Process and system for producing commercial quality carbon dioxide from high solids lime mud

摘要

The invention features methods and systems for producing commercial quality carbon dioxide (CO2) of 90% to +99% purity using, wet calcium carbonate lime mud produced in a manufacturing operation, for instance, Kraft 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 waste water treatment plant (WWTP), sludge biomass, precipitated lignins, coal, or other low cost solid fuels. High reactivity “soft-burned” lime product (“calcine”) required in the mill's chemical recovery circuit is also produced, and steam and heated 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 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 and CO2 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 with a solid particulate media. The system further comprises a flash dryer or spray dryer that utilizes exhausted heat from the calcination stage.

主权项

1. A method for calcining calcium carbonate lime mud from a Kraft pulp and paper mill and converting it to carbon dioxide and reburned lime comprising:
(a) providing wet lime mud sufficiently near a bubbling fluid bed calciner and a spray dryer or flash dryer such that the calciner and flash dryer or spray dryer operate in counter/current gas/solids flow wherein exiting calciner gases substantially dry the wet lime mud and the resulting dry lime mud is fed to the calciner; (b) feeding substantially dry lime mud to the fluid bed calciner wherein the fluid bed calciner is thermally linked by moving media heat transfer (MMHT) to a circulating fluid bed combustor by a heat transfer media wherein said media moves between said calciner and said combustor wherein MMHT provides heat input for calcination; (c) removing substantially all ash from the heat transfer media; (d) recycling the heat transfer media from said calciner to said combustor wherein said combustor receives one or more fuels selected from the group consisting of Kraft pulp and paper mill sludge, biomass, precipitated lignins and NCGs and producing combustion products; (e) recovering excess energy from the process of d) generating superheated high pressure steam; (f) recovering carbon dioxide of 90% to +99% purity and calcined lime mud from the fluid bed calciner; and (g) exporting the superheated high pressure steam to the Kraft pulp and paper mill.