What is vacuum as used in the manufacturing/industrial sector? The clearest answer is – a contained space with gaseous pressures much less than surrounding atmospheric pressure. Atmospheric pressure (ATM) is expressed in many units of measure. At room temperature a cubic foot of contained air at sea level – the random movement and molecular impact on the walls of the containment vessel equal a force of 14.7 psia for every square inch of the walls.
Operating the vacuum system at higher levels (then necessary) affects the needed volumetric flow to compensate for leaks. This required compensation of volume (ACFM) must be added to the nominal production flow demand. The ambient air leak into the system will expand to the highest vacuum level, which is known as the “Expansion Ratio.”
At the beginning of the 20th century, biological wastewater treatment — more specifically, the activated sludge process — was developed and became widely accepted as the treatment method for municipal wastewater, helping to protect our lakes and rivers from pollutants and support public health. In 1947, the Committee on Development of Uniform Standards for Sewage Works was created by the group known as the Great Lakes – Upper Mississippi River Board of State and Provincial Public Health and Environment Managers.
The Lafarge Cement Distribution terminal located in Winnipeg, Canada has significantly reduced the site electrical demand and energy charges by changing the way they transport their cement. Two new low-pressure rotary screw air compressors have replaced two large high-pressure air compressors that previously powered their dense phase transport system. The resulting power reduction has saved the company 46 percent in transport operating costs.
Every municipality and utility is facing the reality of rising energy costs. In 2010, the Town of Billerica, MA, which is located 22 miles northwest of Boston with a population of just under 40,000 residents, engaged Process Energy Services and Woodard & Curran to conduct an energy evaluation of the Town’s Wastewater Treatment Facility (WWTF) and pump station systems sponsored by National Grid. The objective of the evaluation was to provide an overview of each facility system to determine how electrical energy and natural gas were being used at the facility and to identify and develop potential costsaving projects.
This food industry factory, located in California, was spending \$386,533 annually on energy to operate their compressed air system. This system assessment detailed eleven (11) project areas where yearly energy savings totaling \$154,372 could be found with a investment of \$289,540. A local utility energy incentive, paying 9 cents/kWh, provided the factory with an incentive award of \$159,778. This reduced the investment to \$129,762 and provided a simple ROI of ten months on the project.
Bottling companies and breweries, in California, are benefiting from a three-step system assessment process aimed at reducing the electrical consumption of their compressed air systems. The three-step process reduces compressed air demand in bottling lines by focusing on open blowing and idle equipment, and then improves the specic power (reducing the energy consumption) of the air compressors.
The object of this article is to look at some very typical industrial water treatment processes and various compressed air and energy savings projects that have worked well for our clients over the years. The basic fundamentals with regard to compressed air usage are similar to municipal water treatment – a good starting point.
Assessing payback on engineered air nozzle and blower upgrades
There are a variety of means factories can use to remove or “blowoff” moisture from a package. Open tubes or drilled pipe are often viewed as simple low-cost methods. However, there are considerable drawbacks to these approaches, most notably – increased operating expense. While they may be convenient and inexpensive in the short term, these approaches often cost 5-7 times more to operate than preferred alternatives.
Recently, The Kroger Company’s Indianapolis bakery identified the use of compressed air in a blow-off and conveyor gap transfer as a major source of energy loss and cost waste. According to the U.S. Department of Energy, “inappropriate use” of compressed air like blow-off produces high pressure atmosphere bleed leading to significant energy loss and unnecessary operational costs. Carrying a 10-15% efficiency return (according to the Department of Energy), compressed air applications can often be achieved more effectively, efficiently and less expensively with alternative solutions using a high flow rate and moderate pressure.
One major problem that causes severe damage or system failure for any water treatment station is water hammer shock waves. “Water Hammer” or “Hydraulic Shock” is a pressure surge or shockwave resulting when a fluid (usually a liquid but sometimes also a gas) in motion is forced to stop or change direction suddenly (momentum change). The reversed momentum then continues to multiply the further it travels before being stopped.