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Home » Volume 27, 2012 » Issue No. 5
CHEMICAL PULPING
Further insights into extended-impregnation kraft cooking of birch
Helena Wedin, Juha Fiskari, Kari Kovasin, Martin Ragnar, and Mikael E. Lindström
Abstract
Extended-impregnation kraft cooking (EIC) is a cooking concept that combines prolonged impregnation with modern improved modified kraft cooking. In the current investigation, the EIC cooking of birch was studied in relation to conventional kraft cooking. Specifically, the reject content and carbohydrate yield retention when terminating at a high cooking kappa number were examined. It was demonstrated that EIC cooking reduced the reject content. Unexpectedly, a high cooking kappa number led to no increase in carbohydrate yield, possibly due to the chemical composition of birch wood and the EIC cook lab procedure. A large amount of liquor was withdrawn after the impregnation, resulting in a loss of dissolved xylan that otherwise could have redeposited on the fibres and contributed to the carbohydrate yield. The effects of EIC cooking on extended oxygen delignification, bleaching chemical requirement in a D(OP)DP sequence, and strength properties were also examined. Compared with conventional lab cooking, EIC cooking resulted in a lower bleaching chemical requirement and similar strength properties.
Keywords
Bleaching, Carbohydrates, Oxygen delignification, Physical properties, Pulp, Reject, Xylans, Yield
Pages
890-899
Full text
PDF Document N2012-27-05-p890-899-Wedin.pdf (463KB)
Further insights into extended-impregnation kraft cooking of birch (2012-27-05-p890-899-Wedin.pdf)