US3388900A - Tobacco curing and drying apparatus - Google Patents

Description

June 18, 1968 .J. 5. TAYLOR TOBACCO CURING AND DRYING APPARATUS 5 Sheets-Sheet 1 Filed June 7, 1966 June 18, 1968 J. S. TAYLOR TOBACCO CURING AND DRYING APPARATUS 5 Sheets-Sheet 2 Filed June '7, 1966 I AWIH 7 lyJul-m 5'. Ta Zar June 18, 1968 J. 5. TAYLOR 3,388,900

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TOBACCO CURING AND DRYING APPARATUS Filed June '7, 1966 5 Sheets-Sheet 5 IZ\Z\ T r W m T f 33 Ji rz g ur United States Patent 3,388,900 TOBACCO CURING AND DRYING APPARATUS John S. Taylor, Jacksonville, Fla., assignor to Tlfcon Company, Jacksonville, Fla., a corporation of Florida Filed June 7, 1966, Ser. No. 555,796 Claims. (Cl. 263-19) ABSTRACT OF THE DISCLOSURE A tobacco curing barn with the tobacco to be cured hanging in tiers, has an air heating and circulating unit setting on the middle of the floor of the barn. The air is drawn into the top of the unit by an air circulating fan and is discharged from the bottom thereof along with the products of combustion to flow radially in all directions across the floor of the barn. The air heating and circulating unit has a cup-shaped fire pot coaxial with and located in the bottom portion of an inverted cupshaped outer casing. The side walls of the fire pot and outer casing are uniformly spaced to provide an annular air passage. Legs on the unit support the same with the bottom edge of the casing spaced above the floor of the barn to provide an outlet from the annular air passage. A hood-like flame shield supported above the fire pot directs the air drawn into the top of the unit into the annular air passage. The peripheral portion of the flame shield projects beyond the mouth of the fire pot to constrict the entrance into the annular air passage and produces a low pressure zone at the mouth of the fire pot. An oil burner nozzle supported on the top wall of the outer casing receives air for combustion from the air circulating fan and directs flame down into the fire pot.

This invention relates to the tobacco curing art and has as its purpose to provide a simple, inexpensive, selfcontained portable air heating and circulating unit adapted to be set directly on the floor of a tobacco curing barn and to coact with the barn floor in effecting forced circulation of the air throughout the entire barn, with the hottest air moving along the floor and radiating from the unit in all directions towards the perimeter of the floor.

Another object of this invention is to provide a portable, self-contained air heating and circulating unit which, though designed and intended especially for use in curing and drying tobacco, can be used for a wide variety of other purposes.

With a view toward achieving low cost, it is a specific object of this invention to provide a forced air heating and circulating unit in which the heat source comprises a burner nozzle arranged to direct flame into a combustion zone or fire pot, and wherein a single blower effects circulation of the air through the unit and also supplies combustion air to the burner nozzle and the combustion zone.

Also with a view toward achieving low cost, it is another object of this invention to provide an air heating and circulating unit of the character described wherein an oil burner having a fuel pump provides the heat source, and a common drive motor drives the fuel pump and also an air circulating fan or blower by which the air is circulated through the unit.

In an air heating and circulating unit designed especially for use in curing and drying tobacco, it is customary to discharge the bot gases and products of combustion from the combustion zone or chamber of the unit directly into the air stream being circulated through the unit. To achieve good combustion under these conditions, it is essential that only the air needed for combustion be fed into the combustion zone, and also that the combus- 3,3883% Patented June 18, 1968 tion zone be effectively insulated from the air being circulated through the unit.

This invention assures the attainment of these objectives by a unique concentric arrangement of the combustion chamber and the air passage through which the air flows as it is circulated through the unit, and a novel Way of communicating these spaces or zones; and by the pro vision of an effective flame shield to insulate the combustion zone from the cooling effect of the air being circulated through the unit.

With the above and other objects in view which will appear as the description proceeds, this invention resides in the novel construction, combination and arrangement of parts substantially as hereinafter described and more particularly defined by the appended claims, it being understood that such changes in the precise embodiment of the hereindisclosed invention may be made as come with in the scope of the claims.

The accompanying drawings illustrate one complete example of the physical embodiment of the invention, constructed according to the best mode so far devised for the practical application of the principles thereof, and in which:

FIGURE 1 is a view essentially in vertical section through the air heating and circulating unit of this invention;

FIGURE 2 is a horizontal cross sectional view through FIGURE 1 on the planes of the line 2-2;

FIGURE 3 is a horizontal cross sectional view through FIGURE 1 on the plane of the line 33;

FIGURE 4 is a fragmentary detail sectional view through FIGURE 2 on the plane of the line 44;

FIGURE 5 is a top view of the unit with parts thereof broken away;

FIGURE 6 is a detail horizontal sectional view through FIGURE 1 on the plane of the line 66;

FIGURE 7 is a perspective view at a reduced scale of the complete unit;

FIGURE 8 is a vertical sectional view through a tobacco curing barn with the air heating and circulating unit of this invention positioned therein and coacting with the structure of the barn to effect the desired circulation of air; and

FIGURE 9 is a plan view of the barn floor, or a horizontal sectional view on the plane of the line 99 in FIGURE 8.

Referring now particularly to the accompanying drawings in which like numerals indicate like parts throughout the several views, the numeral 10 designates generally a conventional tobacco curing barn having a floor 11 which often is simply the ground upon which the barn is erected, and racks 12 from which the tobacco leaves are hung in superimposed tiers, as is customary.

Also as is customary, the barn may be equipped with a controllable ventilator 13 which is kept closed during the stem-killing portion of the curing cycle, and is open during the drying of the tobacco leaves to permit moisture laden air to escape from the barn.

Set directly upon the floor 11 and substantially centraily thereof, is an air heating and circulating unit 14. As distinguished from air heating and circulating units or furnaces heretofore available to tobacco growers, such as those of the Mac-Cracken Patent No. 2,611,599, and the Taylor Patent No. 3,109,637, the unit 14 is entirely self-contained and requires no ducts or spreaders to achieve the desired distribution of heated air within the barn. Instead, it is designed to utilize and coact with the floor of the barn to eifect the needed distribution of heated air throughout the barn interior, with the hottest gases and air flowing along the floor and radiating in all direc tions from the unit towards the perimeter of the floor. Being self-contained, the unit 14 is also portable so that it may be placed wherever it produces the most effective and uniform circulation.

Since the hottest gases and air flow along the floor of the barn, the lowermost tiers of tobacco leaves can be hung much lower, without danger of overheating and, as a result, the effective capacity of the barn is increased.

The unit 14 comprises an outer casing 15 in the form of an inverted cup-shaped open bottomed sheet metal shell having a cylindrical side wall 16 and a conical top wall 17. Located in the lower portion of the casing or shell 15 is a fire pot 18, preferably formed of refractory material and having a flat bottom wall 19 and an upright cylindrical side wall 20.

The fire pot is supported and held in spaced concentric relationship to the side wall 16 of the outer shell or casing by being seated in a metal ring 21, which in turn is supported in fixed relation to the casing by four legs 22. These legs are welded to the ring 21 and to the casing side wall, and project down beyond the bottom edge 23 of the side wall to Space the same from the floor. The resulting annular opening between the bottom edge 23 and the floor constitutes the outlet for the unit from which the heated air debouches to flow across the floor, as noted hereinbefore; and a hole 17' in the conical top wall of the casing or shell provides its inlet.

Suspended above the fire pot 18 in the upper portion of the casing 15, is a hood 24. This hood and the fire pot together define a combustion chamber CB, and coact with the walls of the casing to define an air passage AP surrounding the combustion chamber and connecting the inlet and outlet of the unit. The hood 24 has a cylindrical side wall or skirt provided by a stainless steel ring 25, and a conical top wall 26 which forms a flame shield across the top of the combustion chamber and thus is preferably molded or otherwise made of good heat insulating material, such as compacted ceramic fibers. The conical flame shield or top wall 26 rests upon but is not connected to the stainless steel ring which has an inturned flange 27 to provide a smooth flat surface for the flame shield to seat upon. Hence the flame shield is free to shift with respect to the ring 25 as the differences in coeificients of expansion between them cause the flame shield to contract with increased temperature, while the stainless steel ring expands.

The periphery of the conical flame shield or top wall 26 is reinforced and protected by an encircling metal band 28 of channel-shaped cross section, and to maintain the desired tight fit of the band on the edge of the flame shield despite the difference in their coeflicients of expansion and contraction, the band is formed in a plurality of sections 28 that are drawn together by springs 29. Since the band embraces the edge of the flame shield, its lower flange is interposed between the shield and the flange 27 and thus protects the shield against scufiing as it moves with respect to the ring 25.

To hold the flame shield or conical top wall 26 concentric with the stainless steel ring 25 without interfering with their required freedom to shift relative to one another, lugs 30 are resiliently mounted on the shield and project down over the ring. For this purpose-as best seen in FIGURE 4-the springs 29 pass through holes in the lugs.

The hood 24 is supported from the side wall 16 of the casing in concentrically spaced relation with it and with the side Wall 20 of the fire pot, by a plurality of webs or brackets 31 fixed to the stainless steel ring 25 and to the casing side wall.

At its top, the conical wall or flame shield 26 has a round hole 32 into which the lower end of a burner tube 33 fits. This tube houses a fuel burner nozzle 34 and has its upper endwhich is square in cross sectiondisposed in the hole 17 which provides the inlet to the air passage AP, to receive some of the air delivered to the inlet by a blower, indicated generally by the numeral 35. The lower end of the burner tube 33 projects into the hole 32 and the tube is supported therein by a collar 36 welded or otherwise fixed to the tube and resting on the top wall 26 of the hood.

he burner nozzle 34 which may be of any conventional type, has an orifice tip 37 to which fuel under pressure is supplied by a fuel line 38 when a solenoid actuated fuel valve 39 is open. As is customary, energization of the solenoid which opens the fuel valve is con trolled by a thermostat 42 having a sensing element 43 positioned to be responsive to the temperature of the air entering the air passage. Ignition of the fuel issuing from the nozzle tip 37 is effected by a spark drawn across the tips of electrodes 44 which are supplied with high voltage from a transformer 45.

The blower 35 is of the conventional squirrel-cage type having a housing 46 with guard-protected air inlet openings 47 in its opposite end walls 48, and a downwardly facing outlet 49 which projects into the hole 17 in the top of the casing or shell 15. Functionally, therefore, the actual air inlet of the unit is provided by the inlet openings 47 of the blower, since it is at those points where the air in the barn enters the unit.

An electric motor 50 suitably mounted on the blower housing 46 drives the bladed wheel 51 of the blower as well as the impeller, not shown, of a fuel pump 52 which delivers fuel under pressure to the fuel valve 39, it being understood that the pump is connectible with a source of fuel, as by a fuel line 54. The hub 55 of the blower wheel may be fixed directly to the motor shaft, but the impeller of the fuel pump is connected therewith through a flexible couple 56.

As will be readily apparent, the burner tube 33 cooperates with the hood 24 and the fire pot 18 to complete the division of the interior of the casing 15 into the combustion zone or chamber CB and the surrounding air passage AP, so that by properly proportioning the air entering the mouths of the burner tube and the surrounding air passage, the correct amount of air to achieve optimum combustion will be fed to the combustion zone. One way of obtaining the desired proportioning of the incoming air is by using a burner tube of fixed cross sectional area and adjusting the size of the air inlet into the air passage by selective placement of a blower housing cutoff plate 57. Obviously, once that placement has been determined, the position of the cutoff plate can be fixed. In the structure illustrated, the edge 57' of the cutoff is contiguous to the adjacent side of the burner tube.

When the unit is in operation, the combustible mixture of fuel and air issuing from the discharge end of the burner tube, burns in the combustion chamber CB and the resulting hot combustion gases and products of combustion leave the combustion chamber and enter the air stream flowing downwardly through the surrounding air passage AP, through the annular opening 60 between the skirt or side wall 25 of the hood and the upper edge portion of the fire pot side wall 20. Since the rate at which the gases leave the combustion zone or chamber has an important bearing upon the completeness or quality of the combustion, the size of the opening 60 through which the gases leave may have to be empirically determined, but once that has been done, the correct dimensions will be known.

It has been discovered that combustion is also improved, especially during the start-up period, by creating a low pressure zone at the point of confluence of the hot gases emanating from the combustion zone, and the air stream flowing through the surrounding air passage. This is accomplished by constricting the air passage directly upstream from the point of confluence, and-for this purposea flange 61 extends into the air passage from the side wall 16 of the casing at a level slightly above the bottom edge of the skirt or side wall 25 of the hood.

Still another factor that has a bearing upon the quality of the combustion taking place in the combustion zone, is the degree to which the combustion zone is insulated from the relatively colder air moving through the air passage.

It is for this reason that the flame shield provided by the conical top wall 26 of the hood is formed of good heat insulating material.

The flame shield also has the important function of keeping the upper walls of the casing, and especially its conical top wall 17, from becoming dangerously hot and creating a fire hazard. Experience has demonstrated that none of the outside walls of the unit become hot enough to ignite a tobacco leaf which might fall onto the unit; and to afford safety against fire resulting from any malfunctioning of the unitwhich might cause flaming gases to be discharged through its outlet--a flame detector 62, of any conventional type, is mounted on the hood with its sensing element in the opening 60. This detector is, of course, connected into the control circuit of the burner to shut oil the fuel supply before a dangerous situation can develop.

Attention is directed to the fact that the fire pot is supported with its bottom slightly off the floor on which the unit sets. This is done to pennit air to circulate under the fire pot and prevent overheating and premature failure of its bottom wall 19 due to the flame impinging thereon; and to promote such air circulation under the fire pot, an air deflector 63 embraces part of the lower portion of the fire pot and projects into the air passage. More specifically, the deflector 63, as shown in FIGURE 3, extends around one quadrant of the fire pot supporting ring 21 to which the deflector is attached by spacers 64.

As a matter of convenience in manufacture, the casing may be made in three sections-a lower cylindrical section which has its upper edge turned in to provide the flange 61 and has the legs 22 welded to its lower end; an intermediate cylindrical section which fits onto the upper flanged end of the lower section; and an upper conical section which is suitably secured to the top edge of the intermediate section and provides the top wall 17 of the casing. To facilitate moving the unit from place to place, handles 65 are fixed to the top of the casing.

The thermostat 42 and the transformer 45 are preferably mounted on the blower housing, with the thermostat housed in a cabinet-like enclosure 66 which has a front wall through which the control knob 67 of the thermostat projects, and on which the transformer is mounted.

If the barn floor 11 is simply dirt, as it is very often, it is preferable to set the unit on a pad 68 of any fireproof material, to keep dirt from being blown around by the air issuing from the unitor, if desired, a small concrete platform may be provided for this purpose.

From the foregoing description taken with the accompanying drawings, it will no doubt be apparent to those skilled in the tobacco curing art, that this invention provides an exceptionally convenient, practical and inexpensive air heating and circulating unit, that not only possesses all the attributes of a good tobacco curing furnace, butin addition-can be used for many other purposes because of its ready portability and the fact that it is self-contained.

What is claimed as my invention is:

1. Means for curing and drying tobacco comprising the combination of:

(A) a barn having a floor and structure to support tiers of tobacco leaves within the barn; and

(B) an air heating and circulating unit in the barn to heat the air therein and coact with the floor of the barn to effect forced circulation of the heated air with the hottest air flowing along the barn floor towards the perimeter thereof, so that the lowermost tiers of tobacco leaves may be placed relatively near the floor of the barn Without danger of being heated excessively, said air heating and circulating unit comprising:

(1) an inverted cup-shaped casing having top and side walls defining an air chamber, the top wall having an inlet opening for the chamber and the side wall having a free lower edge,

(2) leg means on the unit to support the same in an upright position with the free edge of the side Wall of its vcasing spaced from the floor so that said free edge coacts with the floor to provide an annular laterally opening outlet for the air chamber through which air leaves the unit to flow across the floor.

(3) structure Within said casing defining a combustion chamber having a top wall spaced down from the top wall of the casing and side wall means spaced in from the side wall of the casing and extending down from the top wall of the combustion chamber to a level adjacent to that of the free edge of the casing side wall so that the walls of the combustion chamber and the casing cooperate to form an air passage surrounding the combustion chamber and extending from the inlet of the air chamber to its outlet, the side wall means of the combustion chamber having outlet means therein through which hot combustion gases and products of combustion can flow from the combustion chamber to join with air moving through said passage and issuing from the annular outlet;

(4) a burner nozzle arranged to direct flame into the combustion chamber,

(5) a blower on the casing with its inlet in open communication with the interior of the barn and its outlet discharging into the inlet of the air chamber, and

(6) air flow directing means in the upper portion of the casing to direct air entering the inlet of the air chamber to said air passage for discharge therefrom through the outlet along with the combustion gases and products of combustion that enter said passage from the combustion chamber.

2. An air heating and circulating unit comprising:

(A) a cup-shaped casing having end and side walls, the end wall having an opening for the admission of air to be heated and the side wall having a free edge;

(8) a cup-shaped fire pot in the open end portion of the casing, said fire pot having an end wall and a side wall terminating in a free edge which defines the mouth of the fire pot;

(C) bridging members connecting the fire pot with the side wall of the casing, said bridging members being spaced from one another and holding the fire pot spaced from and substantially coaxial with the side wall of the casing with the end wall of the fire pot axially adjacent to the free edge of the casing side wall, whereby the side walls of the casin and the fire pot coact to provide an axially extending annular air passage of substantial length and where by the free edge of the casing side Wall and the adjacent outer surface of the fire pot coact to provid an annular outlet for the unit leading from said annular air passage adjacent to the end wall of the fire pot;

(D) a flame shield in the casing between the mouth of the fire pot and the end Wall of the casing, said flame shield being larger than the mouth of the fire pot;

(E) means mounting the flame shield in the casing with its outer edge portion spaced axially from and projecting laterally beyond the mouth of the fire pot and with its outer edge spaced from the side Wall of the casing to coact therewith in providing an annular entrance to said axially extending annular air passage which entrance is substantially smaller in area than the annular air passage;

(F) a burner nozzle arranged to direct flame into the fire pot;

='(G) duct means surrounding the burner nozzle to supply combustion air to the fire pot; and

(H) air moving means on the casing to force air into the casing through said opening in its end wall and against the flame shield for direction thereby to said annular entrance into the annular air passage past the mouth of the fire pot, and through said annular air passage to the outlet of the unit, the diflerence in area between the annular air passage and the entrance thereto creating a low pressure zone closely adjacent to the mouth of the fire pot, whereby hot combustion gases and products of combustion are educated from the fire pot to commingle with the air flowing along the annular air passage to the output of the casing.

3. The air heating and circulating unit of claim 2, wherein the burner nozzle and the duct means surrounding it opens through a hole in the flame shield, and the inlet end of said duct means is in line with the opening in the end wall of the casing,

wherein the air moving means is mounted on the end wall of the casing and comprises a blower having a rotatable air impeller discharging through the opening in the casing end wall and into said air duct means as well as into the interior of the casing,

so that the same blower provides air for combustion and circulates the air to be heated through the unit,

wherein the burner nozzle is supplied with fuel under pressure by a fuel pump, and wherein a single motor drives both the fuel pump and the impeller of the blower.

4. The air heating and circulating unit of claim 2, further characterized by:

leg means On the unit to support the same on a floor, with its axis vertical and said end wall of the fire pot contiguous to the floor,

so that the annular outlet of the unit is directly adjacent to the floor.

5. The air heating and circulating unit of claim 4, wherein said flame shield mounting means comprises a supporting rin fixed to the side wall of the casing by spaced brackets,

the peripheral portion of the flame shield resting upon said supporting ring and being free to move lat rally relative thereto to compensate for difierences in coefficients of expansion and contraction therebetween.

6. The air heating and circulating unit of claim 5, wherein the flame shield is formed of good heat insulating material,

and further characterized by a metal reinforcing band on the periphery of the flame shield,

said reinforcing band having a portion thereof interposed between the underside of the peripheral portion of the flame shield and the supporting ring.

7. The air heating and circulating units of claim 6, wherein the flame shield is formed of non-metallic heat insulating material,

and wherein said metal reinforcing band comprises a plurality of sections, each U-shaped in cross section,

and spring means yieldingly drawing said sections together to at all times reinforcingly confine the peripheral portion of the flame shield.

8. The air heating and circulating unit of cla m 7, further characterized by:

a flat flange at the upper edge of the supporting ring upon which the reinforcing band rests.

9. The air heating and circulating unit of claim 4, wherein said leg means are part of the bridging members and project below the free edge of the casing side wall,

and wherein the connection of the bridging members with the fire pot comprises a ring fixed to the bridging members and in which the fire pot is supportingly received.

10. An air heating and circulating unit comprising:

(A) a cup-shaped casing having end and side walls, the end wall having an opening for the admission of! air to be heated and the side wall having a free e ge;

(B) structure defining a combustion chamber within said casing, said structure providing the combustion chamber with a side wall and an end wall remote from the end wall of the casing;

(C) bridging members rigidly connecting the casing side wall with the structure that defines the combustion chamber, said bridging members being spaced from one another and holding the combustion chamber-defining structure spaced inwardly of the casing side wall with said end wall of the combustion chamber axially adjacent to the free edge of the casing side wall, whereby an annular outlet is provided for the unit adjacent to said end wall of the combustion chamber;

(D) a burner nozzle arranged to project flame into the combustion chamber;

(E) duct means surrounding the burner nozzle to supply combustion air to the combustion chamber;

(F) means providing communication from the interior of the combustion chamber to said annular outlet, through which hot combustion gases and products of combustion flow from the combustion chamber to said outlet;

(G) air moving means on the casing to force air into the casing through the opening in its end wall;

(H) air directing means by which air entering the casing is caused to flow between the side walls of the casing and the combustion chamber and to issue from said annular outlet along with the hot combustion gases and products of combustion; and

(1) legs fixed to the casing side wall and projecting axially beyond its free edge and beyond said end wall of the combustion chamber to support the unit upon a floor with said end wall of the combustion chamber contiguous to the floor and the free edge of the casin side wall spaced above the floor.

References Cited UNITED STATES PATENTS 1,863,391 6/1932 Bluemel. 2,611,599 9/1952 MacCracken. {2,637,375 5/1953 Tapp et al. 2,896,933 7/ 1959 Barnes. 3,109,637 11/1963 Taylor.

FREDERICK L. MATTESON, 1a., Primary Examiner.

E. G. FAVORS, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,388,900 June 18, 1968 John S. Taylor It is certified that error appears in the above identified patent and that said Letters Patent are herebycorrected as shown below:

Column 1, line 66, "bot" should read hot Column 7, line 11, "educated" should read educted line 12, "output" should read outlet Signed and sealed this 18th day of November 1969.

(SEAL) Attest:

WILLIAM E. SCHUYLER, JR.

Edward M. Fletcher, Jr.

Commissioner of Patents Attesting Officer

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