BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to a linked rotary kiln
incinerator capable of continuous and efficient incineration
of large volumes of mixed waste containing low-calorie waste
and high-calorie waste. The low-calorie waste is fruit
juices, sludge, effluent, foul solution, waste liquor,
kitchen waste, or other types of high-moisture waste having
a high water content, and the high-calorie waste is for
example macromolecular waste, waste oil, waste paper, and
wood chips.
Description of Related Art
The term "incineration" refers to a process to burn
something completely. The term "combustion" refers to a
phenomenon in which the organic matter in a waste material
reacts with the oxygen in the air (undergoes an oxidation
reaction) and burns while generating heat and light.
In a so-called vertical type of dry distillation furnace
or pyrolysis furnace, control air is commonly introduced
through the bottom portion, the materials at the bottom are
partially combusted and the adjacent portions are heated by
the resulting heat, whereupon the organic matter starts
decomposing and vaporizing. When the entire bottom portion
is transformed into a hearth (red-hot layer), the portion
above it is subsequently decomposed and vaporized (fluidized
layer). The upper layer portion thereof is then absorbed
(heat-transfer layer), the uppermost portion is transformed
into a decomposition gas (gas layer). In this way, the
combustion gradually moves upward over time.
Dry distillation ends when the pyrolysis of the organic
matter is completed. Subsequently, a carbonization reaction
starts and the decomposition gas drawn from the dry
distillation furnace are heated by auxiliary burning in a gas
incineration furnace. The necessary air is then fed to the
gas combustion furnace to complete the combustion.
The organic matter contained in high-moisture waste or
other materials combusted in a conventional dry distillation
furnace is gradually combusted in the direction from bottom
top. This process thus needs to be improved in a variety of
ways because it is not suitable for the incineration of, for
example, mixed waste containing low-calorie waste such as
fruit juices, sludge, effluent, foul solution, waste liquor,
kitchen waste, and other types of high-moisture waste with
a high water content, and high-calorie waste such as
macromolecular waste, waste oil, wastepaper, and wood chips.
Conventional incineration of low-calorie waste such as
high-moisture waste needs various methods of acceleration of
combustion. For example, dehydration equipment or a
hydroextractor is installed in the upstream of a line to feed
the low-calorie waste into a dry distillation furnace to
minimize the moisture content of the waste before the
conbustion of the waste. Alternatively, combustion
accelerators or the like are added to the waste in order to
improve the combustion efficiency. The temperature of the
gas burner is set higher than usual. On the other hand,
conventional incineration of mixed waste containing high-calorie
waste such as macromolecular waste, waste oil, waste
paper, and wood chips does not require that low-calorie waste
be pretreated or the furnace temperature be set at a high
level. Accordingly, incineration equipment for incinerating
low-calorie waste and incineration equipment for
incinerating high-calorie waste are required to be
separately installed for different types of waste, and the
equipment cost increases.
Particular drawbacks of the conventional incineration
equipment for incinerating low-calorie waste are that
dehydration equipment must be installed in addition to the
incineration equipment, and the fuel cost is extremely high
because combustion accelerators must be additionally
purchased, and because the temperature inside the furnace
body must be set higher than usual.
Another reason that conventional vertical types of
incineration furnaces need improvement in a variety of ways
is that because high-moisture waste and other types of waste
are introduced through the top of the incineration furnace
and, while descending inside the furnace, are incinerated by
a gas burner installed at the bottom of the furnace, it is
very difficult to control the combustion rate and the amount
in which the waste is introduced, and hence to achieve
complete incineration. In addition, very complicated
post-treatments are needed because large amounts of residues
are generated.
In view of the above mentioned drawbacks, a lateral
rotary kiln incinerator as shown in Fig. 1 has been proposed
in the past, and disclosed in Japanese Published Unexamined
Utility Model Application H06-14730 which was published on
February 2, 1994 in Japan.
As shown in Fig. 1, the lateral rotary kiln incinerator
20 is constructed by mounting a rotation driving assembly 22
on top of a frame base 21 and rotatably installing a furnace
body 23 composed of a single drum on top of the rotation
driving assembly 22. The rotation driving assembly 22 is
provided with an electric motor 22a and is configured in such
a way that barrel gear 23a formed on the outside wall of the
above mentioned furnace body 23 engages with the output gear
22b of the electric motor 22a, allowing the furnace body 23
to roll. The rolling furnace body 23 is configured in such
a way that right and left flanges 23b, 23b formed on the
outside wall of the furnace body 23 are accepted by rotary
free rollers 22c, 22c provided on the right and left sides
of the frame base 21, allowing the furnace body 23 to roll
smoothly.
The above mentioned single-drum furnace body 23 is
roughly shaped as a tapered bottomed cylinder such that the
bottom portion 23c (located in the rear section) is provided
with an opening 23d, and the furnace body 23 is tapered toward
the bottom portion 23c and flared toward the larger opening
23e (located in the front section). The side of the larger
opening 23e is provided with a gas burner 24 that faces the
flame port inside the furnace body 23, with an exhaust unit
25 (including a dust collector), and with an enclosure 28
comprising a blast unit 27 and a slag tapping hole 26 that
opens downward. The side of the bottom portion 23c is
provided with a waste feed assembly 29 integrated with a screw
29a that passes through the opening and faces the feed port
inside the furnace body 23. Because the waste feed assembly
29 feeds each time a predetermined amount of the waste from
a hopper to the furnace body for incineration, the
incineration efficiency is much higher than in the
conventional dry distillation furnaces or vertical types of
incineration furnaces described above, and there is no need
to dehydrate the waste before introducing it to the furnace
in a manner similar to that adopted for dry distillation
furnaces, to admix combustion accelerators into the waste in
order to improve the combustion efficiency, or to set the
temperature of the gas burner higher than is usual under
normal conditions. The technology has numerous other
advantages, such as the fact that it is very easy to control
the combustion rate and the amount in which the waste is
introduced and that very little residue remains because,
unlike a vertical type of incineration furnace, this
technology does not use a process in which the waste is
introduced through the top of an incineration furnace and,
while descending inside the furnace, is combusted by a gas
burner installed at the bottom.
However, the furnace body 23 of the lateral rotary kiln
incinerator with the above-described structure comprises
only a single drum, and is thus disadvantageous in that the
combustion temperature of the furnace must be set high, that
the process must be adjusted to allow the furnace body 23 to
be rotated at a slower pace and to allow the materials to be
thoroughly dried when low-calorie waste such as
macromolecular waste is to be incinerated, and that the
incineration efficiency drops precipitously if the
combustion temperature of the furnace is not set low and the
furnace body 23 is not rotated faster when high-calorie waste
such as macromolecular waste, waste oil, wastepaper, or wood
chips is to be incinerated. Another persisting problem that
is requested to be resolved in the future is that because
low-calorie waste must be incinerated completely during the
incineration of mixed waste containing high- and low-calorie
waste materials, the furnace must be rotated at a low speed
by the rotation driving assembly 22, but such slow rotation
impedes the combustion of admixed high-calorie waste, makes
it extremely difficult to set the rotational speed and the
furnace temperature to a level that would ensure optimum
incineration of the mixed waste containing high- and low-calorie
waste materials being introduced, and makes it
impossible to achieve ideal combustion.
The present invention was made in order to solve the
above mentioned problems and an object thereof is to provide
a linked rotary kiln incinerator capable of continuously and
efficiently incinerating mixed waste containing low-calorie
waste such as fruit juices, sludge, effluent, kitchen waste,
and other types of high-moisture waste with a high water
content, and high-calorie waste such as macromolecular
waste, waste oil, waste paper, and wood chips.
SUMMARY OF THE INVENTION
In order to achieve the above mentioned object, there
is provided the following features to an elongated rotary
kiln incinerator with a cylindrical structure in which a
waste material introduced through one side of a furnace body
is combusted while being gradually transported to the other
side of the furnace body by the rotation of the furnace body.
The furnace body is obtained by aligning along a straight line
a plurality of drums that have openings on the right and left
sides and rotatably linking the adjacent drums at the
openings. Each drum is rotated by a rotation driving assembly
installed on the outer periphery of the drum, and each of the
rotation driving assembly is driven and controlled by a
rotation control unit equipped with furnace temperature
sensors each provided to the drum. A fixed temperature
difference is assigned between the internal temperature of
a first set of drums linked at positions close to the side
of waste introduction and the internal temperature of a
second set of drums linked at positions away from the side
of waste introduction, and the rotational speed of each drum
is controlled in accordance with this temperature
difference. Preferably, the internal temperature and the
rotational speed of the first set of drums linked at the
positions close to the side of waste introduction are
respectively set to a temperature and a rotational speed
necessary to combust high-calorie waste, and the internal
temperature and the rotational speed of the second set of
drums at the positions away from the side of waste
introduction are respectively set to a temperature necessary
and a rotational speed necessary to combust low-calorie
waste. Further preferably, the internal temperature of the
first set of drums linked at the positions close to the side
of waste introduction is set to a temperature necessary to
combust high-calorie waste, and the introduction of the
high-calorie waste is suspended if the interior of the drums
is heated above the set temperature due to the continuous
introduction of waste, and no waste is introduced until the
temperature inside the drums drops to the set temperature.
Still further, the rotational speed of the drums in which
high-calorie waste is combusted is preferably higher than
that of the drums in which low-calorie waste is combusted.
Because a structure such as that described above is
adopted in the present invention, when mixed waste containing
low-calorie waste such as fruit juices, sludge, effluent,
kitchen waste, and other types of high-moisture waste with
a high water content, and high-calorie waste such as
macromolecular waste, waste oil, waste paper, and wood chips
is introduced into the furnace body, then, high-calorie waste
such as macromolecular waste, waste oil, waste paper, or wood
chips is first completely incinerated in the drums that are
rotated at a high speed and that are linked at positions close
to the side of waste introduction, and admixed low-calorie
waste such as fruit juices, sludge, effluent, kitchen waste,
and other types of high-moisture waste with a high water
content is passed while rotated through the rapidly rotating
drums of the first stage, and is thus thoroughly dried while
moving through the rapidly rotating drums. After that the
waste reaches the slowly rotating drums linked at positions
away from the side of waste introduction and undergoes
complete incineration there.
In summary, the adoption of the linked rotary kiln
incinerator pertaining to the present invention allows a
mixed waste containing low-calorie waste such as fruit
juices, sludge, effluent, kitchen waste, and other types of
high-moisture waste with a high water content, and high-calorie
waste such as macromolecular waste, waste oil, waste
paper, and wood chips to be processed continuously and in
large quantities.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a diagram illustrating the structure of a
conventional rotary kiln incinerator;
Fig. 2 is a side view of the linked rotary kiln
incinerator according to the present invention; and
Fig. 3 is a plan view of the linked rotary kiln
incinerator according to the present invention.
DETAILED SCRIPTION OF THE PREFERRED EMBODIMENTS
An embodiment of the linked rotary kiln incinerator
according to the present invention will now be described with
reference to Figs. 2 and 3.
Fig. 2 is a side view depicting the entire structure of
the linked rotary kiln incinerator according to the present
invention, and Fig. 2 is a plan view depicting the entire
structure of the linked rotary kiln incinerator according to
the present invention.
In the drawings, a linked rotary kiln incinerator 1
comprises a rotation driving assembly 3 (blocks A, B, C, D,
and E) mounted on top of a frame base (base) 2. The rotary
kiln incinerator 1 also comprises a furnace body 4 rotatably
installed on top of the rotation driving assembly 3. The
furnace body 4 comprises a plurality of drums. In the present
embodiment, the furnace body 4 comprises five drums D1, D2,
D3, D4, and D5 (for example, the length of one drum is 8 meters,
and the total length is 40 meters).
The rotation driving assembly 3 installed on each of the
above mentioned blocks (A through E) is provided with an
electric motor 3a. The rotation driving assemblies 3 are
configured in such a way that barrel gears 4a formed on the
outside wall of the furnace body 4 enmesh with the output
gears 3b of the electric motors 3a, allowing the furnace body
4 to roll. A rotation control unit 3c is provided for
controlling the rotational speeds of the drums D1, D2, D3, D4,
and D5 forming the furnace body 4. More specifically, a fixed
temperature difference is assigned between the internal
temperature of the plurality of drums D1, D2, and D3 linked
at positions close to the side of waste introduction and the
internal temperature of the plurality of drums D4 and D5 linked
at positions away from the side of waste introduction. The
rotational speed of each drum can be controlled in accordance
with the temperature difference. In the preferred
embodiment, the internal temperature of the drums D1, D2, and
D3 is 500°C ± 100°C while the internal temperature of the drums
D4 and D5 is 850°C ± 100°C. The rotational speed of the drums
D1, D2, and D3 in this embodiment is designed to be set to for
example one revolution per minute and that of the drums D4
and D5, for example, to one revolution every two minutes.
In addition, the overall structure of the drums D1, D2,
D3, D4, and D5 comprising the above mentioned furnace body 4
is such that each of the drums remains cylindrical between
its two openings (4c and 4d), the drums D1, D2, D3, D4, and
D5 are aligned along a straight line, and the facing openings
4c and 4d of the adjacent drums D1, D2, D3, D4, and D5 fit into
each other, yielding a rotatably linked furnace body 4.
The links between the above mentioned drums D1, D2, D3,
D4, and D5 are equipped with a suitable number of an oxygen
feed unit 5 to allow the temperature inside the furnace body
4 to be maintained at the set levels at all times.
A waste feed unit 6 for feeding mixed waste containing
low-calorie waste such as fruit juices, sludge, effluent,
kitchen waste, and other types of high-moisture waste with
a high water content, and high-calorie waste such as
macromolecular waste, waste oil, waste paper, and wood chips
is installed near one of the openings of the above mentioned
drum D1. A desalination/desulfurization apparatus 7, a dust
collector (in the embodiment in question, a cyclone type of
dust collector) 8, a cooling device 9, a wet scrubber 10, and
an exhaust unit 11 are installed in the order indicated near
the opening of the drum D5.
In addition, lifting protrusions (not shown) of
prescribed height are provided to the internal walls of the
drums D1, D2, D3, D4, and D5 forming the furnace body 4 to allow
the waste being introduced to be transported with high
efficiency from one side to the other during rolling.
Furthermore, a heat-exchange apparatus X is provided on the
outer periphery of the above mentioned furnace body 4, as is
a heat reuse system Y containing a hot-water supply apparatus
or a power generator that utilizes heat released by the
furnace body 4.
Moreover, the above mentioned drums D1 and D5 are
equipped with a first burner 13 and a second burner 14,
respectively.
The flame temperature of the above mentioned first
burner 13, second burner 14, and oxygen feed unit 5 is
controlled by a rotation control unit 3c (comprising a
proportional controller, furnace temperature sensors and
other circuitry; not shown), allowing mixed waste or other
types of waste introduced into the furnace body 4 to be
combusted in a controlled manner with high efficiency. The
mixed waste contains low-calorie waste such as fruit juices,
sludge, effluent, kitchen waste, and other types of high-moisture
waste with a high water content, and high-calorie
waste such as macromolecular waste, waste oil, waste paper,
and wood chips.
Although the internal temperature of the drums D1, D2,
and D3, which are linked at positions near the above mentioned
waste feed unit 6, is set to a temperature necessary to
combust high-calorie waste, the introduction of the high-calorie
waste is suspended if the interior of the drums D1,
D2, and D3 is heated above the set temperature due to the
continuous introduction of the waste, and no waste is
introduced by the waste feed unit 6 until the temperature
inside the drums D1, D2, and D3 drops to the set temperature.
An overview of the incineration of waste in the linked rotary
kiln incinerator according to the present invention will now
be given based on the above-described structure.
The linked rotary kiln incinerator 1 according to the
present invention is such that a plurality of drums D1, D2,
D3, D4, and D5 constituting a furnace body 4 are rotatably
driven by the rotation driving assembly 3 provided to each
of the drums D1 through D5 while the rotational speed is
controlled by rotation control unit 3c. Moisture and other
components contained in waste must be thoroughly dried when
incineration involves low-calorie waste alone, as in the case
of low-calorie waste such as fruit juices, sludge, effluent,
kitchen waste, and other types of high-moisture waste with
a high water content to be incinerated. Accordingly, control
involves gradually increasing the rotational speed in the
direction from the drum D1 on the side of the waste feed unit
6 toward the drums D2, D3, D4, and D5 in the order indicated.
More specifically, the waste introduced into the first drum
D1 contains a large amount of moisture or the like, and is
therefore incinerated by slow rotation (most of the moisture
is evaporated and dried by the first burner 13), ultimately
moving to the last drum D5. The low-calorie waste that has
reached the last drum D5 can be combusted relatively easily
because the moisture has already been vaporized and dried in
a sequential manner at the preceding stage. The waste is
therefore transported to the last drum D5 while this drum is
made to rotate faster than the drum D4 and a prescribed
incineration procedure is performed. If there are signs that
the combustion temperature inside the furnace body 4 is
decreasing, the material is subsequently incinerated while
the oxygen feed unit 5 provided to the links between the drums
D1, D2, D3, D4, and D5 are actuated to prevent a reduction in
combustion efficiency. Any residue that has remained without
being incinerated in the drums D1, D2, D3, or D4 of the first
stage is ultimately transferred to the drum D5, burned by the
flame of the second burner 14, and completely incinerated in
the drum D5. The last drum D5 rotates even faster than the
preceding drum D4 because the drum D5 is used to incinerate
only the waste not incinerated in the preceding drum D4. Thus,
the linked rotary kiln incinerator 1 according to the present
invention has a larger furnace capacity than a conventional
rolling type of rotary kiln incinerator because the furnace
body 4 is composed of a plurality of drums D1, D2, D3, D4, and
D5 linked together, and the drums can be rollably driven and
waste materials incinerated in a prescribed manner while the
rotational speed of the furnace body 4 is controlled, with
the result that the amount in which the waste materials can
be processed is increased dramatically in comparison with the
conventional rolling type of rotary kiln incinerator, and the
combustion efficiency can be markedly improved as well.
In addition, during the incineration of mixed waste
containing low-calorie waste such as fruit juices, sludge,
effluent, kitchen waste, and other types of high-moisture
waste with a high water content, and high-calorie waste such
as macromolecular waste, waste oil, waste paper, and wood
chips, the rotation of the drums D1, D2, and D3 is controlled
at each stage in such a way that their speed is set to one
revolution per minute, that is, above the speed of the
subsequent drums D4 and D5. The reason is that the
incineration involves a mixture containing high-calorie
waste such as macromolecular waste, waste oil, waste paper,
and wood chips, rather than only the above mentioned
high-moisture waste or other such low-calorie waste.
More specifically, the waste introduced into the first
drum D1 contains admixed high-calorie waste such as
macromolecular waste, waste oil, waste paper, and wood chips,
making it easier to ignite the first burner 13 and to
evaporate and dry up the contained moisture or the like, with
the result that the waste is incinerated at each step of the
drums D1, D2, and D3 in such a way that these drums are rotated
faster than the drums D4 and D5, which are used to incinerate
only the above mentioned low-calorie waste such as fruit
juices, sludge, effluent, kitchen waste, and other types of
high-moisture waste with a high water content, that the
unburned low-calorie waste that has passed through the drums
D1, D2, and D3 is transported to the second stage, that is,
to the drums D4 and D5 set to perform one revolution every two
minutes (the waste is dried as it is being transported), and
that all the waste is ultimately incinerated in the drums D4
and D5 of the second stage.
In particular, a merit of the linked rotary kiln
incinerator 1 according to the present invention is that
while the above mentioned remarkable effects can be obtained
when incineration involves only the above mentioned low-calorie
waste such as fruit juices, sludge, effluent, kitchen
waste, and other types of high-moisture waste with a high
water content, it is even more remarkable that a higher
incineration capacity per unit of time can be achieved than
with a conventional rolling type of rotary kiln incinerator
during the incineration of mixed waste containing low-calorie
waste such as high-moisture waste, and high-calorie
waste such as macromolecular waste, waste oil, waste paper,
and wood chips, that is, superb incineration capacity can be
achieved by increasing the furnace capacity and rollably
driving the furnace and incinerating the waste in a
prescribed fashion while controlling the rotational speed of
the furnace body 4, thereby providing a radical solution for
the incineration of household waste, an important issue of
future waste disposal.
In addition, the furnace wall surfaces of the drums D1,
D2, and D3, which are linked at positions near the above
mentioned waste feed unit 6, are protected from unnecessary
damage or the like because while the internal temperature of
the drums D1, D2, and D3 is set to a temperature necessary to
combust high-calorie waste, the introduction of the high-calorie
waste is suspended if the interior of the drums D1,
D2, and D3 is heated above the set temperature due to the
continuous introduction of the waste, and no waste is
introduced by the waste feed unit 6 until the temperature
inside the drums D1, D2, and D3 drops to the set temperature.
Furthermore, chlorine gas, dioxins, and other hazardous
substances emitted due to the combustion of industrial waste
are efficiently removed because the present invention
envisages installing the desalination/desulfurization
apparatus 7, the dust collector (in the present embodiment,
a cyclone type of dust collector) 8, the cooling device 9,
the wet scrubber 10, and the exhaust unit 11 in the order
indicated at the second stage of the furnace body 4. In
addition, heat generated by the combustion of such waste can
be efficiently utilized because a heat-exchange apparatus X
is provided on the outer periphery of the above mentioned
furnace body 4, as is a hot-water supply apparatus, power
generator, or other reuse system Y that utilizes heat
released by the furnace body 4.
As described in detail above, the present invention
relates to an elongated rotary kiln incinerator with a
cylindrical structure in which a waste material introduced
through one side of a furnace body is combusted while being
gradually transported to the other side of the furnace body
by the rotation of the furnace body. The furnace body is
obtained by aligning along a straight line a plurality of
drums that have openings on the right and left sides and
rotatably linking the adjacent drums at the openings. Each
drum is rotated by a rotation driving assembly installed on
the outer periphery of the drum, and each of the rotation
driving assembly is driven and controlled by a rotation
control unit equipped with furnace temperature sensors each
provided to the drum. A fixed temperature difference is
assigned between the internal temperature of a first set of
drums linked at positions close to the side of waste
introduction and the internal temperature of a second set of
drums linked at positions away from the side of waste
introduction, and the rotational speed of each drum is
controlled in accordance with this temperature difference.
Preferably, the internal temperature and the rotational
speed of the first set of drums linked at the positions close
to the side of waste introduction are respectively set to a
temperature and a rotational speed necessary to combust
high-calorie waste, and the internal temperature and the
rotational speed of the second set of drums at the positions
away from the side of waste introduction are respectively set
to a temperature necessary and a rotational speed necessary
to combust low-calorie waste. Further preferably, the
internal temperature of the first set of drums linked at the
positions close to the side of waste introduction is set to
a temperature necessary to combust high-calorie waste, and
the introduction of the high-calorie waste is suspended if
the interior of the drums is heated above the set temperature
due to the continuous introduction of waste, and no waste is
introduced until the temperature inside the drums drops to
the set temperature. Still further, the rotational speed of
the drums in which high-calorie waste is combusted is
preferably higher than that of the drums in which low-calorie
waste is combusted.
According to the above configuration, when mixed waste
containing low-calorie waste such as fruit juices, sludge,
effluent, kitchen waste, and other types of high-moisture
waste with a high water content, and high-calorie waste such
as macromolecular waste, waste oil, waste paper, and wood
chips is introduced into the furnace body, then, high-calorie
waste such as macromolecular waste, waste oil, waste paper,
or wood chips is first completely incinerated in the drums
that are rotated at a high speed and that are linked at
positions close to the side of waste introduction, and
admixed low-calorie waste such as fruit juices, sludge,
effluent, kitchen waste, and other types of high-moisture
waste with a high water content is passed while rotated
through the rapidly rotating drums of the first stage, and
is thus thoroughly dried while moving through the rapidly
rotating drums. After that the waste reaches the slowly
rotating drums linked at positions away from the side of waste
introduction and undergoes complete incineration there.
Thus, the remarkable merits of adopting the linked
rotary kiln incinerator pertaining to the present invention
include the fact that a mixed waste containing low-calorie
waste such as fruit juices, sludge, effluent, kitchen waste,
and other types of high-moisture waste with a high water
content, and high-calorie waste such as macromolecular
waste, waste oil, waste paper, and wood chips can be processed
continuously and in large quantities in a single linked
rotary kiln incinerator.
The features disclosed in the foregoing description,
in the claims and/or in the accompanying drawings may,
both separately and in any combination thereof, be material
for realising the invention in diverse forms thereof.