Evaluation of Hydropyrolysis as an Energy-Saving Alternative to the Tomlinson Furnace. Task 3. Chemical Causes of Increased Pulp Yield

摘要

The yield-enhancing effect was found to be the result of the presence of small but significant levels of polysulfide and calcium ions. Polysulfide ions are generated during the causticization of the hydropyrolysis filtrate and is the result of a partial-air oxidation of Na sub 2 S that occurs under conditions existing during the causticizing process. In the presence of residual organics, calcium ions are complexed to form soluble calcium-organo complexes which allow for a carryover of a significant amount of calcium into the final cooking liquor. The presence of both ions in the final cooking liquor allow for pulp yield increases through the formation of alkali-stable aldonic acid end-groups which protect carbohydrates from alkaline-degradation. (ERA citation 08:054160)