Energy Matters: Information and Energy Solutions for Industry U.S. Department of Energy Energy Efficiency and Renewable Energy Energy Matters Bringing you a prosperous future where energy is clean, abundant, and affordable Industrial Technologies Program

Fall 2004

Issue Focus: Tips to Save Energy

This page presents all the articles in the Fall 2004 issue of Energy Matters, the BestPractices quarterly of the U.S. Department of Energy's Industrial Technologies Program.

In This Issue

20 Ways to Save Energy Now

Energy costs can have a significant effect on your plant's bottom line. Volatile natural gas prices in the recent past have made it even more important that energy be used efficiently and effectively. Below, you'll find 20 steps you can take in the next year at little or no cost, and mostly using in-house expertise. You'll also find Web links listed on the next page to help you research topics related to natural gas prices, consumption, and forecasts, all available from the DOE's Energy Information Administration.

All Combustion Systems

  1. Operate furnaces and boilers at or close to design capacity.
  2. Reduce excess air used for combustion.
  3. Clean heat transfer surfaces.
  4. Reduce radiation losses from openings.
  5. Use proper furnace or boiler insulation to reduce wall heat losses.
  6. Adequately insulate air or water-cooled surfaces exposed to the furnace environment and steam lines leaving the boiler.
  7. Install air preheat or other heat recovery equipment.

Steam Generation Systems

  1. Improve water treatment to minimize boiler blowdown.
  2. Optimize deaerator vent rate.
  3. Repair steam leaks.
  4. Minimize vented steam.
  5. Implement effective steam trap maintenance program.
  6. Use high-pressure condensate to make low-pressure steam.
  7. Utilize backpressure turbine instead of pressure-reducing or release valves.
  8. Optimize condensate recovery.

Process Heating Systems

  1. Minimize air leakage into the furnace by sealing openings.
  2. Maintain proper, slightly positive furnace pressure.
  3. Reduce weight of, or eliminate, material handling fixtures.
  4. Modify the furnace system or use a separate heating system to recover furnace exhaust gas heat.
  5. Recover part of the furnace exhaust heat for use in lower-temperature processes.

To learn more, visit the Energy Savers Web site.

Where to Look for Natural Gas Information

The U.S. DOE's Energy Information Administration is a one-stop source for widely used energy information. EIA has four types of information products: Energy data, analyses, forecasts, and descriptive information telling you more about each of its products. Many products, such as the Petroleum Supply Monthly, deal with specific industries. Of particular interest may be products containing data on fuel types presented in an integrated manner. Some key publications that present this kind of integrated information are the Monthly Energy Review, the Annual Energy Review, the Short-Term Energy Outlook, and the Annual Energy Outlook.

EIA forecasts cover all energy types, and include forecasts of supply, consumption, prices, and other important factors. The EIA publishes short-term forecasts that consider conditions 6 to 8 quarters in the future, and a midterm forecast that goes out 20 years. Some of the EIA forecasting models are available on its Web site. Here are some useful links that you can begin using right away:

You can also receive e-mail notification about updated data and newly released reports. Or, you can call the EIA for help at 202-586-8800.

Compressed Air System Retrofit and Improvement Yields Energy Savings at a Foundry

In 2002, engineers at Techni-Cast's foundry in Southgate, California, implemented a retrofit project on the foundry's compressed air system based on a review of the system by DOE Allied Partner, Accurate Air Engineering. The project involved retrofitting the compressed air system with more appropriately sized compressors, upgrading the compressor controls, and replacing the existing condensate drains with more efficient, zero-loss models. The foundry's engineers also investigated and specified the proper pressure levels for all end-use applications, repaired leaks, and cleaned the dryer's coalescing filter.

Altogether, these measures improved the system's efficiency so much that the foundry was able to reduce its online compressor capacity by 50% without any decline in production. The annual energy and maintenance savings from the project are 242,000 kilowatt-hours (kWh) and $24,200. By implementing the project, the plant qualified for a $10,000 incentive payment from the California Public Utilities Commission. This incentive reduced the project's total cost from $38,000 to $28,000, yielding a 14-month simple payback.

Optimizing industrial compressed air systems can be best accomplished using a systems approach. Equipment replacement and reconfiguration of components can help, but both types of measures need to be integrated into a system-level strategy to maximize energy efficiency. In the case of Techni-Cast, a system-level evaluation and strategy allowed the foundry to determine the most optimal compressed air system size and configuration that would efficiently satisfy the plant's production requirements. By configuring the system to have the lowest compressor capacity that meets production requirements, the Southgate foundry increased its compressed air system's efficiency and realized significant energy savings. This approach to optimizing a compressed air system's efficiency can easily be replicated in all types of industrial manufacturing sites.

Questions Answered by the DOE's EERE Information Center

DOE's EERE Information Center has helped thousands of industries identify cost-effective ways to improve energy efficiency, such as the solutions provided below. Through the Information Center, industries and industrial service providers can access Industrial Technologies Program resources to help make their industries more energy-efficient, productive, and competitive.

The Information Center can help you find resources such as publications and software tools, as well as information about working with ITP and cost-sharing opportunities. If you are working on large industrial energy efficiency projects, the Information Center's engineering staff can provide you with technical assistance on motor, steam, compressed air, pumping systems, and more. Contact the EERE Information Center at 877-EERE-INF (877-337-3463), or go to The Industrial Technologies Program Web site for more information.

Q: We use 100 pounds per square inch gauge (psig) steam with serpentine coils to heat several open tanks (some contain phosphoric acid, some nitric acid, and some caustic). At present the hot condensate is dumped to the sewer because of the potential for acid to contaminate the boilers from leaks into failed coils during shutdowns. What technology could you suggest that would allow us to reliably return condensate to the boilers? Total condensate return would be about 3,000 pounds per hour.

A: Several companies make equipment trains that are specifically designed to maximize the return of potentially contaminated condensate. A "contaminated condensate detection system" or "clean condensate" module monitors the conductivity and pH of condensate being returned to the boiler and diverts contaminated condensate to the drain. The system involves the use of a controller, which compares readings against preset values. Condensate is returned to the boiler when it is within specifications. When controller setpoint values are exceeded, a three-way valve on the condensate return line is actuated to dump condensate to the sewer or to a neutralization tank.

Contaminated condensate return systems have been installed in food processing and chemical plants. Note that condensate can be monitored for hydrocarbons, pH, conductivity, oil, and/or turbidity. A certain amount of pre-engineering is required to adapt clean condensate equipment modules to a given site. Automatic dump systems must be designed and installed properly to effectively detect and reject contaminated condensate. Potential design issues include sampling line length, sample cooling requirements, and adjustments to sampling instruments to accommodate pressurized condensate return lines. The installation of condensate filters or polishers might also be considered.

Diversion valves must be periodically exercised and condensate monitors calibrated to ensure that they are functioning properly. Maximizing the return of hot condensate reduces fuel costs and improves boiler efficiency. Assuming year-round operation, a boiler efficiency of 80%, a condensate temperature of 180ºF (enthalpy of 148 British thermal units per pound-Btu/lb), and a makeup water temperature of 55ºF (23 Btu/lb), the return of 3,000 lbs/hour of condensate provides annual energy savings of:

Q: Is there a technology for recovering energy from compressed gases? We operate six centrifugal compressors to provide 125-psig air for our processes.

The reactors consume oxygen and produce a waste gas stream at a pressure of 45 psig. The composition of the waste gas is mainly nitrogen. The waste gas currently goes through a letdown valve, then is routed through a thermal oxidizer to eliminate hydrocarbons, and then released to atmosphere.

A: Several companies can provide turboexpanders that are designed to recover power from pressure letdown stations. In a turboexpander, the compressed gas undergoes isentropic expansion in a single-stage radial turbine. The extracted shaft power is available to drive an electrical generator. Turboexpanders are often used in the hydrocarbon gas processing and petrochemical industries. Turboexpanders are readily available in the 500 kW to 10 MW size range and can be designed to work with hydrocarbons, carbon monoxide, nitrogen, hydrogen or other gases.

Turboexpander manufacturers can provide curves for various gas mixtures that provide the recoverable power (in kW) as a function of expander pressure ratio and gas flow rate . Turboexpander manufacturers can also estimate the electrical generating capacity or shaft horsepower available and provide a preliminary equipment cost estimate when provided with your inlet gas temperature, flow, composition, and required discharge pressure.

Turboexpanders can be installed at pressure letdown sites, pipeline-to-pipeline pressure reduction stations, on steam boiler and other industrial natural gas supply systems, and in parallel with existing control valves or regulators.

Q: A new process in our plant requires a flow of 100,000 lbs/hour of 15-psig steam. About 45,000 lbs/hour of 15-psig steam is available at various locations throughout the facility. Unfortunately, a pressure drop will occur when the low pressure steam is routed to the point of use. The pressure must be boosted back to 15-psig (or higher) for the steam to be useful for the process. How can we do that?

A: Low pressure steam can be boosted to a higher pressure and temperature with single or multi-stage thermocompressors, mechanical vapor recompressors, or with industrial heat pumps. Thermocompressors are recommended when high pressure motive steam is available and compression ratios are low.

A thermocompressor boosts steam pressure by using a Venturi nozzle in a steam jet ejector. High pressure motive steam expands in a converging-diverging nozzle to convert pressure energy to kinetic energy. Low pressure vent or suction steam is entrained into this velocity jet where mixing occurs. A diffuser portion of the thermocompressor reconverts the kinetic energy of the mixture back into pressure. The intermediate discharge pressure is somewhere between the motive steam pressure and the low pressure suction steam pressure. The actual discharge pressure is determined by the ratio of the pounds per hour of motive steam supplied to the pounds per hour of low pressure suction steam entrained.

For higher pressure boosts, mechanical vapor recompressors are recommended. A vapor recompressor is similar to an air compressor-except the fluid being compressed is steam, not air. Generally, an electric motor provides the energy necessary to raise the pressure, temperature, and enthalpy of the suction steam.

Mechanical vapor recompressors are engineered pieces of equipment. They are not available "off-the-shelf". Recompressors are generally built up from existing components that are "fit" onto existing designs. Companies that make large rotating equipment such as steam turbines, backpressure turbines, and turboexpanders can design and supply mechanical vapor recompressors. For additional information, download the Steam Tip Sheet "Use Vapor Recompression to Recover Low-Pressure Waste Steam" (PDF 200 KB) (Download Adobe Reader).

Steam System Assessment Tool Version 2.0.0 Now Available

The Industrial Technologies Program announces the newest version of the popular Steam System Assessment Tool (SSAT). Now SSAT Version 2.0.0 is a more powerful tool that allows steam analysts to develop approximate models of real steam systems. Using these models, the SSAT can be applied to quantify the magnitude-in terms of energy, cost, and emissions savings of key potential steam improvement opportunities. SSAT contains the main features of typical steam systems. If you are an engineer who operates and improves steam systems, SSAT Version 2.0.0 can help you better manage these systems.

SSAT Version 2.0.0 includes several major software improvements and corrections to known problems in the original Version 1.0.0. New features and capabilities include:

Download SSAT Version 2.0.0 free of charge from ITP's BestPractices Web site. If you have SSAT Version 1.0.0 installed, we recommend you perform a complete update to the new version.

To install SSAT Version 2.0.0, simply download the file "SSATv2_Setup.exe" to your computer, double click on the file, and follow the on-screen instructions. Installing SSAT Version 2.0.0 will not erase any software templates you have previously created. Or, you can continue to use Version 1.0.0, but load the new software template files and save them in your existing SSAT "Templates" folder. The SSAT Version 2.0.0 Users Guide is also available for download.

Learn more about this tool and other ITP BestPractices resources, training, and system improvement opportunities on the BestPractices Web site. You can also contact the Energy Efficiency and Renewable Energy Information Center at eereic@ee.doe.gov or 877-337-3463 (877-EERE-INF) for assistance and to find out how ITP and BestPractices can help your company improve energy efficiency and the bottom line today!

Alumni Profiles Show How Employers Benefit from IAC Student Experience

The Industrial Assessment Centers (IAC) provides small- and medium-sized manufacturers with no-cost assessments of their plant's energy, waste, and productivity efficiency, followed by recommendations for specific cost savings.

The assessments are conducted by engineering faculty and students of IACs hosted by 26 universities across the United States. The Industrial Technologies Program sponsors the Centers as part of its efforts to transfer energy-efficient and environmentally sound practices and technologies to U.S. industry.

The Centers benefit many parties, but perhaps the greatest long-term benefit is the effect on engineering students who use the skills learned from their IAC experience in their careers. IAC alumni get choice jobs and employers gain highly experienced and competent employees.

Profiles on three IAC alumni are now available at the Center Student Forum Website, www.iacforum.org. More alumni profiles will be written in the coming months. In these first profiles, you'll meet Judy Dorsey, Julie Sieving and Eric Ruffel, from Colorado State University.

Eric credits the Center with helping him receive four competing job offers on graduation and land the exact job he wanted. Working on more than 40 industrial site assessments during his three years with the Center gave him practical experience few other first-year employees could match.

Judy has parlayed her IAC training into 12 years experience in pollution prevention and sustainable design, as well as 7 years of project management expertise. Judy owns and operates her own engineering consulting business. And Julie, who works with Judy, participated in 30 assessments, giving her the kind of hands-on experience employers want.

Since its inception in 1976, more than 2,000 students have participated in the IAC program. Currently, about 250 students are trained each year. The training each student receives augments his or her traditional engineering education. Prior to their first industrial assessment, students are trained in assessment methodologies, instrument use, safety, and common industrial energy uses, such as air compressor systems, motors, boilers and steam systems, pumping systems, and lighting. Potential energy-conserving and cost-saving recommendations are highlighted and methods to estimate the potential conservation and cost savings are presented.

Energy Matters, the BestPractices' quarterly of DOE's Industrial Technologies Program, is your online source for in-depth information that can help you manage energy use and enhance efficiency in your plant. You can read technical articles from industry experts, find practical tips on how to improve your operations today, learn how others are saving energy and money, and access the latest BestPractices tools, resources, and opportunities. Energy Matters is for industry professionals like you. Subscribe today—it's free!

Visit www.eere.energy.gov/industry/bestpractices/energymatters/ for issue archives, to browse articles by topic, and to subscribe.

Fall 2004
DOE/GO-102004-2025

NOTICE: This online publication was prepared as an account of work sponsored by an agency of the United States government. Neither the United States government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States government or any agency thereof.