Study On Novel Process Of Alkaline Pulping Of Eucalyptus Wood

Cold alkali impregnation and compression were used as pretreatment method,applied in alkaline pulping of eucalyptus wood.The new technology of cold alkali impregnation-compression-alkaline cooking was developed.The optimum conditions of cold alkali impregnation and compression were discussed.And,the influence of cooking conditions on the novel process of soda-AQ pulping and novel process of kraft pulping were studied.The effects of pretreatment conditions and cooking temperature on the pulp properties of two new pulping processes were studied,and the strength of the pulp was compared with traditional alkaline pulping.The results showed that the optimum conditions of alkali impregnation as follows:NaOH dosage 2%,time 2h,temperature 25?,liquor ratio 1:5.The pulp kappa number decreased significantly and pulp yield was higher when the pretreatment was under this condition.The best condition of the compression is:compression ratio 3:1,and the number of the compression is 1.Under this condition,the kappa number of the pulp was lower,the pulp fiber was longer,and maintain a high yield.The influence of pretreatment on subsequent kraft pulping and soda-AQ pulping was studied,and the suitable alkali charge,liquor ratio,cooking temperature and time at maximum temperature were explored on the new technology of cold alkali impregnation-compression-alkaline cooking.According to the experiment results,the pretreatment could reduce the kappa number of the pulp,and consequently improve the pulp yield on a conditiaon of lower alkali dosage,decreased cooking temperature and lower holding time.In the new pulping process,the influence of the cooking temperature on the mechanical properties of the pulp was studied and compared with that of conventional pulping.According to the experimental results,the pretreatment can improve the strength of the pulp under the same cooking temperature.By comparison,the pulp yield of novel process of soda-AQ pulping was increased by 1.34%than conventional kraft pulping,and the kappa number of them was the same,pulp physical properties was similar with or better than conventional kraft pulp.The effect of pretreatment alkali charge on pulp yield and mechanical properties were studied in the new soda-AQ pulping.Impregnated with alkaline charge increased from 2%to 4%,little changes on the mechanical properties of the pulp in the case of total alkali charge(including pretreatment and cooking)were the same,according to the experimental results.With the increase of impregnating alkali charge,residual alkali increases,the actual cost of the total alkali content was gradually reduced.But,the yield of the pulp was slightly lower in this condition.According to the pulp yield and kappa number,choose the impregnating conditions with 2%alkali charge.Finally,the optimum conditions were:using 2%alkali soaking conditions,time 2h,temperature 25?(room temperature),liquor ratio 1:5.Compression condition:compression ratio 3:1.The soda-AQ cooking conditions of the pretreated wood chips:the heating up time is 90min,the maximum temperature was 165?,the holding time was 60min,with 20%of alkaline charge,0.05%anthraquinone,liquor ratio 1:5.The kraft cooking conditions of the pretreated wood chips:the heating up time is 90min,the maximum temperature was 165 ?,the holding time was 60min,with 15%of alkaline charge,sulfidity 25%,liquor ratio 1:5.