Analysis Of Economy On Low Pressure Economizer Retrofit Of 150MW Unit Of Fossil Fuel

In recent years, low pressure economizer technology is widely used in thermal power plant, as the primary means of energy-saving emission reduction. After adding the low pressure economizer, on the one hand, can effectively reduce the temperature of boiler flue gas, guarantee the safe operation under suitable temperature of the desulfurization equipment; on the other hand, the tail waste heat boiler can be used to heat the condensate water out from the low pressure heater for improving the condensation water enthalpy value, so as to improve the heat the unit economy.First,this paper describes the present situation of 150 MW Unit of Fossil Fuel unit and then introduces the design principle of the low-pressure economizer technical transformation project of 150 MW Unit of Fossil Fuel. And economy for the modification of the low pressure economizer has carried on the forecast. Next determines the connection method of the low pressure economizer compared the parallel connection to the series connection. Determines the introduction of the low pressure economizer according to the best water temperature and low temperature corrosion problems of the heat exchangers. According to the designed parameters and considering the thermal economical effect, determines the point location of the low pressure economizer.According to the original parameters to calculate the thermal efficiency indexes such as the rate of steam, steam consumption, heat consumption rate, standard coal consumption rate, and then according to the parameters after the technical transformation, using equivalent enthalpy drop method to calculate the thermal efficiency indexes such as the modified steam rate, modified steam consumption, modified heat consumption rate, modified standard coal consumption rate, Compared the thermal efficiency indexes of in the front and back the thermal efficiency, finally concluded that the unit steam consumption dropped by 1.33 kg/s, the unit steam consumption rate decreased by 0.03kg/(kW·h), the unit heat consumption rate decreased by 90.57kJ/(kW·h), the unit standard coal consumption rate decreased by 3.368 g/(kW·h), the overall thermal efficiency improved after using low pressure economizer. Under the rated load, analyzed the thermal efficiency under different amount of shunt, optimal amount of shunt is obtained under the rated load. In shunt a certain amount of cases, analyzed the unit thermal efficiency under different load, got that the heat efficiency change value is increased with the loss of the load. Analyzed the efficiency of the low pressure economizer and concluded that we can save 3442 tons of standard coal each year, 43720 tons of water saving after the technical transformation.