Non-hot gas stripping separation device and method for trace volatile components

Abstract

The invention discloses a trace volatile component non-hot gas stripping separation device and method, the device comprises a tower body, 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 tower plates are arranged in the tower body, each turbulent element is arranged between every two adjacent tower plates, and a downcomer is fixedly arranged on one side of each tower plate in a penetrating manner; the turbulent element comprises a partition plate coaxially arranged in the gravity direction, and a small rotational flow cavity, a large rotational flow cavity and a liquid seal pipe which are communicated in sequence; and a tangential gas inlet is formed in the side wall of the large rotational flow cavity. According to the device disclosed by the invention, the turbulent elements are additionally arranged between the tower plates, and mass transfer is enhanced by utilizing gas-liquid turbulent contact, so that the gas stripping purification efficiency of unit tower height can be improved, and the carrier gas consumption in a non-hot gas stripping process and the separation cost of trace volatile components are reduced.

Description

Technical Field

[0001] The invention belongs to the field of chemical equipment, and in particular relates to a non-thermal gas stripping separation device and method for trace volatile components. Background Art

[0002] The low separation efficiency and high separation cost of trace volatile components are long-standing engineering problems. Traditional separation of trace volatile components relies on thermal distillation, but the processing cost per unit mass of volatile components is too high, and high temperature can also cause equipment corrosion problems.

[0003] To solve the above problems, the idea of ​​using non-thermal gas as carrier gas for gas stripping has received widespread attention. For example, CN101987970A provides a method for removing mercaptans from gasoline, wherein the mercaptans in the raw material are first decomposed into olefins and hydrogen sulfide, and an inert gas is directly injected into the reactor to remove hydrogen sulfide, and the mercaptan sulfur content in the gasoline product is less than 3 μg / g.

[0004] CN103865575 A provides a method for liquid phase circulating hydrogenation reforming of high nitrogen catalytic cracking diesel, wherein the product coming out of the top of the reactor enters a hydrogen stripping separator, an appropriate amount of hydrogen is introduced into the lower part of the hydrogen stripping separator to strip out ammonia and hydrogen sulfide, and the reaction by-products hydrogen sulfide and ammonia are discharged from the reaction system.

[0005] CN112175670A provides a high-pressure steam stripping and impurity removal method for environmentally friendly aromatic oil before the second-stage hydrogenation, which uses circulating hydrogen as a carrier gas to blow off and separate hydrogen sulfide under high pressure conditions.

[0006] Plate tower is a typical gas lift separation equipment, which has the advantage of low gas phase backmixing. However, the gas-liquid countercurrent relative movement of the plate tower is limited by the gravity field, and the gas-liquid mass transfer efficiency is low. In order to minimize the residual content of volatile components in the liquid phase, it is usually necessary to increase the carrier gas injection amount, resulting in excessive operating costs; or in order to improve the separation efficiency, the tower height is continuously increased, resulting in excessive investment costs. Summary of the invention

[0007] In view of the shortcomings of non-thermal gas stripping separation in the prior art, the present invention provides a device and method for non-thermal gas stripping separation of trace volatile components. By arranging turbulent elements between the plates of a plate tower, the gas-liquid turbulence degree is enhanced, the convective mass transfer is enhanced, and the use of carrier gas is reduced.

[0008] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is as follows:

[0009] The first aspect of the present invention is to provide a non-thermal stripping separation device for trace volatile components, comprising 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; and further comprising a plurality of tower plates arranged inside the tower body, and a turbulent element arranged between two adjacent tower plates, wherein:

[0010] A downcomer is fixedly provided on one side of the tower plate;

[0011] The turbulent element comprises a baffle coaxially arranged along the gravity direction, a small cyclone cavity, a large cyclone cavity and a liquid seal pipe which are connected in sequence; a gas tangential inlet is arranged on the side wall of the large cyclone cavity;

[0012] The upper side of the small cyclone cavity is fixed in the partition and its top is higher than the upper surface of the partition;

[0013] The top end of the downcomer is higher than the bottom end of the liquid sealing tube.

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

[0015] The cross section of the gas tangential inlet of the large cyclone cavity 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.

[0016] The present invention is further configured such that the tower plate is a sieve plate, and the sieve plate is provided with bubbling holes outside the position corresponding to the liquid sealing tube; the thickness of the sieve plate is 1-3 mm.

[0017] 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 20-50 mm.

[0018] The second aspect of the present invention is to provide a non-thermal stripping method for separating trace volatile components based on the above device, comprising the following steps:

[0019] Liquid is injected from the top of the tower body and forms a liquid layer above the partition of the turbulent element. When the liquid layer height exceeds the top of the small cyclone cavity, it enters the small cyclone cavity. Gas is injected from the bottom of the tower body and enters the large cyclone cavity through the gas tangential inlet. The gas and liquid complete turbulent mass transfer in the large cyclone cavity and the small cyclone cavity.

[0020] The gas enters the top of the baffle from the small cyclone cavity, and enters the gas tangential inlet of the upper turbulent element through the tower plate;

[0021] The liquid enters the liquid seal tube from the large cyclone cavity, is injected into the next stage turbulent element through the downcomer, and forms a liquid layer above its partition;

[0022] The above turbulent mass transfer process is repeated, and finally the gas is discharged from the top of the tower body, and the liquid with trace volatile components removed is discharged from the bottom of the tower body.

[0023] The present invention is further configured such that, in the operation link, the gas material is injected first and then the liquid material is injected to form a liquid seal area, thereby preventing the gas from passing through the tower plate and entering the large cyclone cavity from the liquid seal area, so that the gas and liquid phases enter the turbulent element according to the above-mentioned flow direction for gas-liquid mass transfer, thereby enhancing the separation effect.

[0024] The present invention is further configured such that the ratio of the volume flow rates of the gas and the liquid, that is, the gas-liquid ratio, is 0.8-1000.

[0025] The present invention is further configured such that the tower plate is a sieve plate, and the sieve plate is provided with bubbling holes outside the position corresponding to the liquid sealing tube; the gas flow rate at the bubbling holes is 1-3 m / s.

[0026] The present invention is further configured such that the gas flow rate at the gas tangential inlet is 0.5-20 m / s;

[0027] The Reynolds number of the gas inside the large cyclone cavity is 10-100.

[0028] The present invention is further configured such that the vertical component of the gas velocity inside the small cyclone cavity does not exceed 2 m / s to prevent flooding.

[0029] The beneficial effects of the present invention are as follows:

[0030] The device of the present invention adds turbulent elements between the tower plates and utilizes gas-liquid turbulent contact to enhance mass transfer, thereby improving the gas stripping purification efficiency per unit tower height and reducing the carrier gas consumption in the non-thermal gas stripping process and the cost of separating trace volatile components. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic structural diagram of the non-thermal stripping separation device for trace volatile components of the present invention.

[0032] Figure 2 It is a schematic diagram of the positional relationship between turbulent elements and tower plates.

[0033] Figure 3 It is a schematic diagram of the structure of the turbulent element.

[0034] Figure 4 It is a schematic diagram of the gas-liquid countercurrent contact form in the device of the present invention.

[0035] Figure 5 yes Figure 3 Cross-sectional view along the AA direction.

[0036] Figure 6Schematic diagram of the structure of the plate tower without turbulent elements in Example 1.

[0037] In the figure:

[0038] 10-tower body; 11-liquid feed port; 12-liquid discharge port; 13-gas feed port; 14-gas discharge port;

[0039] 20-tower plate; 21-downcomer;

[0040] 30- turbulent element; 31- partition; 32- small swirl cavity; 33- large swirl cavity; 34- liquid seal tube; 35- gas tangential inlet. DETAILED DESCRIPTION

[0041] The technical solution of the present invention is clearly and comprehensively described 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.

[0042] like Figure 1-2 The non-thermal stripping separation device for trace volatile components shown in the figure comprises a tower body 10, wherein the top of the tower body 10 is provided with a liquid feed port 11 and a gas discharge port 14, and the bottom of the tower body 10 is provided with a liquid discharge port 12 and a gas feed port 13; and further comprises a plurality of tower plates 20 arranged inside the tower body 10, and a turbulent element 30 for enhancing mass transfer arranged between two adjacent tower plates 20, wherein:

[0043] A downcomer 21 is fixedly disposed on one side of the tower plate 20;

[0044] Combination Figure 3 As shown, the turbulent element 30 includes a baffle 31 coaxially arranged along the gravity direction, a small cyclone cavity 32, a large cyclone cavity 33 and a liquid seal pipe 34 which are connected in sequence; a gas tangential inlet 35 is arranged on the side wall of the large cyclone cavity 33;

[0045] The upper side of the small cyclone cavity 32 is fixed in the partition 31 and its top is higher than the upper surface of the partition 31;

[0046] like Figure 2 As shown, the top end of the downcomer 21 is higher than the bottom end of the liquid sealing pipe 34 .

[0047] like Figure 4 As shown, the principle of mass transfer enhancement by the turbulence element 30 is as follows:

[0048] The gas is injected from the gas tangential inlet 35 on the side wall of the large cyclone cavity 33, and forms a gas-liquid cyclone flow with the descending liquid. Specifically, during the top-down movement of the liquid, the liquid is subjected to the centrifugal force of the gas cyclone and moves toward the side wall of the large cyclone cavity 33, and the gas and liquid form a turbulent countercurrent contact. The gas cyclones while penetrating the liquid, forming a large relative slip velocity between the gas and the liquid. According to the surface renewal mass transfer theory, gas-liquid equilibrium can be achieved in a very short time, and the effect of enhanced mass transfer can be achieved.

[0049] Further, the large cyclone cavity 33 and the small cyclone cavity 32 are both cylindrical, and the diameter of the large cyclone cavity 33 is 50-500 mm; the ratio of the diameter of the small cyclone cavity 32 to the large cyclone cavity 33 is 0.3-0.7;

[0050] like Figure 5 As shown, the number of the gas tangential inlet 35 is one or more, and if there are multiple, they are evenly distributed; the cross section of the gas tangential inlet 35 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;

[0051] Furthermore, the tower plate 20 is a sieve plate, and the sieve plate is provided with bubbling holes outside the position corresponding to the liquid sealing tube 34; the thickness of the sieve plate is 1-3 mm, and the smaller the thickness of the sieve plate, the smaller the gas resistance in the bubbling process.

[0052] Furthermore, the height difference H1 (eg, Figure 4 shown) is 20-50mm.

[0053] like Figure 4 As shown, the non-thermal stripping separation method of trace volatile components based on the above device comprises the following steps:

[0054] Liquid (containing trace volatile components) is injected from the top of the tower body 10 and forms a liquid layer above the partition 31 of the turbulent element 30. When the liquid layer height exceeds the top of the small cyclone cavity 32, it enters the small cyclone cavity 32. Gas is injected from the bottom of the tower body 10 and enters the large cyclone cavity 33 through the gas tangential inlet 35. The gas and liquid complete turbulent mass transfer in the large cyclone cavity 33 and the small cyclone cavity 32.

[0055] The gas enters the upper part of the partition plate 31 from the small cyclone cavity 32, and enters the gas tangential inlet 35 of the upper stage turbulent element 30 through the tower plate 20;

[0056] The liquid enters the liquid seal pipe 34 from the large cyclone cavity 33, and is injected into the next-stage turbulent element 30 through the downcomer 21, and forms a liquid layer above its partition 31;

[0057] The above turbulent mass transfer process is repeated, and finally the gas is discharged from the top of the tower body 10, and the liquid with trace volatile components removed is discharged from the bottom of the tower body 10.

[0058] Furthermore, in the operation step, the gas material is first injected, and then the liquid is injected to form a Figure 4 The liquid seal area shown prevents the gas from passing through the tower plate 20 and entering the large cyclone cavity 33 from the liquid seal area, so that the gas and liquid phases enter the turbulent element 30 in the above-mentioned flow direction for gas-liquid mass transfer, thereby enhancing the separation effect.

[0059] Furthermore, the ratio of the volume flow rates of the gas and the liquid, that is, the gas-liquid ratio, is 0.8-1000. Under conditions where the gas-liquid ratio is too small, the gas cannot drive the liquid to turbulently move, and under conditions where the gas-liquid ratio is too large, mist entrainment is likely to occur.

[0060] Furthermore, the tower plate 20 is a sieve plate, and the sieve plate 20 is provided with bubbling holes outside the position corresponding to the liquid sealing tube 34; the gas flow rate at the bubbling holes is 1-3 m / s.

[0061] Further, the gas flow rate at the gas tangential inlet 35 is 0.5-20m / s;

[0062] The Reynolds number of the gas inside the large cyclone cavity 33 is 10-100.

[0063] The gas Reynolds number can reflect the degree of turbulence. Where D is the diameter of the large cyclone cavity 33, u is the gas velocity at the gas tangential inlet 35, and ρ G is the gas density, μ G is the gas viscosity.

[0064] Furthermore, the vertical component velocity of the gas velocity inside the small cyclone cavity 32 does not exceed 2 m / s to prevent flooding.

[0065] Example 1

[0066] Trace dissolved oxygen in boiler water is the main cause of equipment and pipeline corrosion. This embodiment uses the above-mentioned trace volatile component non-thermal stripping separation device to separate trace dissolved oxygen in water. The specific equipment and process parameters used are as follows:

[0067] The diameter of the large cyclone cavity 33 is 100 mm, the ratio of the length of the long side to the short side of the cross section of the gas tangential inlet 35 is 4, the ratio of the diameter of the small cyclone cavity 32 to the diameter of the large cyclone cavity 33 is 0.5, and the thickness of the sieve plate is 2 mm;

[0068] The gas material volume flow rate is 3.6m 3 / h, the volume flow rate of liquid material is 0.1m 3 / h, the gas-liquid ratio is 36; the gas velocity at the bubble hole is 2m / s; the gas velocity at the gas tangential inlet is 10m / s, the gas Reynolds number inside the large cyclone cavity is 67; the gas velocity inside the small cyclone cavity in the vertical direction is 1m / s.

[0069] Comparative Example 1

[0070] Based on the device of the above embodiment 1, Figure 6 As shown, the turbulence element was removed, and then a gas lift separation test of trace dissolved oxygen in water was carried out at the same gas-liquid flow rate.

[0071] Comparative Example 2

[0072] On the basis of the device of the above-mentioned embodiment 1, the gas tangential inlet 35 of the turbulent element 30 is changed to eight radial inlets, the gas cyclonic flow is eliminated, and then the gas lift separation test of trace dissolved oxygen in water is carried out at the same gas-liquid flow rate.

[0073] The gas stripping separation effects of the above Example 1 and Comparative Examples 1-2 are shown in Table 1 below:

[0074] Table 1

[0075] Example 1 Comparative Example 1 Comparative Example 2 Initial dissolved oxygen content / ppm 8 8 8 Residual dissolved oxygen content / ppm 0.01 5 4 Purification efficiency 99.9％ 37.5％ 50.0％

[0076] It can be seen from the results in Table 1 that, under the same gas-liquid flow rate, the dissolved oxygen purification efficiency of the device of the present invention can be as high as 99.9%; when the turbulence element is missing, the separation diffusion is slow at low temperature and effective gas lift separation cannot be obtained; the gas tangential inlet 35 of the turbulence element 30 is changed to eight radial inlets, which reduces the gas velocity at the inlet and makes it impossible to form a vortex, resulting in a decrease in the turbulence level in the turbulence element and a poor dissolved oxygen lift separation effect.

[0077] 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 principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A non-thermal stripping separation device for trace volatile components, 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; and further comprises a plurality of tower plates arranged inside the tower body, and a turbulent element arranged between two adjacent tower plates, wherein: A downcomer is fixedly provided on one side of the tower plate; The turbulent element comprises a baffle coaxially arranged along the gravity direction, a small cyclone cavity, a large cyclone cavity and a liquid seal pipe which are connected in sequence; a gas tangential inlet is arranged on the side wall of the large cyclone cavity; The upper side of the small cyclone cavity is fixed in the partition and its top is higher than the upper surface of the partition; The top end of the downcomer is higher than the bottom end of the liquid sealing tube.

2. The non-thermal stripping separation device for trace volatile components according to claim 1, characterized in that: The large cyclone cavity and the small cyclone cavity are both cylindrical, the diameter of the large cyclone cavity is 50-500 mm; the ratio of the diameter of the small cyclone cavity to the large cyclone cavity is 0.3-0.7; The cross section of the gas tangential inlet of the large cyclone cavity 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.

3. The non-thermal stripping separation device for trace volatile components according to claim 1, characterized in that: The tower plate is a sieve plate, and the sieve plate is provided with bubbling holes outside the position corresponding to the liquid sealing tube; the thickness of the sieve plate is 1-3 mm.

4. The non-thermal stripping separation device for trace volatile components 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 20-50 mm.

5. A non-thermal stripping method for separating trace volatile components, characterized in that: The non-thermal stripping separation device for trace volatile components according to claims 1 to 4 above comprises the following steps: Liquid is injected from the top of the tower body and forms a liquid layer above the partition of the turbulent element. When the liquid layer height exceeds the top of the small cyclone cavity, it enters the small cyclone cavity. Gas is injected from the bottom of the tower body and enters the large cyclone cavity through the gas tangential inlet. The gas and liquid complete turbulent mass transfer in the large cyclone cavity and the small cyclone cavity. The gas enters the top of the baffle from the small cyclone cavity, and enters the gas tangential inlet of the upper turbulent element through the tower plate; The liquid enters the liquid seal tube from the large cyclone cavity, is injected into the next stage turbulent element through the downcomer, and forms a liquid layer above its partition; The above turbulent mass transfer process is repeated, and finally the gas is discharged from the top of the tower body, and the liquid with trace volatile components removed is discharged from the bottom of the tower body.

6. The non-thermal stripping separation method of trace volatile components according to claim 5, characterized in that: In the operation process, the gas material is injected first, and then the liquid material is injected to form a liquid seal area to prevent the gas from passing through the tower plate and entering the large cyclone cavity from the liquid seal area. The gas and liquid phases enter the turbulent element in the above-mentioned flow direction for gas-liquid mass transfer, thereby enhancing the separation effect.

7. The non-thermal stripping separation method of trace volatile components according to claim 5, characterized in that: The ratio of the volume flow rates of the gas and the liquid, that is, the gas-liquid ratio, is 0.8-1000.

8. The non-thermal stripping separation method of trace volatile components according to claim 5, characterized in that: The tower plate is a sieve plate, and the sieve plate is provided with bubbling holes outside the corresponding position of the liquid sealing tube; the gas flow rate at the bubbling holes is 1-3m / s.

9. The non-thermal stripping separation method of trace volatile components according to claim 5, characterized in that: The gas flow rate at the gas tangential inlet is 0.5-20m / s; The Reynolds number of the gas inside the large cyclone cavity is 10-100.

10. The non-thermal stripping separation method of trace volatile components according to claim 5, characterized in that: The vertical component of the gas velocity inside the small cyclone cavity does not exceed 2 m / s.

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