Institute of Gas Technology

William A Sandstrom

Jitendra G Patel

John R Bush

Mark J Khinkis

Paul B Tarman

A process for combusting sulfur and nitrogen containing carbonaceous materials in a two stage combustion process wherein sulfur and nitrogen containing carbonaceous materials and sulfur fixation agent particulates are introduced into a first combustion stage single fluidized bed having a density/size selective solids withdrawal conduit. The carbonaceous materials are combusted in the fluidized bed under substoichiometric oxygen conditions at temperatures of about 1600.degree. to about 2000.degree. F. producing ash and reducing gases forming a reducing region in a major portion of the single fluidized bed, the reducing gases comprising gaseous sulfur compounds. In a reducing region of the fluidized bed, the gaseous sulfur compounds are reacted with oxides of the sulfur fixation agent forming an intermediate solid metallic sulfur compound and nitrogen contained in the carbonaceous materials is converted to molecular nitrogen. The intermediate sulfur compound is reacted in an oxidizing region maintained at a base portion of the fluidized bed to form a stable, solid, environmentally acceptable sulfur containing compound which is withdrawn through the selective solids withdrawal conduit with agglomerated ash.

Two stage combustion

An apparatus for thermally and pneumatically treating granular solids to remove organic and inorganic chemical additives which are bonded to the granular solids or in admixture with them, to provide a purified granular solid product which is suitable for reuse, for example foundry sand for use in high strength molded cores, or for other productive uses, such as landfill. Granular solid feed material is preheated in a dilute phase zone of a fluidized bed, organic chemical additives are thermally oxidized in a dense phase zone of the fluidized bed, and remaining inorganic chemical additives are separated and removed from the granular solids in a contiguous pneumatic impaction zone. The purified granular solids are removed from the pneumatic impaction zone and organic and inorganic materials are elutriated from the fluidized bed and removed from the head space.

Apparatus for thermal and pneumatic treatment of granular solids

Granular solids are thermally and pneumatically treated to remove organic and inorganic chemical additives which are bonded to the granular solids or in admixture with them, to provide a purified granular solid product which is suitable for reuse, for example foundry sand for use in high strength molded cores, or for other productive uses, such as landfill. Granular solid feed material is preheated in a dilute phase zone of a fluidized bed, organic chemical additives are thermally oxidized in a dense phase zone of the fluidized bed, and remaining inorganic chemical additives are separated and removed from the granular solids in a contiguous pneumatic impaction zone. The purified granular solids are removed from the pneumatic impaction zone and organic and inorganic materials are elutriated from the fluidized bed and removed from the head space.

Process for thermal and pneumatic treatment of granular solids

An improved apparatus and process for the conversion of hydrocarbonaceous materials, such as coal, to more valuable gaseous products in a fluidized bed gasification reaction and efficient withdrawal of agglomerated ash from the fluidized bed is disclosed. The improvements are obtained by introducing an oxygen containing gas into the bottom of the fluidized bed through a separate conduit positioned within the center of a nozzle adapted to agglomerate and withdraw the ash from the bottom of the fluidized bed. The conduit extends above the constricted center portion of the nozzle and preferably terminates within and does not extend from the nozzle. In addition to improving ash agglomeration and withdrawal, the present invention prevents sintering and clinkering of the ash in the fluidized bed and permits the efficient recycle of fine material recovered from the product gases by contacting the fines in the fluidized bed with the oxygen as it emanates from the conduit positioned within the withdrawal nozzle. Finally, the present method of oxygen introduction permits the efficient recycle of a portion of the product gases to the reaction zone to increase the reducing properties of the hot product gas.

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Chicago, IL, United States of America

William A Sandstrom