Posted by Tom Fitz
Tom Fitz
Tom utilizes over eighteen years of manufacturing experience to help companies c
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on Tuesday, 14 February 2012
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Energy Hogs of Manufacturing

Compressed Air Remains a Costly Utility

I plan on devoting my next few blogs analyzing the four primary energy consumers in a typical manufacturing environment. Obviously, every facility relies on different utilities to run their operation depending on processing needs, but the majority would see compressed air, HVAC, production machinery/equipment, and lighting as the big four energy users.

Compressed air can account for approximately 30 percent of a facility’s energy use. What tends to inflate the usage is the overall inefficiency of most systems. Some analysis has revealed that as little as 8 to 10 percent of the total energy supplied to the compressor is converted to usable energy at the point of use. Contributing to the inefficiency are leaks, air intake flaws, poor maintenance of unit, lack of monitoring, and/or specification and design flaws.

A study by the Carbon Trust estimates businesses in the U.K. could save up to $173 million by taking minimal actions, at little to no cost, to improve the efficiencies of compressed air systems. Imagine what the rest of the world is throwing away?

Following are several tips I have used with clients to optimize their overall systems:

  • Eliminate leaks - Although it seems like a basic step, it’s truly unbelievable how many companies willingly operate their systems with detected air leaks. I’d compare this practice to spraying a crowd of people with a money gun.
  • Run time - Simply put, only have the compressors in operation when use points are calling for demand. Power off the compressors when not needed. There are relatively inexpensive automated timers available that easily affix to most systems that can be programmed for automatic shutdown control. Other alternatives include controlling multiple compressors with an electronic sequential controller, and integrating system controls into plant control or building management systems.
  • Specification - Calculate the peak amount of air needed and install the appropriate size compressor. Too many cases exist where units have been installed that are two, three, four times the peak load, which leads to the units running inefficiently.
  • Design - Locate the compressor as close to use points as possible to reduce the amount of supply piping. Also, challenge the pressure needed at each use point so the lowest possible pressure can be maintained by the system. It’s amazing the efficiency gains realized when working pressures are dropped from 80 psi to 60 psi to 40 psi etc.
  • Break tank - If possible, design a break tank into a new, or retrofit into an existing, system. The compressors will be responsible for maintaining the pressure of the break tank rather than the entire supply system contributing to major gains in efficiency.
  • Maintenance - Routine servicing of the compressors and entire system will not only maximize efficiencies, but prolong the life.
  • Air intake - Improving air intake quality by ducting from a suitable location that is clear from exhaust ducts, free from obstructions and protected from the elements will aid the operation of the system. Also, inspection of the air intake filters ensuring they are not dirty or blocked during scheduled preventative maintenance is a must.

The prior menu of action steps reveals some low cost (many zero cost) ways to improve the operation and efficiency of compressed air systems. Many other steps can be taken with the ultimate goal being to improve overall system efficiencies. Remember, each percentage point of efficiency gained equates to money being saved and reducing your company’s GHG footprint!

 

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