Thermodynamic evaluation of IGCC (integrated gasification combine cycle) power plant using thar coal

Abstract

The power generation from coal using conventional coal fired power plant is not environmental friendly and it becomes expensive when flue gas emissions are considered in the system. The alternate option is IGCC power plant which is environmentally benign compared to traditional pulverized coal-fired power plants, and economically feasible compared to the natural gas combine cycle (NGCC). In IGCC, solid feedstock (coal, coke, wood, biomass, refinery residues) are converted into gaseous fuels (syngas) in the gasifier, and resulted hydrogen gas can be used in several applications such as electricity generation, refineries, production of chemicals (ammonia, methanol, Oxo-chemicals), methanation, and transportation fuels (fuel cells). IGCC power plant is more diverse and offers flexibility in fuel utility. A very low rank solid fuel such as lignite and biomass can be used directly in the gasifier without contributing to the environment pollution. Thar coalfields, located in Sindh (Pakistan), are lignite type coal with an estimated reserves of 175 billion ton, which is 2nd largest in the world. These coal reserves are divided into six blocks and each block of coal reserves have different composition in terms of moisture, fixed carbon, sulfur, volatile matter and heating value. In this paper, IGCC power plant is evaluated for six blocks of Thar coalfields by modeling the process using Aspen Plus process simulation software. The aim of this paper is to present performance evaluation of IGCC in terms of syngas composition, gasification performance and plant efficiency for Thar coalfields. The performance parameters of IGCC plant such as cold gas efficiency (CGE) and net efficiency of plant indicate that Block-5 is relatively more suitable for IGCC compared to other blocks of Thar coalfield. The model and simulation results may be used as a roadmap for the economic evaluation of the process equipment.