Modeling And Performance Analysis Of Coal-based Syngas Solid Oxide Fuel Cell System

Energy is not only the physical basis of national economicdevelopment, but also the key factor for restricting the economic growth.In view of China’s basic national situation, coal will play a dominant rolein energy consumption in decades. However, conventional energyutilization methods can’t meet the needs of society today as a result oflow utilization of coal and huge damage of environment. Therefore, usecoal efficiently and cleanly is necessary to ease the energy pressure inChina. Integrated Coal gasification and solid oxied fuel cell combinedcycle system (IGFC/CC) can make full use of the high temperatureemission gas to improve the efficiency of power generation.As the core equipments of IGFC system, Coal gasifier and solidoxide fuel cell (SOFC) determine the performance of power generationsystem. In this paper, the performance and optimization analysis of SOFCare investigated according to the laws of conservation of mass、 energyand phase equilibrium with Aspen Plus software.By the method of modeling, the performance analysis conclusions ofIGFC system could be described as follows:(1) When fixed coal flow, effective gas content first increases andthen decreases with the increase of the ratio of gas to coal. The turningpoint is3.78;(2) When fixed coal flow and the ratio of gas to coal, effective gascontent first increases and then decreases with the increse of thedistribution of coal. The turning point is0.57. The distribution of coal hasno marked on the temperature of gasifier;(3) When fixed coal flow, the ratio of gas to coal and the distributionof coal, The effective gas content and the temperature of combustionchamber remain the same with the increase of the ratio of steam to coal; (4) Under the limitation of max temperature difference in SOFC,the average current density determines the optimal air excessivecoefficient. When fixed the average current density, the max temperaturedifference and output voltage decreases with the increase of air excessivecoefficient. When fixed air excessive coefficient, the max temperaturedifference increases with the increase of the average current density, andthe output voltage has the opposite trend;(5) The output voltage increases with the rise of the inlet temperature.But the amplification is not obvious, especially on the high temperature.Meanwhile high temperature will lead some other problems, such asthermal expansion;(6) The performance anlysis of coal flow is used to simulate thevariable load regulation ability of SOFC. With the increase of the coalflow, the maximum temperature difference and the fuel utilizationdecrease. However, the output voltage and the output power increase;(7) IGFC-ST system makes full use of the high temperature exhaustto improve the efficiency of power generation. Based on the law of massbalance to verify the rationality of the system model, and the result showsthat the system is reasonable;(8) IGFC/CC system has a higher efficiency because of the exploitof gas turbine and steam turbine. The efficiency of generation powerincreases with the rise of pressure.