Thermodynamic Efficiency Analysis Of Coal-based Power Generation Systems

Electric power production process is a significant way of energy consumption.Coal is the raw materials for the coal based power generation system.To achieve the high conversion efficiency of coal to electricity and to carry out policy of energy conservation and emissions reduction,it is a principle way to reduce the coal consumption in electric power production process.In this thesis, the investigation on optimizations of the heat transfer efficiency inside each individual component of the proposed process has been conducted using professional engineering software, Aspen Plus. Combining the major technical parameters into the optimal approaches implied in the professional engineering calculation and simulation, temperatures and pressures of inlet and outlet of each component as well as the thermal loads of each component have been identified, and parameters on thermal loads and condensation loads, and the process simulation of those parameters based on professional engineering software (Aspen Plus) with followed up an innovative exergy analysis have been determined.This thesis presented significant improvement of the generation efficiency through four approaches:1) the heat exchange water will be compressed before feeding into wall tube of boilers for water/energy saving; 2) the application of new heat exchange to improve heat transfer efficiency through direct flue gas contacting heat exchange prior to liquid-to-liquid heat transfer, and 3) recovery of latent heat of moisture in the flue gas, and 4) most importantly, the current heat exchange setup will make ambient pressure operation of heat exchange with corrosive flue gas using new heat exchange medium, which is heat exchanged by the conventional water/steam medium. The outcomes of this approach make the supercritical and ultra-supercritical plants easily achieve a prolonged service time of the regular heat exchange tube materials, leading a sound economics. The extra gain of electricity compensates for flue gas cooling, leading recoveries of both the latent heat and low temperature sensible heat, as well as water in flue gas. In this sorbent-assisted cooling practice, acid gases and trace metals are subject to a wet-condensation for the recovery of valuable chemical resources, such as acid and trace metal products in a cost-effective way. Another major benefits of the new plant reclaims a new water resource, which is condensed water from the exhaust replaces some of the tower water.The outcomes of this thesis provide a sound and solid scientific basis to the available preliminary engineering estimates, for the confirmation of the technical feasibility, and advantages in the thermal efficiency of the proposed process over the existing coal-fired utilities. The higher thermal efficiency could continue to maintain the use of coal as a primary fuel as usual even under carbon constraint environment, because the recovered energy could compensate most energy penalty caused by the parasite heat load of CO2 capture system.Coal combustion is a process that its physical energy convert to chemical energy. This process will produce large amounts of energy grade losses. This is the main reason for low efficiency of coal-fired power plant. IGCC is a process that can reduce the energy grade loss by coal gasification:1) Through gasification, coal is converted to gas, which can reduce the energy grade loss when burning.2) The exhausted gas can have a perfect match with steam cycle. The outcomes of IGCC in Aspen Plus indicate a 9.2% boost than traditional coal-fired power plant.