Flue gas desulfurization and desulfurization wastewater treatment method and flue gas desulfurization and desulfurization wastewater treatment apparatus

Abstract

The invention relates to a flue gas desulfurization and desulfurization wastewater treatment method. According to the flue gas desulfurization and desulfurization wastewater treatment method, a flue gas pre-treatment tower comprises a flue gas / desalted water heat exchanger and a spraying unit; liquid-state desalted water is converted into gas-state desalted water by using flue gas in the flue gas / desalted water heat exchanger, and the gas-state desalted water enters a gas-liquid separator and is separated; the gas phase is compressed, the compressed gas phase enters the gas discharge cylinderon the top of a desulfurization tower to heat and purify the flue gas; the spraying unit is used for spraying a NaOH solution to reduce the flue gas temperature to below the dew point temperature of an acid, the cooled flue gas enters a bag type dust removing device and is treated, and the treated flue gas enters the desulfurization tower; and on the bottom of the desulfurization tower, a proper amount of desulfurization wastewater is subjected to spraying drying by using the flue gas, and the flue gas enters a desulfurization zone and is subjected to desulfurization purification. The invention further relates to a treatment apparatus of the treatment method. With the method and the apparatus of the present invention, the purified flue gas meets the discharge requirement, and the zero discharge of the flue gas desulfurization wastewater is achieved, the white smoke and the blue smoke are simultaneously eliminated, and the flue gas desulfurization and desulfurization wastewater comprehensive treatment cost is reduced.

Description

technical field [0001] The invention belongs to the technical field of environmental protection, and in particular relates to a method and a device for treating flue gas desulfurization by sodium method and the generated desulfurization wastewater. 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 whether the product is useful or no...

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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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