Mixer, mixing method, and method of producing gypsum board
A pin-type slurry mixer where the foam is not injected into the mixing chamber at all — instead the foam feed port sits on the annular wall just upstream of the slurry outlet, or on the hollow connector below it, so the foam bypasses the impeller.
- Assignee
- Yoshino Gypsum Co Ltd
- Inventors
- Wataru Nakamura, Yuichi Hirooka
- Jurisdiction
- European Patent Office
- Filed
- 2004-05-21
- Published
- 2006-03-22
- Priority
- 2004-05-21
Foam collapse inside the mixer is a chronic loss in gypsum board manufacturing: soap-stabilised bubbles are sheared and destroyed by the same impeller that homogenises the stucco slurry. The plant then compensates by pushing more foam upstream, which raises soap consumption and, at high line speeds, still fails to give a uniform void distribution.
This patent moves the foam injection point downstream of the impeller entirely.
- 01The mixer is a flat, circular housing with an annular wall and a rotary disc inside.
- 02The slurry leaves through an outlet port on the annular wall and travels through a hollow connector to a substantially vertical slurry delivery conduit.
- 03The foam feed port is placed either on the annular wall on the upstream side of the outlet port (relative to the disc rotation), or on the hollow connector below the mixer body.
- 04In both configurations the foam meets the slurry after the disc, so it is not subjected to the agitation impact of the mixer — reducing foam loss and letting the plant increase slurry flow rate without over-dosing soap.
| Parameter | Value | Source |
|---|---|---|
| Mixer geometry | flattened circular housing with annular wall + rotary disc | claim 1 |
| Foam injection location A | annular wall, upstream of the slurry outlet port in rotation direction | claim 1 |
| Foam injection location B | hollow connector section between outlet port and vertical delivery conduit | claim 1 |
| Design intent | foam meets slurry at or downstream of the outlet — bypassing impeller shear | abstract |
- 01A retrofit of an existing pin mixer to relocate the foam port is often much cheaper than replacing the whole mixer.
- 02Because foam collapse is reduced, dose-response curves for soap change: expect to recalibrate foam draw setpoints after the modification.
- 03Line-speed increases enabled by this geometry cascade through the kiln — the kiln profile has to be reviewed at the same time.
The present invention provides a mixer and a mixing method which enable stable supply of slurry at a high flow rate with foam being uniformly mixed therein, and which enable reduction in consumption of foam to be fed to the slurry. The mixer (10) has a housing (20), a rotary disc (32), a slurry outlet port (45), a slurry delivery conduit (46) and a hollow connector section (47). A foam feeding port (41) is disposed in a predetermined position of an annular wall or the hollow connector section. The foam feeding port feeds the foam to the slurry, immediately before the slurry enters the slurry outlet port, or feeds the foam to the slurry in the hollow connector section. The slurry and the foam mix with each other at the slurry outlet port or on its downstream side. The foam is not substantially subjected to agitation impact of the mixer and a quantity of loss of the foam is reduced. The foam is uniformly mixed with the slurry even when the flow rate of slurry is increased, and therefore, the production rate of gypsum boards can be increased.
A mixer comprising a flattened and circular housing provided with an annular wall on its periphery; a rotary disc located in the housing to rotate in a predetermined rotational direction; a slurry outlet port opening on said annular wall to discharge from the housing, gypsum slurry mixed in the housing; a hollow connector section with an open end connected to said slurry outlet port and another open end connected to a substantially vertical and cylindrical slurry delivery conduit; and a foam feeding port for feeding foam to the gypsum slurry, wherein said foam feeding port is provided on the annular wall on an upstream side of the slurry outlet port in the rotational direction so as to feed the foam to the gypsum slurry immediately before the gypsum slurry enters said slurry outlet port, or provided on said hollow connector section so as to feed the foam to the gypsum slurry flowing in the hollow connector section.
Further claims, drawings, prosecution history and legal status: see the official record.
- [1]EP 1 637 302 A1 — Mixer, mixing method, and method of producing gypsum board — Google Patents · 2006-03-22