In developed countries, coal power plants are often used to work in part load and possibly to follow the demand. Consequently, the transient behaviour of these power plants is a very important issue. In integrated coal gasification combined cycles (IGCCs), the complex interactions between the different parts of the plant make the process behaviour difficult to predict.

This paper describes a non-linear simulation model of the gasification island. It comprises mainly a module for the gasifier reactor with water walls, two different ones for the convective and radiant syngas coolers, a raw gas / clean gas heat exchanger and a simple module for the gas treatment. This latter is simplified because it has only a small influence on the transients of the plant given its low inertia. All these modules have been introduced into a dynamic computational tool previously designed to simulate the transients of gas combined cycles (Dechamps, 1995). The computational code, called CCDYN (Combined Cycle DYNamics), is a modular and flexible code, each module being a main component (like a gasifier, a gas turbine, a heat exchanger, …) solving a set of transient equations.

This paper also presents some results and demonstrates the interest of such a modelling. As an example, the gasification island of a coal-based IGCC is modelled in the case of different coal feed properties and the influence on the syngas composition is illustrated. Another example is the evolution with time of the various temperatures in the system during a start-up procedure and a load variation.

The thermochemical and physical properties used in the models are extracted from Barin (1989), from Perry and Green (1984) and from Dechamps (1995).

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