How do I calculate chimney height for fan-diluted emissions below roof level?


The Chimney Heights Memorandum advises that certain fan-diluted emissions may be discharged at heights below the roof level of the building or directly through the roof without a definite chimney. This might lead to local exceedences of the prescribed annual mean objective for nitrogen dioxide in areas where there is already a significant background concentration of nitrogen dioxide or where there are places where members of the public might be regularly exposed to the discharge. The potential for exceedance of the objective may be assessed using the Industrial Emissions Screening Tool, available hereAlternatively, the following Table provides thermal input rate screening limits for fan diluted boilers with low NOx burners (<0.02g/MJ). Larger boilers will require more detailed assessment using an appropriate dispersion model. The information is based on the report here.

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