燃气蒸汽联合循环热电联产机组热经济性分析

Thermal-economic analysis of combined heat and power generation unit of gas-steam combined cycle

通过比较不同工况下燃气蒸汽联合循环热电联产机组的热力学特性,找出机组热损失产生的位置和原因,为机组的优化运行和节能改造提供理论指导。本文首先采用热量法的正平衡法来计算机组的热效率;其次用反平衡法计算该机组的?损失,将计算结果与正平衡法相校核并加以分析;最后用?方法对燃气蒸汽联合循环热电联产机组进行能量损失和效率计算。比较热量法和?方法的计算结果发现:燃气轮机负荷增大对联合循环?损失和?效率影响较大,使得机组?效率也有所提高;机组?效率随着环境温度的上升稍有降低;燃气轮机?效率的变化决定了机组?效率的变化趋势,采用热电联产可有效提高燃气蒸汽联合循环机组的运行经济性。

The thermodynamic characteristics of combined heat and power generation unit of gas-steam combined cycle under different working conditions are compared to find the location and causes of the unit heat loss. It can provide theoretical guidance for the optimal operation and energy-saving transformation of the unit. In this study, thermal efficiency of unit is calculated by the direct balance method of the heat method at first. Then exergy loss is calculated by the indirect balance method, and the calculation results are checked and analyzed with the results of direct balance method. Finally, the exergy analysis method is used to calculate the energy loss and efficiency of combined heat and power generation unit of gas-steam combined cycle. By comparing the results of the heat method and the exergy analysis method, it is found that, the increase of engine load has a great influence on heat loss and efficiency of the combined cycle, which improves the unit exergy efficiency. The exergy efficiency decreases slightly with rising ambient temperature. The changes in the exergy efficiency of gas turbine determine the trend of changes in unit exergy efficiency, and the use of combined heat and power generation unit can effectively improve the operating economics of the gas-steam combined cycle unit.