A kind of high-activity ammonium carbamate powder and preparation method thereof

Abstract

The present invention relates to a highly active ammonium carbamate powder and a preparation method thereof. The highly active ammonium carbamate powder comprises, by mass, 54-56 parts of carbon dioxide, 42-44 parts of ammonia, and 0-2 parts of seed crystals (inducer). The seed crystals are sprayed into a reactor and then carbon dioxide and ammonia are introduced to directly react to form micron-sized ammonium carbamate. The resulting ammonium carbamate powder has high reactivity.

Description

Technical Field

[0001] The present invention relates to the field of denitration, and in particular to a high-activity ammonium carbamate powder and a preparation method thereof. Technical Background

[0002] Based on the "Technical Policy for Pollution Prevention and Control in Thermal Power Plants" issued by the Ministry of Ecology and Environment, the main technologies for denitrification of flue gas from pulverized coal boilers in thermal power plants are currently selective catalytic reduction (SCR) and non-selective catalytic reduction (SNCR). Urea is widely used as a reducing agent in the denitrification and ammonia production process. Although the technology for using urea to produce ammonia for power plant denitrification is relatively mature, it still faces problems such as high cost, low pyrolysis efficiency, low denitrification efficiency, and easy corrosion of the system. In particular, the actual ammonia yield of urea pyrolysis to produce ammonia is only 83% to 93%, resulting in urea waste and a series of derivative problems. Whether from an environmental perspective or an economic benefit perspective, it is extremely important to develop new and efficient denitrification agents and ammonia production technologies to improve ammonia production efficiency, reduce ammonia production temperature, and improve the economic efficiency of denitrification.

[0003] Ammonium carbamate is a promising denitrification product. However, due to current technological limitations, synthesized ammonium carbamate is primarily produced in the form of solid flakes. These flakes significantly reduce the reaction rate and economic efficiency of denitrification in practical applications. Furthermore, if the flakes are further pulverized using a secondary pulverization process, the increased mechanical temperature during the pulverization process can cause them to decompose, resulting in unnecessary product loss and increased labor and material resources, making the process unprofitable. Summary of the Invention

[0004] In response to the above-mentioned limitations, the present invention proposes a high-activity ammonium carbamate powder and a preparation method thereof. By reacting crystals with reaction gases, micron-sized high-activity ammonium carbamate powder can be produced in a "one-step" method. The powder can be used as an efficient and low-cost technology in the pyrolysis system of SCR and SNCR denitrification processes.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] The present invention provides a method for preparing high-activity ammonium carbamate powder, comprising the following steps:

[0007] S1. Select seed crystals and spray them into the reactor;

[0008] S2. The reaction gas is introduced, the seed crystal is suspended in the air and in contact with the reaction gas;

[0009] S3. The reaction generates micron-sized highly active ammonium carbamate powder.

[0010] In some embodiments of the present invention, the high-activity ammonium carbamate powder comprises 50-60 parts of carbon dioxide and 38-48 parts of ammonia by mass; further, the high-activity ammonium carbamate powder comprises 52-58 parts of carbon dioxide and 40-46 parts of ammonia by mass; preferably, the high-activity ammonium carbamate powder comprises 54-56 parts of carbon dioxide and 42-44 parts of ammonia by mass.

[0011] In some embodiments of the present invention, the seed crystal is a nano-scale powder with a particle size of 10-80 nm; further, the crystal particle size is 20-70 nm; further, the crystal particle size is 30-60 nm; further, the crystal particle size is preferably 30-50 nm.

[0012] In some embodiments of the present invention, the seed crystals include at least one of nano-graphite, nano-polyurethane powder, nano-urea powder, aerosol, and PE powder, or a mixture of two or more thereof.

[0013] In some embodiments of the present invention, the highly active ammonium carbamate is a powder; further, the particle size of the highly active ammonium carbamate powder is 1 um to 2 um; for example, it may be 1.1 um, 1.2 um, 1.3 um, 1.4 um, 1.5 um, 1.6 um, 1.7 um, 1.8 um, 1.9 um, 2.0 um, etc.

[0014] In some embodiments of the present invention, the amount of the crystals is no more than 2% (mass percentage); further, the amount of the crystals is 0.1-1% (mass percentage).

[0015] The present invention provides a high-activity ammonium carbamate powder obtained by the above-mentioned preparation method. The raw materials of the high-activity ammonium carbamate powder include reaction gas and inducer.

[0016] In some embodiments of the present invention, the reaction gas includes an N-containing gas and a C-containing gas; further, the reaction gas includes ammonia and carbon dioxide.

[0017] In some embodiments of the present invention, the inducer is a seed crystal; further, the seed crystal is of the type defined above.

[0018] The present invention also provides a use of the above-mentioned high-activity denitrification agent, wherein the high-activity denitrification agent is suitable for the hydrolysis and pyrolysis systems of SCR and SNCR denitrification processes.

[0019] Compared with the prior art, the present invention has achieved at least the following technical effects:

[0020] (1) Introducing seed crystals as inducers during the reaction can obtain micron-sized ammonium carbamate powder, avoiding the formation of large particles and lumps during the reaction, thereby increasing the reaction rate;

[0021] (2) The particle size of the ammonium carbamate powder generated by the "one-step" reaction is only 1-2 μm, which avoids the decomposition of ammonium carbamate caused by the ultrafine grinding process of the flaky ammonium carbamate powder, greatly reducing economic losses;

[0022] (3) The micron-sized ammonium carbamate generated by the reaction has a high reactivity due to its small particle size (the reactivity is increased by 45%-55% compared to the product without adding seed crystals), which greatly improves the economic efficiency of denitrification. DETAILED DESCRIPTION

[0023] The present invention provides a highly active ammonium carbamate powder and a preparation method thereof, which can effectively improve the denitration efficiency and reduce the overall energy consumption of a denitration system.

[0024] The present invention is further described in detail below with reference to the following examples. The description herein is only for explaining the present invention and is not intended to limit the scope of the present invention.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention pertains. The terms used in the specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The reagents and instruments used herein are all commercially available. The characterization methods involved can be found in the relevant descriptions in the prior art and will not be described in detail herein.

[0026] Example 1

[0027] This embodiment provides a highly active ammonium carbamate powder, wherein the raw materials, by mass, are as follows: 530 kg of carbon dioxide; 430 kg of ammonia; and 0.1 kg of nano-polyacrylate as an inducer.

[0028] Preparation method of the above-mentioned highly active ammonium carbamate powder:

[0029] S1. Select 0.1kg of nano-polyacrylate and spray it into the reactor;

[0030] S2. The reaction gas was introduced, including 530kg of carbon dioxide and 430kg of ammonia;

[0031] S3. The seed crystal grows in the reaction gas to form ammonium carbamate powder.

[0032] Example 2

[0033] This embodiment provides a highly active ammonium carbamate powder, wherein the raw materials, by mass, are: 530 kg of carbon dioxide; 430 kg of ammonia; and an inducer: 0.05 kg of nanographite.

[0034] Preparation method of the above-mentioned highly active ammonium carbamate powder:

[0035] S1. Select 0.05kg of nanographite and spray it into the reactor;

[0036] S2. The reaction gas was introduced, including 530kg of carbon dioxide and 430kg of ammonia;

[0037] S3. The seed crystal grows in the reaction gas to form ammonium carbamate powder.

[0038] Example 3

[0039] This embodiment provides a highly active ammonium carbamate powder, wherein the raw materials, by mass, are: 530 kg of carbon dioxide; 430 kg of ammonia; and 1 kg of nano-urea powder as an inducer.

[0040] Preparation method of the above-mentioned highly active ammonium carbamate powder:

[0041] S1. Select 1kg of nano-urea powder and spray it into the reactor;

[0042] S2. The reaction gas was introduced, including 530kg of carbon dioxide and 430kg of ammonia;

[0043] S3. The seed crystal grows in the reaction gas to form ammonium carbamate powder.

[0044] Technical Effects

[0045] The inventors have tested the technical effects of the above embodiments and comparative examples. In order to intuitively display the results, Table 1 is compiled as follows.

[0046] Table 1 Particle size and reaction activity test table

[0047]

[0048]

[0049] As can be seen from Table 1, when no seed crystals are added, the product is flaky and uneven in size, which in turn affects the reaction activity of the product. By adding seed crystals, not only can micron-level ammonium carbamate powder be obtained in one step, but the reaction activity of the product is also greatly increased (compared with no seed crystals, the particle size of the product is micron-level, and the reaction activity increases by 45%-55%), thereby improving the economic efficiency of denitrification.

[0050] It is understood that the above embodiments are merely exemplary embodiments for illustrating the principles of the present invention, and the present invention is not limited thereto, and therefore, the present application is not limited thereto. For those skilled in the art, various modifications, variations, alterations, equivalent substitutions, or improvements can be made without departing from the spirit and essence of the present invention, and all of these are deemed to fall within the scope of protection of the present invention.

Claims

1. A method for preparing highly active ammonium carbamate powder, characterized in that: The following steps are involved: S1. Select seed crystals and spray them into the reactor; S2. The reaction gas is introduced, the seed crystal is suspended in the air and in contact with the reaction gas; S3. The reaction generates micron-sized ammonium carbamate powder; The seed crystals include at least one of nano graphite, nano polyurethane powder, and nano urea powder, or a mixture of two or more thereof.

2. The preparation method according to claim 1, characterized in that The seed crystal is nano-scale powder with a particle size of 30-50 nm.

3. The preparation method according to claim 1, characterized in that The particle size of the high-activity ammonium carbamate powder is 1 μm to 2 μm.

4. The preparation method according to claim 1, characterized in that The raw materials of the high-activity ammonium carbamate powder include reaction gas and seed crystals, and are applied to the SCR and SNCR denitration process pyrolysis systems.

5. The preparation method according to claim 4, characterized in that The reaction gas includes ammonia and carbon dioxide.

6. The preparation method according to claim 4, characterized in that The seed crystals are of the type defined in any one of claims 1-2.

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