Maintenance of Screw Chiller

2024-09-25

The correct debugging of screw chiller units is an important link to ensure the normal operation of refrigeration devices, save energy consumption and extend service life. For large and medium-sized refrigeration systems installed on site, before debugging, first of all, according to the design drawings, be familiar with the layout and connection of the entire system, understand the external structure and component performance of each equipment, as well as the electric control system and water supply system. For this reason, refrigeration, water and electricity engineers should participate in the debugging. Before debugging, users should carefully read the product operation manual provided by the manufacturer and follow the operation requirements step by step. Operators must receive special training from the manufacturer and obtain the operation certificate of the unit before they can start operation, so as to avoid fatal damage to the unit caused by wrong operation.

Preparations before debugging
(1) Since screw chiller units belong to medium and large refrigerators, close cooperation among design, installation and use is required during debugging. In order to ensure the debugging work is carried out in an orderly manner, it is necessary to form a temporary trial operation group composed of personnel from relevant aspects to comprehensively command the debugging work.
(2) The personnel responsible for debugging should be fully familiar with the structure and performance of screw chiller units, be familiar with refrigeration safety technology, clarify the debugging methods, steps and technical requirements to be achieved, formulate a detailed and specific debugging plan, and make the debugging personnel at each post clear about their tasks and requirements.
(3) Check whether the installation of screw chiller units meets the technical requirements, whether the foundation of screw chiller units meets the requirements, and whether the size, specification and material of connecting pipelines meet the design requirements.

(4) The power supply system of the unit should be fully installed and passed debugging.
(5) Conduct a water passage test on the cold water and cooling water systems separately, flush the dirt in the waterway system, the water pump should work normally, and the circulating water volume should meet the requirements of the working condition.
(6) Clean up the environmental site for debugging to achieve cleanliness, brightness and unobstructed.
(7) Prepare all kinds of general tools and special tools required for debugging.
(8) Prepare all kinds of measuring instruments and meters such as pressure, temperature, flow, quality and time required for debugging.
(9) Prepare the necessary safety protection equipment for debugging and operation.
Debugging of screw chiller units
(1) Charging of refrigerant. At present, refrigeration units are generally charged with refrigerant as required before leaving the factory. After on-site installation, if no accidental damage is found through visual inspection, relevant valves can be directly opened (the user manual provided by the manufacturer should be read first. During transportation, the valves on the unit are generally in the closed state) for start-up debugging.
If it is found that the refrigerant has leaked out or is insufficient, the leakage point should be found first and the leakage phenomenon should be eliminated. Then, according to the requirements of the product operation manual, add the refrigerant of the specified brand. Note that the refrigerant charging amount should meet the technical requirements.
(2) Some screw chiller units need to be charged with refrigerant on the user's site. The refrigerant charging amount and refrigerant brand must comply with the regulations. Insufficient refrigerant charging will lead to insufficient cooling capacity. Excessive refrigerant charging will not only increase costs, but also may have adverse effects on operating energy consumption.
(3) Before charging refrigerant, sufficient refrigerant should be prepared in advance. During charging, it can be directly filled from the special liquid filling valve. Since the system is in a vacuum state and the pressure difference between the refrigerant in the cylinder and the system is large, when the valve is opened (the air in the connecting pipe should be blown out with refrigerant first to avoid air entering the unit and affecting the unit performance), the refrigerant quickly flows from the cylinder into the system. After charging is completed, the liquid filling valve should be closed first, and then the connecting pipe should be removed.
(4) Debugging of refrigeration system. After the refrigerant charging is completed (if refrigerant needs to be charged), load debugging can be carried out. In recent years, screw chiller units have made great progress in performance and electrical control. Many screw chiller units can perform simulated action detection on the main electrical control system before formal startup, that is, the unit host is not powered on, the control system is powered on, and then through the internal settings of the unit, the electrical control system of the unit is detected to see if the components are operating normally. If there is any problem with the electrical control system, it can be solved in time. Finally, turn on the main power supply for debugging. During the debugging process, special attention should be paid to the following points:
1. Check whether all valves in the refrigeration system are in the normal open state, especially the exhaust stop valve, and do not close it.
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 proposed by the manufacturer.
3. Before starting, pay attention to observing whether the power supply voltage of the unit is normal.
4. Start the unit according to the start-up manual provided by the manufacturer.
5. After the unit is started, according to the start-up manual provided by the manufacturer, check whether the various parameters of the unit are normal.
6. According to the operation data record form of screw chiller units provided by the manufacturer, record the various data of screw chiller units, especially some main parameters must be recorded clearly.
7. During the operation of the screw chiller unit, pay attention to whether the upper and lower loading mechanisms of the compressor work normally.
8. Correctly use the safety protection devices installed in the refrigeration system, such as high and low pressure protection devices, cold water and cooling water cut-off flow switches, safety valves and other equipment. If any damage occurs, it should be replaced in time.
9. If the screw chiller unit has abnormal conditions, it should be shut down immediately for inspection.
  Before debugging the refrigeration system, be sure to do a good job in cleaning and drying the interior of the air conditioning system.
  If the preliminary work is not carried out carefully, a lot of work will be added during the debugging period, and many hidden dangers will be brought to the operation of the refrigeration device in the future.