A multi-stage shaft seal device for horizontal agitator

Abstract

This utility model discloses a multi-stage shaft sealing device for a horizontal mixing equipment, relating to the field of mixing shaft sealing. It includes a first-stage spiral sealing structure, a second-stage oil seal assembly, and a third-stage mechanical seal assembly arranged sequentially. The first-stage spiral sealing structure includes a threaded groove formed on the mixing shaft. The second-stage oil seal assembly includes multiple sets of oil seals fitted onto the outer side of the mixing shaft and oil seal seats fitted around the outer periphery of the multiple sets of oil seals. Oil seal glands are fixed to the oil seal seats by studs, and the oil seal seats are fixed to the end cover plates by countersunk bolts. The third-stage mechanical seal assembly includes a bearing housing, a bearing gland, and a mechanical seal. The bearing housing is fixedly connected to the frame by a support plate. A buffer cavity is formed within the frame between the second-stage oil seal assembly and the third-stage mechanical seal assembly. This application effectively prevents material leakage and reduces the pressure difference between the two sealing ends through the synergistic effect of the multi-stage sealing structure. Furthermore, the maintenance of each stage of the seal is convenient, reducing equipment maintenance costs and downtime.

Description

Technical Field

[0001] This utility model relates to the technical field of stirring shaft sealing, and more specifically, to a multi-stage shaft sealing device for a horizontal stirring equipment. Background Technology

[0002] Horizontal mixing equipment plays a vital role in the industrial field, widely used in complex processes such as polycondensation, polymer devolatilization, polymer degassing, and distillation residue concentration. With the rapid development of industrial technology, these processes are constantly moving towards higher complexity and precision, placing increasingly stringent performance requirements on mixing equipment. Especially when handling high-viscosity, high-vacuum, and high-temperature materials, the unique physical properties of these materials present unprecedented challenges to the sealing of the mixing shaft. At the same time, new processes and materials are constantly emerging, leading to increasingly diverse applications for horizontal mixing equipment, covering more special working conditions and complex environments. This places higher expectations on the reliability and ease of maintenance of its sealing devices. Only with excellent sealing performance and convenient maintenance can the mixing equipment operate stably under various complex conditions, improving production efficiency and product quality.

[0003] In existing technologies, the sealing of the agitator shaft in horizontal mixing equipment is typically addressed using the following methods. One approach involves installing only one seal on the horizontal equipment, allowing the sealing element to directly contact the material. This simple and direct design proves inadequate under complex operating conditions. Another method employs multiple seals, integrating them into a single unit installed between the agitator shaft support (bearing) and the equipment cylinder. While this increases the sealing layers, it also introduces difficulties in assembly and disassembly. A more common shaft seal assembly design consists of two seals: an external mechanical seal and a five-ring packing seal between the mechanical seal and the end cap. The mechanical seal isolates the equipment cylinder from external atmospheric pressure and the material inside to withstand pressure, while the packing seal attempts to block material from entering the mechanical seal. The packing seal achieves sealing by compressing the packing gland with pressure, causing deformation of the packing packing and reducing the gaps between the packing packing and the shaft sleeve, and between the packing packing and the sealing seat. However, in practical applications, these sealing methods have all revealed their respective drawbacks.

[0004] In summary, how to design a multi-stage shaft sealing device that can adapt to high vacuum and high viscosity conditions and enable convenient maintenance in large horizontal equipment is a problem that urgently needs to be solved by those skilled in the art. Utility Model Content

[0005] In view of this, the purpose of this utility model is to provide a multi-stage shaft sealing device for horizontal mixing equipment, which effectively solves the shaft seal leakage problem under high vacuum and high viscosity conditions, and at the same time realizes convenient maintenance of large equipment.

[0006] To achieve the above objectives, this utility model provides the following technical solution:

[0007] A multi-stage shaft sealing device for a horizontal mixing equipment includes a first-stage spiral sealing structure, a second-stage oil seal assembly, and a third-stage mechanical seal assembly arranged sequentially. The first-stage spiral sealing structure includes a threaded groove formed on the mixing shaft, and the threaded groove fits against the inner wall of the hole in the end cover plate.

[0008] The secondary oil seal assembly includes multiple sets of oil seals sleeved on the side of the stirring shaft located outside the vessel and oil seal seats sleeved on the outer periphery of the multiple sets of oil seals. One end of the oil seal seat abuts against the end cover plate, and the other end of the oil seal seat is provided with an oil seal cap. The oil seal cap is provided with studs to fix the oil seal cap to the oil seal seat, and the oil seal seat is provided with countersunk bolts to fix the oil seal seat to the end cover plate.

[0009] The three-stage mechanical seal assembly includes a bearing housing located at the fulcrum of the stirring shaft, a bearing cap located at the end of the bearing housing for sealing the bearing housing, and a mechanical seal. The bearing housing is fixedly connected to the frame via a support plate. A buffer cavity is formed inside the frame between the two-stage oil seal assembly and the three-stage mechanical seal assembly. The mechanical seal is sleeved on the stirring shaft and is fixed to the bearing cap.

[0010] Preferably, the threaded groove is provided along the axial length of the stirring shaft according to the wall thickness of the end cover plate, and the threaded groove extends through the entire wall thickness of the end cover plate along the axial length of the stirring shaft and ends inside the vessel.

[0011] Preferably, the oil seal group consists of two groups, each group having two oil seals arranged back-to-back. All oil seals are split skeleton oil seals, and the two groups of oil seals are separated by an oil ring.

[0012] Preferably, the oil seal is provided with an elastic element so that the lip of the oil seal abuts against the outer wall of the stirring shaft.

[0013] Preferably, the outer periphery of the oil ring has an inlet and an outlet, the inner periphery of the oil ring is a cavity, and both are connected to the inlet and the outlet. The inlet and the outlet extend radially outward from the oil ring and penetrate the oil seal seat.

[0014] Preferably, a first O-ring is provided between the oil seal seat and the end cover plate.

[0015] Preferably, the frame has an operating hole that communicates with the buffer cavity, and the operating hole is covered with a sealing cover.

[0016] Preferably, the frame is provided with a balance port to balance the pressure inside the buffer chamber with the pressure inside the vessel.

[0017] Preferably, a second O-ring is provided between the bearing housing and the support plate.

[0018] Preferably, a third O-ring is provided between the bearing housing and the bearing cap.

[0019] This utility model provides a multi-stage shaft sealing device for a horizontal mixing equipment. In the first-stage spiral sealing structure, the threaded groove on the mixing shaft fits against the inner wall of the end cover plate hole, which can utilize the viscosity of highly viscous materials and the driving force generated by the spiral rotation to prevent viscous materials from entering the second-stage oil seal assembly. The second-stage oil seal assembly, through the cooperation of components such as oil seal seat and oil seal cover, ensures the stable installation and sealing of the oil seal assembly. In the third-stage mechanical seal assembly, the setting of bearing seat, bearing cover and support plate ensures the sealing performance at the fulcrum of the mixing shaft. At the same time, the buffer cavity formed in the frame can eliminate the pressure difference between the two ends of the second-stage oil seal assembly, reduce material leakage and air leakage, provide space for maintenance of the second-stage oil seal assembly, and also provide a clean environment for the third-stage mechanical seal assembly. The whole device realizes multi-stage sealing for the horizontal mixing equipment, and the design of each sealing structure is convenient for maintenance.

[0020] The further solutions provided in this application can also achieve at least one of the following beneficial technical effects:

[0021] The liquid is periodically flushed into the cavity of the oil ring through the inlet and outlet to prevent a small amount of material that has passed through the primary spiral seal from entering the lip of the oil seal, thus protecting the oil seal and facilitating the maintenance of the equipment's sealing performance.

[0022] By using the balancing port to balance the pressure inside the buffer chamber with the pressure inside the vessel, the pressure difference between the two ends of the secondary oil seal assembly can be eliminated, reducing external material leakage and internal air leakage, and reducing the sealing difficulty of the primary spiral seal structure and the secondary oil seal assembly.

[0023] Operators can perform maintenance operations on the components inside the buffer chamber by opening the sealing cover on the operating port without removing the support point of the stirring shaft, which facilitates the inspection and maintenance of the equipment. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the multi-stage shaft sealing device in this embodiment;

[0026] Figure 2 This is a schematic diagram of the primary spiral seal structure and the secondary oil seal assembly in this embodiment.

[0027] Figures 1-2 In the accompanying drawings, the reference numerals include:

[0028] 1. Stirring shaft; 21. Threaded groove;

[0029] 31. Oil seal; 32. Oil seal seat; 33. Oil seal gland; 34. Stud; 35. Countersunk bolt; 36. Liquid inlet; 37. Liquid outlet; 38. Oil ring;

[0030] 41. Bearing housing; 42. Support plate; 43. Bearing gland; 44. Mechanical seal;

[0031] 5. End cover plate; 6. Frame; 61. Buffer chamber; 62. Operating hole; 63. Balance port; 64. Sealing cover plate; 7. Outside the vessel; 8. Inside the vessel. 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] Unless otherwise defined, the technical or scientific terms used in this application shall have the ordinary meaning understood by one of ordinary skill in the art to which this utility model pertains. The terms "first," "second," and similar words used in this utility model do not indicate any order, quantity, or importance. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship can also change accordingly. An embodiment of this application discloses a multi-stage shaft sealing device for a horizontal stirring apparatus.

[0034] The core of this utility model is to provide a multi-stage shaft sealing device for a horizontal mixing equipment.

[0035] Please refer to Figures 1 to 2 .

[0036] The multi-stage shaft sealing device for the horizontal mixing equipment provided by this utility model includes a first-stage spiral sealing structure, a second-stage oil seal assembly, and a third-stage mechanical seal assembly arranged sequentially. The first-stage spiral sealing structure includes a threaded groove 21 formed on the mixing shaft 1, which fits against the inner wall of the hole on the end cover plate 5. The second-stage oil seal assembly includes multiple sets of oil seals fitted on the side of the mixing shaft 1 located outside the vessel 7, and an oil seal seat 32 fitted on the outer periphery of the multiple sets of oil seals. One end of the oil seal seat 32 abuts against the end cover plate 5, and the other end of the oil seal seat 32 is provided with an oil seal pressure cap 33. A stud 34 is provided on the oil seal pressure cap 33 to allow... The oil seal cap 33 is fixed to the oil seal seat 32. The oil seal seat 32 is provided with countersunk bolts 35 to fix the oil seal seat 32 to the end cover plate 5. The three-stage mechanical seal assembly includes a bearing seat 41 located at the fulcrum of the stirring shaft 1, a bearing cap 43 located at the end of the bearing seat 41 for sealing the bearing seat 41, and a mechanical seal 44. The bearing seat 41 is fixedly connected to the frame 6 through a support plate 42. A buffer cavity 61 is formed in the frame 6 between the two-stage oil seal assembly and the three-stage mechanical seal assembly. The mechanical seal 44 is sleeved on the stirring shaft 1 and is fixed to the bearing cap 43.

[0037] Specifically, this multi-stage shaft sealing device is sequentially configured with a primary spiral seal structure, a secondary oil seal assembly, and a tertiary mechanical seal assembly. The threaded groove 21 of the primary spiral seal structure is formed on the stirring shaft 1 and fits against the inner wall of the hole in the end cover plate 5 (the gap between the diameter of the spiral groove 21 and the hole in the end cover plate 5 is very small). When the stirring shaft 1 rotates, the viscosity of the highly viscous material and the driving force generated by the spiral rotation cause the material to continuously return to the high-pressure end, i.e., the reactor. When the leakage flow of the spiral seal and the pumping flow generated by the spiral rotation reach a dynamic balance, it can prevent a large amount of viscous material from flowing into the secondary oil seal assembly, thus achieving initial sealing of the material.

[0038] Regarding the secondary oil seal assembly, multiple oil seal sets are fitted onto the side of the stirring shaft 1 located outside the vessel 7. An oil seal seat 32 is fitted around the outer periphery of the multiple oil seal sets, with one end abutting against the end cover plate 5 and the other end fitted with an oil seal pressure cap 33. The oil seal pressure cap 33 is fixed to the oil seal seat 32 by studs 34, and the oil seal seat 32 is fixed to the end cover plate 5 by countersunk bolts 35. This structure provides a stable installation and can further prevent a small amount of material from passing through the primary spiral seal.

[0039] In the three-stage mechanical seal assembly, the bearing housing 41 is located at the fulcrum of the stirring shaft 1, and the bearing cap 43 is located at the end of the bearing housing 41 to seal it. The bearing housing 41 is fixedly connected to the frame 6 via a support plate 42. The mechanical seal 44 is fitted onto the stirring shaft 1 and is fixed to the bearing cap 43. The bearing cap 43 serves both to seal the bearing housing 41 and to provide positioning and fixation for the mechanical seal 44. The bearing is positioned as close as possible to the third-stage seal, as this minimizes shaft sway at the mechanical seal 44 and facilitates sealing. A buffer cavity 61 is formed within the frame 6 between the second-stage oil seal assembly and the third-stage mechanical seal assembly. The buffer cavity 61 eliminates the pressure difference across the second-stage oil seal assembly, reduces external material leakage, prevents internal air leakage, provides space for maintenance of the second-stage oil seal assembly, and provides a clean environment for the third-stage mechanical seal assembly, ensuring the effectiveness of the high-vacuum seal. Furthermore, this structure facilitates the maintenance of the multi-stage shaft seal device, enables it to adapt to high vacuum and high viscosity conditions, and improves the efficiency and stability of the horizontal mixing equipment. The mechanical seal 44 is a conventional mechanical seal structure.

[0040] It should be noted that a numerical calculation model of the spiral seal can be established by combining CFD software to simulate the fluid domain of the spiral seal, analyze the different force distribution and velocity distribution of the two main parts of the spiral seal (spiral groove 21 and tooth tip gap) under the action of pressure difference, and optimize various parameters of the spiral seal.

[0041] The multi-stage shaft sealing device of the above-mentioned horizontal mixing equipment effectively solves the problems of difficult sealing of the mixing shaft and inconvenient maintenance of the sealing device under high vacuum and high viscosity conditions.

[0042] The multi-stage shaft sealing device of the horizontal mixing equipment provided by this utility model will be described in more detail below with reference to the accompanying drawings and specific embodiments.

[0043] In one specific implementation, reference is made to... Figure 2 The axial length of the threaded groove 21 on the stirring shaft 1 is set according to the wall thickness of the end cover plate 5. The axial length of the threaded groove 21 on the stirring shaft 1 extends through the entire wall thickness of the end cover plate 5 and ends in the inner 8 of the vessel.

[0044] Specifically, in the multi-stage shaft sealing device of the horizontal mixing equipment, the threaded groove 21 of the first-stage spiral seal structure is formed on the mixing shaft 1. Its axial length on the mixing shaft 1 is set according to the wall thickness of the end cover plate 5, and this length runs through the entire wall thickness of the end cover plate 5 and ends in the vessel interior 7. During operation, the leaked material will fill the sealed space contained in the threaded groove 21 and the end cover plate 5. The direction of the thread on the mixing shaft 1 causes the material to move axially when the shaft rotates, prompting the material to continuously return to the high-pressure end, i.e., the vessel interior. When the leakage flow rate of the spiral seal and the pumping flow rate generated by the spiral rotation reach a dynamic balance, the sealing purpose can be achieved. This structure can effectively utilize the viscosity of highly viscous materials and the driving force generated after the spiral rotation, reduce the amount of material leakage, prevent viscous materials from entering the subsequent secondary seal, and improve the sealing performance and stability of the entire multi-stage shaft sealing device.

[0045] Based on any of the above embodiments, refer to Figure 2 There are two sets of oil seals. Each set of oil seals has two oil seals 31 arranged back to back. All oil seals 31 are split skeleton oil seals. The two sets of oil seals are separated by an oil ring 38.

[0046] Specifically, two sets of oil seals are provided, fitted onto the side of the stirring shaft 1 located outside the vessel 7. Each set of oil seals has two split-type skeleton oil seals 31 arranged back-to-back, separated by an oil ring 38. An oil seal seat 32 is fitted around the outer periphery of the multiple sets of oil seals, with one end abutting against the end cover plate 5. During operation, the two sets of back-to-back oil seals 31 enhance the sealing effect. The split-type oil seal 31 structure allows for replacement without removing the support points of the stirring shaft 1, saving significant manpower and resources and improving maintenance convenience.

[0047] Furthermore, an elastic element is provided inside the oil seal 31 so that the lip of the oil seal 31 abuts against the outer wall of the stirring shaft 1.

[0048] Specifically, in the secondary oil seal assembly of the multi-stage shaft sealing device, an elastic element is installed inside the oil seal 31. The oil seal 31 is fitted onto the side of the stirring shaft 1 located outside the vessel 7, and the elastic element ensures that the lip of the oil seal is tightly pressed against the outer wall of the stirring shaft 1. During operation, the elastic element applies continuous pressure to the lip of the oil seal 31, maintaining a good fit with the outer wall of the stirring shaft 1. This effectively prevents material from entering the interior of the oil seal 31, improving the sealing performance of the secondary oil seal assembly, reducing the risk of material leakage, and thus enhancing the reliability and stability of the entire multi-stage shaft sealing device.

[0049] Based on any of the above embodiments, refer to Figure 2The outer periphery of the oil ring 38 is provided with an inlet 36 and an outlet 37. The inner periphery of the oil ring 38 is a cavity, and both are connected to the inlet 36 and the outlet 37. The inlet 36 and the outlet 37 extend radially outward from the oil ring 38 and penetrate the oil seal seat 32.

[0050] Specifically, the oil ring 38 has an inlet 36 and an outlet 37 on its outer circumference. The inner circumference of the oil ring 38 is a cavity, which is connected to the inlet 36 and the outlet 37. Both the inlet 36 and the outlet 37 extend radially outward from the oil ring 38 and penetrate the oil seal seat 32. During operation, flushing fluid can be injected into the cavity of the oil ring 38 through the inlet 36, and the flushing fluid flows out through the outlet 37. In this way, a small amount of material passing through the primary spiral seal can be prevented from entering the lip of the oil seal 31, thus protecting the oil seal 31, extending its service life, and improving the sealing performance and stability of the entire multi-stage shaft seal device.

[0051] It should be noted that a first O-ring is provided between the oil seal seat 32 and the end cover plate 5.

[0052] Specifically, the oil seal seat 32 is fitted onto the side of the stirring shaft 1 located outside the vessel 7, with one end abutting against the end cover plate 5. A first O-ring seal is provided between the oil seal seat 32 and the end cover plate 5. This sealing ring fills the gap between the oil seal seat 32 and the end cover plate 5, thus sealing the connection and preventing material leakage. This enhances the sealing performance of the entire shaft sealing device and improves the stability and reliability of the equipment operation.

[0053] Based on any of the above embodiments, refer to Figure 1 An operation hole 62 is provided on the frame 6, which is connected to the buffer cavity 61. A sealing cover plate 64 is provided on the operation hole 62.

[0054] Specifically, in the multi-stage shaft sealing device, the frame 6 has an operating hole 62, which communicates with the buffer cavity 61 located between the secondary oil seal assembly and the tertiary mechanical seal assembly. A sealing cover 64 is provided over the operating hole 62. During operation, when maintenance of the secondary oil seal assembly is required, the sealing cover 64 is opened, allowing personnel to inspect and repair the secondary oil seal assembly within the buffer cavity 61 through the operating hole 62, avoiding cumbersome steps such as dismantling the support point of the stirring shaft 1. This structural design makes the maintenance process more convenient, saves significant manpower and resources, and improves the maintainability of the equipment.

[0055] It should be noted that the cross-section of the vacuum buffer chamber 61 can be oblong or rectangular, and a sealing ring is provided on the sealing cover 64 to improve the sealing performance between the sealing cover 64 and the buffer chamber 61.

[0056] Based on any of the above embodiments, refer to Figure 1 The frame 6 is provided with a balance port 63 to balance the pressure in the buffer chamber 61 with the pressure in the vessel 8.

[0057] Specifically, the frame 6 has a balance port 63, and the buffer chamber 61 is located between the secondary oil seal assembly and the tertiary mechanical seal assembly, and is surrounded by the outer shell of the frame 6, the bearing support plate 42 inside the frame 6, and the end cover plate 5 of the cylinder. During operation, the balance port 63 can be used to create a vacuum, so that the pressure inside the buffer chamber 61 is balanced with the pressure inside the vessel 8. This eliminates the pressure difference between the two ends of the second-stage seal, effectively reducing external material leakage and preventing internal air leakage; it also provides a suitable space for maintaining the second-stage seal; and it creates a clean environment for the tertiary mechanical seal, easily solving the high-vacuum sealing problem.

[0058] It should be noted that a second O-ring is provided between the bearing housing 41 and the support plate 42. A third O-ring is provided between the bearing housing 41 and the bearing cap 43.

[0059] Specifically, the second O-ring is positioned between the bearing housing 41 and the support plate 42, at the connection point of the relevant components of the three-stage mechanical seal assembly of the multi-stage shaft sealing device. During operation, the second O-ring fills the gap between the bearing housing 41 and the support plate 42, preventing material leakage and the entry of outside air, thus ensuring the sealing performance and stability of the multi-stage shaft sealing device and improving the operational reliability of the entire horizontal mixing equipment under high vacuum and high viscosity conditions.

[0060] The third O-ring seal is located at the contact point between the bearing housing 41 and the bearing cap 43, filling the gap between them. During operation, when external pressure or internal equipment pressure changes, the third O-ring seal, due to its own elasticity, can tightly fit the contact surfaces of the bearing housing 41 and the bearing cap 43, preventing media leakage. This effectively enhances the sealing performance between the bearing housing 41 and the bearing cap 43, preventing media leakage from the gap between them, thereby ensuring the overall sealing performance of the multi-stage shaft sealing device and improving the stability and reliability of equipment operation.

[0061] The implementation principle of a multi-stage shaft sealing device for a horizontal mixing equipment according to an embodiment of this application is as follows: A multi-stage sealing system is formed by setting a primary spiral sealing structure, a secondary oil seal assembly, and a tertiary mechanical seal assembly. Utilizing the characteristics of different sealing structures, it effectively addresses the sealing challenges under high vacuum and high viscosity conditions. The primary spiral sealing structure uses the pumping action of the threaded groove 21 to prevent material from entering the secondary oil seal assembly. The secondary oil seal assembly uses a split-type skeleton oil seal 31 and an oil ring 38 for flushing, further blocking material and protecting the oil seal. The tertiary mechanical seal assembly balances pressure through a buffer chamber 61, creating a favorable sealing environment. Furthermore, the structural design of each component facilitates maintenance, avoiding cumbersome operations such as dismantling the mixing shaft 1 support point, improving maintenance efficiency, and reducing maintenance costs. Compared to existing technologies, this represents a significant improvement and enhancement.

[0062] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0063] The multi-stage shaft sealing device for a horizontal mixing apparatus provided by this utility model has been described in detail above. Specific examples have been used to illustrate the principle and implementation of this utility model. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core idea of ​​this utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made to this utility model without departing from the principle of this utility model, and these improvements and modifications also fall within the protection scope of this utility model.

Claims

1. A multi-stage shaft sealing device for a horizontal mixing equipment, characterized in that, It includes a first-stage spiral sealing structure, a second-stage oil seal assembly and a third-stage mechanical seal assembly arranged in sequence. The first-stage spiral sealing structure includes a threaded groove (21) opened on the stirring shaft (1). The threaded groove (21) fits against the inner wall of the hole on the end cover plate (5). The secondary oil seal assembly includes multiple oil seal groups sleeved on the side of the stirring shaft (1) located outside the vessel (7) and an oil seal seat (32) sleeved on the outer periphery of the multiple oil seal groups. One end of the oil seal seat (32) abuts against the end cover plate (5), and the other end of the oil seal seat (32) is provided with an oil seal cap (33). The oil seal cap (33) is provided with a stud (34) to fix the oil seal cap (33) to the oil seal seat (32), and the oil seal seat (32) is provided with a countersunk bolt (35) to fix the oil seal seat (32) to the end cover plate (5). The three-stage mechanical seal assembly includes a bearing housing (41) located at the fulcrum of the stirring shaft (1), a bearing cap (43) located at the end of the bearing housing (41) for sealing the bearing housing (41), and a mechanical seal (44). The bearing housing (41) is fixedly connected to the frame (6) by a support plate (42). A buffer cavity (61) is formed in the frame (6) between the two-stage oil seal assembly and the three-stage mechanical seal assembly. The mechanical seal (44) is sleeved on the stirring shaft (1) and is fixed to the bearing cap (43).

2. The multi-stage shaft sealing device for a horizontal mixing equipment according to claim 1, characterized in that, The axial length of the threaded groove (21) on the stirring shaft (1) is set according to the wall thickness of the end cover plate (5). The axial length of the threaded groove (21) on the stirring shaft (1) extends through the entire wall thickness of the end cover plate (5) and ends in the vessel (8).

3. The multi-stage shaft sealing device for a horizontal mixing equipment according to claim 2, characterized in that, The oil seal group consists of two groups, each group having two oil seals (31) arranged back-to-back. The oil seals (31) are all split skeleton oil seals, and the two groups of oil seals are separated by an oil ring (38).

4. The multi-stage shaft sealing device for a horizontal mixing equipment according to claim 3, characterized in that, The oil seal (31) is provided with an elastic element so that the lip of the oil seal (31) abuts against the outer wall of the stirring shaft (1).

5. The multi-stage shaft sealing device for a horizontal mixing equipment according to claim 3, characterized in that, The outer periphery of the oil ring (38) is provided with an inlet (36) and an outlet (37) respectively. The inner periphery of the oil ring (38) is a cavity and is connected to the inlet (36) and the outlet (37). The inlet (36) and the outlet (37) extend radially outward from the oil ring (38) and penetrate the oil seal seat (32).

6. The multi-stage shaft sealing device for a horizontal mixing equipment according to claim 1, characterized in that, A first O-ring is provided between the oil seal seat (32) and the end cover plate (5).

7. A multi-stage shaft sealing device for a horizontal mixing apparatus according to any one of claims 1-6, characterized in that, An operation hole (62) is provided on the frame (6), the operation hole (62) is connected to the buffer cavity (61), and a sealing cover plate (64) is provided on the operation hole (62).

8. A multi-stage shaft sealing device for a horizontal mixing equipment according to claim 7, characterized in that, The frame (6) is provided with a balance port (63) to balance the pressure inside the buffer cavity (61) with the pressure inside the vessel (8).

9. A multi-stage shaft sealing device for a horizontal mixing equipment according to claim 7, characterized in that, A second O-ring is provided between the bearing housing (41) and the support plate (42).

10. A multi-stage shaft sealing device for a horizontal mixing equipment according to claim 7, characterized in that, A third O-ring is provided between the bearing housing (41) and the bearing cap (43).

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