Continuous discharge device for a vacuum drier

Abstract

This utility model relates to a continuous discharge device for a vacuum dryer, comprising a material receiving pipe, a conveying and extruding screw assembly, a variable diameter conveying pipe, a limit detection device, a back pressure conveying screw assembly, and a discharge conveying pipe; the top of the material receiving pipe is connected to the discharge port of the vacuum dryer; the bottom of the material receiving pipe is connected to the inlet of the variable diameter conveying pipe; the outer diameter and pitch of the variable diameter compression screw of the conveying and extruding screw assembly linearly decrease from the large lead conveying screw to the pressurized conveying screw; the conveying and extruding screw assembly is rotatably installed inside the variable diameter conveying pipe and is driven to rotate by a conveying and extruding screw drive device; the inlet end of the discharge conveying pipe is movably sleeved on the outer side of the end of the variable diameter conveying pipe, and the connection between the two is provided with a limit detection device for detecting the material pressure at the connection; the back pressure conveying screw assembly is rotatably installed inside the discharge conveying pipe and is driven to rotate by a back pressure conveying and extruding screw drive device.

Description

Technical Field

[0001] This utility model relates to a continuous discharge device for a vacuum dryer, belonging to the field of vacuum drying equipment technology application for solid waste treatment and disposal. Background Technology

[0002] Vacuum drying equipment is a widely used drying equipment, and most of it on the market currently adopts a non-continuous discharge structure.

[0003] The existing discharge method uses front and rear valve switching to achieve intermittent discharge, as disclosed in Chinese invention patent application CN118816484A entitled "Vacuum Dryer System and Dryer Feeding and Discharging Method". Its so-called continuous discharge structure is merely intermittent discharge with a high discharge frequency, and cannot achieve truly continuous discharge.

[0004] Furthermore, the discharge mechanism of most vacuum dryers allows a lot of air to enter the drying system through the switching of pre- and post-stage valves. Intermittent discharge can lead to uneven discharge, and some air entering the drying chamber can affect the vacuum level of the drying environment, reduce equipment stability, and affect the drying effect.

[0005] In addition, the existing discharge method has strict requirements on materials and is only suitable for materials with good compressibility and relatively soft texture; it is not suitable for materials with low compressibility and the presence of impurities and hard objects.

[0006] In summary, the vacuum drying industry urgently needs a discharge device that can truly achieve continuous vacuum and continuous material discharge, and can operate stably under conditions of high compressibility, low compressibility, and the presence of hard impurities. Utility Model Content

[0007] In order to solve the above-mentioned problems existing in the prior art, the present invention provides a continuous discharge device for a vacuum dryer.

[0008] The technical solution of this utility model is as follows: a continuous discharge device for a vacuum dryer, comprising a material receiving pipe, a conveying and extruding screw assembly, a variable diameter conveying pipe, a limit detection device, a back pressure conveying screw assembly, and a discharge conveying pipe;

[0009] The top of the discharge pipe is connected to the outlet of the vacuum dryer; the bottom of the discharge pipe is connected to the inlet of the variable diameter conveying pipe.

[0010] The conveying and extruding screw assembly includes a large-lead conveying screw, a variable-diameter compression screw, and a pressurizing conveying screw arranged sequentially along the material conveying direction. The large-lead conveying screw is configured with equal diameter and pitch, as is the pressurizing conveying screw. The outer diameter and pitch of the variable-diameter compression screw linearly decrease from the large-lead conveying screw to the pressurizing conveying screw. The conveying and extruding screw assembly is rotatably installed inside the variable-diameter conveying pipe and is driven to rotate by a conveying and extruding screw drive device. The variable-diameter conveying pipe has a straight vacuum-sealed section behind the conveying and extruding screw assembly.

[0011] The feed end of the discharge conveying pipe is movably sleeved on the outside of the end of the variable diameter conveying pipe, and the connection between the two is provided with a limit and a limit detection device for detecting the material pressure at the connection.

[0012] The reverse pressure conveying screw assembly is rotatably installed inside the discharge conveying pipe and is driven to rotate by a reverse pressure conveying extrusion screw drive device. The discharge conveying pipe has a discharge port behind the reverse pressure conveying screw assembly. The automatic control system controls the reverse pressure conveying screw assembly to lock or rotate either, based on the material pressure value detected by the limit detection device and the reverse pressure conveying extrusion screw drive device.

[0013] In a preferred embodiment of this utility model, the limit detection device includes a fixed mounting block fixedly mounted on the variable diameter conveying pipe, a movable limit block fixedly mounted on the discharge conveying pipe, and a guide rod. One end of the guide rod is locked to the fixed mounting block by a mounting nut. A limit nut that blocks the movable limit block is connected to the guide rod located between the fixed mounting block and the movable limit block. An adjusting nut is connected to the guide rod on the side of the movable limit block away from the limit nut. A buffer spring is sleeved on the guide rod between the adjusting nut and the movable limit block. The buffer spring is always in a compressed state. A pressure sensor is provided between the adjusting nut and the buffer spring. One end of the buffer spring rests on the movable limit block, and the other end rests on the pressure sensor.

[0014] In a preferred embodiment of this utility model, a linear bearing is provided in the mounting hole of the movable limiting block, and the guide rod extends through the linear bearing to the outside of the movable limiting block.

[0015] In a preferred embodiment of this utility model, the variable diameter conveying pipe sequentially includes a conveying section, a compaction transition section, and a straight pipe conveying and pressurizing section; the inner diameter of the conveying section is adapted to the outer diameter of the large lead conveying screw of the conveying extrusion screw assembly; the inner diameter of the compaction transition section is adapted to the outer diameter of the variable diameter compression screw of the conveying extrusion screw assembly; and the inner diameter of the straight pipe conveying and pressurizing section is adapted to the outer diameter of the pressurizing conveying screw of the conveying extrusion screw assembly.

[0016] In a preferred embodiment of the present invention, the variable diameter conveying pipe is provided with a reduced diameter transition section between the straight pipe conveying pressurization section and the vacuum sealing section.

[0017] In a preferred embodiment of this utility model, the unit volume of the straight pipe conveying pressurization section and the vacuum sealing section is the same.

[0018] In a preferred embodiment of the present invention, the counter-pressure conveying screw assembly includes a discharge conveying screw, and a crushing drill bit with a conical structure is provided at one end of the discharge conveying screw near the variable diameter conveying pipe.

[0019] In a preferred embodiment of this utility model, the outer diameter of the discharge conveying screw is adapted to the inner diameter of the discharge conveying pipe.

[0020] In a preferred embodiment of this utility model, a laser level gauge for real-time detection of material height is provided inside the material discharge pipe.

[0021] In a preferred embodiment of this utility model, the single-sided gap between the inner diameter of the discharge conveying pipe and the outer diameter of the final outlet of the variable diameter conveying pipe is less than or equal to 1 mm.

[0022] Compared with the prior art, the beneficial effects of this utility model are:

[0023] 1. This utility model is a continuous discharge device for a vacuum dryer. Through the variable diameter compression design of the conveying extrusion screw and the sealing structure, the material forms a continuous "compacted and sealed material column" in the variable diameter conveying pipe, isolating the vacuum environment inside the dryer from the external atmosphere. Compared with the intermittent discharge of traditional valve switching, this structure, combined with an automatic control system, achieves truly continuous discharge with no air intrusion throughout the process, maintaining a stable vacuum and avoiding the impact of vacuum fluctuations on drying efficiency and material quality.

[0024] 2. This utility model is a continuous discharge device for a vacuum dryer. The crushing and counter-pressure screw, through rotation and the front crushing drill bit, can effectively crush impurities and hard objects in the material. With the limit pressure measuring device, the pressure of the sealing section can be monitored in real time, and the speed of the crushing screw can be automatically adjusted. The material level height is fed back in real time through the laser level gauge, and the automatic control system is linked to dynamically adjust the speed of the conveying and extruding screw, forming a closed-loop control of "material level, pressure and speed". It can handle highly compressible soft materials, as well as low compressibility or complex materials containing hard objects (such as sludge and chemical raw materials containing particles). It avoids the clogging or uneven discharge problems caused by material characteristics in traditional structures, while reducing manual intervention and improving discharge stability and control accuracy.

[0025] 3. This utility model is a continuous discharge device for a vacuum dryer. The bearing assembly adopts a composite design, which takes into account both axial and radial load bearing capacity. With the help of a buffer protection device, it reduces mechanical wear and impact risk, extends the service life of key components, reduces maintenance frequency, and improves the long-term operational reliability of the equipment. In addition, the synergistic effect of the crushing reverse spiral and the variable diameter conveying pipe enables the equipment to adapt to a wide range of materials, from highly compressible soft materials to low compressible materials containing impurities, and can work stably in different vacuum ranges, breaking the material and working condition limitations of traditional structures. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the continuous discharge device of the vacuum dryer of this utility model;

[0027] Figure 2 This is a schematic diagram of the conveying and extrusion screw assembly of this utility model;

[0028] Figure 3 This is a schematic diagram of the limit detection device of this utility model;

[0029] Figure 4 This is a schematic diagram of the reverse pressure conveying spiral assembly of this utility model.

[0030] The reference numerals in the figure are as follows:

[0031] 1. Feed pipe; 2. Laser level gauge; 3. Conveying and extruding screw drive device; 4. Bearing assembly; 5. Sealing structure; 6. Conveying and extruding screw assembly; 7. Variable diameter conveying pipe; 8. Limit detection device; 9. Back pressure conveying screw assembly; 10. Discharge conveying pipe; 11. Back pressure conveying and extruding screw drive device; 61. Large lead conveying screw; 62. Variable diameter compression screw; 63. Pressurized conveying screw; 71. Conveying section; 72. Compaction transition section; 73. Straight pipe conveying pressurized section; 74. Variable diameter transition section; 75. Vacuum sealing section; 81. Fixed mounting block; 82. Mounting nut; 83. Guide tie rod; 84. Limit nut; 85. Movable limit block; 86. Linear bearing; 87. Buffer spring; 88. Pressure sensor; 89. Adjusting nut; 91. Crushing drill bit; 92. Discharge conveying section. Detailed Implementation

[0032] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0033] Please see Figure 1 This utility model provides a continuous discharge device for a vacuum dryer. The continuous discharge device includes a material receiving pipe 1, a conveying and extruding screw drive device 3, a conveying and extruding screw assembly 6, a variable diameter conveying pipe 7, a limit detection device 8, a back pressure conveying screw assembly 9, a discharge conveying pipe 10, and a back pressure conveying and extruding screw drive device 11.

[0034] The top of the discharge pipe 1 is connected to the outlet of the vacuum dryer; the bottom of the discharge pipe 1 is connected to the inlet of the variable diameter conveying pipe 7. A laser level gauge 2 is installed inside the discharge pipe 1. The laser level gauge 2 detects the material height in real time to ensure that the material height reaches the preset material level requirement to fill the variable diameter conveying pipe 7.

[0035] Please see Figure 2 The conveying and extruding screw assembly 6 can be a shafted screw conveyor. The conveying and extruding screw assembly 6 includes a large-lead conveying screw 61, a variable-diameter compression screw 62, and a pressurizing conveying screw 63 arranged sequentially along the material conveying direction. The large-lead conveying screw 61 is set with equal diameter and equal pitch, and the pressurizing conveying screw 63 is set with equal diameter and equal pitch. The outer diameter and pitch of the variable-diameter compression screw 62 gradually decrease from the large-lead conveying screw 61 to the pressurizing conveying screw 63. The axial length ratio of the large-lead conveying screw 61, the variable-diameter compression screw 62, and the pressurizing conveying screw 63 is (2.5-3.5):1:(1.5-2.5). The large-lead conveying screw 61 at the front end of the conveying and extrusion screw assembly 6 has a large lead, and the conveying capacity in this section is large, with the material in a loose state. The outer diameter and pitch of the variable-diameter compression screw 62 gradually decrease, which helps to gradually compress the material and improve the conveying efficiency. The pitch of the pressure conveying screw 63 after the diameter change at the rear end is reduced, and the conveying capacity is reduced. Its function is to compress the loose and large-volume material at the front end to achieve a certain degree of compaction, ensuring that the material can fill the entire cavity of the conveying screw.

[0036] One end of the conveying extrusion screw assembly 6 is rotatably mounted inside the connecting variable-diameter conveying pipe 7 via a bearing assembly 4, and is driven to rotate by the conveying extrusion screw drive device 3. The bearing assembly 4 includes a thrust bearing and cylindrical roller bearings to withstand the axial and radial forces generated by the extrusion of the conveying extrusion screw assembly 6.

[0037] The variable-diameter conveying pipe 7 sequentially includes a conveying section 71, a compaction transition section 72, a straight-pipe conveying and pressurizing section 73, a variable-diameter transition section 74, and a vacuum-sealed section 75. The inner diameter of the conveying section 71 is adapted to the outer diameter of the large-lead conveying screw 61 of the conveying extrusion screw assembly 6; the inner diameter of the compaction transition section 72 is adapted to the outer diameter of the variable-diameter compression screw 62 of the conveying extrusion screw assembly 6; and the inner diameter of the straight-pipe conveying and pressurizing section 73 is adapted to the outer diameter of the pressurizing conveying screw 63 of the conveying extrusion screw assembly 6.

[0038] The variable diameter conveying pipe 7 has a variable diameter transition section 74 that connects to the straight pipe conveying and pressurizing section 73 and features a reduced diameter design. After the diameter change in the variable diameter transition section 74, a straight section forms the vacuum sealing section 75. The straight pipe conveying and pressurizing section 73 and the vacuum sealing section 75 have the same unit volume, which minimizes the total thrust requirement (the larger the area, the greater the thrust). At the same time, it reduces unnecessary extrusion power on the sludge (for materials with low compressibility, variable diameter extrusion will generate significant running resistance on the pipe wall), and prevents uneven pressure caused by pores at the top of the discharge conveying pipe due to inconsistent volumes.

[0039] The feed end of the discharge conveying pipe 10 is movably sleeved on the outside of the end of the variable diameter conveying pipe 7. The inner diameter of the discharge conveying pipe 10 is slightly larger than the outer diameter of the final outlet of the variable diameter conveying pipe 7. In this embodiment, the single-sided gap between the inner diameter of the discharge conveying pipe 10 and the outer diameter of the final outlet of the variable diameter conveying pipe 7 is 0.5 mm.

[0040] Please see Figure 3 The connection between the discharge conveying pipe 10 and the variable diameter conveying pipe 7 is equipped with a limit detection device 8 for limiting and detecting the material pressure at the connection. The limit detection device 8 includes a fixed mounting block 81, a mounting nut 82, a guide rod 83, a limit nut 84, a movable limit block 85, a linear bearing 86, a buffer spring 87, a pressure sensor 88, and an adjusting nut 89. The fixed mounting block 81 is fixedly mounted on the variable diameter conveying pipe 7, and the movable limit block 85 is fixedly mounted on the discharge conveying pipe 10; the linear bearing 86 is disposed within the mounting hole of the movable limit block 85. The guide rod 83 passes through the mounting hole on the fixed mounting block 81 and connects to the mounting nut, locking one end of the guide rod 83 to the fixed mounting block 81 through the cooperation of the guide rod 83 and the mounting nut 82. The guide rod 83 is connected to the middle section of the limiting nut 84. The limiting nut 84 is located between the fixed mounting block 81 and the movable limiting block 85 and blocks the movable limiting block 85. The other end of the guide rod 83 passes through the linear bearing 86. Setting the linear bearing 86 can reduce frictional resistance and limit the movement of the discharge conveying pipe 10 except in the axial direction, ensuring that the pressure sensor only bears axial pressure.

[0041] An adjusting nut 89 is connected to the guide rod 83 on the side of the movable limit block 85 away from the limit nut 84. A buffer spring 87 is sleeved on the guide rod 83 between the adjusting nut 89 and the movable limit block 85. A pressure sensor 88 is installed between the adjusting nut 89 and the buffer spring 87. One end of the buffer spring 87 rests on the movable limit block 85, and the other end rests on the pressure sensor 88. The preload of the buffer spring 87 can be adjusted by adjusting the relative positions of the limit nut 84 and the adjusting nut 89 on the guide rod 83, so that the buffer spring 87 is always in a compressed state and always presses against the pressure sensor 88. Since the buffer spring 87 is always in a compressed state, when the material at the front end is conveyed forward, it should be blocked by the conveying screw assembly 9 and cannot move forward. The material continuously conveyed forward at the rear end continuously squeezes the material at the front end, generating a compacting force to achieve compaction. At this time, the buffer spring 87 can buffer the pressure generated by the material, keeping the compacted material in a compacted state. In this embodiment, no fewer than three sets of limit detection devices 8 are evenly distributed within a circumferential range to balance the pressure in the circumferential direction.

[0042] Please see Figure 4 The counter-pressure conveying screw assembly 9 is rotatably connected to the inside of the discharge conveying pipe 10 via a bearing assembly 4, and is driven to rotate by the counter-pressure conveying extrusion screw drive device 11. The counter-pressure conveying screw assembly 9 includes a crushing drill bit 91 and a discharge conveying section 92. The discharge conveying section 92 has a tapered crushing drill bit 91 at one end near the variable diameter conveying pipe 7, and the outer diameter of the discharge conveying section 92 is adapted to the inner diameter of the discharge conveying pipe 10. A discharge port is located at the bottom of the discharge conveying pipe 10, relatively away from the crushing drill bit 91. The function of the counter-pressure conveying screw assembly 9 is to create a sealed compaction of the material by blocking it. When the pressure sensor of the limit detection device 8 detects that the pressure reaches a preset pressure threshold, the counter-pressure conveying screw assembly 9 rotates to crush and convey the compacted material.

[0043] Based on the material level height fed back by the laser level gauge 2 and the material pressure at the connection between the discharge conveying pipe 10 and the variable diameter conveying pipe 7 fed back by the pressure sensor 88, the automatic control system controls the start and stop of the conveying extrusion screw assembly 6 and the counter-pressure conveying screw assembly 9 and the discharge speed.

[0044] The dryer has a vacuum drying chamber inside and normal atmospheric pressure outside. Because the material in the vacuum sealing section of the variable diameter conveying pipe 7 is constantly compressed, the material in the vacuum sealing section can act as a material seal, preventing air from the atmospheric side of the discharge port from entering the discharge device. This ensures that the internal vacuum pressure is maintained during the continuous discharge of material, and the system operates stably.

[0045] The specific steps of the continuous discharge device of this utility model to achieve the continuous discharge process are as follows:

[0046] The vacuum pressure inside the vacuum dryer is -0.09 MPa, and the minimum pressure required to achieve vacuum sealing in the vacuum sealing section of the variable diameter conveying pipe 7 is 10,000 Pa.

[0047] S1. Feed the material into the discharge pipe 1 from the outlet of the vacuum dryer. If the laser level gauge 2 detects that the material has accumulated to the preset first level, start timing; otherwise, continue feeding.

[0048] S2. If the laser level gauge 2 detects that the material has accumulated to the preset second level, the initial discharge speed of the dryer is calculated. At this time, the automatic control system starts the conveying extrusion screw drive device 3 to drive the conveying extrusion screw assembly 6 to start rotating. The conveying extrusion screw assembly 6 discharges the material according to the calculated discharge speed. The material level data is recorded every 20 seconds, and the material level height at the current time and the previous time are compared.

[0049] S3. If the material level increases, adjust the current discharge speed; further determine whether the third material level has been reached. If it has, maintain the current discharge speed until the material level reaches the first material level.

[0050] S4. Otherwise, further determine whether the material level has decreased. If the material level has not decreased, maintain the initial discharge speed. Otherwise, further determine whether the material level has decreased to the first material level. If so, control the conveying extrusion screw assembly 6 to stop discharging. Otherwise, adjust the current discharge speed.

[0051] S5. As the conveying and extrusion screw assembly 6 rotates, the material is slowly conveyed forward by the large-lead conveying screw 61, at which time the material is in a loose state.

[0052] S6. As the material passes through the variable diameter compression screw 62, the diameter of the variable diameter conveying pipe 7 gradually decreases and the pitch of the variable diameter compression screw 62 gradually decreases. The material is compressed to a certain degree of compaction, and the pressurizing conveying screw 63 of the variable diameter conveying pipe 7 is filled. After passing through the large lead conveying screw 61 and the variable diameter compression screw 62, the material enters the pressurizing conveying screw 63. Since the unit volume of the straight pipe pressurizing section at the end of the variable diameter compression screw 62 is the same as the unit volume at the pressurizing conveying screw 63, the pressurizing conveying screw 63 is also filled at this time.

[0053] S7. The material continues to be conveyed forward until it reaches the crushing reverse spiral assembly 9. Since the crushing reverse spiral assembly 9 is in a locked state at this time, the material cannot continue to move forward and will become blocked. Meanwhile, the material at the rear continues to be conveyed forward and squeezes the blocked material, continuously transferring the thrust generated by the squeeze to the crushing reverse spiral assembly 9.

[0054] S8. The crushing reverse screw assembly 9 is pushed backward. During this process, the discharge conveying pipe 10 is relatively displaced relative to the variable diameter conveying pipe 7, and is subjected to the reaction force of the crushing reverse screw assembly, generating a counter-thrust force to push the material back, ensuring that the material is always in a compressed state.

[0055] S9. The pressure generated by the material extrusion of the pressurized conveying screw 63 is transmitted to the pressure sensor 88 of the limit pressure measuring device 8. If the pressure sensor 88 detects that the current pressure has reached the preset second sensor pressure, it controls the reverse pressure conveying screw assembly 9 to rotate; otherwise, it continues to convey the material. The pressure data is recorded every 5 seconds, and the pressure difference between the current time and the previous time is compared.

[0056] S10. If the pressure difference increases, further determine whether the current pressure has reached the third sensing pressure. If so, maintain the current discharge speed; otherwise, adjust the current discharge speed.

[0057] S11. Otherwise, further determine whether the pressure difference has decreased. If the pressure difference has not decreased, maintain the initial discharge speed. Otherwise, further determine whether the material level has decreased to the preset first sensing pressure. If so, control the conveying reverse pressure conveying screw assembly 9 to stop discharging. Otherwise, adjust the current discharge speed.

[0058] S12, the crushing drill bit 91 of the counter-pressure conveying screw assembly 9 crushes the material, and the crushed material is conveyed to the discharge port of the dryer through the discharge conveying section 92 of the counter-pressure conveying screw assembly 9.

[0059] In this application embodiment, "at least one" refers to one or more, and "more than one" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent the existence of A alone, A and B simultaneously, or B alone. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one of the following" and similar expressions refer to any combination of these items, including any combination of singular or plural items. For example, at least one of a, b, and c can represent: a, b, c, a and b, a and c, b and c, or a and b and c, where a, b, and c can be single or multiple.

[0060] The above description is merely an embodiment of this utility model and does not limit the patent scope of this utility model. Any equivalent structural or procedural transformations made based on the description and drawings of this utility model, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this utility model.

Claims

1. A continuous discharge device for a vacuum dryer, characterized in that, It includes a material receiving pipe (1), a conveying and extrusion screw assembly (6), a variable diameter conveying pipe (7), a limit detection device (8), a back pressure conveying screw assembly (9), and a discharge conveying pipe (10); The top of the discharge pipe (1) is connected to the outlet of the vacuum dryer; the bottom of the discharge pipe (1) is connected to the inlet of the variable diameter conveying pipe (7); The conveying extrusion screw assembly (6) includes a large-lead conveying screw (61), a variable-diameter compression screw (62), and a pressurizing conveying screw (63) arranged sequentially along the material conveying direction. The large-lead conveying screw (61) is set with equal diameter and equal pitch, and the pressurizing conveying screw (63) is set with equal diameter and equal pitch. The outer diameter and pitch of the variable-diameter compression screw (62) decrease linearly from the large-lead conveying screw (61) to the pressurizing conveying screw. The conveying extrusion screw assembly (6) is rotatably installed inside the variable-diameter conveying pipe (7) and is driven to rotate by a conveying extrusion screw drive device (3). The variable-diameter conveying pipe (7) has a straight vacuum-sealed section (75) behind the conveying extrusion screw assembly (6). The feed end of the discharge conveying pipe (10) is movably sleeved on the outside of the end of the variable diameter conveying pipe (7), and the connection between the two is provided with a limit and a limit detection device (8) for detecting the material pressure at the connection. The reverse pressure conveying screw assembly (9) is rotatably installed inside the discharge conveying pipe (10) and is driven to rotate by a reverse pressure conveying extrusion screw drive device (11). The discharge conveying pipe (10) has a discharge port behind the reverse pressure conveying screw assembly (9). The automatic control system controls the reverse pressure conveying screw assembly (9) to lock or rotate either by the reverse pressure conveying extrusion screw drive device (11) based on the material pressure value detected by the limit detection device (8).

2. The continuous discharge device for a vacuum dryer according to claim 1, characterized in that, The limiting detection device (8) includes a fixed mounting block (81) fixedly mounted on the variable diameter conveying pipe (7), a movable limiting block (85) fixedly mounted on the discharge conveying pipe (10), and a guide rod (83). One end of the guide rod (83) is locked to the fixed mounting block (81) by a mounting nut (82). A limiting nut (84) that blocks the movable limiting block (85) is connected to the guide rod (83) located between the fixed mounting block (81) and the movable limiting block (85). (83) An adjusting nut (89) is connected to the side of the movable limiting block (85) away from the limiting nut (84). A buffer spring (87) is sleeved on the guide rod (83) between the adjusting nut (89) and the movable limiting block (85). The buffer spring (87) is always in a compressed state. A pressure sensor (88) is provided between the adjusting nut (89) and the buffer spring (87). One end of the buffer spring (87) rests on the movable limiting block (85), and the other end rests on the pressure sensor (88).

3. The continuous discharge device for a vacuum dryer according to claim 2, characterized in that, A linear bearing (86) is installed in the mounting hole of the movable limit block (85), and the guide rod (83) extends through the linear bearing (86) to the outside of the movable limit block (85).

4. The continuous discharge device for a vacuum dryer according to claim 1, characterized in that, The variable diameter conveying pipe (7) includes a conveying section (71), a compaction transition section (72), and a straight pipe conveying pressurization section (73) in sequence; the inner diameter of the conveying section (71) is adapted to the outer diameter of the large lead conveying screw (61) of the conveying extrusion screw assembly (6); the inner diameter of the compaction transition section (72) is adapted to the outer diameter of the variable diameter compression screw (62) of the conveying extrusion screw assembly (6); and the inner diameter of the straight pipe conveying pressurization section (73) is adapted to the outer diameter of the pressurization conveying screw (63) of the conveying extrusion screw assembly (6).

5. The continuous discharge device for a vacuum dryer according to claim 4, characterized in that, The variable diameter conveying pipe (7) has a reduced diameter transition section (74) between the straight pipe conveying pressurization section (73) and the vacuum sealing section (75).

6. The continuous discharge device for a vacuum dryer according to claim 4, characterized in that, The straight pipe pressurization section (73) and the vacuum sealing section (75) have the same unit volume.

7. The continuous discharge device for a vacuum dryer according to claim 1, characterized in that, The counter-pressure conveying screw assembly (9) includes a discharge conveying screw (92), and a cone-shaped crushing drill bit (91) is provided at one end of the discharge conveying screw (92) near the variable diameter conveying pipe (7).

8. The continuous discharge device for a vacuum dryer according to claim 7, characterized in that, The outer diameter of the discharge conveying spiral (92) is adapted to the inner diameter of the discharge conveying pipe (10).

9. The continuous discharge device for a vacuum dryer according to claim 1, characterized in that, The material discharge pipe (1) is equipped with a laser level gauge (2) for real-time detection of material height.

10. The continuous discharge device for a vacuum dryer according to claim 1, characterized in that, The single-sided gap between the inner diameter of the discharge conveying pipe (10) and the outer diameter of the final outlet of the variable diameter conveying pipe (7) is less than or equal to 1 mm.

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