Apparatus for fluidizing, degassing and pumping a suspension of fibrous cellulose material

• US 5,209,641 A
• Filed: 05/29/1991
• Issued: 05/11/1993
• Est. Priority Date: 03/29/1989
• Status: Expired due to Term

• Current Assignee: Kvaerner Pulping Technologies AB
• Original Assignee: Kamyr AB
• Inventors: Jansson, Ulf, Hoglund, Ronny
• Primary Examiner(s): Look, Edward K.
• Assistant Examiner(s): Lee, Michael S.
• Application Number:
  US07/707,053
• Time in Patent Office: 713 Days
• Field of Search: 415/188, 415/169.1, 415/169.2, 416/177, 416/179, 416/181, 416/182, 416/183, 416/203, 416/223 B
• US Class Current: 416/223.00B
• CPC Class Codes: D21D 5/26 De-aeration of paper stock
• CPC Class Codes: F04D 29/2288 for comminuting, mixing or separating
• CPC Class Codes: F04D 7/045 with means for comminuting, mixing stirring or otherwise treating
• CPC Class Codes: F05B 2210/132 Pumps with means for separating and evacuating the gaseous phase

Abstract

An apparatus for fluidizing, degassing and pumping a suspension of fibrous cellulose material is described which comprises a housing, a fluidizing rotor and an impeller of radial type, said housing having a cylindrical portion for the rotor, a portion for the impeller which is radially enlarged in relation to the cylindrical portion, a wall closing one end of the housing and a shaft rigidly connected to the impeller, an axial inlet for suspension being disposed at the cylindrical portion, and a radial outlet for suspension at the radially enlarged portion. The apparatus has also a degassing system for removing gas which collects in front of the impeller and comprising an opening in the impeller and the wall, the impeller having a hub, a partition and forward and rear blades. Furthermore, the impeller is provided with a concentric, circular inlet for the continuous supply of suspension to the rear blade space, the rear blades being arranged to exert a pump action on the suspension supplied to the apparatus.

Claims

1. An impeller for use in an apparatus for fluidizing, degassing and pumping a suspension of fibrous cellulose material, comprising:

a hub;

a wall means surrounding said hub; and

a means for exerting a pumping action on the suspension to increase the head acting thereon, said means comprising;

a plurality of forward blade means, said forward blade means disposed to extend from one side of said wall means and a plurality of rear blade means disposed to extend from said wall means on the opposite side thereof from said forward blade means,

and means defining an annular opening in said wall means to allow for continuously supplying suspension to said rear blade means to be pumped thereby, said rear blade means having an axial extension at a radial portion located radially outside said means defining said annular opening which is greater than the axial extension of the forward blade means located radially outside said means defining said annular opening, said means defining said annular opening comprising said wall means having an inner, concentric flange and an outer concentric ring which is located at a distance from the inner flange to define therebetween said annular opening.

2. An impeller as recited in claim 1 wherein the axial extension of the rear blade means is about 1.3-3.5 times greater than the axial extension of the forward blade means.

3. An impeller as recited in claim 1, wherein said inner flange comprises a peripheral edge which is located axially nearest the hub, and wherein the outer ring is displaced axially away from the hub in relation to the peripheral edge of the flange.

4. An impeller as recited in claim 1 wherein the forward and rear blade means are disposed in pairs opposite each other, the blade means in each pair being connected to each other by a transition portion in said annular opening, said transition portions forming the only interruptions around the opening.

5. An impeller as recited in claim 1 wherein facing surfaces of the ring and the flange are bevelled from axially above the hub and towards the hub, seen in the flow direction of the suspension from axially above the hub toward the hub, so that the opening is substantially conical.

6. An apparatus as recited in claim 1, wherein said rear blade means comprises an outer edge, said forward blade means comprises an outer edge, and said hub having a central axis, and wherein the outer edge of the rear blade means is located at a greater radial distance from the central axis than the outer edge of the forward blade means.

7. An impeller as recited in claim 1, wherein said hub has a central axis, and wherein the annular opening is located at a predetermined radial distance from the central axis so that the annular opening lies within the area of the suspension flowing in a direction radially from above the hub toward the hub and completely outside a central gas bubble produced by the gas present in the suspension.

8. An impeller as recited in claim 1 wherein said hub has a central axis, and wherein said opening with a radially inner region within the outer portion of the gas bubble produced by gas present in the suspension, said inner region forming said opening means in the impeller.

9. An impeller as recited in claim 1 wherein the impeller comprises a substantially radial disc which is rigidly connected to the rear blade means so that the rear blade space is closed on the same axial side of said wall means as the rear blade means, said disc having small openings for gas in the vicinity of the hub and being preferably disposed at an axial distance sufficient to define a space for said rear blade means.