Study On The Technique Of Black Liquor Pretreatment And The Kinetic Of Deliginification For Fast Growing Eucalyptus Kraft Pulp Cooking

In this thesis, it studied the factors of black liquor pretreatment, which affected on the pulp quality, the kinetic in black liquor pretreatment stage and the mechanism of fast growing eucalyptus deliginification. The result of the research showed:With the pretreatment temperature rising, and time at maximum temperature extending, and Na2S, NaOH and lignin in black liquor increasing, the yield, K number and viscosity of pulp decreasing. The increased concentration of NaOH have passive affected the cooking delignification. The maximum temperature improved, and the times extend at maximum temperature and the concentration of Na2S and the concentration of lignin in black liquor increased can enhance the selectivity of the fast growing eucalyptus cooking delignification. According to the study, the pretreatment parameters were temperature 145℃, time 60min, NaOH charge lower 5g/l, and Na2S 16.55g/.After pretreatent by NaOH, Na2S and H2O, the product pulp of fast growing eucalyptus by the later sulphate cooking had some changes on the ratio of the K number vs the viscosity that were 0.01477, 0.01355, 0.01549,and lower than the general cooking 0.01815.The delignin reaction and the lignin concentration was first-order reaction. According to the lgL-t, could compute the reaction rate constant K:1.0197X 10-3, 1.8248 × 10-3, 3.4504 ×10-3, at various temperatures.It concluded that almost the temperature raised 10℃, the reaction rate increased two times. The temperature is the key factor affected the delignification. The delignification chemistry reactions order about concentration of NaOH and Na2S to fast growing eucalyptus pretreatment phase was assumed to be 0.17 and 0.1.The rising temperature of black liquor pretreatment, the increasing concentration of NaOH and black liquor made against the selectivity of delignification in the pretreatment phase, the increasing concentration of Na2S in pretreatment black liquor was not important to lignin removal and the yield in the pretreatment phased.The kinetic of sulphate cooking about fast growing eucalyptus' pretreament told that the delignification in the initial phase was obsolete. There were the bulk phase and the residual phase. There delignification reaction was assumed to be first-order reaction. The activation energies of the bulk and residual phases were 83.6 and 104.45.The delignification reactions order of the bulk phase and the residual phase about concentration of NaOH was assumed to be 0.604 and 0.77. The delignification reactions order of the bulk phase and the residual phase about concentration of Na2S was assumed to be 0.038 and zero.