Graham Packaging Saves 7.5 Million kWh with Compressed Air and Chiller Upgrades
Background
Graham Packaging is a producer of polyethylene terephthalate (PET) and high-density polyethylene (HDPE) bottles for the food, beverage, home care, and industrial industries. Graham Packaging’s plant in Florence, Kentucky produces 283 million PET bottles and 384 million preforms annually. Due to the variability in demand and high pressures required for these products, the Florence plant presented an opportunity for Graham Packaging to upgrade its controls and management systems for the compressed air and chilled water systems. The team quickly identified untapped efficiency gains from automating compressed air and chilled water production based on demand and adding variable frequency drives (VFD) on chiller pumps and cooling tower fans. These upgrades enable plant operators to respond to intermittent demands and run equipment only when needed.
Each energy efficiency improvement was evaluated to ensure it met Graham Packaging’s performance standards. There were significant barriers to be overcome, including the need to maintain precise water temperature and pressure to key systems and production equipment, as well as avoiding prolonged downtime. These barriers were addressed by installing a comprehensive package of air and water management upgrades that improved overall performance and achieved an 11 percent reduction in electricity usage after the first year.
Solutions
Graham Packaging outlined a project timeline of six months for the project and started by tasking a dedicated team to evaluate operational inefficiencies in the Florence plant. The project team assessed multiple energy improvement options and worked with their utility to secure available rebates and incentives for HVAC and compressed air upgrades. During the audit phase, the team collected records of production demand, installed data loggers, and analyzed energy and water usage. Graham Packaging also partnered with compressed air and HVAC vendors to do detailed analyses of the existing systems. They found that significant energy savings were achievable through an automated control system for the compressed air and chilled water systems. Acting on these findings, the team identified multiple measures that taken together and factoring in utility incentives, would achieve a return on investment of less than 24 months.
The project scope included upgrading chiller pumps, installing VFDs on cooling tower pumps and fans, and replacing an inefficient centrifugal chiller. The plant replaced the old centrifugal chiller with a new variable speed drive magnetic bearing chiller. The new chiller is designed to use less power by taking advantage of lower condensing water temperatures that are produced by cooling towers throughout the operating year. Since the Florence plant is located in an area with colder temperatures for much of the year, the new chiller can run the cooling towers at lower speeds and utilize outside air. This process reduced energy usage while maintaining a production chilled water temperature of 44oF. Additionally, the chiller increased cycles of concentration within the cooling tower due to a decrease in the evaporation created by the system heat load.
Energy-efficient chiller with control unit
Graham Packaging also installed upgraded control systems for both the compressed air and chilled water systems. The controls enable the system to meet production demand requirements using real-time data on temperature, flow, and pressure. Installation of the new chiller and controls system took place during scheduled shutdowns of the facility, which reduced the impact on production. Graham Packaging also trained maintenance staff on the operation, management, and limitations of the newly installed system. This training was critical for plant staff to efficiently operate the new controls and implement maintenance protocols for all the new equipment.
Control unit with sequencing and variable frequency drives
The Florence plant upgrades improved efficiencies of the facility’s production systems, including the compressed air and chilled water used in the production of food-grade PET bottles and preforms. The data collected before and after the project allowed the company to quickly quantify the savings of these improvements and the overall project. In total, Graham Packaging achieved an 11 percent reduction in energy intensity—from 1,267 kWh per 1,000 pounds produced to 1,127 kWh per 1,000 pounds produced. Over the 18 months since project completion, the plant has reported a total savings of 7,497,953 kWh.
Other Benefits
The Florence, Kentucky facility was the first Graham Packaging plant to install and utilize an automated compressed air and chilled water management system. Due to the success of the project, the company began to examine other facilities that can benefit from the same system upgrade. Graham Packaging subsequently identified and introduced similar energy-saving projects at five other plants in the United States. Overall, this project has set a new standard for Graham Packaging plants looking for opportunities to reduce their energy usage and will make a significant impact on the company’s ten-year goals to achieve a 25 percent energy reduction by 2028 and a 30 percent reduction in greenhouse gas emissions by 2030.
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