Industrial Utility Efficiency    

Air Treatment/N2

Often when you mention heat of compression the first thought generally relates to HOC desiccant dryers, which are also an under-applied opportunity for heat recovery. However, there are many other heat of compression recoverable energy savings opportunities in all compressed air and gas systems. This article reviews many opportunities in energy heat recovery and provides answer to commonly asked question.
This article is intended to show the relationships between risks and specifications, opportunities and responsibility in validation, and in particular, the use of modern and calibrated measurement technology in the sample chain.
As part of an energy reduction effort, a Canadian technical college hired a compressed air auditor to do a leakage audit of their large campus, which houses over 30 mixed use buildings, including laboratories, research facilities, shops and classrooms. The audit found very few leaks, the reduction of which would achieve minimal savings; however, a few surprising items of interest were noticed during the study that showed very good potential for operating cost savings of 64% with an estimated $45,000 per year in reduced energy and water costs. This article discusses some of the findings and how savings can be achieved on lightly loaded compressed air systems.
Experienced auditors become wary when they see desiccant dryers installed in customers’ plants. These dryers are required when a plant needs instrument-quality compressed air, or when compressed air piping is exposed to freezing temperatures. However, while desiccant dryers can gain this level of quality, the energy cost of stepping up from a dewpoint of 35 oF to a level of -40 oF increases quite considerably. To attempt to reduce the energy costs of drying to these low levels, heated blower desiccant styles may be used. This article describes three common desiccant dryer types, as well as some experiences, good and bad, with heated blower types.
This major food manufacturing plant in the Midwest uses compressed air and onsite nitrogen generation to operate multiple snack production and packaging lines. The plant spends an estimated $430,344 annually on energy to operate its compressed air system based on an average rate of 4.5 cents per kWh.
The University of Manitoba Bannatyne Campus, Canada, upgraded its compressed air system to include variable speed drive (VSD) air compressors and the use of internal heat-of-compression (HOC) drying, replacing oil-free air compressors and refrigerated dryers that reached the end of useful life. In doing so, the campus reduced annual energy consumption by 15%, improved the quality of the compressed air to modern day instrument air standards and gained additional compressed-air capacity. The local utility also awarded the medical campus an incentive of $13,500, offsetting the cost of the initiative.  
A pharmaceutical plant, has had a compressed air assessment performed on two plant systems.  The studies uncovered poor compressed air production efficiency, high air dryer loss, and problems with high flow compressed air uses negatively affecting plant pressure. The plant implemented energy efficiency measures, on the two compressed air systems, saving 46 and 64 percent in energy costs respectively.
One of the most common problems in plants is low air pressure. One of the most common solutions is to purchase new air compressors. Often this advice leads to a poor return on investment with the company’s hard-earned money. Often the issues are related to demand, distribution, or both. Solving the wrong problem can be expensive from a capital and operating cost perspective. Determining root cause analysis may cost more up front, but will save tens if not hundreds of thousands of dollars long term.
A steel distribution and processing company has upgraded and consolidated the compressed air systems in two of their distribution and processing facilities for big energy savings. The previous compressed air systems were running in modes of operation with very low efficiency. A complete replacement of the two systems with new air compressors and dryers has reduced the energy consumption significantly.
This plant has three production lines producing snack food. Depending on the time of year and production demand the plant can operate anywhere from no production lines to all three production lines. A thorough supply and demand-side system assessment was done at this plant. This article will focus on some recommended demand-side reduction projects including nitrogen generation, air vibrators, leaks and vacuum venturis.
A small pulse crop and seed processing facility located in Canada has upgraded their facility compressed air system to accommodate the expansion of their production capacity.  While completing this project the facility has learned some valuable lessons about sizing and maintaining lubricated screw air compressors and compressed air drying equipment.