US3354931A

US3354931A - Carbon dioxide detecting safety device for apparatus operating through catalysis of gaseous hydrocarbons

Info

Publication number: US3354931A
Authority: US
Inventors: Risse Roger
Original assignee: Lyonnaise des Applications Catalytiques Ste
Current assignee: Lyonnaise des Applications Catalytiques Ste
Priority date: 1963-01-15
Filing date: 1963-12-31
Publication date: 1967-11-28
Anticipated expiration: 1984-11-28
Also published as: AT251323B; FR1375002A; LU44880A1; GB1044323A; DK104528C; FI42692B; ES294757A1; CH394457A

Description

NOV. 28, 1967 R RlSSE 3,354,93l

CARBON DIOXIDE DETECTING SAFETY DEVICE FOR APPARATUS OPERATING THROUGH CATALYSIS OF' GASEOUS HYDROCARBONS Filed DeC. 5l, 1965 2 Sheets-Sheet l NOV. 28, 1967 R R|5SE 3,354,931

CARBON DIOXIDE DETECTING SAFETY DEVICE FOR APPARATUS OPERATING THROUGH CATALYSIS OF GASEOUS HYDROCARBONS Flled Dec. 3l, 1963 2 Sheets-Sheet 2 Fiss [will United States Patent O 3,354,931 CARBON DIOXIDE DETECTING SAFETY DEVICE FOR APPARATUS OPERATING THROUGH CA- TALYSIS OF GASEOUS HYDROCARBONS Roger Risse, Lyon, France, assignor to Societe Lyonnaise des Applications Catalytiques, Caluire, France Filed Dec. 31, 1963, Ser. No. 334,788 Claims priority, application France, Jan. 15, 1963, 43,225, Patent 1,375,002 3 Claims. (Cl. 15S- 139) ABSTRACT OF THE DISCLOSURE A heating apparatus operating without llame by catalysis of gaseous hydrocarbons and equipped with a burner for detecting CO2 contained in the ambient atmosphere, the detector being constituted by -a device functioning by catalysis and supplied with gaseous hydrocarbon from the same course as that burned in the heating apparatus, the detector being adjusted to extinguish itself when the proportion of CO2 increases causing closure of a safety valve interrupting supply of the main heating apparatus.

Various safety devices exist presently, which are fitted in particular on heating apparatus using hydrocarbon fuels, such devices making it possible to cut off the input f combustible gas when the percentage of carbon dioxide rea-ches a predetermined level in the surrounding air.

The applicant holds various patents relating to devices of this type which are particularly intended for apparatus operating through catalysis.

All said devices, however, are based on the common principle of the existence of a pilot-llame which is metastable or becomes deformed depending on the percentage of carbon dioxide in the surrounding air. The existence of a pilot-flame in a device of this type obviously does not offer any inconvenience when said device is tted on a flame-emitting apparatus, in particular on a flame-emitting butane heater, but the problem is quite different when an apparatus operating through catalysis is concerned. As a matter of fact, one of the characteristics of the latter apparatus, in normal operation, is the absence of any flame, which gives them a perfect safety, more especially as the catalytic screen has a temperature not exceeding about 400 C. The addition of a pilot-ilame to an apparatus heating through catalysis eliminates an advantage of said apparatus.

The subject-matter of the present invention is a carbon dioxide detecting device which, in contradistinction to the above-mentioned devices, does not include any flame.

The device of the invention is essentially constituted by a small heating apparatus which operates through catalysis of the hydrocarbon fuel from a by-pass of the supply-pipe of the heater proper. Said small pilot-apparatus is designed in a manner such that, when it is located in an atmosphere which contains substantially no carbon dioxide, its oxygenation is just sufficient for ensuring its proper operation; the catalytic oxidation is thus complete. But, if said atmosphere contains some CO2, the oxygenation of the small pilot-apparatus is no longer sufiicient and the catalytic oxidation is no longer complete. On the one hand, unburnt gases are produced, and, on the other hand, the temperature of Said catalytic pilot-apparatus drops.

The essential feature of the present invention consists in using said drop in temperature for detecting an increase n the percentage of carbon dioxide in the surrounding air. As a matter of fact, it is only necessary to ice dispose in the immediate vicinity of the catalytic pilotapparatus the sensing component member of a thermostat controlling a gas valve arranged in the gas supply circuit and operating in a manner such that a fall in the temperature of the catalytic pilot-apparatus causes the valve in the gas supply circuit of the heater to close and thus the entire apparatus to be deactivated.

In a modication, the fall in the temperature of the catalytic pilot-apparatus may, instead of causing the gas valve to close, set the heater in the position where it operates at its minimum reduced speed.

The present invention will be clearly understood with reference to the appended diagrammatic drawings which illustrate, merely by way of example, an embodiment thereof. In said drawings:

FIG. 1 is an axial sectional view of the member;

FIG. 2 is a diagrammatic showing of a gas supply circuit;

FIG. 3 is a sectional View on enlarged scale of the starter-cock assembly in FIG. 2;

FIG. 4 is a cross-sectional view in FIG. 3;

FIG. 5 illustrates a modification of the circuit of FIG. 2;

FIGS. 6 and 7 illustrate two further embodiments of the catalytic pilot-member; and

FIG. 8 is a sectional view on enlarged scale of gauged jets in FIGS. 2 and 5.

The essential member of the apparatus of the invention consists of a catalytic element 1 disposed inside a tube 2 the length diameter ratio of which is calculated in a manner such that in an atmosphere containing zero percent CO2 the catalytic oxidation of said element 1 is just complete.

The catalytic element 1 is fed by a cylindro-conical tube 3 which receives a stream of gas through a nozzle 4.

This gas stream while passing through the cylindrical portion of said tube 3, is mixed intimately with air entering said tube through a hole 5 the diameter of which depends on the proportioning of air and gas to be obtained for allowing the pilot-apparatus to operate under the conditions defined hereinabove.

In the immediate vicinity of the catalytic pilot-element 1 is disposed a sensing component member 6 of a thermostat (see FIG. 2) contr-olling a gas valve 7. One or more openings 8, which may be closed at will and are disposed above the catalytic element 1, are intended to supply additional air at the moment the pilot-device is started. The tube 2 ends in a nozzle 9 which opens in the immediate vicinity of the catalytic screen 10 of the heater so as to catalyze the light unburnt gases which are produced in the pilot-device at the moment the percentage of CO2 begins to increase.

FIG. 2 illustrates, by way of example, a diagrammatic representation of the assembly of said pilot-device o-n a heating apparatus operating through catalysis and starting through the direct ignition of the gases over its screen 1t). In said diagram: 12 indicates a starter-cock assembly tted with four outlet pipes, the details of which are shown in FIGS. 3 and 4; 14 indicates a safety thermostat intended for cutting -oi the incoming gas when the screen 10 is cold.

The lreference letters a, b, c, d, e, f, and g indicate the gas pipes and the reference letters h indicate the various gauged jets adapted to operate the whole assembly under the required ilow-rate conditions.

The starter-cock assembly 12, of a known type, is illustrated in detail in FIGS. 3 and 4. Said assembly is connected at to the main gas pipe-line. It comprises a needlevalve 1S actuated by a handle or a hand-wheel 16, and a catalytic pilottaken along line 4 4 3 spring-loaded piston 17 with spring 18, which piston is operated by means of a pull-rod 19.

Each jet h (FIG. 8) is constituted by a T-junction 20 the

branches

21, 22 and` 23 of which are threaded at 21a, 22a and 23a to receive internally a plug 24 having a calibrated passage 25' and screw slot 26 for positioning and removing the plug 24. Each of these T -junctions is provided with a plug 24 in at least one of its

branches

21, 22 and 23. These branches are connected to the pipelines of which the flow is to be controlled.

During the priming or igniting period the quantity of gas fed to the screen 10 must be considerably greater than that necessary for normal continuous operation. For this purpose the screen 10 contains two supply openings 27 and 28 and the junctions between the lines b and f supplying the opening 28 comprise two jets positioned, respectively, in the branch connected to the line b and in the branch connected to the line f, the calibrated passage of the rst of these jets being of greater diameter than that of the second.

The operation of this assembly is as follows:

(l) Srartz'ng- A pull is exerted on the pull-rod 19 of the starter-cock assembly 12, whereby the piston 17 clears the mouths of the pipes a, b, c, and the gas entering at i reaches freely said pipes. Said gas thus feeds the ignition circuit for the screen 10. The opening 27 is supplied by the tube a and the opening 28 by the tube b, the latter supplying also, through a by-pass, the detector 13 through tubes f and g. The tube e is also supplied through the valve 7 which is open, since it is assumed, when the ignition takes place, that the percentage of CO2 is close to zero. The direction of supply is indicated by the arrows in full lines in FIG. 2. At the end of the pipe e the gas is stopped by the thermostat 14 which opens only when the screen 10 is adequately hot. Through ignition of the gases issuing through the screen 10 and at the end of the detector 13, a pre-heating both of said screen and of said detector is obtained.

(2) Normal operation.-After said pre-heating has been effected, the pull-rod 19 of the starter 12 is released, The gas stops passing through the pipes a, b, c. The operating cock 16-15 is then opened and the gas passes through the pipe d and into the thermostat 14 which has opened owing to the warming up of the screen 10. The gas proceeds in the direction of the arrows in broken lines through the pipe e, passes through the valve 7, which is open and flows both through the pipe f towards the screen 10 in order normally to feed the latter, and through the pipe g towards the detector 13 also in order to feed same.

(3) Operario/1 of the CO2 detectan-This operation of the detector 13 may be readily understood. As a matter of fact, when the percentage of CO2 in the surrounding air reaches a pre-determined level, such as, for instance, one percent, the fall in temperature brought about in the catalytic pilot-element 1 disposed inside the detector 13 causes, as explained hereinabove, the thermostatic valve 7 to close. The gas owing through the pipe e cannot flow any farther, whereby the total extinction of the heater-detector assembly is obtained.

For re-starting said assembly, it will be necessary to wait until the percentage of CO2 has fallen back to a value definitely lower than that selected, that is, one percent in the above example.

The modified embodiment illustrated in FIG. 5 shows an arrangement in which the operation of the CO2 detector does not cause the whole assembly to be completely shut off and put out, but automatically sets the heater to its minimum reduced speed, said heater starting again to operate at full speed as soon as the percentage of CO2 has decreased. To this end, the detector 13 and the valve 7 are connected to the pipe e by by-passes, while suitable jets h are disposed at said by-passes.

As regards the detector proper, a modified embodiment may consist (FIG. 6) in positioning the sensing component member 6 of the thermostat below the catalytic pilot-element 1, which allows, by extending said element, catalyzing all of the unburnt gases.

It is also possible (FIG. 7) to dispose the sensing component member 6 in a manner such that it is positioned vertically along the axis of the cylindre-conical tube 2-3 and at the center of the catalytic pilot-element 1 which is then in the shape of a stack.

Likewise, instead of starting said element through direct ignition of the gas, it is possible to use a small electric resistor disposed in contact with said element and energized by means of a portable cell or the like. Obviously, other construction diagrams may be worked out when the detector of the invention is to be fitted on an apparatus which has an electric starter instead of being ignited directly.

Lastly, as appears already from the foregoing, it is obvious that the invention is by no means limited to the embodiments thereof described hereinabove only by way of example; it covers, on the contrary, all the modifica tions thereof coming within the scope of the appended claims.

What I claim is:

1. The combination comprising a main burner; a catalytic ameless detector burner located to be oxygenated from the air ambient to the main burner; a gaseous fuel supply means; a manually controlled conduit means forming a first connection between said supply means, the main burner and the detector burner; and a thermostatically controlled by-pass conduit means forming a second connection between said supply means and said main burner and having a thermal sensing element sensing the activity of said detector burner and operative to shut off flow through said second connection when the activity is low due to an intolerably high content of inert gas in the ambient air.

2, The combination as claimed in claim 1 wherein said detector burner comprises a tube having a catalytic element arranged to be oxygenated substantially coms pletely when the ambient air is substantially free of CO2.

3. The combination as claimed in claim 2 wherein said main burner includes a catalytic screen, said tube having an end with a nozzle facing the catalytic screen of the main burner.

References Cited UNITED STATES PATENTS 1,416,361 5/1922 Lamb et al 23-254 3,028,909 4/1962 Faure 158-132 3,037,554 6/1962 Risse 158-140 FREDERICK KETTERER, Primary Examiner.

Claims

1. THE COMBINATION COMPRISING A MAIN BURNER; A CATALYTIC FLAMELESS DETECTOR BURNER LOCATED TO BE OXYGENATED FROM THE AIR AMBIENT TO THE MAIN BURNER; A GASEOUS FUEL SUPPLY MEANS; A MANUALLY CONTROLLED CONDUIT MEANS FORMING A FIRST CONNECTION BETWEEN SAID SUPPLY MEANS, THE MAIN BURNER AND THE DETECTOR BURNER; AND A THERMOSTATICALLY CONTROLLED BY-PASS CONDUIT MEANS FORMING A SECOND CONNECTION BETWEEN SAID SUPLY MEANS AND SAID MAIN BURNER AND HAVING A THERAL SENSING ELEMENT SENSING THE ACTIVITY OF SAID DETECTOR BURNER AND OPERATIVE TO SHUT OFF FLOW THROUGH SAID SECOND CONNECTION WHEN THE ACTIVITY IS LOW DUE TO AN INTOLERABLE HIGH CONTENT OF INERT GAS IN THE AMBIENT AIR.