Division BAT 50 In order to prevent or reduce SOX emissions to air from the combustion of iron and steel process gases, BAT is to use a combination of the techniques given below.

United Kingdom

Technique	Description	Applicability
a.	Process gas management system and auxiliary fuel choice	See description in Section 8.2. To the extent allowed by the iron- and steel-works, maximise the use of: a majority of blast furnace gas with a low sulphur content in the fuel diet, a combination of fuels with a low averaged sulphur content, e.g. individual process fuels with a very low S content such as: Blast furnace gas with a sulphur content < 10 mg/Nm³, coke oven gas with a sulphur content < 300 mg/Nm³, and auxiliary fuels such as: natural gas, liquid fuels with a sulphur content of ≤ 0,4 % (in boilers). Use of a limited amount of fuels with a higher sulphur content	Generally applicable within the constraints associated with the availability of different types of fuel
b.	Coke oven gas pretreatment at the iron- and steel-works	Use of one of the following techniques: desulphurisation by absorption systems, wet oxidative desulphurisation	Only applicable to coke oven gas combustion plants

Technique

Description

Applicability

Process gas management system and auxiliary fuel choice

See description in Section 8.2.

To the extent allowed by the iron- and steel-works, maximise the use of:

a majority of blast furnace gas with a low sulphur content in the fuel diet,
a combination of fuels with a low averaged sulphur content, e.g. individual process fuels with a very low S content such as:
- Blast furnace gas with a sulphur content < 10 mg/Nm³,
- coke oven gas with a sulphur content < 300 mg/Nm³,
and auxiliary fuels such as:
- natural gas,
- liquid fuels with a sulphur content of ≤ 0,4 % (in boilers).

Use of a limited amount of fuels with a higher sulphur content

Generally applicable within the constraints associated with the availability of different types of fuel

Coke oven gas pretreatment at the iron- and steel-works

Use of one of the following techniques:

Only applicable to coke oven gas combustion plants

Table 30

BAT-associated emission levels (BAT-AELs) for SO₂ emissions to air from the combustion of 100 % iron and steel process gases

Type of combustion plant	O₂ reference level (%)	BAT-AELs for SO₂ (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.
The higher end of the BAT-AEL range may be exceeded when using a high share of COG (e.g. > 50 %). In this case, the higher end of the BAT-AEL range is 300 mg/Nm³.
Type of combustion plant	O₂ reference level (%)	Yearly average^f1	Daily average or average over the sampling period^f2
New or existing boiler	3	25–150	50–200^f3
New or existing CCGT	15	10–45	20–70

Annotations

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: The higher end of the BAT-AEL range may be exceeded when using a high share of COG (e.g. > 50 %). In this case, the higher end of the BAT-AEL range is 300 mg/Nm³.