Issue Focus: The Benefits of Industrial Plant Assessments
Energy Matters was a quarterly newsletter for DOE's Advanced Manufacturing Program (AMO). It provided in-depth technical articles to help industry professionals save energy, reduce costs, and increase productivity. These archived issues may contain broken links or information that is no longer accessible. Some of the following documents are available as Adobe Acrobat PDFs.
This issue focuses on the benefits of assessing your industrial plant's energy use to uncover opportunities to save money and increase productivity.
In This Issue
- DOE Industrial Energy Savings Assessments Point Out Millions in Savings
- DOE and Dow Join Forces to Save Energy Now
- New Alliance Targets Industrial Energy Efficiency in Northwest
- Chemical Plant Assessment Uncovers More Than $3 Million in Potential Savings
- Spotlight: Pumping System Improvements Save Energy at Texas Power Plant
DOE Industrial Energy Savings Assessments Point Out Millions in Savings
DOE Qualified Specialists Find Savings in U.S. Industrial Plants
Qualified Specialists use sophisticated analysis and assessment tools and techniques to help industrial plants identify ways to improve the efficiency of their industrial systems. These experienced professionals must complete a qualification training workshop and exam in the use of specific DOE-developed software tools designed to help industry curb energy costs, reduce maintenance and downtime, and improve productivity. The training they receive recognizes and enhances their expertise in the use of such software tools as AIRMaster+, the Pumping System Assessment Tool (PSAT), the Process Heating Assessment and Survey Tool (PHAST), and the suite of Steam System Tools.
Large U.S. manufacturing firms stand to save millions of dollars in total energy and maintenance costs by carrying out the recommendations made in Energy Savings Assessments of their plants in 2006. That number could soar into the billions as more plants assess their energy use and make the kind of energy- and cost-saving improvements recommended by U.S. Department of Energy (DOE) Energy Saving Teams.
The volatility of natural gas supplies and prices has sparked serious concerns among U.S. manufacturers about their ability to maintain competitiveness, productivity, and profitability. To help uncover ways to stabilize their energy costs, 200 of the nation's largest, most energy-intensive manufacturing facilities are on tap to receive DOE Energy Savings Assessments (ESAs) as part of Save Energy Now, the industrial component of a national campaign, "Easy Ways to Save Energy," launched by Energy Secretary Samuel W. Bodman in October 2005.
The 200 ESAs are just one part of a strategy to help industry remain competitive through improved energy management. Small and medium-sized plants may also be eligible to receive no-cost assessments through DOE's university-based Industrial Assessment Centers (IACs). DOE also offers training, software, and other tools to help all plants looking for ways to improve their energy use and their bottom line.
The savings resulting from implementing the recommendations made in plant energy assessments can be substantial. For example, a large food processing firm, J.R. Simplot Company, reported saving nearly $300,000 per year in energy costs by improving just one plant's steam system after an assessment (PDF 638 KB). Download Adobe Reader. When companies apply similar cost-saving measures to industrial systems in other plants, the savings can multiply quickly.
ESAs Target Large Plants
The 200 industrial plants selected for ESAs in 2006 consume about 15% of all the natural gas used in the U.S. manufacturing sector. This is equivalent to the amount of energy consumed by some 14 million typical U.S. homes that use natural gas for heating and other needs.
The intent of ESAs is to help these plants find ways to start saving energy and money now, primarily in their industrial process heating and steam systems. The first 36 ESAs identified more than $95 million per year in total potential energy cost savings. If the plants carry out the recommendations made in these assessments, they could help to reduce U.S. natural gas consumption by more than 11 trillion Btu per year. They will also benefit from the enhanced productivity and greater system reliability associated with making energy-saving improvements.
The potential savings from ESAs will soar as assessments continue this year. See the Save Energy Now results page to keep track of the latest results, assessment summaries, and recommended actions for saving energy and money.
IACs Assist Small to Medium-Sized Plants
The IACs, housed at 26 universities around the nation, are also taking an active role by conducting in-plant assessments for companies in their regions. The IACs offer no-cost assessments at eligible small and medium-sized manufacturing plants.
In an IAC assessment, engineering faculty members and students from a participating university in the region conduct a plant assessment and recommend ways to improve the plant's efficiency. These assessments have identified an average of about $55,000 in potential annual savings for each manufacturing plant assessed.
Training and Tools Can Benefit Any Plant
Whether or not you are taking part in an ESA or IAC assessment this year, you can still take advantage of many other DOE resources. These include BestPractices training to improve your knowledge of compressed air, motor-driven, process heating, and pumping system management.
Training can help you get the most out of the free software tools DOE has developed to help plants assess energy savings opportunities. Plant managers and engineers can learn how to make the tools part of an integrated approach to energy management in their facilities.
You can also consult a DOE Qualified Specialist, an industry professional with advanced training in one or more of the software tools who brings valuable expertise and experience to the assessment process.
In addition to training and software tools, DOE offers numerous other resources to help you start saving, such as technical sourcebooks, tip sheets, technical briefs, and case studies. The new Save Energy Now CD brings together many of these resources and information from DOE's BestPractices and the Industrial Technologies Program portfolio. The CD is tailored to help industry plant managers and engineers save on energy costs, emphasizing reductions in natural gas consumption.
With all of these resources, your plant is well on its way to finding opportunities that can save money and energy today. Get started by visiting the Save Energy Now Web site. And for more quick tips on saving energy, visit DOE's 20 Ways to Save Energy Now Web page for industry plant managers and engineers. You can also access the Energy Efficiency and Renewable Energy Information Center online or call 1-877-337-3463.
DOE and Dow Join Forces to Save Energy Now
For the past decade, Dow Chemical Company has been making energy performance improvements that save a substantial amount of money as well as energy. Dow set a goal in 1994 to improve its energy use by 20% by 2005. The company exceeded that goal, reducing its overall energy intensity by 22% last year. That translates to cumulative savings of over 900 trillion Btu and more than $4 billion.
So why is a company with a well-established energy management program like Dow's participating in the U.S. Department of Energy's (DOE) Save Energy Now initiative? Both Dow and DOE have a common energy management goal—to lead by example.
"We operate in a global marketplace in which competitors have access to energy and raw materials at a fraction of U.S. costs," says John Dearborn, Global Vice President for Energy at Dow. "In this environment, energy efficiency is critical to the global competitiveness of any energy-intensive manufacturer. By participating in the DOE assessments, Dow aims to lead by example among other industrial energy consumers. Energy efficiency is a win-win for the environment and the economy." He adds that all American energy consumers need to be part of the solution.
Beginning with Energy Efficiency
Energy efficiency at Dow began with the company founders, when Herbert H. Dow teamed with George Westinghouse to develop one of the first generators for industrial cogeneration, improving a manufacturing process that depends heavily on the efficient use of energy. Energy efficiency is still important at Dow, because the company uses petroleum and natural gas as fuel and raw material for thousands of products considered to be essential to our daily lives, such as plastics, automobile tires, home insulation, and pharmaceuticals.
Today, Dow has annual sales of $46 billion and employs 42,000 people worldwide. Because of its size and scope, it is one of the largest consumers of energy in the United States.
"Dow aims to lead by example among other industrial energy consumers."
Global VP for Energy, Dow
Becoming an Industry Leader
Effective energy management continues to be a top priority at Dow, which has set an even more aggressive energy management goal for 2015 than the one for 2005. Overseeing Dow's energy management program is Joe Almaguer, Global Energy Efficiency Leader at the Dow Energy Systems Technology Center in Texas.
Almaguer leads energy efficiency teams and networks throughout the company to identify energy-saving improvement opportunities, develop long-term plans, and implement efficiency and conservation projects. That kind of strategic energy planning has enabled Dow to achieve substantial energy savings over the last decade. Among the actions taken were upgrading and optimizing power plants and manufacturing facilities, minimizing process waste, using energy-efficient manufacturing technologies where practical, and increasing energy capture from by-products such as hydrogen.
Almaguer recognizes the connection between Dow's goals and the DOE resources that can help achieve them. "DOE has put a lot of effort into developing energy best practices for industry," Almaguer says. "We have knowledge and tools. DOE has knowledge and tools. It makes sense that we collaborate and work together to continue to improve energy efficiency, not only in our manufacturing facilities, but in the industry as a whole."
Forming a Partnership with DOE
DOE's Industrial Technologies Program (ITP) launched its Save Energy Now initiative in 2005 to support a DOE national campaign, "Easy Ways to Save Energy," and to improve the energy efficiency of American businesses, factories, and manufacturing facilities.
Almaguer notes that Dow saw an opportunity in Save Energy Now to explore additional avenues to save energy and to advance the company's energy management leadership goals. Dow was one of the first six companies selected for a DOE Energy Savings Assessment (ESA) because of its interest and past success in setting an example in energy management. In the past year, the company hosted a steam system assessment at its Freeport, Texas, facility, and another at the St. Charles, Louisiana, site. In February 2006, a steam system assessment was completed at the South Charleston, West Virginia, site, and additional assessments are scheduled for sites in Freeport and Seadrift, Texas; St. Charles and Plaquemine, Louisiana; and Ludington and Midland, Michigan.
Assessing Energy Efficiency
At the Dow Freeport facility, three areas for improvement were targeted during the assessment: steam generation, steam utilization, and insulation. Experts from the phenol/acetone manufacturing facility, including plant engineers and technicians, attended. The training also included a field visit to view equipment.
A plant model was built using the DOE-developed Steam System Assessment Tool (SSAT). This tool allows analysts to develop approximate models of real steam systems. SSAT can then be used to quantify opportunities for energy, cost, and emissions savings.
During the assessment, various steam processing projects were evaluated. These included steam generation and acquisition options as well as improvements in steam venting. Recommended improvements included replacing the plant's steam turbine with an electric motor to reduce venting and improve boiler efficiency. The potential energy cost savings were estimated at $508,000 per year.
Hosting Groundbreaking Training
Between October 2005 and February 2006, Dow worked with DOE to pilot innovative methods of enhancing delivery of ITP BestPractices training through directed Webcasts. During the Web cast training sessions for Dow, DOE representatives demonstrated the software tools used to assess opportunities for savings at energy-intensive industrial facilities.
More than 200 Dow engineers, representing sites throughout the United States and elsewhere, participated in the 14 Webcast sessions. The ITP BestPractices tools demonstrated included these:
- Plant Energy Profiler (ChemPEP)
- Steam Systems Tool Suite
- Process Heating Assessment & Survey Tool (PHAST)
In addition to participating in the Webcast series, Dow will host two 1-day, in-depth steam system assessment training sessions this year, conducted by DOE in Freeport, Texas, and at Union Carbide St. Charles Operations sites in Hahnville, Louisiana.
"By hosting these training sessions in Freeport and at the St. Charles Operations sites, we will be bringing the sessions right into the heart of where industry folks are located and drawing in not just Dow but the surrounding industrial community members," Almaguer says. "This makes it more convenient and less expensive for those interested in participating to learn how they can reduce energy consumption at their manufacturing sites."
Incorporating Energy Management
DOE's experience in working with large companies like Dow has led to guidelines on leadership in energy management best practices. Those best practices are captured in Dow's corporate energy management (CEM) program.
CEM refers to best practices that place the accountability for a company's energy management at the corporate level, rather than at the level of plant managers and engineers. CEM takes a synergistic approach in that it involves many areas of business activity, including accounting, marketing, and other areas not traditionally concerned with energy management. You can read more about how to save energy with a corporate energy management program by visiting ITP's BestPractices Corporate Energy Management Web page. (PDF 407 KB) Download Adobe Reader.
Like Dow, which is leading by example to save energy and money, you can also help to set the pace for a company-wide approach to energy management. Here are additional recommendations and resources to help you get started.
- Learn about plant energy assessments
- Take advantage of ITP BestPractices resources to improve your plant's energy efficiency
- Review ITP BestPractices case studies to learn how other companies are achieving successes
- Partner with ITP to create greater awareness or host events to Save Energy Now
- Sign up for a Webcast or a training session near you.
New Alliance Targets Industrial Energy Efficiency in Northwest
The Industrial Efficiency Alliance (IEA), a new organization in the U.S. Northwest, is committed to helping industrial manufacturers increase their energy efficiency and make energy management a part of their everyday business operations. One goal of the new alliance is to help regional industries reduce their electricity use by a total of 130 MW—enough to power 90,000 households for a year—by 2015.
Initially, the new alliance is working with pulp and paper mills and food processing companies with large or multiple facilities, as well as with related trade industries. It was launched in 2005 by the Northwest Energy Efficiency Alliance (NEEA), a long-time U.S. Department of Energy (DOE) Allied Partner.
Through the Industrial Technologies Program (ITP) BestPractices and the network of Allied Partners, DOE provides technical assistance, software tools, training, and other support to industrial manufacturers to help them increase the energy efficiency of their operations, reduce costs, improve environmental performance, and enhance productivity. IEA is also incorporating ITP BestPractices resources into its own program.
Targeting Pulp & Paper and Food Processing
Pulp and paper and food processing are two key industries in the Northwest that consume a significant amount of energy as part of their normal operations. Because these industries present many opportunities to save energy and reduce costs, the Industrial Efficiency Alliance is focusing on them in its initial work.
Manufacturers that work with the alliance can reap such benefits as lower utility costs, increased profits and competitiveness, and greater plant safety and reliability. These are especially important to companies with slim profit margins. For example, the food processing industry relies on a 6% profit margin for success. This means that every dollar saved is worth an estimated $16.67 in return.
In addition to industry participants, the IEA works with many trade groups, utilities, and other organizations that support industry in the Northwest, such as these:
- Bonneville Power Administration
- The Northwest Food Processors Association
- Washington State University Extension Energy Program
Promoting Continuous Energy Improvement
IEA has established a Continuous Energy Improvement Program (CEIP) to engage employees at both the corporate and the plant level. Companies are encouraged to make a commitment to change, to recognize that energy costs are controllable, and to take a whole systems (rather than a single-component) approach to manufacturing operations. Taking this approach can reduce a company's energy use by 10% or more, according to NEEA.
The CEIP stresses the importance of having an energy management policy, assigning an improvement "champion" or sponsor, and setting energy productivity goals and objectives. Participating companies are encouraged to measure performance through key indicators, such as Btu consumed per pound of output, and to work with suppliers committed to energy-efficient business practices.
Bob Helm, a professional engineer and senior manager for the industrial sector in the Northwest Energy Efficiency Alliance, is leading this new effort.
Helm says, "The Continuous Energy Improvement Program provides tremendous returns for industrial customers and for the regional businesses that support them. Government and nongovernment agencies, utilities, allied partners, and private businesses can all succeed in this program, thanks to coordination that leverages combined talent, ideas, and dollars in a cohesive strategy."
Offering Special Tools, Training, and Resources
The CEIP leverages all available tools, training, and resources. For example, the program promotes the use of software assessment tools offered through ITP BestPractices. By incorporating these tools into their assessments, they can help industrial plants identify and analyze the many opportunities for energy savings in their plants. The tools include MotorMaster+, the Pumping System Assessment Tool (PSAT), the Steam System Assessment Tool (SSAT), AIRMaster+, and the Process Heating Assessment and Survey Tool (PHAST).
IEA's training calendar lists courses available to companies throughout the region. And its industrial training curriculum augments DOE's Best Practices courses. Through its allied partnership, the alliance works with DOE to develop and promote projects and case studies that demonstrate the value of energy efficiency.
The new alliance also offers technical assistance using energy management specialists who take a whole-systems approach to manufacturing. They assist in evaluating key industrial systems such as compressed air, motors and drives, pumps, and refrigeration.
Emphasizing Energy Management
Bob Helm says that many different industries will eventually be able to participate in this new program. Companies that can benefit the most are those that are interested in improving their energy management practices, making a commitment to continuous energy improvement, have a culture of learning, and are willing to share their success stories.
"With a coordinated strategy, focused on the customers' needs, we will have a profound effect on industrial business practices as they pertain to energy use," Helm says.
For more information, please contact the Industrial Efficiency Alliance online or call 1-888-720-6823. You can also visit the ITP BestPractices Web site to learn more about partnership opportunities, training, software tools, and other resources.
|Pulp and Paper||Food Products||Wood Products||Transportation||Computers and Electronics||Other|
|Pump System Efficiency||6%||3%||1.10%||1.80%|
|Fan System Efficiency||1%||0.10%||0.70%||1.80%||5%|
|System Improvements: Energy||0.80%||5.60%||1.50%||5%|
|System Improvements: Process||1.50%||1.20%||0.75%||0.00%||2%|
|Total Market Sector Savings||11.80%||19.90%||8.05%||13.60%||14%|
|Motor Efficiency Upgrade||5%||5.40%||1.90%||3.40%|
|Total Cross-Cutting Savings||8.50%||10.80%||7.90%||12%||10.75%||7.50%|
Chemical Plant Assessment Uncovers More Than $3 Million in Potential Savings
Using a unique method known as "SECURE," an energy assessment team found ways to reduce the use of steam, electricity, compressed air, and water at a Solutia chemical plant and save nearly 340,000 million Btu (MMBtu) of natural gas per year.
A plant-wide energy assessment at Solutia Inc.'s chemical production facility in Springfield, Massachusetts, uncovered opportunities to save nearly $3.3 million in energy costs there annually. Implementing all the potential projects identified would save an estimated 9.6 million kilowatt-hours (kWh) of electricity and more than 338,000 MMBtu of natural gas each year. The initial investment required would be $6.3 million, so the project would pay for itself in about 2 years.
The assessment team used the company's Steam, Electricity, Cooling Utility Reduction Exercise (SECURE) method to address energy generation and use. With this method, Solutia's team could focus on reducing the use of steam, electricity, compressed air, and water at the entire site, considering the site as an integrated entity rather than as a collection of individual processes.
- Identified approximately 9.6 kWh in electricity savings per year
- Uncovered opportunities to save 338,000 MMBtu in natural gas annually
- Could save $3.3 million in energy costs annually
Solutia's energy management team conducted the assessment to ensure that plant processes are designed to save as much energy as possible while generating less waste.
The U.S. Department of Energy's (DOE) Industrial Technologies Program (ITP) cosponsored the assessment through a competitive solicitation process. ITP's BestPractices promotes plant-wide energy-efficiency assessments that will lead to improvements in industrial energy efficiency, productivity, and global competitiveness while reducing waste and environmental emissions. In this case, ITP shared $100,000 of the total $305,000 assessment cost.
About the Plant
Solutia manufactures polymers, intermediates, and chemicals; it was formed in 1997 from one of the Monsanto Company's chemical divisions. Solutia produces performance films for laminated safety glass and after-market film applications and manufactures specialty products such as water treatment chemicals, heat transfer fluids, and aviation hydraulic fluid.
Solutia's 180-acre Springfield facility, the largest chemical manufacturing facility in New England, employs about 500 workers. Its management takes an active interest in energy conservation, safety, and the environment. Therefore, Solutia has established goals to ensure that process designs maximize energy conservation and minimize waste. The site's total annual electricity consumption is about 95 million kWh. Energy generated from natural gas and coal amounts to 1.25 million MMBtu per year, and the site uses 2.5 billion gallons of fresh water annually.
Primary production processes include batch and continuous processing systems and solvent recovery processes that use steam-intensive distillation. Production processes focus on the manufacture of polymer resin and chemicals, extrusion of the resin into sheet, and related applications. The utility generation and distribution facility is centralized. Utilities generated on-site include steam (from coal and natural gas), electricity, compressed air, and nitrogen. An on-site cogeneration facility, owned and operated by Mass Power, supplies steam.
The assessment team was made up of Solutia's process experts, utility engineers, research and development scientists, cost estimators, accountants, process and project engineers, and external consultants. They used the Steam, Electricity, Cooling Utility Reduction Exercise (SECURE) method to address both the process and utility sides of the site's operations. This method considers the site as an integrated entity rather than a disparate collection of individual processes.
For production processes, the assessment team collected data on steam, electricity, water, and wastewater usage and costs. They also compiled data on energy use for individual process equipment. They then analyzed this information to identify primary energy users and each one's potential for energy savings.
Then the team evaluated opportunities to reduce the amount of energy used by the equipment and processes that had been identified as significant energy users. To do so, the team reviewed earlier ITP plant-wide assessment case studies, compiled a list of energy savings ideas and best practices, and evaluated the potential for integrating equipment. For example, they looked at whether hot effluent from a distillation column could be used to preheat feed to the column. Finally, the team considered site-wide projects such as recycling steam condensate, which would have an impact on several different processes.
Assessment Results and Identified Projects
The analysis resulted in an initial list of about 80 potential projects. These were pared down to about 30 projects that were determined to be technically and commercially feasible. A more detailed description of some of the projects follows.
Project 1. The assessment team used a chilled water system simulation model to determine the range of optimum operating temperatures for chiller and cooling tower water based on ambient conditions. The team recommended resetting chiller water temperature set points.
Project 2. The team recommended installing a new high-capacity pilot on the burner system in a gas boiler so it could operate at a lower minimum fire level. The pilot would allow the boiler to ramp up to required operating conditions more quickly and would ignite the fuel immediately, without the need for purging. Steam is supplied primarily by a coal boiler, although a gas boiler can also supply steam when the process load fluctuates. Solutia's gas-fired boiler has a relatively high minimum fire level because its burner system is almost 30 years old.
Project 3. The team recommended connecting the preheating systems of coal and gas boilers to transfer the heat load from the gas-fired boilers to the coal-fired boiler whenever the gas-fired ones are producing steam. The coal boiler has a feedwater preheating system; the gas boilers do not. So, fuel burned in the gas boilers provides both the latent heat of vaporization and the sensible heat needed to increase the feedwater temperature to the boiler's operating temperature. However, the sensible heat needed for the gas boilers can be derived by using coal-generated steam rather than burning natural gas.
Project 4. The team recommended repairing any steam traps that were blowing through, leaking, plugged, or flooding—in other words, any that were failing. They found that, out of 700 traps inspected, about 100 had failed.
Project 5. The team recommended retrofitting fluorescent light fixtures with new electronic ballasts and replacing older T12-style light bulbs with high-efficiency T8 bulbs. They also recommended replacing metal halide high-intensity discharge lamps with new, higher efficiency metal halide lamps.
Project 7. The assessment team recommended capturing waste heat from the air compressors and using it to preheat the boiler feedwater. Inadequate air coolers could also be replaced with two new plate-type heat exchangers. The air compressors in the site's centralized air compressor system currently generate a significant amount of waste heat. The compressors have a closed-loop cooling system; coolant-to-air heat transfer is done by means of several undersized heat exchangers. The heat exchangers operate at elevated temperatures in summer and so must be cooled by a water spray system.
These and the other potential projects could save Solutia more than $3 million in operating costs each year and significantly reduce energy usage at the plant. For more, see the full case study (PDF 979 KB). Download Adobe Reader.
Polymer and Chemical Technologies
For more information on plant assessments and reducing your natural gas usage, visit the ITP BestPractices Web pages.
|Project Number||Project Description||Cost Savings ($/year)||Capital Cost ($)||Payback (years)||Fuel Savings (MMBtu/year)||Electricity Savings (kWh/year)|
|1||Optimize chiller water temperatures||46,000||NA||NA||NA||536,000|
|2||Upgrade boiler burner system||240,000||70,000||0.3||89,000||NA|
|3||Transfer heat load for feedwater preheating from gas-fired to coal-fired boiler||25,000||60,000||2.4||9,000||NA|
|4||Repair steam traps||151,000||60,000||0.4||29,000||NA|
|5||Upgrade lighting fixtures||78,000||130,000||1.7||NA||918,000|
|6||Install new cooling tower to reduce process water usage||750,000||3,200,000||4.3||NA||NA|
|7||Use air compressor waste heat to preheat boiler feedwater||208,000||58,000||0.3||35,000||159,000|
|8||Reduce boiler blowdown frequency and automatically control blowdown||9,000||8,000||0.9||1,700||NA|
|9||Recover boiler heat and water losses||376,000||296,000||0.8||82,000||NA|
|10||Recycle steam condensate||396,000||608,000||1.5||62,000||NA|
|11||Recycle process cooling water to the power plant||195,000||160,000||0.8||21,000||NA|
|12-23||Install variable frequency drives on chilled water pumps, cooling tower water pumps, cooling tower fans, chiller motors, hot water pump east, boiler feedwater pump, biofilter supply fan, dryer exhaust fan, biofilter scrubber pump, boiler fans, and B crude pump||555,000||1,295,000||2.3 (avg.)||NA||6,505,000|
|24-27||Install variable-air-volume systems on process air-handling units||136,000||198,000||1.5 (avg)||2,700||819,000|
|28||Recover air knife waste heat||33,000||90,000||2.7||6,200|
|29||Upgrade air knife blowers||6,000||22,000||4||NA||66,000|
|30||Optimize air knife blower system||32,000||60,000||1.9||NA||378,000|
|31||Automate control of extrusion process supply and wind fan to operate fans only when needed for process conditions||27,000||9,000||0.3||500||173,000|
Pumping System Improvements Save Energy at Texas Power Plant
In March 2004, Austin Energy—the electric utility for the city of Austin, Texas—completed an improvement project on the circulating water pumping system that serves a 405-MW steam turbine at its Decker Creek Generating Station. First, a pumping system assessment was performed in part by a (DOE) Qualified Pumping System Assessment Tool (PSAT) Specialist from Flowserve Corporation using DOE's PSAT software assessment tool. This assessment helped utility personnel create a project that would improve the system's energy efficiency and output capacity.
The project involved upgrading several of the pumps' critical components as well as reconfiguring some equipment. When it was completed, the project greatly improved the pumping system's efficiency and performance. These improvements resulted in significant energy savings and reduced maintenance requirements.
- Saves $1.2 million annually
- Reduces annual energy consumption by 220,000 MMBtu
- Reduces maintenance costs
- Achieves an 11-month simple payback
Circulating water pumping systems are needed for any application in which cooling water is required to maintain the temperature of a process. In this application, a power plant uses cooling water to condense steam.
The Decker Creek Generating Station has two steam turbines and 200 MW of gas turbine peaking units. This project focused on the largest steam turbine, a 405-MW power plant that has been serving the city of Austin, Texas, since 1978.
Two 1000-horsepower (hp) circulating water pumps deliver cooling water from a lake to equipment that condenses the steam coming from the turbine. Before the project, these pumps were not equipped to deliver the amount of cooling water required, despite operating at full load. Both pumps were designed to have a combined flow rate of 236,000 gallons per minute (gpm), which was supposed to achieve a turbine back pressure (TBP) of no more than 3.5 inches. During routine, twice-yearly heat rate testing, plant personnel found that the cooling water flow was insufficient to achieve the rated steam flow, and the power plant's efficiency was more than 5% below the design efficiency level.
The assessment revealed that the system's actual flow rate when both pumps were running had degraded to 195,000 gpm, that pump efficiencies were between 50% and 55%, and that the TBP at times increased to as high as 4.1 inches of mercury absolute (HgA), or more than 17.5% above the design TBP. Furthermore, the pumps were vibrating severely, sump vortexes were frequent, and impeller surfaces were severely eroded. The project involved upgrading the circulating water pumps with new impellers, diffusers, shrouds, and shafts. In addition, the plant personnel and Flowserve's pump repair shop reconfigured the suction bell, sections of the intake sump of both pumps, and the pumping station. Finally, they replaced the suction flow splitter below the pumps to better direct the incoming lake water.
These improvements to the plant's circulating water-pumping system resulted in an increase in the pumps' combined flow rate to 11.5% above their design rating. This increase sharply reduced the need to operate both pumps concurrently to satisfy the plant's cooling water demand. Because of the reduction in the parasitic pump load and in the need for additional cooling water, the plant's efficiency increased, yielding annual energy savings of 220,000 MMBtu and energy and maintenance cost savings of $1.2 million per year. With total project costs of $1.1 million, the project had a simple payback of 11 months.
Circulating water-pumping systems should be checked periodically to ensure that they are operating satisfactorily. At the Decker Creek Generating Station, a kink at the low spot in the impulse line from the condenser to the vacuum manometer in the control room caused a water leg (trap), which prevented the vacuum manometer from providing accurate TBP readings. This, in turn, masked the performance of the system. Once the entire system was reviewed, including the pumps' efficiencies, plant personnel were able to discover the suboptimal flow rate of the pumps, determine its cause, and devise an appropriate improvement strategy.
After the project, tests showed that pump efficiency levels had risen to 85%. More importantly, the pumping system flow rate improved significantly. The pumps can now deliver more than 263,000 gpm, an 11.5% increase above the original design flow rate. There has also been a large reduction in vibrational amplitudes, from as high as 3.3 mils down to 0.2 mils, and a TBP improvement of about 3.2 inches HgA. These improvements allow the plant to operate at full capacity using only a single pump, and to do so much later into the summer than it did before the project began—saving both energy and money. The methods applied in this project can be implemented in power plants and at practically all industrial facilities that require water for process cooling.
Alan Flory is a mechanical engineer and a PSAT Qualified Specialist who has been with Flowserve for 12 years. He has worked with Flowserve's IT group to develop pump selection software and has authored technical papers on boiler feed water pumps. In his current role as Industry Director, he focuses on upgrading the efficiency and reliability of pumping systems for Flowserve's industrial customers.
Qualified Specialists are industry professionals who identify cost-cutting and efficiency opportunities in industrial plants. Experienced professionals who complete a qualification training workshop and exam for specific DOE-developed software tools receive special designations, and they can use these tools to help plants reduce costs, decrease maintenance and downtime, and improve productivity. The training recognizes and enhances a professional's expertise in the use of DOE's AIRMaster+ software tool, Pumping System Assessment Tool, Process Heating Assessment and Survey Tool, and Steam System Tools.
For more information on Performance Spotlights, see the ITP BestPractices Web Pages.
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.