Intelligent maintenance system and maintenance method for low-pressure air compressor in hydropower station

Abstract

The present invention provides an intelligent maintenance system for low-pressure air compressors in a hydropower station. The system comprises two low-pressure air compressors, an air tank connected to the air compressor exhaust ports, and a control system. The system also includes an oil-water mixing sensor, a pressure sensor, and an intelligent valve. The oil-water mixing sensor is located in the lower middle portion of the low-pressure air compressor's oil tank; the pressure sensor is located inside the air tank; and the intelligent valve is a two-position, three-way control valve that connects the exhaust port, the air tank, and the atmosphere. The low-pressure air compressor, the pressure sensor, the oil-water mixing sensor, and the intelligent valve are each connected to the control system. The system can detect the water content in the low-pressure air compressor's oil tank in real time and dry the oil in the two low-pressure air compressors separately at different time intervals to ensure the normal operation of the low-pressure air compressors.

Description

Technical Field

[0001] The present invention relates to the field of air compressors, and in particular to an intelligent maintenance system and maintenance method for low-pressure air compressors. Background Art

[0002] The low-pressure gas system is a crucial component of a hydropower station. The production process typically consists of an air compressor, gas storage tanks, and related piping. Low-pressure gas is commonly used for unit braking, spindle and ball valve overhaul seals, phase adjustment, water pressure, antifreeze blowdown, and maintenance and cleaning. Therefore, as a crucial auxiliary equipment, the low-pressure gas generator directly impacts the safe and reliable operation of the power station.

[0003] Screw compressors rotate the male and female rotors in their cylinders, causing the air between the teeth to periodically change, drawing in and mixing the compressor oil and air, compressing and then exhausting them. Due to their high efficiency, high gas production, and stable operation, these devices are often used as low-pressure air compressors in hydropower stations' low-pressure gas systems, often in a dual-use backup configuration. Under normal operation, the two compressors alternate in operation. If one compressor fails, the controller controls the system to operate solely on the functioning compressor.

[0004] Currently, hydropower stations are generally located in locations with abundant rainfall and water resources. The air is humid and contains high amounts of water. To conserve building space and maintain a rational layout, above-ground powerhouses typically house generators and their control systems on the upper floors, while the air compressor room is typically located in the basement, where moisture easily accumulates due to its density. During idle operation, a hydropower station requires a stable low-pressure air system. Air compressors are required to quickly replenish the system pressure when the air pressure drops. The pressure difference between starting and stopping the air compressor is minimal, typically around 0.06-0.1 MPa. Low-pressure air compressor operating conditions are characterized by high moisture content, short single-cycle operation times, and low operating temperatures. The moisture in the air mixes thoroughly with the oil in the compression stage, dispersing it evenly in the oil as tiny droplets. The higher system temperature prevents the moisture from evaporating from the oil. After the exhaust phase, the moisture passes through the oil-gas separator and returns to the compressor and oil tank, resulting in a white, translucent, oil-water mixture.

[0005] Water in air compressor oil brings many risks:

[0006] 1. Changes in oil viscosity reduce lubrication effectiveness. This makes it difficult to form a qualified oil film between the rotating parts of the screw compressor, reducing the gas sealing effect and the mechanical efficiency of the compressor. Rotating parts are at risk of friction and vibration, and resonance can cause equipment damage.

[0007] 2. When the air compressor oil contains water, the heat dissipation effect is reduced. For every 1 degree Celsius increase in the compressed gas temperature, the effective working volume of the air compressor will decrease by 3%.

[0008] 3. It will accelerate the aging of the oil and react with the additives in the oil, causing the oil to oxidize and deteriorate, and no longer meet the performance requirements.

[0009] 4. Water will cause rust and corrosion of the important compressor parts of the air compressor that are in contact with the air compressor oil, and damage the metal sealing structure and rotating parts. And it can only be treated by replacing the core components.

[0010] When the oil deteriorates due to emulsification, the compressor oil must be replaced with new oil. Under the current operating conditions of the hydropower station, the air compressor oil should be completely replaced every three to six months, and the compressor rotor should be disassembled and cleaned and inspected as appropriate. Air compressor oil, especially screw compressor oil, cannot be replaced with ordinary lubricants due to its high cost. The compressor is the core component of the air compressor and is expensive. The male and female rotors of screw compressors use a special thread linear processing method, which requires processing on specialized machine tools, often imported equipment. Replacing a damaged compressor is costly and expensive.

[0011] In view of this, this application is hereby filed. Summary of the Invention

[0012] The first object of the present invention is to provide an intelligent maintenance system for low-pressure air compressors in a hydropower station. The system is equipped with a water content detection device, an oil drying and impurity removal system, and an intelligent control valve for two low-pressure air compressors, so that the system can detect the water content in the low-pressure air compressor oil tank in real time and dry the oil in the two low-pressure air compressors separately in time periods to ensure the normal operation of the low-pressure air compressors.

[0013] The second purpose of the present invention is to provide an intelligent maintenance method for low-pressure air compressors in hydropower stations. This method uses a control system to scientifically and rationally control two low-pressure air compressors, a water detection device, an oil drying system, and an intelligent control valve, thereby realizing water removal maintenance under a wide range of operating modes in which a single system serves as a backup for the two air compressors. A single system serves the two air compressors and utilizes the air compressor's own system for maintenance, so the system equipment is small in size and has a high utilization rate.

[0014] The embodiment of the present invention is achieved as follows:

[0015] An embodiment of the present invention provides an intelligent maintenance system for low-pressure air compressors in a hydropower station, comprising two low-pressure air compressors, an air storage tank connected to the air compressor exhaust port, and a control system. The system also comprises an oil-water mixing sensor, a pressure sensor, and an intelligent valve. The oil-water mixing sensor is located in the lower middle part of the oil tank of the low-pressure air compressor; the pressure sensor is arranged inside the air storage tank; the intelligent valve is a two-position three-way control valve, which is respectively connected to the exhaust port, the air storage tank, and the atmosphere; the low-pressure air compressor, the pressure sensor, the oil-water mixing sensor, and the intelligent valve are respectively connected to the control system.

[0016] Furthermore, it also includes a vacuum drying system, which includes an oil inlet pipe and an oil outlet pipe. The low-pressure air compressor includes an oil filling port and an oil drain port. The oil outlet pipe is respectively connected to the oil filling ports of the two low-pressure air compressors, and the oil inlet pipe is respectively connected to the oil tank drain ports of the two low-pressure air compressors; it also includes an oil inlet control valve arranged on the oil inlet pipe and an oil outlet control valve arranged on the oil outlet pipe; the oil inlet control valve and the oil outlet control valve are respectively electrically connected to the control system, and the oil inlet control valve and the oil outlet control valve are both two-position three-way control valves.

[0017] Furthermore, the vacuum drying system also includes a vacuum drying tank, a condensing tank, a vacuum pump, and a drainage pump connected by pipelines. The oil inlet pipe is connected to the vacuum drying tank, and the oil outlet pipe is arranged at the bottom of the vacuum drying tank, and the oil outlet pipe is connected to the vacuum pump; it also includes a vacuum solenoid valve group, which is arranged between the vacuum drying tank and the condensing tank, and the vacuum battery valve group is electrically connected to the control system.

[0018] Furthermore, a constant temperature heating element is provided between the oil inlet control valve and the vacuum drying tank, and the constant temperature heating element is electrically connected to the control system.

[0019] Furthermore, the vacuum drying system also includes a defoaming net and a rotary atomizing sprayer. The defoaming net and the rotary atomizing sprayer are arranged on the upper part of the vacuum drying tank, and the rotary atomizing sprayer is connected to the oil inlet pipe.

[0020] Furthermore, the control system includes a drive system, a control power supply and a controller; it also includes a touch screen connected to the controller via an RS485 bus; the drive system includes relays, contactors, intermediate relays and a power supply.

[0021] Furthermore, the controller also includes a manual control panel, on which are provided a plurality of manual control switches corresponding to the vacuum pump, drainage pump, intelligent control valve, oil inlet control valve, oil outlet control valve, vacuum solenoid valve group, and constant temperature heating element.

[0022] An embodiment of the present invention also provides a maintenance method for an intelligent maintenance system for a low-pressure air compressor in a hydropower station. The method uses an intelligent maintenance system for a low-pressure air compressor in a hydropower station provided by an embodiment of the present invention. The method includes a no-load operation and water removal mode for the low-pressure air compressor. The no-load operation and water removal mode includes: ① When the oil-water mixing sensor of one of the low-pressure air compressors sends a water content exceeding standard signal to the controller, the controller switches the low-pressure air compressor to maintenance mode and switches the other air compressor to the main air compressor; ② The control system controls the intelligent valve to connect the exhaust port of the low-pressure air compressor in maintenance mode to the atmosphere, and the low-pressure air compressor runs at no load, and sets the running time; ③ After the no-load running time ends, the controller determines that the water content meets the requirements through the oil-water mixing sensor, and the controller controls the no-load running low-pressure air compressor to switch to standby mode; ④ When the oil-water mixing sensors of the two low-pressure air compressors simultaneously transmit a water content exceeding standard signal to the controller, the controller controls the air compressor with the larger water content to enter the maintenance mode.

[0023] Furthermore, the method also includes a vacuum drying mode, which includes: ① when the oil-water mixing sensor of one of the low-pressure air compressors sends a water content exceeding the standard signal to the controller, the controller switches the low-pressure air compressor to maintenance mode and switches the other air compressor to the main air compressor; ② the controller controls the vacuum pump to start, a vacuum is generated in the vacuum drying tank and the condenser, and the oil inlet control valve is controlled to open, and the oil in the oil tank of the low-pressure air compressor entering the maintenance mode is discharged into the vacuum drying tank for drying and dehydration, and then pumped back to the oil tank after dehydration; ③ after the drying and dehydration is completed, the controller determines that the water content meets the requirements through the oil-water mixing sensor, and the controller controls the low-pressure air compressor in the maintenance mode to switch to the standby mode; ④ when the oil-water mixing sensors of the two low-pressure air compressors simultaneously transmit a water content exceeding the standard signal to the controller, the controller controls the air compressor with the larger water content to enter the maintenance mode.

[0024] Furthermore, the method further includes the controller controlling the constant temperature heating element to turn on, the constant temperature heating element and the oil inlet control valve being turned on simultaneously, and the temperature range of the constant temperature heating element being 55° C.-75° C.

[0025] Based on the above solution, the beneficial effects of the embodiments of the present invention are:

[0026] 1. The oil-water mixing sensor can be used to determine whether there is water in the air compressor oil tank. This eliminates the need for regular manual inspection and maintenance, saving manpower and improving the system's sensitivity to water in the air compressor oil tank.

[0027] 2. It improves the unreasonable operation mode of low-pressure air compressors in hydropower stations. By running the air compressor in no-load mode, the system temperature is increased. At this time, the air compressor oil circuit circulates through the air compressor components and various oil filters. The high temperature can help effectively remove particulate impurities and moisture in the air compressor system and operating oil.

[0028] 3. Use a vacuum drying system for air compressor oil. The heated, atomized, and water-containing oil vapor is passed through a vacuum environment, rapidly evaporating the water and draining it through a drain pump. This method is a mature technology with high drying efficiency, effectively preventing oil emulsification and water accumulation in the air compressor.

[0029] 4. Through the control system, the maintenance and operation status of the two air compressors are automatically switched, and the entire maintenance process is fully automated in control and operation.

[0030] 5. The maintenance working conditions can be set through the human-computer interaction interface of the touch panel to achieve regular maintenance or intelligent maintenance.

[0031] 6. By setting up multiple manual control switches on the manual control panel, it can effectively ensure timely manual intervention in the event of automatic control failure, thereby ensuring the stable operation of the system.

[0032] 7. A single system can realize water removal maintenance under a wide range of operating modes where two air compressors serve as backup for each other. A single system serves two air compressors and utilizes the air compressor's own system for maintenance, so the system equipment is small in size and has a high utilization rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0034] Figure 1 It is a schematic diagram of the structure of the present invention;

[0035] Figure 2 Schematic diagram of the controller structure;

[0036] Figure 3 This is a structural diagram of the manual control panel of the present invention;

[0037] Figure numerals: 1-control system, 2-oil inlet control valve, 3-oil outlet control valve, 4-constant temperature heating element, 5-rotary atomizing sprayer, 6-foam removal net 7-vacuum pump, 8-drain pump, 9-vacuum solenoid valve group, 10-vacuum drying tank, 11-condensation tank 12-intelligent valve 13-oil mixing sensor, 14-touch screen, 15-drive system, 16-manual control panel, 17-manual control switch, 18-maintenance system control mode switch, 19-controller,. DETAILED DESCRIPTION

[0038] The present invention will be further described in detail below with reference to the embodiments, but the present invention is not limited to the following:

[0039] Example 1

[0040] This embodiment aims to solve the problem that the water in the oil tank of the low-pressure air compressor affects the normal operation of the air compressor. It provides an automatic intelligent maintenance system for the low-pressure air compressor (screw type) of a hydropower station. The system controls the air compressor to run at no load through the control system. The oil in the oil tank flows according to the normal oil circuit. The temperature of the equipment rises during the operation of the air compressor, and the water in the oil tank can be removed. The specific structure is as follows Figures 1 to 3 As shown,

[0041] It includes two screw air compressors in a standby mode, a control system 1, an oil-water mixing sensor 13, a vacuum drying system and an intelligent valve 12;

[0042] The intelligent valve 12 is a two-position, three-way controllable solenoid valve, which is connected to the exhaust port of a single air compressor, the air storage tank, and the external environment through pipelines. By switching the internal passage of the solenoid valve, the exhaust port of the air compressor can be connected to the atmosphere, or the exhaust port of the air compressor can be connected to the air storage tank, allowing the air compressor to achieve no-load or loaded operation state;

[0043] The oil-water mixture sensor 13 is placed at the lower part of the air compressor oil tank by drilling a threaded hole. This sensor has high accuracy and converts the percentage of water content in the air compressor oil in the tank into an analog signal (4-20mA current) by changing the dielectric constant of the oil-water mixture liquid, which is then transmitted to the control system 1.

[0044] The control system 1 includes a controller 19 and a drive system 15. The drive system 15 contains multiple relays and contactors, and is equipped with AC and DC power supplies to power the controller power switching device, the relays, contactors, and valve group controls in the drive system 15; the input end of the controller 19 also uses the RS485 bus to set parameters and monitor the two air compressors, and connect the oil inlet control valve 2, the oil outlet control valve 3, and the smart valve 12; at the same time, the controller 19 is also connected to the touch screen 14 via the RS485 bus.

[0045] The control system 1 also includes a manual control panel 16 and a maintenance system control mode switch 18. The manual control panel 16 has multiple manual control switches 17. By manually controlling the contactors and relays in the drive system 15, manual control of the oil inlet control valve 2, the oil outlet control valve 3, and the smart valve 12 is achieved.

[0046] The maintenance system control mode switch 18 switches the control system 1 between automatic, manual maintenance mode, and exit.

[0047] When the control mode of control system 1 is automatic and both air compressors are in normal condition, control system 1 automatically completes the automatic rotation of the two air compressors between the main and standby modes. At this time, control system 1 starts and stops the main and standby air compressors according to the judgment of the pressure sensor of the pressure air storage tank to maintain the system pressure of the air storage tank.

[0048] When the control mode of control system 1 is automatic and the water content of the lubricating oil of one air compressor exceeds the standard, the controller will automatically switch the air compressor with excessive water content to maintenance mode, and the controller will switch the other air compressor to the main air compressor. The controller will start and stop the air compressor according to the judgment of the pressure sensor of the pressure storage tank to maintain the system pressure of the air storage tank.

[0049] Maintenance mode working process: Taking air compressor No. 1 as an example, the operation mode of the intelligent maintenance system;

[0050] First, use the touch screen 14 to set the water content value W0 (default 2%) for maintenance startup and set the idle time T0 (default 1200s).

[0051] ① Operation in load maintenance mode: Maintenance mode switch 16 is in automatic mode position,

[0052] 1) When the signal of the low-pressure air compressor oil-water mixing sensor 13 is transmitted to the PLC analog signal (4-20mA) and the conversion value W1>W0, the controller 19 determines that the No. 1 air compressor needs maintenance; the controller 19 interacts with the No. 1 air compressor: when the No. 1 air compressor is in standby mode, the No. 1 air compressor exits the mutual standby mode, and the low-pressure gas system switches to the independent operation of the No. 2 air compressor; the No. 1 air compressor is started and enters the no-load operation mode: the control system 1 controls the intelligent valve 12 to switch to the maintenance state, and the No. 1 air compressor outlet is connected to the external environment and is in the no-load operation mode; the No. 1 air compressor oil circulates in the No. 1 air compressor, the air compression system temperature rises, and the No. 1 air compressor oil is filtered in the oil circulation filter element and the oil-gas filter element to remove impurities in the oil and discharge the water-containing waste gas;

[0053] Stop in no-load maintenance mode: Air compressor No. 1 stops after maintaining no-load time T0. The controller 19 continues to determine the water content value W1 through the oil-water mixing sensor 13. If W1>2%, the system switches to "vacuum drying mode"; if W1≤0.1%, air compressor No. 1 exits maintenance mode and returns to the automatic operation state of mutual backup.

[0054] If the water content of air compressor No. II is W2>W0, the maintenance system execution method is basically the same as that of air compressor No. I, the difference is that the action positions of oil inlet control valve 2 and oil outlet control valve 3 are opposite.

[0055] 2) If both water content W1 and W2 are greater than WO, the compressor with the greater water content enters maintenance mode first. After maintenance is complete, the other compressor enters maintenance mode. Both compressors will not enter maintenance mode simultaneously to ensure that at least one low-pressure compressor in the low-pressure gas system is operating normally.

[0056] 3) Manual maintenance mode: Switch the maintenance mode switch 16 to manual mode, and operate the corresponding solenoid valve switch and oil pump power supply on the manual control switch 17 according to the automatic process mode.

[0057] Example 2

[0058] This embodiment aims to address the situation where water in the oil tank of a low-pressure air compressor affects the normal operation of the air compressor, and provides an automatic intelligent maintenance system for a low-pressure air compressor (screw type) in a hydropower station. Compared with embodiment 1 of this system, a vacuum drying system is added. Therefore, when solving the technical problem of water in the oil tank, a vacuum drying mode is also added. The vacuum drying mode can operate independently to remove moisture from the oil tank of the air compressor, and can also be used in conjunction with the no-load operation mode to solve the technical problem that the air compressor has not been oil-dried for a long time, there is too much water in the oil tank, and the system cannot completely dry the moisture in the oil tank using the no-load operation mode, thereby improving the drying and impurity removal function of the system. This embodiment is a method for drying and impurity removal in conjunction with the vacuum drying mode and the no-load operation mode. The specific structure is as follows: Figure 1 arrive Figure 3 As shown:

[0059] It includes two screw air compressors in a standby mode, a control system 1, an oil-water mixing sensor 13, a vacuum drying system and an intelligent valve 12;

[0060] The intelligent valve 12 is a two-position, three-way controllable solenoid valve, which is connected to the exhaust port of a single air compressor, the gas storage tank, and the external environment through pipelines. By switching the internal passage of the solenoid valve, the air compressor outlet is connected to the external environment, or the air compressor outlet is connected to the low-pressure gas tank, allowing the air compressor to achieve no-load or loaded operation state;

[0061] The oil-water mixture sensor 13 is placed in the air compressor oil tank by drilling a threaded hole. This sensor has high accuracy and converts the percentage of water content in the air compressor oil in the tank into an analog signal (4-20mA current) based on the change in the dielectric constant of the oil-water mixture liquid, which is then transmitted to the control system 1.

[0062] The vacuum oil filtration system mainly consists of an oil inlet control valve 2, an oil outlet control valve 3, a constant temperature heating element 4, a rotary atomizing sprayer 5, a defoaming net 6, a vacuum pump 7, a drainage pump 8, a vacuum solenoid valve group 9, a vacuum drying tank 10, and a condensation tank 11;

[0063] The oil inlet control valve 2 is a two-position, three-way controllable solenoid valve. The inlet of the valve is connected to the oil outlet of the two air compressors via a pipeline, and the outlet of the valve is connected to the constant temperature heating element 4. By switching the internal passage of the solenoid valve, the operating oil of one of the air compressors I and II can be controlled to enter the vacuum drying tank 10. The valve is controlled by the control system 1 through the drive system 15.

[0064] The constant temperature heating element 4 is located between the oil inlet control valve 2 and the vacuum drying tank 10 and is connected by a pipeline. The heating element is mainly composed of a constant temperature heating plate, which can heat the water-containing air compressor oil at a constant temperature set between 55 and 75°C. The temperature is controlled by an internal contact thermal control element to prevent the oil from vaporizing due to excessive temperature or causing a fire risk.

[0065] The vacuum drying tank 10 is a cylindrical steel tank. A rotary atomizing sprayer 5 is located above the interior of the tank and connected to the four heating elements via pipelines. The heated oil-water mixture is sprayed into a very fine liquid mist through the high-speed rotation of the sprayer and the shrinking outlet of the sprayer. This mist is sprayed into the vacuum drying tank 10, evaporating the water. A multi-layered defoaming screen 6 is installed at the top of the vacuum drying tank 10. This multi-layered metal mesh structure separates the oil and water vapor, causing the oil mist to drip into the bottom of the drying tank. The bottom of the vacuum drying tank 10 is interconnected to a vacuum pump 7 via pipelines. The vacuum pump 7 is a gear pump that pumps the air compressor oil in the vacuum drying tank 10 into the air compressor oil tank. The top of the vacuum drying tank 10 is also connected to the condenser tank 11 via pipelines. A liquid level switch in the tank is connected to the controller 19.

[0066] The vacuum pump 7 is connected to air compressors I and II through a pipeline and is equipped with a one-way check valve. The oil circuit is controlled by the oil outlet control valve 3. The oil outlet control valve 3 is a two-position three-way solenoid valve. By switching the internal passage of the solenoid valve, it can control the selection of dried operating oil to enter the oil tank of one of the air compressors I and II. The valve is controlled by the control system 1 through the drive system 15.

[0067] The condensation tank 11 is a cylindrical steel tank with a condenser provided in the tank. The lower right side of the tank body is connected to the drainage pump 8 through a pipeline. The drainage pump is a Roots vacuum pump, which can generate vacuum by suction, compression and exhaust, and allow the water vapor at the top of the vacuum drying tank 10 to enter the condensation tank 11. The lower end of the condensation tank 11 is a drain valve, which can discharge the accumulated water after condensation.

[0068] The connecting pipeline between the vacuum drying tank 10 and the condensing tank 11 is provided with a vacuum solenoid valve group 9, which consists of a solenoid valve and two vacuum relays. The vacuum degrees of the two vacuum relays can be set to -0.07MPa and -0.09MPa respectively. By sending a node signal to the control system 1, the vacuum drying tank 10 and the condensing tank 11 are maintained at a vacuum degree of -0.07MPa to -0.09MPa.

[0069] The control system 1 includes a controller 19 and a drive system 15. The drive system 15 contains multiple relays and contactors, and is equipped with AC and DC power supplies to supply power to the controller power switching device, the relays, contactors, and valve group controls in the drive system 15; the control system 1 controls the intermediate relay in the drive system 15, and the intermediate relay is connected to the auxiliary node of the contactor, thereby realizing the controller 19's control of the vacuum pump 7 and the drainage pump 8; the input end of the controller 19 also uses the RS485 bus to set parameters and monitor the two air compressors, and connect the oil inlet control valve 2, the oil outlet control valve 3, the vacuum solenoid valve group 9, and the smart valve 12; at the same time, the controller 19 is also connected to the touch screen 14 via the RS485 bus.

[0070] The control system 1 also includes a manual control panel 16 and a maintenance system control mode switch 18. The manual control panel 16 has multiple manual control switches 17. By manually controlling the contactors and relays in the drive system 15, manual control of the oil inlet control valve 2, the oil outlet control valve 3, the vacuum solenoid valve group 9, the smart valve 12, the vacuum pump 7, and the drain pump 8 can be achieved.

[0071] The maintenance system control mode switch 18 can switch the control system 1 between automatic and manual maintenance modes and exit.

[0072] When the control mode of control system 1 is automatic and both air compressors are in normal condition, control system 1 automatically completes the automatic rotation of the two air compressors between the main and standby modes. At this time, control system 1 starts and stops the main and standby air compressors according to the judgment of the pressure sensor of the pressure air storage tank to maintain the system pressure of the air storage tank.

[0073] When the control mode of control system 1 is automatic and the water content of the lubricating oil of one air compressor exceeds the standard, control system 1 will automatically switch the air compressor with excessive water content to maintenance mode, and the controller will switch the other air compressor to the main air compressor. The controller will start and stop the air compressor according to the judgment of the pressure sensor of the pressure storage tank to maintain the system pressure of the air storage tank.

[0074] Maintenance mode working process: Taking air compressor No. 1 as an example, the operation mode of the intelligent maintenance system;

[0075] First, use the touch screen 14 to set the water content value W0 (default 2%) for maintenance startup and set the idle time T0 (default 1200s).

[0076] ① Operation in load maintenance mode: Maintenance mode switch 16 is in automatic mode position,

[0077] When the signal transmission of the oil-water mixing sensor 13 in air compressor No. 1 is input to the PLC analog signal (4-20mA) and the conversion value W1>W0, the controller 19 determines that air compressor No. 1 needs maintenance; the controller 19 interacts with air compressor No. 1: when air compressor No. 1 is in standby state, air compressor No. 1 exits the mutual standby mode, and the low-pressure gas system switches to independent operation of air compressor No. II; air compressor No. 1 is started, and air compressor No. 1 enters the no-load operation mode: the control system 1 controls the intelligent valve 12 to switch to the maintenance state, and the outlet of air compressor No. 1 is connected to the external environment and is in no-load operation mode; the oil of air compressor No. 1 circulates in air compressor No. 1, the temperature of the air compression system rises, and the oil circulation filter element and the oil-gas filter element inside the air compressor No. 1 are filtered to remove impurities in the oil and discharge the water-containing waste gas;

[0078] Stop in no-load maintenance mode: Air compressor No. 1 stops after maintaining no-load time T0. The controller 19 continues to determine the water content value W1 through the oil-water mixture sensor 13. If W1>2%, the system switches to "vacuum drying mode"; if W1≤0.1%, air compressor No. 1 exits maintenance mode and returns to the automatic operation state of mutual backup.

[0079] ② Vacuum drying mode operation: the control system 1 controls the vacuum pump 7 to start through the drive system 15, and the vacuum drying tank 10 and the condensation tank 11 generate vacuum;

[0080] When the vacuum relay in the vacuum solenoid valve group 9 determines that the vacuum degree of the vacuum drying system has not reached -0.07MPa, the system will not operate;

[0081] When the vacuum relay in the vacuum solenoid valve group 9 determines that the vacuum reaches -0.07MPa, the signal is transmitted to the control system 1, and the control system 1 controls the oil inlet control valve 2 to switch, and the No. 1 air compressor is connected to the vacuum drying system. The air compressor oil is sucked into the vacuum drying system, and the water-containing No. 1 air compressor oil passes through the constant temperature heating element 4 (not exceeding 75°C) and is sprayed into the vacuum drying tank 10 through the rotary atomizing sprayer 5. The water in the oil evaporates rapidly in the heating and vacuum environment. When the oil mist reaches the defoaming net 6, it passes through the multi-layer metal The mesh structure separates the oil and water vapor, causing the oil mist to drip into the bottom of the drying tank. The water is then sucked into the condensation tank 11 and condensed into water, which accumulates below the tank. When the oil level in the vacuum drying tank 10 reaches the upper limit of the liquid level switch, the oil level switch activates and sends a signal. The control system 1 controls the vacuum pump 7 to start, and the oil outlet valve control valve 3 switches, pumping the clean oil at the bottom of the vacuum drying tank 10 into the air compressor oil tank. When the oil level in the vacuum drying tank 10 reaches the upper limit of the liquid level switch, the control system 1 stops the vacuum pump 7 via the drive system 15.

[0082] When the vacuum relay in the vacuum solenoid valve group 9 determines that the vacuum reaches -0.09 MPa, it transmits a signal to the control system 1, which controls the vacuum solenoid valve group 9 to close and the drainage pump 8 to stop. When the system vacuum is less than -0.09 MPa, the control system 1 controls the vacuum solenoid valve group 9 to start. The above process is continuously executed during operation.

[0083] ③ Vacuum drying mode stops: When the vacuum system runs for 2 hours,

[0084] (1) When the control system 1 determines that the oil-water mixture sensor 13W1 is ≤ 0.1%, or when the vacuum system operation time reaches 12 hours, the vacuum drying is stopped: the control system 1 controls the drainage pump 8 to stop, and starts the vacuum pump 7 to drain the oil in the vacuum drying tank 10 to the lower limit of the liquid level switch;

[0085] If the water content W2 of compressor II is greater than W0, the maintenance system is executed in the same manner as for compressor I, except that the operating positions of oil inlet control valve 2 and oil outlet control valve 3 are reversed. The oil tank of compressor II is connected to the vacuum drying system.

[0086] 4) If both water content W1 and W2 are greater than WO, the compressor with the greater water content enters maintenance mode first. After maintenance is complete, the other compressor enters maintenance mode. Both compressors will not enter maintenance mode simultaneously to ensure that at least one low-pressure compressor in the low-pressure gas system is operating normally.

[0087] 5) Manual maintenance mode: Switch the maintenance mode switch 16 to manual mode, and operate the corresponding solenoid valve switch and oil pump power supply on the manual control switch 17 according to the automatic process mode.

[0088] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A maintenance method for an intelligent maintenance system of a low-pressure air compressor in a hydropower station, characterized in that: It includes a no-load operation and water removal mode for the low-pressure air compressor, and the no-load operation and water removal mode includes: ① When the oil-water mixing sensor of one of the low-pressure air compressors sends a water content exceeding the standard signal to the controller, the controller switches the low-pressure air compressor to maintenance mode and switches the other air compressor to the main air compressor, and the oil-water mixing sensor is located in the lower middle part of the oil tank of the low-pressure air compressor; ② The control system controls the intelligent valve to connect the exhaust port of the low-pressure air compressor in maintenance mode to the atmosphere, and the low-pressure air compressor runs at no load, and sets the running time; ③ After the no-load running time ends, the controller determines that the water content meets the requirements through the oil-water mixing sensor, and the controller controls the no-load running low-pressure air compressor to switch to standby mode; ④ When the oil-water mixing sensors of the two low-pressure air compressors simultaneously transmit a water content exceeding the standard signal to the controller, the controller controls the air compressor with the larger water content to enter the maintenance mode.

2. The maintenance method of the intelligent maintenance system for low-pressure air compressors in hydropower stations according to claim 1 is characterized in that Including vacuum drying mode, the vacuum drying mode includes: ① When the oil-water mixing sensor of one of the low-pressure air compressors sends a water content exceeding the standard signal to the controller, the controller switches the low-pressure air compressor to maintenance mode and switches the other air compressor to the main air compressor; ② The controller controls the vacuum pump to start, generates vacuum in the vacuum drying tank and the condenser, and controls the oil inlet control valve to open, and discharges the oil in the oil tank of the low-pressure air compressor entering the maintenance mode into the vacuum drying tank for drying and dehydration, and pumps it back to the oil tank after dehydration; ③ After drying and dehydration, the controller determines that the water content meets the requirements through the oil-water mixing sensor, and the controller controls the low-pressure air compressor in maintenance mode to switch to standby mode; ④ When the oil-water mixing sensors of the two low-pressure air compressors simultaneously transmit water content exceeding the standard signal to the controller, the controller controls the air compressor with the larger water content to enter maintenance mode.

3. The maintenance method of the intelligent maintenance system for low-pressure air compressors in hydropower stations according to claim 2 is characterized in that It also includes a controller that controls the constant temperature heating element to open, the constant temperature heating element and the oil inlet control valve are opened at the same time, and the temperature range of the constant temperature heating element is 45℃-75℃.

4. An intelligent maintenance system for low-pressure air compressors in a hydropower station, using the maintenance method according to any one of claims 1 to 3, comprising two low-pressure air compressors, an air storage tank connected to the exhaust ports of the low-pressure air compressors, and a control system, characterized in that It also includes an oil-water mixing sensor, a pressure sensor, and an intelligent valve. The oil-water mixing sensor is located in the lower middle part of the oil tank of the low-pressure air compressor; the pressure sensor is arranged inside the air storage tank; the intelligent valve is a two-position three-way control valve, and the intelligent valve is respectively connected to the exhaust port, the air storage tank and the atmosphere; the low-pressure air compressor, the pressure sensor, the oil-water mixing sensor, and the intelligent valve are respectively connected to the control system.

5. The intelligent maintenance system for low-pressure air compressors in hydropower stations according to claim 4 is characterized in that: It also includes a vacuum drying system, which includes an oil inlet pipe and an oil outlet pipe. The low-pressure air compressor includes an oil filling port and an oil drain port. The oil outlet pipe is respectively connected to the oil filling ports of the two low-pressure air compressors, and the oil inlet pipe is respectively connected to the oil drain ports of the oil tanks of the two low-pressure air compressors; it also includes an oil inlet control valve arranged on the oil inlet pipe and an oil outlet control valve arranged on the oil outlet pipe; the oil inlet control valve and the oil outlet control valve are respectively electrically connected to the control system, and the oil inlet control valve and the oil outlet control valve are both two-position three-way control valves.

6. The intelligent maintenance system for low-pressure air compressors in hydropower stations according to claim 5, characterized in that: The vacuum drying system further includes a vacuum drying tank, a condensing tank, a vacuum pump, and a drainage pump connected by pipelines. The oil inlet pipe is connected to the vacuum drying tank. The oil outlet pipe is arranged at the bottom of the vacuum drying tank and is connected to the vacuum pump. The vacuum drying system also includes a vacuum solenoid valve group, which is arranged between the vacuum drying tank and the condensing tank and is electrically connected to the control system.

7. The intelligent maintenance system for low-pressure air compressors in hydropower stations according to claim 6, characterized in that: A constant temperature heating element is provided between the oil inlet control valve and the vacuum drying tank, and the constant temperature heating element is electrically connected to the control system.

8. The intelligent maintenance system for low-pressure air compressors in hydropower stations according to claim 6, characterized in that: The vacuum drying system further comprises a defoaming net and a rotary atomizing sprayer, wherein the defoaming net and the rotary atomizing sprayer are arranged on the upper part of the vacuum drying tank, and the rotary atomizing sprayer is connected to the oil inlet pipe.

9. The intelligent maintenance system for low-pressure air compressors in hydropower stations according to any one of claims 4 to 8, characterized in that: The control system includes a drive system, a control power supply and a controller; it also includes a touch screen connected to the controller via an RS485 bus; the drive system includes a relay, a contactor, an intermediate relay and a power supply.

10. The intelligent maintenance system for low-pressure air compressors in a hydropower station according to claim 7, characterized in that: The controller also includes a manual control panel, on which are provided a plurality of manual control switches corresponding to the vacuum pump, the drainage pump, the oil inlet control valve, the oil outlet control valve, the vacuum solenoid valve group, and the constant temperature heating element.

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