Raw material pre-dissolving device

Abstract

The invention provides a raw material pre-dissolving device, which comprises: a tank body, the top of the tank body is provided with an inlet, and the bottom of the tank body is provided with an outlet; the stirring device is arranged in the tank body; the flow guide cover is of a circular truncated cone structure and comprises a top face and a bottom face, the flow guide cover is arranged in the tank body, the top face is close to the top of the tank body, and the diameter of the top face is smaller than that of the bottom face. The flow guide cover is arranged in the raw material pre-dissolving device, liquid in the pre-dissolving tank can collide with the flow guide cover after rotating, the flow guide cover generates acting force in the opposite direction on the liquid, the liquid on the upper portion in the pre-dissolving tank flows downwards, the liquid on the edge in the tank and the liquid in the middle are further fully stirred, and mixing is more uniform.

Description

Technical Field

[0001] The invention relates to a raw material pre-dissolving device, belonging to the technical field of pre-treatment equipment. Background Art

[0002] Polyolefin elastomer, referred to as POE, refers to a random copolymer elastomer of ethylene and high carbon α-olefins polymerized by metallocene catalysts. The elastomer has a certain degree of crystallinity, a narrow relative molecular weight, and a low density. POE usually refers to ethylene-octene copolymer elastomer with an octene mass fraction greater than 20%. It has good compatibility with polyolefins and high cost performance, so it is widely used in automobiles, footwear, wires and cables, packaging, polymer modification, medical and other fields.

[0003] In 2018, the global POE production exceeded 1Mt. However, only a few companies in the world currently have complete processes and their own proprietary catalysts to produce POE, including Dow Chemical and ExxonMobil in the United States, Mitsui Chemicals in Japan, LG Chem and SK Chem in South Korea.

[0004] In polyolefin elastomers, the crystalline region (resin phase) of the polyethylene chain segment acts as a physical cross-linking point and has certain plastic properties. Adding a certain amount of α-olefin (1-butene, 1-hexene, 1-octene) weakens the crystalline region of the polyethylene chain segment.

[0005] In the small or pilot test of the polymerization reaction of producing POE by the olefin solution method, the raw materials need to be pre-dissolved before the polymerization reaction to increase the amount of ethylene dissolved in the α-olefin solution. When the mixed solution enters the reactor for polymerization reaction, the insertion rate of the comonomer in the ethylene chain segment is increased, and the catalytic efficiency is increased. This method can significantly improve the quality of the product. The increase in the comonomer insertion rate can increase the rubber phase in the product and make the product have excellent tensile properties.

[0006] Under normal experimental conditions, the solution blending device also serves as a raw material storage tank. A stirring paddle with variable rotation speed is set inside the tank to increase the amount of ethylene dissolved through stirring. The ethylene dissolution effect of this pre-dissolution tank is average. Strengthening the pre-dissolution effect in a single way such as stirring only increases the amount of ethylene dissolved slightly, which quickly reaches the threshold. Therefore, optimizing the design of the pre-mixing device is an important part of the production of polyolefin elastomers.

[0007] CN 212758175 U discloses a chemical solution premixing stirring tank, comprising a stirring tank mechanism, a stirring ruler mechanism, and a discharge mechanism, wherein the top of the stirring tank mechanism is fixedly connected to the bottom of the power mechanism. The connecting block can rotate forty-five degrees, so that the fan blades can contact the stirring range of the fan blades in a large area during the stirring of the chemical solution, thereby accelerating the rapid fusion of the chemical solution. The raw materials enter from the feed inlet, and the inside of the tank body is sealed, so that the chemical solution will not be splashed outside during the stirring and fusion of the chemical solution. The stirring and discharging valve functions to discharge the fused solution from the tank through the stirring and discharging valve, and the fertilizer residue is discharged through the waste material discharge valve after precipitation, so as to effectively separate and discharge the fusion product from the precipitate. The utility model patent design optimizes the design of the stirring paddle, so that the contact area with the solution during the stirring process is larger, but the solubility of the raw material under the action of the stirring paddle is still limited, and the dissolution amount cannot be further increased.

[0008] CN 214389973 U discloses a whitening agent dissolving device, comprising a tank body, a pre-dissolving cylinder, a feeding mechanism and a stirring mechanism, wherein the pre-dissolving cylinder is arranged at the top of the tank body, the side wall of the pre-dissolving cylinder is provided with a plurality of overflow holes, the top of the tank body is provided with a feeding port, the feeding port is communicated with the top of the pre-dissolving cylinder, the feeding mechanism comprises a feeding hopper, a blocking plate and a driving assembly, the feeding hopper is arranged at the feeding port at the top of the tank body, the blocking plate is slidably connected to the feeding port, the driving assembly can drive the blocking plate to reciprocate in the horizontal direction, and the reciprocating motion of the blocking plate can realize the closing and opening of the feeding port. The utility model has the effect of improving the uniformity of whitening agent dissolution. However, if used for pre-dissolving gas raw materials, the effect needs to be improved.

[0009] Therefore, further research on raw material pre-dissolving devices is still needed in this field. Summary of the invention

[0010] The main purpose of the present invention is to provide a raw material pre-dissolving device to overcome the problem of poor pre-dissolving effect in the prior art.

[0011] In order to achieve the above object, the present invention provides a raw material pre-dissolving device, comprising:

[0012] A tank body, wherein the top of the tank body is provided with an inlet, and the bottom of the tank body is provided with an outlet;

[0013] A stirring device is arranged in the tank;

[0014] The deflector is a truncated cone structure, including a top surface and a bottom surface. The deflector is arranged inside the tank body, and the top surface is close to the top of the tank body. The diameter of the top surface is smaller than the diameter of the bottom surface.

[0015] The raw material pre-dissolving device described in the present invention, wherein the stirring device includes a stirring shaft and at least one stirring paddle, the stirring shaft extends from the top of the tank body into the interior of the tank body, a cavity is provided inside the stirring shaft, and the gas raw material enters the tank body through the cavity; and / or the diameter of the cavity is 7 to 12 mm.

[0016] The raw material pre-dissolving device of the present invention, wherein the stirring shaft is provided with a plurality of air holes which are respectively connected to the cavities, and the gaseous raw material enters the tank body through the air holes.

[0017] The raw material pre-dissolving device described in the present invention, wherein a hollow structure is arranged inside the stirring paddle, a plurality of holes are distributed on the stirring paddle, and the hollow structure is connected to the cavity.

[0018] The raw material pre-dissolving device described in the present invention, wherein the number of the stirring paddles is 2, including a first stirring paddle and a second stirring paddle, which are arranged up and down on the stirring shaft.

[0019] The raw material pre-dissolving device described in the present invention, wherein the first stirring paddle is a single-layer paddle-type stirring paddle, including blades, keys, shaft rings and vertical shafts, the diameter of the first stirring paddle is 1 / 3 to 2 / 3 of the diameter of the tank body, the number of the blades is 2, and the blades are folding-blade type; the second stirring paddle is a single-layer rotary paddle-type stirring paddle, including blades, keys, shaft rings and vertical shafts, the diameter of the second stirring paddle is 1 / 3 to 2 / 3 of the diameter of the tank body, the number of the blades is two, and the blades are inclined-blade type.

[0020] The raw material pre-dissolving device of the present invention is characterized in that a heat exchange jacket is arranged outside the tank body, a liquid inlet is arranged at the lower part of the heat exchange jacket, and a liquid outlet is arranged at the upper part.

[0021] The raw material pre-dissolving device of the present invention, wherein the inlet includes a solvent inlet and a liquid raw material inlet, and the outlet includes a pre-solution outlet and a liquid discharge outlet.

[0022] The raw material pre-dissolving device described in the present invention further includes a thermocouple and a thermocouple sleeve, wherein the thermocouple is arranged in the tank body and extends to the middle and lower part of the tank body, and the thermocouple sleeve is arranged outside the thermocouple.

[0023] The raw material pre-dissolving device described in the present invention, wherein the ratio of the diameter of the top surface of the guide cover to the diameter of the tank body is 1:2-4, and the ratio of the diameter of the bottom surface to the diameter of the tank body is 1:1.5-2.

[0024] Beneficial effects of the present invention:

[0025] The raw material pre-dissolving device of the present invention is provided with a flow guide cover, which can make the liquid in the pre-dissolving tank rotate and collide with the flow guide cover. The flow guide cover exerts a force in the opposite direction on the liquid, so that the liquid in the upper part of the pre-dissolving tank flows downward, and the liquid at the edge of the tank and the liquid in the middle are further fully stirred and mixed more evenly, so that the dissolution amount of ethylene can be increased, and then the insertion rate of ethylene can be increased. The high content of ethylene monomer insertion rate can improve the catalyst reaction efficiency and obtain high-quality products. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a cross-sectional schematic diagram of a raw material pre-dissolving device according to one embodiment of the present invention.

[0027] Wherein, the reference numerals are:

[0028] 1. Stirring device

[0029] 2 Spare ports

[0030] 3 Gas inlet

[0031] 4 Solvent inlet

[0032] 5 Spare port

[0033] 6 Air deflector

[0034] 7 Thermocouple wells

[0035] 8. Stirring shaft

[0036] 9 First stirring paddle

[0037] 10 Second stirring paddle

[0038] 11 Heat exchange jacket

[0039] 12 Pre-solution outlet

[0040] 13 drain port

[0041] 14 Liquid inlet

[0042] 15 liquid outlet

[0043] 16 Tank DETAILED DESCRIPTION

[0044] The technical scheme of the present invention is described in detail below. The following implementation modes are implemented on the premise of the technical scheme of the present invention, and a detailed implementation process is given. However, the protection scope of the present invention is not limited to the following implementation modes. The structures or experimental methods of specific conditions are not specified in the following implementation modes, and generally conventional conditions are followed.

[0045] The present invention provides a raw material pre-dissolving device, which is used for pre-mixing raw materials, and is particularly suitable for pre-dissolving gas raw materials and liquid raw materials, such as Figure 1 As shown, it includes a tank body 16, a stirring device 1 and a flow guide cover 6.

[0046] In the present invention, the top of the tank body 16 is provided with an inlet, and the bottom is provided with an outlet. The present invention does not particularly limit the shape of the tank body 16, for example, it is a cylindrical tank body, the material is, for example, high temperature resistant stainless steel, and can be made of SUS304 or SUS310L material, with a volume of 10000-50000ml, preferably 40000ml, and a pressure of 2-5MPa, preferably 3MPa, and a sanitary mechanical seal is used for sealing. In one embodiment, the wall thickness of the tank body 16 is 12-30mm, preferably 15mm, and the height of the tank body 16 is 1000-2500mm, preferably 1500mm. The aspect ratio of the tank body 16 is 5-12.5, preferably 8, and the aspect ratio of the tank body 16 refers to the ratio of the height of the tank body to the diameter of the cross-sectional area of ​​the tank body. In another embodiment, the maximum thickness of the tank body 16 is designed to be 4.37 mm, the minimum thickness is 2 mm, the inner diameter of the tank body 16 is designed to be 1000-1100 mm, the maximum pressure to be able to withstand the tank body is designed to be 4 MPa, and the maximum temperature to be able to withstand is 100°C. The tank body lining is subjected to high-precision polishing treatment to reduce its surface roughness, and the polishing degree is 0.4-0.6 μm, preferably 0.5 μm.

[0047] In the present invention, an inlet is provided at the top of the tank body 16. In one embodiment, a gas inlet 3 and a solvent inlet 4 are provided at the top of the tank body 16. In addition, a spare port 2 and a spare port 5 may be provided at the top of the tank body 16. The spare port 5 may be used as an inlet for liquid raw materials. The gas inlet 3 may be used for the inlet of pressurized gas during the pre-dissolution process, such as nitrogen, and the spare port 2 and the spare port 5 may be used for the inlet of other liquid raw materials or solvents during the pre-dissolution process. The inner diameter of the gas inlet 3 is, for example, 3 to 5 mm, preferably 4 mm, and the inner diameter of the solvent inlet 4 is 10 to 15 mm, preferably 13 mm-15 mm. An outlet is provided at the bottom of the tank body 16. In one embodiment, a pre-solution outlet 12 and a drain port 13 are provided at the bottom of the tank body 16. The pre-solution outlet 12 is, for example, controlled by a 1 / 4 ball valve for discharging the obtained pre-solution; the inner diameter of the drain port 13 is, for example, 40 to 50 mm, preferably 45 mm, for emergency discharge or cleaning of residual materials.

[0048] In the present invention, the stirring device 1 is arranged in the tank body 16, and is used to stir the pre-dissolved mixture to promote the mixing of the pre-dissolved raw materials. In one embodiment, the stirring device 1 of the present invention includes a stirring shaft 8 and at least one stirring paddle, and the stirring shaft 8 extends from the top of the tank body 16 into the interior of the tank body 16 until one end of the stirring shaft 8 is close to the bottom of the tank body 16, and the end of the stirring shaft 8 close to the bottom of the tank body 16 is connected to the stirring paddle, and the other end of the stirring shaft 8 is connected to the power device to drive the stirring shaft 8 to rotate. The power device is, for example, a stirring motor, more specifically, a three-phase AC induction motor, using a variable frequency stirring stirring form, a maximum speed of 2000r / min, a minimum speed of 200r / min, and a power of 300W. The length of the stirring shaft 8 can be 700mm~2000mm, and the diameter of the stirring shaft 8 can be 10~15mm.

[0049] In one embodiment, the number of stirring paddles of the present invention is 2, namely, the first stirring paddle 9 and the second stirring paddle 10, which are arranged up and down on the stirring shaft 8. In another embodiment, the first stirring paddle 9 of the present invention is a single-layer paddle stirring paddle, including a blade, a key, a shaft ring and a vertical shaft, the diameter of the first stirring paddle 9 is 1 / 3 to 2 / 3 of the diameter of the tank body 16, the number of blades is 2, the blades are folding blades, θ = 45°, the dimensions are d / D = 0.4 to 0.9, b / d = 0.2 to 0.3, Bn = 2, the operating conditions are: n = 100 r / min to 600 r / min, v = 1 to 6 m / s, and the viscosity range of the commonly used medium is: 0 to 40 Pa / s. The second stirring paddle 10 of the present invention is a single-layer propeller stirring paddle, including a blade, a key, a shaft ring and a vertical shaft. The diameter of the second stirring paddle 10 is 1 / 3 to 2 / 3 of the diameter of the tank body 16. The number of blades is two, and the blades are inclined blades, θ = 45°, and the dimensions are d / D = 0.4 to 0.9, b / d = 0.2 to 0.3, Bn = 2. The operating conditions are: n = 100r / min to 600r / min, v = 1 to 6m / s, and the viscosity range of the commonly used medium is: 0 to 40Pa / s. The circumferential speed of the outer edge of the blade is generally 5 to 15m / s, which mainly causes axial liquid flow and produces a large circulation volume. Among them, n-rotation speed; v-blade line end speed; Bn-number of blades; d-diameter of stirring paddle; D-inner diameter of tank body; θ-folding angle; b-blade thickness.

[0050] In one embodiment, the stirring shaft 8 of the present invention is provided with a cavity inside, and the gas raw material enters the tank body 16 through the cavity. In another embodiment, the stirring shaft 8 is provided with a cavity inside, and the stirring paddle is provided with a hollow structure inside, the cavity of the stirring shaft 8 and the hollow structure of the stirring paddle are connected, and the gas raw material enters the tank body 16 through the cavity and the hollow structure, and the gas raw material is ensured to enter the tank body at a certain flow rate by external pressure. The diameter of the cavity and the hollow structure is, for example, 7 to 12 mm, preferably 8 mm, and the length of the cavity is, for example, 3 / 4 of the length of the stirring shaft 8.

[0051] In another embodiment, a plurality of pores are distributed on the stirring shaft 8, which are respectively connected to the cavity, and the gas raw material enters the tank body 16 through the pores. In another embodiment, a plurality of holes are distributed on the stirring paddle, which are connected to the hollow structure and the cavity, so that the gas raw material enters the tank body 16 through the cavity, the hollow structure and the holes in sequence. The number of holes can be 4 to 10, preferably 8, the pore diameter is 1 to 3 mm, preferably 2 mm, and the material can be stainless steel. The arrangement of the pores and holes can ensure the contact area between the gas raw material and the liquid raw material. The gas raw material is transported from the pressurized storage tank through the cavity and the hollow structure to the pores and holes. The pressure setting can ensure that the gas pressure in the gas pipeline fluctuates and is discharged from the pores and holes.

[0052] In the present invention, the deflector 6 is a truncated cone structure, including a top surface and a bottom surface. The deflector 6 is arranged inside the tank body 16, and the top surface is close to the top of the tank body 16, and the diameter of the top surface is smaller than the diameter of the bottom surface. In one embodiment, the deflector 6 of the present invention is hollow, that is, the truncated cone structure of the deflector 6 does not have an actual top surface and a bottom surface, and only includes the side surface. The stirring shaft 8 passes through the truncated cone structure from top to bottom. In another embodiment, the diameter of the top surface (or upper ring) of the deflector 6 is 200 to 240 mm, preferably 220 mm, the thickness of the deflector is 2-4 mm, preferably 3 mm, and the diameter of the bottom surface (lower ring) is about 400 to 500 mm, preferably 300 mm, and the material can be stainless steel. In one embodiment, the ratio of the diameter of the top surface of the deflector to the diameter of the tank body is 1:2 to 4, and the ratio of the diameter of the bottom surface to the diameter of the tank body is 1:1.5 to 2.

[0053] In one embodiment, a heat exchange jacket 11 is further provided outside the tank body 16 of the present invention for exchanging heat with the tank body 16. The material of the heat exchange jacket 11 may be stainless steel or ordinary carbon steel, and the jacketing method is a full jacket. The thickness of the jacket layer may be 10mm-15mm, the inner diameter of the jacket may be 1200-1500mm, preferably 1300mm, and the aspect ratio may be 4-13.5, preferably 8. The maximum pressure that the jacket can withstand is <2Mpa, and the heat transfer medium is condensate to prevent the dissolution and release of heat in the tank from causing the overall temperature to rise, and the pressure to increase to create safety hazards. The heat exchange jacket is provided with a liquid inlet 14 and a liquid outlet 15, and the condensate circulates in the jacket in a bottom-in-top-out manner, that is, the liquid inlet 14 is arranged at the lower part of the heat exchange jacket, and the liquid outlet 15 is arranged at the upper part of the heat exchange jacket, so that the heat transfer area can be increased, and the heat transfer area of ​​the jacket is 3.4m 2 ~4.5m 2 , preferably 4m 2 .

[0054] In one embodiment, the raw material pre-dissolving device of the present invention further comprises a thermocouple and a thermocouple sleeve 7, the thermocouple is arranged in the tank body 16 and extends to the middle and lower part of the tank body 16, and the thermocouple sleeve 7 is arranged outside the thermocouple. In one embodiment, the height of the thermocouple sleeve 7 of the present invention is 800mm to 2300mm, preferably 1000mm, for inserting and protecting the thermocouple, the contact of the thermocouple is arranged at the lower part of the pre-dissolving system (i.e., below the liquid surface of the pre-dissolving mixture), for detecting the temperature change of the system, and the detection range of the thermocouple is 0-100°C.

[0055] In one embodiment, the gas raw material of the present invention is ethylene, and the liquid raw material is α-olefins, such as 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, etc. The solvents are: Ⅰ: hydrocarbon non-polar solvents and halogenated alkanes (weakly electron-philic solvents): n-hexane, n-octane, cyclohexane, toluene, benzene, carbon tetrachloride, chloroform, chlorobenzene, carbon disulfide, ethylene dichloride; Ⅱ: ethers, aldehydes, ketones, esters, amides and amines (electron-donating solvents): ether, ethyl acetate, tetrahydrofuran, butyraldehyde, butanone, acetaldehyde, cyclohexanone, acetone, pyridine, dimethylformamide; Ⅲ: alcohols, phenols, nitro, sulfonic acids and carboxylic acids (strong electron-donating or strong hydrogen-bonding solvents): hexanol, n-pentanol, n-butanol, n-propanol, m-cresol, acetonitrile, ethanol, acetic acid, formic acid, methanol, phenol, water, sulfuric acid.

[0056] In one embodiment, the test conditions of the pre-dissolution process of the present invention are as follows: the pressure in the pre-dissolution tank is controlled to be 1.5-3.5 MPa, preferably 2 MPa, the temperature is 10-80°C, preferably 60°C, and the feed rate per hour is 2000ml-10000ml / h, preferably 5000ml / h.

[0057] The overall structural design of the raw material pre-dissolving device of the present invention can meet the requirement of high monomer dissolution rate (gas raw material dissolution rate) during the pre-dissolving process. At the same time, the gas raw material is transported to the inside of the pre-dissolving device through a pressurized pipeline to dissolve with the liquid raw material, which can enhance the contact area between the gas and the liquid and increase the amount of gas dissolved in the liquid phase monomer; a flow guide is arranged inside the device to make the liquid in the pre-dissolving tank rotate and collide with the flow guide, and the flow guide exerts a force in the opposite direction on the liquid, so that the liquid in the upper part of the pre-dissolving tank flows downward, and the liquid at the edge of the tank and the liquid in the middle are further fully stirred, and the mixing is more uniform.

[0058] A high monomer insertion rate can improve the catalyst reaction efficiency and obtain high-quality products. The high stability of the pre-dissolution device can significantly reduce the volatility of the reaction temperature and reaction pressure in the solution polymerization reaction system.

[0059] The operating method of the raw material pre-dissolving device of the present invention will be described below.

[0060] High-pressure nitrogen is introduced into the tank body 16 through the gas inlet 3 until the gauge pressure shows 0.5 MPa, and the vent is opened to vent. This step is repeated 3 times to replace the air in the tank body 16, and the last vent is vented until the gauge pressure shows 0 MPa. Close the gas inlet 3. Open the solvent inlet 4, and introduce the solvent. The volume flow rate is controlled by the pre-dissolution tank flow pump, and the volume flow rate value is set to 500 ml / min. At the same time, the stirring device 1 is turned on and the speed is set to 300 r / min.

[0061] After the speed of the stirring device 1 is stabilized, the liquid raw material is introduced from the liquid raw material inlet, and the gas raw material is introduced through the cavity of the stirring shaft 8. The liquid raw material, such as liquid phase butene, and the gas raw material, such as gas phase ethylene, have a volume flow ratio of 1:1, which is set to 500ml / min. At the same time, the speed of the stirring device 1 is adjusted, and the speed value is set to 500r / min. After the speed is stable, high-pressure nitrogen is introduced into the tank body 16 through the gas inlet 3, and the pressure of the pre-dissolution tank is filled to 1MPa. At the same time, the pressure of the liquid raw material storage tank is increased so that the gaseous raw material and the liquid raw material can be sprayed into the pre-dissolution tank and fully mixed, and then the gas inlet 3 is closed.

[0062] Monitor the temperature change in the pre-dissolving tank in real time. When the temperature rises, open the liquid inlet 14 and the liquid outlet 15 of the heat exchange jacket 11 to circulate the condensed medium in the heat exchange jacket outside the tank, reduce the temperature in the tank, and prevent the temperature rise in the system from causing poor pre-dissolving effect. Feed the pre-dissolving tank continuously. When the blended components in the tank fill the pre-dissolving tank, stop feeding the liquid raw materials and gas raw materials outside the tank, and open the pre-solution outlet 12 to enter the next system for polymerization reaction.

[0063] When the catalyst in the polymerization reaction system is completely consumed, the polymerization reaction ends. Close the pre-solution outlet 12, stop feeding the liquid raw material and gas raw material outside the tank, close the liquid inlet 14 and the liquid outlet 15 of the heat exchange jacket 11, and stop the circulation of the condensing medium. Close the stirring device 1, and slowly reduce the speed of the stirring shaft 8 and the stirring paddles 9 and 10 to stop. After the entire system is stable, open the drain port 13 to discharge the remaining pre-solution.

[0064] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, technicians familiar with the field may make various corresponding changes and deformations based on the present invention, but these corresponding changes and deformations should all fall within the scope of protection of the claims of the present invention.

Claims

1. A raw material pre-dissolving device, characterized in that: include: A tank body, wherein the top of the tank body is provided with an inlet, and the bottom of the tank body is provided with an outlet; A stirring device is arranged in the tank; The deflector is a truncated cone structure, including a top surface and a bottom surface. The deflector is arranged inside the tank body, and the top surface is close to the top of the tank body. The diameter of the top surface is smaller than the diameter of the bottom surface.

2. The raw material pre-dissolving device according to claim 1, characterized in that: The stirring device includes a stirring shaft and at least one stirring paddle, wherein the stirring shaft extends from the top of the tank body into the tank body, a cavity is arranged inside the stirring shaft, and the gas raw material enters the tank body through the cavity; and / or the diameter of the cavity is 7 to 12 mm.

3. The raw material pre-dissolving device according to claim 2, characterized in that: The stirring shaft is provided with a plurality of air holes which are respectively connected with the cavities, and the gas raw material enters the tank body through the air holes.

4. The raw material pre-dissolving device according to claim 3, characterized in that: A hollow structure is arranged inside the stirring paddle, a plurality of holes are distributed on the stirring paddle, and the hollow structure is communicated with the cavity.

5. The raw material pre-dissolving device according to claim 2, characterized in that: The number of the stirring paddles is 2, including a first stirring paddle and a second stirring paddle, which are arranged vertically on the stirring shaft.

6. The raw material pre-dissolving device according to claim 5, characterized in that: The first stirring paddle is a single-layer paddle stirring paddle, the diameter of the first stirring paddle is 1 / 3 to 2 / 3 of the diameter of the tank body, the number of the blades is 2, and the blades are folding blade type; the second stirring paddle is a single-layer rotary paddle stirring paddle, the diameter of the second stirring paddle is 1 / 3 to 2 / 3 of the diameter of the tank body, the number of the blades is 2, and the blades are inclined blade type.

7. The raw material pre-dissolving device according to claim 1, characterized in that: A heat exchange jacket is arranged outside the tank body, a liquid inlet is arranged at the lower part of the heat exchange jacket, and a liquid outlet is arranged at the upper part of the heat exchange jacket.

8. The raw material pre-dissolving device according to claim 1, characterized in that: The inlet includes a solvent inlet and a liquid raw material inlet, and the outlet includes a pre-solution outlet and a liquid discharge outlet.

9. The raw material pre-dissolving device according to claim 1, characterized in that: It also includes a thermocouple and a thermocouple sleeve. The thermocouple is arranged in the tank body and extends to the middle and lower part of the tank body. The thermocouple sleeve is arranged outside the thermocouple.

10. The raw material pre-dissolving device according to claim 1, characterized in that: The ratio of the diameter of the top surface of the deflector to the diameter of the tank body is 1:2-4, and the ratio of the diameter of the bottom surface to the diameter of the tank body is 1:1.5-2.

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