A zero-discharge system for desulfurization wastewater with cascaded utilization of flue gas waste heat and its working method

Abstract

The invention discloses a desulfurization wastewater zero discharge system for cascade utilization of flue gas waste heat and a working method thereof, belonging to the technical field of desulfurization wastewater treatment. Including the first air intake device, the second air intake device, the first air heat exchanger, the second air heat exchanger, the first flue gas heat exchanger, the second flue gas heat exchanger, spray drying tower, dust collector, Evaporation and concentration tower and desulfurization wastewater pool. Use the high-temperature flue gas at the tail of the boiler to increase the air temperature. Through the cascade utilization of the temperature, the high-temperature air evaporates and dries the desulfurization wastewater. The air after cooling is used for the concentration and reduction of the desulfurization wastewater. The dust collector is used to recover the dried salt in the wastewater. , The air heat exchanger is used to recover the heat in the outlet air of the system for air preheating. Compared with the traditional zero-discharge method of desulfurization wastewater, the waste heat in the flue gas is fully utilized, the concentration and drying of the wastewater are realized simultaneously, and the water balance and material balance of the gas in the original flue are less affected, so it has a good application prospect.

Description

technical field [0001] The invention belongs to the technical field of desulfurization wastewater treatment, and in particular relates to a desulfurization wastewater zero discharge system for cascaded utilization of flue gas waste heat and a working method thereof. Background technique [0002] Domestic coal-fired power plants usually use the limestone-gypsum method to desulfurize the flue gas, resulting in a large amount of wastewater. Desulfurization wastewater has the characteristics of low pH, high salt content, and high heavy metal content. It is still highly polluting after being treated by traditional pH adjustment, coagulation, and precipitation processes. With the increasing environmental protection requirements, zero discharge of desulfurization wastewater has gradually become the technical trend of power plant water treatment. [0003] Membrane concentration + evaporation crystallization is the technical route usually adopted for zero discharge of industrial was...

AI Technical Summary

Problems solved by technology

However, the actual operation effect of membrane concentration + evaporative crystallization is not ideal, mainly in the following aspects: the membrane system has high requirements on water quality, usually requires softening and other pretreatment links, and the process flow is long; during long-term operation, membrane pollution is serious, and equipment maintenance Frequent; the operating pressure of the reverse osmosis membrane is relatively high, and the operating cost is high; the mixed salt produced by evaporation and crystallization cannot be used, and is usually disposed of as hazardous solid waste

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