US3107721A - Safety device for radiation burners - Google Patents

Description

Oct. 22, 1963 J. A. D` LHRAULT SAFETY DEVICE FOR RADIATION BURNERS Filed Feb. 17, 1959 BEI'EIEBE! EE INV ENTOR BY mm1-Q. m

ATTORNEY United States Patent O SAFETY DEVHCE FR RADEATEN BURNERS .lean Andr Denis Lhranit, Paris, France, assigner to Antargaz Societe Anonyme de Distribution de Gaz Liquides de lletroic, Paris, France, a corporation or France Filed Feb. 17, 1959, Ser. No. 793,826 Claims priority, application France Sept. 26, 1953 9 Claims. (Cl. 15S- 131) The present invention relates to a safety device for radiation burners or other similar heating appliances.

It is know-r1 that radiation burners are generally utilised for heating rooms and premises without being coupled to a sm'oke conduit enabling the gases of combustion to be evacuated to the exterior.

It is therefore necessary to provide such appliances with a safety device which puts them out of operation ias soon as the proportion of CO2 in the ambient air of the room exceeds a certain value, in order toy ensure the safety of its occupants.

Certain types of safety devices are already known which comprise a by-pass or control burner nozzle in which a arne is maintained for heating a thermo-couple, the current of which ensures the operation of )an electromagnetic valve which is turn controls the supply of fuel to the appliance.

It is known that the speed at which the flame extinguishes increases when the quantity of CO2 contained in the combustion-supporting air increases. As soon as the maximum proportion fof CO2 -in the lambient air is reached, the llame is extinglished and, since the thermo-couple is no longer heated, the electro-magnetic valve is no longe-r excited and returns to its closed position.

The present invention has Vfor its object to provide improvements for this type of safety device, enabling its sensitivity :to be considerably increased.

This object is accomplished according to the present invention by the provision of a radiation burner in which the `by-pass or control burner which heats [the thermocouple for other heat sens-itive element is disposed to the rear of the face or arne surface of the radiation plate `of the burner, which plate is provided with an orifice extending through it and opening approximately at its face so .that when a fuel mixture is being burned at its face a draft of ambient air ilows through the orifice toward the flame surface, and the control burner has a nozzle so disposed relative to the orifice that a llame issuing from the nozzle will -be located within and cooled and otherwise influenced by the draft passing through the orifice, in a manner rendering the control burner flame highly sensitive to the prese-nce of CO2 in the draft.

According to another provision of the invention, the sensitiv-ity of the control burner tlame is further increased by tapering the extremity of the control burner nozzle so as to reduce the adherence of the arne to the nozzle.

According to another provision :of the invention, the nozzle of the control burner lis so disposed relative to the orifice extending I rough the radiation plate that the llame issuing from the nozzle is disposed within the orifice and, when the plate is disposed in upright working position, is inclined upwardly toward the face of the plate and extends in the direction of the ilow of the draft passing through the oriiice.

The thermo-couple is located in a position tangential with respect to the path of the 'by-pass flame, in such manner as not to intercept said flame nor .to hinder its extinguishing.

The safety device is constructed in the form of a singleunit assembly which reduces the risk of leakage of gas, said assembly being carried by the rnixer or injector chamber forming part of the equipped radiation burner.

3, i 7,7m Patented Get. 22, 1953 The armature plate or the control lever of the regulator valve is coated with a layer of copper formed by electrodepositi'on, so as .to avoid any adhesion to the cores of the electro-magnet due to residual magnetism.

One Iiform of construction of the safety device carried out in accordance with the invention is described below, by way of example only and not in any sense by way of implied limitation, reference `being rnade to the accompanying drawings in which:

FIG. l shows the safety device mounted on a radiation burner `as seen from the rear of this latter;

FIG. 2 is a view of ythe same `device looking on theffront of the burner;

FIG. 3 is a cross-section taken along the line Ill-III of FIG. l; and

FIG. 4 is a fragmentary cross-sectional view of the bypass control nozzle showing the tap-ered extremity thereof.

lin the -o-rm of construction of the device as shown, the said device is constituted by a regulator valve 1 provided with a coupling 2 intended to receive the fuel supply pipe and an outlet coupling 3l into which -isV screwed the main injector 4 tot the mixer chamber 5 of the radiation burner I6. A swan-neck tube 7 is connected to the coupling 3 and terminates in a three-part coupling 8, the :moving member 0f which is coupled to an elbowed tube 9, the free tapered end of which forms a by-pass nozzle which is inclined upwards.

A calibrated injector 10 is screwed into the coupling S, thus enabling the iow of gas fed through the by-pass to be regulated, while the primary air of the by-prass reaches the coupling 8 through at least one hole 11 also calibrated and bored in the said coupling.

The whole assembly is mounted ion the casing 6 of the radiation burner by means of a stirrup member y12 rigidly fixed to the mixer chamber 5 which passes into the body of Ithe burner.

The regulator valve 1 is operated by a lever 213 provided writh a push-plate 14 enabling said lever to be actuated, which push-plate carries a plate 15 forming an armature designed to be retained by an electro-magret 16 carried by a srnall plate 17 xed to the lbody of the valve 1.

The coil windings of [the electro-magnet 116 are constituted by a conductor, the two extremities 20a, Zlib of which are respectively coupled to the two elements 21a and 2lb of a thermo-couple tixed on the `by-pass 9 by means of a collar 22 insuch manner as to be located in a tangential position with respect to the path of the bypass arne. This position tot the thermoscouple prevents any interception of said llame and does not hinder its extinguishing action, as will be explained below.

The by-pass nozzle 9 is housed in a tubular con-duit or sleeve member 23 passing through the gas chamber 24 of the appliance, and has its outlet at the rear or an orifice 25 formed in the radiation plate 261. A grid 27 form-ing a protective screen is mounted in iront of the plate 26 in the usual marmer.

The operation of the safety device is as follows:

When the gas (for example buta-ne gas) arrives at a certain pressure at the inlet 2 of the regulator valve 1, the disc 14 of the lever :13 is pushed down in lorder to open the regulator valve, which then reduces the pressure to a predetermined xed value.

The gas thus expanded is then conveyed on the orne hand to the main injector 4 which feeds the burner 6 and, on the other hand, to the secondary injector 10 of the safety by-pass.

As soon as the by-pass and the burner are lighted, the thermo-couple is heated by a bly-pass llame and generates a current which excites the electroamagnet 16. The latter retains the plate 15 ot the lever 13 in contact with its cores, the plate .1d having previously been pressed against Zd the cores in order to open the valve d 4and :to light the burner. In this way the valve is held in its open position by the electro-magnet.

A slight draught of air is thus produced thorough the conduit 23 and the orifice 25, caused both by the by-pass or cont-rol flame on the one hand and the radiation burner on .the other. This slight current of air passes from the rear part of the burner towards the front of the `appliance and surrounds the by-pass nozzle. rlfogether with the gaseous mixture which reaches the 'by-pass nozzle, this current assists in cooling the base of the liarne of said bypass in the centre of a burner which is considerably hotter than the by-pass.

In addition, the tapered extremity of the nozzle restricts the path and increases the velocity of the peripheral layer of the gas stream liowing through the nozzle, thereby creating in that layer beyond the nozzle orifice a velocity nearer to that of the core of the stream and rendering the co-ntrol llame less stable than would be the case were the nozzle extremity untapered. The tapered extremity of the nozzle thus assists the extinction of the llame and, for these Various reasons, the sensitivity of the device is substantially greater than that alforded by the devices already in existence.

It Will 4be appreciated that if the proportion of CO2 in the ambient air increases, this air charged with CO2 constitutes the combustion-supporting air of the llame, and since the speed of extinction increases as the proportion of CO2 increases, the llame will be extinguished as soon as this proportion exceeds a limit previously determined by suitable calibration of the by-pass injector and by appropriate diniensioning of the elements which either constitute or tix the by-pass in position.

The tapered extremity of the by-pass nozzle plays a very important part. ln the rst place, it eliminates any risk :of backfire of the flame, and in the second place, were it not for this feature, the llame would lbe extinguished at 1% of CO2 or more, Whereas it has been observed in tests carried out with a tapered nozzle, that extinction takes place at less than 0.4% of CO2 LWithout hindering the ignition. The tapered portion thus makes the device much more sensitive -to the presence of CO2.

It should also be noted that it is very important to place the by-pass in the bottom part of the appliance. ln this position, a natural draught is set up between the grid and the radiation plate and also at the same time through the orifice 25, and it is this draught which ensures the correct operation of the device.

l-f the by-pass were placed near the top of the appliance, the orilice 25 would not contr-ibuteto the above-mentioned natural draught and would be liable to 'have the contrary elfect of permitting the passage of reverse-currents of hot burnt gases which would heat the nozzle of the `oy-pass, causing the ilarne of the by-pass to backfire and thus making it more difficult to extinguish.

It is clear that as soon as the by-pass flame is blown out, the thermo-couple is no longer heated and ceases to generate a current capable of exciting the electro-magnet i6. The latter thus releases the plate l5 and the lever 13 returns to its position of rest, thus causing the valve 1 to close and cutting olf the supply of fuel both to the burner and to the -by-pass. The burner is extinguished and there is no longer any danger.

It is an advantage to coat the plate 15 with a him of non-magnetic `material Which is capable of preventing any 4untimely adhesion due to residual magnetism. The plate may be coated with a metallic layer, for example, copper, obtained by an electrolytic deposit of 3.5 microns in thickness. It may also be coated with a lilm of paint which is either applied by spreading or sprayed with a gun, or alternatively it may be coated with a non-magnetic lrn obtained by rnetallization.

ln addition, the position of the `lay-pass nozzle with respect to the plate Z6 should obviously be adjusted in a precise manner.

t is preferable to construct the device in the form `of a single-unit assembly, in order to reduce the risk of leakages.

Finally, it will be understood that the form of construction described above, by way of example only and not in any sense by Way of limitation, may be modified both as to form and detail, Without thereby departing from the spirit or from the scope of the invention.

What I claim is:

l. A safety device for a radiation burner comprising: a radiation plate having perforations therein for conducting therethrough streams of a gaseous fuel mixture to be burned at the face of said plate, said plate further having an enlarged orifice extending through it and opening approximately at its face so that when a fuel mixture is being burned at its face a draft of ambient air owsv in a position relative to said Orifice such that a llame issuing from the nozzle .will be located Within and cooled to a temperature near its extinction temperature by the draft passing through the orifice; supply means including a valve effective when open to supply said mixture both to said main injector and to the injector of said control burner means; said control burner means and said supply means being operative to maintain said ilarne in a condition such that it will continue to burn when said draft contains no deleterious quantity of CO2 but will be extinguished upon the occurrence of a deleterious amount of CO2 in said draft; and control means, including a heat sensitive ele-ment in a. position to be heated by said flame, for closing said valve when said element ceases to be heated by said llame.

2. A safety device as claimed in claim l wherein said orilice includes a sleeve member extending rearwardly from saidplate and surrounding but spaced from said nozzle to funnel said draft of ambient air over said nozzle.

3. A safety device as claimed in claim l wherein said orifice is located near the bottom of said burner plate when said plate is disposed in upright Working position.

4. A safety device as claimed in claim 1, said valve being normally closed, said control means including means movable to open said valve and means operative to hold said valve in open `position as long as said element is heated by said llame.

5. A safety device as claimed in claim l wherein said nozzle has a tapered extremity so as to reduce adherence,

of said llame thereto and thereby facilitate extinction of said llame in the presence of CO2 in the said ambient air.

6. A safety device as claimed in claim l wherein, when said radiation plate is disposed in upright working position, said nozzle forms within said orifice a flame angled upwardly toward said face of said plate and extending in the direction of the ow of said draft so as to facilitate extinction of said arne in the presence of C02lin the said ambient air.

7. A safety device for a radiation burner comprising: a radiation plate having perorations therein for conducting therethrough streams of a gaseous fuel mixture to be burned at the face of said plate, said plate further having an enlarged orifice extending through it and open.

ing approximately at its tace so that when a fuel mixture is being burned at its face a draft of .ambient air flows through the orifice toward the flame surface; a main in-` jector for supplying said vmixture to said perforations; control burner means including a nozzle and an injector for supplying -a stream of 'said mixture to said nozzle, said nozzle being disposed to the rear of the face of said plate in a position relative to said orifice such that a flame issuing from the nozzle will be located within and cooled to a temperature near its extinction temperature by the draft passing through the orifice; supply means including a valve elective when open to supply said mixture both to said main injector and to the injector of said control burner means; said control burner means and said supply means being operative to maintain said arne in a condition such that it will continue to burn when said draft contains no deleterious quantity of CO2 but will be extinguished upon the occurrence of a deleterious amount of CO2 in said draft; and control mea-ns including a thermocouple in a position to be heated by said iiame for closing said valve when said thermocouple ceases to be heated by said flame; said control means also including a valve lever having a displaced position whereat said valve is maintained in its open position, and an electromagnet responsive to current generated by said thermocouple while the thermocouple is heated by said ame to hold said lever in said displaced position.

8. A safety device as claimed in claim 7 wherein said thermocouple is located in a position tangential to the path of said flame.

9. A safety device for a gas burner comprising a burner surface having a plurality of burner outlets and further having an enlarged orifice opening at said surface and extending rearwardly therefrom so that when a fuel mixture is being burned at said burner outlets a draft of ambient air iiows through the orifice toward said surface; control burner means including a nozzle disposed to the rear of said burner surface in a position relative to said orifice such that a llame issuing from the nozzle will be located within and cooled to a temperature near its extinction temperature by the draft passing through the orilice; supply means including a valve effective when open to supply fuel both to said burner outlets and to said nozzle; said control burner means and said supply means being operative -to maintain said flame in a condition such that it will continue to burn when said draft contains no deleterious quantity of CO2 but will be extinguished upon the occurrence of a deleterious amount of CO2 in said draft; and control means, including a heat sensitive element in a position to be heated by said flame, for closing said valve when said element ceases to be heated by said ilame.

References Cited in the lfile of this patent UNITED STATES PATENTS 1,628,049 Kaufeld May 10, 1927 1,675,638 Brinkerhoi July 3, 1928 1,945,109 Fonseca Ian. 30, 1934 t 2,126,564 Leins Aug. 9, 1938 2,474,547 Patch June 28, 1949 2,817,696 Beck Dec. 4, 1957 FOREIGN PATENTS 452,304 Great Britain Aug. 20; 1936

Claims (1)

1. A SAFETY DEVICE FOR A RADIATION BURNER COMPRISING: A RADIATION PLATE HAVING PERFORATIONS THEREIN FOR CONDUCTING THERETHROUGH STREAMS OF A GASEOUS FUEL MIXTURE TO BE BURNED AT THE FACE OF SAID PLATE, SAID PLATE FURTHER HAVING AN ENLARGED ORIFICE EXTENDING THROUGH IT AND OPENING APPROXIMATELY AT ITS FACE SO THAT WHEN A FUEL MIXTURE IS BEING BURNED AT ITS FACE A DRAFT OF AMBIENT AIR FLOWS THROUGH THE ORIFICE TOWARD THE FLAME SURFACE; A MAIN INJECTOR FOR SUPPLYING SAID MIXTURE TO SAID PERFORATIONS; CONTROL BURNER MEANS INCLUDING A NOZZLE AND AN INJECTOR FOR SUPPLYING A STREAM OF SAID MIXTURE TO SAID NOZZLE, SAID NOZZLE BEING DISPOSED TO THE REAR OF THE FACE OF SAID PLATE IN A POSITION RELATIVE TO SAID ORIFICE SUCH THAT A FLAME ISSUING FROM THE NOZZLE WILL BE LOCATED WITHIN AND COOLED TO A TEMPERATURE NEAR ITS EXTINCTION TEMPERATURE BY THE DRAFT PASSING THROUGH THE ORIFICE; SUPPLY MEANS INCLUDING A VALVE EFFECTIVE WHEN OPEN TO SUPPLY SAID MIXTURE BOTH TO SAID MAIN INJECTOR AND TO THE INJECTOR OF SAID CONTROL BURNER MEANS; SAID CONTROL BURNER MEANS AND SAID SUPPLY MEANS BEING OPERATIVE TO MAINTAIN SAID FLAME IN A CONDITION SUCH THAT IT WILL CONTINUE TO BURN WHEN SAID DRAFT CONTAINS NO DELETERIOUS QUANTITY OF CO2 BUT WILL BE EXTINGUISHED UPON THE OCCURERENCE OF A DELETERIOUS AMOUNT OF CO2 IN SAID DRAFT; AND CONTROL MEANS, INCLUDING A HEAT SENSITIVE ELEMENT IN A POSITION TO BE HEATED BY SAID FLAME, FOR CLOSING SAID VALVE WHEN SAID ELEMENT CEASES TO BE HEATED BY SAID FLAME.

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