Cooling Turbine Modeling And Thermal Performance Analysis For Heavy-duty Gas Turbines

Heavy-duty gas turbines are vital technical equipment for energy restructuring,clean energy utilization and energy security.Turbine blade cooling is one of the significant means to increase the turbine inlet temperature and thus increase the gas turbine cycle efficiency.Establishing an accurate turbine cooling model is critical to accurately predicting thermal performance of gas turbines.This paper took GE’s different grades of heavy gas turbines as the research object,and established a simple thermodynamic equilibrium model,an empirical formula cooling model,a semi-empirical formula cooling model,a quasi-1-dimensional continuous expansion cooling model,and a 0-dimensional and quasi-1-dimensional joint model.System energy balance,coolant flow and its distribution were verified by mutual calculation and analysis of cooling models,and the progress of component performance,the machine performance and cooling technology of different grades of heavy-duty gas turbines were explored.The study can also provide a reference of the parameter values of different cooling models for different grades of gas turbine applications.The main work and results of this paper are as follows:1.Application and calibration of 0-D turbine cooling models on GE gas turbinesFirstly,with 9HA.02,9HA.01,PG9351FA,PG9231EC,PG9171E,PG6581B,PG6561B and other GE typical gas turbines as research objects,a simple thermodynamic equilibrium model was used to obtain key parameters of diverse gas turbines such as the ISO firing temperature,compressor polytropic efficiency and turbine polytropic efficiency.Afterword the sensitivity analysis was performed on the hypothetical gas turbine parameters.The energy loss was introduced when calculating the energy balance of the gas turbine system,and the data consistency of the gas turbine output power and efficiency was realized.Secondly,combined with the turbine inlet temperature,a 0-dimensional semi-empirical formula cooling model was built to estimate the coolant flow of the first nozzle.Meanwhile,the blade uniform temperature and cooling efficiency corresponding to diverse gas turbines were determined.The turbine inlet temperature of each gas turbine and the total coolant flow were obtained by utilizing the turbine inlet temperature estimating method.Calculation results reveal that the ratio of total coolant flow to compressor inlet air of B,E,F and HA gas turbines is about 16%,18%,20%and 22%respectively.And as the level increases,turbine inlet temperature increases significantly,and turbine inlet temperature of the latest 9HA.02 gas turbine reaches 1654℃.Additionally,using data of the gas turbine with known combustor outlet temperature,the Jonsson empirical formula model parameters,which are applicable to gas turbines of GE company,were optimized.And the calculation results of total coolant flow and first nozzle coolant flow were checked.2.0-D and quasi-1-D joint model and its application on PG9351FA gas turbineIn the absence of detailed gas turbine cooling information,the cooling technology level parameter Z in quasi-1-D model and the blade uniform temperature in 0-D semi-empirical formula model generally depend on experience.In order to eliminate the uncertainty brought by the empirical parameter selection to the gas turbine simulation,a joint calculation model was established,which integrates the semi-empirical formula turbine cooling model and the quasi-1-D turbine cooling model.The blade uniform temperature and the parameter Z were taken as model outputs and the coolant flow for a single blade row with known inlet temperature of main gas flow can be calculated with the joint model.The joint model was used to analyze the first nozzle of GE PG9351FA,and the results were verified by the quasi-1-D cooling model with continuous expansion method.After that,the influence of the turbine inlet temperature on the calculation results of the joint calculation model was analyzed,including the total coolant flow and the parameter Z.The joint model parameter analysis illustrates that key ways of increasing turbine inlet temperature is increasing temperature of blade material and improving the convective cooling technology.And the former has less influence on the coolant demand.3.The parameter analysis of 9HA.02Via the calculation of the joint model of first nozzle and the quasi-1-D continuous expansion model of the entire gas turbine,parameter analysis was conducted on 9HA.02,the latest gas turbine type of GE company.The cooling and material technical level parameters of the H-class gas turbine including the film cooling coefficient,the thermal barrier coating Biot number,and the blade wall Biot number were obtained by model calculations.Since the first nozzle of 9HA.02 adopts a new type of directionally solidified single crystal alloy material,maximum allowed blade temperature difference of the first nozzle and the cooling turbine section was obtained as 200℃ and the maximum allowed temperature of first nozzle is 1090℃,greatly improved in comparison with the F-class.And it was found that the coolant amount of first nozzle accounts for about 1/4 of the total coolant in 9HA.02,which was significantly lower than F-class gas turbines’ 1/2.When using the turbine cooling technology level parameter of the F-class gas turbine to calculate the performance of the 9HA.02 gas turbine at the same turbine inlet temperature,the proportion of coolant flow was increased by 35.9%,so that the gas turbine efficiency was lower than that of the PG9351FA,indicating that the cooling technology of HA-class gas turbine has a significant improvement compared with the F-class.Based on the 9HA.02 parameters,the influence of the "cooling-material" level on the thermal performance of the 9HA.02 gas turbine was analyzed.