U.S. patent application number 10/466143 was filed with the patent office on 2004-03-18 for plastic liquefying device.
Invention is credited to Kimura, Shigeyoshi, Takahashi, Kenzo, Takahashi, Masaya.
Application Number | 20040050678 10/466143 |
Document ID | / |
Family ID | 27345720 |
Filed Date | 2004-03-18 |
United States Patent
Application |
20040050678 |
Kind Code |
A1 |
Takahashi, Kenzo ; et
al. |
March 18, 2004 |
Plastic liquefying device
Abstract
A plastic liquefying device, includes a gasifying furnace (19)
for generating pyrolytic gas by heating and melting plastic waste
and a liquefying tank (2) for liquefying and separating the
pyrolytic gas generated in the gasifying furnace (19). The
gasifying furnace (19) further comprising a heating device (22) for
heating the inside of an oven-shaped furnace body (20) provided at
the bottom of the furnace body (20) having a plastic waste inlet
(H) provided at the top thereof and an opening and closing
mechanism (21) for opening and closing the inlet (H) installed at
the inlet (H). The opening and closing mechanism (21) further
includes a plate shutter (24) larger than at least the opening area
of the inlet (H) and a fixing device (25) for pressingly fixing the
shutter (24) to the seal surface (S) around the peripheral edge
part of the inlet (H). Since the inside of the furnace body (20)
can be sealed by closely fitting the shutter (24) to the seal
surface (S), the lowering of a pressure inside the furnace due to
gas leakage and the deterioration of an ambient environment can be
prevented.
Inventors: |
Takahashi, Kenzo;
(Kamifukuoka-shi, JP) ; Kimura, Shigeyoshi;
(Kamifukuoka-shi, JP) ; Takahashi, Masaya;
(Tsuruoka-shi, JP) |
Correspondence
Address: |
McCormick Paulding & Huber
City Place II
185 Asylum Street
Hartford
CT
06103-3402
US
|
Family ID: |
27345720 |
Appl. No.: |
10/466143 |
Filed: |
July 11, 2003 |
PCT Filed: |
January 15, 2002 |
PCT NO: |
PCT/JP02/00190 |
Current U.S.
Class: |
202/108 |
Current CPC
Class: |
C10G 1/10 20130101 |
Class at
Publication: |
202/108 |
International
Class: |
C10B 001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 15, 2001 |
JP |
2001-6998 |
Jul 9, 2001 |
JP |
2001-208280 |
Dec 21, 2001 |
JP |
2001-389920 |
Claims
What is claimed is:
1. A plastic liquefying device comprising a gasifying furnace for
generating pyrolytic gas by melting plastic wastes; and a
liquefying tank for liquefying and separating the pyrolytic gas
generated at the gasifying furnace, wherein the gasifying furnace
comprises: heating means located at a bottom of an oven-shaped body
of the furnace for heating an inside of the furnace, an oven-shaped
body of the furnace having a plastic waste inlet at an upper part
thereof; and an opening and closing mechanism located at the inlet
for opening and closing the inlet, wherein the opening and closing
mechanism comprises: a plate shutter at least larger than an
aperture area of the inlet; and locking means for securing the
shutter onto a sealing surface of the inlet peripheral edge by way
of pressure.
2. A plastic liquefying device of claim 1, wherein sliding means
for opening and closing the inlet by horizontally sliding the
shutter is provided at the shutter.
3. A plastic liquefying device of claim 1, wherein the sliding
means is a hydraulic cylinder with one end connected to the shutter
and the other end pivotably connected to the furnace body.
4. A plastic liquefying device of claim 1, wherein the locking
means is a hydraulic cylinder which secures the shutter onto the
sealing surface by way of pressure from above.
5. A plastic liquefying device of claim 1, wherein a purge gas
header which sprays purge gas onto the sealing surface is provided
at the peripheral edge of the inlet.
6. A plastic liquefying device of claim 1, wherein a corrugated
surface which is formed by a plurality of canaliculate members
placed parallel to each other is provided at a bottom of the
furnace body.
7. A plastic liquefying device of claim 6, wherein a
canaliculate-shape discharge pipe is provided such that the
discharge pipe merges with ends of the canaliculate member, and a
screw conveyer is provided in each of the canaliculate members and
the discharge pipe.
8. A plastic liquefying device of claim 1, wherein the heating
means comprises a gas burner, a jacket which covers a perimeter of
the furnace body to flow exhaust combustion gas from the gas
burner, and a parting strip which is arranged spirally at the
jacket.
9. A plastic liquefying device comprising a gasifying furnace for
generating pyrolytic gas by melting plastic wastes and a liquefying
tank for liquefying and separating the pyrolytic gas generated at
the gasifying furnace, wherein the gasifying furnace comprises: a
vertical tube body for receiving infectious plastic wastes, heating
means for heating the vertical tube body from its surrounding and
generating pyrolytic gas by pyrolitically decomposing infectious
plastic wastes, and an agitator to agitate an inside of the furnace
body, wherein the top part of the furnace comprises: an inlet to
receive the infectious plastic wastes, an opening and closing lid
for opening and closing the inlet, a gas outlet for exhausting the
pyrolytic gas, and the gas outlet includes an automatic opening and
closing valve.
10. A plastic liquefying device of claim 9, wherein the furnace
body is a pressure vessel, the furnace body has a vertical tube
shape metal sack body, the hemispheric end covers are provided at
both top and bottom parts thereof, and an opening and closing lid
and the gas outlet are further provided at the top part.
11. A plastic liquefying device of claim 9, wherein the agitator
comprises a drive shaft which is positioned at a shaft center part
of the furnace body, a driving motor for rotating the drive shaft,
and a plurality of moving vanes which radially extend from the
drive shaft, and the moving vanes respectively revolve in contact
with the bottom of the furnace.
12. A plastic liquefying device of claim 9, wherein a discharge
opening for discharging insolubles is provided at the bottom part
of the furnace body.
13. A plastic liquefying device comprising a gasifying furnace for
heating various kinds of plastic wastes and generating pyrolytic
gas and a liquefying tank for condensing the pyrolytic gas
generated at the gasifying furnace and then separating, wherein the
bottom part of the gasifying furnace narrows in a valley-shape and
includes a screw conveyer and an outlet for discharging
insolubles.
14. A plastic liquefying device of claim 13, wherein the liquefying
tank includes a jet scrubber for spraying a cooling water onto the
pyrolytic gas to condense the pyrolytic gas, and a cleaning column
for cleaning exhaust gas in a landscape water tank, the bottom part
of the water tank narrows in a funnel-shape and is connected to a
drain line, and a middle part of the water tank is connected to an
oil recovery line.
15. A plastic liquefying device of claim 14, wherein a
neutralization tank for infusing neutralizer is provided at the
drain line.
Description
TECHNICAL FIELD
[0001] The present invention relates to a plastic liquefying device
for thermally decomposing plastic wastes to efficiently use the
plastic wastes as reclaimed oil or the like.
BACKGROUND ART
[0002] Recently, one of the most serious issues in waste disposal
problems to deal with ever-increasing wastes is how to dispose of
plastic parts and plastic containers, which are utilized in a
majority of industrial products such as electrical products,
domestic house ware, automobiles, and PET (polyethylene
telephthalate) bottles.
[0003] Since it is difficult to dispose of such plastic wastes by
biodegrading (biological breakdown), which is commonly utilized to
dispose of kitchen wastes, timber wastes or the like, the majority
of such plastic wastes are generally incinerated. However, as is
well known, when incinerating plastics, a large amount of funnel
fume and poison gas are produced. Moreover, because of the high
combustion temperature, there are problems such as the incinerator
damage.
[0004] Therefore, recently an attempt has been made to collect
these plastic wastes and recycle them as an important recycling
resource. However, recycling plastic wastes entails onerous work
such as collecting and separating plastic wastes by each type of
plastic constituent, color, etc. As a result, the large amount of
cost and labor is involved and the recycling plastic wastes does
not meet its cost accounting.
[0005] The present inventors developed a novel plastic liquefying
systems for efficiently disposing of the above-mentioned plastic
wastes and recycling them as reclaimed oil or the like, and filed
patent applications (Japanese Patent Application No. 2000-63335,
etc.) for these systems.
[0006] As shown in FIG. 12, this plastic wastes liquefying device
comprises mainly a gasifying furnace 1 for melting plastic wastes
by way of heat from a gas burner 4, etc. and generating pyrolytic
gas by thermally decomposing, and a liquefying tank 2 for
liquefying the pyrolytic gas which is generated in the gasifying
furnace 1 after cooling and condensing. Specifically, after
thermo-plastic wastes are melted and gasified into the pyrolytic
gas including stylen-monomer and low monocular gravity polyethylene
through a pyrolitical decomposition process in the gasifying
furnace 1. The pyrolitic gas is then contacted with cooling water
to cause vapor-liquid contact, and is re-liquefied by being cooled
and condensed in the liquefying tank 2. Finally, the decomposed
liquid is separated from the cooling water. The decomposed gas can
be used as a material or the like for a new plastic product or fuel
for a boiler, so that effective use of the decomposed liquid is
achieved.
[0007] As shown in the drawings, the inlet of the gasifying furnace
1 is opened, and the plastic wastes can be loaded into the
gasifying furnace 1. The shutter 3 is closed. Then, the plastic
wastes start melting and liquefying, and become fusion-liquid by
the heat of the burner 4. A part of the fusion liquid is
sequentially and pyrolytically decomposed, then gasified. The
pyrolytic gas flows into a gas line G through a gas outlet 5, and
reaches the liquefying tank 2. This liquefying tank 2 integrally
includes a jet scrubber 7, a neutralization column 8, etc. in a
water tank 6 which stores the liquid. The pyrolytic gas reached to
the liquefying tank 2, is contacted with cooling water which
belches up from the jet scrubber 7 having a cooling water circular
line L2 to cause vapor-liquid contact, and thus is rapidly cooled,
condensed and liquefied. Then, the decomposed liquid resulting from
the pyrolytic gas is temporarily stored into the water tank 6
together with the cooling water.
[0008] The above-mentioned blended liquid, which consists of the
decomposed liquid and the cooling water, can be separated into the
decomposed liquid and water at above and below respectively by
specific gravity, after a certain time has elapsed. The decomposed
liquid, which is separated into the upper side of the water tank,
overflows a weir 9 positioned at the end of the water tank 6 and
flows into an oil line L1. After removing solids by filtering
through a filter 10, reclaimed oil or the like made from decomposed
oil can be collected into a recovery tank 12. The water, which is
stored in the lower side of the tank, can be pumped by a pump 11
out from the water tank 6 and re-sent into the jet scrubber 7
through a cooling water circular line L2. Afterwards, the water can
be re-used as cooling water for cooling the high temperature
pyrolytic gas which sequentially flows in.
[0009] The pyrolytic gas which has not been liquefied by the jet
scrubber 7, and detrimental constituents such as chlorine and
bromine which cannot be liquefied by cooling, are sent to the
neutralization column 8 in the form of gas. Then, the pyrolytic gas
can be cooled and condensed again with the newly provided cooling
water from a cooling water line L4, and be simultaneously
neutralized by neutralizer supplied from a neutralization tank 13.
The process makes the pyrolytic gas harmless, and the harmless gas
is retuned to the gasifying furnace 1 via a gas recovery line G2.
Thus, the pyrolytic gas can be recycled as fuel gas, combustion
air, etc. for the burner 4. Also, the exhaust combustion gas which
is emitted from the burner 4, flows into an exhaust gas line G1
through a jacket 16 which covers the gasifying furnace 1, and is
discharged into the atmosphere after being cleaned and filtered by
a filter 14. On the other hand, the superfluous cooling water which
is stored in the water tank 6 of the liquefying tank 2 can be
sequentially discharged through an exhaust line L3.
[0010] According to the above-described plastic liquefying device,
it makes it possible to efficiently dispose of plastic wastes which
were difficult to dispose of in the past. The plastic wastes can be
recycled as burnable reclaimed oil, so that it promotes the
economic and efficient recycling of plastic wastes. In regards to
the above-mentioned process of recycling plastic wastes, it
displays excellent effects such as the removal of the local area
pollution, because in principal there is no possibility of any
toxic gas leak. The reference numeral 15 denotes a hopper which
facilitates the loading of plastic wastes into the device.
[0011] However, a few problems remain as described below, regarding
the above-mentioned plastic liquefying device.
[0012] (1) After plastic wastes are loaded into the gasifying
furnace 1, the inlet of the gasifying furnace 1 is completely
closed by a plate shutter 3. As shown in FIG. 13A and FIG. 13B, the
shutter 3 engages with rails 17 and 17 which are located at both
sides of the shutter 3, and can be horizontally moved to open and
close along the rails 17 and 17 by a rack-and-pinion mechanism
driven by a motor 18. When the shutter 3 is closed, it is simply
placed by its specific gravity on the sealing surface S of the
inlet. Therefore, there would be a possibility that when the
pressure in the gasifying furnace 1 is increased, the gas which is
thermally decomposed may leak from the gap between the shutter 3
and the inlet, whereby the surrounding environment may be
contaminated, the inner pressure may be lowered, and the amount of
the thermally decomposed gas supplied may be decreased. Also, the
plastic wastes and dirt may adhere to the sealing surface S of the
inlet while loading the plastic wastes. Then the shutter 3 may not
be closed completely, consequently leaving a gap between the
shutter 3 and the inlet, and resulting in similar
inconveniences.
[0013] (2) Also, if the solids (insolubles) such as dirt, metal
scraps or timber are adhered to the plastic wastes which will be
processed in the gasifying furnace 1, these solids may accumulated
or sticked to the bottom of the gasifying furnace 1 as residua, so
that not only is the capacity of the furnace decreased but also the
degree of heat conductivity may drastically deteriorate, because
the accumulated solid may act as a heat insulant of the bottom of
the furnace.
[0014] Therefore, regular removal of this accumulated solid is
necessary, but this entails manual labor. Consequently, the device
needs to be turned off and must be in a deactivated condition until
the inside of the gasifying furnace 1 is cooled down completely.
Then, workers have to remove the solid from the inlet with a
scraper, a vacuum cleaner or the like, so that the work efficiency
is drastically deteriorated and also the cleaning work is
burdensome.
[0015] (3) In the liquefying tank 2, the water and oil are
separated by the specific gravity by way of an overflow system. For
example, substances such as terephthalic acid, which is a
constituent element of PET bottles, when heated, directly breaks
down into condensation without liquefying, so that the substances
accumulate into the bottom of water tank 6, and this makes it
difficult to collect them by the specific gravity separation. Thus,
there is a limit on the types of plastic that can be dealt with. In
addition, when the various kinds of mixed plastics are disposed,
the process needs further labor work to separate the plastics
depending upon the types of plastic before the disposal.
[0016] (4) Also, when plastic wastes such as injectors and
catheters from medical institutions such as hospitals and clinics
which may possibly contain infectious bacterial pathogen are
disposed, it is necessary for such plastic wastes to be disposed
after being submitted to sterilization for a given length of time
under high pressure and high temperature. However, if the plastic
wastes are disposed by the above-mentioned liquefying device in the
same way as the normal plastic wastes disposal, in the initial
process, the infectious bacterial pathogen which is adhered to the
surface of these plastic wastes, is not sterilized completely and
flows into the liquefying tank 2 together with the vapor.
Consequently, the infectious bacterial pathogen may possibly
contaminate the inside of the device or interfuse with the
reclaimed oil.
DISCLOSURE OF THE INVENTION
[0017] One aspect of the present invention concerns a plastic
liquefying device, which comprises a gasifying furnace for
generating pyrolytic gas by heating and melting plastic wastes and
a liquefying tank for liquefying the pyrolytic gas generated in the
gasifying furnace and then separated. The gasifying furnace further
includes a heating means provided at the bottom of the oven-shaped
furnace body having an inlet at the top thereof for heating the
inside of an oven-shaped furnace body, and an opening and closing
mechanism positioned at the inlet for opening and closing the
inlet. The opening and closing mechanism further includes a plate
shutter which is larger than at least the opening area of the inlet
and a locking means for securing the shutter to the sealing surface
of the peripheral edge of the inlet.
[0018] Since the inlet for the plastic wastes can be hermetically
closed, the lowering of the pressure inside the furnace due to gas
leakage and the deterioration of the surrounding environment can be
certainly prevented.
[0019] The shutter may include a sliding means for causing the
shutter to move horizontally so as to open and close the inlet. For
example, the sliding means can employ hydraulic cylinders, one end
of which is connected to the shutter, and the other end is
pivotably connected to the furnace body. Then, it is able to
quickly open and close the inlet.
[0020] If the hydraulic cylinders which secure the shutter onto the
sealing surface by way of pressure is employed as the
above-mentioned locking means, the shutter can be completely
closed.
[0021] If a purge gas header is provided at the peripheral edge of
the inlet to spray purge gas onto the sealing surface of the inlet,
thereby catching dust on the sealing surface, the sealing effect is
prevented from being impaired.
[0022] If the bottom part of the furnace body has a corrugated
shape defined by a plurality of canaliculate members which are
placed parallel to each other, the superficial area of the bottom
part of the furnace is enlarged. Then, the heat conductivity from
the heating means to the furnace body can be enhanced, and an
efficient melting process can be also promoted.
[0023] Each end of each of canaliculate members may merge to a
discharge pipe, and also the canaliculate members and the discharge
pipes may respectively include screw conveyers inside themselves.
Then, the solids which have not been melted and have accumulated at
the bottom of the furnace are easily discharged. Accordingly, the
decrease of the furnace body capacity and the deterioration of the
heat transmission can be avoided.
[0024] The heating means may include a gas burner. A jacket may be
provided around the furnace for guiding the exhaust gas from the
gas burner, and parting strips may be positioned spirally inside
the jacket. The heat from the heating means is then efficiently
transmitted to the furnace body, and the efficient melting is
further promoted.
[0025] Another aspect of invention concerns a plastic liquefying
device, which includes a gasifying furnace for generating pyrolytic
gas by heating and melting plastic wastes and a liquefying tank for
liquefying the pyrolytic gas generated in the gasifying furnace and
then separating the pyrolytic gas. The gasifying furnace includes a
vertical tube shape furnace body to receive infectious plastic
wastes, a heating means for heating the furnace body from its
surroundings to generate the pyrolytic gas by pyrolytically
decomposing the infectious plastic wastes, and an agitator to
agitate the inside of the furnace body. The top of the furnace body
includes an inlet to receive the infectious plastic wastes, a lid
to open and close the inlet and a gas outlet to discharge the
pyrolytic gas. The gas outlet has an opening and closing valve
which automatically opens and closes.
[0026] Accordingly, the furnace body can be hermetically sealed and
the inside of the furnace body can be filled with high-pressure
steam, so that the sterilization or removal of infectious bacterial
pathogen which has adhered to plastic wastes can be completely
undertaken.
[0027] Also, the above-mentioned furnace body may be made of a
pressure vessel which includes hemispheric metal end covers
respectively positioned at the top and bottom of the vertical
tube-shaped metallic sack body. The opening and closing lid and gas
outlet may also be provided at the top of the furnace body.
Consequently, the inside pressure of the furnace body can be safely
increased.
[0028] In addition, the above-mentioned agitator may include a
drive shaft which is located at the shaft center part of the
furnace body, a driving motor which rotates the drive shaft and a
plurality of moving vanes which radially extend from the drive
shaft. The moving vanes may revolve in contact with the bottom of
the furnace body. So, when the plastic wastes are melted, an
efficient pyrolytic decomposition can be conducted by agitating the
inside of the furnace, and the deterioration of the heat
transmission which can be caused by the solid or the like
accumulated at the bottom of the furnace can be prevented.
[0029] If the bottom of the furnace further includes an outlet to
discharge insolubles, the insolubles which have accumulated at the
bottom of the furnace can be easily removed by driving the
agitator. Accordingly, the cleaning of the inside of the furnace
does not entail a large amount of labor and time.
[0030] Still another aspect of the present invention according to
the present invention concerns a plastic liquefying device which
comprises a gasifying furnace for generating pyrolytic gas by
simultaneously melting various types of plastic wastes, and a
liquefying tank for liquefying and separating the pyrolytic gas
generated in the gasifying furnace. The bottom of the gasifying
furnace is narrowed like a valley shape, which further includes a
screw conveyer and a discharge opening for discharging insolubles
at the bottom.
[0031] With this liquefying device, it is also easy to discharge
insolubles, which have not been melted and have accumulated at the
bottom of the surface, by driving the screw conveyer. Therefore,
the decrease of the furnace body capacity and the deterioration of
the heat transmission can be avoided.
[0032] The liquefying tank which may be a landscape water tank, may
include a jet scrubber, which sprays cooling water onto the
pyrolytic gas and condenses the pyrolytic gas, and a cleaning
column, which cleans the exhaust gas. The bottom of the water tank
may be narrowed like a funnel form. The bottom part may be
connected to a drain line, and the middle part of the water tank is
connected to an oil recovery line, so that the oil and water are
separated, and the other substances of which specific gravity holds
heavier than water can be certainly separated.
[0033] In addition, the drain line may include a neutralization
tank for infusing the neutralizer. Therefore, the separated water
can be efficiently neutralized. Consequently, the inconveniences
such as acid corrosion of the pipes or the like caused by the acid
water can be avoided.
BRIEF DESCRIPTION OF THE DRAWINGS
[0034] FIG. 1 is a longitudinal sectional view, which shows an
embodiment of the gasifying furnace of the present invention;
[0035] FIG. 2 is a cross-sectional view taken along the line A-A in
FIG. 1;
[0036] FIG. 3 is a cross-sectional view taken along the line Y-Y in
FIG. 1;
[0037] FIG. 4 is a cross-sectional view taken along the line Y-Y in
FIG. 1;
[0038] FIG. 5 is an enlarged partial view of the A part in FIG.
1;
[0039] FIG. 6 is an enlarged partial view of the A part in FIG.
1;
[0040] FIG. 7 is an enlarged partial view of the A part in FIG.
3;
[0041] FIG. 8 is an enlarged partial view of the B part in FIG.
3;
[0042] FIG. 9 is an enlarged partial view of the A part in FIG.
1;
[0043] FIG. 10 is a cross-sectional view taken along the line Z-Z
in FIG. 1;
[0044] FIG. 11 is an enlarged partial view of the B part in FIG.
2;
[0045] FIG. 12 is a whole scheme diagram, which shows a
conventional plastic liquefying device;
[0046] FIG. 13 is an enlarged partial view of the conventional
plastic liquefying device's gasifying device;
[0047] FIG. 14 is a longitudinal sectional view, which shows
another embodiment of the gasifying furnace in the present
invention;
[0048] FIG. 15 is a cross-sectional view taken along the line A-A
in FIG. 14;
[0049] FIG. 16 is a graph, which shows the relationship between the
temperature and the pressure inside of the gasifying furnace shown
in FIG. 14;
[0050] FIG. 17 is a whole scheme diagram, which shows an embodiment
of the plastic liquefying device as it is in the present invention;
and
[0051] FIG. 18 is a cross-sectional view taken along the line A-A
in FIG. 17.
BEST MODE FOR CARRYING OUT THE INVENTION
[0052] Hereinafter, the best mode of the present invention will be
described in reference to the accompanying drawings.
[0053] FIG. 1 is a longitudinal sectional view, which shows an
embodiment of gasifying furnace 19, which is a part of the plastic
liquefying device in the present invention. FIG. 2 is a
cross-sectional view taken along the line X-X in FIG. 1.
[0054] As shown in the drawings, the gasifying furnace 19 comprises
an oven-shaped furnace body including a plastic wastes inlet H, an
opening and closing mechanism 21 for opening and closing the inlet
H, and a heating means for heating the furnace body from its
exterior. The furnace body has a structure which is covered with an
insulative casing 23.
[0055] The furnace body 20 is made of a metal such as hastelloy,
stainless-steel or superalloy which has an excellent heat
resistance, corrosion resistance, and heat conductivity effect. The
plastic wastes which are loaded from the inlet H are melted by the
heating means 22 and pyrolytically decomposed. The pyrolytic gas is
supplied sequentially into the above-mentioned liquefying tank from
a gas outlet 20a.
[0056] The opening and closing mechanism 21 includes a plate
shutter 24 for opening and closing the plastic wastes inlet H and a
locking means 25 for locking the shutter 24 by pressing the shutter
24 onto sealing surface S which is formed around the peripheral
edge of the inlet H.
[0057] As shown in FIG. 3 and FIG. 4, the shutter 24 has a similar
shape to the inlet H which opens in a rectangle shape. The shutter
is made of a heat resistant rectangle plate, which is sufficiently
larger than the aperture area of the inlet H. In addition, the both
side of the shutter includes two pairs of wheels 26, 26, 26, 26 (4
wheels in total) (either one or two pairs). Since these wheels run
along a pair of rails 27 and 27 which extend horizontally from both
sides of the inlet H, the shutter is horizontally moved by a
sliding motion to the inlet H. Also, both side ends of the shutter
24 integrally include brackets 28 and 28 which extend in an
orthogonal direction to the shutter's movable direction, and the
inlet H is opened and closed by sliding the shutter 24 in a
horizontal direction by way of a sliding means, which includes a
pair of hydraulic cylinders 29 and 29. That is to say, both one end
of each hydraulic cylinder 29 is fixed to a bracket 28 of the
shutter 24 while the other side is fixed to the bracket 30 of an
inlet casing 23a. Consequently, as shown in FIG. 4, by
simultaneously expanding and contracting the hydraulic cylinders 29
and 29 from brackets 30 and 30 which are starting points, the
shutter 24 is controlled to be easily opened and closed.
[0058] As shown in FIG. 1 and FIG. 2, the locking means 25 includes
totally four hydraulic cylinders 31 which each pair of which is
provided at back and forth respectively and vertically supported on
the upper part of the inlet casing 23a, and channel shape presser
claws 32, which are provided at the each corner of shutter 24. When
the shutter 24 is closed, each presser claw 32 and each cylinder
rod 33 of each hydraulic cylinder 31 are engaged with each other.
Thus, the shutter 24 is secured by engaging the presser claws 32 to
the piston rods 33 so that the inlet H is completely closed.
[0059] As shown in FIG. 5 to FIG. 8, each of cylinder rods 33, 33,
33, 33 includes circular plate shape collars 34. After the presser
claws 32 are fitted with piston rods 33, the cylinder rods 33 are
extended and their collar parts 34 forcibly press presser claws 32
down. Accordingly, the shutter 24 is pressed onto the sealing
surface S at each of four collar parts. After closing the inlet H
completely by the shutter 24, pulling the cylinder rods 33 in an
upper direction results in easy unlocking of the shutter 24 to
resume a sliding.
[0060] When the shutter 24 is pressed forcibly down to the inlet H,
and the rails 27 and 27 which support the shutter 24 are fixed, the
vertical movement of the shutter 24 is limited by the wheels 26.
Therefore, as shown in FIG. 1 and FIG. 3, in the present
embodiment, the rails 27 and 27 are divided into two parts in a
longitudinal direction. As shown in FIG. 5 and other drawings, the
divided rail segments 27a and 27a which are arranged at the side of
the inlet H are supported by a coiled spring 35 to be able to move
in a vertical direction. As shown in FIG. 6, the rail segments 27a
and 27a is movable in the up and down directions with the shutter
24, so that the vertical movement of the shutter 24 is not limited.
In addition, as shown in FIG. 5, the end of rail segments 27a and
27a are connected with H-shape connecting beam 36. The cylinder
rods 33 may further include another collar part 37 connecting with
the connecting beam 36, so that the divided rails 27a and 27a are
simultaneously movable with the vertical movement of the cylinder
rods 33.
[0061] As shown in FIG. 11, at the peripheral edge of the inlet H
of the furnace body 20, a purge gas header 38 is extends along the
perimeter of the peripheral edge. By spraying the purge gas
supplied from the purge gas tank or the like (not shown) onto the
sealing surface of the inlet H through a slit which opens at the
upper part of the purge gas tank, even if a part of plastic wastes
and dirt are adhered or accumulated on the sealing surface H, it is
possible to remove them from the sealing surface S by the pressure
of the purge gas. A slit 39 includes a guide piece 40 to guide the
purge gas into the direction of sealing surface H. The guide piece
40 is made of a flexible blade spring. When the shutter 24 is
opened or closed, the guide piece 40 is easily deflected, so that
there is no interference with the shutter 24.
[0062] As shown in FIG. 1, FIG. 2 and FIG. 10, the bottom part of
the furnace body 20 forms a corrugated shape by having a plurality
of canaliculate shape members 20b, 20b . . . in parallel to each
other. The each end of the canaliculate shape members 20b, 20b . .
. includes a similar canaliculate shape discharge pipe 20C to merge
extending herefrom. The bottom area of the furnace body is larger
than a flat plate bottom. In particular, it is about 1/2.pi. rtimes
larger than the flat plate bottom area.
[0063] Further, the inside of each of the canaliculate shape
members 20b, 20b . . . and the discharge pipe 20c coaxially include
rotatable screw conveyers 41, 41 . . . which extend in a
longitudinal direction, so that the insolubles accumulated at the
bottom of the furnace, such as dirt, metal scrape, a glass, or
sludge, are forcibly scraped from the bottom wall of the furnace
and discharged from the discharge opening 42 which is formed on the
casing 23 through canaliculate member 20b, 20b . . . to the
discharge pipe 20c. The discharge opening 42 includes an opening
and closing valve (not shown). Of course, the valve is closed while
in operation in order not to leak any melting liquid or give off
any pyrolytic gas from the discharge opening 42 to the outside.
[0064] Each end of rotation axis of the screw conveyers 41,41 . . .
which are provided in the canaliculate shape members 20b, 20b . . .
penetrates casing 23 and extends to the outside respectively. Each
end of the axis of the screw conveyers 41 further includes pulleys
43, 43 . . . respectively. By connecting each pulley 43 to a
scraping motor 44 which is fixed to the outside of the casing, with
a belt 45, the screw conveyers 41,41 . . . can be rotated
simultaneously in the same direction.
[0065] The end of rotation axis of the screw conveyer 41 which is
located in the side of the discharge pipe 20c, also penetrates the
casing 23 and extends to the outside. The screw conveyer is rotated
by connecting the pulley 46 located at the end of the screw
conveyer to a discharge motor 47 with a belt 48.
[0066] As shown in FIG. 11, reinforcing plates 49,49 . . . which
are band plate shapes, and extend in an elongated direction are
provided among the canaliculate shape members 20b, 20b . . . . A
metal heat gauge 50 is embedded in the reinforcing plate 49. The
strength of the bottom furnace is maintained by these reinforcing
plates 49, 49 . . . . The temperature of the bottom furnace can be
measured at any time by the metal heat gauge 50. In addition, the
temperature information read on the metal heat gauge 50 is input
into the control unit which controls output from a gas burner which
will be described hereinbelow.
[0067] As shown in FIG. 1 and FIG. 2, a heating means 22 for
heating the furnace body 20 includes a combustion chamber 51 which
is located at the bottom of the furnace body 20, a gas burner 52
which is provided in the combustion chamber 51 and a jacket 53
which covers around the furnace body 20 while maintaining a certain
distance from it. The furnace body 20 can be heated from its bottom
part by combustion gas generated in the combustion chamber 51 by
the gas burner 52. The exhaust combustion gas is guided into the
jacket 53 which is communicated with the combustion chamber 51 and
further guided to the outside from an exhaust gas exit 54 which is
located at the top part of the jacket 53. Because of this
structure, the furnace body 20 can be heated from its lateral side
and its surroundings.
[0068] The present embodiment further includes parting strips 55
which spirally separate the inside of the jacket 53. The high
temperature exhaust combustion gas which is guided into the jacket
53 is not directly flown into the gas exit 54, but the gas is
spirally flown around the furnace body 20 by the parting strips 55.
Consequently, it makes it possible to cause the longest contact
between the high temperature exhaust combustion gas and the furnace
body 20. As shown in FIG. 1 and FIG. 2, the reference numeral 56
denotes a maintenance hatch for opening and closing the combustion
chamber, and the reference numeral 57 denotes its opening and
closing lid. The reference numerals 58 and 58 denote supporting
legs for the furnace body. The reference numeral 59 denotes a
hopper to facilitate the loading of the plastic wastes. The
reference numeral 60 denotes a view port for checking the inside of
the combustion chamber 51.
[0069] In the gasifying furnace 19 of the present invention which
has the above-described structure, the shutter 24 which closes the
inlet H of the furnace body 20 is closed in such as that the
shutter 24 is pressed to the sealing surface S of the inlet H by
way of hydraulic cylinders 31, presser claws 32 and the like.
Therefore, even if the inside of the pressure of the furnace body
20 is raised during its operation, the gap between the shutter 24
and the sealing surface S can not be compromised. Accordingly,
inconveniences such as contaminating the surrounding environment
because of harmful pyrolytic gas leaks can certainly be
prevented.
[0070] In addition, the peripheral edge of the inlet H includes a
purge gas header 38. When the shutter 24 is closed, the high
pressure purge gas is sprayed onto the sealing surface S from the
purge gas header 38 in order to certainly remove the part of the
plastic wastes and dirt from the sealing surface, which may be
attached when the plastic wastes are placed. Therefore, it is
certainly avoided to compromise the gap on the sealing surface
because of the attachment of the dirt, or the like.
[0071] The surface of the bottom of the furnace body 20 is enlarged
by forming a corrugated surface at the bottom of the furnace body
20 with a plurality of canaliculate shape members 20b, so that the
contact surface between the high temperature generated combustion
gas and the bottom of the furnace is enlarged. Consequently, the
heating efficiency of the furnace body 20 is improved and efficient
melting or pyrolytic decomposition can be achieved. Moreover, the
screw conveyers 41 are provided in the canaliculate shape member
20b or the like, so that solids, sludge, or the like which has
accumulated or attached to the bottom of the furnace are scraped
from the bottom of the furnace and are easily removed. Accordingly,
there is no need to remove them by hand, which was previously
burdensome work in the conventional device. Also, the removal can
be done even when the furnace body maintains a high temperature, so
that the down time of the furnace body is curtailed and a high
operating rate can be maintained.
[0072] The metal heat gauge 50 for measuring the temperature of the
bottom of the surface is provided at the bottom of the furnace, so
that it is possible to accurately measure the temperature of the
whole furnace body 20 together with a conventional furnace body
heat gauge. For example, when the temperature gap between the
temperature of the bottom of the furnace measured by the metal heat
gauge 50 and the temperature of the inside of the furnace body 20
measured by the furnace body heat gauge is small, it can be
determined that the gasifying process has not finished and the
operation should be maintained. On the other hand, when the
temperature gap exceeds a predetermined value, it can be determined
that the gasifying process has finished.
[0073] In the operating method of the plastic wastes furnace
according to the present embodiment, it is necessary to add some
water at the same time or about the time when the plastic wastes
are loaded at its initial operation stage, which is same as in the
above-mentioned conventional device. However, because of the
corrugated shape of the furnace bottom, the contact surface between
the loaded plastic wastes and the bottom of the furnace (furnace
wall) is decreased. Consequently, in the initial operation stage,
there is a possibility that the heat transmission (melting) cannot
be performed under the best conditions. For example, if a small
amount of high boiling oil such as reclaimed oil is added with the
water, following the water evaporation, the high boiling oil
evaporation could be carried out. Accordingly, even if the contact
surface between the plastic wastes and the heat transmission
surface (furnace wall) is small, the heat transmission can be
efficiently carried out, and effective melting can be
accomplished.
[0074] FIG. 14 is a longitudinal sectional view which shows an
embodiment of another gasifying furnace 60 for gasifying the
infectious plastic wastes which especially have a possibility of
the attachment of the infectious bacteria pathogen in injectors or
the like compared with the above-mentioned plastic wastes. FIG. 15
is a cross-sectional view taken along the line A-A in FIG. 14.
[0075] As shown in the drawings, the gasifying furnace 60 mainly
includes an elongated tube shape furnace body 61 for pyrolitically
decomposing infectious plastic wastes and generating pyrolytic gas,
a heating means 62 for heating the furnace body 61 from its bottom
and an agitating means 63 for mixing the inside of the furnace body
61.
[0076] The furnace body 61 is made of a metal such as hastelloy,
stainless-steel or superalloy which has an excellent heat
resistance, corrosion resistance, and heat conductivity effect. The
furnace body 61 is a pressure vessel, in which top and bottom of a
longitudinal tube shape sack body 64 respectively include
hemispheric end covers 65 and 66. An inlet 67 for the placement of
the plastic wastes is provided at the top end cover 65. Moreover,
the inlet 67 can be opened and closed by the flanged type opening
and closing lid 68. The inlet 67 is connected to the feed water
pipe 69 for feeding water to promote melting in the initial stage.
The feed water pipe 69 can be opened and closed by a magnetic valve
V.
[0077] A gas outlet 70 is provided at the upper part of the sack
body 64, and pyrolytic gas which is generated by the furnace body
61 can be guided into the above-mentioned liquefying tank 2.
Moreover, the gas outlet 70 also includes an automatic opening and
closing valve 71 and the gas outlet 70 can be automatically opened
and closed by a predetermined condition which is mentioned
below.
[0078] The bottom end cover 66 of the furnace body 61 includes an
insoluble vent 72 for removing insolubles such as sand or metal
pieces, which have accumulated at the furnace bottom, as
needed.
[0079] The heating means 62 includes a combustion chamber 73
located at the bottom of the furnace body and jacket 74 which
covers the surrounding area of the furnace body 61 from the
combustion chamber 73. A heating device 75 located in the
combustion chamber 73, such as a gas burner, an oil burner or an
electrical heater, directly heats the furnace body 61 from its
bottom. When the gas burner, the oil burner or the like which
utilizes fossil fuel is employed as the heating device 75, the high
temperature of combustion gas generated in the combustion chamber
73 is guided into the exhaust gas outlet 76 through jacket 74.
Accordingly, the furnace body can be heated evenly over its entire
body.
[0080] An agitator 63 located in the furnace body 61 includes a
drive shaft 77 which is positioned in the shaft center part of the
furnace body 61, a driving motor 78 which is installed at the upper
part of the drive shaft 77 to rotatably drive the drive shaft 77,
and a plurality of moving vanes 79, 79, 79, 79 which radially
extend from the bottom part of the drive shaft 77, to efficiently
melt the infectious plastic wastes loaded in the inside of the
furnace body 61 by mixing and heating the wastes evenly. As shown
in FIG. 2, the tips of the moving vanes 79, 79, 79, 79 are curved
toward the down stream side of the rotative direction, and the
bottoms of the moving vanes 79 are normally in contact with the
bottom of the furnace. When the moving vanes revolve and slide on
the bottom surface like scraper, the attachment and accumulation of
stickum, insolubles or the like to the bottom of the furnace can be
prevented.
[0081] One example of the operation method for the gasifying
furnace 60, which has the above-mentioned structure of is described
below.
[0082] Firstly, as shown in FIG. 14, after an inlet 67 positioned
at the top of the furnace body 61 is opened, infectious plastic
wastes and a small amount of water are loaded into the inside of
the furnace body 61. Then, an automatic opening and closing valve
71 of a gas outlet 70 and a valve V of the water feed pipe 69 are
closed. In other words, the furnace body 61 is hermetically closed,
and the furnace body 61 can be heated by the heating means 62 with
driving an agitator 63.
[0083] In the furnace body 61, firstly water which has a lower
boiling point starts evaporating by the heating mentioned above.
Following to the evaporation, the pressure and the temperature
inside the furnace body are gradually raised, as shown in FIG. 16.
The heating means 62 is adjusted as needed to keep the pressure or
temperature which eradicates infectious bacterial pathogen, for
example, as shown in FIG. 16, the saturation pressure can be
established at 121.degree. C. water temperature, and the condition
is maintained for a predetermined time of period, twenty minutes,
for example. Then, the infectious bacterial pathogen which is
attached to the plastic wastes is completely eradicated by steam
sterilization un der pressure. Therefore, there is no possibility
that the infectious bacterial pathogen flows into the liquefying
tank 2 together with pyrolytic gas.
[0084] Thus, after meeting the condition in which the infectious
bacterial pathogen is completely sterilized, as shown in FIG. 16,
the inside pressure of the furnace body 61 can be decreased by
gradually opening the automatic opening and closing valve 71 of the
gas outlet 70. At the same time, the inside temperature is raised
by increasing the energy output of the heating means. In the
furnace body 61, following the evaporation of the water which has
placed at the first stage of the operation, plastic wastes start
melting. Also, the temperature is increased, and when the
temperature reaches the gasifying temperature, for example
380.degree. C., the melt liquid is pyrolitically decomposed and
gasified. The pyrolytic gas is sequentially guided into the
liquefying tank 2, and then the oily water separation, which is
conducted in the same way as the conventional process, is
undertaken. Such reclaimed oil or the like can be effectively
utilized.
[0085] In the gasifying furnace 60 according to the present
embodiment, it is possible that the furnace body 61 can be
hermetically closed with high pressure and under high temperature
for a certain period of time, so that the infectious plastic wastes
such as injectors or catheters for infectious disease, in which the
infectious bacterial pathogen is attached, can be pyrolitically
decomposed of safely and surely.
[0086] After all the plastic wastes loaded inside the gasifying
furnace 60 has pyrolitically decomposed, the same disposal process
can be repeated by butch processing. However, in cases of metal
pieces such as injector needles or insolubles (solid) such as dirt
which have gradually accumulated inside the furnace body during
pyrolytic decomposition, the insolubles disposal exit 72 at the
bottom of the furnace body 61 can be opened, and the insolubles can
be easily removed by revolving the moving vanes 79 of the agitating
means 63. Accordingly, disadvantages such as the deterioration of
the heat transmission and the decrement of the furnace capacity,
which are caused by the attachment and accumulation of the
insolubles at the furnace bottom, are easily eliminated.
[0087] FIG. 17 and FIG. 18 show other embodiments of the plastic
liquefying device according to the present invention.
[0088] As shown in the drawings, this plastic liquefying device
mainly comprises a gasifying furnace 80 for melting plastic wastes,
generating pyrolytic gas and a liquefying tank 81 for condensing
and separating the pyrolytic gas which is generated in the
gasifying furnace 80, similar to the conventional device.
[0089] Firstly, as shown in FIG. 1 and FIG. 2, the gasifying
furnace 80 comprises a heating means 83 for heating a furnace body
82 from its exterior. The heating means is located in the furnace
body 82 having an inlet H at its upper part. The variety of mixed
plastic wastes (which are limited to the thermoplastics) which are
loaded from the inlet H, are melted by the heating means 83, and
gasified. The pyrolytic gas is guided into the liquefying tank 81
through a gas line G1 from a gas outlet 84.
[0090] A closure lid 85 is connected to the end of the inlet H
located at the furnace body 82 by way of hinges. The closure lid 85
is arbitrarily opened and closed by an opening and closing member
86 such as a motor cylinder, which is positioned between the bottom
surface of the closure lid and the wall of the inside furnace body
82.
[0091] The bottom of the furnace body 82 curves into a valley shape
toward its center. A screw conveyer 87 which extends in a
horizontal direction is provided at the bottom part of the valley
shape. As shown in FIG. 2, the screw conveyer 87 integrally
includes a spiral screw 89 around a rotation axis 88 which extends
along an elongated direction of the bottom part of the valley
shape. One end of the rotation axis 88 penetrates the furnace body
82 and connects to a driving motor 90 which is located outside, so
that the axis of rotation 88 revolves in both directions by the
driving motor 90. The other end of the rotation axis 88 includes a
discharge opening 91. The discharge opening 91, which can be opened
and closed, is closed by an exhaust lid 92.
[0092] As shown in FIG. 1, the heating means 83 for heating furnace
body 82 includes three flat shape heaters 93, 94, 95. The flat
shape heater 94 is located at the bottom of the furnace body 22,
and the flat shape heaters 93 and 95 are located at the both sides
of the bottom part, and independently operate.
[0093] The liquefying tank 81 liquefies the pyrolytic gas which is
guided from the gas line G1 and stores the pyrolytic gas
temporarily. A landscape tank 96 includes a jet scrubber 97 which
sprays cooling water onto the pyrolytic gas guided from the gas
line G1 and condenses it, and a cleaning column 98 which cleans and
exhausts unliquefied gas which has not liquefied by the jet
scrubber 97.
[0094] The bottom of the water tank 96 narrows into a funnel-like
shape. The rock bottom part is connected to a drain line L1 through
a valve V1 and the middle part is connected to an oil recovery line
L2 through a valve V2.
[0095] This drain line L1 includes a strainer 99 and a circulating
pump 100. The drain line L1 extracts water from the water tank 96,
circulates the water to the above-mentioned jet scrubber 97 and the
cleaning column 98, and also returns a part of the water to the
above-mentioned gasifying furnace 80 through a return line L3. In
addition, the return line L3 and its branch part include lines L1,
L3, a scrubber line L4 and magnetic valves V3, V4, V5, V6 which
respectively open and close the cleaning column line L5.
[0096] Also, the drain line L1 is connected to a neutralization
tank 101 via a branch line L6 and a valve V7, and the water
extracted from tank 96 is neutralized by injecting the neutralizer.
A cooling water line L9 and valve V9 branch off from the scrubber
line L4, and cooling water (tap water) is supplied to the jet
scrubber 97. Furthermore, the oil recovery line L2 includes a
reclaimed oil tank 102, and the reclaimed oil, which was separated
in the water tank 96, is extracted from the oil recovery line L2
and stored.
[0097] A cleaning column 98 includes an upper spray nozzle 104, a
demister 105, a lower spray nozzle 106 and a baffle plate 107 in
orders from the top in the vertical column body 103. The pyrolytic
gas, which has not been liquefied by the lavation (tap water, etc.)
that flows from a cleaning column line L5 and a cooling water line
L10, is cleaned and then sent to the exhaust line L7. Also, the
exhaust line L7 includes a pre-heater 108 and a catalytic
deodorizer 109, so that the gas is pre-heated and deodorized, and
then is released to the atmosphere.
[0098] In the drawings, the reference numeral 110 denotes a level
meter for measuring liquid level in the water tank and the
reference numeral 111 denotes a translucent liquid level meter for
checking the condition of the oily-water separation from the
outside. Also, the reference numeral 112 denotes a heat insulating
material for preventing the gas line G1 which extends between the
gasifying furnace 80 and the liquefying tank 81 from cooling
down.
[0099] Next, the operation of the plastic liquefying device
according to the present embodiment, which has above-mentioned
structure, that is to say, the disposal process of the plastic
wastes is described hereinafter.
[0100] Firstly, in the disposal process of plastic wastes, before
loading the plastic wastes into the gasifying furnace 80, a small
amount of water is put into the furnace body 82 of the gasifying
furnace 80. Then the opening and closing lid 85 is closed, and the
furnace body 82 is heated with a condition in which the inside
furnace body 82 is hermetically closed. In this initial stage,
there is no need to operate all flat shape heaters 93, 94, 95 of
the heating means 83, so that only one of the heaters, for example,
the bottom part heater 94 is operated.
[0101] The water placed into the inside of the furnace body 82
evaporates into steam by the heat, and then flows into the
liquefying tank 81 through the gas line G1 from the gas outlet 84.
Furthermore, the steam flows into the drain line L1, the oil
recovery line L2, and the exhaust line L7, etc. from the liquefying
tank 81. Accordingly, the steam expels all the air inside the
device.
[0102] Thus, when the inside of the device is replaced with steam,
the valve V1 of the drain line L1 connected to the liquefying tank
81 and the valve V2 of the oil recovery line are closed. Then, the
opening and closing lid 85 of the gasifying furnace 80 is opened
again, and the plastic wastes to be disposed are loaded into the
furnace body 82 from the inlet H. After the furnace body 82 is
hermetically closed by closing the lid 85 again, the furnace body
82 is heated by the heating means 83.
[0103] After melting and liquefying the plastic wastes which are
loaded in the furnace body 82 by the heating means, the pyrolytic
gas which is sequentially and pyrolitically decomposed, flows from
the gas outlet 84 to the gas line G1, then reaches the jet scrubber
97 of the liquefying tank 81. At this time, as shown in FIG. 18,
the opening and closing lid 85 is secured to the furnace body 82 by
bolts B or the like, so that the inside of the furnace body is
hermetically closed. Accordingly, the pyrolytic gas leak is
completely prevented and the above-mentioned infectious plastic
wastes such as injectors are safely disposed of.
[0104] After that, the pyrolytic gas which has reached the jet
scrubber 97, is contacted with cooling water supplied from the
drain line L1 and the branch line L4 to cause a vapor-liquid
contact, and then the pyrolitic gas is rapidly cooled down and
liquefied into reclaimed oil. The reclaimed oil is sequentially
stored into the water tank 96 together with the cooling water. When
the screw conveyer 97 is revolved, and the inside of the furnace is
agitated, the melting process of plastic wastes in the gasifying
furnace 80 is efficiently accomplished. Also, the pyrolytic gas is
cooled down by way of the jet scrubber 97, so that terephtalic
acids or the like which directly solidifies from the gas, is not
clogged. Thus, it is possible to maintain the efficient gas
circulation. If the jet scrubber is substituted by for example, a
fin-tube heat exchanger, such terephtalic acid which directly
solidifies from the gas, is generated inside the tube, and may
cause blockages by the accumulation of the solid. Even if the gas
is solidified around the exit, the solid can be blown off by the
jet water of the jet scrubber 97. Thus, disadvantages such as
blockage are not caused.
[0105] On the other hand, un-liquefied gas (pyrolytic gas), which
could not be liquefied by the jet scrubber 97, passes though the
upper space of the water tank 96 as it is and after being cleaned
by the cleaning column 98 and also deodorized and purified by the
exhaust gas line L7, the pyrolytic gas exhausts into the
atmosphere.
[0106] Thus, when all the plastic wastes loaded into the gasifying
furnace 80 have been gasified into the pyrolytic gas and have flown
into the liquefying tank 81, the heating of the furnace body 82 is
stopped. At this time, however, if the loaded plastic wastes
include insolubles such as dirt, metal pieces or timber pieces,
they accumulate at the furnace bottom, and cause the decrement of
the furnace cap acity and the deterioration of the heat
transmission from the heating means 83. Accordingly, when such
insolules are accumulated to some degree, as shown in FIG. 18, a
lid 92 of a discharge opening 91 at the furnace bottom and the
screw conveyer 87 are driven. Accordingly, the accumulated
insolubles are carried to the discharge opening 91 and easily
disposed of through the discharge opening 91. Thus, the furnace
body cleaning which is done by workers at the conventional device
is no longer needed.
[0107] The mixed liquid of cooling water and reclaimed oil, which
is stored in the water tank 96 of the liquefying tank 81, is
separated by its own specific gravity after setting for a while. In
other words, the reclaimed oil which has a light specific gravity
can be collected to the liquid surface, and water which has a heavy
specific gravity is collected at the bottom part. Firstly, the
valve V2 of the reclaimed oil line L2 is opened, and the reclaimed
oil at the upper part flows into the reclaimed oil tank 102, so
that only reclaimed oil can be efficiently collected by the
separate collection. After a certain amount of the reclaimed oil
has been removed, the water can be extracted from the bottom
through the drain line L1, which are then recycled as cooling water
for the next process. However, as illustrated, if any substances
such as solid terephtalic acid which specific gravity is heavier
than that of water or oil is contained, it is accumulated in layers
at the bottom of the tank. Therefore, when recycling the water in
the water tank, the constituents which have heavier specific
gravity, need to be previously extracted by the exhaust oil line L8
which branches off from the upper part of the drain line L1. Then,
only the substances which have a heavier specific gravity can be
collected. Also, the water in the water tank can be recycled as
cooling water for the water used at the initial operation and also
as cooling water for the jet scrubber 97 as was mentioned above.
Therefore, the effective utilization of the resource can be
accomplished. If the extracted water includes chlorine or the like,
it may incur acid corrosion of the pipes in each line. Therefore,
the water is neutralized by adding an adequate dose of the
neutralizer such as caustic soda. The water can be then
recycled.
[0108] When the collection of the reclaimed oil is completed, new
plastic wastes can be added, and the process, such as the
above-mentioned heating and gasifying decomposition is carried out
by batch processing. Thus, regardless of its composition, the
majority of the plastic wastes can be efficiently disposed of and
the effective utilization of resources can be accomplished.
[0109] The present embodiment employs the electrical flat shaped
heaters 93, 94, 95 as the heating means 83 of the gasifying furnace
80. However, a gas burner or the like may be alternatively
used.
* * * * *