Control Your Compressed Air

March 22, 2016Ken Bean

Compressed Air Controls

Improving and maintaining compressed air system performance requires not only addressing individual components, but also analyzing both the supply and demand sides of the system and how they interact, especially during periods of peak demand. This practice is often referred to as taking a systems approach because the focus is shifted away from components to total system performance.

Latest edition controllers from both the OEM and aftermarket suppliers offer the most sophisticated algorithms for unit control and incorporate sensitive digital sensing devices which all combine to give you the most efficient and reliable control. The better control you have of your compressor allows operators to select the lowest possible operating pressure allowing the plant to save significant money on operations and maintenance costs. Almost all of these controllers offer remote monitoring and remote control where operators are not required to be standing by in the compressor area to monitor data points or select update operating methods.

Controls from IZ Systems offer a complete compressor control automation package capable of handling any type of compressor, dryer, cooling tower or chiller system. Thus allowing integrated control of the entire system which further reduces the operations cost and further improves reliability.

Should I Use Compressed Air?

March 15, 2016March 15, 2016Ken Bean

Decisions, Decisions!

Last month I posted an article discussing the options of using compressed air vs. electric. There were several questions regarding cost calculations.

As a follow up, Todays post will discuss compressed air cost calculations to determine if compressed air should be used for specific applications.

This allows you to determine if compressed air should be used in specific applications (ie. as fans or blowers), or if other electric-motor operated equipment would be more efficient.

First calculate the volume of air produced annually for a specific operation by multiplying:

horsepower (hp)

cubic feet per minute per horsepower (cfm/hp)

total operating hours per year (hr/yr)

60 minutes per hour (60 min/hr)

% time fully loaded

% full-load horsepower

Volume of air produced annually

Then calculate the cost per 1,000 cubic feet (cf) by dividing the total energy cost to operate the air compressor by the volume of air produced annually, then multiply by 1,000. Cost per year / Volume of air products * 1000 cf

Example Calculations

The following example represents a typical small job-shop manufacturer.

A facility operates a 100 hp air compressor 4,160 hours annually. It runs fully loaded, at 94.5 percent efficiency, 85 percent of the time. It runs unloaded at 25 percent of full load at 90 percent efficiency, 15 percent of the time. The electric rate is $0.06 per kWh, including energy and demand costs. The cost per year to power the air compressor will be as follows.

Fully Loaded

Unloaded

The total annual energy cost to operate the air compressor is $17,524. The following calculation shows how much it will cost to use compressed air to operate a specific end use. Assume 3.6 cfm per horsepower and that this rate applies when the compressor is fully loaded.

Volume of air produced annually Cost per 1,000cf ($17,524 / 76,377,600) * 1000 = $0.23

Over the life of a compressor, energy costs will be five to 10 times the compressor’s purchase cost. Energy savings can rapidly recover the extra capital required to purchase an energy-efficient air compressor .

A 1.17 rated horsepower air operated mixer uses 45 cfm at 80 pounds-per-square-inch (psi) and operates 40 hours per week. The cost of the compressed air to operate this motor over a year is $1,292. A comparably sized electric motor of Energy Policy Act (EPACT) efficiency, rated for hazardous locations, is around $350. The cost to operate the EPACT motor under the same conditions is less than $100 per year. Including installation, payback is under one year.

Pressure Fluctuation

March 8, 2016Ken Bean

So there are locations in your compressed air system that the pressure just seems to fluctuate? With the maze of pipes, you have to consider pressure drop for certain areas. Most clients compensate for low or fluctuating pressures with a common fix: Raise the compressor output pressure. While this will usually solve the low pressure problem it rarely solves fluctuation and in addition it also increases your cost of power to produce higher pressure air. The input power for a compressor increases 1% for every 2 PSIG in pressure elevation! So what’s a plant to do?

Pressure/Flow Controllers

Pressure/Flow Controllers (P/FC) are system pressure controls that can be used in conjunction with the individual and multiple compressors. A P/FC does not directly control a compressor and is generally not part of compressor package. A P/FC is a device that serves to separate the supply side of a compressor system from the demand side, and requires the use of storage. Controlled storage can be used to address intermittent loads, which can affect system pressure and reliability. The goal is to deliver compressed air at the lowest stable pressure to the main plant distribution system and to support transient events as much as possible with stored compressed air. In general, a highly variable demand load will require a more sophisticated control strategy to maintain stable system pressure than a consistent, steady demand load.

“Credit to the US DOE for the preceding paragraph”

Contact a compressed air professional to discuss your particular low or fluctuating pressure concerns.

Can Your Air Compressor Make Phone Calls

March 1, 2016August 3, 2016Ken Bean

I read an article (link below) Sunday night from “Plant Services” discussing how the IIoT is coming to compressed air. If you’re not familiar with IIoT, it’s the industrial version of the IoT. In case you’ve not heard of IoT, let me give you a quick explanation. IoT stands for the “Internet of Things” and subsequently, IIoT stands for the “Industrial Internet of Things”.

The premise of IoT is that you and your entire home can be connected with all the components and subsystems being able to communicate and interact with each other. Basically, a Smart Home. What drives me crazy is that the authors of these articles promote this is new. This is NOT NEW! My house has been automated for over 20 years. The lighting, HVAC, security system, garage doors, home theater, whole house sound system along with others all respond to the central computer that controls it all and can be activated by buttons on my iPhone, keypads in the house or timed based controls. It doesn’t need access to the internet, nor do I want it connected to the internet. One less thing I have to be concerned with related to viruses and hacking. Sure a connection to the internet could add a few features to my system but it’s not worth the worry at this point.

Now on the article in “Plant Services” discussing IIoT and how its coming to compressed air equipment. It states how compressed air equipment utilizing IIoT and connecting to the internet will be “a game changer based on the energy-saving impact”. It further states “it will bring smarter control for better efficiency and easier compliance reporting”. My question is: compliance to what and reporting to who?

The goal of any compressed air system in today’s world is better efficiency but you certainly do not need an internet connection for that to happen. My vendor for central compressed air system control (IZ Systems) has been providing this capability for years. Maybe not as long as my house has been automated but for a lot of years. The current system doesn’t require changes to the local controls and can be tied into nearly any type or brand of compressed air equipment. Thus making the system reliable as any failure in the central system will revert control back to the local controller.

The key to energy efficiency has nothing to do with the internet but rather with the central processor that controls the compressed air equipment while monitoring the entire compressed air system and more importantly, the proprietary algorithm that resides in the central processor. Yes, they can use an internet connection to remotely monitor the system but this plays no part in the efficiency and in fact, many of my existing clients will not allow their equipment to access an internet connection due to the same concerns I have over my house. Additional security concerns. The benefits just don’t outweigh the potential headaches.

But, the article states, with the IIoT, my compressor can call the service technician if there is a potential problem. I’m sure this would save all my clients some time however most of my clients already tie equipment monitoring into their DCS and trend various data points such as temperature, pressure and vibration. If there is an escalating problem the DCS notifies them and they determine who needs to be called for further inspection or repair. So in my opinion, having your air compressor make phone calls is not going to add a lot of hours to your day.

Rather than waiting and hoping the IIoT progresses to a usable point, in my opinion, your money would be better spent investing today in a solid service contract with a company that can provide true vibration analysis. I’m not talking about trending but rather vibration analysis by professionals that know what the frequency’s should be on your equipment and can spot problems from one initial vibration analysis.

I think you can determine that I’m no luddite. In fact, quite the opposite. I love technology and the great things it can provide us. I just don’t want my clients getting caught up in the wave of hype surrounding a supposed new technology and spending money on features that are either easily available today or worse, for something they don’t really need.

Perhaps as the IIoT progresses I’ll be proven wrong and this technology can truly provide value to my clients. But for today, I see it as a half baked cookie that nobody really needs to bite into.

Here is a link to the original article if you’re interested.

Desiccant Dryer Control

February 21, 2016Ken Bean

Desiccant air dryers utilize a tremendous amount of energy through the consumption of compressed air and/or heat to regenerate the desiccant bed.

The use of hygrometers or dew point meters is commonly applied to reduce the amount of energy usage.

A recent article by “Compressed Air Best Practices” informs end users that this type of control is not the panacea that manufacturers would have you believe.

Seeing is not always believing

However, the use of an in (desiccant) bed capacitance probe can assure a lifetime of proper operation with no calibration required. The AMLOC capacitance probe used exclusively on dryers manufactured by Pneumatic Products Corporation (PPC)

AMLOC®

The AMLOC Energy Management Systems maintain accuracy, dew point stability and never need recalibration. Patented one quarter century ago, AMLOC® generates tens-of-thousands of dollars in energy saving annuities for industry leaders. The model of durability, THE PTFE or ceramic coated, stainless steel capacitance probes sense the changes to the dielectric constant imparted upon the desiccant by the extracted water vapor. Capable of identifying an aging or fouled bed, desiccant regeneration cycles are managed with precision.

Air or Electric

February 16, 2016Ken Bean

Air Audits can discover a multitude of energy saving ideas in your plant.

Point Of Use Compressed Air Storage

February 9, 2016Ken Bean

There are frequent articles on the site touting the benefits of compressed air storage. We usually refer to large receiver tanks as the ones pictured above. This article will focus on the benefits of local storage or receivers located at or near the point of use where there are one of just a few intermittent high flow demands. I have found this technique to be extremely beneficial in bag house pulsing applications.

A correctly-sized storage receiver close to the point of the intermittent demand with a check valve and a metering valve can be an effective and lower cost alternative. For this type of storage strategy, a check valve and a tapered plug or needle valve are installed upstream of the receiver. The check valve will maintain receiver pressure at the maximum system pressure and only allow air to be consumed from the receiver when the system line pressure falls below the pressure of the receiver. The plug or needle valve will meter the flow of compressed air to “slow fill” the receiver during the interval between demand events. This will have the effect of reducing the large intermittent requirement into a much smaller average demand.

Understand Your System

February 2, 2016Ken Bean

Compressed air system’s are complex. Each components carries it’s own difficulties in understanding but once multiples of these components are installed in an industrial plant, a simple area drawing gets complicated really quick.

Before implementing energy reduction strategies, be familiar with all aspects of your compressed air system.

System Supply

Analyze the supply side of your compressed air system for the types of compressors and dryers used, suitability and settings of capacity controls and other operating conditions. Understand the basic capabilities of the system and its various modes of operation. Verify that air compressors are not too big for end uses. For example, an air compressor is oversized if the end use only requires air pressure that is 50 % of the pressure that the compressor is capable of producing. Once the big picture is in view, supply side operating conditions can be modified, within the constraints of the compressed air unit, to better match the demand side uses of compressed air.

System demand

Identify all the uses of compressed air in the plant. Quantify the volume of air used in each application and generate a demand profile, quantity of air used as a function of time, for the compressor. Equipment specifications for operations that use air are good resources for obtaining data on air volume use rates. The profile highlights peak and low demand. A general assessment of compressed air use will help identify inappropriate uses of air.

System diagram

Develop a sketch of your compressed air system including compressors, dryers, receivers, filtration, drain traps, air supply lines with dimensions, and compressed air end uses to provide an overall view of the entire compressed air process.

Distribution system

Investigate the distribution system for any problems related to line size, pressure loss, air storage capacity, air leaks and condensation drains. Verify that all condensation drains are operating properly because inadequate drainage can increase pressure drop across the distribution system.

Maintenance

Evaluate maintenance procedures, records and training. Ensure that procedures are in place for operating and maintaining the compressed air system, and that employees are trained in these procedures.

Qualified audit engineers can give you a complete understanding of your system.

Keep Your Money

January 26, 2016January 26, 2016Ken Bean

Conservation Strategies for Compressed Air Systems

Identify easy to implement energy conservation opportunities in your compressed air system by conducting a walk-through assessment. Simple conservation opportunities can result in savings up to 25% of the current cost to run the compressed air system.

Leaks

Routinely check your system for leaks. A distribution system under 100 pounds-per-square-inch gauged (psig) of pressure, running 40 hours per week, with the equivalent of a quarter-inch diameter leak will lose compressed air at a rate of over 100 cfm costing over $2,800 per year. In noisy environments an ultrasonic detector may be needed to locate leaks.

Compressor pressure

The compressor must produce air at a pressure high enough to overcome pressure losses in the supply system and still meet the minimum operating pressure of the end use equipment. Pressure loss in a properly designed system will be less than 10% of the compressor’s discharge pressure found on a gage on the outlet of the compressor. If pressure loss is greater than 10%, evaluate your distribution system and identify areas causing excessive pressure drops. Every two PSI decrease in compressor pressure will reduce your operating costs 1.5%.

Identify artificial demands

Artificial demand is created when an end use is supplied air pressure higher than required for the application. If an application requires 50 psi but is supplied 90 psi, excess compressed air is used. Use pressure regulators at the end use to minimize artificial demand.

Inappropriate use of compressed air

Look for inappropriate uses of compressed air at your facility. Instead of using compressed air, use air conditioning or fans to cool electrical cabinets; use blowers to agitate, aspirate, cool, mix, and inflate packaging; and use low-pressure air for blow guns and air lances. Disconnect the compressed air source from unused equipment.

Heat recovery

As much as 80 to 90% of the electrical energy used by an air compressor is converted to heat. A properly designed heat recovery unit can recover 50 to 90% of this heat for heating air or water. Approximately 50,000 British thermal units (BTUs) per hour is available per 100 cfm of compressor capacity when running at full load. For example, consider a 100 hp compressor that generates 350 cfm at full load for 75% of the year. If 50% of heat loss is recovered to heat process water, the savings, at $0.50 per therm, would be about $4,100 per year in natural gas.

Inlet air filters

Maintain inlet air filters to prevent dirt from causing pressure drops by restricting the flow of air to the compressor. Retrofit the compressor with large-area air intake filters to help reduce pressure drop.

Compressor size

If your compressor is oversized add a smaller compressor and sequence-controls to make its operation more efficient when partially loaded. Sequence-controls can regulate a number of compressors to match compressed air needs, as they vary throughout the day.

Air receiver/surge tank

If your compressed air system does not have an air receiver tank, add one to buffer short-term demand changes and reduce on/off cycling of the compressor. The tank is sized to the power of the compressor. For example, a 50 hp air compressor needs approximately a 50-gallon air receiver tank.

Cooler intake air

When ingesting cooler air, which is more dense, compressors use less energy to produce the required pressure. For example, if 90 degree F intake air is tempered with cooler air from another source to 70 degree F, the 20 degree F temperature drop will lower operating costs by almost 3.8%.

V-belts

Routinely check the compressor’s v-belts for proper tightness. Loose belts slip more frequently which reduces compressor efficiency.

An air audit performed by a professional auditing company can find tremendous savings in your compressed air system. Consider an audit as an investment for your companies future.

Compressed Air For Free

January 19, 2016Ken Bean

If you are a regular reader, you frequently see post’s discussing the extreme cost of compressed air. We spend a lot of time posting of various ways to reduce the cost of producing compressed air for your applications and how to optimize your compressors to reduce the cost of electricity.

Following up on last weeks article discussing gas turbine drivers, This week I wanted to discuss the benefits of utilizing a steam turbine driver for your centrifugal compressor.

Wouldn’t it be great if you could run your air compressors for FREE! Of course it would but how could that be possible? Certain large industrial clients use a tremendous amount of steam for plant applications. The steam is often produced at a higher than use pressure and therefore the plant will incorporate steam pressure reduction valves (PRV’s) in the plant where the steam pressure is reduced from it’s output pressure from the boiler or steam generator to the required use pressure in the plant.

Rather than incorporate a PRV, a better use would be to incorporate a steam turbine which can drive the air compressor and put the reduced pressure steam back into a lower pressure steam system. I have a particular client that takes in 575 pounds of steam pressure to their steam turbine which is driving their centrifugal compressor and then downstream of the turbine, the steam is directed to their low pressure plant steam system at 110 pounds of pressure.

I’m sure when most people think of a steam turbine, the initial thought is a huge piece of equipment that perhaps drives a generator at a power plant. However, from the picture above you can see that small turbines can be incorporated into plant use for a variety of applications. Another great feature of using steam turbines is you incorporate a large amount of horsepower from a very small footprint. A 2000 horsepower steam turbine has a much small footprint than a 2000 horsepower electric motor.

If you have excess steam in your facility and feel that driving your air compressor with steam is a viable alternative, feel free to contact me to discuss your particular requirements.