In 2000, Caraustar, in partnership with the Department of Energy, conducted plant-wide energy assessments at two of its recycled paperboard mills, the Chesapeake Mill in Baltimore, and the Rittman Mill in Rittman, Ohio. The assessments identified potential opportunities for systems and process efficiency improvements that could result in important energy savings and improved productivity. Among the improvements included investments in insulation. The projects would particularly improve the efficiency of plant steam systems and would substantially decrease dependence on purchased electricity and fuel. Annual cost savings were estimated at $1.2 million and $370,000 at the Rittman and Chesapeake mills, respectively.

Caraustar is a major manufacturer of recycled paperboard and converted paperboard products. The company operates more than 100 facilities in the United States, along with plants in Mexico and the United Kingdom. Caraustar manufactures its products primarily from recovered fiber derived from recycled paperstock. At its 16 paperboard mills, Caraustar produces various grades of uncoated and clay-coated recycled paperboard both for internal consumption and for sale to customers in four principal markets. In addition to the mills, Caraustar’s facilities include tube and core converting plants, composite container plants, folding carton plants, and speciality converting plants.

Large quantities of electricity, natural gas, coal, and oil are used in the production of recycled paperboard. Caraustar purchases electricity and natural gas for all its facilities, but also purchases significant quantities of fuel oil and coal for many of its recycled paperboard mills. Energy accounts for 15 percent to 25 percent of each mill’s total operating expenses, and is third only to raw material and labor in a mill’s operating cost structure.

Caraustar has made a commitment to continually maintain and improve its paperboard mills. During the past 5 years, Caraustar has spent more than $30 million annually in capital expenditures, primarily to expand and upgrade its paperboard production, and to convert capacity by acquiring and maintaining state-of-the-art machinery and technology.

Assessment Overview

Caraustar has historically monitored the cost per ton of paper produced in its Mill Group. As a result of this study, the company has also begun to document energy costs for the Industrial and Consumer Products and Packaging divisions.

Caraustar conducted the plant-wide energy assessment in association with Sterling Energy Services, LLC. The project was partially funded by the DOE’s Industrial Technologies Program. The assessment team conducted comprehensive plant energy efficiency reviews using a systems approach combined with industry standard practices. Opportunities for energy savings were identified and documented, then evaluated and prioritized based on potential for energy savings. Maintenance practices and operating procedures were also reviewed for their impact on energy efficiency.

Assessment Implementation

The assessment team first developed complete lists of the energy-consuming production and mill utility processes (steam, compressed air, and on-site power production). The team conducted detailed audits of the processes believed to have the greatest energy savings potential.

The areas investigated included:

• steam systems
• cogeneration assessment
• waste heat recovery
• motor analysis
• compressed air systems
• lighting systems
• electric variable speed drive analysis

Seven specific systems and processes were evaluated in detail for efficiency improvement or cost reductions for the Chesapeake mill. (Caraustar closed the Chesapeake mill in the spring of 2000 because of overcapacity in the industry and other issues. In spite of this closure, Caraustar realized that the assessment’s findings were valid for similar facilities.)

The systems and processes evaluated at the Chesapeake mill included:

• backpressure steam turbine generator
• boiler feed pump variable speed electric drive
• boiler feed pump steam turbine drive
• paper machine #2 variable speed electric drive retrofit
• vapor-absorption system boiler stack heat recovery
• stock pulper fill water heat exchangers
• improved insulation of steam pipes

Six systems and processes were also evaluated for efficiency improvements at the Rittman mill. These included:

• project requirements analysis for mill cogeneration (replacement or retrofit of existing operations)
• benchmarking mill operations’ energy use
• pulper fill water heat exchangers
• modifications to steam injection stock heater
• coater oven steam requirement efficiency or elimination
• heat recovery for vapor-absorption system

Actions Identified in the Assessment

The plant-wide studies concentrated on identification of energy efficiency improvements for Caraustar’s Chesapeake and Rittman mills, with an extended focus on the development of efficiency concepts that could be transferred to other Caraustar facilities. Many of the efficiency measures identified and evaluated in this assessment will benefit other Caraustar mills as well as those of other recycled paperboard manufacturers. These include:

• motor procurement and efficiency improvements
• backpressure steam turbine generators
• boiler feed pump variable speed drives
• stack heat recovery to vapor-absorption systems
• pulper fill water heat exchangers
• steam pipe insulation

The application of these energy efficiency measures is being reviewed for other Caraustar mills. In addition to the energy efficiency measures identified, other measures were found that did not offer immediate benefits for either Chesapeake or Rittman, but should offer some benefits to other Caraustar locations. These measures include:

• boiler forced draft fan variable speed drives
• paper machine dryer section drive retrofits

Before initiating the two mill energy assessments, Caraustar had already undertaken a project to inventory electric motors at selected mills to identify savings opportunities that could be realized from implementation of a formal motor management program. The plant-wide energy assessment permitted the project team to accelerate the motor management effort. As a result, Caraustar has implemented a corporate procurement program for electric motors, power transmission, and related industrial equipment that has reduced the cost of purchasing these items, and boosted the opportunities to improve the overall efficiency of each plant’s motor inventory. The plant-wide energy assessment project has been an important component in extending Caraustar’s focus on energy efficiency and cost reduction measures in all divisions.

This article originally appeared in the Spring 2003 edition of Energy Matters, published by the U.S. Department of Energy. For plant-wide assessment program information, contact Grace Ordaz of the DOE’s Industrial Technologies Program by phone at (202) 586-8350 or by e-mail at grace.ordaz@ee.doe.gov. For technical details about the assessments, visit www.oit.doe.gov/bestpractices/factsheets/.pdf, or contact Bob Leach of the Oak Ridge National Laboratory by phone at (865) 946-1352 or by e-mail at leachre@ornl.gov.