Dynamic Modeling And Simulation Of A Micro Humid Air Turbine

Humid Air Turbine (HAT) cycle is an important research direction of new advanced gas turbine cycle. Since been proposed twenty years ago, the thermodynamic analysis and key technology research of HAT cycle have been carried out, and the cycle research will focus on the prototype experiment and demonstration in the near future. As a means of plant performance research, dynamic simulation plays an important role in the plant operation, fault diagnosis, control system design, staff training and so on. With the development of HAT cycle, the dynamic simulation and the dynamic performance analysis of small HAT cycle become important issues to be solved.Aiming at this problem, the dynamic model of micro HAT cycle with control system was established; the dynamic performance of simple cycle, recuperative cycle and HAT cycle was analyzed and compared during the startup, load change and shutdown processes; the system performance with different controller modes and parameters, different rotational inertia, volume inertia and thermal inertia was compared respectively. Finally, the dynamic performance during those typical dynamic processes was verified by the results from operating experience in the100kW micro HAT prototype experiment device. The main works and conclusions are as follows:1. Key components models of micro HAT cycle were built, including compressor, combustor, turbine, heat exchanger (gas-gas heat exchanger:recuperator and gas-liquid heat exchanger:aftercooler and economizer), humidifier, shaft rotational inertia model, volume inertia model, thermal inertia model, fuel supply system and control system.2. The dynamic model of micro simple cycle, which is the key unit of the micro HAT cycle, was built; the dynamic performance of startup, load change and shutdown was analyzed, and the system performance with different controller modes and parameters, different rotational inertia, volume inertia and thermal inertia was compared respectively. It is proved that, a smaller inertia yields a faster response of simple cycle during those typical dynamic processes; during the startup and load change processes, the volume inertia can be ignored, but the volume inertia of the high temperature zone should be considered during the shutdown process; and the thermal inertia should be considered during all those dynamic processes, especially the high thermal inertial; the overspeed of the simple cycle is maintained within reasonable range during the load rejection process, which is the largest load disturbance.3. The dynamic model of the micro recuperative cycle was built, the differences between simple and recuperative cycle during those typical dynamic processes, were compared. It is proved that, the thermal inertia of recuperator is so large that cannot be ignored. During the load rejection process, recuperative cycle have to control the gas valve to avoid the high overspeed.4. The dynamic model of micro HAT cycle was built, the dynamic performance of two starting sequences, one with the humidification process fully integrated from the beginning (humid mode) and one without (dry mode), was compared, and the differences of simple cycle, recuperative cycle and HAT cycle were compared during startup and load change processes. It is proved that, the two starting sequences can both start quickly. The large thermal inertia of the HAT cycle makes a high overspeed during load change process. During the load rejection process, except for the gas valve control method, it is has to bleed off the compressed air from the compressor, in order to avoid the high overspeed.5. Based on the maximum likelihood estimation method, the compressor characteristic model parameters and the design parameters of micro gas turbine's components were estimated from the experimental data; with this information, the dynamic model of the micro HAT cycle based on micro gas turbine was built, and the dynamic simulation processes were validated by the experimental data of the100kW micro HAT prototype experiment device.These conclusions provide references for the development, application and control system design of the HAT cycle.