Should an air compressor be equipped with a refrigerated dryer?

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Air compressors are common equipment in the manufacturing industry, with over 99% of manufacturing companies using them. However, many companies still do not know how to select the right air compressor for their needs. Before purchasing the right type of air compressor, one should consider the following questions: In which areas of the enterprise is compressed air needed? (Gas demand) What is the typical gas consumption of enterprises? What is the normal pressure in the workshop? How many hours per year do compressors operate in enterprises? Does the enterprise production require dry/clean compressed gas? Is there any fluctuation in the company’s gas consumption? Is a backup machine needed? Are there any plans for expansion in the future? Today, we will focus on an issue that many people overlook: \"Does your business require dried/clean compressed air for production?\n\" ” Many people believe that only industries with high demands for compressed air, such as the food and pharmaceutical industries, need dried and clean gas. Many beginners in the field of air compressors are not aware that untreated compressed air contains a large amount of moisture. Why do water molecules form during the air compression process? The air around us contains various gases and water vapor; it is essentially moist air. When air is compressed, the water vapor present in each unit volume of air is condensed into water due to the increased pressure (in other words, the volume of the compressed air decreases, and it can no longer hold as much water vapor). If the compressed air and water molecules separated by pressure are not treated, an excess of water molecules will remain in the pipes along with the compressed air, which can severely disrupt the proper operation of equipment. It can also cause corrosion of machinery and components, leading to damage to pneumatic parts. In winter, in the north, once the temperature drops to zero degrees, liquid water freezes into ice, resulting in ice blockages (accumulation of water inside compressed air pipes). Operating principle of freeze-dryers A. Working principle: As the temperature drops, the moisture-holding capacity of air decreases, and the water that was originally in gaseous form turns into liquid. Freeze-dryers work by cooling compressed air, causing the water vapor contained in it to condense into liquid droplets. This process reduces the moisture content of the compressed air, and the resulting liquid droplets are removed from the device through an automatic drainage system. Before leaving the refrigerated dryer, the air is reheated by a heat exchanger, resulting in relatively dry compressed air (this feature is available only in twin-tower refrigerated dryers). B. Workflow: Compressed air system: 1. When compressed air enters ① Integrated Evaporator A, it undergoes heat exchange with the dry cold air discharged from B, thereby pre-cooling the compressed air entering B ； 2. The pre-cooled compressed air then enters the evaporator section of integrated evaporator B to exchange heat with the refrigerant; at this point, the temperature of the compressed air drops to an optimal level equal to the condensation temperature of the refrigerant. The water vapor in the compressed air then condenses into a liquid, settles at the bottom of the evaporator, and is discharged through the automatic drain solenoid valve ； 3. After dehydration, the compressed air flows from stream B to stream A for heat exchange; this warms the low-temperature compressed air exiting stream B by the hot compressed air entering stream A, resulting in relatively dry compressed air ； 4. The dry compressed air discharged from the compressed air outlet can flow into the next downstream treatment unit for further purification, or it can be directly supplied to end-use equipment ； Refrigeration system: 1. The refrigeration compressor ① is the main component that provides the power necessary for the refrigerant to circulate within the refrigeration system. The compressed refrigerant, which is at high temperature and pressure, flows to the condenser ② where it is cooled. There, the refrigerant cools down and condenses under pressure into a high-pressure liquid state ； 2. The high-pressure liquid refrigerant passes through the dryer-filter ⑤ to be filtered and dried, removing particles and trace amounts of moisture from the refrigerant in order to prevent clogging of the throttle element, namely the capillary ③, or ice buildup at the outlet of the capillary ； 3. The high-pressure liquid refrigerant ⑤, after flowing through the capillary tube ③, is throttled, thereby creating a pressure drop as it enters the evaporator ④; this allows sufficient space in the evaporator for the liquid refrigerant to turn into gas ； (The process by which liquid refrigerant turns into gas is called evaporation.) 4. The liquid refrigerant, after being throttled by capillary tube ③, flows into the integrated evaporator ④ of the B evaporation system. Meanwhile, the compressed air that has been pre-cooled in section A also flows into section B. There, the compressed air exchanges heat with the refrigerant; the refrigerant absorbs heat from the compressed air, changing from a liquid to a gas. It then flows into the suction side of the refrigeration compressor ①, thus completing the refrigeration cycle ； 5. When the evaporation temperature is too low, the condensed water from the compressed air flowing into B may freeze, leading to ice blockage in the air passage. Therefore, the⑥ hot gas bypass valve automatically allows a small amount of high-temperature refrigerant, which has not been cooled by the condenser, to flow into the integrated evaporator ④B for temperature regulation, ensuring that its temperature remains above 0°C. Note: During the evaporation process, the refrigerant absorbs heat from within the evaporator container, including the heat from the compressed air, thereby lowering the temperature inside the evaporator. The temperature during this process is referred to as the “evaporation temperature”. How to select a suitable refrigerated dryer? To ensure the stability and quality of compressed air, it is crucial to select a refrigerated dryer that is compatible with the air compressor. The main relevant factors are as follows. 1. Selection based on the compressor’s exhaust volume: Choose a cold dryer with a compressed air handling capacity that is similar to the compressor’s volumetric flow rate, and ensure that their operating pressures are comparable; this can help to significantly save energy and operational costs. In addition, intake air temperature, pressure dew point, ambient temperature, etc., are also factors in selecting a cold dryer. If you are not familiar with the specific details of the air compressor, be sure to ask a professional air compressor technician to select the appropriate model for you based on the actual air usage requirements at the site ； 2. Size and weight: Many users believe that the larger the cold dryer, the better its performance. In fact, this understanding is incorrect; the use of a cold dryer is not determined solely by its size and weight. With the advancement of science, products with excellent performance can also be made small in size and light in weight ； 3. Internal configuration: The quality of a refrigerated dryer depends on the quality of its raw materials. Currently, the market for air compressors is filled with products of varying quality, and the origin of these materials is often unclear. It is essential to choose manufacturers that are well-known, have a good reputation, and operate at a large scale, so as to ensure product quality.