AU536028B2 - The kinetic extruder: a dry pulverized solid material pump - Google Patents

Description

The Kinetic Extruder: A Dry Pulverized Solid Material Pump

Technical Field

This invention relates to industrial processes wherein solid material is fed to elevated pressure vessels from a low or atmospheric pressure environment. One such industrial process is coal gasification wherein pulverized or powdered coal is fed to an elevated pressure reactor vessel from an atmospheric pressure hopper or the like. More particularly, this invention relates to a dry pulverized solid material pump, or kinetic extruder, which is used to feed pulverized coal from an atmospheric hopper to a high pressure reactor vessel.

Background Art

In one prior arrangement, the slurry feed method, a liquid-solid mixture is pumped into the pressure vessel. Another arrangement is to load the material into a hopper, close and pressurize the hopper with gas, and then dump the material, along with the gas, into the pressure vessel. Such hatch feeding of material is not desirable. With both of these arrangements, the fluid (either gas or liquid) required to transport the solid material may not be required in the process and may be undesirable and require considerable effort to be removed before processing can begin. Other centrifugal devices have been proposed for delivering dry pulverized coal to a high pressure chamber. The present invention differs from this prior art in a number of areas. First, the present invention utilizes a pump having sprues with a control orifice at the high pressure end to maintain a stable plug of coal in the sprues. The dimensions of the orifice are determined by the size and permeability of the coal stock being fed. Without such a control orifice, coal flow cannot be established and maintained in a stable fashion. Second, the configuration of the spin-up zone and entrance region of the sprues of the present invention is such that the incoming coal always impinges on surfaces at an angle which insures that the coal does not stick and build up on these surfaces. Without this feature, regions of coal build up occur which either constrict the flow in the sprues or periodically flock off and block the sprues.

Also, the spin-up zone is vented to remove the carrier gas that is used to transport the incoming coal and to vent the gases which leak from the high pressure region back to the sprues under certain operating conditions.

Also in the present invention, the coal feed pipe is stationary. If the feed pipe were to rotate, as in some of the prior art devices, the resulting centrifugal forces would tend to concentrate the incoming coals on the inner surfaces of the feed pipe where they would easily build up and restrict or stop the incoming supply of coal.

Disclosure of Invention

The present invention provides a method and apparatus for the continuous feeding of pulverized or powdered material to a pressurized container which minimizes the need for a carrier fluid and eliminates venting from the pressurized hopper. This is achieved by the use of a rotor within the pressurized container through which the material outside the container is supplied. The material and gas mixture ar fed from an atmospheric feed hopper through a stationary feed pipe, then into a spin-up zone between the stationary inner hub and the rotatable driven rotor where it enters into sprues.

The spin-up zone is vented to allow the removal of excess gas from the material/gas mixture and a small amount of gas leakage from the high pressure vessel while maintaining a favorable pressure gradient in the feed pipe. It also maintains a favorable pressure gradient across the feed pipe which assures a reliable solid feed of material to the rotor.

Material is fed from the spin-up zone into a plurality of sprues on the rotating rotor. The transition to the sprues is designed to reduce or eliminate any ledges where coal may accumulate and agglomerate. The sprues include two sections. The first section has a relatively large cross sectional area reduction and is shaped to provide a constant angle between the radial acceleration vector and the wall. The second section of the sprues has a relatively small cross sectional area reduction and thus produces a relatively large share of the pressure in the coal plug traveling through the sprue. The sprues are designed to be easily replaceable.

Brief Description of Drawings

Figure 1 is a vertical sectional view, with portions shown diagrammatically, of a material feeder embodying this invention for feeding pulverized or powdered material to a pressurized container.

Figure 2 is an enlarged sectional view of the rotor illustrated in Figure 1 showing the details of the sprues.

Best Mode of Carrying Out the Invention

In the figures there is shown a fragmentary portion of a pressure vessel 2. This pressure vessel 2 may be used for some process, such as coal gasification. Coal gasification requires that the pressure within vessel 2 be maintained at elevated pressure, for example 600 psi. Such pressures have made the feeding of coal to the process difficult and expensive.

In the illustrated embodiment, the novel feeder of our invention is positioned within the pressure vessel 2. As will become apparent, the feeder may be located outside the pressure vessel 2, if desired, so long as the proper pressure is maintained on the feeder.

The material feeder of the present invention comprises a stationary feed tube 4 for receiving material from a feed hopper or the like (not shown). A normally open valve 6 may be positioned between the feed hopper and the stationary feed tube 4.

The downstream end 8 of the stationary feed tube contains a 90° exit in the feed tube to allow the solid material to enter the spin-up zone 10 in a radial direction.

The rotor 12 encloses the spin-up zone and embodies the sprues and includes the control orifices.

The spin-up zone 10 is maintained at a lower pressure than the feed hopper pressure by vent tube 14, which is connected to a suction device or any other well-known means for maintaining low pressure. The suction assists in maintaining a continuous feed of material to the rotor 12 and also vents excess gas from the solids.

The rotor 12 includes a hub portion 16 attached to the lower end of a hollow drive shaft 18. The hollow drive shaft 18 extends through the pressure vessel wall 2 and surrounds the stationary feed tube 4. The rotor is rotatably supported by bearings 20. Seal ring 22 is provided between the drive shaft 18 and the stationary housing 2 to prevent leakage of gas thereat. The feed tube 4 is supported inside the rotating shaft 18 by bearing 23 and leakage is prevented by seal 24. The cavity between the stationary feed tube and the drive shaft can be pressure filled with oil, if desired, to assure that bearing 23 is lubricated and remains free of contaminants.

Seal ring 26 is provided between the drive shaft 18 and ambient pressure.

The drive shaft 18 and attached rotor 12 are driven by a motor 28 connected to shaft 18 by suitable drive connecting means, such as gears 30.

The rotor 12 includes a plurality of radially extending sprues 32. The transition to the sprues is designed to reduce or eliminate any ledges where coal may accumulate and agglomerate. The sprues as shown are made in two sections. The first section 34, viewed sectionally, has a transition from a rectangular cross section shape to a circular cross sectional shape and provides a large reduction in area. The shape of the first section 34 is designed such that the curvature of the wall yields a constant angle between the radial acceleration vector and the wall. The second section 36 defines an aperture which is circular in cross sectional area and which has a relatively small area reduction in the radial direction.

The coal is discharged from the sprues 32 into control orifices 38, which are held into the rotor 12 by means of the orifice blocks 40. The retention blocks are designed to permit the high pressure existing in vessel 2 to equalize across the control orifice. The function of the control orifice is to meter the coal flow through the sprue.

The sprues and control orifices are designed to be easily replaceable.

Claims (1)

1. Claims

   1. Apparatus for feeding a pulverized material from a supply source to a container against a pressure differential comprising a feed pipe, an inner hub, and a rotor, said feed pipe connected to the inner hub and adapted to feed a pulverized material from a supply source to the inner hub, said rotor juxtapositioned to said inner hub and rotatably mounted and adapted to receive pulverized material from said inner hub.

   2. The apparatus for feeding a pulverized material as defined in claim 1, wherein said rotor includes a plurality of radial sprues, each sprue including a first and second section, said first and second section defining a passage for passage of said pulverized material.

   3. The apparatus for feeding a pulverized material as defined in claim 2, wherein said first section of said plurality of sprues defines a passage having a relatively large cross sectional area reduction in the radial direction and where said passage has a cross sectional area having a transition from a rectangular to a circular cross sectional shape.

   4. The apparatus for feeding a pulverized material as defined in claim 3, wherein said first section defines a passage having a curvature defining a constant angle between the radial acceleration vector and the wall of said passage.

   5. The apparatus for feeding a pulverized material as defined in claim 4, wherein said second section of said plurality of sprues defines a passage having a "relatively small cross sectional area reduction in the radial direction,

   6. The apparatus for feeding a pulverized material as defined in claim 5j including an isobaric control orifice at the radial end of each of said sprues. . The apparatus for feeding a pulverized material as defined in claim β, including means to remove excess fluid from the hub region.

   8. The apparatus for feeding a pulverized material as defined in claim 7, wherein said venting means is adapted to maintain a pressure difference between said feed pipe and said inner hub region.

   9. The apparatus for feeding a pulverized material as defined in claim 8, further defined as including means for spinning said rotor relative to said feed pipe and said inner hub.