Explosion-proof cooling device for underground coal mines

Abstract

The invention discloses an explosion-proof cooling device for underground coal mines, including a frame, in which an air-cooled condenser, a compressor unit, a shell-and-tube evaporator and a base are installed, and a programmable control box is installed at the left end of the frame; the air-cooled condenser is used for heat dissipation and cooling of the coolant compressed gas; the compressor unit is used for compressing the gas refrigerant, including an oil separator, a twin-screw compressor, a first motor, a double-circuit reversible vacuum electromagnetic starter, a liquid storage tank, a first drying filter and a second drying filter; the shell-and-tube evaporator is used for heat exchange between high-temperature nitrogen and low-temperature refrigerant. The cooling device of the present invention can recycle the refrigerant used when it works, reducing the investment of resources and costs in this part, saving refrigeration costs, and the nitrogen in the device can quickly and continuously release low-temperature nitrogen, efficiently achieving the air temperature in a large range of the mining area, and inerting the air, reducing the oxidation and spontaneous combustion rate of coal, inhibiting gas explosion, and improving the safety of the mining area.

Description

Technical Field

[0001] The present invention relates to the technical field of mining equipment, in particular to an explosion-proof cooling device used in underground coal mines. Background Art

[0002] Coal combustion requires a certain concentration of oxygen and high temperatures. When exposed to air, coal oxidizes, releasing heat. If this heat cannot be dissipated quickly, the temperature will continue to rise, eventually leading to combustion or even explosion. Therefore, idle coal mines require the introduction of large quantities of nitrogen to prevent combustion or explosion. As a dry, inert gas, nitrogen is continuously introduced into the mining area for several important purposes: 1. It reduces the oxygen content in the mining area. The nitrogen displaces air and exchanges oxygen with the coal surface, reducing the oxygen content in the mining area, slowing the oxidation process, reducing the heat released by oxidation, and preventing combustion. 2. Continuous nitrogen infusion penetrates into the cracks in the coal seam, creating a slightly positive pressure throughout the mining area, effectively reducing air leakage and air ingress. 3. It neutralizes explosives. Once nitrogen is introduced into the mining area, it mixes with other flammable and explosive gases, reducing their volume. When the volume of the mixed gas reaches a certain value, the explosion point of the flammable and explosive gas will drop to the lower limit or below the lower limit.

[0003] Most coal mines in my country suffer from poor ventilation and working surface temperatures exceeding 35°C. High temperatures not only significantly reduce work efficiency but also seriously impact the health of underground workers. However, existing cooling devices are relatively simple in structure. For example, blowers and other devices are often used to cool mining equipment. However, air has low thermal conductivity and a limited cooling range, resulting in poor performance and insufficient performance within the mining area. Therefore, we provide explosion-proof cooling devices for underground coal mines to address these issues. Summary of the Invention

[0004] In response to the problems existing in the above-mentioned prior art, the present invention provides an explosion-proof cooling device for underground coal mines. After the refrigerant is processed by the compressor unit, heat exchange occurs with high-temperature nitrogen in the shell and tube evaporator to achieve the discharge of low-temperature nitrogen, quickly reducing the temperature of the coal mine goaf. Compared with air heat dissipation, the injection of nitrogen can inert the air and reduce the probability of spontaneous combustion of coal. In addition, the refrigeration work is fast and efficient, and the temperature can be reduced over a large range, meeting the use requirements of work in the mining area and improving work safety.

[0005] To achieve the above-mentioned object, the present invention adopts an explosion-proof cooling device for use in underground coal mines, comprising a frame, in which an air-cooled condenser, a compressor unit, a shell and tube evaporator, and a base are installed, and the compressor unit and the shell and tube evaporator are installed on the base. A programmable control box for controlling the operation of the cooling device is installed at the left end of the frame;

[0006] The air-cooled condenser is used to dissipate heat and cool the compressed gas. There are two sets of air-cooled condensers, which are installed horizontally and in parallel on the top of the frame.

[0007] The compressor unit is used to compress the gas refrigerant and includes an oil separator, a twin-screw compressor, a first motor, a dual-circuit reversible vacuum electromagnetic starter, a liquid storage tank, a first filter drier and a second filter drier. The twin-screw compressor is connected to a compressor liquid spray cooling pipeline, which is equipped with an expansion valve and a sight glass.

[0008] The shell and tube evaporator is used for heat exchange between high-temperature nitrogen and low-temperature refrigerant, and a nitrogen inlet pipe and a nitrogen outlet pipe are respectively provided at both ends of the evaporator.

[0009] Among the components of the compressor unit, the twin-screw compressor is provided with a compressor exhaust pipeline, a compressor liquid spray cooling pipeline, a compressor oil supply pipeline and a compressor suction pipeline, and is connected to the oil separator through the compressor exhaust pipeline and the compressor oil supply pipeline. A pressure sensor and a temperature sensor are installed on the compressor exhaust pipeline. An oil filter and a second drying filter are installed on the compressor oil supply pipeline. An oil separation output pipeline is provided on the oil separator of the compressor unit, and is connected to the first drying filter through the pipeline. The first drying filter is connected to the liquid storage tank through the liquid storage tank output pipeline. The liquid storage tank is connected to the condenser output pipeline, and is connected to the air-cooled condenser through the pipeline.

[0010] During operation, the coolant is sucked in and compressed into the suction side of the twin-screw compressor, and refrigeration oil is injected into the compression chamber of the twin-screw compressor. The twin-screw compressor compresses the mixed coolant and discharges it into the oil separator, separates the refrigeration oil and sends it back to the various chambers and bearing parts of the twin-screw compressor. The separated coolant is cooled by the air-cooled condenser and becomes a low-temperature liquid refrigerant. The liquid refrigerant is filtered and expanded and evaporated by the expansion valve to become gas and sent to the shell and tube evaporator. The low-temperature gaseous refrigerant and room-temperature nitrogen exchange heat in the shell and tube evaporator. The refrigerant after heat exchange rises in temperature and flows out to re-enter the twin-screw compressor, and the cycle works in this way. The nitrogen after heat exchange becomes low-temperature nitrogen and is discharged from the nitrogen outlet pipeline.

[0011] As a further optimization of the above solution, the air-cooled condenser includes a fin-and-tube condenser and a cooling fan assembly mounted above the fin-and-tube condenser, a second motor, and a fan protection screen. The cooling fan assembly is fixed to the upper portion of the frame, with its drive end connected to the output end of the second motor. The fan protection screen is mounted on the outer side of the cooling fan assembly's blades. Both the second motor and the first motor are flameproof motors for mining. As a further optimization of the above solution, a ball valve is installed on the nitrogen outlet line, and both the nitrogen inlet and outlet lines extend outside the frame.

[0012] As a further optimization of the above solution, lifting rings for moving and lifting the cooling device are installed at the four corners of the top of the frame, and a condenser protection net is provided on the top surface.

[0013] As a further optimization of the above scheme, three normally closed mining-grade casting solenoid valves are provided on the twin-screw compressor, a laminated flexible coupling is connected between the twin-screw compressor and the first motor, and a dual-circuit reversible vacuum electromagnetic starter is used to control the operation of the first motor and the second motor.

[0014] As a further optimization of the above solution, the compressor liquid spray cooling pipeline, the compressor oil supply pipeline, and the oil separation output pipeline are all installed with welded straight-through stop valves, and the compressor suction pipeline is installed with a welded stop check valve.

[0015] As a further optimization of the above solution, the frame is equipped with three pressure gauges on one side of the programmable control box, namely an oil pressure gauge installed on the compressor oil supply pipeline, a low pressure gauge installed on the compressor suction pipeline, and a high pressure gauge installed on the compressor exhaust pipeline.

[0016] As a further optimization of the above scheme, a safety valve is installed on the oil separator, the bottom of the oil separator is connected to the compressor oil supply pipeline, and the upper part is connected to the compressor exhaust pipeline. The twin-screw compressor is connected to an external liquid spray cooling system through the compressor liquid spray cooling pipeline, and the shell and tube evaporator is provided with an evaporator liquid supply pipeline connected to the liquid spray cooling system.

[0017] As a further optimization of the above solution, the twin-screw compressor is equipped with a four-stage capacity control system or a stepless capacity control system. The four-stage capacity control system will load the capacity in the order of 25%-50%-75%-100% through three mining-grade casting solenoid valves, and then unload it in the order of 100%-75%-50%-25%.

[0018] The explosion-proof cooling device for underground coal mines of the present invention has the following beneficial effects:

[0019] 1. The explosion-proof cooling device for underground coal mines of the present invention adopts the circulation of compressed refrigerant gas to generate low temperature, cools and freezes the room temperature compressed nitrogen flowing through the shell and tube evaporator, and injects the cooled nitrogen into the air in the mining area to reduce the temperature of the air in the area, as well as the oxygen content and the concentration of combustible gas in the air, inertize the air, and make it lose its explosiveness, thereby achieving the effect of reducing the oxidation and spontaneous combustion of coal in the mining area and suppressing gas explosions, meeting the use needs in the mining area and improving the safety of mining work.

[0020] 2. The explosion-proof cooling device for underground coal mines of the present invention, when in operation, operates in a circulation mode in which the refrigerant passes through the compressor unit, the air-cooled condenser, the shell and tube evaporator, and then returns to the compressor unit. This not only avoids the impact on the environment during discharge, but also reduces the investment in resources and costs, thus saving the operating cost of the cooling device and thus reducing the refrigeration cost.

[0021] 3. In the explosion-proof cooling device for underground coal mines of the present invention, heat exchange occurs between nitrogen and refrigerant gas in a shell and tube evaporator, and then low-temperature nitrogen is directly discharged. The nitrogen cooling path is short and the cooling efficiency is high. The rapid and continuous low-temperature nitrogen discharge can quickly reduce the air temperature in a large area of ​​the mining area. The cooled mining environment helps to improve the work efficiency of the staff.

[0022] 4. The explosion-proof cooling device for underground coal mines of the present invention, wherein the setting of the cooling fan assembly in the air-cooled condenser can not only blow air to exchange heat with the refrigerant inside the copper tube to achieve the purpose of cooling the refrigerant, but also reduce the temperature of the tube-fin condenser during operation. The device is also externally connected to a liquid spray cooling system to cool the twin-screw compressor and the shell and tube evaporator. The two cooling methods effectively reduce the probability of failure of the main working components of the device.

[0023] With reference to the following description and drawings, specific embodiments of the present invention are disclosed in detail, indicating how the principles of the present invention can be adopted. It should be understood that the scope of the embodiments of the present invention is not limited thereby, and the embodiments of the present invention include many changes, modifications and equivalents. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a front perspective view of the present invention;

[0025] Figure 2 It is a rear perspective view of the present invention;

[0026] Figure 3 For Figure 1 A top view showing the corresponding pipes and accessories;

[0027] Figure 4 It is a schematic diagram of the position and structure of the air-cooled condenser of the present invention;

[0028] Figure 5 It is a structural schematic diagram of the fan assembly of the present invention;

[0029] Figure 6 For Figure 2 The corresponding top view only retains the base and main components;

[0030] Figure 7 is a side view of the present invention;

[0031] Figure 8For Figure 2 corresponding front view;

[0032] Figure 9 For Figure 1 corresponding front view;

[0033] Figure 10 For Figure 2 A top view of the device with the corresponding air-cooled condenser and condenser protective screen removed;

[0034] Figure 11 This is a schematic diagram of the twin-screw compressor in Example 2 when it is in a starting state with a load of 25%;

[0035] Figure 12 This is a schematic diagram of the twin-screw compressor in Example 2 when it is running at 50% load;

[0036] Figure 13 This is a schematic diagram of the twin-screw compressor in Example 2 when it is operated at 75% load;

[0037] Figure 14 This is a schematic diagram of the twin-screw compressor in Example 2 when it is running at 100% load;

[0038] Figure 15 This is a workflow diagram of the present invention when it is running.

[0039] In the figure: 1. Twin-screw compressor; 2. First motor; 3. Air-cooled condenser; 4. Fan protection net; 5. Second motor; 6. Cooling fan assembly; 7. Shell and tube evaporator; 8. Oil separator; 9. Dual-circuit reversible vacuum electromagnetic starter; 10. Liquid storage tank; 11. First filter drier; 12. Base; 13. Frame; 14. Condenser protection net; 15. Programmable control box; 16. Pressure gauge; 17. Mine-use casting electromagnetic valve; 18. Laminated flexible coupling; 19. Second filter drier; 20. Welded straight-through stop valve; 21. Compressor exhaust line; 22. Pressure sensor; 23. Temperature sensor; 24. Oil separation output line; 25. Lifting ring; 26. Condenser output line; 27. Liquid storage tank output line; 28. Compressor spray cooling line; 29. ​​Nitrogen outlet line; 30. Sight glass; 31. Expansion valve; 32. Evaporator liquid supply line; 33. Compressor suction line; 34. Welded stop check valve; 35. Safety valve; 36. Compressor oil supply line; 37. Oil filter; 38. Nitrogen inlet line; 39. Ball valve; 40. Spray cooling system. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below through the accompanying drawings and embodiments. However, it should be understood that the specific embodiments described herein are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0041] It should be noted that when an element is referred to as being "disposed on, provided with" another element, it may be directly on the other element or there may also be a central element. When an element is considered to be "connected, connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. "Fixed connection" means a fixed connection. There are many ways of fixed connection, which are not within the scope of protection of this article. The terms "vertical", "horizontal", "left", "right" and similar expressions used in this article are for illustrative purposes only and do not represent the only implementation method.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention pertains. The terms used in the specification are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items. Example

[0043] Reference Figures 1 to 3 The present invention provides a technical solution: an explosion-proof cooling device for underground coal mines, comprising a frame 13, wherein an air-cooled condenser, a compressor unit, a shell and tube evaporator 7 and a base are installed in the frame 13, and the compressor unit and the shell and tube evaporator 7 are installed on the base, and a programmable control box 15 for controlling the operation of the cooling device is installed at the left end of the frame 13, and the programmable control box 15 is mainly used for displaying data and controlling the start and stop of the device through a program; three pressure gauges 16 are installed on one side of the programmable control box 15 of the frame 13, namely an oil pressure gauge installed on the compressor oil supply pipeline 36, a low pressure gauge installed on the compressor suction pipeline 36, and a high pressure gauge installed on the compressor exhaust pipeline 21; lifting rings 25 are installed at the four corners of the top of the frame 13 for lifting and shifting the device after the overall movement, and a condenser protection net 14 is provided on the top surface of the frame 13.

[0044] Reference Figures 4 to 5The air-cooled condenser 3 is used to dissipate heat and cool down the coolant compressed gas. There are two groups of air-cooled condensers 3, which are horizontally installed in parallel on the top of the frame 13. The air-cooled condenser 3 includes a tube-fin condenser and a cooling fan assembly 6 installed above the tube-fin condenser, a second motor 5 and a fan protection net 4. The cooling fan assembly 6 is fixed to the upper part of the frame 13, and the driving end is connected to the output end of the second motor 5. The fan protection net 4 is installed on the outside of the fan blades of the cooling fan assembly 6. The second motor 5 is a mining explosion-proof motor. The tube-fin condenser is composed of copper tubes and aluminum sheets. When the high-temperature gaseous refrigerant passes through the radiator copper tube, the cooling fan assembly 6 blows air to exchange heat with the refrigerant inside the copper tube to achieve the purpose of cooling the refrigerant. At the same time, the aluminum heat sink of the condenser increases the heat dissipation area and improves the heat exchange capacity.

[0045] Reference Figures 1 to 3 and 6 to 10, the compressor unit is used for compressing gas refrigerant, including an oil separator 8, a twin-screw compressor 1, a first motor 2, a dual-circuit reversible vacuum electromagnetic starter 9, a liquid storage tank 10, a first drying filter 11 and a second drying filter 19, wherein the twin-screw compressor 1 is equipped with a stepless capacity control system, which can control the loading or unloading of the twin-screw compressor 1 by controlling the switch of one or two mining-used cast-in solenoid valves 17, with a capacity adjustment range of 25%-100%, and is provided with a compressor liquid spray cooling pipeline 28, on which an expansion valve 31 and a sight glass 30 are installed; the first motor Motor 2 is a flameproof motor for mining. A dual-circuit reversible vacuum electromagnetic starter 9 controls the start and stop of motors 1 and 5. It provides overload, phase failure, leakage lockout, and short-circuit protection. A liquid crystal display (LCD) is located within the housing's observation window, displaying operational status, parameters, and faults. A communication interface is also provided for remote monitoring. A sight glass 30 indicates the dryness of the refrigerant: blue = dry, purple = damp, and reddish-purple = wet. Expansion valve 31 continuously supplies refrigerant to shell-and-tube evaporator 7, ensuring that the supplied refrigerant evaporates at the operating temperature. This ensures that the heat exchange surface of shell-and-tube evaporator 7 is fully utilized. The provision of expansion valve 31 ensures optimal charging of shell-and-tube evaporator 7 even when cooling capacity fluctuates, minimizing the impact of the refrigerant pressure changing from high to low during expansion. It also ensures that the gas drawn into twin-screw compressor 1 reaches the correct temperature.

[0046] Reference Figures 1 to 3 6 to 10, the shell and tube evaporator 7 is used for heat exchange between high-temperature nitrogen and low-temperature refrigerant, and a nitrogen inlet pipeline 38 and a nitrogen outlet pipeline 29 are respectively provided at its two ends; a ball valve 39 is installed on the nitrogen outlet pipeline 29, and the nitrogen inlet pipeline 38 and the nitrogen outlet pipeline 29 both extend to the outside of the frame 13.

[0047] Reference Figures 3 to 10 Among the components of the compressor unit, the twin-screw compressor 1 is provided with a compressor exhaust pipeline 21, a compressor liquid spray cooling pipeline 28, a compressor oil supply pipeline 36 and a compressor suction pipeline 33, and is connected to the oil separator 8 through the compressor exhaust pipeline 21 and the compressor oil supply pipeline 36. A pressure sensor 22 and a temperature sensor 23 are installed on the compressor exhaust pipeline 21. An oil filter 37 and a second drying filter 19 are installed on the compressor oil supply pipeline 36. An oil separation output pipeline 24 is provided on the oil separator 8 of the compressor unit, and is connected to the first drying filter 11 through the pipeline. The first drying filter 11 is connected to the liquid storage tank 10 through the liquid storage tank output pipeline 27. The liquid storage tank 10 is connected to the condenser output pipeline 2 6, and is connected to the air-cooled condenser 3 through the pipeline; a safety valve 35 is installed on the oil separator 8, the bottom of the oil separator 8 is connected to the compressor oil supply pipeline 36, and the upper part is connected to the compressor exhaust pipeline 21; the compressor spray cooling pipeline 28, the compressor oil supply pipeline 36, and the oil separation output pipeline 24 are all installed with a welded straight-through stop valve 20, and the compressor suction pipeline 33 is installed with a welded stop check valve 34; three normally closed mining-use cast-in solenoid valves 17 are provided on the twin-screw compressor 1, and a laminated flexible coupling 18 is connected between the twin-screw compressor 1 and the first motor 2. The mining-use cast-in solenoid valve 17 is used to control the oil circuit of the twin-screw compressor 1, and control the loading and unloading actions of the twin-screw compressor 1 by oil pressure.

[0048] Reference Figure 15 The twin-screw compressor 1 is connected to an external liquid spray cooling system 40 through a compressor liquid spray cooling pipeline 28 , and the shell and tube evaporator 7 is provided with an evaporator liquid supply pipeline 32 connected to the liquid spray cooling system 40 .

[0049] The mining cooling device in Example 1 needs to be inspected before use, specifically:

[0050] 1. Check all parts to ensure that the pipeline connections are reliable, and purge and clean the air-cooled condenser 3.

[0051] 2. Check the forward and reverse rotation of the twin-screw compressor 1 by jogging.

[0052] 3. Leakage test: Use a brush to brush each joint and observe whether there are bubbles or observe the pressure gauge reading of the equipment itself. The sealing test should last for at least 24 hours.

[0053] After the inspection, the staff will take safety measures and then can start, run, reset and troubleshoot the equipment by operating the programmable control box 15.

[0054] Working principle of the mining cooling device in Example 1:

[0055] Reference Figure 15 , refrigerant R22 is selected as the refrigerant gas. The refrigerant gas is sucked in through the compressor suction pipe 33 of the twin-screw compressor 1, filtered to the suction side after compression, and then injected into the internal compression chamber, bearings, and shaft seal suction space through the compressor oil supply pipe 36. The twin-screw compressor 1 compresses the refrigerant mixed with oil and discharges it from the compressor exhaust pipe 21. The refrigerant mixed with oil is separated into refrigeration oil in the oil separator 8, and the refrigeration oil is sent back to the compression chamber and various bearing parts of the twin-screw compressor 1 through the compressor oil supply pipe 36. After separation, the compressed coolant gas passes through the air-cooled condenser 3, where it dissipates heat and cools, becoming a low-temperature liquid refrigerant. The liquid refrigerant is filtered, expanded and evaporated by the expansion valve 31, and then fed into the shell-and-tube evaporator 7. The low-temperature refrigerant gas exchanges heat with the high-temperature nitrogen gas within the shell-and-tube evaporator 7. After the refrigerant heats up, it flows out of the shell-and-tube evaporator 7 and enters the twin-screw compressor 1 through the compressor suction line 33. This cycle of compression and refrigeration continues, and the nitrogen gas, after heat exchange, becomes low-temperature nitrogen gas and is discharged through the nitrogen outlet line 29. Pressure and temperature sensors on each low-temperature pipeline monitor the pressure and temperature, and a control program ensures that the compressor and system operate normally under the predetermined pressure and temperature conditions.

[0056] The low-temperature nitrogen discharged from the nitrogen outlet pipe 29 enters the fire prevention and extinguishing area of ​​the mining area, diluting the oxygen and other gases in the area, reducing the concentration of combustible gases and oxygen content, and inerting the goaf, thereby achieving the effect of suppressing explosions. At the same time, the low-temperature nitrogen has a cooling effect on the surrounding environment. The lower the temperature, the greater the corresponding heat exchange and the more obvious the cooling effect. Example

[0057] Different from the first embodiment, the twin-screw compressor 1 adopts a four-stage capacity control system, which loads the capacity in the order of 25%-50%-75%-100% through three mining-used casting solenoid valves 17, and then unloads the capacity in the order of 100%-75%-50%-25%.

[0058] Specifically, when the twin-screw compressor 1 operates under the following conditions: suction pressure: >-0.5 bar; discharge pressure: <18 bar; oil pressure: ≥6 bar; suction temperature: <-30.0°C; discharge temperature: <80°C, the specific operating steps for loading using the four-stage capacity control system are as follows:

[0059] a. 25% startup state, see the state diagram Figure 11 ;

[0060] When the twin-screw compressor 1 is started, 25% of the mining-grade cast-in solenoid valve 17 is energized. Even if the oil enters the main oil circuit from the external oil distributor and then enters the hydraulic cylinder, the high-pressure oil will directly bypass the low-pressure end, so the piston will remain at the initial point.

[0061] b. 50% load operation, see the status diagram Figure 12 ;

[0062] At this point, the 25% solenoid valve is closed, so lubricating oil continues to be supplied to the hydraulic cylinder. When the control system sends a signal to the 50% mining-sealed solenoid valve 17 to energize it, lubricating oil bypasses this 50% mining-sealed solenoid valve 17 to flow to the low-pressure side. The volume adjustment piston is maintained in the bypass port position due to the oil bypass. When the volume adjustment slider is in the 50% position, some refrigerant returns to the low-pressure side from the bypass circuit, maintaining the compression volume at 50%.

[0063] c. 75% load operation, see the status diagram Figure 13 ;

[0064] When the control system sends a signal to the 75% mining casting solenoid valve 17 to energize it, the 50% mining casting solenoid valve 17 is deenergized. Therefore, no lubricating oil bypasses from the 50% to the low-pressure side. At this time, the piston is pushed to the 75% bypass port by the oil continuously entering the hydraulic cylinder, and oil bypasses from the 75% mining casting solenoid valve 17 to the low-pressure side. At this time, the slider position is 75%, and some refrigerant returns to the low-pressure side from the bypass circuit, maintaining the compression volume at 75%.

[0065] d. 100% load operation, see the status diagram Figure 14 ;

[0066] All mining-used cast-in solenoid valves 17 are not energized (not energized), and there is no oil bypass. The lubricating oil directly enters the hydraulic cylinder to push the capacity adjustment piston forward. The capacity adjustment piston drives the capacity adjustment slider, so that the bypass space of the compression chamber gradually becomes smaller until the capacity adjustment slider is completely pushed to the bottom. At this time, the twin-screw compressor 1 is in a 100% full-load operation state.

[0067] The twin-screw compressor 1 can complete capacity loading through the above steps, and then unload in the order of 100%-75%-50%-25%, thereby completing capacity control of the twin-screw compressor 1.

[0068] During use, a stepless capacity adjustment control system or a four-stage capacity adjustment control system can be selected for the twin-screw compressor 1 according to the environment and use conditions.

[0069] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements or improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An explosion-proof cooling device for underground coal mines, characterized in that: The invention comprises a frame (13), wherein an air-cooled condenser (3), a compressor unit, a shell and tube evaporator (7) and a base (12) are installed in the frame (13), and the compressor unit and the shell and tube evaporator (7) are installed on the base (12); and a programmable control box (15) for controlling the operation of the cooling device is installed at the left end of the frame (13); The air-cooled condenser (3) is used to dissipate heat and cool the compressed gas of the coolant. There are two groups of air-cooled condensers (3) which are horizontally installed in parallel on the top of the frame (13). The compressor unit is used for compressing a gas refrigerant, and comprises an oil separator (8), a twin-screw compressor (1), a first motor (2), a dual-circuit reversible vacuum electromagnetic starter (9), a liquid storage tank (10), a first drying filter (11), and a second drying filter (19), wherein the twin-screw compressor (1) is connected to a compressor liquid spray cooling pipeline (28), and an expansion valve (31) and a sight glass (30) are installed on the pipeline; The shell and tube evaporator (7) is used for heat exchange between high-temperature nitrogen and low-temperature refrigerant, and a nitrogen inlet pipeline (38) and a nitrogen outlet pipeline (29) are respectively provided at both ends of the evaporator; Among the components of the compressor unit, the twin-screw compressor (1) is provided with a compressor exhaust pipeline (21), a compressor liquid spray cooling pipeline (28), a compressor oil supply pipeline (36) and a compressor suction pipeline (33), and is connected to an oil separator (8) via the compressor exhaust pipeline (21) and the compressor oil supply pipeline (36), and a pressure sensor (22) and a temperature sensor (23) are installed on the compressor exhaust pipeline (21), an oil filter (37) and a second drying filter (19) are installed on the compressor oil supply pipeline (36), an oil separation output pipeline (24) is provided on the oil separator (8) of the compressor unit, and is connected to a first drying filter (11) via the oil separation output pipeline (24), and the first drying filter (11) is connected to a liquid storage tank (10) via a liquid storage tank output pipeline (27), and the liquid storage tank (10) is connected to a condenser output pipeline (26), and is connected to an air-cooled condenser (3) via the pipeline; When the compressor is working, the coolant is sucked in and compressed to the suction side of the twin-screw compressor (1), and refrigeration oil is injected into the compression chamber of the twin-screw compressor (1). The twin-screw compressor (1) compresses the mixed coolant and discharges it into the oil separator (8), separates the refrigeration oil and sends it back to the various chambers and bearing parts of the twin-screw compressor (1). The separated coolant passes through the air-cooled condenser (3) for heat dissipation and cooling, and then becomes a low-temperature liquid refrigerant. The liquid refrigerant is filtered and expanded and evaporated by the expansion valve (31) to become gas and is sent to the shell and tube evaporator (7). The low-temperature gaseous refrigerant exchanges heat with normal-temperature nitrogen in the shell and tube evaporator (7). The refrigerant after heat exchange is heated up and flows out to re-enter the twin-screw compressor (1), and the cycle is repeated. The nitrogen after heat exchange becomes low-temperature nitrogen and is discharged from the nitrogen outlet pipe (29).

2. The explosion-proof cooling device for underground coal mines according to claim 1, characterized in that: The air-cooled condenser (3) comprises a tube-fin condenser and a cooling fan assembly (6) installed above the tube-fin condenser, a second motor (5) and a fan protection net (4); the cooling fan assembly (6) is fixed to the upper part of the frame (13), and the driving end is connected to the output end of the second motor (5); the fan protection net (4) is installed on the outer side of the fan blades of the cooling fan assembly (6); the second motor (5) and the first motor (2) are both flameproof motors for mining.

3. The explosion-proof cooling device for underground coal mines according to claim 2, characterized in that: A ball valve (39) is installed on the nitrogen outlet pipeline (29), and the nitrogen inlet pipeline (38) and the nitrogen outlet pipeline (29) both extend to the outside of the frame (13).

4. The explosion-proof cooling device for underground coal mines according to claim 3, characterized in that: Lifting rings (25) for moving and lifting the cooling device are installed at the four corners of the top of the frame (13), and a condenser protection net (14) is provided on the top surface.

5. The explosion-proof cooling device for underground coal mines according to claim 4, characterized in that: The twin-screw compressor (1) is provided with three normally closed mining-use casting electromagnetic valves (17); a laminated flexible coupling (18) is connected between the twin-screw compressor (1) and the first motor (2); and a dual-circuit reversible vacuum electromagnetic starter (9) is used to control the operation of the first motor (2) and the second motor (5).

6. The explosion-proof cooling device for underground coal mines according to claim 5, characterized in that: The compressor liquid spray cooling pipeline (28), the compressor oil supply pipeline (36), and the oil separation output pipeline (24) are all installed with welded straight-through stop valves (20), and the compressor suction pipeline (33) is installed with a welded stop check valve (34).

7. The explosion-proof cooling device for underground coal mines according to claim 6, characterized in that: The frame (13) is provided with three pressure gauges (16) on one side of the programmable control box (15), which are an oil pressure gauge installed on the compressor oil supply pipeline (36), a low pressure gauge installed on the compressor suction pipeline (33), and a high pressure gauge installed on the compressor exhaust pipeline (21).

8. The explosion-proof cooling device for underground coal mines according to claim 7, characterized in that: The oil separator (8) is provided with a safety valve (35). The bottom of the oil separator (8) is connected to the compressor oil supply pipeline (36), and the top is connected to the compressor exhaust pipeline (21). The twin-screw compressor (1) is externally connected to a liquid spray cooling system (40) via a compressor liquid spray cooling pipeline (28), and the shell and tube evaporator (7) is provided with an evaporator liquid supply pipeline (32) connected to the liquid spray cooling system (40).

9. The explosion-proof cooling device for underground coal mines according to claim 8, characterized in that: The twin-screw compressor (1) is equipped with a four-stage capacity control system or a stepless capacity control system. The stepless capacity control system has a capacity adjustment range of 25%-100%. The four-stage capacity control system loads the capacity in the order of 25%-50%-75%-100% through three mining-use casting solenoid valves (17), and then unloads the capacity in the order of 100%-75%-50%-25%.

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