US3610791A

US3610791A - Heating apparatus

Info

Publication number: US3610791A
Application number: US860274A
Authority: US
Inventors: Luigi Cirie Iacaccia
Original assignee: Sogena SpA
Current assignee: Sogena SpA
Priority date: 1968-11-26
Filing date: 1969-09-23
Publication date: 1971-10-05
Anticipated expiration: 1988-10-05
Also published as: DE1959416A1; SE366818B; GB1256580A; FR2024222A1

Abstract

A heating device using catalytic oxidation of a gaseous or gasified fuel, wherein the catalytic element is in the form of a candle comprising an external tubular member traversed by holes, an internal diffuser tube also traversed by holes, and in the annular space between said external and internal tubes a filling of catalytically active mass; at one end of this catalytic element a support and connection base is provided, for allowing application of the element in all cases wherein previously a long flame was used.

Description

United States Patent References Cited UNITED STATES PATENTS 3,485,230 12/1969 Harrington et al.,.

Primary ExaminerEdward G. Favors Attorney-Young & Thompson ABSTRACT: A heating device using catalytic oxidation of a gaseous or gasified fuel, wherein the catalytic element is in the form of a candle comprising an external tubular member traversed by holes, an internal diffuser tube also traversed by holes, and in the annular space between said external and internal tubes at filling of catalytically active mass; at one end of this catalytic element a support and connection base is provided, for allowing application of the element in all cases wherein previously a long flame was used.

HEATING APPARATUS The present invention relates to a heating device using gaseous or gasified fuel, and operating with catalytic oxidation of the fuel.

Known heating devices of the catalytic oxidation type are in the form of panels, flat or of limited curvature, of relatively large area, and radiate the heat produced substantially within the limit of a semispace. These are only usable in practice for the direct heating of rooms, working positions and the like, while numerous special applications have hitherto not been feasible with these catalytic devices.

There are also heating applications in which heating devices with flames are used despite the presence of a flame representing an inconvenience or a danger. Particular reference may be made to absorption refrigerators, bath heaters, water heaters and the like, which are used either in houses, caravans, boats or other special units, where the presence of a flame has particular disadvantages, either through the ease with which a draught of air can extinguish it, or through the danger of fire or explosion when the flame is in an atmosphere containing mixtures of combustible gases. For this reason this type of application e.g. on board vessels with gas engines, is forbidden for devices having a flame.

The object of the present invention is to open up these fields of special application to heating devices using the catalytic oxidation of gaseous or gasified fuels, which because of the absence of flames cannot be affected by air currents even if sudden and strong, norjs there any way of producing fires or explosions even in the presence of highly inflammable mixtures in the atmosphere. 4

The basic concept of the invention is that of providing a catalytic oxidation element having substantially a candle shape, thus having one of its three dimensions many times greater than the other two, and provided at one end with support and connection means, so that radiation of the heat produced takes place more or less uniformly all round the element, which in this aspect imitates the behavior of a long flame, which can very effectively be replaced by the element in question. Thus the element may in particular be installed in the heating compartment of an absorption refrigerator, or, possibly with several of the elements, in the compartment of a storage water heater, or in other applications having similar needs, and be supplied with petroleum gas, natural gas, town s gas, gaseous fuel in general, or with the vapors of vaporized or gasified liquid or solid fuels.

The invention also provides for the feeding of the element by means of a diffuser tube and a smaller induction tube inside the first tube, provided with perforated walls and feeding the gap created between the two walls, whereby a greater uniformity of distribution is achieved.

The invention also provides the use as an igniter resistance of the outer tube containing the catalytic body connected to the body at one end and connected to a suitable rheophore at the opposite end; this tube acting as an electrical resistance preferably consists of a stretched metal netting.

Finally the invention provides an automatic feed device of considerable efficiency and particularly simple and economical construction, wherein the same flexible member which carries the mobile electrical starter contact also acts as a spring for opening the feed valve.

The invention will be better explained below with relation to an embodiment, by way of example and not limitative, shown diagrammatically in the attached drawings, wherein:

FIG. 1 is a plan of the location of a heating element as provided by the invention in the thermodynamic circuit of an absorption refrigerator;

FIG. 2 shows a candle element as provided by the invention, in longitudinal section, with some accessories;

FIG. 3 shows a further accessory;

FIG. 4 shows an improved form of candle element, in section.

The candle heating element in accordance with the invention has a support base and connection 1 provided with any suitable connection means provided for the apparatus, and into which enters a gas tube 3 terminating inside the base 1 in a calibrated nozzle 2.

From this base 1 there extends a diffuser tube 4 of small diameter relative to its length, and having over the entire active portion of its length supply holes uniformly distributed in all directions. This diffuser tube is in communication at one end with the internal gas-fed space of the base 1, and is closed at its opposite end 5. Around the diffuser tube 4 there is mounted on the base 1 a larger diameter tube comprising metal netting, expanded metal, perforated sheet or like material, and in the gap between the

tubes

4 and 6 is disposed a mass 16 of catalytic material of annular cross section, comprising for instance asbestos fiber coated on the surface or im' pregnated with an active catalyst.

On bringing the element to the starting temperature of the catalytic reaction and feeding gas from the tube 3, the devices are madeto function in manner known per se, and the heat generated is radiated substantially uniformly all round the element from the surface of the outer tube 6. Depending on the particular application, the cross section of this candle may be circular, polygonal or stellate, elliptical or flattened, in general chosen to provide maximum utilization of the heat generated and suitable connection to the atmosphere whence the element must extract oxygen for its operation.

Because of its particular shape, the element of the invention may readily be utilized where a flame burner is normally pro vided. The example of FIG. 1 shows how the element can be inserted in the heating chamber 7 connected to the thermodynamic circuit of an absorption refrigerator, comprising a heated tube 8, a condenser 9 and a mixer 10, together with other parts not mentioned or shown which complete the circuit. Such an application, apparently inconceivable for a catalytic oxidation thermal element, is in fact one of the most advantageous for the element in question'. In fact, a refrigerator thus equipped has no problems of extinction and stability of the flame, and may be used in a current of air, in the open or in movement, or even in an atmosphere saturated with inflammable vapors, without any inconvenience. In this as in other applications, the draught in the chamber wherein the element is installed may be aided, especially as far as ignition of the element is concerned, by a small funnel cap 1 l disposed at the lower end and carried either by the device or by the base 1 of the element.

Since a catalytic oxidation element produces no visible or audible flame, and thus it is difficult to establish whether it is functioning or at rest, the chamber may preferably contain a function detector comprising a bimetal plate 12 integral with the inner wall of chamber 7 and provided with a relatively long arm 13 which can end in a pointer 14. The deformation (generally flexional or torsional) of the plate 12 causes a change in the position of pointer 14 which indicates visibly the state of functioning or rest of the device.

The catalytic element may be ignited electrically or by a flame. Where electrical ignition is provided, an electrical resistance 15 is inserted in the catalytic mass 16, disposed helically, in straight lines or otherwise, and this resistance can be supplied temporarily from a soiirce R through leads l7, 18, in one of which is provided a switch, K. If required, the resistancemay instead comprise one of the two

tubular members

4, 6, made of electrically resistant material and of suitable cross section. Ignition may be eflected in known manner by manual control, or by the control of a thermometric starter, or with the aid of a time-switch l9 controlling the switch K or a stop valve 20 in the gas tube 3, so as to keep either the switch or the valve closed for a specific period during ignition; sufficient for the resistance 15 to take the element to the catalytic reaction starting temperature. After this the time-switch 19 opens either the switch K, putting the electric ignition circuit out of action, or the valve 20, feeding gas to the element which thus starts its normal operation.

Regulation, controlled in a refrigerator by a telethermometric bulb 21 connected by a flexible conduit 22 to a control device 23 including a stop valve 24 inserted in the gas tube 3, I

and on other applications by equivalent devices, may be effected gradually instead of all or nothing as is usually the case with flame burners. in this case the valve 24 is operated in parallel with a conduit 25 containing a diaphragm 26 adapted to pass a limited gas feed sufficient to maintain the element operating at minimum power, while opening valve 24 permits passage at a rate corresponding to the normal or maximum power of the element, and thus the necessity for restarting at each cycle of automatic control of functioning isavoided.

A device for automatically timed ignition equivalent to that described can be applied in the case of nonelectrical ignition by an auxiliary gas flame with hydrogen or the like, or by means of a flame applied manually or automatically to the outer surface of the element, by merely substituting for the switch K a valve in the auxiliary gas ignition circuit, opened when contact K is closed and vice versa.

In place of a timed igniter, a thermometrically controlled igniter may be used, such as that shown diagrammatically in FIG. 3, particularly adapted for the case of ignition by a flame applied to the element surface. In this case there is incorporated in the element base 1 (which during operation has a temperature close to that of the actual element) a bimetal plate 27 adapted to pass suddenly at a temperature exceeding that whereat catalytic reaction is initiated, from the rest position (cold), shown in full lines, to the active position (hot) shown in dotted lines. To this plate is connected the stem of a valve 28, which thus leaves open when cold and closes when hot a passage 29 which permits a high rate of gas flow, needed for starting the flame. When hot, the flow is limited by a smaller permanently open nozzle 30, formed in a fixed part or passing through the valve 28, commensurate with the flow required for normal functioning of the element.

In the improved form shown in FIG. '4, the candle element also has an inner diffuser tube 4 and an outer tubular member 6, both penetrated by a plurality of holes or windows for the passage of gas and made of perforated metal sheet, metal netting, expanded metal or the like, between which is disposed the catalytic mass l6, for instance in the form of asbestos coated with catalytically active material. The

tubular members

4, 6 are connected at one end to a hollow base 1, while at the opposite end they are connected by a metal dish 31 riveted or welded to the outer tubular member 6. Inside the diffuser tube 4 is disposed a gas induction tube 34 closed at the end corresponding to the dish 31, and at the opposite end communicating with the internal space of the hollow base 1, whereat the gas arrives through a connection 33 to which is connected a feed conduit, not illustrated. The wall of the induction tube 34 is pierced by a number of holes 32 through which the gas which passes from the internal space in base 1 to the induction tube 34 enters the space 35 between the said induction tube 34 and the diffuser tube 4 and thence reaches the catalytic mass 16 through the holes in the diffusor tube. The presence of the gap 35 ensures considerable uniformity in the feed of gas to the catalytic mass, and consequently more regular and efficient operation.

The induction tube 34 is made of copper or other high conductive material and is riveted or welded to the dish 31, while it is mechanically connected to the base 1 with the interposition of an insulating bush 36, and at its end carries a bent leaf spring 37 carrying a movable contact 38 adapted to cooperate with a fixed contact 39 insulated from the base 1 and connected to a clamp 40 for connection to an electrical supply source (preferably low tension, such as the battery of a car, motorboat or the like) whose other pole is connected to the mass (to earth) and hence to the base 1 of the device.

When the

contacts

38, 39 touch, the circuit 40-39-38-37- 34-31-6-1 is closed: in this the element of greatest resistivity is the tubular outer member 6 which in this case acts as a preheating resistance for igniting the device. An expanded metal structure of nickel-chrome is found particularly suitable in this case for the tubular member 6. The extreme simplicity achieved by this method of inserting a suitable resistance in the catalytic mass 16 is clear. Dimensioning the tubular member 6' to provide suitable thermal power for igniting the device is quite easy, particularly in the case of feeding at low tension, from a vehicle battery for instance.

In the case where the induction tube 34 is not adapted to act as a rheophore, or if one does not wish to use it for this purpose, a rheophore of metallic wire or cord may be made to pass inside the tube to connect the dish 31 to the flexible spring 37.

The

contacts

38, 39 must be connected for a certain time to start up the device, and then separated when the catalyzer has reached a temperature suitable for catalysis. For this purpose there is disposed in base 1 a bimetal blade 27 which controls a valve 28 adapted to control admission of gas in the axial bore 29 in the connector 33, and which is under the action of leaf spring 37 which tends to force it back by means of an insulat ing cap 41 to open either the

electrical contact

38, 39 or the gas admission valve 28. The bimetal plate 27 is so designed that it tends instead when cold to close the said contact and valve, with a force exceeding that of the leaf spring 37. Thus when cold the configuration shown in the drawing is provided. When hot, however, the bimetal plate reverses its curvature, allowing the spring 37 to open the contact and valve, which, therefore, happens when the base 1 and hence the electrical device which supplies its heat, and with it the catalyzer, are taken to a temperature suitable for starting functioning. The electrical heating stops when this opening takes place, and the gas reaches the interior chamber of base 1 and by way of induction tube 34 and gap 35 reaches the catalytic mass 16 and is oxidized therein, starting normal operation. From that time the bimetal plate 27 is maintained in the opening position by the heat supplied thereto by the action of the catalytic element. In the case of accidental extinction and hence cooling, the bimetal plate 27 reverses its own curvature, closing off the admission of gas and reconnecting the electrical starting circuit.

The use of the leaf spring 37 itself as a means of opposition to the bimetal plate 27 has the considerable constructional advantage of permitting assembly of the bimetal plate, as seen in the drawing, by merely inserting it in base 1, since it is not required to exert reverse forces: this greatly simplifies assembly.

It is understood that the description and drawings are by way of example, but that the invention may be applied in varied forms, or in combination with any accessory or supplementary part which is not illustrated because it is unnecessary for understanding the invention, while remaining within the scope of the invention and of the present patent, provided the characteristic features thereof are maintained.

I claim:

1. A catalytic heating element of candle shape including an internal diffuser tube, a catalytically active mass surrounding said diffuser tube, an external tubular member traversed by holes, enclosing said active mass, at a first end a support base connected to said tubular member, a terminal dish connected to the second end of said tubular member and an electrical rheophore connected to said terminal dish, whereby an electrical source can be connected to said base and said rheophore thus letting said external tubular member serve as an electrical preheating resistance.

2. A device as set forth in claim 1, wherein said rheophore is an internal induction tube made of high conductivity metal, electrically connected to said terminal dish and mechanically connected with electrical insulation to said base.

3. A device as set forth in claim 1, comprising an ignition control device housed in said base, including a leaf spring connected to said rheophore, a mobile contact carried by the leaf spring, a fixed contact carried with electrical insulation by said base and cooperating with said mobile contact, a connecting clamp connected to said fixed contact, a bimetal plate carried by said base, a gas admission valve connected to and operated by said bimetal plate, and an insulation block between said bimetal plate and leaf spring, whereby said bimetal plate actuates, according to the temperature of said base, both said gas admission valve and said mobile contact thus inserting the gas supply and excluding the electrical preheating or vice-versa.

4. A device as set forth in claim 3, wherein said bimetal plate is simply inserted in a corresponding seat of the base and is held in place by the force exerted by said leaf spring.

5. A device as set forth in claim 1, wherein said external tubular member is of expanded nickelchrome metal mesh.

6. A device as set forth in claim 1, further comprising an air guide of inverted funnel form carried adjacent said base.

7. A device as set forth in claim 1 further comprising an indicator device including a bimetal strip provided for being UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,610,791 Dated October 5: 97

Luigi Iacaccia Inventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

On the cover sheet, [72] should read Luigi Iacaccia Cirie, Turin, Italy Signed and sealed this 31st day of October 1972 (SEAL) Atteat:

EDWARD M.FLETCHER,JR. Attesting Officer ROBERT GO'I'ISCHALK Commissioner of Patents OHM PC4050 no'sg) USCOMM-DC 60H7B-P60 U.5. GOVERNMENT PRINTING OFFICE IIIQ O JlO-Sfll.

Claims

5. A device as set forth in claim 1, wherein said external tubular member is of expanded nickel-chrome metal mesh.

7. A device as set forth in claim 1 further comprising an indicator device including a bimetal strip provided for being heated by said catalytic element, and indicator means connected to said bimetal strip for being displaced according to the cold or warm condition of the device.

8. A device as set forth in claim 1, further comprising a starting device including valves and switches and a timing device controlling said valves and switches.

9. A device as set forth in claim 1, further comprising a regulation device including a gas stop valve, a thermometric device controlling said valve, and a permanently open limited passage dimensioned for operation at minimum power, provided in parallel with said stop valve.