Note: Descriptions are shown in the official language in which they were submitted.
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APPARATUS AND METHOD FOR PRODUCING ACTIVATED CARBON
CROSS-REFERENCE AND PRIORITY CLAIM TO RELATED APPLICATIONS
To the fullest extent permitted by law, the present
application claims priority to and the benefit as a patent
cooperation treaty application to U.S. nonprovisional patent
application entitled "APPARATUS AND METHOD FOR PRODUCING
ACTIVATED CARBON", filed on January 22, 2004, and to U.S.
provisional application entitled "APPARATUS AND METHOD FOR
PRODUCING ACTIVATED CARBON", filed on January 23, 2003, having
Serial No. 60/442,041.
TECHNICAL FIELD
The present invention relates generally to charcoal
activation processes, and more specifically to an apparatus and
method for charcoal activation.
BACKGROUND OF THE INVENTION
Going back over many hundreds of years, the technology for
the carbonization of hardwoods for production of crude charcoal
has remained unchanged.
Specifically, in the past century, various improvements, in
traditional charcoal producing processes, have been introduced,
resulting in a charcoal product containing less impurities and
volatiles.
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Additionally, utilizing Rotary Kilns, Multiple Hearth
Furnaces, Fluidized Bed Reactors, Vertical Retorts, Gasifiers,
or the like, improved charcoal has been converted into activated
charcoal via high temperatures in a non-oxidizing or partially-
oxidizing environment.
Unfortunately, many such systems and processes are
typically costly, and require much energy. Moreover, many such
systems and processes are still unable to yield desired
quantities of quality charcoal.
Therefore, it is readily apparent that there is a need for
a an apparatus and method for charcoal activation, wherein a
multipurpose furnace system is utilized to manufacture high
grade charcoal from hardwood starting materials, which, in turn,
promotes the manufacture of activated charcoal, while providing
a viable and significant cost saving alternative to ongoing,
intensive worldwide, efforts to increase yield and quality of
charcoal product.
BRIEF SUML~IARY OF THE INVENTION
Briefly described, in a preferred embodiment, the present
invention overcomes the above-mentioned disadvantages and meets
the recognized need for such a device by providing an apparatus
and method for charcoal activation, wherein a multipurpose
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furnace system is utilized to manufacture high grade charcoal
from hardwood starting materials, which, in turn, promotes the
manufacture of activated charcoal, while providing a viable and
significant cost saving alternative to ongoing, intensive
worldwide, efforts to increase yield and quality of charcoal
product.
According to its major aspects and broadly stated, the
present invention in its preferred form is an apparatus and
method for charcoal activation having an improved furnace system
that electrically and internally generates energy within the
charcoal bed.
More specifically, the present invention is an apparatus
and method for charcoal activation, wherein the invention
proposed herein represents a lateral shift different from the
present charcoal activation systems in that the energy is not
externally sourced, but rather electrically and internally
generated within the charcoal bed. This is accomplished by
passing an electrical current through the charcoal bed as a
result of imposing a voltage across the extremities of the
charcoal bed.
The electrical current flows between electrodes, positioned
at the top and bottom of the refractory column of the furnace,
in contact with the charcoal. An electrical current passing
through the bed in this way results in a uniform temperature
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rise within the bed due to the resistive heating effect (i~~.e.,
volts x current = watts).
The applied voltage can be varied to control the heating
effect, and consequently the temperature rise in the bed, in a
uniform and predictable way.
Accordingly, a feature and advantage of the invention is
its ability to provide improved energy requirements (i.e., as
l0 ICcals/lb of activated charcoal) versus conventional systems.
A feature and advantage of the invention is its ability to
provided improved yield, based on dried wood chips to activated
charcoal versus conventional systems.
A feature and advantage of the invention is its ability to
provide a 2o attritional loss per cycle, based on subsequent
discharged activated charcoal to storage versus a 250 loss of
conventional systems.
A feature and advantage of the invention is that no
contamination is introduced into the charcoal bed, as opposed to
conventional internally heated rotary kilns, multiple hearth
furnaces, gasifiers, vertical retorts and fluidized bed reactors
that have a tendency to introduce contamination via inert hot
gases.
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These and other features and advantages of the present
invention will become more apparent to one skilled in the art
from the following description and claims when read in light of
the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be better understood by reading
the Detailed Description of the Preferred and Alternate
Embodiments with reference to the accompanying drawing figures,
in which like reference numerals denote similar structure and
refer to like elements throughout, and in which:
FIG. 1 is an illustration of an apparatus for charcoal
activation according to a preferred embodiment of the present
invention;
FIG. 2 is an illustration of an apparatus for charcoal
activation according to a preferred embodiment of the present
invention;
FIG. 3 is an illustration of an apparatus for charcoal
activation according to a preferred embodiment of the present
invention;
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FIG. 4 is an illustration of an apparatus for charcoal
activation according to a preferred embodiment of the present
invention;
FIG. 5 is an illustration of an apparatus for charcoal
activation according to a preferred embodiment of the present
invention;
FIG. 6 is an illustration of an apparatus for charcoal
activation according to a preferred embodiment of the present
invention;
FIG. 7 is an illustration of an apparatus for charcoal
activation according to a preferred embodiment of the present
invention; and,
FIG. 8 is an illustration of an apparatus for charcoal
activation according to a preferred embodiment of the present
invention.
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DETAINED DESCRIPTION OF THE PREFERRED
AND AhTERNATIVE EMBODIMENTS
To the fullest extent permitted by law, the present
application claims priority to and the benefit as a patent
cooperation treaty application to U.S. nonprovisional patent
application entitled ~~APPARATUS AND METHOD FOR PRODUCING
ACTIVATED CARBON", filed on January 22, 2004, and to U.S.
provisional application entitled ~~APPARATUS AND METHOD FOR
PRODUCING ACTIVATED CARBON", filed on January 23, 2003, having
Serial No. 60/442,041.
In describing the preferred and alternate embodiments of
the present invention, as illustrated in FIGS. 1-8, specific
terminology is employed for the sake of clarity. The invention,
however, is not intended to be limited to the specific
terminology so selected, and it is to be understood that each
specific element includes all technical equivalents that operate
in a similar manner to accomplish similar functions.
Referring now to FIGS. 1-8, illustrated therein is the
preferred embodiment of the equipment items involved in the
manufacture of product from the raw materials.
Preferably, the basic raw material for the process is
hardwood chips, which can be obtained from many sources but
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preferably from waste product of sawmills and furniture
factories.
The wood chips are sized into particles approximately less
than 10 millimeters in a chipping machine, and then fed by
gravity onto a double deck vibrating screen where the particles
approximately greater than 7 millimeter are returned to the
chipping machine and the particles approximately less than 7
millimeters, but approximately greater than 3 millimeters, are
fed to the sized woodchip feed hopper. It should be recognized
that other suitably-sized chips could be utilized.
Sized wood chips approximately less than 7 millimeters, but
approximately greater than 3 millimeters, and activated charcoal
granules, approximately less than 6 millimeters, but
approximately greater than 3 millimeters, are then blended on an
equal volumetric basis using vibrating feeders which discharge
the blend into a transit bag for gravity feed into the preferred
activation furnace.
The activation process in the activation furnace is
preferably initiated by applying a voltage (i.e., preferably
approximately 500 VDC) across the activated charcoal/woodchip
bed.
Because the activated charcoal granules in the bed are
electrical semi-conductors, when this voltage is applied across
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the vertical extremities of the bed, a specific electrical
current, dependant on the voltage applied and electrical
resistance of the bed, will flow from the top to the bottom of
the bed between the +ve and -ve terminals, as best illustrated
in FIG. 2.
This current flow causes an electrical heating effect in
the bed with the accompanying rise of temperature in the bed,
which can be controlled by varying the voltage, as applied
across the bed, in a uniform and controllable way.
The electrical heating effect is by resistive heating and
is preferably derived by the following computation:
Applied volts x amps (flowing between the electrodes)
1000
- KW energy generated within the bed
The electrical resistance of the bed is dependant on the
following factors:
a) The height and cross sectional area of the bed.
b) The electrical resistivity of the activated carbon
granules (i.e., for the activated charcoal in question
this resistivity value at ambient temperature will
typically be approximately 30 ohm cm
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As such, based upon the values of (a) and (b), above, the
electrical resistance of the bed is computed as follows:
resistivity (ohm cm) x vertical height of bed (cm)
Area of bed (square cm) - ohms
By controlling the imposed voltage across the terminal
electrodes of the bed, a uniform bed temperature throughout the
bed can be accurately controlled, which, in turn, results in the
ability to produce a high quality activated charcoal.
An additional advantage of the process of the current
invention may be found in its exothermic nature. As the voltage
induced temperature rises within the bed, the hardwood chip
material undergoes an exothermic reaction in its reduction to
charcoal. This exothermic reaction serves to drive the bed
temperature upwardly without introduction of additional voltage.
Accordingly, as the process ensues, the net voltage required to
maintain a carbonizing temperature may be downwardly regulated
to save energy.
Accordingly, the advantages of this technology compared to
the existing technologies are as follows:
a) Significant cost saving in energy to produce activated
charcoal;
b) Significant time saving in the production cycle to
produce activated charcoal;
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c) Significant improvement in the yield to produce activated
charcoal from hardwoods;
d) Significant decrease of environmental pollution in the
production of activated charcoal;
e) Significant improvement in the user friendliness of
operating the system to produce activated charcoal; and,
f) Significant decrease in the capital cost of the preferred
furnace system to produce high quality activated
charcoal.
The attached material and energy balances derived from
tests, using the preferred pilot scale furnace, demonstrate the
above claims of novelty and nonobviousness of this technology
compared to technologies presently in use.
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Ecological implications and advantages of the present
invention include, but are not limited to, the following:
a) Up to 3 times less hardwood to manufacture
charcoal, compared to traditional charcoal
production;
b) The present method will produce no greater
pollution than conventional known charcoal
' production processes;
c) The present charcoal, made even more economically,
on a larger scale, by recovering electrical
energy from furnace off gases and blended with
coal to feed power
stations, will reduce pollution.
Having thus described exemplary embodiments of the present
invention, it should be noted by those skilled in the art that
the within disclosures are exemplary only, and that various
other alternatives, adaptations, and modifications may be made
within the scope of the present invention. Accordingly, the
present invention is not limited to the specific embodiments
illustrated herein, but is limited only by the following claims.
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