Tag: system efficiency

Drying Supply Side Air With Heat of Compression Dryers

Published on by Brian FarnoLeave a comment

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/

Keys to an Efficient Compressed Air System

Published on by Lee EvansLeave a comment

How do I make our compressed air system efficient?

This is a critical question which plagues facilities maintenance, engineering, and operational personnel.  There are concerns over what is most important, how to approach efficiency implementation, and available products/services to assist in implementation.  In order to address these concerns (and others), we must first look at what a compressed air system is designed to do and the common disruptions which lead to inefficiency.

The primary object of a compressed air system is to transport the compressed air from its point of production (the compressors) to its point of use (applications) in sufficient quantity and quality, and at adequate pressure for proper operation of air-driven devices.[1]  In order for a compressed air system to do so, the compressed air must be able to reach its intended destination in proper volume and pressure.  And, in order to do this, pressure drops due to improper plumbing must be eliminated, and compressed air leakage must be eliminated/kept to a minimum.

But, before these can be properly addressed, we must create a pressure profile to determine baseline operating pressures and system needs.  After developing a pressure profile and creating a target system operating pressure, we can move on to the items mentioned above – plumbing and leaks.

Proper plumbing and leakage elimination

The transportation of the compressed air happens primarily via piping, fittings, valves, and hoses – each of which must be properly sized for the compressed air-driven device at the point of use.  If the compressed air piping/plumbing is undersized, increased system (main line) pressures will be needed, which in-turn create an unnecessary increase in energy costs.

In addition to the increased energy costs mentioned above, operating the system at a higher pressure will cause all end use devices to consume more air and leakage rates to increase.  This increase is referred to as artificial demand, and can consume as much as 30% of the compressed air in an inefficient compressed air system.[2]

But, artificial demand isn’t limited to increased consumption due to higher system pressures.  Leaks in the compressed air system place a tremendous strain on maintaining proper pressures and end-use performance.  The more leaks in the system, the higher the main line pressure must be to provide proper pressure and flow to end use devices.  So, if we can reduce leakage in the system, we can reduce the overall system pressure, significantly reducing energy cost.

 

How to implement solutions

Understanding the impact of an efficient compressed air system is only half of the equation.  The other half comes down to implementation of the solutions mentioned above.  In order to maintain the desired system pressure we must have proper plumbing in place, reduce leaks, and perhaps most importantly, take advantage of engineered solutions for point-of-use compressed air demand.

The EXAIR Ultrasonic Leak Detector being used to check for leaks

Once proper plumbing is confirmed and no artificial demands are occurring due to elevated system pressures, leaks in the system should be addressed.  Compressed air leaks are common at connection points and can be found using an ultrasonic noise sensing device such as our Ultrasonic Leak Detector (ULD).  The ULD will reduce the ultrasonic sound to an audible level, allowing you to tag leaks and repair them.  We have a video showing the function and use of the ULD here, and an excellent writeup about the financial impact of finding and fixing leaks here.

The EXAIR catalog – full of engineered solutions for point-of-use compressed air products.

With proper plumbing in place and leaks fixed, we can now turn our attention to the biggest use of compressed air within the system – the intended point of use.  This is the end point in the compressed air system where the air is designed to be used.  This can be for blow off purposes, cleaning, conveying, cooling, or even static elimination.

These points of use are what we at EXAIR have spent the last 34 years engineering and perfecting.  We’ve developed designs which maximize the use of compressed air, reduce consumption to absolute minimums, and add safety for effected personnel.  All of our products meet OSHA dead end pressure requirements and are manufactured to RoHS, CE, UL, and REACH compliance.

If you’re interested in maximizing the efficiency of your compressed air system, contact one of our Application Engineers.  We’ll help walk you through the pressure profile, leak detection, and point-of-use engineered solutions.

Lee Evans
Application Engineer
LeeEvans@EXAIR.com
@EXAIR_LE

 

[1] Compressed Air Handbook, Compressed Air & Gas Institute, pg. 204

[2] Energy Tips – Compressed Air, U.S. Department of Energy