Roots vacuum pump capable of preventing material mixing and oil leakage

Abstract

The utility model relates to the technical field of Roots vacuum pumps, and discloses a Roots vacuum pump capable of preventing material mixing and oil leakage, which comprises a pump shell, a pump shaft connected in the pump shell and a waist-shaped rotor connected on the pump shaft. Through the labyrinth sealing piece, the nitrogen-filled sealing cavity and the mechanical sealing piece, thorough transformation of a shaft sealing mode between the medium cavity and the lubricating oil cavity is achieved, and the possibility that media in a pump cavity and lubricating oil in an oil cavity are blocked from being mixed due to pressure difference is achieved; due to the injection of nitrogen, the possibility that a medium enters a gap of the shaft seal through the labyrinth sealing element is ensured, and the shaft seal can be prevented from being damaged by crystals; meanwhile, a trace amount of nitrogen does not influence the whole air exhaust performance of the roots vacuum pump; due to the existence of the mechanical sealing piece, a pump cavity and an oil cavity are thoroughly isolated, air flow between the two cavities does not circulate any more, the shaft seal mode is put into use, the field actual effect is good, the problem that lubrication often loses efficacy is fundamentally solved, and dual stability of equipment operation and product quality is achieved.

Description

Technical Field

[0001] The utility model relates to the technical field of Roots vacuum pumps, in particular to a Roots vacuum pump capable of preventing material cross-contamination and oil leakage. Background Art

[0002] To maintain stable distillation product quality, the vacuum level in a vacuum distillation tower must be constant with a certain margin, and the vacuum unit is undoubtedly a crucial component in achieving this requirement. The DPC unit's vacuum unit consists of three pump stages: a foreline liquid ring vacuum pump, a secondary Roots vacuum pump, and a primary Roots vacuum pump. Each pump stage must operate optimally to ensure stable pumping performance and, by extension, vacuum stability throughout the vacuum distillation system. Otherwise, system vacuum stability and, consequently, product quality stability cannot be guaranteed.

[0003] The shaft seal between the pump chamber and the oil chamber of a two-stage Roots vacuum pump is a labyrinth seal. This seal consists of several annular sealing teeth arranged in sequence around the rotating shaft. These teeth form a series of intercepting gaps and expansion cavities. As the sealed medium passes through the gaps in the labyrinth, a throttling effect occurs, preventing leakage. Due to the 0.2-0.6mm gap between the rotor and the housing of the labyrinth seal, cross-contamination of the media in the two chambers is inevitable during operation. During vacuuming, the pressure differential between the two sides causes cross-contamination and oil leakage. In severe cases, either phenomenon can lead to lubrication failure of the bearings and gears within the Roots pump. A Roots vacuum pump failure can directly cause instability in the entire vacuum system. Furthermore, the cross-contamination medium is DPC (diphenyl carbonate), which has a melting point of 79-82°C and is a solid crystalline solid at ambient temperature. Severe cross-contamination can cause the pump to suddenly lock during operation. In short, material cross-contamination and oil leakage are caused by improper shaft seal structure, which brings great instability to production and adds a huge burden to maintenance.

[0004] For example, patent publication number CN203867893U discloses a Roots vacuum pump comprising a pump body, a motor, a front cover, and a rear cover. The front cover and rear cover are provided at both ends of the pump body, respectively. An overpressure protection valve is installed above the pump body, an air inlet is provided near the overpressure protection valve, and an exhaust port is provided at the bottom of the pump body. A pair of parallel driving and driven rotor shafts are provided within the pump body. An oil-gas separation device is provided within the pump body below the overpressure protection valve. Two pairs of mutually meshing rotors are vertically provided on the driving and driven rotor shafts. A first synchronous gear is provided at the end of the driving and driven rotor shafts, and a second synchronous gear is provided at the head end. The first synchronous gear is provided within the rear cover, and an oil filling hole is provided on the rear cover. The beneficial effects of this device are: a reasonable structural design, a small size, a high pumping speed, energy and space saving, low impact on the entire machine, a long service life, overload protection for the entire machine, automatic fault protection, no destructive damage, the ability to test the vacuum degree within the pump body, and high safety performance. The above device solves the problem of longer service life, but there are still problems such as material leakage and oil leakage when the pump shaft moves. Utility Model Content

[0005] In view of the deficiencies in the prior art, the utility model provides a Roots vacuum pump capable of preventing material cross-contamination and oil leakage, so that the Roots vacuum pump can be prevented from material cross-contamination and oil leakage during operation.

[0006] To achieve the above-mentioned objectives, the utility model provides the following technical solutions: a Roots vacuum pump that prevents material cross-contamination and oil leakage, comprising a pump housing, a pump shaft connected to the pump housing, and a waist-shaped rotor connected to the pump shaft, a labyrinth seal being connected to the outside of the connection between the pump shaft and the pump housing, a mechanical seal being connected to the side of the labyrinth seal away from the waist-shaped rotor, a gap being left between the mechanical seal and the labyrinth seal, and a nitrogen-filled sealed cavity being formed through the pump housing, and a nitrogen connector being connected to the outside of the pump housing.

[0007] Furthermore, the nitrogen connector includes a pipe joint, one section of which passes through the pump housing and is connected to the nitrogen filling sealed chamber, and the pipe joint is sealed to the outer wall of the pump housing. One side of the pipe joint is connected to a tap, and the tap is connected to the nitrogen filling equipment through a pipeline.

[0008] Furthermore, a pressure gauge is connected to one side of the top of the connecting pipe joint.

[0009] Furthermore, the nitrogen pressure value is set to 10 kPa.

[0010] Compared with the prior art, the present invention has the following beneficial effects:

[0011] The utility model realizes a thorough transformation of the shaft seal between the medium cavity and the lubricating oil cavity through the labyrinth seal, the nitrogen-filled sealing chamber and the mechanical seal, thereby blocking the possibility of the medium in the pump cavity and the lubricating oil in the oil cavity from mixing with each other due to the pressure difference; and the injection of nitrogen ensures the possibility of the medium entering the shaft seal gap through the labyrinth seal, which can avoid the occurrence of crystal damage to the shaft seal; at the same time, a trace amount of nitrogen does not affect the overall air extraction performance of the Roots vacuum pump; the presence of the mechanical seal completely isolates the pump cavity and the oil cavity, so that the air flow between the two cavities no longer circulates, and the oil cavity is at normal pressure or slightly positive pressure; the use of this shaft seal form has achieved good actual results on site, fundamentally solved the problem of frequent lubrication failure, and achieved dual stability of equipment operation and product quality, and the structure is simple, easy to operate and highly practical. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a schematic diagram of an overall three-dimensional structure of the utility model;

[0013] Figure 2 It is a three-dimensional structural diagram of the pump shaft, mechanical seal, labyrinth seal and sigh seal chamber of the utility model;

[0014] Figure 3 It is a front view structural schematic diagram of a partial state of the utility model.

[0015] In the figure: 1. Pump housing; 11. Pump shaft; 12. Waist-shaped rotor; 2. Pipe joint; 3. Tap joint; 4. Pressure gauge; 5. Mechanical seal; 6. Labyrinth seal; 7. Nitrogen-filled seal chamber. DETAILED DESCRIPTION

[0016] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0017] like Figures 1 to 3 As shown, a Roots vacuum pump for preventing material cross-contamination and oil leakage includes a pump housing 1, a pump shaft 11 connected to the pump housing 1, and a waist-shaped rotor 12 connected to the pump shaft 11. A labyrinth seal 6 is connected to the outside of the connection between the pump shaft 11 and the pump housing 1. A mechanical seal 5 is connected to the side of the labyrinth seal 6 away from the waist-shaped rotor 12. A gap is left between the mechanical seal 5 and the labyrinth seal 6, and a nitrogen-filled sealing chamber 7 is formed by the pump housing 1. A nitrogen connector is connected to the outside of the pump housing 1.

[0018] like Figure 1As shown, the structure of the Roots vacuum pump for preventing material leakage and oil leakage in the present invention is similar to that of the existing Roots vacuum pump, such as the Roots vacuum pump disclosed in the patent with publication number CN203867893U. The main improvement of the present invention is to prevent material leakage and oil leakage from occurring during the operation of the Roots vacuum pump. Figures 1 to 3 As shown, when the Roots vacuum pump for preventing material leakage and oil leakage in the utility model is in use, nitrogen can be added to the nitrogen-filled sealing chamber 7 through the nitrogen connector. After being filled in, the nitrogen will enter the pump chamber of the pump housing 1. The purpose of this is to prevent the medium from entering the lubricating oil chamber side through the labyrinth seal 6. By arranging a mechanical seal 5 on the side close to the lubricating oil chamber, because it is a leak-free seal, its lubrication and cooling are guaranteed by the lubricating oil in the oil chamber, thereby achieving the possibility of blocking the pump chamber medium and the oil chamber lubricating oil from leaking due to the pressure difference.

[0019] Through the labyrinth seal 6, the nitrogen-filled sealing chamber 7 and the mechanical seal 5, a thorough transformation of the shaft seal between the medium chamber and the lubricating oil chamber is achieved, thereby blocking the possibility of the medium in the pump chamber and the lubricating oil in the oil chamber from mixing with each other due to the pressure difference; and the injection of nitrogen ensures the possibility of the medium entering the shaft seal gap through the labyrinth seal 6, which can avoid the occurrence of crystal damage to the shaft seal; at the same time, a trace amount of nitrogen does not affect the overall pumping performance of the Roots vacuum pump; the presence of the mechanical seal 5 completely isolates the pump chamber and the oil chamber, so that the air flow between the two chambers no longer circulates, and the oil chamber is at normal pressure or slightly positive pressure; the use of this type of shaft seal has achieved good actual results on site, fundamentally solving the problem of frequent lubrication failure and achieving dual stability of equipment operation and product quality.

[0020] like Figure 2 and Figure 3 As shown, the nitrogen connector includes a pipe joint 2, a section of which passes through the pump housing 1 and is connected to the nitrogen filling sealed chamber 7, and the pipe joint 2 is sealedly connected to the outer wall of the pump housing 1. One side of the pipe joint 2 is connected to a tap 3, and the tap 3 is connected to the nitrogen filling equipment through a pipeline.

[0021] like Figure 2 and Figure 3 As shown, a pressure gauge 4 is also connected to one side of the top of the connecting joint 2.

[0022] like Figure 2 and Figure 3 As shown, the nitrogen pressure value is set to 10 kPa.

[0023] Specifically, through the setting of the connecting joint 2 and the tap joint 3, the external nitrogen filling equipment can be started, and the nitrogen is fed into the tap joint 3 through the pipeline, and then enters the connecting joint 2. It is always judged by the pressure gauge 4, and a small amount of nitrogen is always kept entering the nitrogen-filled sealed chamber 7. The setting of the pressure gauge 4 is maintained at 10kPa. People can also judge the amount of nitrogen in the nitrogen-filled sealed chamber 7 based on the display of the pressure gauge 4.

[0024] Although the embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A Roots vacuum pump for preventing material cross-contamination and oil leakage, comprising a pump housing (1), a pump shaft (11) connected to the pump housing (1), and a kidney-shaped rotor (12) connected to the pump shaft (11), characterized in that: A labyrinth seal (6) is connected to the outside of the connection between the pump shaft (11) and the pump housing (1); a side of the labyrinth seal (6) away from the waist-shaped rotor (12) is connected to a mechanical seal (5); a gap is left between the mechanical seal (5) and the labyrinth seal (6); and a nitrogen-filled sealing cavity (7) is formed through the pump housing (1); and a nitrogen connector is connected to the outside of the pump housing (1).

2. A Roots vacuum pump for preventing material leakage according to claim 1, characterized in that: The nitrogen connecting piece comprises a pipe joint (2), a section of the pipe joint (2) passes through the pump housing (1) and is connected to the nitrogen-filled sealed cavity (7), and the pipe joint (2) is sealedly connected to the outer wall of the pump housing (1); one side of the pipe joint (2) is connected to a tap joint (3), and the tap joint (3) is externally connected to a nitrogen filling device through a pipeline.

3. A Roots vacuum pump for preventing material leakage according to claim 2, characterized in that: A pressure gauge (4) is also connected to one side of the top of the pipe joint (2).

4. A Roots vacuum pump for preventing material leakage and oil leakage according to claim 1, 2 or 3, characterized in that: The nitrogen pressure value was set to 10 kPa.

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