A gas recovery device and method for a polypropylene process

Abstract

The present invention discloses a gas recovery device and a recovery method for a polypropylene process. The gas recovery device for the polypropylene process includes a recovery housing, a condenser tube group, a communication part, an inlet pipe, a first discharge pipe, a second discharge pipe, and a third discharge pipe. The recovery housing includes a first cooling cavity and a second cooling cavity, and the second cooling cavity is located above the first cooling cavity. The condenser tube group sequentially passes through the second cooling cavity and the first cooling cavity along a first direction. The inlet pipe, the first discharge pipe, and the second discharge pipe are sequentially arranged along a direction opposite to the first direction, and the lower part of the second cooling cavity is communicated with the third discharge pipe. On the one hand, the cooling cavities are arranged in an overlapping manner, occupying a small space. On the other hand, the above-mentioned inlet pipe, first discharge pipe, and second discharge pipe are sequentially matched with the relatively high-temperature part to the relatively low-temperature part of the condenser tube group, so that the direction of the condenser tube group is opposite to the direction of the recovered gas, with high utilization rate and maximizing the cooling effect.

Description

Technical Field

[0001] The present invention relates to the technical field of condensation separation structures, and particularly to a gas recovery device and a recovery method for a polypropylene process. Background Art

[0002] In the production process of polypropylene, gas recovery is an important link to achieve efficient utilization of resources, reduce costs, and reduce environmental emissions. Specifically, in the polypropylene production process, gas recovery can separate the unreacted gas, volatile organic compounds, and by-product gas (collectively referred to as recovered gas) discharged from the reactor and reuse them. Usually, the methods of "multi-stage condensation" or "cryogenic separation" are selected.

[0003] "Multi-stage condensation" means using multiple condensation devices to sequentially condense the recovered gas step by step, thereby completing the separation of the gas. The required condensation devices are relatively many, and the overall occupied space is large; "cryogenic separation" means achieving complete gas-liquid separation through extremely low-temperature cooling, which requires complex cryogenic equipment and refrigerant systems and has the disadvantage of high energy consumption. It can be seen that the existing condensation separation technology for polypropylene has the defects of large occupied space and high energy consumption. Summary of the Invention

[0004] The purpose of the present invention is to provide a gas recovery device and a recovery method for a polypropylene process, so as to solve the problems of large occupied space and high energy consumption existing in the cooling and separation of the recovered gas in the polypropylene production process by the existing condensation separation equipment.

[0005] To achieve this purpose, the present invention adopts the following technical solutions:

[0006] A gas recovery device for a polypropylene process includes a recovery housing and a condensation pipe group. The recovery housing includes a first cooling cavity and a second cooling cavity, and the second cooling cavity is located above the first cooling cavity; the first cooling cavity and the second cooling cavity are connected through a communication part;

[0007] The condensation pipe group sequentially passes through the second cooling cavity and the first cooling cavity along a first direction;

[0008] The first cooling cavity is connected with an inlet pipe; the second cooling cavity is respectively connected with a first discharge pipe for discharging light gas, a second discharge pipe for discharging heavy gas, and a third discharge pipe for discharging propylene;

[0009] Wherein, the inlet pipe, the first discharge pipe, and the second discharge pipe are sequentially arranged along a direction opposite to the first direction. The second discharge pipe is connected to the upper part of the second cooling cavity, and the third discharge pipe is connected to the lower part of the second cooling cavity.

[0010] Optionally, the recovery housing includes a first end and a second end that are oppositely arranged. After passing through the second cooling cavity from the first end, the condenser tube group passes out from the second end and passes through the first cooling cavity from the second end;

[0011] The intake pipe is arranged below the first cooling cavity and close to the first end; the first discharge pipe is arranged above the second cooling cavity and close to the second end; the second discharge pipe is arranged above the second cooling cavity and close to the first end; the third discharge pipe is close to the first end.

[0012] Optionally, the recovery housing further includes an intermediate cavity located between the first cooling cavity and the second cooling cavity;

[0013] The communication part includes a first pressure reducing valve arranged in the intermediate cavity, and a second pressure reducing valve is arranged in the intermediate cavity; the inlet of the first pressure reducing valve is communicated with the first cooling cavity, and the outlet of the first pressure reducing valve is communicated with the second cooling cavity; the inlet of the second pressure reducing valve is communicated with the second cooling cavity, and the outlet of the second pressure reducing valve is communicated with the intermediate cavity;

[0014] The inlet of the third discharge pipe is communicated with the intermediate cavity.

[0015] Optionally, both the first pressure reducing valve and the second pressure reducing valve include a valve body, and the valve body includes an inlet channel, a buffer cavity, a pressure reducing cavity, and an outlet channel that are sequentially communicated;

[0016] A throttle port is formed between the buffer cavity and the pressure reducing cavity. The valve body is movably connected with an adjusting rod, and a throttle block is installed at the position of the adjusting rod corresponding to the throttle port; a throttle channel is formed between the throttle block and the throttle port, and the throttle channel communicates the buffer cavity and the pressure reducing cavity, and the caliber of the throttle channel is positively correlated with the distance between the throttle block and the throttle port.

[0017] Optionally, the buffer cavity includes a first buffer sub-cavity and a second buffer sub-cavity; one end of the pressure reducing cavity is communicated with the first buffer sub-cavity, and the other end of the pressure reducing cavity is communicated with the second buffer sub-cavity;

[0018] The throttle port includes a first throttle channel arranged between the first buffer sub-cavity and the pressure reducing cavity, and a second throttle channel arranged between the second buffer sub-cavity and the pressure reducing cavity;

[0019] The throttle block includes a first throttle part corresponding to the first throttle channel and a second throttle part corresponding to the second throttle channel.

[0020] Optionally, the first throttle channel is closer to the adjusting rod than the second throttle channel;

[0021] The first throttle channel is smaller in size than the second throttle channel, and the first throttle portion is smaller in size than the second throttle portion.

[0022] Optionally, the first pressure reducing valve is disposed near the second end portion, and the adjusting rod corresponding to the first pressure reducing valve protrudes from the end portion of the valve body toward the inside of the intermediate cavity;

[0023] The second pressure reducing valve is disposed near the first end portion, and the adjusting rod corresponding to the second pressure reducing valve protrudes from the end portion of the valve body toward the inside of the intermediate cavity;

[0024] An adjusting device for driving the adjusting rod to move is disposed in the intermediate cavity.

[0025] Optionally, the adjusting device includes a hollow motor disposed in the intermediate cavity, and a rotating rod passes through and is fixedly connected to the inner ring of the hollow motor;

[0026] One end of the rotating rod is threadedly connected with a first pushing block, and the other end of the rotating rod is threadedly connected with a second pushing block; the first pushing block is fixedly connected to the adjusting rods corresponding to the plurality of first pressure reducing valves respectively; the second pushing block is fixedly connected to the adjusting rods corresponding to the plurality of second pressure reducing valves respectively.

[0027] Optionally, a conical separation membrane is disposed in the second cooling cavity, and the separation membrane separates the first discharge pipe from the second cooling cavity;

[0028] The separation membrane includes a front membrane body facing the second end portion and a rear membrane body away from the second end portion; both the front membrane body and the rear membrane body are inclined.

[0029] A recovery method for a polypropylene process, applied to the gas recovery device for the polypropylene process as described above, includes:

[0030] Introducing a recovery gas into the inlet pipe and introducing a refrigerant into the condenser group;

[0031] Recovering light components from the first discharge pipe; recovering heavy components from the second discharge pipe; recovering propylene from the third discharge pipe.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The gas recovery device and method for the polypropylene process provided by the present invention. The recovered gas enters the first cooling cavity below from the inlet pipe. Under the action of the condensing tube group, most of the light components are cooled and separated. The separated light components are discharged from the recovery housing through the communication part and the first discharge pipe. The remaining recovered gas continues to be cooled in the second cooling cavity under the action of the condensing tube group to achieve the cooling and separation of the heavy components. The separated heavy components are discharged from the recovery housing through the second discharge pipe. Finally, in the second cooling cavity, propylene flows downward to be discharged from the third discharge pipe. In the above solution, the cooling cavities are arranged in an overlapping manner, occupying a small space. And the condensing tube group passes through the second cooling cavity from one end of the recovery housing and passes through the first cooling cavity from the other end of the recovery housing, in the opposite direction to the flow direction of the recovered gas, with high utilization rate. And with the temperature gradient setting, the relatively low-temperature part matches the second cooling cavity, and the relatively high-temperature part matches the first cooling cavity to maximize the cooling effect. Therefore, this solution has the advantages of small occupied space and low energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0035] The structures, ratios, sizes, etc. shown in the drawings of this specification are only used to cooperate with the content disclosed in the specification for those familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention. Therefore, they do not have technical essence. Any modification of the structure, change of the proportional relationship or adjustment of the size, without affecting the effects that the present invention can produce and the purposes that can be achieved, should still fall within the scope that can be covered by the technical content disclosed in the present invention.

[0036] Figure 1 It is a schematic diagram of the overall structure of the gas recovery device for the polypropylene process provided by the embodiment of the present invention;

[0037] Figure 2 It is a schematic diagram of the partial explosion structure of the gas recovery device for the polypropylene process provided by the embodiment of the present invention;

[0038] Figure 3 It is a schematic diagram of the first partial sectional structure of the gas recovery device for the polypropylene process provided by the embodiment of the present invention;

[0039] Figure 4 It is a schematic diagram of the second partial sectional structure of the gas recovery device for the polypropylene process provided by the embodiment of the present invention;

[0040] Figure 5 A partial structural schematic diagram of the gas recovery device for the polypropylene process provided by the embodiment of the present invention;

[0041] Figure 6 A cross-sectional structural schematic diagram of the first pressure reducing valve and the second pressure reducing valve in the embodiment of the present invention;

[0042] Figure 7 is Figure 6 A partial enlarged structural schematic diagram at A;

[0043] Illustration: 100, recovery housing; 101, first cooling cavity; 102, second cooling cavity; 103, intermediate cavity; 110, first end; 120, second end;

[0044] 200, condenser tube group; 300, inlet pipe; 410, first discharge pipe; 420, second discharge pipe; 430, third discharge pipe;

[0045] 500, connecting part; 510, first pressure reducing valve; 520, second pressure reducing valve; 530, valve body; 531, inlet channel; 532, buffer cavity; 5321, first buffer sub-cavity; 5322, second buffer sub-cavity; 533, pressure reducing cavity; 534, outlet channel; 535, throttle orifice; 5351, first throttle channel; 5352, second throttle channel; 540, adjusting rod; 541, throttle block; 5411, first throttle part; 5412, second throttle part;

[0046] 600, adjusting device; 610, hollow motor; 620, rotating rod; 630, first pushing block; 640, second pushing block; 700, separation membrane; 710, front membrane body; 720, rear membrane body. Detailed implementation manners

[0047] In order to make the invention object, features, and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the embodiments described below are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0048] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "upper", "lower", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention. It should be noted that when a component is considered to be "connected" to another component, it can be directly connected to the other component or there may be intermediate components present simultaneously.

[0049] The technical solution of the present invention will be further described below with reference to the drawings and through specific embodiments.

[0050] Embodiment 1:

[0051] The gas recovery device for the polypropylene process provided in this embodiment is applicable to the scenario of recovering the waste gas generated in the polypropylene process. The gas recovery device in this embodiment can condense and recover the recovered gas (i.e., waste gas), separating it into light components, heavy components, and propylene. The light components include, but are not limited to, hydrogen, methane, etc., and the heavy components include, but are not limited to, ethane, etc. In this embodiment, by improving the structure of the gas recovery device for the polypropylene process, its structure is made more compact and the utilization rate is higher.

[0052] As Figures 1 to 3 shown, the gas recovery device for the polypropylene process in this embodiment includes a recovery housing 100 and a condenser tube group 200. The recovery housing 100 includes a first cooling cavity 101 and a second cooling cavity 102, and the second cooling cavity 102 is located above the first cooling cavity 101; the first cooling cavity 101 and the second cooling cavity 102 are connected through a communication part 500; the condenser tube group 200 sequentially passes through the second cooling cavity 102 and the first cooling cavity 101 along a first direction; the condenser tube group 200 includes a plurality of pipes (not shown in the figure) for transporting a refrigerant. The pipes are arranged along the first direction and are used to transport the refrigerant. Cooperating with external structures such as a condenser and a compressor, the transportation of the refrigerant can be realized. The principle of transporting the refrigerant is well-known to those skilled in the art and will not be introduced in this embodiment.

[0053] The first cooling cavity 101 is communicated with an intake pipe 300; the second cooling cavity 102 is respectively communicated with a first discharge pipe 410 for discharging light gas, a second discharge pipe 420 for discharging heavy gas, and a third discharge pipe 430 for discharging propylene; wherein, the intake pipe 300, the first discharge pipe 410 and the second discharge pipe 420 are arranged in sequence along the direction opposite to the first direction, the second discharge pipe 420 is communicated above the second cooling cavity 102, and the third discharge pipe 430 is communicated below the second cooling cavity 102. It can be understood that the high-temperature and high-pressure recovered gas first enters the lower first cooling cavity 101 from the intake pipe 300. Through the preliminary cooling of the condenser tube group 200, the light components with smaller density are discharged from the first discharge pipe 410, realizing the cooling and separation of most of the light components. The separated light components flow along the direction opposite to the first direction. Due to the smaller density, they are located in the upper layer and can be discharged from the first discharge pipe 410. The remaining heavy components and propylene continue to flow in the second cooling cavity 102. The remaining heavy components are heavier than propylene and are located in the upper layer, and can be discharged from the second discharge pipe 420, realizing the temperature reduction and separation of the heavy components.

[0054] Specifically, for the gas recovery device of the polypropylene process in this embodiment, the high-temperature and high-pressure recovered gas enters the lower first cooling cavity 101 from the intake pipe 300. Under the action of the condenser tube group 200, the cooling and separation of most of the light components are realized. The separated light components are discharged from the recovery housing 100 through the communication part 500 and the first discharge pipe 410; the remaining recovered gas continues to be cooled under the action of the condenser tube group 200 in the second cooling cavity 102, realizing the cooling and separation of the heavy components. The separated heavy components are discharged from the recovery housing 100 through the second discharge pipe 420; finally, in the second cooling cavity 102, the propylene flows downward to be discharged from the third discharge pipe 430. In the above solution, the cooling cavities are arranged in an overlapping manner, occupying a small space. Moreover, the condenser tube group 200 passes through the second cooling cavity 102 from one end of the recovery housing 100 and passes through the first cooling cavity 101 from the other end of the recovery housing 100, opposite to the flow direction of the recovered gas, promoting the heat exchange between the recovered gas and the refrigerant, with high utilization rate. With the temperature gradient setting, the relatively low-temperature part matches the second cooling cavity 102, and the relatively high-temperature part matches the first cooling cavity 101, realizing the maximization of the cooling effect. Therefore, this solution has the advantages of small occupied space and low energy consumption.

[0055] Such as Figures 1 to 4As shown, the recovery housing 100 includes a first end 110 and a second end 120 that are oppositely arranged. After the condenser tube group 200 passes through the second cooling cavity 102 from the first end 110, it passes out from the second end 120 and passes through the first cooling cavity 101 from the second end 120; the intake pipe 300 is arranged below the first cooling cavity 101 and is close to the first end 110; the first discharge pipe 410 is arranged above the second cooling cavity 102 and is close to the second end 120; the second discharge pipe 420 is arranged above the second cooling cavity 102 and is close to the first end 110; the third discharge pipe 430 is close to the first end 110.

[0056] It can be understood that the above design effectively realizes the countercurrent heat exchange of the recovered gas by passing the condenser tube group 200 through the two-stage cooling cavities. Specifically, the high-temperature and high-pressure recovered gas enters from below the first cooling cavity 101 and flows along the relatively high-temperature part of the condenser tube group 200 to directly exchange heat with the refrigerant. Light components such as hydrogen have a low boiling point and low density under the same pressure and can enter the first discharge pipe 410 in a gaseous state. Subsequently, the remaining recovered gas continues to be further cooled in the second cooling cavity 102 with the relatively low-temperature part of the condenser tube group 200 to achieve efficient separation of light components, heavy components, and propylene. The structure where both ends of the condenser tube group 200 penetrate makes full use of the temperature gradient characteristics of the condenser tube group 200, matching its high-temperature section with the first cooling cavity 101 and its low-temperature section with the second cooling cavity 102, ensuring that the utilization efficiency of the refrigerant is maximized. At the same time, through this temperature gradient distribution, the cooling process can be completed within a smaller equipment volume and effectively reduces the overall energy consumption.

[0057] Furthermore, as Figure 3 and Figure 4 shown, the recovery housing 100 further includes an intermediate cavity 103 located between the first cooling cavity 101 and the second cooling cavity 102; the communication part 500 includes a first pressure reducing valve 510 arranged in the intermediate cavity 103, and a second pressure reducing valve 520 is arranged in the intermediate cavity 103; the inlet of the first pressure reducing valve 510 is communicated with the first cooling cavity 101, and the outlet of the first pressure reducing valve 510 is communicated with the second cooling cavity 102; the inlet of the second pressure reducing valve 520 is communicated with the second cooling cavity 102, and the outlet of the second pressure reducing valve 520 is communicated with the intermediate cavity 103; the inlet of the third discharge pipe 430 is communicated with the intermediate cavity 103.

[0058] It can be understood that the recycled gas first enters from the first cooling cavity 101. After passing through the first pressure reducing valve 510, its pressure is initially reduced and it enters the second cooling cavity 102. At this time, the function of the first pressure reducing valve 510 is to reduce the temperature and pressure of the recycled gas, so as to provide suitable thermodynamic conditions for the separation of light components and avoid the liquefaction of light components. The remaining recycled gas after separation is further cooled in the second cooling cavity 102, so that the lowest temperature part of the condenser tube group 200 can liquefy propylene, separating the heavy components from the propylene. After the propylene flows into the second pressure reducing valve 520, it is depressurized and discharged through the third discharge pipe 430 in a gaseous state without mixing with other heavy components, improving the recovery purity of propylene, reducing the impact load inside the equipment, and helping to improve the stability and efficiency of separation.

[0059] Specifically, as Figures 4 to 7 shown, both the first pressure reducing valve 510 and the second pressure reducing valve 520 include a valve body 530. The valve body 530 includes an inlet passage 531, a buffer cavity 532, a pressure reducing cavity 533, and an outlet passage 534 that are connected in sequence; a throttle orifice 535 is formed between the buffer cavity 532 and the pressure reducing cavity 533. A regulating rod 540 is movably connected to the valve body 530, and a throttle block 541 is installed at the position of the regulating rod 540 corresponding to the throttle orifice 535; a throttle passage is formed between the throttle block 541 and the throttle orifice 535. The throttle passage connects the buffer cavity 532 and the pressure reducing cavity 533, and the caliber of the throttle passage is positively correlated with the distance between the throttle block 541 and the throttle orifice 535. It can be understood that by changing the position of the regulating rod 540, the cross-sectional area of the throttle passage can be changed, thereby adjusting the pressure drop value.

[0060] As a specific implementation manner, the buffer cavity 532 includes a first buffer sub-cavity 5321 and a second buffer sub-cavity 5322; one end of the pressure reducing cavity 533 is connected to the first buffer sub-cavity 5321, and the other end of the pressure reducing cavity 533 is connected to the second buffer sub-cavity 5322; the throttle orifice 535 includes a first throttle passage 5351 provided between the first buffer sub-cavity 5321 and the pressure reducing cavity 533, and a second throttle passage 5352 provided between the second buffer sub-cavity 5322 and the pressure reducing cavity 533; the throttle block 541 includes a first throttle portion 5411 corresponding to the first throttle passage 5351 and a second throttle portion 5412 corresponding to the second throttle passage 5352.

[0061] Among them, through the hierarchical setting of the first throttle channel 5351 and the second throttle channel 5352, a more uniform pressure distribution is formed at the throttle orifice 535, avoiding local high-pressure or low-pressure areas that may occur in a single throttle orifice, and improving the fluidity and uniformity of the gas; combined with the setting of the buffer cavity 532, the smoothness and efficiency of the gas decompression process can be achieved. At the same time, combined with the precise adjustment of the throttle block 541, the separation efficiency and the operation stability of the device are significantly improved.

[0062] On the basis of the above embodiments, the first throttle channel 5351 is closer to the adjusting rod 540 than the second throttle channel 5352; the size of the first throttle channel 5351 is smaller than that of the second throttle channel 5352, and the size of the first throttle part 5411 is smaller than that of the second throttle part 5412.

[0063] Further, the first pressure reducing valve 510 is arranged close to the second end 120, and the adjusting rod 540 corresponding to the first pressure reducing valve 510 protrudes from the end of the valve body 530 towards the inside of the middle cavity 103; the second pressure reducing valve 520 is arranged close to the first end 110, and the adjusting rod 540 corresponding to the second pressure reducing valve 520 protrudes from the end of the valve body 530 towards the inside of the middle cavity 103; an adjusting device 600 for driving the adjusting rod 540 to move is arranged in the middle cavity 103.

[0064] Specifically, the adjusting device 600 includes a hollow motor 610 arranged in the middle cavity 103, and a rotating rod 620 passes through and is fixedly connected to the inner ring of the hollow motor 610; a first pushing block 630 is threadedly connected to one end of the rotating rod 620, and a second pushing block 640 is threadedly connected to the other end of the rotating rod 620; the first pushing block 630 is fixedly connected to the adjusting rods 540 corresponding to the plurality of first pressure reducing valves 510 respectively; the second pushing block 640 is fixedly connected to the adjusting rods 540 corresponding to the plurality of second pressure reducing valves 520 respectively.

[0065] It can be understood that through the above setting, when the adjusting rod 540 drives the pushing block to approach the second end 120, the cross-sectional area of the throttle channel of the first pressure reducing valve 510 increases, and the pressure drop of the first pressure reducing valve 510 decreases; correspondingly, the cross-sectional area of the throttle channel of the second pressure reducing valve 520 decreases, and the pressure drop of the second pressure reducing valve 520 increases. When the adjusting rod 540 drives the pushing block to approach the first end 110, the cross-sectional area of the throttle channel of the second pressure reducing valve 520 increases, and the pressure drop of the second pressure reducing valve 520 decreases; correspondingly, the cross-sectional area of the throttle channel of the first pressure reducing valve 510 decreases, and the pressure drop of the first pressure reducing valve 510 increases. Thus, the overall structure is made more compact, and the flexibility of the solution is improved.

[0066] Exemplarily, when the content of light components in the recycled gas is relatively high, by adjusting the throttle channel sizes of the first pressure reducing valve 510 and the second pressure reducing valve 520, the pressure drop of the first pressure reducing valve 510 is appropriately increased, so as to quickly separate the light components and reduce the subsequent separation load; while in the case of a relatively high proportion of heavy components, it is necessary to increase the pressure drop in the second stage to ensure sufficient cryogenic conditions for efficient separation of heavy components. This ability of flexible adjustment enables the equipment to always maintain a high separation efficiency in the face of different gas compositions and pressure fluctuations.

[0067] On the basis of the above embodiment, a conical separation membrane 700 is provided in the second cooling cavity 102. The separation membrane 700 separates the first discharge pipe 410 from the second cooling cavity 102; the separation membrane 700 includes a front membrane body 710 facing the second end portion 120 and a rear membrane body 720 away from the second end portion 120; both the front membrane body 710 and the rear membrane body 720 are inclined. Among them, the above-mentioned membrane body can be made of polyimide film, so that ethane is not easily introduced into the first discharge pipe 410, and at the same time, light components such as hydrogen can preferentially pass through the polyimide film. It can be understood that the conical separation membrane 700 increases the separation path of light components and heavy components through the inclined design, enabling the gas to be redistributed along the surface of the separation membrane 700 before entering the discharge pipe, avoiding the phenomenon of light components entraining heavy components. At the same time, due to the conical design forming a flow splitting effect in space, the flow directions of different components are effectively guided, so that the purities of both light components and heavy components are improved.

[0068] Example Two:

[0069] This embodiment also provides a recovery method for a polypropylene process, which is applied to the gas recovery device for the polypropylene process in Example One, and includes:

[0070] S1. Introduce the recycled gas into the inlet pipe 300 and introduce the refrigerant into the condenser group 200;

[0071] S2. Recover the light components from the first discharge pipe 410; recover the heavy components from the second discharge pipe 420; recover propylene from the third discharge pipe 430.

[0072] Among them, after the recycled gas enters from the inlet pipe 300, it first enters the first cooling cavity 101. At this stage, the high-temperature and high-pressure gas is introduced and contacts the high-temperature section of the condenser group 200. The condenser group 200 exchanges heat through the refrigerant inside it, quickly reducing the temperature of the gas. During the cooling process, because light components (such as hydrogen and methane) have lower boiling points, they start to separate when the temperature has not been further reduced, presenting as a gas state. As the gas density decreases, the light components gradually move upward in the cavity and are finally discharged from the recovery housing 100 through the first pressure reducing valve 510 and the first discharge pipe 410.

[0073] Meanwhile, the remaining recycled gas continues to flow in the first cooling cavity 101 and gradually flows into the second cooling cavity 102. Before entering the second cooling cavity 102, the pressure of the gas is reduced by the first pressure reducing valve 510 to further adjust the cooling conditions. After entering the second cooling cavity 102, the low-temperature section of the condenser tube group 200 takes effect to further cool the gas. Since the second discharge pipe 420 is farther away from the first pressure reducing valve than the first discharge pipe 410, and the density of the heavy components is greater than that of propylene, the recycled gas is discharged from the recycling housing 100 through the second discharge pipe 420.

[0074] Finally, after being processed by the low-temperature section of the condenser tube group 200, propylene is further separated from the heavy components due to its boiling point and characteristics. Then, through the pressure reduction of the second pressure reducing valve, it is ensured that propylene can be separated alone, improving the purity and recovery efficiency of propylene, and finally, it is discharged from the recycling housing 100 through the third discharge pipe 430.

[0075] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A gas recovery device for a polypropylene process, characterized in that: The invention comprises a recovery shell (100) and a condenser tube group (200), wherein the recovery shell (100) comprises a first cooling cavity (101) and a second cooling cavity (102), wherein the second cooling cavity (102) is located above the first cooling cavity (101); the first cooling cavity (101) and the second cooling cavity (102) are connected via a connecting portion (500); The condensing tube group (200) passes through the second cooling cavity (102) and the first cooling cavity (101) in sequence along a first direction; The first cooling cavity (101) is connected to an air inlet pipe (300); the second cooling cavity (102) is respectively connected to a first discharge pipe (410) for discharging light gas, a second discharge pipe (420) for discharging heavy gas, and a third discharge pipe (430) for discharging propylene; The air inlet pipe (300), the first discharge pipe (410) and the second discharge pipe (420) are arranged in sequence along a direction opposite to the first direction, the second discharge pipe (420) is connected to the top of the second cooling cavity (102), and the third discharge pipe (430) is connected to the bottom of the second cooling cavity (102); The recovery shell (100) comprises a first end (110) and a second end (120) which are arranged opposite to each other; the condensing pipe group (200) passes through the second cooling cavity (102) from the first end (110), then passes out from the second end (120), and passes through the first cooling cavity (101) along the second end (120); The air inlet pipe (300) is arranged below the first cooling cavity (101) and is arranged close to the first end (110); the first discharge pipe (410) is arranged above the second cooling cavity (102) and is arranged close to the second end (120); the second discharge pipe (420) is arranged above the second cooling cavity (102) and is arranged close to the first end (110); the third discharge pipe (430) is arranged close to the first end (110); A conical separation membrane (700) is provided in the second cooling cavity (102), and the separation membrane (700) separates the first discharge pipe (410) and the second cooling cavity (102); The separation membrane (700) comprises a front membrane body (710) facing the second end (120) and a rear membrane body (720) away from the second end (120); the front membrane body (710) and the rear membrane body (720) are both arranged in an inclined manner.

2. A gas recovery device for a polypropylene process according to claim 1, characterized in that: The recovery shell (100) further comprises an intermediate cavity (103) located between the first cooling cavity (101) and the second cooling cavity (102); The connecting portion (500) comprises a first pressure reducing valve (510) arranged in the intermediate cavity (103), and a second pressure reducing valve (520) is arranged in the intermediate cavity (103); an inlet of the first pressure reducing valve (510) is connected to the first cooling cavity (101), and an outlet of the first pressure reducing valve (510) is connected to the second cooling cavity (102); an inlet of the second pressure reducing valve (520) is connected to the second cooling cavity (102), and an outlet of the second pressure reducing valve (520) is connected to the intermediate cavity (103); The inlet of the third discharge pipe (430) is in communication with the intermediate cavity (103).

3. A gas recovery device for a polypropylene process according to claim 2, characterized in that: The first pressure reducing valve (510) and the second pressure reducing valve (520) both comprise a valve body (530), wherein the valve body (530) comprises an inlet channel (531), a buffer cavity (532), a pressure reducing cavity (533), and an outlet channel (534) which are connected in sequence; A throttle opening (535) is formed between the buffer cavity (532) and the pressure reducing cavity (533); the valve body (530) is movably connected with an adjusting rod (540); a throttle block (541) is installed on the adjusting rod (540) at a position corresponding to the throttle opening (535); a throttle channel is formed between the throttle block (541) and the throttle opening (535); the throttle channel connects the buffer cavity (532) and the pressure reducing cavity (533); and the caliber of the throttle channel is positively correlated with the distance between the throttle block (541) and the throttle opening (535).

4. A gas recovery device for a polypropylene process according to claim 3, characterized in that: The buffer cavity (532) comprises a first buffer sub-cavity (5321) and a second buffer sub-cavity (5322); one end of the pressure reduction cavity (533) is in communication with the first buffer sub-cavity (5321), and the other end of the pressure reduction cavity (533) is in communication with the second buffer sub-cavity (5322); The throttle port (535) comprises a first throttle passage (5351) arranged between the first buffer sub-chamber (5321) and the pressure reduction chamber (533), and a second throttle passage (5352) arranged between the second buffer sub-chamber (5322) and the pressure reduction chamber (533); The throttling block (541) includes a first throttling portion (5411) arranged corresponding to the first throttling channel (5351), and a second throttling portion (5412) arranged corresponding to the second throttling channel (5352).

5. A gas recovery device for a polypropylene process according to claim 4, characterized in that: The first throttling channel (5351) is closer to the adjusting rod (540) than the second throttling channel (5352); The size of the first throttling channel (5351) is smaller than the size of the second throttling channel (5352), and the size of the first throttling portion (5411) is smaller than the size of the second throttling portion (5412).

6. A gas recovery device for a polypropylene process according to claim 3, characterized in that: The first pressure reducing valve (510) is arranged close to the second end portion (120), and an adjusting rod (540) corresponding to the first pressure reducing valve (510) is arranged at an end portion protruding from the valve body (530) and facing the inner side of the intermediate cavity (103); The second pressure reducing valve (520) is arranged close to the first end (110), and an adjusting rod (540) corresponding to the second pressure reducing valve (520) is arranged at an end protruding from the valve body (530) and facing the inner side of the intermediate cavity (103); An adjustment device (600) for driving the adjustment rod (540) to move is arranged in the intermediate cavity (103).

7. A gas recovery device for a polypropylene process according to claim 6, characterized in that: The regulating device (600) comprises a hollow motor (610) arranged in the middle cavity (103), and a rotating rod (620) passes through and is fixedly connected to the inner ring of the hollow motor (610); One end of the rotating rod (620) is threadedly connected to a first pushing block (630), and the other end of the rotating rod (620) is threadedly connected to a second pushing block (640); the first pushing blocks (630) are respectively fixedly connected to a plurality of adjusting rods (540) corresponding to the first pressure reducing valves (510); and the second pushing blocks (640) are respectively fixedly connected to a plurality of adjusting rods (540) corresponding to the second pressure reducing valves (520).

8. A polypropylene recycling method, characterized in that: A gas recovery device for a polypropylene process as claimed in any one of claims 1 to 7, comprising: Introduce recycled gas into the air inlet pipe and introduce refrigerant into the condenser tube group; The light component is recovered from the first discharge pipe; the heavy component is recovered from the second discharge pipe; and propylene is recovered from the third discharge pipe.

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