Effect of Pulp Delignification Degree and Bleaching Process on an Eucalyptus Fiber Line Performance and Economic, 2007 Engineering, Pulping & Environmental Conference

Please Note: This document will be available in PDF format in the "My Electronic Documents" link on the home page once your order has been completed. Please make sure you have the latest version of Acrobat Reader. Click on the Acrobat Reader icon to check for the latest version, it’s FREE. To print a hardcopy of a PDF file correctly you must have a postscript printer. If you are not sure if your printer is a postscript printer please refer to your owner’s manual.



Industrially made kraft pulps obtained by a modified cooking process may contain 60-75 mmol/kg of hexenuronic acids (HexAs), which represents 6-7.5 kappa units. HexAs do not react with oxygen and very little of it is actually removed across the oxygen delignification stage, causing low efficiencies in the range of 25-35%. In this study, a thorough economical evaluation of the ECF bleaching processes was carried out, having none and double-stage oxygen delignification, when applied to eucalyptus pulps of kappa varying in the range of 14-21. The bleaching processes included sequences containing specific stages for HexAs removal (Z, A/D and DHT). The results indicated that fiber lines already equipped with oxygen delignification will benefit from terminating the cook at higher kappa numbers (17.5-21) and proceeding with the sequence DHT(PO)DP. A more thorough economic analyses for a green field mill, using WinGEMS simulation, suggested that cooking to lower kappa numbers generated higher revenue, free cash value and IRR at $40/MWH power sale value. Oxygen delignification showed a slightly higher revenue and IRR. The sequence O/OD_HT(PO)DP at 14.1 kappa number had the highest IRR (14.28%) and A/D(PO)DP at 20.9 kappa number had the lowest IRR (13.52%).