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/

Air Atomizing Spray Nozzles

Spray nozzles in action.

EXAIR’s Atomizing Spray Nozzles atomize fluids (most commonly water) in a range of spray patterns for a variety of uses. They combine liquid and compressed air to create a mist of atomized liquid that can be easily adjusted to meet the need of your application. All models use stainless steel construction for durability and corrosion resistance. Atomizing spray nozzles are available in 1/8 NPT, 1/4 NPT and 1/2 NPT sizes.

EXAIR’s atomizing nozzles are available in 3 basic families:

Internal Mix:

Internal Mix Atomizing Spray Nozzles

Internal mix nozzles mix the liquid and air inside the air cap and produce the finest atomization. Internal mix nozzles can be used on liquids with a viscosity up to 300 cP. Both air and liquid sides are pressure fed.

External Mix:

External Mix Atomizing Nozzle

External mix nozzles have the highest flow rates and allow the air and liquid flows to be adjusted independently. These nozzles are best where precise liquid flow is needed. External mix nozzles can be used on liquids with a viscosity above 300cP. Both air and liquid sides are pressure fed.

Siphon Fed:

Siphon Fed model

Siphon fed nozzles require no liquid pressure and can be used with gravity fed liquids or liquids from a siphon height as much as 36 inches (91 cm). Siphon fed nozzles can be used on liquids with a viscosity of up to 200cP.

Using EXAIR atomizing nozzles, you can coat, cool, treat and paint a variety of of products. Used with water, they are an efficient way to cool hot items in your automated process. These nozzles are also an excellent choice for dust mitigation.

No Drip Atomizing Nozzle

EXAIR also has No Drip Atomizing Nozzles. No Drip Atomizing Nozzles work the same way our standard atomizing nozzles do, but have the added benefit of positively stopping liquid flow when compressed air is shut off.

Sound levels for individual Atomizing Spray Nozzles are not noted in our catalog and are determined by the actual fluid pressure, surfaces being treated and surrounding enclosures used in conjunction with the Atomizing Spray Nozzle(s) to form the system will determine the actual sound level. Max temperature is 400°F (204°C)for atomizing Spray Nozzles. All Atomizing Spray Nozzles are CE compliant.

If you have a specific application or project requiring Atomizing Spray Nozzles and need help, please contact any of our qualified Application Engineers.

Eric Kuhnash
Application Engineer
E-mail: EricKuhnash@exair.com
Twitter: Twitter: @EXAIR_EK

Pressure Regulators

At EXAIR, a large part of my job is to discuss your applications and make recommendations based upon which of our products would best help your application. In doing so, we always review your air supply to ensure that you have enough air to run our products. For instance you may need an Air Nozzle. This seems simple enough right? Surely you have enough air for this? Well, if you are buying our Atto Super Air Nozzle (left) you probably do, as this is a small nozzle that consumes 2.5 SCFM. However, you may need our large Super Air Nozzle Cluster (right) that will consume 168 SCFM. So as you can see it’s important that we discuss the amount of air you have at the point of use.

Another part of my job is to help customers trouble shoot issues once they have installed our products. I can proudly say that rarely is it an issue with the product itself. The most common cause of malfunction is with the air supply at the point of use. I have seen companies with massive air compressors not be able to supply 30 SCFM. Why? Well just because you have a lot of air coming out of the compressor, doesn’t mean you have a lot of air at the point of use. Other machines and tools down the line, as well as leaks and turns may have depleted the air supply long before it reaches your station for this application. This is the reason why we always recommend our Pressure Regulators with Gauge as seen here:

Pressure Regulators “dial in” performance to get the job done without using more air than necessary.

It’s pretty obvious why we would want you to have a gauge at the point of use, but the importance of the pressure regulator is many times overlooked. Many of our products need to have a certain pressure of air along with the proper SCFM to function efficiently. Some of these are products include some of our Industrial Housekeeping Products and Cabinet coolers. But, many of our products will function perfectly, and even be more efficient for your application with less airflow and psi. To find the best pressure and flow, we use a rule of thumb of starting at 80 psig and dial it back (or up) 5 psig at a time, until the best fit is found.

Most facilities have airlines running throughout, and they are all pushing the same psi and airflow. It is easy to just tap in and drop a line to the new point of use for the new tool. But, if there are 10 machines in line before this one, the air supply at machine 1, is much more than at machine 10. There are also leaks, turns, buildup in the line, and other air flow restrictions that are most likely in the way… This is why you will need a gauge and a pressure regulator at each point of use…

Also, when you drop a line to run a Super Air Knife (or any other EXAIR product) it may be coming off of a 100 psig line. You may only need 40 psi to run this 12″ Super Air knife. At 40 psig you will be pushing 21 SCFM. If this can clean, dry, or move your material as needed, then why use the 100 psig coming from the shop line? At 100 psig, that same 12″ Super Air Knife will use 42 SCFM. That additional SCFM has a rough cost of about $10 per day (running 24 hrs day with cost per kWh at $0.10). As you can see from this simple example, the pressure regulator is a no brainer to save costs and increase efficiency in the product itself.

There are many blogs written about your compressed air being the 3rd to 4th highest utility expense for many companies. In todays economic climate, it is important to use every efficiency possible. Using a regulator is imperative to control any type of flow, be it water, gas, electricity and even – air. Please give us a call to discuss any questions with your next application.

Thank you for stopping by,

Brian Wages

Application Engineer

EXAIR Corporation
Visit us on the Web
Follow me on Twitter

Intelligent Compressed Air®: Common Compressor Room Mistakes, And How To Avoid Them

While we don’t sell, install, or service air compressors, EXAIR Intelligent Compressed Air Products run on compressed air, so helping you get the most out of your compressed air system is important to us. Today, we’re starting where it all begins: the compressor room.

Some of the mistakes that are commonly made in the compressor room are by design, and others are operational. My colleague Tyler Daniel wrote a great blog on design considerations recently, so I’m going to focus on the operational aspects, which include maintenance…and maybe some minor design stuff:

  • Poor ventilation: Air compressors get hot. They’ve got a lot of moving parts, and many of those parts are moving under a great amount of force (pressure is literally defined as force per unit area), and at a high rate of speed. Add in the heat of compression (it takes energy to compress air, and that energy has to go somewhere, something another colleague, John Ball, explains here), to all that friction and you come up with a TREMENDOUS amount of heat. An industry thumbrule, in fact, states that over 2500 Btu/hr of heat is generated, PER HORSEPOWER, by a typical industrial air compressor. If the compressor room isn’t big enough, you’ll need an exhaust fan capable of removing all that heat.
  • Lack of filtration: Take a good, full breath in through your nose, right now. Did you smell anything unpleasant or irritating? I hope not…clean air is a “must” for your lungs (and the rest of your body), and the same is true for your air compressor (and the rest of your compressed air system). Keeping up with the maintenance on the intake filter is literally “starting where it all begins”…from the 1st paragraph.
  • Not removing moisture: Water & water vapor will have an adverse effect on many components of your compressed air system: it’ll cause rust in iron pipes, damage the seals in air cylinders, motors, tools, etc., and if you use it for blow off or conveying, it’ll contaminate your product. We’ve writtenagain and again…about the importance of dryers, and which type might be best for you.
  • Tolerating leaks: The compressor room is loud, so leaks are going to be pretty big before you can hear them. And to add insult to injury, the vibration of a running compressor makes the compressor room a prime location for them to occur. Even one small leak that you couldn’t hear in a quieter area will cost you over $100 over the course of the year, and maybe only take minutes to fix. Good news is, even if you can’t hear them, they ALL make an ultrasonic signature, and we’ve got something for that.
EXAIR Model 9061 Ultrasonic Leak Detector “finds them all, big or small!”
  • Ignoring maintenance. If you don’t schedule planned maintenance, your equipment will schedule corrective maintenance for you…oftentimes at greater expense, and with no regard to your schedule.
    • Moving metal parts that make metal-to-metal contact (or that have very tight spacing tolerances) HAVE to be lubricated properly. If you run low on oil, or let it get dirty or emulsified, severe damage will follow. Keeping an eye on the oil level, and changing it (and the filter) at the manufacturer’s recommended intervals, is critical.
    • Emulsified or otherwise contaminated oil can damage seals, gaskets, and o-rings. That’s obviously a big problem for the compressor, and when it carries over into the header, it’s a big problem for pneumatic cylinders & tools as well. Periodic sampling & analysis of your oil can provide timely notice of issues that can be corrected before they become catastrophic failures.
    • Depending on the type of compressor, and its drive system, the manufacturer’s maintenance recommendations may also include:
      • Checking coupling or belt alignment of the drive.
      • Checking bolts for loosening due to vibration (a “necessary evil”, especially with reciprocating compressors).
      • Adjusting the pistons to maintain valve plate clearance.
      • Tightening or replacing the mounts & vibration pads.

If you’d like to find out more about how EXAIR Corporation can help you get the most out of your compressed air system, give me a call.

Russ Bowman, CCASS

Application Engineer
EXAIR Corporation
Visit us on the Web
Follow me on Twitter
Like us on Facebook

Image courtesy of PEO ACWA Some rights reserved Creative Commons Attribution 2.0 Generic (CC BY 2.0)