Ammonia-free denitration agent, application thereof and cement industry denitration method

Abstract

The application discloses an ammonia-free denitration agent and application and a cement industry denitration method, and belongs to the technical field of cement production. The ammonia-free denitration agent comprises 13-18% of an oxidizing agent, 1-3% of a catalyst and 15-19% of an absorbent, and the balance is water. The oxidizing agent in the ammonia-free denitration agent mainly provides an oxygen source, and through cooperation with the catalyst, gaseous NO x can be quickly and directionally converted into NO2, which is then converted into stable nitrate by the absorbent, so that efficient removal of NO x in tail gas and ultra-low emission at the end are realized. In the production process, the ammonia-free denitration agent is used in combination with the cement industry denitration method, the operation cost is low, the operation is easy, a large amount of ammonia water does not need to be sprayed, a large amount of ammonia escape is avoided, and the ultra-low emission can be effectively realized.

Description

Technical Field

[0001] This invention relates to the field of cement production technology, and more specifically, to an ammonia-free denitrification agent and its application in denitrification methods in the cement industry. Background Technology

[0002] Currently, there are three main types of technologies used for denitrification in the cement industry: low-NOx combustion technology, SNCR denitrification, and SCR denitrification.

[0003] Various denitrification technologies are further subdivided into several denitrification technology routes based on their different implementation methods. Ultra-low emissions of cement production waste gas are an inevitable trend. From the perspective of current denitrification technologies, it is not easy to achieve a balance between ultra-low emissions and economic efficiency by using a single denitrification technology alone.

[0004] While low-NOx combustion technology is the most economical, it can reduce NOx emissions at the source. x While ammonia is generated, the reduction is limited and cannot achieve ultra-low emissions at the end of the line; SNCR technology is limited by reaction efficiency, and controlling lower emission indicators requires a large amount of ammonia water to be injected, which will cause a large amount of ammonia to escape.

[0005] SCR technology can achieve ultra-low emissions and low ammonia slip, with the catalyst dosage and NO treatment efficiency being relatively low. x The amount is directly proportional to the NO entering the SCR exhaust gas. x Excessive concentration will lead to an increase in the amount of catalyst used and an increase in operating costs.

[0006] In view of this, the present invention is proposed. Summary of the Invention

[0007] One of the objectives of this invention is to provide an ammonia-free denitrification agent that can reduce NO levels during cement production. x Highly efficient removal and ultra-low emissions.

[0008] The second objective of this invention is to provide an application of the aforementioned ammonia-free denitrification agent.

[0009] The third objective of this invention is to provide a denitrification method for the cement industry.

[0010] This application can be implemented as follows:

[0011] In one aspect, this application provides an ammonia-free denitrification agent, which, by mass percentage, comprises 13-18% oxidant, 1-3% catalyst, and 15-19% absorbent, with the balance being water.

[0012] In an optional embodiment, the ammonia-free denitrification agent further includes 0.5-1% of a dispersant.

[0013] In an alternative embodiment, the ammonia-free denitrification agent comprises 15.5% of oxidizing agent, 2% of catalyst, 17% of absorbent, and 0.75% of dispersant, with the balance being water.

[0014] In an alternative embodiment, the oxidizing agent comprises at least one of permanganate, perchlorate, peroxoate, and hypochlorite.

[0015] In an alternative embodiment, the oxidizing agent comprises at least one of potassium permanganate, potassium perchlorate, sodium peroxoacetate, and sodium hypochlorite.

[0016] In an alternative embodiment, the catalyst is a compound comprising both a rare earth element and a transition metal.

[0017] In an alternative embodiment, the rare earth element comprises lanthanum.

[0018] In an alternative embodiment, the transition metal comprises at least one of cobalt, nickel, and iron.

[0019] In an alternative embodiment, the catalyst comprises at least one of lanthanum nickelate, lanthanum cobaltate, and lanthanum ferrite.

[0020] In an alternative embodiment, the absorbent comprises at least one of sodium carbonate, potassium carbonate, and water glass.

[0021] In an alternative embodiment, the dispersant comprises at least one of polyvinylpyrrolidone, polyethylene glycol, and cetyltrimethylammonium bromide.

[0022] In a second aspect, the present application provides use of the ammonia-free denitrification agent of any of the preceding embodiments, for example, for denitrification in the cement industry.

[0023] In a third aspect, the present application provides a method for denitrification in the cement industry, comprising the following steps:

[0024] In the cement production process, the ammonia-free denitrification agent of any of the preceding embodiments is added to the cement production equipment, so that the ammonia-free denitrification agent contacts with the nitrogen oxides generated in the cement production process and finally converts the nitrogen oxides into nitrates.

[0025] In an alternative embodiment, the ammonia-free denitrification agent is added in an amount of 0.1-1 m 3 / h.

[0026] In an alternative embodiment, the ammonia-free denitrification agent is added in the form of atomized spraying.

[0027] The beneficial effects of the present application include:

[0028] The oxidizing agent in the ammonia-free denitrification agent provided by the present application mainly provides an oxygen source, which, through cooperation with the catalyst, can convert gaseous NO xFast and directional conversion to NO2, and then to stable nitrate by absorption agent, so as to realize high-efficiency removal of NO x In the production process, the above ammonia-free denitration agent is used in combination with the denitration method of the cement industry, the operation cost is low, the operation is easy, a large amount of ammonia water does not need to be sprayed, a large amount of ammonia escape is not caused, and the ultra-low emission can be effectively realized. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below. If specific conditions are not specified in the embodiments, conventional conditions or manufacturer recommended conditions are used. If the reagents or instruments used are not specified by the manufacturer, they are all conventional products that can be purchased on the market.

[0030] The ammonia-free denitration agent and the application thereof and the denitration method of the cement industry provided in the present application will be specifically described below.

[0031] The present application provides an ammonia-free denitration agent, which comprises 13-18% of an oxidizing agent, 1-3% of a catalyst and 15-19% of an absorption agent, and the balance is water.

[0032] In the present application, the oxidizing agent is mainly used to provide an oxygen source and oxidize the remaining valence state N into +4 valence N.

[0033] For example, the above oxidizing agent can comprise at least one of permanganate, perchlorate, peroxy acid salt and hypochlorite.

[0034] For example, the permanganate can be potassium permanganate and / or sodium permanganate, the perchlorate can be sodium perchlorate and / or potassium perchlorate, the peroxy acid salt can be sodium peroxyacetate, and the hypochlorite can be sodium hypochlorite and / or potassium hypochlorite.

[0035] In some preferred embodiments, the above oxidizing agent comprises at least one of potassium permanganate, potassium perchlorate, peroxyacetic acid and sodium hypochlorite.

[0036] It should be noted that the above preferred oxidizing agent can have a better oxidation effect on gaseous NO x than other oxidizing agents.

[0037] For reference, the content of the above oxidizing agent in the ammonia-free denitration agent can be 13%, 13.5%, 14%, 14.5%, 15%, 15.5%, 16%, 16.5%, 17%, 17.5% or 18%, or other arbitrary values in the range of 13-18%; and preferably 15.5%.

[0038] If the content of the oxidant in the ammonia-free denitration agent is less than 13%, the gaseous NO x cannot be completely converted into NO2; if the content of the oxidant in the ammonia-free denitration agent is more than 18%, the solubility in water is not good, and the denitration effect is reduced.

[0039] In the present application, the catalyst is mainly used to cooperate with the oxidant to convert the gaseous NO x into NO2 quickly and directionally.

[0040] Exemplarily, the catalyst is a compound containing both a rare earth element and a transition metal.

[0041] The rare earth element may be lanthanum, cerium, gadolinium, erbium, neodymium, samarium, or the like, and the transition metal may be chromium, manganese, iron, cobalt, nickel, copper, and / or zinc, or the like.

[0042] In some preferred embodiments, the rare earth element includes lanthanum, and the transition metal includes at least one of cobalt, nickel, and iron.

[0043] In some more preferred embodiments, the catalyst includes at least one of lanthanum nickelate, lanthanum cobaltate, and lanthanum ferrite.

[0044] It should be noted that the catalyst containing both a rare earth element and a transition metal (especially the preferred catalyst) can improve the conversion speed of the gaseous NO x compared to other types of catalysts.

[0045] For reference, the content of the catalyst in the ammonia-free denitration agent may be 1%, 1.5%, 2%, 2.5%, or 3%, or other values within the range of 1-3%; and is preferably 2%.

[0046] If the content of the catalyst in the ammonia-free denitration agent is less than 1%, on the one hand, the amount of NO x that can be treated is small, and the gaseous NO x cannot be completely converted into NO2; on the other hand, the speed of converting NO x into NO2 is too slow; if the content of the catalyst in the ammonia-free denitration agent is more than 3%, the processing cost is greatly increased.

[0047] In the present application, the absorbent is mainly used to convert NO2 into stable nitrate, so as to achieve efficient removal of NO x in the tail gas.

[0048] Exemplarily, the absorbent may include at least one of sodium carbonate, potassium carbonate, and water glass.

[0049] Taking sodium carbonate as an absorbent as an example, it can convert NO2 into sodium nitrate; similarly, potassium carbonate can convert NO2 into potassium nitrate; and water glass can convert NO2 into sodium silicate.

[0050] For reference, the content of the absorbent in the ammonia-free denitrification agent can be 15%, 15.5%, 16%, 16.5%, 17%, 17.5%, 18%, 18.5%, or 19%, or any other value in the range of 15-19%; preferably 17%.

[0051] If the absorbent content in the ammonia-free denitrification agent is less than 15%, it is not conducive to the absorption of oxidized nitrogen oxides; if it is higher than 17%, it is not conducive to the quality of cement clinker and affects its later strength.

[0052] Furthermore, the aforementioned ammonia-free denitrification agent may also include 0.5-1% of a dispersant.

[0053] In this application, the dispersant is mainly used to increase the solubility of the oxidant and the catalyst, thereby improving the NO content. x Conversion efficiency to nitrate.

[0054] For example, the dispersant may include at least one of polyvinylpyrrolidone, polyethylene glycol, and hexadecyltrimethylammonium bromide.

[0055] Using the above-mentioned substances as dispersants can improve the solubility of oxidants and catalysts better than using other dispersants.

[0056] For reference, the content of the above-mentioned dispersant in the ammonia-free denitrification agent can be 0.5%, 0.6%, 0.7%, 0.8%, 0.9% or 1%, or any other value in the range of 0.5-1%; preferably 0.75%.

[0057] If the dispersant content in the ammonia-free denitrification agent is less than 0.5%, the solubility of the oxidant and catalyst will be low; if it is higher than 1%, it will hinder the interaction between the components and reduce the denitrification efficiency.

[0058] In some preferred embodiments, the ammonia-free denitrification agent comprises 15% oxidant, 2% catalyst, 17.5% absorbent, and 0.75% dispersant, with the balance being water.

[0059] In some preferred embodiments, the oxidant is potassium perchlorate, the dispersant is polyvinylpyrrolidone, the catalyst is lanthanum nickelate, and the absorbent is potassium carbonate.

[0060] In some preferred embodiments, the ammonia-free denitrification agent comprises 15% potassium perchlorate, 2% lanthanum nickelate, 17.5% potassium carbonate, and 0.75% polyvinylpyrrolidone, with the balance being water.

[0061] In summary, the mechanism of the ammonia-free denitration agent is as follows: the oxidant in the ammonia-free denitration agent mainly provides oxygen source, which, through the cooperation of the catalyst, can convert gaseous NO x into NO2quickly and directionally, which is then converted into stable nitrate by the absorbent, thereby achieving the efficient removal of NO x from the tail gas. The main role of the dispersant is to increase the solubility of the oxidant and the catalyst, thereby improving the conversion efficiency of NO x into nitrate. Finally, the generated nitrate particles are captured in the dust collection process, thereby achieving the purpose of denitration.

[0062] Correspondingly, the application also provides the use of the ammonia-free denitration agent described above, for example, for denitration in the cement industry.

[0063] In addition, the application also provides a denitration method for the cement industry, which may, for example, comprise the following steps:

[0064] In the cement production process, the ammonia-free denitration agent described above is added to the cement production equipment, so that the ammonia-free denitration agent contacts the nitrogen oxides generated in the cement production process and finally converts the nitrogen oxides into nitrate.

[0065] Specifically, the ammonia-free denitration agent can be added to the denitration reaction zone at the outlet of the high-temperature fan of the cement production equipment, thereby contacting and reacting with the nitrogen oxides in the flue gas, oxidizing the environmentally harmful nitrogen oxides into NO2and converting them into harmless nitrate by the absorbent.

[0066] For reference, the amount of the ammonia-free denitration agent added can be 0.1-1 m 3 / h, such as 0.1 m 3 / h, 0.2 m 3 / h, 0.3 m 3 / h, 0.4 m 3 / h, 0.5 m 3 / h, 0.6 m 3 / h, 0.7 m 3 / h, 0.8 m 3 / h, 0.9 m 3 / h, or 1 m 3 / h, etc., or any other value within the range of 0.1-1 m 3 / h.

[0067] It should be noted that the specific amount of the ammonia-free denitration agent added can be appropriately adjusted within the above range according to actual conditions.

[0068] In some preferred embodiments, the ammonia-free denitration agent can be added in the form of atomized spraying, so as to fully and uniformly contact the nitrogen oxides.

[0069] The features and properties of the present application are described in further detail below in connection with the examples.

[0070] Example 1

[0071] This example provides an ammonia-free denitration agent, which includes 15% of potassium perchlorate, 2% of lanthanum nickelate, 17.5% of potassium carbonate, and 0.75% of polyvinylpyrrolidone by mass percentage, with the balance being water.

[0072] Example 2

[0073] This example provides an ammonia-free denitration agent, which includes 13% of potassium perchlorate, 1% of lanthanum nickelate, 15% of potassium carbonate, and 0.5% of polyvinylpyrrolidone by mass percentage, with the balance being water.

[0074] Example 3

[0075] This example provides an ammonia-free denitration agent, which includes 18% of potassium perchlorate, 3% of lanthanum nickelate, 19% of potassium carbonate, and 1% of polyvinylpyrrolidone by mass percentage, with the balance being water.

[0076] Example 4

[0077] This example is different from Example 1 in that the ammonia-free denitration agent of this example does not contain a dispersant.

[0078] Example 5

[0079] This example is different from Example 1 in that potassium permanganate is used instead of potassium perchlorate in Example 1.

[0080] Example 6

[0081] This example is different from Example 1 in that peroxoacetic acid is used instead of potassium perchlorate in Example 1.

[0082] Example 7

[0083] This example is different from Example 1 in that sodium hypochlorite is used instead of potassium perchlorate in Example 1.

[0084] Example 8

[0085] This example is different from Example 1 in that lanthanum cobaltate is used instead of lanthanum nickelate in Example 1.

[0086] Example 9

[0087] This example is different from Example 1 in that lanthanum ferrite is used instead of lanthanum nickelate in Example 1.

[0088] Example 10

[0089] The difference between this embodiment and embodiment 1 is that sodium carbonate is used instead of potassium carbonate in embodiment 1.

[0090] Embodiment 11

[0091] The difference between this embodiment and embodiment 1 is that sodium carbonate is used instead of potassium carbonate in embodiment 1.

[0092] Embodiment 12

[0093] The difference between this embodiment and embodiment 1 is that sodium carbonate is used instead of potassium carbonate in embodiment 1.

[0094] Embodiment 13

[0095] The difference between this embodiment and embodiment 1 is that sodium carbonate is used instead of potassium carbonate in embodiment 1.

[0096] Test Example

[0097] Take the ammonia-free denitration agent provided in embodiment 1 as an example, it is added at the outlet of the high-temperature fan of the cement kiln in a way of atomization spraying, so that it can fully contact and react with nitrogen oxides in the flue gas, oxidize the harmful nitrogen oxides into NO2 and convert them into harmless nitrates by the absorbent, and observe the change of nitrogen oxide emission value at the kiln tail at different time points, compare with the case without adding the denitration agent to judge the denitration effect of the denitration agent, and the results are shown in Table 1.

[0098] Table 1 Denitration results

[0099]

[0100]

[0101] Note: "days" refers to the clinker output per hour.

[0102] As can be seen from Table 1, by using the ammonia-free denitration agent of the present application in the cement production process, gaseous NO x can be quickly and directionally converted into NO2, and then converted into stable nitrates by the absorbent, thereby realizing the efficient removal of NO x in the tail gas and the ultra-low emission (≤50 mg / Nm 3 ) at the end, and without the need for a large amount of ammonia water injection, which will not cause a large amount of ammonia escape.

[0103] Test Example 2

[0104] The ammonia-free denitration agent provided in embodiment 1 is added in the outlet pipeline of the high-temperature fan, and fully contacts and reacts with nitrogen oxides in the flue gas through spray gun atomization, so as to achieve the purpose of reducing nitrogen oxides.

[0105] Test method: Before the test, the ammonia water use pressure is automatically controlled (7.5 bar), the kiln table and kiln condition are stabilized, and when the nitrogen oxide emission is basically stable, the denitration agent is added, the nitrogen oxide emission value change is observed, and the denitration effect is verified.

[0106] Test steps:

[0107] S1: Transport the denitration agent to the designated position;

[0108] S2: Connect the compressed air pipe to the gas end of the spray gun, connect the liquid pipe to the liquid end of the spray gun, start the pump and compressed air for debugging, and reach the optimal atomization state;

[0109] S3: Place the spray gun at the pre-drilling position of the high-temperature fan outlet and fix it;

[0110] S4: Automatically control the ammonia water use pressure (7.5 bar), stabilize the kiln table and kiln condition, and when the nitrogen oxide emission is basically stable, count the blank period data, and then add the denitration agent for testing. The specific test conditions are as follows:

[0111] Blank period 14:00-14:30, nitrogen oxide emission value 64-71 mg / Nm 3 , 14:30 nitrogen oxide emission value 64 mg / Nm 3 , start adding the denitration agent for testing, stop testing at 15:48, and the specific data are shown in Table 2.

[0112] Table 2 Test results

[0113]

[0114] As can be seen from Table 2, the ammonia-free denitration agent provided in the application has the following effects:

[0115] A. Fast reaction speed: after adding the ammonia-free denitration agent, the nitrogen oxide emission value starts to decrease in 3-4 minutes, and tends to be stable in 10 minutes;

[0116] B. Certain effect on nitrogen oxide emission control, which can reduce the nitrogen oxide from 65 mg / Nm 3 to a minimum of 35 mg / Nm 3 ;

[0117] C. The ammonia-free denitration agent added at the high-temperature fan outlet has no effect on the entire kiln system and coal consumption, while the ammonia water is added at the C5 outlet of the cement kiln, and after increasing the ammonia water use amount, the coal consumption increases. In summary, the oxidizing agent in the ammonia-free denitration agent provided in the application mainly provides oxygen source, which can quickly and directionally convert gaseous NO x into NO2 through the cooperation of the catalyst, and then convert it into stable nitrate through the absorbent, thereby realizing the conversion of NOx The high removal efficiency and the ultra-low emission of the end. In the production process, the above-mentioned ammonia-free denitration agent is used to assist the denitration method of the cement industry, the operation cost is low, the operation is easy, and a large amount of ammonia water does not need to be sprayed, a large amount of ammonia escape will not be caused, and the ultra-low emission can be effectively realized.

[0118] The above are only preferred embodiments of the present application and are not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for denitration in the cement industry, characterized in that, The method comprises the following steps: In the cement production process, the ammonia-free denitration agent is added into the cement production equipment to contact with the nitrogen oxides generated in the cement production process and finally convert the nitrogen oxides into nitrate; the ammonia-free denitration agent is added in the form of atomized spraying; The ammonia-free denitration agent comprises 13-18% of oxidizing agent, 1-3% of catalyst, 15-19% of absorbent and 0.5-1% of dispersant by mass percentage, and the balance is water; The oxidizing agent is at least one selected from potassium permanganate, potassium perchlorate, sodium peroxyacetate and sodium hypochlorite; the catalyst is at least one selected from lanthanum nickelate, lanthanum cobaltate and lanthanum ferrite; and the absorbent is at least one selected from sodium carbonate, potassium carbonate and water glass.

2. The method of cement industry denitration according to claim 1, characterized in that, The ammonia-free denitration agent comprises 15.5% of the oxidizing agent, 2% of the catalyst, 17% of the absorbent and 0.75% of the dispersant, and the balance is water.

3. The method of cement industry denitration according to claim 1, characterized in that, The dispersant comprises at least one of polyvinylpyrrolidone, polyethylene glycol and cetyltrimethylammonium bromide.

4. The method of cement industry denitration according to claim 1, characterized in that, The amount of the ammonia-free denitration agent added is 0.1-1 m 3 / h.

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