Multi-mode stress loading and unloading device for testing permeability of coal rock

Abstract

The invention discloses a multi-mode stress loading and unloading device for testing permeability of coal rock, which comprises a base, a piston water taking pump is arranged on the base, the upper end of the piston water taking pump is connected with a first piston rod, a water outlet of the piston water taking pump is connected with a pressure injection pipe, the pressure injection pipe is connected with a core holder, and the core holder is connected with a first piston rod. A water storage bin is fixed to the upper end of the base and connected with a water suction pump through a pipeline, the water suction pump is placed in the water storage pond, and the water storage bin is connected with a water inlet of the piston water taking pump through a pipeline. The multi-mode stress loading and unloading mode can be achieved, and different experiment condition requirements are met.

Description

Technical Field

[0001] The present invention relates to a multi-mode stress loading and unloading device for coal and rock permeability testing, belonging to the technical field of seepage experiment equipment for coalbed methane development. Background Art

[0002] In the prior art, an axial press and a confining press are usually used to load and unload stress during the coal and rock permeability testing. However, the existing axial press and confining press have the following technical problems: the loading and unloading methods of the sample stress are usually fixed and single; the stress conditions are difficult to stabilize; the accuracy of stress loading and unloading is insufficient; and the operation is inconvenient, etc. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a multi-mode stress loading and unloading device for coal and rock permeability testing to solve the technical problems existing in the above prior art.

[0004] The technical solution adopted by the present invention is as follows: a multi-mode stress loading and unloading device for coal and rock permeability testing, including a machine base, a piston water pump arranged vertically is provided at the upper end of the machine base, a first piston rod is slidably connected to the upper end of the piston water pump, a water injection pipe is connected to the water outlet of the piston water pump, the water injection pipe is connected to a core holder, a water storage bin is fixed at the upper end of the machine base, the water storage bin is connected to a water pump through a pipeline, and a water storage pool is further included, the water pump is placed inside the water storage pool, and the water storage bin is connected to the water inlet of the piston water pump through a pipeline; A pressure sensor is arranged on the water injection pipe, the pressure sensor is electrically connected to a controller, the controller is electrically connected to a display, the display is located on the front side of the machine base, and the display is a touch screen; The piston water pump is electrically connected to the controller; A constant pressure mode button is arranged on the touch screen. Clicking the constant pressure mode button can set the piston water pump to inject water with a specified pressure into the water injection pipe at one time; A constant speed mode button is arranged on the touch screen. Clicking the constant speed mode button can set the water injection speed of the piston water pump into the water injection pipe; A tracking mode button is arranged on the touch screen. Clicking the tracking mode button can set the lifting speed of the first piston rod of the piston water pump; A manual mode button is arranged on the touch screen. Clicking the manual mode button can manually operate the lifting of the first piston rod of the piston water pump.

[0005] Preferably, a power switch button is arranged on the machine base.

[0006] Preferably, the measurement range of the pressure sensor is from atmospheric pressure to 25 MPa, and the measurement accuracy is ±0.25% FS.

[0007] Preferably, a second piston rod arranged in the vertical direction is fixed to the upper end of the first piston rod. A second piston is fixed to the upper end of the second piston rod. A cylinder body arranged in the vertical direction is fixed to the frame. The second piston is slidably and sealingly connected inside the cylinder body. A cavity is provided on the side wall of the cylinder body. A one-way outlet valve and a one-way inlet valve are provided between the inside of the cylinder body and the top of the cavity. The one-way inlet valve is communicated with the bottom of the cavity through a suction pipe. The inside of the cylinder body is filled with non-Newtonian fluid.

[0008] Advantages of the present invention: 1. Compared with the prior art, in Embodiment 1 of the present invention, stress loading and unloading modes in multiple modes can be realized to meet the requirements of different experimental conditions; clean energy aqueous solution injection pressure is adopted, which is more economical and more conducive to pressure stability; multiple pressure loading and unloading methods are adopted to solve the problem of single stress loading and unloading method; after pressurizing to a predetermined pressure value in a short time, it can be quickly stabilized, solving the problem that stress conditions are difficult to stabilize; the stress setting on the operation interface can be accurate to three decimal places, solving the problem of insufficient stress loading and unloading accuracy; an operation interface is invented with four pressure loading and unloading methods, and a touch screen is adopted, which is convenient to operate.

[0009] 2. Compared with Embodiment 1, in Embodiment 2 of the present invention, the noise generated by the piston water pump due to vibration can be reduced, protecting the hearing of experimental personnel. Description of the drawings

[0010] Figure 1 is the overall structural schematic diagram of Embodiment 1 of the present invention.

[0011] Figure 2 is the structural schematic diagram of the piston water pump and the cylinder body of Embodiment 2 of the present invention.

[0012] Figure 3 is Figure 2 the enlarged view of part A in

[0013] The reference numerals in the drawings of the specification include: machine base 1, power switch 2, display 3, piston water pump 4, first piston rod 5, injection pipe 6, water storage bin 7, water pump 8, water storage pool 9, second piston rod 10, second piston 11, cylinder body 12, cavity 13, one-way outlet valve 14, one-way inlet valve 15, suction pipe 16. Detailed implementation manners

[0014] The present invention will be further introduced below in conjunction with the drawings and specific embodiments.

[0015] Embodiment 1: A multi-mode stress loading and unloading device for coal and rock permeability testing, as Figure 1 shown, includes a base 1. At the upper end of the base 1, there is a piston water pump 4 arranged vertically. The upper end of the piston water pump 4 is slidably and sealingly connected with a first piston rod 5. The water outlet of the piston water pump 4 is connected with an injection pressure pipe 6. The injection pressure pipe 6 is connected to a core holder. At the upper end of the base, a water storage bin 7 is fixed. The water storage bin 7 is connected with a water pump 8 through a pipeline. There is also a water storage pool 9. The water pump 8 is placed inside the water storage pool 9. The water storage bin 7 is connected with the water inlet of the piston water pump 4 through a pipeline; When the first piston rod 5 moves upward, the piston water pump 4 sucks the water inside the water storage bin 7. When the first piston rod 5 moves downward, the piston water pump 4 drains water to the core holder through the injection pressure pipe 6 to pressurize the core holder.

[0016] A pressure sensor is arranged on the injection pressure pipe 6. The measurement range of the pressure sensor is normal pressure - 25 MPa, and the measurement accuracy is ±0.25% FS. The pressure sensor is electrically connected with a controller, and the controller is electrically connected with a display 3. The display 3 is located on the front side of the base 1. The display 3 is a touch screen and is also called an operation panel; The piston water pump 4 is electrically connected with the controller; A constant pressure mode button is arranged on the touch screen. Click the constant pressure mode button to set the piston water pump 4 to inject water with a specified pressure into the injection pressure pipe 6 at one time. When the pressure sensor monitors that there is a large fluctuation in the pressure inside the core holder, the piston water pump 4 will intermittently inject / extract a certain volume of solution into the injection pressure pipe 6 to stabilize the pressure inside the core holder; A constant speed mode button is arranged on the touch screen. Click the constant speed mode button to set the water injection speed of the piston water pump 4 into the injection pressure pipe 6. The water pump 8 pumps a certain amount of solution into the liquid storage bin at regular intervals, and slowly injects pressure through the first piston rod 5 to take water, realizing the determination of coal and rock permeability under variable pressure conditions; A tracking mode button is arranged on the touch screen. Click the tracking mode button to set the lifting speed of the first piston rod 5 of the piston water pump 4; To meet the sometimes fast and large flow rate requirements in the pressure increasing section, by adjusting the lifting speed of the piston water pump 4, the flow rate injected into the injection pressure pipe 6 is adjusted, and the pressure inside the core holder is changed to achieve precise pressure tracking in the pressure increasing section.

[0017] A manual mode button is arranged on the touch screen. Click the manual mode button to manually operate the lifting of the first piston rod 5 of the piston water pump 4. When the instrument fails, or the pressure loading and unloading speed is too slow, the manual mode can be used to control the lifting of the first piston rod 5 of the piston water pump 4.

[0018] In this embodiment, a power switch 2 button is arranged on the base 1.

[0019] Example 2 During the use of the piston water pump 4, vibrations are likely to occur, generating noise and damaging the hearing of the experimenters.

[0020] The difference between Example 2 and Example 1 is that as Figures 2 - 3 shown, a second piston rod 10 arranged vertically is coaxially fixed to the upper end of the first piston rod 5, a cylindrical second piston 11 is fixed to the upper end of the second piston rod 10, a cylinder 12 arranged vertically is fixed to the frame, the second piston 11 is slidably and sealingly connected inside the cylinder 12, the second piston 11 and the cylinder 12 are coaxially arranged, an annular cavity 13 is provided on the side wall of the cylinder 12, a one-way outlet valve 14 and a one-way inlet valve 15 are provided between the inside of the cylinder 12 and the top of the cavity 13, the one-way inlet valve 15 is communicated with the bottom of the cavity 13 through a straw 16, and the inside of the cylinder 12 is filled with non-Newtonian fluid.

[0021] When the non-Newtonian fluid is subjected to a sudden impact force, it will become solid, and when the external force disappears, after a period of time, the non-Newtonian fluid will return to its liquid state.

[0022] During the water intake and discharge process of the piston water pump 4, the first piston rod 5 drives the second piston rod 10 to move up and down synchronously. When the second piston rod 10 moves upward, a positive pressure is generated inside the cylinder 12, the one-way inlet valve 15 closes, and the one-way outlet valve 14 opens. The second piston 11 squeezes the non-Newtonian fluid inside the cylinder 12 into the cavity 13. When the second piston rod 10 moves downward, a negative pressure is generated inside the cylinder 12, the one-way inlet valve 15 opens, and the one-way outlet valve 14 closes. The non-Newtonian fluid in the cavity 13 is sucked into the inside of the cylinder 12, and this process is repeated continuously.

[0023] During the upward movement of the second piston rod 10, if the first piston rod 5 vibrates severely, the non-Newtonian fluid inside the cylinder 12 will be subjected to a sudden impact force from the second piston 11 and become solid, thereby preventing the severe vibration of the second piston rod 10 and the first piston rod 5, reducing noise. After a period of time, the non-Newtonian fluid will return to its liquid state again; during the downward movement of the second piston rod 10, on the one hand, the negative pressure inside the cylinder 12 will slow down the downward movement speed of the first piston rod 5 and the second piston rod 10, and on the other hand, the water inside the piston water pump 4 will also slow down the downward movement speed of the first piston rod 5 and the second piston rod 10, thereby reducing vibrations and noise.

[0024] As described above, it is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claimed rights.

Claims

1. A multi-mode stress loading and unloading device for coal and rock permeability testing, characterized in that: It includes a machine base, at the upper end of the machine base, there is a piston water pump arranged vertically, at the upper end of the piston water pump, a first piston rod is slidably connected, the water outlet of the piston water pump is connected to a pressure injection pipe, the pressure injection pipe is connected to a core holder, at the upper end of the machine base, a water storage bin is fixed, the water storage bin is connected to a water pump through a pipeline, and there is also a water storage pool, the water pump is placed inside the water storage pool, and the water storage bin is connected to the water inlet of the piston water pump through a pipeline; A pressure sensor is arranged on the pressure injection pipe, the pressure sensor is electrically connected to a controller, the controller is electrically connected to a display, the display is located on the front side of the machine base, and the display is a touch screen; The piston water pump is electrically connected to the controller; A constant pressure mode button is arranged on the touch screen, by clicking the constant pressure mode button, the piston water pump is set to inject water with a specified pressure into the pressure injection pipe at one time; A constant speed mode button is arranged on the touch screen, by clicking the constant speed mode button, the water injection speed of the piston water pump into the pressure injection pipe is set; A tracking mode button is arranged on the touch screen, by clicking the tracking mode button, the lifting speed of the first piston rod of the piston water pump is set; A manual mode button is arranged on the touch screen, by clicking the manual mode button, the lifting of the first piston rod of the piston water pump is manually operated.

2. The multi-mode stress loading and unloading device for coal and rock permeability testing according to claim 1, wherein: A power switch button is arranged on the machine base.

3. A multi-mode stress loading and unloading device for coal and rock permeability testing according to claim 1, characterized in that: The measurement range of the pressure sensor is normal pressure - 25 MPa, and the measurement accuracy is: ±0.25% FS.

4. A multi-mode stress loading and unloading device for coal and rock permeability testing according to claim 1, characterized in that: At the upper end of the first piston rod, a second piston rod arranged vertically is fixed, at the upper end of the second piston rod, a second piston is fixed, on the frame, a cylinder body arranged vertically is fixed, the second piston is slidably and sealingly connected inside the cylinder body, a cavity is arranged on the side wall of the cylinder body, a one-way outlet valve and a one-way inlet valve are arranged between the inside of the cylinder body and the top of the cavity, the one-way inlet valve is communicated with the bottom of the cavity through a suction pipe, and the inside of the cylinder body is filled with non-Newtonian fluid.

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