Process and system for producing commercial quality carbon dioxide from recausticizing process calcium carbonates

Abstract

The invention features methods and systems for recovering carbon dioxide, for producing commercial quality carbon dioxide (CO) of 90% to +99% purity using, wet calcium carbonate lime mud produced in a recausticizing process that also produces caustic soda, for instance, Kraft paper pulp mill lime mud (a.k.a., 'lime mud') as a feedstock to a multi-stage lime mud calcination process. This process may be fueled with low, or negative cost 'carbon-neutral' fuels such as waste water treatment plant (WWTP) sludge, biomass, precipitated lignins, coal, or other low cost solid fuels. High reactivity, high-quality calcined lime mud (a.k.a. re-burned lime, or calcine), required in the Kraft paper pulp mill's recausticizing process is also produced, and superheated high pressure steam and hot boiler feed-water is generated and exported to the mill's steam distribution and generation system as well as hot process water for use in the mill's manufacturing operation. The system for calcining calcium carbonate lime mud produced from a recausticizing manufacturing operation and converting it to calcined lime mud and COcomprises 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 with a solid particulate media. The system further comprises a flash dryer or spray dryer that utilizes exhausted enthalpy from the calcination stage.