Study On Integrating A Gas Turbine In Steam Methane Reforming Process

The original route in the steam methane reforming process has some problems such as the low energy recovery efficiency from the F101 outlet gas.So,a new process of turbine integration is proposed,which means that the F101 outlet gas expands in the turbine for power producing and then into the heat recovery steam generator(HRSG)for medium pressure steam producing.The main research work includes the following parts.Based on the Pinch and exergy analysis,the optimization direction and potential of the new process is proposed.As a result,the operating pressure and temperature of F101 should improve and the operating pressure and temperature of PSA should reduce as far as possible but within the range of engineering permit.The mathematical model of the new process with turbine integration is formulated,including turbine,HRSG,reactor,gas-liquid separation drum,cooler,compressor and PSA operating unit.Based on this model,reaction pressure(P1),turbine outlet pressure(P2)and turbine isentropic efficiency(ηgt)are set as the design variables,and the optimal design method of new route is suggested with single objective function called minimum exergy loss of process((35)Exl).Thinking about the economic profit of the new process,the optimal design method of the new route is proposed with multi-objective function called the maximum total annual profit(TAP)and the minimum exergy loss process((35)Exl).The NSGA-II algorithm is used in the Matlab to calculate the Pareto frontier result.In the single objective optimization,ηgt,P1,and P2 have reached the extremes within the specified range.However,in the multi-objective optimization,the distribution of ηgt is highly concentrated in the upper limit,indicating that ηgt is beneficial to the double targets.However,the distributions of P1 and P2 are scattered,which indicates that their influence on the double targets is contradictory.In the multi-objective optimization,the point B on the Pareto frontier shows that the turbine integration new process increases the F101 operating parameters from 850℃/3.05 MPa to856.8℃/3.27 MPa,which receives the turbine shaftwork of 5493.41 kW.The B102 inlet gasreduces from the 850 ℃/3.05 MPa to 765.83 ℃/2.21 MPa,leading to the steam reduction of7.05t/h in the system.However,the TAP of the system increases by $ 1.04 million$/year and the process exergy loss reduces by 17.4%.