Industrial Utility Efficiency    

System Assessment

Annual plant electric costs for compressed air production, as operating today, are $147,469 per year. If the electric costs of $750 associated with operating ancillary equipment such as dryers are included, the total electric costs for operating the air system are $148,219 per year. These estimates are based upon a blended electric rate of $0.087 /kWh. The air system operates 8,760 hours per year. The load profile or air demand of this system is relatively stable during all shifts. Overall system flow ranges from 800- 1,000 acfm during production. The system pressure runs from 95 to 80 psig in the headers during production.  

Compressor Controls

UniFirst is one of North America’s largest workwear and textile service companies. They outfit nearly two million workers in clean uniforms and protective clothing each workday. Founded in an eight-stall garage in 1936, the Company has grown to 240 customer servicing locations throughout the U.S. and Canada servicing 300,000 business customer locations. The subject of this article is an energy-saving Air Demand Analysis (ADA), conducted by Kaeser Compressors, at UniFirst’s centralized 320,000 square foot hub Distribution Center located in Owensboro, Kentucky.

Piping Storage

The company specializes in fabrication of precision assembled customized parts for OEM’s and system integrators. Since 1997 the company has steadily grown in size and capacity as the demand for its high quality fabrications has increased.  Through the years, many new CNC machines, laser cutters and powder coat painting operations have been added, but with all the expansion the facility has amazingly kept the plant compressed air consumption low. This has been achieved by following excellent “best practice” compressed air efficiency principles and by keeping watch on system waste.

End Uses

A chemical plant spends an estimated $587,000 annually on electrical energy to operate their compressed air system. In addition, the plant has an expenditure on rental air compressors of equal or greater size - but this will not be covered in this article. The plant was built in the 1940s and modernized in the 1970s. The plant generates its own power and serves many processes. The average cost per kWh is $0.0359.

Pressure

A Canadian chemical plant installed a large heated blower-purge style compressed air dryer, years ago, to condition the instrument air system against freezing temperatures.  The dryer selected was oversized for the connected air compressors and had unused on-board energy savings features.  A compressed air assessment revealed the site air compressors and compressed air dryers were running inefficiently and causing in-plant pressure problems.  Repairs to a compressed air dryer and the replacement of aging air compressors and dryers has reduced compressed air energy costs by 31 percent.

Air Treatment/N2

This plant has three production lines producing snack food. Depending on the time of year and production demand the plant can operate anywhere from no production lines to all three production lines. A thorough supply and demand-side system assessment was done at this plant. This article will focus on some recommended demand-side reduction projects including nitrogen generation, air vibrators, leaks and vacuum venturis.

Leaks

Petro Chemical Energy, Inc. (PCE) specializes in energy loss surveys for the refining and chemical industries. We’ve been providing Compressed Air Leak Surveys, Nitrogen Leak Surveys, Steam Leak Surveys and Steam Trap Surveys – for over twentyfive (25) years. We operate totally independent of all equipment manufacturers to ensure our clients receive a complete and unbiased report of the leaks in their facility. PCE has conducted compressed air leak surveys for hundreds of customers at thousands of sites. Undetected, compressed air and gas leaks rob efficiency in manufacturing and processing industries. As a result, businesses lose millions of dollars annually in energy costs and lost production time.

Pneumatics

Energy, in all forms, has always been a key Lantech focus. It was, in fact, a key element of the core packaging problem the company’s founders set out to address. They saw an opportunity to capitalize on an inexpensive and under-used resource – stretch film – to displace a high materials cost and energy intensive way of unitizing pallet loads of products – shrink bagging.

Vacuum Blowers

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.
Compressed air reliability has been the obsession of both factory personnel and service providers for a number of years now. Constant availability of high quality air can be absolutely critical to maintaining efficient plant production. Most modern factories operate reliable compressed air systems – and more recently have also begun to focus on the efficiency of those systems. The objective of this article is to use a few real-life case studies of already reliable compressed air installations to illustrate the potentially huge economic benefits of also improving system efficiency.
Over many years of reviewing industrial compressed air production machinery, of many types and styles, there is one common thread or complaint; “push-to-connect pneumatic tubing connections/fittings are a continual source of compressed air leaks and production interruptions.”  Probably seventy-five to eighty percent of push-to-connect type tubing fittings use flexible tubing selected for lower material cost and assembly rather than an alternate appropriate hard metallic tubing.  
Chemical plants, due to their size and complexity, pose many challenges to the efficient and reliable operation of a compressed air system. There are so many places for hidden opportunities to be found in these large industrial complexes. We are normally dealing with several large centrifugal and rotary screw air compressors scattered across the complex. We encounter sites with well over thirty (30) desiccant air dryers of different types. Compressed air leaks can be found almost at will across the vast lengths of compressed air piping. Add to this the fact they are outdoor installations exposing all compressed air system components to the extremes of summer and winter. As you can imagine, it is a big task to simply understand the system.
This paper mill currently spends $1,747,000 annually on energy to operate the compressed air system at their plant located in the southwestern region of the U.S. The set of projects recommended, in this system assessment, could reduce these energy costs by $369,000 or twenty-one percent (21%). Estimated costs for completing the projects total $767,900, representing a simple payback of 25 months. More importantly, these projects will improve productivity, quality and maintenance costs - many associated with poor compressed air quality.
Based on the air system operating 8,760 hours per year, the group of projects recommended below could reduce these energy costs by an estimated $170,718 or 56% of current use.  In addition, these projects will allow the plant to have a back-up compressor and help eliminate the rental expenditure for compressor maintenance or downtime.
The development of extruded aluminum piping is a recent innovation in the compressed air industry. The internal bore of this piping is smooth and corrosion resistant which makes the pressure differential characteristics of a straight run of this pipe superior to that of steel pipe. Because it is much lighter than steel pipe the installation is much easier. And the manufacturers of this style of piping have come up with various twist lock connectors to make the installation even simpler.
This food & beverage plant is a large (500,000 sq ft) meat processing plant with twenty packaging lines and nine palletizers. The compressed air system is supplied from three separate rooms with seven individual lubricant-cooled, single and two-stage rotary screw compressors. The plant has four blower purge desiccant dryers designed to deliver a - 40°F pressure dewpoint.
Proper compressed air supply to the IS Machine, in glass container manufacturing, is critical. Each process requires carefully controlled pressure, air quality (dryers), and flow as necessary for optimum production with minimum scrap. Most IS machine operations, which Air Power has reviewed over the years, offer significant energy savings opportunities with low capital costs. The final results also enhance quality and productivity.
This glass bottle production plant had a complete compressed air audit in 2001 and 2002 at which time many successful projects reduced and stabilized the demand at 3,148 scfm at 95 psig for the high pressure system air and 9,300-9,500 scfm at 58 psig for the low pressure system. Successful application of an oversized 7,200-scfm rated cycling refrigerated dryer completely dried up the high-pressure air, allowing the removal of several non-performing desiccant dryers and savings in direct kW and purge air.
The Technical Director of a large facility in the Mid-West (producing valves and meters) hired us to assist with a Site Energy & Utility Systems assessment. The compressed air system quickly became one of the main issues identified. The plant was built in the 1960’s and had expanded over the years. Recent reduction-in-force programs (to reduce costs) had impacted the maintenance department and the plant air system was high among the systems that were the most affected. Over the next several months, as management became attuned to all of the air system issues affecting utility costs and process quality concerns, resources were provided and significant improvements occurred.