45m³ Refrigerated Air Dryer

In modern industrial production, compressed air is an important power source, and its quality has a significant impact on production efficiency, product quality and even equipment life. Untreated compressed air contains a large amount of moisture, oil and solid particles. These impurities will not only corrode pneumatic equipment and block pipelines, but will also directly affect the quality of the final product. As a key device in the compressed air post-processing system, the refrigerated dryer cools and condenses the water vapor in the compressed air into liquid water and discharges it, thereby obtaining clean and dry compressed air. However, many companies often only focus on the selection and installation of refrigerated dryers, but ignore daily maintenance. Little do they know that regular and professional maintenance is the key to ensuring the efficient operation of refrigerated dryers, extending their service life and reducing operating costs. This article will explore the seven core points of daily maintenance of refrigerated dryers in depth, aiming to provide users with a comprehensive and practical maintenance guide to help your refrigerated dryer maintain its best working condition and escort the production of the company.

Condensate is a byproduct that is inevitably produced during the operation of the refrigerated dryer. After the compressed air is cooled, the water vapor contained in it will condense into liquid water. If this water cannot be discharged in a timely and effective manner, it will have a serious impact on the performance and service life of the dryer.

Importance:

Affecting the drying effect: Condensate accumulation will reduce the heat exchange efficiency of the dryer, resulting in an increase in the dew point and poor drying effect of the compressed air.

Corrosion of equipment: Condensate may contain acidic substances, and long-term accumulation will corrode the pipes and components inside the dryer, and even cause equipment damage.

Breeding bacteria: A humid environment is prone to breeding bacteria and microorganisms, affecting the cleanliness of compressed air, which is particularly unfavorable for industries such as food and medicine that have high requirements for air quality.

Increase energy consumption: Excessive condensate will increase the operating load of the dryer, resulting in increased energy consumption.

Damage to the automatic drainer: If the condensate contains oil and impurities, it will block or corrode the float or solenoid valve of the automatic drainer, resulting in poor drainage or even damage.

Specific operation steps:

Manual drain valve: For dryers equipped with manual drain valves, the drain valve should be opened regularly (such as every day, every week or every shift) according to the humidity of the compressed air and the operating environment to completely drain the condensed water. During the drainage process, the flow and color of the drainage should be observed. If the drainage volume is abnormal or milky white liquid appears, it may indicate a problem inside the dryer.

Automatic drainer: Most refrigerated dryers are equipped with automatic drainers, such as float drainers, electronic drainers or time-controlled drainers. Although it is automatic drainage, its working status still needs to be checked regularly.

Inspection frequency: It is recommended to check the working status of the automatic drainer every day and listen for regular drainage sounds.

Manual test: Press the manual test button of the automatic drainer regularly (such as every week or every month) to ensure that it can drain normally. If there is no drainage after pressing the button, or the drainage volume is too small, it means that the drainer may be faulty.

Cleaning the drainer: It is recommended to disassemble and clean the automatic drainer every 3-6 months to remove oil, rust and solid particles in it to prevent clogging. When cleaning, you should pay attention to closing the compressed air inlet valve, and you can operate after the pressure is released.

Precautions:

When discharging condensed water, you should wear protective gloves and goggles to prevent condensed water from splashing.

Condensed water usually contains oil and impurities, and should be properly handled to avoid direct discharge into the environment in accordance with environmental protection requirements.

If the condensed water discharge volume is found to be abnormal, or the condensed water is turbid and has an odor, the cause should be found and resolved in time. It may be that the compressed air contains too much water, the internal components of the dryer are damaged, or the drainer is faulty.

In cold areas in winter, special attention should be paid to the antifreeze problem of condensed water to prevent condensed water from freezing and blocking the pipes or damaging the drainer. You can consider adding heating tape or insulation materials to the drainage pipeline.

A pre-filter is usually installed in front of the refrigerated dryer to remove solid particles, oil and most of the water in the compressed air to protect the dryer from contamination. Cleaning or replacing the filter is an important part of daily maintenance that cannot be ignored.

Importance:

Protect the dryer: The pre-filter can effectively block pollutants entering the dryer, preventing these pollutants from attaching to the heat exchanger fins, affecting the heat exchange efficiency, or entering the refrigeration system, causing refrigerant contamination.

Ensure the drying effect: Clean compressed air can pass through the dryer more effectively, ensuring that the dew point meets the design requirements. If the filter is clogged, it will cause poor airflow and affect the drying effect.

Reduce energy consumption: A clogged filter will increase airflow resistance, causing the compressor to require a higher pressure to deliver air into the system, thereby increasing the energy consumption of the compressor.

Extend equipment life: Reduce the wear and corrosion of pollutants on the internal components of the dryer and extend the service life of the dryer.

Specific operation steps:

Check the differential pressure gauge: Most filters are equipped with a differential pressure gauge. By observing the differential pressure gauge, you can determine whether the filter needs to be cleaned or replaced. When the differential pressure reaches a certain value (usually 0.5-0.7bar), it means that the filter element is clogged and needs maintenance.

Clean the filter element: For washable filter elements (such as activated carbon filter elements), they can be cleaned according to the manufacturer’s instructions. Usually rinse with neutral detergent and clean water, then dry thoroughly. Be careful not to use strong acid and alkali solutions to clean, so as not to damage the filter material.

Replacement of filter element: For non-washable filter elements (such as precision filter elements), once the service life is reached or the pressure difference is too high, it must be replaced immediately. Different types of filter elements have different replacement cycles, which should be determined by referring to the manufacturer’s recommendations or according to actual operation conditions. It is usually recommended to replace it every 6 months to 1 year.

Operation process: Before cleaning or replacing the filter element, be sure to close the compressed air inlet valve and drain the pressure inside the filter to ensure safe operation. When removing the filter housing, be careful to place it gently to avoid damaging the seal. When installing a new filter element, pay attention to the direction and ensure a good seal.

Precautions:

Never use a filter element that does not match the original filter element model to avoid affecting the filtering effect or damaging the equipment.

Regularly check the filter housing for leaks and replace aging seals in time.

For oil-water separators, the separated oil-water mixture should be discharged regularly to prevent secondary pollution.

In environments with more dust or heavy oil mist, the inspection and replacement cycle of the filter should be appropriately shortened.

It is recommended to equip spare filter elements for timely replacement to avoid production being affected by waiting for the arrival of filter elements.

The refrigerated dryer uses the refrigeration system to reduce the temperature of compressed air, so the normal operation of the refrigeration system is the key to the performance of the dryer. Checking the refrigerant pressure and refrigerant quantity is an important part of daily maintenance.

Importance:

Impact on refrigeration effect: Too high or too low refrigerant pressure, as well as insufficient or excessive refrigerant quantity, will directly affect the efficiency and refrigeration effect of the refrigeration system, resulting in an increase in dew point and a decrease in drying effect.

Increased energy consumption: Abnormal operation of the refrigeration system will cause the compressor to run for a long time, increasing energy consumption.

Damage to the compressor: Insufficient refrigerant quantity may cause the compressor to overheat or even burn; excessive refrigerant quantity will increase the load on the compressor and shorten its life.

Leakage risk: Refrigerant leakage will not only affect the performance of the equipment, but also pollute the environment. Some refrigerants also have a greenhouse effect.

Specific operation steps:

Observe the pressure gauge: Refrigerated dryers are usually equipped with high-pressure and low-pressure gauges to display the operating pressure of the refrigeration system. Under normal operating conditions, high pressure and low pressure should be within the range specified by the manufacturer.

High pressure is too high: Possible reasons include: too high ambient temperature, poor heat dissipation, dirty condenser, too much refrigerant, too much expansion valve opening, etc.

High pressure is too low: Possible reasons include: refrigerant leakage, too small expansion valve opening, insufficient compressor suction, etc.

Low pressure is too high: Possible reasons include: too large expansion valve opening, too much refrigerant, reduced compressor efficiency, etc.

Low pressure is too low: Possible reasons include: refrigerant leakage, expansion valve blockage, evaporator frosting, insufficient compressor suction, etc.

Check the liquid level sight glass (some models): Some large refrigerated dryers have a liquid level sight glass, and you can judge whether the refrigerant is sufficient by observing the bubbles in the sight glass. If there are too many bubbles, it may mean that the refrigerant is insufficient; if the sight glass is always full of liquid, it may mean that the refrigerant is too much.

Auscultation: Listen carefully to the running sound of the refrigeration compressor. The normal compressor sound should be smooth and continuous. If there is an abnormal noise, such as the sound of liquid impact, it may indicate that there is too much refrigerant; if there is a “hissing” sound of suction, it may indicate that there is insufficient refrigerant or there is a leak.

Regular leak detection: It is recommended to use a professional leak detector to regularly detect leaks in the refrigeration system, especially when the refrigerant pressure is abnormal or a leak is suspected. Leaks usually appear in welding ports, valves, connectors and other parts.

Replenish or replace refrigerant: If it is confirmed that the refrigerant is insufficient, ask a professional to replenish it. Before replenishing the refrigerant, the leak must be found and repaired. If the refrigerant is contaminated or needs to be replaced, ask a professional to vacuum and refill it.

Precautions:

The refrigeration system involves high pressure and refrigerant, and improper operation may cause danger. Non-professionals should not operate it privately.

Before performing any refrigeration system maintenance, be sure to ensure that the equipment is powered off and wear protective equipment.

Record the pressure data of each inspection to track the trend of changes and detect problems in time.

Different models of refrigerated dryers may have different refrigerant types and charge amounts, and should be operated strictly in accordance with the manufacturer’s instructions.

There are multiple heat exchangers inside the refrigerated dryer, including the precooler, evaporator and condenser. The cleanliness of these heat exchangers directly affects the refrigeration efficiency and overall performance of the dryer.

Importance:

Affecting heat exchange efficiency: If dust, oil or impurities accumulate on the surface of the heat exchanger, a heat insulation layer will be formed, which will seriously affect the heat transfer efficiency, resulting in a decrease in refrigeration effect and an increase in dew point.

Increasing energy consumption: A decrease in heat exchange efficiency will cause the refrigeration compressor to work longer and under greater load, thereby increasing power consumption.

Damaged parts: Severe dirt and blockage may cause excessive pressure inside the heat exchanger and even cause pipeline rupture.

Shortening equipment life: Long-term operation at low efficiency will accelerate the aging of refrigeration system components and shorten the service life of the dryer.

Specific operation steps:

Condenser (air-cooled): For air-cooled condensers, their fins are prone to accumulate dust and flocs in the air.

Inspection frequency: It is recommended to inspect the condenser fins once a month.

Cleaning method: You can use compressed air or a soft brush to blow or brush away dust from top to bottom and from inside to outside. For heavy oil stains, you can use a special cleaning agent to spray and then rinse with clean water, but be careful to avoid water splashing on electrical components. Be sure to dry thoroughly after rinsing.

Evaporator (plate-fin or shell-and-tube): The inside of the evaporator is a channel for compressed air to flow through, and it is also easy to accumulate oil and solid particles.

Inspection frequency: It is recommended to check the evaporator every 6 months to 1 year.

Cleaning method: For plate-fin evaporators, it is usually necessary to remove the outer shell and clean the fins with compressed air or a soft brush. For shell-and-tube evaporators, if the internal blockage is found to be serious, chemical cleaning or disassembly and cleaning may be required, which usually requires professional operation.

Precooler (plate-fin or shell-and-tube): The cleaning method of the precooler is similar to that of the evaporator.

Operation safety: Before cleaning the heat exchanger, be sure to disconnect the power supply of the dryer and wait for the equipment to cool down. When using high-pressure air or a water gun, pay attention to moderate pressure to avoid damaging the heat exchanger fins.

Precautions:

When cleaning the heat exchanger, be gentle to avoid damaging the weak fins, otherwise it will affect the heat exchange efficiency.

For water-cooled condensers, in addition to external cleaning, it is also necessary to regularly check the quality of the cooling water to prevent scale from forming in the tubes and affecting heat exchange. Pickling and descaling can be performed if necessary.

Make sure the surface of the heat exchanger is dry after cleaning before restarting the equipment.

If a large area of the heat exchanger fins is found to be lodged or damaged, they should be repaired or replaced in time.

Record the time and situation of each cleaning to master the maintenance cycle.

The electrical system and control system are the brain and nerves of the refrigerated dryer, and their stable operation is crucial to the overall performance of the dryer.

Importance:

Ensure equipment safety: Electrical failures may cause dangers such as short circuits, overloads, leakage, and even fires.

Ensure normal operation of the equipment: The control system is responsible for monitoring and adjusting the various operating parameters of the dryer. Once a failure occurs, the dryer may not work properly or work inefficiently.

Extend the life of electrical components: Regular inspection and maintenance can detect and eliminate potential electrical hazards and prevent premature damage to components.

Improve fault diagnosis efficiency: Complete electrical inspection records help to quickly locate and troubleshoot faults.

Specific operation steps:

Check the power connection: Check whether the power cord, plug, and socket are loose, damaged, or aged. Ensure that the wiring is firm and there is no false connection.

Check the contactor and relay: Check whether the contactor contacts are burned or oxidized, and whether the pull-in is normal. Check whether the relay coil is overheated or has odor.

Check the fuse and circuit breaker: Check whether the fuse is intact and whether the circuit breaker can trip and reset normally.

Check the terminal: Check whether all the terminal blocks in the control cabinet are loose, especially the terminal blocks of the high current circuit.

Check the sensor: Check whether the temperature sensor, pressure sensor, dew point sensor, etc. are firmly installed and the leads are intact. Calibrate the sensor regularly to ensure accurate measurement.

Check the control panel and display: Check whether the buttons and indicator lights on the control panel are working properly and whether the display is clear and fault-free.

Check the control program: If the dryer has a programmable controller (PLC), it is recommended to back up the control program regularly and check whether the program runs normally and whether there are any abnormal error messages.

Clean the control cabinet: Use a vacuum cleaner or dry cloth to clean the dust inside the control cabinet regularly and keep the electrical components clean.

Notes:

All electrical inspections must be carried out under power-off conditions and ensure that the equipment has completely stopped running.

Non-professional electricians should never disassemble or repair electrical components at will.

During the inspection process, attention should be paid to moisture and dust prevention to prevent water and debris from entering the electrical components.

If electrical components are found to be burnt, have an odor or make abnormal sounds, the equipment should be stopped immediately and professionals should be asked to check and repair them.

Keep the electrical schematics and wiring diagrams for fault diagnosis and repair.

Although the refrigerated dryer does not have a large number of moving parts like some mechanical equipment, its refrigeration compressor and some parts such as the fan of the air-cooled condenser still need proper lubrication.

Importance:

Reduce wear: Proper lubrication can effectively reduce friction and wear between moving parts and extend the service life of components.

Reduce noise: Insufficient lubrication will increase the noise of components and affect the working environment.

Improve efficiency: Good lubrication can ensure smooth operation of components and improve the overall operating efficiency of the equipment.

Prevent overheating: Lubricating oil can also play a role in heat dissipation and prevent components from overheating.

Specific operation steps:

Refrigeration compressor: Most refrigerated dryers use fully enclosed or semi-enclosed refrigeration compressors, whose lubricating oil is filled at the factory and does not need to be added or replaced under normal operation. However, when performing refrigeration system maintenance (such as replacing the compressor and dealing with major leaks), it may be necessary to check or replace the lubricating oil. This work must be performed by professionals using special tools.

Fan motor (air-cooled): For fans used in air-cooled condensers, their motor bearings may need to be lubricated regularly.

Inspection frequency: It is recommended to check the fan motor bearings every 6 months to 1 year.

Lubrication method: According to the motor type and manufacturer’s instructions, use appropriate grease or lubricating oil to fill the lubrication hole of the bearing. Be careful not to overfill to avoid waste or pollution.

Other moving parts: If there are other moving parts in the dryer that need lubrication (such as the mechanical structure of some old-style drain valves), they should be regularly inspected and lubricated according to the manufacturer’s instructions.

Notes:

Be sure to use special lubricating oil or grease that is compatible with the equipment. Different types of lubricants may not be mixed.

Before lubrication, the parts to be lubricated should be cleaned to avoid dust and impurities.

The amount of lubrication should be moderate. Too much or too little may affect the effect.

For the replacement of refrigeration compressor lubricating oil, it must be operated by qualified professionals and strictly follow the operating procedures.

Record the date of each lubrication and the type of lubricant used.

Establishing a complete operating data record and regular calibration system is an important means to achieve predictive maintenance, optimize equipment operation, and extend equipment life.

Importance:

Trend analysis: By recording operating data for a long time, you can analyze the operating trend of the equipment and discover potential problems in advance. For example, if the dew point continues to rise, it may indicate that the efficiency of the refrigeration system is declining or the filter is clogged.

Fault diagnosis: When the equipment fails, detailed operation data records can help maintenance personnel quickly locate the cause of the fault and shorten the maintenance time.

Optimize operation: Through the analysis of data, the deficiencies in the operation of the equipment can be found, so as to adjust the operating parameters and optimize energy efficiency.

Extend life: Timely discover and solve small problems to prevent them from developing into major faults, thereby effectively extending the service life of the equipment.

Compliance with regulations: For some industries, it may be necessary to provide equipment operation records and calibration reports to comply with relevant regulations and standards.

Specific operation steps:

Record content: It is recommended to record the following key operating data:

Inlet temperature, pressure

Outlet temperature, pressure

Dew point temperature (the most important indicator)

Refrigeration system high pressure, low pressure

Ambient temperature

Compressor operating current

Filter pressure difference

Automatic drainer drainage

Maintenance date, content and person in charge

Any abnormal phenomena and treatment measures

Recording frequency: Record operation data at least once a day, and the recording frequency can be increased under special circumstances.

Recording method: You can use a paper record book, spreadsheet or professional equipment management system for recording.

Regular calibration: Key measuring instruments, such as thermometers, pressure gauges, dew point meters, etc., should be regularly sent to professional metrology institutions for calibration to ensure their measurement accuracy. The calibration cycle is usually 1 year.

Professional inspection: It is recommended to ask a professional refrigerated dryer maintenance service provider to conduct a comprehensive inspection and maintenance of the equipment at least once a year, including professional inspection, calibration and necessary adjustments to the refrigeration system.

As an important part of the compressed air system, the daily maintenance of the refrigerated dryer is by no means an optional link, but the cornerstone to ensure its efficient and stable operation, extend the service life of the equipment, and reduce operating costs. Through the seven key points of regularly checking and discharging condensed water, cleaning or replacing air filters, checking the pressure and refrigerant volume of the refrigeration system, cleaning the heat exchanger, checking the electrical system and control system, lubricating moving parts, and recording operating data and regular calibration, enterprises can significantly improve the performance of refrigerated dryers, reduce the occurrence of failures, and provide continuous, stable, and high-quality dry compressed air for production.

Investing time and resources in professional maintenance may seem to increase costs, but in the long run, it can effectively avoid production stoppages, high repair costs, and the risk of product quality damage caused by equipment failure. Remember, a meticulous routine maintenance plan is not only responsible for the equipment, but also an investment in corporate productivity, product quality, and economic benefits. Let us start from now on and pay attention to the routine maintenance of the refrigerated dryer, so that it can become a reliable and efficient “air guardian” on your production line!