Gravity-flow solids blending

Claim 2

In a gravity-flow particulate solids blender having an elevated main storage vessel, a multiplicity of solids withdrawal downcomers connected at their top ends in open communication at preselected points with said storage vessel, and a common collector receiving solids discharged from the bottom ends of said downcomers, individual traps interposed between the bottom ends of said downcomers and said common collector retaining solids emerging from said downcomers in static repose during blender standby, and means directing a regulated solids-conveying gas stream through solids held up in said traps and thence into said collector effecting controlled drawoff of solids from said downcomers during bleNder operation.

Claim 3

Apparatus according to claim 1 wherein said means directing a regulated solids-conveying gas stream through solids held up in said traps is a vacuum source.

Claim 4

Apparatus according to claim 2 wherein the gas inlet sides of said means directing a regulated solids-conveying gas stream through solids held up in said traps are provided with flow restrictors such as valves or orifices.

Claim 5

Apparatus according to claim 2 provided with a regulable gas bypass valve connected to maintain a preselected level of vacuum effectively applied by said vacuum source to said means directing a regulated solids-conveying gas stream through solids held up in said traps.

Claim 6

Apparatus according to claim 1 wherein said means directing a regulated solids-conveying gas stream through solids held up in said traps is a pressure jet disposed with discharge opening in the range of about 1 inch- 2 inches from the face of the slope of said solids adjacent said collector measured during repose.

Claim 7

Apparatus according to claim 5 wherein said pressure jet is mounted generally perpendicularly adjustable of said face of said solids adjacent said collector.

Claim 8

Apparatus according to claim 1 wherein said means directing a regulated solids-conveying gas stream through solids held up in said traps comprises a multiplicity of pressure jets, each individually serving a single trap, a common manifold supplied with solids-conveying gas from a pressure source, individual gas flow regulation valves interposed between said manifold and said pressure jets, and a common gas pressure control valve interposed between said pressure source and said manifold.

Claim 9

In a process for the gravity-flow blending of solids comprising, in sequence, confining a mass of the heterogeneous solids in an elevating column, withdrawing as separate fractions from said mass in a generally vertical direction substantially equal amounts of said solids per unit time simultaneously from a multiplicity of different regions of said mass, and combining said separate fractions in a common collector to produce a solids blend having improved homogeneity of composition, the improvement consisting of entrapping said solids in said separate fractions at the discharge ends of their courses before combining in said common collector to thereby retain the solids of said fractions in static repose during blending standby and directing a regulated solids-conveying gas stream through said solids at said discharge ends of said courses effecting controlled drawoff of solids from said separate fractions into said common collector during blending operation.

Claim 10

In a process for the gravity-flow blending of solids comprising, in sequence, confining a mass of the heterogeneous solids in an elevating column, withdrawing as separate fractions from said mass in a generally vertical direction substantially equal amounts of said solids per unit time simultaneously from a multiplicity of different regions of said mass, and combining said separate fractions in a common collector to produce a solids blend having improved homogeneity of composition, the improvement consisting of entrapping said solids in said separate fractions at the discharge ends of their courses before combining in said common collector to thereby retain the solids of said fractions in static repose during blending standby and directing a regulated solids-conveying gas stream through said solids at said discharge ends of said courses effecting controlled drawoff of solids from said separate fractions into said common collector during blending operation.