Patent EA-000328-B1 (EA)
Title: A method and apparatus for maintaining solids in suspension in a liquid
IPC: B01F33/40
Filed: 1996-09-24
Abstract: 1. A container (10) for fluids, having means (15) for driving the fluid to move within the container whereby to encourage circulation, and means for guiding the fluid to circulate, in which the said driving means (15) is located at a point higher than the lowermost part (12) in the container, and the guide means comprise or include a lower guide surface (20) shaped such as to guide the fluid in its circulatory motion towards the said driving means (15), characterized in that the container wall (11) is so shaped as wholly to define the boundary of the circulatory path (S2) of a fluid within the container (10) with no surface discontinuities in the path (S2) of the fluid from the said driving means (15) around the entire boundary of the circulatory path defined by the container walls (11). 2. A container according to Claim 1 or Claim 2, characterized in that the said lower guide surface (20) defines at least part of a cusp, which is substantially symmetrical about a median plane of the container. 3. A container according to Claim 2, characterized in that the said cusp defined by the lower guide surface (20) is symmetrical about any vertical median plane passing through the apex of the cusp. 4. A container according to Claim 2, or Claim 3 characterized in that the container (10) is elongate, and the said cusp extends generally centrally along its length. 5. A container according to any preceding Claim, having means for maintaining solids in suspension in a liquid by causing forced circulation thereof with the container stationary, characterized in that an upper part of the container wall is so shaped as to guide the circulatory motion of the fluid to follow a downwardly curved path (S2) so as to maintain the solids in suspension. 6. A container according to Claim 5, characterized in that the container wall is shaped with a continuous curve from the upper part to a lower part of the container so as to cause the circulatory motion of the fluid to follow a smoothly-curved circulatory path (32) within the container (10). 7. A container according to any preceding Claim, characterised in that the upper wall of the container (10) is formed as a smoothly continuously curved surface such as, in use, to divert an upward flow of fluid in the central region of the container outwardly from the central region and downwardly in a smooth circulatory movement. 8. A container according to Claim 7, characterized in that it is elongate and the said fluid circulation-driving means extends centrally along the length of the container, the upper wall thereof being shaped to divert a central upward fluid flow outwardly into opposite container halves on either side of a central median plane of the container. 9. A container according to any preceding Claim, characterized in that the container is elongate and has a longitudinal median plane, an inlet opening being provided at one end and an outlet opening being provided on the other, the inlet and outlet openings being located at opposite sides of the said longitudinal median plane. 10. A method of maintaining a fluid suspension within a container (10) by creating a circulatory motion of fluid within the container by fluid driving means (15) acting to cause the fluid to move within the container, the said fluid driving means (15) being located at a height within the container spaced above the lowermost point (12) of the circulatory motion, characterized in that the fluid is guided within the container (10) in a smoothly continuous curve from the said lowermost point (12) to the said drive means by flow guide surfaces forming part of the outer wall of the container (10) and defining part of the circulatory flow path (S2) within the container, the entirety of the circulatory flow path (S2) within the container being defined by the outer wall (11) of the container. 11. A method according to Claim 10, in which the circulatory flow path defined within the container includes a downward curve defined by the shape of an upper portion of the container wall having a convex curvature towards the interior of the container, the fluid flow being driven by the said fluid driving means to follow the said curvature. 12. A method according to Claim 10 or Claim 11, characterized in that the fluid driving means comprise a gas (9) introduced into the interior of the container so that it bubbles up through the suspension. 13. A method according to Claim 11, characterized in that the fluid flow is constrained to follow a continuously curving path by the shape of the container wall with no discontinuities from an upper part of the container (10) to the part at which the gas (9) is introduced. 14. A method according to any of Claims 9 to 12, characterized in that the container is elongate with a constant cross-section and the gas (9) is introduced at a plurality of introduction points (15) spaced along the container (10), the suspension being caused to flow through the container (10), from one end to the other as well as being driven and constrained to follow the said circulatory path within the container (10). 15. A method according to Claim 13, characterized in that the container (10) has a plane of symmetry and the gas (9) is introduced substantially in the plane of symmetry so as to set up circulatory flows of suspension in opposite directional senses within the container (10) on either side of the plane of symmetry. 16. An installation comprising a plurality of containers according to any of Claims 1 to 9, in an arrangement with means (104) interconnecting the outlet of one container to the inlet of a successive container (102).