Rotary sealing structure of gas desorption dynamic measuring device for friction test

Abstract

The invention discloses a rotary sealing structure of a gas desorption dynamic measuring device for a friction test, which belongs to the technical field of coal mine safety engineering and gas prevention and control, has the innovative core of adopting a dual sealing principle of solid sealing liquid and liquid sealing gas, and mainly comprises a central rotating shaft, a fixed cylindrical shell and a solid-liquid sealing assembly. A gas overflow channel communicated with the coring pipe is arranged in the center rotating shaft, liquid sealing media are injected into a left annular cavity and a right annular cavity formed among the fixed shell, the center rotating shaft, the inner sealing ring and the outer sealing ring to seal gas, liquid sealing gas is achieved through a liquid barrier, and gas leakage is prevented. Sealing assemblies are arranged at the two ends of the insulating oil to achieve solid sealing of the liquid, and oil leakage is prevented. The device is scientific in principle and simple and reliable in structure, continuous and pollution-free sealing and exporting of the gas in the rotating state are achieved, and key technical support is provided for studying the gas desorption rule under the dynamic friction condition.

Description

Technical Field

[0001] This invention belongs to the field of coal mine safety engineering and gas control technology, specifically relating to a rotary sealing structure for a dynamic gas desorption measuring device used in friction testing. Background Technology

[0002] The desorption mechanism of coal seam gas is a key parameter for predicting gas emission, evaluating extraction effectiveness, and preventing gas disasters. Currently, laboratory measurements of gas desorption often employ the static isothermal desorption method, which involves placing the coal sample in a sealed container and measuring the gas desorption amount at a constant temperature. However, in actual underground drilling (such as construction boreholes and hydraulic drilling) or mining processes, tools like drill rods and cutting teeth experience high-speed rotational friction with the coal seam, generating significant frictional heat. This significantly alters the coal seam temperature field, thus strongly affecting the gas desorption kinetics. Static measurement methods cannot reflect this dynamic coupling effect, leading to discrepancies between predicted results and actual operating conditions.

[0003] To simulate this physical process, a test device is urgently needed that can simultaneously and online measure the amount of gas desorption from coal samples under rotating friction. The core technical challenge of this device lies in how to establish a gas channel seal between the rotating component (simulating a drill rod) and the fixed gas acquisition and measurement pipeline without interfering with the gas composition. Conventional mechanical seals or packing seals are prone to wear and heat generation under long-term rotating friction, which may lead to leakage or changes in gas properties; while high-end sealing methods such as magnetohydrodynamic seals are expensive and have strict requirements for the working environment.

[0004] Therefore, developing a simple, reliable, cost-effective rotary sealing structure suitable for laboratory simulation environments is of great significance for promoting the development of dynamic gas desorption measurement technology. Summary of the Invention

[0005] To solve the above-mentioned technical problems, the present invention provides a rotary sealing structure for a dynamic gas desorption measuring device for friction testing. This structure can achieve dynamic sealing of gas between the rotating component and the fixed component, ensuring that during the simulated process of drill pipe rotation friction heat generation, the gas desorption gas can be completely and continuously exported to the static measurement system, and the sealing medium will not contaminate the gas path.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a rotary sealing structure for a dynamic gas desorption measuring device for friction testing, comprising a central rotating shaft and a fixed cylindrical shell arranged along the left-right direction, the fixed cylindrical shell being coaxially sleeved on the central rotating shaft and rotatably connected to the central rotating shaft, the left and right ends of the central rotating shaft being connected to a driving device and a core tube containing a coal sample, respectively, the central rotating shaft having a gas overflow channel communicating with the core tube, the fixed cylindrical shell having an exhaust hole communicating with the gas overflow channel, the outer port of the exhaust hole being connected to an external gas measuring instrument, and a set of solid-liquid sealing components being provided on the left and right sides of the connection between the gas overflow channel and the inner port of the exhaust hole during the rotation of the central rotating shaft.

[0007] The gas overflow channel includes a central hole at the right end that connects to the gas outlet of the core tube. Two radial vents are connected to the left end of the central hole. The two radial vents and the exhaust port are located on the same vertical plane.

[0008] The inner circles of the left and right ports of the fixed cylindrical shell are rotatably connected to the outer circle of the central rotating shaft through a bearing. The solid-liquid sealing assembly includes two outer sealing rings and two inner sealing rings, each disposed between the inner circle of the fixed cylindrical shell and the outer circle of the central rotating shaft. One outer sealing ring is adjacent to the left bearing and located on the right side of the bearing, and the other outer sealing ring is adjacent to the right bearing and located on the left side of the bearing. The two inner sealing rings are located on the left and right sides of the inner port of the vent hole, respectively. A left annular cavity is formed between the inner circle of the fixed cylindrical shell and the outer circle of the central rotating shaft between the left outer sealing ring and the left inner sealing ring. A left annular cavity is formed between the inner circle of the fixed cylindrical shell and the outer circle of the central rotating shaft between the right outer sealing ring and the left inner sealing ring. A right annular cavity is formed between the inner sealing rings on the right side; a gas-liquid outlet is opened on the upper side of the fixed cylindrical shell, which communicates with the left and right annular cavities respectively; a liquid injection hole is opened on the lower side of the fixed cylindrical shell, which communicates with the left and right annular cavities respectively; an upper valve and a lower valve are respectively provided at the upper end of the gas-liquid outlet and the lower end of the liquid injection hole; a liquid sealing medium is injected into the left and right annular cavities through the liquid injection hole to form a liquid ring sealing barrier to achieve "liquid sealing gas", and the liquid sealing medium is located between the outer sealing ring and the inner sealing ring to achieve "solid sealing liquid".

[0009] The left end of the core tube is coaxially connected to the right end of the central rotating shaft via a flange and bolt assembly. A gas filter screen for filtering coal powder is installed in the gas guide chamber or gas overflow channel inside the core tube. The gas filter screen is made of breathable coal seam filter cloth.

[0010] The fixed housing is equipped with a pressure gauge or pressure sensor for monitoring the pressure of the liquid sealing medium in the left and right annular cavities.

[0011] The liquid sealing medium is mineral insulating oil or synthetic insulating oil.

[0012] Both the outer and inner sealing rings are rotary shaft lip seals made of nitrile rubber, fluororubber, or polytetrafluoroethylene.

[0013] The core tube is made of thermally conductive material, and a friction sleeve is installed on the outer wall of the core tube.

[0014] By adopting the above technical solution, compared with the prior art, the present invention has the following technical effects: This invention provides a rotary sealing structure for a dynamic gas desorption measurement device used in friction tests. Utilizing a dual sealing principle of "solid sealing liquid, liquid sealing gas," this structure aims to solve the technical challenge of dynamically sealing the desorbed gas from the rotating component to the fixed measuring pipeline during simulated drill pipe rotation friction heat generation. This invention achieves efficient sealing and pollution-free continuous gas extraction between the central rotating shaft and the fixed cylindrical shell while the shaft is rotating, overcoming the technical bottleneck in gas desorption measurement under dynamic friction conditions. This invention is scientifically sound, structurally simple and reliable, and cost-effective. It can be widely applied in laboratory simulation research in the field of coal mine safety engineering, providing key technical support for accurately assessing the impact of frictional heat on gas desorption laws and possessing significant theoretical and practical value for optimizing gas disaster prevention and control measures. Attached Figure Description

[0015] Figure 1 This is a schematic cross-sectional view of the overall structure of the device of the present invention; Figure 2 for Figure 1 Schematic diagram of the cross section along line AA; Figure 3 for Figure 1 A schematic diagram of the cross section along line BB. Detailed Implementation

[0016] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples.

[0017] like Figures 1-3 As shown, the rotary sealing structure of the gas desorption dynamic measuring device for friction testing of the present invention includes a central rotating shaft 1 and a fixed cylindrical shell 2 arranged along the left-right direction. The fixed cylindrical shell 2 is coaxially sleeved on the central rotating shaft 1 and rotatably connected to the central rotating shaft 1. The left and right ends of the central rotating shaft 1 are respectively connected to a driving device and a core tube 4 containing a coal sample 3. The central rotating shaft 1 is provided with a gas overflow channel that communicates with the inside of the core tube 4. The fixed cylindrical shell 2 is provided with an exhaust hole 5 that communicates with the gas overflow channel. The outer port of the exhaust hole 5 is connected to an external gas measuring instrument. During the rotation of the gas overflow channel with the central rotating shaft 1, a set of solid-liquid sealing components is provided on the left and right sides of the connection part with the inner port of the exhaust hole 5.

[0018] The gas overflow channel includes a central hole 6 at the right end that connects to the gas outlet of the core tube 4. Two radial vents 7 are connected to the left end of the central hole 6. The two radial vents 7 and the exhaust hole 5 are located on the same vertical plane.

[0019] The inner circles of the left and right ports of the fixed cylindrical shell 2 are rotatably connected to the outer circle of the central rotating shaft 1 via a bearing 8. The solid-liquid sealing assembly includes two outer sealing rings 9 and two inner sealing rings 10, both disposed between the inner circle of the fixed cylindrical shell 2 and the outer circle of the central rotating shaft 1. One outer sealing ring 9 is adjacent to the left bearing 8 and located to the right of the bearing 8, and the other outer sealing ring 9 is adjacent to the right bearing 8 and located to the left of the bearing 8. The two inner sealing rings 10 are located to the left and right of the inner port of the vent hole 5, respectively. A left annular cavity 11 is formed between the inner circle of the fixed cylindrical shell 2 and the outer circle of the central rotating shaft 1, between the left outer sealing ring 9 and the left inner sealing ring 10. A left annular cavity 11 is formed between the inner circle of the fixed cylindrical shell 2 and the outer circle of the central rotating shaft 1, between the right outer sealing ring 9 and the right inner sealing ring 10. A right annular cavity 12 is formed between the rings 10; a gas-liquid outlet 13 is provided on the upper side of the fixed cylindrical shell 2, which communicates with the left annular cavity 11 and the right annular cavity 12 respectively; an injection hole 17 is provided on the lower side of the fixed cylindrical shell 2, which communicates with the left annular cavity 11 and the right annular cavity 12 respectively; an upper valve and a lower valve are respectively provided at the upper end of the gas-liquid outlet 13 and the lower end of the injection hole 17; a liquid sealing medium 14 is injected into the left annular cavity 11 and the right annular cavity 12 through the injection hole 17 to form a liquid ring sealing barrier to achieve "liquid sealing gas", and the liquid sealing medium 14 is located between the outer sealing ring 9 and the inner sealing ring 10 to achieve "solid sealing liquid".

[0020] The left end of the core tube 4 is coaxially connected to the right end of the central rotating shaft 1 via a flange and bolt assembly 15. A gas path filter screen 16 for filtering coal powder is provided in the gas guide chamber or gas overflow channel inside the core tube 4. The gas path filter screen 16 is made of breathable coal seam filter cloth.

[0021] The fixed housing is equipped with a pressure gauge or pressure sensor for monitoring the pressure of the liquid sealing medium 14 in the left annular cavity 11 and the right annular cavity 12.

[0022] The liquid sealing medium 14 is made of mineral insulating oil or synthetic insulating oil.

[0023] Both the outer sealing ring 9 and the inner sealing ring 10 are rotary shaft lip seals made of nitrile rubber, fluororubber or polytetrafluoroethylene.

[0024] The core tube 4 is made of thermally conductive material, and a friction sleeve is provided on the outer wall of the core tube 4.

[0025] The working principle and steps of this invention are as follows: 1) Open the lower valves connected to the lower ends of the left and right injection holes 17 respectively, and inject liquid sealing medium 14 (using 25# mineral insulating oil) into the left annular cavity 11 and the right annular cavity 12 through the two injection holes 17 respectively. At the same time, open the two upper valves and exhaust the gas through the two gas-liquid outlet holes 13 until oil comes out, and then close all valves. Monitor the pressure of the liquid sealing medium 14 through a pressure gauge or pressure sensor.

[0026] 2) Load coal sample 3 into core tube 4 and seal the right end of core tube 4; set the speed of drive device (motor) and monitor the temperature rise of friction sleeve surface through infrared thermometer.

[0027] 3) As the central shaft 1 continues to rotate, the outer circle of the core tube 4 rubs against the friction sleeve, causing the core tube 4 to heat the coal sample 3 inside. This accelerates the desorption of gas from the coal sample 3. The gas then enters the central hole 6 inside the central shaft 1 through the gas filter screen 16 from the core tube 4, and further enters the external gas measuring instrument through two radial gas holes 7 and the exhaust hole 5. Because the 25# mineral insulating oil is incompressible and has good barrier properties, the gas cannot penetrate the liquid layer through the inner sealing ring 10. The inner circle of the inner sealing ring 10 is tightly fitted to the central shaft 1, preventing the 25# mineral insulating oil from leaking from the left annular cavity 11 and the right annular cavity 12. Therefore, the gas is not affected by the insulating oil. At the same time, external gas cannot penetrate the liquid layer through the outer sealing ring 9 to enter the left annular cavity 11 and the right annular cavity 12. The inner circle of the outer sealing ring 9 is tightly fitted to the central shaft 1, preventing the 25# mineral insulating oil from leaking from both ends of the axial direction, thus ensuring the integrity of the liquid sealing barrier.

[0028] The above embodiments illustrate the basic principles and features of the present invention, but are merely preferred embodiments and are not limited to these embodiments. Those skilled in the art, inspired by this patent, can make many modifications and improvements without departing from the spirit and scope of the claims, all of which fall within the scope of protection of the present invention. Therefore, the scope of this patent and its protection should be determined by the appended claims.

Claims

1. A rotary seal structure for a gas desorption dynamic measurement device for a friction test, characterized by: The center shaft is provided with a center line along the left-right direction, and a fixed cylinder shell is coaxially arranged on the center shaft and rotationally connected with the center shaft.

2. The rotating seal structure for a gas desorption dynamic measurement device for a friction test according to claim 1, characterized by: The gas overflow channel includes a center hole with the right end connected with the gas outlet of the coring tube.

3. The rotating seal structure for a gas desorption dynamic measurement device for a friction test according to claim 2, characterized by: The left and right ends of the inner circle of the fixed cylinder shell are rotationally connected with the outer circle of the center shaft through bearings. The solid-liquid sealing assembly includes two outer sealing rings and two inner sealing rings arranged between the inner circle of the fixed cylinder shell and the outer circle of the center shaft.

4. The rotary seal structure for a gas desorption dynamic measurement apparatus for a friction test according to any one of claims 1 to 3, characterized by: The left and right ends of the inner circle of the fixed cylinder shell are rotationally connected with the outer circle of the center shaft through bearings.

5. The rotating seal structure for a gas desorption dynamic measurement device for a friction test according to claim 3, characterized by: The solid-liquid sealing assembly includes two outer sealing rings and two inner sealing rings arranged between the inner circle of the fixed cylinder shell and the outer circle of the center shaft.

6. The rotating seal structure for a gas desorption dynamic measurement device for a friction test according to claim 3, characterized by: The left and right ends of the inner circle of the fixed cylinder shell are rotationally connected with the outer circle of the center shaft through bearings.

7. The rotating seal structure for a gas desorption dynamic measurement device for a friction test according to claim 3, characterized by: The solid-liquid sealing assembly includes two outer sealing rings and two inner sealing rings arranged between the inner circle of the fixed cylinder shell and the outer circle of the center shaft.

8. The rotating seal structure for a gas desorption dynamic measurement device for a friction test according to claim 3, characterized by: The left and right ends of the inner circle of the fixed cylinder shell are rotationally connected with the outer circle of the center shaft through bearings. The solid-liquid sealing assembly includes two outer sealing rings and two inner sealing rings arranged between the inner circle of the fixed cylinder shell and the outer circle of the center shaft. The left and right ends of the inner circle of the fixed cylinder shell are rotationally connected with the outer circle of the center shaft through bearings. The solid-liquid sealing assembly includes two outer sealing rings and two inner sealing rings arranged between the inner circle of the fixed cylinder shell and the outer circle of the center shaft. The left and right ends of the inner circle of the fixed cylinder shell are rotationally connected with the outer circle of the center shaft through bearings. The solid-liquid sealing assembly includes two outer sealing rings and two inner sealing rings arranged between the inner circle of the fixed cylinder shell and the outer circle of the center shaft. The left and right ends of the inner circle of the fixed cylinder shell are rotationally connected with the outer circle of the center shaft through bearings. The solid-liquid sealing assembly includes two outer sealing rings and two inner sealing rings arranged between the inner circle of the fixed cylinder shell and the outer circle of the center shaft. The left and right ends of the inner circle of the fixed cylinder shell are rotationally connected with the outer circle of the center shaft through bearings. 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