Research On Operation Optimization Of Cold End System In Thermal Power Units

Steam turbine cold end system is an important part of thermal power units. Keeping the unit’s cold end in the optimum operation condition has great engineering significance to improve the efficiency of the unit, and this is an important measure to ensure the economic operation of the unit. Condenser vacuum has an important effect on the energy consumption and the power generation efficiency of the unit. The vacuum of condenser is required to maintain an optimum value to ensure the benefit of unit. In view of its important role of the unit operation, it is very important to study on operation optimization of cold end system. Therefore, the following work has been done in this paper.Firstly, each impact of heat-transfer coefficient was generalized combined with the heat transfer process and empirical formulas, and a dimensionless quantity using for labeling condition was obtained based on similitude theory. The kc—M model using for calculating the condenser heat-transfer coefficient was identified ultimately using the data of different loads. The results showed that, this model avoided the calculation deviation from the correction of specific condenser in experience formula, and also avoided the limitations of test method that it could not obtain all possible conditions. The calculation model of condenser heat-transfer coefficient did a better job in describing the heat transfer intensity of condenser, and the relative error was less than 1.41% compared with the experimental data, which met the requirements of engineering application.Secondly, According to the actual situation of dispatching operation, the optimum vacuum of condenser was redefined. At the same time, the evaluation index of optimum condenser pressure was proposed that the heat-efficiency of power supply is highest in the condition of certain power. For this evaluation index, the condenser pressure with power calculation model was obtained using equivalent enthalpy drop method, and the calculation model of heatconsumption was established with the condenser pressure in the condition of certain power.Finally, using the optimization model of condenser vacuum, the water circulating pump in actual unit was optimized, and the optimized solution was identified. Results showed that, after optimization, the heat-consumption rate of power supply was reduced up to 151.8 kJ/(kW?h), compared with the situation that all conditions used A, B(high speed), C circulating water pump parallel operation mode. And the heat-consumption rate of power supply was reduced up to 97.5 kJ/(kW?h), compared with the situation that all conditions used A,C circulating water pump parallel operation mode. The heat-consumption rate of power supply get a significantly reduction.