Treating method and treating apparatus for waste liquid produced in flue gas desulfurization

Abstract

The invention relates to a treating apparatus for waste liquid produced in sodium-process flue gas desulfurization. The treating apparatus mainly comprises a flue gas / desulfurization waste liquid heatexchanger, a dust-removal and desulfurization tower, a solid-liquid separator, a plate heat exchanger and a steam compressor, wherein the flue gas / desulfurization waste liquid heat exchanger is divided into an upper heat exchange zone and a lower crystallization zone; the upper heat exchange zone comprises a steam chamber, an upper tube plate, a partition plate, a heat exchange tube and a lower tube plate from top to bottom; a desulfurization waste liquid feeding box is arranged between the upper tube plate and the partition plate; a liquid film former is arranged at the heat exchanger tube end of the desulfurization waste liquid feeding box; the lower crystallization zone is provided with an inclined drainage plate, a sealing plate and a crystallization tank; and the sealing plate is inserted into a position located below the liquid level of the crystallization tank. Through adoption of the specific treating apparatus and a specific treating method, the dual purposes of allowing purified flue gas to meet emission requirements and realizing zero discharge of waste liquid produced in flue gas desulfurization are achieved on the basis of full use of the waste heat of flue gas; and in particular, the supplementation amount of fresh water for a flue gas desulfurization system is reduced, and overall treatment cost of flue gas desulfurization and desulfurization waste liquid is lowered.

Description

technical field [0001] The invention belongs to the field of environmental protection wastewater treatment, and particularly relates to a treatment method and a treatment device for a sodium-method flue gas desulfurization waste liquid. Background technique [0002] Since 2003, my country's SO 2 Total emissions have remained high. In 2014, my country's SO 2 The total amount of emissions was 19.744 million tons, the first time since 2003 that it was below 20 million tons. Commonly used flue gas desulfurization methods mainly include dry method and wet method. Compared with dry desulfurization, wet desulfurization equipment is small, operation is simple, and desulfurization efficiency is high, and it is widely used, such as sodium method, magnesium method, ammonia method. and calcium method, among which sodium method and calcium method are the most. Wet desulfurization can also be divided into disposal method and recovery method according to whether the product is useful. T...

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Problems solved by technology

[0005] CN102335553A The sodium-based flue gas desulfurization waste liquid is passed into the bipolar membrane electrodialysis device, and the desulfurization absorbent is regenerated by relying on the selective permeation of the membrane and the electrolysis device, and sulfuric acid is produced as a by-product, realizing "zero discharge" of the desulfurization waste liquid , but the technology consumes more power

CN104801162A uses ammonia water as reducing agent and absorbent to carry out denitrification and desulfurization treatment on flue gas respectively, and removes mist droplets with wet electric demister to purify flue gas, which can eliminate "smoke plume" and "blue smoke" phenomenon, but due to the purification of flue gas Before the gas is emptied, it is still a saturated gas, and the temperature is high, which still cannot effectively solve the problem of "white smoke"

However, this technology requires major changes to the boiler economizer, and the investment is high; and the water evaporated by the high-temperature flue gas is used together with the flue gas to enter the desulfurization tower for recycling, which increases the treatment scale of the desulfurization waste liquid; and A special dust collector is required to remove the moisture in the flue gas

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