This invention relates in general to the operation of coke ovens and in particular to a new and useful method of desulfurizing coke oven gases wherein sulfur containing waste gases are directed to association with ammoniated water to expel the ammonia therefrom which is carried over with the gases into the hydrogen sulfur scrubber tower to which the coke oven gases are passed.
While carbonizing coal, coke oven gas is obtained containing components which are harmless in later use of the coke gas, but also components which must be removed in a coke oven gas cleaning process. Among the latter components, it is hydrogen sulfide which must be removed from the coke oven gas in hydrogen sulfide scrubbers and then processed to sulfuric acid or elementary sulfur in a so-called Claus plant. During the combustion of hydrogen sulfide with air supply, to elementary sulfur, a waste gas is obtained still containing various sulfuric compounds.
In this method, the waste gas, prior to being introduced into the coke oven gas conduit, may be treated with an aqueous ammoniacal liquor which is obtained from the crude coke oven gas. In accordance with the effect expected while applying this prior art method, it is provided and necessary to cool the waste gas prior to introducing it into the hydrogen sulfide scrubber. This must not affect the hydrogen sulfide scrubbing process, i.e. a high degree of hydrogen sulfide absorption must be maintained. This prior art method does not provide any improvement in the degree of desulfurization, nor is such an improvement sought or achieved.
What is sought is only a utilization of the waste gases leaving the Claus patent so as to make them harmless either completely, or to a high degree. It is further disadvantageous in this prior art method that the waste gases leave the Claus plant with temperatures of 120.degree. to 150.degree. C. and must then be cooled at adequate costs. Their considerable heat content is transmitted to the cooling water without any utilization. This is technologically unsatisfactory and uneconomical.
German Pat. AS No. 22 57 023 discloses the removal of sulfur compounds still present in the waste gas from a Claus plant. In this reference the waste gas is mixed together in a conduit upstream of a tar separator and/or a benzene scrubber and/or a hydrogen sulfide scrubber. This reference discloses the type of prior art process discussed above.
U.S. Pat. No. 3,789,105 to Tippmer et al discloses a hydrogen sulfide stripping method for coke oven gases and provides two different washing liquor circuits. The use of gases containing sulfur compounds, and in particular the waste gases of a Claus process, are not taught however nor is it taught to supply such gases along with coke oven gases into a scrubber. U.S. Pat. No. 4,302,430 to Weber et al discloses the use of hot waste gases containing sulfur compounds for stripping ammonia from ammonia liquors and supplying the cooled waste gases loaded with ammonia to a scrubber into which a crude coke oven gas is also supplied. This reference however does not teach that waste gases from a Claus plant can be used as the sulfur containing compounds.
USPTO Backgrounds
USPTO Backgrounds