Gas-liquid turbulent mass transfer device and method for low temperature stripping of heat sensitive materials

Abstract

The application discloses a gas-liquid turbulent mass transfer device and method for low-temperature gas stripping purification of heat-sensitive materials. The device comprises a tower body, a liquid feeding port and a gas discharging port arranged at the top of the tower body, a liquid discharging port and a gas feeding port arranged at the bottom of the tower body, and a turbulent element arranged in the tower body. The turbulent element comprises a baffle coaxially arranged along the gravity direction, a small cyclone cavity, a large cyclone cavity and a downcomer which are sequentially communicated, a liquid seal circular groove and a plurality of connecting rib plates for fixing the liquid seal circular groove on the downcomer. A gas tangential inlet is arranged on the sidewall of the large cyclone cavity. The gas-liquid turbulent mass transfer is realized by the turbulent element. Under the premise of avoiding deterioration of the heat-sensitive materials, the volatile components in the heat-sensitive materials are removed at low cost. The liquid seal is realized at a low liquid amount by arranging the liquid seal circular groove, the residence time of the heat-sensitive materials is reduced, and the energy consumption and purification and separation cost are greatly reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical equipment, and in particular relates to a gas-liquid turbulent mass transfer device and method for low-temperature gas stripping purification of heat-sensitive materials. Background Art

[0002] Heat-sensitive materials are widely used in industrial production and daily life. Many organic monomers and intermediates, fine chemicals, pharmaceuticals, and fragrances are heat-sensitive. Removing volatile components from heat-sensitive materials is a key step in their refining production. Compared to liquid-liquid extraction, gas-liquid mass transfer via carrier gas or steam does not introduce solvents or dissolved water, making it a highly efficient drying and separation method.

[0003] However, traditional steam stripping must increase the temperature of heat-sensitive materials, and heat-sensitive materials are very likely to undergo decomposition, polymerization, oxidation and other deterioration reactions when heated, causing significant economic losses. Therefore, heating of heat-sensitive materials should be avoided in industrial production.

[0004] Currently, the primary method for removing volatile components from heat-sensitive materials is to inject low-temperature carrier gas into them to reduce the partial pressure of volatile components, thereby achieving gas stripping separation of these components. However, low temperatures slow the molecular diffusion rate of volatile components within the material, resulting in slow separation and poor separation progress. Traditionally, increasing the carrier gas injection rate into packed or plate towers has been employed to increase the gas-liquid interface area and gas-liquid turbulence, thereby compensating for the lack of gas-liquid mass transfer. However, excessive carrier gas injection results in high operating costs and excessive material volatilization losses. Summary of the Invention

[0005] Aiming at the deficiencies of low-temperature gas stripping purification of heat-sensitive materials in the prior art, the present invention proposes a gas-liquid turbulent mass transfer device and method for low-temperature gas stripping purification of heat-sensitive materials.

[0006] To achieve the above object, the technical solutions adopted by the present invention are as follows:

[0007] A first aspect of the present invention is to provide a gas-liquid turbulent mass transfer device for low-temperature gas stripping purification of heat-sensitive materials, comprising a tower body, wherein the top of the tower body is provided with a liquid feed inlet and a gas discharge inlet, and the bottom of the tower body is provided with a liquid discharge inlet and a gas feed inlet; a turbulent element is provided inside the tower body, wherein:

[0008] The turbulent element includes a baffle coaxially arranged along the gravity direction, a small cyclone cavity, a large cyclone cavity and a downcomer connected in sequence, a liquid sealing circular groove, and a plurality of connecting ribs for fixing the liquid sealing circular groove to the downcomer;

[0009] The upper side of the small cyclone cavity is fixed in the partition, and the top end thereof is higher than the upper surface of the partition;

[0010] The side wall of the large cyclone cavity is provided with a gas tangential inlet;

[0011] The bottom end of the downcomer is located in the liquid-sealed circular groove.

[0012] The present invention is further configured such that the number of the turbulence elements is one or more; when there are multiple turbulence elements, the multiple turbulence elements are arranged in series in the tower body along the direction of gravity, which can increase the number of countercurrent contact units and the gas lift purification efficiency.

[0013] The present invention is further configured such that a height difference H1 between the top of the small cyclone cavity and the upper surface of the partition is 10-20 mm.

[0014] The present invention is further configured such that the large cyclone cavity and the small cyclone cavity are both cylindrical, wherein the diameter of the large cyclone cavity is 50-500 mm; and the ratio of the diameter of the small cyclone cavity to the large cyclone cavity is 0.3-0.7.

[0015] The present invention is further configured such that the number of the gas tangential inlets is one or more, and if there are multiple, they are evenly distributed; the cross-section of the gas tangential inlet is a narrow rectangle, and the ratio of the length of the long side a to the short side b of the narrow rectangle is 2-10.

[0016] A second aspect of the present invention is to provide a gas-liquid turbulent mass transfer method for low-temperature gas stripping purification of heat-sensitive materials based on the above-mentioned device, comprising the following steps:

[0017] Liquid material is injected from the top of the tower body and forms a liquid layer above the partition. When the liquid layer height exceeds the top of the small cyclone cavity, it enters the small cyclone cavity. Gas material enters from the bottom of the tower body and enters the large cyclone cavity through the gas tangential inlet. The rising gas material and the descending liquid material complete turbulent mass transfer in the large cyclone cavity and the small cyclone cavity to remove volatile components in the liquid material.

[0018] Subsequently, the gaseous material enters the top of the partition from the small cyclone cavity and is discharged from the top of the tower body; the liquid material enters the downcomer and the liquid seal groove in sequence from the large cyclone cavity and is finally discharged from the bottom of the tower body;

[0019] When multiple turbulent elements are connected in series in the tower body, the liquid overflowing from the liquid-sealed circular groove forms a liquid layer on the partition of the next-stage turbulent element; the gas above the partition enters the gas tangential inlet of the previous-stage turbulent element, repeating the above-mentioned turbulent mass transfer process, and finally the gas is discharged from the top of the tower body, and the liquid with volatile components removed is discharged from the bottom of the tower body.

[0020] The present invention is further configured such that the ratio of the volume flow rates of the gas material and the liquid material, that is, the gas-liquid ratio, is 0.8-100. Under conditions where the gas-liquid ratio is too small, liquid turbulence cannot be promoted, and under conditions where the gas-liquid ratio is too large, mist entrainment is likely to occur.

[0021] The present invention is further configured such that the velocity of the gas material at the gas tangential inlet is 0.5-20 m / s, and the gas Reynolds number Re inside the large cyclone cavity is 10-100.

[0022] The present invention is further configured such that the viscosity of the gas material is 0.002-0.1 cP;

[0023] When the gas viscosity is 0.002-0.02cP, the gas resistance is 0.1-1kPa, and the liquid seal level height is 0.01-0.1m; when the gas viscosity is 0.02-0.1cP, the gas resistance is 1-2kPa, and the liquid seal level height is 0.1-0.2m.

[0024] The present invention is further configured such that, during the operation, liquid material should be injected first to form a liquid sealing area in the liquid sealing circular groove, and then gas material should be injected to prevent gas from entering the large cyclone cavity from the liquid sealing area.

[0025] The beneficial effects of the present invention are as follows:

[0026] The device of the present invention uses turbulent elements to enhance gas-liquid turbulence and mass transfer, effectively removing volatile components from heat-sensitive materials while preventing their deterioration. Furthermore, the provision of a liquid-sealing circular groove allows for a liquid seal with a relatively low liquid volume, reducing the residence time of the heat-sensitive material. Furthermore, compared with existing methods for gas stripping and purification of heat-sensitive materials, the present invention eliminates the need for steam, vacuum equipment, or antioxidants, significantly reducing energy consumption and purification and separation costs, addressing the difficulty of cost-effective purification of heat-sensitive materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural schematic diagram of the gas-liquid turbulent mass transfer device for low-temperature gas lift purification of heat-sensitive materials according to the present invention.

[0028] Figure 2 It is a structural diagram of the turbulent element.

[0029] Figure 3 yes Figure 2 Cross-sectional view in the AA direction.

[0030] Figure 4 It is a schematic diagram of the gas-liquid countercurrent contact form in the device of the present invention.

[0031] In the picture:

[0032] 10-tower body; 11-liquid feed port; 12-liquid discharge port; 13-gas feed port; 14-gas discharge port;

[0033] 20- turbulent element; 21- partition; 22- small swirl cavity; 23- large swirl cavity; 24- downcomer; 25- liquid seal groove; 26- connecting rib plate; 27- gas tangential inlet. DETAILED DESCRIPTION

[0034] The technical solutions of the present invention are described clearly and in detail below through specific embodiments in conjunction with the accompanying drawings. It should be understood that the following embodiments are only part of the embodiments of the present invention. Other embodiments obtained by those skilled in the art without creative work still fall within the scope of protection of the present invention.

[0035] like Figure 1 The gas-liquid turbulent mass transfer device for low-temperature gas stripping purification of heat-sensitive materials shown in the figure includes a tower body 10, the top of which is provided with a liquid feed port 11 and a gas discharge port 14, and the bottom of which is provided with a liquid discharge port 12 and a gas feed port 13; the interior of the tower body 10 is provided with a turbulent element 20, wherein:

[0036] Combine Figure 2 and Figure 3 As shown, the turbulent element 20 includes a baffle 21 coaxially arranged along the gravity direction, a small cyclone cavity 22, a large cyclone cavity 23 and a downcomer 24 that are sequentially connected, a liquid sealing circular groove 25, and a plurality of connecting ribs 26 for fixing the liquid sealing circular groove 25 to the downcomer 24;

[0037] The upper side of the small cyclone cavity 22 is fixed in the partition 21, and the top end thereof is higher than the upper surface of the partition 21;

[0038] The side wall of the large cyclone cavity 23 is provided with a gas tangential inlet 27;

[0039] The bottom end of the downcomer 24 is located in the liquid-sealed circular groove 25 .

[0040] like Figure 4 As shown, the principle of mass transfer enhancement by the turbulent element 20 is as follows:

[0041] Gas is injected through a tangential gas inlet 27 on the side wall of the large cyclone cavity 23, forming a gas-liquid cyclonic flow with the descending liquid. Specifically, as the liquid moves downward, it is acted upon by the centrifugal force of the gas cyclone, moving toward the side wall of the large cyclone cavity 23. This creates a turbulent countercurrent contact between the gas and liquid. The gas swirls through the liquid, creating a high relative slip velocity between the gas and liquid. Based on the surface renewal mass transfer theory, gas-liquid equilibrium can be achieved in a very short time, achieving enhanced mass transfer.

[0042] Furthermore, the number of the turbulent elements 20 is one or more; Figure 1 As shown, when there are multiple turbulence elements 20, the multiple turbulence elements 20 are arranged in series along the gravity direction in the tower body 10, which can increase the number of countercurrent contact units and the gas lift purification efficiency.

[0043] Furthermore, the height difference H1 between the top of the small cyclone cavity 22 and the upper surface of the partition 21 (eg Figure 4 shown) is 10-20mm.

[0044] Furthermore, the large cyclone cavity 23 and the small cyclone cavity 22 are both cylindrical, wherein the diameter of the large cyclone cavity 23 is 50-500 mm; and the ratio of the diameters of the small cyclone cavity 22 to the large cyclone cavity 23 is 0.3-0.7.

[0045] Furthermore, the number of the gas tangential inlet 27 is one or more, and if there are multiple, they are evenly distributed; Figure 3 As shown, the cross section of the gas tangential inlet 27 is a narrow and long rectangle, and the ratio of the length of the long side a to the short side b of the narrow and long rectangle is 2-10.

[0046] like Figure 1 and Figure 4 As shown, the gas-liquid turbulent mass transfer method for low-temperature gas stripping purification of heat-sensitive materials based on the above device includes the following steps:

[0047] Liquid material (i.e., heat-sensitive material including volatile components) is injected from the top of the tower body 10 and forms a liquid layer above the partition 21. When the liquid layer height exceeds the top of the small cyclone cavity 22, it enters the small cyclone cavity 22. Gas material enters from the bottom of the tower body 10 and enters the large cyclone cavity 23 through the gas tangential inlet 27. The rising gas material and the descending liquid material complete turbulent mass transfer in the large cyclone cavity 23 and the small cyclone cavity 22 to remove the volatile components in the liquid material.

[0048] Subsequently, the gaseous material enters the partition 21 from the small cyclone cavity 22 and is discharged from the top of the tower body 10; the liquid material enters the downcomer 24 and the liquid seal groove 25 from the large cyclone cavity 23 in sequence, and is finally discharged from the bottom of the tower body 10;

[0049] When multiple turbulent elements 20 are connected in series in the tower body 10, the liquid overflowing from the liquid-sealed circular groove 25 forms a liquid layer on the partition 21 of the next-stage turbulent element 20; the gas above the partition 21 enters the gas tangential inlet 27 of the previous-stage turbulent element 20, and the above-mentioned turbulent mass transfer process is repeated. Finally, the gas is discharged from the top of the tower body 10, and the liquid with volatile components removed is discharged from the bottom of the tower body 10.

[0050] Furthermore, the ratio of the volume flow rates of the gas material and the liquid material, that is, the gas-liquid ratio, is 0.8-100. If the gas-liquid ratio is too small, the liquid turbulence cannot be driven, and if the gas-liquid ratio is too large, mist entrainment is likely to occur.

[0051] Furthermore, the velocity of the gas material at the gas tangential inlet 27 is 0.5-20 m / s, and the Reynolds number Re of the gas inside the large cyclone cavity 23 is 10-100.

[0052] The gas Reynolds number can reflect the degree of turbulence. Where D is the diameter of the large cyclone cavity 23, u is the gas velocity at the gas tangential inlet 27, and ρ G is the gas density, μ G is the gas viscosity.

[0053] Furthermore, the viscosity of the gas material is 0.002-0.1 cP. When the gas viscosity is high, the resistance of the gas moving from the tangential gas inlet 27 to the top of the partition 21 is large, and the gas resistance determines the liquid seal level height (such as Figure 4 As shown), the required liquid seal level is also larger, specifically:

[0054] When the gas viscosity is 0.002-0.02cP, the gas resistance is 0.1-1kPa, and the liquid seal level height is 0.01-0.1m; when the gas viscosity is 0.02-0.1cP, the gas resistance is 1-2kPa, and the liquid seal level height is 0.1-0.2m.

[0055] Furthermore, the height of the liquid layer above the partition 21 is 10-20 mm, so as to minimize the residence time of the heat-sensitive material while maintaining the mass transfer effect.

[0056] Furthermore, in the operation link, liquid material should be injected first to form a liquid seal groove 25 as shown in FIG. Figure 4 The liquid seal area shown is then injected with gas material to prevent the gas from entering the large cyclone cavity 23 from the liquid seal area.

[0057] Application Examples

[0058] Polyether polyols are typically heat-sensitive materials with poor thermal stability. When heated, they undergo oxidation reactions, causing the material to turn yellow. Traditional polyether polyol production processes involve multiple steps, including raw materials, side reactions, and post-processing, all of which lead to the formation of volatile substances (aldehydes), which are difficult to separate.

[0059] Total aldehyde content test method: A liquid chromatography instrument Shimadzu LC-20AT, UV detector, and chromatographic column model VenusilXBPC18(2) were used. The mobile phase used was a mixture of water, acetonitrile, and tetrahydrofuran (the mass ratio of the three was 53:31:16). After the sample was derivatized with 2,4-dinitrophenylhydrazine, aldehyde substances were determined by HPLC.

[0060] Example 1

[0061] The above-mentioned gas-liquid turbulent mass transfer device for low-temperature gas stripping purification of heat-sensitive materials was used to perform nitrogen stripping treatment on polyether polyols to remove volatile aldehydes. The specific parameters and process conditions were set as follows:

[0062] Liquid flow rate is 0.1m 3 / h, nitrogen flow rate 3.6m 3 / h, gas-liquid ratio is 36;

[0063] The gas velocity at the gas tangential inlet 27 is 10 m / s, and the gas Reynolds number inside the large cyclone cavity 23 is 67.

[0064] The gas viscosity is 0.018 cP, the gas resistance is 0.18, and the liquid seal level height is 0.18 m.

[0065] The height of the liquid layer formed above the partition 21 is 10 mm;

[0066] The diameter of the large cyclone cavity 23 is 100 mm, the ratio of the diameter of the small cyclone cavity 22 to the diameter of the large cyclone cavity 23 is 0.5, and the ratio of the length of the long side a to the short side b of the gas tangential inlet 27 is 4.

[0067] Comparative Example 1

[0068] The polyether polyol was stripped using a method disclosed in CN106543427A for removing volatile substances from the polyether polyol and reducing odor. An antioxidant and a reducing agent were added to the polyether polyol. Then, water vapor was used as a stripping agent. The ratio of the water vapor flow rate to the volume flow rate of the polyether polyol was adjusted to 2.5. The stripping operation was carried out at 140°C and 0.08 MPa.

[0069] Comparative Example 2

[0070] On the basis of the device of Example 1, the gas tangential inlet 27 of the turbulence element 20 is changed to eight radial inlets, and nitrogen stripping treatment is performed at the same gas-liquid flow rate.

[0071] The treatment effect data of the above embodiment 1 and comparative examples 1-2 are shown in the following table 1:

[0072] Table 1 Treatment effect data

[0073] Example 1 Comparative Example 1 Comparative Example 2 Initial total aldehyde content / ppm 200 200 200 Residual total aldehyde content / ppm 4 4 30 Purification efficiency 98％ 98％ 85％

[0074] The results in Table 1 indicate that the device of the present invention, without the addition of antioxidants or reducing agents, achieves comparable removal efficiency to that of Comparative Example 1, significantly reducing aldehyde content in polyether polyols. Furthermore, the present invention utilizes low-temperature stripping, which reduces steam consumption, antioxidant consumption, and vacuum equipment power consumption compared to Comparative Example 1.

[0075] In Comparative Example 2, the eight radial gas inlets reduce the gas velocity and fail to form a gas vortex in the large vortex cavity 23, resulting in a decrease in turbulence and failure to obtain effective gas lift separation.

[0076] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A gas-liquid turbulent mass transfer device for low-temperature gas stripping and purification of heat-sensitive materials, characterized in that: The tower body comprises a tower body, wherein the top of the tower body is provided with a liquid feed port and a gas discharge port, and the bottom of the tower body is provided with a liquid discharge port and a gas feed port; the interior of the tower body is provided with a turbulent element, wherein: The turbulent element includes a baffle coaxially arranged along the gravity direction, a small cyclone cavity, a large cyclone cavity and a downcomer connected in sequence, a liquid sealing circular groove, and a plurality of connecting ribs for fixing the liquid sealing circular groove to the downcomer; The upper side of the small cyclone cavity is fixed in the partition, and the top end thereof is higher than the upper surface of the partition; The side wall of the large cyclone cavity is provided with a gas tangential inlet; The bottom end of the downcomer is located in the liquid-sealed circular groove.

2. The gas-liquid turbulent mass transfer device for low-temperature gas stripping purification of heat-sensitive materials according to claim 1, characterized in that: The number of the turbulence elements is one or more; when there are multiple turbulence elements, the multiple turbulence elements are arranged in series along the gravity direction in the tower body.

3. The gas-liquid turbulent mass transfer device for low-temperature gas stripping purification of heat-sensitive materials according to claim 1, characterized in that: The height difference H1 between the top of the small cyclone cavity and the upper surface of the partition is 10-20 mm.

4. The gas-liquid turbulent mass transfer device for low-temperature gas stripping purification of heat-sensitive materials according to claim 1, characterized in that: The large cyclone cavity and the small cyclone cavity are both cylindrical, wherein the diameter of the large cyclone cavity is 50-500 mm; and the ratio of the diameter of the small cyclone cavity to the large cyclone cavity is 0.3-0.

7.

5. The gas-liquid turbulent mass transfer device for low-temperature gas stripping purification of heat-sensitive materials according to claim 1, characterized in that: The number of the gas tangential inlet is one or more, and if there are multiple, they are evenly distributed; the cross section of the gas tangential inlet is a narrow rectangle, and the ratio of the length of the long side a to the short side b of the narrow rectangle is 2-10.

6. A gas-liquid turbulent mass transfer method for low-temperature gas stripping purification of heat-sensitive materials, characterized in that: The gas-liquid turbulent mass transfer device for low-temperature gas stripping and purification of heat-sensitive materials according to any one of claims 1 to 5 comprises the following steps: Liquid material is injected from the top of the tower body and forms a liquid layer above the partition. When the liquid layer height exceeds the top of the small cyclone cavity, it enters the small cyclone cavity. Gas material enters from the bottom of the tower body and enters the large cyclone cavity through the gas tangential inlet. The rising gas material and the descending liquid material complete turbulent mass transfer in the large cyclone cavity and the small cyclone cavity to remove volatile components in the liquid material. Subsequently, the gaseous material enters the top of the partition from the small cyclone cavity and is discharged from the top of the tower body; the liquid material enters the downcomer and the liquid seal groove in sequence from the large cyclone cavity and is finally discharged from the bottom of the tower body; When multiple turbulent elements are connected in series in the tower body, the liquid overflowing from the liquid-sealed circular groove forms a liquid layer on the partition of the next-stage turbulent element; the gas above the partition enters the gas tangential inlet of the previous-stage turbulent element, repeating the above-mentioned turbulent mass transfer process, and finally the gas is discharged from the top of the tower body, and the liquid with volatile components removed is discharged from the bottom of the tower body.

7. The gas-liquid turbulent mass transfer method for low-temperature gas stripping purification of heat-sensitive materials according to claim 6, characterized in that: The ratio of the volume flow rates of the gas material and the liquid material, that is, the gas-liquid ratio, is 0.8-100.

8. The gas-liquid turbulent mass transfer method for low-temperature gas stripping purification of heat-sensitive materials according to claim 6, characterized in that: The velocity of the gas material at the gas tangential inlet is 0.5-20 m / s, and the gas Reynolds number Re inside the large cyclone cavity is 10-100.

9. The gas-liquid turbulent mass transfer method for low-temperature gas stripping purification of heat-sensitive materials according to claim 6, characterized in that: The viscosity of the gas material is 0.002-0.1 cP; When the gas viscosity is 0.002-0.02cP, the gas resistance is 0.1-1kPa, and the liquid seal level height is 0.01-0.1m; when the gas viscosity is 0.02-0.1cP, the gas resistance is 1-2kPa, and the liquid seal level height is 0.1-0.2m.

10. The gas-liquid turbulent mass transfer method for low-temperature gas stripping purification of heat-sensitive materials according to claim 6, characterized in that: During the operation, liquid material should be injected first to form a liquid seal area in the liquid seal circular groove, and then gas material should be injected to prevent gas from entering the large cyclone cavity from the liquid seal area.

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