Thermodynamic Performance For Gas Turbine Cycle Applied Technology Of Methane Reforming

The advantages of gas turbine are approved by people, but traditional simple cycle has some inherent disadvantages, such as low thermal efficiency and high excess air and emission pollution. So gas steam combined cycle is researched to enhance the thermal performance of gas turbine cycles, however, these studies adopt the methods of direct combustion which has many drawbacks, and are limited to the graded use of physical energy, seldom involved chemical energy utilization in combustion reactions.Firstly, a new gas turbine cycle is presented, methane is used as fuel. In combustion chamber of new cycle, there not only has combustion reactions, but also has methane reforming reactions which can absorb combustion heat. The innovation of new cycle is applying reforming technology to dynamic system, to achieve the purpose of increasing thermal performance and energy cascade utilization. The content of research has high academic value and wind application prospect.Secondly, system process and mathematics model of new cycle are established, and independent reaction numbers are confirmed by the method of calculating equilibrium constant. Based on the first law of thermodynamics, thermal efficiency and specific work are researched. The results show that thermal efficiency of new cycle increases with the increase of pressure ratio and inlet temperature of turbine. Compared to simple cycle, the thermal efficiency and specific work of new cycle are improved.Thirdly, new cycle's exergy efficiency is analyzed based on the second law of thermodynamics. The result shows that new cycle's exergy efficiency is higher than simple cycle, and it increases with the increase of pressure ratio and inlet temperature of turbine. The main reason is that new cycle's exergy loss decreases drastically because of methane reforming, so the exergy efficiency of combustion chamber improves.Finally, reheat cycle, which uses the syngas produced in new cycle as reheat fuel, is researched. The results show that reheat cycle has much higher specific work than new cycle without reheat. Thermal efficiency of new cycle with reheat can be improved when total pressure ratio is big and low pressure turbine inlet temperature is high. The optimal middle expansion ratio corresponding to the highest specific work is higher than that corresponding to the highest thermal efficiency, but it is much less than the optimal value of simple cycle. The essential reason of improving thermal performance is that new cycle makes full use of chemical energy in combustion process, reduces the gap of chemical energy level and physical energy level.