Apparatus for cleaning tanks and the like

Abstract

Apparatus for cleaning the interior surfaces of tanks and the like, of the type comprising an outer section with a flange member for attachment to the wall of a tank to be cleaned, and with device means for connection to a fluid supply and to a driving means, and an inner section with a supply tube for introduction into the tank, whereby the tube is fixed to the flange member at one end and at its other end is provided with a flushing head which is rotatable about the tube axis and has a tube section on which there is pivotally mounted a nozzle unit with two oppositely directed nozzles. The nozzle unit is rotatable about an axis at right angles to the tube axis, and the flushing head is provided with a mechanism for rotating the nozzle unit a small angle for each revolution of the flushing head. The flushing head is mounted in a holder fixed to the adjacent end of the tube, and is rotated by a driving shaft disposed concentrically in the supply tube, which shaft is attached to the flushing head at one end and is connectable to the external driving device at its other end, and further the tube section of the flushing head is provided with a slot-like aperture in the area facing the nozzles, which aperture extends essentially over one half of the circumference of the tube section, for supplying cleaning fluid to only one nozzle at a time.

Description

The present invention relates to an apparatus for cleaning the interior surfaces of tanks and the like, comprising an outer section with a flange means for attachment to the wall of a tank to be cleaned, and with means for connection to a fluid supply and to a driving means, and an inner section with a supply tube for introduction into the tank, which tube is fixed to the flange means at one end and at its other end is provided with a flushing head which is rotatable about the tube axis and has a tube section on which there is pivotably mounted a nozzle unit with two oppositely directed nozzles so that the nozzle unit is rotatable about an axis at right angles to the tube axis, the flushing head being provided with means for rotating the nozzle unit a small angle for each revolution of the flushing head.

The present apparatus is especially intended for cleaning of oil tanks on tankers. There are previously known different types of tank cleaning devices. With the constantly increasing size of the tankers and with the need for correspondingly effective and simultaneously economic devices there is, however, a need for larger, simpler and more powerful tank cleaning devices.

By the known tank cleaning devices of the above mentioned type, which are provided with a nozzle unit with oppositely directed nozzles, the cleaning fluid is delivered simultaneously through both nozzles. During the slow rotation of the nozzle unit one of the fluid jets will then move slowly downwards on the tank wall, whereas the other fluid jet will move upwards. By washing down or flushing of the tank walls it is, however, primarily by the downwardly directed movement of the fluid jet than the most effective cleaning is achieved, as oil residues or the like along the walls are then washed downwards by the hitting fluid jets. Besides, with the apparatus in which both nozzles deliver fluid simultaneously, there is needed a fluid amount which is the double of that which is needed with an apparatus in which only one nozzle is supplied with cleaning fluid at a time.

Thus it is an object of the invention to provide a tank cleaning apparatus which has a particularly simple construction with small space requirements, but which is simultaneously powerful and efficient. Simultaneously it is an object of the invention to provide an apparatus in which only one of the nozzles delivers cleaning fluid at a time, and with which there is achieved effective cleaning with high washing pressure and reduced fluid consumption.

The above objects are achieved with an apparatus of the type which is set forth above, and which according to the invention is characterized in that the flushing head is mounted in a holder means fixed to the adjacent end of the tube, and is rotated by means of a driving shaft disposed concentrically in the supply tube, which shaft is attached to the flushing head at one end and is connectable to the external driving means at its other end, and in that said tube section of the flushing head is provided with a slot-like aperture in the area facing the nozzles, which aperture extends essentially over one half of the circumference of the tube section, for supplying cleaning fluid to only one nozzle at a time.

In order that the invention may be more readily understood an embodiment thereof will now be described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 shows a vertical section of an apparatus according to the invention,

FIG. 2 shows a partly sectioned view of a portion of the apparatus viewed in the direction of the arrow A in FIG. 1,

FIG. 3 shows a schematic view of an embodiment of a portion of the turning mechanism for the rotation of the nozzle unit, and

FIG. 4 shows a section along the line IV -- IV in FIG. 1.

In FIG. 1 is shown a flange means 1 which is for instance disposed on the upper surface of a tank on board a ship. On the flange there is disposed a tube section 2 which in the example shown has the form of a T and forms a supply device for the supply of the cleaning fluid to the lower section of the apparatus. A tube 3 is fixed to the flange 1 for supply of cleaning fluid to a flushing head 4 and a nozzle unit 5 mounted on the flushing head. At the lower end of the tube 3 there is arranged a holder means which is fixed to the tube and in which the flushing head is rotatably mounted. The holder means consists of two ring flanges 6 and 7 which are held together by means of a ring 8 which is disposed between the ring flanges and secured thereto by welding. The ring flange 7 carries a sliding bearing or sleeve 9 which constitutes a bearing for the flushing head.

The flushing head 4 is an L-formed tube section with a vertical and a horizontal portion. As mentioned above the vertical portion is mounted in said holder means, and the nozzle unit 5 is pivotally mounted on the horizontal portion. The flushing head is rotatable about the axis of the tube 3 by means of a driving shaft 10 which is concentrically disposed in the tube, of which shaft the lower end is rigidly secured to the flushing head and the upper end is adapted for connection to an external driving means (not shown). It appears from FIG. 1 that the driving shaft 10 in a sealing way is passed through the wall in the T section 2, and that a protecting casing 11 is disposed on the upper flange of the T section. This casing can be removed for connection of the actual driving means which preferably consists of a hydraulically or pneumatically driven motor which by way of a gear causes the driving shaft with the flushing head to be rotated in the desired direction and with the desired speed, e.g. approximately one revolution per minute.

The nozzle unit 5 includes a nozzle holder 12 in which there are mounted two oppositely directed tubes 13 and 14 on the outer ends of which there are provided nozzles 15 and 16, respectively. The flushing head is provided with a rotating mechanism which for each revolution of the flushing head 4 about the tube axis or the vertical axis causes the nozzle unit is turned a small angle about the horizontal axis (i. e. at right angles to tube axis), whereby the nozzle unit for the rest of the rotation of the flushing head is prevented from rotating. In the present embodiment the mechanism for the rotation of the nozzle unit includes a worm gear 17 which is mounted on the nozzle holder 12 and which is concentric with the horizontal tube section of the flushing head. Further the mechanism includes a worm 18 (see FIG. 2) which is in engagement with the worm gear and is rotatably mounted in a hub 1 which is a part of or is fixed to the flushing head 4. At its upper end the worm 18 is provided with a cog wheel 20 which for each revolution of the flushing head is intermittantly actuated by an engagement member (not shown in FIGS. 1 and 2) which is attached to the underside of the lower ring flange 7 of the holder means. Further the worm is provided with a specially designed blocking wheel 21 which is disposed above the cog wheel 20 and prevents rotation of the worm when this is not actuated by the engagement member, as the blocking wheel outside the engagement area bears against the outer surface of the ring flange.

The details of the combined rotating and blocking device for the worm is shown in FIG. 3 which shows a plan view of the worm 18 with the cog wheel 20 and the blocking wheel 21. Further this Figure shows the lower portion of the ring flange 7 to the underside of which there is secured an engagement member 22 (in phantom lines) which is formed with two teeth 23. As shown the cog wheel 20 is provided with four teeth, whereas the blocking wheel 21 is formed as a square with opposed concave outer surfaces, where the concavity has a radius of curvature corresponding to half the outer diameter of the ring flange 7. The operation of the device is as follows: During the rotation of the flushing head about the longitudinal axis of the tube 3 one of the concave surfaces of the blocking wheel 21 bears against the outer surfaces of the ring flange 7 (shown in phantom lines). In the area between the teeth 23 of the engagement member 22 this outer surface is provided with a notch 24 which allows simultaneous rotation of the blocking wheel and the cog wheel when the teeth of the cog wheel are brought into engagement with the teeth 23. By means of the arrangement shown one achieves that the worm 18 is rotated exactly 90.degree. per revolution of the flushing head. The pitch of the worm is such that by its rotational movement the worm gear 17 and thus the nozzle unit 5 is rotated a desired angle about the horizontal axis. When the worm 18 with cog wheel and blocking wheel has passaed the engagement member 22 another surface of the blocking wheel is abutting against the outer surface of the ring flange 7, so that further rotation of the worm in relation to the flushing head is prevented until the blocking wheel returns to the notch 24.

Such as indicated in FIG. 4, the horizontal tube section of the flushing head 4 is provided with a slotlike aperture 25 in the area facing the inner openings of the tubes 13 and 14, which aperture has a width which is essentially equal to the inner diameter of the tube 13 and 14 and extends essentially over one half of the circumference of the horizontal tube section. When the nozzle unit is rotated on the flushing head in direction of the arrow B in FIG. 4, one achieves with the shown position of the slot-like aperture that only the nozzle describing a downwardly directed circular arc, delivers washing fluid, whereas the other nozzle is closed. Thus the fluid jet will wash from the top to the bottom of the inner surfaces of the tank, which gives the most effective cleaning. If required, the washing can, however, take place in direction from the bottom to the top. This is achieved by using opposite rotational direction for the driving shaft 10 and thus the flushing head 4. It appears from FIG. 3 that the used rotating and blocking mechanism is symmetrical, so that it will function in the same way independently of the direction in which the worm is moved along the periphery of the ring flange 7. With the construction shown consumption of washing fluid is avoided in the period during which the nozzle is moved from downwardly to upwardly directed position, i.e. during the period when the washing is less effective. Simultaneously one achieves effective time utilization as a new washing cycle is initiated as soon as a downwardly directed or descending cycle through 180.degree. is completed. As shown in FIGS. 2 and 4, the axis of the nozzles form an angle of .alpha. degrees in a plane perpendicular to the horizontal axis of rotation. This applies for the case when the nozzle unit 5 is rotated an angle of 2.alpha. degrees per revolution of the flushing head. In this way one achieves that the hit stripes which are formed by one nozzle on the inner surfaces of the tank, will be located midway between the hit stripes for the other nozzle, when several washing cycles are carried out sequentially. Thus the cleaning becomes more effective.

The bearing means for the mounting of the nozzle unit 5 on the horizontal tube section of the flushing head 4 consists of a bearing in the form of two cylindrical sleeves 26 and 27. Simultaneously these bearings have a sealing effect. The terminal opening of the horizontal tube section is closed by means of a cover 28 which is secured to or screwed onto the tube section. The cover is provided with a flange 29 preventing that the nozzle unit is displaced axially on the flushing head.

Claims

I claim:

1. Apparatus for cleaning the interior surfaces of tanks and the like, comprising an outer section with a flange means for attachment to the wall of a tank to be cleaned, and with means for connection to a fluid supply and to a driving means, and an inner section with a supply tube for introduction into the tank, which tube is fixed to the flange means at one end and at its other end is provided with a flushing head which is rotatable about the tube axis and has a tube section on which there is pivotally mounted a nozzle unit with two oppositely directed nozzles so that the nozzle unit is rotatable about an axis at right angles to the tube axis, the flushing head being provided with means for rotating the nozzle unit a small angle for each revolution of the flushing head, characterized in that the flushing head is mounted in a holder means fixed to the adjacent end of the tube, and is rotated by means of a driving shaft disposed concentrically in the supply tube, which is attached to the flushing head at one end and is connectable to the external driving means at its other end, and in that said tube section of the flushing head is provided with a slot-like aperture in the area facing the nozzles, which aperture extends essentially over one half of the circumference of the tube section, for supplying cleaning fluid to only one nozzle at a time.

2. Apparatus according to claim 1 wherein the means for step by step rotation of the nozzle unit comprises a worm mounted in the flushing head and meshing with a worm gear on the nozzle unit, whereby the worm is intermittently acted upon by an engagement member on the supply tube, and by means of a blocking device is prevented from rotation outside the engagement zone, characterized in that the blocking device consists of a square blocking wheel mounted on the worm and having opposed concave outer surfaces for movement along a cylindrical surface which is concentric with the supply tube and is provided with a notch allowing an angular rotation of the blocking wheel when the worm is acted upon by the engagement member.

3. Apparatus as set forth in claim 1, characterized in that the axis of the nozzles in a plane perpendicular to the rotational axis of the nozzle unit form a mutual angle equal to half the angle which the nozzle unit is rotated per revolution of the flushing head.