GB2310037A

GB2310037A - Gas nozzle

Info

Publication number: GB2310037A
Application number: GB9602285A
Authority: GB
Inventors: Roger Shaun Lanary
Original assignee: Hamworthy Combustion Engineering Ltd
Current assignee: Hamworthy Combustion Engineering Ltd
Priority date: 1996-02-05
Filing date: 1996-02-05
Publication date: 1997-08-13
Also published as: GB9602285D0

Abstract

A gas nozzle comprises a housing provided with a gas inlet and a gas outlet 104 having an outlet aperture 105, and directional means 110 situated in the gas outlet 104. The orientation of the said directional means 110 is adjustable, for thereby controlling the direction in which gas is discharged from the outlet 104.

Description

GAS NOZZLE This invention relates to a gas nozzle. More particularly, but not exclusively. the invention relates to a gas nozzle suitable for use in a burner having a restricted NOy emission.

The control of NOx emissions and flame shape for a given burner or boiler furnace application depends very strongly on the precise spatial distribution and mixing of the fuel gas and the air supplied for combustion.

Fuel gas is typically introduced into a furnace through an array of so-called i'gas spuds' (or pokers9') which are located within a burner register. The discharge ends of the gas spuds terminate in a nozzle drilled with one or more orifices. The orifices are sized and located in such a way as to inject the correct amount of fuel gas with a velocity and direction believed to be that which will result in a requlred flame shape and with the minimum NOx emission.

Experience has shown that the critical parameters cannot always be optimised at the design stage. In such cases, it becomes necessary to optimise the configuration on site during installation. As each gas spud has a fixed geometry, it is necessary to provide a relatively large number of alternative configurations for on-site performance evaluation.

As a consequence of this evaluation, the installation of the gas spuds requires an often extensive breaking and re-making of gas-tight joints. These procedures can result in an extension of the installation period - with a commensurate (and often considerable) increase in costs.

The present invention sets out to provide a gas nozzle which has variable geometry.

thereby greatly facilitating installation procedures and enabling system optimisation in a fraction of the time previously possible.

According to a first aspect of the present invention there is provided: a gas nozzle comprising a housing provided with a gas inlet and a gas outlet having an outlet aperture, and directional means situated at the gas outlet; the orientation of the said directional means being adjustable in at least two directions which are not mutually opposite, for thereby controlling the direction in which gas is discharged from the nozzle.

This arrangement enables simple and effective adjustment of the geometry of the nozzle during installation. This enables the configuration of the system to be optimised very easily and quickly.

Preferred features of this aspect of the invention are set out in Claims 2 to 19.

A second aspect of the invention provides a gas burner as set out in one of Claims 20 to 22.

Preferred embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings in which: Figures la and lb are a cross-sectional view and an end view, respectively, of a first embodiment of a nozzle according to a first aspect of the invention; Figures 2a and 2b are a cross-sectional view and an end view, respectively, of a second embodiment of a nozzle according to the first aspect of the invention; Figures 3a and 3b are a cross-sectional view and an end view, respectively. of a third embodiment of a nozzle according to the first aspect of the invention; Figures 4a and 4b are a cross-sectional view and an end view, respectively of a fourth embodiment of a nozzle according to the first aspect of the invention;; Figures 5a and 5b are a cross-sectional view and an end view, respectively. of a directional sphere suitable for use in an embodiment of the invention; Figure 6 is a sectional view of a burner according to a second aspect of the invention incorporating nozzles in accordance with the first aspect of the invention; Figure 7 is an end view of the burner shown in Figure 6; and Figure 8 is an end view of the burner shown in Figures 6 and 7, viewed from the opposite direction to Figure 7.

Figures 6 to 8 show a burner 2 in accordance with the second aspect of the invention.

The burner 2 comprises a burner register provided with a central gas gun 4 radially surrounded by six gas spuds 6. As can be seen in Figure 7, the gas spuds 6 are all arranged at intervals of 60 on a virtual circle which has its centre at the centre of the gas gun 4. The gas gun 4 and the gas spuds 6 are supported, supplied with gas and arranged in a generally conventional manner and these details will not, therefore be discussed extensively. However, it will be noted that the gas gun 4 is supplied with gas via a generally L-shaped pipe 8 and each of the spuds 6 is supplied with gas via a respective pipe 10, which has a generally J"-shaped portion 12 at the gas supply end (which is shown towards the right of Figure 6). The end portions 12 are connected to a common radial manifold 14 which comprises a single inlet 16.

As can be seen from Figure 6, the discharge end of the burner 2 is mounted within the wall of a furnace 18 for use. An air casing 20 surrounds the burner in a region proximate to the furnace wall 18.

Each of the gas spuds 6 and the gas gun 4 comprise a nozzle in accordance with a first aspect of the invention. Embodiments of such a nozzle will now be described.

Figures 1 a and 1 b show a first embodiment of a nozzle in accordance with the invention. Each of the gas spuds 6 of the above-described burner may include such a nozzle.

The nozzle comprises an outer housing 102 which is generally cylindrical and has a radially inwardly directed flange 104 which defines a circular outlet aperture 105 of the housing 102. At its inlet end, the housing comprises a radially outer annular rebate 106.

which is configured to slot within the mouth of a gas supply pipe 10 to which the nozzle is fitted. The two are secured together by means of screws 108.

A spherical gas jet 110 is provided at the outlet end of the housing 102 and seats closely against the upstream side of the inner perimeter of the outlet aperture 105 by virtue of having a slightly greater diameter. The gas jet 110 is basically a steel ball which comprises an axial bore 112. The configurations of the gas jet 110 and the aperture 105 are such as to effect a good seal between the two, so that gas being discharged from the housing 102 may only pass through the bore 112 and not between the outer surface of the gas jet 110 and the radially inner perimeter of the flange 104.

Prior to fixation, the gas jet 110 can rotate and, therefore, the orientation of the bore 112 can be adjusted. As a consequence, the gas jet 110 defines a directional means, which can be used to control the direction of discharge of gas from the gas nozzle when secured in place. The degree of adjustment possible is great. This is because the orientation of the gas jet 110 is infinitely adjustable within the limitations enforced by the need for the gas to escape via the bore 112. There is no restriction of movement of the bore outlet within a single plane, or over a predetermined path, for example. because movement of the jet is angularly unconstrained. This freedom of movement of the bore therefore, offers unprecedented flexibility in selecting appropriate configurations.

A screw 114 is provided within a co-operatively threaded bore 116 provided in the housing wall. The bore extends completely through the wall of the housing 102 in a direction generally radial to the gas jet 110. Consequently, the screw can be tightened from the outside and brought into abutment with the surface of the gas jet 110. This secures the position of the gas jet 110 and, therefore, enables the direction of discharge of gas to be fixed.

Figures 2a and 2b show an alternative embodiment of a gas nozzle in accordance with the first aspect of the invention. This gas nozzle can be used in a gas spud 6 of the above described bumer 2 as an alternative to that shown in Figures la and lb. In this embodiment, a gas jet 210 is seated against an outlet aperture 205 of a housing 202 in the same manner as that of the first embodiment. It is used to direct gas discharge by virtue of a bore 212 in exactly the same way. However, the fixation of the orientation of the gas jet 210 is achieved in a different way. In this arrangement, the screws 108 and 114 are omitted, along with their associated details.Instead, the gas jet 210 is seated against, and secured in position by, a seating cylinder 214 which fits closely within the internal wall of the housing 202 and can be slid backwards and forwards in the axial direction (i.e. from left to right in Figure 2a). The cylinder 214 comprises a radially outwardly directed flange 216 which is of such a dimension as to enable it to abut an end face of the gas supply pipe 10. In this embodiment, the housing 202 also comprises a radially outwardly directed flange 206 at its inlet end, and a nut 208 which fits around the outer perimeter of the housing wall and has a radially inwardly directed flange 209 with a radially inner diameter smaller than that of the radially outer diameter of the flange 206.An end portion of the supply pipe 10 is provided with a thread of such a diameter as to co-operate with the thread of the nut 208.

The nut 208 serves a dual purpose. On the one hand it is used to fix the nozzle 6 to the end of the supply pipe 10. This is achieved by screwing the nut 208 onto the end of the pipe 10. On the other hand, the nut has the effect of securing the position of the gas jet 210. This is achieved as the housing 202 is tightened onto the pipe 10. because the flange 209 provided on the nut pulls the flange 206 provided on the housing 202 (and consequently the whole housing 202) towards the right in Figure 2a, whilst the axial position of the seating cylinder 214 remains stationary by virtue of its abutment against the end of the pipe.Consequently, the tightening of the nut serves to reduce the axial separation between the flange 204 and the seating end of the seating cylinder 214. with the effect that the gas jet 210 is gradually clamped between the two and eventually secured in position.

Figures 3a and 3b show a third embodiment of a gas nozzle according to the first aspect of the invention. This can nozzle can be used in the gas gun 4 shown in the gas bumer of Figures 6 to 8.

This nozzle employs the same principle as the previous two embodiments, i.e. the direction of gas discharge is controlled by use of spherical gas jets 310.

Eight gas jets 310 are provided in this case. These are arranged generally in the form of a circle.

The outlet end of the housing 302 is provided with eight outlet apertures 304, each of which acts as a seat for a respective one of the gas jets 310. In this case, the gas jets 310 are seated on the downstream side of the apertures 304, rather than the upstream side. as in previous embodiments. Despite this difference, the dimensions of the gas jets 310 and the apertures 304 are such as to provide a gas-tight seal therebetween, thus causing discharging gas to flow through bores 312 which are provided in the gas jets 310.

The gas jets 310 are clamped in position by means of a clamping plate 314, which is applied to the discharge end of the housing 302. The clamping plate 314 is provided with eight apertures 316, each of which has a diameter slightly smaller than that of the gas jets 310. In addition, the clamping plate comprises a central aperture 315 which receives a clamping screw 309 which can be screwed into a co-operatingly threaded axial blind bore 311. which is provided in the discharge end of the housing 302.

To secure the gas jets 310 in position, the clamping plate is fitted to the discharge end of the housing 302 with each aperture 316 sitting over a respective one of the gas jets 310.

The clamping screw 309 is inserted through the aperture 315 and screwed into the blind bore 311. As the screw 309 is tightened, the clamping plate 314 presses the gas jets 310 into the apertures 304, with the effect that each of the gas jets 310 is eventually clamped in position between opposed seats defined by a respective one of the apertures 315 and a respective one of the apertures 304.

The housing 302 is fixed to the end of the gas supply pipe 8 by welding at the junction 350 between the two.

Figures 4a and 4b show an arrangement which is generally similar to that of Figures 3a and 3b. The primary difference is that the discharge end face of the housing 302 comprises a frustoconical annular surface 303 and the discharge apertures 304 are arranged in a circle within this surface. The frustoconical surface 303 has an angle of inclination of about 30 to the longitudinal axis of the housing 302. To enable the gas jets 310 to be clamped effectively, the clamping plate 314 comprises a correspondingly frustoconical surface 313.

In each of the above-described embodiments of the first aspect of the invention, the or each gas jet comprises a simple bore for the discharge of gas. However, if desired, a jet plate 514 can be fitted within the bore. This is shown in Figures 5a and 5b.

As in the previous embodiments, the gas jet of Figures Sa and Sb is spherical and comprises a bore 512. However, the diameter of the bore is broadened at the discharge end. to define an annular, axially facing shoulder 516. The discharge plate 514 has a circular perimeter with a diameter corresponding to that of the portion of enlarged diameter 513. It is provided with five fine jet holes 518, through which the gas is discharged.

The jet plate 514 is retained in position by virtue of a C-clip 520 which expands into an annular groove 522 provided in the wall of the enlarged portion 513 of the bore. Thus the jet plate 514 can be removed and replaced with one having a different pattern of orifices with whatever configuration, number and size that is desired. This enables these variables to be tested without the need to completely replace the spherical jets thus avoiding the need for re-alignment.

Many further modifications and variations will suggest themselves to those versed in the art upon making reference to the foregoing description, which is given by way of example only and is not intended to limit the invention, the scope of which is determined by the appended claims.

In particular, it is to be understood that the invention can be applied to any appropriate type of gas and/or oil burner, in which any appropriate number of spuds and/or guns can be used. These, of course, can be arranged in any appropriate configuration.

Furthermore, a gas gun in accordance with the invention can include any appropriate number of gas jets arranged in any appropriate configuration and clamped in place by any suitable means. It is not necessary for every nozzle to be the same.

Whilst the above-described arrangements provide a freedom of adjustment which is found to be particularly advantageous, it is to be understood that alternative embodiments of the invention could be configured such that the jet is replaced by a mechanism having more limited movement. For example, whilst the jets of the abovedescribed embodiments have completely unconstrained rotation, the rotation could be restricted (by a suitable flange, for example) to a range in which the bore ends cannot be covered or blocked by other parts of the nozzle in such a way as to restrict gas flow.

Alternatively, the spherical jet could be replaced by a component having movement which is angularly constrained. As long as the directional means is capable of movement in two directions which are not mutually opposite, a wide range of orientation and hence gas discharge directions will be available.

Claims

1. A gas nozzle comprising a housing provided with a gas inlet and a gas outlet having an outlet aperture. and directional means situated at the gas outlet; the orientation of the said directional means being adjustable in at least two directions which are not mutually opposite, for thereby controlling the direction in which gas is discharged from the nozzle.

2. A gas nozzle according to Claim 1, wherein the orientation of the adjustable means is angularly unconstrained within at least a predetermined range.

3. A gas nozzle according to Claim 1 or 2, wherein the directional means comprises a bore through which gas passes as it is discharged from the nozzle.

4. A gas nozzle according to Claim l, 2 or 3, wherein the directional means has a generally spherical outer surface.

5. A gas nozzle according to Claim 4, wherein the housing is provided with a seat. in which the directional means can rotate whilst seated.

6. A gas nozzle according to Claim 5, wherein the seat is situated upstream of the outlet aperture and is disposed on a seat structure, which seat structure is slidably received within the said housing, and the outlet aperture is defined by a radially inwardly directed first flange; the arrangement being such as to enable the directional means to be clamped between the flange and the seat by axial movement of the seat structure.

7. A gas nozzle according to Claim 6, comprising clamping means for securing the axial position of the seat structure within the housing.

8. A gas nozzle according to Claim 7, wherein the housing comprises a radially outwardly directed second flange at an inlet end thereof, and the clamping means is defined by a nut. the said nut being fitted about a radially outer surface of the inlet end of the housing and having a radially inwardly directed third flange which radially overlaps the said second flange and is situated downstream thereof; the said nut being adapted to be screwed onto a gas supply body and urge the housing towards the gas supply body, as it is rotated, by virtue of the axial displacement of the third flange causing axial displacement of the second flange, whilst axial displacement of the seat structure is resisted by abutment of an inlet end thereof against a surface of the gas body, thereby causing a reduction of the axial separation of the seat and the first flange and a consequent clamping of the directional means.

9. A gas nozzle according to Claim 5, wherein the seat is annular and defines the outlet aperture and means are provided for clamping the directional means into the seat, on the downstream side thereof.

10. A gas nozzle according to Claim 9 comprising a plurality of said gas outlets, each provided with a respective said directional means seated within a respective said seat, the said clamping means being configured simultaneously to clamp each said directional means into its respective seat.

11. A gas nozzle according to Claim 9 or 10, wherein the clamping means is a plate fitted to the outside of the housing in a region adjacent the outlet.

12. A gas nozzle according to Claim 10 or 11, wherein the said gas outlets are arranged upon a virtual circle lying generally in a plane orientated substantially perpendicular to the direction of gas flow within the housing.

13. A gas nozzle according to Claim 12 when dependent on Claim 11, wherein the plate is generally flat.

14. A gas nozzle according to Claim 12 when dependent on Claim 11, wherein gas outlets are disposed in a frustoconical surface of the housing and the said plate has a correspondingly frustoconical profile in section.

15. A gas nozzle according to Claim 4, wherein the said outlet aperture is defined bv a radially inwardly directed flange and the directional means is clamped against the said flange by a clamping projection, which can be operated from outside the housing.

16. A gas nozzle according to Claim 15, wherein the clamping projection is defined by a clamping screw which is fitted within a threaded bore extending through a wall of the housing so as to direct the screw toward the directional means as it is screwed into the bore.

17. A gas nozzle according to Claim 3 or any claim dependent thereon, wherein the or each directional means is provided with a jet plate at an outlet end of the bore therein; the said jet plate being provided with one or more apertures for causing gas directed therethrough to form ajet.

18. A gas nozzle according to Claim 17, wherein the or each bore comprises an axially facing. annular shoulder situated in the mouth of the outlet end of the bore, upon which the jet plate is seated.

19. A gas nozzle according to Claim 18, wherein the jet plate is held in place by a spring clip which expands into an annular groove provided in the bore wall.

20. A gas nozzle substantially as hereinbefore described with reference to Figure 1; or figure 2; or Figure 3; or Figure 4; or Figures 1 and 5; or Figures 2 and 5; or Figures 3 and 5; or Figures 4 and 5 of the accompanying drawings.

21. A gas burner comprising one or more nozzles according to any one of Claims 1 to 20.

22. A gas burner comprising a first gas nozzle according to any one of Claims 11 to 14 in a central region thereof and a plurality of nozzles, each according to any one of Claims I to 10 and 15 to 19, arranged on a virtual circle located concentrically about the said first gas nozzle.

23. A gas burner substantially as hereinbefore described with reference to Figures 6 to 8 of the accompanying drawings.