【Mechanical Equipment Technology Edition】Daily Question 20171021: Handling Refrigeration System Failures
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This post was last edited by YORK Industrial Refrigeration on 2017-10-26 at 09:44. Starting from now, in order to enhance communication among users, we have launched the \"One Question per Day\" activity on the Mechanical Equipment Technology forum. We hope everyone will participate actively to progress and improve together! ! ! Rewards: 3 wealth points for active participation, 10-15 wealth points for correct answers. This question is valid for two days; no scoring will be given after that period. For industrial chillers, how should the water entering the system be handled? 1. Perform thorough vacuuming before filling the refrigerant; the higher the vacuum level, the better. Vacuum pumping is one of the methods used for dehumidifying and drying systems. The drying time required depends on factors such as the size of the system’s container, the performance and efficiency of the vacuum pump, the indoor temperature, and the amount of moisture present in the system. Generally, when the temperature and pressure of the system reach 1.7°C and 5 mmHg gauge, it can be considered that all the air within the system has been removed. Then, a certain amount of nitrogen is added, and the industrial refrigeration system is evacuated again to reach the aforementioned temperature and pressure; it can be assumed that the system’s requirements regarding dryness and vacuum have been met at the desired level. 2. When charging a industrial refrigeration machine system with refrigerant, external drying of the refrigerant is carried out, that is, a dry filter is installed in the charging pipeline; the desiccants used include calcium fluoride, silica gel, molecular sieves (synthetic zeolites), etc. Reduce the water content of the refrigerant entering the system to a certain level. 3. A dryer-filter should be installed on the pipeline of the high-pressure liquid line in the refrigeration system of industrial refrigerators, prior to it reaching the thermal expansion valve, in order to further remove any water contained within and any precipitates that form as a result of chemical reactions during operation. Desiccants typically use 4A0 molecular sieves, whose saturated water absorption rate can reach 21–25% (by mass). To prevent the desiccant powder from causing damage to the system, core-type desiccants are generally used nowadays. When selecting a desiccant filter, the flow velocity inside the cylinder is usually set at 0.03 m/s. For R134a systems, the desiccants used are XH7 (carbide) or 3×10-10 M-type molecular sieves. The reason for this is that, compared to R12, water has a lower solubility in R134a. Therefore, in R134a systems, especially those operating at low temperatures, desiccants with better water-absorbing capabilities are required; thus, the desiccants commonly used in R12 refrigeration systems are clearly not suitable. ================================ Premium promotions: Mechanical equipment——York screw compressors: Maintenance procedures http://bbs.hcbbs.com/thread-1806833-1-1.html Mechanical equipment——York Quinton control centers: Upgrades http://bbs.hcbbs.com/thread-1804837-1-1.html Mechanical equipment——GEA Grauso screw compressors: Major repairs http://bbs.hcbbs.com/thread-1800467-1-1.html Mechanical equipment——British HOWDEN screw compressors: Disassembly and maintenance http://bbs.hcbbs.com/thread-1832529-1-1.html Mechanical equipment——Japanese MYCOM screw compressors: Disassembly and maintenance http://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1786445
1) Analyze the reasons. Inspect the entire refrigeration system to determine the cause of water ingress and locate the leak. 2) Segmented fouling blowing. ①The moisture can first be blown away using an air compressor (to save nitrogen), until no water mist is produced. Blow again with high-pressure nitrogen; the nitrogen can be heated while blowing (heating of nitrogen cylinders is prohibited). ②Due to the complexity of the refrigerant system’s pipelines, it is possible, depending on the specific circumstances, to use a welding torch to heat up certain sections of the pipes and blow out the moisture from them. ③Heating and drying: Small components such as capillaries, thermal expansion valves, and compressors can be placed in an oven to be baked and dried. The refrigerant oil must be replaced after the compressor has been dried with water. 3) Vacuum drying: ① Restore the piping, purge with nitrogen to ensure airtightness of the system, then connect a vacuum pump for vacuum drying. (The dry filter tank must be placed at the front end of the vacuum pump to prevent excessive water vapor from entering the pump.) ② During the vacuum drying process, the parts of the pipeline where water tends to accumulate can be heated; the duration of this heating depends on the specific conditions on site. 4) Debug and run. ①Confirm that the moisture in the system has been essentially removed. ②Connect the external drying and filtering tank to the system, and replace the desiccant after 5 minutes of operation. At the same time, monitor the operating parameters of the unit and pay attention to the sound produced by the compressor. If the dryer filter is cold, the expansion valve is frosted, or there is a pressure difference of more than 0.5 kilograms before and after the return air filter, the unit should be stopped immediately. ③ Repeat the above process to continuously replace the desiccant, with the interval between replacements gradually increasing as more replacements are carried out. (Dryants: Calcium chloride drying particles have a high water absorption capacity and are used when there is an excess of moisture at the beginning; colored silica gel can accurately detect the moisture content and can be used for drying later on.) ④Finally, replace the desiccant with color-changing silica gel and run it for 24 hours to confirm that the color-changing silica gel retains its original color. 5) Maintenance completed ① Remove the dry filter tank and restore the refrigerant piping. ②Check the amount of supplementary refrigerant. Power on the machine and check that its operating parameters are normal.
1. Analyze the reasons for water entering the chiller equipment. Inspect the entire refrigeration system to determine the cause of the freezing and identify the leak. 2. Segmental fouling blowing. ①The moisture can first be blown away using an air compressor (to save nitrogen), until no water mist is produced. Blow with high-pressure nitrogen, and the nitrogen can be heated while blowing (heating of nitrogen cylinders is prohibited). ②Due to the complexity of the refrigerant system’s pipelines, it is possible, depending on the specific circumstances, to use a welding torch to heat up certain sections of the pipes and blow out the moisture from them. ③Heating and drying: Small components such as capillaries, thermal expansion valves, and compressors can be placed in an oven to be baked and dried. The refrigerant oil must be replaced after the compressor has been dried with water. 3. Vacuum drying: ① Restore the piping, purge with nitrogen to ensure airtightness of the system, then connect a vacuum pump for vacuum drying. (The dry filter tank must be placed at the front end of the vacuum pump to prevent excessive water vapor from entering the pump.) ② During the vacuum drying process, the parts of the pipeline where water tends to accumulate can be heated; the duration of this heating depends on the specific conditions on site. 4. Debug and run. ①Confirm that the moisture in the system has been essentially removed. ②Connect the external drying and filtering tank to the system, and replace the desiccant after 5 minutes of operation. At the same time, monitor the unit’s operating parameters and pay attention to the sound emitted by the compressor. If the dryer filter is cold, the expansion valve is frosted, or there is a pressure difference of more than 0.5 kilograms before and after the return air filter, the unit should be stopped immediately. ③ Repeat the above process, continuously replacing the desiccant; the interval between replacements can be increased gradually as the number of replacements increases. (Dryants: Calcium chloride drying particles have a high water absorption capacity and are used when there is an excess of moisture at the beginning; colored silica gel can accurately detect the moisture content and can be used for drying later on.) ④Finally, replace the desiccant with color-changing silica gel and run it for 24 hours to confirm that the color-changing silica gel retains its original color. 5. Maintenance completed: ① Remove the dryer filter drum of the refrigeration unit and restore the refrigerant lines. ②Check the amount of supplementary refrigerant. Power on the machine and check that its operating parameters are normal.
1. Analyze the reasons for water entering the chiller equipment. Inspect the entire refrigeration system to determine the cause of the freezing and identify the leak. 2. Segmental fouling blowing. ①The moisture can first be blown away using an air compressor (to save nitrogen), until no water mist is produced. Blow with high-pressure nitrogen, and the nitrogen can be heated while blowing (heating of nitrogen cylinders is prohibited). ②Due to the complexity of the refrigerant system’s pipelines, it is possible, depending on the specific circumstances, to use a welding torch to heat up certain sections of the pipes and blow out the moisture from them. ③Heating and drying: Small components such as capillaries, thermal expansion valves, and compressors can be placed in an oven to be baked and dried. The refrigerant oil must be replaced after the compressor has been dried with water. 3. Vacuum drying: ① Restore the piping, purge with nitrogen to ensure airtightness of the system, then connect a vacuum pump for vacuum drying. (The dry filter tank must be placed at the front end of the vacuum pump to prevent excessive water vapor from entering the pump.) ② During the vacuum drying process, the parts of the pipeline where water tends to accumulate can be heated; the duration of this heating depends on the specific conditions on site. 4. Debug and run. ①Confirm that the moisture in the system has been essentially removed. ②Connect the external drying and filtering tank to the system, and replace the desiccant after 5 minutes of operation. At the same time, monitor the unit’s operating parameters and pay attention to the sound emitted by the compressor. If the dryer filter is cold, the expansion valve is frosted, or there is a pressure difference of more than 0.5 kilograms before and after the return air filter, the unit should be stopped immediately. ③ Repeat the above process, continuously replacing the desiccant; the interval between replacements can be increased gradually as the number of replacements increases. (Dryants: Calcium chloride drying particles have a high water absorption capacity and are used when there is an excess of moisture at the beginning; colored silica gel can accurately detect the moisture content and can be used for drying later on.) ④Finally, replace the desiccant with color-changing silica gel and run it for 24 hours to confirm that the color-changing silica gel retains its original color. 5. Maintenance completed: ① Remove the dryer filter drum of the refrigeration unit and restore the refrigerant lines. ②Check the amount of supplementary refrigerant. Power on the machine and check that its operating parameters are normal.
1. Remove the compressor for disassembly. 2. Remove rust from all spare parts of the compressor. 3. The bearings must be replaced. 4. The large gear must be heated to 115 degrees before it can be installed; otherwise, it will come loose once installed. 5. Be careful with the spring washer of the bearing when installing the rotor; I ran into a problem just once because of that. 6. Fill the system with R11 refrigerant to perform a high-pressure cycle cleaning. 7. Fill the filter with color-changing silica gel; it should remain completely blue until its color changes. 8. It must be heated by the condenser and evaporator during vacuum pumping. 9. The compressor current may be slightly higher after startup and debugging. 10. Replace the oil, as well as the external and internal oil filters, after 3 days of operation. 11. The dry filter element should be replaced with one from Danfoss that is designed for moisture removal.
1. Analyze the reasons for water entering the chiller equipment. Inspect the entire refrigeration system to determine the cause of the freezing and identify the leak. 2. Segmental fouling blowing. ①The moisture can first be blown away using an air compressor (to save nitrogen), until no water mist is produced. Blow with high-pressure nitrogen, and the nitrogen can be heated while blowing (heating of nitrogen cylinders is prohibited). ②Due to the complexity of the refrigerant system’s pipelines, it is possible, depending on the specific circumstances, to use a welding torch to heat up certain sections of the pipes and blow out the moisture from them. ③Heating and drying: Small components such as capillaries, thermal expansion valves, and compressors can be placed in an oven to be baked and dried. The refrigerant oil must be replaced after the compressor has been dried with water. 3. Vacuum drying: ① Restore the piping, purge with nitrogen to ensure airtightness of the system, then connect a vacuum pump for vacuum drying. (The dry filter tank must be placed at the front end of the vacuum pump to prevent excessive water vapor from entering the pump.) ② During the vacuum drying process, the parts of the pipeline where water tends to accumulate can be heated; the duration of this heating depends on the specific conditions on site. 4. Debug and run. ①Confirm that the moisture in the system has been essentially removed. ②Connect the external drying and filtering tank to the system, and replace the desiccant after 5 minutes of operation. At the same time, monitor the unit’s operating parameters and pay attention to the sound emitted by the compressor. If the dryer filter is cold, the expansion valve is frosted, or there is a pressure difference of more than 0.5 kilograms before and after the return air filter, the unit should be stopped immediately. ③ Repeat the above process, continuously replacing the desiccant; the interval between replacements can be increased gradually as the number of replacements increases. (Dryants: Calcium chloride drying particles have a high water absorption capacity and are used when there is an excess of moisture at the beginning; colored silica gel can accurately detect the moisture content and can be used for drying later on.) ④Finally, replace the desiccant with color-changing silica gel and run it for 24 hours to confirm that the color-changing silica gel retains its original color. 5. Maintenance completed: ① Remove the dryer filter drum of the refrigeration unit and restore the refrigerant lines. ②Check the amount of supplementary refrigerant. Power on the machine and check that its operating parameters are normal.
1. Analyze the reasons for water entering the chiller equipment. Inspect the entire refrigeration system to determine the cause of the freezing and identify the leak. 2. Segmental fouling blowing. ①The moisture can first be blown away using an air compressor (to save nitrogen), until no water mist is produced. Blow with high-pressure nitrogen, and the nitrogen can be heated while blowing (heating of nitrogen cylinders is prohibited). ②Due to the complexity of the refrigerant system’s pipelines, it is possible, depending on the specific circumstances, to use a welding torch to heat up certain sections of the pipes and blow out the moisture from them. ③Heating and drying: Small components such as capillaries, thermal expansion valves, and compressors can be placed in an oven to be baked and dried. The refrigerant oil must be replaced after the compressor has been dried with water. 3. Vacuum drying: ① Restore the piping, purge with nitrogen to ensure airtightness of the system, then connect a vacuum pump for vacuum drying. (The dry filtration tank must be placed at the front end of the vacuum pump to prevent excessive water vapor from entering the pump.) ② During the vacuum drying process, the parts of the pipeline where water tends to accumulate can be heated; the duration of this heating depends on the specific conditions on site. 4. Debug and run. ①Confirm that the moisture in the system has been essentially removed. ②Connect the external drying and filtering tank to the system, and replace the desiccant after 5 minutes of operation. At the same time, monitor the unit’s operating parameters and pay attention to the sound emitted by the compressor. If the dryer filter is cold, the expansion valve is frosted, or there is a pressure difference of more than 0.5 kilograms before and after the return air filter, the unit should be stopped immediately. ③ Repeat the above process, continuously replacing the desiccant; the interval between replacements can be increased gradually as the number of replacements increases. (Dry agents: Calcium chloride drying particles have a high water absorption capacity and are used when there is an excess of moisture at the beginning; colored silica gel can accurately detect the moisture content and can be used for drying later on.) ④Finally, replace the desiccant with color-changing silica gel and run it for 24 hours to confirm that the color-changing silica gel retains its original color. 5. Maintenance completed: ① Remove the dryer filter drum of the refrigeration unit and restore the refrigerant lines. ②Check the amount of supplementary refrigerant. Power on the machine and check that its operating parameters are normal. When using electrical equipment, please make sure to keep the environment in which it operates dry and place it in a safe location to prevent water from getting in, so as to ensure its efficient and stable operation.
1) Analyze the reasons. Inspect the entire refrigeration system to determine the cause of water ingress and locate the leak. 2) Segmented fouling blowing. ①The moisture can first be blown away using an air compressor (to save nitrogen), until no water mist is produced. Blow again with high-pressure nitrogen; the nitrogen can be heated while blowing (heating of nitrogen cylinders is prohibited). ②Due to the complexity of the refrigerant system’s pipelines, it is possible, depending on the specific circumstances, to use a welding torch to heat up certain sections of the pipes and blow out the moisture from them. ③Heating and drying: Small components such as capillaries, thermal expansion valves, and compressors can be placed in an oven to be baked and dried. The refrigerant oil must be replaced after the compressor has been dried with water. 3) Vacuum drying: ① Restore the piping, purge with nitrogen to ensure airtightness of the system, then connect a vacuum pump for vacuum drying. (The dry filter tank must be placed at the front end of the vacuum pump to prevent excessive water vapor from entering the pump.) ② During the vacuum drying process, the parts of the pipeline where water tends to accumulate can be heated; the duration of this heating depends on the specific conditions on site. 4) Debug and run. ①Confirm that the moisture in the system has been essentially removed. ②Connect the external drying and filtering tank to the system, and replace the desiccant after 5 minutes of operation. At the same time, monitor the operating parameters of the unit and pay attention to the sound produced by the compressor. If the dryer filter is cold, the expansion valve is frosted, or there is a pressure difference of more than 0.5 kilograms before and after the return air filter, the unit should be stopped immediately. ③ Repeat the above process to continuously replace the desiccant, with the interval between replacements gradually increasing as more replacements are carried out. (Dryants: Calcium chloride drying particles have a high water absorption capacity and are used when there is an excess of moisture at the beginning; colored silica gel can accurately detect the moisture content and can be used for drying later on.) ④Finally, replace the desiccant with color-changing silica gel and run it for 24 hours to confirm that the color-changing silica gel retains its original color. 5) Maintenance completed ① Remove the dry filter tank and restore the refrigerant piping. ②Check the amount of supplementary refrigerant. Power on the machine and check that its operating parameters are normal.
1. Analyze the reasons for water entering the chiller equipment. Inspect the entire refrigeration system to determine the cause of the freezing and identify the leak. 2. Segmental fouling blowing. ①The moisture can first be blown away using an air compressor (to save nitrogen), until no water mist is produced. Blow with high-pressure nitrogen, and the nitrogen can be heated while blowing (heating of nitrogen cylinders is prohibited). ②Due to the complexity of the refrigerant system’s pipelines, it is possible, depending on the specific circumstances, to use a welding torch to heat up certain sections of the pipes and blow out the moisture from them. ③Heating and drying: Small components such as capillaries, thermal expansion valves, and compressors can be placed in an oven to be baked and dried. The refrigerant oil must be replaced after the compressor has been dried with water. 3. Vacuum drying: ① Restore the piping, purge with nitrogen to ensure airtightness of the system, then connect a vacuum pump for vacuum drying. (The dry filter tank must be placed at the front end of the vacuum pump to prevent excessive water vapor from entering the pump.) ② During the vacuum drying process, the parts of the pipeline where water tends to accumulate can be heated; the duration of this heating depends on the specific conditions on site. 4. Debug and run. ①Confirm that the moisture in the system has been essentially removed. ②Connect the external drying and filtering tank to the system, and replace the desiccant after 5 minutes of operation. At the same time, monitor the unit’s operating parameters and pay attention to the sound emitted by the compressor. If the dryer filter is cold, the expansion valve is frosted, or there is a pressure difference of more than 0.5 kilograms before and after the return air filter, the unit should be stopped immediately. ③ Repeat the above process, continuously replacing the desiccant; the interval between replacements can be increased gradually as the number of replacements increases. (Dryants: Calcium chloride drying particles have a high water absorption capacity and are used when there is an excess of moisture at the beginning; colored silica gel can accurately detect the moisture content and can be used for drying later on.) ④Finally, replace the desiccant with color-changing silica gel and run it for 24 hours to confirm that the color-changing silica gel retains its original color. 5. Maintenance completed: ① Remove the dryer filter drum of the refrigeration unit and restore the refrigerant lines. ②Check the amount of supplementary refrigerant. Power on the machine and check that its operating parameters are normal.
1. Analyze the reasons for water entering the chiller equipment. Inspect the entire refrigeration system to determine the cause of the freezing and identify the leak. 2. Segmental fouling blowing. ①The moisture can first be blown away using an air compressor (to save nitrogen), until no water mist is produced. Blow with high-pressure nitrogen, and the nitrogen can be heated while blowing (heating of nitrogen cylinders is prohibited). ②Due to the complexity of the refrigerant system’s pipelines, it is possible, depending on the specific circumstances, to use a welding torch to heat up certain sections of the pipes and blow out the moisture from them. ③Heating and drying: Small components such as capillaries, thermal expansion valves, and compressors can be placed in an oven to be baked and dried. The refrigerant oil must be replaced after the compressor has been dried with water. 3. Vacuum Drying ① Restore the piping, purge with nitrogen to ensure airtightness of the system, then connect a vacuum pump for vacuum drying. (The dry filtration tank must be placed at the front end of the vacuum pump to prevent excessive water vapor from entering the pump.) ② During the vacuum drying process, the parts of the pipeline where water tends to accumulate can be heated; the duration of this heating depends on the specific conditions on site. 4. Debug and run.
I. Analyze the causes: Inspect the entire refrigeration system to determine the reason for the freezing and identify the leakage points. II. Segmental purging: First, use an air compressor to blow out the moisture (to save nitrogen), until no water mist is produced. Blow again with high-pressure nitrogen; the nitrogen can be heated while blowing (heating of nitrogen cylinders is prohibited). Due to the complexity of the refrigerant system’s pipelines, it is possible, depending on the specific circumstances, to use a welding torch to heat up certain sections of the pipes and blow out the moisture from them. Heating and drying: Small components such as capillaries, thermal expansion valves, and compressors can be placed in an oven to be baked and dried. After the compressor has been cleaned with water, its refrigerant oil must be replaced. III. Vacuum drying: Restore the piping, fill it with nitrogen to maintain pressure and ensure the system is airtight, then connect a vacuum pump to carry out vacuum drying. (The dry filter tank must be placed at the front end of the vacuum pump to prevent excessive water vapor from entering the pump.) During vacuum drying, the parts of the pipeline where water tends to accumulate can be heated, with the duration depending on the specific conditions on site. IV. Debugging and operation: Confirm that the moisture in the system has been essentially removed. Connect the external drying and filtering tank to the system, and replace the desiccant after 5 minutes of operation. At the same time, monitor the operating parameters of the unit and pay attention to the sound emitted by the compressor. If the dry filter is cold, the expansion valve is frosted, or there is a pressure difference of more than 0.5 kilograms before and after the return air filter, the unit should be stopped immediately. Repeat the above process to continuously replace the desiccant, with the interval between replacements gradually increasing as more replacements are done. (Dryants: Calcium chloride drying particles have a high water absorption capacity and are used when there is an excess of moisture at the beginning; colored silica gel can accurately detect the moisture content and can be used for drying later on.) Finally, replace the desiccant with color-changing silica gel, and run the system for 24 hours to ensure that the color-changing silica gel retains its original color. V. Repair completed: remove the drying and filtering tank and restore the refrigerant pipeline. Check the amount of supplementary refrigerant. Power on the machine and check that its operating parameters are normal. Precautions: Dry filter drum: Since the gaskets used in external dry filter drums are usually asbestos gaskets, they do not provide a tight seal for the refrigerant. Therefore, it is not allowed to run connected to the system for long periods of time. It should be removed after maintenance is completed to avoid fluorine leakage. Ban on methanol: Adding methanol can raise the freezing point of water and thus prevent ice blockages, but it does not reduce the amount of water in the system. As this water circulates within the system for longer periods, it can degrade the quality of the refrigerant oil, cause copper plating on the metal components of the system, and lead to corrosion of the compressor coils, resulting in electrical leaks that can cause serious injuries or deaths.