JPS607757B2 - Paper making machine stock screen device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates generally to papermaking technology, and more particularly to a new and improved papermaking machine stock screening apparatus capable of achieving substantially constant acceptance rates. It is.

Stock screen devices are used in the papermaking process to help clean the stock before it enters the headbox and is dewatered to form a web.

In one preferred arrangement, the stock screen is conventionally tubular in shape, the stock is directed against the inner surface of the tubular screen, and the accepted stock passes through the screen, but the bundled fibers, Reject stock, including particles, dust, knots, etc., does not pass through the screen and is removed through the reject passageway. Typically, the feed sample is pumped inside the screen and the paper If the stock flows outwardly through the screen by sorting action, the slurry stock will enter at one end of the tubular screen, the rejects will be discharged from the pond end of the screen, while the accepts will be received into an annular chamber around the outer periphery of the screen. An example of such a structure is disclosed in U.S. Patent No. 4.
It is described in the specification of No. 11179. Described herein is a generally horizontally disposed stock screen assembly in which the perforated screen, often referred to as a basket, is arranged concentrically with the surrounding housing or casing wall; For this reason, the chamber that receives acceptance from the screen has a completely constant cross-sectional area over the entire length of the screen. Since the flow rate or volume increases from the point of the housing furthest from the accept stock outlet and the accept chamber is of constant volume, the flow rate of the accept slurry is naturally accelerated. In addition to removing unacceptable particulates, screening of fibrous papermaking slurry stock reduces fibrous clumping. Areas of low velocity encourage concentration to increase. When fiber concentrations are high, low velocity flow zones result in inefficient screening. A follow-up attempt to alleviate the drawbacks of stagnation and low-speed zones is US Pat. Nos. 3,680,696 and 372, in which the acceptance chamber has a spiral design
No. 64 OI is mentioned. However, such designs are expensive to manufacture and, although intended to accelerate towards the exit to remove the mass from the screen, reduce pulsation in the acceptance chamber around the screen's periphery, or reduce the flow if the flow is slow or slow. It is not our intention to eliminate areas. An important object of the present invention is to provide a new and improved papermaking screen apparatus which overcomes the inconveniences, shortcomings, inefficiencies, shortcomings and problems inherent in prior art apparatus and is capable of achieving substantially constant accept stock rates. It's about doing.

Another object of the invention is to provide a new and improved papermaking system which is comparable in price to conventional equipment in which the screen and housing are concentric, but which achieves new and improved results at substantially constant accept stock speeds. Our goal is to supply screen equipment.

That is, the present invention provides a screen comprising an elongated cylindrical tubular screen and an elongated cylindrical wall extending in spaced relation to the outer periphery of the screen and defining an acceptance chamber about the screen. an enclosing housing; means for supplying slurry stock to said screen; and means operative within said screen to promote good slurry stock movement through the walls of said screen to said acceptance chamber; , outlet means for the accepted stock guided from the accept chamber through the cylindrical wall of the housing, and ejection means for receiving the stock waste that has not passed through the screen wall but has been removed by the screen, the stock entering the head box; In a papermaking machine stock screen apparatus for processing a paper machine stock screen, the longitudinal axis of the screen is centered relative to the longitudinal axis of the cylindrical housing wall, so that the acceptance chamber is a chamber with a minimum eccentric distance of the screen relative to the housing wall. area to the chamber area of maximum offset D distance of the screen relative to the cylindrical housing wall, the screen is adapted to expand substantially uniformly in volume on opposite sides of the screen, and the accept stock exit means arranged to receive good slurry stock from said chamber section of greatest eccentric distance, as a result of which the volume of said receiving chamber expands from said minimum eccentric distance zone to said greatest eccentric distance zone; , a good, substantially pulsation-free slurry stock velocity from said screen to said exit means;
It is characterized in that a substantially uniform and good slurry-like stock flow increase is obtained to the outlet means.

While various alterations and modifications may be made without departing from the spirit and scope of novel concepts embodied in the specification, other objects, features and advantages of the invention will be apparent from the following description in conjunction with the accompanying drawings: It will become clear from the description of the specific example.

1 is a detailed longitudinal cross-sectional view of a conformal figure of a papermaking stock screen embodying the principles of the present invention; FIG. 2 is a detailed view taken along line 0-Ro of FIG. This is a vertical cross section.

As shown in the drawings, a paper machine screen device embodying the invention includes an elongated cylindrical screen 5 having a barrier 7 throughout its effective length.

The closure part 7 is designed to pass through a good slurry-like stock and remove unacceptable fibers, fibers, and foreign matter, such as dust clumps, bundled fibers, excessive fine particles, etc., without allowing them to pass through. Round holes, through holes, or slits in an array. The housing 8 surrounds the screen 5 and has an elongated cylindrical wall extending in spaced relation to the screen periphery to define an acceptance chamber 10 around the screen periphery. At opposite ends, the housing 8 has end walls 11 and 12, respectively. A supply chamber 13 is defined in the screen 5 between the end wall 11 and the adjacently spaced ends of the screen 5. This supply chamber 13 communicates into the screen 5, but is separated from the accept chamber 10 by a partition wall 14 extending radially from the screen machine to the housing 8. Feed inlet 15 receives papermaking slurry stock from a suitable source, indicated by arrow 17, and discharges it tangentially into feed chamber 13 through feed port 18. Such centrifugal feeding of the stock is carried out in the same centrifugal direction from the supply chamber 13 into the screen 5, and the stock is treated on the screen by suitable means operating within the screen, and a good slurry stock is passed through the screen. Encourage movement through the wall to the first room.
In this case, said means include a plurality of axially extending foils 19 which are arranged to rotate within the screen and driven by any suitable means 21 on a rotating shaft 20' lying on the axis of the screen 5. do. End wall 12
On the other hand, at the edges of the screen 5 at related positions spaced apart in the cross-line direction, the paper waste that does not pass through the screen 5 is deposited in the ejection chamber between the edge 12 and the adjacent spaced edges of the screen 5. 22 and is separated from the receiving chamber by a radially extending annular partition wall 23 between the screen end and the housing wall 9.

The means for evacuation from the reject chamber 22 includes an outlet 24 leading to a reject passageway or conduit 25 . The accepted stock outlet means are in the housing wall 9 and include an outlet 27 leading to an outlet pipe 28 suitable for connection in the usual manner with a paper machine headbox. For best results, the acceptance outlet 27 should occupy a position approximately aligned with the central longitudinal area of the screen 5. Furthermore, the outlet 27 has a substantially funnel-like shape that faces in the direction of connection with the pipe 28 for drinking water. Screen 5 and housing wall 9 are used to obtain a constant good slurry stock velocity with substantially no pulsations from the screen to the outlet and to obtain a substantially uniform good slurry stock flow rate increase up to the outlet 27. A new and improved relationship is given.

i.e. from the chamber area with the smallest eccentric spacing of the screen relative to the housing wall (i.e. the lower part in FIGS. 1 and 2) to the chamber area with the largest eccentric spacing relative to the cylindrical housing wall (i.e. the upper part in FIGS. 1 and 2). The screen 5 is simply mounted on an eccentric longitudinal axis (i.e. a mandrel axis 20) relative to the longitudinal axis of the cylindrical housing wall 9 so that the acceptance chamber 10 extends substantially uniformly in volume on opposite sides of the screen. Equip it. The accept stock outlet 27 is in a position to receive good slurry stock from the chamber area of maximum eccentric spacing, in particular in relation to the maximum eccentric spacing between screen 5 and housing wall 9.

It will be understood that various changes and modifications may be made without departing from the spirit of the invention and the scope of the novel concept.

[Brief explanation of the drawing]

FIG. 1 is a detailed isometric view of a longitudinal axial cross-section of a papermaking stock screen embodying the present invention, and FIG. 2 is a vertical cross-sectional view taken along line Nl of FIG. 6...Screen, 7...Screen opening, 8...Housing, 9...Housing wall, 10...
...Acceptance room. 11,12... Machine wall, 1
3... Supply room, 14, 23... Partition wall,
15... Supply inlet, 17... Stock supply direction arrow, 18... Supply port, 19... Film, 20... Rotating shaft, 21... ...Film rotating device, 22...Reject chamber, 24...Discharge port, 25...Conduit, 27...Acceptance outlet, 28...Outlet pipe. FIGI FIG2

Claims (1)

[Claims] 1 an elongated cylindrical tubular screen; a housing surrounding the screen having an elongated cylindrical wall extending in spaced relation to the periphery of the screen and defining an acceptance chamber about the screen; means for acting within the screen to promote good slurry stock movement through the walls of the screen to the acceptance chamber; and means for conducting from the acceptance chamber through the cylindrical wall of the housing. In a papermaking machine stock screen apparatus for processing stock entering a headbox, the apparatus comprises: outlet means for accepted stock being removed; and discharge means for receiving stock waste removed by the screen without passing through the screen wall; The longitudinal axis of the screen is eccentric with respect to the longitudinal axis of the cylindrical housing wall so that the acceptance chamber has a maximum eccentricity of the screen relative to the cylindrical housing wall. the chamber area of said screen is adapted to expand substantially uniformly in volume on opposite sides of said screen, and said accept stock exit means is adapted to provide a good slurry form from said chamber area of said maximum eccentric distance. arranged to receive stock, thereby substantially pulsating from the screen to the exit means as a result of expansion of the volume of the acceptance chamber from the minimum eccentric distance area to the maximum eccentric distance area. A papermaking machine stock characterized in that it provides a constant good slurry stock velocity with no lag and also a substantially uniform increase in the flow rate of the slurry stock to said outlet means. screen device.