CN109107373B

CN109107373B - Denitration agent for coal-fired flue gas denitration and preparation method thereof

Info

Publication number: CN109107373B
Application number: CN201810936955.6A
Authority: CN
Inventors: 程广文; 杨嵩; 姚明宇; 郭中旭; 杨成龙
Original assignee: Xian Thermal Power Research Institute Co Ltd
Current assignee: Xian Thermal Power Research Institute Co Ltd
Priority date: 2018-08-16
Filing date: 2018-08-16
Publication date: 2020-12-11
Anticipated expiration: 2038-08-16
Also published as: CN109107373A

Abstract

The denitration agent comprises 1-5% of a reducing agent and 95-99% of a dispersing agent by mass percent, wherein the reducing agent is an amino-terminated hyperbranched polymer. Dissolving an amino-terminated hyperbranched polymer in an alcohol solvent to form a solution, adding reductive powder into the solution for soaking, filtering, drying and grinding to obtain the denitration agent for coal-fired flue gas denitration. The reducing agent in the formula of the denitrifier disclosed by the invention is an amino-terminated hyperbranched polymer, and the molecular structure of the amino-terminated hyperbranched polymer contains a large amount of NH₂And the denitration active center can be directly formed at high temperature, so that the formula of the denitration agent is relatively simple (two components), and high denitration efficiency is easier to obtain. The preparation method of the denitration agent disclosed by the invention can uniformly mix the two components at a molecular level, so that the stability of the denitration efficiency is ensured. The preparation process is simple and suitable for large-scale production.

Description

Denitration agent for coal-fired flue gas denitration and preparation method thereof

Technical Field

The invention belongs to the field of electric power environmental protection, relates to coal-fired flue gas denitration, and particularly relates to a denitration agent for coal-fired flue gas denitration and a preparation method thereof.

Background

With the national emphasis on environmental protection, the flue gas denitration of industrial boilers (kilns) has also been proposed. Because the smoke temperature of an industrial boiler (kiln) is generally low, the SCR method widely applied to a coal-fired power plant is not suitable for denitration of the smoke of the industrial boiler (kiln), and a certain denitration agent is sprayed into a hearth, so that denitration by adopting an SNCR (selective non-catalytic reduction) process becomes an important technical approach (high-efficiency selective reduction) for denitration of the smoke of the industrial boiler (kiln). Different from the traditional SCR method and the SNCR method, the efficient selective reduction method can show higher removal efficiency in the aspect of flue gas denitration of an industrial boiler (kiln), but has more factors influencing the denitration efficiency, including the combustion mode of the boiler, the injection amount of a denitration agent, the mixing degree of the denitration agent and flue gas, the retention time of the denitration agent in the flue gas, the flue gas temperature, the flue gas composition and the like. Analysis shows that the denitrifier is bondedThe structure or the formula is the fundamental factor for determining the efficient selective reduction denitration efficiency. Therefore, in recent years, the development of a high-efficiency denitration agent has been receiving much attention. For example, CN106861431A discloses a four-effect denitration agent, which is composed of nine components, i.e., a reducing agent, a catalyst, an adsorbent, an accelerator, a dispersant, an activator, a penetrating agent, a corrosion inhibitor, an initiator, etc. The denitration agent is characterized by being mixed with NO_xReacted other than NH₃But the ammonia free radical with very high activity effectively overcomes the defects of high reaction temperature and low denitration efficiency of the traditional SNCR, and shows very high denitration efficiency (more than or equal to 80 percent) in the aspects of flue gas denitration of circulating fluidized bed boilers, chain furnaces, water-coal slurry boilers and the like. Patent CN103977701A discloses a denitrifier comprising sludge, urea, ammonium salt and water, which also exhibits high removal efficiency (about 70%) in cement kiln flue gas denitration. Patent CN105771645A discloses a high molecular dry denitration agent composed of urea, silica, sodium carbonate, bentonite, anhydrous sodium sulphate and shale powder; patent CN107149867A discloses an environment-friendly low-temperature denitrifier consisting of organic alcohol, organic amine, urea, hydroxypropyl methylcellulose and water; CN107952346A discloses a biomass denitration agent consisting of melamine-amide, modified plant cellulose, cyanuric acid-amide, peroxycarbonate amide and adsorbent. The denitration agent has higher denitration efficiency under the condition of fixed flue gas, but because the components of the denitration agent are complex, on one hand, the denitration cost is increased, and meanwhile, the instability of the denitration efficiency is increased, in other words, when the combustion type of a boiler or the flue gas condition changes, the content of each component of the denitration agent needs to be optimized and adjusted again to maintain certain denitration efficiency. Therefore, it is necessary and important to simplify the components of the denitrifier and increase the universality of the denitrifier.

Disclosure of Invention

In order to overcome the problems of the existing denitration agent, the invention aims to provide the denitration agent for coal-fired flue gas denitration and the preparation method thereof.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

the denitration agent comprises 1-5% of a reducing agent and 95-99% of a dispersing agent by mass percent, wherein the reducing agent is an amino-terminated hyperbranched polymer.

The invention further improves that the repeating unit structure of the amino-terminated hyperbranched polymer is as follows:

the amino-terminated hyperbranched polymer is prepared by the following processes: adding methyl acrylate and divinyl triamine into methanol, and reacting for 4 hours at room temperature; wherein the ratio of methyl acrylate, divinyl triamine and methanol is 43:52: 100.

The further improvement of the invention is that the reducing powder is activated carbon powder or activated coke powder.

The preparation method of the denitration agent for coal-fired flue gas denitration comprises the steps of dissolving the amino-terminated hyperbranched polymer in an alcohol solvent to form a solution, adding the reducing powder into the solution for soaking, filtering, drying and grinding to obtain the denitration agent for coal-fired flue gas denitration.

In a further improvement of the invention, the alcoholic solvent is methanol, ethanol or propanol.

The invention is further improved in that the mass concentration of the solution is 1-5%.

The soaking temperature is room temperature, and the soaking time is 2-4 hours.

The drying temperature was 90 ℃ and the drying time was 5 hours.

Compared with the prior art, the invention has the following beneficial effects:

(1) efficient selective reduction denitration is mainly based on NH₂Reaction with NO, in existing denitrifier systems, NH₂Is dependent on NH generation by the reductant component of the formulation₃The interaction with OH or O and the like generated by other components causes the problem that the existing denitration agent has a relatively complex formula. The invention discloses a denitration agent formula in which a reducing agent is an amino-terminated supermicroBranched polymers containing substantial amounts of NH within the molecular structure itself₂And the denitration active center can be directly formed at high temperature, so that the formula of the denitration agent is relatively simple (two components), and high denitration efficiency is easier to obtain. The denitration efficiency of the denitration agent prepared by the method reaches 90-94%.

(2) The existing denitration agent usually contains various solid components with different properties, and is difficult to mix uniformly, so that the prepared denitration agent has poor uniformity and the stability of denitration efficiency is influenced. The preparation method of the denitration agent disclosed by the invention can uniformly mix the two components at a molecular level, so that the stability of the denitration efficiency is ensured. The preparation process is simple and suitable for large-scale production.

Drawings

FIG. 1 is a chemical structure diagram of a repeating unit of the amino-terminated hyperbranched polymer of the invention.

Detailed Description

The present invention will now be described in further detail with reference to specific examples, which are intended to be illustrative, but not limiting, of the invention.

The denitration agent for denitration of coal-fired flue gas comprises 1-5% of a reducing agent and 95-99% of a dispersing agent by mass percent.

Wherein, referring to fig. 1, the reducing agent is an amino-terminated hyperbranched polymer, and the repeating unit structure of the amino-terminated hyperbranched polymer is as follows:

the amino-terminated hyperbranched polymer is prepared by taking methyl acrylate and divinyl triamine as raw materials and methanol as a reaction medium and reacting for 4 hours at room temperature. Wherein the ratio of methyl acrylate, divinyl triamine and methanol is 43:52: 100.

The dispersing agent is reductive powder; specifically, the reducing powder is activated carbon powder or activated coke powder.

The preparation method of the denitration agent for denitration of the coal-fired flue gas comprises the steps of dissolving the amino-terminated hyperbranched polymer in an alcohol solvent to form a solution with the mass fraction of 1-5%, adding the reducing powder into the solution, soaking the solution at room temperature for 2-4 hours, filtering the solution, drying the solution at 90 ℃ for 5 hours, and grinding the solution to obtain the denitration agent for denitration of the coal-fired flue gas.

The alcohol solvent is methanol, ethanol or propanol.

And (4) inspecting the denitration performance of the denitration agent by using real coal-fired flue gas on a 1MW one-dimensional furnace. The results are shown in Table 1.

TABLE 1 preparation conditions and results for the inventive denitrifier examples disclosed in the present invention

As can be seen from Table 1, the denitration efficiency of the denitration agent prepared by the method is between 90 and 94 percent.

Claims

1. A denitration agent for denitration of coal-fired flue gas is characterized by comprising 1-5% of a reducing agent and 95-99% of a dispersing agent in percentage by mass; wherein, the dispersing agent is active carbon powder or active coke powder, and the reducing agent is amino-terminated hyperbranched polymer;

the repeating unit structure of the amino-terminated hyperbranched polymer is as follows:

2. the denitration agent for denitration of coal-fired flue gas according to claim 1, wherein the amino-terminated hyperbranched polymer is prepared by the following steps: adding methyl acrylate and divinyl triamine into methanol, and reacting for 4 hours at room temperature; wherein the ratio of methyl acrylate, divinyl triamine and methanol is 43:52: 100.

3. The preparation method of the denitration agent for denitration of coal-fired flue gas according to any one of claims 1 to 2, characterized by dissolving the amino-terminated hyperbranched polymer in an alcohol solvent to form a solution, then adding the dispersant into the solution for soaking, then filtering, drying and grinding to obtain the denitration agent for denitration of coal-fired flue gas.

4. The preparation method of the denitration agent for denitration of coal-fired flue gas according to claim 3, wherein the alcohol solvent is methanol, ethanol or propanol.

5. The preparation method of the denitration agent for denitration of coal-fired flue gas according to claim 3, wherein the mass concentration of the solution is 1-5%.

6. The preparation method of the denitration agent for denitration of coal-fired flue gas according to claim 3, wherein the soaking temperature is room temperature, and the soaking time is 2-4 hours.

7. The preparation method of the denitration agent for denitration of coal-fired flue gas as claimed in claim 3, wherein the drying temperature is 90 ℃ and the drying time is 5 hours.