A device and method for non-thermal stripping of trace volatile components

Abstract

The application discloses a device and method for non-thermal gas stripping separation of trace volatile components, which comprises a tower body, a liquid inlet and a gas outlet arranged at the top of the tower body, a liquid outlet and a gas inlet arranged at the bottom of the tower body, a plurality of tower plates arranged in the tower body, and a turbulent element arranged between two adjacent tower plates, wherein one side of the tower plate is provided with a downcomer, 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 sequentially connected, and the side wall of the large cyclone cavity is provided with a gas tangential inlet. The device of the application increases the turbulent element between the tower plates, strengthens the mass transfer by gas-liquid turbulent contact, can improve the gas stripping purification efficiency of unit tower height, and reduces the carrier gas consumption in the non-thermal gas stripping process and the cost of separation of trace volatile components.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of chemical equipment, and particularly relates to a device and method for non-thermal gas stripping separation of trace volatile components. BACKGROUND

[0002] Low separation efficiency and high separation cost of trace volatile components are long-standing engineering problems. Traditional separation of trace volatile components relies on heat rectification, but the processing cost of unit mass of volatile components is too high, and high temperature can cause equipment corrosion problems.

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

[0004] CN103865575A provides a method for liquid phase cycle hydro-upgrading of high-nitrogen catalytic cracking diesel. The product at the top of the reactor enters a hydrogen stripping separator, hydrogen is introduced into the lower part of the hydrogen stripping separator, and ammonia and hydrogen sulfide are stripped out, and the reaction byproducts hydrogen sulfide and ammonia are discharged from the reaction system.

[0005] CN112175670A provides a high-pressure stripping method for removing impurities before two-stage hydrogenation of environmentally friendly aromatic oil. Recycled hydrogen is used as a carrier gas to separate hydrogen sulfide under high pressure.

[0006] Plate column is a typical stripping separation equipment with the advantage of low gas phase back mixing. However, the relative motion of gas-liquid countercurrent in the plate column is limited by the action of gravity field, and the gas-liquid mass transfer efficiency is low. In order to reduce the residual content of volatile components in the liquid phase as much as possible, the amount of carrier gas injection needs to be increased, resulting in high operating cost; or in order to improve the separation efficiency, the column height needs to be increased, resulting in high investment cost. SUMMARY

[0007] In view of the deficiencies of non-thermal stripping separation in the prior art, the present application provides a device and method for non-thermal stripping separation of trace volatile components, which strengthens the degree of gas-liquid turbulence by setting turbulence elements between the plates of the plate column, and strengthens the convective mass transfer while reducing the amount of carrier gas used.

[0008] To achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0009] The first aspect of the present application provides a non-thermal stripping separation device for trace volatile components, comprising a tower body, wherein a liquid inlet and a gas outlet are arranged at the top of the tower body, and a liquid outlet and a gas inlet are arranged at the bottom of the tower body; a plurality of tower plates are arranged in the tower body, and a turbulent element is arranged between two adjacent tower plates.

[0010] A downcomer is fixed 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 sequentially connected; the side wall of the large cyclone cavity is provided with a gas tangential inlet;

[0012] The top end of the small cyclone cavity is fixed in the baffle and higher than the upper surface of the baffle;

[0013] The top end of the downcomer is higher than the bottom end of the liquid seal pipe.

[0014] The large cyclone cavity and the small cyclone cavity are both cylindrical, the diameter of the large cyclone cavity is 50-500 mm, and the diameter ratio of the small cyclone cavity to 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 long and narrow rectangle, and the length ratio of the long side a to the short side b of the long and narrow rectangle is 2-10.

[0016] The tower plate is a sieve plate, the sieve plate is provided with a bubbling hole at a position corresponding to the liquid seal pipe, and the thickness of the sieve plate is 1-3 mm.

[0017] The height difference H1 between the top end of the small cyclone cavity and the upper surface of the baffle is 20-50 mm.

[0018] The second aspect of the present application provides a non-thermal stripping separation method for trace volatile components based on the above device, comprising the following steps:

[0019] The liquid is injected from the top of the tower body and forms a liquid layer above the baffle of the turbulent element, and when the height of the liquid layer exceeds the top end of the small cyclone cavity, the liquid enters the small cyclone cavity; the gas is injected from the bottom of the tower body and enters the large cyclone cavity through the gas tangential inlet; the gas-liquid completes turbulent mass transfer in the large cyclone cavity and the small cyclone cavity;

[0020] The gas enters above 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 pipe from the large cyclone cavity, is injected into the lower turbulent element through the downcomer, and forms a liquid layer above the baffle of the lower turbulent element;

[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 is discharged from the bottom of the tower body.

[0023] The present application is further provided that, in the operation link, the gas material is injected first, and then the liquid material is injected to form a liquid seal area, so as to avoid the gas from passing through the tray to enter the large cyclone cavity from the liquid seal area, so that the gas-liquid two-phase flows into the turbulent element according to the above flow direction to strengthen the separation effect.

[0024] The present application is further provided that, the volume flow ratio of the gas and the liquid, that is, the gas-liquid ratio is 0.8-1000.

[0025] The present application is further provided that, the tray is a sieve plate, and the sieve plate is provided with a bubbling hole outside the corresponding position of the liquid seal pipe; the gas flow rate at the bubbling hole is 1-3 m / s.

[0026] The present application is further provided that, the gas flow rate at the tangential inlet of the gas is 0.5-20 m / s.

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

[0028] The present application is further provided that, the gas velocity inside the small cyclone cavity is not more than 2 m / s in the vertical direction, so as to prevent flooding.

[0029] The present application has the beneficial effects as follows:

[0030] The device of the present application increases the turbulent element between the trays, utilizes the gas-liquid turbulent contact to strengthen the mass transfer, can improve the gas stripping purification efficiency per unit tower height, and reduces the carrier gas consumption in the non-thermal gas stripping process and the cost of trace volatile component separation. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 is a structure schematic view of the trace volatile component non-thermal gas stripping separation device of the present application.

[0032] Figure 2 is a schematic view of the position relationship between the turbulent element and the tray.

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

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

[0035] Figure 5 is Figure 3 is a sectional view in A-A direction.

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

[0037] In the picture:

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

[0039] 20- tray; 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 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.

[0042] like Figures 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; the tower body 10 further comprises a plurality of trays 20 disposed within the tower body 10, and a turbulence element 30 disposed between two adjacent trays 20 for enhancing mass transfer, wherein:

[0043] A downcomer 21 is fixed on one side of the tray 20;

[0044] Combine 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 that are connected in sequence; a gas tangential inlet 35 is provided 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] Gas is injected through a tangential gas inlet 35 on the side wall of the large cyclone cavity 33, 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 33. This creates a turbulent countercurrent contact between the gas and liquid. The gas cyclones while penetrating the liquid, resulting in 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.

[0049] Furthermore, the large cyclone cavity 33 and the small cyclone cavity 32 are both cylindrical, 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 rectangle, and the ratio of the length of the long side a to the short side b of the narrow 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 during the bubbling process.

[0052] Furthermore, the height difference H1 between the top of the small cyclone cavity 32 and the upper surface of the partition 31 (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 includes 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 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. Turbulent mass transfer is completed between the gas and liquid in the large cyclone cavity 33 and the small cyclone cavity 32.

[0055] The gas enters the upper part of the partition 31 from the small cyclone cavity 32 and enters the gas tangential inlet 35 of the upper stage turbulent element 30 through the tray 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 is discharged from the bottom of the tower body 10.

[0058] Further, in the operation, the gas material is injected first, and then the liquid is injected, forming a liquid seal area as shown in the figure, avoiding the gas from passing through the tray 20 from the liquid seal area into the large cyclone cavity 33, so that the gas-liquid two-phase flows into the turbulent element 30 in the above-mentioned flow direction to carry out gas-liquid mass transfer, and the separation effect is strengthened. Figure 4

[0059] Further, the volume flow ratio of the gas and the liquid, that is, the gas-liquid ratio is 0.8-1000, and under the condition of too small gas-liquid ratio, the gas cannot push the liquid to be turbulent, and under the condition of too large gas-liquid ratio, mist entrainment is prone to occur.

[0060] Further, the tray 20 is a sieve plate, and the sieve plate 20 is provided with a bubbling hole outside the corresponding position of the liquid seal pipe 34; the gas flow rate at the bubbling hole is 1-3 m / s.

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

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

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

[0064] Further, the vertical component of the gas velocity inside the small cyclone cavity 32 is not more than 2 m / s, which prevents flooding.

[0065] Embodiment 1

[0066] The trace dissolved oxygen in the boiler water is the main inducement for the corrosion of equipment and pipelines. The above-mentioned trace volatile component non-thermal gas stripping separation device is used to separate the trace dissolved oxygen in the water, and the specific equipment and process parameters used are as follows:

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

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

[0069] Comparative Example 1

[0070] On the basis of the device in Example 1 above, the turbulent elements were removed, and then the gas stripping separation test of trace dissolved oxygen in water was carried out under the same gas-liquid flow rate. Figure 6

[0071] Comparative Example 2

[0072] On the basis of the device in Example 1 above, the tangential gas inlet 35 of the turbulent element 30 was changed to eight radial inlets, and the gas cyclone flow was cancelled, and then the gas stripping separation test of trace dissolved oxygen in water was carried out under the same gas-liquid flow rate.

[0073] The gas stripping separation effects of Example 1 and Comparative Examples 1-2 above 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] As can be seen from the results in Table 1, under the same gas-liquid flow rate, the dissolved oxygen purification efficiency of the device of the present application can be as high as 99.9%; when the turbulent elements are absent, the separation and diffusion are slow at low temperature, and effective gas stripping separation cannot be obtained; when the tangential gas inlet 35 of the turbulent element 30 is changed to eight radial inlets, the gas velocity at the inlet is reduced, and the cyclone flow cannot be formed, resulting in a decrease in the degree of turbulence in the turbulent element, and the dissolved oxygen gas stripping separation effect is poor.

[0077] The above only describes the preferred embodiments of the present application, and is not intended to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.​

Claims

1. A non-thermal stripping separation device for trace volatile components, characterized in that: The invention 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 tower body also 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 fixed on one side of the tower plate; The turbulent element comprises a baffle coaxially arranged along the direction of gravity, a small cyclone cavity, a large cyclone cavity and a liquid seal pipe connected in sequence; a gas tangential inlet is provided 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 seal tube; 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.

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 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 is characterized in that it 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 partition from the small swirl cavity, and enters the gas tangential inlet of the upper stage 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: During the operation, the gas material is injected first, and then the liquid material is injected to form a liquid seal area, which prevents 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 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 for 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 position corresponding to 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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