Industrial Utility Efficiency    

System Assessment

“Retro-Commissioning” (ReCX) of compressed air systems has become a trendy activity with many utility demand-side-management programs emerging in the last 5-10 years.  This is intended to be the process of “tuning up” a compressed air system, getting low cost savings from mostly adjustments and repairs.  The term was borrowed from the building/HVAC industry, where it means to get a system operating as it was originally “commissioned”. 

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

Technology is available which enables a compressed air flow meter to measure not only the magnitude of the flow, but also the direction. Why is this important? In this article we will describe two case studies where bi-directional compressed air flow measurement plays a key role to come to the right conclusions. In the first case study, we will describe an electronics manufacturing plant, which has a large interconnected ring network with two air compressor rooms located in different buildings. The two air compressor rooms are about five hundred feet apart. In the second case study, the effect of compressed air flow measurement upstream of a local receiver tank is described.

End Uses

At a Midwest window manufacturing plant, the cooling process for the plastic frame pieces, after leaving the extruder, was critical to process productivity and quality. Too much cooling air (or not enough cooling air) would generate scrap and rejected product. The plants’ 17 extruders and 55 separate blow-offs in these lines had similar cooling stations at the cooling boxes. They consisted of about three hoses at each exit frame angled down to the extruded piece moving past it. The compressed air flow was controlled by a manual control valve set by an operator. The operator used his experience to control the flow delivered and thereby control the product quality.

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 northeastern U.S. automotive manufacturing facility spends $269,046 annually on energy to operate their compressed air system. This figure will increase as electric rates are raised from their current average of .019 cents per kWh. The set of projects, in this system assessment, reduce these energy costs by $110,166 or forty percent. Reliability of compressed air quality, however, is the main concern in this plant and the primary focus of this system assessment.

Leaks

Compressed air optimization measures adopted by PTMSB have reduced the consumption of compressed air by 31 percent resulting in savings of about 3,761,000 kWh per year in energy consumption. The monetary savings are MYR 1,090,627 per year ($255,000 USD). The CO2 reduction is estimated at 2,735 ton per year.

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.
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.
Insufficient focus at the design phase will kill a project. In one aerospace project, insufficient detail was paid to the physical size of the air compressor. The compressor didn’t fit in the allocated space—requiring the extension of the building, and costing tens of thousands of unbudgeted dollars. That had a significant, negative impact on the project return. 
In many parts of the country—and especially the Pacific Northwest—interest has surged in completing energy-saving compressed air system upgrades. The financial assistance from incentive programs, combined with the falling costs of efficiency-increasing technology, has made these projects very attractive to all those involved. The benefits for society, power companies and customers are immense.
To produce healthy, high-quality cooking oil, this food processing company crushes and processes oil seeds shipped in from local farms. The oil produced is thought to be the healthiest cooking oil available, because it is low in saturated fat, high in monounsaturated fatty acid (MUFA), and polyunsaturated fat (PUFA), like omega-3 fatty acids. To increase the energy efficiency of its oil seed crushing and processing facility, the company optimized its compressed air system by combining three separate systems into one. Some end-use optimization was done to correct low pressure, particularly caused by some critical high-flow, short-duration events.
Technological trends in plastics manufacturing are driving the costs of production down. In industrial PET blow molding specifically, two innovative techniques have had major impacts over the last 15 years: “light weighting” the plastic bottles, and recirculating high-pressure compressed air. Both have helped to improve the energy efficiency of PET blow molding by reducing compressed air requirements dramatically.
PET Power Containers, a Canadian manufacturer of PET plastic containers, had plans for expanding its operations with the addition of more blow-molding equipment. Before the expansion could happen, however, the company needed to assess its compressed air system. Based in Vaughan, Ontario, PET Power provides a dizzying array of differently shaped and sized plastic bottles. Their operations run 24/7, and compressed air plays a key role in their primary manufacturing applications, including PET blow molding, PET preforming, and labeling bottles.
A Canadian fiberglass plant has completed a lengthy compressed air improvement journey and achieved significant efficiency gains by applying “the systems approach.” Along the way, the company ran across many frustrating problems, the solutions to which were only determined after the entire system was monitored holistically using data loggers. The overall compressed air audit led to a reduction in energy usage of 48 percent, yielding savings worth $17,500 per year. The project also qualified for a large utility incentive of $32,000 with a calculated payback of 4.4 years.
Sometime in mid-2015, I received a call from a project engineer at a major plastics firm. He had a troubling issue with one of his PET bottle plants. The bottom line was this: They could not run all five high production blow-molding machines at one time—even though they were able to do so 18 months previously.
Air-operated double diaphragm (AODD) pumps are common to many manufacturing facilities. As estimated by veteran compressed air auditor Hank van Ormer of Air Power USA, approximately 85 to 90 percent of plants in the United States have AODD pumps. They are used for all kinds of liquid transfer applications, like those found in chemical manufacturing, wastewater removal, and pumping viscous food products.
There is always something new to learn about compressed air systems – particularly in regards to compressed air dryer installations. As I discussed in Part 1 of this series, you can make compressed air dryer installations more reliable by understanding the consequences of any modifications you make to the system.  As a continuation of those ideas, Part II explores more ways to make a dryer installation more reliable. Discussions include: the difference between operating a desiccant dryer in a fixed cycle opposed to demand mode, what happens when you operate a heated desiccant dryer with the cooling air turned off, and how to deal with the unintended consequences of dedicating a desiccant dryer to a compressor.