US3394695A - Heating apparatus - Google Patents

Description

July 30, 1968 BODEN 3,394,695

HEATING APPARATUS Filed April 20, 1966 2 Sheets-Sheet l 2!? I 14 32 T "-H WT 18 5 LLER ......muurfl J1 I l 18 20 a E i Ill 1 J r; 259 1L 1 6 16b 16&

INVENTOR, RAY BODEN PATENT AGENTS July 30, 1968 BODEN 3,394,695

HEATING APPARATUS Filed April 20, 1966 2 Sheets-Sheet 2 FIG.4

INVENTOR. RAY BODEN wa d &

PATENT AGENTS United States Patent 3,394,695 HEATING APPARATUS Raymond John Bod'en, Hamilton, Ontario, Canada (163 North Shore Blvd. E., Burlington, Ontario, Canada) Filed Apr. 20, 1966, Ser. No. 543,869 13 Claims. (Cl. 126-110) ABSTRACT OF THE DISCLOSURE Spaced heating apparatus comprises an air moving device and a combined heat exchange and combustion device disposed in the air stream, the latter device comprising a plurality of stacked elements, each of which operates substantially independently of the others. Thus each element has respective mixing and combustion chambers and extracts its own combustion air from the part of the air stream incident thereon; the combustion chambers communicate freely with one another and any number of elements can therefore be stacked to give the required heating capacity; the invention also comprises each element as a novel subcombination.

The present invention is concerned with improvements in or relating to space heating apparatus, and especially to such apparatus comprising a heat exchanger device and an air moving device, such as a fan or blower, the said air moving device drawing air from the ambient space around the apparatus, passing it through or over the exchanger in heat exchange relation therewith, and returning the thus heated air to the said ambient space.

Such apparatus as commonly employed in industrial buildings usually employs a heat exchanger device of sheet steel in combination with a separate atmospheric multiple outlet burner located beneath the exchanger device. The primary and secondary air for the burner is obtained from the said ambient space, and the hot combustion gases are moved through or over the exchanger device by natural convection to an external vent, by which they are discharged from the building. A draft diverter is usually provided above the exchanger device, between it and an outlet from the apparatus, in order to shield the stream of gaseous combustion products as far as possible from external conditions, and also to mix the said products with additional air and ensure complete combustion.

It has been found that such apparatus as provided hitherto is extremely sensitive to conditions in the said ambient area, and to wind conditions exterior to the building, to the extent that in practice it is almost impossible to ensure continuous completely satisfactory operation. For example, if a negative condition exists owing to the said exterior wind conditions, or to an interior condition such as the operation of an exhaust fan, the flame is pulled down into the burner and licks around the base of the exchanger. In the presence of a positive pressure the burner becomes overfired, so that it becomes overheated. Overheating or direct contact of the flame with the walls of the exchanger device will result in rapid corrosion and subsequent perforation of the walls, so that the device must be replaced.

It is an object of the present invention to provide a new form of space heating apparatus.

In accordance with the present invention there is provided space heating apparatus comprising a heat exchanger device, an air moving device for moving an air stream in heat exchange relation with the exchanger device, means 3,394,695 Patented July 30, 1968 for extracting combustion air from the said air stream and mixing it with a gaseous fuel, and means for feeding the mixture of combustion air and gaseous fuel to an interior combustion chamber of the exchanger device for combustion therein.

A particular preferred embodiment of the invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings, wherein:

FIGURE 1 is a general sectional view in elevation of the apparatus, the section being taken on the line 11 of FIGURE 2,

FIGURE 2 is a sectional view of the apparatus from above, taken on line 22 of FIGURE 1,

FIGURE 3 is a section through the heat exchanger device on the line 33 of FIGURE 4, and

FIGURE 4 is a side elevation to a larger scale of the heat exchanger device.

In this embodiment an air blower unit 10, of conventional form, has its outlet 11 directly connected with an inlet 12 of a casing 13. Air is extracted by the blower from the ambient space, passed through the casing 13 over a combined burner and heat exchanger device 14, and is discharged through an outlet 15 back into the ambient space. The casing interior is provided with baflles 16 defining a passage that, as seen in plane in FIGURE 2, converges at 16a toward the device 14, remains of substantially constant width at 16b, and diverges at 16c until it joins the casing mouth 15. Secondary converging baflies 17 are provided at the entry to the casing, and also direct the entering air into intimate heat exchange contact with the device 14, so as to achieve as efficient a transfer of heat as possible to the air stream.

In this particular embodiment the burner exchanger device is constituted by a plurality of separate elements (9 are illustrated, but more or less could be used) stacked one upon the other, and connected together to constitute a single unit by vertically-extending tie rods 18 passing through corresponding holes 19 provided in the elements. The top and bottom of the stack are closed by respective end plates 20 and 21. A preferred method of producing the elements is by casting from a suitable material, such as iron or ceramic with appropriate transfer properties.

Referring especially to FIGURES 3 and 4, each element has formed therein an entry chamber 22, of generally conical shape, and convergent in the direction of flow of air through the casing 13 (indicated by the arrows 23). A fuel gas feed pipe 24 is common to all elements, and has a discharge orifice 25 for each chamber 22, each orifice discharging into the respective chamber near to the apex thereof. At the said apex each chamber discharges into a first bore 26 of substantially uniform diameter, that discharges in turn into a mixing chamber 27, which in this embodiment is of generally circular transverse cross-section.

At least one second bore 28 connects the interior of the chamber 27 to the interior of a combustion chamber 29, the gaseous fuel/ air mixture discharging through the bore or bores 28 into the chamber 29, in which it is ignited. As illustrated for this particular embodiment three vertically spaced bores 28 are provided, the middle bore being disposed diametrically opposite to the bore 26. In general, the number, configuration, size and location of the bores 28 are so arranged that a continuous flame pattern is provided in the exchanger, the combustible mixture is fully utilized and no substantial back pressure is created in the mixing chamber 27. Ignition is maintained in all of the chambers 29 by means of the usual pilot light provided in the lowermost element and supplied via a feed pipe 30.

In operation of the apparatus a portion of the air supplied by the blower is extracted by each convergent chamber 22 from the main air stream and fed around the respective orifice 25 to entrain the fuel gas stream issuing therefrom, this air constiuting both the primary and secondary air that would be required in the atmospheric burners employed hitherto. The convergent form of the chamber 22 ensures that the entraining air entering the bore 26 is at the required positive pressure to pass it through the device 14, and also ensures that it has sufficient forward velocity to prevent back-ignition through the bore or bores 28 into the mixing chamber 27. The gases are thoroughly mixed in the chamber 27, so that a completely combustible mixture enters the chamber 29. It is contemplated that in some embodiments of the invention additional flow passages, such as 31, may be provided to convey additional secondary combustion air directly from the space surrounding the exchanger to the chamber 29. The combusted gases move upward and are discharged via a flue 32 to the building exterior; it is contemplated that in some embodiments additional exhaust means, such as an induced draft fan, may be connected to the discharge of the flue 32 for inducing additional draft through the exchanger device.

Since all of the air required for combustion is extracted directly from the mechanically-forced blower air stream, any changes in that air stream due to changes in the ambient atmospheric conditions are superimposed on the relatively high positive pressure produced by the blower and become negligible, so that the air forced into the combined burner and exchanger device 14 is relatively stable in pressure and flow volume and produces a stable flame pattern under completely controlled conditions. The com- 2 plete enclosure of the flame also ensures that the pattern will remain stable. Moreover, the use of the stable forced draft eliminates the possibility of direct contact of the flame with the exchanger/and burner walls, and it is therefore possible to use a hotter smaller flame, so that more compact construction is achieved. Additional simplicity of construction is also achieved in that a separate burner assembly is eliminated, and a draft diverter is no longer required.

The elements of the exchanger and burner device prefcrably are provided With internal vertical ribs 33, and external horizontal ribs 34 to give a more rigid structure, and also to increase the efficiency of the heat exhange. In this embodiment also the length of the combustion chamber 29 provided by the elements increases progressively in the direction of flow of the gas stream through the device, since the combustion chambers of all the elements are effectively connected in series with one another, and the volume of gas to be passed by the combustion chambers increases in this direction. In other embodiments, however, all of the elements may be of the same shape so that the chambers 29 are of constant volume and flow capacity.

In the embodiment particularly described, a single combined burner and heat exchanger device 14 is provided, but it is also possible to use more than one device 14 within a single casing 15, and supplied with air from one or more blower or fan devices 10, so that apparatus of different heating capacities can be produced from a relatively restricted size range of devices 14. In such an arrangement each device may be provided with respective baflies 16 and 17, or a single set of such baflles may be common to two or more burner and exchanger devices.

What I claim is:

1. Space heating apparatus comprising an air moving device for producing a stream of air, and a heat exchange and combustion device disposed in heat exchange relation with the said air stream, the last mentioned device comprising means for feeding fuel thereto, a plurality of contiguous generally similar elements, such said element having the air stream incident thereon and comprising respective means for extracting combustion air from the stream and for feeding the combustion air together with said fuel to the interior of the element, a respective fuel and air mixing chamber in the interior of the element receiving the said combustion air and fuel, a respective combustion chamber in the interior of the element connected with the associated mixing and combustion chamber to receive mixed fuel and air therefrom, and passage means for connecting the combustion chambers of each immediately adjacent two elements to communicate freely with one another.

2. Apparatus as claimed in claim 1, wherein the said combustion air extracting means comprise a chamber of the respective elements which intercepts the air stream and is convergent in the direction of movement of the air toward the interior of the element.

3. Apparatus as claimed in claim 2, wherein the said fuel feeding means comprise a fuel feed passage for each element, and an outlet from said feed passage discharges into the said convergent chamber in the direction of flow of air therein, so that the fuel discharged from said outlet is entrained in the air flowing through the convergent chamber into the interior of the element.

4. Apparatus as claimed in claim 2, wherein the said convergent chamber discharges at its apex via a first bore into the said mixing chamber, and the said mixing chamber discharges via feed passage means comprising at least one second bore into the said combustion chamber, the said at least one second bore being of greater flow capacity than the said first bore.

5. Apparatus as claimed in claim 4, wherein the said convergent chamber, the said first bore, the said mixing chamber and the said at least one second bore comprise a linear flow path for the air and fuel and the air fuel mixture flowing within the element.

6. Apparatus as claimed in claim 1, wherein each element comprises additional passage means connecting the exterior of the element and the interior of the combustion chamber to feed secondary combustion air directly from the air stream to the combustion chamber.

7. Apparatus as claimed in claim 1, and comprising passage means for connecting the mixing chambers of each immediately adjacent two elements to communicate freely with one another.

8. A heat exchanger and combustion device element operable in contiguous relation to another generally similar element to constitute a heat exchanger and combustion device that is operative in combination with an air moving device producing a stream of air to constitute space heating apparatus, each said element comprising a unitary body having respective means for extracting combustion air from the said air stream incident on the element and for feeding the said combustion air together with fuel to the interior of the element, a respective fuel and air mixing chamber in the interior of the element receiving the said combustion air and fuel, a respective combustion chamber in the interior of the element connected with the associated mixing and combustion chamber to receive mixed fuel and air therefrom, and passage means for connecting the combustion chambers of two immediately adjacent elements to communicate freely with one another.

9. A device element as claimed in claim 8, wherein the said combustion air extracting means comprise a chamber of the respective element which intercepts the air stream and is convergent in the direction of movement of the air toward the interior of the element.

10. A device element as claimed in claim 9, wherein the said convergent chamber discharges at its apex via a first bore into the said mixing chamber, and the said mixing chamber discharges via feed passage means comprising at least one second bore into the said combustion chamber, the said at least one second bore being of greater flow capacity than the said first bore.

11. A device element as claimed in claim '10, wherein the said convergent chamber, the said first bore, the said mixing chamber and the said at least one second bore comprise a linear flow path for the air and fuel and the air fuel mixture flowing within the element.

12. A device element as claimed in claim 8, wherein each element comprises additional passage means connecting the exterior of the element and the interior of the combustion chamber to feed secondary combustion air directly from the air stream to the combustion chamber.

13. A device element as claimed in claim 8, and comprising passage means for connecting the mixing chambers of each immediately adjacent two elements to communicate freely with one another.

References Cited UNITED STATES PATENTS 1,519,673 12/1924 Do'ble 126-110 X 2,062,605 12/1936 Peters 1261 10 X 2,132,294 10/ 1938 Hatvelt 126-1 10 2,196,829 4/1940 Hess 263-19 2,286,853 6/1942 Holthouse 126110 X 3,301,308 1/1967 Briggs 26319 X JAMES W. WESTHAVER, Primary Examiner.

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