| In order to achieve sustainable economic development,China has put forward the requirement of ultra low emission for coal-fired units.The most widely used wet desulphurization technology in China has increased the water consumption of the boiler when removing the SO2 from the flue gas.Because of the increase of the humidity of the flue gas leaving the desulfurization tower,the flue gas discharge into the atmosphere and caused the environmental problems such as "plaster rain" and"white smoke plume".Aiming at this problem,the condensate method is applied to develop the new fluorine plastic flue gas cooler,and the research on integrated recovery technology of flue gas waste heat and moisture is carried out.This thesis takes the 330 MW coal-fired unit of Tianjin Guodian Jinneng thermal power plant as the research object,and carries out the research on the technical scheme of the integrated recovery technology of the flue gas waste heat and water.The thermal performance of three waste heat utilization schemes,named as the conventional low temperature economizer,integrating low temperature economizer with air heater and Integrating bypass flue with low temperature economizer,are compared.On the basis of the comparition results,a two-stage double utilizations integrated recovery system is put forward.A new fluorine plastic flue gas cooler suitable for flue gas waste heat and moisture recovery has been developed.Through the experiment,the acid corrosion resistance of DD anticorrosion coating,G3(enamel)anticorrosion coating and fluoroplastics heat transfer tube was compared.The new flue gas cooler was developed on the basis of fluoroplastic tube with good corrosion resistance.The fluoroplastic flue gas cooler was designed and manufactured for pilot test.The heat transfer,resistance and condensation and dehydration performance of the fluorine plastic flue gas cooler were tested.The experimental results show that the heat transfer efficiency of the fluoroplastic tube with small tube diameter and thin wall thickness can be greatly improved.The heat transfer coefficient of the fluoroplastic flue gas cooler reaches 150?163 W/(m2·?)when cooling the original flue gas,and reaches 380?400 W/(m2 ?)when cooling thenet flue gas.Fluorine plastic flue gas cooler can realize the integrated recovery of flue gas waste heat and moisture by condensing flue gas,so that the moisture in flue gas can be removed.The operation characteristics of integrated recovery system of flue gas waste heat and moisture were studied.The simulation model of the residual heat and water recovery system of flue gas is constructed.The simulation results show that the use of waste heat and the input of the integrated water recovery system have little influence on the stability of the thermal power unit,and the control system of the original unit can ensure the regular operation of the unit.The thermal economic analysis of the system shows that after the integration of the integrated recycling system,the unit costs of the main components of the unit have decreased,and the efficiency of energy saving is achieved.In Tianjin Guodian Jinneng thermal power plant,the demonstration project of integrated flue gas heat recovery and moisture recovery is carried out.By comparing the data analysis of the system for 9 months and the performance test of the unit before and after the system put into service,the accumulative recovery of the condensing water of the flue gas is 26400 tons,and saving about 77%of the water consumption of the desulfurization system.Under the rated condition of 330 MW,the moisture content in the flue gas can be recovered by 6.4 t/h,the coal consumption of power generation is reduced by 3.09 g/(kW h),and the concentration of the solid particles at the outlet of the desulfurization tower is 8.08 mg/Nm3,which reaches the standard of the ultra-low emission of 10mg/Nm3.The system has a certain dedusting function while recovering flue gas heat and moisture,which provides a new way for controlling particulate matter emissions of coal-fired boilers. |
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