Explosion-proof cooling device for underground coal mine

Abstract

The explosion-proof cooling device for the underground coal mine comprises a frame, an air-cooled condenser, a compressor unit, a shell-and-tube evaporator and a base are installed in the frame, 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 coolant compressed gas; the compressor unit is used for compressing a gas refrigerant and comprises an oil separator, a double-screw compressor, a first motor, a double-loop 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 a low-temperature refrigerant. According to the cooling device, a refrigerant used when the cooling device works can be recycled, the investment of resources and cost of the part is reduced, the refrigeration cost is saved, nitrogen in the device can rapidly and continuously release low-temperature nitrogen, the air temperature in a large range of a mining area is efficiently achieved, air is inerted, the oxidation spontaneous combustion rate of coal is reduced, and gas explosion is restrained; the mining area safety is improved.

Description

Technical Field

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

[0002] Coal combustion requires a certain concentration of oxygen and high temperature. If coal is exposed to the air, oxidation will occur and heat will be released. If this heat cannot be diffused out in time, the temperature will continue to rise, eventually leading to combustion or even explosion. Therefore, in idle coal mines, a large amount of nitrogen needs to be introduced to prevent coal mine combustion or explosion. As a dry inert gas, nitrogen is continuously introduced into the coal mining area for the following important purposes: 1. By introducing nitrogen, the oxygen content in the mining area is reduced: nitrogen is introduced to replace air to exchange oxygen with the surface of coal, reduce the oxygen content in the mining area, slow down the oxidation process of coal, reduce the heat released by oxidation, and prevent combustion; 2. Continuously introduce nitrogen, nitrogen will penetrate into the cracks of the coal seam, and a slight positive pressure will be formed in the entire mining area, effectively reducing the air leakage phenomenon in the coal mine and reducing the entry of external air; 3. Make the explosive lose its explosive ability: after nitrogen is introduced into the mining area, it will mix with other flammable and explosive gases in the mining area to reduce the volume of flammable and explosive gases. When the volume of the mixed gas reaches a certain value, the explosion point of the flammable and explosive gas will drop to or below the lower limit.

[0003] Most of the coal mines in my country have poor ventilation conditions and the working surface temperature is greater than 35℃. The high temperature working environment not only significantly reduces work efficiency, but also seriously affects the health of underground workers. However, the existing cooling device structure is relatively simple. For example, blowers and other devices are often used to cool and dissipate heat for mining equipment. The heat conduction capacity of air is low, and the cooling range is small, the use effect is poor, and it cannot meet the use needs in the mining area. For this reason, we provide explosion-proof cooling devices for underground coal mines to solve the above problems. Summary of the invention

[0004] In view of 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 a shell and tube evaporator to achieve the discharge of low-temperature nitrogen, and quickly reduce the temperature of the coal mine goaf. Compared with air heat dissipation, the injection of nitrogen can inertate 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] In order to achieve the above-mentioned object, the explosion-proof cooling device for underground coal mines adopted by the present invention comprises 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, and a programmable control box for controlling the operation of the cooling device is installed at the left end of the frame; 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. The compressor unit is used for compressing 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, wherein the twin-screw compressor is connected to a compressor liquid spray cooling pipeline, and an expansion valve and a sight glass are installed on the pipeline; The shell and tube evaporator is used for heat exchange between high-temperature nitrogen and low-temperature refrigerant, and a nitrogen inlet pipeline and a nitrogen outlet pipeline are respectively provided at both ends; During operation, the coolant is sucked in and compressed to the suction side of the twin-screw compressor, and refrigerant oil is injected into the compression chamber of the twin-screw compressor. The twin-screw compressor compresses the mixed oil coolant and discharges it into the oil separator, separates the refrigerant oil and sends it back to each chamber and each bearing part 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 exchanges heat with normal temperature nitrogen in the shell and tube evaporator. The refrigerant after heat exchange is heated up 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.

[0006] As a further optimization of the above scheme, the air-cooled condenser includes a tube-fin condenser and a cooling fan assembly installed above the tube-fin condenser, a second motor and a fan protection net. The cooling fan assembly is fixed to the upper part of the frame, and the driving end is connected to the output end of the second motor. The fan protection net is installed on the outside of the fan blades of the cooling fan assembly. The second motor and the first motor are both explosion-proof motors for mining.

[0007] As a further optimization of the above solution, a ball valve is installed on the nitrogen outlet pipeline, and the nitrogen inlet pipeline and the nitrogen outlet pipeline both extend to the outside of the frame.

[0008] 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.

[0009] As a further optimization of the above scheme, three normally closed mining-type 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.

[0010] As a further optimization of the above scheme, 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, and 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.

[0011] 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.

[0012] 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.

[0013] 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.

[0014] 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-type casting solenoid valves, and then unload it in the order of 100%-75%-50%-25%.

[0015] The explosion-proof cooling device for underground coal mines of the present invention has the following beneficial effects: 1. The explosion-proof cooling device for underground coal mines of the present invention adopts compressed refrigerant gas circulation 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, make it lose its explosiveness, and achieve the effect of reducing the oxidation and spontaneous combustion of coal in the mining area and inhibiting gas explosion, meeting the use needs in the mining area and improving the safety of work in the mining area.

[0016] 2. The explosion-proof cooling device for underground coal mines of the present invention, when working, the refrigerant goes through the compressor unit, the air-cooled condenser and the shell and tube evaporator and then returns to the compressor unit in a circulation working mode, which not only avoids the impact on the environment during discharge, but also reduces the investment of this part of resources and costs, saves the working cost of the cooling device, and thus reduces the refrigeration cost.

[0017] 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. Rapid and continuous low-temperature nitrogen discharge can quickly reduce the air temperature in a large range of the mining area. The mining environment after cooling is helpful to improve the work efficiency of the staff.

[0018] 4. The explosion-proof cooling device for underground coal mines of the present invention, wherein the arrangement 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.

[0019] With reference to the following description and drawings, a specific embodiment of the present invention is disclosed in detail, indicating the manner in which the principle of the present invention can be adopted. It should be understood that the scope of the embodiment of the present invention is not limited thereby, and the embodiment of the present invention includes many changes, modifications and equivalents. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a front perspective view of the present invention; Figure 2 It is a back perspective view of the present invention; Figure 3 For Figure 1 A top view corresponding to and showing the pipes and accessories; Figure 4 It is a schematic diagram of the position and structure of the air-cooled condenser of the present invention; Figure 5 It is a structural schematic diagram of a fan assembly of the present invention; Figure 6 For Figure 2 Corresponding to and retaining only the top view of the base and main components; Figure 7 is a side view of the present invention; Figure 8 For Figure 2 The corresponding front view; Fig. 9 For Figure 1 The corresponding front view; Fig.10 For Figure 2 The top view of the device after the corresponding air-cooled condenser and condenser protective net are removed; Fig.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%; Fig.12 This is a schematic diagram of the twin-screw compressor in Example 2 when it is operated at 50% load; Fig.13 It is a schematic diagram of the twin-screw compressor in Example 2 when it is operated at 75% load; Fig.14 This is a schematic diagram of the twin-screw compressor in Example 2 when it is running at 100% load; Fig.15 It is a workflow diagram when the present invention is running.

[0021] 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 dryer; 12. Base; 13. Frame; 14. Condenser protection net; 15. Programmable control box; 16. Pressure gauge; 17. Mine-use cast-in solenoid valve; 18. Laminated flexible coupling; 19. Second filter dryer; 20. Welded straight-through stop valve; 21. Compressor exhaust pipeline; 22. Pressure sensor; 23. Temperature sensor; 24. Oil separation output pipeline; 25. Lifting ring; 26. Condenser output pipeline; 27. Liquid storage tank output pipeline; 28. Compressor liquid spray cooling pipeline; 29. ​​Nitrogen outlet pipeline; 30. Sight glass; 31. Expansion valve; 32. Evaporator liquid supply pipeline; 33. Compressor suction pipeline; 34. Welded stop check valve; 35. Safety valve; 36. Compressor oil supply pipeline; 37. Oil filter; 38. Nitrogen inlet pipeline; 39. Ball valve; 40. Liquid spray cooling system. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution 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 explain the present invention and are not intended to limit the scope of the present invention.

[0023] 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.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which the present invention belongs. The terms used in the specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used in this article includes any and all combinations of one or more related listed items.

[0025] Embodiment 1

[0026] 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 data display and control of the start and stop of the device through a program; the frame 13 is installed with three pressure gauges 16 on one side of the programmable control box 15, which are respectively 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.

[0027] Reference Figures 4 to 5The air-cooled condenser 3 is used for heat dissipation and cooling of 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 outer side 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 copper tube of the radiator, 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.

[0028] Reference Figures 1 to 3 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 casting electromagnetic valves 17, and the capacity adjustment range is 25%-100%, and a compressor spray cooling pipeline 28 is provided, on which an expansion valve 31 and a sight glass 30 are installed; the first motor The machine 2 is a flameproof motor for mining. The double-circuit reversible vacuum electromagnetic starter 9 can control the start and stop of the first motor 2 and the second motor 5. It has functions such as overload, phase failure, leakage lockout and short circuit protection. At the same time, there is a liquid crystal display in the observation window of the shell, which is used as a status display of operation, parameters, faults, etc., and a communication interface is reserved to realize remote monitoring; the sight glass 30 is used to display the dryness of the refrigerant: blue = dry, purple = turning wet, red purple = wet; the function of the expansion valve 31 is to continuously supply refrigerant to the shell and tube evaporator 7, and the supplied refrigerant can evaporate at the working temperature. Therefore, it can ensure that the heat exchange surface of the shell and tube evaporator 7 is fully utilized. At the same time, the setting of the expansion valve 31 can ensure that the filling of the shell and tube evaporator 7 can reach the best state even when the cooling capacity is constantly changing, so as to reduce the impact of the refrigerant pressure changing from the original high pressure to low pressure during the expansion process, and it can also ensure that the gas sucked into the twin-screw compressor 1 reaches the correct temperature.

[0029] 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 both ends thereof; 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.

[0030] 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, 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 dry filter 19 are installed on the compressor oil supply pipeline 36, and an oil separation output pipeline 24 is provided on the oil separator 8 of the compressor unit, and is connected to the first dry filter 11 through the pipeline, and the first dry filter 11 is connected to the liquid storage tank 10 through the liquid storage tank output pipeline 27, and the liquid storage tank 10 is connected to the condenser output pipeline 2 6, and 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 liquid 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 the loading and unloading actions of the twin-screw compressor 1 are controlled by oil pressure.

[0031] Reference Fig.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 .

[0032] The mining cooling device in the first embodiment needs to be inspected before use, specifically: 1. Check all parts to ensure that the pipeline connections are reliable, and purge and clean the air-cooled condenser 3.

[0033] 2. Check the forward and reverse rotation of the twin-screw compressor 1 by jogging.

[0034] 3. Leakage inspection: 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 inspection should last at least 24 hours.

[0035] After the inspection, the staff takes safety measures and can then start, run, reset and troubleshoot the equipment by operating the programmable control box 15.

[0036] Working principle of the mining cooling device in Example 1: Reference Fig.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 suction space of the shaft seal through the compressor oil supply pipe 36. The twin-screw compressor 1 compresses the refrigerant mixed with oil and discharges it through 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 each bearing part of the twin-screw compressor 1 through the compressor oil supply pipe 36. The compressed coolant gas after separation is cooled by the air-cooled condenser 3 and becomes a low-temperature liquid refrigerant. The liquid refrigerant is filtered and expanded and evaporated by the expansion valve 31 to become a gas and sent to the shell and tube evaporator 7. The low-temperature refrigerant gas and the high-temperature nitrogen are heat-exchanged in the shell and tube evaporator 7. After the temperature of the refrigerant is increased, it flows out of the shell and tube evaporator 7 and enters the twin-screw compressor 1 through the compressor suction pipeline 33 of the twin-screw compressor 1. The compression and refrigeration work is carried out in this cycle, and the nitrogen after heat exchange becomes low-temperature nitrogen and is discharged from the nitrogen outlet pipeline 29. The pressure and temperature sensors on each low-temperature pipeline detect the pressure and temperature, and the control program protects the compressor and the system to work normally under the predetermined pressure and temperature regulation.

[0037] The low-temperature nitrogen discharged from the nitrogen outlet pipe 29 enters the fire prevention and extinguishing area of ​​the mining area, dilutes the oxygen and other gases in the area, reduces the concentration of combustible gases and the oxygen content, and inertizes 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.

[0038] Embodiment 2

[0039] 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-type casting solenoid valves 17, and then unloads the capacity in the order of 100%-75%-50%-25%.

[0040] Specifically, when the twin-screw compressor 1 operates under the following conditions: suction pressure: >-0.5 bar; exhaust pressure: <18 bar; oil pressure: ≥6 bar; suction temperature <-30.0 °C; discharge temperature: <80 °C, the specific operation steps of loading using the four-stage capacity control system are as follows: a. 25% startup state, see the state diagram Fig.11 ; When the twin-screw compressor 1 is started, 25% of the mining-used 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.

[0041] b. 50% load operation, see the status diagram Fig.12 ; At this time, the 25% solenoid valve is closed, so the lubricating oil is continuously supplied to the hydraulic cylinder. When the control system sends a signal to the 50% mining casting solenoid valve 17 to excite it, the lubricating oil bypasses the 50% mining casting solenoid valve 17 to the low-pressure side, and the volume adjustment piston is maintained at the bypass port position due to the oil bypass. When the volume adjustment slider is at the 50% position, part of the refrigerant returns to the low-pressure side from the bypass circuit, and the compression volume is maintained at 50%.

[0042] c. 75% load operation, see the status diagram Fig.13 ; 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 stops energizing, so no lubricating oil bypasses from 50% to the low-pressure side. At this time, the piston is pushed to the position of the 75% bypass port by the oil that continues to enter the hydraulic cylinder, and the oil bypasses from the 75% mining casting solenoid valve 17 to the low-pressure end. At this time, the slider position is 75%, part of the refrigerant returns to the low-pressure side from the bypass circuit, and the compression volume is maintained at 75%.

[0043] d. 100% load operation, see the status diagram Fig.14 ; 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.

[0044] 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 the capacity control of the twin-screw compressor 1.

[0045] 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.

[0046] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included in the protection scope 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; During operation, 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 to become a low-temperature liquid refrigerant. The liquid refrigerant is filtered and expanded and evaporated by the expansion valve (31) to become a gas and is sent to the shell and tube evaporator (7). The low-temperature gaseous refrigerant exchanges heat with the normal-temperature nitrogen in the shell and tube evaporator (7). The refrigerant after the heat exchange is heated up and flows out to re-enter the twin-screw compressor (1), and the cycle is repeated. The nitrogen after the 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: 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.

7. The explosion-proof cooling device for underground coal mines according to claim 6, 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).

8. The explosion-proof cooling device for underground coal mines according to claim 7, 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).

9. The explosion-proof cooling device for underground coal mines according to claim 8, 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).

10. The explosion-proof cooling device for underground coal mines according to claim 9, 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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