Study On Preparation Of 8 MTPD Chlorine Dioxide And Bleaching Of Bagasse Pulp

Chlorine dioxide as the most important agent of ECF bleaching process has been widely used in the bleaching of bagasse pulp by means of its strong oxidizing property. Brightness of the pulp improved and yellowing as well as wastewater loading decreased after bleaching. The thesis aimed at technical research of chlorine dioxide preparation and application research in the bleaching of bagasse pulp, such as the physical index and fiber form distribution of the bleached bagasse pulp and wastewater loading, etc.1. The preparation technology of chlorine dioxide and influence factors were analyzed. The optimum preparation technological conditions as follows:the acidity of the generator liquor was 8.0 to 8.2 N; the sodium chlorate concentration was 2.2 to 2.5 M; the solid content was 15% to 25%(by volume); the pressure of the generator was 120 mmHg, and the reaction temperature was 71 ? to 73 ?. In these conditions, the state of the reaction was ideal.2. Effects of the circulation in generator to the steam, power, consumption of the raw material and reaction efficiency were analyzed according to the production experiments. The raw materials could make sure uniform mixing when the circulation in the generator at 400 m3/h to 650 m3/h, and Reynolds number 8000 to 13325. The circulation volume controlled by frequency conversion circulation pump, then the energy consumption effectively reduced and the yield of chlorine dioxide enhanced.3. Physical index of the bagasse pulp and optimum bleaching conditions were studied in the bleaching of chlorine dioxide. The brightness of the pulp could reach to 85% ISO when the bleaching temperature at 45 ?, pH 3 to 4,45 min for Do period, and at 80 ?, pH 4 to 5,180 min for the D1 period.4. Routine indexes of D0 and D1 period bleaching wastewater were superior to traditional CEH bleaching, especially the reduction of AOX, relative to one ton of pulp. AOX was 0.56 kg/t in Do period, and 0.12 kg/t in D1 period, but 6 to 7kg/t in CEH bleaching produces, which was nine times to chlorine dioxide bleaching.