Gas recovery device and gas recovery method for polypropylene process

Abstract

The invention discloses a gas recovery device and a gas recovery method for a polypropylene process. The gas recovery device for the polypropylene process comprises a recovery shell, a condensation pipe group, a communication part, a gas inlet pipe, a first discharge pipe, a second discharge pipe and a third discharge pipe, the recovery shell comprises a first cooling cavity and a second cooling cavity, and the second cooling cavity is located above the first cooling cavity; the condensation pipe set sequentially penetrates through the second cooling cavity and the first cooling cavity in the first direction. The air inlet pipe, the first discharging pipe and the second discharging pipe are sequentially arranged in the direction opposite to the first direction, and the lower portion of the second cooling cavity communicates with the third discharging pipe. On one hand, the cooling cavities are arranged in an overlapped mode and small in occupied space, and on the other hand, the gas inlet pipe, the first discharging pipe and the second discharging pipe are sequentially matched with the relative high-temperature part to the relative low-temperature part of the condensation pipe set, so that the condensation pipe set and recycled gas are opposite in trend, the utilization rate is high, and the cooling effect is maximized.

Description

Technical Field

[0001] The invention relates to the technical field of condensation separation structures, and in particular 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 resource utilization, reduce costs and reduce environmental emissions. Specifically, in the polypropylene production process, gas recovery can separate the incompletely reacted gas, volatile organic matter and by-product gas (collectively referred to as recovered gas) discharged from the reactor and reuse it, usually by "multi-stage condensation" or "cryogenic separation".

[0003] "Multi-stage condensation" refers to the use of multiple condensation equipment to condense the recovered gas step by step in order to complete the gas separation. It requires more condensation equipment and occupies a larger space overall; "cryogenic separation" refers to the 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 condensation separation technology for polypropylene in the prior art has the disadvantages of occupying a large 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 problem that the condensation separation equipment in the prior art occupies a large space and has high energy consumption when cooling and separating the recovered gas in the polypropylene production process.

[0005] To achieve this object, the present invention adopts the following technical solutions: A gas recovery device for a polypropylene process, comprising a recovery shell and a condenser tube group, wherein the recovery shell comprises a first cooling cavity and a second cooling cavity, wherein the second cooling cavity is located above the first cooling cavity; the first cooling cavity and the second cooling cavity are connected through a connecting portion; The condenser tube group sequentially passes through the second cooling cavity and the first cooling cavity along a first direction; The first cooling cavity is connected to an air inlet pipe; the second cooling cavity is respectively connected to a first discharge pipe for discharging light gas, a second discharge pipe for discharging heavy gas, and a third discharge pipe for discharging propylene; Among them, the air inlet pipe, the first discharge pipe and the second discharge pipe are arranged in sequence along a direction opposite to the first direction, the second discharge pipe is connected to the top of the second cooling cavity, and the third discharge pipe is connected to the bottom of the second cooling cavity.

[0006] Optionally, the recovery shell includes a first end and a second end that are arranged opposite to each other, and the condensing pipe group passes through the second cooling cavity from the first end, then passes through the second end, and passes through the first cooling cavity from the second end; The air inlet 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 arranged close to the first end.

[0007] Optionally, the recovery shell further includes an intermediate cavity located between the first cooling cavity and the second cooling cavity; The communicating portion comprises a first pressure reducing valve disposed in the intermediate cavity, and a second pressure reducing valve is disposed in the intermediate cavity; an inlet of the first pressure reducing valve is communicated with the first cooling cavity, and an outlet of the first pressure reducing valve is communicated with the second cooling cavity; an inlet of the second pressure reducing valve is communicated with the second cooling cavity, and an outlet of the second pressure reducing valve is communicated with the intermediate cavity; The inlet of the third discharge pipe is communicated with the intermediate cavity.

[0008] Optionally, the first pressure reducing valve and the second pressure reducing valve both 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 connected in sequence; A throttle port is formed between the buffer cavity and the pressure reducing cavity, an adjusting rod is movably connected to the valve body, a throttle block is installed on the adjusting rod at a position corresponding to the throttle port; a throttle channel is formed between the throttle block and the throttle port, the throttle channel connects the buffer cavity and the pressure reducing cavity, and a diameter of the throttle channel is positively correlated with a distance between the throttle block and the throttle port.

[0009] Optionally, the buffer cavity includes a first buffer sub-cavity and a second buffer sub-cavity; one end of the depressurization cavity is connected to the first buffer sub-cavity, and the other end of the depressurization cavity is connected to the second buffer sub-cavity; The throttle port includes a first throttle passage disposed between the first buffer sub-chamber and the depressurization chamber, and a second throttle passage disposed between the second buffer sub-chamber and the depressurization chamber; The throttling block includes a first throttling portion arranged corresponding to the first throttling passage, and a second throttling portion arranged corresponding to the second throttling passage.

[0010] Optionally, the first throttling channel is closer to the adjusting rod than the second throttling channel; The size of the first throttling passage is smaller than that of the second throttling passage, and the size of the first throttling portion is smaller than that of the second throttling portion.

[0011] Optionally, the first pressure reducing valve is arranged close to the second end, and an adjusting rod corresponding to the first pressure reducing valve protrudes from an end of the valve body and is arranged toward the inner side of the intermediate cavity; The second pressure reducing valve is arranged close to the first end, and the regulating rod corresponding to the second pressure reducing valve protrudes from the end of the valve body and is arranged toward the inner side of the intermediate cavity; The middle cavity is provided with an adjusting device for driving the adjusting rod to move.

[0012] Optionally, the adjustment device comprises 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; One end of the rotating rod is threadedly connected to a first pushing block, and the other end of the rotating rod is threadedly connected to a second pushing block; the first pushing blocks are respectively fixedly connected to the adjusting rods corresponding to the multiple first pressure reducing valves; the second pushing blocks are respectively fixedly connected to the adjusting rods corresponding to the multiple second pressure reducing valves.

[0013] Optionally, a conical separation membrane is provided in the second cooling cavity, and the separation membrane separates the first discharge pipe and the second cooling cavity; The separation membrane comprises a front membrane body facing the second end portion and a rear membrane body away from the second end portion; the front membrane body and the rear membrane body are both arranged in an inclined manner.

[0014] A polypropylene process recovery method, applied to the gas recovery device of the polypropylene process as described above, 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.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The gas recovery device and recovery method of the polypropylene process provided by the present invention, wherein the recovered gas enters the first cooling cavity below from the air inlet pipe, and under the action of the condenser pipe group, most of the light components are cooled and separated, and the separated light components are discharged from the recovery shell through the connecting part and the first discharge pipe; the remaining recovered gas continues to be cooled in the second cooling cavity under the action of the condenser pipe group to achieve cooling and separation of heavy components, and the separated heavy components are discharged from the recovery shell 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 scheme, the cooling cavities are overlapped, occupying a small space, and the condenser pipe group passes through the second cooling cavity from one end of the recovery shell, and passes through the first cooling cavity from the other end of the recovery shell, which is opposite to the direction of the recovered gas, and has a high utilization rate, and is set with a temperature gradient, the relatively low temperature part matches the second cooling cavity, and the relatively high temperature part matches the first cooling cavity, so as to maximize the cooling effect. Therefore, this scheme has the advantages of small space occupation and low energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0017] The structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with this technology. They are not used to limit the conditions under which the present invention can be implemented, and therefore have no substantive technical significance. Any structural modification, change in proportion or adjustment of size, without affecting the effects and purposes that can be achieved by the present invention, should still fall within the scope of the technical contents disclosed by the present invention.

[0018] Figure 1 A schematic diagram of the overall structure of a gas recovery device for a polypropylene process provided by an embodiment of the present invention; Figure 2 A schematic diagram of a partial explosion structure of a gas recovery device for a polypropylene process provided by an embodiment of the present invention; Figure 3 A schematic diagram of a first partial cross-sectional structure of a gas recovery device for a polypropylene process provided by an embodiment of the present invention; Figure 4 A second partial cross-sectional structural schematic diagram of a gas recovery device for a polypropylene process provided by an embodiment of the present invention; Figure 5A schematic diagram of the partial structure of a gas recovery device for a polypropylene process provided by an embodiment of the present invention; Figure 6 Schematic diagram of the cross-sectional structure of the first pressure reducing valve and the second pressure reducing valve in an embodiment of the present invention; Figure 7 for Figure 6 A schematic diagram of the local enlarged structure at point A; Illustration: 100, recovery shell; 101, first cooling cavity; 102, second cooling cavity; 103, middle cavity; 110, first end; 120, second end; 200, condenser tube group; 300, air inlet pipe; 410, first discharge pipe; 420, second discharge pipe; 430, third discharge pipe; 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 port; 5351, first throttle channel; 5352, second throttle channel; 540, adjusting rod; 541, throttle block; 5411, first throttle part; 5412, second throttle part; 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 DESCRIPTION

[0019] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] In the description of the present invention, it should be understood that the terms "upper", "lower", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions 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 cannot be understood as a limitation of the present invention. It should be noted that when a component is considered to be "connected" to another component, it may be directly connected to the other component or there may be a centrally arranged component at the same time.

[0021] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0022] Embodiment 1: The gas recovery device for the polypropylene process provided in this embodiment is suitable for 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., the waste gas) to separate 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, the structure of the gas recovery device for the polypropylene process is improved to make it more compact and more efficient.

[0023] like Figures 1 to 3 As shown, the gas recovery device of the polypropylene process in this embodiment includes a recovery shell 100 and a condenser pipe group 200, the recovery shell 100 includes a first cooling cavity 101 and a second cooling cavity 102, 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 connecting portion 500; the condenser pipe group 200 passes through the second cooling cavity 102 and the first cooling cavity 101 in sequence along a first direction; the condenser pipe group 200 includes a plurality of pipes for conveying refrigerant (not shown), the pipes are arranged along the first direction for conveying refrigerant, and cooperate with external structures such as a condenser and a compressor to realize the conveying of refrigerant, and the principle of conveying refrigerant is well known to those skilled in the art and is not introduced in this embodiment.

[0024] The first cooling cavity 101 is connected with an air inlet pipe 300; the second cooling cavity 102 is respectively connected 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 air inlet pipe 300, the first discharge pipe 410, and the second discharge pipe 420 are sequentially arranged in a direction opposite to the first direction, the second discharge pipe 420 is connected to the upper part of the second cooling cavity 102, and the third discharge pipe 430 is connected to the lower part of the second cooling cavity 102. It can be understood that the high-temperature and high-pressure recovered gas first enters the first cooling cavity 101 below from the air inlet pipe 300, and the recovered gas is preliminarily cooled by the condenser pipe group 200, and the light components with lower density are discharged from the first discharge pipe 410, realizing the cooling and separation of most of the light components, and the separated light components flow in the opposite direction of the first direction, and due to their lower 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 chamber 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, thereby achieving temperature reduction and separation of the heavy components.

[0025] Specifically, in the gas recovery device of the polypropylene process in this embodiment, the high-temperature and high-pressure recovered gas enters the first cooling cavity 101 below from the air inlet pipe 300, and under the action of the condenser pipe group 200, most of the light components are cooled and separated, and the separated light components are discharged from the recovery shell 100 through the connecting part 500 and the first discharge pipe 410; the remaining recovered gas continues to be cooled in the second cooling cavity 102 under the action of the condenser pipe group 200, so as to achieve cooling and separation of heavy components, and the separated heavy components are discharged from the recovery shell 100 through the second discharge pipe 420; finally, in the second cooling cavity 102, propylene flows downward to be discharged from the third discharge pipe 430. In the above scheme, the cooling cavities are overlapped, occupying a small space, and the condenser tube group 200 passes through the second cooling cavity 102 from one end of the recovery shell 100, and passes through the first cooling cavity 101 from the other end of the recovery shell 100, which is opposite to the direction of the recovered gas, promoting the heat exchange between the recovered gas and the refrigerant, with high utilization rate, and with a 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, to maximize the cooling effect. Therefore, this scheme has the advantages of small space occupation and low energy consumption.

[0026] like Figures 1 to 4 As shown, the recovery shell 100 includes a first end 110 and a second end 120 which are arranged opposite to each other. After the condensing pipe group 200 passes through the second cooling cavity 102 from the first end 110, it passes through the second end 120 and passes through the first cooling cavity 101 from 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.

[0027] It can be understood that the above design effectively realizes countercurrent heat exchange of the recovered gas by running the condenser tube group 200 between the two-stage cooling cavities. Specifically, the high-temperature and high-pressure recovered gas enters from the bottom of the first cooling cavity 101, and flows along the relatively high-temperature part of the condenser tube group 200, and directly exchanges heat with the refrigerant. Light components such as hydrogen have low boiling points and low densities under the same pressure, and can enter the first discharge pipe 410 in the gas phase. Subsequently, the remaining recovered gas continues to be further cooled and treated with the relatively low-temperature part of the condenser tube group 200 in the second cooling cavity 102, so as to achieve efficient separation of light components, heavy components and propylene. The structure of the condenser tube group 200 running through both ends makes full use of the temperature gradient characteristics of the condenser tube group 200, so that the high-temperature section matches the first cooling cavity 101, and the low-temperature section matches the second cooling cavity 102, ensuring that the use efficiency of the refrigerant is maximized. At the same time, through the distribution of this temperature gradient, the cooling process can be completed in a smaller equipment volume, and the overall energy consumption is effectively reduced.

[0028] Furthermore, if Figure 3 and Figure 4 As shown, the recovery shell 100 also includes an intermediate cavity 103 located between the first cooling cavity 101 and the second cooling cavity 102; the connecting portion 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 connected to the first cooling cavity 101, and the outlet of the first pressure reducing valve 510 is connected to the second cooling cavity 102; the inlet of the second pressure reducing valve 520 is connected to the second cooling cavity 102, and the outlet of the second pressure reducing valve 520 is connected to the intermediate cavity 103; the inlet of the third discharge pipe 430 is connected to the intermediate cavity 103.

[0029] It is understandable that the recovered gas first enters from the first cooling cavity 101, and after passing through the first pressure reducing valve 510, its pressure is initially reduced and 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 recovered gas, thereby providing suitable thermodynamic conditions for the separation of light components and avoiding the liquefaction of light components. The remaining recovered gas after separation is further cooled in the second cooling cavity 102, so that the lowest temperature part of the condenser group 200 can liquefy propylene, so that the heavy components are separated from propylene, and after propylene flows into the second pressure reducing valve 520, it is discharged through the third discharge pipe 430 in the gas phase through the pressure reduction, and does not mix with other heavy components, thereby improving the recovery purity of propylene, reducing the impact load inside the equipment, and helping to improve the stability and efficiency of separation.

[0030] Specifically, Figures 4 to 7As shown, the first pressure reducing valve 510 and the second pressure reducing valve 520 both include a valve body 530, and the valve body 530 includes 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 port 535 is formed between the buffer cavity 532 and the pressure reducing cavity 533, and the valve body 530 is movably connected with an adjusting rod 540, and a throttle block 541 is installed at the position of the adjusting rod 540 corresponding to the throttle port 535; a throttle channel is formed between the throttle block 541 and the throttle port 535, and 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 port 535. It can be understood that by changing the position of the adjusting rod 540, the cross-sectional area of ​​the throttle channel can be changed, thereby adjusting the pressure drop value.

[0031] As a specific embodiment, the buffer chamber 532 includes a first buffer sub-chamber 5321 and a second buffer sub-chamber 5322; one end of the pressure reduction chamber 533 is connected to the first buffer sub-chamber 5321, and the other end of the pressure reduction chamber 533 is connected to the second buffer sub-chamber 5322; the throttle port 535 includes a first throttling channel 5351 arranged between the first buffer sub-chamber 5321 and the pressure reduction chamber 533, and a second throttling channel 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.

[0032] Among them, through the graded setting of the first throttling channel 5351 and the second throttling channel 5352, a more uniform pressure distribution is formed at the throttling port 535, avoiding the local high-pressure or low-pressure areas that may occur in a single throttling port, and improving the fluidity and uniformity of the gas; combined with the setting of the buffer chamber 532, the smoothness and efficiency of the gas decompression process can be achieved, and combined with the precise adjustment of the throttling block 541, the separation efficiency and the stability of the device operation are significantly improved.

[0033] Based on the above embodiment, 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.

[0034] Furthermore, the first pressure-reducing valve 510 is arranged near 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 and is arranged toward the inner side of the intermediate cavity 103; the second pressure-reducing valve 520 is arranged near 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 and is arranged toward the inner side of the intermediate cavity 103; an adjusting device 600 for driving the adjusting rod 540 to move is arranged in the intermediate cavity 103.

[0035] Specifically, the adjusting device 600 includes a hollow motor 610 arranged in the middle cavity 103, and the inner ring of the hollow motor 610 passes through and is fixedly connected to a rotating rod 620; 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 block 630 is respectively fixedly connected to the adjusting rods 540 corresponding to the multiple first pressure reducing valves 510; the second pushing block 640 is respectively fixedly connected to the adjusting rods 540 corresponding to the multiple second pressure reducing valves 520.

[0036] It can be understood that, through the above arrangement, when the adjusting rod 540 drives the push block to approach the second end 120, the cross-sectional area of ​​the throttling channel of the first pressure reducing valve 510 increases, and the pressure drop of the first pressure reducing valve 510 decreases; accordingly, the cross-sectional area of ​​the throttling 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 push block to approach the first end 110, the cross-sectional area of ​​the throttling channel of the second pressure reducing valve 520 increases, and the pressure drop of the second pressure reducing valve 520 decreases; accordingly, the cross-sectional area of ​​the throttling channel of the first pressure reducing valve 510 decreases, and the pressure drop of the first pressure reducing valve 510 increases. As a result, the overall structure is more compact and the flexibility of the solution is improved.

[0037] For example, when the light component content in the recovered gas is high, the pressure drop of the first pressure reducing valve 510 is appropriately increased by adjusting the throttling channel size of the first pressure reducing valve 510 and the second pressure reducing valve 520, so as to quickly separate the light component and reduce the subsequent separation load; while in the case of a high proportion of heavy components, it is necessary to increase the pressure drop of the second stage to ensure sufficient cryogenic conditions to achieve efficient separation of heavy components. This flexible adjustment capability enables the equipment to always maintain a high separation efficiency when facing different gas compositions and pressure fluctuations.

[0038] On the basis of the above-mentioned embodiment, 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 includes 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 inclined. Among them, the above-mentioned membrane body can be selected from polyimide film, so that ethane is not easy to enter the first discharge pipe 410, and 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, so that the gas can be redistributed along the surface of the separation membrane 700 before entering the discharge pipe, avoiding the phenomenon of light components carrying heavy components. At the same time, since the conical design forms a diversion effect in space, the flow direction of different components is effectively guided, so that the purity of light components and heavy components can be improved.

[0039] Embodiment 2: This embodiment also provides a polypropylene process recovery method, which is applied to the gas recovery device of the polypropylene process in the first embodiment, comprising: S1, introducing recovered gas into the air inlet pipe 300 and introducing refrigerant into the condenser pipe group 200; S2, recovering light components from the first discharge pipe 410; recovering heavy components from the second discharge pipe 420; and recovering propylene from the third discharge pipe 430.

[0040] Among them, after the recycled gas enters from the air 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 uses the refrigerant inside it to perform heat exchange and quickly reduce the temperature of the gas. During the cooling process, because the light components (such as hydrogen and methane) have a lower boiling point, they begin to separate before the temperature is further reduced and appear in a gaseous state. As the gas density decreases, the light components gradually move to the top of the cavity and are finally discharged from the recovery shell 100 through the first pressure reducing valve 510 and the first discharge pipe 410.

[0041] At the same time, the remaining recovered 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 component is greater than that of propylene, it is discharged from the recovery shell 100 through the second discharge pipe 420.

[0042] Finally, after being processed in the low temperature section of the condenser group 200, propylene is further separated from the heavy components due to its boiling point and characteristics, and then the pressure is reduced by the second pressure reducing valve to ensure that propylene can be separated separately, thereby improving the purity and recovery efficiency of propylene, and finally discharged from the recovery shell 100 through the third discharge pipe 430.

[0043] As described above, 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 thereof 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 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).

2. A gas recovery device for a polypropylene process according to claim 1, characterized in that: 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); and the third discharge pipe (430) is arranged close to the first end (110).

3. A gas recovery device for a polypropylene process according to claim 2, 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).

4. A gas recovery device for a polypropylene process according to claim 3, 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).

5. A gas recovery device for a polypropylene process according to claim 4, 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).

6. A gas recovery device for a polypropylene process according to claim 5, 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).

7. A gas recovery device for a polypropylene process according to claim 4, 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).

8. A gas recovery device for a polypropylene process according to claim 7, 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).

9. A gas recovery device for a polypropylene process according to claim 2, characterized in that: 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.

10. A polypropylene recycling method, characterized in that: A gas recovery device for a polypropylene process as claimed in any one of claims 1 to 9, 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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