Experiment And Numerical Calculation Of Flue Gas Flow In Inlet Flue Of HRSG In CCPP

Gas-steam combined cycle power generation system（CCPP）is one of the key tasks of China’s "Energy Development" 13th Five-Year Plan.The HRSG（heat recovery steam generator）is the key equipment in the CCPP.The power generation efficiency of CCPP is determined by the scale and energy conversion efficiency of the HRSG.One of the difficulties in the largecapacity and localization of HRSG is to solve the problem of uniformity of gas flow in the furnace and to enhance heat transfer.Among them,the inlet flue is connected with the gas turbine and the HRSG body,and its structural type directly affects the uniformity of the gas flow and the heat exchange in the furnace.However,the current flue gas velocity distribution in the inlet flue of different structures of HRSG in CCPP is not perfect,and relevant experiments have not been carried out.At the same time,the effect of the supplemental combustion device on the heat transfer of flue gas in the flue is less studied.Based on this,a domestic F-class gas turbine cogeneration project was researched as an example.The experimental device for visualizing the flue gas flow of the inlet flue is designed and constructed in a ratio of 1:12.The distribution of flue gas velocity in the inlet flue and the influence of different elevation angles on the flue gas flow are preliminarily studied.Four different elevation angles and three kinds of guidance are established.The three-dimensional model of the inlet flue of the flow board scheme is used to study the basic laws of flue gas flow in the inlet flue of different structures,and the standard deviation analysis method is used to judge whether the velocity distribution of the outlet section is uniform;the internal combustion of the inlet flue of the HRSG is set.The device is used to carry out the exploration of the flow field and temperature field distribution in the inlet flue of the burning HRSG by numerical simulation.The main research contents and conclusions are as follows:（1）In the space near the bottom of the flue,the velocity of the flue gas rapidly increases to the maximum value.As the height increases,the velocity gradually decreases,and the velocity of the velocity to the central recirculation zone decreases sharply,and the entire upper part is the recirculation zone.The velocity in the recirculation zone is small until the top velocity approaches 0;as the section position moves toward the center,the proportion of the high-speed zone is larger,and the reflow center is gradually moved upward.（2）The elevation angle on the flue affects the distribution of smoke flow in the flue.When the elevation angle α₁ of the first segment is constant and the upper elevation angle α₂ of the second segment is decreased,the proportion of the high-speed zone is decreased,and the upper recirculation zone is increased;When α₂ is constant and α₁ decreases,the proportion of the high-speed zone is larger,the upper recirculation zone is decreased,and the outlet cross-section center position is moved upward.（3）The most uniform distribution of the flue gas velocity at the exit section is the flue which the elevation angle are 30°and 70°,and the standard deviation of export speed is 1.2195.Three different kinds of baffles are installed in this model,and the standard deviation of export speed can be reduced to 0.7812,which greatly improves the uniformity of smoke flow.（4）The flue gas high-speed zone in the inlet flue with supplemental combustion device is mainly concentrated in the bottom of the flue and near the incinerator.The maximum speed can reach 26 m/s,which is obviously improved.The gas is sprayed from the make-up port and is in the shape of a typical torch.The high temperature zone is near the gas nozzle and the temperature in the horizontal direction is continuously decreasing.As the gas velocity increases,the range of the high-speed zone in the lower part of the flue gradually increases,the position of the upper recirculation zone gradually moves upward,the length of the flame gradually lengthens,and the area of the high-temperature zone becomes larger.