Method for determining the degree of completion and pulp yield

In a method for monitoring and determining the degree of completion and pulp yield of a pulping or delignification reaction for a known quantity of starting wood of identified characteristics immersed and digesting in a known quantity of black liquor at a known black liquor to wood ratio, the improvement comprising:

• sampling the starting black liquor and measuring the dead load organic carbon content of the starting black liquor;
• determining the total carbon content in the known quantity of starting wood;
• sampling the black liquor during the pulping reaction;
• measuring the total organic carbon content of the sampled black liquor during the reaction;
• calculating the degree of completion of the pulping reaction and pulp yield from the sampled black liquor total organic carbon content measurement using a conservation of carbon mass mathematical model based upon conservation of carbon mass in the wood and black liquor during the reaction, said mathematical model including a conservation of mass equation in which the total organic carbon content in the sampled black liquor less any dead load organic carbon content measured in the starting black liquor substantially equals the total carbon content in the starting quantity of wood less the total carbon content in the of wood residue at the time of sampling the black liquor, said mathematical model providing the calculation of degree of completion and pulp yield based upon the sampled black liquor total organic carbon measurement without requiring sampling of the wood or pulp residue of the pulping or delignification reaction;
• controlling the pulping reaction in real time according to the calculated degree of completion and pulp yield of the pulping reaction;
• and terminating the pulping reaction when the reaction reaches the desired degree of completion and pulp yield predicted by the mathematical model based upon the sampled black liquor total organic carbon content measurement.