U.S. patent number 3,664,034 [Application Number 05/074,678] was granted by the patent office on 1972-05-23 for tobacco bulk curing system with improved curing air flow rate control.
This patent grant is currently assigned to R. H. Bouligny, Inc.. Invention is credited to Robert W. Wilson.
United States Patent |
3,664,034 |
Wilson |
May 23, 1972 |
TOBACCO BULK CURING SYSTEM WITH IMPROVED CURING AIR FLOW RATE
CONTROL
Abstract
A system of curing flue-cured tobacco in bulk including a barn
structure having perforated floor defining a curing air inlet space
therebelow and tobacco loading and curing space thereabove for
receiving and supporting a plurality of bulk curing racks disposed
in side-by-side relation and in a plurality of vertically spaced
tiers, a return air space above the loading space and a curing air
conditioning and circulating assembly including a housing having an
inlet communicating with the upper return air space, an outlet
communicating with the lower curing air space, damper controlled
fresh air inlets adjacent the upper end thereof, an air heater, a
blower and an improved air throttling mechanism for controlling the
amount of curing air circulated throughout the cure so that (1) the
yellowing of the leaves is accomplished with the curing air at the
desired temperature and relative humidity flowing at a relatively
slow rate within an operative range of between 10 and 50 cubic feet
per minute for each square foot of effective curing area, and
within a preferred range of 40 to 45 cfm and (2) drying of the
leaves is accomplished with the curing air at the desired
temperatures and relative humidities flowing at a relatively high
rate within an operative range of 50 to 120 cfm for each square
foot of effective curing area with an increase of at least 10
percent of the flow rate during yellowing and within a preferred
range of 55 to 75 cfm and an increase of at least 30 percent.
Inventors: |
Wilson; Robert W. (Charlotte,
NC) |
Assignee: |
R. H. Bouligny, Inc.
(Charlotte, NC)
|
Family
ID: |
22120987 |
Appl.
No.: |
05/074,678 |
Filed: |
September 23, 1970 |
Current U.S.
Class: |
34/225; 432/222;
131/303; 432/500 |
Current CPC
Class: |
A24B
1/02 (20130101); Y10S 432/50 (20130101) |
Current International
Class: |
A24B
1/02 (20060101); A24B 1/00 (20060101); A24b
001/02 () |
Field of
Search: |
;263/19D ;34/225,219D,54
;131/140 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Matteson; Frederick L.
Assistant Examiner: Ramey; Harry B.
Claims
I CLAIM:
1. An apparatus for bulk curing tobacco comprising a plurality of
bulk curing racks, each of said racks including means for receiving
and supporting a multiplicity of tobacco leaves in initially
compressed bulk form, a barn structure comprising means defining a
curing air inlet space, a return air space and a vertically
confined tobacco loading and curing space therebetween, means
within said loading and curing space for receiving and supporting a
plurality of bulk curing racks therein in a position with respect
to the leaves supported thereby so that the flat surfaces thereof
extend generally vertically and with respect to each other so as to
form vertically spaced tiers of leaves horizontally filling said
loading and curing space throughout an effective horizontal curing
area, housing means within said barn structure defining a
circulatory curing air flow path extending from said housing means
to said air inlet space vertically therefrom through said tobacco
loading and curing space and then through said return air space
back to said housing means, said housing means having an inlet
opening communicating with said return air space, fresh air inlet
opening means communicating with said circulatory path adjacent
said inlet opening, damper means mounted within said fresh air
inlet opening means for movement into different positions
controlling the amount of fresh air flowing inwardly into said
circulatory path through said fresh air inlet opening means, air
exhaust means communicating said circulatory path with the
atmosphere for discharging a quantity of curing air from the flow
path generally equal to the amount of fresh air flowing through
said fresh air opening means in accordance with the position of
movement of said damper means, heating means within said housing
means downstream from said fresh air inlet opening means for
controllably heating the air in said circulatory path, blower means
within said housing means downstream from said fresh air inlet
opening means rotatable to establish a flow of air in said
circulatory path, constant speed motor means operatively connected
with said blower means for continuously rotating the same, and air
flow throttling means mounted within said housing downstream of
said fresh air inlet opening means for movement into (1) a flow
restricting position wherein said blower means is operable to
establish a flow of curing air within said circulatory path at a
rate of between 10 to 50 cfm per square foot of said effective
horizontal curing area for curing the tobacco supported in said
loading and curing space through an initial yellowing stage without
premature drying or bruising and (2) a substantially unrestricted
flow position wherein said blower means is operable to establish a
flow of curing air within said circulatory path at a rate of
between 50 to 120 cfm per square foot of effective horizontal
curing area with an increase of at least 10 percent of the flow
rate during the initial yellowing stage for curing the tobacco
within the loading and curing space through subsequent leaf drying
and stem drying stages efficiently in terms of time.
2. Apparatus as defined in claim 1
wherein said throttling means comprises damper means mounted within
said housing means between said fresh air inlet opening means and
said blower means for movement into said flow restricting position
and said substantially unrestricted flow position.
3. Apparatus as defined in claim 2
wherein said throttling means includes an actuating lever
operatively connected with said damper means for effecting movement
of the latter and releasable latching means for releasably
maintaining said actuating lever in positions corresponding with
the flow restricting position and unrestricted flow position
respectively of said damper means.
4. Apparatus as defined in claim 3
wherein said adjustable throttling means further includes means
cooperating with said releasable latching means for releasably
retaining said damper means within a plurality of positions
intermediate said flow restricting position and said substantially
unrestricted flow position.
5. Apparatus as defined in claim 1 wherein
said housing means comprises a vertically extending housing of
generally rectangular horizontal cross-sectional configuration and
wherein said blower means includes a squirrrel cage blower mounted
within the lower end portion of said housing for rotational
movement about a horizontally extending axis and a casing
surrounding said rotor having axial inlet openings on opposite
sides of said rotor and a tangentially extending outlet opening,
said throttling means comprising a pair of pivotally mounted damper
means mounted within opposite sides of said housing in generally
horizontally extending parallel relation in a position between the
inlet openings of said blower casing and the upper end of said
blower casing.
Description
This invention relates to the curing of tobacco and more
particularly to the bulk curing of flue-cured tobacco.
The type of tobacco known as bright leaf or Virginia tobacco is
cured in curing barns by means of heated air in a period of time of
about 6 days. This type of tobacco is also known in the trade as
flue-cured tobacco and is distinguished from other types of tobacco
cured by essentially different processes as, for example,
fire-cured and air-cured tobacco.
The procedures utilized in flue-curing before the introduction of
bulk curing in 1960 (see Hassler U.S. Pat. no. 3,110,326, dated
Nov. 12, 1963) are now referred to as conventional curing. These
procedures usually involved the initial stringing of the tobacco
leaves on sticks in small groups, sometimes referred to as hands.
The strung tobacco sticks are individually supported on tier poles
within the barn. With this conventional procedure, heaters are
mounted in the bottom of the barn to heat the air and establish a
chimney effect flow upwardly past the leaves and out the top of the
barn.
The advent of bulk curing greatly reduced the amount of labor
required in handling the tobacco leaves during the curing operation
by eliminating the stringing procedures. Instead of stringing the
tobacco on sticks, the leaves are loaded in mass within bulk curing
racks which hold the tobacco in a generally compacted bulk mass
with the flat surfaces of the leaves extending generally in a
vertical direction. Bulk curing required the provision of a fan or
blower operable to effect a forced flow of curing air through the
leaves supported within the bulk curing racks.
In my earlier U.S. Pat. No. 3,134,583, dated May 26, 1964, there is
disclosed a dual blower system for separately yellowing and drying
tobacco in bulk. However, commercial bulk curing systems which have
been used since the advent of bulk curing have all utilized a
blower or fan operable to establish an essentially constant curing
air flow rate through the tobacco during the entire curing
process.
It has been found that the utilization of a constant flow rate
results in certain disadvantages in the curing operation. If the
rate of flow of the curing air is established at a relatively high
value, the time required to accomplish the drying steps can be
minimized, but all too often the quality of the cure is
detrimentally affected because of premature drying during the
yellowing stage. Premature drying prevents the tobacco from
reaching its most desirable yellow color and prematurely stops the
chemical reactions within the leaves before all of the desirable
reactions have taken place. Moreover, leaf fluttering may occur at
relatively high flow rates, resulting in bruising of the leaf and
hence detrimentally affecting the quality of the cured leaf. On the
other hand, where the flow rate is maintained constant at a
relatively low value to insure proper yellowing, the drying stages
are unduly prolonged, thus diminishing the overall efficiency of
the equipment.
Accordingly, it is an object of the present invention to provide a
bulk curing system of the type described having improved means for
establishing a relatively low flow rate of the curing air for
accomplishing the yellow stage of the curing process and a
relatively high flow rate for accomplishing the leaf and stem
drying stages of the curing process.
Another object of the present invention is the provision of a flow
rate throttling means of the type described in a bulk curing
apparatus which is simple in construction and operation and
economical to manufacture and maintain.
These and other objects of the present invention will become more
apparent during the course of the following detailed description
and appended claims.
The invention may best be understood with reference to the
accompanying drawings wherein an illustrative embodiment is
shown.
In the drawings:
FIG. 1 is a perspective view of a tobacco curing apparatus
embodying the principles of the present invention;
FIG. 2 is a fragmentary perspective view of the air conditioning
and circulating assembly of the present invention with parts broken
away for purposes of clearer illustration;
FIG. 3 is a fragmentary sectional view taken along line 3--3 of
FIG. 2;
FIG. 4 is an enlarged fragmentary front elevational view of the
curing air flow rate throttling means; and
FIG. 5 is a fragmentary sectional view taken along the line 5--5 of
FIG. 4.
Referring now more particularly to FIG. 1 of the drawings, there is
shown therein a tobacco curing apparatus, generally indicated at
10, embodying the principles of the present invention. In general,
the apparatus 10 includes a curing barn structure, generally
indicated at 12, constructed in accordance with the teachings of
Hassler U.S. Pat. No. 3,110,326, the disclosure of which is hereby
incorporated by reference into this specification; and in
accordance with the teachings of the aforesaid Wilson patent, the
disclosure of which is hereby incorporated by reference into the
present specification.
The curing barn structure 12 is adapted to receive and support a
plurality of bulk curing racks, generally indicated at 14,
constructed in accordance with the teachings of my aforesaid patent
and in accordance with my later U.S. Pat. No. 3,244,445, dated Apr.
5, 1966, the disclosure of which together with my earlier patent is
hereby incorporated by reference into the present specification. As
stated in the aforesaid Wilson and Hassler patents, each of the
bulk curing racks 14 is operable to support a multiplicity of
tobacco leaves within the barn structure 12 for curing by the
passage of curing air vertically therethrough.
As best shown in FIGS. 2 and 3, the apparatus 10 includes a curing
air conditioning and circulating assembly, generally indicated at
16, constructed in accordance with the principles of the present
invention. In general, the assembly 16 is operable to establish a
forced flow of heated air upwardly through the leaves carried by
the bulk curing racks within the curing barn 12 to effect cure of
the leaves.
The principles of the present invention can be adequately
understood without a description of the details of the curing barn
structure 12. Reference may be had to the aforesaid Hassler U.S.
Pat. No. 3,110,326, and Wilson U.S. Pat. No. 3,134,583, for these
details. For present purposes, it is important merely to note that
the curing barn structure provides one or more curing compartments
20, there being three such compartments provided in the barn
structure shown in FIG. 1. The three curing compartments 20 are
disposed in side-by-side relation with the outermost compartments
extending the full depth of the barn structure and the central
compartment being of lesser length so as to provide an area,
generally indicated at 22 in FIG. 3, disposed rearwardly of the
central compartment and between the rear end portions of the outer
compartments within which the curing air conditioning and
circulating assembly 16 is mounted.
Each of the curing compartments 20 is provided with rack supporting
rails 24 which, as best shown in FIG. 3, are disposed three
vertically spaced, horizontally aligned pairs on opposite sides of
each compartment. The curing compartments define a tobacco loading
and curing space through which the curing air passes vertically
upwardly. It will be understood that while a vertically upwardly
flow is preferred, a vertically downward flow may be utilized if
desired.
Each horizontally aligned pair of rails 24 slidably receives and
supports a plurality of bulk curing racks 14. Here again, the
details of construction of the bulk curing racks 14 need not be
described in order to understand the principles of the present
invention. References may be had to the disclosures contained in
the aforesaid Wilson patents for these details. For present
purposes, it is sufficient to indicate that each rack includes a
pair of complementary rack sections 26 separable to permit the
loading of a multiplicity of tobacco leaves therebetween, and
movable together to retain the loaded leaves therein. Each rack
also includes a plurality of elongated spikes or prongs 28 which
serves to pierce the tobacco leaves when the rack sections are
moved together and to provide for interior support of the
multiplicity of leaves secured within the rack during curing. The
rack sections provide for peripheral support of the multiplicity of
leaves when the rack sections are secured together, such peripheral
support retaining the leaves together in an initially compressed
condition in the manner described in the aforesaid Hassler
patent.
The racks are of a size complementary to the curing chambers 20 so
that when a plurality of such racks is supported on the rails 24
within each curing compartment 20 the leaves to be cured are
supported for curing in three vertically spaced compact beds of
leaves which uniformly fill the curing compartment in such a way as
to insure that the curing air will pass through the leaves of the
beds in series.
The present invention is more particularly concerned with
improvements in the curing air conditioning and circulating
assembly 16, operable to provide effective control of the rate of
air flow through the tobacco supported by the racks 14 within the
compartments 20 of the apparatus 10 during the curing process. The
assembly 16 comprises certain known components including a
vertically extending main housing 30 of conventional skeletonized
frame and sheet metal construction mounted within the area 22 and
forming a part of an endless circulatory curing air flow path
which, for convenience, can be described as commencing with an
inlet opening 32 defined by the upper end of the housing 30 and
extends therefrom in the direction of flow downwardly through the
housing 30 to a discharge or outlet opening 34 formed in an
imperforate floor structure 36 defining the lower surface of the
area 22. From the discharge opening 34 the air flows into an inlet
space 38 which communicates with the curing compartments through
perforated floor structures, generally indicated at 40. If desired,
vanes (not shown) may be provided within the space 38 adjacent the
outlet opening 34 for the purpose of insuring an even distribution
of the air to the floor structure associated with each
compartment.
Each floor structure 40 is preferably of perforated metal
construction, such as expanded metal or the like, in accordance
with conventional practice, which renders the apparatus suitable
for drying other crops, although it will be understood that other
floor structures may be provided if desired, as for example, spaced
wooden slats or the like. Moreover, it will be understood that the
apparatus 10 will operate to cure tobacco without the provision of
a floor structure 40. The floor is a definite convenience during
loading and unloading and renders the apparatus capable of being
conveniently used for drying other crops.
The floor structures define the lower surface of the tobacco
loading compartments through which the curing air flows vertically
upwardly. The upper end of the curing compartments freely
communicate with an upper return air space 42 defined along its
upper surface by the roof of the barn structure. The endless curing
air flow path is completed by communicating the upper space 42 with
the upper inlet opening 32 of the housing 30 as by a roof structure
44 which defines the upper surface of the area 22.
The temperature of the curing air is controlled by means of a
burner unit, generally indicated at 46. The burner unit as shown is
gas fired, and may be of any conventional construction, either oil
or gas fired. As shown, the burner unit communicates directly with
the interior of the housing so that the products of combustion pass
into the curing air. Such an arrangement is preferable with a gas
fired burner unit. On the other hand, it is preferable where an oil
fired burner unit is employed to discharge the products of
combustion through a separate chimney or stack and to heat the air
through a suitable heat exchanger, all in accordance with
conventional practice. It will be understood that the burner unit
is preferably provided with suitable controls (not shown) such as a
thermostat or the like for effecting operation thereof in
accordance with conventional practice.
In order to control the relative humidity of the curing air, the
housing 30 is formed with fresh air inlet means 48 which, as shown,
is in the form of two rectangular openings, one on each side of the
housing adjacent the upper end thereof. The amount of fresh air
introduced into the flow path is controlled by a damper member 50
movably mounted within each fresh air inlet opening 48, the two
dampers being interconnected for movement together by a lever and
connecting rod assembly 51 of generally conventional construction.
When the damper members 50 are adjusted to permit the introduction
of fresh air through the inlet openings 48 additional air is
supplied to the system and, for the purpose of permitting the
discharge of a generally corresponding amount of air from the
circulatory path, there is provided a pair of louvre units 52 which
forms a part of the overall damper means for controlling the
introduction and exhaust of air into and out of the circulatory
path of flow.
As best shown in FIG. 1, the louver units 52 are mounted in the
front wall of the barn structure in communication with the upper
portion of the barn. The units are of the type adapted to open
outwardly in response to a predetermined air pressure in the upper
portion of the barn structure. Thus, the louver units 52 will
remain closed when the fresh air inlets are closed so that the
entire system is effectively closed and the curing air will merely
recirculate in the circulatory path. When fresh air is allowed to
be introduced through the inlet openings 48, the pressure will
build up in the upper portion of the barn structure resulting in
the exhaust of air in the circulatory path of flow outwardly to the
atmosphere through the louver units 52. The louver units thus serve
to permit a discharge of air from the circulatory path commensurate
with the amount of fresh air introduced to the circulatory
path.
While the damper means described above is preferred, it will be
understood that the essential characteristic for the control of
relative humidity is to have a fresh air inlet opening and an
outlet opening for the discharge of circulating air and a
controllable damper unit associate with at least one of the
openings. For example, louver unit 52 could simply be eliminated
leaving the discharge outlet open or louver unit 52 could be
controlled in lieu of damper means 50 and the latter could be
either eliminated or replaced with a unit, such as louver unit
52.
It will be understood that the fresh air inlet damper means as well
as the thermostat controls of the burner unit may be automatically
operated as, for example, by the control mechanism disclosed in my
U.S. Pat. No. 3,503,137, dated Mar. 31, 1970, as well as other
types of automatic as well as semi-automatic control mechanisms
known in the art.
The circulation of curing air within the flow path is provided by a
rotatable fan or blower, generally indicated at 54, mounted within
the housing 30 with its suction side downstream from the fresh air
inlet openings 48. As shown, the fan or blower is of the squirrel
cage type, having a rotor blade assembly 56 mounted on a horizontal
shaft 58 suitably journaled within the housing 30 surrounded by a
casing 60 providing axial inlet openings 62 spaced from the
adjacent wall of the housing 30 and a generally tangential outlet
64 connected with the outlet opening 34 in the floor structure 36.
As best shown in FIG. 2, one end of the shaft 58 extending
outwardly of the housing 30 is connected with a driving motor 66,
as by a belt and pulley assembly 68. In accordance with
conventional practice, the motor 66 is preferably an electrical
motor of suitable horsepower as, for example, 71/2 horsepower, with
an operating rpm of 1725, the belt and pulley assembly 68 being
operable to reduce the output rpm of the electric motor to an
exemplary 625 rpm of the blower rotor blade assembly 56.
It will be understood that other types of blowers may be utilized,
as for example, radial blade fans and the like. The preferred power
driven blower exemplified above has a rated capacity capable of
establishing a continuous operational flow through the discharge
opening 64 of approximately 16,500 cfm at the end of the drying
procedure. The rated capacity of the fan is determined at the end
of the cure because the fan is operating more nearly at its maximum
capacity at this time. It will be understood that a relatively
small change in cfm output will occur because of the changing
resistance to flow offered by the leaves as they diminish in size
during the cure due to loss of moisture.
The rated capacity of the fan is given only as an example and is
related to the specific air flow requirements of the exemplary barn
structure herein disclosed. In general, the air flow requirements
can most conveniently be expressed in terms of a cubic feet per
minute flow per square foot of effective curing area provided by
the apparatus. The effective curing area of the apparatus is herein
defined as the horizontal cross-sectional open area (i.e. between
the rails 24) of all compartments 20 less the cross-sectional area
therein assumed by the rack section structure in one tier or the
cross-sectional area within which the leaves of one tier are
confined. The effective curing area is determined by the leaf
confining area in one tier only for the reason that the same curing
air passes through the leaves in each tier regardless of whether
there are two, three or more. The effective curing area of the
exemplary barn structure referred to above is approximately 257
square feet.
In accordance with the principles of the present invention, the
rated capacity of the motor driven fan 54 is chosen at a value
within an operative range of between 50 cfm and 120 cfm for each
square foot of effective curing area. A preferred range is from 55
cfm to 75 cfm and the preferred example enumerated above is about
65 cfm per square foot of curing area.
In accordance with the principles of the present invention, the
rated flow rate of the fan is utilized only during the later leaf
drying and stem drying stages of the curing process. It has been
found that the preferred operative range provides efficient drying
within a minimum time period but that such rate of flow when
utilized during the initial yellowing stage of the curing process
will detrimentally affect the quality of the cure. Where a constant
flow rate within this operative range is utilized throughout the
curing process, it has been found that the time required to effect
drying is reduced as the constant air flow rate utilized is
increased within the range but the quality of the yellowing
decreases. This decrease in the quality of the leaf yellowing is
due to premature drying toward the end of the yellowing stage,
which results in setting the color at a point before the full
desired yellowing takes place and stopping the chemical reaction
within the leaf before the desired extend of chemical reaction has
been completed. Moreover, at the relatively higher constant rates
of flow, leaf fluttering during the yellowing stage can occur,
resulting in leaf bruising and hence a deteriorating effect on the
quality of the cured leaf.
In accordance with the principles of the present invention, the
curing air controlling and circulating assembly 16 is provided with
means for throttling the rate of air flow established by the fan
54. To this end, with the embodiment shown, there is provided a
pair of movable damper members 70 mounted within the housing 30 in
a position upstream from the fan casing inlet openings 62 and
downstream from the fresh air inlet openings 48. As best shown in
FIGS. 4 and 5, each damper member 70 is formed from a rectangular
piece of sheet metal having its longitudinal edges bent in parallel
directions. Each damper member is fixedly secured to a shaft 72,
preferably in the form of a hollow tubular member, as by a pair of
angular end brackets 74 and a central plate 76 suitably welded to
the damper member 70 and the tubular shaft. The ends of each shaft
72 are suitably journaled within appropriate bearings 78 carried by
the adjacent frame and walls of the housing 30, the shaft end at
the front wall adjacent the left side of the housing extending
outwardly through an opening formed in a dial plate 80 fixed to the
outer surface of the adjacent wall of the housing.
As best shown in FIG. 4, the dial plate 80 includes a plurality of
openings 82 which, as shown, are seven in number, equally spaced
arcuately about the axis of the shaft 72. A sleeve 84 is detachably
rigidly secured to the protruding end of the shaft and has an
actuating lever 86 fixedly secured thereto and extending radially
outwardly from the outer end thereof. An L-shaped strap member 88
is rigidly connected, as by welding or the like, between an outer
end portion of the lever and the inner end portion of the sleeve
84. The lever and strap are formed with registering openings for
receiving a latch pin 90, the inner end of which is adapted to
selectively engage within one of the openings 82 in the dial plate
80. The latch pin 90 is spring urged in a direction to engage
within the openings as by a coil spring 92 disposed in surrounding
engagement with the pin with one end in engagement with the
adjacent surface of the lever and the opposite end in engagement
with a cotter key or the like extending through the pin. The outer
end of the latch pin includes a handle portion 94 by which the
operator effects manual movement of the pin outwardly of the
openings 82, against the action of the spring 92, permitting manual
movement of the lever 86 into any desired position of adjustment.
Movement of the damper member 70 associated with the manual lever
86 is transmitted to the other damper member 70 by means of a
connecting rod 96 pivoted at one end to the lever 86, as indicated
at 98 and at its other end to the outer end of an actuating arm
100, the inner end of which is fixed to the associated shaft
72.
It will be noted that when the actuating lever 86 is moved between
its limiting positions defined by the outermost openings 82, the
damper members 70 will be moved from a horizontal to a vertical
position within the housing. With the dampers in their vertical
position, the flow rate of the fan 54 is substantially at its rated
capacity. It will be noted however, that when the damper members 70
are disposed in their horizontal position, the area of the flow
path to the fan casing inlet openings 62 is diminished, being
restricted to the flow past the ends of the vertically disposed
damper members 70 on opposite sides of the fan casing ends. In this
way, the rate of air flow of the fan 54 is throttled down to an
operative range of from 10 cfm to 50 cfm for each square foot of
effective curing area. A preferred range is from 40 cfm to 45 cfm
and in the exemplary embodiment described, an approximately 45 cfm
rate of flow is established. The throttled down operative range of
flow rates is utilized during the yellowing stage of the curing
process, the flow rate utilized within the operative range being
increased at least 10 percent during the subsequent drying stages
in the curing process. Where the flow rate utilized is within the
preferred range, the increased flow rate during the drying stages
is at least 30 percent and in the specific example the increase is
from 45 cfm to 65 cfm or approximately 45 percent. It will be
understood that while the throttling damper members 70 are shown as
being preferably positioned on the suction side of the fan, it is
within the contemplation of the present invention to position the
throttling damper members on the pressure side of the fan means as
well.
From the above it is evident that in the normal operation of the
present apparatus, the operator should adjust the actuating lever
86 at the start of the yellowing stage of the curing process so
that the damper members 70 are disposed in their horizontal
position. The curing can then proceed through the yellowing stage
utilizing temperature and relative humidities such as disclosed in
my U.S. Pat. No. 3,503,137. At the end of the yellowing stage, the
operator then moves the actuating lever 86 so that the damper
members 70 are disposed in their vertical positions and the leaf
drying, stem drying and ordering procedures are then carried out
utilizing temperatures and relative humidities such as disclosed in
my U.S. Pat. No. 3,503,137. It will be understood that where an
automatic control mechanism, such as disclosed in my U.S. Pat. No
3,503,137 is utilized, the air flow throttling damper members 70
may be connected with an actuating solenoid which is interconnected
within the control circuit so as to be actuated or deactuated at
the appropriate time during the curing cycle (i.e. at the end of
the yellowing stage).
It will also be understood that with the seven positions of
adjustment provided by the adjusting mechanism shown, the operator
may utilize flow rates both for yellowing and drying which are
intermediate the minimum and maximum flow rates. These seven
positions designate flow rates from 45 to 65 cfm in the
illustrative embodiment shown at increments of 31/3 cfm. This range
of adjustability is particularly advantageous when the apparatus is
utilized, without the bulk curing racks 14, to dry other crops,
such as grain, corn, peanuts and the like. The adjustment provided
affords the operator a simple means by which the most desirable
drying flow rate for each crop can be utilized.
It thus will be seen that the objects of this invention have been
fully and effectively accomplished. It will be realized, however,
that the foregoing specific embodiment has been shown and described
only for the purpose of illustrating the principles of this
invention and is subject to extensive change without departure from
such principles.
* * * * *