US2039429A - Oven and the like with heat circulating means therefor - Google Patents

Description

May T. LYDON V OVEN AND THE LIKE WITH HEAT CIRCULATING MEANS THEREFOR Filed April 16, 1951 5 Sheets-Sheet 1 IN VEN TOR.

y 1936- 'r. LYDON 9 29 OVEN AND THE LIKE WITH HEAT QIRCULATING MEANS THEREFOR Filed April 16, 1931 3 Sheets-Sheet 2 May 5, '1936. T. LYDON 2,039,429

OVEN AND THE LIKE WITH HEAT CIRCULATING MEANS THEREFOR Fi-l-ed- Ap-ril 1a, .1951 $Sheets-Sheet s IN VEN TO.

Patented May 5, 1936 OVEN AND THE LIKE WITH HEAT CIRCU- LATING MEANS THEREFOR Timothy Lydon, New York, N. Y.

Application April 16, 1931, Serial No. 530,592

6 Claims.

This invention relates to improvements in ovens for drying, dehydration, polymerization, vulcanizing, heat treating and glass annealing and it consists in the novel features, which are 5 hereinafter described. This application is in part a continuation of my prior co-pending application filed Dec. 6, 1929 under Serial Number 412,168.

An object of the present invention is to provide a perfected process and an oven, in which the atmosphere is maintained at a high degree of uniformity of temperature throughout the oven.

Another object of my invention is to provide a perfected oven, in which, by a continuous and rapid circulation of air, the formation of gas pockets and the accumulation of inflammable vapors produced by drying or by chemical reaction, is prevented and the resulting explosions avoided.

A further object of my invention is to maintain the heating means, or parts radiating heat in the oven at uniform and relatively low temperature.

A further object of my invention is to maintain an internal air circulation and agitation in the oven with the oven atmosphere being maintained at relatively low pressures therein.

A further object of my invention is to provide an exhaust outlet and damper for controlling same, for discharging a part of the air circulated through the oven, which air is mixed with the vapors given olf by sundry articles during the process of baking within the oven.

A further object is to constantly control and dilute the vapor accumulation within the oven,

and to this end means are provided for discharging a part of the vapors and replacing the same with induced fresh air from outside the oven, to obviate inflammable or explosive mixtures within the oven and to provide fresh air for supply of oxygen for the process. I.

Another object of the present invention is 1, to increase the efficiency and sensitivity of the temperature controlling instrument by utilizing a stream flow to sweep away the quiescent film of air which surrounds and tends to prevent heat Fig. 1' is a longitudinal vertical section of one view to obtaining uniform conditioning atmosphere within same.

A further object of the present invention is to provide a centrifugal blower on the inside of the oven, thereby permitting wider and shorter 5 air ducts to be used without the necessity of bringing same outside the oven with consequent loss of heat from same and to prevent the deposition or condensation by cooling of inflammable or harmful carbonaceous material in the ducts and blower.

Another object of my invention is to increase the efficiency of the apparatus as a whole by reducing theconsumption of power used in recirculating the air and by increasing the emciency 15 of the radiating surfaces producing heat within the oven.

Finally, as will hereinafter be ascertained, an object of this invention is to'provide an oven of economical construction and low cost to operate efficiently and with low power or fuel consumption and provided with a rapid circulating system and means for simultaneously exhausting a part of the vapor laden air within the oven and replacing same with an induced draft of fresh air which is immediately diffused.

Various further objects and advantages of the present invention will hereinafter appear.

I attain these objects by the oven and the appurtenances thereof, several forms of which are shown in the drawings or by mechanical equivalents or modifications of same.

,In the drawings:'

form of my oven on the line i| of Fig. 4, looking in the direction of the arrows and showing sundry parts in elevation.

Rig. 2 is a transverse vertical section on the line 2-2 of Fig. 4, showing sundry parts in elevation;

Fig. 3 is a horizontalsectional top view on the line 3-3 of Fig. 1 witha part of the casing 22 cut away to show sundry parts in plan view.

Fig. 4 is a plan view of the oven, with the top of the fresh air flue removed to show sundry parts 45 in plan. w v

Fig. 5 is a plan view in detail of the fresh air inlet damper plates.

Fig. 6 is across sectional detail of the fresh 5 air inlet damper plates.

Fig. 7 is a diagrammatic outline in longitudinal vertical section of an electrically heated truck type oven with recirculation in a vertical direction.

Fig. 81s a diagrammatic outline in longitudinal 55 dinal vertical section of an indirect gas heated conveyor type oven provided with recirculation.

Fig. 13 is a diagrammatic outline in longitudinal vertical section of an indirect gas heated cabinet type oven with vertical recirculation.

Fig. 14 is a diagrammatic outline in longitudinal vertical section of an indirect gas heated cabinet type oven with shelves, and provided with horizontal circulation between the shelves.

Fig. 15 is a diagrammatic outline in longitudinal vertical section of an indirect gas heated two compartment cabinet type oven with shelves, provided with circulation across the shelves.

Fig. 16 is a diagrammatic outline in longitudinal vertical section of an electrically heated cabinet type oven with shelves, and provided with circulation in a vertical direction through the shelves.

Fig. 1'7 is a diagrammatic outline in longitudinal vertical section of an electrically heated cabinet type oven with shelves and circulation horizontally between the shelves.

Like characters of reference refer to like parts throughout the several views:

II designates an outer metal casing, I2 an inner metal casing and I3 heat insulating material of the walls of the outer shell I4 of an indirect gas heated oven, shown in Figs. 1, 2, 3 and 4. The doors I5 of the oven consist of similar parts.

A centrifugal fan or blower I5 is overhung interiorly of said shell I4 under the top I! thereof, to revolve in a horizontal plane, and is secured to a vertical shaft I8, supported in suitable bearings I9 and 20; said shaft I8 has secured thereto at the upper end thereof a suitable source of power 2 I, which may be either a belt driven pulley or a direct connected motor.

The fan I6 is enclosed between the top I! of the oven and a metal shell 22 supported immediately below it. The shell 22 extends across the depth of the oven to be connected to and supported by the combustion chambers 24a and 21a which in turn are connected to the inner metal casing I2 by the angle irons 23; space is allowed between the combustion chamber 24a and 21a and the inner metal casing I2 to form the pressure ducts 24 and 21 and these form a continuation of the duct 28 formed between the metal shell 22 and the inner metal casing I2. Dis- Fig. 12 is a diagrammatic outline in longitubustion of a suitable fuel gas, these burners are disposed immediately above perforated plates 56 which allow the passage of secondary air therethrough from the secondary air intake ducts 53;

for the complete combustion of the fuel gas being .side, and before they escape to the outside,

through the stack 52.

InFig. 2 the openings 49 as indicated are for the accommodation of a truck or carriage 33 provided with shelves 34 both shown dotted, and for supporting the material to be treated. The doors I 5 of the oven shell I4 are employed to admit the said truck or carriage into the oven and its withdrawal therefrom.

During a baking process within my oven vapors or fumes may be formed and it is desirable to positively ventilate the oven at all times. To this end the fan I6 is provided in addition to its main blades IBa with subsidiary blades I6b on its upper surface and is disposed concentric with and immediately under the fresh air inlet 38 and its damper plates 3i and 40.

To efiect and regulate the discharge from the oven of vapors or fumes resulting from the baking process within the oven, an outlet 35 extending through the outer shell I4 of the oven from the duct 28 and a damper 36 hingedly supported at 31 and a damper regulating rod 3| are provided as shown in Figs. 1 and 3.

A fresh air flue 48 leading to the fresh air intake 38 is built around the outlets 35 and 52 so that some of the heat escaping through these outlets may be used to preheat the incoming air.

During a baking process in an oven of the type indicated in Figs. 1, 2, 3 and 4, the inlet damper plate 39 which is pivoted around a projection 4I on the fixed damper plate 40 is moved by means of the regulating rod 3I so that the holes 42 always register wholly or in part with the holes 43 in the fixed plate 40. The outlet damper 36 is also likewise never entirely closed but opened to the extent found by the operator to suit his particular needs best. The stops 44 and 45 are so placed on the regulating rod 3I of the intake damper that this plate can never be moved beyond certain limits, these limits being such that the holes 42 and 43 in the damper plates always register to some extent.

When an oven of the type described is in operation a stream of fresh air is being drawn in by the subsidiary blades IIib on the fan I6 and a stream of vapor laden air is being discharged through the outlet 35 simultaneously with a rapidly circulated stream of heated air being forced through and across the material placed within the oven and in the directions indicated by arrows in Fig. 2. The fresh air induced into the passage 38 is heated during its passage along the heated sides of the combustion chambers 24a and 21a and serves to reduce the temperature of these surfaces.

In a form of my oven above described the operator is afforded means for effecting a high degree of uniformity in temperature, and positive control over ventilation within the oven, such as is adaptable to a wide variety of useful applications.

In the forms of my oven hereafter described the same rapid circulation of air with the accompanying processes already described, are brought about in modified forms to suit the nature of the work to be handled withrespect to size, shape, time of baking, amount to be handled, method of handling and such other considerations as enter into factory production.

Fig. 7 shows a modification of my oven adapted for electric heating and truck loading. Aninterior sheet metal shell 51 forms the inside wall of the pressure ducts 24 and 21.

The electric heating units 58 and 59 placed close to the perforations 60 and vanes Si in the lower portion of the shell 51, heat the air directed against them by said vanes and perforations, and the baflle 62 placed near the intake to the fan l6 helps to spread out the course taken by the air through the oven.

In Fig. 8 I indicate how my oven may be adapted for direct oil or gas heating. In this modification the products of combustion are allowed to enter the oven proper and are used for heating. The oil burner 63 placed in a suitable refractory firebox 64 generates heat and hot gasses. The gases and convection currents arising from the combustion are assisted in their vertical rise by draft induced on them by the air passing over the vane 65 disposed as indicated above the outlet 66 to the firebox 64.

Another method of heating an oven of this type is indicated on the right side of Fig. 8 in which a gas burner 4'! provided with a secondary air supply duct 53 and disposed under a vane 61 which dissipates some of the heat generated by the flame 41b of the burner 41 and induces a draft to carry away the hot products of combustion, in a direction indicated by the arrows. The fresh air intake for this type of oven may be located near the floor.

Fig. 9 shows a modification of my oven direct gas heated to take two trucks and with circulation from each side across the trucks to a central passage H between the trucks. The sheet metal shell 57! providedwith perforations 68 matching the spaces between the shelves 34 of the trucks 33, forms the pressure ducts 24 and 21 which are closed, in this modification, at the bottom. The hot gases of combustion rising from the burners 41 are taken in circulation by the cross currents of air between the shelves and together are drawn out from the passage ii to the fan l6.

Fig. 10 indicates a two truck electrically heated oven adapted for horizontal and vertical air circulation. In this modification the pressure ducts 24 and 2?, are partly restricted at their lower ends by necks l4 and i5 so that part of the air is forced across the material in the oven and the remainder is blown across the heaters to mix and rise with fresh air drawn through the fresh air inlets lb and ll disposed below the electric heaters 8|.

Fig. 11 shows a two compartment modification of my oven provided with means for cross circulation and electric heating. This oven may be adapted for truck, drawer or shelf loading. The space '38 between the compartments I9 and 88 contains the electric .heating elements 8| and forms the suction duct towards which circulation takes place from the pressure ducts 24 and 21.-

In Fig. 12 I show a modification of my oven adapted for indirect gas heating and with a conveyor for continuous operation. The material to be baked is placed on the conveyor 82 which is slowly drawn through the oven by-the sprockets 83 and a suitable driving mechanism not shown.

Gas is burned in the burners 41 which are supplied with secondary air through the ducts 53. The combustion chambers 24b and 21b carry away the products of combustion to the outlets 84 and 85. The fan I6 which is direct driven by the motor 88 is disposed so that its secondary blades l6b .draw a stream of fresh air as indicated by the arrows through the passages 81 and along the hot surfaces of the combustion chambers 24b and 21b. The fan I6 blows the incoming preheated fresh air across the upper hot surfaces 89 and 90 through the perforated floor ill] of the oven and the material on the perforated conveyor 82 as indicated by the arrows, and is drawn down through the material and back into the .fan above the funnel 9|. A certain part of the air is exhausted at each open end of the oven and the hoods 92 and 93 are provided to carry away these vapors. In an oven of this nature room for circulation of air between the articles to be baked must be allowed when they are placed on the conveyor at the loading end.

I indicate in Fig. 13 an indirect gas heated cabinet type oven with air circulation in a vertical direction. The fan I6 is direct connected to the motor 88 and blows fresh air and recirculated air over the hot surfaces of the combustion chambers 24b and 21b. The air is forced upward through the pressure ducts 24 and 21 and down through the interior space 94 of the oven. The products of combustion are carried away by the outlets 95 and 96.

I indicate in Fig. 14 an indirect gas heated cabinet type oven with shelves and cross circulation between the shelves. In this modification the fresh air is induced through an opening 91 in the suction passage 98, by the passage over a vane 91a of the recirculated air. The combined fresh and recirculated air is then blown over the hot surface of the combustion chamber 241) while a part thereof is exhausted through the stack Hll containing the damper E02. The air passes across the oven from the pressure duct I80 to the suction duct 98.

In Fig. 15 I show an indirect gas heated two compartment cabinet type oven with shelves and cross circulation between the shelves. The oven is divided into two compartments I03 and I84 and a central suction passage 99. By dividing the oven as here indicated and narrowing the width of the trays or shelves to fit therein, and lessening the. horizontal distance through which the air is circulated it is possible to obtain the very great degree of temperature uniformity desired in baking processes involving the fractional distillation of volatiles from semi-solid materials.

In Fig. 16 I indicate an electrically heated cabinet type oven furnished with perforated shelves and adapted for vertical recirculation through the material placed on said shelves. No fresh air inlet is provided in this modification which is one used for baking or heating processes which require uniform temperature and exact temperature control but in which the processes brought about by heating, do not result in the formation of vapors or fumes to any marked extent. The electric heating units 81 are placed in the pressure ductsformed by the side walls of the oven and the interior shell 51.

I indicate in Fig. 17 an electrically heated cabinet type oven with shelves and trays I01 and a f esh air intake 91 located in the suction duct 98. The electric heater 8| is placed directly in front of the fan It so that it is keptat a low temperature by the stream of air which is blown over it.

The heated air passes between the trays ID! in traveling from one side of the oven to the other and in so doing bakes the material .therein to a uniform degree and immediately carries away all vapors as soon as they are formed.

Many other changes may be made in the modifications of my oven without departing from the main scope of my invention, and parts of my invention may be used without other parts.

I do not therefore restrict myself to the details as shown in the drawings, but I intend to include also all mechanical equivalents and obvious modifications of the same within the scope of my invention.

I claim as my invention:

1. In combination, a shell having opposite side walls and a substantially horizontal bottom wall; an approximately horizontal thin heat conducting intermediate wall slanting upwardly from near the mid-part 'of said bottom wall to said opposite walls to form a heating chamber; heating burners in said heating chamber; ducts supplying combustion air to the lower part of said chamber; outlet means at the upper outer part of the chamber; a centrifugal fan in the interior of said shell near, and substantially axially perpendicular to said bottom wall, above the mid-part of the-intermediate wall and adapted to throw air from the vanes against said intermediate wall; a partition extending above said fan having an intake opening at the axis of the motor; said slanting floor providing an unobstructed guide means for air from the tips of the fan blades to the respective flues; whereby air is evenly distributed substantially tangentially from said tips, free of eddies and free of lateral gravity components, whereby even distribution is maintained.

2. An oven comprising a substantially rectangular shell of heat insulating material forming a material receiving space and having a substantially horizontal wall having a ventilating opening through a mid part thereof; an axially vertical fan shaft passing vertically axially through said opening and spaced from contact with the shell; a centrifugal rotor fast on the shaft within the shell, near said horizontal wall, and comprising an upper ventilating fan and a lower circulating fan, each fan having blades extending outwardly from said shaft, whereby air drawn directly from said opening and from said space into the fans at the middle part, is centrifugally forced outwardly and mixed and evenly distributed substantially throughout said space, whereby even distribution is maintained; said intermediate wall having an outlet opening near said ventilating opening; and heating means in the shell disposed to heat upwardly moving currents of air only, thereby aiding convection and circulation.

3. In combination, a shell having opposite side walls and a substantially horizontal intermediate top wall; a centrifugal fan in the interior of said shell near, substantially adjacent to and axially perpendicular to said intermediate wall; pressure flues on opposite sides of said interior near said opposite walls and extending substantially from top to bottom and front to rear thereof and forming a deep vertical material receiving space therebetween; a pair of vertical sets of horizontal shelves in said space leaving a vertical passage between the sets vertically under the axis of the fan; said flues having aseries of openings directed directly between adjacent shelves of the same set; said flues being provided with passage openings at the upper end parts and closed at the lower end; and a partition extending across said interior near said fan between the fan and said space and. cooperating with said intermediate wall to form a fan casing having an inlet from said interior at the axis of the motor, and providing passage means communicating with and discharging into the adjacent passage openings at the upper ends of said flues; said casing forming an unobstructed passage from the tips of the fan blades to the respective flues; and means under said shelves for heating the air in said space; said space providing a deep body of heated air assisting by convection in its circulation.

4. In combination, a shell having opposite side 'walls and a substantially horizontal intermediate wall; a centrifugal fan in the interior of said shell near, substantially ad 'acent to and axially perpendicular to said intermediate wall; pressure flues on opposite sides of said interior near said opposite walls and extending substantially from top to bottom and front to rear thereof and forming a deep vertical material receiving space therebetween; two vertical sets of horizontal shelves in said space leaving a vertical space alined with the axis of the fan; said flues having a series of openings directed between adjacent shelves; said flues being provided with passage openings at the end adjacent to the fan, the other ends of the flues being closed; a partition extending across said interior near said fan between the fan'and the mid part of the interior and cooperating with said intermediate wall to form a fan casing having-an inlet from said interior at the axis of the fan, and providing passage means communicating with and discharging into the adjacent passage openings atthe adjacent ends of said flues; said casing forming an unobstructed passage from the tips of the fan blades to the respective flues; whereby air is evenly distributed tangentially from said tips, free of eddies and free of lateral gravity components, whereby even distribution is maintained; means under said shelves for heating the air in said space; said space providing a deep body of heated air assisting by convection in its circulation.

5. An oven comprising a shell of heat insulating material having an substantially horizontal wall; a substantially vertical fan shaft passing through said horizontal wall of the shell; a centrifugal fan fast on the shaft Within the shell, near said wall, and having upright blades extending outwardly from said shaft, whereby air drawn into the fan at the middle part, is centrifugally thrown and evenly distributed substantially horizontally tangentially from the tips of the blades,

means forming a passage inlet to the fan whereby air is drawn into the fan substantially at the center thereof; heating means in the shell; said shaft being spaced from contact with the shell to provide an air inlet into the oven around the shaft; said horizontal wall being provided with an outlet opening; a stack for said outlet opening, and means forming an inlet passage surrounding said stack shaft and air inlet and discharging into said air inlet, thereby to extract heat from air in said stack to pre-warm the air passing in at said air inlet.

6. An oven comprising a shell of heat insulating material forming a material receiving space and having a substantially horizontal wall having a ventilating air inlet opening, heating means in said shell; an axially vertical fan shaft passing through said ventilating opening and spaced from contact with the shell; a centrifugal fan fast on the shaft within the shell, near'said horizontal :wall and opening and having blades extending outwardly'from said shaft adapted to draw ventilating air from said opening and to draw air from said space into the fan at the middle part, and immediately centrifugaily force said air out? wardiy and immediately evenly mix it before it reaches said space and then distribute it slibstantiaily horizontally tangentially from the tips of the blades, and then throughout said space,

- whereby even distribution of heat is maintained in said space and throughout the material to be 5 heated, thereby to heat the material evenly. V

TIMOTHY LYDON.

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