1. Suction and exhaust pressure protection: mainly to prevent the compressor suction pressure is too low and exhaust pressure is too high. With the pressure controller, suction pressure and exhaust pressure reaches the alert pressure value, the other compressor stops running.
2. Differential oil pressure protection: for the compressor with oil pump oil supply, to prevent the oil pump does not affect the compressor lubrication and cause the cylinder unloading mechanism can not work properly. The protection method is to use the oil pressure controller to detect the oil pump import and export oil pressure difference, if the oil pressure difference continues to 60g or so to reach the normal value (0.15MPa or so), the compressor will stop.
3. Compressor exhaust temperature and oil temperature protection: due to prevent the exhaust temperature is too high and oil is too low or too high. With the temperature controller, when the above temperature reaches the warning value, the compressor will be shut down.
4. Cooling water jacket cut-off protection: ammonia compressor cylinder head with cooling water jacket on the compression process to apply external cooling. With the water flow relay seat cooling water cut-off protection control, if the continuous cut-off reaches a specified time, the control compressor shutdown.
In the refrigeration system using refrigerant liquid pump to evaporator forced liquid supply cycle, if the pump operation on the night, will cause cavitation damage to the refrigerant liquid pump and burn the motor. The differential pressure controller is used to detect the fluid pressure difference before and after the pump, if the differential pressure lasts for 8~15s and does not reach the normal value, the pump is controlled to stop running.
Cooling water system and chilled water system outside the refrigeration system also need to use the cooling water pump and chilled water pump, these pumps will encounter the same problems in operation, also use the pressure difference controller to implement the same protective control.
The high-pressure containers in the chiller refrigeration system (such as water-cooled condensers with refrigerant on the shell side, high-pressure reservoirs, etc.) are equipped with safety valves on the containers in order to avoid shell breakage when the internal pressure is too high. The safety valve opens automatically when the internal pressure exceeds 10% of the control value, and suppresses the increase of the internal pressure of the container by releasing the high-pressure medium therein in an emergency.
Smaller size high pressure vessels can use simpler fusible plugs or safety membranes. When the temperature (pressure) inside the vessel exceeds the warning value, the fusible plug or safety membrane ruptures, allowing the high-pressure medium in the vessel to be discharged.
Refrigeration system in normal operation, the refrigerant in each pipeline according to a certain direction of movement, in the possibility of reverse movement and cause harm to the occasion, the corresponding pipeline should be equipped with a check valve, to automatically prevent the role of reverse flow.
The more commonly used industrial chillers include: water-cooled/air-cooled box-type chillers, screw-type chillers, low-temperature chillers, open chillers, acid and alkali resistant chillers, etc.