Thermoeconomic Analysis Of Coal Poly-Generation Energy System

Coal consumption takes up more than 60% in our primary energy consumption, and this status will not be broken in short time. The rapid development of economy promotes the increase of energy supply drastically, and the sustainable development of economy is facing intense pressure between the limit of energy resource and pollution of environment. Many scholars have put forward that the poly-generation energy system may be a distinct approach to solve the sustainable development of energy. Poly-generation (heat, electricity, coal gas and tar) energy system based on coal has been developed by Zhejiang University is remarkable in enhancing energy utilization efficiency, but there are not any literatures about the analysis of poly-generation from thermoeconomics point. In the present work, the 75t/h CFB poly-generation energy system(heat, electricity, coal gas and tar) cooperate between Zhejiang University and Coal Preparation Plant of Huainan is analyzed through employing thermoeconomics structural theory, which combines with the physics environments of energy and economic. Then the distribution and process of cost of products are arrived.Firstly, this poly-generation energy system is divided into eight components, then the physical diagram and productive diagrams are drawn. According to the physical diagram and productive diagram, the thermoeconomics cost relations of fuel and products are also attained, these relations are formulated to algebraic equations following the Structural Theory of Thermoeconomics. The exergy and thermoeconomics costs are calculated. Based on the relations, the unit thermoeconomics cost of terminal products between the two-generation ( heat and electricity ) and poly-generation system ( heat, electricity, coal gas and tar ) are analyzed, and the influence of different fuel price to the unit thermoeconomics cost of terminal products are also analyzed. At last, the unit thermoeconomics cost of fuels and products at different gasification temperature(600℃,700℃,800℃) are compared. These results can play a key role for analysis and assessment of operation and be a reasonable basis for products pricing, optimizing design, and malfunction diagnosis.The results indicate that: the unit thermoeconomics cost of terminal products of poly-generation is lower about 20% than two-generation energy system, so the poly-generation energy system can enhance energy utilization efficiency and decrease the cost of products; the unit thermoeconomics cost of products increase with the increase of price of unit fuel; when the gasification temperature increase, the exergy efficiency of components and whole system are improved, the rate of gasification increase, which contribute to the decrease of the unit thermoeconomics cost of products.