How to minimize production costs by reducing energy consumption.
Daishowa-Marubeni International (DMI) owns and operates the Peace River Pulp Division (PRPD) mill, located in Peace River, Alberta. PRPD produces premium hardwood (aspen) and softwood fully bleached kraft pulp in campaigns. In continuing efforts to reduce production costs through reduced energy consumption, DMI implemented strategies to optimize the hot and warm water systems through an integrated system-wide approach.
BUSINESS PROBLEM SOLVED
As part of an ongoing effort to reduce production costs, DMI chose to implement three projects identified in a pinch analysis as opportunities for energy conservation.
TECHNICAL PROBLEM SOLVED
An integrated system-wide strategy, to utilize the copious warm water available to produce higher-value hot water, was implemented through three project components. Surface Condenser water tempering was implemented in order to produce consistently warmer water. This warmer water is then fed to the Dump Condenser to produce hotter water for use in other plant process use, and is also fed to a new Cold Blow Cooler. The new Cold Blow Cooler helps to ensure that the blowline temperature remains below the target which eliminates cost Diffusion Washer bypasses, as well as produces hot water for other process use.
WHAT WE DID
The feasibility of implementing three of the component projects identified in the pinch analysis was determined through preliminary process design, scope development, and cost estimating. Once the projects were deemed feasible, the design implementation included heat and material balances of the warm and hot water system to ensure the design flows produced optimal warm and hot water temperatures; equipment sizing and specifications; and integration of the new equipment and controls into the existing control system. A HAZOP review was performed to ensure the new components would have no unintended compromise to safety or operations. The new Surface Condenser Recir pump design adhered to the energy saving intent of the project by utilizing a magnetic coupling to accommodate widely varying flow demands.
Integration of a new Cold Blow Cooler in series with the existing cooler. This additional cooling reduced the frequency of Diffusion Washer bypasses, thereby saving associated soda loss costs, improving delignification efficiency, and reducing bleaching costs. The design considered all operating, seasonal, and feedstock changes and implemented design facets to ensure stable operation in all conditions.
The completion of the design components was scheduled to ensure coordination of the shutdown construction with the mill’s annual scheduled outage, and allowed installation of the Cold Blow Cooler to be performed without a process shutdown and prior to the summer months, in order to capitalize on the period of greatest bleach savings.
PROJECT LIFECYCLE SERVICES USED