Process and apparatus for dry distillation of discarded rubber tires

Discarded rubber tires are charged in random state into a vertical dry distillation furnace, and the tires at a lower part thereof are caused to undergo combustion to give off hot combustion gases by which the tires at higher levels undergo dry distillation to produce distillation gases which are useable as fuel. The combustion is started by burners and is then self-sustained by supplying only air. The furnace interior at its part below the combustion zone is expanded or flared in the downward direction to an open end immersed in water, but the downward movement of the tires and residue is braked by a self-sustained grate effect until the residue finally drops out of the furnace to be removed by a conveyor. The continuous and efficient operation over a long period of this furnace is assisted by a separator also capable of long continuous operation.

BACKGROUND OF THE INVENTION 
This invention relates to the dry distillation of overworn discarded rubber 
tires of vehicles and more particularly to a process and apparatus for 
continuously and smoothly dry distilling discarded tires thereby to 
recover gases and liquids for combustion. 
As a consequence of the rapid development of motorization in recent years, 
there has been a tremendous increase in the rate at which overworn or 
worn-out rubber tires (hereinafter referred to simply as tires) of land 
vehicles are being discarded. Of these tires, one portion is being 
reutilized as retreaded tires, but most of the tires are being disposed of 
as refuse. Because of the shape and bulk of tires, however, they cannot be 
disposed of as they are as filling material for land reclamation and other 
purposes, and, in some instances as a stopgap lawful method of land 
reclamation, tires are being cut up into pieces of suitable size and then 
used as filling material. 
Another method of disposal of such tires is the combustion thereof. On a 
small scale, tires are being burned outdoors in agricultural fields and 
orchards for the purpose of preventing frost damage. In this case, 
however, the gases of combustion of rubber have a characteristic bad odor, 
whereby tires cannot be burned in the open except in such emergency cases. 
The quantity of tires used in such instances is a mere 2 to 3 percent of 
the total quantity of tires discarded. 
On the other hand a sudden interest in the utilization of tires as a 
combustible material is becoming apparent as a result of the rise in 
energy costs. This is a natural result because of the high calorific value 
of tires of approximately 8,000 Kcal/kg, and already most of the tires, 
exclusive of those being retreaded, are beginning to be used as a 
substitute fuel. 
However, because of structural features of tires such as their 
characteristic shape and steel wire incorporated therein, direct 
combustion of these tires requires pretreatment such as cutting and an 
after treatment, such as the removal of steel wires from the tires after 
combustion. Furthermore, because of the characteristicly high surface 
density of rubber, the degree of contact of the rubber with air for 
combustion is small, whereby incomplete combustion tends to occur, and 
black smoke and unpleasant odors are easily given off. Combustion of tires 
in large quantities is difficult in actual practice without the use of 
large furnaces affording long combustion zones. 
As another approach, it is also possible, since combustible gases and 
liquid fuels can be generated by dry distilling rubber at relatively low 
temperatures, to once extract gas and liquid fuels and to burn them in a 
separate combustion furnace. In this case, the steel wire and other solids 
are left as residue and separated, and even if the distillation furnace 
and the combustion furnace are installed in a spaced apart relation, 
continuous operation is possible by merely connecting them with transfer 
piping for gaseous and liquid fuels, whereby effective utilization is 
readily attainable. 
Accordingly, numerous techniques relating to the dry distillation of tires 
have heretofore been disclosed and proposed. For example, Japanese Patent 
Publication Nos. 25874/1978 and 27752/1978 disclose apparatuses in each of 
which vertical preheating and dry distillation furnaces are coupled in a 
gas-tight manner, and, for horizontally stacking tires therein to carry 
out preheating and dry distillation, respectively, and means for 
horizontally, handling each tire for charging the tires and removing the 
residue must be installed. In the operation of each apparatus, preheating 
and dry distillation proceed as the tires being processed in the furnaces 
descend one at a time, being continually maintained in horizontal state, 
and finally the non-volatile residue is taken out. 
In a furnace of this known character, support of the tires in an orderly 
disposition is maintained within the furnace by a tire supporting 
mechanism comprising a forkshaped tire receptacle provided near the bottom 
of the furnace and functioning as a movable grate. In the dry distillation 
furnace described in Japanese Patent Publication No. 27752/1978, a 
butterfly-shaped grate is separately provided below the support fork to 
function cooperatively in supporting the tire charged into the furnace and 
in taking out the dry distillation residue. However, after a long period 
of operation of these apparatuses, problems tend to arise in the taking 
out of the residue. 
Still another proposed furnace is of a construction wherein the inner 
diameter of the vertical furnace is made greater than the outer diameter 
of the tires at the upper part of the furnace and is tapered to become 
smaller than the tire outer diameter at the lower part of the furnace, and 
this constricted lower part is caused to exhibit a grate effect to support 
the tires charged into the furnace. Since there are no support structures 
such as a grate in the interior space of this furnace, there is little 
possibility of substances such as residue and semi-molten material formed 
in the high-temperature part of the furnace being caught or adhering to 
parts of the furnace, and it would seem that the operation can be expected 
to proceed under considerably favorable conditions. 
However, this furnace has a drawback in that it is difficult to take out 
scrap wire after completion of dry distillation and incompletely distilled 
residual tires frequently produced in actual operation because of the 
constriction at the lower part of the furnace. Particularly in the case of 
continuous operation, which almost always means operation over a long 
period, there is a continuous accumulation of residue at the bottom of the 
furnace, whereby removal of this residue tends to become difficult. 
In the case of batch-wise operation, it is possible, upon the completion of 
dry distillation of each batch, to take out the residue, including scrap 
wire, and carbon particles adhering to various interior parts of the 
apparatus as described hereinafter. This work, however, is extremely 
troublesome and requires much time and labor. Furthermore, a batch-wise 
operation unavoidably entails periodic interruptions thereof, whereby a 
stable operation under steady conditions cannot be achieved. 
In view of the above described circumstances in the state of the prior art, 
we have carried out a detailed analysis of the phenomena occurring within 
a dry distillation furnace of the instant character during operation in 
order to facilitate the taking out of the dry distillation residue. As a 
result, from a completely separate line of thinking, we have arrived at 
the conceptual conclusion that the cross-sectional area of the furnace at 
its lower part should be made the same as or greater than that of its 
upper part. Furthermore, we have carried out tests based on this concept, 
as a result of which we have succeeded in developing this invention. 
More specifically, we have carried out studies on the premises: 
(1) that, within a furnace reaching a high temperature, mechanisms which 
can become obstructions to the falling or downward movement of charged 
material must be eliminated as much as possible; 
(2) that, since continuous operation is the general rule, mechanisms such 
as that for holding charged material and that for taking out residue, 
which are used only at the starting and stopping of operation must be 
dispensed with and substituted by a mechanism for continuous operation 
which is most easy to control and, moreover, is efficient for ordinary 
continuous operation; and 
(3) that, for facilitating of tire charging and for uniformity of heat 
distribution within the furnace, the tires charged into the furnace must 
be stacked in random directions. 
As a result, we have found that, during steady operation, the charged 
tires, the residue of these tires, and the like, while combining naturally 
to form suitable gas passages within the furnace, brake and retard the 
charged material in the upper part of the furnace, whereby not only is a 
grate unnecessary, but since the combined mechanism progressively varies, 
it is useful in the stabilization of the furnace condition. Moreover, 
since the dry distillation residue is predominantly steel wire, it is 
extremely bulky, and if there are some obstructions within the furnace, 
this steel wire is readily caught thereby, whereby the taking out of the 
residue is hindered. 
Therefore, it was verified that expanding the furnace cross-sectional area 
in the downward direction is desirable for facilitating the work of taking 
out the residue, that at least there is absolutely no necessity of 
constricting the lower part of the furnace relative to its upper part, and 
that, if the lower diameter is smaller than the upper diameter, trouble 
occurs frequently during the work of taking out the residue. 
It was confirmed further that when the inner diameter of the furnace is 
made constant or is downwardly expanded, bridging blockage or a so-called 
log-jamming effect of the charged tires as they naturally fall or move 
downward is prevented, and that, in addition, the charged tires are 
automatically restacked as they sink while they are dry distilled and 
burned, whereby uniform reaction is facilitated, and the solid materials 
exhibit an effect of forming their own grate. These effects cannot be 
obtained in systems wherein tires are charged horizontally one at a time. 
On the basis of the above described findings and conclusion, we have 
developed a process and furnace for continuously dry distilling tires over 
long periods of time. However, still another problem must be solved before 
this continuous and long-period dry distillation of tires can be 
profitably practiced. That is, one hindrance to the continuous and 
long-period distillation of tires has heretofore been the presence of a 
great quantity of dust particles, comprising principally carbon particles, 
in the gases generated in and discharged from the tire dry distillation 
process step. 
More specifically, oils produced in the dry distillation adhere to these 
dust particles (hereinafter referred to as carbon) to form sticky carbon, 
which adheres to the inner wall surfaces of the apparatus and parts such 
as complicated bent parts and gas passages and, upon accumulating, gives 
rise to various difficulties such as clogging of passages. Accordingly, we 
have developed an apparatus for dry distilling tires which can be operated 
continuously and over long periods under stable conditions within the dry 
distillation furnace, and in which removal of adhering carbon can be 
accomplished without stopping the operation of the apparatus. 
SUMMARY OF THE INVENTION 
According to this invention in one aspect thereof, there is provided a 
process for the dry distillation of discarded tires which comprises 
charging the tires into the upper part of a vertical furnace to cause the 
tires to descend progressively, causing the lower tires to undergo 
oxidation combustion, dry distilling the upper tires with the resulting 
combustion gases, and collecting gaseous fuel and/or liquid fuel thereby 
distilled. The invention is characterized in that the tires are charged 
and stacked in a random state and thus caused to descend through the 
furnace whose horizontal cross-sectional area of its interior at its lower 
part is at least equal to those at higher parts of the furnace, the 
descent of the tires and resulting tire residue being braked by a 
self-formed and self-sustained grate effect until the final solid residue 
descends further to be discharged out of the furnace. 
According to this invention in another aspect thereof, there is provided an 
apparatus for dry distillation of discarded tires comprising: a vertical 
furnace structure having an inlet opening at its top and an open lower end 
part; a feeding device for feeding discarded tires into the inlet opening; 
a leakage-sealing damper disposed in the upper part of the furnace in the 
vicinity of the inlet opening for preventing escape of gases to the 
outside through the upper part; first damper means disposed below and 
apart from the leakage-sealing damper for reserving the tires thus fed and 
subsequently dropping the same into the lower interior of the furnace 
structure constituting a reaction chamber, whose horizontal 
cross-sectional area at said lower end part is at least equal to those at 
higher parts of the furnace, the upper and lower parts of the reaction 
chamber becoming a dry distillation zone and a combustion zone, 
respectively, during operation, an upper chamber being thus formed between 
the leakage-sealing damper and the first damper means, the first damper 
means, when in closed state, sealing the upper chamber from the furnace 
interior below the first damper means; a gas discharge outlet provided at 
the upper part of the reaction chamber for discharging distilled gases; a 
tuyere disposed around the combustion zone for supplying air thereinto; 
burners for combustion mounted in the furnace wall in the vicinity of the 
tuyere for initiating combustion of the tires in the combustion zone; a 
water sealing device for sealing the interior of the open lower end part 
of the furnace structure from the outside air yet permitting residue of 
distillation and combustion to drop out of the furnace structure; and a 
residue discharging device for discharging the residue thus dropped. 
According to this invention in still another aspect thereof, there is 
provided an apparatus as described above which further comprises a 
separator for separating carbon particles from the distillation gases 
obtained from the dry distillation in the dry distillation furnace, the 
separator being connected, preferably by a straight pipe, to the gas 
discharge outlet of the reaction chamber of the furnace and comprising: a 
separating device having an inlet to which the downstream end of said 
straight pipe is connected and operating to separate carbon particles from 
the distillation gases, which are then discharged through an outlet; a 
hopper connected to the bottom of the separating device for collecting the 
carbon particles thus separated; and carbon removers actuated by actuating 
rods of respective actuating means to remove carbon particles from the 
interiors of the gas discharge pipe and the separating device, 
respectively. 
The nature, utility, and further features of this invention will be more 
clearly apparent from the following detailed description with respect to a 
preferred embodiment thereof when read in conjunction with the 
accompanying drawings, briefly described below.

DETAILED DESCRIPTION OF THE INVENTION 
The process of dry distilling tires according to this invention can be 
practiced by means of the apparatus of the invention, one example of which 
is shown in FIG. 1. Broadly considered, this apparatus comprises a dry 
distillation furnace 1 and a separator 2. 
The dry distillation furnace 1 has a vertical furnace structure 3 in the 
form of a hollow tower with a cross-sectional shape such as a circle, a 
square, an oblong rectangle, a polygon, or an ellipse. This furnace 
structure 3, the inner wall surface of which is lined with refractory 
material, has a constant cross-section shape and size over a greater part 
thereof, only its upper and lower end parts being of different shape. The 
lower end part 3a of this furnace structure 3 is outwardly flared and is 
immersed in water in a water-sealing device 4 comprising a tank holding 
the water. The top part of the furnace structure 3 is suitably formed to 
receive tires as described hereinafter and is provided with a 
leakage-sealing damper 5 for sealingly closing the top of the structure 3 
to prevent escape of gases to the outside. The damper 5 is operated by a 
driving device 5a. 
At an intermediate level in the upper part of the structure 3, a first pair 
of horizontal gate dampers 6,6, is provided to operate cooperatively 
across the entire cross section of the structure at that level. A second 
pair of horizontal gate dampers 7,7 similar to the first pair 6,6 is 
provided at a lower level of the structure 3. These gate dampers 6,6 and 
7,7, as well as the above mentioned leakage-sealing damper 5 can be driven 
in their respective opening and shutting action either manually or by 
suitable powered driving devices 6a and 7a, respectively. The interior of 
the furnace structure 3 can thereby be divided into an upper chamber A 
between the damper 5 and the dampers 6,6, an intermediate chamber B 
between the dampers 6,6 and the dampers 7,7, and a lower reaction chamber 
C when these dampers are in closed state. 
The furnace structure 3 is provided around its part enclosing the reaction 
chamber C with an annular tuyere 8 supplied with air for combustion from 
an air source 10, a group of burners 9 supplied with fuel from a fuel 
source for initiating combustion of tires and disposed in a horizontal 
circle in the furnace wall at substantially the same level as the tuyere 
8, and an annular cooling jacket 12 in which coolant such as water flows. 
It has been found that the cooling jacket 12 serves to prevent the molten 
tire material from sticking to the furnace inner wall because the molten 
tire material is cooled by the wall and tends to solidify. A gas discharge 
outlet pipe 13 is provided through the furnace wall at the upper part of 
the combustion chamber C and is connected at its downstream end to the 
separator 2 described hereinafter. 
A conveyor 14 is disposed at its upstream end in the aforementioned 
water-sealing device 4 at a position below the lower end of the furnace 
structure 3. The downstream part of this conveyor 14 extends obliquely 
upward and out of the water-sealing device 4 to a position above a solid 
residue collector 15 and a scrap wire collector 16. 
As mentioned hereinbefore, an important feature of the dry distillation 
furnace in the apparatus of this invention is that the cross-sectional 
area of the interior of the furnace is constant or, as in the instant 
example thereof, expands progressively downward in the part 3a thereof 
below the level where dry distillation is carried out or, preferably, the 
level where oxidation combustion takes place. Moreover, there is no 
grate-like solid object for supporting the tires whatsoever within the 
furnace at its bottom part. 
While there is no particular specification for the degree of expansion or 
flaring of the cross section of the furnace interior at its lower end part 
3a, it should be designed in accordance with factors such as the sizes and 
kinds of the tires or cut-up tires to be processed. For example, in the 
case where a large quantity of tires having a high steel wire content are 
to be distilled, the furnace lower end part 3a should be widely flared. We 
have found, in general, that a flared lower end part 3a is desirable 
although in some cases a lower end part without any flare is suitable. 
In general, this outward flare should be such that the angle between the 
inner wall surface of the lower end part 3a, as viewed in vertical 
section, and the vertical plumb direction is 0 to 10 degrees. By thus 
providing a lower end part 3a of this shape: (1) taking out of the solid 
residue and scrap wire is facilitated; (2) adhering of foreign matter to 
the inner wall surface of the furnace is prevented; and (3) "bridging" or 
log-jamming of solid matter across the furnace is prevented. A flare angle 
exceeding 10 degrees is disadvantageous because it will necessitate an 
increase in the sizes of the water sealing device 4 and the conveyor 14, 
and because it will cause excessive residue to drop onto the conveyor 14, 
which will make residue removal difficult. 
The vertical position at which the furnace structure 3 starts to flare 
outward is determined in accordance with various conditions and factors. 
In the illustrated example, this vertical position is shown to be at the 
level of the cooling jacket 12. This is most desirable. However, the 
flared end part 3a may start at any level between a position immediately 
below the gates 7 and a position below the tuyere 8 and the burners 9. 
The flared lower end part 3a of the furnace 3 may assume various shapes as 
viewed in elevation as indicated by some examples illustrated in FIGS. 4a 
through 4f and assume various shapes at different height levels as viewed 
in cross section as indicated in FIGS. 5a through 5d. 
The above mentioned separator 2 connected to the downstream end of the gas 
discharge pipe 13 comprises, essentially, a separating device 21, which in 
the instant example is a cyclone separator, to whose inlet the pipe 13 is 
connected, a hopper 22 connected to the bottom of the cyclone 21 for 
extracting carbon particles, and a heat exchanger 24, to which the upper 
part of the central outlet tube 33 of the cyclone is connected by way of a 
gas discharge passage 23. The heat exchanger 24 has an outlet 24a and 
operates to cool and separate oils from the gases from which carbon 
particles have been separated in the separating device 21. 
The separator is further provided with a carbon remover 26 disposed within 
the gas discharge pipe 13 and actuated by the actuating rod 25a of an 
actuating cylinder 25, an annular carbon remover 29 disposed within the 
cyclone 21, a carbon remover 28 disposed within the outlet tube 33, the 
carbon removers 28 and 29 being actuated by the actuating rods 27a, 27b 
and 27c of an actuating cylinder 27, and a carbon remover 32 disposed 
within the gas discharge passage 23 and actuated by the actuating rod 31a 
of an actuating cylinder 31. These carbon removers are actuated by their 
respective actuating cylinders to remove carbon adhering to the inner wall 
surfaces of their respective parts in which they are disposed. 
The process of this invention is practiced by means of the above described 
apparatus in the following manner. Whole tires or cut-up tires are 
conveyed by means such as a conveyor 17 into the top part of the furnace 
1. By opening the leakage-sealing damper 5, the tires thus conveyed are 
dropped at random onto the first pair of gate dampers 6,6. 
The leakage-sealing damper 5 is provided to prevent leakage of a portion of 
the gases generated in the furnace which would otherwise rise, entering 
the chamber A as the first dampers 6,6 are opened and closed, and cause an 
explosion depending on the gas-air ratio. Furthermore, a tire supplying 
means which is relatively easy to seal from the outside air, such as a 
conveyor 17, is preferable. In addition, the second pair of dampers 7,7 
are provided to prevent direct communication between the furnace interior 
and the outside air. 
When a specific quantity of the tires has been supplied onto the first 
dampers 6,6, the operation of the conveyor 17 is automatically stopped by 
control means (not shown), and the leakage-sealing damper 5 is shut. 
Thereafter, the first dampers 6, 6 are opened, and all of the charged 
tires in the upper chamber A are dropped into the intermediate chamber B 
to rest on the second dampers 7, 7. The first dampers 6, 6 are then 
closed. Then, as the dry distillation reaction of the tires previously 
charged into the reaction chamber C progresses, and the volume of the 
charged tires in the reaction chamber C decreases, the second dampers 7, 7 
are opened, the entire quantity of tires in the intermediate chamber B is 
released for shifting into the reaction chamber C. 
In this case, however, since the state of filling and loading of the 
charged tires in the reaction chamber C is varying from second to second 
as the reaction proceeds, the tires in the intermediate chamber B may not 
entirely fall into the reaction chamber C, and a portion may remain in the 
chamber B in some instances. In such an event, the second dampers 7, 7 
will become clogged and will not fully close, and a dangerous situation 
will arise if the first dampers 6, 6 are opened with the second dampers 
still in this clogged state. Accordingly, a safety mechanism (not shown) 
is provided to cause the second dampers 7, 7 to undergo repeated opening 
and shutting action until they can be fully closed and to prevent the 
first dampers 6, 6 from opening if the second dampers 7, 7 are not fully 
closed. 
The tires which have been dropped and charged in this manner are stacked in 
a totally random manner within the reaction chamber C and form a 
self-sustaining "grate" of very high effectiveness because of the 
intrinsic shape of the tires. 
In the initial start-up of the process, the tires are thus stacked in 
random state in the reaction chamber C, and, as air is fed thereinto at a 
suitable rate through the annular tuyere 8, the burners 9 are ignited 
thereby to form a combustion zone in this region from which combustion 
gases are generated. 
When the combustion of the tires starts in this combustion zone, the 
burners 9 are extinguished, and only air necessary for the combustion is 
supplied to continue self-sustained combustion. As the oxygen in the gases 
generated by this combustion is consumed by combustion, the oxygen content 
progressively decreases below the explosion limit. As these gases rise in 
the furnace, they heat the charged tires and form a dry distillation zone. 
In general, a tire is composed of approximately 50 percent of a 
combustible volatile component, approximately 40 percent of a solid 
component comprising carbon powder, zinc white, and other solids as 
additives, and the remainder principally of steel wire. 
One of the objects of this invention is to utilize the heat of combustion 
of the non-volatile carbon as energy for recovering the above mentioned 
combustible volatile component. Accordingly, the reaction within the 
furnace is carried out in a mode for achievement of this object. More 
specifically, in the dry distillation zone, the volatile component is 
vaporized by the gases of combustion at a high temperature, and the tires 
successively migrate into the combustion zone by dropping naturally. The 
remaining carbon undergoes combustion in this combustion zone due to blown 
in air and is used as fuel for generating combustion gases. At the same 
time, combustible substances other than the volatile component are burned 
and generate energy necessary for dry distillation. As a net result, the 
reaction assumes a so-called self-energy-compensation form, which is 
another important feature of this invention. Thus, a combustion zone and a 
dry distillation zone coexist within the furnace and must be maintained 
under mutually set conditions. 
More specifically, the air for combustion is supplied through the tuyere 8 
at a rate such that oxygen is supplied at a rate sufficient for the 
combustion of the carbon in the charged tires but not sufficient to burn 
the volatile combustible substances. Accordingly, only this combustion 
zone assumes a high temperature, and therefore the provision of the 
cooling jacket 12 around the outer wall at this part is effective for 
protecting the furnace structure 3. Within the furnace, since the dry 
distillation zone is formed above the combustion zone, the charged tires 
are heated by the combustion gases rising from below, and the volatile 
combustible substances are vaporized and are conducted out of the furnace 
through the gas discharge outlet and pipe 13. 
The gases thus conducted out may be used as they are as combustion gases in 
a separate furnace. In addition, there are various other modes of 
utilizing these gases. For example, these gases are once cooled to remove 
heavy fractions as tar, and then, at room temperature, the light fractions 
and water content are separated into gaseous and liquid components which 
are used respectively as fuels. 
Furthermore, the combustion residue in the combustion zone comprises metal 
wire containing a small quantity of incombustible additives and is 
extracted as it is from the furnace bottom. An effective method of 
accomplishing this is, since a load due to the tire charged into the 
furnace is imparted to this residue, to discharge it through the furnace 
bottom, for example, and to forcibly remove this residue by means of the 
conveyor 14. 
Since the purpose of the reaction in the furnace is to accomplish dry 
distillation with insufficient oxygen, any leakage of outside air into the 
furnace is dangerous as a cause of an explosion. This danger is eliminated 
by making the furnace structure 3 gas-tight, providing the water-sealing 
device 4, and causing the pressure within the furnace to be positive. 
In order to obtain a normally and steadily progressing reaction in the 
furnace, to take the vaporizable combustible component in a vaporized 
state out of the furnace while preventing as much as possible its 
combustion within the furnace, and, at the same time, to cause the carbon 
component to undergo combustion within the furnace as much as possible, it 
is necessary to carry out in a smooth and steady manner the charging of 
the tires and the taking out of the residue remaining after the dry 
distillation and combustion. For this purpose, one method is to provide a 
control system which, for example, detects the temperature within the 
furnace and, in response to the detection signal, causes the discharging 
conveyor 14 and the charging conveyor 17 to respectively start and stop. 
More specifically, if the air supply into the furnace is continued with the 
charged tires in a stagnant state without steady downward movement, the 
combustion zone will progressively expand upward, and even the component 
to be vaporized will undergo combustion. Accordingly, there is provided a 
control system which detects the temperature at the upper part of the 
combustion zone and operates in response to the detection signal to drive 
the discharge conveyor 14 to take out the combustion residue and 
thereafter to cause newly supplied tires to be charged into the furnace. 
Thus, by the process of this invention as described above: tires are 
efficiently processed at a high rate; gaseous and liquid fuels are 
continuously produced; and, moreover, and steel wire in the tires are 
recovered as steel scrap. 
In order to indicate more fully the nature and utility of this invention, 
the following specific examples of practice are set forth, it being 
understood that these examples are presented as illustrative only and that 
they are not intended to limit the scope of the invention. 
EXAMPLE 1 
A vertical furnace having a cylindrical furnace structure (3) of a total 
height of 10 meters (m), a diameter at the upper end of 1.3 m, and a 
diameter at the lower end of 1.8 m was used. This furnace structure had 
first dampers (6,6) at a position 2.5 m below the top, second dampers 
(7,7) 1.5 m below the first dampers, a tuyere (8) for blowing in air and 
ignition burners (9) 1.3 m above the furnace bottom end, and a gas 
discharge outlet (13) 1 m below the second dampers. 
The lower 0.3 m of this furnace structure was immersed in water (4) in a 
water tank provided at its bottom with a discharge conveyor (14) for 
carrying out residue. A tire feeding conveyor (17) was provided at the 
upper part of the furnace. 
First, tires and cut-up tires were fed by the feeding conveyor (17) into 
the upper part of the furnace. By opening and closing the first and second 
dampers (6,6) and (7,7), the tires were charged into the furnace in 
divided lots of approximately 10 tires. When the reaction chamber (C) 
below the second dampers was substantially full, the charging was stopped. 
Air was then fed through the tuyere (8) into the reaction chamber, and, at 
the same time, the burners (9) were operated thereby to form a combustion 
zone. When this combustion chamber had been heated to a specific 
temperature, the burners were extinguished, and the combustion was 
thereafter continued by feeding only air. 
As the combustion gases thus generated flowed upward through the layers of 
randomly charged tires, dry distillation took place, and volatile 
combustible substances vaporized and, together with the combustion gases, 
were discharged out of the furnace through the outlet and pipe (13) and 
into a cyclone separator (21) of the separator (2). 
In the operation of feeding and charging the tires, the discharge conveyor 
14 was operated intermittently every 90 seconds, and the residue was thus 
removed in accordance with the quantity of tires charged into the 
intermediate chamber (B) between the first and second dampers. 
Accordingly, when a space was formed at the upper part of the reaction 
chamber (C), the second dampers were opened to cause the tires in the 
intermediate chamber (B) to drop and thereby to fill the reaction chamber. 
Then the second dampers were closed, and the leakage-sealing damper (5) 
was thereafter opened to cause the tires, in a quantity corresponding to 
the residue removed, to drop into the upper chamber (A). The 
leakage-sealing damper was then closed. Thereafter, the first dampers were 
opened to cause the tires in the upper chamber to drop into the 
intermediate chamber (B), and then the first damper is closed. 
The apparatus of this invention was operated continuously for 250 hours, 
whereupon it was found that, in terms of percent by weight of the charged 
tires, the quantity of the vaporized and recovered fuel was approximately 
40 percent, that of the collected free solid matter was approximately 40 
percent, and that of the combustion residue such as wire was approximately 
10 percent. Furthermore, the unburned matter at the furnace bottom at the 
time of start of the operation was again charged into the top of the 
furnace and therefore did not require any special processing. 
EXAMPLE 2 
As described above, the vaporized volatile combustible substances produced 
by the dry distillation in the distillation furnace (1), together with the 
combustion gases, were discharged out of the furnace through the outlet 
and pipe (13) and supplied into the cyclone separator (21) of the 
separator (2), which had a construction substantially the same as that of 
the separator illustrated in FIGS. 1, 2, and 3. 
In this separator, the cyclone separator operated to separate carbon 
particles from the gases thus supplied, and the gases thus separated and 
free of carbon particles were passed through the heat exchanger (24), 
where oils were separated from the gases. 
During these separation operations in the separator, the gas discharge pipe 
(13) for supplying gases into the separator, the interior parts of the 
cyclone separator, and the gas discharge passage (23) for supplying gases 
into the heat exchanger were cleansed of carbon particles adhering to 
their respective inner wall surfaces by the carbon removers (26), (28), 
(29), and (32), respectively. The actuating cylinders (25), (27), and (31) 
for actuating these carbon removers were operated intermittently, that is, 
at intervals of 5 minutes, by respective timers. 
It was found that even after 600 hours of continuous operation, there were 
no indications of malfunctioning or defects in either the dry distillation 
furnace or the separator, and it was obvious that the operation could have 
been continued much longer. This performance, which is due in part to the 
efficient removal of carbon by the separator, far exceeds that obtainable 
heretofore in the prior art, in which the limit of continuous operation 
has ordinarily been of the order of 72 hours. 
An indirect benefit of this invention is that it affords saving of energy 
and does not polute the environment. That is, as mentioned hereinbefore, 
tires have a calorific value of 8,000 Kcal/kg, which has heretofore not 
been utilized in a continuous manner on a quantity-production scale. This 
invention affords utilization of this energy latent in discarded tires by 
a continuous process on a large-quantity scale.