Application Research On Wet Desulfurization Wastewater Treatment Technology In Thermal Power Plant

Desulfurization wastewater is the end of wastewater concentration in the thermal power plant.It contains many harmful impurities to the ecological environment.It must be treated strictly before discharge.Our country’s environmental protection standards are more and more stringent,the traditional desulfurization wastewater treatment technology has been difficult to meet environmental protection requirements,and desulfurization wastewater treatment has become one of the important factors restricting the development of thermal power industry.Therefore,a new desulfurization wastewater treatment technology is of great significance for the development of thermal power industry.This paper proposes a technical scheme of zero discharge treatment of desulfurization wastewater(Fully softening pretreatment→ Expansion evaporation concentration→Vacuum membrane distillation concentration→Evaporation crystallization).The mechanism of capacity expansion evaporation technology was studied,and the basic equation of flash evaporation process was established.Based on the conservation of mass and energy,a mathematical model of the dilatant evaporator is set up,and the expression of steam volume and gasification rate is obtained.An experimental platform for evaporation performance of expanded vessels was designed and built,and an experimental study was carried out on brine expansion evaporation concentration system.Under the experimental conditions,the evaporation performance of the expanded vessel enhances with the increase of the inlet water temperature;decreases with the increase of the equilibrium pressure of the container(the steam quality increases);enhances with the increase of the overheat;decreases with the increase of the flow rate;enhances first and then decreases with the increase of the liquid level of the container.The inlet water temperature and equilibrium pressure are the main factors that affect the evaporation performance of the expansion container,while the inlet water volume and liquid height have little influence on the evaporating performance of the expansion container.Therefore,when the liquid is dilatant and evaporated,the inlet water temperature should be increased as much as possible,and choose the balance pressure,inlet water flow rate and liquid level height reasonably according to the actual situation(taking into account both evaporation rate and two steam quality).Taking a 2×600MW unit as an example,the design calculation and economic benefit analysis of the system are carried out.System design output 20t/h.System designs output 20t/h.The design parameters of expanding container are calculated as follows:the inner diameter is 2.2m,the height is 3.2m,and the volume is 12.2m3.Under the full load operation of the unit,the flue gas distribution from the flue gas system is about 2.11%,and the thermal efficiency of the boiler is about 0.39%,which will not affect the normal operation of the boiler.The system can produce about 2 million yuan of economic benefits each year.Comprehensive theoretical analysis,experimental research and computational analysis,the new desulfurization wastewater zero emission treatment technology can not only solve the pollution problem of the desulfurization wastewater from the thermal power plant to the ecological environment,but also can recover a large number of high-quality fresh water resources,which has great potential for application.