US1893240A - Warm air furnace - Google Patents

Description

1933. H. J. HILLIER ET AL 1,893,240

WARM AIR FURNACE Filed Feb. 14. 1950 2 Sheets-Sheet l Jan. 3, 1933. H, J. HILLIER ET AL WARM AIR FURNACE Filed Feb. 14, 1930 2 Sheets-Sheet 2 Patented Jan. 3 1933 UNITED sATEs rarer HAROLD JOSE-PH HILLIER AND RONALD GRUNDY HILLIEB, on roRoN'ro, oN rnnrq,

" CANADA i WAR-M AIR FURNACE Application filed February 14,1930.

Our invention relates to improvements in Warm air furnaces, and one of the objects of the invention is to provide a unique construction whereby the products of combustion will 5 primarily move upwardly from the fire-pot, and then downwardly thereafter through a tortuous pathway so that the up-flowing air to be heated will be gradually heated before it reaches that portion of the heating apparatus where products of combustion are at their highest temperature, thus realizing the greatest entraction of heat therefrom by the air being heated. Another object is to create a warm air furnace of welded sheet-metal construction that is positively gas and dust tight and whereby all possibility of leakage of. gases or dust'through joints, or the seepage of carbon monoxide from the furnace proper into the warm air passages, is positively eliminated, and whereby in the case of astrong draft passing through the furnace by'reason of the sealed joints no heated fresh air can be drawn from the warm air passages through these joints, as is now commonly the case and passed into the body of waste products of combustion flowing to the flue, with a result that greater efficiency is had from a given 7 amount of fuel consumed. The advantage flowing from the facts just mentioned is that our warm air plant, by circulating a continuous flow of clean healthy air, takes on the benefits and advantages of a ventilating system.

Another object of our invention is to make use of a natural draft, undiminished by infiltrations from the warm air ducts owing to the leak-proof construction of the joints, to burn cheap fine low grade types of fuel.

Another object of the invention is to minimize the danger of explosion while burning the grade of fuel mentioned.

Another object of our invention is to drastically reduce stack losses by means of our large ratio of heating surface to grate area; the favorable position of the vertical air-fines, and the long bafiied path that the products of combustion must follow before they reach the stack.

Another object of our invention inherent 50 in the welded construction thereof, is to elimpoint out the pathway for the various air Serial No. 428,376.

inate the use of cement or asbestos in packing the joints between the parts composing the warm air furnace, thereby dispensing with what might be termed zones of insulation, which result in: heat centres, with the advantage that we secure absolute diffusion of the heat throughout the whole structure. The zones of insulation such as thecemented joints, are positive barriers to uniform diffusion or transference of heat units through-'- out the warm air furnace In existingidesigns of warmair'furnaces much difficulty :ias arisen from the very rapid oxidation and warping of the sheet-metal sections thereof when adjacent to or exposed to the direct radiation of the fuel body and we have found that suchoxidation and warping is due to the use of cement or asbestos in' making joints between the various parts of the apparatus, thus interfering with the diffusion of the heat resulting in heatccentres. The result is a shortening of the life of the sections of the warm air furnace subjected to said heat cen-v tres. Moreover the warm air, in such types of furnacesmentioned, coming into contactwith the intensely hot sections thereof is scorched andconsequently is not: healthful. Furthermore it is-well-knownthat the concentration of heat above referred to lowers the average efiective co-eflicients of heat transfer.

In the following specification and the i drawings forming part thereof, we shall disclose our preferred form of construction, and

currents. 1

Fig. 1 is avertical central section onthe line 1-1, Fig. 2, through a heating apparatus embodying our invention. Fig. 2 is a horizontal cross section on the line 2-2, Fig. 1. Fig. 3 is a vertical section on the line 3-3, Fig. 1. Fig. 4c is a perspective viewshowing the interior portion of the heating apparatus controlling the directions of movement of the products of combustion and the air to be heated. Fig. 5 is a side elevation'of portions of the preferred form of fire-pot used.

In the draw ngs, like characters ofreference refer to the sameparts.

At the outset it must be understood that vac . be heated will flow,

provided door'8 is suitably we may make use of any suitable type of fire-pot in combination with the means disclosed to direct the direction of movement of the products of combustion and the air to be heated, though with the type of fire Ipof;i illustrated much increase in efficiency is The unique construction for controlling the direction of movement of the products of combustion provides for the desired turbulence thereof as they flow towards the stack; therefore these waste products of combustion will be caused to give up the maximum number of heat units to the walls of the vertical fiues through which the incoming air to thus increasing the efliciency of the said apparatus.

Although this disclosure indicates that coal or similar fuel is to be used in the fire-pot, it must be understood that any other tvpe of fuel may be used, such as gas or oil.

The heating apparatus comprises a suitable outer casing 2 having a heat-distributing dome 3 from which opens any desired number of hot-air pipes 4. Located within the casing 2 is another casing 5, spaced apart from the casing 2. A boxing 6 is provided which surrounds an opening 7 in the front Wall 5 of the casing 5. This boxing is welded or otherwise secured in place, and projects through the casing 2. Any suitable dampermounted in place to control the'opening 7 through which fuel is supplied to the fire-pot; The boxing 9 simllar to the boxing 6, though smaller, is attached to the wall 5 around an opening 10 therethrough. A suitable door'll is associated with the boxing 10 so as to control the opening therethrough. A boxing 12 is located at the bottom of the heating apparatus, and is carried by the wall 5 to laterally enclose an opening 13 therethrou'gh. A damper-provided door 14 is associated with the boxing 12 and casing 2 to control air passing into the ash pit. This ash pit is composed of a horizontal plate 15 and a back plate 16 forming the rear wall thereof. Preferably, though not essentially, integrally formed with the plate 16 is a horizontal plate 17. 18 is a collar carried by the back wall 20 and surrounding the opening 19, formed therein, and projecting through the casing 2. The products of combustion pass through the collar 18 to the stack (not shown). 21 are the side walls of the casing 5, and of course these walls form the sides of the ash pit. 22 is a plate at the'top of the ash pit, and this plate snugly fits against the walls of the ash pit so that no air can pass between the edges of said plate and its supporting walls. Any suitable construction may be employed to support said plate 22, though we prefer to use angle bars 23-suitablysecured as by welding to the walls 21. As shown clearly in Figs. 2 and 3, portions of the plate 22 at opposite sides overlap the lower flanges of said angle bars 23 thereby providing supporting means for said plate. Bolts 24 or other fastening means may be used to couple the plate 22 firmly to the angle bars 23. As shown clearly in Figs. 1 and 2, the plate 22 is provided with a central opening in which is located the grate bars 25. These grate bars may be of any suitable construction, and a conventional type thereof has been illustrated in the drawings. The preferred manner of supporting the grate bars used is to integrally form with the opposite sides of the plate 22 trunnions 26 adapted to be received by the ends of said bars to, permit the same to be rocked.

27 are the flues for the air to be heated. These fiues are open at both ends, and are carried at their lower ends by the plate 17 so that they will be in alignment with their respective openings 28 formed in said plate. These flues continue to the top of the casing 5 and open therethrough as shown clearly in Fig. 3. The said fiues-27 may be of any desired number, and they are spaced apart as shown clearly in Figs. 2, 3 and. -'l. .29 are bafile plates vertically-disposed and interposed between t-he flues 27. These baffle plates together with the inner ends 30 of the fines 27 form the inner wall of the combustion chamber. As shown clearly in Fig. 4, the baflie plates 29 extend down to the plate 17, and of course are interposed between "the flues 27, and these flues and the side walls 21. Figs. 1 and 2 show clearly that the fiues 27 are spaced apart from the wall 20.

31 are baflle plates, one located above the other in each passageway on each side of any given flue 27. The upper baffle plates are secured to the baffle plates 29 at their inner ends, and the outer ends of the lower baffle plates 31 are secured to the wall 20. As shown clearly in Figs. 1 and 2, the outer ends of the fiues 27 are spaced apart from the wall 20 thus providing for a passageway 33 therebetween. This passageway at the lower baffle plates 31 is blocked by any suitable means, such as a plate 32, resting upon the outer ends of said baffle plates, and extending from one side wall 21 to the other side wall, and be-'' tween the outer ends of the fiues 27 and the wall 20. Suitable supports 34 carried by the flues 27 may be used to additionally support said baflle plates 31.

While any suitable type of fire-pot may be used, we prefer to use one constructed with openings in the sides thereof. The preferred type of fire-pot may be made in one piece,

or in sections, to facilitate repairs. In the drawings, we show the fire-pot made of sections 35. These sections have preferably vertical walls, and at the top of each one is formed an outward-upward extending flange 36, the outer edges of which rest in contact with the side walls 21; the front wall 5,

- shown by arrows with and the rear wall of the combustion chamber formed by the baflle plates 29 and the ends of the flues 27. The plate 22 is provided on its upper side with an annular groove or channel 37 which receives a correspondinglyshaped lower end of each section 35.

Each section is provided with one or more openings 38 therethrough, and as shown clearly in Figs. 1 and 3 these openings are formed so that their upper and lower walls will be inclined at an angle. If desired, the

abutting edges of the sections 35 may also be provided with openings, which edge openings may align, as shown clearly in Fig. 1.

As shown clearly in Figs. 1 and 3, there is an annular passageway 39 formed around the fire-pot since the walls of the fire-pot are spaced apart from the side walls 21; front wall .5, and the wall formed by the baffle plates 29 and the ends 30 of the fines 27.

The casing 5 is of all steel, welded construction throughout and so designed that all boxings, collars, and connections welded to it, pass cleanly through outer casing 2 before any joints are made. This form of construction eliminates the possibility of any leakage of gases from furnace into warm air passages.

The operation may be outlined as follows:

With a fire burning, air will be drawn through the fuel bed by the action of the that of either single path. This lessened fuel bed resistance, with means whereby secondary air can be regulated to requirements of fuel body, enables a heating apparatus employing our principle to operate under much weaker draft than that required in ordinary fire-pot construction. In other words, with average draft available, we can burn fuel beds of buckwheat of depths and at rates of combustion, comparable to those used with high grade anthracite in ordinary furnace construction. Applied to domestic fuels, such as pea, nut, and stove sizes of anthracite, we can obtain rates of combustion much higher than that possible with ordinary furnace construction.

The waste products of combustion are crossed tails, and the paths thereof are over plates 29 into the passageways between the The primary air, that which passes 'ber may rapidly and the top of the baffle.

lines 27 and down and around the bafiie plates 31 and finally escaping through the collar 18. Theair to be heated passes through the opening 39 at the bottom of the back of the heating apparatus and into the chamber formed between portions of the side walls 21 and casing 2 and the plates 16 and 17 and isdistributed over the heating surface of furnace and by means of flues 27 and passageways between inner and outer casings 2 and 5.

The preferred type of fire-pot we use has the lowermost openings in the walls thereof well above the top of the normal ash layer,

and the topmost openings are well below the normal top of the fire bodyL' When the top of the fire body is below any of the said openings, the door 11 is closed thereby preventing passage of air into the passageway 39 so that no air will pass over the top of the fire body to interfere with combustion.

hen the door 11 is closed, air will pass into the fire bodyfrom the ash pit.

The baflie plates 29', and portions of the front ends 30 of. the fines 27 form a central transverse wall in this heating app aratus, that extends from one side of the casing 5 to the other side.

In former designs of similar'heating' plants much difficulty has arisen from the very rapid oxidation and warping of their sheet-metal" sections when adjacent to or exposed to the direct radiation of the fuel body, due to the commonly accepted furnace practice of using cement or asbestos in making joints and connections. Such practice makes posslble the formation of centresof intense heat. This heat rapidly accelerates the oxidation of the metal, and eerlouslyshortens the life of the sections affected.

Moreovercomm g into contact wlth these' ntensely hot sections is scorched ful. In addition, such concentration of heat lowers the average efiective co-eflicients of heat transfer.

New, by employing an all-steel, 6lBCtI'1C welded construction throughout, the furnace becomes an integral unit of one continuous I sheet of metal, so that the intense heat from sections surrounding the combustion chamconipletely diffuse throughout the entire surface of the furnace. In this way, every s surface in contact with the warm air to be heated, the heat; the air is heated without scorching and the life of the furnace lengthened appreciably.

Moreover the favorable position of the allsteel, welded, long, chimney-like, vertical fines, with their continuous metal contact with the hottest parts of the furnace can create a velocity in the warm air duct much higher than that ordinarily available. In;

uare inch of the furnace becomes a potential transmitter of the warm air- 105.

and rendered unhealth- 1 this way the capacity and efliciency of system is materially increased. lVhat we claim as our invention is:

l. A warm air furnace comprising asheetmetal casing having a fuel opening in the front side thereof and openings in the rear thereof to permit in one case the escape of waste products of combustion, and the other case to admit fresh air into said casing, and embracing a pluralit of sheet-metal members which are welded to make sealed joints where they abut, thus providing for positive diffusion of heat tl roughout the structure and the avoidance of setting up heat centres; a central vertical transverse wall within said casing forming the bacl: wall of the combustion chamber, said wall being composed of the end walls of a plurality of spaced substantially vertical sheet-metal air-fines communicating with said fresh air inlet and opening through the top of said casing, and sub stantially vertical sheet-metal baflle plates located between said flues and the side walls of said casing and terminating at their upper ends. a suitable distance below the top of said casing, the said elements where they abut one another, and abut the side walls of said casing having their joints sealed by welding, the said flues being spaced apart from the rear wall of said casingto form a passageway in connection with passageways around said fines and in communication with the opening for the escape of waste products of combustion, and an ash pit located beneath said combustion chamber.

2. In the warm air furnace as set forth in claim 1, the further feature of providing substantially horizontal baffle plates within the passageways around said fiues; an apertured fire-pot supported by a flange-provided portion in the lower portion of said combustion chamber and above said ash pit and chiefly in spaced relation to the front and side walls of said casing and said transverse wall, and having its top portion located in sealed contact with said walls and its lower portion supported in sealed contact with said flangeprovided portion of said casing thus providing a heating chamber surrounding the sides of said fire pot into which air passes through a controlled opening formed in the front wall of said casing whereby the volume of secondary air passing into said chamber surrounding said fire pot is regulated independently of the primary air passing into said fire pot through said ash pit.

HAROLD JOSEPH HILLIER. RONALD GRUNDY HILLIER.

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