Industrial Utility Efficiency    

Air Compressors

There are many choices of compressor technology and types of controls that can be used for variable demands. Some examples are rotary screw compressors with inlet valve control: variable speed drives: load/unload control; or centrifugal compressors with variable inlet guide vanes. However, in many cases, the efficiency of the overall compression process can be reduced significantly during lower flow demands, leading to more power per unit of air flow being delivered. It is very important to evaluate different available options and see how a plant can run most efficiently.
Compressed Air Best Practices® Magazine recently discussed variable speed drive (VSD) air compressors with the Compressed Air and Gas Institute’s Technical Director, Rick Stasyshan and with CAGI member – Bob Baker of Atlas Copco. Their inputs should provide you with some insight to this energy-saving technology.
It is common to see energy assessment specialists treat centrifugal compressors like positive displacement compressors when attempting to reduce compressed air system energy consumption. Unfortunately, centrifugal compressors are normally much larger, and miscalculations can easily represent hundreds of thousands of dollars in overestimated energy savings. These errors are not malicious; they result from oversimplified best practices perpetuated by individuals with limited centrifugal compressor knowledge. This type of knowledge is not readily available and most energy assessment specialists do not have access to engineering teams responsible for the technical development and design of centrifugal compressors.
Grand Manufacturing, a small community owned Canadian agricultural products manufacturer, has upgraded their compressed air system as a result of a production expansion, yet increased the compressed air energy efficiency 61% by consolidating their system and implementing an innovative dual pressure control strategy.
This article reviews portions of an audit report commissioned to survey the condition of a compressed air system in a factory located in the U.S. The objective of this study is to determine the current operating conditions and make recommendations for improvement based upon application of industry recognized best practices. Due to article space limitations, this article will focus on portions of the over-all audit report provided to the factory.
Energy conservation measures (ECMs) associated with compressed air have received a significant amount of attention over the years, mostly due to a reasonably short financial return compared with other energy-consuming equipment. Over time, many of the recommended corrective actions to reduce compressed air energy consumption were simplified so much that they did not lead to positive results. One of the most common compressed air ECMs is reducing system pressure, and it leverages the best practice calculation —.5 percent power per psi — outlined in the Department of Energy’s Compressed Air Challenge. This article highlights more common issues associated with estimating energy conservation resulting from changing system pressure.
The story of Atlas Copco’s 140-year commitment to innovation. When thinking about innovation during the past century, the mind immediately wanders to consumer-facing brands that make products that are experienced by users – like a mobile computer and videophone that fits in our hands or the technology applications through which almost all modern business is conducted.
Compressed air quality is measured by the amount of solid particulates, water and oil content in one cubic foot (cu. ft.) of compressed air. Many of these contaminants are introduced from the air surrounding the installation site that is drawn into the system at the beginning of the compression process. The relative humidity, type of compressor and air treatment and filtration system can also affect air quality. Minimum air quality requirements vary by industrial application; the most stringent standards apply to manufacturers whose end products, packaging or critical instrumentation come in direct contact with compressed air.
When the Environmental Protection Agency was formed, in1970, it used its congressional mandate to issue all sorts of regulations regarding the discharge of contaminants into the land, water and air of this country. Over the years, air pollution has been one of the key areas where the Agency has put in place stringent requirements to control the emission of VOCs or Volatile Organic Compounds. Today the mandates of this government agency require extensive steps be taken to curtail their release by all operators of tank farms, chemical plants, refineries, fermentation plants and landfill operations. As a result of these regulations the Bio-Mass utilization industry was born.
Variable speed control for all types of industrial equipment is now readily available on the market with competitive pricing to non-variable speed controlled alternatives, including in the air compressor industry. With the advent of prescriptive rebate programs for variable speed compressors and other equipment, the demand for these types of controls has increased. General wisdom would recommend a variable speed compressor for all applications, or multiple variable speed compressors within each system.
Compressed air systems are present in almost all industrial processes and facilities. They have been correctly identified as an area of opportunity to reduce electrical (kW) energy costs through measures like reducing compressed air leaks and identifying artificial demand and inappropriate uses. Water-cooled air compressors can also be significant consumers of water and reducing these costs can represent a second area of opportunity.