In the combined cycle power generation plant for coal gasification, it is necessary to establish a coordinated control for the gasifier and the gas turbine according to a load. Therefore, a dynamic model which expresses system's dynamic behavior with regard to various kinds of coal and operating conditions is required.
In this paper, a dynamic model dealing with an air blow pressurized two-stage entrained bed gasifier is first considered. And then, it has been confirmed that this model is valid by comparing the dynamic responses of this model with those of 2 tons/day bench scale gasifier.
In the entrained bed gasifier, intricate chemical reactions predominate between coal particles and gases in flowing state and hence it is difficult to describe the reactions exactly. Since our object is to control the gasifier's operation, the model has been so simplified as to fully indicate the behaviors of the air blow two-stage entrained bed gasifier (the gasifier has been lumped into two parts- upper and lower parts-, and have taken only the reaction of carbon, hydrogen and oxygen have been take into acount).
The results of the dynamic simulation of the present model are as follows: in the entrained bed gasifier, the residence time of coal particles is very short (about ten seconds), and the responses of the produced gas property, the gasifier temperature and the gasifier pressure are extremely fast corresponding to the change of coal-feed rate or air-feed rate. From these results, it is important to control the coalfeed rate, the air-feed rate and the gasifier pressure for the stable and sustained operation of the gasifier.
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