Date of Defense
Date of Graduation
Chemical and Paper Engineering
The goal of the Yoda Chemical Company Paper Recycling Fiber Recapture project and subsequent report was to identify and recommend plant optimization opportunities associated with the potential recovery of five waste streams. Additionally, an analysis of the upgrade’s design was completed in order to determine the economic viability of fiber recapture. Beginning the analysis, the five waste streams were identified and analyzed. The waste streams include the top liner, back liner, and filler liner primary cleaner rejects on the K1 machine, the common rejects from under the K3 paper machine, and the tertiary cleaner rejects from stock preparation.
Two different fiber recapture scenarios were evaluated for economic and process viability. Option One rerouted each waste stream back into the pulper in the stock preparation area. Option Two rerouted the tertiary cleaner rejects from stock prep back into the pulper, while the other four streams were rerouted to the fractionation stage in the process prior to the paper machine pressure cleaners. Both of these options required assumptions to be made. First, when a reject stream was recycled back into the system, it was assumed that all usable fiber was then considered accepts. The second assumption was that mill equipment was located in close proximity in order to prevent the installation of unnecessary tanks and pumps. A third fiber recovery option was explored in relation to optimizing the cleaners and screens currently in use through the addition of elutriation water, changing the hydrocyclone cleaners’ diameters, and changing the pressure cleaners’ hole and slot sizes.
The cost of equipment required to complete Options One and Two was found in addition to the savings in utility costs resulting from the changes. The equipment costs were $43,593.94 and $44,800.86 for Options One and Two, respectively. The differences between these costs could be attributed to how the streams were rerouted in each option. Next, the amount of savings due to the decreased utilities was calculated. For Option One, the annual savings in utility cost amounted to $522,333.87. In Option Two, the annual utility savings was slightly lower at $516,699.15. Based on a seven year MACRS cash flow analysis consisting of a ten year plant life and 30% minimum acceptable rate of return, Option One resulted in a net present value of $1,077,238.38, a return on investment of 1,825%, and a payback period of 0.4467 years. Option Two produced a net present value of $1,057,981.98, a return on investment of 1,754%, and a payback period of 0.4638 years.
Riley, Erin, "Paper Recycling Fiber Recapture" (2020). Honors Theses. 3352.
Honors Thesis-Open Access