OPTIMIZATION STUDIES OF COMBINED CYCLE PLANT WITH COAL GASIFICATION AND HIGH TEMPERATURE HEATED COMBUSTION AIR

Abstract

Relevance. Integrated gasification combined-cycle plants are considered as one of the promising directions for development of thermal power plants using fossil fuel. Interest in this area is explained by large natural reserves of coal and minimal harmful emissions into the atmosphere during generator gas combustion. The air enriched with oxygen is mainly used to improve gasification, which is quite expensive and leads to an increase in the cost of the installation. Another way to increase the calorific value of the generator gas is to supply air heated to a high temperature (1000 °C or more) into the gasifier. The conventional tubular recuperative heat exchangers do not allow such heating. The only real way to heat the air to the specified temperature level is to use the regenerative heat exchangers of batch operation with ceramic backfilling. The aim of the study is to make a rational choice of the flow chart of integrated gasification combined-cycle plant with the use of the air preheated to the high temperature, to find optimal cycle parameters and design parameters of individual elements, and to perform the optimization researches according to the criterions of minimum electricity price and energy efficiency for estimation of competitive conditions for the considered integrated gasification combined-cycle plant. Methods. Complex heat and power systems, including integrated gasification combined-cycle plant, are characterized by the diversity of processes occurring in their elements. The only way for effective studies of these systems is using the methods of mathematical modeling and optimization. А methodical approach developed at ISEM SB RAS was used to compare the efficiency of thermal power plants when carrying out optimization studies in this work. It is based on the joint optimization of cycle parameters and design parameters of individual elements. Results. The authors have carried out technical and economical optimization studies of integrated gasification combined cycle plant. The facility was considered both with the use of high-temperature air heated in a system of ceramic heat exchangers of batch operation, and without such heating. It is shown that the supply of high-temperature heated air to the gas generator does not lead to a significant improvement in the technical and economic parameters of the integrated gasification combined-cycle plant, but it allows obtaining more calorific gas with comparable values of the energy efficiency and electricity price.

Keywords

• high-temperature air heating
• integrated gasification combined cycle
• air-blown gasification
• mathematical modeling
• technical and economical optimization studies