Note: Descriptions are shown in the official language in which they were submitted.
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INCINERATOR AND INCINERATING METHOD EMPLOYING THE SAME
BACKGRO~ND OF THE INVENTION
l. Field of the Invention
The present invention relates to an incinerator for
combustion of general refuse and industrial wastes, and an
incinerating method employing the same.
2. Description of the Prior Art
Heretofore proposed is a vertical incinerator having a
plurality of grates dividing a furnace into a plurality of
stages in such a manner that said grates can be freely opened
and closed, whereby the refuse charged from the top of the
furnace piles up on the grate in the first stage in a
sufficient thickness thereon and is then transferred
successively to the grate in the succeeding stage or stages
while it is burned until it has been finally turned to ashes
for discharge from the bottom of the furnace.
However, the refuse generally includes hardly
combustible materials such as rich in moisture and air-
impermeable lamps or hardly crushable masses, so that the
combustion may not be completed in the upper combustion zone
but continue in the lower combustion zone or the plastics
melt and drip down, and then ignite in the lower zone of the
~5 furnace. For these reasons, the grates supporting the refuse
in the upper combustion zone are exposed to intense heat from
the reverse surfaces and cannot be sufficiently cooled by
blasting cold air against the grates, with the result that the
grates tend to be thermally strained or damaged.
Furthermore, the ventilation holes in the grates may be
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plugged with ashes and foreign matter to interfere with the
free passage of combustion gases and combustion air or
clinkers may be melted and stuck to the ventilation holes to
impede the opening and closing of the grates.
SUMMARY OF THE INVENTION
The present invention has been accomplished for
overcoming the above-mentioned disadvantages of the
conventional vertical incinerator. It is, therefore, an
object of the invention to provide an incinerator and an
incinerating method employing the same, wherein the layer of
ashes accumulated in the lower zone of a furnace is utilized
as an equivalent of the grate to dispense with the grate and,
thereby, simplify the equipment and insure effective
utilization of combustion energy without the risk of burning
out and thermal straining of the parts and the consequent
troubles, thus effecting savings in running cost.
It is another object of the invention to provide an
incinerator and an incinerating method employing the same,
wherein both the refuse supporting means and the ash discharge
means are simplified in construction to preclude insufficient
operation due to intricate structure of the equipment.
It is a further object of the invention to provide an
incinerator and an incinerating method employing the same,
wherein refuse supporting means project into a furnace so as
to effect breaking of clinker masses which tend to form on
the refuse supporting means in the incineration of high calory
refuse, thereby insuring complete combustion and an increased
ease of discharge of the ashes.
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The above and further objects, features and advantages
of the invention will more fully appear from the following
description with reference to the accompanying drawings. It
is to be expressly understood, however, that the drawings are
for purpose of illustration only and are not intended as a
definition of the limits of the invention.
BRIFF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a schematic longitudinal section view showing
the construction of an incinerator according to the
invention;
Figs. 2 and 3 each shows an example of the refuse
supporting means; Fig. 2 is a longitudinal sectional
elevation view showing the refuse supporting means in
retreated position and Fig. 3 is a longitudinal sectional
elevation view showing the same swung into the furnace;
Fig. 4 is a perspective view showing another example of
a refuse supporting means, which is in the form of a grate;
and
Fig. 5 is a sectional view showing another example of
an ash discharge means, which is an inclined reversible
grate.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Fig. 1 is a schematic view of the incinerator according
to the invention.
In Fig. 1, the reference numeral 1 indicates a hopper.
The refuse storaged in a refuse pit (not shown) is mixed well
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until it is crumbled to a certain extent and, then, charged
into this hopper l by means of crane (not shown). The hopper
l communicates with a refuse feeding port 3l installed to an
upper position of a furnace 3 through a feeder 2. The refuse
charged into the hopper l is fed into the furnace 3 by the
feeder 2 at a predetermined rate.
The furnace 3 is equipped with a pair of refuse
supporting plates 4, 4 which constitute a refuse supporting
means, and a pair of ash discharge plates 5, 5 which
constitute an ash discharge means, in an upper position and a
lower position, respectively.
The refuse supporting plates 4,4 are displaceably
installed within the furnace body 3; that is to say each is
normally located in the retreated position away from the
furnace 3 as illustrated. However, these plates 4,4 are
operated to project into an upper part of a layer of ashes
l54 in the furnace 3 as indicated by a dot-dash line only at
the time when the ash discharge plates 5,5 are opened to
discharge the ashes, thus supporting the refuse and ashes
located above.
A pair of compartments 6,6 for accommodating the refuse
supporting plates 4, 4 drawn away from the furnace 3 are
located on both sides of the furnace 3 at the level where the
plates 4, 4 are disposed. These compartments 6, 6 are
supplied with cooling air 7l from a normal temperature air
source 7. This cooling air 7l blows out into the furnace 3
from clearances 8, 8 formed between the furnace 3 and the
respective compartments 6, 6 to cool the refuse supporting
plates 4, 4 and, at the same time, prevent entry of ashes
into the compartments 6, 6 through the clearances 8, 8.
2 0 A l 8 ~ ~
The ash discharge plates 5, 5 are each disposed
rotatablely through the angle from the horizontal position to
the vertical position indicated by a dot-dash line to open
and close the ash discharge port at the bottom of the furnace
3. The refuse supporting plates 4, 4 then support the refuse
and ashes above the upper part of the layer of ashes 154 in
the lower zone of the furnace 3. Thereafter, the ash
discharge plates 5, 5 are swung down to discharge the ashes
into an ash transport means 9 disposed below the furnace 3.
Thus, said refuse supporting plates 4, 4 are provided to
assist in smooth discharge of ashes by said ash discharge
plates 5, 5.
ht its upper, intermediate and low levels, the furnace
3 is supplied with combustion air 101, 102 and 103t all of
adjusted temperature, through dampers 111, 112 and 113
respectively. These combustion air are adjusted at the
optimum temperature suited for the refuse character.
Disposed on the side opposite to the refuse feeding
port 31 of the furnace 3 is an ignition burner 12 which is
used for igniting the refuse at the start of operation and
assisting in combustion during temperature drop in the
furnace 3. Disposed at top of the furnace 3 is a gas exhaust
port 13 for exitof combustion gases.
The incinerating method employing the above incinerator
is now described~
In normal operation, the interior of the furnace 3 is
divided, in correspondence with the combusting condition of
the refuse, into a flame layer 151, a refuse layer 152, a
combustion layer 153 and an ash layer 154 from the top to the
bottom
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First, the refuse charged in the hopper 1 is fed, at a
predetermined rate, into the furnace 3 by the feeder 2 through
the refuse feeding port 31. At the beginning of operation,
the refuse are piled up on the ash layer 154 in the bottom
zone of the furnace 3 and is ignited by the ignition burner
12. The refuse then starts burning with the aid of combustion
air 101, 102 and the portion of refuse which is more easily
combustible is turned to ashes. The ashes are accumulated
together with the hardly combustible portion of the refuse and
are charged to said combustion layer 153, retaining fire
seeds.
As the refuse is fed by the feeder 2 in this condition,
the refuse are piled up to the refuse layer 152, gets ignited
by the heat from the combustion layer 153 and the combustion
air 111 and the combustion then spreads throughout the refuse
layer 152 to place the furnace into a normal operating
condition.
In this combustion state, the combustion gases produced
in the combustion layer 153 and the lower part of the refuse
layer 152 ascend through the refuse layer 152. In this
prosess of ascent, the hot combustion gases promote ignition
and gasification of the refuse in the upper layer and dry the
raw refuse.
Then, the hot combustion gases reaching up to the flame
layer 151 is recombusted by secondary air 72 from a normal
temperature air source 7 and exhausted from the exhaust gas
outlet 13 to the next process. The radiant heat produced by
this combustion effects preliminary drying of the refuse in
the refuse layer 152 and promotes burning of the paper and
plastics with low ignition points to grow to fire seeds.
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In this manner, the refuse descended in sequence is
combusted in the refuse layer 152 and the unburnt
combustibles remaining together with hardly combustible
materials are completely combusted into ashes in the
combustion layer 153 and retained in the ash layer 154.
In the ash layer 154, the combustion air 103 helps to
complete the final burning of the unburnt combustibles
remaining in the upper layer of the ash layer 154 and, at the
same time, cools the ashes and metals having a low-melting
point from below.
In this process, the air and hot combustion gases
ascending from the ash layer 154 flow through the combustion
layer 153 and refuse layer 152 to facilitate combustion of the
refuse at the upper layer and further accelerate the drying,
ignition and gasification of raw refuse.
Thus, the ash layer 154 plays the duty of the
conventional fire grate.
Upon completion of this combustion of ashes, the refuse
supporting plates 4, 4 are caused to project into the upper
position of the ash layer 154 within the furnace 3 to support
the refuse and ashes in the refuse layer 152, combustion
layer 153 and ash layer 154 which are disposed above. At this
time of projection, the combustion of refuse has already been
completed at the level of the refuse supporting plates 4, 4.
Therefore, the ref~se supporting plates 4, 4 need not be
provided with the ventilation holes which are required for the
conventional fire grate. Moreover, because of low resistance
by the refuse, the refuse supporting plates 4, 4 are allowed
to project smoothly.
After the refuse supporting plates 4, 4 have thus been
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caused to project, the ash discharge plates 5, 5 are swung
down to let the ashes below the refuse supporting plates 4, 4
fall down into the ash transport means 9.
After discharge of the ashes, the ash discharge plates
5, 5 are returned into the upper position and the refuse
supporting plates 4, 4 are caused to retreat away from the
furnace 3 to let the remaining ashes and the incinerator
residues in the combustion layer 153 on the refuse supporting
plates 4, 4 fall down onto the furnace bottom and the refuse
layer 152 fall down.
The shock of this fall not only improves the air
permeability in the ash layer 154 but disintegrates the
unburnt mases in the combustion layer 153 and refuse layer 152
so that the whole layer becomes more permeable to air.
15Therefore, as the high-temperature combustion air 102, 103 is
dupplied, the unburnt combustibles in the ashes is easily
glowed by the remaining fire seeds.
The feeding pressure of the combustion air 102, 103
need not be high because of the improved air permeability of
20the combustion layer 153 and ash layer 154, and the resulting
improved drying efficiency helps reduce the excess air ratio.
The incinerator thus constructed not only insures
almost uniform combustion of refuse at high temperature but,
as aforesaid, helps reduce the excess air ratio, with the
result that the volume of exhaust gas is decreased to prolong
the residence time of combustion gases. This result is
effective in sterilization and decomposition of dioxins. The
sterilization effect, in particular, is beneficial for the
incineration of medical wastes.
30Furthermore, the time of projection of the refuse
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supporting plates 4, 4 into the furnace 3 when the
temperature of the ash layer 154 has dropped and is also short
in duration. Therefore, there is no risk of thermal strain
and burning out due to high temperature. Moreover, the ash
discharge plates 5, 5 are not adversely affected by high
temperature, for the upper surfaces of the plates 5, 5 are in
contact with the ashes cooled by the combustion air 103 while
their lower surfaces are cooled by the atmospheric air.
It should be understood that the refuse supporting
plates 4, 4 need not be those described in the foregoing
embodiment but may be those each rotatable about a pivot 41
as illustrated in Figs. 2 and 3. Moreover, the refuse
supporting plates 4, 4 may also have a grate-like structure as
illustrated in Fig. 4.
The ash discharge plates 5, 5 need not be those
described above in the foregoing embodiment, either, but may
be an inclined reversible grate rotatable about a pivot 51 as
illustrated in Fig. 5.
While there has been described what is at present
considered to be preferred embodiments of the invention, it
will be understood that various modifications may be made
therein, and it is intended to cover in the appended claims
all such modifications as fall within the true spirit and
scope of the invention.
