Technology

To gain about one horsepower of mechanical energy from a compressed air powered motor it costs seven times as much at the input of the air compressor. And surprisingly between 20 and 30 percent of this valuable power is lost even before it gets to the end use. Further to this another 10 percent is lost to artificial demand caused by higher than required pressure, and to top that all off, another 10 percent is wasted by equipment that is either inappropriately supplied with compressed air or left to consume air even when the associated production machine has been turned off.

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.

What are the conditions inside your pipes, is it cloudy and hot with showers or cool and dry? Could there be snow and blowing snow and excessive icing conditions? Are there smog and dust storm conditions or is the air as fresh as a mountain breeze. All these conditions are commonly experienced inside compressed air systems. What you get is determined by your selection of system equipment, ambient conditions and how well your system is maintained.

This facility is part of a major corporation with dozens of manufacturing facilities where consumer good food products are processed and packaged for shipment to retail outlets. The factory was spending \$210,000 annually on energy to operate their compressed air system. This system assessment detailed four (4) project areas where yearly energy savings totaling \$100,855 could be found with an investment of \$100,000.

Anest Iwata was the first company in the world to develop the air-cooled, oil-free(dry), scroll vacuum pump. We provide a very compact package with lower vibration and noise levels than competitive offerings. Our oil-free vacuum pump market share, in Japan, is estimated to be fifty percent in the <600 L/min flow range.

Aeration systems at wastewater treatment facilities present significant, cost-effective energy savings opportunities. Aeration—the introduction of air into the wastewater stream to support anaerobic bacteria and mixing—is a key function at the majority of wastewater treatment facilities in North America. Aeration accounts for 25-60 percent of total energy consumption at wastewater treatment facilities , and a significant piece of operating budgets sector-wide.

We have industrial accounts where we mix chemicals and acids. Our favorite is blending wine and spirits using compressed nitrogen. The old way to blend was to use “air rousing.” This was done by installing rows of perforated pipes in the bottom of the tank and attaching an air pipe to this grid. Since the typical mixing cycle was 45 minutes, copious amounts of air and energy were used.

In recent years, there have been many changes in wastewater treatment. Most modern processes control three cycles: DO, NH4, and NO3, and all of the processes require high volumes of air. Undeniably, the low pressure air system uses more electrical power than the rest of the wastewater treatment plant combined. The blower packages in these systems can be equipped with low noise enclosures, fixed speed or variable speed drives, and can include all the instrumentation needed for self-protection.

A large multi-service public utility provider was faced with an ongoing problem. The utility, which services 93,000 retail and wholesale customers, employed five oil-free compressors at one power generation facility, but, if they needed to take down Unit 2 at the facility, it almost always pulled Unit 1 down with it, overloading the system’s capacity and causing service interruptions.

Compressed Air Best Practices® Magazine interviewed Ms. Julie Gass P.E., Lead Process Mechanical Engineer, from Black & Veatch on trends in the wastewater treatment industry especially pertaining to new technology aeration blowers and energy efficiency.