when an ASU is used for the gasification process |
e. |
Selective catalytic reduction (SCR) |
See description in Section 8.3 |
Not applicable to IGCC plants operated < 500 h/yr. Retrofitting existing IGCC plants may be constrained by the availability of sufficient space. There may be technical and economic restrictions for retrofitting existing IGCC plants operated between 500 h/yr and 1 500 h/yr |
IGCC plant total rated thermal input (MWth) |
BAT-AELs (mg/Nm3) |
|||
Yearly average |
Daily average or average over the sampling period |
|||
New plant |
Existing plant |
New plant |
Existing plant |
|
≥ 100 |
10 –25 |
12 –45 |
1 –35 |
1 –60 |
7.1.3.
SO
X
emissions to air
BAT 74.
In order to reduce SO
X
emissions to air from IGCC plants, BAT is to use the technique given below.
Technique |
Description |
Applicability |
|
a. |
Acid gas removal |
Sulphur compounds from the feedstock of a gasification process are removed from the syngas via acid gas removal, e.g. including a COS (and HCN) hydrolysis reactor and the absorption of H2S using a solvent such as methyl diethanolamine. Sulphur is then recovered as either liquid or solid elemental sulphur (e.g. through a Claus unit), or as sulphuric acid, depending on market demands |
The applicability may be limited in the case of biomass IGCC plants due to the very low sulphur content in biomass |
7.1.4.
Dust, particulate-bound metal, ammonia and halogen emissions to air
BAT 75.
In order to prevent or reduce dust, particulate-bound metal, ammonia and halogen emissions to air from IGCC plants, BAT is to use one or a combination of the techniques given below.
Technique |
Description |
Applicability |
|
a. |
Syngas filtration |
Dedusting using fly ash cyclones, bag filters, ESPs and/or candle filters to remove fly ash and unconverted carbon. Bag filters and ESPs are used in the case of syngas temperatures up to 400 °C |
Generally applicable |
b. |
Syngas tars and ashes recirculation to the gasifier |
Tars and ashes with a high carbon content generated in the raw syngas are separated in cyclones and recirculated to the gasifier, in the case of a low syngas temperature at the gasifier outlet (< 1 100 °C) |
|
c. |
Syngas washing |
Syngas passes through a water scrubber, downstream of other dedusting technique(s), where chlorides, ammonia, particles and halides are separated |
IGCC plant total rated thermal input (MWth) |
BAT-AELs |
||
Sb+As+Pb+Cr+Co+Cu+Mn+Ni+V (mg/Nm3) (Average over the sampling period) |
Hg (μg/Nm3) (Average over the sampling period) |
Dust (mg/Nm3) (yearly average) |
|
≥ 100 |
< 0,025 |
< 1 |
< 2,5 |
8. DESCRIPTION OF TECHNIQUES
8.1.
General techniques
Technique |
Description |
Advanced control system |
The use of a computer-based automatic system to control the combustion efficiency and support the prevention and/or reduction of emissions. This also includes the use of high-performance monitoring. |
Combustion optimisation |
Measures taken to maximise the efficiency of energy conversion, e.g. in the furnace/boiler, while minimising emissions (in particular of CO). This is achieved by a combination of techniques including good design of the combustion equipment, optimisation of the temperature (e.g. efficient mixing of the fuel and combustion air) and residence time in the combustion zone, and use of an advanced control system. |
8.2.
Techniques to increase energy efficiency
Technique |
Description |
Advanced control system |
See Section 8.1 |
CHP readiness |
The measures taken to allow the later export of a useful quantity of heat to an off-site heat load in a way that will achieve at least a 10 % reduction in primary energy usage compared to the separate generation of the heat and power produced. This includes identifying and retaining access to specific points in the steam system from which steam can be extracted, as well as making sufficient space available to allow the later fitting of items such as pipework, heat exchangers, extra water demineralisation capacity, standby boiler plant and back-pressure turbines. Balance of Plant (BoP) systems and control/instrumentation systems are suitable for upgrade. Later connection of back-pressure turbine(s) is also possible. |
Combined cycle |
Combination of two or more thermodynamic cycles, e.g. a Brayton cycle (gas turbine/combustion engine) with a Rankine cycle (steam turbine/boiler), to convert heat loss from the flue-gas of the first cycle to useful energy by subsequent cycle(s). |
Combustion optimisation |
See Section 8.1 |
Flue-gas condenser |
A heat exchanger where water is preheated by the flue-gas before it is heated in the steam condenser. The vapour content in the flue-gas thus condenses as it is cooled by the heating water. The flue-gas condenser is used both to increase the energy efficiency of the combustion unit and to remove pollutants such as dust, SOX, HCl, and HF from the flue-gas. |
Process gas management system |
A system that enables the iron and steel process gases that can be used as fuels (e.g. blast furnace, coke oven, basic oxygen furnace gases) to be directed to the combustion plants, depending on the availability of these fuels and on the type of combustion plants in an integrated steelworks. |
Supercritical steam conditions |
The use of a steam circuit, including steam reheating systems, in which steam can reach pressures above 220,6 bar and temperatures of > 540 °C. |
Ultra-supercritical steam conditions |
The use of a steam circuit, including reheat systems, in which steam can reach pressures above 250–300 bar and temperatures above 580–600 °C. |
Wet stack |
The design of the stack in order to enable water vapour condensation from the saturated flue-gas and thus to avoid using a flue-gas reheater after the wet FGD. |
8.3.
Techniques to reduce emissions of NO
X
and/or CO to air
Technique |
Description |
Advanced control system |
See Section 8.1 |
Air staging |
The creation of several combustion zones in the combustion chamber with different oxygen contents for reducing NOX emissions and ensuring optimised combustion. The technique involves a primary combustion zone with substoichiometric firing (i.e. with deficiency of air) and a second reburn combustion zone (running with excess air) to improve combustion. Some old, small boilers may require a capacity reduction to allow the space for air staging. |
Combined techniques for NOX and SOX reduction |
The use of complex and integrated abatement techniques for combined reduction of NOX, SOX and, often, other pollutants from the flue-gas, e.g. activated carbon and DeSONOX processes. They can be applied either alone or in combination with other primary techniques in coal-fired PC boilers. |
Combustion optimisation |
See Section 8.1 |
Dry low-NOX burners (DLN) |
Gas turbine burners that include the premixing of the air and fuel before entering the combustion zone. By mixing air and fuel before combustion, a homogeneous temperature distribution and a lower flame temperature are achieved, resulting in lower NOX emissions. |
Flue-gas or exhaust-gas recirculation (FGR/EGR) |
Recirculation of part of the flue-gas to the combustion chamber to replace part of the fresh combustion air, with the dual effect of cooling the temperature and limiting the O2 content for nitrogen oxidation, thus limiting the NOX generation. It implies the supply of flue-gas from the furnace into the flame to reduce the oxygen content and therefore the temperature of the flame. The use of special burners or other provisions is based on the internal recirculation of combustion gases which cool the root of the flames and reduce the oxygen content in the hottest part of the flames. |
Fuel choice |
The use of fuel with a low nitrogen content. |
Fuel staging |
The technique is based on the reduction of the flame temperature or localised hot spots by the creation of several combustion zones in the combustion chamber with different injection levels of fuel and air. The retrofit may be less efficient in smaller plants than in larger plants. |
Lean-burn concept and advanced lean-burn concept |
The control of the peak flame temperature through lean-burn conditions is the primary combustion approach to limiting NOX formation in gas engines. Lean combustion decreases the fuel to air ratio in the zones where NOX is generated so that the peak flame temperature is less than the stoichiometric adiabatic flame temperature, therefore reducing thermal NOX formation. The optimisation of this concept is called the ‘advanced lean-burn concept’. |
Low-NOX burners (LNB) |
The technique (including ultra- or advanced low-NOX burners) is based on the principles of reducing peak flame temperatures; boiler burners are designed to delay but improve the combustion and increase the heat transfer (increased emissivity of the flame). The air/fuel mixing reduces the availability of oxygen and reduces the peak flame temperature, thus retarding the conversion of fuel-bound nitrogen to NOX and the formation of thermal NOX, while maintaining high combustion efficiency. It may be associated with a modified design of the furnace combustion chamber. The design of ultra-low-NOX burners (ULNBs) includes combustion staging (air/fuel) and firebox gases’ recirculation (internal flue-gas recirculation). The performance of the technique may be influenced by the boiler design when retrofitting old plants. |
Low-NOX combustion concept in diesel engines |
The technique consists of a combination of internal engine modifications, e.g. combustion and fuel injection optimisation (the very late fuel injection timing in combination with early inlet air valve closing), turbocharging or Miller cycle. |
Oxidation catalysts |
The use of catalysts (that usually contain precious metals such as palladium or platinum) to oxidise carbon monoxide and unburnt hydrocarbons with oxygen to form CO2 and water vapour. |
Reduction of the combustion air temperature |
The use of combustion air at ambient temperature. The combustion air is not preheated in a regenerative air preheater. |
Selective catalytic reduction (SCR) |
Selective reduction of nitrogen oxides with ammonia or urea in the presence of a catalyst. The technique is based on the reduction of NOX to nitrogen in a catalytic bed by reaction with ammonia (in general aqueous solution) at an optimum operating temperature of around 300–450 °C. Several layers of catalyst may be applied. A higher NOX reduction is achieved with the use of several catalyst layers. The technique design can be modular, and special catalysts and/or preheating can be used to cope with low loads or with a wide flue-gas temperature window. ‘In-duct’ or ‘slip’ SCR is a technique that combines SNCR with downstream SCR which reduces the ammonia slip from the SNCR unit. |
Selective non-catalytic reduction (SNCR) |
Selective reduction of nitrogen oxides with ammonia or urea without a catalyst. The technique is based on the reduction of NOX to nitrogen by reaction with ammonia or urea at a high temperature. The operating temperature window is maintained between 800 °C and 1 000 °C for optimal reaction. |
Water/steam addition |
Water or steam is used as a diluent for reducing the combustion temperature in gas turbines, engines or boilers and thus the thermal NOX formation. It is either premixed with the fuel prior to its combustion (fuel emulsion, humidification or saturation) or directly injected in the combustion chamber (water/steam injection). |
8.4.
Techniques to reduce emissions of SO
X
, HCl and/or HF to air
Technique |
Description |
Boiler sorbent injection (in-furnace or in-bed) |
The direct injection of a dry sorbent into the combustion chamber, or the addition of magnesium- or calcium-based adsorbents to the bed of a fluidised bed boiler. The surface of the sorbent particles reacts with the SO2 in the flue-gas or in the fluidised bed boiler. It is mostly used in combination with a dust abatement technique. |
Circulating fluidised bed (CFB) dry scrubber |
Flue-gas from the boiler air preheater enters the CFB absorber at the bottom and flows vertically upwards through a Venturi section where a solid sorbent and water are injected separately into the flue-gas stream. It is mostly used in combination with a dust abatement technique. |
Combined techniques for NOX and SOX reduction |
See Section 8.3 |
Duct sorbent injection (DSI) |
The injection and dispersion of a dry powder sorbent in the flue-gas stream. The sorbent (e.g. sodium carbonate, sodium bicarbonate, hydrated lime) reacts with acid gases (e.g. the gaseous sulphur species and HCl) to form a solid which is removed with dust abatement techniques (bag filter or electrostatic precipitator). DSI is mostly used in combination with a bag filter. |
Flue-gas condenser |
See Section 8.2 |
Fuel choice |
The use of a fuel with a low sulphur, chlorine and/or fluorine content |
Process gas management system |
See Section 8.2 |
Seawater FGD |
A specific non-regenerative type of wet scrubbing using the natural alkalinity of theseawater to absorb the acidic compounds in the flue-gas. Generally requires an upstream abatement of dust. |
Spray dry absorber (SDA) |
A suspension/solution of an alkaline reagent is introduced and dispersed in the flue-gas stream. The material reacts with the gaseous sulphur species to form a solid which is removed with dust abatement techniques (bag filter or electrostatic precipitator). SDA is mostly used in combination with a bag filter. |
Wet flue-gas desulphurisation (wet FGD) |
Technique or combination of scrubbing techniques by which sulphur oxides are removed from flue-gases through various processes generally involving an alkaline sorbent for capturing gaseous SO2 and transforming it into solids. In the wet scrubbing process, gaseous compounds are dissolved in a suitable liquid (water or alkaline solution). Simultaneous removal of solid and gaseous compounds may be achieved. Downstream of the wet scrubber, the flue-gases are saturated with water and separation of the droplets is required before discharging the flue-gases. The liquid resulting from the wet scrubbing is sent to a waste water treatment plant and the insoluble matter is collected by sedimentation or filtration. |
Wet scrubbing |
Use of a liquid, typically water or an aqueous solution, to capture the acidic compounds from the flue-gas by absorption. |
8.5.
Techniques to reduce emissions to air of dust, metals including mercury, and/or PCDD/F
Technique |
Description |
Bag filter |
Bag or fabric filters are constructed from porous woven or felted fabric through which gases are passed to remove particles. The use of a bag filter requires the selection of a fabric suitable for the characteristics of the flue-gas and the maximum operating temperature. |
Boiler sorbent injection (in-furnace or in-bed) |
See general description in Section 10.8.4. There are co-benefits in the form of dust and metal emissions reduction. |
Carbon sorbent (e.g. activated carbon or halogenated activated carbon) injection in the flue-gas |
Mercury and/or PCDD/F adsorption by carbon sorbents, such as (halogenated) activated carbon, with or without chemical treatment. The sorbent injection system can be enhanced by the addition of a supplementary bag filter. |
Dry or semi-dry FGD system |
See general description of each technique (i.e. spray dry absorber (SDA), duct sorben injection (DSI), circulating fluidised bed (CFB) dry scrubber) in Section 8.4. There are co-benefits in the form of dust and metal emissions reduction. |
Electrostatic precipitator (ESP) |
Electrostatic precipitators operate such that particles are charged and separated under the influence of an electrical field. Electrostatic precipitators are capable of operating under a wide range of conditions. The abatement efficiency typically depends on the number of fields, the residence time (size), catalyst properties, and upstream particle removal devices. ESPs generally include between two and five fields. The most modern (high-performance) ESPs have up to seven fields. |
Fuel choice |
The use of a fuel with a low ash or metals (e.g. mercury) content. |
Multicyclones |
Set of dust control systems, based on centrifugal force, whereby particles are separated from the carrier gas, assembled in one or several enclosures. |
Use of halogenated additives in the fuel or injected in the furnace |
Addition of halogen compounds (e.g. brominated additives) into the furnace to oxidise elemental mercury into soluble or particulate species, thereby enhancing mercury removal in downstream abatement systems. |
Wet flue-gas desulphurisation (wet FGD) |
See general description in Section 8.4. There are co-benefits in the form of dust and metals emission reduction. |
8.6.
Techniques to reduce emissions to water
Technique |
Description |
Adsorption on activated carbon |
The retention of soluble pollutants on the surface of solid, highly porous particles (the adsorbent). Activated carbon is typically used for the adsorption of organic compounds and mercury. |
Aerobic biological treatment |
The biological oxidation of dissolved organic pollutants with oxygen using the metabolism of microorganisms. In the presence of dissolved oxygen – injected as air or pure oxygen – the organic components are mineralised into carbon dioxide and water or are transformed into other metabolites and biomass. Under certain conditions, aerobic nitrification also takes place whereby microorganisms oxidise ammonium (NH4 +) to the intermediate nitrite (NO2 -), which is then further oxidised to nitrate (NO3 -). |
Anoxic/anaerobic biological treatment |
The biological reduction of pollutants using the metabolism of microorganisms (e.g. nitrate (NO3 -) is reduced to elemental gaseous nitrogen, oxidised species of mercury are reduced to elemental mercury). The anoxic/anaerobic treatment of waste water from the use of wet abatement systems is typically carried out in fixed-film bioreactors using activated carbon as a carrier. The anoxic/anaerobic biological treatment for the removal of mercury is applied in combination with other techniques. |
Coagulation and flocculation |
Coagulation and flocculation are used to separate suspended solids from waste water and are often carried out in successive steps. Coagulation is carried out by adding coagulants with charges opposite to those of the suspended solids. Flocculation is carried out by adding polymers, so that collisions of microfloc particles cause them to bond thereby producing larger flocs. |
Crystallisation |
The removal of ionic pollutants from waste water by crystallising them on a seed material such as sand or minerals, in a fluidised bed process |
Filtration |
The separation of solids from waste water by passing it through a porous medium. It includes different types of techniques, e.g. sand filtration, microfiltration and ultrafiltration. |
Flotation |
The separation of solid or liquid particles from waste water by attaching them to fine gas bubbles, usually air. The buoyant particles accumulate at the water surface and are collected with skimmers. |
Ion exchange |
The retention of ionic pollutants from waste water and their replacement by more acceptable ions using an ion exchange resin. The pollutants are temporarily retained and afterwards released into a regeneration or backwashing liquid. |
Neutralisation |
The adjustment of the pH of the waste water to the neutral pH level (approximately 7) by adding chemicals. Sodium hydroxide (NaOH) or calcium hydroxide (Ca(OH)2) is generally used to increase the pH whereas sulphuric acid (H2SO4), hydrochloric acid (HCl) or carbon dioxide (CO2) is generally used to decrease the pH. The precipitation of some pollutants may occur during neutralisation. |
Oil-water separation |
The removal of free oil from waste water by gravity separation using devices such as the American Petroleum Institute separator, a corrugated plate interceptor, or a parallel plate interceptor. Oil-water separation is normally followed by flotation, supported by coagulation/flocculation. In some cases, emulsion breaking may be needed prior to oil-water separation. |
Oxidation |
The conversion of pollutants by chemical oxidising agents to similar compounds that are less hazardous and/or easier to abate. In the case of waste water from the use of wet abatement systems, air may be used to oxidise sulphite (SO3 2-) to sulphate (SO4 2-). |
Precipitation |
The conversion of dissolved pollutants into insoluble compounds by adding chemical precipitants. The solid precipitates formed are subsequently separated by sedimentation, flotation or filtration. Typical chemicals used for metal precipitation are lime, dolomite, sodium hydroxide, sodium carbonate, sodium sulphide and organosulphides. Calcium salts (other than lime) are used to precipitate sulphate or fluoride. |
Sedimentation |
The separation of suspended solids by gravitational settling. |
Stripping |
The removal of purgeable pollutants (e.g. ammonia) from waste water by contact with a high flow of a gas current in order to transfer them to the gas phase. The pollutants are removed from the stripping gas in a downstream treatment and may potentially be reused. |