Compressed Air – The Fourth Utility

Industrial use of compressed air dates to the middle of the 19th century.  European engineers developed & used compressed air operated drills in the construction of the Mont Cenis Tunnel in 1861.  This type of machinery had typically been steam-powered, but you needed a fire to boil the water.  Since steam loses energy when piped over long distances, that means you’d need a fire in the tunnel shaft, and that’s not good for the miners.  Electric powered products were not a viable option…they weren’t developed to the scale needed for this, and generation & distribution were not up to the task back then.

Compressed air made the most sense, because it COULD be generated locally, outside the shaft, and plumbed in to the tools without energy loss (much of the energy from steam is lost when it condenses…and compressed air doesn’t condense.)  The Mont Cenis Tunnel project was a big deal in the advancement of industrial compressed air applications.  It was originally estimated to take 25 years, but, largely due to the success of the air operated drills, it was completed in only 14 years.  This got the attention of mining industry folks in America, where coal mining was growing exponentially in the late 1800’s.

The need for bigger & better machinery and tools kept pace with the growth in industry overall throughout this time, and even to the present day.  As the distribution grid spread to just about everywhere, electricity became the principal method of providing power.  Natural gas remains popular for especially large machinery, heating, and, in fact, for electric power generation.

Water has always been key to just about any human endeavor, from agriculture, to chemical production, to cleaning…which is universal to any industry.  Like electricity and natural gas, its distribution grid was also vital to industrial growth & production.

As the “fourth utility,” as it’s become known, compressed air is unique in that it’s customarily generated on site.  This gives control to the consumer, which is great, because they can decide how much they want to make, based on how much they want to use.  And, because many applications that can use compressed air can also be addressed through other means (more on that in a minute,) the powers-that-be can decide which one makes the most sense, big-picture-wise.

Here are some common industrial applications that can be handled pneumatically, or otherwise:

  • EXAIR is the industry leader in point-of-use compressed air product applications. Try us, you’ll see.

    Moving product from one place to another: air operated conveyors (like EXAIR Line Vacs) or electric powered belt/auger/bucket conveyors.

  • Force and motion: pneumatic, or hydraulic cylinders.
  • Cleaning: Compressed air blow off devices (like EXAIR Intelligent Compressed Air Products) or electric powered blowers…or brooms, brushes, and dustpans.
  • Rotary or impact tools: pneumatic or electric.
  • Cooling: Compressed air operated Vortex Tubes, or refrigerant based chillers, or chilled water.

The fact that there are four major utilities proves that there’s usually more than one solution to an application.  The challenge is, which one makes the most sense?  If you need help with data or recommendations from a compressed air industry expert, give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
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What is an Air Compressor?

Internals of an air compressor

What is an air compressor?  This may seem like a simple question, but it is the heartbeat for most industries.  So, let’s dive into the requirements, myths, and types of air compressors that are commonly used.  Like the name states, air compressors are designed to compress air.  Unlike liquid, air is compressible which means that it can be “squished” into a smaller volume by pressure.  With this stored energy, it can do work for your pneumatic system.

There are two types of air compressors, positive displacement and dynamic.  The core component for most air compressors is an electric motor that spins a shaft.  Positive displacement uses the energy from the motor and the shaft to change volume in an area, like a piston in a reciprocating air compressor or like rotors in a rotary air compressor.  The dynamic types use the energy from the motor and the shaft to create a velocity energy with an impeller.  (You can read more about types of air compressors HERE).

Compressed air is a clean utility that is used in many different ways, and it is much safer than electrical or hydraulic systems.  But most people think that compressed air is free, and it is most certainly not.  Because of the expense, compressed air is considered to be a fourth utility in manufacturing plants.  For an electrical motor to reduce a volume of air by compressing it.  It takes roughly 1 horsepower (746 watts) of power to compress 4 cubic feet (113L) of air every minute to 125 PSI (8.5 bar).  With almost every manufacturing plant in the world utilizing air compressors much larger than 1 horsepower, the amount of energy needed to compress air is extraordinary.

Let’s determine the energy cost to operate an air compressor to make compressed air by Equation 1:

Equation 1:

Cost = hp * 0.746 * hours * rate / (motor efficiency)

where:

Cost – US$

hp – horsepower of motor

0.746 – conversion KW/hp

hours – running time

rate – cost for electricity, US$/KWh

motor efficiency – average for an electric motor is 95%.

As an example, a manufacturing plant operates a 100 HP air compressor in their facility.  The cycle time for the air compressor is roughly 60%.  To calculate the hours of running time per year, I used 250 days/year at 16 hours/day for shifts.  So operating hours equal 250 * 16 * 0.60 = 2,400 hours per year.  The electrical rate at this facility is $0.10/KWh. With these factors, the annual cost to operate the air compressor can be calculated by Equation 1:

Cost = 100hp * 0.746 KW/hp * 2,400hr * $0.10/KWh / 0.95 = $18,846 per year in just electrical costs.

So, what is an air compressor?  The answer is an expensive system to compress air to operate pneumatic systems.  So, efficiency in using compressed air is very important.  EXAIR has been manufacturing Intelligent Compressed Air Products since 1983.  If you need alternative ways to save money when you are using your air compressor, an Application Engineer at EXAIR will be happy to help you.

John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb

 

Compressor internals image courtesy of h080, Creative Commons License.

More Efficient Compressed Air Use Could Lead To Energy Rebates

The use of compressed air can be found in almost any industry and is often referred to as a “fourth utility” next to water, gas and electric. The generation of compressed air accounts for approximately 1/3 of all energy costs in an industrial facility, in many cases, it’s the largest energy user in an industrial plant. With an average cost of $ 0.25 per every 1,000 SCF used, compressed air can be expensive to produce so it is very important to use this utility as efficiently as possible.

Utility companies recognize the benefit of using engineered products to reduce compressed air usage, like the ones manufactured by EXAIR, and offers rebate incentives for making a switch. Our local utility provider here in Cincinnati, Duke Energy, offers a $ 20 incentive for each replacement engineered nozzle.

 

Our Model # 1100SS 1/4″ FNPT and Model # 1101SS 1/4″ MNPT Super Air Nozzles

In their specification, the nozzle must meet a certain volumetric flow rate (SCFM) at 80 PSIG operating pressure for a given pipe size. For example, when looking at a 1/4″ nozzle, the flow rate must be less than or equal to 17 SCFM when operated at 80 PSIG. Our most popular nozzles for “general” blowoff applications would be our Model # 1100 (1/4″ FNPT) or our Model # 1101 (1/4″ MNPT) Super Air Nozzles. These nozzles require 14 SCFM @ 80 PSIG so this would be the ideal solution to reduce the air demand and take advantage of the rebate.

Here at EXAIR, much of our focus is to improve the overall efficiency of industrial compressed air operating processes and point of use compressed air operated products. If you’d like to contact one of our application engineers, we can help recommend the proper engineered solution to not only save on your compressed air usage but also assist with possible energy rebates available in your area.

Justin Nicholl
Application Engineer
justinnicholl@exair.com
@EXAIR_JN

 

 

FREE EXAIR Webinar – November 2nd, 2017 @ 2:00 PM EDT

On November 2, 2017 at 2 PM EDT, EXAIR Corporation will be hosting a FREE webinar titled “Optimizing Your Compressed Air System In 6 Simple Steps”.

During this short presentation, we will explain the average cost of compressed air and why it’s important to evaluate the current system. Compressed air can be expensive to produce and in many cases the compressor is the largest energy user in a plant, accounting for up to 1/3 of the total energy operating costs. In industrial settings, compressed air is often referred to as a “fourth utility” next to water, gas and electric.

Next we will show how artificial demand, through operating pressure and leaks, can account for roughly 30% of the air being lost in a system, negatively affecting a company’s bottom line. We will provide examples on how to estimate the amount of leakage in a system and ways to track the demand from point-of-use devices, to help identify areas where improvements can be made.

To close, we will demonstrate how following six simple steps can save you money by reducing compressed air use, increasing safety and making your process more efficient.

CLICK HERE TO REGISTER

Justin Nicholl
Application Engineer
justinnicholl@exair.com
@EXAIR_JN