A production process for preventing diesel exhaust treatment fluid from generating flocculent suspended matter or sediment

Abstract

The present invention discloses a production process for avoiding the generation of flocculent suspended matter or sediment in diesel exhaust treatment liquid, comprising: introducing a first nitrogen gas into a reactor from a stirring vent to discharge the air in the reactor and reduce the impurities suspended in the reactor; in response to the complete discharge of the air in the reactor, adding deionized water into the reactor from a water inlet; introducing a second nitrogen gas into the reactor from a stirring vent, and adding solid urea particles into the reactor from a urea feed port; in response to the completion of the addition of solid urea particles, closing all the connecting holes of the reactor except the stirring vent and the exhaust port, controlling the second nitrogen introduction speed to increase the pressure in the reactor to a preset pressure; in response to the complete dissolution of the solid urea particles, controlling the rotation of the stirring blades, mixing the liquids in the reaction zone and the mixing zone, and obtaining the diesel exhaust treatment liquid. The present invention reduces the introduction of metal ions, thereby avoiding the generation of metal hydroxide suspended matter or sediment.

Description

Technical Field

[0001] The invention relates to the field of diesel exhaust treatment liquid production, and in particular to a production process for preventing diesel exhaust treatment liquid from generating flocculent suspended matter or sediment. Background Art

[0002] As environmental regulations become increasingly stringent, people are paying more and more attention to the pollution of diesel exhaust pollutants to the environment and the harm to human health. Diesel exhaust treatment fluid (commonly known as automotive urea in China) is widely used in the gas purification system of large diesel vehicles, namely the reducing agent of the SCR (Selective Catalytic Reduction) system. Its principle is to use the exhaust treatment fluid to react with nitrogen oxides in the exhaust gas of heavy trucks, buses and other diesel vehicles to generate N2 and H2O to purify the exhaust gas, so that the nitrogen oxides discharged can meet the national emission standards of National IV, National V and above.

[0003] After years of development, the production technology of domestic exhaust gas treatment fluid has made great progress, but there are still some technical bottlenecks that restrict the further development of the industry. Since the exhaust gas treatment fluid has extremely high requirements for metal ion content and insoluble matter, and has strict requirements for the storage environment. The existing production and storage environment are difficult to meet the above requirements. As a result, the exhaust gas treatment fluid produced in China breeds suspended matter (called "algae" in the industry) under certain circumstances, and the suspended matter makes the exhaust gas treatment fluid product difficult to use. There will be a small amount of metal impurity ions such as iron, chromium, aluminum, and nickel in the production process of exhaust gas treatment fluid. During the preparation and storage process, the automotive urea aqueous solution will hydrolyze to produce hydroxide ions and make the solution weakly alkaline. Under certain conditions, hydroxide ions and metal impurity ions such as iron, chromium, aluminum, and nickel will produce nano-scale amorphous metal hydroxides. These amorphous metal hydroxides will further aggregate to form flocculent suspended matter visible to the naked eye and even flocculent precipitation. The time period for the generation of suspended matter fluctuates greatly, ranging from one or two days to weeks or months, which greatly increases the difficulty of the development of suspended matter removal process. Simply adding filtration steps will have little effect. Summary of the invention

[0004] The applicant has found that excessive metal ions in diesel exhaust treatment fluid will combine with hydroxide to form metal hydroxides and then aggregate and precipitate. There are generally three sources of metal ions. First, the purity of the raw materials (generally deionized water and solid urea particles) is not high and is doped with impurities; second, impurity particles suspended in the air; third, the diesel exhaust treatment fluid is prone to hydrolysis during the preparation process, and the intermediate products of hydrolysis (some amines, such as methylamine) and the final product (ammonia) will corrode the metal reactor and produce metal ions. Metals are also commonly used materials for diesel exhaust treatment fluid reactors. The existing technology usually produces diesel exhaust treatment fluid by filtering or treating suspended matter and sediments in the diesel exhaust treatment fluid in the form of post-compensation. Since the aggregation and generation time of metal hydroxides is relatively long, such a treatment method will still generate suspended matter and sediments when the diesel exhaust treatment fluid is left standing after leaving the factory, and the effect is not very ideal.

[0005] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is to provide a production process for preventing the diesel exhaust treatment fluid from producing flocculent suspended matter or sediment, aiming to reduce the generation of metal ions from the source, thereby preventing the generation of flocculent suspended matter or sediment, and improving the treatment effect of flocculent suspended matter or sediment in the diesel exhaust treatment fluid.

[0006] To achieve the above-mentioned purpose, the present invention discloses a production process for preventing diesel exhaust treatment fluid from generating flocculent suspended matter or sediment, which is applied to a metal reactor, wherein the central area within a preset range of the reactor is a reaction zone, and the reaction zone is surrounded by a mixing zone. The bottom of the reactor corresponding to the reaction zone is provided with stirring vents arranged in an array, and a stirring blade is provided at the center of the bottom of the reactor, and the length of the stirring blade covers the reaction zone and the mixing zone. A water inlet, an exhaust port, and a urea feed port opposite to the reaction zone are also provided above the reactor. The process comprises:

[0007] Introducing a first nitrogen gas into the reactor from the stirring vent hole to discharge the air in the reactor and reduce the impurities suspended in the reactor;

[0008] In response to the air in the reactor being completely exhausted, adding deionized water into the reactor from the water inlet; wherein the temperature of the deionized water is 50-55° C.;

[0009] A second nitrogen gas is introduced into the reactor from the stirring vent, and solid urea particles of a preset purity are added into the reactor from the urea feed port; wherein the second nitrogen gas is compressed nitrogen gas, and the temperature of the second nitrogen gas is 60-55° C.;

[0010] In response to the completion of the addition of the solid urea particles, all the connecting holes of the reactor except the stirring vent and the exhaust port are closed, and the introduction speed of the second nitrogen gas is controlled to increase the pressure in the reactor to a preset pressure; wherein the second nitrogen gas pneumatically stirs the reaction zone to accelerate the dissolution of the solid urea particles in the reaction zone into the deionized water;

[0011] In response to the solid urea particles being completely dissolved, the stirring blades are controlled to rotate, and the liquids in the reaction zone and the mixing zone are mixed to make the urea evenly distributed, thereby obtaining a diesel exhaust treatment liquid.

[0012] Optionally, controlling the second nitrogen introduction rate to increase the pressure in the reactor to a preset pressure includes:

[0013] Controlling the second nitrogen to be passed into the reactor at a first ventilation speed, ensuring that the first ventilation speed is greater than the exhaust speed of the exhaust port, so that the pressure in the reactor is increased to accelerate the dissolution of the solid urea particles;

[0014] In response to the pressure in the reactor reaching the preset pressure, the introduction speed of the second nitrogen gas is controlled to be slowed down to a second ventilation speed, ensuring that the second ventilation speed is the same as the exhaust speed of the exhaust port to maintain the preset pressure in the reactor.

[0015] Optionally, after obtaining the diesel exhaust treatment fluid, the process further comprises:

[0016] The diesel exhaust treatment liquid is treated with a suspended matter prevention and removal agent, wherein the organic acid ligand of the suspended matter prevention and removal agent forms a stable water-soluble complex with the metal impurity ions in the diesel exhaust treatment liquid, thereby reducing the effective concentration of metal ions in the diesel exhaust treatment liquid and avoiding the formation of metal hydroxide precipitation.

[0017] Optionally, the suspended matter prevention and removal agent includes one or more of ethylenediaminetetraacetic acid and its ammonium salt, catechol-3,5-disulfonic acid and its ammonium salt, gallic acid and its ammonium salt, tannic acid and its ammonium salt.

[0018] Optionally, after obtaining the diesel exhaust treatment fluid, the process further comprises:

[0019] The diesel exhaust treatment liquid is treated with an anti-precipitation and polymerization inhibitor, which has strong dispersibility and adsorption properties and blocks the aggregation growth and precipitation of nano-scale metal hydroxides in the diesel exhaust treatment liquid.

[0020] Optionally, the anti-precipitation and polymerization inhibitor includes one or more of ethylene glycol, glycerol, polyethylene glycol, polyvinyl alcohol, carboxymethyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose.

[0021] Optionally, after obtaining the diesel exhaust treatment fluid, the process further comprises:

[0022] Performing coarse filtration on the diesel exhaust treatment fluid to remove mechanical impurities in the diesel exhaust treatment fluid;

[0023] The diesel exhaust treatment liquid is finely filtered to remove coarse filtration residues and metal hydroxide aggregates in the diesel exhaust treatment liquid.

[0024] Optionally, the stirring blade is located above the stirring vent, and the stirring blade is slender to reduce the obstruction of the stirring vent, avoid affecting the pneumatic stirring efficiency and affecting the mixing zone.

[0025] Optionally, the mass ratio of the deionized water to the solid urea particles is 67.5:32.5.

[0026] Beneficial effects of the present invention: 1. The present invention sets a reaction zone and a mixing zone in the reactor, the reaction zone is in the center, the mixing zone is outside the reaction zone and one side is the inner wall of the reactor, and the urea feed port is arranged above the reaction zone. The reaction zone is stirred by introducing a second nitrogen gas to dissolve the solid urea particles in the reaction zone. In this way, the urea concentration in the mixing zone is reduced while ensuring the normal dissolution of the solid urea particles, thereby avoiding the excessive hydrolysis of the urea concentration in the mixing zone to corrode the inner wall of the reactor to produce metal ions, thereby avoiding the generation of metal ions at the source and reducing the metal hydroxide suspension and sediment in the finished diesel exhaust treatment liquid. The present invention dissolves in the central area inside the reactor and reduces the dissolution outside the central area, thereby avoiding the corrosion of the inner wall of the reactor due to contact with the solution of excessive hydrolysis of urea concentration to produce metal ions. 2. Before dissolving the solid urea particles, the present invention performs exhaust treatment on the reactor, and uses nitrogen to remove air to avoid the impurity particles suspended in the air from mixing into the solid urea particles when they are dissolved, and then dissolving to produce metal ions. 3. The present invention adopts a pneumatic stirring method, which can increase the pressure during the stirring process, so that the pressure in the reactor increases, the solubility of the solid urea particles increases, and then the dissolution efficiency is accelerated, the residence time of the solution in the reactor is reduced, and excessive hydrolysis and corrosion of the reactor due to excessive residence time are avoided. 4. The present invention adopts solid urea particles and deionized water of preset purity to avoid the metal ions produced by the dissolution of too many impurities in the raw materials. 5. When obtaining the diesel exhaust treatment liquid, the present invention further avoids the generation of suspended matter or sediment in the finished diesel exhaust treatment liquid by using suspended matter prevention removal agents, anti-settling inhibitors and multi-stage filtration. In summary, the present invention prevents metal ions from entering the diesel exhaust treatment liquid and generating suspended matter or sediment from the source by placing the urea solution in the central area of ​​the reactor, exhausting the air with nitrogen, and pressurizing. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic flow chart of a production process for preventing diesel exhaust treatment fluid from generating flocculent suspended matter or sediment, provided by a specific embodiment of the present invention;

[0028] Figure 2 It is a structural schematic diagram of a production device for preventing diesel exhaust treatment fluid from generating flocculent suspended matter or sediment, provided by a specific embodiment of the present invention. DETAILED DESCRIPTION

[0029] The present invention discloses a production process for avoiding the generation of flocculent suspended matter or sediment in diesel exhaust treatment fluid. Those skilled in the art can refer to the content of this article and appropriately improve the technical details for implementation. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art, and they are all considered to be included in the present invention. The method and application of the present invention have been described through preferred embodiments, and relevant personnel can obviously modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention.

[0030] The applicant has found that excessive metal ions in diesel exhaust treatment fluid will combine with hydroxide to form metal hydroxides and then aggregate and precipitate. There are generally three sources of metal ions. First, the purity of the raw materials (generally deionized water and solid urea particles) is not high and is doped with impurities; second, impurity particles suspended in the air; third, the diesel exhaust treatment fluid is prone to hydrolysis during the preparation process, and the intermediate products of hydrolysis (some amines, such as methylamine) and the final product (ammonia) will corrode the metal reactor and produce metal ions. Metals are also commonly used materials for diesel exhaust treatment fluid reactors. The existing technology usually produces diesel exhaust treatment fluid by filtering or treating suspended matter and sediments in the diesel exhaust treatment fluid in the form of post-compensation. Since the aggregation and generation time of metal hydroxides is relatively long, such a treatment method will still generate suspended matter and sediments when the diesel exhaust treatment fluid is left standing after leaving the factory, and the effect is not very ideal.

[0031] Therefore, the embodiment of the present invention provides a production process for preventing diesel exhaust treatment fluid from generating flocculent suspended matter or sediment, which is applied to a metal reactor 201, such as Figure 2As shown, the central area within the preset range of the reactor 201 is the reaction zone 202, and the reaction zone 202 is surrounded by the mixing zone 203. The bottom of the reactor corresponding to the reaction zone 202 is provided with an array of stirring vents 204, and the center of the bottom of the reactor 201 is provided with a stirring blade 205, and the length of the stirring blade 205 covers the reaction zone 202 and the mixing zone 203. The top of the reactor is also provided with a water inlet 207, an exhaust port 208, and a urea feed port 206 opposite to the reaction zone. Figure 1 As shown, the process includes:

[0032] Step S101: introducing a first nitrogen gas into the reactor from the stirring vent hole to discharge the air in the reactor and reduce the impurities suspended in the reactor.

[0033] The first nitrogen is high-purity nitrogen, which is nitrogen with impurity content that meets the standard after ordinary nitrogen is impurity-removed. After the air is introduced and exhausted, no new impurities will be introduced into the urea dissolution.

[0034] It should be noted that the reaction zone and the mixing zone are not two areas separated by a real isolation plate, but two areas of the reactor divided by a virtual boundary.

[0035] In a specific embodiment, the nitrogen can be discharged from the exhaust port, or can be discharged from the exhaust port, the water inlet, and the urea feed port.

[0036] Step S102: in response to the air in the reactor being completely exhausted, deionized water is added into the reactor from the water inlet.

[0037] Wherein, the temperature of deionized water is 50-55°C.

[0038] It should be noted that the deionized water used in the embodiment of the present invention is high-purity deionized water to avoid the introduction of metal ion impurities from the raw materials. The temperature of the deionized water is 50-55°C, which can ensure the dissolution rate of the solid urea particles while preventing hydrolysis after dissolution due to excessive temperature. The dissolution of solid urea in water is heat-absorbing, and a certain temperature is required to ensure its dissolution rate.

[0039] Step S103: introducing a second nitrogen gas into the reactor from the stirring vent hole, and adding solid urea particles of a preset purity into the reactor from the urea feed port.

[0040] The second nitrogen is compressed nitrogen, and the temperature of the second nitrogen is 60-55°C.

[0041] It should be noted that the second nitrogen is compressed nitrogen, which can release pressure and heat after entering the solution. In addition, the temperature of the second nitrogen itself is higher than that of deionized water, which can heat the reactor and accelerate the dissolution rate of solid urea particles.

[0042] In the specific application process, when adding the corresponding material, open the connecting port of the corresponding material and close the other connecting ports to prevent air from entering the reactor again.

[0043] Optionally, the solid urea granules are high-purity solid urea granules, generally with a purity higher than 98.5%, so as to avoid the introduction of impurities from the raw materials to generate metal ions.

[0044] Step S104: in response to the completion of the addition of the solid urea particles, all the connecting holes of the reactor except the stirring vent and the exhaust port are closed, and the introduction speed of the second nitrogen is controlled to increase the pressure in the reactor to a preset pressure.

[0045] The second nitrogen gas pneumatically stirs the reaction zone to accelerate the dissolution of solid urea particles in the reaction zone into deionized water.

[0046] It should be noted that the preset pressure is greater than the atmospheric pressure. Increasing the pressure can increase the solubility of urea and accelerate the dissolution of urea, thereby avoiding the urea dissolution time being too long, resulting in hydrolysis and corrosion of the reactor.

[0047] Optionally, controlling the second nitrogen introduction rate to raise the pressure in the reactor to a preset pressure includes:

[0048] Controlling the second nitrogen to be introduced into the reactor at a first ventilation speed, ensuring that the first ventilation speed is greater than the exhaust speed of the exhaust port, so that the pressure in the reactor is increased to accelerate the dissolution of the solid urea particles;

[0049] In response to the pressure in the reactor reaching a preset pressure, the introduction speed of the second nitrogen gas is controlled to be slowed down to a second ventilation speed, ensuring that the second ventilation speed is the same as the exhaust speed of the exhaust port to maintain the preset pressure in the reactor.

[0050] It should be noted that the embodiment of the present invention achieves the effect of pressurization through the speed ratio of nitrogen introduction and discharge on the basis of pneumatic stirring, which can not only easily realize pressure control, but also achieve multiple purposes (stirring and pressurization) in one go. In this embodiment, the first ventilation speed is greater than the exhaust speed of the exhaust port in the front time, so that the pressure in the reactor is increased; the introduction speed of the second nitrogen is slowed down to the second ventilation speed in the back time, ensuring that the second ventilation speed is the same as the exhaust speed of the exhaust port to maintain the preset pressure in the reactor. The method of pressurization in the front and voltage stabilization in the back realizes accelerated dissolution, and ensures that the pressure in the reactor is constant without causing damage to the reactor.

[0051] Step S105: In response to the solid urea particles being completely dissolved, the stirring blades are controlled to rotate, and the liquids in the mixing zone and the mixing zone are mixed to make the urea evenly distributed, thereby obtaining a diesel exhaust treatment liquid.

[0052] It should be noted that the stirring range of the stirring vent is limited to the reaction zone, and the entrance of the solid urea particles is above the reaction zone, so that the urea dissolved in the reaction zone can be much larger than that in the mixing zone, and the mixing zone is in a low urea concentration state during most of the time of urea dissolution, reducing the urea hydrolysis corrosion reactor to produce metal ions. The stirring range of the stirring blade covers the reaction zone and the mixing zone. After the solid urea particles are completely dissolved in the reaction zone, the stirring blade is started to stir the reaction zone and the mixing zone, so that the urea is evenly distributed in the solution to generate a diesel exhaust treatment liquid. In this way, the contact time between the high-concentration urea solution and the inner wall of the reactor can be reduced, and the urea solution can be evenly mixed.

[0053] In a specific embodiment, after obtaining the diesel exhaust treatment fluid, the process further comprises:

[0054] The diesel exhaust treatment fluid is treated with a suspended solids prevention and removal agent. The organic acid ligand of the suspended solids prevention and removal agent forms a stable water-soluble complex with the metal impurity ions in the diesel exhaust treatment fluid, thereby reducing the effective concentration of metal ions in the diesel exhaust treatment fluid and avoiding the formation of metal hydroxide precipitation.

[0055] Furthermore, the suspended matter prevention and removal agent includes one or more of ethylenediaminetetraacetic acid and its ammonium salt, catechol-3,5-disulfonic acid and its ammonium salt, gallic acid and its ammonium salt, tannic acid and its ammonium salt.

[0056] It should be noted that this embodiment is used to further remove suspended matter or sediment. The organic acid ligand forms a stable water-soluble complex with the metal impurity ions to prevent the metal ions from combining with hydroxide to produce precipitation.

[0057] In a specific embodiment, after obtaining the diesel exhaust treatment fluid, the process further comprises:

[0058] The diesel exhaust treatment fluid is treated with an anti-precipitation and polymerization inhibitor, which has strong dispersibility and adsorption properties and blocks the aggregation and growth of nano-scale metal hydroxides in the diesel exhaust treatment fluid and then precipitates.

[0059] Furthermore, the anti-settling and polymerization inhibitor includes one or more of ethylene glycol, glycerol, polyethylene glycol, polyvinyl alcohol, carboxymethyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose.

[0060] It should be noted that this embodiment is used to further remove suspended matter or sediment by blocking the aggregation of nano-sized metal hydroxides in the diesel exhaust treatment fluid to form precipitates or suspended matter.

[0061] In a specific embodiment, after obtaining the diesel exhaust treatment fluid, the process further comprises:

[0062] Coarsely filter the diesel exhaust treatment fluid to remove mechanical impurities in the diesel exhaust treatment fluid;

[0063] The diesel exhaust treatment fluid is finely filtered to remove coarse filtration residues and metal hydroxide aggregates in the diesel exhaust treatment fluid.

[0064] Multiple filtrations can further remove impurities, including but not limited to mechanical impurities and metal hydroxide aggregates.

[0065] Optionally, the stirring blade is located above the stirring vent, and the stirring blade is slender to reduce the obstruction of the stirring vent, avoid affecting the pneumatic stirring efficiency and affecting the mixing zone.

[0066] Optionally, the mass ratio of deionized water to solid urea particles is 67.5:32.5, which is the standard ratio of diesel exhaust treatment fluid.

[0067] In the embodiment of the present invention, a reaction zone and a mixing zone are arranged in the reactor, the reaction zone is in the center, the mixing zone is outside the reaction zone and one side is the inner wall of the reactor, and the urea feed port is arranged above the reaction zone. The reaction zone is stirred by introducing a second nitrogen gas so that the solid urea particles are dissolved in the reaction zone. In this way, the urea concentration in the mixing zone is reduced while ensuring the normal dissolution of the solid urea particles, thereby avoiding the urea concentration in the mixing zone from being too high and hydrolyzed too much to corrode the inner wall of the reactor to produce metal ions, thereby avoiding the generation of metal ions at the source and reducing the metal hydroxide suspension and sediment in the finished diesel exhaust treatment liquid. In the embodiment of the present invention, the inner wall of the reactor is prevented from being corroded by the solution of the excessively high urea concentration and hydrolysis by dissolving in the central area inside the reactor and reducing the dissolution outside the central area, thereby avoiding the generation of metal ions by contacting the inner wall of the reactor with the solution of the excessively high urea concentration and hydrolysis. In the embodiment of the present invention, the reactor is exhaust-treated before dissolving the solid urea particles, and the air is removed by nitrogen to avoid the impurity particles suspended in the air from mixing into the solid urea particles when they are dissolved, thereby dissolving and producing metal ions. The embodiment of the present invention adopts a pneumatic stirring method, which can be pressurized during the stirring process, so that the pressure in the reactor increases, the solubility of the solid urea particles increases, and then the dissolution efficiency is accelerated, the residence time of the solution in the reactor is reduced, and the excessive hydrolysis and corrosion of the reactor due to excessive residence time is avoided. The embodiment of the present invention uses solid urea particles and deionized water of preset purity to avoid the metal ions produced by the dissolution of too many impurities in the raw materials. In the diesel exhaust treatment liquid obtained by the embodiment of the present invention, the suspended matter prevention removal agent, anti-settling inhibitor and multi-stage filtration are further used to avoid the generation of suspended matter or sediment in the finished diesel exhaust treatment liquid. In summary, the embodiment of the present invention prevents metal ions from entering the diesel exhaust treatment liquid from the source to generate suspended matter or sediment by placing the urea solution in the central area of ​​the reactor, exhausting the air with nitrogen, and pressurizing.

[0068] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0069] Each embodiment in this specification is described in a related manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0070] The above are only preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A production process for preventing diesel exhaust treatment fluid from generating flocculent suspended matter or sediment, characterized in that: A reactor made of metal material is applied, wherein the central area within a preset range of the reactor is a reaction zone, and the reaction zone is surrounded by a mixing zone. The bottom of the reactor corresponding to the reaction zone is provided with stirring vents arranged in an array, and a stirring blade is provided at the center of the bottom of the reactor. The length of the stirring blade covers the reaction zone and the mixing zone. A water inlet, an exhaust port, and a urea feed port opposite to the reaction zone are also provided above the reactor. The process comprises: Introducing a first nitrogen gas into the reactor from the stirring vent hole to discharge the air in the reactor and reduce the impurities suspended in the reactor; In response to the air in the reactor being completely exhausted, adding deionized water into the reactor from the water inlet; wherein the temperature of the deionized water is 50-55° C.; A second nitrogen gas is introduced into the reactor from the stirring vent, and solid urea particles of a preset purity are added into the reactor from the urea feed port; wherein the second nitrogen gas is compressed nitrogen gas, and the temperature of the second nitrogen gas is 60-55° C.; In response to the completion of the addition of the solid urea particles, all the connecting holes of the reactor except the stirring vent and the exhaust port are closed, and the introduction speed of the second nitrogen gas is controlled to increase the pressure in the reactor to a preset pressure; wherein the second nitrogen gas pneumatically stirs the reaction zone to accelerate the dissolution of the solid urea particles in the reaction zone into the deionized water; In response to the solid urea particles being completely dissolved, controlling the stirring blades to rotate, mixing the liquids in the reaction zone and the mixing zone so that the urea is evenly distributed, and obtaining a diesel exhaust treatment liquid; Wherein, controlling the second nitrogen introduction rate to increase the pressure in the reactor to a preset pressure includes: Controlling the second nitrogen to be passed into the reactor at a first ventilation speed, ensuring that the first ventilation speed is greater than the exhaust speed of the exhaust port, so that the pressure in the reactor is increased to accelerate the dissolution of the solid urea particles; In response to the pressure in the reactor reaching the preset pressure, the introduction speed of the second nitrogen gas is controlled to be slowed down to a second ventilation speed, ensuring that the second ventilation speed is the same as the exhaust speed of the exhaust port to maintain the preset pressure in the reactor.

2. The production process for preventing diesel exhaust treatment fluid from generating flocculent suspended matter or sediment according to claim 1, characterized in that: After obtaining the diesel exhaust treatment fluid, the process further comprises: The diesel exhaust treatment liquid is treated with a suspended matter prevention and removal agent, wherein the organic acid ligand of the suspended matter prevention and removal agent forms a stable water-soluble complex with the metal impurity ions in the diesel exhaust treatment liquid, thereby reducing the effective concentration of metal ions in the diesel exhaust treatment liquid and avoiding the formation of metal hydroxide precipitation.

3. The production process for preventing diesel exhaust treatment fluid from generating flocculent suspended matter or sediment according to claim 2, characterized in that: The suspended matter prevention and removal agent includes one or more of ethylenediaminetetraacetic acid and its ammonium salt, catechol-3,5-disulfonic acid and its ammonium salt, gallic acid and its ammonium salt, tannic acid and its ammonium salt.

4. The production process for preventing diesel exhaust treatment fluid from generating flocculent suspended matter or sediment according to claim 1, characterized in that: After obtaining the diesel exhaust treatment fluid, the process further comprises: The diesel exhaust treatment liquid is treated with an anti-precipitation and polymerization inhibitor, which has strong dispersibility and adsorption properties and blocks the aggregation growth and precipitation of nano-scale metal hydroxides in the diesel exhaust treatment liquid.

5. The production process for preventing diesel exhaust treatment fluid from generating flocculent suspended matter or sediment according to claim 4, characterized in that: The anti-precipitation and polymerization inhibitor includes one or more of ethylene glycol, glycerol, polyethylene glycol, polyvinyl alcohol, carboxymethyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose.

6. The production process for preventing diesel exhaust treatment fluid from generating flocculent suspended matter or sediment according to claim 1, characterized in that: After obtaining the diesel exhaust treatment fluid, the process further comprises: Performing coarse filtration on the diesel exhaust treatment fluid to remove mechanical impurities in the diesel exhaust treatment fluid; The diesel exhaust treatment liquid is finely filtered to remove coarse filtration residues and metal hydroxide aggregates in the diesel exhaust treatment liquid.

7. The production process for preventing diesel exhaust treatment fluid from generating flocculent suspended matter or sediment according to claim 1, characterized in that: The stirring blade is located above the stirring vent hole, and the stirring blade is slender to reduce the obstruction of the stirring vent hole, avoid affecting the pneumatic stirring efficiency and affecting the mixing zone.

8. The production process for preventing diesel exhaust treatment fluid from generating flocculent suspended matter or sediment according to claim 1, characterized in that: The mass ratio of the deionized water to the solid urea particles is 67.5:32.5.

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