Air pollution controls for metal processing furnaces

A guidance note on local authority control of air pollution from furnaces used in metal processing has been issued by the Department of the Environment (DoE).1

Until recently it was open to doubt whether smaller reheat and heat treatment furnaces are subject to the local authority air pollution control system established by Part I of the Environmental Protection Act (ENDS Report 207, p 27 ). The matter was clarified by regulations enacted in April (ENDS Report 207, p 27 ).

Local authorities will now have responsibility for reheat and heat treatment furnaces in the 20-50MW(th) range. Larger individual units, or two or more units on the same site with an aggregate capacity of 50MW(th) or more, are regulated by HM Inspectorate of Pollution under integrated pollution control (IPC), and a guidance note for these was issued in February (ENDS Report 205, 27-9 ).

Operators subject to local authority control will have to apply for authorisation by 30 June in England and Wales, and by 31 July in Scotland.

The air pollution controls under the two regimes are similar. The most important provisions are the emission limits for particulates and sulphur and nitrogen oxides. Under both systems, existing processes will have to be upgraded to interim emission standards by April 1996, with full upgrading to the standards applicable to new plant being due by April 2001.

Compliance with the new plant limits for SO2 will probably be achievable in the smaller furnaces subject to local authority control by using low-sulphur fuels. The limits which take effect for existing processes in 2001 are in any event less stringent than those for plants subject to IPC where the fuels used are coke oven gas or other gases produced by the steel industry.

Compliance with the NOx limits which will apply to existing processes by 2001 may require the installation of flue gas treatment methods such as selective catalytic or non-catalytic reduction, particularly on furnaces where air is preheated to high temperatures, although novel combustion chamber and burner designs may suffice. The DoE has promised to review the limits as more information on the capabilities of NOx abatement techniques becomes available.

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