A simple modeling for performance prediction of a dry-feeding entrained bed coal gasifier

As the first phase of a national IGCC project, a conceptual design of each part of the IGCC components is being researched. In this study, a simple coal gasifier is modeled for performance prediction of a dry-feeding entrained bed coal gasifier and for reverse engineering of the Shell gasifier. The gasifier is the most important unit because the gasifier performance directly affects following units. Hence it is necessary to model the gasifier to analyze the internal process in the gasifier. The gasifier shape is simplified to one dimensional and pseudo two dimensional reactors for simple analysis. Coal gasification phenomena are simplified to three phases by difference of reaction rate. After the pyrolysis process, gas phase and solid phase reactions progress simultaneously. Simple chemical kinetics is applied to interpret the inner process. As solving the rate equations of Arrhenius type, it is possible to gain the property corresponding to the reactor height. Carbon conversion and cold gas efficiency are determined as an indicator of the gasifier performance. Oxygen to coal ratio, steam to coal ratio, and pressure are considered as operating variables because the gasifier performance is susceptible to the operating conditions. This model has basic problems because it has rough assumptions for considering turbulence, radiative heat transfer, and other physicochemical phenomena. Therefore this model may be best used to evaluate trends in performance of the coal gasifier for a variation in the operating conditions rather than to provide accurate values of the results.