FAQ

The heat exchanger is very important part in refrigerant air dryer. We can explain this question from two aspects:

(1) Structure: there are two types of heat exchangers in refrigerant air dryer for compressor. One is shell-tube type. Another is the 3-in-1 plate heat exchanger. The latter has bigger heat exchange area. So its heat exchange efficiency is higher than former. Moreover, the latter usually has smaller pressure drop. Therefore, the compressed air dryer with 3-in-1 plate heat exchanger is more energy-saving.

Of course, the latter also has one disadvantage. The dryer pressure can’t be too high. Its working pressure is usually max 16bar. But for the dryer with former heat exchanger, we can customize high pressure up to 100bar.

(2) Material: the former usually uses the carbon steel shell. And core materials are usually copper tube and aluminum foil. So this traditional compressed air dryer can’t be suitable for food and medical industry. But we can also customize the stainless steel air dryer for compressor.

The latter usually uses the aluminum alloy or stainless steel material. So you can use this air compressor dryer for food & medical industry directly.

 The air compressor discharges the compressed air, but it is not clean. There are a large number of contaminants, such as moisture, dust particles, and oil, etc. If not purify and dry the air, they will enter the production process. Moreover, many screw air compressors are oil-type. Then this leads to many problems. So it needs compressed air dryer. It mainly includes refrigerated and desicant air compressor air dryer. Of course, there also include the 3-stage coalescing filters in the air compressor dryer system.

So what are the specific problems that arise?

1. Firstly, it leads to a decrease in production capacity

If there is no compressed air dryer, then moisture and oil will lead to clogging and rusting of pneumatic equipment and tools. This causes slow operation. Besides, clogged lines and parts will lead to lower pressure. And the tools will lose efficiency. In the long time, the equipment will break down. In severe cases, this can lead to production downtime.

1. Secondly, the product defect rate will increase

High water content in compressed air leads to an increase in product failure rate. For example, spray painting, electronic product processing. In laser or plasma cutter machines, moisture will pollute the lenses on our cutter heads. So it will directly affect the cutting efficiency.

In addition, more various influence exists in the food industry. Compressed air often plays a role in food packaging and transportation. Also, compressed air often comes into contact with the product.

If there is no air compressor air dryer, then a large amount of moisture or oil can damage our food. Especially in the dry food industry, there are more strict requirements for air humidity. ISO standards have different classes for compressed air quality in the food industry. Different levels, different contents of solids, water and oil.

1. Thirdly, air aerodynamic loss

Water in compressed air will corrode the pipes. This leads to pipe blockage. Moreover, the mixing of water, oil and dust can exacerbate blockages. Besides, in cold regions, moisture freezing can cause pipes to freeze. Then the pressure drops and the pressure difference is large. Eventually, it will affect the safety production. In addition, in serious cases, it will lead to air leakage from the pipeline.

So it needs the refrigerated compressed air dryer and desiccant air compressor dryer to remove water.

1. Finally, the production and maintenance costs increase

Moisture and oil will directly damage our pneumatic components. Besides they will also corrode our equipment. Then we have to replace the spare parts with new ones. This increases both the maintenance cost and the production time cost.

If you want to improve the quality of compressed air, it needs to install precision filters to remove oil and water. Then install air compressor air dryer to remove the water deeply. This brings the dew point to reach the application requirements.

Where does the water in compressed air come from?

The moisture in compressed air comes primarily from the atmosphere. This is inherent in the natural air. Regardless of the season, there is a certain relative humidity in the atmosphere. In addition, after compression or cooling, the water vapor in the air will become liquid water. This affects the quality of compressed air.

In the field of industrial air compressor applications, many users are very sensitive to the presence of moisture. Since we can’t eliminate the water before air compressor, it needs to remove moisture in compressed air treatment system.

Before entering the air compressor, the moisture in the air is mainly water vapor. And it is unsaturated. As shown in Sheet 1, the relative humidity of the air is 69% and the temperature is 20°C. After compression (7 bar), the water vapor in the compressed air becomes saturated because of the cooling of the rear cooler of the air compressor. And 42% of liquid water will be precipitated. This liquid water can be removed by gas-water separator and storage tank. The remaining 58% of water is present in the compressed air in the form of water vapor.

If there is no air compressor dryer, then the direct use of compressed air will be bad to production. Therefore, refrigerated air dryer and desiccant air dryer become the preferred air treat equipment.

There are three general requirements for the water content of compressed air.

① The air compressor discharge compressed air. If there is a cooler + air receiver, then it can lower temperature by 3 to 10 ℃. This can basically meet for customers with low quality of air, such as drilling rigs, air cannons, etc..

②But most industrial enterprises generally have such requirement :10℃>pressure dew point>0℃. This requires the use of air compressor refrigerated dryer as to remove the water vapor.

③ And if the need for dew point ≤ 0 ℃, it is necessary to choose desiccant air compressor air dryer. The common dew point requirements for adsorption compressed air dryer are .

Air compressor dryer is an essential element of compressed air systems. Inevitably, there will be moisture during the operation of the air compressor. It can not only contaminate the end product, but also damage our production equipment and components. So this is why it must remove these moisture in the compressor system. Compressed air dryers are rightly the devices that helps to dry the wet air. This guarantees the quality of your compressed air. But to you, what is the best air dryer for air compressor? And how to select them?

In order to choose the right dryer, it needs to know following parameters:

1. Air capacity

This is the max flow of compressed air that the air compressor dryer can handle. Firstly the user needs to determine this value based on the consumption of all air consuming equipment and the usage factor. Of course, if you already have an air compressor, you can send us the nameplate.

As a air compressor dryer manufacturer, we tell you responsibly. If you use a lot of air, try to choose a compressed air dryer with a larger capacity. That is, the air capacity of the dryer should be greater than that of the air compressor. Because in times of high temperature and humidity, the water content of the air increases. At this time, the dryer machine is overload. So the drying effect will decrease. This can cause many problems, such as large amounts of moisture and equipment breakdown.

1. Inlet air pressure

Different air pressures, different air capacities of dryer. The common pressures in industrial production range from 0.6MPa to 1.0MPa. So the most common is the normal pressure air compressor air dryer.

However, other industries have different pressure requirements. For example, the laser industry generally requires 16 bar. There are also some industries that require high pressure compressed air dryer. Our company can customize dryers up to 100 bar.

1. Inlet air temperature and ambient temperature

Temperature is critical to the choice of air compressor dryer. For example, there are two types of refrigerated air dryers. Namely normal temperature type (50°C) and high temperature type (80°C). For example, in Pakistan and the Middle East, temperature is very high in summer. First of all, it must choose a high temperature type of refrigerant dryer. Moreover, we often need to choose a larger model. This not only achieves good water removal, but also avoids dryer downtime.

On the other hand, the inlet air temperature of the desiccant air dryer should generally not be greater than 40°C. If temperature is too high, the water removal effect of the adsorbent will be greatly reduced. Of course, it can chose the HOC type desiccant dryer at this moment.

1. Dew point requirement of air compressor dryer

Different dew point requirements, different equipment configurations. Naturally the price is different. Refrigerated dryers generally have a pressure dew point of 2 to 10°C. Of course, different conditions, different dew points. For example, refrigerant compressed air dryer can achieve a very low dew point. But it requires a standard operating condition of 25°C and 7 bar.

Different industries have different requirements for dew points. The following are some examples.

(1) Pharmaceutical industry: dew point is at least -40°C;

(2) PCB industry: dew point needs to reach -20°C;

(3) Gas air separation industry: dew point requires to be -70°C;

If you require a dew point of -70°C, it must choose a combination dryer. Or there must be a refrigeration dryer and filters before adsorption air dryer.

1. Other factors to select a compressed air dryer

In addition to the parameters above, it also needs to consider the following factors.

(1) Voltage and frequency

It varies from country to country. For example, in North America, 220V/60HZ/single-phase and 380V/60HZ/3-phase are common. At this moment, it needs to customize the refrigerant compressor. Sometimes the dyer price will also be different.

(2) Raw materials

Some industries have requirements for the material of air compressor dryer. For example, pharmaceutical industry requires stainless steel. In this case, the piping and heat exchange system must be SS304. And the adsorption tower also needs SS304. In addition, the lithium battery industry also requires stainless steel.

The stainless steel dryer will be more expensive. Of course, you can choose our PD series refrigerated air dryer. And also can choose the modular desiccant compressed air dryer. They can also meet the requirements of food and pharmaceutical industries.

(3) Environmental requirements

The usual refrigerant of refrigerant air dryers is R22. It is common in developing countries. However, European and American countries require eco-friendly refrigerants. For us, R134a, R407C, R410a are available.

If you want an eco-friendly refrigerant, the dryer is a little more expensive.

(4) Air cooled vs water cooled refrigerated compressor dryer

Small flow refrigerant air dryer is air cooled. Our air-cooled dryer can be up to 120 m³/min. If above 120 m³/min, air compressor air dryer are water-cooled.

For high flow dryers: if needs air-cooled type, the size will be very large. For example, it will be as high as several floors. And the heat exchange efficiency will be much worse.

Water cooled dryer is not affected by high temperature environment. Of course there needs a cooling water system. So this will add cost.

(5) Energy saving requirements

① Fixed vs variable frequency refrigerated air dryer

We commonly use fixed frequency air compressor dryers. It can meet the maximum output. But in actual production activities, the air demand varies. At small demands, it still works at maximum output. This leads to a waste of energy.

On the contrary, the output of variable frequency dryer can match with the air demand. This results in significant energy and operation cost savings.

② Choice of desiccant dryer regeneration method

The heatless compressed air dryer has a small power ~0.1 kW. But it has big air consumption of about 15%. This is high energy consumption.

Micro-heated desiccant dryer generally consumes about 8% of regeneration air. Compared to the heatless dryer, it can save 40% of energy.

The zero air loss desiccant dryer consumes 0% regeneration air. To heatless air compressor air dryer, it can save 70% of energy. Of course it is more expensive.