Division BAT-associated emission levels

United Kingdom

See Table 15.

Table 15

BAT-associated emission levels for dust and SO₂ emissions from a recovery boiler

Parameter	Average over the sampling periodmg/Nm³ at 5 % O₂
For recovery boilers operated in mills using more than 25 % of hardwood (potassium-rich) in raw materials, higher dust emissions up to 30 mg/Nm³ may occur.
The BAT-AEL for dust does not apply for ammonium-based mills.
Due to process-specific higher emissions, the BAT-AEL for SO₂ does not apply for recovery boilers operated permanently under ‘acidic’ conditions, i.e. using sulphite liquor as wet-scrubber washing media as part of the sulphite recovery process.
For existing multistage venturi scrubbers, higher emissions of SO₂ up to 400 mg/Nm³ as a daily average value and up to 350 mg/Nm³ as a yearly average may occur.
Not applicable during ‘acid operation’, i.e. periods in which preventive flushing and cleaning of incrustation in the scrubbers takes place. During these periods emissions can be up to 300 – 500 mg SO₂/Nm³ (at 5 % O₂) for cleaning of one of the scrubbers and up to 1 200 mg SO₂/Nm³ (half-hourly mean values, at 5 % O₂) when cleaning the final washer.
Dust	5 – 20^f1 ^f2
	Daily average mg/Nm³ at 5 % O₂	Yearly average mg/Nm³ at 5 % O₂
SO₂	100 – 300^f3 ^f4 ^f5	50 – 250

The BAT-associated environmental performance level is a duration of acid operation of around 240 hours per year for the scrubbers, and less than 24 hours per month for the last monosulphite scrubber.

Annotations

Footnotes

f1: For recovery boilers operated in mills using more than 25 % of hardwood (potassium-rich) in raw materials, higher dust emissions up to 30 mg/Nm³ may occur.
f2: The BAT-AEL for dust does not apply for ammonium-based mills.
f3: Due to process-specific higher emissions, the BAT-AEL for SO₂ does not apply for recovery boilers operated permanently under ‘acidic’ conditions, i.e. using sulphite liquor as wet-scrubber washing media as part of the sulphite recovery process.
f4: For existing multistage venturi scrubbers, higher emissions of SO₂ up to 400 mg/Nm³ as a daily average value and up to 350 mg/Nm³ as a yearly average may occur.
f5: Not applicable during ‘acid operation’, i.e. periods in which preventive flushing and cleaning of incrustation in the scrubbers takes place. During these periods emissions can be up to 300 – 500 mg SO₂/Nm³ (at 5 % O₂) for cleaning of one of the scrubbers and up to 1 200 mg SO₂/Nm³ (half-hourly mean values, at 5 % O₂) when cleaning the final washer.