Industrial Utility Efficiency
Over the last two decades, there has been a significant increase of manufacturing facilities deciding to produce their own nitrogen on-site, using compressed air systems and nitrogen generators. They are choosing on-site nitrogen generation, instead of purchasing and receiving deliveries of nitrogen by the cylinder or having a “Nitrogen Over the Fence” supplier.
Dew point is simply the temperature to which air must be cooled for the water vapor within to condense into dew or frost. At any temperature, there is a maximum amount of water vapor that the air can hold. This maximum amount is called the water vapor saturation pressure. If more water vapor is added beyond this point, it will result in condensation.
The foundation of any purification system is its filtration and of the ten main contaminants found in a compressed air system, filtration is responsible for the treatment of nine of them. Coalescing filters are the most important piece of purification equipment as they reduce six of the ten contaminants and a look in any air compressor room will find a pair of coalescing filters (backed up with dry particulate and oil vapor removal filters).
In the field of externally heated adsorption dryers there is a large variety of different systems on the market offering substantial flexibility in terms of process flows, dew points and energy demand. Often, economic parameters and project-specific requirements ultimately define the individual user-specific solution. This article discusses the basic types of desiccants used in compressed air dryers.
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.
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.
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.
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.
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.
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.
