Gasification of Coal and Heat Integration Modification for IGCC - Integrated Gasification Combined Cycle

Use of energy is closely related to the development of an economy. The most useful form of energy in the modern world is electricity. IGCC has higher fuel flexibility (biomass, refinery residues, petroleum coke, etc.) and generates multiple products (electricity, hydrogen and chemicals like methanol and higher alcohols) and by-products - sulphur, sulphuric acid, slag, etc. IGCC plants include coal preparation unit, air separation unit (ASU) to separate oxygen from air to use it in the gasification process, gasification unit where an incomplete combustion for coal is made to produce Syngas, cleaning unit to remove acid gases and CO2 from Syngas and a power station that contains gas turbines and steam turbines to produce electricity (Emun et al., 2010). In this work Heat Integration study is made to an IGCC plant whose feedstock is coal-water slurry with a flow rate of 3,020 t/d. The study produces a comparison between the capital investment and operating costs of the existing and the integrated IGCC plant and investigates the effect of changing the feedstock content on thermal efficiency, net power and cold gas efficiency. The Heat Integration considers Delta Tmin = 1.5 degrees C as for the existing plant, and results in savings of 47.5 % and 5.4 % as in the required heating and cooling duties. Three different feedstocks with the same flow rate 3020 t/d are used in this work to study their effects on the efficiency of IGCC plant; coal, coal-water slurry and a mixture of 93 % coal and 7 % ricestraw. Thermal efficiencies resulted due to the change in feedstock are 37 %, 36.6 % and 36.8 %, net powers are 337.5 MW, 334 MW and 337 MW while the cold gas efficiencies are 71.5 %, 70 % and 72 % for coal, coal-water slurry and (93 % coal and 7 % ricestraw).