Division BAT 28 In order to prevent or reduce NOX 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.

United Kingdom

Technique		Description	Applicability
a.	Air staging	See descriptions in Section 8.3	Generally applicable
b.	Fuel staging
c.	Flue-gas recirculation
d.	Low-NO_X 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 MW_th
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

Table 14

BAT-associated emission levels (BAT-AELs) for NO_X emissions to air from the combustion of HFO and/or gas oil in boilers

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.
For industrial boilers and district heating plants put into operation no later than 27 November 2003, which are operated < 1 500 h/yr and for which SCR and/or SNCR is not applicable, the higher end of the BAT-AEL range is 450 mg/Nm³.
The higher end of the BAT-AEL range is 110 mg/Nm³ for plants of 100–300 MW_th and plants of ≥ 300 MW_th that were put into operation no later than 7 January 2014.
The higher end of the BAT-AEL range is 145 mg/Nm³ for plants of 100–300 MW_th and plants of ≥ 300 MW_th that were put into operation no later than 7 January 2014.
For industrial boilers and district heating plants of > 100 MW_th put into operation no later than 27 November 2003, which are operated < 1 500 h/yr and for which SCR and/or SNCR is not applicable, the higher end of the BAT-AEL range is 365 mg/Nm³.
	Yearly average		Daily average or average over the sampling period
	New plant	Existing plant^f1	New plant	Existing plant^f2
< 100	75–200	150–270	100–215	210–330^f3
≥ 100	45–75	45–100^f4	85–100	85–110^f5 ^f6

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

10-30 mg/Nm³ for existing combustion plants of < 100 MW_th operated ≥ 1 500 h/yr, or new combustion plants of <100 MW_th,
10–20mg/Nm³ for existing combustion plants of ≥ 100 MW_th operated ≥ 1 500 h/yr, or new combustion plants of ≥ 100 MW_th.

Annotations

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: For industrial boilers and district heating plants put into operation no later than 27 November 2003, which are operated < 1 500 h/yr and for which SCR and/or SNCR is not applicable, the higher end of the BAT-AEL range is 450 mg/Nm³.
f4: The higher end of the BAT-AEL range is 110 mg/Nm³ for plants of 100–300 MW_th and plants of ≥ 300 MW_th that were put into operation no later than 7 January 2014.
f5: The higher end of the BAT-AEL range is 145 mg/Nm³ for plants of 100–300 MW_th and plants of ≥ 300 MW_th that were put into operation no later than 7 January 2014.
f6: For industrial boilers and district heating plants of > 100 MW_th put into operation no later than 27 November 2003, which are operated < 1 500 h/yr and for which SCR and/or SNCR is not applicable, the higher end of the BAT-AEL range is 365 mg/Nm³.