PROCEDURE AND APPARATUS FOR THE DRAINAGE OF THE WIRE AND/OR PRESS SECTION OF A PAPER MACHINE OR EQUIVALENT

Abstract: Procedure for the drainage of the wire and/or press section of a paper machine, in which procedure at least one suction pipe (1) is provided with at least one gap (2) and the suction pipe (1) is connected to a vacuum device (4) to develop a vacuum at least in this vacuum pipe, and in which procedure a felt, wire or equivalent (3) is moved over the gap of the suction pipe, water being thus drained from the felt, wire or equivalent. In the procedure, the vacuum capacity is adjusted by measuring and/or adjusting at least the amount of water drained from the suction pipe (1) and, on the basis of the measured data, adjusting the vacuum capacity by means of regulating devices (11, 12). The invention also relates to an apparatus for adjusting the vacuum capacity.

Description: PROCEDURE AND APPARATUS FOR THE DRAINAGE OF THE WIRE AND/OR PRESS SECTION OF A PAPER MACHINE OR EQUIVALENT The present invention relates to a procedure as defined in the preamble of claim 1 and to an apparatus as defined in claim 6 for the drainage of the wire and/or press section of a paper machine. In paper industry, drainage is implemented using suction pipes, suction boxes, suction rollers or equivalent provided with longitudinal gaps or holes against a wire screen, felt or equivalent. Each suction pipe is so placed that the wire, felt or equivalent passes over the gap or holes and drying is effected as the water is hurled by a centrifugal force into the roller trough. The water is gathered in the suction pipe and passed to a suitable collecting place. An apparatus of this type is presented in Finnish patent publication 77706. In current systems, the vacuum is adjusted on the basis of pressure, by using various valve elements or by varying the rotational speed of a pump unit to maintain a desired pressure. Of the processes in a paper machine, the vacuum system is responsible for the highest power consumption. It also has an effect on the driving output and steam consumption of the press and wire section. In the solutions currently used, the adjustment of the vacuum capacity affects the negative pressure, but it has not been possible to reliably determine the effect of the adjustment on the drainage of the paper machine. An excessively high vacuum level is not beneficial to drainage. Instead, it increases the pumping costs and the costs resulting from the wear of fabrics and consumption of energy caused by increased friction. The object of the present invention is to achieve a completely new solution that allows the drawbacks of known technology to be avoided. The invention is based on an idea according to which the vacuum capacity is adjusted on the basis of water volume measurements with the aid of preprogrammed data. More particularly, the invention is characterized by what is presented in the claims. The solution of the invention has numerous significant advantages. It makes it possible to control the drainage of a paper machine so that an optimal drainage situation is reached, with the result that the solids content e.g. after the press section is maximized. Therefore, maximal drainage for the wire and felt type in use is achieved. The runnability of the paper machine is improved. An adjustable vacuum system allows considerable savings to be made in energy consumption and has advantageous effects on paper quality. In the following, the invention is described by referring to the attached drawing, which is a diagrammatic representation of an apparatus as provided by the invention. The figure shows a simplified form of an apparatus for the drainage of the wire and/or press section of a paper machine. The apparatus comprises at least one suction pipe 1 having at least one gap 2 over which the felt, wire or equivalent 3 passes, vacuum elements 4, piping elements 5, 6 connecting the suction pipe 1 to the vacuum elements 4, drive elements 7, 8 for operating the vacuum devices 4 and creating a vacuum in the suction pipe, and elements 9, 10 for moving the felt, wire or equivalent over the suction pipe, thereby developing a vacuum for the drying of the felt, wire or equivalent. The apparatus is provided with regulating elements 11, 12 for the adjustment of the vacuum capacity and elements 13 at least in the suction pipe for the measurement and/or adjustment of the amount of water drained, on the basis of which the vacuum capacity is adjusted by means of the regulating elements. x Vacuum capacity' refers to a value which equals negative pressure (p) * pump yield value (Q) . The suction pipe 1 is placed in the apparatus in a manner known in itself and it has a gap 2 that opens towards the felt, wire or equivalent 3 passing over it. Connected to the suction pipe 1 is a pipe 5 whose one end communicates with the hollow space of a separator 16. From the lower end of the separator, a pipe 18 extends downwards to a container 17. The water flows in the pipe 18 under the influence of gravity. Alternatively, a centrifugal pump (not shown) can be mounted in conjunction with the pipe 18, constituting a so-called extraction pump system. A pipe 6 starting from the upper end of the separator is connected at its other end to the vacuum element 4, preferably a vacuum pump. The pump 4 is operated by means of the drive elements 7, 8. The regulating elements consist of a control unit 12 and at least one valve element 11. The control unit 12 is preferably a process computer or equivalent. The valve element 11 preferably consists of at least one throttle valve and/or a replacement air valve. The valve element 11 is placed in the piping between the suction pipe 1 and the vacuum device 4 preferably near the suction pipe, most preferably in the pipe 6 between the pump 4 and the separator 16. The apparatus comprises a collecting element 15, preferably a so-called nip water trough, into which the water is hurled by a centrifugal force. The apparatus is provided with measuring devices 13 for the measurement of the amount of water drained. The measuring element that measures the amount of water drained from the suction pipe 1 is preferably placed in pipe 18 between the collecting element 15 and the container 19 or the like. The control unit 12 may consist e.g. of a process computer connected to receive the data supplied by the water meters 13, 14 and to adjust the vacuum capacity on the basis of these data. The adjustment of the vacuum capacity is controlled on the basis of information adjusted according to the water measurements or on the basis of preprogrammed information. The control unit preferably regulates the valve element 11 and/or the drive 7 of the pump 4. The vacuum capacity is adjusted in the suction piping by means of the valve element 11 and/or periodic operation of the pump 4 and/or by adjusting the speed of rotation of the vacuum pump 4 and/or by varying the rotational speed of the centrifugal fan or the position of the static vanes on its suction and pressure sides. With the solution of the invention, the ratio of the amounts of water drained from the suction pipe 1 and the collecting element 15 can be adjusted or programmed. It is obvious to the person skilled in the art that the invention is not restricted to the application example described above, but that it may instead be varied within the scope of the following claims.

Claims: CLAIMS 1. Procedure for the drainage of the wire and/or press section of a paper machine, in which procedure at least one suction pipe (1) is provided with at least one gap (2) and the suction pipe (1) is connected to a vacuum device (4) to develop a vacuum at least in this vacuum pipe, and in which procedure a felt, wire or equivalent (3) is moved over the gap of the suction pipe, water being thus drained from the felt, wire or equivalent, characterized in that at least the amount of water drained from the suction pipe (1) is measured and, on the basis of the measured data, the vacuum capacity is adjusted by means of regulating devices (11, 12) . 2. Procedure according to claim 1, characterized in that the amount of water drained into a collecting element (15) or the like placed under the roller (10) , especially water drained under the influence of centrifugal force, is also measured and the vacuum capacity is adjusted on the basis of the measured data. 3. Procedure according to claim 1 or 2, characterized in that the vacuum capacity is adjusted in the suction piping by means of a valve element (11) and/or by operating the vacuum pump (4) in periods and/or by adjusting the rotational speed of the vacuum pump (4) and/or by varying the rotational speed of a centrifugal fan or the position of the static vanes on its suction and pressure sides. 4. Procedure according to any one of claims 1 - 3, characterized in that the vacuum capacity is adjusted according to preprogrammed data in accordance with a suction piping (1) /collecting element (15) drainage ratio adjustable by manual or automatic means. 5. Procedure according to any one of claims 1 - 4, characterized in that a control unit (12) is used for the adjustment of the vacuum capacity. 6. Apparatus for draining the wire and/or press section of a paper machine, said apparatus comprising at least one suction pipe (1) provided with at least one gap (2) over which a felt, wire or equivalent (3) is passed, vacuum elements (4), pipe elements (5, 6) connecting the suction pipe (1) to the vacuum elements (4), drive elements (7, 8) for operating the vacuum elements (4) for creating a vacuum in the suction pipe, and elements (9, 10) for moving the felt, wire or equivalent (3) over the suction pipe, a vacuum being thus developed for the drying of the felt, wire or equivalent, characterized in that the apparatus is provided with elements (13) for measuring at least the amount of water drained from the suction pipe (1), on the basis of which the vacuum capacity is adjusted by means of regulating devices (11, 12) . 7. Apparatus according to claim 6, characterized in that the regulating devices consist of a control unit (12) and at least one valve element (11) . 8. Apparatus according to claim 6 or 7, characterized in that the apparatus additionally comprises elements (14) for measuring the amount of water flowing from a trough (15) or a similar collecting element. 9. Apparatus according to any one of claims 6 - 8, characterized in that the valve element (11) consists of at least one throttle valve and/or a replacement air valve.

Inventors: KARVINEN JUHA, KARVINEN, JUHA
Applicants: ECOPUMP OY, KARVINEN JUHA, KARVINEN, JUHA
Application year: 1995
Main classification: D21F1
IPC codes: D21F1, D21F7