Division BAT 57 In order to reduce SOX, 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.

United Kingdom

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 MW_th, 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 SO_X emissions
f.	Wet flue-gas desulphurisation (wet FGD)	See descriptions in Section 8.4
g.	Seawater FGD	See descriptions in Section 8.4

Table 35

BAT-associated emission levels (BAT-AELs) for SO₂ emissions to air from the combustion of 100 % process fuels from the chemical industry in boilers

Type of combustion plant	BAT-AELs (mg/Nm³)
For existing plants operated < 1 500 h/yr, these BAT-AELs do not apply.
For existing plants operated < 500 h/yr, these levels are indicative.
Type of combustion plant	Yearly average^f1	Daily average or average over the sampling period^f2
New and existing boilers	10–110	90–200

Table 36

BAT-associated emission levels (BAT-AELs) for HCl and HF emissions to air from the combustion of process fuels from the chemical industry in boilers

Combustion plant total rated thermal input(MW_th)	BAT-AELs (mg/Nm³)
For plants operated < 500 h/yr, these levels are indicative.
In the case of plants operated < 1 500 h/yr, the higher end of the BAT-AEL range is 20 mg/Nm³.
In the case of plants operated < 1 500 h/yr, the higher end of the BAT-AEL range is 7 mg/Nm³.
	HCl		HF
	Average of samples obtained during one year
	New plant	Existing plant^f3	New plant	Existing plant
< 100	1–7	2–15^f4	< 1–3	< 1–6^f5
≥ 100	1–5	1–9	< 1–2	< 1–3

Annotations

Footnotes

f1: For existing plants operated < 1 500 h/yr, these BAT-AELs do not apply.
f2: For existing plants operated < 500 h/yr, these levels are indicative.
f3: For plants operated < 500 h/yr, these levels are indicative.
f4: In the case of plants operated < 1 500 h/yr, the higher end of the BAT-AEL range is 20 mg/Nm³.
f5: In the case of plants operated < 1 500 h/yr, the higher end of the BAT-AEL range is 7 mg/Nm³.