Textiles: fluid treating apparatus – Machines – Liquid flowing
Reexamination Certificate
2000-03-13
2001-02-06
Coe, Philip R. (Department: 1746)
Textiles: fluid treating apparatus
Machines
Liquid flowing
C068S183000
Reexamination Certificate
active
06182478
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to an apparatus for cleaning a suspension, preferably a fiber mass suspension.
BACKGROUND OF THE INVENTION
When processing recycling paper, extra substances, such as dirt and printing ink, must be removed from the paper in order to provide a fiber mass usable for further processing. For this purpose, so-called flotation deinking is used rather generally, whereby fiberized and, in most cases, screened fiber mass is fed with air bubbles, which rise and carry impurities upwards in such a way that these can be removed from the surface of the fiber mass suspension. In practice, one aeration is not enough for cleaning the mass, but the known solutions generally utilize several sequential receptacles and different pumping and mixing solutions, trying to expose the suspension to several processes for providing a final result as clean as possible. A problem with such solutions is that the apparatus is complicated and requires separate pumps and tube systems as well as several receptacles. An additional problem with solutions of this kind consists in operating and maintenance costs caused by additional devices.
GB Patent 2 291 367 discloses a solution, in which a suspension is fed into a circular receptacle divided into sectors by means of partition walls and there is a funnel in the middle of the receptacle, into which impurities rising onto the surface of the sectors may flow over the edge of the funnel. The suspension is fed into one sector and it moves forward from the feeding sector into the next sector through openings in the lower portion of the partition walls and finally flows out from the last sector adjacent to the feeding sector. Each sector is fed with air and comprises a separate mixing device, by which the suspension within the sector is put in circulation. In practice, this solution corresponds to several sequential aeration receptacles, even though it functions without separate pumps moving suspension from one aeration space into another. In the solution, however, air feed devices and mixing devices shall be provided for each sequential sector. Finnish Patent Application 922/64 discloses, in turn, a solution, which corresponds to said GB solution and in which suspension is moved from one sector into another by means of so-called air-lift pumps. In other respects, however, the function corresponds to the solution of the GB publication.
SUMMARY OF THE INVENTION
The object of the present invention is to provide an apparatus for cleaning a suspension, preferably a fiber mass suspension, which enables a more efficient cleaning than the known solutions and which is easy to implement. The apparatus of the invention is characterized in that the partition wall between the two spaces is formed in such a way that the spaces are in communication with each other at the lower portion of the partition wall. Accordingly, the suspension may flow from one space into the other at the upper portion of the partition wall. Means for feeding air into the suspension are arranged to feed air only into an aeration space, which is one of said two spaces being in communication with each other. The suspension flows, under the influence of the air to be fed, in the aeration space upwards and, respectively, in the space on the other side of the partition wall downwards so that a spiral flow around the partition wall between said two spaces is created. The inlet channel and the outlet channel of the suspension are positioned such that the distance between them in the propagation direction of the suspension flow is as long as possible.
An essential idea of the invention is that a suspension, such as a fiber mass suspension, is fed into a receptacle for processing comprising at least one partition wall dividing the receptacle into at least two spaces. The suspension to be cleaned may flow from one space into the other below the partition wall and over the upper edge thereof, respectively. Another essential idea of the invention is that cleaning air is fed only into one of the two spaces being in communication with each other. The suspension to be cleaned is put in circulation in a cleaning receptacle by means of air bubbles fed for removing impurities in such a way that the part of the suspension which is bound by air bubbles and contains mainly impurities rises onto the surface of the receptacle, from where it can be easily removed. The cleaner suspension moves forward in the process and turns back to the aeration stage as a result of the vertical flow so that an essentially spiral flow is created. This flow propagates from the inlet of the suspension to the outlet thereof, while the degree or purity of the suspension increases all the time.
In accordance with a preferred embodiment of the invention, the aeration receptacle is divided into sequential parts by means of spacer plates in such a way that the spacer plates extend to the bottom of the receptacle. There are openings in the lower portion of a ring-shaped partition wall around the central part of the receptacle, through which openings the mass is allowed to flow from the receptacle spaces at the outer periphery into the central part. The mass can then flow over the upper edge of the partition wall around the central part and further into the outermost receptacle spaces of the receptacle.
An advantage of the invention is that a fiber mass can be aerated effectively at the same time as air bubbles cause the fiber mass or another suspension to flow between the spaces of a cleaning receptacle. This is because, when air is fed into one of the receptacle spaces communicating with each other, the suspension therein flows upwards and, respectively, the suspension in the other receptacle flows below a partition wall into an aeration space. Simultaneously, the suspension arrives, when rising upwards in the aeration space, at the upper portion of the receptacle and moves forward over the upper edge of the partition wall together with the flow. A froth is created by means of air and containing impurities, and which is easy to remove from the surface of the fiber mass suspension either according to overflow principles or by different mechanical removing means.
Simultaneously, the rest of the fiber mass suspension can be caused to flow downwards in the other receptacle space, and consequently, a spiral flow is provided around the partition wall. In this spiral flow the degree of purity increases all the time as the spiral propagates, until the suspension is finally discharged through the outlet channel of the suspension situated at a distance as long as possible from the inlet channel of the suspension. In this way, no separate pumps or circulation devices are required for the implementation of the solution according to the invention, but the air alone fed for aeration purposes causes a circulation and a sequential cleaning in many stages.
REFERENCES:
patent: 1055168 (1979-05-01), None
patent: 0 229 224 A2 (1987-07-01), None
patent: 922/64 (1969-01-01), None
patent: 2 291 367 (1996-01-01), None
Hautala Jouko
Heimonen Jukka
Hourula Ismo
Rajala Veli-Matti
Alston & Bird LLP
Coe Philip R.
Valmet Corporation
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