Method and device for coupling treatment of desulfurization wastewater zero discharge and flue gas white elimination for coal-fired power plant

Abstract

The invention discloses a method and a device for coupling treatment of desulfurization wastewater zero discharge and flue gas white elimination for a coal-fired power plant. The method comprises thefollowing steps that (1) feeding desulfurization wastewater into a water outlet tank to adjust the total water inlet amount of the desulfurization wastewater, and pumping the wastewater into a concentration tank through a water inlet pump, wherein a water collecting pipe is inserted deeply into the concentration tank by at least 1.2 m to prevent flue gas from being poured into the concentration tank; (2) pumping the wastewater in the concentration tank into a spraying device positioned in a vertical flue: (3) enabling sprayed liquid drops to be in direct contact with the low-temperature flue gas behind the electric precipitator for heat exchange, enabling evaporated wastewater steam to enter a desulfurizing tower along with the flue gas, and enabling unevaporated wastewater to enter the concentration tank again; and 4) filtering and separating the solid-liquid mixed salt solution at the bottom of the concentration tank through a membrane separation system, feeding the filtrate back tothe concentration tank again, and transporting the crystallized mixed salt outside for landfilling. The device comprises an air pre-heater, an electric dust remover, a concentration spraying part, anabsorption tower, a chimney, a dehydration system, a water outlet tank, a microfiltration separation system and a computer control system.

Description

technical field [0001] The invention belongs to the technical field of waste water treatment, and in particular relates to a method and device for coupling treatment of desulfurization waste water in a coal-fired power plant with zero discharge and flue gas whitening. Background technique [0002] At present, my country's electricity demand mainly depends on coal-fired power generation. The combustion of coal produces various air pollutants and the composition of the flue gas is relatively complex. In the process of removing sulfur dioxide in the flue gas, the flue gas desulfurization technology with the highest application rate at this stage is the limestone-gypsum method. The treatment of the desulfurization wastewater generated in the power plant has always been a hot spot in the power environmental protection industry. The main process route of desulfurization at this stage is: desulfurization wastewater - pretreatment - concentration reduction (thermal method or membra...

AI Technical Summary

Problems solved by technology

Among them, the membrane distillation method has a high cost of membrane production, and membrane contamination during operation will lead to a decrease in membrane flux. At the same time, its operating state is unstable. So far, no large-scale industrial production application has been seen, and technical experience is lacking.

The Chinese patent with the patent number CN201710942060 discloses a zero-discharge system and method for desulfurization wastewater in coal-fired power plants. This system atomizes the wastewater after wet desulfurization through the rotary atomizer of the spray drying tower after simple pretreatment in a triple box , extract the high-temperature flue gas before the air preheater and heat the low-temperature flue gas after the air preheater at the same time. After mixing the two gases, use the high-temperature gas as a heat source to evaporate the waste water and realize zero discharge of waste water. This method makes full use of the power plant The flue gas waste heat energy reduces the cost, but because the atomization nozzle is used in the atomization process, the problem of nozzle clogging and fouling will occur after long-term operation

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