Internal structure diagram and user manual of the refrigerated compressed air dryer (for direct reference, no download required)

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The last edit to this post was made by 4 a.m on 2010-6-19 at 11:08: http://bbs.bjx.com.cn/data/attachment/forum/month_1006/1006191108d584d08f9df27af0.jpg 1.0 Overview 1.1 Working Principle of Refrigerated Dryers The JRL series of refrigerated compressed air dryers operate based on the principle of air freeze-drying; they use refrigeration equipment to cool the compressed air to a certain dew point temperature, causing the water contained in it to precipitate out. Subsequently, a separator is used to separate the gas from the liquid, and an automatic drain valve is then used to remove the water. Thus, the purpose of freeze drying is achieved. At the same time, solid dust particles of 3 μm and larger, as well as trace amounts of oil, are removed from the compressed air, ensuring that the quality of the air supply meets the requirements for cleanliness and dryness. 1.2 Process flow sequence: The operation of the JRL series of products is divided into two parts: the air system and the refrigeration system. Air system: Compressed air containing moisture and oil enters the gas-to-gas heat exchanger, where it is pre-cooled to reduce its temperature and some of the moisture is removed. It then enters the gas-to-refrigerant heat exchanger, where it is cooled to a dew point temperature of 2–100°C. Water, oil, and certain impurities are condensed here. The cooled gas, along with the condensed water, oil, and impurities, is separated using a gas-liquid separator; thereafter, the water and oil are removed through automatic drain valves. The dried compressed air is then heated using a gas-to-gas heat exchanger before being discharged, thereby effectively preventing the occurrence of \"sweating\" in the pipelines. Refrigeration system: The low-temperature liquid refrigerant absorbs heat in the gas-to-refrigerant exchanger and evaporates into a gaseous state. The gaseous refrigerant then passes from the refrigerant outlet of the exchanger, through a vaporizer and a suction filter, to the suction inlet of the refrigeration compressor. The vaporizer and suction filter are designed to prevent liquid refrigerant and impurities from entering the compressor. The compressor compresses the low-temperature, low-pressure refrigerant into a high-temperature, high-pressure gas. Depending on the automatic regulation by the bypass valve, a small portion of this gas goes directly to the gas-to-refrigerant heat exchanger, while most of it enters the condenser where it is condensed and cooled. The low-temperature liquid refrigerant that emerges from the condenser passes through a receiver and a dryer filter before reaching the expansion valve. The function of the reservoir and the condenser is to ensure that the refrigerant is in a pure liquid state at the inlet of the expansion valve. The liquid refrigerant expands and enters the gas-to-refrigerant heat exchanger, where it cools the compressed air, thus initiating a new cycle. As the load increases, the temperature and pressure of the refrigerant in the refrigerant heat exchanger rise; the sensor signal from the expansion valve then controls the expansion orifice to open wider until a new equilibrium is reached. When the load is too low, the bypass valve automatically provides an artificial load to the gas-to-refrigerant heat exchanger to prevent the suction pressure from becoming too low. Features: 1. The refrigeration compressors are high-temperature, hermetically sealed types from companies such as TECUMSEH and BRISTOL in the United States, as well as MANEURCP in France; they operate with low noise, consume less electricity, and have a long service life. 2. All refrigeration control components are products from renowned European and American companies. The electrical appliances use Schneider products, offering reliable performance. 3. Automatic thermal compensation for underload. 4. High-efficiency copper tubes shall be used for the copper tubes in heat exchangers and evaporators. 5. Use a float-type or electromagnetic timed drain, equipped with an anti-clogging device to prevent the automatic drain from getting clogged. 6. The equipment features a reasonably designed structure and an attractive appearance; it dynamically displays operating parameters and requires no foundation for installation. Schematic diagram of the operation of a refrigerated compressed air dryer: 1. Refrigeration compressor; 9. Energy control valve; 17. Drainage anti-clogging filter; 2. Condenser (water-cooled); 10. Vaporizer; 18. High-pressure gauge for refrigerant; 3. Condenser (air-cooled); 11. Filling valve; 19. Water flow control valve; 4. Drying filter; 12. Low-pressure gauge for refrigerant; 20. Water quality filter; 5. Capillary tube (used for capacities below 10 M3); 13. High/low pressure switch; 21. Manual valve; 6. Thermostatic expansion valve; 14. Evaporator assembly; 22. Automatic drain device; 7. Gas-liquid mixer; 15. Air pressure gauge; 23. Pre-cooler (used in high-temperature water-cooled dryers); 8. Liquid separator; 16. Digital temperature controller (used for capacities above 10 M3); 24. Pre-cooler (used in high-temperature air-cooled dryers). Explanation of model numbering: For example, JRL-1NF denotes a normal-temperature air-cooled dryer with a processing capacity of 1 Nm3/min. JRL-6HTW refers to a high-temperature water-cooled refrigerated dryer with a processing capacity of 6 Nm3/min. 3.0 Configuration and Installation 1. Configuration recommendations (see figure below): (1) When the exhaust temperature of the air compressor exceeds 80 °C, a rear cooler should be installed ； (2) If a reciprocating air compressor is installed before the refrigerated dryer, a surge tank should be provided; this helps to eliminate vibrations caused by airflow pulsations ； (3) To maintain the heat exchange efficiency of the heat exchanger, a pre-filter should generally be installed ； (4) If the process gas supply must not be interrupted, a bypass valve should be installed in the system (rear cooler, cold dryer). (5) The filter for the outlet air of the refrigerated dryer should be selected based on the user’s air usage requirements. 2. Installation requirements: (1) Environmental requirements — 1) The maximum ambient temperature for installation should generally not exceed 35 ℃ ； 2) The installation location should have good ventilation, but it should not be installed outdoors ； 3) The installation environment should be dry, not humid ； 4) The installation location should be chosen to facilitate maintenance, and it should be kept level to avoid affecting the drainage of condensate water. (2) Pipeline requirements — 1) Filters should be installed before and after the refrigeration dryer ； 2) When connecting the refrigerated dryer to the piping system, care should be taken to prevent it from being subjected to vibrations ； 3) The diameter of the pipes to be installed should not be smaller than the diameter of the inlet and outlet pipes of the cold dryer ； 4) The installed pipes should be avoided being too thin or too long, to prevent water from accumulating inside them. 3. Installation of the drain: Drains can be divided into electronic drains (with timing function) and automatic drains. 4. Power distribution requirements and methods — (1) A separate power switch should be provided ； The voltage should be set according to the values specified on the nameplate and the number of phases. (2) Do not share a protective device with other equipment, and the voltage fluctuation range must not exceed 10% of the rated voltage. (3) The cables used should not be too thin or too long, to avoid voltage drops ； (4) The shell of the cold dryer should be reliably grounded, and the grounding wire should be connected to the bolt marked with a grounding symbol. (5) The power supply voltage for cold dryers with a capacity of 10 m3 or less is 220V/50HZ, while that for cold dryers with a capacity of 10 m3 or more is 380V/50HZ. (6) When connecting power, first introduce the power cable into the electrical box. For 220V systems, there are three power supply wires. In this case, it’s necessary to distinguish between the power supply wires and the grounding wire. Then, open the small transparent cover at the wiring area inside the electrical box, and connect the power supply wires to the available terminal blocks (usually located on the far right). Then connect the ground wire to the terminal marked with a ground symbol. The standard 380V wiring consists of five wires (three power wires, and one neutral wire and one ground wire), and the wiring method is the same as described above. (Note: Do not connect wires while powered on! ) 5. Precautions for safe use: (1) Check whether ventilation, voltage, wiring, and grounding protection are correct and in good condition ； (2) Check whether the inlet air temperature and pressure are normal ； (3) Power must be cut off before maintenance ； (4) Before maintenance or disassembly, the air lines and refrigeration system must be depressurized ； (5) Check whether the fan is operating normally ； (6) Check for any leaks in the refrigerant. The method is as follows: After running the unit without a load for 10 minutes, check whether there is a large temperature difference between the suction and exhaust ports of the refrigerator; the exhaust temperature should be significantly higher than the suction temperature ； (7) Under normal conditions, it is possible to start the machine first; after a few minutes, the air compressor can be turned on, followed by gradually opening the intake valve (while closing the bypass valve) ； (8) After running for 30 minutes, check whether the drainage system is functioning properly. 6. Precautions for the daily maintenance of refrigerated dryers: (1) It is strictly prohibited to frequently turn the refrigerator on and off; after each operation, a minimum interval of 3 minutes must be observed ； (2) Regularly clean the exterior of the cold dryer, and pay attention to the drainage condition of the drain. (3) The refrigeration unit should be avoided from running idle for long periods of time ； (4) The air-cooled condenser should be regularly cleaned of dust and dirt to avoid affecting its cooling efficiency. The specific methods for maintaining air-cooled condensers are as follows: ① Blow with compressed air; ② Clean using a soft wire brush or brush, but be careful not to damage the cooling fins and cause them to bend. ③The air filter is a vulnerable component of this machine; it needs to be cleaned and maintained regularly to prevent blockage and loss of functionality ； ④Pay regular attention to whether the refrigeration unit is operating properly; its operation should be smooth without any abnormal noises ； ⑤Pay attention to the temperature difference between the air inlet and outlet; the normal temperature difference is 10–30℃ ； ⑥Note that the ambient temperature where the refrigerated dryer is located should not be lower than 10°C; otherwise, the refrigeration oil may not be replenished in time, leading to oil starvation and subsequent damage to the refrigerator. The specific methods for maintaining a water-cooled condenser are as follows: The water filter is used primarily to prevent impurities settled in the cooling water from entering the condenser and causing blockages in the cooling water pipes. Since its filter mesh can easily get clogged by these sedimented impurities, it should be cleaned regularly to avoid insufficient water circulation, which would prevent heat from being dissipated. (5) When the unit is shut down, the internal components of the refrigerated dryer should be regularly cleaned by vacuuming. (6) Always ensure that there is good ventilation around the unit on all sides, and avoid direct sunlight and any heat sources. (7) During maintenance, care should be taken to protect the refrigeration system to avoid damage. (8) Key points for cleaning the drain valve: Schematic diagram for cleaning the automatic drain valve. 1) Close the ball valve located before the drain valve, loosen the fixing screws on the drain valve cover, and release the compressed air inside the drain valve. 2) Release the drainer housing cover, then remove the drainer core and clean it thoroughly with water and a soft brush. (Use of gasoline, toluene, or turpentine as cleaning solvents is strictly prohibited.) 3) Install the cleaned drain core into the valve body, then attach the drain cover, and finally open the ball valve at the front end. 4) For the inverted barrel type drain, it must be filled with clean water to create a water seal before it can function. A slight amount of air leakage during operation is normal. (9) After being in use for a period of time, the Y-type filters located at the cooling water inlet and in front of the automatic drain will have impurities accumulate in their filter elements, which increases the flow resistance ahead of the filters, affects the water flow rate, and causes poor drainage. Therefore, these filter elements should be cleaned and replaced regularly. The newly installed equipment requires frequent inspection and cleaning due to dirty pipelines. 4.0 Operating Procedures for the JRL Series Freeze-Dryers I. Checks before starting up 1. Check whether the power supply voltage is normal ； (JRL-10NF/JRL-10NW and below are ∮220VAC+5%) ； For JRL-10NF and above, it is 3∮380VAC +5%. 2. Observe the refrigeration system: Check the high and low pressure gauges for the refrigerant; these gauges reach a basic equilibrium at certain pressures, with this equilibrium value fluctuating depending on the surrounding temperature, generally ranging between (0.5MPa and 1.0MPa). 3. Check whether the air pipeline is in good condition; the air inlet pressure must not exceed 1.0 MPa (except for special models), and the inlet air temperature should preferably not exceed the value specified during selection. 4. If a water-cooled system is selected, it is also necessary to check whether the cooling water is normal. The water pressure should be 0.2–0.4 MPa, and the water temperature should be ≤32°C. Open the cooling water inlet valve. 5. The compressed air pipeline system must be purged before startup to prevent debris from entering the dryer and filters and affecting their performance. II. Operating method of the refrigerated dryer: (1) Description of the control panel In the diagram: (See Figure 3) 1 – Refrigerant low-pressure gauge. Indicates the saturated pressure value of the refrigerant inside the evaporator. (Not applicable for 10 m³ and below) 2 – Refrigerant high-pressure gauge, indicating the condensation pressure value of the refrigerant. (None for below 10 m3) 3 — Air pressure gauge, indicating the pressure of compressed air at the outlet of the cold dryer. 4 – Pressure dew point gauge, indicating the dew point temperature of the compressed air after being cooled and dehumidified by the refrigerated dryer. 5——Intake air temperature (digital display), indicating the temperature of the air entering the cold dryer. (None for 10 m3 and below) 6——STOP button: Pressing this button stops the refrigerated dryer from operating. 7 —— Start button (START): Pressing this button supplies power to the refrigerated dryer, and it begins to operate after six minutes. 8—Power indicator light (POWER). When this light is on, it indicates that the power supply is connected. 9—Run indicator light (RUN). When this light is on, it indicates that the refrigerated dryer is in operation. 10 — Refrigerant high and low pressure protection trip indicator light (REF H.L.P). When this light is on, it indicates that the high and low pressure protection switches inside the refrigeration dryer have tripped, and the machine needs to be shut down for inspection. Press the shutdown button again at this time. (Not available for volumes below 10 m3) 11 – Current overload protection trip indicator light (O.C.TRIP). When this light is on, it indicates that the operating current of the compressor is overloaded, the overload relay has tripped, and the machine needs to be stopped for inspection. Press the shutdown button again at this time. (None for below 10 m3) At this time, the low-pressure gauge of the refrigerant indicates a value within the range of 0.3–0.5 MPa. The high-pressure gauge for the refrigerant indicates a value within the range of 1.2 to 1.6 MPa. (II) Operating procedure of the cold dryer: 1. Turn on the air switch to supply power; at this point, the POWER indicator light (red light) on the panel will turn on. 2. If it is water-cooled, open the inlet and outlet valves for cooling water ； 3. At this point, press the green START button; the time relay starts to operate. After a 3-minute delay, the contactor closes, the RUN indicator light (green) lights up, and the compressor begins to run ； 4. Check whether the compressor is operating normally, if there are any abnormalities, and whether the high- and low-pressure gauges for the refrigerant indicate normal values ； 5. Assuming everything is normal, turn on the air compressor or the inlet and outlet valves to supply air to the cold dryer, and close the air bypass valve; at this point, the air pressure gauge will indicate the pressure at the air outlet ； 6. After observing for 5–10 minutes, the air treated by the refrigerated dryer meets the usage requirements. At this point, the low-pressure gauge for the refrigerant indicates a value in the range of 0.3–0.5 MPa, while the high-pressure gauge shows a value between 1.2–1.6 MPa. The dew point temperature gauge reads between 2–10°C (except for special requirements) ； 7. Open the ball valve on the automatic drain to allow the condensation water in the air to flow into the drain, from where it is then discharged outside the machine. 8. When shutting down the machine, first turn off the air supply, then press the red STOP button to shut down the refrigerated dryer, and cut off the power supply. 5. Causes and Solutions for Failures in Refrigerated Dryers: The failures that can occur due to issues with the refrigerator dryer itself or external factors include the following:

1. Complete failure to operate:
- **Condition**: No operation.
- **Causes**: Power supply issues, blown fuses, or no fuse in place; poor grounding of the power supply; damaged fuse switches; broken wires.
- **Solutions**: Check if there is a proper power supply; replace blown fuses; ensure proper grounding; repair broken wires.

2. Poor performance after startup:
- **Condition**: Poor performance after starting up.
- **Causes**: Abnormal voltage; short circuits in the wires shortly after startup, resulting in a burning smell; overload; continuous startups – wait at least 3 minutes between each startup; compressor overload; dryer overload, requiring reduced air handling capacity; too high inlet temperature of the dryer – install additional coolers or improve ventilation; too low setting of the thermal protector – adjust the setting; poor power connections – clean or replace them; faulty contacts – clean or replace them.

3. Problems with the automatic drainage system:
- **Condition**: Poor drainage.
- **Causes**: Operating pressure below 1.5 kgf/cm2; the minimum operating pressure for the automatic drain is 1.5 kgf/cm2; blockage in the automatic drain built into the air filter – clean or replace it; the air filter is tilted or its filters are blocked – adjust its position, clean, or replace it.

4. Normal operation but poor performance:
- **Condition**: Normal operation but suboptimal results.
- **Causes**: Too low outlet temperature of the evaporator; leaks in the condenser – repair the leaks and then refill with refrigerant; blockage in the refrigerant lines – replace the desiccant, evacuate again, and refill with refrigerant; too high outlet temperature; too high inlet temperature (above 80°C) – improve the exhaust temperature of the air compressor; blockage in the condenser – clean it; excessive air handling capacity with pressure below 4 kgf/cm2 – control the air flow; worn valves in the refrigerant compressor – replace them.

5. Poor water removal by the refrigerator dryer:
- **Condition**: Poor water removal.
- **Causes**: Errors in the piping system; bypass valves not fully closed – close the bypass valves; air not passing through the dryer – close the bypass valves and open the inlet and outlet valves of the dryer; the dryer not placed level – level it; the automatic drain is tilted – level it; excessive air flow; high heat load – redesign the air source; problems with the drainage system – clean or replace the drain; abnormal outlet temperature of the evaporator; dew point too low or too high – adjust the pressure switch; high ambient temperature – it’s okay to continue using the dryer; too high inlet temperature – install additional coolers or improve the inlet air temperature; refrigerant leaks, resulting in poor cooling effect – repair the leaks and refill with refrigerant.

6. Excessive pressure drop:
- **Condition**: Excessive pressure drop.
- **Causes**: Errors in the piping system; valves not fully open – close the valves; too small pipe diameter – increase the diameter; pipes too long with too many bends and connections – redesign the piping system; blockage in the filters in the pipes – replace the filters; excessive air leakage at pipe connections – check the bends and connections; air handling capacity exceeding the rated value – since the flow rate exceeds the dryer’s capacity, pressure naturally drops.
- Solutions: Replace the dryer with one of higher capacity; reduce the air flow rate.
- Condensation water freezing inside the evaporator; faulty temperature switches – replace them, check the wiring, and adjust the switches