The main components of paper are cellulose and hemicellulose. The plant fibers for papermaking include wood fiber and non-wood fiber. The main compositions of plant fibers are cellulose, hemicellulose, and lignin. Paper pulping is a process of removing lignin as much as possible and retaining cellulose and hemicellulose. Wood fiber is a high-quality papermaking material and it has a great advantage in the paper industry. With the rapid development of industry, the contradiction between supply and demand of wood, the search for non-wood fiber paper raw material is a realistic and urgent problem to be solved.
Rice straw is a cheap non-wood fiber material for papermaking. Since the fiber length ratio is large, which is good for interweaving and bonding between fibers, and increase the smoothness and transparency of the paper. Bleached straw pulp can be applied into a common culture paper making, also can be used with wood pulp to make high-quality printing paper and writing paper.
Rice straw is an annual herbaceous stem plant with high hemicellulose content, low lignin content, short and fine fibers, high content of non-fibrous cells, especially thin wall cell content is high, so the water filtration performance of the straw pulp is poor, and the ash content of pulp is high. The straw section is solid and difficult to cook. Therefore, the study of straw cooking process will help to further optimize the straw cooking process.
As we all know, rice straw pulp making usually adopts displacement cooking, so the pulping equipment includes displacement digester system, blow tank, vacuum drum washer, twin roll press, single screw press, and etc.
According to the data, the content of SiO2 of straw is much higher than that of other fiber materials. For common soda cooking: Generally, the SiO2 content of various fibers is different, the wood pulp black liquor solids are less than 1%; the sputum and bagasse black liquor is 5% to 8%, and the straw black liquor is as high as about 20%.
components of rice straw
After the dry and wet material preparation, the grass pieces are transported through the screw conveyor of the wet preparation section to straw metering section of the continuous cooking section. After being metered and then enter into the heating screw conveyor, and the pre-heat treated grass pieces are subsequently fed into the thickening feeder. The meter controls the amount of feed by the rotation speed, and the heating screw conveyor is introduced into the low-pressure steam, which is beneficial to the softening of the grass piece and the immersion of the liquid medicine, thereby achieving the purpose of pre-steaming.