As China's economy continues to develop, screw chillers not only widely used in commercial buildings, is also gradually being most production-oriented enterprise applications, with screw chillers used more widely in the enterprise, but the attendant commissioning, maintenance and maintenance of screw chillers have also become an important aspect of each screw chillers business owners, now briefly screw chillers some debugging, maintenance and maintenance methods:
Preparation before (a) Screw chillers start
Debugging correct screw chillers is to ensure the normal operation of the cooling device, save energy and prolong the life of an important part. For large and medium-sized refrigeration systems on-site installation, prior to commissioning the first design drawings should be familiar with the layout and connection of the system to understand the shape of the structure and components of the performance of each device, and electronic control systems and water supply systems. For this reason, debug should have refrigeration and utilities engineers to participate. Users should carefully read the manufacturer's products provide operating instructions before commissioning, according to operational requirements progressively. The operator must go through specialized training factory, access to the unit's operating certificate to posts it to avoid faulty operation caused by a fatal damage to the unit.
1 . Preparation prior to commissioning
(1) Due to screw chillers belong to the large refrigerator, so the need to design debugging closely with installation, use three aspects. In order to ensure the orderly conduct of commissioning work, it is necessary to temporary commissioning team of the staff concerned, the overall command of debug work.
(2) The person responsible for commissioning should be fully familiar with the structure and performance of screw chillers, familiar refrigerator security technology, specifically debugging methods, procedures and technical requirements to be met to develop a detailed and specific debugging program, and each job commissioning engineers define their tasks and requirements.
Installation (3) Check screw chillers meets the technical requirements, the foundation screw chillers to meet the requirements, the connecting pipe dimensions, specifications, material meets the design requirements.
(4) Units of power supply system should be fully installed by debugging.
(5) separately in cold water and cooling water systems through water tests, flushing water system dirt, water pump should work, the cycle of water conditions in line with requirements.
(6) to clean up the site debugging environment, to clean, bright and smooth.
(7) is ready and commissioning of various generic tools and special tools required.
(8) is ready to debug the desired kinds of pressure, temperature, flow, quality, time and other measuring instruments, meters.
(9) is ready for commissioning safety equipment required during the operation.
2. Screw chillers debugging
(1) of the refrigerant charge. Currently, the refrigeration unit at the factory are generally required to charge the refrigerant, after on-site installation, visual inspection if no damage was found accidentally, can be directly related to the valve open (you should read the manufacturer's instruction manual, in transit, the unit The valve is in the closed state general) commissioning. If you find a refrigerant leak has been completed or not enough, they should first identify the leak and
Exclude leakage, then according to product specification requirements, the addition of provisions grades refrigerants. Note that the amount of refrigerant charge should meet the technical requirements.
(2) Some screw chillers require the user's site filling refrigerant, the refrigerant charge volume and grade must be in accordance with the provisions of the refrigerant. Insufficient refrigerant charge fluence. It will lead to less cold. Refrigerant charge excessive fluence, will not only increase costs, but also for energy consumption, which may adversely affected.
(3) Before charging refrigerant, it should be pre-equipped with enough refrigerant. When filling, can be directly charged from a dedicated filling valve. Because the system is in a vacuum state, the cylinder and refrigerant system pressure is large, when you open the valve (connecting tube should be blown out of the air with the refrigerant, in order to avoid air into the unit, affect unit performance), the refrigerant from the cylinder quickly inflow system, filling has been completed, should first filling valve is closed, and then remove the connecting pipe.
(4) refrigeration system debugging. After the refrigerant charge is completed (if required refrigerant charge), you can load debugging. In recent years, screw chiller performance and electrical control have made considerable progress, many screw chillers before the official start of the main electrical control system can be simulated motion detection side, that is the host unit is not energized, the control system electricity, then by setting internal unit, the unit's electronic control system for testing, components are functioning properly. What problems arise if the electronic control system, can be solved in time. Finally, pass on the power to the host for debugging.
In the debugging process, should pay special attention to the following points:
1) Check the cooling system throughout the valves are open in a normal state, especially the exhaust valve, do not close.
2) Open the cooling water valve and cold water valve evaporator condenser, cold water and cooling water flow should comply with the request of the manufacturer.
3) Before starting the unit should observe the power supply voltage is normal.
4) Follow the manufacturer's manual supplied power, start the unit.
5) When the unit starts, according to the manufacturer's manual provided by the boot, the parameters to view the unit is normal.
6) According to screw chiller factory to provide the operational data recording table, the data on screw chillers be recorded, especially in some key parameters must be recorded clearly.
7) screw chillers during the operation, should pay attention to the compressor, whether normal download-agency working.
8) should be the proper use of safety devices installed in the refrigeration system, such as high and low voltage protection devices, cold water and cooling water without water Flow Switch, safety valves and other equipment, should be replaced if damaged.
9) screw chillers such as abnormal situation should immediately stop checking. Before refrigeration system debugging, be sure to do air conditioning systems clean and dry inside job. If the preliminary work is not seriously, during commissioning will increase the number of workload, and will run the cooling device after brings many risks.
Power Operation (b) screw chillers
After the screw refrigeration compressor in question after commissioning operations, and found processed, they can enter the normal operation procedures. Its methods of operation are:
(1) Check whether the status of the unit in which compliance with the relevant valve power requirements.
(2) to the unit of electrical power control device, and turn on the power switch, the power to control lights.
(3) to start cooling water pumps, cooling tower fans and coolant pumps, you should be able to see the lights of the three runs.
(4) detecting the lubricant oil temperature reaches 30 ℃. Failure to 30 ℃, it should open the electric heater for heating and to activate the pump, the lubricating oil circulating temperature uniformity increased.
(5) After the pump starts running, the energy regulator control valve is in place in load shedding and determine the spool is in the zero position.
(6) adjusting the oil pressure regulating valve. The hydraulic reach 0.5 ~ O.6MPa.
(7) closed compressor power to start control switch, turn on the compressor suction valve, the compressor starts running after a delay, after the oil pressure to adjust the compressor is running, and it is higher than the discharge pressure of 0.15 to 0.3 MPa.
(8) for closing the liquid line solenoid valve control circuit, starting solenoid valve. The evaporator for liquid refrigerant, the energy regulator in a loading position, and over time, progressively increasing load. While observing the suction pressure by adjusting the expansion valve, the suction pressure is stable at 0.36 ~ O.56MPa.
After (9) of the compressor operation, when the oil temperature reaches 45 ℃
When disconnecting the power of the electric heater, and open the oil cooler cooling water inlet and outlet valves, the compressor is running, oil temperature control in the range of 40 ~ 55 ℃.
(10) If the cooling water temperature is low, you can temporarily turn off the cooling tower fan.
(11) will open the fuel injection valve 1/2 to 1 turn, and should enable the continent and the intake valve unit is in the fully open position.
(12) The energy adjustment means to adjust to 100% position, while adjusting the suction superheat expansion valve is maintained at above 6 ℃.
(13) screw chillers start running checks. After the completion of the unit starts running invest, you should be careful to check the contents of the following, to ensure the safe operation of the unit.
1) indicators coolant pumps, cooling water pumps, cooling tower fan sound runtime, vibration, water pump outlet pressure, water temperature and other operating parameters are within the normal range.
2) whether the lubricant oil at below 60 ℃, the oil pressure is higher than the exhaust pressure 0.15 ~ O.3MPa, the oil level is normal.
3) compressor at full load operation, suction pressure value is within 0.36 ~ 0. 56MPa range.
4) whether the discharge pressure of the compressor 1.55MPa or less, the exhaust gas temperature is below 100 ℃.
Procedure 5) screw chiller compressor is running, run the motor current is within a predetermined range. If the current is too large, it should be adjusted to reduce load operation, to prevent the motor due to the running current is too large to burn.
6) a sound when the compressor is running, vibration is normal.
In the above, if found to have abnormal circumstances, they should immediately stop, identify the reasons for the exclusion of the fault, and then restart the unit. We must not take questions for screw chillers run, in order to avoid a major accident.
Flag (c) screw chiller compressor normal operation
Screw refrigeration compressor running flags as follows:
(1) the compressor discharge pressure is 1.8 ~ 1.47MPa (gauge pressure);
(2) compressor discharge temperature is 45 ~ 90 ℃, the maximum should not exceed 1.05 ℃;
Oil (3) of the compressor is about 40 ~ 55 ℃;
(4) Hydraulic compressor is 0.2 ~ 0.3MPa (gauge pressure)
Process (5) the sound operation of the compressor should be uniform, smooth, no abnormal sound;
Condensing temperature (6) units should high 3 ~ 5 ℃ than cooling water temperature; extremely cold temperatures should generally be controlled at about 40 ℃, the condenser water temperature should be below 32 ℃;
Evaporation temperature (7) unit should be lower than 3 ~ 4 ℃ water temperature cooling water, cooling water outlet temperature is generally about 5 ~ 7 ℃.
Stop operation (d) screw refrigeration compressors
Stop screw refrigeration compressors into normal shutdown, emergency shutdown, automatic shutdown and long-term shut-down stop mode.
Operation 1. Normal shutdown
(L) to manually uninstall the control device is placed in the position of load shedding.
(2) closes the solenoid valve supply tube condenser to swallow the road between the hair, the liquid valve.
(3) stopping the compressor running, while closing its intake valve.
(4) to be energy load reduction to zero, stop the pump working.
(5) The energy adjustment device is placed on the stop position.
(6) Close the oil cooler cooling water inlet valve.
(7) Stop the cooling water pump facilitate cooling tower fan operation.
(8) to stop the operation of the refrigerant pump.
(9) off the main power.
Emergency stop 2. Unit
Screw refrigeration compressor during normal operation, such as hair regulatory anomalies; for the protection of crew safety, they should implement an emergency stop. Its methods of operation are:
(1) Stop the compressor is running.
(2) Close the suction valve of the compressor.
A fluid valve (3) Close the unit for the solenoid valve and a condenser tube on the.
(4) stop the pump working.
(5) Close the oil cooler cooling water inlet valve.
(6) Stop refrigerant pumps, cooling water pumps and cooling tower fans.
(7) cut off the mains.
Stop method crew appeared power, water supply and other faults during operation when the centrifugal compressor can refer emergency stop processing the relevant content.
After the unit emergency stop, should promptly investigate the cause of the failure, after troubleshooting, according to the normal startup method to restart the unit.
3. The unit automatically shut down
Screw refrigeration compressor is running, if the pressure of the unit, the temperature exceeds a predetermined range, the unit control system protection device will play a role, automatically stops the compressor, a phenomenon known as automatic shutdown of the unit. When the unit automatically shut down, the unit of the electrical control board its corresponding fault indicator lights to indicate the fault location. Encountered such a situation occur, after the host downtime, downtime can operate in other parts of the emergency stop manner. After completing the stop operation work, to deal with the unit for inspection, troubleshooting before they can be normal startup procedures to restart the operation. , Refrigeration equipment screw compressors in refrigeration industry, cold storage, cold chain supermarkets, chemical industry, commercial air conditioning and other industries has been widely used, the screw compressor unit generally equipped with GE-315 Flow Switches, flow switching to monitor the flow of lubricating oil circuit, ensuring the minimum flow to prevent the device from running dry.
4. Long-term shutdown unit
Because of the cold source for central air conditioning refrigeration compressor screw are seasonal running, so long downtime of the unit. To ensure the safety of the unit, in the season shut down, shut down operations according to the following method.
(L) in the unit normal operation, close the valve unit, the unit derating run the unit in all of the refrigerant pumped to the condenser. As the unit will not shut down the suction pressure too low, you can adjust the setting value for the low pressure relay
0.15MPa. When the suction pressure dropped to about 0.15MPa, compressor shutdown, when the compressor is stopped, the low pressure value can then be transferred back.
Oil cooler (2) will stop running after the condenser, evaporator water removed, and put a clean residual water, frozen when its internal heat transfer tube to prevent winter.
(3) Close the unit's good about the valve and check for leaks.
(4) Every week should start lubricating oil pump run 10 ~ 20min, to enable long-term lubricant evenly distributed to each face in the compressor, to prevent the unit due to prolonged downtime caused by mechanical surface oil, causing a reboot difficulties.
(V) screw chiller maintenance
Screw chillers maintain the main content of maintenance, including routine maintenance and periodic maintenance. Regular repair and maintenance to ensure the normal operation of the unit long, extend the service life of the unit, but can also save cooling energy. For screw chiller
Group, should be run record, recording unit running situations, but also to establish a maintenance technical files. Complete technical information to help find hidden faults, to take early measures to prevent the discharge barrier appears.
1 . Screw Compressor
Screw compressor is a very critical component unit, the compressor is directly related to the stability of the unit. If the compressor malfunction. Since the mounting precision screw compressors are higher, generally we need to ask the manufacturer for repair.
2 . Cleaning the condenser and evaporator
Water-cooled condenser cooling water because it is open-loop circuit, generally use the tap water through a cooling tower recycling. When the calcium and magnesium content in the water is large, easily decomposed and deposited on the cooling water pipes and the formation of scale, affecting heat transfer. Fouling too thick will make the cooling water flow cross-section narrowing, reduced water condensing pressure rises. Therefore, when the poor water quality of cooling water used for cooling water pipes cleaned at least once a year to remove pipe scale, and other contaminants. Cleaning the condenser pipes usually have the following two methods:
(1) using specialized pigging gun tube cleaning.
(2) use a special cleaner rinse cycle, or filling in the cooling water until 24h before replacing the solution until the washing up.
3. Change oil
Crew after prolonged use, lubricating oil qualitative difference, the oil inside the impurities and moisture increases, so regular observation and inspection oil. Once the problem should be replaced, the replacement oil grades must meet the technical information.
4. Replace the filter drier
Dry filter is to ensure the normal circulation of refrigerant important part. As the water immiscible with the refrigerant, if the system contains water, will greatly affect the operating efficiency of the unit, thus maintaining an internal drying system is very important, inside the filter drier filter must be periodically replaced.
5. The check valve
Condenser and evaporator screw chillers belong on the pressure vessel, according to the regulations, to be installed on the high pressure side valve unit ie condenser body, once the unit is in the non-normal working environment, safety valve can automatically release pressure, in order to prevent high pressure may cause harm to the human body. So periodically check the safety valve for the safety of the whole unit is very important.
6 refrigerant charge Note:
If no other particular reason, generally the unit will not generate a lot of leakage. If used improperly, or after repair, there is a certain amount of refrigerant leaks. We need to re-add refrigerant. Refrigerant charging unit must pay attention to the use of refrigerants grades.
(F) operational management and stop precautions
1. screw chillers run management considerations
Normally open (1) of the unit, shut down the factory must strictly follow the steps provided in the operating instructions to operate.
(2) unit during operation, should be promptly and correctly make a record operating parameters.
(3) unit operating in the event of alarm shutdown, shall promptly notify the relevant personnel on the unit to be checked. You can also contact directly with the factory.
(4) The crew is forbidden to shorting flow switch during the run to avoid frozen pipes.
(5) room should have dedicated staff responsible prohibited without fixed duties into the room, the operating unit.
(6) room should be equipped with appropriate safety equipment and maintenance testing tools, such as pressure gauges, thermometers, etc., tools should be stored in a fixed position.
2 . Screw chillers stop Precautions
(1) The unit should be shut off after the main power switch.
Period (2) If the unit is in long-term shutdown, should the cold water, cooling water, let go of all the water inside the system, to prevent corrosion. Cap should be sealed water chamber.
(3) unit at the long-term shutdown, should do the maintenance work.
(4) During the shutdown, all units should be covered to prevent fouling.
(5) During the shutdown, it has nothing to do with the unit shall not contact with the machine.