Drying Supply Side Air With Heat of Compression Dryers

The supply side of a compressed air system has many critical parts that factor in to how well the system operates and how easily it can be maintained.   Dryers for the compressed air play a key role within the supply side are available in many form factors and fitments.  Today we will discuss heat of compression-type dryers.

Heat of compression-type dryer- Twin Tower Version

Heat of compression-type dryers are a regenerative desiccant dryer that take the heat from the act of compression to regenerate the desiccant.  By using this cycle they are grouped as a heat reactivated dryer rather than membrane technology, deliquescent type, or refrigerant type dryers.   They are also manufactured into two separate types.

The single vessel-type heat of compression-type dryer offers a no cycling action in order to provide continuous drying of throughput air.  The drying process is performed within a single pressure vessel with a rotating desiccant drum.  The vessel is divided into two air streams, one is a portion of air taken straight off the hot air exhaust from the air compressor which is used to provide the heat to dry the desiccant. The second air stream is the remainder of the air compressor output after it has been processed through the after-cooler. This same air stream passes through the drying section within the rotating desiccant drum where the air is then dried.  The hot air stream that was used for regeneration passes through a cooler just before it gets reintroduced to the main air stream all before entering the desiccant bed.  The air exits from the desiccant bed and is passed on to the next point in the supply side before distribution to the demand side of the system.

The  twin tower heat of compression-type dryer operates on the same theory and has a slightly different process.  This system divides the air process into two separate towers.  There is a saturated tower (vessel) that holds all of the desiccant.  This desiccant is regenerated by all of the hot air leaving the compressor discharge.  The total flow of compressed air then flows through an after-cooler before entering the second tower (vessel) which dries the air and then passes the air flow to the next stage within the supply side to then be distributed to the demand side of the system.

The heat of compression-type dryers do require a large amount of heat and escalated temperatures in order to successfully perform the regeneration of the desiccant.  Due to this they are mainly observed being used on systems which are based on a lubricant-free rotary screw compressor or a centrifugal compressor.

No matter the type of dryer your system has in place, EXAIR still recommends to place a redundant point of use filter on the demand side of the system.  This helps to reduce contamination from piping, collection during dryer down time, and acts as a fail safe to protect your process.  If you would like to discuss supply side or demand side factors of your compressed air system please contact us.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

Heat of compression image: Compressed Air Challenge: Drive down your energy costs with heat of compression recovery: https://www.plantservices.com/articles/2013/03-heat-of-compression-recovery/

So Many Holes

I remember the book and movie about a young teenager who gets sent to a prison/ work camp that all they do is dig holes. Yeah, there’s a much deeper story line there and that isn’t the point of this blog. The point is, that movie is all I thought of when I encountered this customer’s nozzle solution. Their ejector nozzle on a recycling conveyor was using too much air and was too noisy.

Upon receiving the nozzle to do a free EXAIR Efficiency Lab, we were absolutely amazed at the level of care taken to make something like this. The nozzle was purpose built and definitely got the job done, it also drained their compressed air system at times and made a lot of noise while it did the work. So what did this nozzle look like, now keep in mind, this was not the customer’s design, it was a solution from the machine manufacturer.

For an idea, the customer nozzle was a 3″ overall length, and had a total of 162 holes in it. There were two inlets for 3/8″ push to connect tubing. The holes were very cleanly drilled and we used a discharge through orifice chart to estimate the consumption before testing. Operating pressure were tested at 80 psig inlet pressure.

Discharge through an orifice table.

Our estimations were taken from the table above. We used a pin gauge to determine the hole size and it came close to a 1/32″ diameter. With the table below we selected the 1.34 CFM per hole and used a 0.61 multiplier as the holes appeared to have crisp edges.

Estimation Calculation

Then, we went to our lab and tested. The volumetric flow came out to be measured at 130.71 SCFM. This reassured us that our level of estimation is correct. We then measured the noise level at 95.3 dBA from 3′ away. Lastly, we tested what could replace the nozzle and came up with a 3″ Super Air Knife with a .004″ thick shim installed. To reach this solution we actually tested in a similar setup to the customer’s for functionality as they sent us some of their material.

Now for the savings, since this customer was focused on air savings, that’s what we focused on. The 3″ Super Air Knife w/ .004″ thick shim installed utilizes 5.8 SCFM per inch of knife length when operated at 80 psig inlet pressure. So the consumption looks like below

That’s an astounding amount of air saved for each nozzle that is replaced on this line. The line has 4 nozzles that they want to immediately change out. For a single nozzle, the savings and simple ROI looks like the table below.

Air Savings / Simple ROI

That’s right, they will save 115.02 SCFM per minute of operation. These units operate for seconds at a time so the amount of actual savings is still to be determined after a time study. In videos shared, there was not many seconds out of a minute where one of the four nozzles was not activated. Once the final operation per minute is received we can rework our calculations and see how many hours of line operation it will take to pay back each knife purchase.

If you have any point of use blowoff or part ejection and even have a “nice looking” blowoff in place, don’t hesitate to reach out. These are still very different from our Engineered Solutions. We will help you as much as we can and provide test data, pictures, and even video of testing when possible.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

Take It All In – Just Filter It

The Nose – Only the Nose Knows

Take a nice deep breath as you read this. In through the nose. If you are like me right now, due to Fall allergies you’ll have a little bit of a restriction, hold it for just a second and then breathe out through the mouth. The body is an amazing thing, when we breathe in through our nose the body has some natural filtration built in that is also known as nose hair. While not the most attractive thing to most, it is important. The hairs in the nose help to filter out allergens and catch foreign debris.

An Improperly maintained Cabin Air Filter on a car makes a great bed for mice

Other items you interact with daily have similar air intake filtration. A car often has both an intake air filter and even an in-cabin air filter, these both protect various parts. The engine air filter is vital to prevent dust, debris and even excessive water from entering into the precision machined and assembled motor. The HVAC system in every business or home generally has an intake air filter in order to protect the coils and heater box.

There’s another system in most manufacturing facilities that should always have a filter on it, and that is the compressed air system. Properly maintaining and filtering the incoming ambient air feed before it is compressed starts the process of on the right foot to optimize performance and insure efficiency is maintained from the start of the entire process. These filters are like many others and can be part of a preventative maintenance program. The air compressor manufacturer will have a recommendation on frequency for the various types.

Old Piston driven air compressor intake air filter.

If these filters are left unchanged then the compressor begins to have restricted flow on the intake which then results in less air being pulled in or maybe the filter is removed and then the debris all gets pulled in and sent through to become foreign debris inside the compressor. Both of these will cause the compressor to wear or overheat and work harder to compress the air and send it into the storage tank. This results in premature maintenance needed on the compressors and or point of use devices.

Thus, always filter your incoming air. Whether for your air compressor, car engine, or house, start with a fresh intake and then keep it optimized from there. The payback will be longer lasting equipment that operates at a higher efficiency. And remember, breathe in through your nose.

If you would like to discuss your filtration setups, feel free to reach out to an Application Engineer.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

Stories From The Field: Automotive Plant Tour

Throughout my years I have been in many manufacturing facilities. Oddly enough, I have seen nearly every part of a passenger car manufactured and then fully assembled. The amount of compressed air applications in automotive supplier and manufacturing facilities are tremendous. Here are some stories from just a few we have encountered over the years, and all of them can be found in our Application Database.

Air Wipe – How it works
  1. A component manufacturer, specifically a steering and transmission component manufacturer was having issues with machined parts coming out of a CNC machine with too much oil based cutting fluid on them and not passing inspection process because the oil would throw off the automated measuring system. The part was a splined shaft that the high surface tension oil stayed in the splines. The part was removed from the machine via robotic loader and set onto a fixture. The path to the fixture was outfitted with a Super Air Wipe so the robotic loader could move the part into and out of the air wipes’s airflow and remove the oil. The converging airflow of the Super Air Wipe was ideal to keep the peaks and valleys of the shaft clean of oil and they were able to direct oil back into the cutting machine so no separate collection system was needed.
Robotic Welder fitted with EXAIR Super Air Wipe

2. A seat bracket manufacturer had issues protecting the lenses on their vision systems from welding spatter. They were again able to reduce the replacement / repair downtime by installing a 9″ Super Air Wipe in front of the robotic mounted lens and keep the spatter / fumes from ever making it to the lens, resulting in expanded run times between repair / downtime.

Cooling with Air Amplifiers

3. A forging company manufacturing the pistons was having issues reducing the temperature of the pistons as they were assembled to the connecting rods. The solution for them was to install a series of Super Air Amplifiers over the fixtured, indexing line and at each dwell station a Super Air Amplifier would activate and cool down the assembly by moving large volumes of ambient air mixed with small amounts of compressed air onto the surfaces.

4. An automotive manufacturer had issues with stamping shavings and welding debris staying on the surface of parts and fixtures resulting in rework and defective parts. Implementing a series of Super Air Nozzles, and Super Air Knives resulted in debris removal that saved tooling rework as well as production reject parts.

5. Another automotive / recreational vehicle manufacturer needed help with their torture test machine for suspension components. They were utilizing fans to try and keep shock sensors cool and replicate air movement. electric fans were not able to provide a focused airflow and so enter the Super Air Amplifiers. These have also been utilized on engine torture test machines.

1 – Chevrolet Corvette C7 2014 – LT1 Engine Testing on Dyno

These are just a select few of the actual applications that I have actually help with over the course of the years. As a whole, we have helped endless number of automotive industry applications. It doesn’t matter if you are in the automotive industry or just a garage tinkerer, contact and Application Engineer and let us help you with your point of use compressed air application today.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

1 – Autoblog_gr; Chevrolet Corvette C7 2014 – LT1 Engine Testing on Dyno – retrieved from https://www.youtube.com/watch?v=N3h8imnOPwU on 8/31/2022