DE2827554C3 - burner - Google Patents

Description

The invention relates to a burner according to the preamble of claim I.

Such a burner is known from GB-PS 6 04 444. The means of limitation provided there of the reverse flow are in many cases insufficient for the effective suppression of flashbacks.

The object of the present invention is to improve a burner of the generic type with regard to avoidance of flashbacks in which the flame is trapped in the burner, where it can trigger undesired melting processes. According to the invention, this object is achieved with the features of claim I solved.

The present invention thus provides a particularly simple and reliable solution to the problem of Flashback.

With the feature of claim 2 according to a development of the invention, the inflowing and expanding oxygen gas is used to cool such combustion gases, which in the case of a Flashback flow backwards.

Further advantages and possible applications of the present invention emerge from the following Description of exemplary embodiments based on the drawing. It / cigt

F i g. I an acoustic high-pass filter according to the invention,

4.7 I Λ /, C ₁ ,

whereby

and

W ₁ . "'2

m =

I,

Speed of sound in the medium in question Density of the medium in question

effective length of the hole 3

Area of the hole 3

Volume of the resonator space 2

I "ig. 2 illustrates the principle of an acoustic Low pass filter in the oxygen gas channel. The gas is circulated through a flow restrictor 1 and passages 20 in guided a cylindrical chamber which is formed by walls 4. In the chamber is a body 23 arranged, which is designed so that individual resonator spaces 22 are formed. Between these Rcsonator buckets 22 are located / wiping pieces 21. The cylindrical chamber has a front

conical section 24 which opens into the mixing chamber 8 via an axial bore 6. The oxygen gas will mixed in the mixing chamber 8 with burner gas, which in the mixing chamber 8 from the surrounding Burner gas chambers 7 is drawn in while the oxygen gas flows in. The gas mixture is then fed via a pipe 9 to the nozzle (not shown).

The limit / frequency f .: of the low-pass filter is determined by the following equations:

f.i =

.τ j A /, -C ₁ ,

whereby

C _A1 =

Speed of sound in the medium in question Density of the medium in question

Distance between the resonator spaces 22

Area of the intermediate pieces 21

Volume of the resonator space 22

Due to the special design of the acoustic filter, in addition to the aforementioned Damping effect also a resistance against a backflow of the fresh oxygen gas in the case achieved a flashback. As a result of the special design of the filter, it is oxygen gas forced to get through a multitude of narrow channels and change direction several times.

Before the oxygen gas gets into the filter, it passes the flow limiter 1 at the inlet. Because of its oxygen gas expands, whereby a cooling effect occurs. The cooling atmosphere is used Cooling of hot combustion gases, which in the event of a flashback or a misfire flow backwards. The desired cooling effect is achieved through the special design of the flow restriction and the flow rate of the oxygen gas is achieved.

The three measures mentioned above each contribute in their own way to preventing post-ignition occur within the burner at the entrance of the mixing chamber 8 or 16 in the first backflow stage; the Rather, the flame remains extinguished or is at the

Tabel

The outlet nozzle reignited as a result of the hot workpiece.

In Fig.3 a burner is illustrated in which an acoustic filter is inserted. The filter in this embodiment is a high pass filter. The cylindrical one Body 11 is provided with radial holes 12 as shown. The oxygen gas will through the flow limiter 10 into the Sauersicfl'gaskanal is inserted and then passes through the holes 12

in in the acoustic filter. The oxygen gas passes through the axial bore of the filter into the mixing chamber 16. The burner gas comes from the cylindrical fuel gas chamber 15, which surrounds the filter, into the mixing chamber 16. Into the fuel gas chamber 15 is

ii burner gas introduced via a channel 14 and a connecting bore 13. A burner gas pipe 18 and a Nozzle 19 are connected to section 17. The burner gas pipe 18 and nozzle 19 are not shown in the figure shown. When using a small nozzle, this is

2n tube for guiding the gas mixture briefly, while at a large nozzle the pipe is long.

A heating burner which, with reference to FIG. 3 type described was with propane as burner gas tested. These test results are in the

_'i illustrated in the table below. The I investigations were made in a wide range of five different nozzle arrangements. As can be seen from the table, the burners were safe against flashback or misfire

in all cases very well. The burners were also using Acetylene tested as burner gas. Good results against flashback and / or misfire have been made also achieved in this case.

Using theoretical acoustic, flow

r, metrological and thermal theories and putting these theories into practice it became possible to use a burner with simple means create, which is secured against flashback or misfire, by a constructive

in association of measures which alie the oxygen gas duct of the burner. As mentioned, these measures relate to the acoustic filter Attenuation of the oscillations in the backward flowing combustion gases, the flow restriction at the

■ ti inlet, which allows an expansion of the fresh oxygen in one way causes cooling of the backward flowing combustion gases and delay the backflow of fresh oxygen as a result of the mechanical design of the filter.

The arrangement in the oxygen gas channels is not limited to the exemplary embodiments or burner types shown. It can also be modified in ι way.

Nozzles oxygen llul.lnüe propane “Normal Hamm ·: '« f No hammer - arrangement setback pressure l / h pressure hardness length - llamb- 3 weeks setback har 5,000 bar "'Hill I Il 0.5 4,800 0.25 middle 12th + 5 I Il 0.7 8 750 0.38 strong 15th + 5 2 11 0.5 8 700 0.2 middle 15th KS 2 Il 1.3 8,300 0.5 strong 15th + 4 2 Il 1.3 0.5 strong 15th + 5 3 Il 1.1 0.35 middle 20th + 5

I (nt set / Ήΐιμ Nmiirslo Il I uHmIe l'ro |> .m "Niiriu.ili I l.imiiu · " 20th 'Ki'in I hiiiiiiu'ii DiiM'ii- 20th riiiksihl.iu . Take it! pressure l / h Inside k ll.irli ' I JMl ¹ I- 15th I I.IMlMH-M 16 500 IO πιι'ΚΜ'ΙιΚιμ h.ir 10 700 here Ml Ml IO I S 60 (1 O.S. hurl ι 5 .ι ii 1.6 12 70 (1 0.4 schwiicli ι 5 4 Il 2SO (M) 0.5 sin ι k I s 4 Il 2.1 (1.6 Sl'hUMlll ι S. 5 Il 5 7 (). '» niilli'l ι> 5 Il

I HImII / .L'icliiimu'.L'ti

Claims (2)

Patent claims: 1. Burner, in particular burner secured against flashback, which is operated with a mixture of oxygen gas and fuel gas, for example propane, natural gas or acetylene and is optionally equipped with an injector, with means for delaying the backward flow of fresh oxygen being provided in the oxygen gas duct in that the measures provided in the oxygen gas channel means are formed as an acoustic high or low-pass filter with such frequency limits that the oscillation frequencies of the combustion gases, which are ^p formed lamb setback in the burner in the case of a lie within ο damping region of the filter, d · . The high-pass filter has a cylindrical chamber in which a cylindrical body (5, 11) with radial holes (3, 12) is arranged to form a resonator (2) and the cut-off frequency of the high-pass filter is determined by the effective length of the holes (3, 12) Area of the holes (3, 12) and the volume of the resonator chamber (2) is determined, and the low-pass filter has a cylindrical chamber in which a cylindrical body (23) with spaced apart resonator chambers (22) and the cut-off frequency of the low-pass filter determines the distance between the resonator spaces (22), the area of the intermediate pieces (21) and the volume of the resonator spaces (22). 2. Burner according to Claim ¹ '1, characterized in that the inlet of the oxygen gas channel is equipped with a flow limiter,' -O). Fig.2 shows an acoustic low-pass filter according to the invention and Fig. 3 a heating burner with built-in acoustic filter. - According to the invention is in the oxygen gas channel of the Burner installed a suitable acoustic filter. The filter should have such a cutoff frequency that the Oscillation frequencies that occur in the combustion gases when a flashback or a occur in misfire within the damping Frequency range of the filter. The filter can be a high-pass filter or a low-pass filter. In the event of a heat and flame burner, which in the order of 1000 I per hour to 70001 per | -, hour works, has a high-pass filter on proven to be most effective. In the case of smaller welding torches and cutting torches, however, have Low pass filter shown as being more suitable. Fig. 1 illustrates the principle of the arrangement 2n of an acoustic high-pass filter in the oxygen gas duct of a burner. The oxygen gas is fed through a flow limiter 1 into a chamber delimited by walls 4. In the chamber is a cylindrical body 5 with radial holes 3 to form a >> Resonator space 2 arranged. The oxygen gas flows through the radial holes 3 into a centrally located axial bore 6, from where it flows into a Mixing chamber 8 arrives. In the mixing chamber 8, the oxygen gases are mixed with burner gas, which in ίο the mixing chamber 8 due to an ejector effect the surrounding cylindrical burner gas chamber 7 is drawn in when the oxygen gas from the the front end of the bore 6 flows into the mixing chamber 8. The gas mixture then becomes a (in the Γ) Figure (not shown) nozzle fed through a pipe 9. A high-pass filter has a cutoff frequency fc \, which is determined on the basis of the following formulas: