WO2005039825A1

WO2005039825A1 - A method and a device for surface cleaning

Info

Publication number: WO2005039825A1
Application number: PCT/NO2004/000318
Authority: WO
Inventors: Elmund Harestad; Valter Harestad
Original assignee: WATECH AS
Current assignee: WATECH AS
Priority date: 2003-10-24
Filing date: 2004-10-20
Publication date: 2005-05-06
Anticipated expiration: 2006-04-24
Also published as: NO319655B1; NO20034755D0; NO20034755L

Abstract

A method and a device for surface cleaning, in which an abrasive agent is mixed with a fluid before the mixture is jetted against the surface which is to be cleaned, a pump (2) supplying a cleaning gun (6) with fluid and the cleaning agent and fluid being mixed together before flowing, together, through the feed hose (8) to the cleaning gun (6),

Description

A METHOD AND A DEVICE FOR SURFACE CLEANING

This invention relates to a method and a device for surface cleaning. More particularly, it concerns a method, in which there is preferably used a ceramic abrasive material which is mixed into a fluid, after which the mixture of fluid and abrasive material flows through a feed hose up to a cleaning gun. By means of a rotating nozzle in the feeding gun, the mixture of fluid and abrasive material is directed towards the surface which is to be cleaned. The invention also comprises a device for practicing the method.

Conventionally, the removal of corrosion and possible surface treatment previously applied, in particular from larger surfaces, has been carried out by means of dry sand-blasting. Sand-blasting according to the prior art is relatively effective, but contaminates to a considerable degree the surroundings at the work area. Further, it is necessary to protect the operator against grains of sand, dust, noise and heat. Thus, the operator's protective equipment is comprehensive and heavy, reducing, to a considerable degree, the efficiency of the method. ι Due to the risk of sparking between grains of sand and the object which is being cleaned, this cleaning method cannot be used in explosion-hazardous areas.

It is also known to use high-pressure washing with water under very high pressure. It is obvious that the risk of serious operator injuries, for example by hose rupture, is considerable with this method, in which the water pressure can be several thousand bars in the feed hose up to the cleaning gun which is held by an operator.

In a further known method sand and water are mixed together in the cleaning gun by means of the ejector principle, after which water and sand, together, are directed towards the object to be cleaned. Cleaning guns for this method are relatively complicated with several supply hoses for sand, air and water, and therefore, such cleaning cjuns are relatively heavy and difficult to handle. At the same time, using this method, the yield is modest.

All the prior art methods mentioned are relatively energy- demanding relative to the area cleaned.

The invention has as its object to remedy or reduce at least one of the drawbacks of the prior art.

The object is achieved according to the invention through the features specified in the description below and in the following claims .

According to the invention, a pump supplies a mixing unit for abrasive material and fluid with a fluid under pressure. The pressure is most advantageously in the order of 900 bars, but can be varied within wide limits according to what materials are to be cleaned. The abrasive material is normally formed by a ceramic material, for example sand, whereas the fluid, in by far the most cases, is water, to which chemicals have possibly been added in order to prevent ice formation. In what follows, the term sand is used for the abrasive material, whereas water represents the fluid.

In the mixing unit the stream of water from the pump is divided into a first partial stream which flows through a first control valve, possibly an adjustable throat, and further through the feed hose to a cleaning gun.

A second partial stream flows through a second control valve into a pressure-tight sand tank filled with sand. A mixture of sand and water flows via an outlet pipe out of the sand tank and is directed into the first partial stream.

Water and sand then flow together through the feed hose to the cleaning gun.

In the cleaning gun the mixture of water and sand is directed into a spindle tube which is rotating about its longitudinal axis .

In order to overcome operational problems that arise when water and sand under high pressure are flowing from a. non- rotating flow channel into a rotating flow channel, riere in the form of the spindle tube, there is arranged at thie inlet of the spindle tube a spindle sub comprising a relatively short nipple tube. The nipple tube is preferably made from tungsten carbide. A nipple gasket encircling the nipple tube seals against the spindle tube.

The nipple gasket may with advantage be made from a synthetic material containing some glass. At its projecting portion the spindle tube is provided with a nozzle holder co-rotating with the spindle tube. The nozzle holder may be provided with one or more nozzles, the nozzles being assigned suitable directions of flow relative to the axis of rotation.

For example, the nozzles may be arranged in such a way that the jets from the nozzles will intersect at a distance from the nozzle holder. By adjusting the distance between the nozzle holder and the surface to be cleaned, it may be controlled how large a surface the jet is to cover, the jet being able to work in one point when said distance matches the distance of the point of intersection between the jets.

In another embodiment the nozzles may be placed ±n such a way that the reaction force from the out-flowing water helps to put the nozzle holder into rotation.

The relative portions of water and sand flowing out of the mixing unit can be adjusted by, among other things, adjusting the through-put of the first and the second control valves .

These control valves can, with advantage, be connected to a control system, in which water-sand ratios and also water pressure are pre-programmed, and in which the operator can easily select a program during the work.

It has turned out to be advantageous for the spindle tube and nozzle holder to rotate relatively fast during the work. Rotational speeds in the order of 3000 revolutions per minute have given good results .

Compared with the prior art, the invention contributes to an increased yield, reduced relative energy consumption, improved work environment and operator safety. In addition the invention represents a method which, when used sensibly, can be used also in explosion-hazardous areas .

In what follows is described a non-limiting example of a preferred method and embodiment which is visualized in the accompanying drawings, in which:

Figure 1 shows a plant for surface cleaning including a pump, a mixing unit and a cleaning gun;

Figure 2 shows a principle drawing of the mixing unit , arrows indicating flow directions;

Figure 3 shows a longitudinal section through the cleaning gun;

Figure 4 shows, on a larger scale, a section of the cleaning gun of Figure 3 ; and

Figure 5 shows a nozzle holder, in which the nozzles are placed in such a way that the jets from the nozzles will intersect.

In the drawings the reference numeral 1 identifies a plant for surface cleaning, including a pump 2 pumping water under pressure to a mixing unit 4 for water and sand, and a cleaning gun 6 connected to the mixing unit 4 by means of a feed hose 8.

In the mixing unit 4 there is placed a sand tank 10, see Figure 2. The sand tank 10 is provided with a filling opening 12 for sand.

Water from the pump 2 is supplied to the mixing unit 4 by way of a supply pipe 14. The water stream is then divided!, and a first water stream is directed to a first control valve 16, further to a preferably adjustable throat 18 and then on to the feed hose 8, these components forming a first flow path.

A second water stream is directed by way of a second control valve 20 and an inlet pipe 22 to the sand tank 10. From the bottom portion of the sand tank 10 sand and water are directed via an outlet pipe 24 into the first water stream upstream of the feed hose 8, the components 20, 22 and! 24, together with the sand tank 10, forming a second flow path.

The throat 18 is adjusted to produce a pressure drop in the first water stream, corresponding to the pressure drop experienced by the second water stream when flowing tb_rough, among other things, the sand in the sand tank 10.

The control valves 16 and 20 are used in order to set the relative flow rate through the sand tank 10 and may with advantage be connected to a control plant, not shown.

The cleaning gun 6 includes a gun housing 26, see Figure 3, a tube housing 28 projecting forwards from the gun housing 26 and a bearing housing 30 projecting rearwards from the gun housing 26. A grip 32 is provided with a trigger 34, t_he trigger 34, when operated, being arranged to start, via a not shown connection to the not shown control system, the supply of water and sand in a manner known in itself, through the feed hose 8. The grip 32 is connected to the gun housing 26.

During the cleaning work, a support 36 is arranged to loear against the operator's shoulder portion. The support 36 is also connected to the gun housing 26.

A rotatable spindle tube 38 extends through respective through bores 40, 42 and 44 of the bearing housing 30, the gun housing and the tube housing 28. The spindle tube is supported by means of bearings 46 in the bearing housing 30 and by a bearing 46' in the projecting end portion of the tube housing 28.

A driving motor 48 connected to the gun housing 26, drives the spindle tube 38 by means of a belt drive 50.

At its projecting downstream end portion the spindle tube 38 is connected to a nozzle holder 52 co-rotating with the spindle tube 38. The nozzle holder 52 is provided with nozzles 54 communicating with the spindle tube 38 via bores 56.

The feed hose 8 is connected by means of a nipple 58 to a through-bore nipple tube holder 60, see Figure 4. The nipple tube holder 60 is connected to the bearing housing 30 by mans of threads 62.

A nipple tube 64, concentric to the spindle tube 38, is placed sealingly, by means of a gasket 66, in a bore 68 of the nipple tube holder 60. A locking washer 70 prevents the nipple tube 64 from being pushed out of the nipple tube holder 60 during operation.

The nipple tube 64 projects into the spindle tube 38 and is sealingly encircled by a nipple gasket 72 sealing against the bore 74 of the spindle tube.

A protective sleeve 76 encircles the connection of the feed hose 8 to the cleaning gun 10, see Figure 3.

When the spindle tube 38 rotates, the nipple gasket 72 rotates on the nipple tube 64, preventing water and sand from penetrating into the bearing housing 30. When the trigger 34 is operated, water flows in from the pump 2 through the supply pipe 14 and is divided into two streams of water, the relative flow rates depending on the setting of the control valves 16, 20. The first water stream is directed through a throat 18, whereas the second water stream flows via the inlet pipe 22 to the sand tank 10. In. the sand tank 10 the water entrains sand before flowing out through the outlet pipe 24 and then being directed into tlie first water stream before water and sand flow to the cleaning gun 6 via the feed hose 8.

In the cleaning gun 6 water and sand flow in through the nipple tube holder 60 and the nipple tube 64 to the rotating spindle tube 38. From the spindle tube 38 the water and sand flow on through the bores 65 and nozzles 54 to the not shown surface, which is to be cleaned.

Claims

C L A I M S

1. A surface cleaning method, in which an abrasive agent is mixed with a fluid before the mixture is jetted against the surface to be cleaned, the mixture flowing through a rotating nozzle holder (52), cha r ac t e ri z ed i n that the abrasive agent and the fluid are mixed before flowing, together, through one feed hose (8) to the rotating nozzle holder in a hand-held cleaning gun (6) .

2. A surface cleaning device (1) including a pump (2) and a rotating nozzle holder (52), in which the rotating nozzle holder (52) is arranged to work with a cleaning medium comprising an abrasive agent and a fluid, charac t er i z ed in that a feed hose (8) for abrasive agent and fluid extends from a mixing unit (4) for abrasive agent and fluid to the rotating nozzle holder (52), the feed hose (8) forming the only hose connection to the rotating nozzle holder (52).

3. A device in accordance with claim 2, charac - t er i z e d in that the rotating nozzle holder (52) forms part of a hand-held cleaning gun (6) .

4. A device in accordance with claim 2, c ha rac t er i z ed in that the nozzle holder (52) is connected to a supported spindle tube (38) .

5. A device in accordance with claim 4, cha r ac t er i z ed in that the spindle tube (38) is rotated by a driving motor (48) via a belt drive (50) .

6. A device in accordance with claim 5, charac t er i z ed i n that a fluid connection between the feed hose (8) and the spindle tube (38) includes a nipple tube (64), the nipple tube (64) being sealingly encircled by a nipple gasket (72) .

7. A device in accordance with claim 2, charac - t er i z ed in that the mixing unit (4) includes an abrasive agent tank (10) , the supply pipe (14) being connected to a first flow path (16, 18) bypassing the abrasive agent tank (10) and a second flow path (20, 22, 24) extending via the abrasive agent tank (10) , the flow paths (16, 18 and 20, 22, 24) being connected to each other upstream of the feed hose (8) .

8. A device in accordance with claim 2, charac t e r i z ed in that the nozzle holder (52) is provided with nozzles (54) , the extensions of the longitudinal axes of the nozzles (54) intersecting each other.