Compressed Air Dryers : What are they Good For?

Absolutely Nothing….. err ALOT! They are really good for a lot! Specifically removing moisture/condensate from compressed air.

In almost every operation, clean, dry compressed air will result in lower operating costs. The purpose of compressed air dryers is to overcome the dew point of your compressed air by removing water from it. Compressed air can contain humidity, and in the right environments it can reach the dew point temperature and condense into a damaging liquid. This liquid can be problematic, as it can contaminate your products or equipment, causing frozen pipes, and possibly leading to corrosion and other issues.

Now that we know how important they are how do you know which one is right for you?

Types of compressed air Dryers

Refrigerant Dryer – the most commonly used type, the air is cooled in an air-to-refrigerant heat exchanger. (Here is a great blog deep diving on Refrigerant Dryers)
Regenerative-Desiccant Type – use a porous desiccant that adsorbs (adsorb means the moisture adheres to the desiccant, the desiccant does not change, and the moisture can then be driven off during a regeneration process). (Here is a great blog deep diving on Desiccant Dryers)
Deliquescent Type – use a hygroscopic desiccant medium that absorbs (as opposed to adsorbs) moisture. The desiccant is dissolved into the liquid that is drawn out. Desiccant is used up and needs to be replaced periodically. (Here is a great blog deep diving on Deliquescent Dryers)
Membrane Type– use special membranes that allow the water vapor to pass through faster than the dry air, reducing the amount of water vapor in the air stream. (Here is a great blog deep diving on Membrane Dryers)

The selection of an air dryer is done best by the professional who knows or learns the particular end uses, the amount of moisture which each use can tolerate and the amount of moisture which needs to be removed to achieve this level. Air, which may be considered dry for one application, may not be dry enough for another. Dryness is relative. Even the desert has moisture. There is always some moisture present in a compressed air system regardless of the degree of drying.

For compressed air, the best way to specify dryness is to cite a desired pressure dew point. Different types of dryers, therefore, are available with varying degrees of pressure dew point performance. To specify dew point lower than required for an application is not good engineering practice. (Naming a pressure dew point is how to state the degree of dryness wanted.) It may result in more costly equipment and greater operating expense.

If you have questions about compressed air systems and dryers or any of our 15 different Intelligent Compressed Air® Product lines, feel free to contact EXAIR, and I or any of our Application Engineers can help you determine the best solution.

Jordan Shouse
Application Engineer

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Air Compressors: Savings Found on the Supply and Demand Side

Producing compressed air can be expensive, but it is necessary for pneumatic systems.  And a large part of that expense is wasted energy, in the form of heat.  Waste will add to your overhead and affect your bottom line.  EXAIR has a line of products to help reduce air consumption at the point-of-use to save you money.  This would include replacing open-pipes and tubes with EXAIR Super Air Nozzles and Super Air Knives.  But, let’s look at the supply side inside your compressor room.  The air compressor operates at about 10% efficiency where most of that loss is in a form of heat. 

Wouldn’t it be nice to recover some of that expense?  You can.  By equipping your air compressor with a heat recovery system.  These systems are designed to recover the loss of heat for other uses.  Today, they can recover somewhere between 50% for liquid-cooled compressors to 80% for air-cooled compressors.  The heat can come from the after-coolers, the electric motor, the “heat of compression”, and the oil cooler.  This reclaimed heat can be used to heat water, warm rooms, pre-heat steam systems, and dry parts. 

Let’s create an example.  A company has a 100 HP air-cooled compressor that is running 8 hours per day for 250 days per year.  The heat recovery system will be able to reclaim 60% of the heat to warm city water in the plant.  If the electrical cost is $0.10 per KWh, we can calculate the savings.

Annual Savings:

100 HP * 0.746 KW/HP * 0.6 (reclaim) * 8 hours/day * 250 days/yr * $0.10/KWh = $8,952.00 savings per year.

In practice, reclaiming the maximum percentage may not be cost effective.  Your company can determine the best percentage for heat recovery by calculating the Return on Investment (ROI).  I wrote a blog post that can help you estimate (Click Here)

As mentioned above, EXAIR saves you money and increase efficiency on the demand side.  EXAIR has engineered nozzles to help reduce compressed air usage.  The following is a quick calculation by replacing an open-end blow-off with an EXAIR Super Air Nozzle.  If you have a ¼” (6mm) copper tube, it will use 33 SCFM (935 SLPM) of compressed air at 80 PSIG (5.5 bar).  As a common replacement, EXAIR uses a model 1100 Super Air Nozzle which will use 14 SCFM (396 SLPM) at 80 PSIG (5.5 bar).  With a simple tube fitting, you can mount the ¼” NPT Super Air Nozzle to the end of the ¼” copper tube.  If we use the same pretext as above, we can find the annual cost savings.  With an air compressor that produces 5 SCFM/hp, we can get a cost savings with the Super Air Nozzle.  The difference in air flow at 80 PSIG (5.5 bar) is:

33 SCFM (copper tube) – 14 SCFM (Model 1100) = 19 SCFM savings

Annual Savings:

19 SCFM * 1 HP/ 5 SCFM * 0.746 KW/HP * 8 hr/day * 250 days/yr * $0.10/KWh = $566.96 savings per year per nozzle.

Whether it is on the supply side or the demand side, companies are looking to reduce or reuse the wasted energy to have a more efficient compressed air system.  The heat recovery system is a bit more complex, but should be considered.  The EXAIR engineered nozzles are more simplistic, and they can give you a return on your investment in a short period of time.  If you would like to discuss how to improve your compressed air system from the supply side to the demand side, an Application Engineer at EXAIR will be happy to assist you. 

John Ball
Application Engineer

Twitter: @EXAIR_jb

Photo: Idea by Saydung89Pixabay License.

Compressed Air Distribution System, Keeping Pressure Drop to a Minimum

Compressed air is used to operate pneumatic systems within a facility, and it can be separated into three categories; the supply side, the demand side, and the distribution system.  The supply side is the air compressor, after-cooler, dryer, and receiver tank that produce and treat the compressed air.  They are generally located in a compressor room somewhere in the corner of the plant.  The demand side is the collection of devices that will use that compressed air to do “work”.  These pneumatic components are generally scattered throughout the facility.  To connect the supply side to the demand side, a compressed air distribution system is required.  Distribution systems are pipes which carry the compressed air from the compressor to the pneumatic devices.  For a sound compressed air system, the three sections have to work together to make an effective and efficient system.

An analogy that I like to use is to compare the compressed air system to an electrical system.  The air compressor would be considered the voltage source, and the pneumatic devices would be marked as light bulbs.  To connect the light bulbs to the voltage source, electrical wires are needed which will represent the distribution system.  If the gauge of the wire is too small to supply the light bulbs, the wire will heat up and a voltage drop will occur.  This heat is given off as wasted energy, and the light bulbs will be dim.  The same thing happens within a compressed air system.  If the piping size is too small, a pressure drop will occur.  This is also wasted energy.  In both types of systems, wasted energy is wasted money.  One of the largest systematic problems with compressed air systems is pressure drop.  If too large of a pressure loss occurs, the pneumatic equipment will not have enough power to operate effectively and efficiently.  As shown in the illustration below, you can see how the pressure decreases from the supply side to the demand side.  With a properly designed distribution system, energy can be saved; and, in referencing my analogy above, it will keep the lights on.

Pressure Drop Chart

To optimize the compressed air system, we need to reduce the amount of wasted energy.  This can be caused from leaks or pressure drop.   Leaks can be hidden and are typically located at connections within the distribution system.  In a poorly maintained system, a study found that 30% of the compressor capacity is lost through air leaks on average.  Even though leaks are the “silent killer” to a compressed air system, they can be found with the Ultrasonic Leak Detector

Pressure drop is more of a wide range issue.  It is based on restrictions, obstructions, and piping surface.  Out of these, restrictions are the most common types of pressure drops. The air flow is forced into small areas, causing high velocities.  The high velocity creates turbulent flow which increases the losses in air pressure.  Flow within the pipe is directly related to the velocity times the square of the diameter.  So, if you cut the I.D. of the pipe by one-half, the flow rating will be reduced by 25% of the original rating.  Restriction type of pressure drop can be found in different forms like small diameter pipes or tubing; restrictive fittings like quick disconnects and needle valves, and undersized filters, regulators and valves.

As a rule, air velocities will determine the correct pipe size for the distribution system.  It is beneficial to oversize the pipe to accommodate for any expansions in the future.  For header pipes, the velocities should not be more than 20 feet/sec (6 meter/sec).  For the distribution lines, the velocities should not exceed 30 feet/sec (9 meter/sec).  In following these simple rules, the distribution system can effectively supply the necessary compressed air from the supply side to the demand side.

To have a properly designed distribution system, the pressure drop should be less than 10% from the reservoir tank to the point-of-use.  By following the tips above, you can have the supply side, demand side, and distribution system working at peak efficiency.  If you would like to reduce waste even more, EXAIR offers a variety of efficient, safe, and effective compressed air products to fit within the demand side.  This will include the EXAIR Super Air Knives, Super Air Nozzles, and Safety Air Guns.  This would be the pneumatic equivalent of changing those incandescent light bulbs into LED light bulbs.  If you wish to go further in optimizing your system, an Application Engineer at EXAIR will be happy to help you. 

John Ball
Application Engineer
Twitter: @EXAIR_jb

Photo:  Lightbulb by qimonoPixabay Licence

Pressure Drop Chart by Compressed Air Challenge Organization.

The Basics of a Compressed Air Leak Detection Program

It is no surprise that compressed air can be a costly utility for industrial facilities. It can easily chip away at the bottom line finances if used carelessly and without planning. This is one of the leading reasons we have educated continuously on how to ensure this vital utility is used with safety and conservation in mind. If we have installed all engineered solutions at the point of use throughout a facility, there is still more to be saved. One of the easiest things to do with a utility system inside of a facility is to leave it unchecked and undocumented until something goes wrong. This does not have to be the scenario and in fact, starting a leak detection program in a facility can help to save up to 30% of the compressed air generated.

Leaks cost money!

That’s right, up to 30% of the compressed air being generated in an industrial facility can be exhausting out to ambient through leaks that run rampant throughout the facility. When the point of use production is still working fine, then these sorts of leaks go unnoticed. Another common occurrence goes something like this example: Maybe there is a leak bad enough to drop the packaging line pressure slightly, this may get fixed by bumping up a pressure regulator, production is back up and it is never thought of again. In all actuality this is affecting the production more and more with each leak.

The leaks add additional load onto the supply side. The compressor has to generate more air, the dryer needs to process more air, the auto drains dump more moisture, it all ads up to additional wear and tear also known as false load. All of this additional load on the system can add more maintenance which if left undone can result in system shut downs. One way to begin to eliminate this false load is to deploy a leak detection program. The steps are fairly easy.

Similar to our 6 Steps to Compressed Air Optimization, you start with a baseline of how much air the system is seeing and operating pressures. This begins the documentation process which is critical to the success of the program. Next, acquire an ultrasonic leak detector (ULD) and a layout of your compressed air system piping. Utilizing the ULD, test all compressed air piping along with equipment, and tag each leak that is detected. Next, begin to repair all of the tagged leaks and document the amount of compressed air savings with each repair. This again, is more documentation which leads to giving a quantitative value to the return on investment of the program. Lastly, schedule a follow up scan that recurs on a pre-determined basis to prevent the system from returning to it’s original leaky state.

EXAIR Ultrasonic Leak Detector

If you would like to discuss starting a leak detection program in your facility or have questions about the ULD or any point of use compressed air product, please reach out to an Application Engineer today.

Brian Farno
Application Engineer