The Parameters Optimization Of Reed Ethanol Counter-current Cooking And Pulp Bleaching Reaserch

With the increasing demands for environmental protection,the environmental regulations are more strict,the existing pulp is facing tough challenges.The solvent pulping has aroused great interest of the paper workers,ethanol pulp has made substantial progress in North America.Ethanol slurry of the same kind of material is comparable with the kraft pulp.Ethanol can be the simplest way to be recycled back into use,and a variety of high value-added products can be recycled,bring about significant social and environmental benefits.However,the shortcomings of the ethanol pulping are the high temperature,high pressure and wash difficulties.This article adopts three-stage countercurrent cooking method,to optimize the cooking conditions and the ECF bleaching process of ethanol pulp,focus on the latter.For one-stage cooking method:the ethanol concentration is 50%,H202 dosage is 1.5%,liquid ratio 1:8,the time of heat preservation is 3h,cooking temperature 165?,the yield of crude pulp and fine pulp are 68.04%and 58.69%,kappa number 45.1.For two-stage cooking:the first stage uses fresh ingredients and the second cooking waste liquid,the ethanol concentration is 50%,H2O2 dosage is 1.5%,liquid ratio 1:8,the cooking temperature is 165?,the time of heat preservation is 3h;The second stage adopts the first stage pulp and the recovery ethanol,the ethanol concentration is 50%,H2O2 dosage is 1.5%,liquid ratio is 1:8,the cooking temperature is 165 ?,the time of heat preservation is 3h,the yield of crude pulp and fine pulp are 55.22%and 44.73%,kappa number 19.5;For three-stage cooking:The first stage uses fresh ingredients and the second cooking waste liquid,the ethanol concentration is 50%,H2O2 dosage is 1.5%,liquid ratio is 1:8,cooking temperature 165?,the time of heat preservation is 2h;The second stage adopts the first stage pulp and and the third cooking waste liquid,ethanol concentration is 50%,liquid ratio is 1:8,the cooking temperature is 140?,the time of heat preservation is 1h;The third stage adopts the second stage pulp and the recovery ethanol,ethanol concentration is 50%,liquid ratio is 1:8,the cooking temperature is 140? for lh.The yield of crude pulp and fine pulp are 57.03%and 53.20%,kappa number 35.3.Adopts Op-D-E-P bleaching sequence bleaching,focus on the oxygen delignification role and the dioxide part of the process parameters of the chlorine bleaching process,the use of response surface analysis of the Minitab software to design and optimization.The hydrogen peroxide dosage,temperature and oxygen pressure of oxygen delignification process parameters have been optimized;the chlorine dioxide dosage,final pH and time of chlorine dioxide bleaching process parameters have been optimized.In addition,the use of single-factor experimental design for hydrogen peroxide bleaching,to optimize the hydrogen peroxide dosage.The use of response surface analysis of the Minitab software analysis:after oxygen delignification,the whiteness reached to 50.9%ISO,the optimal process parameters were:hydrogen peroxide dosage 0.75%,temperature 95?,oxygen pressure 0.6Mpa,time 60min,sodium silicate 3.0%,magnesium sulfate 0.5%,sodium hydroxide 3.0%;after the chlorine dioxide bleaching,the whiteness reached to 73.5%ISO,the optimal process parameters were:chlorine dioxide dosage 1.7%,final pH=3,time 240min,temperature70?.Using single factor experimental design,after the hydrogen peroxide bleaching,the whiteness reached to 82.5%ISO,the optimal process parameters were:hydrogen peroxide dosage0.5%,temperature 90 ?,time 90min,pH value 11,EDTA 0.5%,silicate sodium 3.0%,magnesium sulfate 0.5%,sodium hydroxide3.0%.The pulp concentration in the reaction environment was 10%.