| Steam turbine flow passage transformation technology is an effective approach to achieve higher energy efficiency in power plants.It has important theoretical and practical reference value to determine a reasonable method of steam turbine flow passage retrofit programme, especially in low pressure cylinder, which develops the turbine flow technique and study on the calculation method of steam exhaust enthalpy.First, analysis of the thermodynamic properties of water vapor and its mathematical description, introduces the methods of model construction and solution of water vaper in steam turbine. Explore the working characteristics of steam turbine flow passage, especially within the low pressure cylinder of steam flow characteristics and operating conditions, and the main regulation of the variation in the stage parameters, which can be set as the base of this research.Based on the theory above, the author conducted the analysis of turbine changing conditions, focused on the research of last stage characteristics, and put up with the rule of judgement on the turbine flow style. Meanwhile, by the serious mathematic deduction, we get a conclusion that the initial parameters are strictly equal to the stagnation parameters and spread it to the group stage, which completes the changing condition characteristic theory. And then combined with the Flugle formula, the scope of this formula has been widen.At last, for the operating characteristics of the turbine and the low-pressure cylinder exhaust characteristics in the wet steam region, analysis of the distribution of the low pressure cylinder level of loss, using a way that two-stage turbine efficiency approximately equal, established analysis model based on exhaust enthalpy controllable parameters of the turbine and conducted the error analysis. And an example to verify the accuracy of the model are around 0.2%, the maximum does not exceed 0.6%. fully able to meet the needs of engineering applications. |
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