US3548764A - Heat conserving,retaining and radiating assemblies for space heaters - Google Patents

Description

United States Patent 1 1 3,548,764

[72] inventors John F. NavarroJIl 3,135,505 6/1964 Agnew 263/5] 13 River St., New Rochelle, N.Y. 10801; Prima ry Examiner-Edward G. Favors Blackmck Attorneys-A. Yates Dowell and A. Yates Dowell, Jr. 211 App]. NO. 807,757 Flled 1969 ABSTRACT: Heat conserving, retaining and radiating assemi Patented 1 1970 blies for installation in or immediately above the combustion 1113/11 cousaizvmo, RETAINING AND momma ASSEMBLIES roa SPACE HEATERS 7 Claims, 10 Drawing Figs.

2,432,779 12/1947 MacDonald chamber of a space heater, each such assembly being constituted by a plurality of unifonnly spaced tubular silica rodlike elements, disposed transversly of said combustion chamber and on a horizontal plane, with refractory spacers beneath said tubular elements for preventing displacement thereof and a first layer of refractory heat-retaining blocks supported above said tubular elements in interlocking relationship therewith and having vertically disposed passages to permit free circulation therethrough of heated air. Refractory heat-retaining spacing blocks supported upon said first layer of refractory material in opposed rows and a plurality of elongated heat-retaining bars disposed thereabove in spaced relationship and parallel to the tubular silica carbide elements, said elongated bars being produced from refractory material and each having at least one stainless steel reinforcing rod extending longitudinally therethrough.

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PATENTEBnEc22|9m 3548764 sum 1 or 2 l3 INVENTORS 2 JOHN F.NAVARROIII RICHARD 'r. DiDONAT'O ATTORNEYS v Pix ENTEflnaczz I970 3548764 sum 2 0F 2 INVENTORS JOHN F. NAVARRO m RICHARD T. DiD

ATTORNEYS HEAT CONSERVING, RETAINING AND RADIATING ASSEMBLIES FOR SPACE HEATERS This invention relates to heating apparatus and more particularly to improvements specifically designed for use in furnaces, whether domestic or commercial, of the gas or oil buming types.

In furnaces of the class with which we here are concerned, it has long been known and widely recognized that tremendous losses in efficiency occur through such factors as heat loss by reason of escaping flue gases and heat absorption in the combustion chamber and heat exchanger. Of equal importance insofar as a relatively low level of thermal efficiency is concerned, and this is particularly true in apparatus or furnaces which are thermostatically controlled, the burner is initiated responsive to the thermostat and will continue to operate until the desired or preset temperature conditions are met, at which time the burner becomes inactive and remains in this condition until the furnace and system cool to the point where another requirement for heat becomes necessary.

At this time the entire furnace structure must again be heated before any heat can be delivered to the area supplied by the heating plant. Under wintry weather conditions, the burner is required to operate at frequent intervals thereby increasing wear and tear on the unit and with attendant heat losses in direct relationship to the frequency of the repeated activation of the burner unit.

It is a particular purpose of the present invention to provide novel and highly efficient furnace structure whereby loss of heat in the combustion chamber and furnace, during coolingoff intervals, will be minimized, thereby extending the cycle to reduce sharply the frequency of burner operation and at the same time maintaining the temperature of the combustion chamber and furnace at a substantially high level whereby the heating time and fuel required to raise these furnaces to operative level at the outset of each heating cycle are reduced with a corresponding increase in furnace efficiency.

Further objects and advantages of the present invention will be readily apparent from the following description, taken in conjunction with the accompanying drawings, wherein:

FIG. I is a perspective view of the combustion chamber of a furnace illustrating a novel heat retaining or conserving unit or assembly constructed in accordance with the present invention mounted thereupon so as to extend upwardly into the heat exchanger; I

FIG. 2 is a vertical sectional view of the assembly illustrated in FIG. I;

FIG. 3 is a horizontal sectional view taken on the line 3-3 of FIG. 2;

FIG. 4 is a perspective view of a refractory heat-retaining block forming a part of the present invention;

FIG. 5 is a perspective view similar to FIG. 4 and illustrating a modified form of refractory heat-retaining block;

FIG. 6 is a perspective view also similar to FIGS. 4 and 5 and illustrating a still further modified form of refractory heatretaining block;

FIG. 7 is a perspective view of a modified form of longitudinal spacer bar which rests upon each sidewall of the combustion chamber and mounts the transverse tubular elements upon which the remaining structure of the present invention is supported;

- FIG. 8 is a fragmentary perspective view on a reduced scale of a portion of a furnace combustion chamber and illustrating a modified form of the invention, disclosing the use of auxiliary spacers for mounting the transverse tubular elements where greater height above the combustion chamber is desired;

'FIG. 9 is a perspective view of one of the auxiliary spacers of FIG. 8; and

FIG. 10 is a fragmentary perspective .view similar to FIG. 9, and also on a reduced scale, of a portion of a furnace combustion chamber and illustrating a still further modified form of the invention.

As shown in the drawings, the combustion chamber of a conventional furnace or other heating plant has been illustrated conventionally as including a vertical front wall It) having a fuel inlet opening for the reception of a nozzle or the like 11 which is connected to a suitable source of fuel (not shown) such as gas, oil, etc. The combustion chamber includes sidewalls 12 and 13 and a rear wall 14 and, desirably, the longitudinal sidewalls l2 and 13 are disposed in spaced, parallel relationship and the heat retaining assembly of the present invention preferably is supported upon the upper surfaces of the opposed sidewalls l2 and 13.

While the front wall 10 of the combustion chamber, as well as the remaining walls thereof, has been shown as constructed from fire brick, it will be understood that metallic furnace panel structure may be employed with equal facility. The flame F is received within the combustion chamber and, particularly where oil is employed as the fuel, the rear wall of the combustion chamber may be provided with the usual protective target block (not shown) as is well known in this art As illustrated in the drawings, particular reference being bad to FIGS. 1, 2 and 3 thereof, a longitudinally disposed spacer in the form of an elongated bar 15 is positioned upon the upper surface of each sidewall of the-combustion chamber and the top surface of each of the bars 15 is provided with a plurality of uniformly spaced depressions 16 of arcuate or comparable configuration for the reception and retention against displacement of the extremities of a plurality of uniformly spaced tubular rodlike elements 17 which span the combustion chamber and support novel heat-retaining and conserving elements which will be described in detail hereafter.

The spacing bars 15 are produced from suitable refractory material and each of these bars preferably is provided with a plurality of spaced transverse bores or passages 150 which will permit of rapid and uniform heating of the spacing bars and the passage therethrough of heated air produced in the combustion chamber.

The rods 17 are produced from silica carbide and will absorb heat rapidly under operative conditions and by reason of the nature of the material thereof will cool slowly when the direct application of heat is discontinued. It should be understood that the material from which these rods are produced is critical and that the spacing between the longitudinal axes of adjacent rods also is critical and is complementary to the width of each block of a layer of heat-retaining blocks 18, produced from refractory material, which is supported upon the rods 17.

One form of heat-retaining block 18 is illustrated in FIG. 4 and is of substantially equal dimensions insofar as length and width are concerned. The bottom longitudinal edges of each block 18 are grooved as indicated at 180 so that each block will be supported between adjacent rods 17. Further, each block 18 is provided with a centrally located vertical bore or passage 18b and each side edge of the block may be provided with a vertical and centrally located semicircular groove 18c to permit the ready circulation of heated air through the central bore or passage 18b and the passages created by the complementary grooves in adjacent blocks 18.

As shown more clearly in FIG. 3 of the drawings, the locks 18 are disposed in rows between adjacent rods 17 and provide a substantially continuous layer or level of refractory heatretaining elements over the entire central surface of the cornbustion chamber, the path or circulation of heated air through the layer of blocks 18 being illustrated by the arrows to be found in FIG. 2.

The production of the layer of heat-retaining blocks in the manner described hereabove is highly advantageous in that these blocks will heat more rapidly than would a lesser number of comparable elements of greater size. Further, in the event of damage to any individual block 18, replacement thereof is extremely simple and the repair can be effected with particular economy.

In the modified form of heat-retaining block 19 illustrated in FIG. 5 of the drawings, each block is provided with a longitudinal flange 19d along one upper edge thereof and the opposed longitudinal edge of the block is provided with a complementary shoulder 19e for the reception of the flange IQd of the adjacent block 19 when the blocks are in assembled relationship.

In the further modified form of heat-retaining block 20 illustrated in FIG. 6 of the drawings, each block is provided with a rib or tongue 20d adjacent the upper extremity of one longitudinal face thereof and the opposed longitudinal face is pro vided with a complementarily located groove 20e. With this structure, a tongue and groove association is provided to retain adjacent blocks 20 in assembled relationship.

The assembled blocks 18 thus provide a first layer or level of heat-retaining and conserving refractory material above the combustion chamber and in relatively close relation thereto. and, desirably, a second level of such material is provided thereabove. As shown in the drawings, particular reference being had to FIGS. 1 through 3 thereof, spacers 21 are supported on each outside row of blocks 18. These spacers may be in the form of an elongated bar of rectangular cross section or, as illustrated, may be constituted by a plurality of bricklike blocks 21 produced from refractory material and having transverse bores or passages 21a for the ready passage therethrough of heated air.

Heat-retaining bars 22, disposed transversely of the combustion chamber and parallel to the tubular silica carbide rods 17, are supported upon the opposed rows of blocks 21 and complete the heat-retaining assembly being described. These bars preferably are produced through a molding operation and each bar 22 includes and is reinforced by a pair of stainless steel rods 23 which extend the full length of the heat-retaining bar.

In operation, when heat is introduced into the combustion chamber and the walls thereof reach an elevated temperature, with initiation of hot air circulation, there will be simultaneous heating of the silica carbide tubular rods 17 which span the combustion chamber and support the transverse lower level of heat-retaining blocks 18, the longitudinally disposed opposed rows of spacing blocks 21 which rest upon the outermost blocks 18 and the transverse heat-retaining bars 22 which provide the upper level of heat-retaining structure.

The tubular silica carbiderods 17 can withstand high temperatures and absorb heat with great rapidity. Thus, there-is a minimum of time delay in the heating, through conduction and hot air circulation, of the spacing blocks 21 and upper level of heat-retaining bars 22.

It has been found that the stainless steel bars 23 in each bar 22 immediately absorb heat from the surrounding refractory material from which these bars are molded and, when the source of heat or flame becomes inactive, retain such absorbed heat over substantial periods of time and effectively prevent any rapid cooling of the bars 22 between heating cycles.

Extensive tests have been conducted in connection with domestic and commercial heating plants which have been operated under identical conditions with and without the heatconserving structure of the present invention. In such tests there was sealing of excessive leakage of secondary air to insure substantially identical conditions with and without the heabconserving structure.

The criteria for the amount of excess air was fixed by stack emission only to comply with municipal air purity standards in the localities where such tests were conducted. Such tests demonstrated that fuel oil would burn with less excess air with the present invention and with a clear stack, thus establishing improved efficiency without question. Use of the heat-conserving structure did not restrict the boiler output and the burner turned on at full capacity with each call for heat.

It is known that gas will burn clean even if not properly adjusted as to excess air, carbon monoxide emission, etc. Thus, with the higher cost of gas, as distinguished from oil as a fuel, the necessity for increased efficiency becomes paramount. Reduction in stack temperatures and increase in carbon dioxide concentration in the flue gas were found both with gas and oil used as fuels.

Tests were conducted in a commercial installation which used fuel oil and during a four-month interval had required 25,365 gallons of oil at a cost of $0.0762 per gallon.

Without any change in the installation, a flow meter was installed in the oil supply line of the heating plant to determine the gallonage used in a twenty-four hour interval, both with and without the heat-conserving structure of the present invention. During these tests, the burner was made to operate on a pressure cutoff point of 5 pounds.

Without the present invention, the heating plant consumed 78 gallons of oil in a twenty-four hour interval. The present invention was then installed and during the following twentyfour hour interval, with identical operating conditions and no material change in weather, the heating plant consumed only 55 gallons of fuel. This demonstrated a saving of 23 gallons or approximately 30 percent in fuel.

Further, during such tests it was discovered that there was less wear and tear on the burner, which did not have to run as often when the installation included the present invention.

There was less wear and tear on the motors used in the operation of the heating plant. a

Most of the gases given ofi from the fuel oil being burned in the heating plant were retained and consumed within the plant and were not permitted to escape. This resulted in a drop in stack temperature of approximately F., with the virtual elimination of air pollution.

A modified form of the invention has been illustrated in FIGS. 8 and 9 of the drawings and is intended for use under conditions where it is desirable to have the lower level of heatretaining blocks elevated, to a degree, above the top of the combustion chamber. As shown, the combustion chamber is identical to that illustrated in FIGS. 1 through 3 and an elongated bar 15 is positioned upon the upper surface of each sidewall. Spacers 24, produced from refractory material, are positioned upon the bars 15 and the upper surface of each spacer includes an arcuate depression 240 within which an extremity of a tubular silica carbide rod is received. The blocks 18 and other elements are identical to the structure described here above and no further discussion thereof is believed necessary.

In the further modified form of the invention illustrated fragmentarily in FIG. Ill of the drawings, the spacing bars 15 have been omitted and individual refractory supporting blocks are uti zed, an opposed pair of such blocks, which are similar to the blocks 24, being required for each tubular silica carbide rod 17. The upper surface of each block 25 is provided with an arcuate groove to receive and retain an extremity of a rod 17 against inadvertent displacement and each block 25 may be provided with transverse bores 25b to permit of more rapid absorption of heat as well as passage of heated air therethrough.

The remaining components of this modified form of the invention are identical to those discussed hereabove and no additional discussion thereof is believed necessary.

A modified form of elongated upper heat-retaining bar has been illustrated in FIG. 7 of the drawings. As shown, each elongated bar 26 preferably is molded from refractory material and includes a spaced pair of stainless steel reinforcing rods 23 extending longitudinally therethrough. Additionally, each longitudinal face of each bar 26 is provided with a plurality of vertically disposed and uniformly spaced semicircular grooves to permit free passage of heated air between adjacent elongated bars 26 when assembled in abutting or particularly close relationship.

It will be obvious to those skilled in this art that various changes may be made in the invention without departing from the spirit and scope thereof. Thus, the invention is not considered limited by that which is shown in the drawings and described in the specification and reference therefore is had to the claims for summaries of the essentials of the invention, and of the novel features of construction and novel combinations of parts, for all of which protection is desired.

We claim:

1. In a furnace provided with a combustion chamber having a burner located in the lower portion thereof, a heat-absorbing and radiating assembly extending transversely of said combustion chamber and positioned above said burner, said assembly comprising a plurality of uniformly spaced tubular silica carbide rodlike elements mounted transversely of said chamber; refractory spacing bar means for securely retaining said tubular rodlike elements against displacement; a horizontally disposed first layer of refractory heat-retaining blocks supported upon said tubular rodlike elements, the lower surfaces of said heat-retaining blocks having a configuration complementary to that of said tubular rodlike elements whereby said blocks are securely maintained in position, said blocks also being provided with a plurality of vertically disposed bores to permit free passage of heated air therethrough; refractory spacing blocks supported upon said level of heat-retaining blocks adjacent the side edges of said level, said refractory spacing blocks being provided with a plurality of horizontally disposed bores to permit free passage of heated air therethrough; and a plurality of elongated spaced heat-retaining bars supported upon said refractory spacing blocks, each of said elongated heat-retaining bars including at least one stainless steel reinforcing rod extending longitudinally therethrough.

2. A furnace and heat-retaining and radiating assembly as set forth in claim 1 where each of the refractory heat-retaining blocks of said first layer is of a width complementary to the axial spacing of said tubular rodlike elements, the bottom longitudinal edges of each block being grooved to provide a snug fit with the adjacent tubular rodlike element, each block being provided with a centrally located vertical bore to permit free passage of heated air therethrough, and each side edge of the block is provided with a centrally located and vertically disposed semicircular groove which complements a similar groove in the next adjacent block to permit free passage of heated air between abutting blocks.

3. A furnace and heat-retaining and radiating assembly as set forth in claim 2 where each of the refractory heat-retaining blocks of said first layer is provided with a'longitudinal flange along one upper edge thereof and the opposed longitudinal edge of the block is provided with a complementary recessed shoulder for the reception of the flange of the adjacent block when in assembled relationship.

4. A furnace and heat-retaining and radiating assembly as set forth in claim 2 where each of the refractory heat-retaining blocks of said first layer is provided with a tongue adjacent the upper extremity of one longitudinal face thereof and the op posed longitudinal face of said block is provided with a complementarily located groove for the reception of the tongue of the adjacent block when in assembled relationship.

5. A furnace and heat-retaining and radiating assembly as set forth in claim 1 where intermediate refractory spacers are positioned beneath said tubular rodlikeelements, one ad- 7 jacent each extremity thereof, the upper surface of each intermediate spacer being provided with a centrally located depression for the reception and retention of the extremity of the tubular rodlike element.

6. A furnace and heat-retaining and radiating assembly as set forth in claim 5 where each intermediate spacer is provided with a plurality of horizontally disposed spaced bores to permit free circulation of heated air therethrough.

7. A furnace and heat-retaining and radiating assembly as set forth in claim 1 where each of the elongated heat-retaining bars is provided with a pair of spaced stainless steel reinforcing rods disposed longitudinally thereof, and each longitudinal face of each of said elongated bars is provided with a plurality of closely spaced and vertically disposed semicircular grooves, the spacing and location of said grooves being such that the grooves in adjacent bars are complementary to provide free passage of heated air therethrough when the elongated bars are in assembled relationship.

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