Denitration agent as well as preparation method and use method thereof

Abstract

The invention aims to provide a denitration agent as well as a preparation method and a use method thereof in order to solve the problems that the denitration material rate is low and the denitration efficiency is greatly influenced by the reaction temperature in the existing SNCR denitration technology. The denitration agent comprises the following raw materials in percentage by mass: 60%-70% of an organic reducing agent, 20%-30% of an inorganic amino compound, 2%-5% of metal salt, 2%-5% of an additive and 1%-3% of a surfactant. According to the denitration agent, the denitration temperature window of the SNCR technology is widened, the denitration efficiency of SNCR is greatly improved, NOx emission is efficiently removed, and the denitration requirements of different types of industrial boilers are met.

Description

Technical Field

[0001] This invention belongs to the field of flue gas denitrification technology, and specifically relates to a denitrification agent and its preparation and application methods. Background Technology

[0002] With the rapid development of modern industry, NO x NO is a major air pollutant. NO released during boiler combustion... x This accounts for over 40% of emissions. According to the national standard GB13271-2014, NOx emissions from coal-fired boilers... x ≤400mg / m 3 Under the premise of vigorously promoting low-carbon economic development in my country, effective measures must be taken to reduce boiler NOx emissions. x Emissions.

[0003] Existing denitrification technologies are mainly divided into dry flue gas denitrification and wet flue gas denitrification. Compared with dry flue gas denitrification, wet flue gas denitrification has lower denitrification efficiency because NO is difficult to be directly absorbed by the solution, and it easily generates difficult-to-treat waste liquid and wastewater, increasing the treatment process and difficulty. Therefore, dry flue gas denitrification technology is mostly used in actual production. Because in dry denitrification technology, NO... x The gases are reduced to non-toxic N2 and H2O, and the byproducts (CO2, etc.) are easy to treat. Dry flue gas denitrification technologies mainly include selective catalytic reduction (SCR) and selective non-catalytic reduction (SNCR).

[0004] SCR (Sequencing Catalytic Reduction) utilizes a catalyst (such as non-precious metals like copper, iron, chromium, and manganese) at relatively low temperatures (typically 200-400℃) to catalytically reduce NOx in flue gas with a reducing agent, producing N2 and H2O. This method boasts high denitrification efficiency, typically exceeding 80%, and in some cases even surpassing 90%. However, the system is relatively complex, requiring specialized SCR reactors, catalyst beds, ammonia injection systems, and other equipment. Furthermore, the catalyst is costly, resulting in substantial initial investment costs.

[0005] SNCR (Synchronous Non-Catalytic Reduction) requires no catalyst. Under high-temperature conditions (850-1100℃), a reducing agent containing amino groups (such as ammonia water or urea solution) is injected into the furnace. The reducing agent rapidly pyrolyzes into active groups such as NH3, which react with NOx in the flue gas to produce N2 and H2O. This method does not require a continuous supply of expensive catalysts and consumes relatively little reducing agent, resulting in relatively low operating costs. However, it suffers from relatively low denitrification efficiency, generally between 30% and 50%, and is significantly affected by factors such as flue gas temperature, reducing agent injection volume, and mixing uniformity. Addressing the technical challenges of low denitrification efficiency in SNCR (which does not use a catalyst) and high efficiency in SCR (Synchronous Non-Catalytic Reduction) (which uses a catalyst but suffers from high catalyst cost, short lifespan, and difficult processing), developing a novel denitrification agent to improve SNCR denitrification efficiency is a pressing issue. Summary of the Invention

[0006] The purpose of this invention is to address the problems of low denitrification feed ratio and significant influence of reaction temperature on denitrification efficiency in existing SNCR denitrification technologies, and to provide a denitrification agent and its preparation and application methods. The denitrification agent of this invention broadens the denitrification temperature window of SNCR technology, significantly improves the denitrification efficiency of SNCR, and achieves highly efficient removal of NO. x The emissions meet the denitrification requirements of different types of industrial boilers.

[0007] To achieve the above objectives, one of the technical solutions provided by the present invention is as follows:

[0008] A denitrification agent comprising the following raw materials by mass percentage: 60%-70% organic reducing agent, 20%-30% inorganic amino compound, 2%-5% metal salt, 2%-5% additive, and 1%-3% surfactant.

[0009] Furthermore, the organic reducing agent is one or more of melamine, n-butylamine, sulfonamide, and cyanuric acid.

[0010] Furthermore, the inorganic amino compound is one or more of ammonium dihydrogen phosphate, ammonium chloride, and ammonium bicarbonate.

[0011] Furthermore, the metal salt is a mixture of potassium permanganate and ferrocene, with a mass ratio of 1:1.5-2.5.

[0012] Furthermore, the additive is composed of 0.5%-2% silica as a dispersant, 0.5%-1.5% calcium carbonate as an auxiliary agent, and 1%-2% diatomaceous earth as a carrier.

[0013] Furthermore, the surfactant is sodium dodecyl sulfate.

[0014] The second technical solution of the present invention is a method for preparing the above-mentioned denitrification agent, comprising the following steps:

[0015] Step 1: Weigh each raw material according to the mass percentage, and then mix the organic reducing agent, inorganic amino compound and metal salt to obtain the first mixture;

[0016] Step 2: Add additives and surfactants to the first mixture and mix well to obtain the denitrification agent.

[0017] Furthermore, in the above-mentioned method for preparing the denitrification agent, the particle size of each raw material is 150-200 mesh.

[0018] The third technical solution of the present invention is a method of using the above-mentioned denitrification agent, wherein the denitrification agent is pneumatically injected into the boiler flue gas duct at a rate of 200-230 kg / h, in a temperature range of 700℃-1100℃, and the denitrification agent reacts with NO in the flue gas. x The reaction proceeds to remove nitrogen oxides from the flue gas.

[0019] Furthermore, the specific method of using the aforementioned denitrification agent, which involves pneumatically injecting the denitrification agent into the boiler flue gas duct, is as follows: A high-speed gas supplied by a blower transports the denitrification agent to the furnace spray gun, which then sprays the agent into the boiler flue gas duct. The spray gun outlet is located within the flue gas duct at a temperature of 700~1100℃. The denitrification agent reacts with NO in the boiler flue gas. x The reaction will proceed.

[0020] Compared with the prior art, the advantages of the present invention are:

[0021] 1. The denitrification agent of the present invention is composed of an organic reducing agent, an inorganic amino compound, a metal salt, additives, and a surfactant. By introducing the inorganic amino compound, it readily generates active groups with the organic reducing agent at high temperatures, participating in the denitrification process and improving the denitrification efficiency. The addition of the metal salts potassium permanganate and ferrocene broadens the temperature window, while the metal salt ions are beneficial for catalyzing the denitrification reaction. The addition of additives increases powder flowability, helps disperse the reducing agent, and results in lower ammonia slip during use, improving the utilization rate of the denitrification agent and reducing secondary pollution. The addition of the surfactant sodium dodecyl sulfate solves the problem of uneven mixing between the reducing agent and flue gas, ensuring that the active components fully contact nitrogen oxides.

[0022] 2. The high-efficiency denitrification agent of this invention solves the technical problems of low SNCR denitrification efficiency and high SCR denitrification cost. At a denitrification temperature of 775~1100℃, its flue gas denitrification efficiency can reach over 85%, and its denitrification reaction temperature window is relatively wide. The maximum denitrification efficiency of this agent can reach 96%, reducing denitrification costs while improving denitrification efficiency, and achieving ultra-low nitrogen oxide emissions. Attached Figure Description

[0023] Figure 1 Example and comparative examples show the denitrification efficiency comparison curves. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments:

[0025] Example 1

[0026] A denitrification agent comprising the following raw materials by mass percentage: 70% organic reducing agent (20% melamine, 20% n-butylamine, 10% sulfonamide, 20% hydrogen sulfide), 20% inorganic amino compound (10% ammonium dihydrogen phosphate, 5% ammonium chloride, 5% ammonium bicarbonate), 5% metal salt (1.67% potassium permanganate, 3.33% ferrocene), 3% additives (2% dispersant silica, 0.5% auxiliary agent calcium carbonate, 0.5% carrier diatomaceous earth), and 2% surfactant.

[0027] Its preparation method is as follows:

[0028] Step 1: First, grind each raw material into powder with a particle size of 150-200 mesh. Weigh out 20% organic reducing agent, 20% inorganic amino compound, and 5% metal salt according to the raw material ratio, and mix them to obtain the first mixture.

[0029] Step 2: Add additives and surfactant sodium dodecyl sulfate to the first mixture described in Step 1 according to the raw material ratio, mix evenly, and you can obtain powdered denitrification agent.

[0030] The above denitrification agent is used for NO x Concentration of 700-800 mg / Nm 3 The average value of the flue gas denitrification process is 750 mg / Nm³. 3 .

[0031] The specific denitrification process is as follows: A high-speed gas supplied by a blower delivers the metered denitrification agent to the furnace spray gun. The spray gun then sprays the denitrification agent into the boiler flue gas duct at a rate of 220 kg / h. The spray gun outlets are located at different temperature points between 700 and 1100°C. At different temperatures, the denitrification agent reacts with NO in the boiler flue gas. x The reaction proceeds. A flue gas analyzer is used to detect the concentration of nitrogen oxides in the flue gas before and after denitrification.

[0032] Examples 2-4

[0033] The denitrification agent preparation steps in Examples 2-4 are the same as those in Example 1, the difference being that the denitrification agent composition is different, as shown in Table 1.

[0034] Table 1. Composition of denitrification agents in Examples 1-4

[0035]

[0036] Comparative Example 1

[0037] Pure urea is used as a denitrification agent.

[0038] Comparative Examples 2-3

[0039] Comparative Examples 2-3 follow the same process as Example 1. In Comparative Example 2, no surfactant was added to the denitrification agent composition, and in Comparative Example 3, no metal salt was added. The denitrification agent compositions of Comparative Examples 2-3 are shown in 2.

[0040] Table 2. Composition of denitrification agents in Examples 2-3

[0041]

[0042] The denitrification efficiency of each embodiment and comparative example at different temperatures is shown in the figure below. Figure 1 As shown, the data is presented in Table 3. (From...) Figure 1 It can be seen that the denitrification reaction carried out using specific Examples 1-4 exhibits a denitrification efficiency superior to that of urea as the denitrification agent at different temperatures, and also superior to that of Comparative Examples 2 and 3. High denitrification effects are achieved at temperatures ranging from 775 to 1000°C, with denitrification efficiencies exceeding 85%. The denitrification reaction temperature window is wider than that of the comparative examples. When the denitrification temperature is 850°C, the denitrification efficiency of Example 3 reaches its maximum value of 96%.

[0043] Table 3 Denitrification efficiency of the examples and comparative examples

[0044]

Claims

1. A denitrification agent, characterized in that, It includes the following raw materials by weight percentage: 60%-70% organic reducing agent, 20%-30% inorganic amino compound, 2%-5% metal salt, 2%-5% additives, and 1%-3% surfactant; The organic reducing agent is one or more of melamine, n-butylamine, sulfonamide, and cyanuric acid; The inorganic amino compound is one or more of ammonium dihydrogen phosphate, ammonium chloride, and ammonium bicarbonate; The metal salt is a mixture of potassium permanganate and ferrocene, with a mass ratio of 1:1.5-2.

5. The additive is composed of 0.5%-2% silica as a dispersant, 0.5%-1.5% calcium carbonate as an auxiliary agent, and 1%-2% diatomaceous earth as a carrier. The surfactant is sodium dodecyl sulfate.

2. The method for preparing the denitrification agent according to claim 1, characterized in that, Includes the following steps: Step 1: Weigh each raw material according to the mass percentage, and then mix the organic reducing agent, inorganic amino compound and metal salt to obtain the first mixture; Step 2: Add additives and surfactants to the first mixture and mix well to obtain the denitrification agent.

3. The method for preparing the denitrifying agent according to claim 2, characterized in that, The particle size of each raw material is 150-200 mesh.

4. The method of using the denitrification agent according to claim 1, characterized in that, The denitrification agent is pneumatically injected into the boiler flue gas duct at a rate of 200-230 kg / h, within a temperature range of 700℃-1100℃. The denitrification agent reacts with NO in the flue gas. x The reaction proceeds to remove nitrogen oxides from the flue gas.

5. The method of using the denitrifying agent according to claim 4, characterized in that, The specific method of injecting the denitrification agent into the boiler flue gas duct using pneumatic spraying is as follows: A high-speed gas supplied by a blower delivers the denitrification agent to the furnace spray gun, which then sprays the agent into the boiler flue gas duct. The spray gun outlet is located in the flue gas duct at a temperature of 700~1100℃. The denitrification agent reacts with NO in the boiler flue gas. x The reaction will proceed.

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