Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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The invention relates tO an ignition gun for igniting
main burner ~ed with easeous fuel.
In such a main burner the gun thereof may issue into a
refractory-lined combustion chamber ~/hich itself communicates, for
example, with a reactor or ~rith a combustion heartb. The ga~eous fuel
and the combustion air are usually supplied separately to the
; burner, mixing ~requently taking place outside the gun, i.e. inthe combustion chamber. In this case it i8, for example, possible
for the fuel to leave the gun centrally and the air peripherally.
tO The main burner may o~ course be so protected that the
supply of fuel is halted in the event of extinction of the
flame. A drawback to this is that the main burner has to be
re-ignited whenever the supply of fuel is interrupted and the
flame is extinguished, which frequently requires a cumbersome
procedure. ~his drawback i!3 obviated by the use of a pilot flame
or a pilot burner.
The pilot flame has the task of re-igniting the flame
immediately if and when it is extinguished, thereby preventing
an explosive mixture from collecting in the combustion chnmber.
Once the refractory lining of the burner has reached the
operating temperature, self-ignition of the flame frequently
takes place in the event of temporary extinction of the ~lame, `
` indicating that the conditiGns ~or a stable flame are
re~atively favourable. This is not the case~ however5 when
` 25 a/cold main burner is ignited. At this time the ignition
gun or pilot burner must therefore be capable of meeting
more severe demands. Flame stability is an important criterion
in this connection.
~- A drawback to permanently installed gas-fired pilot
burners is the fact that they have a relatively complicated
and vulnerable gun, which moreover has to be cooled on account
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~ of the risk of its becoming overheated by the main flame. Further,
j the stability of the flame on such a pilot burner is frequently
unsatisfactory, and is further impaired once excess pressure
prevails in the combustion chamber or builds up during ignition
;l of the main flame.
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A mobile i~nition gun to be inserted in the main burner, which
gun is subsequently removed a~ter ignition and thus is not used as a pilot
burner, does not have the drawback of the risk of becoming overheated and
will be less subject to corrosion. ~lowever, it has the drawback that the
ignition flame, which is ignited outside the main burner, is easily
extinguished under the effect of the excess pressure in the main burner
during insertion. In particular the mobile ignition guns are very sensitive
to the air/fuel ratio and the air pressure and gas pressure relative to the
excess pressure in the main burner. Excess pressure or high pressure means
; 10 a pressure higher than atmospheric pressure.
The object of the present invention is to provide a mobile ignition
gun having a large chance of igniting the main burner and which ignition gun
overcomes the drawbacks of the known ignition guns.
One aspect of the invention is an ignition gun for igniting a main
burner wherein fuel is supplied through an annulus between an inner tube
and an outer tube, said ignition gun having an ignition chamber provided with
supply inlet means for injecting gaseous fuel and oxygen-containing gas into
the ignition chamber and a spark plug mounted on said chamber for intermitt-
ently providing a spark, and means for detachably connecting said ignition
gun to the main burner with the chamber communicating with the i~terior of
the inner tube such that the inner tube acts as a flame tube to transmit a
flame from the ignition gun to the main burner.
A second aspect of the invention is a combination of an ignition
gun for igniting a main burner fed with gaseous fuel, said ignition gun having
an ignition chamber provided with a supply inlet means for injecting gaseous
fuel and oxygen-containing gas into the ignition chamber, a spark plug mounted
on said ch~mber for intermittently providing a spark, and a main burner
wherein fuel is supplied through an annulus between an inner tube and an
; outer tube, the end of the inner tube remote from the main burner~ including
a valve and the ignition gun being detachably connected to the inner tube.
Such an ignition gun can emit flame flashes at a frequency suitable
for igniting a main burner. I the ignition gun is inserted in the main
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burner or installed on this main burner the flame flashes leave the open
front end of the fl~ne tube and en~er tlle combustion chamber of the main
burner ~ld there ignite the main flame of the gun of the main burner.
To this end~ a gas/air mixture should collect in the ignition
chamber after each flame flash, which mixture is subsequently ignited by
the said spark. A flame front then travels through the said flame tube,
after which the flame flash can finally leave the open front end of the
fl~le tube.
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~)37;3'74
It will be clear that the risk of fQilure when i~niting
the main burner with such an ignition gun i9 remote, particulsrly
in view o~ the fact that a number of flQme flashes are
generated, each of which provide a chance of success~ul ignition.
Ihe use of a stabilizer is thereby rendered unnecessary. Moreover,
the said ~la~e tube cDntains no vulnerable components.
The ignition gun described above may be utilized with great
advantage for igniting a main burner operating at excess pressure.
In an excess-pressure burner an excess pressure prevails in the
tO combustion chamber with respect to the atmosphere. This requires
the ignition gun to be also capable of operating at thi~ excess
pressure.
The ignition gun described above can be detachable in the
sense that the ignition chamber is provided with means to aetachably
connect the same to the ~lame tube. For this purpose the ignition
chamber may be provided with a quick-release coupling. In the lattçr
case it is possible to leave the flame tube in the main burner aMer
the latter has been ignited by means of the ignition gun. This has
the advantage that the ignition gun can be employed for
several main burners and needs little or no cooling. Another
advantage is that a sight glass can be installed in the flame
tube after ignition through which it is possible to inspect ~ -
the ignited main flame.
The invention also reIates to a combination of an ignition
gun as referred to abov~ nd a main burner for gas20us fuel
in which the main burner has an annular burner port at the -~
front end o~ a tube which debouches and is open inside the
burner port, and which tube has a valve at its rear end,
the said tube acting as the flame tube to which the ignition
chamber is connected through its quick-release coupling.
Particularl~ in the case of such a main burner, the flame tube
m~y readily remain permanently installed while the rest o~
the ignition 6un is remo~ed ~fter i~nition of the v~in burner.
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The ignition Kun is found to be exceptionally effective particularly
- with this type of main burner, because the fl~me tube deboUches
centrally in the flame ultimately to be generated.
In this connection it should be noted that a maJor advantage
of the above-mentioned central positioning of the ignition gun
with respect to the main burner lies in the fact that large
volumes of sweeping combustion air cool the flame tube of the
ignition gun.
The above-mentioned combination according to the invention
is preferably equipped with a safety device which responds to
the flame. It is possible for this device to respond only to the
main flame to be ignited in the main burner, so that it is
known when the ignition attempt has succeeded and dis~ssembly
of the ignition gun may commence, if desired. An alternative
; 15 or additional possibility is to utilize a detector which moreover
responds to the fl~e flashes from the ignition gun itsel~
In the latter case it is, for example, possible to link this
detector with the gaseous fuel supply to the main burner,
the said supply remaining closed if no ~lame flashes are ;`
detected. Equally, however, it is possible to inspect by
human agency whether the ignition gun is operating when installed
in the above-mentioned combination oY ignition gun and main
burner.
The main burner m,~y advantageously have a gun with a hollow, `
double-walled, cylindrical barrel in which the fuel flows between
the walls of the inner tube and the outer tube to an annular ~ ~ -
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slit at the front end of the barrel ana in which the air flows ~ ~ !
via a register along the exterior of the barrel to the front
end thereo~. The inner tube of the barrel can in that case
act as flame tube. -
The invention may be utilized with advantage in a sulphur
~, recovery plant for the preparation o~ elementary sulphur from
and H2S-containing gas3 comprising a first burner for the
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combu~tion of nt l~st part of the H2S to S02, a thermal
reactor for th& formation o~ elementary sulphur by reaction
of the formed S02 with the remaining H2S at elev~ted temper~tUre~
a first condenser for cooling the gas leaving the thermal
re~ctor for the condens~tion and removal o~ sulphur, as well
as ~t lea~t one catalytic unit for the further conversion
of H2S, comprising a second burner for the preparation of
hot combustion ga~es from gaseous fuel for heating the gas
leaving the first cooler and a catalytic reactor for the
further reaction o~ H2S and S02 in the gas and a second
cooler for cooling the ga~3 leaving the catalytic reactor
for the condensation and removal of further sulphur.
The second burner used in the above~mentioned plant may consi6t
of a combination of an ignition gun and a main burner accordine
to the invention.
For the sake of clar:ity it is mentioned in this connection
that problems which occur especially in the burner of the
catalytic unit~ the so-called line burner with a permanently
installed ignition gun are the rapid corrosion of the
ignition gun and the clogging with solid sulphur of the
barrel of the ignition gunO This is very closely related
to the non-central positioning of the ignition gun in the
burner o~ conventional sulphur recovery plants, because
some of the sulphur formed is recycled in the specially formed
flame. Central positioning o~ the ignition gun in accordance with
the invention obviates this drawback since the combustion air
supplied via the main burner prevents deposition of sulphur
at the locus of the gun of the burner.
The main burner of the above-mentioned combination according
to the invention is ignited by - if necessary - connecting the
ignition chamber to the vslve, by opening the valve, supplying
gas and air to the ignition gun and switching on the sparking
! plug, and subsequently ignit;ng the main burner, to which a
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g~seous fuel and air are supplied, whereupon, once the main
burner hQs been ignited, tho supply o~ ~RS Qnd air to the ignition
gun is shut off, the aparking plu~ is ~witched of~ and the v~lve
is closed. Optionally the ignition chamber is di~connected from
the valve
The invention further relates to the use of a combination
of an ignition gun and a main burner as a gun in a process
for the preparation of elementary sulphur from an H2S-containing
gas, in which proess at least part of the H2S is burnt to ~ive
S02, which S02 is thermally reacted with the remaining H20,
the formed s~phur being condensed and removed by
cooling the gas, the cooled gas is reheated in a burner which
i9 fed with a gaseous fuel and wherein its resultant hot combustion
gases are mixed with the cooled gas, whereafter the heated
gas mixture is passed through at least one catalytic converter
for the further reaction of H2S and S02, followed by cooling for
the condensation and removal of further sulphur.
The combin~tion accorcling to the invention is also suitable for -
use as a burner in a process for the removal of sulphur compounds
from an off-gas Erom a sulphur recovery plant in which the oEf-gas
containing the sulphur compounds is firstly heated in a burner`~ -
~ which is fired with gaseous fuel and in which burner the off-gas
- is mixed with its hot combustion gases, the heated off-gas mixture
is subsequently mixed with a reducing gas ~nd substantially all
sulphur compounds are catalytically redùced to H2S9 after which
H2S is at least substantially removed from the off-gas by absorption
and recycled to the said sulphur recovery plant.
The invention is pre-eminently applicable to p~cesses QS
referred to above, provided that an excess pressure of at least
; 30 0.01 atm. prevails in the combustion chamber of the main
burner.
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The in~re~tion will now be furthcr elucida-ted with r~ference
to the drawings.
F`ig. 1 is a large-scale axial cross-section of the gun of
a main burner, attached to which is ~n ignitio~ eun according
to an embodiment of the invention.
Fig. 2 is an axi~1 cross-section of a burner used in a
sulphur recovery plant.
Fig . 1 shows a gun 1 of a main burner 2, to which an
ignition gun 3 according to an embodiment of the invention is
detachably attached. Between ignition gun 3 and gun 1 a valve
4 is provided.
Main burner 2, which i8 of the type shown in Fig. 2.
comprises a combustion chamber 5 (partly sho~m) with a refractory
lining 6 and an annular opening 7, in which gun 1 is inserted.
This gun 1 comprises a double-walled barrel, of which the inner
tube 8 widens in a funnel-shaped manner at its free end 9, and
of which the outer tube 10 is provided with a connection 11 for ~-
the supply of gaseous fuel to an annular slit 12. Via this
slit 12 the fuel leaves gun 1, after which it fans out and
becomes intensively mixed with the combustion air which is
supplied via an air register 13 and a guide funnel 14 from
an air box 15 (partially shownj. Inner tube 8 of gun 1 acts
as a flame tube ~or ignition gun 3.
The rear end 16 of gun 1, which projects clear of main
; 25 burner 2~ is provided with a screw thread to permit fixing
of a valve 4 9 which is permanently fixed on the rear end 16
of the gun and also has a connecting sleeve 17. Ignition gun
3 comprises an ignition chamber 18 which can be connected to ;
or detached from sleeve 17 by means of a quick-release coupling
19. After ignition chamber 18 has been coupled to gun 1 by
means of the said sleeve and valve 4 has been opened9 a single
continuous passa6e ses ed at lts rear end 20 with s sight g1sss 21,
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i5 created ~rhich debouches in combustion chamber 5 Or the m~in
burner.
An air supply nozzle 22 and a g~ supply nozzle 23 debouch
in ignition chF~nber 18. A sparking pl1lg 24 is also inserted
into the ignition chamber, the terminal of which sparking plug
is visible at 25.
~` The shape of the front end of the gun is so adapted to the
shape of the burner port 7 of the combustion chamber 5 that a
special flame shape is obtained in this chamber 5. It will be
clear that the gaseous ~uel, immediately after leaving the annular
slit 12, is struck by the whirling air stream leaving the air
register 13. As a result, intimate mixing immediately takes
place before the flame forms in the shape of a double vortex
in the combu~tion chamber 5. It is observed that combustion
chamber 5 corresponds with re~erence numeral 50 in Fig. 2.
The operation of the ignition gun shown in Fig. 1 is as ~ -
follows. The gas supply to gun 1 of the main burner is shut
off and valve 4 is also closed. Then, by means of ~uick-release
coupling 19 ignition chamber 18 o~ ignition gun 3 is installed
and valve 4 opened. Next the air supply to noz~le 22 is
opened and sparking plug 24 is switched on. Subsequentl~ the
supply for gaseous fuel to no~zle 23 is opened. Then, at the
rate at which sparking plug 24 generates sparkæ, flame flashes
leave the front end of gun 1 via flame tube 8. Whether ignition
gun 3 is in fact functioning may be inspected through sight
glass 21. Alternatively or additionally, it is possible for
a safety device to be installed in main burner 2 which detects
whether a flame is or flame flashes are present. Such a safety
device may be, for example~ a cell sensitive to ultraviolet
radiation installed in the masonry of combustion chamber 5
of the main burner. ;
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Subsequently the air supply to the ~ain bur~er i9 opened,
after which the supply for gaseous fuel to connection 11 i8
opened. This procedure is generally monitored by the above
safety device for detecting whether the main flame Or gun
1 has ignited within a certain period. If this is not the csse
the supply for gaseou.s fuel i9 shut off, whereupon a new
attempt can be made. If ignition has been successful, however1
the fuel supply via nozzle 23 is then shut off, sparking plug 24
switched off, the air supply via no~zle 22 interrupted, valve 4
closed and the ignition gun is detached from sleeve 17.
It is now possible to install, by means of quick-release
coupling 19, a tube end - not shown - in the place of the
removed ignition chamber, the rear end of which -tube carries a
sight glass similar to sight glass 21. The flame of the main
burner may be watched by temporarily opening valve 4.
If use is made of propane, for example, available
virtually every~rhere in gas bottles, as gaseous ruel ~or
ignition gun 3, a gas pressure of at most about 3 atm and an
air pressure for the combustion air of at most about 10
atm are sufficient to operate the ignition gun. The sparks may
be generated, for example, at a frequency of approx. two per
second by means of a 24V alternating current source; the
highest discharge voltage on the sparking plug may be, for
example, 2500V.
Line burner 42~ which is suitable for use in a sulphur
recovery plant (Clausplant), is shown in a cross-section and
on a large scale in Fig. 2. It is fired with a gaseous fuel
supplied via a line 11'to gun 46. Compressed air or an
oxygen-containing gas is introduced via an inlet 48 in the
above-mentioned manner, whirling around gun 46, via an air
box 49, air register 13' and guide funnel 14'. The combustion
in the line burner should be stoichiometrically as precise as
possible, ae otherrriG~ either 52 or N2N will be pr~sent i= the
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of i -gas .
In a mixing chamber 43 with refractory linin~ 51 the
combustion gases f'omed in combustion chamber 50 of line burner
42 are mixed with the process gases to be heated which are
supplied via an inlet 52. The heated ga3, mixed with the combustion
gases, leaves mixing chamber 43 via a discharge 53.
It can further be seen that an ignition gun 3' is ,
installed on the rear end of gun 46 which i8 provided with a
valve 4'.
For the construction and operation o~ the ignition gun
reference is made to the description given in Fig. 1.
The ignition gun to which the invention relates may be
used on the above-mentioned burners and in particular, for
example, on a burner of the type as shown in Fig. 2. This type
Or burner dis-tinguishes itself among other things by the
lateral inlet 48 for the combustion air, to which air
register 13' with funnel-shaped interior 14' connects for the
creation of an air stream whirling around the central gun 46,
In using the line burner 42 in a sulphur recovery
plant the process gas introduced via inlet 52 emanates
from a preceding sulphur condenser. The heated gas mixture
leaving the mixing chamber via discharge 53 is conducted `~
to a catalytic reactor. Burner and catalytic reactor form
together the catalytic unit of the sulphur recovery plant. ~ ,-
Such a plant may have more than one catalytic unit. In the
first catalytic unit the process gas introduced via inlet 52
emanates from the sulphur condenser following the thermal
reactor; in any following catalytic unit this process -`
gas emanates from a sulphur condenser following the preceding
ct~lytia unit.
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