Coking plant with flue gas recirculation
Improvement in carbonization in a carbonization furnace and simultaneous reduction in NO x emissions is achieved by recirculation of waste gas from a coking oven back to the oven chamber, the downcomers, or the sole channel system.
1. A process for homogenizing burn-out characteristics and for reducing thermal NO x emissions from a non-recovery or heat-recovery coking plant having a multiplicity of coking furnaces, each coking furnace comprising a coking chamber delimited by oven doors, lateral walls, and an oven top, for a bed of coal or a compacted coal cake, and a lower furnace having a sole channel system of sole channels at least partially integrated below the coking chamber, comprising:
supplying primary combustion air into the coking chamber, transporting partially combusted coking gas from the coking chamber by means of downcomers to sole channel heating flues; supplying secondary air to the sole channel heating flues, further combusting the partially combusted coking gas with secondary air, forming a waste gas stream exiting the coking furnace into an external channel system; and recirculating the waste gas by means of a blower from the external channel system to at least one of the coking chamber, the downcomers, or the sole channel system.
2. The process of claim 1 , wherein waste gas is recirculated into the sole channel system.
3. The process of claim 1 , wherein waste gas is recirculated into downcomers.
4. The process of claim 1 , wherein waste gas is recirculated into primary air apertures in an oven door.
5. The process of claim 1 , wherein waste gas is recirculated into primary air apertures in the oven top.
6. A non-recovery or heat-recovery coking plant, comprising a multiplicity of coking furnaces, each coking furnace comprising a coking chamber delimited by oven doors, lateral walls, and an oventop for a bed of coal or compacted coal cake, a lower furnace having a sole channel system of sole channels at least partially integrated below the coking chamber, a plurality of downcomers to transport partially combusted coking gas from the coking chamber to the sole channel system, wherein a plurality of apertures are provided in sole channel partition walls between sole channels such that waste gas produced by further combusting partially combusted coking gas with secondary air is recirculated within the sole channel system, the apertures being closeable or adjustable, and further comprising a blower which recirculates waste gas from the coking plant into one or more of the coking chamber, the downcomers, or the sole channel system.