Thermodynamics of the Kraft Causticizing Reaction

苛化反应在大多数造纸工业使用的硫酸盐法制浆过程的化学回收循环中起着至关重要的作用。硫酸盐回收操作包括浓缩废纸浆废液、燃烧以回收能量和化学品、熔体形成、熔体溶解、苛化、白液澄清、碳酸钙浓缩和泥浆洗涤。这项建议是PI工作的一部分，目的是改进卡夫工艺的许多方面，试图使其更易于控制。改进的过程控制应该减少过程的资本和运营成本，并提高生产率。苛化将碳酸钠和硫化钠的水溶液(绿液)转化为苛性溶液(白液)和石灰泥(S)。产品的苛性溶液用于消化过程中对木材和其他植物物质进行脱木素。拟议研究的目的是获得实验数据并估计验证焦化反应热力学模型所需的参数。问题是确定何时达到均衡，并改进接近均衡的方法。焦散效率在平衡状态下最大。如果能提高焦化效率，生产率就会提高，运营和资本成本就会降低。这一提议的目的是为均衡转换定义一个表达式。这些数据将直接适用于通过硫酸盐和苏打工艺将木材和其他植物物质加工成纸浆。此外，这些数据可以应用于使用苛化反应的化学过程；例如，烧碱的生产。

The causticizing reaction plays a crucial role in the chemical recovery cycle of the Kraft pulping process used by most of the paper industry. Kraft recovery operations include concentration of spent pulping liquor, burning to recover energy and chemicals, smelt formation, smelt dissolution, causticizing, white liquor clarification, calcium carbonate thickening, and mud washing. This proposal is part of the PI's work to improve the many aspects of the Kraft process in an attempt to make it more amenable to control. Improved process control should decrease capital and operating cost for the process and increase productivity. Causticizing converts an aqueous solution of sodium carbonate and sodium sulfide (green liquor) into caustic solution (white liquor) and lime mud (CaCO (s)). The product caustic solution is used in the digestion process to delignify wood and other vegetable matter. The objective of the proposed research is to obtain experimental data and estimate parameters required to verify a thermodynamic model of the causticizing reaction. The problem is to determine when equilibrium has been attained and to improve the approach to equilibrium. The causticizing efficiency is a maximum at equilibrium. Increases in productivity and decreased operating and captital costs would result if the causticizing efficiency can be improved. This proposal is aimed at defining an expression for the equilibrium conversion. The data will be directly applicable to processing wood and other vegetable matter into pulp by the Kraft and Soda processes. In addition, the data can be applied to chemical processes wherever causticizing reactions are used; for example, the production of caustic soda.