Division BAT 24 In order to prevent or reduce NOX emissions to air while limiting CO and N2O 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.

United Kingdom

Technique		Description	Applicability
a.	Combustion optimisation	See descriptions in Section 8.3	Generally applicable
b.	Low-NO_X 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 MW_th. Not generally applicable to existing combustion plants of < 100 MW_th

Table 9

BAT-associated emission levels (BAT-AELs) for NO_X emissions to air from the combustion of solid biomass and/or peat

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 combustion plants operated < 500 h/yr, these levels are indicative.
For plants burning fuels where the average potassium content is 2 000 mg/kg (dry) or higher, and/or the average sodium content is 300 mg/kg or higher, the higher end of the BAT-AEL range is 200 mg/Nm³.
For plants burning fuels where the average potassium content is 2 000 mg/kg (dry) or higher, and/or the average sodium content is 300 mg/kg or higher, the higher end of the BAT-AEL range is 250 mg/Nm³.
For plants burning fuels where the average potassium content is 2 000 mg/kg (dry) or higher, and/or the average sodium content is 300 mg/kg or higher, the higher end of the BAT-AEL range is 260 mg/Nm³.
For plants put into operation no later than 7 January 2014 and burning fuels where the average potassium content is 2 000 mg/kg (dry) or higher, and/or the average sodium content is 300 mg/kg or higher, the higher end of the BAT-AEL range is 310 mg/Nm³.
The higher end of the BAT-AEL range is 160 mg/Nm³ for plants put into operation no later than 7 January 2014.
The higher end of the BAT-AEL range is 200 mg/Nm³ for plants put into operation no later than 7 January 2014.
	Yearly average		Daily average or average over the sampling period
	New plant	Existing plant^f1	New plant	Existing plant^f2
50–100	70–150^f3	70–225^f4	120–200^f5	120–275^f6
100–300	50–140	50–180	100–200	100–220
≥ 300	40–140	40–150^f7	65–150	95–165^f8

As an indication, the yearly average CO emission levels will generally be:

< 30–250 mg/Nm³ for existing combustion plants of 50–100 MW_th operated ≥ 1 500 h/yr, or new combustion plants of 50–100 MW_th,
< 30–160 mg/Nm³ for existing combustion plants of 100–300 MW_th operated ≥ 1 500 h/yr, or new combustion plants of 100–300 MW_th,
< 30–80 mg/Nm³ for existing combustion plants of ≥ 300 MW_th operated ≥ 1 500 h/yr, or new combustion plants of ≥ 300 MW_th.

Annotations

Footnotes

f1: These BAT-AELs do not apply to plants operated < 1 500 h/yr.
f2: For combustion plants operated < 500 h/yr, these levels are indicative.
f3: For plants burning fuels where the average potassium content is 2 000 mg/kg (dry) or higher, and/or the average sodium content is 300 mg/kg or higher, the higher end of the BAT-AEL range is 200 mg/Nm³.
f4: For plants burning fuels where the average potassium content is 2 000 mg/kg (dry) or higher, and/or the average sodium content is 300 mg/kg or higher, the higher end of the BAT-AEL range is 250 mg/Nm³.
f5: For plants burning fuels where the average potassium content is 2 000 mg/kg (dry) or higher, and/or the average sodium content is 300 mg/kg or higher, the higher end of the BAT-AEL range is 260 mg/Nm³.
f6: For plants put into operation no later than 7 January 2014 and burning fuels where the average potassium content is 2 000 mg/kg (dry) or higher, and/or the average sodium content is 300 mg/kg or higher, the higher end of the BAT-AEL range is 310 mg/Nm³.
f7: The higher end of the BAT-AEL range is 160 mg/Nm³ for plants put into operation no later than 7 January 2014.
f8: The higher end of the BAT-AEL range is 200 mg/Nm³ for plants put into operation no later than 7 January 2014.