Control Of Stickies Deposition On Four Kinds Of Paper Machine By Cleaning Enzyme

The recent rapid developments of biotechnologies have driven the pulping and papermaking industry to adapt novel enzymes in its production to increase production efficiency and improve paper product quality in a sustainable green manner.In this thesis the applications of an advanced enzyme technology for stickies control—Cleanase^TM were systematically investigated in the OCC recycling paper production process of the four most common grades of packaging papers and paperboards,which were corrugated medium,cardboard paper,kraft liner cardboard paper and tube & core papers.First,major efforts were made to determine the chemical nature of the main components of the stickies deposited on the paper machine.It was demonstrated that all the four types of stickies contain polyacrylate?PA?,ethylene vinyl acetate copolymers?EVA?,polyvinyl acetate?PVAc?,fatty acid ester,silicone,styrene acrylic copolymers.However,the proportions of the various components in the stickies in different paper types differ from each other and vary with the wastepaper furnishes.In addition,stickies deposits were also found to have non-tacky and non-extractable components,including cellulose,hemicellulose,lignin and inorganic minerals such as calcium carbonate and silicates.Based on the above analytical information,appropriate enzymes were first selected and examined in the lab screening phase.Enzyme formulations containing the various proportion of the selected types of enzymes were then made and tested for stickies control efficiency with “standard” OCC furnishes.Then the pre-screened Cleanase^TM products were further tested on-site with mill OCC pulps,and the optimal product was determined for large scale trial.Mill trials of 2-4 weeks were run to evaluate the effects of the Cleanase^TM product on the stickies through comprehensive comparison of changes in the production with and without the Cleanase^TM application.The application of cleaning enzyme in corrugated medium,cardboard paper,kraft liner cardboard paper and tube & core paper machines had produced good application effects,which were mainly reflected in the following aspects: effectively reducing the deposition of colloidal substances in each node of the whole paper machine system,purifying the paper machine system;improving the running condition of the paper machine,such as increasing the speed and output of the paper machine,reducing the number and time of paper breaking of the paper machine,and improving the speed and output of the paper machine;improving the dewatering rate and operation rate of the web part of the paper machine;reducing the production cost and increasing the profit margin;reducing the viscosity of the adhesive and the deposition on the surface of the drying cylinder,guide roller and scraper and increasing the service life of the spare parts and the efficiency of the drying cylinder to reduce the steam energy consumption;improving the paper quality and reducing the amounts of holes,black spots and other paper diseases formed by the adhesive sticking to the paper wool and falling on the paper web.The improvement of rewinding and paper breaking could reduce the workload of workers.Although clean enzyme has a positive effect on the deposition control of mucilage as a whole,the control effect on mucilage varied with paper type.In this study,by comparing the operating parameters of the paper machine and the economic benefits of the clean enzyme,we can see that the control effect of the clean enzyme on the stickies in the production process of corrugated paper was the best,followed by T-paper and the control effect of the clean enzyme on the stickies in the production process of kraft paper was the worst.After using the clean enzyme to control the deposition of stickies,the comprehensive operation parameters of the tube paper machine had been greatly improved,which showed that the control effect of biological enzyme method on stickies is better than that of chemical methods.Moreover the production cost for one ton paper can be reduced by 4.8 RMB as a result of the application of cleaning enzyme.