Research & Innovation
Energy on the Cost-Cutting List
Although the pulp and paper industry has made great strides in reducing energy use, rising prices continue to erode the benefits gained from these initiatives. Energy still represents 15-25 % of the t...
June 1, 2008 By Pulp & Paper Canada
Although the pulp and paper industry has made great strides in reducing energy use, rising prices continue to erode the benefits gained from these initiatives. Energy still represents 15-25 % of the total production costs for a pulp and paper mill, and as a result, optimizing the management of this resource is a top priority.
The Belgo Mill in Shawinigan, QC, is owned by Abitibi-Bowater. In 2003, the mill concluded a performance service contract with energy management consultant OPNOR. The focus was on implementing an energy-optimization program for the mill’s equipment. The savings in fossil fuel were impressive, at $6 per ton.
To get there, OPNOR used an Energy Performance Services Contract, which has become an increasingly popular way to optimize. The EPSC identifies hidden energy-saving opportunities and creative financing options that provide quick pay-backs, positive cash flows and the option of vendor-arranged financing.
The contract between OPNOR and the Belgo Mill began in 2003, with a validation of the performance guarantees, followed by implementation of the various projects. This first step was a targeted review of the mill’s steam-distribution system. Next came a detailed analysis to identify and focus on those processes that offered the best energy-reduction opportunities. It also gave planners a portrait of the annual steam consumption by sector.
Over time, multiple performance service contracts were implemented, which included engineering detail, project management, optimizer server configuration, new system commissioning and operational startup, sector energy balances, performance reports available on the mill-wide network and one year of monitoring/ support. The sub-projects completed within the scope of the contracts were: 1. One paper machine optimization, including;
• the energy-recovery system as well as corrections at the hood to increase the recovery rate;
• supervisory control of the air temperature of air supply systems to the paper machines;
• supervisory control of dryer differential
2. Optimization of two additional paper machines, including;
• energy-recovery system on one machine;
• condenser cooling water;
• integration and management of the water systems for the two machines.
3. Optimization of the steam recovery from the pulp preparation plant, including;
• venting supervisory control;
• refiner line stop/start optimization;
• refiner network pressure supervision.
4. Optimization of shower water consumption for all three paper machines, including;
• modelization of the low and high pressure steam supply networks;
• supervision of, and alarms for faulty showers.
Integration: How It’s Done
The new control loops are integrated with the existing systems and new set points are generated by a supervising computer. This PC communicates through an interface with related mill control systems.
The new optimization measures are transparent to the operators and have little or no impact on paper production. Mill visits, combined with regular monitoring via remote access ensure sustained performance, year after year.
Payback: The Results
The optimization systems installed by OPNOR generated energy savings of $140,000 per month, equivalent to 23 Gj/ hr at an average energy cost of $8.70/Gj. As a bonus, the mill reduced greenhouse
gas emissions (GHG) or CO2 from fossil fuels by about 15,000 tons/year. The capital cost of the new equipment was about 25% of one full year of savings achieved.
Sadly, despite these major low-risk energy savings, the Belgo Mill has since been closed permanently for multiple other economic reasons. However, the lessons learned and techniques developed at this mill have already been applied very successfully at other Abitibi-Bowater mills, with more projects pending.
The EPSC: How Does It Work?
The typical pulp and paper Energy Performance Services Contract (EPSC) has three steps. They are business opportunity definition, which helps define potential returns involved in implementing an EPSC, performance guarantee validation, which determines the feasibility of a project, and contract implementation, which focuses on implementing the recommendations arrived at and agreed upon between vendor and client in step two.
The total duration to complete them should not exceed 18 months.
Typical Cost -Benefit Expectations
The chart shown below demonstrates the total typical implementation cost range, including equipment and vendor fees, and annual savings range that can be expected from an energy-performance services project. The client can perform an estimate for a particular mill, knowing the mill’s annual total cost of fossil fuel.
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