Gas-liquid two-phase sealing structure and single-screw expander

Abstract

The utility model discloses a gas-liquid two-phase sealing structure and a single-screw expander. The gas-liquid two-phase sealing structure comprises a base and a sealing module, a cavity communicated with the outside is formed in the base; the sealing module comprises a rotating ring located in the cavity, and the rotating ring rotates to form a dynamic pressure effect and generate a sealing film. The single-screw expander comprises the gas-liquid two-phase sealing structure. Two-end sealing can be achieved through the same gas-liquid two-phase sealing structure, a two-end sealing structure formed by two sets of dry gas sealing faces in the prior art is replaced, the number of parts is effectively reduced, and the use cost is reduced. And the gas-liquid two-phase sealing structure effectively meets the sealing requirement in a special process, the application range is expanded, and the practicability is better.

Description

Technical Field

[0001] This utility model relates to the field of sealing structure technology, specifically to a gas-liquid two-phase sealing structure and a single-screw expander. Background Technology

[0002] A single-screw expander is a heat engine that converts thermal energy into mechanical energy by expanding the volume of a gas, driving the screw rotor to rotate. It mainly consists of a pair of meshing screw rotors and a casing. The rotors are sealed with gaps, forming a continuously variable volume working chamber. A gaseous working fluid containing heat enters the working chamber and expands adiabatically, driving the rotor to rotate and perform work. During this expansion and work, the pressure and temperature of the working fluid decrease, thus achieving the heat-work conversion. The working fluid may liquefy during the cooling and depressurization process. Therefore, the expander needs a reliable sealing device to seal the hot gaseous substance within the working chamber.

[0003] Dry gas seals are a new type of non-contact gas-lubricated seal. Utilizing fluid dynamics principles, they achieve non-contact operation of the sealing end face by creating a dynamic pressure groove. Due to their unique advantages, they are widely used in various medium- and high-speed rotating machinery, such as centrifugal compressors, turbines, and fans. The structural forms of dry gas seals can be classified according to the sealed medium and its pressure into single-end dry gas seals, double-end dry gas seals, and tandem dry gas seals.

[0004] Currently, double-end dry gas seals consist of two sets of dry gas seals facing each other, with nitrogen as the sealing gas. The sealing of the medium gas is achieved by sealing the nitrogen. However, in certain special processes, nitrogen is not allowed to enter the process gas. In such cases, if the process gas is used as the sealing gas, conventional double-end dry gas seals will allow the process gas to leak into the environment. If water ingress is permissible, water can be used as a buffer to block the process gas. However, if the process gas is prone to liquefaction, conventional double-end dry gas seals cannot meet the requirements. Utility Model Content

[0005] The technical problem to be solved by this utility model is that the existing dry gas seals are not effective for some special processes. The purpose is to provide a gas-liquid two-phase sealing structure and a single screw expander to solve the above problems.

[0006] This utility model is achieved through the following technical solution:

[0007] In the first aspect, this utility model provides a gas-liquid two-phase sealing structure, including a base and a sealing module;

[0008] The base has a cavity that connects to the outside world;

[0009] The sealing module includes a rotating ring located in the cavity. The rotation of the rotating ring creates a hydrodynamic effect and generates a sealing film.

[0010] In one possible design, the base is provided with three spaced-apart media channels. The two ends of the media channels are connected to the cavity and the outside, respectively. The two media channels on both sides are constructed as media inlet channels located at both ends of the rotating ring, and the media channel in the middle is constructed as a media outlet channel corresponding to the rotating ring.

[0011] In one possible design, the cavity has two opposing sides, one side having an opening for communicating with the outside, and the other side having the medium channel. Accordingly, a rotating ring is located at the opening, and the inner circumference of the rotating ring extends out of the opening.

[0012] In one possible design, the rotating ring has two opposing outer surfaces, each with an annular dynamic pressure grooves rotating in opposite directions.

[0013] In one possible design, the sealing module also includes two stationary rings respectively disposed on both sides of the rotating ring. The stationary rings are slidably disposed on the cavity and abut against the rotating ring by elastic elements.

[0014] When a sealing film is formed outside the rotating ring, the rotating ring separates from the stationary ring and forms a gap that fits the sealing film. Correspondingly, the stationary ring maintains the gap width less than the maximum width of the forming sealing film through an elastic element.

[0015] In one possible design, the stationary ring has two opposing ends, one end of which is configured as a drive end that is slidably disposed on the cavity, and the other end of which is configured as an abutment end facing the rotating ring.

[0016] The stationary ring is provided with vent holes for guiding the flow of the sealing medium;

[0017] The contact end of the stationary ring is provided with a drainage groove that communicates with the vent hole. Correspondingly, the vent hole is connected to the dynamic pressure groove through the drainage groove.

[0018] The driving end of the stationary ring is connected to the elastic element through a push ring. The push ring has two opposing outer wall surfaces, one of which abuts against the stationary ring and the other against the elastic element.

[0019] Correspondingly, the push ring is provided with an additional hole that communicates with the vent; the outer periphery of the push ring is provided with a floating sealing ring that abuts against the annular area.

[0020] In one possible design, the cavity has an annular area adapted to the stationary ring, and a retaining ring is provided on the inner wall of the annular area. Correspondingly, the outer periphery of the stationary ring has an inner concave groove adapted to the retaining ring.

[0021] In one possible design, a drive shaft and an auxiliary seat are also included, with a gap between the drive shaft and the auxiliary seat, and the base is set on the gap;

[0022] Correspondingly, the base has two opposite sides, one side of which is sleeved on the drive shaft and the inner circumference of the rotating ring is connected to the sleeve through a sealing ring, and the other side abuts against the auxiliary seat. Correspondingly, the auxiliary seat is provided with three air holes, which correspond one-to-one with and are connected to three medium channels.

[0023] The base has two opposite and parallel ends to the drive shaft, with an additional plate provided at the end adjacent to the process medium. Accordingly, the base abuts against the additional plate and is connected to the additional plate by screws.

[0024] In one possible design, multiple sealing rings are provided between the auxiliary seat and the base, and two adjacent sealing rings are located on both sides of the same air hole;

[0025] The bushing has two ends opposite and parallel to the drive shaft, one end of which is adjacent to the auxiliary plate and has a first fixing member located outside the auxiliary plate, and the other end has a second fixing member.

[0026] Secondly, this utility model provides a single-screw expander, including the aforementioned gas-liquid two-phase sealing structure.

[0027] Compared with the prior art, this utility model has the following advantages and beneficial effects:

[0028] The gas-liquid two-phase sealing structure achieves sealing at both ends, replacing the existing two-end sealing structure consisting of two sets of dry gas seals facing each other. This effectively reduces the number of components and lowers operating costs. Furthermore, the gas-liquid two-phase sealing structure effectively meets the sealing requirements of special processes, expanding its application range and improving its practicality. Attached Figure Description

[0029] The accompanying drawings, which are included to provide a further understanding of the embodiments of the present invention and form part of this application, do not constitute a limitation thereof. In the drawings:

[0030] Figure 1 This is a schematic diagram of a gas-liquid two-phase sealing structure.

[0031] Figure 2 This is a schematic diagram of the assembly of the base and the sealing module.

[0032] Figure 3 The diagram shows the structure of the rotating ring and the stationary ring, and also illustrates the dynamic pressure groove on the rotating ring.

[0033] Figure 4 This is a schematic diagram showing the flow direction of the sealing medium.

[0034] The attached diagram shows the markings and corresponding component names:

[0035] 100. Base; 101. Cavity; 102. Medium channel; 103. Medium inlet channel; 104. Medium outlet channel; 105. Opening; 200. Sealing module; 201. Rotating ring; 202. Dynamic pressure groove; 203. Stationary ring; 204. Push ring; 205. Elastic element; 206. Vent hole; 207. Drainage groove; 208. Concave sliding groove; 300. Drive shaft; 400. Additional seat; 500. Bushing; 501. First fixing element; 502. Second fixing element; 600. Additional plate. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of this utility model are only used to explain this utility model and are not intended to limit this utility model.

[0037] Example 1:

[0038] like Figures 1-4 As shown, a gas-liquid two-phase sealing structure includes a base 100 and a sealing module 200;

[0039] The base 100 is provided with a cavity 101 that communicates with the outside world;

[0040] The sealing module 200 includes a rotating ring 201 located in the cavity 101. The rotating ring 201 rotates to create a dynamic pressure effect and generate a sealing film.

[0041] In the gas-liquid two-phase sealing structure, the cavity 101 is connected to the outside, which facilitates the disassembly and assembly of the sealing module 200. On the other hand, the cavity 101 allows the base 100 to be spatially connected to the component to be sealed, thereby achieving sealing through the sealing module 200.

[0042] For the sealing module 200, the rotating ring 201 has rotational properties. When the rotating ring 201 rotates under the action of external power, and the sealing medium flows into the rotating ring 201 through the cavity 101, the rotating ring 201 rotates to form a dynamic pressure effect and generate a sealing film. The sealing film blocks the entry of the external or internal medium, which not only achieves sealing at both ends and prevents the leakage and escape of the process medium, but also separates adjacent components through the sealing film, realizing non-contact sealing, which helps to reduce wear during operation.

[0043] It is worth noting that the sealing medium will flow from the cavity 101 to the outside. Therefore, during operation, the sealing medium is continuously input to provide a continuous and stable buffer fluid for the seal, so that the sealing membrane can form stably, ensuring smooth operation of the seal and guaranteeing the sealing effect.

[0044] Based on this, the two-end sealing can be achieved by using the same gas-liquid two-phase sealing structure, which replaces the two-end sealing structure composed of two sets of dry gas seals facing each other in the prior art, effectively reducing the number of components and lowering the cost of use.

[0045] For specialized processes, such as when existing dry gas seals are used in single-screw expanders with nitrogen as the sealing medium, but nitrogen is not allowed to enter the process gas, the process gas needs to be used as a buffer fluid. Simultaneously, the process gas in the single-screw expander must not leak into the environment. In this case, the aforementioned gas-liquid two-phase sealing structure can completely block the process gas. Furthermore, even if the process gas liquefies, the gas-liquid two-phase sealing structure can still function normally. Therefore, the gas-liquid two-phase sealing structure effectively meets the sealing requirements of specialized processes, expands its application range, and improves its practicality.

[0046] It is worth noting that the sealing medium used in the gas-liquid two-phase sealing structure can be either a sealing gas or a sealing liquid, offering a variety of options to suit different sealing scenarios and broad applicability. Similarly, the process medium can also be either a process gas or a process liquid. Therefore, the sealing medium and the process medium can be combined in various ways to meet different sealing requirements.

[0047] In one possible implementation, the base 100 is provided with three spaced-apart medium channels 102. The two ends of the medium channels 102 are respectively connected to the cavity 101 and the outside. The two medium channels 102 on both sides are configured as medium inlet channels 103 located at both ends of the rotating ring 201, and the medium channel 102 in the middle is configured as a medium outlet channel 104 corresponding to the rotating ring 201.

[0048] Based on the above design, the sealing medium simultaneously enters the base 100 from both medium entry channels 103, and then contacts the side of the rotating ring 201. As the rotating ring 201 rotates, a sealing film is formed at the inner and outer end faces of the rotating ring 201. After the sealing film is formed, the sealing medium will also flow to the relatively low-pressure medium discharge channel 104 and flow out of the cavity 101.

[0049] As is easily understood, the medium inlet channel 103 is provided with two channels symmetrically located on both sides of the rotating ring 201. Based on this, not only is the input amount of sealing medium increased, ensuring that a sealing film is formed at both ends of the rotating ring 201, but also the amount of sealing medium on both sides of the rotating ring 201 is sufficient, and the performance of the sealing film is more stable.

[0050] Preferably, a medium input device is provided outside the medium inlet channel 103 to control the speed at which the sealing medium enters the cavity 101. A medium extraction device is provided outside the medium outlet channel 104 to guide the flow direction of the sealing medium and control the flow speed of the sealing medium.

[0051] Preferably, such as Figure 1 and Figure 2 As shown, the medium inlet channel 103 is tilted to reduce the length of the base 100.

[0052] In one possible implementation, the cavity 101 has two opposing sides, one side having an opening 105 for communicating with the outside, and the other side having the medium channel 102. Accordingly, the rotating ring 201 is located at the opening 105, and the inner circumference of the rotating ring 201 extends outside the opening 105.

[0053] Based on the above design scheme, such as Figure 2 As shown, the two sides of the base 100 are the process side and the atmospheric side, respectively. Two dry gas sealing friction pairs are formed on the basis of the sealing membrane, supplemented by multiple sealing end faces and corresponding static sealing points, which prevent the leakage and escape of the process medium.

[0054] Furthermore, as... Figure 1 As shown, for the sealing medium, a small amount of sealing medium will inevitably flow to both the process side and the atmospheric side, especially when the rotational speed of the rotating ring 201 is low. Therefore, for the process side, the gas-liquid two-phase sealing structure is preferably used in operations that allow trace amounts of sealing medium to enter the process side. For the atmospheric side, the sealing medium is drawn in by external equipment and then recycled to reduce sealing costs.

[0055] In one possible implementation, the rotating ring 201 has two opposing outer surfaces, each with an annular dynamic pressure groove 202 in opposite directions. Based on this design, the two dynamic pressure grooves 202 create sealing films at both ends of the rotating ring 201, resulting in a better sealing effect.

[0056] In one possible implementation, the sealing module 200 further includes two stationary rings 203 respectively disposed on both sides of the rotating ring 201. The stationary rings 203 are slidably disposed on the cavity 101 and abut against the rotating ring 201 by means of elastic members 205.

[0057] When a sealing film is formed outside the rotating ring 201, the rotating ring 201 separates from the stationary ring 203 and forms a gap that fits the sealing film. Correspondingly, the stationary ring 203 maintains the gap width less than the maximum width of the sealing film through the elastic element 205.

[0058] Based on the above design, the stationary ring 203 has two working positions: one is the first working position where it abuts against the rotating ring 201, and the other is the second working position where it disengages from the rotating ring 201. Specifically:

[0059] When the gas-liquid two-phase sealing structure is working, the sealing medium is introduced into the cavity 101, the rotating ring 201 rotates to form a dynamic pressure effect and generate a sealing film, and the stationary ring 203 is pushed away from the rotating ring 201 by the sealing film, thus realizing non-contact sealing.

[0060] Meanwhile, if the gap between the rotating ring 201 and the stationary ring 203 is too large, the sealing performance of the sealing membrane will decrease, and the sealing membrane may even fail to form properly. Therefore, an elastic element 205 is connected to the stationary ring 203. The elastic force of the elastic element 205 maintains the gap width less than the maximum width for sealing membrane formation, ensuring the sealing effect of the sealing membrane.

[0061] In addition, the two stationary rings 203 cooperate with each other to achieve the limiting effect, ensuring that the rotating ring 201 rotates in the designed position.

[0062] When the gas-liquid two-phase sealing structure stops working, the stationary ring 203 abuts against the rotating ring 201 through the elastic element 205, causing the rotating ring 201 to stop rotating. This also serves to fix and limit the rotation, ensuring that the rotating ring 201 is in the designed position.

[0063] It is easy to understand that the elastic element 205 can be any suitable existing component.

[0064] Optionally, such as Figure 2 As shown, the stationary ring 203 has two opposite ends. One end of the stationary ring 203 is configured as a driving end that is slidably disposed on the cavity 101, and the other end of the stationary ring 203 is configured as an abutting end facing the rotating ring 201.

[0065] The stationary ring 203 is provided with a vent 206 for guiding the flow of the sealing medium;

[0066] The abutting end of the stationary ring 203 is provided with a flow channel 207 that communicates with the vent 206. Correspondingly, the vent 206 is connected to the dynamic pressure channel 202 through the flow channel 207.

[0067] The driving end of the stationary ring 203 is connected to the elastic element 205 through the push ring 204. The push ring 204 has two opposing outer wall surfaces, one of which abuts against the stationary ring 203 and the other abuts against the elastic element 205.

[0068] Correspondingly, the push ring 204 is provided with an additional hole that communicates with the vent 206; the outer periphery of the push ring 204 is provided with a floating sealing ring that abuts against the annular area.

[0069] Based on the above design, the stationary ring 203 is provided with a vent 206 to guide the flow of the sealing medium, so that the sealing medium flows along the designed route and contacts the rotating ring 201, ensuring the quality of the sealing film generated by the rotating ring 201. Specifically, after the sealing medium is input into the base 100, the sealing medium flows sequentially through the medium entry channel 103, the additional hole (on the push ring 204), the vent 206, and the drainage groove 207, and then enters the dynamic pressure groove 202.

[0070] For the push ring 204, the connection is achieved through an additional hole to prevent the push ring 204 from blocking the flow of the sealing medium. At the same time, the design of the floating sealing ring not only ensures that the push ring 204 can move back and forth, but also ensures the sealing performance, ensuring that the sealing medium flows from the additional hole into the vent hole 206.

[0071] In one possible implementation, the cavity 101 is provided with an annular region adapted to the stationary ring 203, and a retaining ring is provided on the inner wall surface of the annular region. Correspondingly, the outer periphery of the stationary ring 203 is provided with an inwardly recessed groove 208 adapted to the retaining ring.

[0072] Based on the above design, the retaining ring is inserted into the concave groove 208. When the stationary ring 203 slides, the retaining ring also slides in the concave groove 208 to ensure that the stationary ring 203 will not leave the annular area in a free state. At the same time, the length of the concave groove 208 limits the sliding length of the stationary ring 203, ensuring that the sliding distance of the stationary ring 203 is within the design range.

[0073] In one possible implementation, the gas-liquid two-phase sealing structure further includes a drive shaft 300 and an auxiliary seat 400, with a gap between the drive shaft 300 and the auxiliary seat 400, and the base 100 is disposed in the gap.

[0074] Correspondingly, the base 100 has two opposite sides, one side of which is sleeved on the drive shaft 300 through the bushing 500, and the inner circumference of the rotating ring 201 is connected to the bushing 500 through the sealing ring. The other side abuts against the auxiliary seat 400. Correspondingly, the auxiliary seat 400 is provided with three air holes, and the three air holes correspond one-to-one with and are connected to the three medium channels 102.

[0075] The base 100 has two opposite and parallel ends to the drive shaft 300, wherein the end adjacent to the process medium is provided with an auxiliary plate 600, and the base 100 abuts against the auxiliary plate 600 and is connected to the auxiliary plate 600 by screws.

[0076] Based on the above design, an approximately L-shaped gap is defined by the drive shaft 300, the auxiliary seat 400, and the auxiliary plate 600. The base 100 is installed in this gap, wherein one side of the base 100 abuts against the auxiliary seat 400, and one end face is connected to the auxiliary plate 600 by screws, thereby fixing the position of the base 100.

[0077] The auxiliary seat 400 is connected to the medium channel 102 via an air vent, ensuring smooth inflow and outflow of the sealing medium and guaranteeing the normal operation of the gas-liquid two-phase sealing structure. Furthermore, multiple sealing rings are provided between the auxiliary seat 400 and the base 100, with adjacent sealing rings located on opposite sides of the same air vent. This ensures a tight seal and prevents leakage of the sealing medium.

[0078] For the drive shaft 300, a bushing 500 is fitted onto its outer circumference, thus eliminating the need for additional machining of the drive shaft 300. The gas-liquid two-phase sealing structure is connected to the bushing 500 via a rotating ring 201. A sealing ring is provided between the rotating ring 201 and the bushing 500 to improve sealing performance.

[0079] For bushing 500, its two ends can be connected to drive shaft 300 through fasteners.

[0080] Alternatively, in one possible implementation, the bushing 500 has two ends opposite and parallel to the drive shaft 300, one end being adjacent to the auxiliary plate 600 and provided with a first fastener 501 located outside the auxiliary plate 600, and the other end being provided with a second fastener 502.

[0081] It is easy to understand that the first fastener 501 and the second fastener 502 can be any suitable existing fastening components or fastening structures, which will not be elaborated here.

[0082] Based on the aforementioned gas-liquid two-phase sealing structure, a single-screw expander is introduced, which includes the aforementioned gas-liquid two-phase sealing structure. Furthermore, the gas-liquid two-phase sealing structure can also be used in any other suitable equipment.

[0083] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this utility model. It should be understood that the above description is only a specific embodiment of this utility model and is not intended to limit the scope of protection of this utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the scope of protection of this utility model.

Claims

1. A gas-liquid two-phase seal structure, characterized by, The base (100) and the sealing module (200) are included. The base (100) is provided with a cavity (101) communicating with the outside world. The sealing module (200) includes a rotating ring (201) located in the cavity (101), and the rotating ring (201) rotates to form a dynamic pressure effect and generate a sealing film.

2. The gas-liquid two-phase seal structure according to claim 1, characterized by, The base (100) is provided with three medium channels (102) arranged at intervals, and the two ends of the medium channel (102) are respectively connected to the cavity (101) and the outside world, and the two medium channels (102) located on both sides are respectively configured as medium inlet channels (103) located at both ends of the rotating ring (201), and the medium channel (102) located in the middle is configured as a medium discharge channel (104) corresponding to the rotating ring (201).

3. The gas-liquid two-phase seal structure according to claim 2, characterized by, The cavity (101) has opposite sides, one side is provided with an opening (105) for communicating with the outside world, and the other side is provided with the medium channel (102), and correspondingly, the rotating ring (201) is located at the opening (105), and the inner circumference of the rotating ring (201) extends to the outside of the opening (105).

4. The gas-liquid two-phase seal structure according to any one of claims 1 to 3, characterized by, The rotating ring (201) has two opposite outer surfaces, and the two outer surfaces are respectively provided with annular dynamic pressure grooves (202) with opposite rotation directions.

5. The gas-liquid two-phase seal structure according to claim 4, wherein The sealing module (200) further includes two static rings (203) respectively arranged on both sides of the rotating ring (201), and the static ring (203) is slidably arranged on the cavity (101) by the elastic element (205) and abuts against the rotating ring (201); When the rotating ring (201) generates a sealing film outside, the rotating ring (201) and the static ring (203) are separated and form a gap suitable for the sealing film, and correspondingly, the static ring (203) maintains the gap width smaller than the maximum width of the sealing film through the elastic element (205).

6. The gas-liquid two-phase seal structure according to claim 5, wherein The static ring (203) has opposite ends, one end of the static ring (203) is configured as a driving end slidably arranged on the cavity (101), and the other end of the static ring (203) is configured as an abutting end facing the rotating ring (201); The static ring (203) is provided with a vent hole (206) for guiding the flow direction of the sealing medium; The abutting end of the static ring (203) is provided with a drainage groove (207) communicating with the vent hole (206), and correspondingly, the vent hole (206) communicates with the dynamic pressure groove (202) through the drainage groove (207); The driving end of the static ring (203) is connected to the elastic element (205) through a push ring (204), and the push ring (204) has two opposite outer walls, one of which abuts against the static ring (203), and the other abuts against the elastic element (205); Correspondingly, the push ring (204) is provided with an additional hole communicating with the vent hole (206); and the outer periphery of the push ring (204) is provided with a floating seal ring abutting against the annular area.

7. The gas-liquid two-phase seal structure according to claim 6, wherein The cavity (101) is provided with an annular area matched with the static ring (203), and the inner wall surface of the annular area is provided with a clasp, and correspondingly, the outer periphery of the static ring (203) is provided with a first limiting piece and a second limiting piece located on both sides of the clasp.

8. The gas-liquid two-phase sealed structure according to any one of claims 1 to 3, wherein It also includes a transmission shaft (300) and an additional seat (400), and a gap is left between the transmission shaft (300) and the additional seat (400), and the base (100) is arranged on the gap. Correspondingly, the base (100) has two opposite sides, one side of which is sleeved on the transmission shaft (300) through the shaft sleeve (500), and the inner periphery of the rotating ring (201) is connected to the shaft sleeve (500) through a sealing ring, and the other side abuts against the additional seat (400). Correspondingly, the additional seat (400) is provided with three air holes, which are one-to-one corresponding to and communicated with the three medium channels (102). The base (100) has two opposite and parallel ends relative to the transmission shaft (300), one end of which is provided with an additional plate (600). Correspondingly, the base (100) abuts against the additional plate (600) and is connected to the additional plate (600) through a screw.

9. The gas-liquid two-phase seal structure according to claim 8, wherein A plurality of sealing rings are arranged between the additional seat (400) and the base (100), and adjacent two sealing rings are located on two sides of the same air hole. The shaft sleeve (500) has two opposite and parallel ends relative to the transmission shaft (300), one end of which is adjacent to the additional plate (600) and is provided with a first fixing member (501) located outside the additional plate (600), and the other end is provided with a second fixing member (502).

10. A single screw expander characterized by, The gas-liquid two-phase sealing structure of any one of claims 1-9.

Images