Study of Causticizing Kinetics and Design of Pressurized Reactor

苛化动力学研究及加压反应釜设计

• 批准号: 8917595
• 负责人: Gopal Krishnagopalan
• 金额: $ 13.65万
• 依托单位: Auburn University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1990
• 资助国家: 美国
• 起止时间: 1990-03-01 至 1993-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8917595&HistoricalAwards=false
• 关键词: Study; Causticizing; Kinetics; Design; Pressurized

Wood contains mainly cellulose, hemicellulose, lignin and small quantities of extractives. The primary purpose of chemical pulping is to remove the lignin which binds the fibers in the wood and liberate the cellulosic fibers. Kraft pulping is the major chemical pulping process used by the pulp and paper industry for the liberation of cellulosic fibers from the structural matrix of wood. The kraft process uses sodium hydroxide and sodium sulfide as effective chemicals for pulping. The chemicals along with wood chips are charged into a pressure vessel (digester), and the contents are brought to the reaction temperature at a preset rate. After the digestion the chips are disintegrated by being "blown" into a tank and then sent for further processing. The pulp resulting from digestion and disintegration of the wood chips is washed thoroughly in a counter current system of washers to produce spent liquor or "black liquor". This black liquor is sent through a recovery cycle which involves concentration of black liquor to 60-70% solids by evaporation and burning of the concentrated black liquor in a furnace. In the furnace the organic materials are completely burned to generate steam, the sodium-sulfur compounds are reduced to sodium sulfide, and the remainder of the inorganic components are converted to sodium carbonate. The inorganic compounds are withdrawn as smelt from the furnace, dissolved, and then sent to a causticizing section to regenerate sodium hydroxide by treating with lime. The clarified liquor from the causticizing section, containing mainly sodium hydroxide, sodium sulfide and small quantities of unconverted sodium carbonate, is called "white liquor" and is recycled back as the cooking liquor to the digester. One of the major reasons for the success of the kraft pulping process is the established, efficient chemical recovery process whereby more than 95% of the chemicals used in the cooking process can be recovered. Uniformity of composition of the regenerated cooking liquor is a key factor in the production of uniform quality pulp and therefore in the economy of operation of the entire process. The purpose of this research project is to study the causticizing process and develop a reliable kinetic model for the system, with the ultimate goal to improve the chemical recovery operation in the kraft pulping process. A semi-batch reactor already designed and fabricated, capable of operating at higher pressures and equipped to monitor the composition of the main reaction products continuously will be used. A novel in-situ and on-line sampling and analysis system will be used to measure the feed green liquor concentration. Experimental equilibrium data will be supplemented by theoretical calculations. A tubular flow reactor equipped with analyzers to test the green liquor and reaction products will be designed. Such a reactor will also allow necessary adjustment for lime addition and result in uniform white liquor feed to the digester which in turn will allow stable digester operation, improved pulp quality and higher productivity.

木材主要含有纤维素、半纤维素、木质素和 少量提取物。 的主要目的 化学制浆是为了去除木质素， 木材中的纤维并释放纤维素纤维。 卡夫 制浆是纸浆使用的主要化学制浆工艺 和造纸工业的纤维素纤维的解放 从木材的结构矩阵。 牛皮纸工艺使用 氢氧化钠和硫化钠作为有效的化学品， 制浆。 化学品沿着木屑被装入 压力容器（蒸煮器），内容物被带到 反应温度以预定速率进行。 后 消化芯片被分解被“吹”成一个 罐，然后送去进一步处理。 所产生的纸浆 从木片的消化和分解中得到的 在洗涤机的逆流系统中彻底地生产 废液或“黑液”。 这种黑液被送到 通过一个回收循环， 液体60-70%的固体通过蒸发和燃烧的 在熔炉中浓缩的黑液。 在熔炉里， 有机材料完全燃烧产生蒸汽， 钠-硫化合物被还原成硫化钠， 其余的无机成分转化为钠 碳酸盐。 无机化合物作为熔融物被提取 从炉子里出来，溶解，然后送到苛化炉， 段，通过用石灰处理来再生氢氧化钠。 来自苛化工段的澄清液，含有 主要是氢氧化钠、硫化钠和少量 未转化的碳酸钠被称为“白色液”， 作为蒸煮液再循环回蒸煮器。 一 硫酸盐法制浆成功的主要原因 该工艺是一种成熟、高效的化学品回收工艺， 该过程中使用的95%以上的化学品 烹饪过程可以恢复。 成分均匀性 再生蒸煮液的回收率是影响蒸煮液回收率的关键因素。 生产质量均匀的纸浆，因此， 整个过程的经济性。 本研究项目的目的是研究 苛化过程，并建立可靠的动力学模型， 该系统的最终目标是改善化学品 硫酸盐法制浆工艺中的回收操作。 半间歇 反应堆已经设计和制造，能够运行 在更高的压力和装备，以监测组成， 将连续使用主要反应产物。 一种新型 将使用现场和在线取样和分析系统 以测量进料绿色液体浓度。 实验 平衡数据将补充理论 计算。 装有分析仪的管式流动反应器 为了测试绿色液体和反应产物， 设计了 这样的反应堆也将允许必要的调整 用于石灰添加，并导致均匀的白色液体进料， 该消化器又将允许稳定消化器 操作，改善纸浆质量和更高的生产率。