Reducing content of nitrogen oxide(s) in coke oven flue gas - by introduction of carbonaceous gas as reducing agent

摘要

In reducing the N0x content in flue gas from a range of coking ovens heated with burner and/or mixed gas, with combustion and withdrawal areas of the heating walls, a thermal N0x redn is initiated in the withdrawal areas by addn to the flue gas of a carbonaceous gas, esp a gas contg CH4, eg burner gas or natural gas, as reducing agent. Post-combustion may follow the thermal redn. The thermal N0x redn and/or post-combustion is initiated by introduction of the hydrocarbon gas and/or post-combustion air into the area of the upper reversing positions or the upper horizontal channels, or into the heating flues and/or regions of the regenerators. Introduction may be through horizontal feed pipes in the area of the lid of the oven, and through vertical channels into the withdrawal area, or may be to the foot of the heating flue through channels parallel to the usual channels for introduction of burner gas. At most 10% (0.2-5%) of the amt of heat of the normal heating gas is fed by the hydrocarbon gas introduced for thermal N0x redn and/or post-combustion. The gas needed for thermal N0x redn may be fed through the channels used for feeding burner gas while these are not charged with burner gas. ADVANTAGE - The N0x content of the waste gas is reduced during the operation of the coking ovens, and addn of NH3 gas is avoided. Only little alteration to the plant is needed.