SI9110667A

SI9110667A - burner

Info

Publication number: SI9110667A
Application number: SI9110667A
Authority: SI
Inventors: Willem Meijer
Original assignee: Dru Bv
Priority date: 1990-04-12
Filing date: 1991-04-12
Publication date: 1994-06-30
Also published as: DE69105588D1; NO911413D0; LTIP1567A; HUT60027A; EP0451923A2; FI911764A0; EP0451923A3; ATE115260T1; YU66791A; HU911220D0; EP0451923B1; JPH04225709A; PL165631B1; BG94249A; NL9000883A; DK0451923T3; RU2042883C1; NO911413L; CS104091A2; FI911764A

Abstract

A burner (1) is provided, comprising a primary mixture supply conduit (2) and a primary mixture chamber (6) connected with the supply conduit (2), the primary mixture chamber (6) having primary discharge openings (7) for discharging burning mixture into the space surrounding the burner (1). The burner (1), which may be made of a ceramic material, which may be made of a ceramic material, further comprises flame stabilizing means arranged near the primary discharge openings (7). The flame stabilizing means may be vortex strips (14) separating areas (16) of discharge openings (7), or they may be secondary discharge openings (5), discharging burning mixture from a secondary mixture chamber (3) near the primary discharge openings (7). <IMAGE>

Description

Izum se nanaša na gorilnik, obsegajoč primarni vod za dovajanje mešanice gorljivega plina in zraka; vsaj eno primarno mešalno komoro, obsegajočo vsaj eno dotočno odprtino povezano s primarnim vodom za dovod mešanice, pri čemer je premer odprtine enakega reda kot premer primarnega voda za dovod mešanice, in vsaj eno primarno odtočno odprtino, katera odvaja v prostor okoli gorilnika in katere premer je majhen relativno glede na premer primarnega voda za dovod mešanice.The invention relates to a burner comprising a primary conduit for supplying a mixture of combustible gas and air; at least one primary mixing chamber comprising at least one inlet port connected to the primary inlet line for the mixture, the diameter of the opening being in the same order as the diameter of the primary inlet line for the mixture, and at least one primary outlet opening to the space around the burner and whose diameter is small relative to the diameter of the primary supply line of the mixture.

Tovrstne gorilnike se je že pogosto uporabljalo za grelne namene. Znani gorilniki pa imajo pomanjkljivost, da se pri visokih obremenitvah gorilnika (kadar zgoreva velika količina mešanice na enoto časa) pojavljajo visoke zgorevalne temperature v zgorevalni mešanici. Pri teh visokih zgorevalnih temperaturah se tvorijo velike količine dušikovega oksida (ΝΟ_χ).Burners of this type have long been used for heating purposes. Known burners, however, have the disadvantage that, at high burner loads (when a large amount of the mixture per unit of time is combusted), high combustion temperatures occur in the combustion mixture. At these high combustion temperatures large amounts of nitric oxide (ΝΟ _χ ) are formed.

Nadaljnja pomanjkljivost teh znanih gorilnikov leži v tem, da so nastavljivi le v omejenem območju obremenitev. Kadar se jih uporablja pri grelnih instalacijah, je potrebno znane gorilnike redno prižigati in ugašati, da bi se temperaturo vzdrževalo znotraj podanega območja. To ne vodi le k manjši prikladnosti za uporabnika temveč se odraža tudi v pospešeni obrabi grelne instalacije. Nadalje se vsakokrat, ko se gorilnik prižge ali ugasne, oddaja snovi, ki so škodljive ljudem in okolju.A further disadvantage of these known burners lies in the fact that they are adjustable only in a limited load range. When used in heating installations, known burners should be regularly switched on and off in order to maintain the temperature within the specified range. Not only does this lead to less user-friendliness, it also results in accelerated wear of the heating installation. Furthermore, every time a burner is lit or extinguished, substances that are harmful to humans and the environment are emitted.

Omejena nastavljivost znanih gorilnikov je posledica dejstva, da ko s porastom dovoda mešanice naraste moč gorilnika, hitrost pri določeni točki, pri kateri mešanica, ki naj zgori, izstopa iz primarne odtočne odprtine, presega njeno hitrost zgorevanja. Zato je plamen odpihnjen in gorilnik izgine.The limited adjustability of the known burners is due to the fact that as the supply of the mixture increases as the burner power increases, the velocity at a certain point at which the mixture to burn out of the primary outlet exceeds its combustion rate. Therefore, the flame is blown away and the burner disappears.

Zato je naloga predloženega izuma ustvariti gorilnik z izboljšano nastavljivostjo glede na zgoraj opisane gorilnike in kjer se vzdržuje sorazmerno nizko temperaturo zgorevanja po celotnem območju obremenitev. To se po izumu doseže s sredstvom za stabiliziranje plamena, razporejenim poleg primarne odtočne odprtine.Therefore, it is an object of the present invention to provide a burner with improved flexibility with respect to the burners described above and where a relatively low combustion temperature is maintained throughout the load range. This is achieved by the invention by means of a flame stabilizer arranged adjacent to the primary outlet.

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Z uporabo sredstva za stabiliziranje plamena v bližini odtočne odprtine primarne mešalne komore se lahko vzdržuje stabilno zgorevanje, ki se lahko pojavi tudi zunaj gorilnika, preko širokega območja obremenitev. Kot posledica premera primarne odtočne odprtine, kije majhna relativno glede na premer primarnega voda za dovod mešanice, se v njej pri visokih obremenitvah razvije visoka pretočna hitrost mešanice, ki naj zgori. Tako se razvije pahljačasta plamenska fronta velike površine, pri čemer se zgorevalno temperaturo drži sorazmerno nizko (velikostnega razreda 1000-1100°C), s čimer tako zgorevanje čisti. Sredstvo za stabiliziranje plamena deluje tako, da obdrži zgorevalno hitrost v vsaj eni točki plamenske fronte v bistvu enako odtočni hitrosti mešanice, ki naj zgori, pri čemer plamen v tej točki počiva. Ta točka stabilizira zgorevanje v preostanku plamenske fronte.By using a flame stabilizer near the outlet opening of the primary mixing chamber, stable combustion, which may occur outside the burner, over a wide range of loads, can be maintained. As a result of the diameter of the primary outlet opening, which is small relative to the diameter of the primary inlet line for the mixture, a high flow rate of the mixture to be burnt develops at high loads. In this way, a large flame flame front develops, keeping the combustion temperature relatively low (size class 1000-1100 ° C), keeping the combustion clean. The flame stabilizer operates by keeping the combustion rate at at least one point of the flame front substantially equal to the outflow velocity of the mixture to be burnt, leaving the flame at that point. This point stabilizes combustion in the rest of the flame front.

Kadar ima primarna mešalna komora niz odtočnih območij, v katerih so razporejene primarne odtočne odprtine, v pravilnem vzorcu, sredstvo za stabiliziranje plamena pa ima obliko vrtinčnih trakov, ki mesebojno ločujejo odtočna območja, je na enostaven način zagotovljen čvrst gorilnik z izboljšano nastavljivostjo.When the primary mixing chamber has a series of drainage areas in which the primary drainage openings are arranged, in the correct pattern, and the flame stabilizer has the form of swirl strips separating the drainage zones in a simple way, a solid burner with improved adjustability is easily provided.

Gorilnik je prednostno zasnovan iz keramičnega materiala. Keramični gorilniki imajo zelo čisto zgorevanje v primeri z običajnimi jeklenimi gorilniki. Pri uporabi keramičnega gorilnika je zlasti močno zmanjšana emisija dušikovega oksida. To je zaradi izolacijskega delovanja keramičnega materiala, pri čemer se vzdržuje sorazmerno nizko temperaturo zgorevanja. Izolacijsko delovanje keramičnega materiala nadalje preprečuje, da bi se mešanica plin-zrak pregrela v dovodnem vodu gorilnika. To je pomembno, kajti s pregrevanjem pride do disociacije mešanice in s tem tvorbe dušikovega oksida že v dovodnem vodu.The burner is preferably made of ceramic material. Ceramic burners have very clean combustion when compared to conventional steel burners. When using a ceramic burner, the emission of nitrous oxide in particular is greatly reduced. This is due to the insulating action of the ceramic material while maintaining a relatively low combustion temperature. The insulating action of the ceramic material further prevents the gas-air mixture from overheating in the burner supply line. This is important because overheating leads to the dissociation of the mixture and thus the formation of nitric oxide already in the supply line.

Nadalje se z uporabo keramičnega gorilnika s sredstvom za stabiliziranje plamena po izumu izognemo pomanjkljivosti, da so keramični gorilniki nastavljivi le znotraj majhnega območja obremenitev.Furthermore, the use of a ceramic burner with a flame stabilizer according to the invention avoids the disadvantage that ceramic burners are adjustable only within a small load range.

Omenjene in druge značilnosti gorilnika po izumu so nadalje pojasnjene sklicujoč se na niz primerov, prikazanih v priloženem načrtu, kjer so enaki deli označeni z enakimi referenčnimi številkami, in kjer kaže sl. 1 delno odrezan perspektivni pogled prvega izvedbenega primera gorilnika po izumu, sl. 2 zgorevanje pri nizki obremenitvi, v detajlnem pogledu vzdolž puščice Π,The foregoing and other features of the burner according to the invention are further explained with reference to the set of examples shown in the accompanying drawing, wherein the same parts are denoted by the same reference numbers and where FIG. 1 is a partially cut-away perspective view of a first embodiment of a burner according to the invention; FIG. 2 low load combustion, in detailed view along the arrow Π,

21590PR0.IV sl. 3 in 4 zgorevanje pri povečani obremenitvi v pogledu, ustreznem onemu s sl. 2, sl. 5 prvi izvedbeni primer gorilnika po izumu z veliko grelno kapaciteto, zgrajenega iz modulov, sl. 6 drugi izvedbeni primer gorilnika po izumu, sl. 7 delno izrezan perspektivni pogled tretjega izvedbenega primera gorilnika po izumu, sl. 8 detajl gorilnika s sl. 7 v prečnem prerezu, pri visoki zgorevalni obremenitvi, in sl. 9 pogled, ustrezajoč onemu s sl. 8, v prečnem prerezu, pri nizki zgorevalni obremenitvi.21590PR0.IV fig. 3 and 4 combustion at increased load in a view corresponding to that of FIG. 2, FIG. 5 is a first embodiment of a burner according to the invention having a large heating capacity constructed from modules, FIG. 6 is another embodiment of the burner of the invention; 7 is a partially cut-away perspective view of a third embodiment of the burner of the invention, FIG. 8 is a detail of the burner of FIG. 7 in cross section, at high combustion load, and FIG. 9 is a view corresponding to that of FIG. 8, in cross section, at low combustion load.

Keramični gorilnik 1 (sl. 1) obsega primarni vod 2 za dovod mešanice, okoli katerega je razporejena obročasta druga mešalna komora 3, da bi stabilizirala plamen gorilnika 1, pri čemer je omenjena komora preko obodno razmaknjenih, radialnih drugih vodov 4 za dovod mešanice povezana s primarnim vodom 2 za dovod mešanice. Druga mešalna komora 3 je preko druge odtočne odprtine 5 povezana s prostorom, ki obdaja gorilnik. Prvi vod 2 za dovod mešanice dovaja v cilindrično primarno mešalno komoro 6, ki je preko niza obodno razmaknjenih, radialnih primarnih odtočnih odprtin 7 povezana s prostorom, ki obdaja gorilnik 1.The ceramic burner 1 (Fig. 1) comprises a primary conduit 2 for the mixture inlet, around which an annular second mixing chamber 3 is arranged in order to stabilize the flame of the burner 1, said chamber being connected via circumferentially spaced, radial other conduits 4 for supplying the mixture. with primary water 2 to supply the mixture. The second mixing chamber 3 is connected to the space surrounding the burner through the second outlet 5. The first conduit 2 feeds the mixture into the cylindrical primary mixing chamber 6, which is connected to the space surrounding the burner 1 through a series of circumferentially spaced, radial primary drainage openings 7.

Primarna in sekundama mešalna komora 6, 3 sta zasnovani z zložljivima koncentričnima obročastima elementoma 9,10. Z zlaganjem več teh elementov 9, 10 na način, prikazan na sliki, se da enostavno sestaviti gorilnik z zahtevano grelno kapaciteto.The primary and secondary mixing chambers 6, 3 are designed with folding concentric annular elements 9,10. By stacking several of these elements 9, 10 in the manner shown in the figure, it is easy to assemble a burner with the required heating capacity.

Mešanica plin-zrak, ki se jo dovaja skozi primarni vod 2 (sl. 2, 3 in 4), se deli po sekundarni mešalni komori 3 (kot je označeno s puščicami S) in primarni mešalni komori 6 (označeno s puščicami P). Pri nizkih obremenitvah (sl. 2) je hitrost toka mešanice sorazmerno nizka, zgorevanje primarnega toka P mešanice pa poteka v primarni odtočni odprtini 7. Plamenska fronta 11 je v tem primeru lokasta. Keramični gorilnik učinkuje kot vir toplotnega sevanja, kajti keramični material, ki obdaja primarne odtočne odprtine 7, žari.The gas-air mixture supplied through the primary conduit 2 (Figures 2, 3 and 4) is divided by the secondary mixing chamber 3 (indicated by arrows S) and the primary mixing chamber 6 (indicated by arrows P). At low loads (Fig. 2), the flow velocity of the mixture is relatively low, and the combustion of the primary flow P of the mixture takes place in the primary outlet 7. The flame front 11 is in this case arched. The ceramic burner acts as a source of heat radiation, because the ceramic material surrounding the primary drainage openings 7 glows.

Ko obremenitev naraste (sl. 3), naraste hitrost toka mešanice, in ker se zgorevalna hitrost ne spremeni, se zgorevanje premakne ven iz gorilnika 1. Plamenske fronte počivajo sedaj na zunanjem robu gorilnika 1 in so še vedno lokaste.As the load increases (Fig. 3), the flow velocity of the mixture increases, and since the combustion rate does not change, the combustion moves out of the burner 1. The flame fronts now rest on the outer edge of the burner 1 and are still arched.

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Z nadalje naraščajočo obremenitvijo (sl. 4) hitrost toka mešanice še nadalje naraste in preseže zgorevalno hitrost mešanice za tak znesek, da bi plamen lahko odpihnilo. Vendar pa je primarni tok P mešanice pregret s prisotnostjo sekundarnega toka S mešanice, ki teče od sekundarne mešalne komore 3, pri čemer zgorevalna hitrost primarnega toka P mešanice naraste in postane v vsaj eni točki plamenske fronte v bistvu enaka odtočni hitrosti le-te, tako da se razvije stabilen plamen. Zaradi visoke hitrosti primarnega toka P mešanice v primarnih odtočnih odprtinah 7 privzame plameska fronta 11 pahljačasto obliko. Ker ima takšna pahljačasta plamenska fronta 11 večjo površino kot primerljiva lokasta plamenska fronta, zgorevanje pa je tako razpršeno po večjem območju, je zgorevalna temperatura nižja kot v primerljivi lokasti plamenski fronti, s čimer se močno zmanjša tvorjenje dušikovega oksida.With increasing load (Fig. 4), the flow rate of the mixture continues to increase and exceeds the combustion rate of the mixture by such an amount that the flame can blow. However, the primary flow P of the mixture is overheated by the presence of a secondary flow S of the mixture flowing from the secondary mixing chamber 3, whereby the combustion rate of the primary flow P of the mixture increases and becomes substantially equal to the outlet velocity thereof at at least one point of the flame front. to develop a stable flame. Due to the high velocity of the primary flow P of the mixture in the primary drainage openings 7, the flame front 11 takes on a fluffy shape. Because such a fluffy flame front 11 has a larger surface area than a comparable arc flame front, and combustion is thus dispersed over a larger area, the combustion temperature is lower than that of a comparable arc flame front, thereby greatly reducing nitric oxide formation.

Grelna kapaciteta keramičnega gorilnika po izumu je lahko nadalje povečana s povezavo več skladov obročastih elementov 9, 10 s skupnim glavnim dovodnim vodom 12 (sl. 5). V glavni dovodni vod 12 se dovaja mešanico plin-zrak z injektoijem 13, skozi katerega je plin G vbrizgan v glavni dovodni vod 12 s tako visoko hitrostjo, da hkrati posesa zrak A.The heating capacity of the ceramic burner according to the invention can be further increased by connecting several stacks of annular elements 9, 10 with a common main supply line 12 (Fig. 5). A gas-air mixture is injected into the main inlet duct 12 with an injector 13 through which gas G is injected into the main inlet duct 12 at such a high rate that it simultaneously sucks air A.

Kadar je potrebno spreminjati grelno kapaciteto, modularni sklop grelnega sistema pa ni zahtevan, zadostuje keramični gorilnik kot je prikazan na sl. 6. Klinasta zasnova glavnega dovodnega voda 12 zagotavlja enakomerno porazdelitev mešanice plin-zrak po z zarezami zasnovanem primarnem vodu 2 v ta gorilnik 1.When it is necessary to change the heating capacity and the modular assembly of the heating system is not required, a ceramic burner as shown in FIG. 6. The wedge design of the main inlet duct 12 ensures a uniform distribution of the gas-air mixture through the notch-shaped primary conduit 2 into this burner 1.

Čeprav so v prikazanih primerih sekundarni vodi 4 vsakokrat povezani s primarnim vodom 2 je lahko seveda predvideno, da se poveže sekundarni vod 4 z virom gorljive mešanice neodvisno od primarnega voda 2. Tako je v vseh okoliščinah zagotovljen dobro goreč stabiliziran plamen.Although in the examples shown above, the secondary conduits 4 are each connected to the primary conduit 2, it can, of course, be envisaged to connect the secondary conduit 4 to the source of the combustible mixture independently of the primary conduit 2. Thus, in all circumstances a well-ignited stabilized flame is provided.

Alternativni izvedbeni primer keramičnega gorilnika po izumu uporablja sredstvo za stabiliziranje plamena v obliki ti. vrtinčnih trakov 14 (sl. 7). V tem izvedbenem primeru je primarna mešalna komora 6 pokrita na svoji zgornji strani z gorilnikovo ploščo 15, v kateri je razporejeno veliko število primarnih odtočnih odprtin 7. Slednje so razporejene v pavilnem vzorcu v nizu ločenih odtočnih območij 16, ki so ločena z vrtinčnimi trakovi 14.An alternative embodiment of the ceramic burner according to the invention uses a flame stabilizer in the form of ti. vortex strips 14 (Fig. 7). In this embodiment, the primary mixing chamber 6 is covered on its upper side by a burner plate 15 in which a large number of primary drainage openings 7 are arranged. The latter are arranged in a pavilion pattern in a series of separate drainage areas 16 separated by swirling strips 14 .

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Vrtinčni trakovi 14 tvorijo področja zmanjšanih hitrosti toka med odtočnimi območji 16, v katerih se vrtinči naokoli topla mešanica, ki vžiga mešanico, dotekajočo z visoko hitrostjo. Zato so tudi pri visokih obremenitvah gorilnika (sl. 8) točke v plamenski fronti 11, kjer je zgorevalna hitrost v bistvu enaka odtočni hitrosti mešanice. Tako plamen počiva na teh točkah, celotna plamenska fronta pa je stabilizirana.Vortex strips 14 form regions of reduced flow velocities between drainage areas 16 in which a swirling mixture is swirled around, which ignites the mixture flowing at high velocity. Therefore, even at high burner loads (Fig. 8), the points in the flame front 11, where the combustion rate is essentially equal to the discharge velocity of the mixture. Thus the flame rests at these points, and the entire flame front is stabilized.

Optimalni vzorec vrtinčnih trakov 14 na gorilnikovi plošči 15 in razmerje med širinami vrtinčnih trakov 14, dimenzijami odtočnih območij 16 in premeri ločenih odtočnih odprtin 7 lahko strokovnjak enostavno določi na osnovi iskušenj in poznavanja. Priporočljivo je izbrati nepravilen vzorec za vrtinčne trakove 14, da bi se kar je mogoče preprečilo pojav resonanc.The optimal pattern of vortex strips 14 on the burner plate 15 and the ratio of vortex stripe widths 14, dimensions of drainage areas 16 and diameters of separate drainage openings 7 can be easily determined by one skilled in the art on the basis of experience and knowledge. It is advisable to select an irregular pattern for vortex bands 14 to prevent resonance from occurring.

V prikazanem primeru je primarna mešalna komora 6 pravokotna. Mogoče spremembe v hitrosti toka mešanice plin-zrak zaradi te oblike komajda vplivajo na lastnosti gorilnika 1, kajti prisotnost vrtinčnih trakov 14 zagotavlja stabilnost zgorevanja po razširjenem območju obremenitev in s tem preko raznolikih hitrostih toka mešanice.In the example shown, the primary mixing chamber 6 is rectangular. Due to this shape, the possible changes in the gas-air flow rate of the mixture hardly affect the properties of the burner 1, since the presence of vortex strips 14 ensures the stability of combustion over an extended load range and thus over the various flow rates of the mixture.

Prikazan gorilnik 1 je nadalje opremljen s poravnalnim obročem 17, razporejenim okoli gorilnikove plošče 15, za zagotavljanje porazdelitve gorečega toka mešanice vzdolž roba plošče 15 znotraj oboda gorilnikove plošče 15, Pod navznoter raztezajočim se delom poravnalnega obroča 17 je razporejena zunanja vrsta odtočnih odprtin 7, od koder teče mešanica proti poravnalnemu obroču 17, pri čemer ponovno generira vrtinec za stabiliziranje plamena. Med poravnalnim obročem 17 in gorilnikovo ploščo 15 je predvideno pletivasto mašivo 18 iz keramičnega materiala.The illustrated burner 1 is further provided with an alignment ring 17 arranged around the burner plate 15 to provide a distribution of the combustion flow of the mixture along the edge of the plate 15 within the circumference of the burner plate 15. where the mixture flows toward the alignment ring 17, again generating a vortex to stabilize the flame. Between the alignment ring 17 and the burner plate 15 there is provided a knit mass 18 of ceramic material.

Razume se, da se poleg zgoraj opisanega sredstva za stabiliziranje plamena lahko uporabi tudi druga sredstva za stabiliziranje zgorevanja pri visokih hitrostih dovajanja mešanice. Trakovi hladilnega materiala, na katerem se zgorevanje lahko stabilizira, se lahko npr. razporedi na določeni razdalji oz primarnih odtočnih odprtinIt is understood that, in addition to the flame stabilizer described above, other combustion agents may be used at high feed rates. Tapes of cooling material on which combustion can be stabilized may e.g. distributes at a certain distance or primary drains

7. Nadalje se lahko predvidi uporabo kombinacije poprej opisanih sredstev za stabiliziranje plamena.7. It may further be envisaged to use a combination of the flame stabilizing agents described above.

Claims

PATENT APPLICATIONS

1. Burner (1), comprising:

- a primary conduit (2) for supplying a mixture of combustible gas and air;

- at least one primary mixing chamber (6) comprising at least one inlet port connected to the primary conduit (2) for supplying the mixture, the diameter of the orifice being in the same order as the diameter of the primary conduit (2), and at least one primary drainage orifice (7) , which discharges into the space surrounding the burner (1) and whose diameter is small relative to the diameter of the primary conduit (2);

characterized in that the flame stabilizer is arranged adjacent to the primary outlet opening (7).

Burner according to claim 1, characterized in that the primary mixing chamber (6) comprises a series of drainage areas with primary drainage openings (7) arranged therein in the correct pattern, and that the flame stabilizer is designed as vortex strips, which they separate the drainage areas from one another.

Burner according to claim 2, characterized in that the swirl bands (14) form an irregular pattern on the burner plate (15), covering the primary mixing chamber (6).

Burner according to any one of the preceding claims, characterized in that the burner (1) is made of ceramic material.

Burner according to claim 5, characterized in that the flame stabilizers are designed with at least one secondary mixing chamber (3) connected to at least one secondary conduit (4) for supplying the mixture and which is via at least one secondary drain openings (5) connected to the space surrounding the burner (1), the opening (5) being distributed in addition to the primary outlet opening (7), the diameters of the secondary conduit (4) and the secondary openings (5) being small relative to the primary water (2) to feed the mixture.

Burner according to claim 5, characterized in that the secondary supply line (4) is connected to the primary supply line (2) for the mixture supply.

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Burner according to claim 6, characterized in that the secondary mixing chamber is annular and arranged around the primary conduit (2) and comprising several circumferentially spaced radial secondary conduits (4), and that the primary mixing chamber (6) is positioned downwards with respect to secondary water (4), has the shape of a cylinder concentric with the primary water (2) and comprising several circumferentially spaced radial primary drainage openings (7).

Burner according to claim 7, characterized in that the set of primary and secondary mixing chambers (6, 3) is arranged in series, each primary mixing chamber (6) distributed in the direction of flow between successive secondary mixing chambers (3 ), a flow orifice arranged opposite its inlet orifice.

Burner according to claim 5, characterized in that the primary conduit (2) is slit-shaped, an elongated secondary mixing chamber (3) comprising several spaced secondary conduits (4) is arranged on at least one side of the supply conduit (2) , and the primary mixing chamber (6) is disposed downwards relative to the secondary conduit (4), has an elongated shape and comprises several spaced primary drainage openings (7).