GB2257619A

GB2257619A - A tank washer

Info

Publication number: GB2257619A
Application number: GB9115562A
Authority: GB
Inventors: Michael Robinson
Original assignee: Breconcherry Ltd
Current assignee: Breconcherry Ltd
Priority date: 1991-07-18
Filing date: 1991-07-18
Publication date: 1993-01-20
Anticipated expiration: 2011-07-18
Also published as: GB2257619B; GB9115562D0

Abstract

A tank washer located or locatable in a tank or other vessel for washing the same, comprises: a hollow shaft 1 having an axis; a rotor 10 mounted on and freely rotatable with respect to the shaft 1 about the axis, the rotor 10 having at one end region 15 a first curved surface 23 or 24 and at the opposite end region 16 a second curved surface; and a plurality of passageway means 6, 7 extending laterally through the shaft 1 from the hollow interior, through which in use a liquid can be fed, with some 6 of the passageway means opening in the vicinity of the first curved surface 23 or 24 of the rotor and with other passageway means 7 opening in the vicinity of the second curved surface of the rotor; wherein the arrangement of the shaft 1, rotor 10 and passageway means 6, 7 is such that in use liquid fed through the passageway means is caused to strike both the first and second curved surfaces of the rotor, to cause the rotor to rotate about the shaft, and the liquid is caused to be deflected by each curved surface through different degrees in different radial regions so that the liquid extends over an arc between a line perpendicular to the axis of the shaft and a line parallel to that axis. <IMAGE>

Description

TANK WASHER This invention relates to a tank washer intended to be located or locatable in a tank or other vessel for washing the same.

In a wide range of industrial processes it is normal practice to store liquids in tanks. Such tanks have to be cleaned from time to time, and the present invention is concerned with equipment for effecting the cleaning.

The types of tanks to be cleaned are those which contain, for example, milk, beer or wine, but the tank washer of the present invention can be used to wash tanks used for storing other materials, such as those used in the chemical, pharmaceutical or food industry.

During the washing, there is used either plain water or a combination of hot or cold chemical detergents specifically employed to deal with the liquid being flushed out. When detergents are employed, it is normal practice to rinse the tanks afterwards with water.

It is known to clean tanks by means of a spray device either inserted in the tank or fitted permanently in the tank. Such a device is supplied with the hot and cold water or detergent solution and it sprays the tank walls with the water or detergent solution until the vessel is cleaned, the residue then being drained from the bottom of the tank to waste or recirculated as necessary. To wash the tank effectively, the washing device has to supply a dense spray to all internal surfaces of the vessel, and it should spray in all directions with an even pattern of liquid. It is necessary that the washing device rotates, or at least part of the device rotates, because a fixed spray, though simpler, requires considerably more washing liquid.This is generally not acceptable because in industrial processes it is likely that the cleaning solution is paid for at source, with extra charges for disposing of the used cleaning solution. It is therefore important to keep the amount of liquid used to a minimum, and this low consumption is a major feature of the tank washer of the present invention.

Moreover, it is important that the tank washer is as simple as possible, totally reliable, and can be manufactured at a low cost. Although there are instances of the tank washer being moved from one tank to another, the trend nowadays is to install one washer in each tank on a permanent basis. The tank washer is immersed in the liquid stored in the tank and must be unaffected by it and also must not contaminate the stored liquid product. Furthermore, it is important that the tank washer is totally reliable as its operation cannot be checked - the first indication of a failure would be the spoiling of a later batch stored in the tank. As maintenance is not possible or not readily possible, the tank washer should be as simple as possible.

According to the present invention, there is provided a computer tank washer located or locatable in a tank or other vessel for washing the same, the tank washer comprising: a hollow shaft having an axis; a rotor mounted on and freely rotatable with respect to the shaft about the axis, the rotor having at one end region a first curved surface and at the opposite end region a second curved surface; and a plurality of passageway means extending laterally through the shaft from the hollow interior, through which in use a liquid can be fed, with some of the passageway means opening in the vicinity of the first curved surface of the rotor and with other passageway means opening in the vicinity of the second curved surface of the rotor;; wherein (i) the arrangement of the shaft, rotor and passageway means is such that in use liquid fed through the passageway means is caused to strike both the first and second curved surfaces of the rotor, (ii) the first and second curved surfaces of the rotor include angled faces inclined to jets of liquid issuing, in use, from the passageway means such that the action of the liquid striking those angled faces causes the rotor to rotate about the shaft, (iii) the shape of the first curved surface is such that in use liquid striking that surface is deflected through different degrees in different radial regions so that the liquid extends over an arc between a line perpendicular to the axis of the shaft and a line parallel to that axis away from the one end, (iv) the shape of the second curved surface is such that in use liquid striking that surface is deflected through different degrees in different radial regions so that the liquid extends over an arc between a line perpendicular to the axis of the shaft and a line parallel to that axis away from the opposite end, whereby as the rotor rotates liquid is sprayed through 360" about the axis of the shaft and about a line perpendicular to that axis, and (v), in use, the flows of liquid hitting the rotor at one end region and the opposite end region are balanced such that there is no overall axial thrust on the rotor caused by the liquid.

With regard to the rotor this must be shaped in such a way that the action of the water striking the rotor causes the rotor to rotate about the axis of the shaft, and also the shape of the rotor must be such that some water moving out radially away from the shaft is allowed to travel out radially without any deflection whereas the majority of the water is deflected through differing degrees at different regions of the first and second curved surfaces of the rotor with, on the first curved surface, some water being deflected through 90" towards the one end of the shaft and, on the second curved surface, other water being deflected through 90" towards the opposite end of the shaft.Thus, with the equipment being mounted in such a way that the axis of the shaft is vertical, water is deflected by the rotor from an entirely upward direction through differing degrees to the horizontal and downwardly to an entirely downward direction. In view of the fact that the rotor is rotating at high speed the resultant effect is a provision of a universal spray spraying in all directions, which can effect a thorough washing of a tank.

With regard to the surfaces of the first and second curved surfaces of the rotor, each has at least one angled face which is inclined to a radius from the axis of the shaft such that liquid moving along that radial line will strike the angled face and will tend to cause lateral movement of that face and hence rotation of the rotor. Conveniently each of the first and second curved surfaces of the rotor has two such angled faces. The angled faces will need to be inclined in the same sense so that all of the angled faces tend to cause rotation of the rotor in the same rotational direction. Moreover, with the first and second curved surfaces being of the same configuration and size, there is no net overall axial thrust on the rotor.

With regard to each of the first and second curved surfaces, various arrangements of the surfaces are possible in order to effect a suitable distribution of the liquid. However, one particular arrangement which is simple but effective is that in which the rotor is a single body which has a cylindrical external surface and which is provided with a central aperture to enable the rotor to be freely rotatably mounted on the shaft.

With each of the upper and lower surfaces of the rotor being provided with a smoothly curving indentation, it can be appreciated that any liquid moving radially outwardly from the axis across such a milled surface will be deflected by the milled surface upwardly (in the case of the upper, first curved surface) or downwardly (in the case of the lower, second curved surface). If the height of the rotor is reduced by milling in different regions, in travelling circumferentially around the rotor, it can be appreciated that the curved surface used to deflect the water will be reduced accordingly with the result that less deflection of the water will take place in certain zones thereby causing the water still to leave tangentially, but at different angles as measured relative to the axis.If, in at least one place, the curved surface is reduced to zero the water moving radially away from the axis will be free to travel without any deflection towards the tank wall.

In the tank washer of the present invention, liquid issuing radially through the passageway means is deflected by the rotor through an angle in the range from 0 to about 90 , unlike some known arrangements which call for a more tortuous path for the liquid to follow.

For a better understanding of the present invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which: Figure 1 is a side view of an embodiment of a tank washer in accordance with the present invention; Figure 2 is a section taken along the line lI-Il in Figure 1 in a plane perpendicular to the plane of the paper in Figure 1; Figure 3 is a longitudinal section on an enlarged scale through the rotor shown in Figure 1 prior to milling to its final shape; Figure 4 is an elevation of the rotor shown in Figure 2; and Figure 5 is a plan view of the rotor of Figure 4; In practice the tank washer of the present invention can be disposed with the axis of the shaft horizontal or vertical but in the illustrated embodiment it is shown with the axis vertical and with the majority of the shaft above the centre of the rotor, and therefore references to "upper" and "lower" with regard to the illustrated embodiment are to be read on the basis that the tank washer is in this particular disposition, but it is to be appreciated that this is not a requirement in practice.

Referring to the drawings, particularly Figures 1 and 2, it can be seen that a major component of the tank washer is an inlet tube 1 serving as the hollow shaft. The inlet tube 1 has an open upper end 2 and a closed lower end 3. Over an upper end portion is an external screw thread 4 by means of which the inlet tube can be secured to an internally screwthreaded duct capable of supplying liquid under pressure. The majority of the exterior of the inlet tube 1 is generally circularly cylindrical, apart from the screwthread 4 and two flats 5 which can be gripped by a spanner when the inlet tube is being fed into the liquid supply duct (not shown).

At a position intermediate the flats 5 and the closed lower end 3 of the inlet tube is an upper series of holes 6 which extend radially through the tube and are evenly spaced around a circumferential line.

Nearer the closed lower end 3 of the inlet tube 1 is a lower series of holes 7 which also extend radially through the inlet tube and which are also evenly spaced around a circumferential line. Just below the upper series of holes 6 is an upper circumferential groove 8 in the exterior of the inlet tube, and just above the lower series of holes 7 is a lower circumferential groove 9 provided in the exterior of the inlet tube.

Mounted for free rotation on the inlet tube 1 is a rotor 10 which has a circular cylindrical inner surface 11 fractionally larger than the external diameter of the inlet tube 1 in the region between the grooves 8 and 9. Opposite the grooves 8 and 9 in the inlet tube 1 are upper and lower circumferential grooves 12 and 13 in the rotor 10. The rotor 10 has a generally cylindrical outer surface 14, as well as an upper end region 15 and a lower end region 16. Other details of the rotor 10 appear in Figures 3, 4 and 5.

With regard to the upper end region 15 of the rotor 10, and with particular reference to the plan view of Figure 5, it can be seen that there is a broad low part 17 of the upper surface which, moving in an anti-clockwise direction (as viewed in Figure 5) tapers and is inclined upwardly, leading to a narrow high part 18. Similarly there is another broad low part 19 which also tapers and moves upwardly to a narrow high part 20.

Between the outer edge of the groove 12 and the arcuate region leading from the broad low part 17 to the narrow high part 18 is an upwardly curved face which curves upwardly moving in the outwardly radial sense and which increases in width (as measured radially) in a manner corresponding to that in which the arcuate part leading from the broad low part 17 to the narrow high part 18 corresponding tapers.

Similarly, outside the groove 12 and inside the zone leading from the broad low part 19 to the narrow high part 20 is another upwardly curved face 22 which curves upwardly moving in the outwardly radial sense.

In the region between the narrow high part 18 of one arcuate zone and the broad low part 19 of the other arcuate zone is an angled end face 23, and similarly in the region between the narrow high part 20 of that other arcuate zone and the broad low part 17 of the one arcuate zone is another angled end face 24. The word "angled" means that the face is inclined to a radially line extending from the central axis of the rotor which is coaxial with the central axis of the inlet tube 1.

A consequence of this is that some of the liquid issuing radially through the upper series of holes 6 will strike the angled end faces 23 and 24 and cause rotation of the rotor 10 in a clockwise direction (as viewed from above the rotor 10).

The angled end faces 23 and 24 face in opposite directions but are struck by jets of liquid moving in opposite directions which enables the same rotational sense to be imparted to the rotor 10.

The lower half of the rotor 10 is very similar to the upper half, except that in the illustrated embodiment the corresponding angled end faces face in a direction perpendicular to that in which the angled end faces 23 and 24 face. Moreover, in the upper part of the rotor 10 in moving from the broad lower part 17 to the narrow high part 18 of one arcuate zone one moves anti-clockwise as viewed from above the rotor 10. In contrast, in the lower half of the rotor 10 it is necessary to move clockwise (as viewed from below the rotor 10) when moving from the corresponding broad low part to the corresponding narrow high part; this is most clearly shown in Figure 4.

In all other respects, however, the lower half of the rotor 10 is identical to the upper half of the rotor 10, but separate reference numerals have not been used to identify the different regions of the lower part of the rotor 10.

As indicated above the rotor 10 is freely rotatable with respect to the inlet tube 1 but it is restrained from relative axial movement by two retaining rings 25 and 26. The ring 25 extends partially into the groove 8 of the inlet tube and partially into the groove 12 of the rotor 10, and the ring 26 extends partially into the groove 9 of the inlet tube 1 and partially into the groove 13 of the rotor 10 so as to secure the rotor 10 relative to the inlet tube 1 whilst still permitting rotational movement.

In production, the rotor 10 is initially in the form shown in Figure 3, but the characteristic upper and lower end regions 15 and 16 are formed by milling so as to leave milling so as to cause the gradual sweep down to the broad lower parts 17 and 19 respectively.

A similar technique is employed, but in the opposite rotational direction, with regard to the lower end region 16.

On any given line lying on a radius from the axis of the rotor 10 the outer portion of the upper end region 15 is substantially horizontal, but the outer portion, when moving in the anti-clockwise direction is viewed from above the rotor 10, decreases in width but increases in height until it terminates in the angled face 23 which is inclined to a line on a radius from the axis of the rotor 10.

Turning now to the flow of liquid, the liquid issuing from some of the holes 6 in the region of the broad lower part 17 can continue moving radially outward without any deflection but the liquid issuing from holes positioned anti-clockwise (as viewed from above) increasingly strikes a larger amount of the upwardly curved face 21 and is deflected through a greater upward angle progressively; in terms of the liquid issuing from holes 6 which are located anticlockwise (as viewed from above the rotor 10) it is the variation in the height of the rotor in certain regions which causes the variation in deflection so that a whole rage of angles in deflection can be achieved.

In order to balance out all of the hydraulic forces the upper end region 15 has two matching machined configurations as does also the lower end region 16.

In practice, half of the liquid being used in the washing passes through the upper series of holes 6 and either just misses or is deflected by the upper end region 15 and the other half passes through the lower series of holes 7 and either just misses or is deflected by the lower end region 16 of the rotor 10.

It can be appreciated that the spray leaving the upper end region 15 covers an arc of 90" and that the spray leaving the lower end region 16 covers another arc of 90 . When these two arcs are defined this effectively covers 1800 and, as the rotor 10 rotates 360 , a universal spray is achieved. With regard to the materials from which the components are formed, any suitable durable materials can be employed.

Conveniently, however, the inlet tube 1 is formed of a stainless steel and the rotor is formed of an appropriate plastics material such as a filled polytetrafluoroethylene, which is a fine bearing material in itself and which, with the aid of the lubricating effect of the cleaning water, will run smoothly without any significant wear. Alternatively, the rotor can be formed of a stainless steel.

From the foregoing it can be appreciated that the illustrated embodiment of the tank washer in accordance with the present invention can be reliable because it is simple and need have only one moving part. It can avoid contaminating the product stored in the tank because it is made in materials compatible with those products, and it requires no lubrication other that the cleaning liquid itself. Moreover, in practice, it can be operated with a reduced consumption of the cleaning liquid because, unlike a fixed series of nozzles, the rotor during each complete revolution, sprays universally through 360". The resultant spray can clean the top and bottom of the tank as required.

Moreover, the rotor 10 is particularly freely running because any axial forces caused by the jets of liquid hitting the upper end region 15 are balanced by opposite axial forces caused by jets of water leaving the lower holes 7 and striking the lower end region 16 of the rotor 10.

With regard to the rings 25 and 26, they can be resilient rings which are forced apart to fit them around the main cylindrical portion of the inlet tube 1 and which "shrink" into the grooves 8 and 9 respectively.

The embodiment of tank washer illustrated in the drawings can be particularly compact, with the external diameter of the rotor 10 being as little as 28 mm. The rotor can have a height 23 mm, and the internal diameter of the rotor can be 11.5 mm.

In this embodiment the end face 23 is 19.5 mm from the further tangent of the rotor which is parallel to that end face. The height of the rotor in the region immediately adjacent the edge of the grooves 12 and 13 is 9.8 mm.

With regard to the numbers of holes, it has been found that good results can be obtained if each of the upper and lower series of holes 6 and 7 has thirteen holes each of a diameter of 2.5 mm, but different numbers and different diameters can obviously be employed.

Claims

1. A compact tank washer located or locatable in a tank or other vessel for washing the same, the tank washer comprising: a hollow shaft having an axis; a rotor mounted on and freely rotatable with respect to the shaft about the axis, the rotor having at one end region a first curved surface and at the opposite end region a second curved surface; and a plurality of passageway means extending laterally through the shaft from the hollow interior, through which in use a liquid can be fed, with some of the passageway means opening in the vicinity of the first curved surface of the rotor and with other passageway means opening in the vicinity of the second curved surface of the rotor;; wherein (i) the arrangement of the shaft, rotor and passageway means is such that in use liquid fed through the passageway means is caused to strike both the first and second curved surfaces of the rotor, (ii) the first and second curved surfaces of the rotor include angled faces inclined to jets of liquid issuing, in use, from the passageway means such that the action of the liquid striking those angled faces causes the rotor to rotate about the shaft, (iii) the shape of the first curved surface is such that in use liquid striking that surface is deflected through different degrees in different radial regions so that the liquid extends over an arc between a line perpendicular to the axis of the shaft and a line parallel to that axis away from the one end, (iv) the shape of the second curved surface is such that in use liquid striking that surface is deflected through different degrees in different radial regions so that the liquid extends over an arc between a line perpendicular to the axis of the shaft and a line parallel to that axis away from the opposite end, whereby as the rotor rotates liquid is sprayed through 360" about the axis of the shaft and about a line perpendicular to that axis, and (v), in use, the flows of liquid hitting the rotor at one end region and the opposite end region are balanced such that there is no overall axial thrust on the rotor caused by the liquid.

2. A compact tank washer according to claim 1, wherein the rotor is shaped in such a way that the action of the water striking the rotor causes the rotor to rotate about the axis of the shaft, and also the shape of the rotor must be such that some water moving out radially away from the shaft is allowed to travel out radially without any deflection whereas the majority of the water is deflected through differing degrees at different regions of the first and second curved surfaces of the rotor with, on the first curved surface, some water being deflected through 90" towards the one end of the shaft and, on the second curved surface, other water being deflected through 90" towards the opposite end of the shaft.

3. A compact tank washer according to claim 1 or 2, wherein each of the first and second curved surfaces of the rotor has at least one angled face which is inclined to a radius from the axis of the shaft such that liquid moving along that radial line will strike the angled face and will tend to cause lateral movement of that face and hence rotation of the rotor.

4. A compact tank washer according to claim 3, wherein each of the first and second curved surfaces has two angled faces, with all of the inclined faces being inclined in the same sense so that all of the angled faces tend to cause rotation of the rotor in the same rotational direction.

5. A compact tank washer according to any preceding claim, wherein the rotor is a single body which has a cylindrical external surface and which is provided with a central aperture to enable the rotor to be freely rotatably mounted on the shaft.

6. A compact tank washer according to any preceding claim, wherein the plurality of passageway means includes a first series of holes which extend radially through the shaft and are evenly spaced around a first circumferential line level with the first curved surface of the rotor, and a second series of holes which extend radially through the shaft and are evenly spaced around a second circumferential line level with the second curved surface of the rotor.

7. A compact tank washer according to any preceding claim, wherein the rotor is restrained from axial movement with respect to the shaft by restraining means.

8. A compact tank washer according to any preceding claim, wherein the shaft is formed of a stainless steel and the rotor is formed of a stainless steel or a plastics material.

9. A compact tank washer according to claim 1, substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawings.