The Effect of Dead Load Chemicals in the Kraft Pulping and Recovery System, 2007 Engineering, Pulping & Environmental Conference

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The main dead load chemicals are sodium carbonate form incomplete conversion during causticizing, and sodium sulfate from low reduction efficiency in the recovery boiler, but thiosulfate and chloride are also potentially important. The difference between a low and high dead load operation may amount to as much as 125 kg/mtp. A 1% increase in causticizing efficiency reduces dead load by 6-7 kg/mtp while a 1% increase in reduction efficiency decreases dead load by 2-3 kg/mtp. Costs associated with dead load include that of increased internal energy use, greater chemical losses, reduced equipment capacity, and operating problems. The differences in energy use between a low and high dead load operation can be as much as 0.7 GJ/mtp. Capacity impacts are likely to be greatest at the evaporators, but the green and white liquor system and recovery boiler could also be impacted. Some guidelines for minimizing the effects of dead load are provided in the paper.