Method and Apparatus for Post-Oxidation of Carbon-Containing Gasification Products

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This invention relates to a method and an apparatus for the post-oxidation (further processing) of carbon-rich residual products from the gasification of solid fuels like coal. It combines a primary gasifier with a specially designed fixed-bed gasifier (with a moving oxidation bed located below the primary unit). The approach ensures complete oxidation of leftover carbon materials by optimizing the flow and mixing of reagents and gases, ultimately producing deposable ash and reducing unburned carbon in waste.

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• Waste management at coal gasification plants to produce safer, landfill-ready ash.
• Integration in coal-to-gas or coal-to-liquid facilities to improve carbon conversion efficiency.
• Industrial processes generating carbon-rich residues needing complete oxidation and safe disposal.
• Facilities aiming to decrease carbon emissions from solid fuel gasification.
• Retrofitting existing fluidized-bed gasifiers for improved waste residue handling.

BenefitsContent extracted from patent full text and abstract with AI.

• Achieves complete oxidation of carbonaceous residues, reducing hazardous waste and allowing for safer disposal.
• Improves overall efficiency of the gasification process by maximizing carbon conversion.
• Minimizes CO2 emissions by preventing incomplete combustion and avoiding carbon-rich landfill materials.
• Reduces operational challenges like slagging and unwanted channel flows in fixed-bed systems.
• Enables use of fuels with higher ash content and requires less pre-treatment of feedstocks.

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Patent Abstract

The invention relates to a process and to an apparatus for postoxidation of carbonaceous gasification products from a primary gasifier by means of gasification in fluidized beds via arrangement of a fixed bed gasifier having a moving postoxidation bed beneath the primary gasifier. The process is characterized in that a) the reaction space of the primary gasifier is connected directly or via a connecting tube to the reaction space of a fixed bed gasifier in an uninterrupted manner and the two form a common pressure space, wherein the connection between the primary gasifier and fixed bed gasifier has a smaller cross section compared to the reaction spaces of the primary gasifier and fixed bed gasifier, b) the moving postoxidation bed in the fixed bed gasifier is formed from a lower cylindrical portion and an upper narrowing portion, the upper end of which reaches no further than the lower end of the connection to the primary gasifier, c) the gases that ascend upward out of the moving postoxidation bed (comprising raw postoxidation gases and further gases) are introduced into the lower end of the connection to the primary gasifier at flow rates that are at most sufficiently high that the primary gasification bottom products that form the moving postoxidation bed can fall from above out of the primary gasifier through the connection into the moving postoxidation bed, d) the gases that enter the primary gasifier in the upward direction from the upper end of the connection are introduced at flow rates that are at least sufficiently high that the primary gasification bottom products are fluidized above the upper end of the connection, e) the secondary gasifying agents are introduced into the moving postoxidation bed from below distributed over the cross section of the reaction space of the fixed bed gasifier, f) the size of the cross section of the moving postoxidation bed is sufficiently high that flow through the moving postoxidation bed is regular (and not in the form of channels), g) and the amount of the secondary gasifying agent introduced into the moving postoxidation bed in the upward direction and the amount of the postoxidation bottom products drawn off in the downward direction from the moving postoxidation bed are adjusted such that the postoxidation is complete beneath the upper end of the cylindrical portion of the moving bed.