Simultaneous desulfurization and denitrification device for boiler exhaust gas

Abstract

The invention discloses a simultaneous desulfurization and denitrification device for a boiler exhaust gas. The device comprises one or more serial desulfurization and denitrification towers and an external hydrogen peroxide storage tank, wherein a spraying pipe, an ultraviolet lamp and a desulfurization and denitrification module composed of regular nanometer photocatalyst plates and sieve plates are successively arranged in the tower from top to bottom; the spraying pipe is connected with the hydrogen peroxide storage tank through a hydrogen peroxide circulating pump; an exhaust gas inlet is formed in a side wall at the bottom of the tower; a liquid sealing tank is vertically arranged at the bottom of the tower; the boiler exhaust gas enters the tower through the exhaust gas inlet; under the effects of the desulfurization and denitrification module and the hydrogen peroxide, SO3 and NO2 are respectively oxidized and absorbed as sulfuric acid and nitric acid and then are removed; the liquid after the photocatalysis hydrogen peroxide oxidizing reaction passes by the sieve plates and then enters the liquid sealing tank and finally converges in the storage tank; the treated clean exhaust gas is discharged from an exhaust gas outlet at the top end of the tower. The simultaneous desulfurization and denitrification device for the boiler exhaust gas can oxidize all the SO2 and NO in a coal-fired boiler into SO3 and NO2 and the desulfurization rate and the denitration rate are respectively above 99% and 90%.

Description

technical field [0001] The invention relates to a simultaneous desulfurization and denitrification device for boiler flue gas, in particular to a device for desulfurization and denitrification of boiler flue gas by using oxidation reaction, which belongs to the field of industrial waste gas treatment. Background technique [0002] The flue gas of coal-fired boilers contains a large amount of air pollutants, mainly SO 2 , NO x . Among them, SO 2 and NO x It not only damages human body, plants, especially crops and economic crops, but also can form acid rain, optical smog and haze, etc., and can destroy the ozone layer. It is estimated that by 2020 and 2030, my country's NOx emissions will reach 29 million and 40 million tons respectively. In 2011, my country revised the "Emission Standards of Air Pollutants for Thermal Power Plants" (GB 13223-2011); in 2012, the State Council and relevant departments issued the "Twelfth Five-Year Plan for Energy Conservation and Plan”, “...

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Problems solved by technology

[0006] 3) The high water consumption of this technology also poses great difficulties to the promotion and application of the technology in the vast water-scarce areas of central and western my country, and these areas are the areas with the most coal-fired power plants in my country;

[0007] 4) For each ton of SO removed by this method 2 About 2.7 tons of gypsum will be discharged. Due to the loose texture of the by-product gypsum, its performance cannot be compared with that of mineral gypsum. As a result, desulfurized gypsum is discarded for disposal, occupying a large amount of land, and long-term stacking of desulfurized gypsum will release toxic substances, causing secondary pollution. , the post-processing cost is huge;

[0008] 5) China is a country with a large demand for sulfur, sulfuric acid and ammonium sulfate, but the precious sulfur resources in flue gas have not been resourced and commercialized;

[0009] 6) Denitrification cannot be carried out, and denitrification equipment needs to be redesigned and installed, resulting in large footprint, complicated process, and high operating costs

The disadvantages are: when the flue gas temperature is high and the dust content in the flue gas is high, ammonia is easy to volatilize, operation control is difficult, and the consumption of ammonia water absorbent is large. 2 Without "enrichment and concentration", the obtained ammonium sulfate solution is very dilute, and the process requires "oxygen oxidation", and absorption and crystallization require a lot of energy

However, the traditional SCR still has the following disadvantages: (1) The catalyst is prone to poisoning due to dust wear and alkali / alkaline earth metal corrosion for a long time; (2) The high reaction temperature of the catalyst needs to be preheated between the economizer and the air preheater. Leave a large space for the layout of the catalytic device; (3) The traditional SCR catalytic method has inevitable heat loss, resulting in energy waste; (4) Due to the consumption of NH by SCR technology 3 , the storage, leakage, transportation and other problems of liquid ammonia cause high operating costs and large investment in equipment.

However, when activated semi-coke is used in the process of flue gas oxidation and denitrification, due to NO and H 2 The competitive adsorption of O can easily cause the phenomenon of "water poisoning" of the catalyst, which will significantly reduce the denitrification activity.

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