Compressed air systems account for an average of approximately 10 percent of all industrial electricity consumption and can be as high as 40 percent of a plant’s electricity bill. Even within the most efficient compressed air systems, a small fraction of the energy required for the process — 10 to 15 percent — ultimately is delivered as compressed air. When an air compressor physically compresses air, the input electrical energy is converted into heat. The largest component of this energy transformation is heat loss. This heat appears at the compression elements, the oil cooler, intercooler and aftercooler.
There are two typical ways to reuse this energy — through hot air or heated water. The simplest solution is routing the hot air byproduct of the compression process to a warehouse or loading dock for supplemental heating during cool seasons, offsetting the energy otherwise required strictly and specifically to perform the same function.
Most industries can make use of hot water for space heating, showers and other such applications. However, many food and beverage manufacturers can benefit even more because of the prominent need for hot water and steam in their processes, including scalding, cleaning, sterilization, and melting. Hot water, as a byproduct of the air compression process, could also be used for locker room showers or other, conventional hot-water applications. Atlas Copco Compressors has developed the world’s first oil-free air compressor that can recover 90 percent of the electrical power needed for operations in the form of hot water. In specific design conditions, 100 percent of the power can be recovered as hot water, meaning the costs to run the compressor become revenue neutral through the offset or elimination of other energy costs.
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