Impact Of Fuel Gas Preheater On Gas-steam Combined Cycle

Due to environmental and energy requirements, gas-steam combined cycle power plant has been widely applied in electricity industry. Large-scale gas turbine power generation power plant has been introduced and operated more than ten years, certain amount of knowledge and experience has been accumulated, however some practical problems still exist.In a real HRSG, exhaust gas temperature has become higher than its designvalue. In order to study this problem, this paper firstly introduced the basic configuration of the combined cycle, the development status and trends of the HRSG. Via analyzing the structure of the HRSG, the characteristics of heat transfer surface and arrangement, this paper establishes the calculation model in the first place which conform to the thermodynamic constraints of design parameters on the basis condition of the HRSG, then gets the distribution of its temperature and exhaust gas resistance, finally summarize the rules. Through the calculation of the operatingparameters, this paper gets the distribution of the temperature, exhaust gas resistance and the energy exchanged to each surface and its share under actual operation.Considering the operation characteristics of HRSF’s installation, the most important system performance parameters such as heat transfer coefficient, temperature difference, correction factor and heat transfer surface structure remain roughly constant from year to year. Therefore, the shutdown of IBH system is the mainly cause of the rise of the exhaust gas temperature. On the basis of accurate modeling of annular combustion chamber, the flow field, combustion and NOx emission in this annular combustion chamber of standard operation condition and its fuel gas preheating conditions are calculated using CFD code Fluent 6.2.3. The influence rule of fuel gas pre-heating on NOx formation characteristic in combustion chamber are investigated in this paper.The thermodynamic results shows the temperature distribution in HRSG, make up the insufficient of the measuring point and provides a theoretical reference to solve the problem, which will be helpful to make the unit economical and efficiency.