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Benefits: Energy

Compressed air systems are critical to a number of functions within a manufacturing facility. But poorly designed and maintained compressed air systems, by some estimates, account for up to $3.2 billion in wasted utility payments in the United States every year. One quick and easy way to ensure your facility isn't squandering energy in its compressed air production process is to consider the benefits that can be provided by operating the compressed air system at constant pressure.

While many plants require continuous, round-the-clock operations seven days a week, there are likely cycles where lulls in production present opportunities for energy savings. For example, there are 168 hours in a week and most compressed air systems only require anything near full capacity between 60 and 100 hours, or about half the time. When an air compressor runs at 100 percent to accommodate demand that represents only 50 percent of the compressor's maximum output, then half of the energy required to power that compressor is immediately wasted. Variable speed drive air compressors continually and automatically vary the production and output of compressed air to meet fluctuating power requirements.

Statistics compiled through compressed air system assessments and performance analysis show that many air compressor applications are ideal for VSD. Compared to a fixed drive compressor, a properly sized VSD compressor can be operated for significant less power.

Energy costs, already on the rise in recent years, have garnered additional attention of late as facility managers are continually charged with finding new ways to cut costs.

Look at one case where a manufacturer was running a 200 horsepower air compressor 24 hours a day at 3 cents per kWh. These energy costs have doubled in the last five years, increasing in some areas to 8 cents per kWh or more. The annual cost to operate that compressor at 3 cents per kWh was $41,273. Today, at 8 cents per kWh, that same compressor costs $110,062 to operate every year, or more than $550,000 over five years. Staying with this example, switching to a VSD compressor could potentially save this facility $38,521 annually or $192,608 over five years.

And you can combine these savings with heat recovery. How much money do you think you can save if you harnessed a portion of the energy used to power your air compressors and used that recycled energy to heat water or direct warm air into a warehouse or loading dock?

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. Energy can be even more effectively recycled through built-in energy recovery systems that circulate cooling water through a compressor's compression elements and components and, as a result of the heat transfer, yield hot water at up to 90°C.

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.

Many manufacturers can typically recover approximately 90 percent of the electrical power needed for operations in the form of hot water, meaning the costs to run the compressor become revenue neutral through the offset or elimination of other energy costs.

Energy costs have shown a steady increase in recent years, but that doesn't mean that utility bills need to follow the same path. Taking advantage of cutting-edge engineering and technology can yield a number of positive returns.

 

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