The Research And Practice Of Reed Displacement Cooking

Displacement cooking is a pulping method through the black liquor recycling to achieve saving energy and reducing consumption, improving the quality of the pulp, conforming to the theory of depth to take off the lignin. Since the technology is promoted, it has been widely used in the world, especially DDST M displacement cooking technology of wood and bamboo run on multiple projects very successfully. Reed for papermaking material is better than the other’s, it is close to hardwood fibers. If it can be successfully applied displacement cooking technology, it will play a "in the contemporary benefits, and ever- lasting" important role on the shortage of wood resources of our country.The study showed the main research difficulty that the success application of reeds displacement cooking technology is: the reed after thermal softening will make the compactness of cooking pot change, causing the pot non- uniform flow resistance, uniformity affect cooking; Softening reed pieces and mixed cells in the material will influence the speed of displacement and circulation, and even lead to paste mesh. And reed charging, fluid replacement will result in slower and the extension of cooking cycle.The reeds using displacement cooking process is feasible. The results of the current production practice show that the optimum process conditions of cooking is following: Cooking time is 4.5h(warm filling is 0.5h, hot filling and first cooking is 0.5h, secondary cooking is 2h, cooling displacement is 0.6h, blowing is 0.7h, flushing plate is 0.2h); The temperature of cooking:the first cooking 130℃, the secondary cooking 150℃(warm black liquor120~130℃, hot black liquor140~150℃, hot white liquor140~150℃); the displacement speed is 4times/h, the alkali consumption is about 19% and so on. The stock properties is: Kvalue number is 13.6-14.6K, the breaking length is 5310 m, the folding strength is over 38 times, The steam consumption of tons pulp is 1.0~1.3t/bdt, and with the improvement of the system it still has a larger decline in space.1. Controling the reed material quality and improving the content of the reeds piece and qualified rate of cutting reeds. It can reduce paste sieve plate, improve the uniformity with the pot and pancharged and control the generation of drift and cooking uneven phenomenon;2. Controling the warm filling and hot filling and the ratio of fil ing alkaline. The warm filling and the hot filling use that the liquid enters from the above and comes out from the following; and among the circulation, the liquid enters from up and down. It can avoid ran alkali and ensure uniform solution concentration in pan. The ratio of filling alkalineof warm filling and hot fil ing is 15:85.3. Controling the pressure difference of the inside and outside digester sieve plate. The reed softened has influence to the filter velocity and the flow rate fell by around 20%. But as long as you can conctrol the pressure difference, the cycle is not a momentary traffic impact among the displacement, the cooking liquor to filter speed will not be affected and sieve plate won’t more be pasted.4. We can control the hydraulic control valve to adjust the corresponding temperature and achieve the goal of control flow deviation.5. The warm and hot black liquor need constant temperature heating system and the white liquid need to configure the white liquid heating system to ensure that the liquid temperature of the digester conform to technical requirements. The pump and the elevation of the system of the pulp’s blowing should be fully considered to avoid the problem of feeding is not clean.And specified in this research institute of reed can be used in the direction of displacement cooking technology is right, this article tries to restore the problems in the project development process and production practice, and hopes that it can further promote the development of reed fiber pulping technology.