Screw Refrigeration Compressor Unit Operation

1. Initial Startup and Shutdown

Before starting the machine, the coupling must be realigned. Before starting the machine for the first time, check the operation of all parts of the compressor and electrical components.

Inspection items are as follows:
Turn on the power switch and set the selector switch to the manual position;
Press the alarm button; the alarm will sound; press the mute button; the alarm will go off;
Press the electric heater button; the indicator light will illuminate. After confirming that the electric heater is operating, press the heating stop button; the heating indicator light will go off;
Press the water pump start button; the water pump starts; the indicator light will illuminate. Press the water pump stop button; the water pump stops; the indicator light will go off;
Press the oil pump start button; the oil pump indicator light will illuminate, and the oil pump is running and rotating in the correct direction. Adjust the oil pressure differential to 0.4-0.6 MPa.
Move the four-way valve or press the load increase/decrease button to check that the slide valve and energy indicator are operating properly. The energy level indicator should be at “0.” Check the settings of all automatic safety relays or programs.

Exhaust pressure high protection: Exhaust pressure ≤ 1.57 MPa

Injection temperature high protection: Injection temperature ≤ 65°C

Oil pressure differential low protection: Oil pressure differential ≥ 0.1 MPa

Pressure differential high protection before and after the fine filter: Pressure differential ≤ 0.1 MPa

Intake pressure low protection: Set according to actual operating conditions.

After checking the above items, the unit can be started. The startup steps are as follows:

1) Select the manual start switch.

2) Open the compressor discharge shut-off valve.

3) Unload the compressor to the “0″ position, i.e., 10% load.

4) Start the cooling water pump and refrigerant water pump to supply water to the condenser, oil cooler, and evaporator.

5) Start the oil pump.

6) 30 seconds after the oil pump starts, and the oil pressure differential between the oil pressure and the exhaust pressure reaches 0.4-0.6 MPa, press the compressor start button. The compressor will start, and bypass solenoid valve A will automatically open. After the motor is operating normally, valve A will automatically close.

7) Observe the suction pressure gauge, gradually open the suction shutoff valve, and manually increase the load, taking care not to let the suction pressure drop too low. After the compressor enters normal operation, adjust the oil pressure regulating valve to maintain a differential oil pressure of 0.15-0.3 MPa.

8) Check the pressure and temperature of all parts of the equipment, especially those of moving parts, for normal operation. If any abnormality is detected, shut down the equipment for inspection.

9) The initial operation should not be too long; approximately half an hour is sufficient. The shutdown sequence is to unload the equipment, shut down the main engine, close the suction shutoff valve, stop the oil pump, and then stop the water pump, completing the initial startup process. Pressing the main engine stop button automatically opens bypass solenoid valve B. Valve B automatically closes after shutdown.

42b2dd36-b008-4da8-b48a-79bbe02b1f50

2. Normal Startup and Shutdown: The normal startup process is as follows:

a. Select manual startup, which is the same as the first startup process.

b. Select automatic startup

1) Open the compressor exhaust shutoff valve and start the cooling water pump and refrigerant pump. 2) Press the compressor start button. The oil pump will automatically start operating and the slide valve will automatically return to the “0″ position. After the oil pressure differential is established, the main motor will automatically start after a delay of approximately 15 seconds, and bypass solenoid valve A will automatically open. Once the motor is operating normally, valve A will automatically close. 3) When the main motor starts, slowly open the suction shutoff valve simultaneously. Otherwise, excessive vacuum will increase machine vibration and noise. 4) The compressor will automatically increase the load to 100% and enter normal operation. The load position will automatically adjust according to the pressure setpoint or refrigerant temperature setpoint.

The normal shutdown process is as follows: a. Manual shutdown: The same as the first startup process. b. With the selector switch in the automatic position: 1) Press the compressor stop button. The slide valve automatically returns to the “0″ position, the main motor automatically stops, and bypass solenoid valve B automatically opens. The oil pump automatically stops after a delay. After shutdown, valve B automatically closes. 2) Close the suction stop valve. If the machine is shut down for an extended period, the exhaust stop valve should also be closed. 3) Turn off the water pump power and the compressor power switches.

螺杆机组主图 (4)

3. Precautions during operation

(1) During the operation of the compressor, pay attention to observe the suction and exhaust pressure, suction and exhaust temperature, oil temperature and oil pressure, and record them regularly. The instrument must be accurate.

(2) If the compressor stops automatically due to a safety protection action during operation, the cause of the fault must be found before restarting. It is never allowed to restart by changing their set values ​​or shielding the fault.

(3) When the main unit stops due to a sudden power outage, the bypass solenoid valve B cannot be opened, and the compressor may reverse. At this time, the suction stop valve should be closed quickly to reduce the reverse.

(4) If the machine is shut down for a long time in a season with low temperature, all water in the system should be drained to avoid freezing damage to the equipment.

(5) If the machine is started in a season with low temperature, first start the oil pump and press the motor to rotate the steering wheel to move the coupling so that the oil circulates in the compressor for sufficient lubrication. This process must be carried out in manual start-up mode; if it is a Freon refrigerant, the oil heater should be turned on to heat the lubricating oil before starting the machine, and the oil temperature should be guaranteed to be above 25℃.

(6) If the unit is shut down for a long time, the oil pump should be started every 10 days or so to ensure that all parts of the compressor are lubricated with oil. The oil pump can be started for 10 minutes each time. The compressor should be started every 2 to 3 months for 1 hour each time to ensure that the moving parts do not stick together.

(7) Before starting the unit each time, it is best to rotate the compressor several times to check whether the compressor is stuck and ensure that the lubricating oil is evenly distributed in all parts.

brand2

 

 


Post time: Oct-22-2025