Institute of Gas Technology

John W Loeding

Frank C Schora

Jitendra G Patel

An improved method for feeding caking coal particles to a fluidized bed gasifier, without prior pretreatment, is disclosed. The coal particles are entrained in a gaseous stream and injected directly into the bottom of the fluidized bed around the outer perimeter thereof at a plurality of points and at a predetermined high velocity, such that the coal particles are shock heated and charred.

Method for feeding caking coal particles to a gasifier

A process for converting a finely divided carbonaceous material, particularly coal, to a fuel gas. A finely divided or pulverized carbonaceous feed material, such as coal, is pretreated at a temperature of about 700.degree. - 800.degree. F in order to destroy the caking properties of a caking coal feed in a fluidized pretreatment zone, or, alternatively to dry a non-caking coal feed. The pretreated coal is passed from a pretreatment zone to a gasification zone wherein the carbonaceous feed material or coal is maintained as a fluid bed at selected conditions for converting the pretreated material to ash and a gaseous mixture. During the pretreatment of the feed material, hot off gases are formed and the hot off gases, which generally comprise steam, tars, oils, and carbonaceous fines, are passed from the pretreatment zone to the underside of the fluid bed in the gasification zone. The steam contained in the off gases is reacted with the coal in the fluidized bed in the gasification zone for converting the coal feed material to ash and the fuel gas product. The off gases also provide heat for maintaining the desired temperature conditions in the gasification zone. The tars and oils in the off gases are substantially destroyed during passage upwardly through the fluidized bed in the gasification zone. The fines in the off gases are converted by the gasification reaction in the gasification zone to form a part of the fuel gas and the ash. The fuel gas is withdrawn from the upper portion of the gasification zone and ash is withdrawn from the bottom of the gasification zone.

Coal pretreatment and gasification process

A fluidized bed of material retained in a vessel receives a high velocity gas stream through a venturi orifice and passage to assist in the agglomeration of ash particles. The particles form a semi-fixed bed within the passage upstream from the venturi orifice. The particular dimensions of the semi-fixed bed are dependent, in part, upon the orifice size of the venturi. An iris valve defining the orifice permits adjustment of the cross-sectional area of the orifice thereby controls the velocity of the gas stream through the venturi.

Growing community of inventors

Naperville, IL, United States of America

John W Loeding