Intelligent Compressed Air: Refrigerant Dryers and How They Work

We’ve seen in recent blogs that Compressed Air Dryers are an important part of a compressed air system, to remove water and moisture to prevent condensation further downstream in the system.  Moisture laden compressed air can cause issues such as increased wear of moving parts due to lubrication removal, formation of rust in piping and equipment, quality defects in painting processes, and frozen pipes in colder climates.  The three main types of dryers are – Refrigerant, Desiccant, and Membrane. For this blog, we will review the basics of the Refrigerant type of dryer.

All atmospheric air that a compressed air system takes in contains water vapor, which is naturally present in the air.  At 75°F and 75% relative humidity, 20 gallons of water will enter a typical 25 hp compressor in a 24 hour period of operation.  When the the air is compressed, the water becomes concentrated and because the air is heated due to the compression, the water remains in vapor form.  Warmer air is able to hold more water vapor, and generally an increase in temperature of 20°F results in a doubling of amount of moisture the air can hold. The problem is that further downstream in the system, the air cools, and the vapor begins to condense into water droplets. To avoid this issue, a dryer is used.

Refrigerated Dryer

Fundamental Schematic of Refrigerant-Type Dryer

Refrigerant Type dryers cool the air to remove the condensed moisture and then the air is reheated and discharged.  When the air leaves the compressor aftercooler and moisture separator (which removes the initial condensed moisture) the air is typically saturated, meaning it cannot hold anymore water vapor.  Any further cooling of the air will cause the moisture to condense and drop out.  The Refrigerant drying process is to cool the air to 35-40°F and then remove the condensed moisture.  The air is then reheated via an air to air heat exchanger (which utilizes the heat of the incoming compressed air) and then discharged.  The dewpoint of the air is 35-40°F which is sufficient for most general industrial plant air applications.  As long as the compressed air stays above the 35-40°F temperature, no further condensation will occur.

The typical advantages of Refrigerated Dryers are-

  1.  – Low initial capital cost
  2.  – Relatively low operating cost
  3.  – Low maintenance costs

If you have questions about getting the most from your compressed air system, or would like to talk about any EXAIR Intelligent Compressed Air® Product, feel free to contact EXAIR and myself or one of our Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer

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Don’t Waste Your Money (or Compressed Air)

This week I worked with a customer trying to separate a 135” wide paper sheet from a fabric used for commercial paper towel machines. They were using 45 spray nozzles, spaced 3” apart on a manifold, to blow off the sheet which then would fall into a chute below. The nozzles were doing the job but they were growing more concerned with their compressed air expense for this process.

Competitor Nozzle

45 pcs. of this nozzle were replaced with EXAIR’s Super Air Knife to save $87,000 annually!

The current nozzle setup was also causing another issue – there were “empty voids or gaps” in the airflow between the nozzles, which resulted in creases in the fabric. They were considering adding more nozzles and spacing them 2” apart but that was only going to increase their compressed air expense, so I asked them to consider our Super Air Knife. They were intrigued but were concerned that they would consume more compressed air, you’ll see below that the Super Air Knife uses less air and eliminates the creasing problem because the Super Air Knife provides a continuous airflow from end to end.

After reviewing the specs, I determined that each nozzle was consuming 29.6 SCFM @ 90 PSIG of compressed air, meaning they were consuming 1,332 SCFM for the process (29.6 SCFM x 45 nozzles).

I recommended using (2) 48” and (1) 42” Aluminum Super Air Knives, coupled together, to provide a 138” laminar sheet of airflow. I chose these In Stock – Ready to Ship lengths, so the customer wouldn’t have to order a special length even though that lead time would have only been 3 days. The Super Air Knife only consumes 2.9 SCFM @ 80 PSI (per inch of knife), and provides a laminar sheet of uniform airflow with a 40:1 air amplification rate, which would not only perform in the application, but also provide the needed compressed air savings.

SAK

What a great replacement for multiple nozzle manifolds! How SAK works

Using the above air consumption for our Super Air Knife, 2.9 SCFM @ 80 PSI (per inch of knife or 2.9 SCFM x 138”), I calculated the Super Air Knife consuming 400.2 SCFM @ 80 PSIG.

Since their process is a 24 hour operation, Monday – Friday, every week of the year, I calculated the following (* Using $ 0.25 per 1000 SCF used):

  • 45 nozzles x 29.6 SCFM = 1,332 SCFM @ 90 PSIG
  • 1332 SCFM (current) – 400.2 SCFM (EXAIR proposed) = 931.8 SCFM saved
  • 931.8 SCFM x 60 minutes x $ 0.25 / 1000 SCF = $ 13.98 saved per hour
  • $ 13.98 per hour x 24 hours = $ 335.52 saved per working day
  • $ 335.52/day x 5 days = $ 1,677.60 saved per week
  • $ 1,677.60 week x 52 weeks = $ 87,235.20 in yearly savings

After reviewing this savings with the customer, they mentioned they were glad they called because they were looking at increasing their air compressor size or purchasing another auxiliary unit. Now, they were not only going to save money on their current process, but they were eliminating the need to spend major funding on another compressor – not to mention the saved compressed air being available for future growth and processes.

At EXAIR, we commit to providing our customers with solutions to optimizing their current compressed air system.

Please contact an Application Engineer for optimizing your system today.

Justin Nicholl
Application Engineer
justinnicholl@EXAIR.com
@EXAIR_JN

 

Ionizing Point Best Thing for Static on Trim Scrap in Cyclone Separator

This application came in from our distributor (AYRFUL) in Argentina. They had a customer who is recycling film scraps. The scrap material is conveyed into a cyclone separator. The problem is that the scrap becomes charged with static as a result of the motions and interactions within the conveying pipe. This results in the scrap sticking to itself and to the parts of the cyclone separator inside. The problem is so bad that it becomes almost impossible to separate the material when it comes time to clear it out of the cyclone separator once clogged.

After discussing the challenges the customer faced in trying to keep their cyclone up and running, we decided to recommend that the customer utilize 4 pieces of EXAIR’s Model 7199 Ionizing Point and 1 piece of Model 7941 (4 outlet Power Supply) to neutralize the static within the cyclone.

The ionizing Points would be attached by means of inserting through the wall of the inlet pipe of the cyclone separator.

Ion Point

cyclone

The existing blower moving air into the cyclone separator will do the job of carrying the positive and negative ions into the cyclone separator and keep it and the contents at a neutral state.

If you have a similar problem, contact us to discuss the application. We would be glad to help with our full range of static eliminators to address your application issues.

Neal Raker, Application Engineer
nealraker@exair.com

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