SE190818C1

SE190818C1 -

Info

Publication number: SE190818C1
Authority: SE
Publication date: 1964-01-01

Description

Uppfinnare: J Isreeli Prioritet begdrd frdn den 7 oktober 1960 (USA) FOreliggande uppfinning hanfor sig till brannare och brdnnaranordningar for astadkommande av en spektralMga for k-vantitativ bestamning av ett eller flera amnen i vatskeprov. Inventor: J Isreeli Priority as of October 7, 1960 (USA) The present invention relates to burners and burner devices for providing a spectral quantitative determination of one or more substances in liquid samples.

Ett andamal med foreliggande uppfinning ãr att astadkomma en. spektralbrannare, som arbetar med en sakerhetslAga och är utford sh, att varmeovergangen &an denna till brdnnarkroppen minskas i hog grad. Ett annat findamal är att astadkomma en spektralanalysbrannare, som lampar sig väl for astadkommande av en hogtemperaturlfiga utan att brannarkroppen behOver vattenkylas. Ett annat andamal fir att astadkomma en. spektralanalysbrannaranardning, som omfattar hj alpmedel for att i fOrvfig blanda brfinnbar gas och syrehaltig gas till bildning av en brannbar gasblandning for bade sakerhetslagan och spektralanalyslagan. Ett annat andamhl är att fistadkomma en spektralanalysbrannare med tillforseln-tedel for analysprovet, vilka minska inverkan av tryckvariationer, som verka ph detta pa grund av dess forberedning for spektralanalys. Ett ytterligare andamhl ar att astadkomma en forbdttrad spektralbrdnnare som liar enkel konstruktion och är billig i tillverkning. An object of the present invention is to provide one. spectral burners, which work with a safety layer and are challenged, that the heat transfer & this to the burner body is greatly reduced. Another fine is to provide a spectral analysis burner which is well suited for producing a high temperature fig without the need for the burner body to be water cooled. Another spirit to achieve one. spectral analysis burner device, which comprises auxiliary means for mixing combustible gas and oxygen-containing gas in a precursor to form a combustible gas mixture for both the safety law and the spectral analysis law. Another object is to provide a spectral analysis burner with supply parts for the analysis sample, which reduce the effect of pressure variations, which act on this due to its preparation for spectral analysis. A further aim is to provide an improved spectral burner which is simple in construction and inexpensive to manufacture.

Uppfinningen kommer i det f6ljande att beskrivas nfirmare med han.visning till bifaga.de ritning, vilken som exempel visar en utforingsform. Fig. 1 ür ett vertikalt axialsnitt genom en spektralanalysbrannare enligt foreliggande uppfinning. Fig. 2 är ett snitt efter linjen 2-2 I fig. 1 Arnie en vy uppifrfin av brannaren. Fig. 3 dr en sidovy av apparaten sedd i riktningen for pilen 3 i fig. 1. Fig. 4 är en sidovy av en del av apparaten sedd i riktningen for Filen 4 i fig. 2. Fig. 5 är ett snitt efter linj en 5-5 i fig. 1. Fig. 6 är ett snitt i storre skala efter linjen 6-6 i -fig. 1. Fig. 7 Or ett snitt i storre skala efter linjen 7-7 i fig. 1. Fig. 8 är ett snitt i storre skala efter linjen 8---8 i fig. 1. The invention will be described in more detail below with reference to the accompanying drawing, which shows by way of example an embodiment. Fig. 1 is a vertical axial section through a spectral analysis burner according to the present invention. Fig. 2 is a sectional view taken along line 2-2. In Fig. 1 Arnie is a top view of the burner. Fig. 3 is a side view of the apparatus seen in the direction of the arrow 3 in Fig. 1. Fig. 4 is a side view of a part of the apparatus seen in the direction of the File 4 in Fig. 2. Fig. 5 is a section along line one. 5-5 in Fig. 1. Fig. 6 is a section on a larger scale along the line 6-6 in Figs. Fig. 7 Or a section on a larger scale along the line 7-7 in Fig. 1. Fig. 8 is a section on a larger scale along the line 8 --- 8 in Fig. 1.

Analysapparaten ,enligt foreliggande uppfinning omfattar en. spektralbrdnnare 12 och ett ventilblock 14, som fir forbundet med brannaren genom stela ror 16 och 18, som uppbara brannaren 12 och leda en. brannbar gasblandning frail ventilhuset till brannaren. Ventilhuset dr fdst i en tdckplatta 20 med bultar 21. Mellan huset och plattan Or inlagt en packning 22. Tfickplattan är forsedd med bultar 24 for 'monterin g av apparaten ph ett icke visat stativ. The analyzer according to the present invention comprises a. spectral burner 12 and a valve block 14, which is connected to the burner by rigid tubes 16 and 18, which support the burner 12 and guide one. combustible gas mixture frail the valve body to the burner. The valve housing is housed in a cover plate 20 with bolts 21. A gasket 22 is inserted between the housing and the plate 22. The pocket plate is provided with bolts 24 for mounting the apparatus on a stand (not shown).

.Brannaren 12 omfattar en huvudkropp 26 med .ett .centralt, fvertikalt borrhal 28, som bildar en vertikal kanal fOr den brannbara gasblandningen. Derma bestar av ett lampligt, gasformigt bransle, sasom propen eller cyan, och -en gas for underhallande av f6rbrdnning, exempelvis syre. Borrhalet stacker sig till kroppens ovre ande eller spets till ett centralt hhl 30 i ,densamma. Ett smalt kapillarror 32 stracker sig genom borrhalet med sin owe mynning i hfilet 30 fOr infOrande av den vatska, som skall analyseras, i brannarens huvadlaga, vars nedre ande bildas vid Met 30, for att bilda spektrallagan. Rorets 32 diameter är nfigot mindre On hfilets 30 diameter, sO att den brannbara gasblandningen kan strOmma ut frau brannarkrappen till spektrallagan. Roret 32 Or anordnat i en kapilldrhylsa 34, som Mlles centralt i borrhfilet 28 med skruvar 36, sh. att ett .mellanrum bildas 'mellan borrhalets insida och kapilldrhylsan.s utsida fOr gasblandningens stronming. Roren 32 och 34 arc forbundna med en propp 38, som Or inskruvad I nedre anden av kroppen 26 f Or att h011a rOren i Idge i borrhhlet 28. The burner 12 comprises a main body 26 with a central, vertical drill bit 28, which forms a vertical channel for the combustible gas mixture. These consist of a suitable, gaseous fuel, such as propylene or cyan, and a gas for maintaining combustion, for example oxygen. The drill tail extends to the upper spirit or tip of the body to a central hhl 30 i, the same. A narrow capillary tube 32 extends through the drill tail with its owe orifice in the hole 30 to introduce the liquid to be analyzed into the main layer of the burner, the lower spirit of which is formed at Met 30, to form the spectral layer. The diameter of the tube 32 is slightly smaller than the diameter of the tube 30, so that the combustible gas mixture can flow from the burner scraper to the spectral layer. The rudder 32 is arranged in a capillary sleeve 34, which is placed centrally in the drill fillet 28 with screws 36, sh. that a gap is formed between the inside of the drill tail and the outside of the capillary sleeve for the flow of the gas mixture. The pipes 32 and 34 are connected to a plug 38, which is screwed into the lower spirit of the body 26 to hold the pipe in Idge in the borehole 28.

Fiera vertikala ror 40 Oro anordnade vid brannarkroppens 28 ovre del i en krans intill halet 30 samt placerade ph avsthnd frail varandra och frau krOkta urholkningar 42 i Ovre 2— — delen av kroppen. Dessa ror leda en. brannbar gasblandning avsedd att antandas vid rorens ovre andar for att bilda en krans sa.kerhets- gor, som omger spektrallagan och befinner sig tatt intill densamma for att forhindra slackning av spektrallagan. Pa grund av mellanrummet imellan roren 40 och brannarkroppens sidar 42 bildas ett varmeisolerande luftmellanrum mellan rZiren och brannarkroppens owe del, sá att varmeovergangen frail de heta roren till kroppen minskas .och det blir lattare att forhindra forangning av den provsubstans, som strommar genom roret 32. Denna forangning hr undvikas, fOr att ett konstant flode av provsubstans till spektrallagan skall erhallas. Wren 40 aro fasta i brannarkroppen vid sina nedre andar. Eftersom roren emellertid aro smala, OverfOres relativt obetydligt med varme genom varmeledning fran rOrens nedre delar till brannarkroppen. Man far salunda en effektiv spektrallagebrannare, vilken lampar sig val Mr astadkommande av en laga med hog temperatur, som är sarskilt lamplig for spektralanalys, utan att brannaren behover vattenkylas. Det md. i detta sammanhang framhallas, att den brannbara gasblandningen strommar med relativt hog hastighet till halet 30, sa att spektrallagan komquer att befinna sig nagot ,ovanfor brannarkroppens owe ande ur kontakt med kroppen och salunda icke overfora flagon storre mangd varme till brannaren. Den brannbara gasblandningen ledes .daremot med avsevart lag-re hastighet till sakerhetslagorna an till spektrallagan, sa att sakerhetslagorna brinna vid rorens 40 avre an:de och upphettar roren genom varmeledning. Ehuru endast Ire ror 40 visas pa. ritningarna, kan man inom ramen for uppfinningen anordna mer an ire rOr, on sa Onskas. Several vertical tubes 40 are arranged at the upper part of the burner body 28 in a ring next to the tail 30 and placed at a distance from each other and from the hollowed-out recesses 42 in the upper part of the body. These rudders lead one. combustible gas mixture intended to ignite at the upper spirits of the rudder to form a ring of safety elements surrounding the spectral layer and located adjacent thereto to prevent slackening of the spectral layer. Due to the space between the tubes 40 and the sides 42 of the burner body, a heat-insulating air gap is formed between the tube and the upper part of the burner body, so that the heat transfer from the hot tubes to the body is reduced and it becomes easier to prevent evaporation of the test substance flowing through the tube 32. This evaporation is avoided in order to obtain a constant flow of test substance to the spectral layer. Wren 40 are stuck in the body of the burner by their lower spirits. However, since the pipes are narrow, heat is transferred relatively insignificantly by heat conduction from the lower parts of the pipes to the burner body. Thus, an efficient spectral layer burner is obtained, which lamps are selected by producing a layer with a high temperature, which is particularly suitable for spectral analysis, without the burner having to be water cooled. It md. in this connection it is pointed out that the combustible gas mixture flows at a relatively high speed to the tail 30, so that the spectral layer comes to be slightly above the spirit of the burner body out of contact with the body and thus does not transfer a large amount of heat to the burner. The combustible gas mixture, on the other hand, is led at a considerably lower speed to the safety layers than to the spectral layer, so that the safety layers burn at the lower end of the tube 40 and heat the tubes by heat conduction. Although only Ire ror 40 is shown on. the drawings, more an ire rOr can be arranged within the scope of the invention, said Onskas.

ROret 16 leder den brannbara gasblandningen fran ventilhuset 14 till brann.aren 12 och rOrets mynning 41 är anordnad i brannarkroppens 26 nedre del saint star i fOrbindelse med en kanal 46, vilken i sin tur star i fOrbindelse med borrhalet 28. floret 18 leder den brannbara gasblandningen for tandlagorna fran ventilhuset 14 och rorets mynning 48 dr anordnad I nedre delen av brannarkroppen 26. Ett vertikalt ror 50 forbinder roret 18 med ett ringformigt organ 52, som är monterat pa. brannarkroppen, och star i fOrbindelse med en inre, ringformig kanal 54 i organet 52. Vart och ett av sakerhetslageroren 40 star vid nedre anden i fOrbindelse med en vertikal kanal 56 och en horisontell kanal 58 upptagna i brannarkroppen. Kanalen 58 star i fOrbindelse med den ringformiga kanalen 54. Roret 50 leder sdlunda den bra.nnbara gasblandningen till den. ringformiga kanalen 54, vilken verkar som fordelare .och fran vilken blandningen ledes till vart .och ett av roren 40 genom motsvarande hal 58 och 56. The pipe 16 leads the combustible gas mixture from the valve housing 14 to the burner 12 and the mouth 41 of the pipe is arranged in the lower part of the burner body 26 in connection with a duct 46, which in turn communicates with the bore 28. the gas mixture for the tooth layers from the valve housing 14 and the mouth of the pipe 48 is arranged in the lower part of the burner body 26. A vertical pipe 50 connects the pipe 18 to an annular member 52, which is mounted on. the burner body, and communicates with an inner annular channel 54 in the member 52. Each of the safety bearing members 40 communicates at the lower end with a vertical channel 56 and a horizontal channel 58 received in the burner body. The channel 58 communicates with the annular channel 54. The tube 50 thus leads the combustible gas mixture to it. annular channel 54, which acts as a distributor, and from which the mixture is led to each of the tubes 40 through corresponding halls 58 and 56.

Rorens 16 och 18 inloppsandar 60 och 62 aro monterade i ett block 64, som ar fast pa ventilhuset 14 vid ,dess ovre del med hj alp av en bull 66. Ventithusets Ovre del innehaller tva horisontella kanaler 68 och 70, som sta. i forbindelse med var sin av rorens 16 och 18 inloppsandar 60 och 62. I var och en av kanalerna 68 och 70 finnes en blandare 72, som i ena linden Ar skruvad pa en gangad tapp 74, vilken i sin tur dr inskruvad i blocket 64. Blandarens 72 yttre ytor aro anordnade avstand fran de sidovaggar och den. andvagg, som begransa kanalen 68, sá att den brann- bara gasblandningen strommar in i kanalen 68 och tranger in i blandaren genom ett hal 76 vid blandarrorets 78 ena ande. En serie bagarformiga blandarorgan 80 med hal 82 ar anordnad i blandarroret 78 och har till uppgift att intimt blanda brannbar gas och syrgas, som ledas till kanalerna 68 och 70, for att astadkomma den. brannbara gasblandningen for huvudlagan respektive sakerhetslagorna. De gaser, som bilda den brannbara blandningen, blandas pa ett stAlle, som ligger pa avstand fran brannaren, dvs i ventilhuset 14, varefter blandningen ledes till brannaren genom roren 16 och 18. Den brannbara blandningen strommar genom rOren 16 och 18 frail blandarna 72 genom en kanal 83 upptagen i vardera tappen 74. The inlet sands 60 and 62 of the pipes 16 and 18 are mounted in a block 64, which is fixed to the valve housing 14 at, its upper part by means of a ball 66. The upper part of the vent housing contains two horizontal channels 68 and 70, which stand. in connection with each of the inlet sands 60 and 62 of the tubes 16 and 18. In each of the channels 68 and 70 there is a mixer 72, which in one of the grooves is screwed onto a threaded pin 74, which in turn is screwed into the block 64. The outer surfaces of the mixer 72 are spaced from the side cradles and the. breathing wall, which defines the channel 68, so that the combustible gas mixture flows into the channel 68 and penetrates into the mixer through a hall 76 at one end of the mixing tube 78. A series of baker-shaped mixers 80 with halves 82 are arranged in the mixer tube 78 and have the task of intimately mixing combustible gas and oxygen, which is led to the channels 68 and 70, in order to provide it. combustible gas mixture for the main layer and the safety layers, respectively. The gases which form the combustible mixture are mixed at a place which is at a distance from the burner, i.e. in the valve housing 14, after which the mixture is led to the burner through the tubes 16 and 18. The combustible mixture flows through the tubes 16 and 18 from the mixers 72 through a channel 83 received in each pin 74.

De gaser, sam bilda den. brannbara blandningen, ledas till ventilhuset 14 frail icke visade flaskor eller andra lampliga behallare. Ventilhuset Ar salunda forsett med en anslutning 84 for tillforsel av brannbar gas och en anslutning 86 fo,r tillforsel av den forbranningen underhallande gasen. Nalventiler aro anordnade i ,ventilhuset 14 for reglering av den mangd gas, som ledes till blandarna 72. Dessa nalventiler dro identiska sa att tillforseln av brannbar gas och av forbranning underhallande gas regleras pa samma satt Mr bade spektrallagan och sakerhetslagorna. Anslutningen 84 for tillforsel av brannbar gas star i forbindelse med en kanal 88 i ventilhuset, medan anslutningen 86 Rir tillfOrsel av forbranning underhallande gas star i fOrbindelse med en kanal 90 i ventilhuset. En vertikalkanal 92 I ventilhuset forbinder kanalen 88 med en kanal 94. Denna har en mynning 96, vars genomstrOmningsarea regleras med en nalventil 98, som reglerar tillforseln av bransle till spektrallagan. En vertikal kanal 100 i ventilhuset fOrbinder kanalen 90 med en kanal 102, vars mynning regleras med en nalventil 104 for reglering av tillfOrseln av forbranning underhallande gas till spektrallagan. En kanal 106 forbinder kanalen 68 med en urborrning 108, som star i fOrbindelse med kanalen 94. En kanal 11:0 f8rbinder kanalen 106 med en urborrning 112, som star i fOrbindelse med kanalen 102. Forbranning underhallande gas, som passerar genom kanalen 110, ledes salunda till kanalen 106, dar den sammanfores med en strain av brannbar gas, varefter den — — bildade blandningen ledes till kanalen 68 genom en del av kanalen 106 och infores i blandaren 72, som ãr anordnad i kanalen 68. Fran blandaren 'ledes gasblandningen till brannaren for spektrallagan genom riiret 16. The gases, together form it. flammable mixture, is led to the valve housing 14 frail bottles (not shown) or other suitable containers. The valve housing is thus provided with a connection 84 for supplying combustible gas and a connection 86 for supplying the combustion gas. Needle valves are arranged in the valve housing 14 for regulating the amount of gas which is led to the mixers 72. These needle valves are so identical that the supply of combustible gas and of combustion-entertaining gas is regulated in the same way as both the spectral law and the safety laws. The connection 84 for the supply of combustible gas is connected to a channel 88 in the valve housing, while the connection 86 is connected to the supply of combustion entertaining gas and is connected to a channel 90 in the valve housing. A vertical channel 92 in the valve housing connects the channel 88 to a channel 94. This has a mouth 96, the flow area of which is regulated by a valve valve 98, which regulates the supply of fuel to the spectral layer. A vertical channel 100 in the valve housing connects the channel 90 to a channel 102, the mouth of which is controlled by a needle valve 104 for controlling the supply of combustion-sustaining gas to the spectral layer. A duct 106 connects the duct 68 to a bore 108 which communicates with the duct 94. A duct 11: 0 connects the duct 106 to a bore 112 which communicates with the duct 102. Combustion entertaining gas which passes through the duct 110, is thus passed to the duct 106, where it is combined with a strain of combustible gas, after which the formed mixture is led to the duct 68 through a part of the duct 106 and introduced into the mixer 72, which is arranged in the duct 68. From the mixer 'the gas mixture is led to the spectral layer burner through ring 16.

Gasblandningen for sakerhetslagorna ledes pa liknande satt till brannaren. Ett riir 114 MI-binder kanalen 92 for den brannbara gasen med en kanal 116, vars mynning 118 regleras med en nalventil 120, vilken styr tiliforseln av brannbar gas till sakerhetslagorna. Reret 114 har relativt liten diameter och leder relativt smâ mangder brannbar gas frail kanalen 92, eftersom sakerhetslagorna behiiva avsevart mindre brannbar gas an spektrallagan. Tack vare det smala roret 114 blir det mojligt att med ventilen 120 effektivt reglera tillfOrseln av brannbar gas till sakerhetslagorna, varigenom det Mir overflodigt att anordna mycket tunna Ml for den brannbara gasen i ventilhuset och motsvarande mycket sma nalventiler for reglering av gasflodet i sadana tunna Ett small riir 122 forbinder vidare kanalen 100 med kanalen 124, vars mynning regleras med en nalventil 126 for reglering av den mangd forbranning underhallande gas, som ledes till sakerhetslagorna. En. kanal 128 i ventilhuset forbinder kanalen 70 med en oppning 130, som star i forbindelse med kanalen 124, och en kanal 132 i ventilhuset fOrbinder kanalen 128 med en Oppning 134, som star i forbindelse med kanalen 116, sa att den brannbara gas, som strommar i kanalen 132 for att inforas sakerhetslagorna, blandas med den f8rbranning underhallande gas, som strOmmar i kanalen 128 fOr sakerhetslagorna, varefter den bildade ga.sblandningen ledes till kanalen 70 genom en del av kanalen 128 for att infOras i blandaren 72 i kanalen 70 och sedan stromma fran blandaren till brannaren genom roret 18. The gas mixture for the safety laws is led in a similar way to the burner. A tube 114 MI-binds the flammable gas channel 92 with a channel 116, the mouth 118 of which is controlled by a needle valve 120, which controls the supply of flammable gas to the safety laws. The tube 114 has a relatively small diameter and conducts relatively small amounts of combustible gas from the channel 92, since the safety layers have considerably less combustible gas than the spectral layer. Thanks to the narrow pipe 114, it becomes possible with the valve 120 to effectively regulate the supply of combustible gas to the safety laws, whereby it is superfluous to arrange very thin M1 for the combustible gas in the valve housing and corresponding very small valve valves for regulating the gas flow in such barrels. The small pipe 122 further connects the duct 100 to the duct 124, the mouth of which is controlled by a needle valve 126 for regulating the amount of combustion-entertaining gas which is led to the safety laws. One. channel 128 in the valve housing connects the duct 70 to an opening 130 which communicates with the duct 124 and a duct 132 in the valve housing connects the duct 128 to an opening 134 which communicates with the duct 116 so that the combustible gas flowing in the duct 132 to be introduced into the security layers, is mixed with the combustion entertaining gas flowing in the duct 128 for the security layers, after which the formed gas mixture is passed to the duct 70 through a part of the duct 128 to be introduced into the mixer 72 in the duct 70 and then flow from the mixer to the burner through the rudder 18.

En kapa 136 ar fast i ventilhuset med en bull 138 och tacker roren 114 och 122 for att skydda dessa. Ett ror 140 16r tillforsel av provsubstans är anordnat pa ventilhusets 14 sida och fast i ventilhuset med hjalp av en bygel 112. Provsubstansroret omfattar en serie tatt lindade rorslingor, som bilda en cirkular stromningsbana for substansen mellan rorets inloppsande 146 och dess utloppsande 148. Denna fir forbunden med inloppsanden 150 till provsubstansroret 32 i bra_nnaren med hjalp av ett joke visat ror. ROrets 110 relativt ringa innerdiameter, som lampligen är lika med eller mindre an rOrets 32 innerdiameter och den langa stromningsvag far provsubstansen, som bildas av slingorna 144, medfora ett avsevart strOmningsmotstand .och &liar trycket i tillforselroret 140, sa att provsubstansen ledes jamnare till brannaren, emedan det hoga tryeket minskar inverkan av tryckvariationer I substansen, vilka kunna upptrada till foljd av forberedningen av substansen fOr spektralanalysen. A cutter 136 is fixed in the valve housing with a ball 138 and thanks the tubes 114 and 122 to protect them. A pipe 140 16r supply of test substance is arranged on the side of the valve housing 14 and fixed in the valve housing by means of a bracket 112. The test substance pipe comprises a series of taken wound pipe tubes, which form a circular flow path for the substance between the pipe inlet 146 and its outlet 148. connected to the inlet sand 150 to the test substance tube 32 in the well with the aid of a joke shown tube. The relatively small inner diameter of the tube 110, which is suitably equal to or less than the inner diameter of the tube 32 and the long flow path of the test substance formed by the loops 144, cause a considerable flow resistance and reduce the pressure in the supply tube 140 so that the test substance is directed more evenly to the burner. because the high pressure reduces the effect of pressure variations in the substance, which can occur as a result of the preparation of the substance for the spectral analysis.

Claims

Patent claim:

A spectral burner apparatus comprising a burner body (10) having a burner tip (30), a channel (28) for a combustible gas mixture to form a main layer adjacent to the tip, and a capillary tube (32) for liquid sample substance drawn to the tip for introducing a stream of the substance in the flame has through the tube for spectral analysis of the test substance for determination of one or more constituents therein, characterized in that it is represented by a device (18, 50, 52) arranged on the burner body, which comprises at least one narrow root. (40) with an outlet portion adjacent the burner tip, although at a lateral distance from the same, for supplying a combustible gas mixture to form a safety flange. the main layer without overheating the air burner tip (30), so that evaporation of the test liquid may be introduced into the main layer.

Apparatus according to claim 1, characterized in that the device for forming the air safety act comprises one or more further small tubes (40) of the same type.

Apparatus according to claim 2, characterized in that the small tubes (10) for forming the safety layer are arranged with their mouths distributed around the burner tip ph distance therefrom.

Apparatus according to patent claim 2 or 3, characterized in that a feed chamber (52) for combustible gas mixture for the safety law is arranged at the burner at a distance from the burner tip (30), and that the small tubes (40) are connected to the feed chamber and extend away from it. this to the laws of their mouths.

Apparatus according to any one of the preceding claims, characterized by a mixer unit (14) for mixing fuel and a combustion entertaining gas, before the combustible mixture is introduced into the burner tip (30) for the main layer and the small pipe (s) (10). for the safety law, which mixer unit 1 (14) is provided with valves (98, 104, 120, 12: 6) for regulating the relative proportions between the fuel and the combustion-maintaining gas, which are mixed in the mixer unit.

Apparatus according to patent claim 5, characterized in that the mixing unit (VI) comprises a mixing chamber (68) Mr the combustible mixture for the main layer and one. a separate mixing chamber (70) for the combustible mixture for the safety layer, and that separate control valves (104, 106) are provided for each mixing chamber. Cited publications: