A high-efficiency flue gas denitrification agent and denitrification treatment process thereof

Abstract

The present invention discloses a high-efficiency flue gas denitrifier and a denitrification treatment process thereof. The denitrifier comprises 85-90 parts by mass of an organic amine reducing agent, 5-8 parts by mass of a polyol polymer, 4-5 parts by mass of a simple organic matter of ketone / benzene, and 1-2 parts by mass of a sodium / potassium metal salt. The treatment process using the above denitrifier comprises atomizing a 25-40°C solution containing 20-40wt% of the denitrifier, and then quantitatively spraying it countercurrently into a 750-1100°C boiler high temperature zone, and then dispersing it into the boiler flue gas, reacting with nitrogen oxides in the boiler flue gas, and reducing the content of nitrogen oxides. The denitrifier provided by the present invention has the advantages of a wide reaction temperature window, high denitrification efficiency, a wide range of adaptability, and economic rationality, and has good application prospects.

Description

Technical Field

[0001] The invention belongs to the field of denitration, and in particular relates to a high-efficiency flue gas denitration agent and a denitration treatment process thereof. Background Art

[0002] Nitrogen oxides are one of the toxic substances in the exhaust gas of the chemical industry, defense industry, power industry, boilers and internal combustion engines. The most toxic NOx to the human body is NO2, which mainly affects the respiratory system and can cause diseases such as bronchitis and emphysema; NO2 is very easy to combine with the pigment (Hb) in animal blood, causing blood hypoxia and central nervous system paralysis. NOx is also very harmful to the environment. It is not only the main pollutant in the formation of acid rain and acid fog, but also can form photochemical smog with hydrocarbons, and can also participate in the destruction of the ozone layer. Nitrous oxide (N2O) will destroy the ozone layer in the high-altitude stratosphere, causing more ultraviolet radiation to the ground, and is one of the culprits of the greenhouse effect.

[0003] Flue gas denitrification technology refers to emission reduction technology that reduces NOx in flue gas to N2 through a reducing agent, such as selective catalytic reduction technology (SCR), selective non-catalytic reduction technology (SNCR), plasma flue gas denitrification technology, etc. Flue gas denitrification technology has high denitrification efficiency. For example, SCR can achieve a NOx removal rate of 90%, and SNCR also has a denitrification efficiency of >75% in the experimental stage. At present, these two technologies are relatively mature and have been widely used in power plant boilers.

[0004] However, in actual operation, SCR technology requires the addition of a large number of equipment, such as SCR reaction devices, ammonia storage and ammonia injection systems, etc., and the catalyst needs to be constantly replaced during operation. The high investment and operating costs make this technology only suitable for power plant boilers with large investment amounts. In addition, the application of SCR will lead to the formation of ammonium bisulfate aerosol in the flue gas after the SCR device. The aerosol condenses and deposits near the downstream low-temperature heating surface, often causing large-scale dust accumulation and blockage of the air preheater.

[0005] SNCR technology is simple and requires little investment, but the reaction temperature window is narrow. Fluctuations in flue gas temperature at the ammonia injection position will lead to a decrease in denitrification efficiency. In actual operation, the denitrification efficiency of SNCR is only about 50%. When the SNCR of a power plant is in operation, low temperatures will reduce the denitrification efficiency, increase the leakage of NH3, and cause corrosion to devices such as the air preheater at the tail of the boiler. When the temperature is high, the denitrification efficiency will also decrease due to the oxidation of NH3, and the NO concentration will even exceed the NO concentration in the original furnace. At the same time, in addition to power plants, some garbage, biomass, gasification fine slag, and volatile organic compounds (VOCs) processing plants also often use SNCR technology for denitrification. However, the flue gas temperature of these plants is generally not high, and the denitrification efficiency of SNCR technology is low. Therefore, it is extremely important to broaden the temperature reaction range of SNCR.

[0006] In summary, there is an urgent need to find an efficient flue gas denitrifier with a wide denitrification temperature window. Summary of the invention

[0007] The purpose of the present invention is to provide a high-efficiency flue gas denitrification agent and a denitrification treatment process thereof, so as to solve the problems existing in the existing denitrification technology, broaden the denitrification temperature window of the SNCR technology, greatly improve the denitrification efficiency of the SNCR, achieve continuous and efficient NOx removal effect, and meet the denitrification requirements of different types of industrial boilers.

[0008] Specifically, to achieve the above objectives, the first aspect of the present invention provides a high-efficiency flue gas denitrification agent, wherein the denitrification agent raw materials include: 85-90 parts by mass of an organic amine reducing agent, 5-8 parts by mass of a high molecular polymer, 4-5 parts by mass of a simple organic matter, and 1-2 parts by mass of a metal salt.

[0009] Furthermore, the organic amine reducing agent is a mixture of one or more of urea, methylamine, dimethylamine, n-butylamine, cyclopentylamine, phenylenediamine, and p-aminophenol.

[0010] Furthermore, the high molecular polymer is a polyol polymer; specifically, a mixture of one or more of polyvinyl alcohol, polyethylene glycol, polyethylene glycol dimethyl ether, and polypropylene glycol.

[0011] Furthermore, the simple organic matter is a ketone or benzene organic matter; specifically, a mixture of one or more of acetone, butanone, pentanone, toluene, o-xylene, and p-xylene.

[0012] Furthermore, the metal salt is an organic compound containing potassium ions or sodium ions; specifically, a mixture of one or more of KMnO4, K2CO3, CH3COONa, and Na2CO3.

[0013] Furthermore, the denitrification agent is used at a temperature greater than 725°C.

[0014] The second aspect of the present invention provides a denitration treatment process based on any of the above-mentioned high-efficiency flue gas denitration agents, the process comprising the following steps:

[0015] A solution of any of the above-mentioned high-efficiency flue gas denitrification agents at 25-40°C is atomized and quantitatively sprayed in countercurrent to the high-temperature zone of the boiler, and then dispersed into the boiler flue gas to react with nitrogen oxides in the boiler flue gas to reduce the content of nitrogen oxides.

[0016] Furthermore, the solution of the high-efficiency flue gas denitrification agent is an aqueous solution, and the mass fraction of the high-efficiency flue gas denitrification agent in the aqueous solution is 20-60wt%.

[0017] Furthermore, the high temperature zone of the boiler is a high temperature zone of 750-1100°C.

[0018] Furthermore, the quantitative standard of the quantitative countercurrent injection of the denitrification solution is: controlling the molar ratio of the N element in the organic amine contained in the solution to the NOx in the flue gas to be 1.2-1.5; adopting this preferred molar ratio can ensure that sufficient reducing agent is provided while not generating a large amount of organic matter and CO emissions in the exhaust gas.

[0019] Beneficial effects:

[0020] (1) The high-efficiency flue gas denitrification agent of the present invention uses an organic amine reducing agent as a basic raw material, and the large amount of amino groups contained in it provide NH2 and active sites for reducing NOx. Polyol polymers, simple organic substances and OH and CH i The activation of Na / K metal salt ions is beneficial to the catalytic oxidation-reduction reaction of nitrogen oxides. The synergistic effect of each component can greatly improve the denitrification efficiency of SNCR at low temperatures, while maintaining high denitrification efficiency at high temperatures and widening the temperature range of the reaction.

[0021] (2) The high-efficiency flue gas denitrifier improved by the present invention can not only be used in power station boilers, but also be suitable for treating various types of solid waste, volatile organic matter and NOx in biomass boiler flue gas. By adjusting the mass fraction of the denitrifier in the denitrifier solution, the boiler flue gas under different loads and different temperatures can be treated.

[0022] (3) Using the high-efficiency flue gas denitrification agent and treatment process provided by the present invention, under the appropriate ratio of denitrification dosage to flue gas volume, the denitrification products are water, N2 and other non-polluting gases, and are low in price, simple to manufacture and easy to store. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The denitration efficiency of the denitrification agent solution of the present invention at different temperatures is compared with the SNCR denitration efficiency using pure NH3 as raw material. DETAILED DESCRIPTION

[0024] The exemplary embodiments of the present invention are now described in detail, which should not be considered as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, characteristics and implementation schemes of the present invention. It should be noted that the present invention is not limited to the following specific embodiments, and any equivalent changes made to the technical solutions of this application belong to the protection scope of the present invention.

[0025] In the present invention, unless otherwise specified, the "parts" are all based on mass parts.

[0026] The calculation of the denitrification rate involved in the present invention is: Denitrification rate = (NOx content in boiler flue gas before denitrification agent treatment - Nx content in boiler flue gas before denitrification agent treatment) ÷ NOx content in boiler flue gas before denitrification agent treatment. Specific embodiment 1:

[0028] A high-efficiency flue gas denitrifier, comprising the following components:

[0029] 85 parts of urea, 8 parts of polyethylene glycol, 5 parts of acetone, 2 parts of sodium acetate. Specific embodiment 2:

[0031] A high-efficiency flue gas denitrifier, comprising the following components:

[0032] 88 parts of dimethylamine, 6 parts of polyethylene glycol, 5 parts of toluene, and 1 part of sodium carbonate. Specific embodiment 3:

[0034] A high-efficiency flue gas denitrifier, comprising the following components:

[0035] 90 parts of cyclopentylamine, 5 parts of polyvinyl alcohol, 4 parts of butanone, and 1 part of potassium carbonate.

[0036] Comparative Example:

[0037] Use pure urea as denitrification agent.

[0038] The above denitrification agent was used for flue gas denitrification of a biomass power plant boiler. Without treatment, the concentration of nitrogen oxides in the flue gas emission was 500-600 mg / Nm 3 , the average value is 550mg / Nm 3 .

[0039] The specific denitrification process is as follows: the measured denitrification solution (or urea solution in the comparative example) is transported to the furnace spray gun by the high-speed gas provided by the fan, and the denitrification agent is sprayed into the boiler flue gas duct by the spray gun. The spray gun position is selected at different temperature positions of the flue gas temperature of 650 to 1100°C. At different temperatures, the denitrification solution reacts with the NOx in the boiler flue gas.

[0040] When the denitrification agent solution is quantitatively transported, the ratio of the amount of the substance containing the NH2 group in each embodiment to the amount of the substance containing the total NOx in the flue gas is controlled to be 1.5.

[0041] The denitration efficiency of each embodiment and comparative example at different temperatures is as follows Figure 1 As shown in the figure. Figure 1 It can be seen that the maximum denitration rate is about 95% when the above denitration reaction is carried out using specific examples 1 / 2 / 3, and a relatively high denitration effect can be achieved at 750-1100° C. The denitration reaction temperature window is wider than that of the comparative example.

Claims

1. A high-efficiency flue gas denitrification agent, characterized in that: The denitrification agent raw materials include: 85 parts by mass of an organic amine reducing agent, 8 parts by mass of a high molecular polymer, 5 parts by mass of a simple organic matter, and 2 parts by mass of a metal salt; The high molecular polymer is a mixture of one or more of polyvinyl alcohol, polyethylene glycol, polyethylene glycol dimethyl ether and polypropylene glycol; The simple organic matter is a mixture of one or more of acetone, butanone, pentanone, toluene, o-xylene and p-xylene; The denitrification agent can significantly improve the denitrification efficiency of SNCR at relatively low temperatures, while maintaining high denitrification efficiency at high temperatures, thereby widening the temperature range of the reaction.

2. The high-efficiency flue gas denitrification agent according to claim 1, characterized in that: The organic amine reducing agent is a mixture of one or more of urea, methylamine, dimethylamine, n-butylamine, cyclopentylamine, phenylenediamine and p-aminophenol.

3. The high-efficiency flue gas denitrification agent according to claim 1, characterized in that: The metal salt is an organic compound containing potassium ions or sodium ions, and is a mixture of one or more of KMnO4, K2CO3, CH3COONa, and Na2CO3.

4. The high-efficiency flue gas denitrification agent according to claim 1, characterized in that: The denitrification agent has an operating temperature greater than 725°C.

5. A denitration treatment process based on the high-efficiency flue gas denitrification agent according to any one of claims 1 to 3, characterized in that: The process comprises the following steps: A 25-40° C. solution of the high-efficiency flue gas denitrification agent according to any one of claims 1 to 3 is atomized and quantitatively sprayed in countercurrent into the high-temperature zone of the boiler, and then dispersed into the boiler flue gas to react with nitrogen oxides in the boiler flue gas to reduce the content of nitrogen oxides.

6. The denitration treatment process of the high-efficiency flue gas denitrification agent according to claim 5 is characterized in that: The solution of the high-efficiency flue gas denitrification agent is an aqueous solution, and the mass fraction of the high-efficiency flue gas denitrification agent in the aqueous solution is 20-60wt%.

7. The denitration treatment process of the high-efficiency flue gas denitrification agent according to claim 5 is characterized in that: The high temperature zone of the boiler is a high temperature zone of 750-1100°C.

8. The denitration treatment process of the high-efficiency flue gas denitrification agent according to claim 5 is further characterized by: The quantitative standard of the quantitative countercurrent injection of the denitrification solution is: controlling the molar ratio of the N element in the organic amine contained in the solution to the NOx in the flue gas to be 1.2-1.5.

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