Should saving energy be of interest to the industrial compressor user?
If you are using compressed air in your plant, your company is typically wasting energy which equates to wasted dollars. In fact, estimates indicate that poorly designed and maintained compressed air systems in the United States account for up to $3.2 billion in wasted utility payments every year."(1)
Here are 10 ways to to reduce energy use in your compressed air production:
1. Eliminate Compressed Air Leaks
"Leaks are a significant source of wasted energy in a compressed air system, often wasting as much as 20-30% of the compressor’s output." (2)
Some air leaks are big and easy to find. The reality is that often it is the many small leaks over dozens or hundreds of locations in a plant that create huge air waste and useless energy consumption.
Every leaking air fitting, every leaking air cylinder and valve, every air tool left on when idle is a potential source of leaks and energy loss.
2. New Equipment Leaks Air Too
Elimination of air leaks includes checking all new equipment. Every time a new piece of air-driven equipment is added or when a new air tool is connected it needs to be double checked to prevent new leaks.
New equipment can mean new plumbing as well. Plan before installation to ensure that any new piping works seamlessly with the old and possible air-use redundancyis weeded out.
Air audits are recommended to allow a third party to scrutinize the plant's air plumbing and to locate and systematically repair all air leaks.
3. Lower the System Air Pressure
Compressed air driven equipment will come with pressure and flow recommendations ensuring that the equipment has sufficient air supply.
The plant main system air pressure is typically provided at a higher pressure than most equipment needs.
When compressed air at too high a pressure is delivered to equipment that does not require that pressure, it may not create a problem for the equipment, yet driving equipment at that too high a pressure makes the compressor work harder to generate that higher pressure. That means energy waste and added cost.
"To produce compressed air at 120 psi compared with 100 psi, you must input about 10% more power for the same volume of air".(3)
4. Use Air Regulators
An air regulator installed before each piece of equipment could be used to regulate the air pressure to the actual level needed by that piece of equipment.
If a particular section of a machine requires higher pressure than the rest of the machine, run a line from the higher pressure main only to that section of the machine. Regulate that pressure to the lowest minimum operating pressure of that section.
5. Compressor Maintenance
A compressor not maintained to high operational standards is one that has to run longer than absolutely necessary.
The maintenance issues that can lead to increased energy usage include:
Plugged filters includes any air intake filters, air / oil separators and oil filters. As these get full of debris and plugged, the compressor has to work harder and hotter, increasing energy demand for increased cooling.
Whether compressor oil is lubricating oil for the mechanical operation of the compressor, or the rotary screw oil used to actually compress the air, plugged filters make the compressor work harder and hotter.
The filter for the screw-compressing oil is critical to the operation of the rotary screw compressor. This oil must be changed even more frequently than suggested by the maintenance schedule if the compressor is operating in harsh conditions. Otherwise, screw maintenance issues will arise, efficiency of the compressor will decline, and energy use will increase.
-Heat Exchangers / Condenser Coils
In order for heat exchangers and condenser coils to work, hot air must radiate efficiently from the coils to the atmosphere. Dust and oil coating interferes with that and results in a hotter running compressor. The greater cooling required uses more energy than normal.
Further, any air compressor that runs too hot is susceptible to heat related shutdown. Additional energy is required to restart a compressor. Sudden compressor shut down can also mean sudden air loss to the plant and production loss.
-Monitor Condensate Drains
Condensate drains remove water and the filtered-out contaminants from the compressor and air systems, and can be overlooked when doing system maintenance.
The result can be fluid buildup, filter contamination and then re-contamination of the compressed air. That generates substantial downside for air driven equipment supplied by that contaminated air.
Greater energy will be consumed as the compressor attempts to overcome the constricted flow issues created by blockages in the filter media.
Automatic "no-waste" drains are recommended to keep drains purged without requiring operator intervention.
7. Compressor Heat Recovery
Compressor-generated heat is always a by-product of compressing air. It is a logical step to try to capture that heat using it to offset energy consumption elsewhere in the plant.
"It is a thermodynamic fact that around 95% of this energy is converted to heat and is wasted to the atmosphere through heat dissipated by the motor and cooling system." (4)
Compressor heat recovery includes installing equipment to capture the heat, transporting it to the point of use, and using conversion equipment to put it to work.
Larger compressors that run for extended periods are optimal for reclaiming compressor generated heat.
8. Compressors Left On
A simple concept, but one that can be overlooked in manufacturing plants is, "Why leave the compressor on"? If the plant is shut down for extended periods or regularly overnight, and it is not detrimental to the plant operation, shut the compressor down.
If all air system leaks have not been fixed, that can cause the compressor to cycle needlessly, wasting energy.
9. Examine How Air Is Used
Looking at overall plant air usage through "new eyes" might pinpoint areas in which compressor energy can be reduced.
Would new, more efficient air tools reduce air demand, reducing compressor size and use?
If the load on air cylinders had changed with less mass, then a smaller cylinder might do the job with less air use.
10. Staff Training
Does the staff fully understand the need for diligence in reducing compressed air use?
Inefficient use of blow guns or longer-than-necessary parts blow off may waste air.
Operators need to check when the shift is done to ensure that air is off resulting in less waste.
An excellent defense against energy waste in any plant is a knowledgeable and well trained staff.
A compressor that is well maintained and run with energy conservation paramount will last longer than one that is not.
What would your compressor cost to replace?