GB2237803A

GB2237803A - Ceramic welding nozzle

Info

Publication number: GB2237803A
Application number: GB8925487A
Authority: GB
Inventors: Colin John Jackson; Andrew Mcquarrie
Original assignee: Coal Industry Patents Ltd
Current assignee: Coal Industry Patents Ltd
Priority date: 1989-11-10
Filing date: 1989-11-10
Publication date: 1991-05-15
Also published as: GB8925487D0

Abstract

A ceramic welding nozzle has orifices (3) arranged at an angle at its end. The orifices are connected to a tube (6) through which a combustible fluid, such as, propane is injected to mix with welding particles entrained in air flowing through the body of the nozzle. <IMAGE>

Description

CERAMIC WELI)ENG NUZZLE This invention relates to a ceramic welding nozzle of the kind having a central bore through which particles and materials to be welded are arranged to pass entrained in a gaseous fluid.

Ceramic welding is used as ;t technique for repairing refractory surfaces, such as, th linings of glass ovens and coke ovens when fractures or fissures occur in the refractory lining of the ovens. The operation is usually carried out while the lining is still hot because of the need to minimise downtime and that some linings if allowed to cool can some more seriously cracked and faulted. However, on some occasions it is necessary to repair cold ovens and the linings, in such a case, are beneficially heated locally and it is necessary to apply a large degree of control to the heating process to avoid further damaging the lining.

In ceramic welding a stream Cf welding particles usually of a material, such as, a mixture of silica, aluminium and silicon is propelled in a stream of a gaseous fluid, preferably air, although in certain circumstances oxygen has been used although this is more dangerous and difficult to control. The particles are directed through a lance having a nozzle and the nozzle is held some distance from the area to b: welded. The particles impinge at a velocity on the area to be welded and if the area is already hot the particles fuse to form R weld in the area. If the area is a cold surface then extra heat has to be added at the point of the weld.This is a difficult p::ocess to control and it is an object of the present invention to provide an improved form of ceramic welding nozzle which enables better control than has hitherto been possible.

According to the present invention a ceramic welding nozzle, having a central bore through which particles of materials to be welded are arranged to pass entrained in a gaseous fluid, includes combustion means at or adjacent the outlet of the nozzle for the injection of a combustible fluid to the gaseous fluid.

The combustion means preferllbly comprise a plurality of outlet orifices directed in the direction of flow of the gaseous material. The orifices s are directed at an angle to the longitudinal axis of the nozzle and hence the axis of flow and this angle of direction is prefer:tbly between 50 and 300 to the axis.

The orifices may be mounted to be adjustable in their angle. The orifices are preferably set ct regular intervals on an annulus at or adjacent the outlet of the no::zle. The orifices may be incorporated into the outlet of the nozzle or alternatively may be incorporated into a separate col:ar surrounding the nozzle.

Means are provided to the nozzle for the external supply of the combustible fluid. This fluid is preferably gaseous, such as, propane, butane or acetylene. The fluid may however, be combustible liquid and preferably in such a case the fluid is entrained with the gaseous fluid in a droplet form.

The internal bore of the nozzle may be uniform in cross-sectional area or be tapered to an internal frusto-conical form with the narrower part oi the bore being at the outlet or the inlet of the nozzle.

In order that the inventions may be readily understood, one embodiment of a nozzle in accordance therewith for a ceramic welding lance will now be described with reference to Figure 1 of the accompanying drawings, and a modification of this nozzle is shown in Figure 2 of the drawings.

Referring now to the drawings, the nozzle comprises a tubular end piece 1 having at its outlet end a recessed portion 2 which has six orifices 3, of which only tWD are shown in the drawing, equally spaced in a form of an annulus. The orifices are connected to a recess 4 of annular form which surrounds the end of the end piece 1. A collar member 5 is welded to the end piece 1 to cover the recess 4 and the collar 5 has a tube 6 welded to it at 7 for the input of a combustible fluid.

The bore of the end piece comprises a frusto-conical section 8 and a parallel sided section 9. Section 9 has an internal screw thread for securing it to a lanc:e. The frustoconical section 8 tapers towards the recess portion 2 at the outlet end of the nozzle.

It can be seen from the drawing in Figure 1 that the orifices 3 are angled towards the longitudinal axis 10 of the nozzle at an angle of 300. Depending on the pplication this angle can be important and if reference 1 made to the modification shown in Figure 2 a variation is here shown where the angle is only 5 . In practice, the best performance of the angle depends on a number of parameters including the tempera ure being worked at in order to operate the welding system. The angle d does s control the position on the hot spot of the flame and will be dependent to some degree on the nature of material passing through the end piece and its velocity.In a variation not shown, the orifices 3 can be formed as jet nozzles which are mounted so as to be adjustable between limits within the end piece . These limits would be between the angles shown of 50 and 300.

In operation according to this example the nozzle is screwed to the end of a lance and th-:a lance supplies an entrained flow of particles of a mixture of silico:l, aluminium and silica grog along the access 10. There is a Venture effect by the frusto-conical section 8 which forces the particles out with a high velocity from the end of the nozzle. The particles are, in this example, entrained in air and a gaseous fluid, in this example, propane is supplied to the tube 6 and injected into the flow of air through the orifices 3. The air and propane are mixed and since the ceramic welding is usually done against a hot surface, combustion of the propane will take place assisted by the air. This will heat the particles with the substrate refractory being repaired so that a weld will be more readily formed. The use of the propane means that there is a very good contra over the temperature of the hot region where the welding is taking place. When migrating between areas the propane can be switche(:l on and off.

When a cold area is being treated it is possible to use the propane from the tube 6 as a pre-heating torch. Thus, the nozzle would not supply any silicon, aluminium or silica grog particles entrained in air but only oxygen which would mix with the propane.

This would be ignited and it would be used as a torch to pre-heat the area to be welded. When the area has reached a sufficient temperature the flow of particles can be introduced into the stream and welding can take place. Therefore, an extremely satisfactory and controllable degree of weld can be achieved easily.

The use of the propane from the tube 6 as a pre-heating torch is also beneficial when not linings are being repaired.

Pre-heating of the lining to its fusion temperature, or near to its fusion temperature, and then immediate introduction of the welding powder entrained in air will ensure a good interfacial and strong bond between substrate refactory and the repair.

Although propane has been referred to in this example any suitable combustible gas, such as, butane or acetylene may be used. In variation even a liquid fuel, such as, an oil preferably in droplet form is fed through the tube 6. The orifices would then produce a mist of oil droplets which would ignite.

Claims

1. A ceramic welding nozzle hazing a central bore through which particles of material to be welded are arranged to pass entrained in a gaseous fluid, and including combustion means at or adjacent the outlet of the nozzle for the injection of a combustible fluid to the gaseous fluid.

2. The nozzle as claimed in claim 1 in which the combustion means comprises a plurality of outlet orifices directed in the direction of the flow of the gaseous material.

3. The nozzle as claimed in claim 2 wherein the angle of direction of the orifices is between 50 and 300 to the longitudinal axis of the nozzle.

4. The nozzle as claimed in claim 2 or claim 3 wherein the orifices are set in an annulus at regular intervals and the orifices are integral with the outlet end of the nozzle.

5. The nozzle as claimed in any preceding claim wherein the combustion means is connected to an annular supply chamber external to the nozzle.

6. The nozzle as claimed in claim 2 or claim 3 in which the nozzle is provided with an external tubular collar and the orifices are formed in the collar.

7. The e nozzle as claimed in anìpreceding claim and including an external supply pipe for the com):ustible fluid.

8. A nozzle as claimed in any one of claims 2 to 7 in which the nozzles are individually mounted in an adjustable manner to enable the angle of direction to be altered.

9. A nozzle as claimed in any preceding claim in which the inlet bore of the nozzle is tapered t() an internal frusto-conical form with the narrowest part of the bore at the outlet end of the nozzle.

10. A nozzle as claimed in aT7 one of the preceding claims 1 to 8 in which the bore of the nozzle is tapered to an internal frusto-conical form with the narrowest part of the bore at the inlet end of the nozzle.

11. A nozzle as claimed in aly one of the preceding claims 1 to 8 in which the nozzle is of uniform cross-sectional area along its entire length.

12. A ceramic welding nozzle sutantially as hereinbefore described and with reference to Figure 1 or Figure 2 of the accompanying drawings.

13. A method of ceramic welding comprising directing in a stream of a gaseous fluid particles of materials to be welded through a nozzle as claimed in any preceding claim, and mixing with the gaseous fluid a combustible fluid fed to the gaseous fluid through the combustion means and igniting the mixture of the fluids.

14. A method as claimed in claim 13 wherein the combustible fluid is a gas.

15. A method as claimed in claim 13 wherein the gas is propane, butane or acetylene.

16. A method as claimed in claim 13 wherein the combustible fluid is a liquid.