Flue gas and flue gas desulfurization wastewater treatment method and device

Abstract

The invention relates to a flue gas and flue gas desulfurization wastewater treatment method and device. The flue gas is used to exchange heat and raise the temperature of desulfurization wastewater in a flue gas / desulfurization wastewater heat exchanger, a spray nozzle is arranged in a flue gas outlet to spray an NaOH solution, the temperature of the flue gas is reduced to the temperature of theacid dew point, then the flue gas enters a bag filter to remove dust and a sulfate / sulfuric acid liquid drop and then falls into a desulfurizing tower; the flue gas is desulfurized, purified and heated and the temperature is raised in the desulfurizing tower, the wastewater part at the bottom part of the desulfurizing tower serves as a circulating absorption liquid, other wastewater enters a plateheat exchanger in the form of desulfurization wastewater; and the plate heat exchanger uses steam condensation water produced in a heating coil in an exhaust funnel to preheat the desulfurization wastewater, and the preheated wastewater enters the flue gas / desulfurization wastewater heat exchanger. The double purposes of purifying the flue gas and meeting the emission requirement and achieving zero emission of the flue gas desulfurization waste liquid are achieved on the basis that the waste heat of the flue gas is fully used, meanwhile, the white smoke and the blue smoke are eliminated, andthe comprehensive treatment costs for the flue gas desulfurization and the desulfurization waste liquid are reduced.

Description

technical field [0001] The invention belongs to the field of environmental protection waste water and waste gas treatment, and in particular relates to a sodium method flue gas desulfurization and a treatment method and device for the generated flue gas desulfurization waste water. Background technique [0002] Since 2003, my country's SO 2 The total emissions have remained high. In 2014, my country's SO 2 The total emissions were 19.744 million tons, which was below 20 million tons for the first time since 2003. Common flue gas desulfurization methods mainly include dry method and wet method. Compared with dry desulfurization, wet desulfurization equipment is small, easy to operate, and has high desulfurization efficiency. 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 discarding method and recycling method according to w...

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Problems solved by technology

Literature "SO in coal-fired flue gas 3 Causes, Impacts and Emission Reduction Countermeasures” mentions the use of wet electrostatic precipitators to remove SO 3 , the removal rate can reach 95%, but the construction and operation costs are relatively high

[0006] CN102335553A passes the sodium-based flue gas desulfurization wastewater into the bipolar membrane electrodialysis device, relies on the selective permeation of the membrane and the electrolysis device, regenerates the desulfurization absorbent, and produces sulfuric acid by-product, realizing "zero discharge" of desulfurization wastewater, but The technology consumes more power

CN103936220A first separates the desulfurization wastewater from solid and liquid, and then uses steam mechanical recompression technology (MVR) to recover sodium sulfite or ammonium salt. This technology better solves the problem of zero discharge of desulfurization wastewater, but the flue gas temperature has not been reduced, and the water consumption is still Larger and not involved in "white smoke" issues

CN104801162A uses ammonia water as reducing agent and absorbent to carry out denitrification and desulfurization treatment on flue gas respectively, purifies flue gas and removes mist droplets with wet electric demister, 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 "white smoke" problem, and the power consumption of the electric demister is very large

However, this technology requires major changes to the boiler economizer to arrange the desulfurization wastewater heating system, which requires a high investment; and the moisture evaporated by the high-temperature flue gas enters the desulfurization tower together with the flue gas for recycling, which increases the desulfurization. Waste liquid treatment scale

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