AU488552B2 - Gas buhner - Google Patents

Description

74,040/74

This invention relates to a gas burner comprising a mixir

chamber with burner cifice, in which a removable burner bed is

incorporated comprising a nest of ribbons, the ribbons of whic

in at least one of the edge portions are provided with spacing

means, said ribbons being pressed against each other by wall

faces of the burner orifice and being collected such that in t

nest of ribbons one or more rows of gap-like main gas burner

ports are formed between successive spacing means and one or t

rows of auxiliary gas burner ports.

Such a gas burner is known -e fromhUo h patentjapplie

7"in18 In this known gas burner the spacing means are pi

vided in both edge portions and aligned in the direction of f

of the gas. Generally always two ribbons are arranged with the

faces remote from the spacing means against one another, the a

cing means obtained by deformation from one side being shiftec

relative to one another. The ribbons are collected in this mar

to a nest of ribbons clamped in some known manner in the burnc

orifice so that after each pair of ribbons a row of gap-like

main gas burner ports are formed. Against the side faces of tt

burner orifice ribbons may be arranged which comprise spacing

means of less height so that consequently at the side edges ol

burner orifice each time a row of auxiliary gas burner ports 4

obtained. It is also possible to use in the known gas burner 2

bons comprising spacing means having a height equal to half tt

desired width of the main gas burner ports. When the ribbons i

collected to a nest the spacing means of a pair of ribbons arc

arranged against the spacing means of a next pair.

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.The Dutch patent application mentions as an advantage that

on the main gas burner ports separate flame cores are formed.

Between said flame cores transverse passages are formed allowing

the supply of additional secondary air. Consequently a lower

flame is produced resulting in a reduced risk of incomplete com-

bustion and/or deposit of soot on the heat exchange means situated

above the burner, and a lower pre-mixing may be applied so that

a higher port load is possible. This renders possible a more

compact design both of the burners and of the boilers in which

said burners are used.

However, in this known gas burner still a pre-mixing of

is necessary. If the pre-mixing becomes less, then a incomplete

combustion will be the result, because the supply of secondary

air cannot compensate the reduced pre-mixing.

Now the invention aims at improving the supply of secondary

air so that one may do with a very low pre-mixing and a still

higher port load may be arrived at.

According to the invention this is accomplished in that of

the spacing means defining the main gas burner ports in the com-

posite gas burner the spacing means facing the gas supply side

are shifted by half a pitch relative to the spacing means facing

the flame side.

This special arrangement of the spacing means in the compo-

site burner brings about a very surprising effect. At a very low

capacity (low nozzle pressure) the flame is positioned in the

normal way on the main gas burner port, i.e. approximately in the

plane of the slot forming the main gas burner port. When the nozzle

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pressure is raised the flame starts to rotate and assumes a

position perpendicular to the slot. When the nozzle pressure

is still further increased the bat-shaped very low flame does

not become higher but it becomes wider. Since said bat-shaped

flames are spaced according to the pitch of the spacing means

therefore also of the main gas burner ports, a very satisfacti

supply of secondary air is possible so that a very low pre-mix:

of 10-20% may suffice.

The phenomenon may be explained as follows. At a very loi

nozzle pressure the flows of the gas-air mixture in the main

gas burner ports are so weak that nowhere a thrust is produce<

and the gas mixture may flow out comparatively free and unimpi

The flames then stand normally on the main gas burner ports.

When the nozzle pressure is raised two gas flows being formed

in the slots constituting the main gas burner ports an being

directed obliquely upwards and towards each other will increal

thrust against one another, and as soon as they have left the

slot will only be able to expand in a direction perpendicular

the slot. This expansion starts slightly above the slot, as m,

be observed at the flame, where on the slot a core of 1-2 mm

height and transversely to said core a bat-shaped flame is vi:

As a result of these impinging flows of the gas-air mixture,

which expand perpendiculary to the slot, there is produced a

but wide column of gas. adapted to come into contact with secoi

air over a large surface thus making possible a rapid and com;

combustion resulting in a low flame. The content of non-combu,

-products and CO is then limited to zero or to only a few p.p.i

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a further increase of the nozzle pressure the two gas flows

11 only thrust more strongly against each other and will expand

re perpendicularly to the slot so that a widening of the flame

d no increase in height of the flame is obtained. The widening

the flame results in a larger contact suface with the secondary

r and a complete combustion is maintained. An additional advantage

said widening of the flame instead of an increased height of the

ame, as in the case of the known gas burner, is that the heat

change means situated above the gas burner may be arranged closer

the flame without the risk of incomplete combustion and deposit

soot respectively.

As a result of the low pre-mixing which may be applied with

e gas'burner according to the invention the capacity of one

w of slots or main gas burner ports in the burner according to

e invention corresponds with a nest of ribbons of 6-8 rows of 4ddta41 no.417,95O*, ots in the burner according tothc itd Du-t patentlappl-i-e*in

,444&&S, the ribbon or burner bed length and slot dimensions

ing the same in both instances.

Although the shape of the spacing means may strongly vary it

preferred if the spacing means, viewed on the flat side of the

bbons are approximately semi-circular, the diameter of the

micircle being situated approximately at the level of the ribbon

ge. Thus a sitisfactory guiding of the gas flows is realized

thout considerable flow losses. In particular when the spacing

ans are.obtained by deformation of the ribbons, this shape of

iespacing means is advantageous from a point of view of manufac-

ring technique, because one may use nipples and apertures for the

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punches.

If the spacing means are obtained by deformation from one

side and at each of the edges of the ribbons up to a thickness

dimension equal to approximately half the width of the main gas

burner ports, and said main gas burner ports are formed by two

ribbons with their spacing means abutting against one another,

it is of advantage if on one side or either side beside a row

of main gas burner ports one or more rows of auxiliary gas burT

ports are formed by arranging the ribbons with their spacing mf

in the recess of spacing means of the adjacemt ribbons.

Forming a nest of ribbons with more than two rows of main

gas burner ports, said ports being arranged one beside the othe

may badly influence the favourable effect. On the two outermosi

rows bat-shaped flames are slill formed, but on the main gas bui

ports of the intermediate rows the flames stand again in aligni

with the ports. It will, moreover, be possible for these flame;

to become higher by lack of secondary air which namely is cons,

for the greter part by the outermost rows.

In case two rows of main gas burner ports are used, the s

may be arranged one beside the other so that consequently perp

dicular to the pair of slots a bat-shaped flame, be it a somew

wider one, is formed. It is preferred, however, if the main ga

burner ports of a row of said ports are shifted by half a pitc

relative to the main gas burner ports of an adjacent row, so t

the bat-shaped flames of one row stand between those of the ot

row and a satifactory supply of secondary air to each row is

maintained.

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of four Of course it is also possible to arrange a nest

one another such, that the ows of main gas burner ports beside the other, but the slots lots are situated per pair one beside of the pitch relative to the f one pair being shifted by part

ther pair. burner of large capacity Now in order to obtain yet a gas

:he main gas burner ports can be arranged at a sufficient large

two nests of each time four nutual distance. For this purpose may be placed against two opposite rows of main gas burner ports intermediate side walls of the burner orifice and the remaining filled for example whith blind space between said nests may be it is difficult to get ribbons or a fitting block. However, the flames. This secondary air sufficient secondary air between be burner bar vertically and must rises past the side walls of the in order to get between the deflected in the horizontal dir.ection

flames. a favourable embodiment of In order to remove said drawback orifices pointing aslant the gas burner comprises two burner To this end the burner bar upwards and in opposite directions. burner orifice there is then may be somewhat modified. In each with four rows of main gas arranged a nest of ribbons fbr example flames are brought into burner ports. In this way the bat-shaped An additional advantage is that the vertical secondary air flows. the temperature is very -in a horizontal plane above the burner

much uniform. bat-shaped flames In this embodiment it is surprising that the

ports in such a stable manner are standing on the main gas burner

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that they do not show any tendency of bending their tops upwar

In an other favourable embodiment of the gas burner accor

to the invention the latter is of a round design with horizont

and radial gas outlet, the ribbons being annular and flat with

spacing meas at the inner and or outer circumference shifted

this embodiment the width dimension of the by half a pitch. In

bat-shaped flames is vertical. In this embodiment the annular

ribbons can be clamped between an upper and a lower burner cha

the gas-air mixture being fed for example through a conduit tc

the lower gas burner chamber.

From the foregoing it is apparent that on account of the

of ribbons, both straight and annular ones,. there is a great

flexibility in the selection of the burner shape. The flames V

at choice be directed vertically, horizontally and/or aslant.

The burner and the flames can be entirely adapted to the shap4

the location of the combustion chamber and of the heat exchanj

means so that always an optimal efficiency can be arrived at.

It is also of advantage that the flames in the burner ac<

to the invention cannot flash back. Even when using a gas thai

easily flashes back the flames will not strike back. The reaso

are'as follows. As a result of the very low pre-mixing there

through the main gas burner ports a gas-air mixture which is

or only little combustible since it is above the explosion li:

As the flame stands vertically on the ribbons the heating of

ribbons by radiation of the flame is small. The ribbons are co

by the flows of secondary air between the flames. Finally the

rate of outflow the flows of gas prevents the flames from str

back.

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The invention is explained by means of the following descrip-

ion with reference to the drawings. Said drawings show in

Fig.l various views of two abutting ribbons with spacing

leans applied in an embodiment of a gas burner according to the

.nvention;

Fig.2 illustratively an explanation of the shape of the flame

.n front view and side view;

Fig.3 other forms of spacing means;

Fig.4 a top plan view of an embodiment of a nest of ribbons;

a top plan view of another embodiment of a nest of

cibbons;

Fig.6 the arrangement of two burner ports in a special

the gas burner according to the invention, and in mbodiment of

Fig.7 two views and a partial section of the round embodiment

)f the gas burner according to the invention.

In the embodiment shown in Fig.l two ribbons 1 and I' with

spacing means 2, 2' and 3, 3' are placed against each other. In

this instance said spacing means are formed by indentation from

3ne side in the edge portions of the ribbons I and I' and they

have a half-round shape. The upper spacing means 2 of the ribbon

I abut against the upper spacing means 2' of ribbon 1' while the

lower spacing means 3 of ribbon I abut against the lower spacing

means 3' of ribbon Now according to the invention the spacing

means 2, 2' are staggered by half a pitch in longitudinal direction

relative to the spacing means 3, The spacing means now form

between the ribbons slots, called main gas burner ports 4, which,

however, do not allow a straight passage of the gas flows.

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In fig.2 it is shown how the gas flows are guided through

the main gas burner ports 4. A gas flow 5 supplied form one si4

of the main gas burner ports is split into two partial flows 6

and 7. The partial flow 6 thrusts, on passing through'the main

gas burner port 4, against the partial flow 7 of an adjacent

gas flow 5. At the exit of the partial flows 6 and 7 thrust one

against the other the gas expands mainly transversely to the o

o.f the main gas burner ports 4, a core 8 and a wide bat-shaped

flame 9 being formed, at any rate if the nozzle pressure is sul

ciently high.

Instead of asemi-round shape the spacing means on the

ribbons may also be differently shaped. Fig.3 shows a ribbon 1(

with triangular spacing means 11 and 12 and a ribbon 13 with

trapewid spacing means 14 and

Fig.4 shows a nest of ribbons comprising four strips I, I'

16 and 16'. The ribbons 1 and 1' are placed again with the corr

ponding spacing means 2, 2' and 3, 3' against each other so tha

between them main gas burner ports 4 are formed.-On either side

these two ribbons I and 1' there are arranged two ribbons 16 am

16' such that the spacing means 17 and 17' respectively are posi

in the indented back sides of the spacing means 2 and 2' respec

of the ribbon I and I' respectively. Since the spacing means 17

17' respectively cannot reach entirely to the bottom of the bac

sides of the spacing means 2 and 2' respectively, there will be

created between the flat portions of the ribbons I and 16 and t

ribbons I' and 16' respectively gaps 18 and 18' respectively fo

auxiliary burner ports.

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In Fig.5 there are arranged beside the pair of ribbons I and

I' a second pair of ribbons 19 and 19', collected in the same manner

as the ribbons 1 and the ribbon 19' abutting against ribbon I

such that the main gas-burner ports 4 and 20 are staggered by half

a pitch relative to each other. As a result the bat-shaped flames

from the main gas burner ports 20 get partly between the bat-shaped

flames from the main gas burner ports 4. Beside the strips 19 and

I' there are arranged again a number of- ribbons 21-23 and 21'-23'

respectively such that a plurality of- rows of auxiliary burner

ports are created.

In a.preferred embodiment of gas burners having.a great.-

capacity, as shown in Fig.6, two burner orifices 27.and 28 are

pointing aslant upwards and in opposite directions and-are

arranged according to an angle relative to the.horizontal plane

on the burner pipe 24 with gas supply 25. In a technical embodiment

the burner pipe 24 may comprise slanting faces 26 on which the

burner orifices 27 and 28 can be arranged. As a result of this

arrangement of the burner orifices 27 and 28 secondary air rising

along the walls 29 and 30 of the burner pipe 24 may easily reach

the flames and a substantially complete combustion of the gases

is. realized.

Also in the round embodiment of the gas burner according

to the invention shown in Fig.7 secondary air has an easy access

to the flames. In this embodiment the ribbons 31 are of annular

shape. At the inner and outer circumference said ribbons are pro-

vided with spacing means 32 and 33, the spacing means 33 at the

inner circumference being staggered by half a pitch relative to

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the spacing means 32 at the outer circumference. Said annular

ribbons I are clamped between an upper burner chamber 34 and

a lower burner chamber 35. A mixture of gas and air is supplied

to said burner chamber 34, 35 via a conduit 36 connected to the

lower burner chamber

It will be obvious that the invention is not restricted

to the afore-decribed embodiments but that numerous modificatic

are possible which, however, are all within the scope of the

invention.

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The claims defining .the-invention are as follo.s:- i. A gas burner comprising a mixing chamber with a burner orifice,

in which a removable burner bed is incorporated comprising a

nest of ribbons, the ribbons of which in at least one of the edge

portions are provided with spacing means, said ribbons being

pressed against each other by wall faces of the burner orifice

and being collected such that in he nest of ribbons one or more

rows of gap-like main gas burner ports are formed between

successive spacing and one or more rows of auxiliary gas burner

ports, characterized in that of the spacing means defining the

main gas burner ports in the composite gas burner the spacing

ueans facing the gas supply side are by half a pitch 4ohi.ft

relative to the spacing means facing the flame side.

2. A gas burner according to claim I, characterized in that the

spacing means, viewed on the flat sides of the ribbons, are

approximately semi-circular, the diameter of the semi-circle

being situated approximately at the level of the ribbon edge. ij

3. A gas burner according to any one of the preceding claims, in

which the spacing means are obtained by deformation from one side

at each of the edges of the ribbons up to a thickness dimension

equal to approximately half the width of the main gas burner ports

and said main gas burner ports are formed by two ribbons with their

spacing means abutting against one another, characterized in that

on one side or either side beside a row of main gas.burner ports one

or more rows of auxiliary gas burner ports are formed by arranging

the ribbons with their spacing means in the recess of spacing means

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of the adjacent ribbons.

4. A gas burner according to any one of the preceding claims,

characterized in that the main gas burner ports of a row of mi

ports are shifted by part of the pitch relative to the main

gas burner p6rts of.'an adjacent row.

1973).

A gas burner according to any one of the preceding claims,

characterized in that it comprises two burner orifices pointin

aslant upwards and in opposite directions.

6. A gas burner according to any one of claims 1-4, characteri

in that it is of a round design with horizontal and radial gas

outlet, the ribbons being annular and flat with spacing means

at the inner and/or outer circumference shifted by half a pitc

7. A ribbon as used in the gas burner according to any one of

preceding claims, and a nest of ribbons composed of said ribbo

Dated this 2nd day of October 1974

RESEARCH INSTITUUT SESTO B.V. Sby its Patent Attorneys DAVIES COLLISON

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FIG. 1 I13 2

3 .2

3

FIG.2 67 6N 872

12~-

V-/

1

1,5488,5 52

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FIG.4 17' 18, 1' 3' 16'

2 17 18 16 3 1

FIG. 23. 2-2' 21

19 21 22 23 FIG.620 19.

,27 28

-26

-24.

29

11

17 17488,5 5 2

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Fl G.7

34

3

19 48 8,5 5 2