The present invention relates to a method of cooling retort or chamber coke.
Aside from the conventional wet quenching where, as a rule, the sensible heat of the coke is not utilized at all, or recovered only to a very small extent, dry cooling of coke is known in which the heat of the retort or chamber coke having a temperature of about 1,000.degree. C. is removed by a circulated gas and utilized in a waste heat boiler for producing steam. It is further known to use this steam for preheating the moist coking coal, with the heat being transferred to the coal, for example, in a fluidized bed or rotary drum drier through suitable heating surfaces (see German patent application Nos. P 30 13 325.6 and P 30 34 952, U.S. Pat. Nos. 4,354,903 and 4,422,858, respectively, which are here incorporated by reference).
It is also known to supply the chamber coke having a temperature of about 1,000.degree. C. to a first cooling and gasification stage for partial degasification under the addition of steam and to cool it down to 500.degree.-800.degree. C., and then to direct it through a pressure metering system to a pressure-type gasifier where it is gasified by fixedbed gasification while adding air or oxygen, and steam (German application No. P 30 32 212.4 or U.S. Pat. No. 4,422,858 also incorporated by reference).
With such coke cooling methods, the produced steam can only be employed for preheating the coal to be coked, in view of the heat economy of the coking plant. Exceptionally, a power plant may be in the neighborhood of the coking plant, where the steam from the dry coke cooling may be used for generating power. However, this is not the case as a rule. Further, if the steam is employed for preheating moist coking coal, as usual, only superheated steam is used for transferring the heat to the coal through indirectly heated surfaces. This means that, as compared to the relatively high temperature of about 1,000.degree. C. of the coke coming from the chambers, the heat is utilized at a relatively low temperature level (t=232.degree. C. at 30 bar, or t=249.degree. C. at 40 bar) large heat exchanger surfaces or, in addition, special and very expensive measures must be provided (such as a fluidized bed) for improving the heat transfer.