Liquid purification or separation – Processes – Separating
Reexamination Certificate
2000-06-28
2001-04-24
Popovics, Robert (Department: 1723)
Liquid purification or separation
Processes
Separating
C210S783000, C210S386000, C210S400000, C162S056000, C162S308000, C162S313000, C100S118000, C100S120000
Reexamination Certificate
active
06221265
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method for concentrating liquid-drenched material, particularly for de-watering fiber suspensions, in which the material is formed into a string embraced by a straining cloth and rolled while covered with that cloth. The present invention also relates to apparatus suitable for carrying out this method.
BACKGROUND OF THE INVENTION
A method and an apparatus for concentrating liquid-drenched material by rolling a string of that material while the string is embraced by an endless straining cloth belt are known, for instance, from U.S. Pat. No. 4,017,398. Apparatus of this type which are known are encumbered with certain drawbacks. For instance, a single straining cloth belt which embraces a material string has the tendency to rupture at the edge regions of the string when rolling at high pressure, and generally has a width which is more than twice the breadth of the rolled material string, resulting in large space requirements.
An object of the present invention is to provide a novel method and novel apparatus with which the aforesaid drawbacks are avoided at least to a substantial extent.
SUMMARY OF THE INVENTION
In accordance with the present invention, this and other objects have now been realized by the invention of a method for the concentration of a dilute material by forming the dilute material into a concentrated layer having a predetermined width, the method comprising enclosing the dilute material between a first straining belt having a first width which is insufficient to completely enclose the concentrated layer and including a pair of longitudinal edges and a center portion, and a second straining belt having a second width which is insufficient to completely enclose the concentrated layer, and including a pair of longitudinal edges, moving the first and second straining belts through first and second endless paths, the first width being greater than the second width, causing the pair of longitudinal edges of the first straining belt to overlap the pair of longitudinal edges of the second straining belt in an initial concentration stage, unfolding the pair of longitudinal edges of the first straining belt, and further compressing the concentrated layer against the first straining belt in a further concentration stage. In a preferred embodiment, the dilute material comprises a fiber suspension.
In accordance with one embodiment of the method of the present invention, the further compressing of the concentrated layer comprises compressing the concentrated layer between the first straining belt and a third straining belt having a third width and moving in a third endless path, the third width being greater than the second width.
In accordance with another embodiment of the method of the present invention, causing of the pair of longitudinal edges of the first straining belt to overlap the pair of longitudinal edges of the second straining belt comprises folding the central portion of the first straining belt over a first transverse folding edge having a first end and a second end, and folding each of the pair of longitudinal edges of the first straining belt over a second folding edge extending obliquely forward and outward in the direction of movement of the first straining belt and over a third folding edge extending obliquely forward and inward in the direction of movement of the first straining belt, whereby the pair of longitudinal edges of the first straining belt are folded over the first and third folding edges first inwardly over the central portion of the first straining belt and then parallel to the center portion of the first straining belt.
In accordance with another embodiment of the method of the present invention, unfolding of the pair of longitudinal edges of the first straining belt comprises folding the pair of longitudinal edges of the first straining belt outward and rearward around a third folding edge and a second folding edge and folding the central portion of the first straining belt back over a first folding edge.
In accordance with the present invention, apparatus has also been devised for the concentration of dilute material by forming the dilute material into a concentrated layer having a predetermined width, the apparatus comprising a first straining belt having a first width which is insufficient to completely enclose the concentrated layer, and a pair of longitudinal edges and a central portion, and having a first endless path, a second straining belt having a second width which is insufficient to completely enclose the concentrated layer, and a pair of longitudinally extending edges, and having a second endless path, the first width being greater than the second width, enclosing means for causing the longitudinal edges of the first straining belt to be folded over the longitudinal edges of the second straining belt whereby the first and second straining belts enclose the concentrated layer in an initial concentration stage, and secondary concentration means comprising means for unfolding the longitudinal edges of the first straining belt whereby the concentrated layer is further compressed against the first straining belt in a further concentration stage. Preferably, the dilute material comprises a fiber suspension.
In accordance with one embodiment of the apparatus of the present invention, the apparatus includes a third straining belt having a third width and a third endless path, the third width being greater than the second width, and the third straining belt disposed for compressing the concentrated layer between the first straining belt and the third straining belt in the further concentration stage.
In accordance with the present invention a method has been devised in which at least a terminating part of the concentration process effected by rolling is carried out with the string of material located between outwardly spread, single sheets of straining cloth, and wherein
for the purpose of enclosing the string of material there is used two belts of straining cloth, each travelling in a respective endless path, and each having a width which alone is insufficient to fully enclose the string of material;
the string is enclosed by a narrow belt and a broader belt of straining cloth, and the longitudinally extending edge portions of the broader web are caused to overlap the longitudinally extending edge portions of the narrower belt; and wherein
at least the broader web is spread out to form a single straining cloth sheet subsequent to the initial stage of the concentration process, and is also used during the remainder of said concentration process.
The present inventive method places no great strain on the straining cloth belts, and enables the material to be concentrated at high roll pressures, since the terminating concentration process is carried out with the string of material located between outwardly spread, single sheets of cloth. Only a relatively small amount of space is required, since the broader belt can have a width which is substantially smaller than the circumference of the rolled string.
According to the present invention, apparatus suitable for carrying out the aforesaid method while achieving the advantages afforded thereby includes a first stage through which the material is transported in enclosure means during initial concentration of the material to form a string of material and which is comprised of two separately advanced endless belts of straining cloth, and a second stage in which the material is finally concentrated by rolling the string of material as it is transported between two outwardly spread belts of straining material that move in two endless paths, wherein the enclosure means is formed by a narrower and a broader belt of straining cloth, each having a width which alone is insufficient to form said enclosure means, and wherein at least the broader belt also extends through the second stage and, in an outwardly spread state, also forms one of the transport belts used in this stage of the process.
REFERENCES:
patent: 4017398 (1977-04-01), Hart
Lerner David Littenberg Krumholz & Mentlik LLP
Popovics Robert
Valmet Fibertech AB
LandOfFree
Method and device for concentrating liquid-drenched material does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and device for concentrating liquid-drenched material, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and device for concentrating liquid-drenched material will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2523621