Note: Descriptions are shown in the official language in which they were submitted.
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GRAIN DRYING AND STORAGE SYSTEM
Field of the Invention
The Present invention relates to grain drying and storage systems with
rotating drum
and, more particularly, to a computer controlled grain drying and storage
system which
operates in response to the measured moisture contents and temperatures of the
grain to be
dried and for storage.
Background of the Invention
Once a cereal crop is harvested, it may have to be stored for a period of time
before it
can be marketed or used as feed or seed. The length of time cereal can be
safely stored will
depend on the condition it was harvested and the type of storage facility
being utilized. Grain
binned at lower temperatures and moisture contents can be kept in storage for
longer
periods of time before its quality will deteriorate.
The moisture content of freshly harvested grain is too high for storage right
away. The
moisture content must be lowered before storage to prevent spoilage. For corn,
a moisture
content of 17 to 18 percent is considered the maximum desirable moisture
content for short
term storage. A moisture content of 15.5 percent is considered optimum by
commercial
grain elevator operators. For long term storage of the grain, 14 percent is
preferred to retard
spoilage.
There are a number of types of grain dryers in current use. When dryers
operate,
generally, large volumes of air at relatively high temperatures are passed
through grain in a
drying chamber. The removal of too much moisture is wasteful of drying energy
and usually
results in shrinkage which decreases the sale value of the grain. If the
moisture is removed
too rapidly, damage to the grain results. But on farms, harvest season time is
limited. The
moisture content of dried grain is 15.5 percent or higher. Some grain from
different sources
will be storage in same storage bin with different moisture content of grain
layers.
To maximize storage life and prevent moisture migration and buildup, most
grain bins
in current use are equipped with aeration system (see Fig.ref.01). Aeration is
the process of
ventilating stored grain at low air flow rates with the purpose of maintaining
a fairly uniform
grain temperature throughout the bin to prevent moisture accumulation at the
top (or
bottom) layers of the bin due to natural convection. The principal objective
of the aeration
system is: the air-blower unit (Ref 01 of Fig.ref.01) blows aerating air into
the plenum
channel.
Normally air is forced into the bin from the bottom (Ref 02 of Fig.ref.01)
through a fully
perforated floor and exhausted through the roof vents (Ref 03 of Fig.ref.01).
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The key to success is to move the drying zone through the top of the grain
mass within
the allowable storage time. As shown in FIG.ref 02, at the time grain is first
stored, a higher
airflow is required to drop down the moisture content of grain to safety level
such as 14
percentage as soon as possible. Then the high airflow rate maintains to
complete drying
grain until the grain temperature drops down to such degree as 15 C before
grain spoils.
At the time grain is first stored, grain moisture content should be fairly
uniform
throughout the bin, but if the grain from different sources or with time,
localized high
moisture zones may develop due to changes in outdoor air temperatures. The low
outside
temperature cools the grain nearer the wall. This results in a downward air
flow through the
grain and upward towards the centre of the bin. As the air moves through the
grain it
becomes warmer and begins to pick up moisture from the grain. Condensation
occurs when
the warm moist air hits the cool surface of the grain near the centre of the
bin, (Ref 04 of
Fig.ref.01) thus leading to grain spoilage.
In most types of grain storage methods of the current use, another problem of
those
grain storage systems is: in order to safely store grain, the aeration system
should provide a
minimum of 1/10 cubic foot per minute (cfm) of air for each bushel aerated.
But the air flow
effect is low, because air flow rates pass through all grain layers from
chamber bottom to the
headspace of bin. And horsepower of blower motor will rapidly increase when
grain level
increases in the chamber.
Summary of the Invention
The present invention provides a rotating drum and automatic control
arrangement for
grain drying and storage based on capacitive moisture content and temperature
measurement. The drying and storage equipment includes a rotating drum as a
bin having
two static end-stops, and one separated heating/aerating/cooling combination
unit with
plenum controlled valves.
The grain is filled into the horizontal drum from front static end-stop, named
in-feed
end. The drum rotates at between 0.5 and 5 rotations per minute (rpm) without
damaging
grain. A grain moisture content sensor for moisture content measurement, which
is mounted
at the static end-stop, contacts with grain in the rotating drum. A grain
temperature sensor
provides a grain signal.
The grain is discharged from the lower discharge end. Drum is driven by large
ring-gears, rubber trunions, or sprockets and chains. The loading and
unloading doors and
the drive mechanisms introduce a higher degree of mechanical complexity or
electrical
drives and maintenance requirements relative to other devices if needed.
Air is typically injected into the drums, usually at the feed-in end, to meet
process air
requirements. The drum is loaded to between 65 to 80% of their total volume.
Loading more
material into the drum prevents materials inside from tumbling and reduces
processing
efficiency. A plenum air temperature sensor and a humidity sensor provide the
air signal for
optimizing the grain drying/aeration/cooling operation.
A heater/chiller/blower combination unit with plenum system provides heated,
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aerating or cooled air into the drum for drying and storage grain.
The plenum air temperature signal, air humidity signal, grain temperature
signal and
grain moisture content signal etc. are entered into the PLC (Programmable
Logic Controller)
or other kinds of computer. The PLC or computer is programmed to operate the
grain drying
and storage system with the set parameters, to monitor the system for
malfunctions, to
respond to Such problems by correcting the problem if possible or by shutting
the system
down and sounding an alarm, to print out report of the operation, and to
remote SCADA
system (Supervisory Control and Data Acquisition).
-An ambient air temperature sensor and an ambient humidity sensor which
monitor
ambient conditions, provide signals to PLC control system for automatic
running system for
year- round grain storage. The system is capable of reliable operation without
the attention
of an operator and is characterized by a high output and high quality of the
processed grain.
Objectives of the Invention
The principal objectives of the present invention are: to provide an improved
grain
drying and storage system; to provide such a system which results in a
superior grain
product which has a high uniformity of the desired moisture content; to
provide a
heater/chiller/blower combination unit with plenum system in response to the
measured
grain moisture content and temperature; to rotate the drum to move the grain
from bottom
to the top in the drum; to force air to carry the moisture content of grain
and/or high
temperature air out of the drum to reach the desired moisture content or
temperature levels;
to provide such a system wherein a startup drying air temperature and a
maximum air
temperature and the desired grain moisture content are set by an operator and
are
monitored by the control system to optimize the drying operation; to provide
such a system
wherein a startup cooling air temperature and a minimum air temperature and
the desired
grain temperature are set by an operator and are monitored by the control
system to
optimize the storage operation; to provide such a system which monitors
various
parameters of the grain drying system and storage and which controls the
process in
response to such parameters; to provide such a system which will function
reliably without
human intervention; to provide such a system which includes a computer and
network
system which collects and responds digital signals and analog signals; to
provide such a
system which includes soft-touch screens HMI (Human Machine Interface) and PC
base
monitors to display processing sequence, controls and historic data; to
provide such a
control system which averages the moisture content readings and which adjusts
the
temperature of the heated drying air in response to the relationship of each
individual
reading to the current average to expedite the processing of grain through the
drying system;
to provide such a control system which adjusts the speed of the blower in
response to the
relationship of each individual reading to the current average to expedite the
processing of
grain through the aeration system; to provide such a control system which
start/stop the
chiller and blower in response to the relationship of each individual reading
to the current
average to expedite the processing of grain through the cooling system; to
provide such a
control system which is reliable and energy efficient in operation, and which
is particularly
well adapted for its intended purpose.
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Other objects and advantages of this invention will become apparent from the
following
description taken in conjunction with the accompanying drawings wherein are
set forth, by
way of illustration and example, certain embodiments of this invention.
The drawings constitute a part of this specification and include exemplary
embodiments of the present invention and illustrate various objects and
features thereof.
Brief Description of the Drawings
FIG. 01 is a sectional view of a grain drum and heater/chiller combination
blower unit and
plenum system in which the grain drying and storage system according to the
present
invention is installed.
FIG. 02 is a sectional view of front static end-stop, named in-feed end, of
the drum in which
the grain can be filled into the drum, and the plenum air can be forced into
the drum
according to the present invention is installed.
FIG. 03 is a sectional view of back static end-stop, named the lower discharge
end, of the
drum in which the grain can be discharged from the drum, and the moisture and
warm air
can be exhausted from the drum when drying or aeration operation, or as the
outlet for the
warm air cycling back to chiller unit, according to the present invention is
installed.
FIG.04 is a diagrammatic sectional view of relationship of the rotate drum,
both static
stop-ends, drum drive motors and base.
FIG.05 is a diagrammatic sectional view of the moisture content sensor
installation on the
in-feed end.
FIG. 06 is a block diagram illustrating the principal computer interface of
the control system.
Detailed Description of the Preferred Embodiment
Detailed embodiments of the present invention are disclosed herein; however,
it is to
be understood that the disclosed embodiments are merely exemplary of the
invention which
may be embodied in various forms. Therefore, specific structural and
functional details
disclosed herein are not to be interpreted as limiting, but merely as a basis
for the claims
and as a representative basis for teaching one skilled in the art to variously
employ the
present invention in virtually any appropriately detailed structure.
Referring to the drawings in more detail
The reference numeral 1. generally designates a computer controlled grain
drying and
storage system according to the present invention. The exemplary grain drying
and storage
system 1 generally includes a grain rotate drum 2, front static stop-end named
in-feed end 3,
back static stop-end named the lower discharge end 4, a air heater and a
chiller and a blower
combination unit 5, Plenum air control system with ducts and control valves 6,
a system
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controller or control computer panel 7.
A quantity of wet grain 8 is loaded into the drum 2 from filling windows 19 on
in-feed
end 3, and heated air from the unit 5 is passed through the top wet grain
layer 9 to dry same.
The moisture air exhaust from the system exhaust outlet 10, and same time
control valve 6-2
is closed for isolation, control valve 6-3 is opened for the moisture air
exhausting from the
drum, control valve 6-1 is opened for fresh air keep going into the unit 5.
The drum is sitting on 4 drive wheels 11-1, 11-2, 11-3 and 11-4, each drive
wheel
connected with its gearbox and driven by a motor. The computer adjusts the
motors running
speed and direction. The motors with the gearboxes drive the drum to rotate in
lower speed.
Periodically, the wet grain on the bottom of drum is turned over to the top
position of the
grain in the drum. The moisture content of the grain in drum is measured by
moisture
content sensor 12; and in response to the measured moisture content, the
drying process is
continued until the moisture content measured value reach the desired level,
such as 14%.
The grain drying and storage drum 2 is not a conventional type of static grain
bin,
instead of combination by three parts: a static front stop-end 3 and a static
back stop-end 4,
and rotate drum 2. The drum 2 is a horizontal cylinder which sitting on 4
drive wheels 11-1,
11-2, 11-3 and 11-4, and a base 13. (See FIG. 04) . Although not illustrated,
the drum 2 is
preferably of foam isolation or a double wall construction for insulation
purpose.
Internally, the drum is filled with grain about 70% total volume, the top of
the grain in
the drum is lower than plenum air inlet 14 and moisture air exhaust outlet 16,
inside of the
drum, there is a space, named headspace 15, for the air flow.
The Heater/chiller/blower combination unit 5 communicated with the plenum
system
6, include air flow duct and control valves 6-1, 6-2 and 6-3. (See FIG.01,
FIG.02, FIG.03). The
unit 5 includes a fuel burner, or electrical heater to heat air, and include
electrical chiller to
cooling air, both burner and chiller cooperate with a fan or blower. The
heater unit includes
fuel valves to control the flow of fuel such as natural gas or the like to the
burner; and the
unit 5 includes a high fire valve for drying grain purpose, and a low fire
valve for remove
moisture from grain for long term grain storage purpose. Other type of valves
arrangements
such as modulating, proportioning, throttling valves, or the like could also
be employed for
best control and save energy purpose.
When drying grain, the valve 6-1 is open, the fresh air going into the unit 5,
and the unit
is operative to heat air which is propelled by the blower into the plenum
system 6. The
heated air expands upon entry into the plenum 6 and is forced into the
headspace 15 of
drum 2 by the blower. The drying action occurs in the drying zone or top layer
of grain 9
with the upper levels receiving virtually no drying action because of
saturation of the air
with moisture from grain in the drying zone 9. In order to monitoring the
drying process, the
plenum 6 is provided with a -plenum air temperature sensor 17, and the drum
may be
provided with a grain temperature sensor 18 which is located to sense the
temperature of
the lower layer of grain 9. A grain temperature sensor would be desirable in a
rice and seeds
dryer and storage system because the greater sensitivity of rice and seeds
than other grains
to damage- from overheating. The blower may be capable of operating
independently of the
burner and chiller for long term storage aerating operation to cooling the
grain. Such action
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is desirable when long term grain storage in drum to prevent spoilage of the
grain which
would be accelerated because of the elevated temperature.
The grain drying and storage drum 2 is loaded with grain from in-feed window
19, (see
FIG. 02) specifically, the in-feed window 19 locate at upper center of in-feed
end 3. Grain is
unloaded from the discharge gate 20 which locate at lower center of discharge
stop-end 4
(see FIG. 03).
The drum 2 is driven by 4 drive wheels 11-1, 11-2, 11-3, 11-4, and the wheels
are
driven by the gearboxes with motors, the gearboxes reduce motor speed to lower
speed, and
motor speed adjusted by VFD (Variable Frequency Drive) unit installed inside
of the control
panel 7. Drum rotate Maximum speed can be set by operator from soft-touch
screen on
control panel 7 to avoid damage the grain due to drum rotate too fast.
The grain moisture content measuring sensor 12 illustrated in FIG.05 , the
sensor 12 is a
digital microwave moisture sensor, and designed to be installed in bins, soils
and conveyors
in process control environments . This modern sensor with stainless steel body
12-2 and
ceramic faceplate 12-3 construction, the sensor is mounted on the wall of in-
feed end 3,
measuring the moisture content of grain 8 in the drum.(see FIG.05). the sensor
12 is
designed to suit the flow characteristic of the material, when the drum 2
rotating, the grain
turning and moving inside of drum, the sensor 12 accurately measures the
moisture content
of grain 8 as it flows over the ceramic faceplate 12-3, measuring at 25 times
per second and
with on-board functionality such as signal processing and averaging. The
sensor 12-1
provides 4 ¨ 20 mA current loop source to PLC or computer for grain drying and
storage
processing control. The moisture content measurement shown in FIG. OS is
exemplary, and
other automatic sampling arrangements may be employed without departing from
the spirit
of the present invention.
Plenum system 6 has three control valves 6-1, 6-2 and 6-3. (see FIG.01,
FIG.02, FIG.03),
for the system 1 running under the different functions: grain drying function,
aeration
function for long term storage, cooling function for long term storage.
When the system 1 operating under grain drying function, the valve 6-1 is
open, fresh
air going into the unit 5, the air is heated by the heater, the blower forced
the heated air into
headspace 15 in the drum 2, the valve 6-2 is closed and the valve 6-3 is open,
the air with the
moisture from the grain 8 exhausts to outlet 16, due to the valve 6-2 is
closed, the moisture
air cannot return to the unit 5, the moisture air passes the valve 6-3 which
is open and the
system air outlet 10 to atmosphere.
When the system 1 operation under aeration function for long term storage, the
PLC or
computer 7 turn OFF the heater and chiller in the unit5, turn ON the blower in
the unit 5, the
fresh air passes the valve 6-1 which is open into the unit and forced by the
blower into the
headspace 15, the aeration air push the existing warm air in the drum 2 out to
the outlet 16,
due to the valve 6-2 is closed, the warm air cannot return to the unit 5, the
warm air passes
the valve 6-3 which is open and the system air outlet 10 to atmosphere. The
grain is cooled
down for the grain safety storage.
When the system 1 operation under cooling function for long term storage, such
as
summer and ambient humidity is high, isolate the air from ambient into the
drum 2 and
operating the chiller for cooling the air in the headspace 15 as air condition
system, to keep
the grain in the drum 2 in desired temperature level such as 15 C. the PLC or
computer turn
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OFF the heater and turn ON chiller and the blower in the unit 5, the valve 6-1
is closed to
isolate the air from atmosphere into the unit, and the cooled air is forced by
the blower into
the headspace 15, the cooled air push the existing warm air in the drum 2 out
to the outlet
16, due to the valve 6-3 is closed, the atmosphere air is isolated, and the
valve 6-2 is open,
the warm air return to the chiller in the unit 5 to cool down. The air is
cycling between the
chiller in the unit 5 and headspace 15 to keep the grain in safety storage
temperature level.
The humidity sensor 21 which is mounted on the wall of the discharge end 4,
measures
the humidity of the air in headspace 15 for best processing control under
grain drying
operation and aeration operating for long term storage.
An ultrasonic level sensor 24 is mounted on the upper location of the wall of
the
discharge end 4 to measure the height of grain in the drum 2 for the
processing monitor and
control.
FIG. 06 illustrates the major components of the control system in the panel 7
of the
grain drying and storage system 1. The principal control component is a the
microprocessor
of PLC unit (Processing Logic Controller) or digital computer 26, it cooperate
with soft-touch
screen HMI ( Human Machine Interface) 27, and signal input model 28, control
output model
29. The microprocessor 26 may employ any of a number of suitable
microprocessors which
are commercially available. Whil the soft-touch screen HMI 27 provides
diagnostic
information to an operator. The operating equipment such as sensors, valves
and alarm light
etc of the system 1 is interfaced to the PLC unit by Input/output(I/0)
interface unit. In
general, the signal input model 28 has the digital moisture sensor 12, Plenum
air
temperature sensor 17, Grain which in the drum 2 temperature sensor 18, the
air humidity
sensor 21 which measuring the air humidity level in the headspace 15, a
ultrasonic level
sensor 24 for measuring the grain height inside of the drum 2. In order to
storage grain
year-round time long, an atmosphere temperature sensor 22 and an atmosphere
humidity
sensor 23 provide the ambient condition for the system control.
The I/O unit control output model 29 commands to heater/chiller/blower unit 5,
Plenum air system 6, motors which drive the drum 2 to rotate, extra exhaust
fan 26, alarm
light 30, buzzer 31 for an operator, safety interlock 32 if need for some
safety reasons,
remote control signals 33 for other equipments which related with the system 1
such as a
grain feed in system or devices. The equipments of the system 1 as will be
detailed herein
below.
FIG.06 illustrates details of the interface as signal input models 28, the
sensors
monitored by the microprocessor CPU unit 26. The operating equipment of the
system 1 is
interfaced to CPU unit 26 through the control output models 29. The signal
input models 28
may be digital signal input DI model and analog signal input Al model, the
control output
models 29 may be digital signal DO model and analog signal output AO model.
The CPU unit
26, model 28 and model 29 may be any one of a number of commercially devices.
Such as
Allen-Bradley PLC or Siemens PLC.
The Digital moisture sensor 12 is a microwave moisture sensor, provides 4 ¨ 20
mA
current loop source to analog signal input model 28; the temperature sensor 17
and 18, are
preferable RTD with 4 ¨ 20 mA transmitter, the 4 ¨ 20 mA signals are provided
to the analog
input model 28 for monitoring pletnim air temperature changing and the grain
temperature
changing. Same way, when the system operating for long term grain storage,
atmosphere
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temperature is monitoring by RTD and its transmitter 22. A humidity sensor
provides 4-20
mA signal is used as drum air humidity sensor 21, and another humidity sensor
23 is used
for monitoring atmosphere humidity for best control. An ultrasonic level
transmitter is
employed for measuring the grain volume by measuring height of grain in the
drum 2.
If need, some digital input signals can be used for monitoring the equipment
operating
status, such as the heater is ON or OFF, the chiller is ON or OFF, the blower
is ON or OFF, the
drum 2 is rotating or stop, the fresh air valve 6-1 is Open or Close position,
the isolation valve
6-2 is Open or Close position, the exhaust valve 6-3 is Open or Close
position.
One specific status sensor is a drum humidity sensor 21 which is positioned in
the
headspace 15 of the drum and nearby the outlet 16 to determine if humidity
level reach the
desired humidity level or humidity set-point. If the sensor 21 indicates a
very high level
humidity of grain, the heater will be started to remove the moisture of the
grain; if the
sensor 21 indicates a level higher than set-point, the blower will be on in
high speed and
system operating under aeration mode.
The functions of the system 1 which are controlled by the PLC unit 26 include:
the
blower, the high fire valve, the low fire valve, the chiller, speed of motor
of the blower can be
adjusted by a VFD (Variable Frequency Drive), a analog control output model is
employed to
provide 4-20 mA signal to the VFD for changing the blower's rotate speed. When
the
system 1 is operating under grain drying mode, the blower should operate as
maximum
rotating speed.
The high fire valve and the low fire valve are used for effetely remove the
moisture of
the grain and protect to avoid temperature too high for the grain.
The plenum 6 control valves 6-1, 6-2 and 6-3 are controlled by PLC with
programming
sequence. When the system is operated as grain drying, the fresh air valve 6-1
is open, the
fresh air goes into the heater, and the exhaust valve 6-3 is open, the
moisture air of the grain
is exhausted through the valve 6-3 to atmosphere; when the system is operated
as a aeration
period for long term grain storage, the fresh air valve 6-1 is open, the fresh
air is forced by
blower, while both of the heater and the chiller are OFF, and the exhaust
valve 6-3 is open,
the existing warm air in the drum 2 is forced out to atmosphere through valve
6-3, and
isolate valve 6-2 is controlled to close to avoid the warm air returns back to
the blower;
when the system is operated as cooling period of grain long term storage, the
valve 6-1 and
the valve 6-3 are closed, the isolate valve 6-2 is open, the drum and the unit
5, and plenum 6
are enclosed to isolate from the ambient, the air is cooled by the chiller,
and is forced by the
blower to entry the drum, the warm air return to the chiller through the valve
6-2, and the
warm is cooled by the chiller and send back to the drum 2, the cycling is
continue until the
temperature of the grain is cooled down to desired level or set-point such as
15 C. Each of
these functions is controlled through the PLC or computer output interface
models.
The drum cylinder 2 is made by carbon steel or stainless steel, the drum
cylinder sitting
on four solid steel wheels or solid rubber wheels, the wheels are driven by
the motor and
gearbox combination units. In drying operation of the systeml, the drum with
about 70%
full of wet grain, an operator turn on the system 1 from HMI 27 on the control
panel 7 and
sets the desired grain moisture content, the maximum plenum temperature, a
blower
start-up temperature for plenum 6, and the current time. The system 1 is then
controlled by
the PLC or computer 26 to take an initial moisture reading and activating the
motors of drive
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solid wheels to cause the rotating of the drum2. While this is occurring, the
heater is ignited,
and the PLC control system 26 is set to automatic operation. If the grain is
wetter than
desired, a waiting period is initiated in proportion to the difference between
the measured
moisture content and the desired moisture content. The heating unit 5 is
cycled in such a
manner as to dry the grain 8 most efficiently If the initial cycle is as dry
as or dryer than
desired, the drum 2 will be stopped; the grain will be unloaded from the drum
2, or keep the
grain in the drum 2 for long term storage. In the automatic mode of operation,
moisture
readings are taken at selected intervals of time, and the heater unit 5 and
the rotating drum 2
are automatically controlled in response to the moisture content and sensed
temperatures.
The system 1 will shut itself down upon the occurrence of predefined
malfunction and
display diagnostic messages on HMI 27, or on a remote screen. The grain level
sensor 24
senses the grain height in the drum 2 and display on HMI 27, the grain level
sensor 24
provides the signal of grain volume in drum 2 to PLC as reference for
adjusting the rotating
speed of drum 2.
In a preferred mode of operation, an initial moisture content reading is
taken. If the
reading is wetter than the desired moisture content, a wait period is
initiated during which
the heater unit 5 is cycled to maintain the start-up temperature. After the
initial moisture
content measurement, the subsequent moisture readings are averaged up to a
selected
maximum, for example, four readings including the current reading. After the
first reading,
as each reading is taken and determined to be wetter than desired, the PLC
unit 26 cycles the
heater unit 5 to maintain an incrementally higher drying air temperature. As
soon as either
the current reading or the average moisture content is reduced to the desired
moisture
content, the buzzer will be ON; an operator will remove grain from drum 2, or
forward to
next process step for long term storage.
Thereafter, the drying air temperature is adjusted, by cycling the heater unit
5 through
the high and low fire valves 5-1 and 5-2, to accommodate variations in the
moisture content
of the grain in drum 2. The PLC unit 26, therefore, discerns a trend in the
moisture content of
grain in drum 2 and adjusts the maintained drying air temperature in
accordance with short
term variations in the moisture content as measured. For example, if the
average moisture
content is as dry as desired, but the currently measured moisture content is
too wet, the
maintained drying air temperature is increased. Conversely, if either the
average or current
moisture drops below the desired moisture percentage, the maintained air
temperature is
reduced to prevent over-drying. Before each increase in air temperature, the
currently
maintained drying air temperature is compared to the set maximum temperature
to prevent
"cooking" of the grain from excessive heat. The object is to adjust the drying
air temperature
in such a manner as to uniformly dry the grain while operating the drum 2
rotating as
continuously as possible. This allows the drying process to proceed as rapidly
as possible
commensurate with high uniformity of moisture content of the grain in the drum
2. The
control method as described herein retains the energy efficiency associated
with heater unit
controlled by PLC unit 26.
The grain drying and storage system 1 significant advantage over previously
employed
grain dryer systems and grain storage systems. Drying operation is controlled
in relation to
directly measured grain moisture content by the sensor 12 rather than moisture
content
related to temperature measurements which is subject to a greater number of
variables.
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Start up with the system 1 is faster and more efficiency for the operator
since it is not
necessary to wait for equilibrium conditions to be established as in systems
in which control
is based on temperature derived moisture content. The system 1 continuously
adjusts the
drying temperature for maximum drying rate and monitors the operation to
prevent
over-drying of the grain.
The monitoring and display of the status of the grain drying processing, if
malfunctions
occur alarm lighting will be on, and the historic processing data and alarm
records can be
checked by the operator through soft-touch screen HMI 27, and can be remotely
checked
from SCADA system. Because the operation is closely monitored and controlled
in response
to monitored conditions, greater throughput and efficiency can be attained.
Finally, the
system 1 does not require a high degree of skill to operate and can run for
the most part
without human intervention.
Further, it is possible that other types of non-manual moisture measuring
devices could
be advantageously employed. Therefore, it is to be understood that while
certain forms of the
present invention have been illustrated and described herein, it is not to be
limited to the
specific forms or arrangement of parts described and show.
