Industrial Utility Efficiency    

Air Compressors

As an end user, have you ever heard the message to put in the biggest VFD air compressor, and the system will always be reliable and efficient.  Why do an audit?  Just add up the compressors on site and put one VFD for that size or larger.  Why have the complexity of multiple compressors, storage, sequencing, etc?  Even better, put in two of them, one for the whole system, and one for back-up.  If you could wave a wand, wouldn’t that be what every system should look like?  Perfect peace and efficiency, with 100% confidence of reliability.
The purpose of this article is to investigate the cause and effect that can occur when you reduce demand with no supply changes and the alternative which will produce positive, long term results which you can take to the bank.
This textile plant uses compressed air in their knitting, sewing, and dye house operations and needed a system designed for the significant fluctuations in demand. Compressed air demand profiles were placed into four segments; 1st shift peak demand and minimum demand, and 2nd shift peak demand and minimum demand.
Compressed air systems are a source of power (a utility) present in virtually all manufacturing and process industries. What is unique about this utility is that facilities own the utility and are responsible for all the installation, generation, transmission, and maintenance costs of the compressed air system. Outsourcing compressed air as a utility, while not a new idea, is a growing trend in industry as service providers have increased their ability to meet customer expectations.
While biodegradable, energy efficient, and recyclable are terms that come to mind when thinking about protecting the environment we live in today, these three terms are also, ironically, directly related to protecting a company's bottom line... profit.
Its simple physics that compressing air gives off heat. The heat energy is concentrated in the decreasing volume of air. To maintain proper operating temperatures, the compressor must transfer excess heat to a cooling media before the air goes out into the pipe system. As much as 90 percent of that heat can be recovered for use in your operation. If you can supplement or replace the electricity, gas or oil needed to create hot water for washrooms, or direct warm air into a workspace, warehouse, loading dock, or entryway, the savings can really add up.
Since the cost of energy has dramatically increased during the past few years, it seems that energy audit companies have opened shop on more city street corners than coffee shops in Seattle.  In addition to the mass numbers and abundant varieties of these energy savings promoters, there have been an equal number of energy audit articles written for the engineering magazines.  
In the U.S. as an example, the NFPA has taken the view that if your compressor draws in good clean ambient air, the air stays clean through the compressor, is then dried and filtered, when you deliver it to the patient it will be entirely satisfactory. After all, when you went into the hospital that’s what you were breathing and when you leave you will breathe it again!
Located in the bowels of most hospitals, you will find the source of the Level 1 Medical Air compressed air system. Per the NFPA Section 99 Specification (National Fire Protection Association), Level 1 air compressor systems provide air for human consumption within the hospital facility.
Roxane Laboratories, Inc., a subsidiary of Boehringer Ingelheim Corporation located in Columbus, Ohio, created a world-class air system that generated $61,314 per year in electrical energy cost savings (1,156,868 kWh), improved productivity and quality, and allowed the successful completion of a significant plant expansion.
This aluminum mill spends $369,000 annually in energy costs to operate their compressed air system. This system assessment recommends actions reducing annual energy costs by $120,000 and improving productivity and quality by delivering clean, dry compressed air.