GB2403197A

GB2403197A - Package for lubrication of sliding gate valve plates

Info

Publication number: GB2403197A
Application number: GB0314609A
Authority: GB
Inventors: Clive Lacey
Original assignee: FUCHS LUBRITECH
Current assignee: FUCHS LUBRITECH
Priority date: 2003-06-23
Filing date: 2003-06-23
Publication date: 2004-12-29
Also published as: GB0314609D0

Abstract

A lubricant package contains or incorporates a lubricant such as graphite, the package being formed by, or including a component formed by, a material which will metamorphose when subjected to an elevated temperature to release the lubricant. As shown, the package comprises a hollow ball 2, 3 of plastics material which contains a sachet 7 including a liquid lubricant. It may be located against refractory stones or elements of a sliding gate valve controlling flow of molten metal, the hot valve components causing the ball to melt. Alternatively, the outer component may be of cellulose material such as cardboard or papier mache which will char or burn to release the lubricant, or the entire package may be formed of a material such as a petroleum wax which incorporates the lubricant and will melt.

Description

PATENTS ACT 1977 P17630GB - NHF/ns

DESCRIPTION OF INVENTION

"IMPROVEMENTS IN OR RELATING TO THE LUBRICATION OF A

SLIDE GATE VALVE REFRACTORY PLATES FOR CONTROLLING

THE FLOW OF MOLTEN METAL" THE PRESENT INVENTION relates to the lubrication of the refractory inserts, stones or plates a slide gate valve for controlling the flow of molten metal.

It is necessary to control the flow of molten metal, such as steel, when metals are being refined or processed. In a flow control system as found in a metal processing plant, such as a steel making plant, there may be various sliding valves, which may be termed "gate valves", which incorporate refractory plates which are capable of withstanding high temperatures. Such gate valve systems may be found, for example, in a converter or a furnace and may be termed a tap hole gates. When mounted on a ladle such a gate valve may be termed as ladle slide gate.

In a typical gate valve there are two refractory inserts with abutting faces. The refractory plates slide relative to each other with the face of one plate moving relative to the face of the other plate. It is common practice to apply lubricants to the adjacent sliding faces of the refractory plates, prior their insertion within the various valve mechanisms. However, subsequent "in service" lubrication is either impossible, due to reasons of restricted access, or must be carried out using specialized air atomising spray equipment powered by an external source of compressed air. It is to be appreciated that it is difficult to apply any lubricant to the abutting faces of the refractory plates since these faces are inaccessible. It is desired to be able to prolong the life of the refractory plates, and thus it is desired to be able to lubricate the plates when in position.

The present invention seeks to provide an improved method for applying I a lubricant to the surfaces of refractory plates as present in a gate valve. The invention also relates to a refractory plate lubricant package for use in performing the method.

According to this invention there is provided a refractory surface lubricant package, the package containing or incorporating a lubricant, the package being formed by, or including a component formed by, a material which will metamorphose when subjected to an elevated temperature to release the lubricant.

The word metamorphose is used broadly to cover any change of state including melting, thus changing from a solid phase to a liquid phase, and also charring or burning.

It is to be appreciated in preferred embodiments of the invention the package is formed by, or includes a component formed, a material which will metamorphose when subjected to an elevated temperature in excess of 300 C, but which will not metamorphose at ordinary ambient temperatures. However, t in one embodiment of the invention, the package may include a material which melts. In this embodiment the package would initially be provided at a very low temperature, that is to say a temperature below 0 C, and would melt when subjected to an elevated temperature which is above 0 C.

With the exception of the embodiment where a frozen material is utilised it is preferred that the material which will metamorphose when subjected to an elevated temperature will not metamorphose at room temperature and, most preferably, will not metamorphose until subjected to a temperature in excess of 100 C. In a preferred embodiment the material will not metamorphose until even higher temperature thresholds are reached.

Conveniently the component of the package is an element that melts when subjected to said elevated temperature.

Preferably the element that melts is an element that is formed of a polymer.

Advantageously the polymer is polypropylene or polyethylene.

Alternatively the component of the package is a component that chars or burns.

Conveninently the component is formed of a cellulose based material.

Preferably the component is formed cardboard or papier macho.

In a preferred embodiment the package is in the form of a hollow container, the container containing a sachet, the sachet containing the lubricant.

Preferably the lubricant is contained in an invert emulsion of water and oil, or water and residual hydrocarbon material.

Conveniently the invert emulsion contains between 30% and 40% water.

Advantageously the emulsion is a rape oil emulsion.

In an alternative embodiment of the invention the entire package is t formed of a material which will melt when subjected to an elevated temperature, the material incorporating the lubricant.

Conveniently the material is a petroleum wax.

Alternatively the material is a frozen material.

Advantageously the lubricant is graphite.

Conveniently the lubricant incorporates an antioxidant.

Preferably the antioxidant is a metal.

Conveniently the antioxidant is aluminium.

A package in accordance with the invention may be provided with an anchor to restrict the distance of travel within a bore.

Conveniently the anchor is an elongate flexible element with a terminal cross piece.

The invention also relates to a method of lubricating a sliding gate valve for controlling the flow of molten metal which incorporates a refractory surface, the sliding gate valve having a fixed plate and a sliding plate, the sliding plate having an outlet spigot defining a collector bore, the method comprising the steps of positioning the sliding plate so that the collector bore is aligned with part of the fixed plate and introducing to the collector bore a package of the type described and positioning the package adjacent the fixed plate, permitting the package to metamorphose to release the lubricant.

The method may additionally comprise the subsequent step of slidably l moving the slideable plate, thus assisting in the spreading of the lubricant.

In order that the invention may be more readily understood, and so that further features thereof may be appreciated, the invention will now be described, by way of example, with reference to the accompanying drawings in which: FIGURE 1 is a perspective view of a package containing a lubricant; FIGURE 2 is an exploded view of the package of Figure 1; FIGURE 3 is a view of the sliding gate valve on a converter, when in the open position; FIGURE 4 is a view of the gate valve of Figure 3 when in the closed position illustrating the lubrication of the gate valve; and FIGURE 5 is a view corresponding to Figure 4 illustrating a modified form of package.

At this stage it is to be understood that the present invention provides a package, containing a lubricant, for example, in the form of high purity graphite, and the package is intended to be brought into contact with part of a slide gate valve whilst the slide gate valve is at an elevated temperature. The package, in response to the high temperature, is designed to metamorphose or change its condition so that the lubricant is released, the lubricant then being applied to the appropriate parts of the gate valve.

Figures 1 and 2 illustrate the package containing a lubricant. The package is in the form of a hollow container in the form of a spherical ball 1.

The spherical ball 1 is a ball formed of two substantially semi-spherical hollow shells 2, 3. The shells are configured to be joined together by a snap action between the rim 4 of the shell 2 and the rim 5 of the shell 3. However, the shells may, in alternative embodiments, be interconnected by a screw connection. The shells are formed of a polymer material, the preferred polymer being polypropylene or polyethylene. Each shell has a thickness of approximately 1 mm. One shell is provided with a vent opening 6, although both shells may be provided with a vent opening if desired.

Contained within the hollow interior of the ball as defined by the shells 2,3 is a sachet 7 again formed of a polymer material. In some embodiments the sachet may be a sealed plastic bag. Contained within the sachet is an invert emulsion of water and oil, the emulsion consisting of less than 50% water, the preferred emulsion containing between 35% and 40% water. The oil of the emulsion is, in the described embodiment of rape oil, which is an oil which has a high flash point and which is non-toxic. However, other oils or residual hydrocarbon materials may be utilised.

The oil includes a lubricant in the form of high purity graphite. The emulsion, in the described embodiment, also contains an anti-oxidant component to help minimise oxidation of the graphite, the anti-oxidant being in the form of a metal. Whilst metals such as bronze and lithium may be used the preferred metal is finely divided aluminium.

to The sachet may contain at least 100 ml of emulsion and the ball may have a diameter of lOO mm or less.

Referring now to Figure 3 of the accompanying drawings it is to be understood that the ball l as shown in Figures l and 2 is intended for use in lubrication components of a gate valve, such as the gate valve shown in Figure 3. The gate valve shown in Figure 3 forms part of a system intended to handle a flow of molten metal, such as steel.

Referring now to Figure 3 in more detail, a gate valve lO is illustrated, the gate valve 10 being associated with a vessel 11 which, in use, contains molten steel. The vessel 11 comprises an outer steel shell 12 with an inner refractory lining 13, the inner refractory lining 13 defining a channel 14 through which molten metal may leave the vessel. The gate valve comprises of fixed or back plate 15 which defines a front face 16. A recess 17 is provided in the front face 16 and a refractory element or "stone" 18 is located within the recess.

The stone 18 may include a zirconia insert in a body of castable material such as an aluminium oxide-based-cement, but any type of refractory element or stone may be utilised. The refractory element or stone 18 has a front face 19 which is co-planar with the front face 16 of the fixed plate 15. The fixed plate and the stone 18 together define an extension of the channel 14 in the form of a bore 20 which leads from the channel 14 to the front face 16.

An outer sliding plate 21 is provided which has a flat face 22 which abuts with the flat face 16 of the inner or fixed plate 15. A recess 23 is formed in the flat face 22 of the sliding plate 21, and the recess 23 accommodates a second refractory element or stone 24 which corresponds with the stone 18 described above. The stone 24 has a front face 25 which substantially abuts the front face 22 of the outer or sliding plate 21.

The outer or sliding plate 21 is provided with a tap outlet or "collector" formed by a downwardly extending hollow spigot which defines a bore 27.

The bore typically has a diameter in excess of 100 mm, being about 130 mm in this example. In the case of ladle gates the bore will be smaller. The bore 27 extends from the front face 25 of the stone 24n and may be termed a collector bore. I In one relative position of the outer or sliding plate 21 relative to the fixed plate 15, as shown in Figure 3, the bore 27 within the spigot 26 is co-aligned with the bore 20 in the fixed plate 15 and thus molten metal may i flow, as shown by the arrows 28, from the interior of the vessel l 1, through the tap outlet, or"collector".

The gate valve shown in Figure 3 is being used and consequently the initially flat faces of the refractory element or stones 18, 23 have become eroded in the regions 29, 30 where the bores 20 and 27 emerge into the flat faces of the inserts or stones.

It is to be understood that when the vessel 11 has been emptied of metal the gate valve will be closed by sliding the outer or sliding plate 21 to a position in which the bore 27 within the spigot 26 is no longer aligned with the bore 20.

The valve is thus closed, but, when the valve is closed it is conventional for a furnace vessel to be rotated to a position in which the spigot 26 is inclined upwardly at an angle to the horizontal, that angle typically being about 10 .

This is the position of the gate valve as shown in Figure 4. When the gate valve has been recently closed, the gate valve will have a very high temperature typically in excess of 400 C.

The gate valve described above is a conventional linear slide gate valve.

Figure 4 illustrates a ball 1, of the type described with reference to Figures 1 and 2, being introduced to the collector bore 27 within the spigot 26.

Because of the inclination of the spigot 26 the ball will, in any event, tend to roll down the collector bore 27 and come into contact with the refractory element or stone 18 forming part of the back plate 15. Because the ball 1 is formed of shells which have a wall thickness of about 1 mm, the ball 1 will not melt during the brief period of time it takes to roll to a position in contact with the beck plate 15.

When the ball 1 is in this position, the ball will be subjected to a very high temperature, typically in excess of 400 C. Should air within the ball expand, the air will be able to vent through the aperture 6 without causing the ball to explode. The polymer shells 2, 3 of the ball will, due to the high temperature, melt. The inner sachet 7 will then be subjected to a high temperature and will, itself, melt. The invert emulsion containing the lubricant will thus be released and may tend to form a pool or puddle as shown in phantom, 31, at the lower corner of the collector bore 27. The emulsion may combine with the molten plastic material to form a mixture or solution which includes the graphite lubricant.

The water present in the invert emulsion may evaporate to provide a flame suppressant and cooling effect, but the generation of steam is not of an explosive nature. Any steam that is generated will be able to flow past any remaining parts of the ball l, since the ball 1 has a diameter which is less than a diameter of the bore 27, even when the ball is complete.

The lubricant released from sachet 7 is subjected to high temperature, and the graphite lubricant may thus tend to oxidise. However, if a metal, such as finely divided aluminium is present within the emulsion, the aluminium may be oxidised in preference to the graphite oxidising. Thus the presence of the aluminium helps ensure that there is only a minimum oxidation of the graphite.

The mixture or solution in the pool or puddle31 may, of itself, seep between the abutting faces of the fixed plate 15 and the sliding plate 21. It is believed that the mixture or solution formed by the combination of the molten plastic and the remaining components of the invert emulsion have good "spreading" properties and appropriate viscosity to deliver lubricant to the surfaces of the fixed plate 15 and the sliding plate 21, especially if the sliding plate 21 is moved, with a sliding action, whilst the gate valve is in the orientation shown in Figure 4.

It is thus to be understood by simply introducing a ball 1, as described in i Figures 1 to 3 into the tap hole or collector bore 27, when in the position in Figure 4, and by actuating the sliding plate 21, the appropriate components of the gate valve may be lubricated.

It has been found that very little flame is given off when lubricating a gate valve in the manner described above and thus the lubrication may be effected in a simple and easy manner. I Whilst the invention has been described with reference to one embodiment of the invention in which the lubricant is initially present within a ball made of a meltable material, it is believed that the lubricant may be incorporated in alternative forms of package. An inverted emulsion of the type described above, within a sachet, may be contained within a ball formed, for example, of cardboard or some other cellulose or paper-based material, such as papier macho. Such a material would burn or at least char when inserted into the collector bore 27 in the manner described with reference to Figure 4, thus releasing the lubricant from within the ball.

In a further embodiment of the invention the lubricant is incorporated within an homogenous material that constitutes the ball. The homogenous material may be a wax, such as a paraffin wax, which has a relatively low i melting point. In a further embodiment of the invention the ball may be formed from frozen emulsion of the type described above.

It is to be appreciated that in each of the embodiments described above the ball, when subjected to a high temperature, changes its condition or metamorphoses in some way, by melting or burning, so as to release the lubricant.

Whilst the invention has been described with reference to a spherical ball, that may roll down the collector or tap hole bore 27 within the spigot 26, the package containing the lubricant may have other forms, especially if different techniques are utilised to deliver the package to a point within the collector or tap hole bore 27 adjacent the back plate 15.

A modified form of package 1 is illustrated in Figure 5. The package 1 1 is provided with an anchor in the form of an elongate flexible element 31 provided with a terminal cross piece 32. The flexible element may be of flammable material such as, in a simple embodiment, string or cord, and the terminal cross piece may also be flammable, being made of, for example, wood although the cross piece may be of meltable material, such as a thermoplastic material.

The cross piece will have a length greater than the diameter of the collector or tap hole bore 27, and the elongate flexible string or cord will have a length less than the length of the collector or tap hole bore.

When the package 1 is introduced into the bore, the package will be able to move down the bore until further movement of the package is arrested, when the terminal cross piece 32 becomes jammed across the open end of the collector or tap hole bore 27. The package 1 will then be located adjacent, but slightly spaced from the fixed plate. The package will, however, be subjected to a sufficiently high temperature for the package to change its condition or metamorphose so as to release the lubricant.

In the present specification "comprises" means "includes or consists of" and "comprising" means "including or consisting of". i The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse I forms thereof.

Claims

CLAIMS: 1. A refractory surface lubricant package, the package containing

or incorporating a lubricant, the package being formed by, or including a component formed by, a material which will metamorphose when subjected to an elevated temperature to release the lubricant.
2. A package according to Claim 1 wherein the component of the package is an element that melts when subjected to said elevated temperature.
3. A package according to Claim 2 wherein the element that melts is an element that is formed of a polymer.
4. A package according to Claim 3 wherein the polymer is polypropylene or polyethylene.
5. A package according to Claim 1 wherein the component of the package is a component that chars or burns.
6. A package according to claim 5 wherein the component is formed of a cellulose based material.
7. A package according to Claim 6 wherein the component is formed cardboard or papier mache.
8. A package according to any one of the preceding Claims wherein the package is in the form of a hollow container, the container containing a sachet, the sachet containing the lubricant.
9. A package according to any one the preceding Claims wherein the lubricant is contained in an invert emulsion of water and oil.
10. A package according to any one Claims 1 to 8 wherein the lubricant is contained in an invert emulsion of water and residual hydrocarbon material.
11. A package according to Claim 9 or 11 wherein the invert emulsion contains between 30% and 40% water.
12. A package according to Claim 9 or Claim 11 wherein the emulsion is a rape oil emulsion.
13. A package according to Claim 1 wherein the entire package is formed of a material which will melt when subjected to an elevated temperature, the material incorporating the lubricant.
14. A package according to Claim 13 wherein the material is a petroleum wax.
15. A package according to Claim 14 wherein the material is a frozen material.
16. A package according to any one of the preceding Claims wherein the lubricant is graphite.
17. A package according to Claim 16 wherein the lubricant incorporates an antioxidant.
18. A package according to Claim 17 wherein the antioxidant is a metal.
19. A package according to Claim 18 wherein the antioxidant is aluminium.
20. A package according to any one of the preceding Claims provided with I an anchor to restrict the distance of travel within a bore
21. A package according to Claim 20 wherein the anchor is an elongate flexible element with a terminal cross piece.
22. A method of lubricating a sliding gate valve for controlling the flow of molten metal which incorporates a refractory surface, the sliding gate valve having a fixed plate and a sliding plate, the sliding plate having an outlet spigot defining a collector bore, the method comprising the steps of positioning the sliding plate so that the collector bore is aligned with part of the fixed plate and introducing to the collector bore a package according to any one of the preceding Claims, and positioning the package adjacent the fixed plate, permitting the package to metamorphose to release the lubricant.
23. A method according to Claim 20 comprising the subsequent step of slidably moving the slideable plate, thus assisting in the spreading of the lubricant.
24. A refractory surface lubricant package substantially as herein described with reference to and shown in Figure l and 2 of the accompanying drawings.
25. A refractory surface lubricant package substantially as herein described with reference to and shown in Figure 5 of the accompanying drawings.
26. A method of lubricating a sliding gate valve substantially as herein described with reference to the accompanying drawings.
27. Any novel feature or combination of features disclosed herein.