Transfer pipe system

Claim 1

A transfer pipe system for moving particulate bed material from the reaction chamber of a relatively low pressure fluid bed unit at a first elevation to a relatively high pressure secondary reaction chamber at a lower elevation, comprising an inclined discharge pipe extending downwardly from the fluidized bed region of said reaction chamber, a substantially vertical transfer pipe connected to said discharge pipe and having gravity feed connection to said secondary reaction chamber, gas injection means spaced along said vertical transfer pipe to introduce fluidizing gas into said transfer pipe, so that a substantial quantity of the particulate material therein is maintained in a fluidized state, valve control means positioned in said transfer pipe system to control the flow of particulate material under the influence of gravity from said vertical transfer pipe into said gravity feed connection for delivery to said secondary reaction chamber; a vertical standpipe extending upwardly from the junction of said discharge pipe with said vertical transfer pipe to an elevation above the bed level in said fluid bed unit and a vent pipe connecting said standpipe with the freeboard region of said fluid bed unit thereby routing most of the fluidizing gas provided to said transfer pipe system directly to said freeboard region rather than through said discharge pipe so that flow of particulate material through said discharge pipe is not impeded by gas flow from said vertical transfer pipe.