Note: Descriptions are shown in the official language in which they were submitted.
CA 02646634 2008-12-12
SPECIFICATIONS
Background of the invention
As it is evident, the sustained growth of economy in Chile has led to a
permanent
increase of the energy demand. However, we know that the energy supply has
been
hindered by the country's lack of self-supply; its dependence on other
countries has
been one of its main problems, especially in respect of natural gas supply
from
Argentina.
Once the natural gas gasifying plant in Quintero starts operating, it will
certainly
permit a greater energy supply, although it is known that a higher cost of the
energy will
irremediably exist.
The problem inherent in the energy supply for domestic and commercial use has
been most sensitive, since it involves an important social component. The
energy
destined to heating, food cooking and hot water supply certainly does not
permit any
interruption. In this scenario we could think that one of the natural and
logical
alternatives to be applied are renewable energies, such as firewood and
biomass, which
due to the diversity of climates could represent a significant
alternative, where the Chilean central and south zones - having the greatest
forest
potential for wood production - are found, in addition to the historical
culture of use of
firewood ranges and stoves. As a consequence, mention is made of the problem
of
environmental pollution affecting very important cities of our country, such
as Santiago,
Rancagua, Chillan, Temuco, Osorno and others.
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In effect, for over a decade the goodness of double combustion chamber
firewood stoves appeared to be the solution, since everything suggested that
by being
most efficient they emit less contaminants into the external environment;
however,
everybody knows that there is a major variable, which is difficult to control
by the
agencies entrusted with environmental pollution matters, such as the need to
use
firewood suitable for heating purposes that has a low humidity content (under
20%). For
this reason, it is of little advantage to have a stove manufactured according
to a good
technology if the wood is very humid; therefore, an excessive rise of the
environmental
pollution level is produced, since no practical regulations force the
consumers to use
only wood with 20% humidity or less.
In the practice, users can buy firewood in the informal market at a lower
cost, but
without its fitness for heating purposes being duly guaranteed. According to
statistics
delivered by CONAMA (the National Environmental Commission), it is estimated
that
during the year 2006 over 600 tons of PM 10 particulate material were
discharged in
Santiago, which is attributable to the use of firewood for heating and food
cooking;
these contamination levels are similar to those emitted by the industry and
the overall
collective transportation system of the city.
According to CONAMA, in 2006 over 70,000 firewood stoves were installed in
Santiago and this figure would exceed one million in the country as a whole. A
very
strong expansion level has been projected and it could possibly reach three
million
firewood stoves by the year 2020. The reasons behind this expansion are the
attraction
and coziness offered by open fire stoves, in addition to their considerable
heating
capacity; however, their main attractive lies in their low operating cost;
according to
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studies performed by Universidad Austral de Chile, firewood heating can be up
to 14
times less expensive than electricity, 9 times cheaper than gas and almost 8
times
cheaper than oil.
Firewood represents 17% of the energy consumption in Chile.
The market for firewood appliances in Chile is as follows:
(a) Yearly sales of double chamber combustion stoves: 70,000 units at an
average unit value of CH$150,000.-
(b) Yearly sales of firewood ranges: 80,000 at an average value of CH$
140,000.-
Summary of the invention
The present invention consists in contributing an appliance that uses biomass
as
fuel, equipped with closed combustion chamber, which incorporates a fuel
feeding
system in the form of briquets made of pressed sawdust using a high tonnage
press.
This fuel has been designed for the appliance according a specific geometric
shape and
dimensions, which is loaded to the stove around the combustion chamber. The
fuel
drops by gravity into the lower portion of the heater; next, each briquet is
raised through
the side portion of the supporting structure of the appliance by means of an
internal
conveyor.
The movement of the fuel (briquets) conveyor is performed by a stepper
electric
motor, i.e. the motor feeds the briquets one by one into the fuel chamber
according to
the heating needs of the environment by means of a thermoelectric control
mechanism.
The main characteristics of the present invention are the following:
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(a) TO ESTABLISH A SINGLE AND REGULAR FUEL. The combustion chamber is
closed in the front part and the user has no direct access to it, as it is now
the case with
all firewood stoves; it can be provided with a glass window that only permits
to see the
fire inside the chamber. In respect of the chamber, the appliance can only
operate with
a predefined fuel and not in the way the user commonly proceeds today, wherein
very
humid wood can be used without controlling the size and load of the combustion
chamber.
The briquets are produced according to predefined standards of humidity,
density, dimensions and raw material involved. This fuel can be sold in the
formal
market inside a suitable packing that maintains the original humidity content,
preferably
not higher than 20%.
(b) AUTONOMY OF THE APPLIANCE. The standard strove considers a briquets
transportation circuit that permits to load the unit with about 20 briquets of
approximately 500 grams each, i.e., a 10 kg load inside the stove. If we
consider an
average consumption of 1.5 kg per hour, this means an estimated autonomy of 6
to 7
hours. In other words, the user can load its stove when going to bed and
maintain the
heating throughout the night.
(c) GREATER HEATING EFFICIENCY. In the use of this heating invention, the
appliance can incorporate a turbine to drive the surrounding environmental air
through
the hot external part of the combustion chamber and thereby increasing the
radiation
efficiency of the heater; in other words, the heating capacity is
comparatively increased
in a shorter time as compared with the conventional firewood stoves equipped
with
single or double combustion chamber.
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(d) VARIED APPLICATIONS. This appliance can have diverse applications; e.g.,
aside from heating, it can be used in firewood ranges where the stepper motor
is
substituted with a direct manual system for driving the briquets step by step
inside the
combustion chamber. In this way, the food cooking speed can be controlled
according
to the needs and the time availability of the user.
The stove can also be used to heat water in commercial and industrial boilers.
The appliance can be provided with a ceramic glass in its front part, so that
the
user can see the intensity of the fire, although access to the stove by
introducing directly
the fuel into the chamber is not possible, according to the principles already
indicated
for this invention.
In view of the foregoing, the present invention means a technical and
practical
solution that permits to control the fuel load to the stove, a feature that
has not been
contemplated in the current units equipped with combustion chamber through
radiation;
in this way, the aspect of environmental pollution can be controlled,
especially in the
cities already referred to in this specification.
The client can enjoy autonomy, inasmuch as he/she is not permanently
concerned with the introduction of firewood to the heater in order to avoid
its becoming
extinguished.
Description of the drawings
For a better understanding of the characteristics and advantages of this
invention, by way of complement, a number of drawings are enclosed, which are
of an
illustrative and not restrictive character, where:
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Figure 1 illustrates a scheme of the operating principle of a traditional
double
combustion chamber heater.
Figure 2 shows a scheme of the operating principle of a traditional firewood
range without a double combustion chamber.
Figure 3 describes the principle of a heater according to the present
invention,
namely, every time the stepper motor is actuated, a single briquet is
introduced inside
the combustion chamber.
Figures 4 and 5 show the fuel briquets loading mechanism, according to the
present invention, into the environmental loading side of the heater.
Figures 6 and 7 show a manual ignition mechanism of the heater of the
invention.
Figure 8 shows, an automatic temperature control mechanism and manual "step"
control, according to the present invention.
Figures 9 and 10 show a heat transfer mechanism by natural radiation and
forced
convection.
Figure 11, show an ash combustion discharge mechanism, according to the
present invention.
Figure 12 illustrates a traditional firewood range incorporating the feeding
mechanism with fuel side loading (briquets) according to the present
invention.
Detailed description of the preferred embodiment of the invention
With reference to Figure 1, it is illustrated a scheme of the operating
principle of a
traditional double combustion chamber heater.
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With reference to figure 2, it is illustrated a scheme of the operating
principle of a
traditional firewood range without a double combustion chamber.
With reference to figure 3, it is illustrated the principle of a heater
according to the present invention, namely, every time the stepper motor is
actuated, a
single briquet is introduced inside the combustion chamber. Said combustion
chamber
can be made of steel and can correspond to the double or single combustion
type.
Figures 4 and 5 describe the form of loading the appliance with briquets.
Through
the gate (1) briquets (2) are orderly introduced into the heater, since the
fuel concerned
has fixed and regular dimensions. The briquets descend by gravity to the pitch
sheave
(3) that includes radial lugs, which is driven by a stepper electric motor
(4). The pitch
sheave (3) permits that briquets pass one by one into the conveyor (5).
Said conveyor (5) may correspond to a chain mechanism equipped with devices
for guiding the briquets (2), being driven by toothed pinions made of steel or
other heat-
resistant material; the pinions are connected by means of an axis made of
steel or other
suitable material.
In the normal operating phase, once the stepper motor (4) is driven by means
of
a thermoelectric signal, the following simultaneous movements are produced:
1. The pitch sheave (3) effects one step.
2. The upper rotary gate (9) opens and a briquet falls into the chamber (8).
3. The conveyor (5) effects one pitch movement.
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Once the briquets loading inside chamber (8) is complete and the respective
motor
(4) stops, the upper gate (9) closes and the pitch sheave (3) also stops.
Figures 6 and 7 illustrate the initial manual ignition mechanism of the
heater; this
takes place by displacing the ignition lid (6) in order to enable the
introduction of an
inducer element, paper or the like, which through a match can cause the
ignition of the
briquets (2) placed over the rack or grid (7) inside the combustion chamber
(8).
Said ignition lid (6) can be opened to a greater or lesser extent in order to
permit
the entry of a greater or smaller air flow into the combustion chamber (8).
Figure 8 describes the fuel entry control systems into the combustion chamber.
There are two options for controlling the entry of fuel into the combustion
chamber,
namely:
= Automatically, through thermoelectric signals. This means that a room
temperature sensor device has been provided, either by means of a thermostatic
bulb (10) or an environment thermostat (11). These elements have been
previously set for a comfortable temperature and will transmit an energy
signal to
the stepper motor (4). The minimum movement is of one pitch, i.e., the
equivalent to introducing one briquet into the combustion chamber.
= Manually: the user has the option to press the pushbutton (12), whereby the
stepper motor is actuated and one briquette enters into the combustion
chamber. Every time the motor is in standstill and the user presses the
pushbutton (12) this will cause one pitch for feeding the combustion chamber.
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Figures 9 and 10 illustrate the main forms in which the appliance of the
present
invention transfers heat into the environment, namely, by means of radiation
through the
glass and the upper part of the heater and by forced convection through the
air flow
entering by the heater rear part operated by the turbine (13), which drives
the
environmental air through the heated external surface of the combustion
chamber and
thereby picks up the heat generated by the combustion chamber (8). Said
turbine can
be a steel fan driven by an ad hoc electric motor.
Between the combustion chamber (8) and the briquets compartment in the heater
supporting structure (16) a thermal insulation layer (17) has been installed,
with the
object of avoiding an overheating in the briquets storage zone.
Figure 11 describes the form of extracting the ash generated by the briquets
combustion inside the combustion chamber. The procedure consists in opening
the lid
(6) and displace it laterally and by means of the scraper (14) the ash into
the rear part
of the rack is moved (7), which falls into the ashtray (15); the latter
element can be
extracted by the user from the supporting structure (16) of the stove for its
disposal.
Said ashtray (15) can consist of a metallic pan for retaining the ash, from
which
ash can be eventually extracted by the user for its elimination.
Figure 12 illustrates a traditional firewood range incorporating the feeding
mechanism with fuel side loading (briquets) according to the present
invention.
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