A treatment method and device for flue gas and flue gas desulfurization wastewater

Abstract

The invention relates to a treatment method for flue gas and flue gas desulfurization wastewater. In the flue gas / desulfurization wastewater heat exchanger, the flue gas is used to exchange heat for the desulfurization wastewater, and a nozzle is set at the outlet of the flue gas to spray NaOH solution to make the flue gas At this time, the flue gas enters the bag filter to remove dust and sulfate / sulfuric acid droplets, and then enters the desulfurization tower; desulfurization purification and heating are carried out in the desulfurization tower, and the waste water at the bottom of the tower is used as The absorption liquid is circulated, and the others enter the plate heat exchanger in the form of desulfurization wastewater; the plate heat exchanger uses the steam condensed water generated by the heating coil in the exhaust cylinder to preheat the desulfurization wastewater, and after preheating, the wastewater enters the flue gas / desulfurization wastewater exchange heater. On the basis of making full use of the waste heat of the flue gas, the present invention realizes the dual purpose of purifying the flue gas to meet the emission requirements and zero discharge of flue gas desulfurization waste liquid, and simultaneously eliminates "white smoke" and "blue smoke", and reduces the cost of flue gas desulfurization. and the comprehensive treatment cost of desulfurization waste liquid.

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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