A key component of the control strategy is BTU based liquor firing. As opposed to liquor volume or liquor solids flow to the boiler, BTU based firing uses the heat release of the liquor as the most representative value of long-term production rate. The advantage of this method is that heat release can be stabilized relative to production rates. This allows a stable and constant oxidation process to occur on the smelt bed. Once stability is achieved, carryover and emissions are reduced and the boiler can be pushed closer to maximum production rates.
Variations in heat release rate are controlled based on the amount of air being consumed in the furnace. The air consumed by burning liquor is continuously calculated and used to adjust liquor flow such that proper heat is maintained. Consumed air control provides the advantages of uniform burning, better oxygen control, and overall furnace stability. This optimization module functions with either oscillating liquor guns or stationary firing.
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