November/December 2000

Issue Focus: Implementing Technology

This page presents all the articles in the November/December 2000 issue of Energy Matters, the BestPractices quarterly of the U.S. Department of Energy's Industrial Technologies Program.

In This Issue

• Darby Electric—A Model Allied Partner
• Assessment Helps Aluminum Casting Plant Key In to Potential Improvements
• Emissivity: The Unknown Factor
• New Feature: OIT Emerging Technologies and Research

Darby Electric—A Model Allied Partner

The BestPractices initiative works closely with Allied Partners that provide equipment and services to industry. Allied Partners are private companies, organizations, or government agencies that help assess plant efficiencies and demonstrate efficiency improvements. Not only do the plant owners benefit, but so do the Allied Partners—who become valuable to clients by helping them achieve plant efficiencies. One excellent example of an Allied Partner is Darby Electric, of Anderson, South Carolina.

The company signed on as an Allied Partner under the Motor Challenge program about 5 years ago. This year, the Motor Challenge program was incorporated under the umbrella of the BestPractices initiative as the Motor Systems program.

As an Allied Partner, Darby Electric has taken advantage of OIT's BestPractices training modules, software, publications, and technical assistance to help customers upgrade motor systems and save energy and money. In fact, according to Steve Darby, president of Darby Electric, "Gaining knowledge and being up-to-date on the latest technology are the biggest advantages of being an Allied Partner."

Those advantages helped Darby win the "Joint Cost Reduction" award from Milliken Textile Company in 1997. This award is Milliken's highest level of supplier recognition. It was achieved, in part, through Darby's work with OIT's Motor Systems program.

Steve Darby says that convincing customers to replace old motors with energy-efficient versions can be a challenge. "It's a hard sell, because companies often just look at the short-term bottom line, and they want to buy less expensive motors. But we've stuck to our guns," partly because of certain Energy Policy Act requirements, and partly "because I know we can serve customers better by providing them with better technology that gives them better efficiency and cost savings. Every motor should be evaluated prior to repair or replacement. If efficiency can't be improved by replacement, it should be rewound to original specifications with the utmost attention to detail, using the best techniques and insulating materials."

To make the selling job easier, Darby Electric has had to educate customers. It has sponsored and cosponsored motor system workshops, sent representatives to tradeshows, and in the process, has distributed many OIT fact sheets and software programs. Account managers for Darby Electric are trained in the use of Motor Master+ software and the Repair/Replace training module to help customers determine cost savings on purchasing replacement energy-efficient motors. In addition to Milliken, Darby Electric has served Monsanto, Morton International, NutraSweet, FujiFilm, and DuPont.

"Steve Darby had a vision to educate customers about energy efficiency. He successfully used OIT materials in his efforts, and it has paid off handsomely. I've really enjoyed working with him," says Chris Cockrill, project manager for the BestPractices Motor Systems program.

One advantage, according to Steve Darby, has been improved business. "Participating in this program has enabled Darby Electric to increase business volume in both new motor sales and in motor rebuilding," he says.

Darby Electric's experience demonstrates that through the Allied Partners program, vendors add value to their services and customers gain more efficient operations.

Assessment Helps Aluminum Casting Plant Key In to Potential Improvements

One year ago, OIT's BestPractices initiative launched its Plant-Wide Energy Efficiency Opportunity Assessments program. The idea was to encourage industrial facilities to investigate the possibilities throughout the plant and identify potential energy savings, process improvements, and opportunities for new technologies. With cost-shared funding and technical assistance from OIT, such assessments could facilitate the process for industrial plants.

Since the program began in September 1999, OIT has opened three rounds of solicitations and has made awards to 13 companies to conduct plant-wide assessments. These companies represent industries, such as aluminum, chemicals, glass, forest products, and petroleum refining—all within the scope of OIT's Industries of the Future initiative.

Among the recipients of the plant-wide assessment awards is aluminum casting manufacturer AMCAST of Wapakoneta, Ohio. One of the original seven companies to receive the cost-shared funding from OIT, AMCAST recently completed its assessment and moved quickly to implement improvements that could yield impressive savings of $3.6 million annually.

AMCAST's primary products are aluminum permanent mold castings for the automotive industry, but the company also serves the construction and other industrial sectors. The company employs 300 people at this plant and processes 15-20 million pounds of aluminum annually at the Wapakoneta site.

To make its products, AMCAST begins with aluminum ingots, which are melted in natural-gas-fired reverb furnaces. Melted aluminum is transferred to the hold furnaces adjacent to each low-pressure permanent mold machine via electrically heated ladles. After casting, flash and scrap parts are sent back to a Jet-melt furnace. Cast products are trimmed, inspected, heat treated, and aged in ovens. Primary waste streams include aluminum dross, recyclable aluminum flash, deburring material, metal shavings, and cooling wastes.

AMCAST is the first to use the low-pressure, permanent mold casting process to produce high-volume, aluminum suspension components for the auto industry. The company set out to identify ways to cost-effectively reduce waste, energy, and operating costs, and the plant-wide assessment award supported this effort. The company teamed with the University of Dayton Energy Efficiency Office and the Edison Materials Technology Center, of Dayton, Ohio; Midwest Building Diagnostics (formerly Miami Valley Diagnostics), of Xenia, Ohio; and CSGI of Rockville, Maryland. The team identified areas of improvement in AMCAST's operation, and generated ideas that could help other casting-related industries.

Path to Improved Efficiency

The assessment team's first step was to gain an understanding of the total cost of energy in the AMCAST facility. Utility costs as well as ongoing maintenance, capital investments, material, and labor associated with energy systems were also considered. By monitoring the operation's energy use, from the transformer and switches to production lines, the team identified opportunities to improve reliability, increase efficiency, and reduce total cost of energy.

Initially, the focus was on identifying and minimizing end-use loads. Next, the distribution system was examined for savings opportunities, then the primary driver. In most cases, the end-use and distribution system savings directly influence the recommendation for modifying the energy source.

Sources of Savings

Based on previous assessments of metal casting facilities and the information provided by AMCAST, the team noted potential savings and improvements throughout the plant in electrical, lighting, motor drive, compressed air, and process heating systems. By implementing these efficiency measures, the company expects to save $600,000 annually.

The assessment confirmed that the most significant improvements are in the manufacturing process. Approximately 90%, or about $3 million, of the total projected savings are process-related. As a result of material modifications to process equipment (riser tubes, glow bars, and others), AM CAST has realized reductions in maintenance, scrap, downtime, and has improved product quality.

The prospect of saving $3.6 million annually has led AMCAST to act immediately on the process improvements and other efficiency measures identified in the assessment. Of the 13 programs identified, four are underway and one is complete. For its $1 million investment on these improvements, AMCAST anticipates a simple payback of just 3 months. In addition, the company stands to reduce carbon dioxide (CO2) emissions by 11 million pounds per year.

Opportunity Captured

For AMCAST, this plant-wide assessment highlights the synergy of process performance and its impact on overall energy and cost savings. It also demonstrates the need to consider all other factors that affect performance and costs.

AMCAST has taken the opportunity to explore potential improvements, and is now implementing programs to capture substantial savings. In turn, other casting companies have the opportunity to share in the findings at AMCAST and perhaps capture similar results.

"The opportunity, guidance, and encouragement from OIT to help foster teamwork has helped overcome the 'not-invented-here' syndrome and has made the assessment a glowing success." explains James R. Van Wert, Jr., AMCAST's vice president of technology.

Emissivity: The Unknown Factor

Understanding Thermal Calculations to Save Money and Energy

By Gary J. Bases

Recently, a client, who is a plant manager for a major oil refinery, asked for help to understand how the amount of refractory and insulation lining system recommended for his flues and waste heat boiler by his supplier/contractor was calculated and what questions he should ask. I asked him what he knew about emissivity. He knew only that it was a measure of reflection or something to that effect.

I explained that emissivity is a key factor to understanding heat flow calculations and saving energy and money. The other important factors are wind velocity, ambient air temperature, surface temperature, thermal conductivity, or "K" value, and operating temperature. Proper calculation of the insulation and refractory (thicknesses and material types) will save money at the initial installation because he will only be paying for what he needs. As a long-term investment, this client will save energy and money by minimizing the amount of heat loss that radiates from the outer casings. By understanding emissivity, he will use less fuel to reach and maintain the waste heat boiler's operating conditions.

The following discussion, while not the whole story on emissivity, might simply shed some light on its value in determining the right insulation and refractory requirements for maximum savings.

Emissivity Defined

Emissivity is a measure of the ability of a material to radiate energy. It is expressed as a ratio (decimal) of the radiating ability of a given material to that of a black body.¹ A black body emits radiation at the maximum possible rate at any given temperature, and has an emissivity of 1.0. The values of emittance for various metals are published and so are undisputed. I suggest that the emissivity value used for the calculation be based on the current conditions of the materials being installed (i.e. reusing existing outer casing or lagging or installing new lagging or casing). More than just knowing the definition of emissivity, however, it is important to understand where and how this value can be used or misused in the calculation of insulation thickness.

Calculating Insulation Thickness

A good way to understand the role of emissivity in calculating insulation and refractory material thickness is to use good old- fashioned hand calculations. The formula below can be used for flat surfaces:

To find the elusive emissivity factor, the formula must be broken down further:

This gives the two basic components of Btu or heat loss portion, which are convection (in this case natural convection) and radiant values. In the radiant component of the Btu value we find emissivity.

This thermal calculation seems quite complicated, and with all the calculation software on the market today,² we should be glad that we no longer have to hand calculate. However, these computer programs require the same input to calculate heat flow. They all ask for velocity, ambient air temperature, surface temperature, and operating temperature. Most have built-in K values for the types of insulation and refractory to be used, or these values can be easily entered.

Variables of Calibration

So, what affects the insulation thickness calibration? The most obvious factor is the K value. A higher K value causes the calculation to have a greater insulation thickness. By using the mean value of the insulating material, we get a lower K value, and therefore, a lower insulation thickness. To find the K value:

• Find the mean temperature:
       (operating temp. + surface temp.)
                              2
• Identify value of K on published charts

The K value of insulation has not changed dramatically over the years. As R.L. Schneider, a pioneer in heat transfer calculations, wrote "...since it is harder to keep improving insulation by decreasing the K value, let's increase the thickness when necessary."³ If this is still true, then the only other variable that can affect the outcome of the insulation thickness calculation is emissivity.

Factoring Economic and Energy Savings

By understanding the emissivity factor, you can compare labor and material costs at various insulation thicknesses. That is the easy part of determining economic savings. The more difficult part is to relate that to energy savings, but this is the key. Think of insulation and refractory as an investment in energy savings down the road. "The greater the cost of insulation, the smaller the cost of heat loss," explained J.F Malloy,⁴ in Thermal Insulation. That is, savings on heat loss occur when insulation thickness is increased; however initially, there is a greater installation cost for that increase of insulation thickness.

A Little Knowledge Pays Off

With a better understanding of emissivity, my client felt that he could evaluate the insulation and refractory design with confidence. The next time he talked with his supplier/contractor, he could ask informed questions, such as:

• Was the K value based on mean temperature?
• What external wind velocity was used?
• What emittance was used to calculate the insulation and refractory thickness?

Knowledge is everything! Knowing more about the calculations helped my client obtain the proper material type at the right thickness. He found that the design was insufficient due to incorrect emissivity and wind velocity factors. As a result, he kept the initial installation costs down by paying only for what he needed (short-term cost savings). In addition, heat loss in the plant has been minimized, which keeps fuel costs down (long-term energy savings). The end result is a thermally efficient and cost-effective installation of a refractory and insulation lining system for his flues and waste heat boiler. Thus proving what Mr. Malloy also wrote: "Thermal insulation installed to save energy also saves money at the rate that is essential for efficient plant operation."

Gary Bases is president of BRIL inc., an independent consulting firm specializing in brick, refractory, insulation, and lagging. Contact him at (330) 665-2931 or e-mail inquiry@bril-inc.com.

1 ASTM C-680-89, page 13, Appendix A.

2 Download DOE/NAIMA's 3E Plus insulation thickness software.

3 Fundamental Heat Transfer, R. L. Schneider, 1961.

4 Thermal Insulation, J.F. Malloy, 1969.

New Feature: OIT Emerging Technologies and Research

In this new column, Energy Matters highlights emerging technologies to illustrate their important role in helping industry achieve energy savings and emission reductions. OIT considers technologies to be "emerging" when:

• They are ready for use in industrial settings.
• They have been demonstrated under real-use conditions to achieve a minimum of 25% baseline or potential improvement in energy efficiency and emissions generation.

These technologies are developed with support from OIT's Industries of the Future partnerships. After a successful demonstration, the technologies could be brought into industrial use through OIT's BestPractices initiative.

One such technology, developed by Argonne National Laboratory (ANL) recycles usable plastics products from automotive scrap when vehicles are shredded to recover metal for reuse. About 3-5 million tons of residue are produced annually in the United States and have been destined for landfills without an economical or effective means for material recovery. This patented ANL process, which separates the residue into streams of polyurethane foam, mixed plastics, and iron oxides, has the potential to recover 250,000 tons of polyurethane foam and 750,000 tons of heat-formed plastics when applied to the annual production of shredder residue in the United States. It would thus minimize landfill disposal operations by recovering 20%-30% of the shredder residue.

An ANL pilot plant built to demonstrate its 6-step process for recovering polyurethane foam from the shredder residue produced more than 3 tons of foam that met industry specifications for new material carpet padding and for reuse in automobile applications. At a cost of less than $.30 per pound, the recycled foam has a substantial cost advantage over the $1 per pound cost for virgin foam. Because of these significant results, the polyurethane foam recovery process has received a 2000 R&D 100 Award from R&D magazine.

In addition, ANL has developed a froth-flotation process, which, when combined with mechanical/physical separation, can be used to recover high-value plastics, such as acrylonitrile-butadiene-styrene (ABS) and high-impact polystyrene (HIPS) from the shredder residue stream of mixed plastics. A pilot-plant demonstration at Appliance Recycling Centers of America, in Minneapolis, Minnesota, succeeded in producing high-purity (>90% pure) ABS and HIPS. The recovered polymers can be mixed with new materials to make automobile, appliance, and electronic parts, piping, and furniture. When applied to recovery operations of automobile shredder residue and obsolete appliances more than 300 million pounds of high-value plastics could be reclaimed for reuse. That would save 87 trillion Btu in energy costs and avoid disposal costs of $10-$40 per ton of waste.

The process for recovering polyurethane foam has been licensed to Salyp Recycling Center, of Belgium, where it will be applied to achieve a 40% reduction of the waste from end-of-life vehicles by 2005, as required under European Union directives. Negotiations are ongoing for licensing the froth flotation process to private companies.

Learn more about these processes online at http://www.eere.energy.gov/industry/chemicals/.

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