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How to maintain the screw chiller with Ammonia/EVR/MSV refrigeration solenoid valve?

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How to maintain the screw chiller with Ammonia/EVR/MSV refrigeration solenoid valve?

How to maintain the screw chiller with Ammonia/EVR/MSV refrigeration solenoid valve?

How to maintain the screw chiller?

 

Preparation before the start of the screw chiller

The correct commissioning of the screw chiller is an important part of ensuring the normal operation of the refrigeration unit, saving energy consumption and prolonging the service life. For on-site installation of large and medium-sized refrigeration systems, the requirements should be familiar with the layout and connection of the entire system, the outline structure and component performance of each equipment, as well as the electronic control system and water supply system. To this end, engineers such as refrigeration and hydropower should participate in the commissioning. Users should carefully read the product operation manual provided by the factory before commissioning, and proceed step by step according to the operation requirements. The operator must undergo special training from the factory to obtain the operation certificate of the unit before the operation can be carried out, so as to avoid fatal damage to the unit caused by wrong operation. (Ammonia/EVR/MSV refrigeration solenoid valve)

1 . Preparation before commissioning

(1) Since the screw chiller is a medium and large chiller, it needs to be closely coordinated in design, installation and use during commissioning. In order to ensure that the commissioning work is carried out in an orderly manner, it is necessary for the relevant personnel to form a temporary commissioning team to fully conduct the commissioning work. (Ammonia/EVR/MSV refrigeration solenoid valve)

(2) The personnel responsible for commissioning should be fully familiar with the structure and performance of the screw chiller, familiar with the safety technology of the chiller, clarify the methods, steps and technical requirements to be debugged, formulate detailed and specific commissioning plans, and make each post The commissioning staff clarifies their tasks and requirements. (Ammonia/EVR/MSV refrigeration solenoid valve)

(3) Check whether the installation of the screw chiller meets the technical requirements, whether the foundation of the screw chiller meets the requirements, and whether the size, specification and material of the connecting pipeline meet the design requirements. (Ammonia/EVR/MSV refrigeration solenoid valve)

(4) The power supply system of the unit should be fully installed and debugged. (Ammonia/EVR/MSV refrigeration solenoid valve)

(5) Pass the water test on the cold water and cooling water system separately, flush the dirt of the waterway system, the water pump should work normally, and the circulating water quantity meets the requirements of working conditions. (Ammonia/EVR/MSV refrigeration solenoid valve)

(6) Clean and debug the environmental site to achieve clean, bright and smooth. (Ammonia/EVR/MSV refrigeration solenoid valve)

(7) Prepare the various common tools and special tools required for debugging. (Ammonia/EVR/MSV refrigeration solenoid valve)

(8) Prepare various measuring instruments and meters for pressure, temperature, flow, quality, time, etc. required for commissioning. (Ammonia/EVR/MSV refrigeration solenoid valve)

(9) Prepare the safety protection equipment necessary for commissioning operation. (Ammonia/EVR/MSV refrigeration solenoid valve)

2 . Screw chiller commissioning

(1) Charge of refrigerant. At present, the refrigeration unit is generally filled with refrigerant before leaving the factory. After the installation on site, if no accidental damage is found in the visual inspection, the relevant valve can be opened directly (you should read the manufacturer's instruction manual first, in transit, on the unit). The valve is normally in the off state) for commissioning. If the refrigerant has been leaked or insufficient, first find the leak point and eliminate the leak, then add the required grade of refrigerant according to the product instruction manual. Note that the refrigerant charge should meet the technical requirements. (Ammonia/EVR/MSV refrigeration solenoid valve)

(2) Some screw-type chillers need to be filled with refrigerant at the user's site. The refrigerant charge and refrigerant grade must be in accordance with regulations. The refrigerant charge is insufficient. Will result in insufficient cooling. Excessive refrigerant charge will not only increase the cost, but also adversely affect the operating energy consumption. (Ammonia/EVR/MSV refrigeration solenoid valve)

(3) Before charging the refrigerant, sufficient refrigerant should be prepared in advance. When filling, it can be directly charged from the special filling valve. Since the system is in a vacuum state, the pressure difference between the refrigerant and the system in the cylinder is large. When the valve is opened (the air in the connecting pipe should be blown out with the refrigerant first, so that the air does not enter the unit and affect the performance of the unit), the refrigerant is quickly replaced by the cylinder. In the flow system, after filling, the liquid filling valve should be closed first, and then the connecting pipe should be removed. (Ammonia/EVR/MSV refrigeration solenoid valve)

(4) Refrigeration system commissioning. After the refrigerant is charged (if the refrigerant needs to be charged), the load can be debugged. In recent years, screw chillers have made great progress in performance and electrical control. Many screw chillers can perform analog operation check on the main electronic control system before the official start-up, that is, the main unit of the unit is not energized, and the control system Power on, and then through the internal settings of the unit, the unit's electronic control system is tested, and the components are running normally. If there is any problem with the electronic control system, it can be resolved in time. Finally, connect to the host power supply for debugging. During the debugging process, special attention should be paid to the following points:

  1. Check that the valves in the refrigeration system are in the normal open state, especially the exhaust shut-off valve, do not close.
  2. Open the cooling water valve of the condenser and the cold water valve of the evaporator. The flow of cold water and cooling water should meet the requirements of the factory.
  3. Before starting, pay attention to observe whether the power supply voltage of the unit is normal.
  4. Start the unit according to the start-up manual provided by the factory.
  5. After the unit is started, check whether the parameters of the unit are normal according to the start-up manual provided by the factory.
  6. According to the screw chiller operating data record table provided by the factory, record the data of the screw chiller, especially some main parameters must be clearly recorded.
  7. During the operation of the screw chiller, attention should be paid to whether the upper and lower downloading mechanisms of the compressor are working properly.
  8. The safety protection devices installed in the refrigeration system, such as high and low pressure protection devices, cold water and cooling water water flow switch, safety valve, etc., should be used correctly. If there is damage, replace it in time.
  9. If there is any abnormality in the screw chiller, stop it immediately.

 

Before the refrigeration system is commissioned, be sure to clean and dry the air conditioning system. If the preliminary work is not carried out seriously, a lot of work will be added during the commissioning, and it will bring many hidden dangers to the future operation of the refrigeration unit. (Ammonia/EVR/MSV refrigeration solenoid valve)

Start-up operation of screw chiller

After the screw-type refrigeration compressor has undergone trial operation and processed the discovered problems, it can enter the normal operation procedure. Its method of operation is:

(1) Confirm that the state of each relevant valve in the unit meets the requirements for power on.

(2) Supply power to the unit's electrical control unit, and turn on the power switch to make the power control indicator light.

(3) Start the cooling water pump, cooling tower fan and refrigerant pump, and you should be able to see that the running indicators of the three are on.

(4) Check if the lubricating oil temperature reaches 30 °C. If it is less than 30 °C, the electric heater should be turned on for heating, and the oil pump can be started to increase the lubricating oil circulation temperature evenly.

(5) After the oil pump starts running, the energy adjustment control valve is placed in the deloading position, and the spool valve is determined to be in the zero position.

(6) Adjust the oil pressure regulating valve. The oil pressure is made 0.5 to 0.6 MPa.

(7) Close the compressor power supply, start the control switch, open the compressor suction valve, and start the compressor after the delay. After the compressor is running, adjust the lubricating oil pressure to make it higher than the exhaust pressure 0.15~0.3. MPa.

(8) Close the solenoid valve control circuit in the liquid supply pipeline and start the solenoid valve. The liquid refrigerant is supplied to the evaporator, the energy regulating device is placed at the loading position, and the load is gradually increased over time. At the same time, observe the suction pressure, and adjust the expansion valve to stabilize the suction pressure at 0.36~O.56MPa.

(9) After the compressor is running, when the lubricating oil temperature reaches 45 °C, the electric heater is turned off, and the inlet and outlet valves of the cooling water of the oil cooler are turned on, so that the oil temperature is controlled at 40 during the operation of the compressor. Within the range of ~55 °C.

(10) If the cooling water temperature is low, the fan of the cooling tower can be temporarily turned off.

(11) Open the injection valve 1 / 2 ~ 1 turn, and at the same time, the suction valve of the suction and the unit should be in the fully open position.

(12) Adjust the energy adjustment device to 100% position and adjust the expansion valve to keep the suction superheat above 6 °C.

(13) Inspection of the start-up operation of the screw chiller. After the unit is started and put into operation, attention should be paid to the following to ensure the safe operation of the unit.

  1. The sound and vibration of the refrigerant pump, cooling water pump and cooling tower fan during operation, whether the pump outlet pressure, water temperature and other indicators are within the normal working parameters.
  2. Is the oil temperature of the lubricating oil below 60 °C, and whether the oil pressure is higher than the exhaust pressure by 0.15~O.3MPa, and the oil level is normal.
  3. When the compressor is at full load, the suction pressure value is in the range of 0.36 to 0. 56MPa.
  4. Is the discharge pressure of the compressor below 1.55 MPa and whether the exhaust temperature is below 100 °C.
  5. During the operation of the screw chiller compressor, the running current of the motor is within the specified range. If the current is too large, it should be adjusted to the load shedding operation to prevent the motor from being burnt due to excessive operating current.
  6. Whether the sound and vibration of the compressor are normal.


If any abnormality is found in the above items, it should be stopped immediately. After identifying the cause and troubleshooting, restart the unit. Do not let the screw chiller run with problems to avoid major accidents. (Ammonia/EVR/MSV refrigeration solenoid valve)

Shutdown operation of screw refrigeration compressor

The shutdown of the screw refrigeration compressor is divided into normal shutdown, emergency shutdown, automatic shutdown and long-term shutdown. (Ammonia/EVR/MSV refrigeration solenoid valve)

1. Normal shutdown operation method

(l) Place the manual unloading control unit in the load shedding position.

(2) Close the solenoid valve and the outlet valve on the liquid supply line between the condenser and the hair dryer.

(3) Stop the compressor operation and close its suction valve.

(4) After the energy is reduced to zero, stop the oil pump.

(5) Place the energy adjustment device in the "stop" position.

(6) Close the cooling water inlet valve of the oil cooler.

(7) Stop the operation of the cooling water pump and the cooling tower fan.

(8) Stop the operation of the refrigerant pump.

(9) Turn off the main power.

2. Emergency shutdown of the unit

In the normal operation of the screw refrigeration compressor, such as the abnormal phenomenon of the regulation; in order to protect the safety of the unit, emergency shutdown should be implemented. Its method of operation is:

(1) Stop the compressor operation.

(2) Close the suction valve of the compressor.

(3) Close the solenoid valve on the unit supply pipe and the outlet valve of the condenser.

(4) Stop the oil pump work.

(5) Close the cooling water inlet valve of the oil cooler.

(6) Stop the refrigerant pump, cooling water pump and cooling tower fan.

 

Echo

Pub Time : 2019-07-31 16:22:27 >> News list
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