EP0907791B1

EP0907791B1 - Cleaning device for cleaning a dewatering screen in a wet or dry section or a wet felt in a press section of a paper making machine

Info

Publication number: EP0907791B1
Application number: EP97918431A
Authority: EP
Inventors: Mathieu Jozef Maria Robberts
Original assignee: ROBO PAPER BV
Current assignee: Robo Paper BV
Priority date: 1996-05-09
Filing date: 1997-05-12
Publication date: 2003-04-16
Anticipated expiration: 2017-05-12
Also published as: ATE237714T1; NL1003070C2; EP0907791A1; AU2653697A; WO1997042373A1; DE69720993D1; BR9708943A

Abstract

Cleaning device (1) for cleaning a dewatering screen (7) in a wet or dry section or a wet felt in a press section of a paper making machine, which device comprises at least one rotatable spray nozzle (3), which is coupled to an air and/or liquid supply means (131, 132), wherein the cleaning device includes a motor (5) for rotating spray nozzle. Herewith is achieved that the rotational speed of the spray nozzle can be adjusted independently of the amount of medium and the pressure of said medium, which is required (or desired) for the necessary cleaning operation.

Description

The invention relates to a cleaning device for cleaning a dewatering screen in a wet or dry section or a wet felt in a press section of a paper making machine, said device comprising at least one rotatable spray nozzle, which is coupled to an air and/or liquid supply means, and a motor for rotating said spray nozzle.

During the production of paper a dewatering screen and/or a wet felt is contaminated with paper residue, size-residue and other contaminants. In order to obtain a proper operation of the paper making machine, the dewatering screens and/or wet felts need to be cleaned by means of a cleaning device.

A cleaning device of this kind is inter alia known from German Gebrauchsmuster DE-U-29517859. The cleaning device shown and described therein includes a rotatable spray nozzle which is driven by the (cleaning) water. The cleaning device furthermore contains means for supplying air, which air is blown into a hood, in which the rotatable spray nozzle is disposed, in order to provide exhaustion of the detached dirt and/or the mist or the residual water into an discharge room.

One disadvantage of this known cleaning device is the fact that a particular amount of cleaning water is required to obtain a required/desired rotational speed of the spray nozzle. This may cause the screen or the felt to become wetter than may be desirable, which has a negative effect on the paper production process and/or may lead to malfunctions.

Another disadvantage of this known device is the fact that the exhaustion of the detached dirt and/or the mist or the residual water does not function adequately, because the matter to be exhausted is carried from under the hood along with the screen or the felt.

The object of the invention is to provide an improved cleaning device which does not exhibit the above disadvantages. In order to accomplish that objective a cleaning device according to the invention is characterized in that said said motor is an electro-motor and includes a hollow shaft, which forms part of the rotatable part of the motor, wherein the spray nozzle is directly mounted to one end of the hollow shaft and wherein the other end of the hollow shaft is coupled to the air and/or liquid supply means.

This enables easy adjustment of the rotational speed of the spray nozzle in dependence on the degree of contamination, the type of screen or felt, the necessary cleaning operation, etc.

Another embodiment of a cleaning device according to the invention is characterized in that said cleaning device furthermore includes at least two air jet nozzles, which jet nozzles are disposed on either side of the rotatable spray nozzle.

This enhances the cleaning operation of the rotatable spray nozzle, because the dirt detached by the spraying of the spray nozzle is removed from the screen or the felt by the air jets. In addition to that an overpressure is generated near the screen or the felt, which automatically causes exhaustion.

Another embodiment of a cleaning device according to the invention is characterized in that said cleaning device includes a row of air jet nozzles extending transversely to said screen or said felt, which air jet nozzles are positioned in the direction of movement of said screen or said felt with respect to said rotatable spray nozzle, and which comprise outlet openings, which blow in operative condition, in a direction opposed to the direction of movement of said screen or said felt.

This provides additional certainty that (detached) dirt, residual water, etc. cannot be carried along with said screen or said felt, but is discharged through an exhausting hood.

Furthermore the invention relates to a cleaning device wherein said device comprises an exhausting hood, which hood terminates near or in a discharge drain (save-all) disposed at some distance from said screen and/or said felt and parallel to the transverse direction thereof. Said cleaning device is according to the invention characterized in that said exhausting hood comprises at least one plate-shaped end piece, which end piece is in contact, at least with its free end, with the inner side of the discharge drain (save-all) during operation. Thus the detached contaminations being carried off through said exhausting hood are collected only at the ends of the discharge drain (save-all), and said discharge drain (save-all) will not become clogged in the working area of the cleaning device. This leads to a considerably improved operation of the cleaning device, whilst at the same time minimizing shut-down and/or unnecessary standstill of the cleaning device.

According to one aspect of the invention the free end of the plate-shaped end piece is configured to have a shape which substantially corresponds with the shape of the inside of the discharge drain (save-all). This leads to a considerably improved displacement and removal of the contaminations to the ends of the discharge drain (save-all), whilst preventing the discharge drain (save-all) from becoming clogged.

One embodiment of the cleaning device according to the invention is characterized in that the plate-shaped end piece is made of a flexible material, for example a rubber or a plastic. This material can be readily processed at low cost, whilst at the same time providing a satisfactory cleaning of the discharge drain (save-all).

Another embodiment of the cleaning device according to the invention is characterized in that the outlet opening of the exhausiting hood is in the form of a venturi tube. This provides a considerably improved discharge of the contaminations from the exhausiting hood, so that the occurrence of clogging, failure and/or unnecessary standstill of the cleaning device is considerably reduced.

In US-A-5,129,956 a device for cleaning printed circuit boards using a heated aqueous solution is disclosed. It incorporates a motor to rotate by means of a belt drive a manifold with two nozzles in circular pattern allowing the aqueous solution to impact the circuit boards to be cleaned from many angles and in many directions as to cover large areas.

Hereafter the cleaning device will be explained by way of example with reference to the accompanying figures, in which:

Figure 1 shows a first embodiment of a cleaning device according to the invention;

Figure 2 is a more detailed view of a part of an embodiment of a cleaning device;

Figure 3 is a more detailed view of another embodiment of a cleaning device according to the invention; and

Figure 4 shows another embodiment of a cleaning device according to the invention.

Figure 1 shows an embodiment of a cleaning device 1 including a rotatable spray nozzle 3. Said spray nozzle is driven by a motor 5 in order to obtain the required/desired rotational speed. Spray nozzle 3 is coupled to a hollow shaft 51, which forms part of the rotatable part of the motor. The rotational speed can be adjusted thereby in dependence on e.g. the extent of contamination, the type of screen or felt, the spray nozzle used, the amount and/or the pressure of the liquid (e.g. water) and the air pressure used.

The cleaning device is placed near a screen or felt 7, which moves over a roll 9. The cleaning device furthermore includes an exhausting hood 11, which is coupled to a fan 21.

A cleaning device furthermore includes supply means 13, which are on the one hand coupled to a liquid supply pipe 131 and an air supply pipe 132, and which on the other hand supply the liquid to spray nozzle 3 via an outlet 15. Supply means 13 furthermore include an outlet 17, which is coupled to air supply means 19. Said air supply means 19 include a portion 193, which blows air along the liquid sprayed onto the screen or the felt by the spray nozzle. Air supply means 19 furthermore include a portion 191, which blows air in the form of a so-called air knife after the screen or the felt has passed spray nozzle 3. The supplied air and the detached dirt, residual water etc. are exhausted via a fan 21.

Four parameters are of essential importance for the necessary cleaning of screen or felt 7, viz. the speed at which the paper, and thus the screen or the felt are transported, the amount of medium (air, water and/or other liquid) that is required, the pressure of the medium and the rotational speed (power) of spray nozzle 3.

The possibility to select the amount of medium and the pressure of said medium independently of the rotational speed of the spray nozzle with the cleaning device according to the invention provides a great deal of freedom in the selection of the above parameters for different types of screens or felts, different types of contamination/cleaning requirements, different belt speeds, different requirements with regard to the allowed amount of liquid, etc.

Figure 2 is a more detailed view of a part of an embodiment of a cleaning device according to the invention. Those elements that correspond with the elements shown in Figure 1 are indicated by the same reference numerals.

The rotatable spray nozzle 3 covers a spraying area 31. Beside this spraying area air jet nozzles 4 forming part of portion 193 of air supply means 19 are provided, which air jet nozzles assist in soaking off/detaching contaminations from the screen or felt 7. Said air jets 41 furthermore cause the dirt to be moved from the screen or felt 7 into the exhausting hood 11 disposed thereabove.

Instead of using two air jet nozzles 4 it is also possible, of course, to use four air jet nozzles or a row of air jet nozzles disposed on an imaginary circle.

Figure 3 is a more detailed view of a part of an embodiment of a cleaning device according to the invention.

In this embodiment portion 191 of air supply means 19 is in the form of a row of air jet nozzles, which blow air jets 195 at an angle towards screen or felt 7, in a direction opposed to the direction of movement of said screen or said felt. This provides a so-called air knife, by means of which the detached dirt and/or the mist or the residual water is removed from said screen or said felt.

Because air is blown in the direction of said screen or said felt, a high pressure (overpressure) is generated at the location of said screen or said felt, which results in the removal of dirt etc. from said screen or said felt. The fan (21, see Figure 1) takes care of the further transport and discharge of the dirt etc.

Figure 4 shows another embodiment of the cleaning device according to the invention. The parts of the cleaning device of this embodiment are indicated by reference numerals that correspond with those of the embodiment of the cleaning device according to Figure 1. The contaminated screen or felt 7 is cleaned by means of rotatable spray nozzle 3, after which the detached contaminations are transported through exhausting hood 11 in the direction indicated by the arrows, possibly along with the cleaning liquid being used, by means of

portions

191 and 193 of air supply means 19. As is shown in Figure 4, exhausting hood 11 terminates near or in a discharge drain 60 (save-all), which discharge drain 60 (save-all) is disposed at some distance from the screen or felt 7 and parallel to the transverse direction thereof. In order to prevent accumulation of contaminations in discharge drain 60 (save-all) resulting in said discharge drain 60 (save-all) becoming clogged, the exhausting hood 11 is according to the invention provided with at least one end piece 61, said end piece 61 with its free end piece 61a in the operative position being in contact, at least substantially so, with the inner side 60a of discharge drain 60 (save-all). End piece 61 is preferably plate-shaped, so that the outflow of contaminations from exhausting hood 11 in the direction indicated by the arrows is hardly obstructed, if at all.

Whilst screen or felt 7 is being cleaned in the operative condition, cleaning device 1 is moved to and from along screen or felt 7, in the transverse direction thereof, in a known manner. The soaked-off contaminations are deposited into discharge drain 60 (save-all) via exhausting hood 11, in the direction indicated by the arrows, from which location they are moved towards the two ends of said discharge drain 60 (save-all) by means of end piece 61 during the movement of cleaning device 1. Thus the soaked-off contaminations are collected only at the ends of discharge drain 60 (save-all), and said discharge drain (save-all) will not become clogged in the working area of cleaning device 1, i.e. substantially in the centre of discharge drain 60 (save-all). In addition to that the collected contaminations can be readily removed at the two ends of the discharge drain (save-all), without having to stop cleaning device 1. This leads to a considerably improved functioning of cleaning device 1, whilst at the same time reducing the occurrence of failure and/or unnecessary standstill of the cleaning device.

The free end 61a of end piece 61 may have a shape which substantially corresponds with the shape of the inner side 60a of discharge drain 60 (save-all). This leads to a considerably improved displacement and removal of the contaminations to the ends of discharge drain 60 (save-all), thus preventing the discharge drain (save-all) from becoming clogged.

The plate-shaped end piece may be made of a flexible material, for example a rubber or a plastic, which exhibits sufficient rigidity for moving the contaminations.

Although the outflow opening of exhausting hood 11 of Figure 1 is provided with a fan 21, the exhaustion of contaminations from exhausting hood 11 may also take place in a different manner. As is shown in Figure 4, the outflow opening of exhausting hood 11 is made in the form of a venturi tube 62. As a result of the special converging configuration of venturi tube 62, the pressure generated within exhausting hood 11 is converted into velocity within said venturi tube, resulting in an improved exhaustion of the contaminations to discharge drain 60 (save-all), as indicated by the arrows. In this manner the risk of clogging and failure of the cleaning device is strongly reduced.

It will be apparent that several minor modifications to the cleaning device according to the invention are possible without departing from the essence of the invention.

Thus it will be possible to operate the cleaning device with air only (without liquid), resulting in dry cleaning action.

Furthermore it will be possible to add chemicals to the cleaning liquid (e.g. water).

It will also be possible, if desired, to configure said spray nozzle as a combined liquid and air spray nozzle.

Claims

Cleaning device for cleaning a dewatering screen (7) in a wet or dry section or a wet felt (7) in a press section of a paper making machine, said device (1) comprising at least one rotatable spray nozzle (3), which is coupled to an air and/or liquid supply means (13), and an motor (5) for rotating said spray nozzle (3), characterized in that said motor (5) is an electro-motor and includes a hollow shaft (51), which forms part of the rotatable part of the motor, wherein the spray nozzle (3) is directly mounted to one end of the hollow shaft (51) and wherein the other end of the hollow shaft (51) is coupled to the air and/or liquid supply means (13).
Cleaning device (1) according to claim 1, characterized in that said cleaning device includes furthermore at least two air jet nozzles (191, 193), which jet nozzles are disposed on either side of said rotatable spray nozzle (3).
Cleaning device (1) according to claim 1 or 2, characterized in that said cleaning device includes a row of air jet nozzles (191) extending transversely to said screen or said felt (7), which air jet nozzles are positioned downstream to said rotatable spray nozzle (3) with respect to the direction of movement of said screen or said felt (7) and which comprise outlet openings which blow during operation in a direction opposed to the direction of movement of said screen or said felt (7).
Cleaning device according to any one of the preceding claims, wherein said device comprises an exhausting hood (11), whereby the spray nozzle (3) is disposed within the exhausting hood, which hood is movable along the screen or felt (7) in the transvere direction thereof and terminates near or in a discharge drain (60) disposed at some distance from said screen and/or said felt (7) and parallel to the transverse direction thereof, characterized in that said exhausting hood (11) comprises at least one plate-shaped end piece (61), which end piece is in contact, at least with its free end, with the inner side (60a) of the discharge drain (60) during operation.
Cleaning device according to claim 4, characterized in that the free end (61a) of the plate-shaped end piece (61) is configured to have a shape which substantially corresponds with the shape of the inside (60a) of the discharge drain.
Cleaning device according to claim 4 or 5, characterized in that said plate-shaped end piece (61) is made of a flexible material.
Cleaning device according to claim 4, 5 or 6, characterized in that said plate-shaped end piece (61) is made of a rubber or a plastic.
Cleaning device according to any one of the preceding claims, wherein said device comprises an exhausting hood, whereby the spray nozzle is disposed within the exhausting hood, characterized in that the outlet opening of said exhausting hood (11) is in the form of a venturi tube (62).