AU685806B2

AU685806B2 - Furnace vacuum cleaning device

Info

Publication number: AU685806B2
Application number: AU67497/94A
Authority: AU
Inventors: Alastair Clark
Original assignee: DYNAMIC CLEANING SERVICES Pty
Current assignee: DYNAMIC CLEANING SERVICES Pty Ltd
Priority date: 1994-07-14
Filing date: 1994-07-14
Publication date: 1998-01-29
Anticipated expiration: 2014-07-14
Also published as: AU6749794A

Description

P/00/011~ Regulation 3.2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

TO BE COMPLETED BY APPLICANT

I

*es.

S..

Name of Applicant: Actual Inventor(s): Address for Service: Invention Title: DYNAMIC CLEANING SERVICE PTY LTD cR/

REG

ALASTAIR CLARK @22.10 (2)a, Patent and Trade Mark Attorneys T O FURNACE VACUUM CLEANING DEVICE The following statement is a full description of this invention, including the best method of performing it known to us:- This invention relates to the general field of high temperature engineering. In particular the invention relates to a cleaning device capable of operating in very hot environments such as inside a furnace.

BACKGROUND ART It is generally accepted that high temperature furnaces must be periodically shut down and allowed to cool so that cleaning and maintenance work can occur. For large, continuous production furnaces, such as those used in steel production, the cost of lost production during a shut down can be upwards of million. In some cases these shut downs need to occur every 3 to 4 months 10 and therefore may cost up to $100 million annually.

One example of such a furnace is a reheat furnace used to raise steel billets to a Z. temperature suitable for hot forming. A typical billet is 3 to 4 metres long with a 50 centimetre by 70 centimetre cross-section. The reheat furnace raises the temperature of the billets from ambient to approximately 1600'C during a 12 to 15 24 hour transit of the furnace.

seto Heating of the billet causes a scale to form on the billet during reheating.

Billets formed from older single cast methods have a scale layer that comes away from the billet as granules and small sheets. Reheat furnaces have been designed with an arrangement of slots at the bottom of the furnace below F. 20 which are water screens. The scale falls off the billets and down through the ~slots. It is cooled flushed out, collected and disposed of.

Billets formed by a continuous cast process do not loose the scale layer in granules but rather it falls off in sheets. The sheets of scale cannot fall through the slots so instead sit on the bottom of the furnace. The scale can collect to a degree that it adversely affects the operation of the furnace. With the old style billets the reheat furnace needed to be shut down and cleaned about every 12 to 18 months. The new style billets result in the reheat furnace needing to be cleaned about every 3 to 4 months. Shut down of furnaces at this frequency can lead to major insulation refractory damage. There is a clear need for a device that can remove the sheets of oxide from the furnace without the need to cool the furnace.

A similar problem arises with blast furnaces. The inside of a blast furnace must be periodically scraped and cleaned and relined every 10 to 12 years. This is 1- conventionally done by cooling the blast furnace to a telnperature that a man L 'j 3 can work in. A large hole is cut in the side of the blast furnace and men enter the furnace to remove the rubbish. Cooling a blast furnace may take several weeks and the cost in lost production may be tens of million of dollars. A device that could be used to remove the slag and residue waste material at a much higher temperature would shorten the process thereby allowing access to the furnace for maintenance and saving costs due to lost production.

OBJECT OF THE INVENTION One object of the present invention is to provide a cleaning device that can remove material from a high temperature environment, such as within a 10 furnace.

A further object is to provide a device that can break up material within a furnace.

A still further object is to provide furnace operators with an alternative to shutting down a furnace for cleaning.

15 Other objects and advantages will become clear from the following discussion.

DISCLOSURE OF THE INVENTION In one form, although it need not be the only or indeed the broadest form, the invention resides in a vacuum cleaning device comprising a venturi pump adapted to generate a vacuum by directing fluid at high velocity into a venturi; a suction tube having one end in vacuum connection with the venturi pump and another end adapted to collect material from the high temperature environment; a cooling jacket surrounding a portion of the suction tube, said portion including the end adapted to collect material from the high temperature environment.

In preference the end of the device is provided with a shovel tip to assist in collection of the material. The shovel tip may be a separate element which is attached to the end of the tube by a thread, an interference fit, a welded seam or some other suitable manner. Alternatively the shovel tip may be integrally formed with the end of the suction tube.

4 To assist with cleaning of the bore of the suction tube it is preferably formed in two halves that are separable. One half incorporates the cooling jacket.

Alternatively the suction tube may be formed as an integral piece, In preference the vacuum cleaning device further comprises a breaking jet incorporated in the end of the suction tube, The breaking jet being in fluid contact with a source of fluid at high pressure and adapted to direct a high pressure stream of fluid at material in the high temperature environment.

The purpose of the high pressure stream of fluid is to break large pieces of material into smaller pieces which will fit through the suction tube.

ee

Q

10 In preference the vacuum cleaning device further comprises a clearing jet incorporated in the end of the suction tube. The clearing jet being in fluid eS contact with a source of fluid at high pressure and adapted to direct a high pressure stream of fluid at material within the end of the suction tube.

Some pieces of material can become stuck in the mouth of the suction tube if 15 they have a diameter greater than the diameter of the bore of the suction tube.

The purpose of the clearing jet is to direct a high pressure stream of fluid at the blockage and break it into smaller pieces.

Material collected by the device is ejected from the venturi pump at high velocity. The material has considerable kinetic energy and is quite abrasive. In preference a buffer means is located downstream from the venturi pump. The buffer means absorbs much of the kinetic energy of the collected material.

In a further form, the invention resides in a method of removing material from a high temperature environment including the steps of: inserting a suction tube into the high temperature environment, said suction tube incorporating a cooling jacket adapted to cool an end of the suction tube in the high temperature environment; generating a vacuum in a venturi pump by directing fluid at high velocity into a venturi; generating suction in the suction tube by locating one end of the tube in vacuum connection with the venturi pump; and applying the suction to the material to be removed by positioning another end of the tube adjacent the material to be removed.

In preference the method further includes the steps of breaking up the material by directing a jet of high pressure fluid at the material and clearing blockages of the tube by directing a jet of high pressure fluid at the blockage.

BRIEF DESCRIPTION OF THE DRAWINGS To further assist in understanding the invention reference will be made to the following drawings in which: FIG 1 is a cross-sectional side view of a first embodiment of a vacuum cleaning device; FIG 2 is a cross-sectional side view of the vacuum cleaning device of FIG 10 1 with the addition of a shovel tip; FIG 3 is an enlarged cross-sectional view of an end of a second embodiment of a vacuum cleaning device showing a clearing jet; FIG 4 is an enlarged cross-sectional side view of an end of a third embodiment of a vacuum cleaning device showing a clearing jet and a breaking jet; FIG 5 is a sectional end view of the vacuum cleaning device of FIG 4 taken through AA; FIG 6 is a sketch of a fourth embodiment of a vacuum cleaning device; FIG 7 depicts the method of operation of the vacuum cleaning device.

DETAILED DESCRIPTION OF THE DRAWINGS Referring now to the drawings in detail there is shown in FIG 1 a vacuum cleaning device generally depicted as 1. The device consists of a venturi pump 2 and a suction tube 3. The venturi pump 2 has a water inlet port 4 and water jets 5. Water sprays from the jets into a venturi 6 and entrains air thereby generating a low pressure region in the venturi. The theory of the venturi pump is well known to those skilled in the art.

The suction tube 3 is approximately 6 metres long in the preferred embodiment. This length is chosen to suit the application of the vacuum cleaning device in a reheating furnace and is not due to a limitation on the vacuum generated by the venturi pump. The end of the suction tube is the only part of the cleaning device that enters the furnace (refer Fig the venturi 6 pump is outside the furnace. To prevent the suction tube from melting it is surrounded by a cooling jacket 7. In the preferred embodiment water is used as the coolant. In specific applications other fluids may be more appropriate as coolants.

The cooling jacket 7 has a water inlet port 8 and water exit port 9. The water inlet port 8 is connected to a pipe 10 within the cooling jacket 7. The pipe delivers water to the distal end of the suction tube 3. The water flows through the cooling jacket 7 and out exit port 9. It is important that the entry and exit ports are as far apart as possible to ensure that fluid flows through the entire 10 cooling jacket so as to cool the part of the suction tube working in the furnace.

Pieces of scale that have fallen from a billet are picked up by the suction tube 3 under the influence of the suction generated by the venturi pump 2 and are carried out of the furnace. The water in the venturi has the added feature of cooling the scale so that it can be easily handled.

15 In one preferred embodiment the part of the suction tube with the cooling jacket is formed separately from the rest of the device and connected by a threaded section to the rest of the device. This facilitates cleaning of the bore 11 of the suction tube. In an alternative arrangement the suction tube is formed as an integral whole as shown in FIG 7.

Some of the scale may be difficult to collect so in a second embodiment of the V invention shown in FIG 2 a shovel tip 15 is provided on the end of the suction tube 3. The L.loivel tip 15 may be a solid metal piece attached to the suction tube (such as shown in FIG 2) or may be integrally formed (such as shown in FIG 3, 4 and The shovel tip 15 can be used to scrape scale material into the mouth of the suction tube 3. For most applications of the invention the embodiments of FIG 1 and FIG 2 are satisfactory. In some applications additional features are required.

In a third embodiment, shown particularly in FIG 3, a clearing jet 20 is incorporated into the tip 21 of the suction tube 3. The clearing jet 20 provides a high velocity water jet that can clear any blockages of the suction tube 3.

Blockages can be cleared by two mechanisms. Firstly, when the much cooler water contacts the super heated scale the sudden temperature gradient induced causes the scale to shatter. Since the scale generally falls from the billets in sheets this first function breaks the scale into sizes that can be handled by the suction tube 3.

Even after shattering there may be some pieces of scale that are too large for the suction tube. The second purpose of the clearing jet is to deliver a high velocity jet of water that is able to break large pieces of scale into smaller, manageable pieces. Water is delivered to the clearing jet 20 by high pressure pipe 22 located within the cooling jacket 7.

In a third embodiment of a vacuum cleaning device the suction tube 3 incorporates a clearing jet 30 and a breaking jet 31. The breaking jet 31 is recessed in the tip 32 of the suction tube 3. Water at high pressure is delivered to the breaking jet 31 by high pressure pipe 33. The purpose of the breaking jet 31 is to break up pieces of scale into manageable sizes which will fit through the bore 11 of the suction tube 3. As explained above, the breaking jet 31 provides a high pressure water jet which shatters and breaks large pieces of scale. A clearing jet 30 is slightly recessed and is directed into the bore 11 to clear any scale which lodges in the suction tube 3. Water at high pressure is delivered to the clearing jet by high pressure pipe 34.

As shown in FIG 5 the high pressure pipes 33 and 34 and the pipe 10 are located within the cooling jacket 7. The pipes 33, 34 and 10 assist in maintaining the separation of the sides of the cooling jacket 7.

In some applications the high pressure water jet delivered from the breaking jet may not be sufficient to break up material to be removed from the furnace.

In this case a water jet cutter can be used before the vacuum cleaning device.

The inventor has found that known water jet cutters are suitable as long as a cooling jacket is provided around the portions entering the furnace and the nozzle is repacked with suitable high temperature grease.

A sketch of a fourth embodiment of a vacuum cleaning device is shown in FIG 6. This embodiment includes a shovel tip 15 incorporating a breaking jet 31.

The cut-away portions of the figure clearly show the arrangement of the high pressure pipe 33 and the cooling water inlet pipe 10. An inlet port 35 is shown for the high pressure pipe 33. The pipes 10 and 33 are arranged diametrically opposite to provide support for the sides of the cooling jacket 7.

The method of use of the vacuum cleaning device is depicted in FIG 7. The device is somewhat bulky and requires two person operation (although mechanical assistance could be provided). Scale 40 is removed from the bottom of a furnace 41 by the vacuum cleaning device 1. Access is gained through apertures 42 in the furnace wall 43. Burner ports are suitable apertures for l" T O 8 access however' not all scale will be able to be removed because of the restrictions to access. It is preferable if apertures are provided near the base of the furnace wall.

As mentioned earlier, only that part of the suction tube that is water cooled enters the furnace. Water is provided to the cooling jacket by hoses 44 and to the venturi pump by hose 45. The suction generated by the venturi pump is sufficient to propel the scale and water over a hundred meters beyond the end of the device. Furthermore, the scale is abrasive so special precautions must be taken to collect the material ejected from the pump. A buffer region 50 is 10 provided beyond the pump which absorbs the energy of the material leaving the pump and diverts the material into a tube 51 which goes to a disposal area.

Because the end of the vacuum cleaning device is cooled it can work in the furnace with the furnace at operating temperature. Furthermore, a positive draft occurs at the aperture 42 so that the heat impacting the workers 52 is not excessive. Nonetheless, protective equipment is necessary.

Throughout the specification the intention has been to describe the invention without limiting it to any specific embodimen,. Specific reference has been made to embodiments of the invention designed for removing accumulated scale from the bottom of a reheat furnace. It will be appreciated that the invention is not limited to this application but is useful for removing material from any high temperature environment. Those skilled in the art will be able to conceive of variations on the specific embodiments described without departing from the spirit of the invention.

Claims

1. A vacuum cleaning device for removal of material from a high temperature environment including: a venturi pump adapted to generate a vacuum by directing a first fluid at high velocity into a venturi; a suction tube in vacuum connection with the venturi pump and a free end adapted to collect material from the high temperature environment, to thereby draw the material into the venturi pump to be carried away with the first fluid; a cooling jacket surrounding a portion of the suction tube, said portion including the end adapted to collect material from the high temperature environment.

2. The vacuum cleaning device of claim 1 further including a shovel tip to assist in collection of the material to be removed, said shovel tip being attached to or integrally formed with the free end of the suction tube.

3. The vacuum cleaning device of claim 1 or 2 in which the suction tube is formed in two parts, one of the two part incorporating a cooling jacket, and in which the two part are separable.

4. The vacuum cleaning device of claim 1 or 2 further comprising a breaking jet incorporated in the free end of the suction tube, said breaking jet being in fluid contact S 20 with a source of second fluid at high pressure and directed outwardly from the free end :i of the suction tube to direct a high pressure stream of fluid at material in the high temperature environment.

The vacuum cleaning device of claim 1 or 2 further comprising a clearing jet S•.incorporated in the free end of the suction tube, said clearing jet being in fluid contact with a source of a third fluid at high pressure and directed inwardly from the free end of the suction tube to direct a high pressure stream of fluid at material within the end of the suction tube.

6. The vacuum cleaning device of claim 1 or 2 further comprising a breaking jet and a clearing jet incorporated in the free end of the suction tube, said breaking jet being in fluid contact with a second source of secund fluid at high pressure and directed outwardly from the free end of the suction tube to direct a high pressure stream of fluid W at material in the high temperature environment and said clearing jet being in fluid contact with a source of fluid at high pressure and directed inwardly from the free end of the suction tube to direct a high pressure stream of fluid at material within the end of the suction tube.

7 The vacuum cleaning device of claim 1 or 2 further comprising a buffer means located downstream from the venturi pump and adapted to absorb kinetic energy from material collected by the vacuum cleaning device.

8. The vacuum cleaning device of claim 1 or 2 wherein the buffer means is a bore in line with and downstream of a flow path of the material and fluid directed by the venturi pump.

9. A method of removing material from a high temperature environment including the steps of: inserting a suction tube into the high temperature environment, said suction tube incorporating a cooling jacket adapted to cool an end of the suction tube in the high temperature environment; generating a vacuum in a venturi pump by directing a first fluid at high velocity into a venturi; generating suction in the suction tube by locating the tube in vacuum connection with the venturi pump; 20 applying the suction to the material to be removed by positioning a free end of the tube adjacent the material to be removed; and carrying the material to a disposal depot with the first fluid downstream of the venturi pump.

10. The method of claim 9 further including the step of breaking up the material by directing a high pressure breaking jet of a second fluid at the material.

11. The method of claim 9 further including the step of clearing blockages of the tube by directing a high pressure clearing jet of a third fluid at the blockage.

12. The method of claim 9 further including the steps of breaking up the material by directing a high pressure breaking jet of a second fluid at the material and clearing 30 blockages of the tube by directing a high pressure clearing jet of a third fluid at the blockage.

13. A method of removing material from a high temperature environment as herein described with reference to the attached drawings. I L0I) (ITQS... 11

14. A vacuum cleaning device as herein described with reference to the attached drawings. DATED this 16th day of September 1997 DYNAMIC CLEANING SERVICES PTY LTD By their Patent Attorneys A.P.T. Patent and Trade Mark Attorneys *0: *go• 4** *o* 0 *3 ABSTRACT A device for removing material from a high temperature environment comprises a venturi pump connected to a suction tube which has a cooling jacket surrounding a portion of the tube that enters the furnace. The end of the suction tube is located adjacent the material to be collected which is sucked into the tube under the influence of the vacuum generated by the venturi pump. High pressure fluid jets are provided to break the material into small pieces and to clear blockages of the tube. The device is useful for removing scale and other waste from the bottom of a furnace. .oo. °o o• ooo• .°ooee e•. 0*