System for recovering hydrogen in ethylbenzene catalytic dehydrogenation tail gas to prepare high-purity hydrogen

Abstract

A system for recycling hydrogen in ethylbenzene catalytic dehydrogenation tail gas to prepare high-purity hydrogen comprises pressurization equipment, a gas-liquid separator, an oil remover, a first pressure swing adsorption device, a second pressure swing adsorption device and a gas conveying pump, the pressurization equipment is connected with a tail gas pipeline, and the gas-liquid separator is connected with the pressurization equipment through the pressurization pipeline. An outlet of the gas-liquid separator is connected with the degreaser through a pipeline, an outlet of the degreaser is connected with the first pressure swing adsorption device through a first pressure swing adsorption device inlet pipeline, and the first pressure swing adsorption device is provided with a first resolver pipeline, a common hydrogen extraction pipeline and a second pressure swing adsorption device connecting pipeline. The second pressure swing adsorption device is provided with a high-purity hydrogen extraction pipeline and a second analyzer pipeline, a gas conveying pump is arranged on the second analyzer pipeline, the gas-liquid separator is cylindrical, a partition plate is arranged in the gas-liquid separator and divides the gas-liquid separator into an upper cavity and a lower cavity, the lower cavity is connected with a gas pressure switching pipeline, and the gas pressure switching pipeline is connected with a gas outlet of the gas-liquid separator. A first valve and a second valve are arranged on the air pressure switching pipeline, and the air pressure switching pipeline is respectively communicated with the tail gas pipeline and the pressurizing pipeline through the first valve and the second valve.

Description

Technical Field

[0001] The invention relates to the technical field of styrene production, and in particular to a system for recovering hydrogen from tail gas of catalytic dehydrogenation of ethylbenzene to prepare high-purity hydrogen. Background Art

[0002] At present, there are two main ways to prepare styrene from ethylbenzene, one is the catalytic dehydrogenation of ethylbenzene, and the other is the oxidative dehydrogenation of ethylbenzene. The main reaction in the catalytic dehydrogenation of ethylbenzene is: The tail gas of ethylbenzene catalytic dehydrogenation contains a large amount of by-product hydrogen. In the traditional process, the hydrogen-rich tail gas is introduced into the steam boiler as boiler fuel. With the current development of fuel cells, the price of hydrogen is much higher than that of fuel gas. Therefore, recovering hydrogen from the tail gas of ethylbenzene catalytic dehydrogenation has great economic value. At present, the hydrogen in the tail gas of ethylbenzene catalytic dehydrogenation can be recovered by a single pressure swing adsorption (PSA) method to obtain general hydrogen (99.9%), which can be used for crude benzene hydrogenation in this unit. However, compared with the price of general hydrogen, the price of high-purity hydrogen (99.999%) is about twice that of general hydrogen. Therefore, when there is spare capacity of equipment or there is a gap in high-purity hydrogen in the market, further preparing high-purity hydrogen has certain economic value. The tail gas pressure of the ethylbenzene catalytic dehydrogenation method is relatively low, only about 43kPa, while in the pressure swing adsorption method, the pressure needs to reach about 2.0MPa. In this way, the catalytic dehydrogenation tail gas needs to be compressed before entering the pressure swing adsorption device. However, the tail gas of the ethylbenzene catalytic dehydrogenation method contains free water, which will condense after compression, affecting the quality of high-purity hydrogen and shortening the service life of the adsorbent for adsorption / desorption. When the existing water separator is drained, the pressure in the water separator needs to be emptied to discharge the condensed water collected in the water separator. The operation is complicated and time-consuming, and two sets of water separators need to be switched for use. Summary of the invention

[0003] In view of this, the present invention aims to propose a system for recovering hydrogen from the tail gas of ethylbenzene catalytic dehydrogenation to prepare high-purity hydrogen, which can remove condensed water produced by compression before the tail gas of ethylbenzene catalytic dehydrogenation enters the pressure swing adsorption device. When the condensed water in the water separator is full, it can be drained online without suspending work or switching to replace the gas-liquid water separator.

[0004] The invention provides a system for recovering hydrogen from tail gas of catalytic dehydrogenation of ethylbenzene to prepare high-purity hydrogen. The system comprises a pressurizing device, a gas-liquid separator, an oil remover, a first pressure swing adsorption device, a second pressure swing adsorption device and a gas transmission pump. The pressurizing device is connected with a tail gas pipeline. The gas-liquid separator and the pressurizing device are connected through the pressurizing pipeline. The outlet of the gas-liquid separator is connected with the oil remover through a pipeline. The outlet of the oil remover is connected with the first pressure swing adsorption device through an inlet pipeline of the first pressure swing adsorption device. The first pressure swing adsorption device is provided with a first resolver pipeline, a general hydrogen extraction pipeline and a second pressure swing adsorption device connecting pipeline. The second pressure swing adsorption device is provided with a high-purity hydrogen extraction pipeline and a second resolver pipeline. The second resolver gas pipeline is provided with a gas transmission pump. The gas-liquid separator is cylindrical and provided with a partition plate inside. The partition plate divides the gas-liquid separator into an upper cavity and a lower cavity. The lower cavity is connected with a switching gas pressure pipeline. The gas pressure switching pipeline is provided with a first valve and a second valve, and is respectively connected with the tail gas pipeline and the pressurizing pipeline through the first valve and the second valve.

[0005] Furthermore, a liquid level gauge is provided in the upper cavity, a pressure gauge is provided in the lower cavity, and the liquid level gauge is provided with upper and lower limits and is electrically connected to the first valve and the second valve.

[0006] Furthermore, the partition is disc-shaped with a mounting hole in the middle, an automatic valve is arranged in the mounting hole, and the automatic valve consists of a valve seat and a valve core.

[0007] Furthermore, the valve seat is cylindrical, and a cavity for accommodating the valve core is provided inside, and the cavity is divided into three parts, namely, a conical cavity, a first cylindrical cavity and a second cylindrical cavity from top to bottom.

[0008] Furthermore, the cone angle of the inverted cone cavity is 30-45°, and the diameter D1 of the first cylindrical cavity is equal to the minimum diameter D 小 The diameter D2 of the second cylindrical cavity is smaller than the diameter D1 of the first cylindrical cavity, preferably D 2＝ 0.5 to 0.8 times D1, an annular support block is formed between the second cylindrical cavity and the first cylindrical cavity.

[0009] Furthermore, the side wall of the first cylindrical cavity is provided with a plurality of positioning grooves, the height of the positioning grooves is smaller than the height of the first cylindrical cavity, and the bottom of the positioning grooves is flush with the bottom of the first cavity.

[0010] Furthermore, the valve core includes a valve stem, a counterweight installed at the upper end of the valve stem, and a spring, an annular gasket and an annular limiting ring installed at the lower end of the valve stem.

[0011] Furthermore, the valve stem is composed of three parts, namely a counterweight block seat, a conical valve plug and a guide rod; a conical sealing surface is provided on the side of the conical valve plug, and a mounting hole is provided in the middle of the counterweight block.

[0012] Furthermore, the guide rod is provided with a plurality of positioning blocks.

[0013] Furthermore, a boss is provided at the lower end of the inverted conical cavity, and the boss is arranged so that the diameter D1 of the first cylindrical cavity is smaller than the minimum diameter D 小 , forming a first sealing surface, on which a shaped sealing gasket is arranged, and correspondingly, a second sealing surface corresponding to the first sealing surface is arranged on the side surface of the valve plug of the valve stem.

[0014] Beneficial effects:

[0015] The present invention provides a system for recovering hydrogen from tail gas of ethylbenzene catalytic dehydrogenation to prepare high-purity hydrogen. By adding a second pressure swing adsorption device, when the amount of general hydrogen exceeds the production demand or there is a gap in the high-purity hydrogen market, high-purity hydrogen can be produced to increase economic value; by arranging upper and lower chambers in a gas-liquid separator, the upper chamber is a working chamber, and the lower chamber is a liquid separation chamber, the liquid separation chamber is connected with a switching air pressure pipeline, the air pressure switching pipeline is provided with a first valve and a second valve, and is respectively connected to the tail gas pipeline and the pressurized pipeline through the first valve and the second valve; when the condensate liquid level in the working chamber reaches the upper limit, the water is drained online without suspending the generation or adding a replacement gas-liquid separator; the pressure in the tail gas pipeline is in a low-pressure state of (43kpa), which can reduce the hydrogen content of the condensate in the liquid separation chamber, making the condensate discharge safer. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of a system for recovering hydrogen and preparing high-purity hydrogen in the present invention;

[0017] Figure 2 This is a schematic diagram of the structure of a gas-liquid separator in an embodiment of the present invention;

[0018] Figure 3 for Figure 2 Section view along AA direction;

[0019] Figure 4 This is a schematic diagram of an automatic valve installed on a partition in an embodiment of the present invention;

[0020] Figure 5 It is a vertical cross-sectional view of the automatic valve in the embodiment of the present invention when it is closed;

[0021] Figure 6 It is a vertical cross-sectional view of the automatic valve in the embodiment of the present invention when it is opened;

[0022] Figure 7This is a schematic diagram of the valve seat structure in an embodiment of the present invention;

[0023] Figure 8 This is a front view of the valve seat in the embodiment of the present invention;

[0024] Fig. 9 for Figure 7 Section view along BB direction;

[0025] Fig.10 for Figure 7 Sectional view along CC direction;

[0026] Fig.11 A schematic diagram of the valve core structure in an embodiment of the present invention;

[0027] Fig.12 for Fig.11 Explosion diagram of

[0028] Fig.13 A schematic diagram of a valve seat structure in another embodiment of the present invention;

[0029] Fig.14 for Fig.12 Sectional view along DD direction;

[0030] Fig.15 This is a schematic diagram of the valve core structure in another embodiment of the present invention.

[0031] Among them, the reference numerals in the figure are: 100, hydrogen recovery system for preparing high-purity hydrogen; 1, pressurizing equipment; 11, tail gas pipeline; 111, first valve; 12, pressurizing pipeline; 121, second valve; 2, gas-liquid separator; 21, pressurized gas inlet; 22, pressurized gas outlet; 23, supporting foot; 24, partition; 241, mounting hole; 25, automatic valve; 251, valve seat; 2511, first cylindrical cavity; 2512, first cylindrical cavity; 2513, positioning groove; 2514, support block; 2515, second cylindrical cavity; 2516, boss; 25161, first sealing surface; inverted conical cavity; 2512, 252, valve core; 2521, valve stem, 25 211. Guide rod; 25212. Conical valve plug; 25213. Counterweight seat; 25214. Positioning block; 2522. Counterweight; 25221. Mounting hole; 2523. Spring; 2524. Gasket; 2525. Limit ring; 26. Liquid level gauge; 27. Pressure gauge; 271. Third valve; 28. Switching air pressure pipeline; 3. Oil remover; 4. First pressure swing adsorption device; 41. First pressure swing adsorption device inlet pipeline; 42. General hydrogen production pipeline; 43. First analytical gas outlet pipeline; 44. Second pressure swing adsorption connecting pipeline; 441. Fourth valve; 5. Second pressure swing adsorption device; 51. High-purity hydrogen production pipeline; 52. Second analytical gas outlet pipeline; 6. Booster pump. DETAILED DESCRIPTION

[0032] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification. The methods described are all conventional methods unless otherwise specified, and the raw materials described can be obtained from public commercial channels unless otherwise specified.

[0033] The term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0034] like Figure 1 As shown, this embodiment provides a system 100 for recovering hydrogen from tail gas of catalytic dehydrogenation of ethylbenzene to prepare high-purity hydrogen, comprising a pressurizing device 1, a gas-liquid separator 2, a deoiler 3, a first pressure swing adsorption device 4, a second pressure swing adsorption device 5 and a gas delivery pump 6. The pressurizing device 1 is connected to a tail gas pipeline 11 and a pressurizing pipeline 13. The dehydrogenated tail gas enters the pressurizing device 1 through the tail gas pipeline 11, enters the gas-liquid separator 2 through the pressurizing pipeline 12 after being pressurized, and the dehydrated gas enters the deoiler 3. After deoiling, the gas enters the first pressure swing adsorption device 4 through the inlet pipeline 41 of the first pressure swing adsorption device for adsorption purification. A switching gas pressure pipeline 28 is provided on the gas-liquid separator 2. The switching gas pressure pipeline 28 is separated by a first valve 111 and a second valve 121. The gas-liquid separator 2 is connected to the tail gas pipeline 11 and the pressurized pipeline 12 respectively. A drainage pipeline 27 is also provided at the bottom of the gas-liquid separator 2. A third valve 271 is provided on the drainage pipeline 27. The first pressure swing adsorption device 4 is also provided with a general hydrogen extraction pipeline 42, a first analytical gas outlet pipeline 43 and a second pressure swing adsorption connecting pipeline 44. A fourth valve 441 is provided on the second pressure swing adsorption connecting pipeline 44. General hydrogen can be transported to the second pressure swing adsorption device 5 for further adsorption and purification through the second pressure swing adsorption connecting pipeline 44. The second pressure swing adsorption device 5 is provided with a high-purity hydrogen extraction pipeline 51 and a second analytical gas outlet pipeline 52. A gas delivery pump 6 is provided on the second analytical gas outlet pipeline 52. The low-purity hydrogen (about 99%) after analysis is transported to the first pressure swing adsorption device 4 for adsorption and purification through the gas delivery pump 6.

[0035] like Figures 2-3 As shown, the gas-liquid separator 2 is cylindrical, with supporting feet 23 at the bottom and a partition 24 inside. The partition 24 divides the gas-liquid separator 2 into two upper and lower cavities. The upper cavity is a working cavity, with a pressurized gas inlet 21 in the middle and a pressurized gas outlet 22 at the top, and a liquid level meter 26 in the working cavity; the lower cavity is a liquid separation cavity, with a pressure gauge 27 in the liquid separation cavity, a switching air pressure pipeline inlet 22 on the side wall, and a condensate discharge port 24 on the bottom wall, which is connected to the condensate discharge pipeline.

[0036] The liquid level meter 26 is provided with an upper limit and a lower limit of the liquid level, and the liquid level meter 26 is electrically connected to the first valve 111 and the second valve 121 through a controller (not shown in the figure).

[0037] like Figure 4 As shown, the partition 24 is disc-shaped, and a circular valve installation hole 241 is provided in the middle. Figure 5 As shown, an automatic valve 25 is installed in the valve installation hole 241. The automatic valve 25 is composed of a valve core 252 and a valve seat 251.

[0038] like Figures 6 to 9 As shown, the valve seat 251 is cylindrical, and has a cavity for accommodating the valve core 252 inside. The cavity is divided into three parts, from top to bottom, into an inverted cone cavity 2511, a first cylindrical cavity 2512, and a second cylindrical cavity 2515. The cone angle of the inverted cone cavity 2511 is 30-45°, and the diameter D1 of the first cylindrical cavity 2512 is equal to the minimum diameter D1 of the inverted cone cavity 2511. 小 The diameter D2 of the second cylindrical cavity 2515 is smaller than the diameter D1 of the first cylindrical cavity 2512, preferably D 2＝ 0.5 to 0.8 times D1, an annular support block 2514 is formed between the second cylindrical cavity 2515 and the first cylindrical cavity 2512.

[0039] In some embodiments, a plurality of positioning grooves 2513 are provided on the sidewall of the first cylindrical cavity 2512 . The height of the positioning grooves 2513 is smaller than the height of the first cylindrical cavity 2512 , and the bottom of the positioning grooves 2513 is flush with the bottom of the first cavity 2512 .

[0040] like Figures 10-11 As shown, the valve core 252 includes a valve stem 2521, a counterweight 2522 installed at the upper end of the valve stem 2521, and a spring 2523, an annular gasket 2524 and an annular limit ring 2525 installed at the lower end of the valve stem; the valve stem 2521 is composed of three parts, namely a square counterweight seat 25213, a conical valve plug 25212 and a cylindrical guide rod 25211; a conical sealing surface 252121 is provided on the side of the conical valve plug 25212, and a mounting hole 25221 is provided in the middle of the counterweight 2522, and the counterweight 2522 can be installed on the valve stem 2521 through the mounting hole 25221 and the counterweight seat 25213.

[0041] When the valve core 252 is installed on the valve seat 251, the conical valve plug 25212 can be accommodated in the inverted conical cavity 2511, and the cooperation between them can play a sealing role. The spring 2523 can be accommodated in the first cylindrical cavity 2512, the cylindrical guide rod 25211 can pass through the second cylindrical cavity 2515, the annular gasket 2524 can be carried on the ring-shaped support block 2514, and the limit ring 2525 is sleeved on the outer position of the guide rod 25211 passing through the second cylindrical cavity 2515. The outer diameter of the limit ring 2525 is larger than the diameter of the second cylindrical cavity 2515, but when the valve core 252 is bounced open by the spring 2523, the valve core 252 can be limited from leaving the valve seat 251.

[0042] In some embodiments, an inverted cone-shaped sealing gasket (not shown in the figure) is provided in the inverted cone-shaped cavity 2511 to provide a better sealing effect.

[0043] In some embodiments, a plurality of positioning blocks 25214 are provided on the guide rod 25211. The positioning blocks 25214 can be accommodated in the positioning grooves 2513, which can limit the rotation of the valve core 252 in the circumferential direction, thereby preventing the conical valve plug 25212 and the inverted conical cavity 2511 from rotating and affecting the sealing effect.

[0044] like Figures 12-14 As shown, in some embodiments, a boss 2516 is provided at the lower end of the inverted conical cavity 2511, and the boss 2516 is arranged so that the diameter D1 of the first cylindrical cavity 2512 is smaller than the minimum diameter D1 of the inverted conical cavity 2511. 小 , forming a circular ring-shaped first sealing surface 2516, a circular ring-shaped sealing gasket (not shown in the figure) is provided on the first sealing surface 25151, and accordingly, a second sealing surface 252122 corresponding to the first sealing surface 25151 is provided on the side of the valve plug 25212 of the valve stem 2521.

[0045] It should be noted that when the valve core 252 is installed on the valve seat 251, there is no air pressure in the working chamber, or the pressures in the working chamber and the liquid separation chamber are equal, when the water level in the working chamber reaches the upper limit, under the elastic force of the spring 2523, the sealing surface of the valve plug 25212 is away from the sealing surface of the valve seat 251. At this time, it is in a connected state, and condensed water can flow from the working chamber into the liquid separation chamber. When the pressure on the upper surface of the valve plug 25212 is greater than the pressure when the water level in the working chamber reaches the upper limit, the spring 2523 is compressed, and the sealing surface of the valve plug 25212 contacts the sealing surface of the valve seat 251. At this time, it is in a sealed state, and the pressure can be adjusted by the counterweight 2522.

[0046] Working principle of the system 100 for recovering hydrogen from tail gas of ethylbenzene catalytic dehydrogenation to prepare high-purity hydrogen:

[0047] After the dehydrogenated tail gas with a pressure of about 40 kPa is compressed by the pressurizing device 1, the pressure rises to about 2 MP. At this time, the free water in the dehydrogenated tail gas will become liquid, pass through the gas-liquid separator 2, remove the water in the compressed tail gas, and then enter the deoiler 3 to remove the high carbon impurities in the tail gas, and finally enter the first pressure swing adsorption device. The hydrogen that meets the quality standard (purity 99.9%) is collected through the general hydrogen production pipeline 42, and the desorption gas is collected through the desorption gas pipeline 43. When the amount of general hydrogen exceeds the production needs or there is a gap in the high-purity hydrogen market, the fourth valve 441 is opened, and the general hydrogen is transported to the second pressure swing adsorption device 5 through the second pressure swing adsorption connecting pipeline 44. After the secondary pressure swing adsorption, the high-purity hydrogen with a content of 99.999 is collected through the high-purity hydrogen production pipeline 51, and the low-purity hydrogen is transported to the first pressure swing adsorption device 4 through the second desorption gas pipeline 52 and the delivery pump 6 for adsorption and purification.

[0048] During normal operation, the valve core 252 is closed and the spring 2523 is in a compressed state. When the reading of the liquid level gauge 26 in the gas-liquid separator 2 reaches the upper limit, the linkage control switches the second valve 121 on the air pressure pipeline to open. At this time, the pressurized tail gas enters the liquid separation chamber. When the air pressure in the liquid separation chamber is equal to the air pressure in the working chamber, the elastic force of the spring 2523 causes the valve stem 2521 to move upward, and the valve plug 25212 moves away from the valve seat 251 to form a passage. At this time, the condensed water in the working chamber flows into the liquid separation chamber. When the reading of the liquid level gauge 26 reaches the lower limit, the linkage control second valve 121 is closed and the first valve 111 is opened. This is because the air pressure product of the liquid separation chamber is sharply reduced. Under the pressure of the working chamber air pressure, the valve plug 25212 overcomes the elastic force of the spring 2523 and moves toward the valve seat 251 to form a seal. When the pressure of the pressure gauge 27 does not decrease (about 43kpa), the first valve 111 is closed, the condensed water discharge port is opened, and the condensed water discharge port is closed after the condensed water is discharged. The present invention can also extract the hydrogen in the liquid separation chamber through the low pressure (43 kPa) in the tail gas pipeline 11, so as to avoid a large amount of hydrogen contained in the subsequent water discharge through the condensate removal pipeline, which may cause safety hazards.

[0049] The system 100 for recovering hydrogen from the tail gas of ethylbenzene catalytic dehydrogenation to prepare high-purity hydrogen of the present invention can produce high-purity hydrogen according to market conditions and increase economic value by providing a second pressure swing adsorption device 5. The valve 25 provided by the present invention can remove the condensed water in the gas-liquid separator 2 without interrupting the operation of the equipment when the condensed water level in the gas-liquid separator 2 reaches the upper limit, and at the same time can reduce the hydrogen content in the condensed water, which is safer and more reliable.

[0050] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A system for recovering hydrogen from tail gas of catalytic dehydrogenation of ethylbenzene to prepare high-purity hydrogen, comprising a pressurizing device, a gas-liquid separator, an oil remover, a first pressure swing adsorption device, a second pressure swing adsorption device and a gas pump, wherein the pressurizing device is connected to a tail gas pipeline, the gas-liquid separator and the pressurizing device are connected through a pressurizing pipeline, the outlet of the gas-liquid separator is connected to the oil remover through a pipeline, the outlet of the oil remover is connected to the first pressure swing adsorption device through the first pressure swing adsorption device inlet pipeline, the first pressure swing adsorption device is provided with a first resolver pipeline, a general hydrogen production pipeline and a second pressure swing adsorption device connecting pipeline, the second pressure swing adsorption device is provided with a high-purity hydrogen production pipeline and a second resolver pipeline, and the second resolved gas pipeline is provided with a gas pump, characterized in that The gas-liquid separator is cylindrical and has a partition inside. The partition divides the gas-liquid separator into an upper and lower cavity. The upper cavity is a working cavity, and the lower cavity is a liquid separation cavity. A switching air pressure pipeline is connected to the liquid separation cavity. A first valve and a second valve are provided on the air pressure switching pipeline, which are respectively connected to the exhaust gas pipeline and the pressurized pipeline through the first valve and the second valve.

2. The hydrogen recovery system in tail gas from ethylbenzene catalytic dehydrogenation as claimed in claim 1, characterized in that: A liquid level gauge is arranged in the upper cavity, a pressure gauge is arranged in the lower cavity, the liquid level gauge is provided with upper and lower limits, and is electrically connected with the first valve and the second valve.

3. The hydrogen recovery system in tail gas from ethylbenzene catalytic dehydrogenation as claimed in claim 1, characterized in that: The partition is in the shape of a disc, with a mounting hole in the middle. An automatic valve is arranged in the mounting hole, and the automatic valve consists of a valve seat and a valve core.

4. The hydrogen recovery system in tail gas from ethylbenzene catalytic dehydrogenation as claimed in claim 1, characterized in that: The valve seat is cylindrical, and a cavity for accommodating the valve core is provided inside. The cavity is divided into three parts, which are a conical cavity, a first cylindrical cavity and a second cylindrical cavity from top to bottom.

5. The hydrogen recovery system in tail gas from catalytic dehydrogenation of ethylbenzene as claimed in claim 4, characterized in that: The cone angle of the inverted cone cavity is 30-45°, and the diameter D1 of the first cylindrical cavity is equal to the minimum diameter D 小 The diameter D2 of the second cylindrical cavity is smaller than the diameter D1 of the first cylindrical cavity, preferably D2 = 0.5 to 0.8 times D1, and an annular support block is formed between the second cylindrical cavity and the first cylindrical cavity.

6. The hydrogen recovery system in tail gas from catalytic dehydrogenation of ethylbenzene as claimed in claim 4, characterized in that: The side wall of the first cylindrical cavity is provided with a plurality of positioning grooves, the height of the positioning grooves is smaller than the height of the first cylindrical cavity, and the bottom of the positioning grooves is flush with the bottom of the first cavity.

7. The hydrogen recovery system in tail gas from catalytic dehydrogenation of ethylbenzene as claimed in claim 6, characterized in that: The valve core comprises a valve stem, a counterweight block installed at the upper end of the valve stem, and a spring, an annular gasket and an annular limiting ring installed at the lower end of the valve stem.

8. The hydrogen recovery system in tail gas from catalytic dehydrogenation of ethylbenzene as claimed in claim 7, characterized in that: The valve stem is composed of three parts, namely a counterweight block seat, a conical valve plug and a guide rod; a conical sealing surface is provided on the side of the conical valve plug, and a mounting hole is provided in the middle of the counterweight block.

9. The hydrogen recovery system in tail gas from catalytic dehydrogenation of ethylbenzene as claimed in claim 8, characterized in that: A plurality of positioning blocks are arranged on the guide rod.

10. The hydrogen recovery system in tail gas from ethylbenzene catalytic dehydrogenation as claimed in claim 9, characterized in that: The lower end of the inverted conical cavity is also provided with a boss, and the arrangement of the boss makes the diameter D1 of the first cylindrical cavity smaller than the minimum diameter D 小 , forming a first sealing surface, on which a shaped sealing gasket is arranged, and correspondingly, a second sealing surface corresponding to the first sealing surface is arranged on the side surface of the valve plug of the valve stem.

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