PROCESS AND SYSTEM FOR CALCINATION OF HIGH SOLIDS LIME MUD

摘要

The invention features methods and systems for calcining wet calcium carbonate lime mud produced in a re-causticizing manufacturing operation, for instance, Kraft pulp mill lime mud ("lime mud") and converting it to re-burned lime by (a) feeding wet lime mud obtained from a re-causticizing manufacturing process into a flash dryer and then feeding the dried lime mud into a bubbling fluid bed calciner thermally linked by moving media heat transfer (MMHT) utilizing solid particulate media to a circulating fluid bed combustor wherein the MMHT provides heat input for calcination and drying; (b) recycling the media being from said calciner to said combustor wherein said combustor receives mill WWTP sludge, or precipitated lignins, or biomass, or NCGs as fuels to re-heat the solid particulate media; and (c) recovering calcined "soft-burned" lime mud from the fluid bed calciner. Steam and heated boiler feed-water are also generated and exported to the mill's steam distribution and generation system as well as hot process water for use in the mill's boiler house and manufacturing operation. The system for calcining calcium carbonate lime mud produced from a re-causticizing manufacturing operation and converting it to re-burned lime comprises a calciner and a combustor linked by a moving media heat transfer MMHT system or apparatus. The MMHT system or apparatus thermally links separate fluid bed combustion (exothermic) and calcination (endothermic) stages. The system further comprises a flash dryer or spray dryer that utilizes exhausted heat from the calcination stage.