Desiccant Dryers: Heat of Compression Type

Desiccant Dryers

Desiccant dryers come in different forms.  They are designed for water sensitive areas as they can reach a dew point to -40oF (-40oC) and below.  That means that water will not condense in the compressed air lines until the temperature is below the dew point.  The desiccant inside these units will adsorb the water vapor as compressed air passes through a bed.  Once the desiccant bed is full of water vapor, it will have to be regenerated.

A typical system will use two towers that will switch back and forth.  One tower is used to remove the water from the compressed air system, and the other is used to regenerate the desiccant.  In this blog, I will cover how the desiccant can be regenerated with a Heat of Compression (HOC) type of desiccant dryer.

An air compressor is not an efficient device.  For every eight horsepower of energy to make compressed air, only one horsepower is used as work.  And for compressed air drying, the type of desiccant dryer is important.  Regeneration of desiccant beads can be done either with non-heated or heated means. The non-heated, or heatless version will use 15% of your compressed air to purge through the regeneration tank.  The air escapes into the atmosphere with the water vapor and is wasted.

With the heated type desiccant dryers, they come in three different categories.  One type uses a heater to increase the temperature of the compressed air. At the elevated temperature, the purge requirement can be reduced to 7% for the regeneration of desiccant.  But, still compressed air is wasted.  To cut the purge to zero, a blower-type heated desiccant dryer can be used.  Instead of heating the compressed air, the blower will push ambient air through a heater to regenerate the desiccant bed.  But can you get more efficient than that?

Well, what if you can remove the heater and the blower?  The heat of compression type of desiccant dryers can do that.  Remember above when I mentioned that “for every eight horsepower of energy to make compressed air, only one horsepower is used as work”.  The seven horsepower of energy that is lost is given off as heat.  The HOC dryer uses that heat to regenerate the desiccant bed.  So, the overall energy is reduced even further.  There is a restriction when using this type of dryer.  The air compressor will have to be oil-free because oil will coat the desiccant beads and stop the adsorption rate.

When the air is compressed, heat is generated.  This heated air can reach around 200oF (93oC).  With the higher temperature, air can hold more water vapor.  As the heated air passes through the desiccant bed that needs to be regenerated, the water vapor is picked up from the desiccant beads.  The saturated air would then pass through an aftercooler.  The aftercooler reduces the air temperature below 100oF (38oC) which will cause the water to drop out.  From the aftercooler, the air will then pass through the desiccant bed in the drying tower.   When the cycle time is reached, the towers will switch to regenerate the second tower.

Line Vacs can convey many things.

With these types of dryers, the desiccant beads will start to degrade from regeneration.  To help replace them, EXAIR offers a Line Vac.  Instead of climbing a ladder with many bags of desiccant, the Line Vac can do this safely and ergonomically.   EXAIR Line Vacs use a small amount of compressed air to generate a powerful vacuum by a Venturi effect.  The unique design of the generators creates a high velocity of air to create a low pressure on one side and a powerful thrust on the other.  The Line Vac can pick up and move solid material vertically up to 20 feet (6 meters).  You can watch a video on the operation of a Line Vac HERE.  The EXAIR Line Vacs are very quiet, compact, rugged, and powerful.  To replace the desiccant, it can do it quickly and safely.

If you need to convey solid materials in a quick and easy way, an EXAIR Line Vac could be a solution for you.  We have them in a variety of materials and designs to match your application.  Ergonomically, they can save the back-wrenching labor of picking up bags, climbing stairs, and dumping material into towers.  If you want to know if the EXAIR Line Vac could work for you, an Application Engineer at EXAIR can help to recommend the best unit for you.

John Ball
Application Engineer

Email: johnball@exair.com
Twitter: @EXAIR_jb

 

Photo: Heated Desiccant Dryer by Compressor1Creative Commons Attribution-No Derivs 2.0 Generic

Line Vac Makes Golf Ball Testing More Efficient

Recently, we at EXAIR worked with a major player in the golf ball manufacturing world.  As an avid golfer myself, this was an application I could really get a ‘grip’ on and I had the ‘drive’ to propose a solution.

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Golf Ball Pyramids

The customer was involved in Research & Development, performing testing on the golf balls through robotic hitting, collection, and attribute measurement. The current set up involved the ball being hit, gravity collection into a PVC tube, and then an operator unhooking the tube, walking it over to and unloading the balls onto a rack, in the same order of hitting. The customer wanted to eliminate the manual task of the tube handling and have the balls delivered directly to the rack area.  The transfer would need to be 15′ vertically, then 15′ horizontally, before dropping down to table level.  A typical rate is only 5 balls per minute. This is a perfect application for the Line Vac, a compressed air operated conveyor.

EXAIR had previously tested golf ball conveyance, as seen in the Line Vac video below (at the 1:53 mark) where golf balls are conveyed 100′, at only 30 PSIG of supply pressure.

To present the best solution to customer, we had 2 dozen golf balls sent to us, and we set-up and simulated the actual conveyance conditions of 15′ vertical and 15′ horizontal travel. We found that the balls could be conveyed at only 20 PSIG of supply pressure, when presented one at a time. When the inlet was flooded with golf balls, simulating a worst case condition, the Line Vac was able to perform the conveyance at 60 PSIG. Operation at 80-100 PSIG is possible providing a operational safety factor.

The customer was impressed with the results and has implemented the model 6984 – 2″ Aluminum Line Vac Kit into the process, making the process more efficient.

6984
Model 6984 – 2″ Aluminum Line Vac Kit, with Auto Drain Filter Separator, Pressure Regulator, and Mounting/Coupling Kit for the Filter/Regulator

We have a team of Application Engineers that are ready to review your process and application, and help to determine if an EXAIR Line Vac can convey your material at the distance and rate desired.  We may even have you send in small sample of the material, and we can set-up, test, and share the results with you.

If you have questions about Line Vacs, or would like to talk about any of the EXAIR Intelligent Compressed Air® Products, feel free to contact EXAIR and myself or any of our Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer

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Golf Ball Pyramids by Beau B used under Creative Commons – CC BY 2.0

Video Blog: Sanitary Flange Line Vac

The below video reviews the Sanitary Flange Line Vac, the newest type from the EXAIR family of Line Vacs.

 

Sanitary Line Vac Family
EXAIR offers the Sanitary Line Vacs in diameters from 1-1/2″ (19mm) to 3″ (38mm), all in stock!

 

PowerPoint Sanitary Flanged Line Vacs file

If you have questions about the Sanitary Line Vac, or would like to talk about any of the EXAIR Intelligent Compressed Air® Products, feel free to contact EXAIR and myself or any of our Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer

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Sanitary Flange Line Vacs for Bulk Conveying

Piping systems have been a hallmark of human civilization for almost as long as people have been living in community with each other. Evidence of complex earthen pipe systems, with flanged fittings & asphalt sealants, date to 2700 BC. These were used for crop irrigation, potable water distribution, and wastewater removal in ancient civilizations from the Mediterranean to the Far East.

Over the centuries, new ways to use pipe led to new ways to make pipe.  Scientists and engineers figured out ways to make pipe stronger, lighter, cheaper, and in a variety of materials.  One of the more recent milestones is the development of sanitary piping and fittings.  The stringent cleanliness controls in certain industries (food and pharmaceutical, I’m looking at you) require highly corrosion resistant materials of construction.  The inside & outside surfaces of the pipe have to be finely finished so that they can be thoroughly and positively cleaned, with no crevices, “nooks & crannies,” etc., for material to gather or cling.  And since regular cleaning & sterilization is performed, the fittings must be able to be made & unmade in a manner that still provides for positive sealing when the system is restored to operation.

EXAIR Line Vac Air Operated Conveyors have always been well suited for applications like this.  With their open, unobstructed throats and smooth bores, they’re intuitively easy to clean, by design.  And we’ve made them, for years, in Type 316 Stainless Steel – the preferred material of construction for many food and pharmaceutical applications.  Many users in these industries were able to install them in sanitary piping systems by welding the flanges on our Stainless Steel Line Vacs, or by installing adapters on our Threaded Stainless Steel Line Vacs.

In the spring of 2017, EXAIR released the Sanitary Flange Line Vac with those same users in mind – eliminating the need to weld or thread flanges onto existing products.  They feature the same conveyance power as our Stainless Steel Line Vacs, and can even be modified to meet Heavy Duty Line Vac performance, if needed.  There are four sizes: 1-1/2″, 2″, 2-1/2″, and 3″…which covers the most popular size range of sanitary pipe systems.

While the sanitary piping systems are certainly most often found in those cleanliness-critical food & pharma type applications, other users incorporate them because of the smooth, continuous bore of the pipe and fittings, as opposed to a threaded pipe system, where the OD of the pipe threads into the ID of the fittings, causing a “step” in the throughput.  Because sanitary fittings mate via face-to-face flange seals, this eliminates that “step” which can make for a catch-point for certain items.  It’s for this very reason that a popular ammunition manufacturer uses sanitary pipe systems to convey shell casings…because they tumble with such turbulence in the air flow, they are especially prone to hanging up on any kind of catch-point.  So, they use sanitary piping & fittings, long radius elbows, and EXAIR Model 161150-316 1-1/2″ Sanitary Flange Line Vacs.

Air conveying of certain items, like these ammo shell casings, can be prone to clogging or jamming in systems where pipe, hose, and/or fittings are inserted into each other, creating catch-points.

EXAIR has a wide selection of engineered compressed air products that are “textbook” solutions for certain applications, but also make perfect sense for use in places you might not have thought of.  If you have a bulk material conveyance operation you’d like to discuss, give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
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Shells photo courtesy of hydropeek  Creative Commons License