CA1090562A - Grain drying bin - Google Patents
Grain drying binInfo
- Publication number
- CA1090562A CA1090562A CA340,270A CA340270A CA1090562A CA 1090562 A CA1090562 A CA 1090562A CA 340270 A CA340270 A CA 340270A CA 1090562 A CA1090562 A CA 1090562A
- Authority
- CA
- Canada
- Prior art keywords
- plenum chamber
- air
- bin
- grain
- grain drying
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Abstract
ABSTRACT OF THE DISCLOSURE
A novel grain drying bin is provided herein which is of the type having a plenum chamber formed in the lower part thereof, and a gas-pervious floor forming the top of the plenum chamber. Such grain drying bin includes means for introducing atmospheric air into the plenum chamber, and electrical heating means for adding heat energy to the air in the plenum chamber, the electrical heating means including a plurality of heat lamps mounted on the lower part of the bin adjacent the plenum chamber.
The grain drying bin has a setting which is selectively controllable to accommodate the hygroscopic properties of differing seeds and variations of seasonal temperatures and humidities.
A novel grain drying bin is provided herein which is of the type having a plenum chamber formed in the lower part thereof, and a gas-pervious floor forming the top of the plenum chamber. Such grain drying bin includes means for introducing atmospheric air into the plenum chamber, and electrical heating means for adding heat energy to the air in the plenum chamber, the electrical heating means including a plurality of heat lamps mounted on the lower part of the bin adjacent the plenum chamber.
The grain drying bin has a setting which is selectively controllable to accommodate the hygroscopic properties of differing seeds and variations of seasonal temperatures and humidities.
Description
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This invention relates to a grain drying bln for controlling the drying and cooling of field-harvested seeds in storage. This application is a division of application Serial No. 238,392 filed October 27, 1975.
The technique of early harvesting including field shelling and subsequent conditioning of corn and other cereal grains in storage is becoming increaslngly popular. The present methods of conditioning or drying these cereal grains range from simply storing the seeds and letting them dry in the atmosphere, to placing them in drying bins and passing heated air through the grain seeds. In more recent years, complicated mechanical devices for agitating the stored grain or for removing the bottom-most layer of stored grain have increased equipment and operational expenses and severely damaged both the phyRical and food properties of the grains and not infrequently the storage structure itself.
Grain exposed by storing in atmospheric air frequently is inadequately driet. In most cases, the drying process is so slow that problems of mold and biochemical changes result in serious losses to the Etored grain. Also, drying of this type is interruptet by undesirable weather conditions,~e.g., high humidity or prolonged wet and rainy periods, both of which result in accelerated degradation of the stored grain.
Wet graln that is artificially dried by flow of heated air in a drying bin i8 frequently damaged due to the fact that commercial drying techniques often use drying air temperatures from 100F. to 140F., and sometimes even as high as 200F., with resultant destruction of enzymes and amino acid proteins and other volatile ingredients.
The early harvesting techniques used in producing corn today frequently involve field shelling of the corn when it is at a moisture content of 27X. At this moisture level, grain deteriorates rapidaly and becomes mold infested. Corn approaches physiological maturity when its moisture content is 20%. The maturing process involves not only the re-moval of moisture, but also chemical stabilization. Because mature corn B
--` lO90S6Z
is more stable, it may be stored ~afely over long periods under proper con-ditions while storing of corn with excessive isture inhibits or even prevents the natural occurrence of biological maturity. Maturing involves the chemical stabilization of starch and protein which constitutes 85~ of the corn kernel. In the maturing process, sugar molecules bond together to form starch molecules which are more complex carbohydrates and are more stable chemically. Similar processes are involved with proteins and amino acids. In these processes water is eliminated, and thus drying or the elimination of water is an essential aspect of maturing of grain. Tempera-ture and moisture are both factors in grain stabilization; however, abovecertain isture levels, chilling of grain does not prevent deterioration of the seed. The following table shows germination loss in stored, refrigerated corn.
; GERMINATION LOSS IN STORED, REPR~GERATED CORN
GERMINATION- EMERGENCE*
MOISTURE AFTER 6 MOS.: APTER 18 MOS, AFTER 6 MOS. AFTER 18 MOS.;
Above 24% 17X 0% 0% 0Z
18 - 24% 4ZX 13X 33% 53%
16 - 18% 74% 71% 59% 88%
14 - 16% 70% 73% 56X 86%
12 - 14% 75% 75% 47% 93 10 - 12% 65Z 69% 70% 91%
Under 10% 74% 73% 75% 84Z
AVERAGE56.5% 82.5 Storage temperature approximately 35~F.
*Percentage Emergence within`five days of plantlng
This invention relates to a grain drying bln for controlling the drying and cooling of field-harvested seeds in storage. This application is a division of application Serial No. 238,392 filed October 27, 1975.
The technique of early harvesting including field shelling and subsequent conditioning of corn and other cereal grains in storage is becoming increaslngly popular. The present methods of conditioning or drying these cereal grains range from simply storing the seeds and letting them dry in the atmosphere, to placing them in drying bins and passing heated air through the grain seeds. In more recent years, complicated mechanical devices for agitating the stored grain or for removing the bottom-most layer of stored grain have increased equipment and operational expenses and severely damaged both the phyRical and food properties of the grains and not infrequently the storage structure itself.
Grain exposed by storing in atmospheric air frequently is inadequately driet. In most cases, the drying process is so slow that problems of mold and biochemical changes result in serious losses to the Etored grain. Also, drying of this type is interruptet by undesirable weather conditions,~e.g., high humidity or prolonged wet and rainy periods, both of which result in accelerated degradation of the stored grain.
Wet graln that is artificially dried by flow of heated air in a drying bin i8 frequently damaged due to the fact that commercial drying techniques often use drying air temperatures from 100F. to 140F., and sometimes even as high as 200F., with resultant destruction of enzymes and amino acid proteins and other volatile ingredients.
The early harvesting techniques used in producing corn today frequently involve field shelling of the corn when it is at a moisture content of 27X. At this moisture level, grain deteriorates rapidaly and becomes mold infested. Corn approaches physiological maturity when its moisture content is 20%. The maturing process involves not only the re-moval of moisture, but also chemical stabilization. Because mature corn B
--` lO90S6Z
is more stable, it may be stored ~afely over long periods under proper con-ditions while storing of corn with excessive isture inhibits or even prevents the natural occurrence of biological maturity. Maturing involves the chemical stabilization of starch and protein which constitutes 85~ of the corn kernel. In the maturing process, sugar molecules bond together to form starch molecules which are more complex carbohydrates and are more stable chemically. Similar processes are involved with proteins and amino acids. In these processes water is eliminated, and thus drying or the elimination of water is an essential aspect of maturing of grain. Tempera-ture and moisture are both factors in grain stabilization; however, abovecertain isture levels, chilling of grain does not prevent deterioration of the seed. The following table shows germination loss in stored, refrigerated corn.
; GERMINATION LOSS IN STORED, REPR~GERATED CORN
GERMINATION- EMERGENCE*
MOISTURE AFTER 6 MOS.: APTER 18 MOS, AFTER 6 MOS. AFTER 18 MOS.;
Above 24% 17X 0% 0% 0Z
18 - 24% 4ZX 13X 33% 53%
16 - 18% 74% 71% 59% 88%
14 - 16% 70% 73% 56X 86%
12 - 14% 75% 75% 47% 93 10 - 12% 65Z 69% 70% 91%
Under 10% 74% 73% 75% 84Z
AVERAGE56.5% 82.5 Storage temperature approximately 35~F.
*Percentage Emergence within`five days of plantlng
- 2 -It is not uncommon for the drying air used in conventional pro-cesses to be at a temperature of 110F. to 140F., and occasionally even higher, e.g., up to 200F. It would seem that such temperatures would ~speed drying, but because of the sharp contrast with ambient temperatures as the air approaches the surface, resulting in moisture condensation and blockage to air flow, the drying process is slowed. When the grain is stirred, condensation in bin walls is intensified because of contrasting temperatures, resulting in rusted wall and rotted grain. Destruction of protein, loss of corn oils and other heat-suscepible ingredients can result in as much as five pounds per bushel loss of weight when high heat drying is utilized.
Commonly, hydrocarbon fuels, e.g., propane, are used as a heat source. The combustion of these fuels is associated with the production of water. The BTU per hour output of heaters commonly employed range from 500,000 to 3,000,000 so that the per day production of water as a product of combustion can range from 75 to 500 gallons. This vapour is in the air that goes through the grain.
The seriousness of this problem is attested to by the fact that nearly every drying bin has crusted and sprouting surface grain, overdried bottom grain, rusting of bin walls and rotting of grain.
Present principles and practices of drying stored grain rest on the assumption that obtaining saturated, exhaust air is desirable. In the prior art, specific zones in the grain bulk are referred to, i.e., the dry zone, the drying zone and the wet zone.
Weight losses of 1% of the dry matter have been found to corre-late to a 20% loss of germination, and in today's economy~ such deteriora-tion can amount to as much as 20¢ per bushel loss in value. Since loss of germination means loss of value, it is desirable to maintain maximum germination. Therefore, maximum control provides maximum germination, and the induction of dormancy from the earliest time following the harvest of lO90S62 the grain by exposing the harvested grain to controlled air flow and moisture removal is desirable. Dormancy is a state of retarded respirs-tion; accelerated respiration increases kernel food consumption and weight loss. Respiration is the conversion of_oxygen to carbon diox de (the carbon being derived from the consumed sugar) and is exothermic, i.e., heat is generated. Thus, when high-moisture _orn is exposed to warm saturated air, the rapid development of mold and heating of grain is intensified by the exothermic process of respiration as well as by the external addition of heat.
In the case of excessive differential, overdried grain will result~ if saturated air is obtained, deteriorative conditions are estab-. _ lished. The proces~ of this invention proposes to maximize utilization of natural air, and to maximlze preservation of seed quality and market weight and value. The equilibrium corn moisture obtained during ventilation is shown in the following table.
Si~ilar moisture equilibrium charts can be-prepared for other grains. ~~ ~~~
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,__ ~ E~ ~ 0 ~
C~ H ~ O~
P~ X
P~ ~
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E-~ H 1-/ 0 ~ ~D O ~ u~ I` O
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P ~ O
z~ ~
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P~ ~ O ~ U~
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P ~Y ~~X
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P ~
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X ~1: P E~ ~ ~ ~ ~ a~
E~ ~ ~ H H c~ u~ o u~ 0 0 ~ E~ ~ ~ ~ ~ ~ ~ u H H X ~ X
O ¢ P~ ~ P
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P m a: o 0 ~ ~Y o~
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H O PS H u~ ~t) It) u~ ~ ~ ~ '$ ~S ~ C'~ ~ c~
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X ~ H o ~1 u~ O ~ ~
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~-~ ~ ~ ~ ~ P~ ~ P~ ~ ~ ~ ~ P~ ~ ~ ~
P~ ooooooooooooo Z ~ ~ U~ O U~ O U~ O U~ O U~ o U~ o U~ .
~ ~ ~ 0 P~ ~
lO90S6Z
Accordingly, it is an ob~ect o a broad aspect of this invention to provide a grain drying bin for conditioning grain to controlled dormancy and moisture, and to maximize weight and market value for specific markets while maintaining optimum seed conditions.
It is an ob~ect of a further aspect of this invention to provide a grain drying bin for "cool-drying" grain by reference to the temperature differential between dry-air and wet-air in which the dry-air temperature is automatically regulated and the source of heating the drying air can be inactivated when the difference between the wet-air temperature (exhaust) and the dry-air temperature (plenum) is greater than the preset tolerance, allowing for fluctuations of the plenum-air temperature that occur seasonally.
By one aspect of this invention, a grain drying bin is provided which is of the type having a plenum chamber formed in the lower part thereof and a gas-pervious floor forming the top of the plenum chamber, the grain drying bin comprising: means for introducing atmospheric air into the plenum chamber; and electrical heating means for adding heat energy to the air in the plenum chamber, the electrical heating means including a plurality of heat lamps mounted on the lower part of the bin ad~acent the plenum chamber.
By one variant thereof, the grain drying bin further includes:
means for determining the temperature of air in the plenum chamber; means for determining the temperature of air as it exhausts the bin; thermostat means responsive to the temperature of the air in the plenum chamber for controlling the operation of the meating means; and means, adapted to over-ride the thermostat controlling the heating means and to inactivate the heating means when the temperature difference between the drying air in the plenum chamber and the air exiting the bin is greater than a predetermined amount.
By a variation thereof, the grain drying bin further includes:
a plurality of heat lamps spaced about the bin wall ad~acent the plenum chamber and having a total output of 10 to 40 watts per one hundred bushels of bin capacity.
By another variation, the grain drying bin further includes: a plurality of fans distributed about the wall of the plenum chamber; each fan being individually controlled and including closure means to prevent air from exiting the plenum chamber when the fan is inactivated.
By yet another variation, the grain drying bin further includes transparent heat lamp mounting plates detachably secured to the bin wall.
By a still further variation, the grain drying bin further includes means for indicating the amount of air being introduced into the plenum chamber.
By another variant, the heat lamps emit radiant energy.
By another variant, the heat lamps emit radiant energy in the infrared wavelengths in the electromagnetic spectrum.
By a further aspect of this invention, a grain drying bin is provided which is of the type having a plenum chamber formed in the lower part thereof, a gas-pervious floor forming the top of the plenum chamber and an upstanding plenum chamber wall forming the sides of the plenum chamber, the grain drying bin comprising: means for introducing atmos-pheric air into the plenum chamber, including at least one fan tube attached to the plenum chamber wall; and electrical heating means for adding heat energy to the air in the plenum chamber, the electrical heating means comprising a plurality of heat lamps attached to and spaced around - the plenum chamber wall, the plurality of heat lamps also being spaced i from the fan tube on the plenum chamber wall.
By a variant thereof, the heat lamps include means for emitting infrared rays.
By another variant, the graln drying bin further includes a plurality of fan tubes having fans therein spaced around and attached to _. .
lO90S6Z
the plenum chamber wall, each of the fan tubes and the heat lamps being spaced apart from each other around the plenum chamber wall.
By a further aspect of this invention, a grain drying bin is provided of the type having a plenum chamber formed in the lower part thereof and a gas-pervious floor forming the top of the plenum chamber, the grain drying bin comprising: means for introducing atmospheric air into the plenum chamber; and electrical heating means for adding heat energy to the air in the plenum chamber, the electrical heating means comprising a plurality of heat lamps spaced about the plenum chamber.
According to one embodiment of this invention as now provided by the present Divisional Application, grain to be conditioned or dried is placed in a storage bin, generally of the type having a means for blowing drying air into a plenum chamber below the body of grain to be dried.
The roof of the plenum chamber, which is also the floor of the storage bin, is pervious to gas flow and allows the drying air to percolate up through the body of grain to be dried. Bins of this type are quite common in the prior art, but they usually include a blower furnace as the means for supplying drying air to the bin.
In the present invention as now provided by the present Divi-sional Application, in one of its embodiments,:the drying which is effectedmuch more closely approximates what can be termed natural drying. Specifi-cally, it utilizes a flow of air and a particularly specified heat source which is more controllable and less destructive to the grain than prior art techniques. Strictly natural air drying is not fully adequate to reduce grains to moisture levels safe for long-term storage, due to humidity and temperature conditions that exist in fall and early winter, as noted in the following table.
10~056Z
'~ !
NAT~RAL AIR GRAIN DRYNESS* BY THE MONT~ ~IOWA) AVG. CORN WET-BULB** AVG. CORN WET-BULB** ¦
MOISTUR~ DEPRESSION MOISTUR~ DEPRESSION
Jan.20Z 1 - 2 July 11 1/2% 7 - 10-Feb.l9X 1 - 3 Aug. 12% 7 - 9 March i7% 2 - 5 Sept. 13Z 6 - 8 April 16Z 5o _ 70 Oct. 14Z 5 _ 70 May13 1/2Z 7 - 8 Nov. 16% 3 _ 5 June13 1/2Z 7 - 8 Dec. 19~ 1- - 3-. _ . .
*Varies With Dlfferent Grains; also with varietal and sea-son-l differences.
**Average Mean Wet-Bulb DepreggIong From U.S. Weather Bureau Data.
The grain drying bin of aspects of this invention as now provided by this Divisional Application departs fundamentally from this generally accepted assumption and employs a controlled balance of volume of air flow to grain volume and of air dryness to grain dryness while substantially avoiding the clash of warm grain air temperatures with cool or cold ambient temperatures.l The effect is to maintain a relative humidity in the exhaust air below saturation so that some drying can occur within the entire bulk of grain and thus substantially eliminate the "wet zone" of high-moisture perishable grain exposed to saturated air; accelerated rates of respiration (in the grain itself and in molds and other micro-organisms exposed to warm, humid conditions) that intensify losses of weight and food value are likewise sub-stantially prevented. - j The grain drying bin of aspects of this invention as now provided by this Divisional Application utili~es the fact that as water evaporates from a surface, the surface becomes cool. Therefore, as dry air is passed through the body of moist grain, evaporation takes place and cools the grain air a certain amount; t~he amount of cooling is dependent upon a number of factors, e.g., the particular grain being dried, the temperature of the drying air, the moisture content of the grain, and the relative I
.
humidity o~ the drying air. The effect of eyaporatiye cooling is to render the kernel and micro-organism dormant and thus to stabilize the kernels and micro-organisms. It is a feature of an aspect of this inven-tion as now provided by this Divisional Application that the drying air is not heated to such an extent that the grain can be damaged thereby or overdried. It is desired to approximate as closely as practicable the conditions of natural air drying, and accordingly, the drying air is pre-ferably conditioned only to control its dryness or relative humidity with-out greatly raising it above ambient temperatures.
The temperature of the plenum air is controlled, e.g., by a thermostat or other similar modulating or cycling device. According to one aspect of the invention as now provided by this Divisional Application, the temperature differential between plenum air and exhaust air is moni-tored, and the specified heating means is inactivated when the differential exceeds a preselected value.
Specifically, according to an aspect of this invention as now provided by this Divisional Application, a controlled flow of ideal, natural "harvest air" is maintained within the stored grain with an apparatus for measuring and controlling natural air dryness or relative humidity so as to control grain dryness and dormancy. The addition of dry energy (heat) to the drying air is selectively controllable so as to determine the extent of drying that can occur within the grain. This is accomplished by obtaining a measure of the "dry-bulk" temperature and the "wet-bulb" temperature depression that occurs within the grain with the addition of heat only when the wet-bulb depression is less than the pre-determined tolerance.
Since only a small rise in temperatu~e of the drying air is required in the use of the grain drying bin of an aspect of this invention as now provided by this Divisional Application, electrical heating means are ideally suited, and because of their extraordinary safety, convenience --.10 --lO90S62 and serviceability, heat lamps are preferred as a means for heating the drying air. Heat lamps distributed about the plenum chamber uniformly warm metal floor and floor supports, giving good distribution of the added heat. The exceptional economies of light energy as a heat source are well known.
Additionally, radiant heat energy from electrical sources is totaly dry energy and does not aggravate problems of moisture condensation as does the combustion of hydrocarbon fuels.
In summary, the grain drying bin of aspects of this invention as now provided by this Divisional Application provides that, because of the sensitive nature of seeds and other products with similar sensitivities, the application of heat as used in conventional drying of non-living pro-ducts is excessive and intolerably damaging, and that preservation of weight and food value in grain is accomplished only in preserving the biological integrity of the seed.
Further, even when drying is accomplished with low levels of heat, these can be excessive because of the adverse environment created by the heat in increasing seed respiration and in causing stratification of moisture within the grain which allows for mold infestation.
Because of high costs of energy and limitations of energy resourc~s, their wise management, especially in drying grains, is obviously urgent because of the vast expenditure of energy resulting from the growing practice of drying food grains.
More specifically, this invention in another of its aspects as now provided by this Divisional Application includes a grain drying bin operated in such a way that the biological integrity or living character of biological products, especially food grains, is preserved by drying, chilling and conditioning in a controlled storage environment. Such con-trol of storage environment is by ventilation, which maintains a balanced ratio of air-volume to grain-volume, and which substantially prevents stagnation of and accumulation of moisture in the interstitial grain-air.
Throughout the conditioning process inherent in the use of the apparatus of aspects of this invention as now provided by this Divisional Applica-tion, the temperature of the product in storage remains colder than ambient temperatures and that when the product has achieved the desired equilibrium moisture, it is at the same temperature as the ambient air.
Furthermore, monitoring means indicate the extent of heat expen-diture or evaporative cooling during ventilation, i.e., the differential temperature observéd from the time the air enters the grain to the time it exhausts, thereby providing direct indication of equilibrium moisture being achieved within the grain at any time. Control means are provided which automatically activate or deactivate heat sources in response to evapora-tive cooling and make possible the selective control of moisture content in the grain by selective control of differential temperatures.
In the accompanying drawings, Figure 1 is a side elevation view, partically cut away, showing a grain bin equipped according to one aspect of this invention;
Figure 2 is an exploded view showing the details of heat lamp mountings according to one aspect of the invention;
Figure 3 is a front elevation view showing a control panel for use in accordance with one aspect of this invention;
Figure 4 shows a schçmatic operational circuit diagram for the operation of the grain bin of one embodiment of the in~ention;
Figure 5 shows a schematic opërational circuit diagram for the operation of the grain bin of another embodiment of the invention; and Figure 6 is a partial perspective view of the interior bottom of the grain bin equipped with a multiple fan arrangement according to one aspect of this invention, with certain portions removed for clarity.
According to one embodiment of this invention as now provided by this Divisional Application, a grain drying bin is now provided which has !
~ 1090S6Z
the ability to produce grain having precisely controlled levels of moisture and also provides that these levels are obtained in a manner which results in minimum germination loss of the grain with resultant maximum quality for ultimate use. Some processing techniques require specific moisture levels, and the ability to supply grain with these specific levels will produce competitive advantages in certain cases.
A feature of one aspect of this invention as now provided by this Divisional Application is that the ultimate grain moisture can be obtained by selected settings of the controls. These controls include a thermometer mounted so as to measure plenum-air temperature, and a tempera-ture cycling control, e.g., a thermostat, that activates or deactivates heat sources in response to the plenum-air temperature. A second thermo-meter, sensing the temperature of the exhaust air, provides a differential reading of temperature from the plenum-air so as to provide an indication of grain moisture and extent of drying taking place. The differential reading, when greater than a preset level, causes the heat sources to be inactivated regardless of the thermostat setting.
Incorporated in aspects of this invention as now provided by this Divisional Application is specified electrical apparatus including a specific type of heating means which provide indirect and direct condition-ing of the air.
By means of electrically powered fans, a controlled volume of air is kept flowing through the grain according to grain moisture content as has been described in the aforementioned United States Patent No.
Commonly, hydrocarbon fuels, e.g., propane, are used as a heat source. The combustion of these fuels is associated with the production of water. The BTU per hour output of heaters commonly employed range from 500,000 to 3,000,000 so that the per day production of water as a product of combustion can range from 75 to 500 gallons. This vapour is in the air that goes through the grain.
The seriousness of this problem is attested to by the fact that nearly every drying bin has crusted and sprouting surface grain, overdried bottom grain, rusting of bin walls and rotting of grain.
Present principles and practices of drying stored grain rest on the assumption that obtaining saturated, exhaust air is desirable. In the prior art, specific zones in the grain bulk are referred to, i.e., the dry zone, the drying zone and the wet zone.
Weight losses of 1% of the dry matter have been found to corre-late to a 20% loss of germination, and in today's economy~ such deteriora-tion can amount to as much as 20¢ per bushel loss in value. Since loss of germination means loss of value, it is desirable to maintain maximum germination. Therefore, maximum control provides maximum germination, and the induction of dormancy from the earliest time following the harvest of lO90S62 the grain by exposing the harvested grain to controlled air flow and moisture removal is desirable. Dormancy is a state of retarded respirs-tion; accelerated respiration increases kernel food consumption and weight loss. Respiration is the conversion of_oxygen to carbon diox de (the carbon being derived from the consumed sugar) and is exothermic, i.e., heat is generated. Thus, when high-moisture _orn is exposed to warm saturated air, the rapid development of mold and heating of grain is intensified by the exothermic process of respiration as well as by the external addition of heat.
In the case of excessive differential, overdried grain will result~ if saturated air is obtained, deteriorative conditions are estab-. _ lished. The proces~ of this invention proposes to maximize utilization of natural air, and to maximlze preservation of seed quality and market weight and value. The equilibrium corn moisture obtained during ventilation is shown in the following table.
Si~ilar moisture equilibrium charts can be-prepared for other grains. ~~ ~~~
a; 1(t90~6'~
,__ ~ E~ ~ 0 ~
C~ H ~ O~
P~ X
P~ ~
. P P ~ ~ ~ ~ ~ ~ ~ i~ a~
E-~ H 1-/ 0 ~ ~D O ~ u~ I` O
~ ¢ H c~ ~ t` -J ~ ~t -;t u~
.~ , , . 1~ ~ X
,,, P~ ~3 P
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lO90S6Z
Accordingly, it is an ob~ect o a broad aspect of this invention to provide a grain drying bin for conditioning grain to controlled dormancy and moisture, and to maximize weight and market value for specific markets while maintaining optimum seed conditions.
It is an ob~ect of a further aspect of this invention to provide a grain drying bin for "cool-drying" grain by reference to the temperature differential between dry-air and wet-air in which the dry-air temperature is automatically regulated and the source of heating the drying air can be inactivated when the difference between the wet-air temperature (exhaust) and the dry-air temperature (plenum) is greater than the preset tolerance, allowing for fluctuations of the plenum-air temperature that occur seasonally.
By one aspect of this invention, a grain drying bin is provided which is of the type having a plenum chamber formed in the lower part thereof and a gas-pervious floor forming the top of the plenum chamber, the grain drying bin comprising: means for introducing atmospheric air into the plenum chamber; and electrical heating means for adding heat energy to the air in the plenum chamber, the electrical heating means including a plurality of heat lamps mounted on the lower part of the bin ad~acent the plenum chamber.
By one variant thereof, the grain drying bin further includes:
means for determining the temperature of air in the plenum chamber; means for determining the temperature of air as it exhausts the bin; thermostat means responsive to the temperature of the air in the plenum chamber for controlling the operation of the meating means; and means, adapted to over-ride the thermostat controlling the heating means and to inactivate the heating means when the temperature difference between the drying air in the plenum chamber and the air exiting the bin is greater than a predetermined amount.
By a variation thereof, the grain drying bin further includes:
a plurality of heat lamps spaced about the bin wall ad~acent the plenum chamber and having a total output of 10 to 40 watts per one hundred bushels of bin capacity.
By another variation, the grain drying bin further includes: a plurality of fans distributed about the wall of the plenum chamber; each fan being individually controlled and including closure means to prevent air from exiting the plenum chamber when the fan is inactivated.
By yet another variation, the grain drying bin further includes transparent heat lamp mounting plates detachably secured to the bin wall.
By a still further variation, the grain drying bin further includes means for indicating the amount of air being introduced into the plenum chamber.
By another variant, the heat lamps emit radiant energy.
By another variant, the heat lamps emit radiant energy in the infrared wavelengths in the electromagnetic spectrum.
By a further aspect of this invention, a grain drying bin is provided which is of the type having a plenum chamber formed in the lower part thereof, a gas-pervious floor forming the top of the plenum chamber and an upstanding plenum chamber wall forming the sides of the plenum chamber, the grain drying bin comprising: means for introducing atmos-pheric air into the plenum chamber, including at least one fan tube attached to the plenum chamber wall; and electrical heating means for adding heat energy to the air in the plenum chamber, the electrical heating means comprising a plurality of heat lamps attached to and spaced around - the plenum chamber wall, the plurality of heat lamps also being spaced i from the fan tube on the plenum chamber wall.
By a variant thereof, the heat lamps include means for emitting infrared rays.
By another variant, the graln drying bin further includes a plurality of fan tubes having fans therein spaced around and attached to _. .
lO90S6Z
the plenum chamber wall, each of the fan tubes and the heat lamps being spaced apart from each other around the plenum chamber wall.
By a further aspect of this invention, a grain drying bin is provided of the type having a plenum chamber formed in the lower part thereof and a gas-pervious floor forming the top of the plenum chamber, the grain drying bin comprising: means for introducing atmospheric air into the plenum chamber; and electrical heating means for adding heat energy to the air in the plenum chamber, the electrical heating means comprising a plurality of heat lamps spaced about the plenum chamber.
According to one embodiment of this invention as now provided by the present Divisional Application, grain to be conditioned or dried is placed in a storage bin, generally of the type having a means for blowing drying air into a plenum chamber below the body of grain to be dried.
The roof of the plenum chamber, which is also the floor of the storage bin, is pervious to gas flow and allows the drying air to percolate up through the body of grain to be dried. Bins of this type are quite common in the prior art, but they usually include a blower furnace as the means for supplying drying air to the bin.
In the present invention as now provided by the present Divi-sional Application, in one of its embodiments,:the drying which is effectedmuch more closely approximates what can be termed natural drying. Specifi-cally, it utilizes a flow of air and a particularly specified heat source which is more controllable and less destructive to the grain than prior art techniques. Strictly natural air drying is not fully adequate to reduce grains to moisture levels safe for long-term storage, due to humidity and temperature conditions that exist in fall and early winter, as noted in the following table.
10~056Z
'~ !
NAT~RAL AIR GRAIN DRYNESS* BY THE MONT~ ~IOWA) AVG. CORN WET-BULB** AVG. CORN WET-BULB** ¦
MOISTUR~ DEPRESSION MOISTUR~ DEPRESSION
Jan.20Z 1 - 2 July 11 1/2% 7 - 10-Feb.l9X 1 - 3 Aug. 12% 7 - 9 March i7% 2 - 5 Sept. 13Z 6 - 8 April 16Z 5o _ 70 Oct. 14Z 5 _ 70 May13 1/2Z 7 - 8 Nov. 16% 3 _ 5 June13 1/2Z 7 - 8 Dec. 19~ 1- - 3-. _ . .
*Varies With Dlfferent Grains; also with varietal and sea-son-l differences.
**Average Mean Wet-Bulb DepreggIong From U.S. Weather Bureau Data.
The grain drying bin of aspects of this invention as now provided by this Divisional Application departs fundamentally from this generally accepted assumption and employs a controlled balance of volume of air flow to grain volume and of air dryness to grain dryness while substantially avoiding the clash of warm grain air temperatures with cool or cold ambient temperatures.l The effect is to maintain a relative humidity in the exhaust air below saturation so that some drying can occur within the entire bulk of grain and thus substantially eliminate the "wet zone" of high-moisture perishable grain exposed to saturated air; accelerated rates of respiration (in the grain itself and in molds and other micro-organisms exposed to warm, humid conditions) that intensify losses of weight and food value are likewise sub-stantially prevented. - j The grain drying bin of aspects of this invention as now provided by this Divisional Application utili~es the fact that as water evaporates from a surface, the surface becomes cool. Therefore, as dry air is passed through the body of moist grain, evaporation takes place and cools the grain air a certain amount; t~he amount of cooling is dependent upon a number of factors, e.g., the particular grain being dried, the temperature of the drying air, the moisture content of the grain, and the relative I
.
humidity o~ the drying air. The effect of eyaporatiye cooling is to render the kernel and micro-organism dormant and thus to stabilize the kernels and micro-organisms. It is a feature of an aspect of this inven-tion as now provided by this Divisional Application that the drying air is not heated to such an extent that the grain can be damaged thereby or overdried. It is desired to approximate as closely as practicable the conditions of natural air drying, and accordingly, the drying air is pre-ferably conditioned only to control its dryness or relative humidity with-out greatly raising it above ambient temperatures.
The temperature of the plenum air is controlled, e.g., by a thermostat or other similar modulating or cycling device. According to one aspect of the invention as now provided by this Divisional Application, the temperature differential between plenum air and exhaust air is moni-tored, and the specified heating means is inactivated when the differential exceeds a preselected value.
Specifically, according to an aspect of this invention as now provided by this Divisional Application, a controlled flow of ideal, natural "harvest air" is maintained within the stored grain with an apparatus for measuring and controlling natural air dryness or relative humidity so as to control grain dryness and dormancy. The addition of dry energy (heat) to the drying air is selectively controllable so as to determine the extent of drying that can occur within the grain. This is accomplished by obtaining a measure of the "dry-bulk" temperature and the "wet-bulb" temperature depression that occurs within the grain with the addition of heat only when the wet-bulb depression is less than the pre-determined tolerance.
Since only a small rise in temperatu~e of the drying air is required in the use of the grain drying bin of an aspect of this invention as now provided by this Divisional Application, electrical heating means are ideally suited, and because of their extraordinary safety, convenience --.10 --lO90S62 and serviceability, heat lamps are preferred as a means for heating the drying air. Heat lamps distributed about the plenum chamber uniformly warm metal floor and floor supports, giving good distribution of the added heat. The exceptional economies of light energy as a heat source are well known.
Additionally, radiant heat energy from electrical sources is totaly dry energy and does not aggravate problems of moisture condensation as does the combustion of hydrocarbon fuels.
In summary, the grain drying bin of aspects of this invention as now provided by this Divisional Application provides that, because of the sensitive nature of seeds and other products with similar sensitivities, the application of heat as used in conventional drying of non-living pro-ducts is excessive and intolerably damaging, and that preservation of weight and food value in grain is accomplished only in preserving the biological integrity of the seed.
Further, even when drying is accomplished with low levels of heat, these can be excessive because of the adverse environment created by the heat in increasing seed respiration and in causing stratification of moisture within the grain which allows for mold infestation.
Because of high costs of energy and limitations of energy resourc~s, their wise management, especially in drying grains, is obviously urgent because of the vast expenditure of energy resulting from the growing practice of drying food grains.
More specifically, this invention in another of its aspects as now provided by this Divisional Application includes a grain drying bin operated in such a way that the biological integrity or living character of biological products, especially food grains, is preserved by drying, chilling and conditioning in a controlled storage environment. Such con-trol of storage environment is by ventilation, which maintains a balanced ratio of air-volume to grain-volume, and which substantially prevents stagnation of and accumulation of moisture in the interstitial grain-air.
Throughout the conditioning process inherent in the use of the apparatus of aspects of this invention as now provided by this Divisional Applica-tion, the temperature of the product in storage remains colder than ambient temperatures and that when the product has achieved the desired equilibrium moisture, it is at the same temperature as the ambient air.
Furthermore, monitoring means indicate the extent of heat expen-diture or evaporative cooling during ventilation, i.e., the differential temperature observéd from the time the air enters the grain to the time it exhausts, thereby providing direct indication of equilibrium moisture being achieved within the grain at any time. Control means are provided which automatically activate or deactivate heat sources in response to evapora-tive cooling and make possible the selective control of moisture content in the grain by selective control of differential temperatures.
In the accompanying drawings, Figure 1 is a side elevation view, partically cut away, showing a grain bin equipped according to one aspect of this invention;
Figure 2 is an exploded view showing the details of heat lamp mountings according to one aspect of the invention;
Figure 3 is a front elevation view showing a control panel for use in accordance with one aspect of this invention;
Figure 4 shows a schçmatic operational circuit diagram for the operation of the grain bin of one embodiment of the in~ention;
Figure 5 shows a schematic opërational circuit diagram for the operation of the grain bin of another embodiment of the invention; and Figure 6 is a partial perspective view of the interior bottom of the grain bin equipped with a multiple fan arrangement according to one aspect of this invention, with certain portions removed for clarity.
According to one embodiment of this invention as now provided by this Divisional Application, a grain drying bin is now provided which has !
~ 1090S6Z
the ability to produce grain having precisely controlled levels of moisture and also provides that these levels are obtained in a manner which results in minimum germination loss of the grain with resultant maximum quality for ultimate use. Some processing techniques require specific moisture levels, and the ability to supply grain with these specific levels will produce competitive advantages in certain cases.
A feature of one aspect of this invention as now provided by this Divisional Application is that the ultimate grain moisture can be obtained by selected settings of the controls. These controls include a thermometer mounted so as to measure plenum-air temperature, and a tempera-ture cycling control, e.g., a thermostat, that activates or deactivates heat sources in response to the plenum-air temperature. A second thermo-meter, sensing the temperature of the exhaust air, provides a differential reading of temperature from the plenum-air so as to provide an indication of grain moisture and extent of drying taking place. The differential reading, when greater than a preset level, causes the heat sources to be inactivated regardless of the thermostat setting.
Incorporated in aspects of this invention as now provided by this Divisional Application is specified electrical apparatus including a specific type of heating means which provide indirect and direct condition-ing of the air.
By means of electrically powered fans, a controlled volume of air is kept flowing through the grain according to grain moisture content as has been described in the aforementioned United States Patent No.
3,408,747, according to the following chart. Because of chilled-air tem-peratures, the process involving the use of the grain bin of an aspect of this invention allows for reduced volumes of air (by 40X) over previously cited recommendations.
REQUIRED C.F.M./BU.
Percent moisture: c.f.m./bu.
30 . . . . . . . . . . 9.0 28 . . . . . . . . . . 7.0 25 . . . . . . . . . . 5.0 22 . . . . . . . . . . 3.5 20 . . . . . . . . . . 2.5 18 . . . . . . . . . . 1.5 Indirect electrical heating is obtained by fan blade friction and by the heat given off by electric motors powering the fans. Also, the pressure in the plenum would be above atmospheric, and the higher pressure gives greater drying capacity to the air as is well known. The combination of fan blade friction, electric motor heat and pressurized air may in some cases raise the temperature as much as from 2 to 5F. This temperature increment together with ideal weather conditions can, in some cases, pro-vide adequate capacity for accomplishing the desired degree of grain dry-ness. However, during most seasons the supplemental adtition of some heat energy will be required. Electrical sources are ideally suited for this additional heat. Advantages obtained by electrical heating include greater safety, ln that the fire hazard is reduced compared to that when conventional blower furnaces are used or when propane burners are used.
Service requirements are at a minimum and only require changing a light or heat element in most cases. Additionally, the well-known sanitizing advan-tage of infrared renders certain bacteria and mold spores inactive upon exposure,which effect is of great value in stabilizing a safe-keeping environment for food grain. The present invention in one of its aspects as now provided by this Divisional Application minimizes problems resulting from conventional high heat drying including uneven drying, overdrying, condensation of moisture within the grain causing accelerated biochemical activity, and moisture condensation on the bin walls. Conventional high-- ~4 -heat drying generally includes introducing the products of combustion into the drying bins, and as a result, large amounts of water are introduced into the grain.
Referring now to Figure 1 of the drawings, a grain storage bin 11 is shown having side walls 12, a conically shaped roof 13, and an opening 14 in the top of the roof. The bin has a foundation 15 and floor supports 16 supporting a floor 17 which is pervious to gas flow. A body of grain to be conditioned is indicated at 18, and fan 19 and duct 20 leading from the fan for introducing air into the plenum chamber are shown.
A group of heat lamps 21 mounted in frames 40 are located around the outer wall of the plenum chamber formed between the bin foundation 15 and the bin floor 17, and control panel 22 is located on the side wall 12 of the bin. According to one simple aspect of this invention as now provided by this Divisional Application, the heat lamps 21 distributed about the lower part of the grain bin side walls 12 are simply turned on and left on during the entire drying procedure, which may take several weeks. In some cases, the heat lamps 21 may be thermostatically controlled to maintain a desired temperature level in the plenum chamber. The kilowatt input accomplished with lamps is generally within a range from 1/4 to 3/4 watt per bushel of bin capacity.
According to a variant of the invention also shown in Figure 1, a temperature sensing means 37 is shown in the top of the body of grain 18 and is located preferably near the center of the bin to minimize the effects of heat loss through the bin wall. Plenum air thermostat 33 (see Figure 3) with differential sensor 36 closes the circuit supplying power to cable 47 within the range of preset tolerances,~i.e., if the exhaust air drops below the preset tolerance of cooling, the circuit is opened, or if the plenum-air temperature rises above the thermostat setting the circuit is broken.
As an alternative to the use of fan l9 and duct 20 as shown in lO90S62 Figure 1, a plurality of small fans 24 could be spaced about the bin directly on the lower bin wall, (which is also seen in Figure 1). These smaller fans would preferably be individually operable to guard against a surge of electrical load if all the fans were turned on togetherr and would include suitable closure means on each fan (not shown) substantially to prevent pressurized air from the plenum chamber from exiting through a fan that is not running.
A preferred embodiment of the heating means to be utilized in an aspect of this invention as now provided by this Divisional Application is illustrated in Pigure 2. As shown therein, a window frame 40 which may - be round, square, or rectangular, attaches to the bin wall 12 by means of bolts 41 or other suitable means through holes in bin wall 12. Heat lamp 42 is carried by receptacle 43 carried on transparent window 44. Window 44 can be removed for changing a burned out lamp or for providing access to the plenum chamber for cleaning or inspection simply by removing bolts 45. Some of the advant~ges provided by this embodiment include ease of maintenance, access to plenum for inspection or cleaning, illumination of both plenum and grQunds outside the bin, and substantial prevention of mildew. j This embodiment also reduces fire hazards which arelpresent when flame heaters .
are used, and substantially eliminates the pollution resulting from flame heaters or glowing resistance elements.
Figure 3 shows a grain dryness control panel 22 suitable for mounting on the lower side wall of the bin below the floor 17.
The control panel includes: a thermostat 32 with a remote sensor 37 that measures the exhaust air temperature; a thermostate 31 that measures the plenum air temperature; a cycling (thermostat humidstat) and/or moldulating means 33 with remote sensor 36; and differential (humidity/temperature) selector 34; a light 38 indicating when the circuit is open or closed; a power cord 47 supplying power to the heat sources;
and a manometer 35 that indicates air flow.
B - 16 _ In Figure 4 the power cord 47 is connectet to a power source (not shown) and forms a circuit having a heat lamp 42, a thermostat 33, and a differential temperature controller 34 all connected in series. The thermostat 33 responds to warming through sensor 46. Thermometer 31 indicates the temperature in the plenum at sensor 46, and this temperature reading is also carried to thermostat 33 and differential controller 34 by lines 33' and 34', respectively. The temperature of the exhaust chamber of the grain bin is measured by sensor 36, which temperature reading is indicated on thermometer 32 and is also input into differential controller 34.
In Figure 5, the power cord is likewise connected to a power source (not shown) and has connected, in series therewith, a thermostat 53, and a heat lamp 42. Thermostat 33 operates exactly as described in the Figure 4 embodiment, i.e., it responds to warming. mermostat 33 closes the contact when the temperature at sensor 46 is below the setting thereon, and the contact is opened when the temperature at sensor 46 rises to the temperature set on the setting, or above the setting. mermostat 53 works in an opposite fashion in that it responds to chilling, i.e., when the temperature sensed by sensor 46 is lower than the setting thereon, the thermostat 53 contact is open and when the temperature sensed by sensor 36 is at the setting or above, the circuit is closed. It will be under-` stood that the heat lamp 42 operates only when the contacts of both thermo-stats 33 and 53 are closed. This arrangement, like that of the embodiment of Figure 4, is fully automatic.
Figure 6 shows a view of the base of the grain drying bin, including the side walls 12 resting on the foundation 15 and floor supports 16 which support a floor 17 which is pervious to gas flow. The group of heat lamps 21 are shown disposed around the perimeter of the floor supports 16, and the fans 19 and ducts 20 leading therefrom for introducing air into the plenum chamber are shown to be spaced around the perimeter of the floor support and between the heat lamps 21. The ducts 20 are pro-vided with air controlling registers 54.
The operation of the control panel shown in Figure 3 is based upon the following considerations:
When corn moisture is above 26%, sufficient water is present so that evaporation and evaporative cooling approximates that of water from a free surface. Therefore, the temperature depression measured in the ex-haust air when compared with that of the plenum air provides the wet-bulb temperature reading. This being so, the previously cited moisture equili-brium chart (TABLE 1) provides a meaningful guide (based on psychometricwet-bulb depression) as to how dry the grain is becoming.
To obtain 13% moisture corn, the wet-bult depression to be main-tained should be 7F. approximately.
As the grain dries, its hygroscopic property (i.e., internal seed forces holding water) increasingly resists evaporation, and as evaporation decreases evaporative cooling also decreases. When grain moisture reaches equilibrium with air moisture, the plenum air and exhaust air temperatures will be the same ant no drying will take place.
Therefore, the comparison of these two temperatures provides positive indication as to when drying does or does not ta~e place and as to how dry the grain is becoming; heretofore, the farmer could only guess about these situations. More complete charts can be supplied as a valuable aid to the producer in co~trolling drying, e.g., the chart shown in Table I.
The ultimate dryness of the grain is determined by the ultimate dryness of the air. It can be observed from a psychrometric chart that a 5F. wet-bulb depression at 70F. represents 74% relative humidity (14.0 corn moisture); while a 10F. wet-bulb depression at 70F. represents a 55% relative humldity and 11.4% corn moisture; while a 20~F. wet-bulb de-pression represents a 36Z relative humidity and corn moisture under 9~.
Similarly, relative humidities and equilibrium corn moisture can be found .losns~z for all other normally occurring temperatures. The actual wet-bulb depres-sion observed in the surface grain may be somewhat less than the real wet-bulb depresæion as the grain dries, and increasingly so the closer grain moisture approaches equilibrium moisture with the atmosphere, so that actual grain dryness being achieved would, in fact, be lower than that suggested by the observed temperature differential. The corn equilibrium chart contained in the aforesaid United States Patent No. 3,408,747 gives corn moisture levels below those cited on the chart contained in this invention and represents an accommodation to the changing hygroscopic characteristics of grain as it dries, and may therefore more accurately represent grain moisture being achieved.
-- 19, ----` TABLE 1 ~09056Z
GRAIN MOISTURE EQUILIBRIUM. CORN ROUGH RICE SOYBEANS.
~ i ... . U o~ o~ ~ I
~ . ~ ~1 o o . ~: ~ ~ ~ . . .
U~ ~ o ~ o ~ ~ ~
o . U ~ O~J D ~ ~ ~> ~ u~ ~
O Z; ~ ~ 0~ 0 OP' ~ ~ O U~
X ~ ~c~ ~ ~ 1 u~ P u ~: ~ p, a~o~ o-~lu) ~
_I H t~ ~ ~ ~ O O O ~ ~ O ~ ~ u~
o ~ . ~ ~o ~ u~ ~ o ~ ~ ~ ~ ~
o P w q~ C o ~ o ~ ~ ~ ~ 1 ~
0~ . ~ ~S U C OD ~ u~ 0 ~ ~ O ~ u~ e~ CO O ~ u~
~: ~ U ~, C ~ j_l~ ~ 1 ~ _~ OCI~ ~ ~
o~4 U~ ~0 ~ 0 ~ 4 O ~ O ~ U~ ~ o~ u7 1~ o o o PS C o O ~ _l ~ ~ ~ ~ ~ o o <~
.C ~d ~ ~ ~ _~ ~1 ~ ~ 1 ~ ~ ~J
P6 o Z 4 ~ 0 h :~ ~ 0 0 1~ o~ ~ ~ u~ 0 ~ O ~ u~
p u~ 'C ~O~ ~ ~ ~ O ~0 0 _1 _1 ~ ~ O o~l~ co ~ u~
U C ~O.n ~D 0 _1 ~ U~ ~ _~ ~ ~ _l ~ ~ ~ O~
~ o ~ u~ S~ ~ ~ . . . . . . . . . . . . . .
P~ O ~ C O O O ~ O o~ ~ ~ u~ u~ ~ O~ I~ ~O
X ~ ~.~: ~ C~ ~1 ~1 _1 ~1 ~ 1 ~ 1 E~ ~ vC ~0 ~ ~ ~ o ~ u~ ~ ~ u~ 1~ 0 O~
PS P~ O O ~ O ~ r~ ~ O u~ ~ O~ ~ `D ~
c ~rC ~ c~ ~ _l ~ ~ _l ,. ,1 _1 c~ ~ ~ .c VC ~0 ~ ~1 ~ ~ 1~ o~ C~l O 1~ vl O ~1 u~ 1~ O rl ~U
E- `~ ~a ~ . . . . . . . . . . . . .
~q O ~ ~ O O O ~1 0 CO ~ ~ O U~ ~ ~ ~ OD ~ U~ ~J _ ,C ~ ~ ~1 ~ ~ ~1_1 c~ 0 ~ ~ OO,n ~ O ~ ~ ~ ~ ~ ~ O
X o ~ . . . . . . . . . . . . . . V~
u~ O O O O O a~ ~ ~ ~ ~ o~ D u~ ~ V O
U~ ~ ~ ~ ~ ~ ~ o U~ I~ o o ~ U~ U~ I~ o ~ o U~ 1~ o ~ O . . . . .,. . . . . . . . . .
:~ o o~o~ ~1~ ~ C~l`~ U~ .¢
~O _l ~ . ~ 1 ~ 1 ~ ~ ~ V
~ ~ ~ ~ ~ ~ I~ ~o a~ _~ c~ ~1 ~
o . . . . . . . . . . . C
U~ ~oo~ ~ ,~u~ ~C~ ~
~D ~ ~ 1 ~ ~ ~ ~ ~J O
1~ O~ ~ ~ ~ ~ ~O r~ y~ ~ . O
o ~ 1~ ~D ~ ~ ~ V O
` ~ 1 ~ 1 ~ o ~
~ 'D t _l a~t o ~ ~ v o ~o to~ ~ ~t ~ _~ ~; ~`- ~ o t~
1 ~ t ~ c~
O ~ ~ O
t o o o o o o o ' o o o --O t~lt O tJ~ O tJlt o u~ o t ~ , t~ , I DRY, PLENUM-AIR TEMPERATURE
, ~090562 The measure of wet-bulb depression is a measure o relative humidity; it is obvious, therefore, that controlling wet-bulb depression controls relative humidity.
~ When the setting on thermostat 33 is below the temperature observed on thermometer 31, the contacts of the thermostat are open and light 38 will be on.
When drying begins, thermostat 33 is set as desired (e.g., 6F.
above ambient) by turning the knob of 33 in the direction of "increase"
indicated by the arrow.
When the thermostat 33 setting is above the plenum temperature, the contacts close to activate the heat source and light 38 goes out.
When the temperature of the plenum is the same as the thermostat setting, the heat sources are deactivated. It can happen that because of low rela-tive humidities in the natural air, overdrying can occur even though the temperature of the plenum air would never reach the thermostat setting.
Undesirable overdrying would result if the heat source were not deacti-vated. Such conditions are indicated if the exhaust air temperature drops excessively below the plenum temperature, e.g., 10F. An adjustable temperature differential control means 34 is provided in conjunction with the thermostat 33. Differential control means 34 is adapted to determine the differential between plenum air and exhaust air, and automatically to open the thermostat circuit, thereby deactivating the heat source, when the differential exceeds the value preset on control means 34.
The manometer 35 measures static pressure (inches water) and indicates the volume of air being delivered by the fan(s).
The required ratio of air-volume to grain-volume varies with the grain moisture, By knowing the actual and the required ratios, the operator knows how fast the bin can safely be filled. The required ratios (cfm/Bu.) for heated ai~ drying are defined in the sforesaid United States Patent -- 30 No. 3,408,747, but because of chilled air temperatures are less:than those required in the above identified patent, ag has been observed previously.
Filling of the bin can continue as long as ratios are maintained.
By fixing the depth of grain (8 - 14'), a prescribed horsepower requirement can be defined to maintain a certain level of air.
By maintaining horsepower application of 1/2 to 1-1/2 h.p. per 1000 bushels of corn, an air-to-grain ratio of 3 cfm/Bu. can be maintained and substantially complete filling of the structure allowed. For example, a 10 H.P. is recommended for 10,000 bushels of corn; a 33~ diameter bin is required to obtain 10,000 bushels in a 12 - 14' depth. As grain depth increases, pressure increases and air flow decreases, thus decreasing the safe fill rate. Air volume has to be maintained according to grain moisture content as previously cited, which principle is basically applicable to all grains.
Heretofore it has been customary to use single fans. The appli-cation of multiple fans offers distinct advantages: control of air flow according to grains need lower electrical requirements; increased air flow; more uniform air flow, more easily serviced; more direct attachment to the bin by sizing fan housing to plenum depth and a more flexible appli-cation of horsepower to fit a wide variation of systems.
The fans 19 have flap closures around the plenum chamber which allow the respective fans to introduce air into the plenum chamber, but which substantially prevent air from leaving the plenum chamber when that same respective fan is not operative. Furthèr, it becomes practicable to prefabricate an electrical harness that attaches in series to the previous fan providing a simple "add on" approach to increase fan numbers in a given system.
It is a feature of this invention as now provided by this Divisional Application that grain can be dried in a manner more closely approximating natural drying, and over-heating and over-drying of the grain can be avoided. Specifically, satisfactory drying rates may be obtained without using supplemental heat sources e.g., the heat lamps 21 -`` 109056;~
so long as the dryness of the air is consistent with the desired equili-brium dryness that will be obtained in the grain. When the outside air temperature is too cold and/or when it has a high humidity, the supple-mental heat source can then be activated to provide the necessary dryness in the air to obtain proper drying rates.
The differential setting for the operation will vary with the particular grain being dried and the ultimate moisture content desired .
A~ setting of 7 - 10 F. may be best for corn, while a 5 - 8F. differen-tial may be best for rough rice and a 3 - 6F. differential for soybeans.
It must be emphasized that adequate air flow must be provided in any drying operation of this type. As has been said, a thorough dis-cussion of the importance of air volume to the drying operation appears in the aforesaid United States Patent No. 3,408,747.
Dryness of the air determines dryness of the grain, while the volume of air employed and the temperature determines how long it will take to complete drying.
Calculated averages for dryness, for time required, as well as probability of weight and germination losses (as described in the afore-said United States Patent No. 3,408,747) can be determined according to differing conditions of air flows.
For exampleJ 26% moisture corn harvested on November 1, using 1-1/2 cfm/Bu. generally requires 44 days to dry to 13-1/2% moisture with a 64Z probability of losing 0.5% of dry matter (approximately 10% germina-tion); doubling the air volume (3 cfm/Bu.) reduces the probability of weight loss to zero and reduces drying time to 22 days.
The application of this gradual process of moisture removal does not limit harvest capacities since under certain moisture levels (25%) instant and total filling of the bin is possible. Even now, structures up to 48' diameter are available with capacities in excess of 20,000 bushels.
The operation of one embodiment of the invention as now provided ~090~i6Z
by this Divisional Application will now be illustrated by reference to Figures 1 and 3 of the drawings. A grain bin 11 is filled with grain to be conditioned, e.g., by filling through the opening 14 in the roof 13 of the bin. After the grain 18 is in the bin and has been levelled, tem-perature sensor 37 and sensor 36 for the differential temperature control are placed in the bed of grain near the surface thereof. Depending upon the ambient temperature and humidity conditions, a desired drying tempera-ture is set on the thermostat 33 and a setting selected for maxmimum tolerable differéntial. During fan 19 operation, air is forced into the plenum chamber and up through the floor 17 into the body of grain 18 and eventually out the opening 14. As the drying air passes through the body of grain, moisture will tend to be removed from the grain into the air, and the resultant evaporation will cause a lowering of the temperature of the air. The extent of the temperature lowering will be indicative of the rate of removal of water from the grain, and can be observed by the operator by reference to the thermometers 31 and 32. If the temperature differential indicated by thermometers 31 and 32 exceeds the differential setting of control 34, this indicates that overdrying would occur, and the differential control 34 will function to inactivate the supplemental heating means. Drying will then continue utilizing air which has not had supplemental heat added thereto, other than the small amount resulting from the operation of the fan and motor. The differential temperature then will tend to work back toward the range set on the differential con-trol 34, and if the differential temperature becomes less than the amount set on control 34, the thermostat may again cause the heat lamps 21 to become activated, adding heat to the drying air.
Now, with respect to the embodiment shown in Figure 4, in its operation, the heat lamp 42 will only operate when the contacts of both the termostat and the differential controller 34 are closed. Consequently, in order for the heat lamp to operate, the temperature sensed in the plenum ~09056Z
by sensor 46 must be below the preset temperature of thermostat 33 in order to have the contact in thermostat 33 closed, and the different$al tempera-ture between 36 and 46 (in the exhaust and plenum chambers, respectively) must be less than the differential setting on differential controller 34.
It will be understood that thermostat 33 and differential controller 34 respond automatically to close the contacts as well as to open them to provide a fully automated control.
REQUIRED C.F.M./BU.
Percent moisture: c.f.m./bu.
30 . . . . . . . . . . 9.0 28 . . . . . . . . . . 7.0 25 . . . . . . . . . . 5.0 22 . . . . . . . . . . 3.5 20 . . . . . . . . . . 2.5 18 . . . . . . . . . . 1.5 Indirect electrical heating is obtained by fan blade friction and by the heat given off by electric motors powering the fans. Also, the pressure in the plenum would be above atmospheric, and the higher pressure gives greater drying capacity to the air as is well known. The combination of fan blade friction, electric motor heat and pressurized air may in some cases raise the temperature as much as from 2 to 5F. This temperature increment together with ideal weather conditions can, in some cases, pro-vide adequate capacity for accomplishing the desired degree of grain dry-ness. However, during most seasons the supplemental adtition of some heat energy will be required. Electrical sources are ideally suited for this additional heat. Advantages obtained by electrical heating include greater safety, ln that the fire hazard is reduced compared to that when conventional blower furnaces are used or when propane burners are used.
Service requirements are at a minimum and only require changing a light or heat element in most cases. Additionally, the well-known sanitizing advan-tage of infrared renders certain bacteria and mold spores inactive upon exposure,which effect is of great value in stabilizing a safe-keeping environment for food grain. The present invention in one of its aspects as now provided by this Divisional Application minimizes problems resulting from conventional high heat drying including uneven drying, overdrying, condensation of moisture within the grain causing accelerated biochemical activity, and moisture condensation on the bin walls. Conventional high-- ~4 -heat drying generally includes introducing the products of combustion into the drying bins, and as a result, large amounts of water are introduced into the grain.
Referring now to Figure 1 of the drawings, a grain storage bin 11 is shown having side walls 12, a conically shaped roof 13, and an opening 14 in the top of the roof. The bin has a foundation 15 and floor supports 16 supporting a floor 17 which is pervious to gas flow. A body of grain to be conditioned is indicated at 18, and fan 19 and duct 20 leading from the fan for introducing air into the plenum chamber are shown.
A group of heat lamps 21 mounted in frames 40 are located around the outer wall of the plenum chamber formed between the bin foundation 15 and the bin floor 17, and control panel 22 is located on the side wall 12 of the bin. According to one simple aspect of this invention as now provided by this Divisional Application, the heat lamps 21 distributed about the lower part of the grain bin side walls 12 are simply turned on and left on during the entire drying procedure, which may take several weeks. In some cases, the heat lamps 21 may be thermostatically controlled to maintain a desired temperature level in the plenum chamber. The kilowatt input accomplished with lamps is generally within a range from 1/4 to 3/4 watt per bushel of bin capacity.
According to a variant of the invention also shown in Figure 1, a temperature sensing means 37 is shown in the top of the body of grain 18 and is located preferably near the center of the bin to minimize the effects of heat loss through the bin wall. Plenum air thermostat 33 (see Figure 3) with differential sensor 36 closes the circuit supplying power to cable 47 within the range of preset tolerances,~i.e., if the exhaust air drops below the preset tolerance of cooling, the circuit is opened, or if the plenum-air temperature rises above the thermostat setting the circuit is broken.
As an alternative to the use of fan l9 and duct 20 as shown in lO90S62 Figure 1, a plurality of small fans 24 could be spaced about the bin directly on the lower bin wall, (which is also seen in Figure 1). These smaller fans would preferably be individually operable to guard against a surge of electrical load if all the fans were turned on togetherr and would include suitable closure means on each fan (not shown) substantially to prevent pressurized air from the plenum chamber from exiting through a fan that is not running.
A preferred embodiment of the heating means to be utilized in an aspect of this invention as now provided by this Divisional Application is illustrated in Pigure 2. As shown therein, a window frame 40 which may - be round, square, or rectangular, attaches to the bin wall 12 by means of bolts 41 or other suitable means through holes in bin wall 12. Heat lamp 42 is carried by receptacle 43 carried on transparent window 44. Window 44 can be removed for changing a burned out lamp or for providing access to the plenum chamber for cleaning or inspection simply by removing bolts 45. Some of the advant~ges provided by this embodiment include ease of maintenance, access to plenum for inspection or cleaning, illumination of both plenum and grQunds outside the bin, and substantial prevention of mildew. j This embodiment also reduces fire hazards which arelpresent when flame heaters .
are used, and substantially eliminates the pollution resulting from flame heaters or glowing resistance elements.
Figure 3 shows a grain dryness control panel 22 suitable for mounting on the lower side wall of the bin below the floor 17.
The control panel includes: a thermostat 32 with a remote sensor 37 that measures the exhaust air temperature; a thermostate 31 that measures the plenum air temperature; a cycling (thermostat humidstat) and/or moldulating means 33 with remote sensor 36; and differential (humidity/temperature) selector 34; a light 38 indicating when the circuit is open or closed; a power cord 47 supplying power to the heat sources;
and a manometer 35 that indicates air flow.
B - 16 _ In Figure 4 the power cord 47 is connectet to a power source (not shown) and forms a circuit having a heat lamp 42, a thermostat 33, and a differential temperature controller 34 all connected in series. The thermostat 33 responds to warming through sensor 46. Thermometer 31 indicates the temperature in the plenum at sensor 46, and this temperature reading is also carried to thermostat 33 and differential controller 34 by lines 33' and 34', respectively. The temperature of the exhaust chamber of the grain bin is measured by sensor 36, which temperature reading is indicated on thermometer 32 and is also input into differential controller 34.
In Figure 5, the power cord is likewise connected to a power source (not shown) and has connected, in series therewith, a thermostat 53, and a heat lamp 42. Thermostat 33 operates exactly as described in the Figure 4 embodiment, i.e., it responds to warming. mermostat 33 closes the contact when the temperature at sensor 46 is below the setting thereon, and the contact is opened when the temperature at sensor 46 rises to the temperature set on the setting, or above the setting. mermostat 53 works in an opposite fashion in that it responds to chilling, i.e., when the temperature sensed by sensor 46 is lower than the setting thereon, the thermostat 53 contact is open and when the temperature sensed by sensor 36 is at the setting or above, the circuit is closed. It will be under-` stood that the heat lamp 42 operates only when the contacts of both thermo-stats 33 and 53 are closed. This arrangement, like that of the embodiment of Figure 4, is fully automatic.
Figure 6 shows a view of the base of the grain drying bin, including the side walls 12 resting on the foundation 15 and floor supports 16 which support a floor 17 which is pervious to gas flow. The group of heat lamps 21 are shown disposed around the perimeter of the floor supports 16, and the fans 19 and ducts 20 leading therefrom for introducing air into the plenum chamber are shown to be spaced around the perimeter of the floor support and between the heat lamps 21. The ducts 20 are pro-vided with air controlling registers 54.
The operation of the control panel shown in Figure 3 is based upon the following considerations:
When corn moisture is above 26%, sufficient water is present so that evaporation and evaporative cooling approximates that of water from a free surface. Therefore, the temperature depression measured in the ex-haust air when compared with that of the plenum air provides the wet-bulb temperature reading. This being so, the previously cited moisture equili-brium chart (TABLE 1) provides a meaningful guide (based on psychometricwet-bulb depression) as to how dry the grain is becoming.
To obtain 13% moisture corn, the wet-bult depression to be main-tained should be 7F. approximately.
As the grain dries, its hygroscopic property (i.e., internal seed forces holding water) increasingly resists evaporation, and as evaporation decreases evaporative cooling also decreases. When grain moisture reaches equilibrium with air moisture, the plenum air and exhaust air temperatures will be the same ant no drying will take place.
Therefore, the comparison of these two temperatures provides positive indication as to when drying does or does not ta~e place and as to how dry the grain is becoming; heretofore, the farmer could only guess about these situations. More complete charts can be supplied as a valuable aid to the producer in co~trolling drying, e.g., the chart shown in Table I.
The ultimate dryness of the grain is determined by the ultimate dryness of the air. It can be observed from a psychrometric chart that a 5F. wet-bulb depression at 70F. represents 74% relative humidity (14.0 corn moisture); while a 10F. wet-bulb depression at 70F. represents a 55% relative humldity and 11.4% corn moisture; while a 20~F. wet-bulb de-pression represents a 36Z relative humidity and corn moisture under 9~.
Similarly, relative humidities and equilibrium corn moisture can be found .losns~z for all other normally occurring temperatures. The actual wet-bulb depres-sion observed in the surface grain may be somewhat less than the real wet-bulb depresæion as the grain dries, and increasingly so the closer grain moisture approaches equilibrium moisture with the atmosphere, so that actual grain dryness being achieved would, in fact, be lower than that suggested by the observed temperature differential. The corn equilibrium chart contained in the aforesaid United States Patent No. 3,408,747 gives corn moisture levels below those cited on the chart contained in this invention and represents an accommodation to the changing hygroscopic characteristics of grain as it dries, and may therefore more accurately represent grain moisture being achieved.
-- 19, ----` TABLE 1 ~09056Z
GRAIN MOISTURE EQUILIBRIUM. CORN ROUGH RICE SOYBEANS.
~ i ... . U o~ o~ ~ I
~ . ~ ~1 o o . ~: ~ ~ ~ . . .
U~ ~ o ~ o ~ ~ ~
o . U ~ O~J D ~ ~ ~> ~ u~ ~
O Z; ~ ~ 0~ 0 OP' ~ ~ O U~
X ~ ~c~ ~ ~ 1 u~ P u ~: ~ p, a~o~ o-~lu) ~
_I H t~ ~ ~ ~ O O O ~ ~ O ~ ~ u~
o ~ . ~ ~o ~ u~ ~ o ~ ~ ~ ~ ~
o P w q~ C o ~ o ~ ~ ~ ~ 1 ~
0~ . ~ ~S U C OD ~ u~ 0 ~ ~ O ~ u~ e~ CO O ~ u~
~: ~ U ~, C ~ j_l~ ~ 1 ~ _~ OCI~ ~ ~
o~4 U~ ~0 ~ 0 ~ 4 O ~ O ~ U~ ~ o~ u7 1~ o o o PS C o O ~ _l ~ ~ ~ ~ ~ o o <~
.C ~d ~ ~ ~ _~ ~1 ~ ~ 1 ~ ~ ~J
P6 o Z 4 ~ 0 h :~ ~ 0 0 1~ o~ ~ ~ u~ 0 ~ O ~ u~
p u~ 'C ~O~ ~ ~ ~ O ~0 0 _1 _1 ~ ~ O o~l~ co ~ u~
U C ~O.n ~D 0 _1 ~ U~ ~ _~ ~ ~ _l ~ ~ ~ O~
~ o ~ u~ S~ ~ ~ . . . . . . . . . . . . . .
P~ O ~ C O O O ~ O o~ ~ ~ u~ u~ ~ O~ I~ ~O
X ~ ~.~: ~ C~ ~1 ~1 _1 ~1 ~ 1 ~ 1 E~ ~ vC ~0 ~ ~ ~ o ~ u~ ~ ~ u~ 1~ 0 O~
PS P~ O O ~ O ~ r~ ~ O u~ ~ O~ ~ `D ~
c ~rC ~ c~ ~ _l ~ ~ _l ,. ,1 _1 c~ ~ ~ .c VC ~0 ~ ~1 ~ ~ 1~ o~ C~l O 1~ vl O ~1 u~ 1~ O rl ~U
E- `~ ~a ~ . . . . . . . . . . . . .
~q O ~ ~ O O O ~1 0 CO ~ ~ O U~ ~ ~ ~ OD ~ U~ ~J _ ,C ~ ~ ~1 ~ ~ ~1_1 c~ 0 ~ ~ OO,n ~ O ~ ~ ~ ~ ~ ~ O
X o ~ . . . . . . . . . . . . . . V~
u~ O O O O O a~ ~ ~ ~ ~ o~ D u~ ~ V O
U~ ~ ~ ~ ~ ~ ~ o U~ I~ o o ~ U~ U~ I~ o ~ o U~ 1~ o ~ O . . . . .,. . . . . . . . . .
:~ o o~o~ ~1~ ~ C~l`~ U~ .¢
~O _l ~ . ~ 1 ~ 1 ~ ~ ~ V
~ ~ ~ ~ ~ ~ I~ ~o a~ _~ c~ ~1 ~
o . . . . . . . . . . . C
U~ ~oo~ ~ ,~u~ ~C~ ~
~D ~ ~ 1 ~ ~ ~ ~ ~J O
1~ O~ ~ ~ ~ ~ ~O r~ y~ ~ . O
o ~ 1~ ~D ~ ~ ~ V O
` ~ 1 ~ 1 ~ o ~
~ 'D t _l a~t o ~ ~ v o ~o to~ ~ ~t ~ _~ ~; ~`- ~ o t~
1 ~ t ~ c~
O ~ ~ O
t o o o o o o o ' o o o --O t~lt O tJ~ O tJlt o u~ o t ~ , t~ , I DRY, PLENUM-AIR TEMPERATURE
, ~090562 The measure of wet-bulb depression is a measure o relative humidity; it is obvious, therefore, that controlling wet-bulb depression controls relative humidity.
~ When the setting on thermostat 33 is below the temperature observed on thermometer 31, the contacts of the thermostat are open and light 38 will be on.
When drying begins, thermostat 33 is set as desired (e.g., 6F.
above ambient) by turning the knob of 33 in the direction of "increase"
indicated by the arrow.
When the thermostat 33 setting is above the plenum temperature, the contacts close to activate the heat source and light 38 goes out.
When the temperature of the plenum is the same as the thermostat setting, the heat sources are deactivated. It can happen that because of low rela-tive humidities in the natural air, overdrying can occur even though the temperature of the plenum air would never reach the thermostat setting.
Undesirable overdrying would result if the heat source were not deacti-vated. Such conditions are indicated if the exhaust air temperature drops excessively below the plenum temperature, e.g., 10F. An adjustable temperature differential control means 34 is provided in conjunction with the thermostat 33. Differential control means 34 is adapted to determine the differential between plenum air and exhaust air, and automatically to open the thermostat circuit, thereby deactivating the heat source, when the differential exceeds the value preset on control means 34.
The manometer 35 measures static pressure (inches water) and indicates the volume of air being delivered by the fan(s).
The required ratio of air-volume to grain-volume varies with the grain moisture, By knowing the actual and the required ratios, the operator knows how fast the bin can safely be filled. The required ratios (cfm/Bu.) for heated ai~ drying are defined in the sforesaid United States Patent -- 30 No. 3,408,747, but because of chilled air temperatures are less:than those required in the above identified patent, ag has been observed previously.
Filling of the bin can continue as long as ratios are maintained.
By fixing the depth of grain (8 - 14'), a prescribed horsepower requirement can be defined to maintain a certain level of air.
By maintaining horsepower application of 1/2 to 1-1/2 h.p. per 1000 bushels of corn, an air-to-grain ratio of 3 cfm/Bu. can be maintained and substantially complete filling of the structure allowed. For example, a 10 H.P. is recommended for 10,000 bushels of corn; a 33~ diameter bin is required to obtain 10,000 bushels in a 12 - 14' depth. As grain depth increases, pressure increases and air flow decreases, thus decreasing the safe fill rate. Air volume has to be maintained according to grain moisture content as previously cited, which principle is basically applicable to all grains.
Heretofore it has been customary to use single fans. The appli-cation of multiple fans offers distinct advantages: control of air flow according to grains need lower electrical requirements; increased air flow; more uniform air flow, more easily serviced; more direct attachment to the bin by sizing fan housing to plenum depth and a more flexible appli-cation of horsepower to fit a wide variation of systems.
The fans 19 have flap closures around the plenum chamber which allow the respective fans to introduce air into the plenum chamber, but which substantially prevent air from leaving the plenum chamber when that same respective fan is not operative. Furthèr, it becomes practicable to prefabricate an electrical harness that attaches in series to the previous fan providing a simple "add on" approach to increase fan numbers in a given system.
It is a feature of this invention as now provided by this Divisional Application that grain can be dried in a manner more closely approximating natural drying, and over-heating and over-drying of the grain can be avoided. Specifically, satisfactory drying rates may be obtained without using supplemental heat sources e.g., the heat lamps 21 -`` 109056;~
so long as the dryness of the air is consistent with the desired equili-brium dryness that will be obtained in the grain. When the outside air temperature is too cold and/or when it has a high humidity, the supple-mental heat source can then be activated to provide the necessary dryness in the air to obtain proper drying rates.
The differential setting for the operation will vary with the particular grain being dried and the ultimate moisture content desired .
A~ setting of 7 - 10 F. may be best for corn, while a 5 - 8F. differen-tial may be best for rough rice and a 3 - 6F. differential for soybeans.
It must be emphasized that adequate air flow must be provided in any drying operation of this type. As has been said, a thorough dis-cussion of the importance of air volume to the drying operation appears in the aforesaid United States Patent No. 3,408,747.
Dryness of the air determines dryness of the grain, while the volume of air employed and the temperature determines how long it will take to complete drying.
Calculated averages for dryness, for time required, as well as probability of weight and germination losses (as described in the afore-said United States Patent No. 3,408,747) can be determined according to differing conditions of air flows.
For exampleJ 26% moisture corn harvested on November 1, using 1-1/2 cfm/Bu. generally requires 44 days to dry to 13-1/2% moisture with a 64Z probability of losing 0.5% of dry matter (approximately 10% germina-tion); doubling the air volume (3 cfm/Bu.) reduces the probability of weight loss to zero and reduces drying time to 22 days.
The application of this gradual process of moisture removal does not limit harvest capacities since under certain moisture levels (25%) instant and total filling of the bin is possible. Even now, structures up to 48' diameter are available with capacities in excess of 20,000 bushels.
The operation of one embodiment of the invention as now provided ~090~i6Z
by this Divisional Application will now be illustrated by reference to Figures 1 and 3 of the drawings. A grain bin 11 is filled with grain to be conditioned, e.g., by filling through the opening 14 in the roof 13 of the bin. After the grain 18 is in the bin and has been levelled, tem-perature sensor 37 and sensor 36 for the differential temperature control are placed in the bed of grain near the surface thereof. Depending upon the ambient temperature and humidity conditions, a desired drying tempera-ture is set on the thermostat 33 and a setting selected for maxmimum tolerable differéntial. During fan 19 operation, air is forced into the plenum chamber and up through the floor 17 into the body of grain 18 and eventually out the opening 14. As the drying air passes through the body of grain, moisture will tend to be removed from the grain into the air, and the resultant evaporation will cause a lowering of the temperature of the air. The extent of the temperature lowering will be indicative of the rate of removal of water from the grain, and can be observed by the operator by reference to the thermometers 31 and 32. If the temperature differential indicated by thermometers 31 and 32 exceeds the differential setting of control 34, this indicates that overdrying would occur, and the differential control 34 will function to inactivate the supplemental heating means. Drying will then continue utilizing air which has not had supplemental heat added thereto, other than the small amount resulting from the operation of the fan and motor. The differential temperature then will tend to work back toward the range set on the differential con-trol 34, and if the differential temperature becomes less than the amount set on control 34, the thermostat may again cause the heat lamps 21 to become activated, adding heat to the drying air.
Now, with respect to the embodiment shown in Figure 4, in its operation, the heat lamp 42 will only operate when the contacts of both the termostat and the differential controller 34 are closed. Consequently, in order for the heat lamp to operate, the temperature sensed in the plenum ~09056Z
by sensor 46 must be below the preset temperature of thermostat 33 in order to have the contact in thermostat 33 closed, and the different$al tempera-ture between 36 and 46 (in the exhaust and plenum chambers, respectively) must be less than the differential setting on differential controller 34.
It will be understood that thermostat 33 and differential controller 34 respond automatically to close the contacts as well as to open them to provide a fully automated control.
Claims (12)
1. A grain drying bin of the type having a plenum chamber formed in the lower part thereof and a gas-pervious floor forming the top of the plenum chamber, said grain drying bin comprising:
means for introducing atmospheric air into the plenum chamber; and electrical heating means for adding heat energy to the air in the plenum chamber, said electrical heating means including a plurality of heat lamps mounted on the lower part of the bin adjacent the plenum chamber.
means for introducing atmospheric air into the plenum chamber; and electrical heating means for adding heat energy to the air in the plenum chamber, said electrical heating means including a plurality of heat lamps mounted on the lower part of the bin adjacent the plenum chamber.
2. The grain drying bin as claimed in claim 1, and further including:
means for determining the temperature of air in the plenum chamber;
means for determining the temperature of air as it exhausts the bin;
thermostat means responsive to the temperature of the air in the plenum chamber for controlling the operation of said heating means;
and means, adapted to override said thermostat controlling said heating means and to inactivate said heating means when the temperature difference between the drying air in said plenum chamber and the air exiting said bin is greater than a predetermined amount.
means for determining the temperature of air in the plenum chamber;
means for determining the temperature of air as it exhausts the bin;
thermostat means responsive to the temperature of the air in the plenum chamber for controlling the operation of said heating means;
and means, adapted to override said thermostat controlling said heating means and to inactivate said heating means when the temperature difference between the drying air in said plenum chamber and the air exiting said bin is greater than a predetermined amount.
3. The grain drying bin as claimed in claim 2 and further inclu-ding:
a plurality of heat lamps spaced about said bin wall adjacent said plenum chamber and having a total output of 10 to 40 watts per one hundred bushels of bin capacity.
a plurality of heat lamps spaced about said bin wall adjacent said plenum chamber and having a total output of 10 to 40 watts per one hundred bushels of bin capacity.
4. The grain drying bin as claimed in claim 3 and further including:
a plurality of fans distributed about the wall of the plenum chamber;
each fan being individually controlled and including closure means to prevent air from exiting said plenum chamber when the fan is inactivated.
a plurality of fans distributed about the wall of the plenum chamber;
each fan being individually controlled and including closure means to prevent air from exiting said plenum chamber when the fan is inactivated.
5. The grain drying bin as claimed in claim 4 and further including transparent heat lamp mounting plates detachably secured to said bin wall.
6. The grain drying bin as claimed in claim 2 and further including means for indicating the amount of air being introduced into said plenum chamber.
7. The grain drying bin as claimed in claim 1 wherein said heat lamps emit radiant energy
8. The grain drying bin as claimed in claim 1 wherein said heat lamps emit radiant energy in the infrared wavelengths in the electromag-netic spectrum.
9. A grain drying bin of the type having a plenum chamber formed in the lower part thereof, a gas-pervious floor forming the top of the plenum chamber and an upstanding plenum chamber wall forming the sides of the plenum chamber, said grain drying bin comprising:
means for introducing atmospheric air into said plenum chamber, including at least one fan tube attached to said plenum chamber wall; and electrical heating means for adding heat energy to the air in the plenum chamber, said electrical heating means comprising a plurality of heat lamps attached to and spaced around said plenum chamber wall, said plurality of heat lamps also being spaced apart from said fan tube on said plenum chamber wall.
means for introducing atmospheric air into said plenum chamber, including at least one fan tube attached to said plenum chamber wall; and electrical heating means for adding heat energy to the air in the plenum chamber, said electrical heating means comprising a plurality of heat lamps attached to and spaced around said plenum chamber wall, said plurality of heat lamps also being spaced apart from said fan tube on said plenum chamber wall.
10. The grain drying bin as claimed in claim 9 wherein said heat lamps include means for emitting infrared rays.
11. The grain drying bin as claimed in claim 9 further including a plurality of fan tubes having fans therein spaced around and attached to said plenum chamber wall, each of said fan tubes and said heat lamps being spaced apart from each other around said plenum chamber wall.
12. A grain drying bin of the type having a plenum chamber formed in the lower part thereof and a gas-pervious floor forming the top of said plenum chamber, said grain drying bin comprising:
means for introducing atmospheric air into said plenum chamber; and electrical heating means for adding heat energy to the air in said plenum chamber, said electrical heating means comprising a plurality of heat lamps spaced about the plenum chamber.
means for introducing atmospheric air into said plenum chamber; and electrical heating means for adding heat energy to the air in said plenum chamber, said electrical heating means comprising a plurality of heat lamps spaced about the plenum chamber.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA340,270A CA1090562A (en) | 1975-10-27 | 1979-11-21 | Grain drying bin |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA238,392A CA1086052A (en) | 1975-10-27 | 1975-10-27 | Method and apparatus for controlling the drying and cooling of field harvested seeds in storage |
| CA340,270A CA1090562A (en) | 1975-10-27 | 1979-11-21 | Grain drying bin |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1090562A true CA1090562A (en) | 1980-12-02 |
Family
ID=25668121
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA340,270A Expired CA1090562A (en) | 1975-10-27 | 1979-11-21 | Grain drying bin |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1090562A (en) |
-
1979
- 1979-11-21 CA CA340,270A patent/CA1090562A/en not_active Expired
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