Determining The Heat Of Reaction Of Kraft Pulping

Kraft pulping is accompanied by a gradual but significant exothermic heat of reaction. Most of the exothermic heat results from the neutralization of carboxylic acids formed by the degradation of carbohydrates. The exothermic heat was measured in a laboratory digester for both softwood and hardwood cooks. The measured values of the heats of reaction at a final H factor of 1200 were -93′31 kcal per kilogram of wood dissolved for softwood and -148′28 kcal per kilogram of wood dissolved for hardwood. These results were used in a spreadsheet model to estimate the energy balance and the maximum temperature rise to be expected in batch kraft digesters.