Division BAT 21 In order to prevent or reduce SOX, 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.

United Kingdom

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	See description in Section 8.4
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 MW_th, and for retrofitting existing combustion plants operated between 500 h/yr and 1 500 h/yr
g.	Seawater FGD
h.	Combined techniques for NO_X and SO_X 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

Table 4

BAT-associated emission levels (BAT-AELs) for SO₂ emissions to air from the combustion of coal and/or lignite

Combustion plant total rated thermal input(MW_th)	BAT-AELs (mg/Nm³)
These BAT-AELs do not apply to plants operated < 1 500 h/yr.
For plants operated < 500 h/yr, these levels are indicative.
In the case of plants put into operation no later than 7 January 2014, the upper end of the BAT-AEL range is 250 mg/Nm³.
The lower end of the range can be achieved with the use of low-sulphur fuels in combination with the most advanced wet abatement system designs.
The higher end of the BAT-AEL range is 220 mg/Nm³ in the case of plants put into operation no later than 7 January 2014 and operated < 1 500 h/yr. For other existing plants put into operation no later than 7 January 2014, the higher end of the BAT-AEL range is 205 mg/Nm³.
For circulating fluidised bed boilers, the lower end of the range can be achieved by using high-efficiency wet FGD. The higher end of the range can be achieved by using boiler in-bed sorbent injection.
	Yearly average		Daily average	Daily average or average over the sampling period
	New plant	Existing plant^f1	New plant	Existing plant^f2
< 100	150–200	150–360	170–220	170–400
100–300	80–150	95–200	135–200	135–220^f3
≥ 300, PC boiler	10–75	10–130^f4	25–110	25–165^f5
≥ 300, Fluidised bed boiler^f6	20–75	20–180	25–110	50–220

For a combustion plant with a total rated thermal input of more than 300 MW, which is specifically designed to fire indigenous lignite fuels and which can demonstrate that it cannot achieve the BAT-AELs mentioned in Table 4 for techno-economic reasons, the daily average BAT-AELs set out in Table 4 do not apply, and the upper end of the yearly average BAT-AEL range is as follows:

(i)

for a new FGD system: RCG × 0,01 with a maximum of 200 mg/Nm³;
(ii)

for an existing FGD system: RCG × 0,03 with a maximum of 320 mg/Nm³;

in which RCG represents the 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 SO_X abatement system, expressed at a reference oxygen content of 6 vol- % O₂.
(iii)

If boiler sorbent injection is applied as part of the FGD system, the RCG may be adjusted by taking into account the SO₂ reduction efficiency of this technique (η_BSI), as follows: RCG (adjusted) = RCG (measured)/(1-η_BSI).

Table 5

BAT-associated emission levels (BAT-AELs) for HCl and HF emissions to air from the combustion of coal and/or lignite

Pollutant	Combustion plant total rated thermal input(MW_th)	BAT-AELs (mg/Nm³)
The lower end of these BAT-AEL ranges may be difficult to achieve in the case of plants fitted with wet FGD and a downstream gas-gas heater.
The higher end of the BAT-AEL range is 20 mg/Nm³ in the following cases: plants combusting fuels where the average chlorine content is 1 000 mg/kg (dry) or higher; plants operated < 1 500 h/yr; FBC boilers. For plants operated < 500 h/yr, these levels are indicative.
In the case of plants fitted with wet FGD with a downstream gas-gas heater, the higher end of the BAT-AEL range is 7 mg/Nm³.
The higher end of the BAT-AEL range is 7 mg/Nm³ in the following cases: plants fitted with wet FGD with a downstream gas-gas heater; plants operated < 1 500 h/yr; FBC boilers. For plants operated < 500 h/yr, these levels are indicative.
		Yearly average or average of samples obtained during one year
		New plant	Existing plant^f7
HCl	< 100	1–6	2–10^f8
HCl	≥ 100	1–3	1–5 ^f9
HF	< 100	< 1–3	< 1–6^f10
HF	≥ 100	< 1–2	< 1–3

Annotations

Footnotes

f1: These BAT-AELs do not apply to plants operated < 1 500 h/yr.
f2: For plants operated < 500 h/yr, these levels are indicative.
f3: In the case of plants put into operation no later than 7 January 2014, the upper end of the BAT-AEL range is 250 mg/Nm³.
f4: The lower end of the range can be achieved with the use of low-sulphur fuels in combination with the most advanced wet abatement system designs.
f5: The higher end of the BAT-AEL range is 220 mg/Nm³ in the case of plants put into operation no later than 7 January 2014 and operated < 1 500 h/yr. For other existing plants put into operation no later than 7 January 2014, the higher end of the BAT-AEL range is 205 mg/Nm³.
f6: For circulating fluidised bed boilers, the lower end of the range can be achieved by using high-efficiency wet FGD. The higher end of the range can be achieved by using boiler in-bed sorbent injection.
f7: The lower end of these BAT-AEL ranges may be difficult to achieve in the case of plants fitted with wet FGD and a downstream gas-gas heater.
f8: The higher end of the BAT-AEL range is 20 mg/Nm³ in the following cases: plants combusting fuels where the average chlorine content is 1 000 mg/kg (dry) or higher; plants operated < 1 500 h/yr; FBC boilers. For plants operated < 500 h/yr, these levels are indicative.
f9: In the case of plants fitted with wet FGD with a downstream gas-gas heater, the higher end of the BAT-AEL range is 7 mg/Nm³.
f10: The higher end of the BAT-AEL range is 7 mg/Nm³ in the following cases: plants fitted with wet FGD with a downstream gas-gas heater; plants operated < 1 500 h/yr; FBC boilers. For plants operated < 500 h/yr, these levels are indicative.