A: All our compressed air dryers warranty time is one year. But we will provide the technical support to customers all the time. As one of famous compressed air dryer manufacturers in China, Lingyu Machinery have strong technical and after-sales abilities. So we can help you solve any technical problems.

A: At present, Lingyu has sold air compressor dryers to many countries, such as United States, Mexico, Argentina, South Korea, Vietnam, Thailand, Malaysia, Indonesia, Philippines, India, Pakistan, UAE, Iran, Mozambique, UK, France, Russia, Turkey, etc.

A: Lingyu Machinery is professional compressed air dryer manufacturer. Our factory focus on compressed air treatment. We produce refrigerant dryer, twin tower desiccant air dryer, modular desiccant air dryer, coalescing compressed air filter and nitrogen generator.

(1) about refrigerant air dryer: in addition to the traditional shell-tube type dryers, we also produce energy-saving dryers. For example, Lingyu manufactures VSD air dryer, 0.1bar differential pressure refrigeration dryer, 3-in-1 plate heat exchanger dryer.

(2) Regenerative adsorption air dryer: besides the normal heatless and heated air dryer, we also produce the zero air-loss desiccant dryers. The zero air consumption air dryers are blower purge and HOC type. They can help customers to reduce the production costs.

(3) Special customization: Lingyu specializes in large air dryer for air compressor. The max air capacity can be up to 350m³/min. And we have rich experience in of high pressure compressed air dryer. For example, our factory can produce refrigerant & desiccant air dryers with 25 bar, 40 bar, 60 bar, 70 bar, 90 bar. Of course, low pressure air compressor dryer is also available.

Moreover, Lingyu also manufactures the explosion-proof air dryers. For instance, we can produce the refrigerated compressed air dryer for biogas. In addition, air compressor air dryer for ocean offshore platform. This kind of dryer has higher requirements for materials and anti-corrosion treatment.

Of course, our factory also customize other special air dryer for air compressor as requests.

(4) Compressed air filter: they are also manufactured by ourselves. High pressure air filters, such as 25bar and 40 bar, are also available. We can print your logo on the filter label.

(5) Other air compressor system products: Lingyu also supplies rotary screw air compressors, air receiver tank and pipe & fittings.

A: 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.

A: 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.

2. 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.

3. 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.

4. 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 -20℃, -40℃ and -70℃.

Does the compressed air dryer really work?

Yes. The air compressor air dryer is effective in removing moisture. Of course, different dryers, different working principles.

Refrigerant air dryer mainly use the principle of freezing and dehumidification. According to the second law of thermodynamics, heat can be transferred spontaneously from a higher temperature object to a colder one. The compressed air passing through the evaporator of the refrigerated dryer exchanges heat with the refrigerant. Finally it can obtain low dew point.

The working principle of adsorption air dryer is “Pressure Swing Adsorption”. The desiccant beads in the working tower can adsorb the water vapor in the compressed air. Thus, it can remove water to reach the required dew point.

Therefore, to sum up, the air compressor air dryer plays a big role in our industrial production. Especially with the increasing demand for energy saving, people have higher requirements for the use effect. Therefore, dryers with higher technical content have become, such as zero air loss dryer, variable frequency compressed air dryer, etc.

A: 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.

2. 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.

3. 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.

4. 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.

5. 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.

A: Air compressor dryer is the main compressed air treatment equipment. During compressing the air, the water vapor is also compressed along with it. So it will make compressed air have a high dew point. To ensure a lower dew point, we need compressor dryers.

There are several types of compressed air dryers. Besides, their working principles are different.

1. basic working principle of air compressor dryer

We can remove moisture by these methods, such as cooling, pressurizing and adsorption. For example, refrigeration dryer rightly uses cooling method.

(1) Pressurization for water-removal

Compressed air is wet air. Generally, it’s moisture content is inversely proportional to the pressure. That is, the higher the pressure, the lower the water.

PS: Take an example. Suppose that the air is a wet sponge. Squeeze out some water with force. Then the moisture content of this sponge is relatively reduced. Conversely, let go of the sponge and let it recover. Naturally, it is drier than the original sponge. So this is the drying principle under pressure.

So air compressor itself has the function of removing water. The method is rightly pressurisation. But this is not the purpose of the compressor. It is a “nasty” chore.

This is mainly due to economics. For example, increase a 1 kg in pressure. It will consume around 7% of energy. So this is quite uneconomical.

(2) cooling for moisture-removal

Conversely, “cooling” is a relatively economical way. Refrigerated compressed air dryer works in a similar way to air conditioning dehumidification.

Cool the air as low a temperature as possible. So the water vapor becomes less dense. This results in the formation of “condensation”. Air compressor dryer will collect and discharge these water droplets . Finally it eliminates moisture from the compressed air.

This involves condensing into water. Therefore, the temperature cannot be lower than the “freezing point”. Otherwise, icing will occur. And the drainage will not be effective. Generally, the pressure dew point of the refrigeration compressed air dryer is mostly 2~10℃.

2. working principle of refrigerant dryer

Its workflow consists of two aspects:

(1) compressed air working process

Firstly, the compressed air enters the heat exchanger of air compressor dryer. It’s also namely pre-cooler. Here the initial cooling takes place.

Next, it enters the evaporator. In it, it make air cool extremely fast.

Thirdly, the air-water separation takes place in the separator. And the water is drained out of the compressed air dryer.

Fourthly, exchange heat with the low temperature refrigerant in the evaporator. At this moment, air temperature is very low. It is approximately equal to the dew point temperature of 2 to 10°C.

Finally, the compressed air will then return to the pre-cooler. At this time, they will exchange heat with the high temperature air .

(2) Refrigeration process

Firstly, the refrigerant (e.g. R22) enters the compressor. After compression, its pressure and temperature rise.

Secondly, the R22 vapour is discharged into the condenser. In the condenser, they exchange heat with the compressed air. Thereby, R22 condenses to a liquid state.

Thirdly, the pressure and temperature of the liquid R22 drop as it passes through the throttling device. This device of air compressor air dryer usually are capillary or expansion valve.

Finally, the refrigerant enters the evaporator. They absorb heat from the compressed air and vaporise. And the R22 vapour will go back to the compressor. Then the next cycle begins.

3. working principle of adsorption dryer

There are many types of desiccant air compressor dryers. But their principles are basically same, i.e. PSA.

(1) What’s PSA pressure swing adsorption?

For compressed air: the lower the temperature and the higher the pressure. Then the adsorption capacity of the adsorbent is greater. Instead, the higher the temperature and the lower the pressure. So adsorption capacity of the desiccant beads is smaller.

If the temperature remains constant, the adsorbent will adsorb a large amount of water vapor under pressure. At reduced pressure, its adsorption capacity decreases. Then, the water originally adsorbed in the adsorbent is discharged. This is namely PSA.

In simple terms, compressed air flows alternately through towers A and B of the desiccant air compressor dryer. For example, at high pressure, tower A adsorbs water vapor. At the same time, tower B precipitates water at low pressure. The flow is then switched according to a set time program.

(2) The workflow of A/B tower air compressor air dryer

A-tower adsorption, B-tower regeneration (for heatless air dryer):

Firstly, the compressed air passes through the switching valve. Then it enters the drying tower A.

Secondly, the desiccant beads adsorb water vapor. Then they pass through the check valve to the outlet and are discharged.

In addition, part of air passes through a throttle valve. Then the pressure will drop.

Fourthly, the dried air purges the adsorbent of tower B. This results in a “regeneration”.

Finally, the air carries water through the switching valve. Then they go to the muffler. Finally, they are discharged to the atmosphere.

When switching, the valves of air compressor dryer act in the opposite way to the above. This results in “tower B adsorption, tower A regeneration.”

How do the other types of desiccant dryers differ?

● Micro-heat adsorption air dryer.

In contrast to the heatless compressed air dryer, it firstly heats compressed air with an electric heater. The purge the adsorbent.

Because of the heating, air temperature is higher. Therefore the drying effect is better. In other words, it consumes less compressed air.

So the energy consumption is lower than for heatless air dryer.

● Blower heated regeneration air dryer.

Compared to the micro-heat type, this dryer doesn’t use the compressed air. Instead, it uses a blower to blow the air.

Therefore, compressed air no longer acts as a “regeneration” air source. Then it reduces its consumption.

As a result, the energy consumption of the whole air compressor dryer is lower.

● HOC type desiccant air dryer.

Unlike the above dryer, it uses the recovered thermal energy of the compressor. This is because the compression process generates heat.

In summary, it is air compressor air dryer with the lowest energy consumption.

A: During using compressed air dryer, we have to maintain it regularly. In the following we will analyse the common problems for refrigeration dryer. And give the corresponding solutions.

1. High differential pressure between inlet and outlet?

(1) Reasons:

Firstly, the actual air capacity maybe exceed the rated value of the refrigerant air dryer.

Secondly, the resistance of the dryer system increases. Therefore, it leads to a reduction in the circulation area.

Thirdly, the inlet and outlet valves of refrigerated dryer maybe not fully open. Or the valve spool falls off.

There maybe leakage of piping inside the refrigeration air compressor air dryer.

Clogging of the inlet and outlet filters of the refrigerant dryer.

Finally, frost outside the evaporator refrigeration pipe. It will reduce the flow-through area.

(2) Treatment:

Firstly, start the spare compressed air dryer. So it can meet the need for continued production.

Secondly, check the piping of air compressor air dryer for defects. Or whether there is a blockage.

Thirdly, open and close the inlet and outlet of the dryer. To determine if the valve spool is dislodged. Otherwise contact for replacement.

Fourthly, overhaul & clean or replace the filter element.

Finally, if the evaporation pressure is too low, adjust the hot air bypass valve. So it an eliminate frost.

2. Ice refrigerant jamming of refrigerated air compressor air dryer?

Under high temperature and pressure, the refrigerant will become liquid from gaseous state. Then the moisture will enter the capillary tube with it.

When the filter is saturated with water and cannot filter the water out. The temperature at the exit of the capillary tube reaches 0°C. At this moment, the water get out from the refrigerant. As a result, it forms ice. Eventually it generates “ice jamming”.

Troubleshooting for “ice jamming” of refrigerant dryer

(1) Low temperatures in winter.

In winter, the temperature and humidity will be substantially lower. At this time, compressed air dryer has very good drying effect. However, problems also arise. Temperatures can too easily reach below zero. As a result, the pipes freeze up.

For such weather reasons, insulation is usually necessary. For example, close the doors and windows of the air pressure station. Or wrap the dryer pipes well.

(2) Selected too large a model

We usually advise clients to choose a bigger refrigerated compressed air dryer. This allows them to cope with high temperature conditions. So the air capacity of dryer is higher than air compressor. Sometimes this is not always a good thing.

For example, the refrigerant will exchange heat for 1m³ compressed air. But now it only processes 0.5m³ air. This can lead to low temperatures. It’s as low as below zero. Eventually there becomes the ice jam.

(3) Failure of dryer bypass valve

The function of hot air bypass valve to prevent ice jamming. When it fails, the probability of ice jamming increases significantly.

3. Refrigerated compressed air dryer not working

What should I do if air compressor dryer is not cooling? No cooling means that it does not work properly. Even more so, it cannot remove water. What is the reason for this?

(1) Firstly, check the heat dissipation of the condenser. It plays an important role. Therefore, we need clean the the aluminium fins frequently.

(2) Secondly, see if the compressor of air dryer is faulty. If the numbers of the high and low pressure meter are the same, there is a fault.

Or touch the outer wall of the air line. It feels like there is no temperature difference or a small temperature difference. It indicates that there may be a problem.

At this moment, it needs to repair or exchange the refrigerant compressor.

(3) Thirdly, many times because the refrigerant is not enough. So check the refrigerant pressure gauge. If it is not enough, directly add refrigerant into air compressor air dryer.

Or refrigerant is leaking and the high and low pressure gauges are all zero. Then you only need to check for leaks and fix them.

If the high pressure is very high and the low pressure is very low, the filter drier is clogged. It needs to fix or exchange it.

(4) Check other conditions.

1) whether the expansion effect of the expansion valve is normal;

2) if the high pressure of the refrigerant is within the normal value (12~18Bar for R22);

3) whether the low pressure of the refrigerant is within the normal value (3~5 bar);

4. Why does refrigeration air dryer trip frequently?

(1) Firstly, the ambient temperature is high. Besides, there is no cooling measures. So it leads to excessive work load of air compressor air dryer.

(2) Secondly, the room is not well ventilated with the outside world. So it is not able to discharge the dryer heat in time.

(3) Thirdly, the power supply is unstable. Or poor contact. So cause the voltage to float. Especially in many areas where electricity is relatively tight.

(4) Finally, the selection model is too small. The current processing capacity of compressed air dryer is small. But the actual demand is large. So overload operation.

After a certain time limit, we should take proper care and maintenance. Avoid fatigue operation of the machine.

More importantly, fully consider the influence of ambient temperature before purchasing compressor air dryer.

What should I do if my refrigerated dryer is leaking refrigerant?

The most visual indication of refrigerant leak is a zero value on the refrigerant pressure gauge. The most important thing is to find the leak firstly.

(1) Firstly, check inside dryer for oil stains. If there is, it means there is a leak.

(2) Secondly, look inside the air compressor air dryer. And see if the capillary copper pipes are broken.

After inspection, mark it well. Next, fill with a certain pressure of inert gas to confirm the leak. It is best to use nitrogen. If nitrogen is not available, gaseous Freon will do. It is strictly forbidden to use oxygen for leak checking.

How to do it?

At the beginning, add the gas slowly. Check the refrigerant gauge pressure of the compressed air dryer. Temporarily suspend when the pressure reaches about 0.2Mpa. Then listen carefully to whether there is any sound of air leakage inside dryer. If there is, you can find the leakage.

If not, continue to pressurise to 0.4-0.5 Mpa. Then find a sponge and dip it in soapy water. Firstly, wipe the area you have marked just now. Then wipe all the brass nuts inside the air compressor air dryer. If there is a leak, bubbles will blow out.

If don’t find the leakage, then it is possible that the evaporator is leaking internally. Put the evaporator to a separate pressure test. If there is pressure drop, then it shows that the evaporator that is leaking.

Once find the leak, needs to take action. For air compressor air dryer, it generally use brazing to patch the leak. Of course, it still needs a further pressure test. To ensure that the leak-filling weld is OK.

A: We need air treatment equipment to ensure the quality of compressed air. They include dryers, filters and air receiver. How about their installation order?

Many factories use refrigerant dryers directly behind the air compressor. First of all, this is not correct. The pressure of the compressed air just coming out is unstable. Besides it contains a lot of moisture and magazines. So you have to install a storage tank in front of air dryer for compressor. Not only it helps to stabilize the pressure, but it also cools temperature and removes water. Moreover, it will protect our refrigerant compressed air dryer.

Then, behind the storage tank, it should install a pre-filter. It can remove solid particles and impurities from the compressed air. Let the clean air enter the refrigeration dryer.

In addition, we need install a water and oil removal filters in front of desiccant air dryer. Because the adsorbent needs to avoid oil. Otherwise, it will affect the effect and service life of the desiccant beads. Then behind the adsorption dryer you also need to install a dust-removal filter. Because the adsorbent may be powdered over time, it is necessary to remove dust.

Therefore, the correct installation order is as follows: air compressor — storage tank — pre-filter — refrigerated air dryer — moisture / oil-removal filter — adsorption air dryer — dust-removal compressed air filter. Next, introduce the installation of refrigerated and desiccant air dryer separately.

1. Refrigerated compressed air dryer installation

(1) Installation site requirements

① Firstly, avoid exposing the air compressor dryer to direct sunlight. At the same time, not install in a humid and corrosive gas environment.

Otherwise it will lead to corrosion of the dryer heat exchange system pipes. This can cause damage to the equipment.

② Secondly, the ambient temperature should be below 45°C. And the room should have good air circulation.

If the ambient temperature is too high, it will cause the refrigeration compressor exhaust pressure to be too high. Then make the refrigeration air dryer overload. Eventually the machine will stop working.

③ Keep the air compressor air dryer at least 800 mm away from around. Otherwise it will cause inconvenient maintenance or poor heat dissipation.

④ Regarding installation: The dryer does not need to be installed using a foundation. It is only necessary to fix on a solid horizontal surface.

(2) Dryer installation piping requirements

① First of all, use flange connections for the compressed air inlet and outlet. So it can facilitate disassembly.

② Next, install a main line pipe filter. Then it can avoid solid impurities and oil mist contamination. Otherwise it will affect the heat exchange performance of the air compressor dryer.

③ Thirdly, the piping diameter can’t be smaller than the dryer inlet size. Besides the pipeline length should be short as much as possible. Then it can avoid too much bending to reduce the pressure drop.

④ In order not to affect normal production during maintenance. Consider installing a bypass line.

⑤ Sometimes there will be debris blocking the pipeline. And they will affect the normal operation of the refrigerated air dryer. Therefore, when piping, we must blow the main air line and the bypass.

⑥ There should be on-off valves for cooling water pipeline. Also install pressure gauge and temperature gauge for maintenance.

After installation of compressed air dryer, must check for leakage with soapy water. Otherwise it will waste air supply. Or the pressure may not reach the customer’s usage requirements.

(3) Power supply connection of refrigerant air compressor dryer

① Firstly, please connect to the power supply as indicated on the dryer nameplate.

② Secondly, the power supply must be with an earth leakage switch.

③ Thirdly, the voltage should comply with ±5% of the standard voltage.

④ Also, the refrigerant air compressor dryer must be with a grounding wire. Ensure reliable earthing.

⑤ The power supply line must not be barged in the middle. Otherwise, it will cause a voltage drop in the line. Finally, it will affect normal operation of compressed air dryer.

⑥ When setting the earth leakage circuit breaker, please refer to the maximum operating current of dryer.

⑦ Finally, please do not share the same protector with other machines.


If the voltage falls below 5% for a long time, it will damage the refrigerant compressor.

The refrigerant air dryer may cause personal injury if there is no earth wire.

If the power supply does not have an earth leakage switch, an electric shock may occur.

2. Desiccant air dryer installation

(1) Installation place

Similar to refrigerated compressed air dryer, desiccant dryer also has requirements for temperature. Don’t install the adsorption air dryer in areas where the ambient temperature exceeds 45°C. And it also avoid extremely cold environment. If possible, advise to insulate the dryer’s A/B twin towers. Also do not install outdoors.

Please reserve adequate space around the desiccant air compressor dryer. So it’s good for later maintenance. And fix the dryer to the foundation with bolts.

(2) Pipe installation

Connect the compressed air lines to the dryer inlet/outlet fittings. And there needs two filters before the adsorption air dryer for compressor. Also, to minimize pressure drop, use as few elbow connections as possible.

Frequent air discharge of A/B towers will cause noise. To reduce noise, consider connecting the dryer exhaust pipe to the outside. Besides, it is good for the discharge of condensate.

Likewise, after installing all piping, test for leaks. This ensures that the air compressor air dryer can work without problems.

(3) Compressed air filter installation

In addition to installing 2 filters in front of the desiccant air compressor dryer, you also need to install a filter in the back. The front coalescing filters are for water and oil removal. This ensures a long service life for the adsorbent. Also helps to reduce costs.

And the post-filter can help to eliminate the possibility of desiccant dust into the air system.

A: We know that compressed air dryers contain both refrigerated and adsorption dryers. The former can only reach a dew point of around 3°C. If requires a lower dew point, it only use adsorption air dryer. Depending on the regeneration method, the following types of machines are available. That is, heatless, micro-heat, HRB and HOC desiccant air compressor dryer.

Firstly, here we discuss the working principle of the HOC type regenerative air dryer. Then compare the energy consumption of various dryers with an engineering example. In addition, the discussion will focus on the problems of HOC desiccant dryers. And give solutions in two aspects.

1. Working principle of HOC desiccant air dryer

Adsorption air dryer usually uses twin-tower structure. One is for air drying. The other takes action during the regeneration of adsorbent. Currently the common adsorbent materials are activated alumina and molecular sieve.

The former is sensitive to the temperature of the working medium. When the temperature reaches 130°C or more, the water content of the adsorbent is only about 1%. It is almost completely desorbed.

On the other hand, molecular sieves have a higher adsorption capacity. The regeneration process includes following 4 stages. That is, heating – pressure reduction – cold blowing – equal pressure. The A/B towers switch according to the dryer PLC signal.

High temperature compressed air (above 110°C) enters the air compressor dryer. Then flows directly into the regeneration tower. And it will vaporise the moisture in the desiccant beads. Next, they will enter the cooler of the desiccant dryer. Cooling to around 40°C. At this time, the compressed air is in a supersaturated state. Therefore, many liquid water will precipitate.

Then the cooled air enters the drying tower. After reaching the dew point, most air is output to the compressed air pipe. This supplies the workshop and the air-using stations.

Another small part air flows into the regeneration tower via the control valve. They will blow adsorbent. At this stage, air consumption is about 2%. Finally discharge this part of compressed air via a silencer.

2. Energy consumption comparison of regenerative dryers

Firstly, briefly introduce the regeneration process of different adsorption air dryers. Then make a comparison of their energy consumption.

(1) Heatless air compressor dryer

The regeneration process does not require heating. It uses the regeneration air to purge the adsorbent. The air consumption is about 15% of the total air volume.

(2) Heated regenerative adsorption air dryer

The difference lies in the heating stage. There requires an external heat source. The air consumption of the regeneration process is about 8%.

(3) Blower purge desiccant compressed air dryer

The compressed air for heating comes from the outside. The air consumption is around 3%. Although the air loss is low, but there are also other consumption. That is, the heater and blower power consumptions.

(4) HOC air dryer:

The air consumption of this compressed air dryer is also about 3%. In addition, it needs the cooling water.

Take a example: Choose an oil-free screw air compressor. The power of the compressor is 1100kW. Its air flow is 200m³/min.

Heatless air dryer: operation charges each year is about CNY 1,445,400;

Heated air dryer: total operation fees each year is about CNY846,982;

Blower purge desiccant air dryer for compressor: operation charges each year is about CNY514,759;

HOC air dryer: total operation fees each year is about CNY157,680;

In summary, the HOC dryer has the lowest total regeneration power consumption. Besides, the unit power consumption is also lowest. The energy efficiency ratio is the highest.

On the contrary, heatless air compressor dryer has lowest energy efficiency ratio. The micro-heat and HRB dryers have the middle of the range.

3. Applications of HOC Compressed Air Dryer

Optimum regeneration temp. for adsorbents is above 130°C. And the regeneration effect will drop sharply when lower than 100℃。

Therefore the air temperature entering the dryer should not be below 110°C. This makes it impossible to set a pre-filter before air compressor dryer. The air oil content into dryer must be low. So only centrifugal and oil-free screw air compressors can meet this requirement.

How to ensure the dew point?

Firstly, it depends on the type and filling capacity of desiccant beads. Secondly, it depends on whether the regeneration of the adsorbent is complete.

Activated alumina has fast desorption speed So the regeneration process is short. But the adsorption capacity is not as good as molecular sieve. So when require a dew point of -40°C, only fill the activated alumina. However, when the dew point needs to reach -70°C, it must fill a certain amount of molecular sieve.

To ensure the dew point, should follow the below principles:

(1) Air compressors should match compressed air dryer one to one.

Each dryer should match to the corresponding air compressor.So it can avoid hydraulic disconnection due to the many units. Besides, the shorter the connection pipe, the smaller the heat loss.

(2) HOC dryer is not suitable for matching with variable speed air compressor.

Because the air flow of VSD air compressor ranges from 60% to 100%. If air flow is too small, the desiccant heating time becomes longer. So the effect of desiccant regeneration is not satisfactory.

(3) It should insulate the air inlet pipeline of the air compressor dryer.

The higher the air inlet temperature, the more ideal the regeneration effect of desiccant beads. If no insulation treatment, the air temperature will be down in the process of conveying. Besides it may cause scalding accident.

(4) For the compressed air system with big air-load change:

It should choose dew point and time control. When in the peak of air consumption, and the operating conditions are relatively smooth, use the time control mode. Conversely, switch to the dew point control mode. So it can ensure dew point of desiccant compressed air dryer.

(5) When the dryer inlet temp. is likely to be low, advise adding an electrical auxiliary heating system. It allows for the secondary heating for the inlet air.

In summary, the HOC desiccant dryer is suitable for such applications. That is, the air load is large and the load fluctuation is small. The regular time control mode can achieve the good operating effect. Besides the energy saving effect is remarkable.

When the air load fluctuates much, it needs to improve air compressor dryer. Change to a dew point control mode. And add electric auxiliary heater. So it can allow dryer convert automatically to micro-heat dryer when the dew point mode fails.

A: There are several types of air dryer for compressor. Below we will classify them. Air compressor dryer mainly has three types. That is, refrigerated air dryer, desiccant air dryer and membrane dryer. Of course, the former two kinds of dryers also have many different types.

(1) Refrigerant air dryer:

It is most common air dryer for air compressor. The working principle is heat exchange between air and refrigerant. During this process, the moisture will condense. It can remove about 95% water in the air compressor system. And lowest pressure dew point can reach 3℃. So refrigeration dryer can meet requirements of most industries.

But there are still many industries that have high dew point requirements. For example, food & pharmaceutical industry usually requires at least -40℃ dew point. Then only refrigerated dryer is not enough.

Below are some different types of refrigerated compressed air dryer:

① Air-cooled vs water-cooled refrigerant dryer:

They cool the refrigerant in different ways. The former uses an air-cooled condenser. The latter uses cooling water. So in appearance, the latter has cooling water pipes. But there is no air-cooling condenser. The former is susceptible to the ambient temperature. The dew point of the latter is a little more stable. Of course, it requires cooling water on site.

② Cycling vs non-cycling air dryer:

The latter is most common refrigerant compressed air dryer. It usually works at full load. But the former has a water accumulator and liquid temperature controller. They can regulate the refrigerant compressor. So the cycling air dryer for compressor is more energy-saving.

③ VSD air dryer:

VSD refrigerated dryer is similar to cycling air dryer. Both of them can save energy. But VSD air dryer uses the inverter to control refrigerant compressor.

④ Normal temperature vs high temperature refrigeration air dryer:

It refers to the inlet temperature of air compressor dryer. The former is Max 45℃. And the latter is Max 80℃. The key difference between them is whether there is a pre-cooler.

⑤ Normal pressure vs low pressure vs high pressure air dryer:

Normal pressure usually refers to 7~10bar. We can produce low pressure compressed air dryer down to 3.5bar. In addition, Lingyu also customize high pressure refrigeation dryer up to 100bar.

(2) Regeneration desiccant air dryer:

The desiccant beads has strong adsorption ability for water. Under the role of PSA + TSA, twin tower air dryer can remove water deeply. The available dew point can be down to -70℃. So this compressed air dryer can meet requirements of all industries.

Different regeneration methods, different adsorption dryers. Below we will introduce four kinds of regenerative air dryers.

① Heatless air dryer for compressor: it means there is no heater. The regeneration air is all from finished compressed air. So the energy consumption is biggest.

② Heated adsorption air dryer: there is a electric heater. It only consume part of compressed air for regeneration. Other part is from outside air. So energy consumption is smaller than above.

③ Blower purge desiccant air dryer: there adds a blower. It consumes much less compressed air. Besides, there is another zero air loss type. So its energy consumption is smaller that heated air dryer.

④ HOC type air dryer for compressor: it uses the waste heat from the air compressor. This is the most energy-saving compressed air dryer.

(2) Membrane dryer:

It is a new kind of air dryer for compressor. There is hollow fiber ultrafiltration membrane tube inside. Each component in the compressed air has different permeability to the membrane. Therefore, it can realize the separation of air and water. Finally get dry compressed air.

The performance of the membrane dryer is stable. The installation space is small. Besides, it doesn’t need power. It is commonly used in the laboratory.