Research On Flow Characteristic And Energy Consumotion Analysis Of Supercritical Steam Turbine Unit

With the implementation of saving energy and declining energy loss in power plant and the increasing request of the units’s operational level, it is very important to do deeper analysis on energy consumption. Energy-loss analysis is one of the essential basic theoretical works for coal-fired power unit energy conservation and coal consumption decrease.Main steam flow is an important parameter in performance monitoring and process control and requires accurate measurement. Accurately acquiring the flow characteristics is the premise of realizing reliable energy-loss analysis. Presently, many flow characteristics experimental researches have been carried out for low-parameter steam turbines, but few for supercritical steam turbines which have big errors. Critical pressure ratio of governing stage has important significance on improving the calculation accuracy of flow characteristics. The actual main steam flow can be calculated and the error is controlled in1%.In this paper, taking a600MW supercritical steam turbine for example, critical pressure ratio can be obtained accurately by theoretical analysis. Relationships between critical pressure ratio, steam flow, reaction degree and speed ratio are studied. The effects of steam parameters, steam distribution modes and structure sizes on the critical pressure ratio of governing stage are analyzed too. Analysis shows that the critical pressure ratio of governing stage is a constant only related to its structure parameters, which has no relation with steam parameters and steam distribution modes of units. Compared with flow characteristics test and actual operation data, the accuracy of theoretic calculation and analysis is verified.Take a1000MW supercritical heating unit for example, the energy-loss analysis model is established on the basis of thermodynamic method and equivalent enthalpy drop method. Coal consumption caused by controllable parameters and uncontrolled parameters deviating from base values could be calculated quantificationally. And the exergy economy of supercritical unit has been calculated and analyzed by the exergy analysis method. The essence of energy consumption is really reflected. Compared with the energy analysis result, the loss distribution of the thermodynamic system is put out factually. When connecting to the database of power plant, the main economy indexes of thermodynamic system can be calculated online, and the operating parameters affecting the thermoeconomy of unit can be supervised and analyzed continuously.The distribution of the loss of energy of the unit can be diagnosed online. The economy of unit operation is improved greatly.