WO1996018564B1

WO1996018564B1 - Vertical-shaft airlock

Info

Publication number: WO1996018564B1
Application number: PCT/US1995/016324
Authority: WO
Filing date: 1995-12-14
Publication date: 1996-09-26

Abstract

An enclosed-rotor vertical-shaft rotary valve is used as an airlock to inject abrasive, fine, or sticky solids into pressurized air. The invention eliminates the effect of thermal expansion on the gap between the rotor and casing, thereby making it possible to obtain much smaller gaps than before. The smallness of the gaps makes it feasible to pump clean air into the gaps without interfering with the performance of the airlock. The clean air keeps dust-laden air from entering the gaps, which eliminates the erosion that has limited the usefulness of conventional rotary valves when handling abrasive powders. By the use of two vents and a dual-pressure purge-air system, the invention also greatly reduces the blowby of air into the entrance of the airlock, which has limited the usefulness of conventional rotary valves when handling very-small-particle powders. These benefits also accrue to the injection of sticky solids into pressurized fluids. The invention extends the pressure and temperature capability of airlocks, so they may be used to inject solids into fluids at lower instead of higher pressure, and so they may be used with fluids other than air.

Claims

AMENDED CLAIMS

[received by the International Bureau on 8 July 1996 (08.07.96); original claims 1 and 4 amended; remaining claims unchanged (2 pages)] 1. A rotary valve, comprising:

a) a rotor assembly rotatable by a driver to cause material to be transferred from an inlet side to an outlet side of the rotary valve, the rotor assembly including a rotor coupled to a shaft which rotates about an axis when driven by the driver, the rotor including:

an outer tube,

an inner tube,

a plurality of radial blades, wherein the outer tube, inner tube, and radial blades are all of substantially the same height and the radial blades extend between the outer and inner tubes and are connected thereto to define a plurality of pockets between the outer and inner tubes, the pockets being open at a top and a bottom of the rotor, and

a hub connected to the inner tube and coupled to the shaft;

b) a casing assembly for supporting the rotor assembly, and including an inlet for allowing the material to enter the pockets of the rotor assembly and an outlet for allowing the material to exit the rotor assembly, the casing assembly including:

an upper cap disposed at a top of the casing assembly that contains an opening for allowing the material to enter the pockets of the rotor assembly, a shaft opening, and a wiper assembly that removes material from the blades as the blades pass by the inlet opening,

a sleeve coupled to the upper cap, the sleeve being shorter than the rotor, and

- 42 - a lower cap disposed at the bottom of the casing assembly that contains an opening for allowing the material in the pockets of the rotor assembly to exit,

wherein the lower surface of the upper cap conforms to the shape of the top of the rotor and the upper surface of the lower cap conforms to the shape of the bottom of the rotor;

c) a plurality of springs coupling the lower cap to the sleeve that serve to compress the rotor between the caps; and

d) a bearing assembly for rotatably supporting the rotor inside the casing assembly, comprising an upper bearing which separates the upper cap from the top of the rotor by a minimum gap, a lower bearing which separates the lower cap from the bottom of the rotor by a minimum gap, and bearing grooves in which the bearings are disposed.

2. The valve of claim 1 wherein the bearings are located at a diameter greater than the outside diameter of the rotor pockets.

3. The valve of claim 1 wherein the bearings are ball bearings.

4. The valve of claim 3 wherein the contact angle between the bearing balls and the bearing grooves is 90° relative to thrust loads, and is sufficiently high to prevent the bearing grooves from riding up on the bearing balls due to radial loads.

5. The valve of claim 1 wherein the rotor assembly comprises a first shaft extending from the top of the valve and a second shaft extending from the bottom of the lower cap, wherein each shaft is coupled to the casing by a first bearing located at the cap and a second bearing mounted in a yoke that is firmly attached to the casing, wherein the second bearings' mounting positions are a significant distance from the cap.

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