Rotor Ventilation System Study And Structure Optimization Of 350MW Air Cooled Turbine Generator

Energy demand is declining now and energy structure is transforming consequentially,but the power generation by coal is still a major part of domestic new increasing energy,so turbine generator will continue to be an important part of the power generation equipment for the future.Because the generator with high capacity can improve the efficiency of energy conversion,reduce the costs of construction and operation,the single-unit capacity of turbine generator is continuously increasing.However,the rotor cooling channels in turbine generator are small in size and complex in structure,the distribution of cooling fluid in these channels should meet the cooling requirements in different parts,so the cooling ability of rotor is the key issue for the capacity upgrading of turbine generator.At present,350 MW has reached the limit capacity of air-cooled turbine generator,the heat load of which also increases significantly corresponding to the lower capacity one,therefore,the study and optimization of rotor ventilation system can avoid the overheat of rotor’s coil,and can make sure that the temperature rise meets the requirements of temperature-rise limit.In this dissertation,the internal interaction of ventilation system in turbine generator is considered,and the analysis method based on numerical simulations is used to study the whole flow field of 350 MW turbine generator,so as to obtain the rotor’s optimized structures,and to improve the characteristics of flow field and cooling capacity in rotor.Firstly,in order to simulate air flow in rotor ’s ventilation system accurately,it builds the three-dimensional physical model of 350 MW turbine generator,and then determines the computational domain.Based on the variant design of rotor structures,the flow fields of the whole generator based on numerical simulation are carried out so as to get the flow characteristics of generator.Secondly,according to numerical simulations of flow field,the temperature rises of rotor in different rotor ’s structures are obtained.Therefore,it can be easily to obtain the temperature distributions of rotor ’s ends and straight sections,and the temperature rise of rotor under different flow characteristics.Finally,the temperature-rise test of rotor is carried out after the design and manufacture of prototype machine,and the cooling effect of rotor is investigated.The results show that the temperature rise of generator ’s rotor is reasonable and the cooling performance can meet the requirements of operation.