افزايش قدرت توربين گاز در سيكل تركيبي براساس طراحي بهينه‌ي بويلر بازياب حرارت

Incensement of Gas Turbine Power in a Combined Cycle, based on Optimized Design of a Heat Recovery Steam Generator (HRSG)

يكي از موارد بازيابي انرژي، استفاده از حرارت گاز خروجي از توربين گاز است. «بويلر بازياب حرارت» تجهيزي است كه بازيابي حرارتي را در اين كاربردها انجام مي دهد. افت فشار گاز داغ عبوري از بويلر بازياب سبب افت قدرت در توربين گاز مي‌شود. لذا در اين مطالعه پارامترهاي طراحي بويلر بازياب ــ ازجمله پارامترهاي ترموديناميكي و هندسي ــ به‌عنوان پارامترهاي تصميم و با هدف افزايش قدرت توربين گاز در سيكل تركيبي بهينه شده اند. در اين تحقيق، به‌منظور بررسي تاثير بهينه سازي بر عملكرد بويلر بازياب، به مقايسه‌ي ميزان حرارت تبادل شده، سطح انتقال حرارت مورد نياز و بازده اكسرژي بويلر بازياب در دو حالت پايه و بهينه ي طراحي پرداخته‌ايم. نتايج نشان مي دهد كه افت قدرت توربين گاز در حالت بهينه ي طراحي نسبت به قدرت نامي توربين گاز به‌صورت تنها، حدود 1درصد است و نسبت به حالت پايه‌ي طراحي، كه حدود 5درصد است، بهبود يافته است.

Dealing with the increasing demand for electricity is one of the most challenging issues in developing countries. Electrical energy is a common kind of energy, and, in this regard, power plants play a key role in its production. Among different kinds of power plant, combined cycle power plants (CCPPs) have gained much attention. They are attractive options in the power generation field due to having higher thermal efficiency than individual steam or gas turbine power plants, and having less negative environmental impact. The most important part of a CCPP is the heat recovery steam generator (HRSG). The heat recovery steam generator (HRSG) is widely used in power plants for energy recovery and efficiency improvement. Therefore, optimization of the heat recovery steam generator (HRSG) is a key element in increasing the efficiency of the combined plants. Also, due to the large number of design parameters of HRSG, performing an optimization study is necessary for finding the optimum design. These parameters include thermodynamic variables, such as pinch and approach points, as well as geometric parameters, such as fins and tube characteristics. In this study, the design parameters of HRSG, such as thermodynamic and geometric parameters, have been optimized as decision parameters with the objective of incensing gas turbine power in the combined cycle plant. The optimization has been carried out using the Genetic Algorithm (GA). In this paper, a comparison between heat exchange rate, required heat exchanger area and the exergetic efficiency of HRSG is carried out for base and optimized cases, in order to consider the effect of optimization on HRSG operation. The results show that the ratio between the power loss of the gas turbine to the nominal power of the gas turbine (i.e. HRSG is not attached to the gas turbine) in the optimized case is 1 percent, which is an improvement over the base case, which is 5 percent.