JPH026106A - Treatment method of unburnt carbon of waste tire after thermal decomposition and its device - Google Patents

Abstract

PURPOSE:To realize a process which keeps well the property of a thermal decomposition furnace by suppressing the increase of the unburnt carbon-rate in the medium circulating in the furnace by a method in which after a waste tire has been thermally decomposed on the fluid bed composed of incombustible medium, said medium is air-classified, whereby the medium is separated from the unburnt carbon mixed with the medium. CONSTITUTION:A fluid bed 16 is composed of the medium 7 such as silica. The rubber part of the waste tyre 2 thrown into, is vaporized immediately, and carbon black is separated from steel cords by the flowing of the medium 7, and further it is finely powdered and is fed into the combustion chamber of a boiler, etc. from a discharging port 3, accompanying with vaporized gas. The card 17 and the medium 7 are discharged outside of the boiler with a transporter 12, and the cord 17 is separated from the medium 7 in a separating device 13, and then the medium 7 is returned to a thermal decomposition furnace. The air classification device 23 in which an air classifying machine is combined with a screen is provided in the intermediate position of the circulating path of the medium in the thermal decomposition furnace, and the medium 7 is separated from the unburnt carbon. Consequently, the unburnt carbon in the medium is removed effectively, whereby the property of the fluid bed and the sealing layer of the thermal decomposition furnace is prevented from being deteriorated due to aging.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a method and apparatus for treating unburned carbon after thermal decomposition of waste tires from automobiles and the like.

BACKGROUND OF THE INVENTION The inventor of this invention previously invented and disclosed a pyrolysis furnace for waste tires as shown in FIG.
No. 7199).

Since this invention also relates to the above-mentioned disclosed invention, this disclosed invention will be explained first.

In FIG. 5, 1 is a charging chamber for the tire 2, 3 is an outlet for pyrolysis gas, 4 is a recirculation port for media such as sand, and 5 is a feeder. 6 is a fluidized bed section containing a nonflammable medium 7 such as sand, 8 is an air inlet formed in communication with a blower 9, 10 is a seal layer forming section, and 11 is an opening.

A transfer device 12 is provided below the opening 11 to transfer the medium 7 in the direction of arrow A12. 13 is a separation device such as a steel cord, 15 is a medium 7
16 is a fluidized bed formed by the air introduced from the air inlet 8, 17 is a steel coat produced by thermal decomposition of tires 2, etc., 18 is a sealing layer, 19 is a wind box, and 20 is a A hopper, 21 a supply device, and 22 a damper. Note that a belt conveyor is used as the transfer device 12, for example. The tire 2 is fed into a fluidized bed 16 by the feeder 5.
It is fed to the top and ignited. Medium 7 is inlet 8
A fluidized bed 16 is formed by the air supplied from the tire 2, and the tire 2 is thermally decomposed in this fluidized bed 16.

The gas generated by the thermal decomposition is sent from the exhaust port 3 to a combustion device such as a boiler (not shown). On the other hand, the steel cord 17 generated by the thermal decomposition gradually descends together with the medium 7 in the seal layer forming part 1o as the transfer device 12 operates, exits from the opening 11, and is separated in the separation device 13. taken out. The medium 7 from which the steel cord 17 has been removed is circulated by a circulation device 15, passed through a hopper 20, and refluxed from the reflux port 4 onto the fluidized bed 16.

Problems to be Solved by the Invention When the tire 2 is thermally decomposed using the fluidized bed 16 as described above, the carbon black contained in the tire 2 is pulverized by the fluidized bed 16.

Then, the finely pulverized material is carried along with the cracked gas to a boiler or cement kiln (not shown) outside the furnace, where it is burned and used. However, carbon particles that do not become extremely fine remain in the flow 116,
A part of it moves to the sealing layer 18 filled with the medium 7 below the fluidized bed 16 together with the medium 7 and the steel cord 17, and is finally discharged out of the system from the bottom of the furnace. Then, the steel cord 17 is removed by the separator 13, and the unburnt carbon black is returned to the furnace together with the medium 7 via the circulation device 15 and circulated therein. As the above-mentioned situation is repeated, the proportion of unburned carbon in the medium 7 gradually increases over time. For this reason, the following problems occur.

(A) Carbon is softer than silica sand or the like used as the medium 7, so inside the fluidized bed 16, coarse carbon adhering to the steel cord 17 of tire residue can be peeled off, coarse carbon can be pulverized, etc. The ability to miniaturize is low. As a result, the tire processing capacity of the furnace is reduced, and coarse carbon is mixed into the medium 7 discharged from the bottom of the furnace.

(B) Since the surface level of the medium in the fluidized bed 16 rises in response to the increase in unburned carbon, a slight bumping phenomenon in the fluidized bed 16 causes the medium 7 to blow up to the gas outlet 3 at the top of the furnace. This causes the gas to rise and be transported out of the system along with the gas.

(C) Unburned carbon has a microscopic size of 20 to 50 μm
Since it is composed of agglomerated ultra-fine carbon particles, it is porous, and the sealing performance of the sealing layer 18 filled with the medium 7 at the bottom of the fluidized bed 16 deteriorates. A workpiece of the gas generated is generated.

This invention was made to solve these problems, and its purpose is to efficiently separate unburned carbon contained in the medium in a furnace that uses a fluidized bed to pyrolyze waste tires. The purpose is to avoid increasing the proportion of unburned carbon in the medium flowing into the furnace. Another object of the present invention is to provide a method and apparatus for maintaining good performance of this pyrolysis furnace.

Means for Solving the Problems Regarding the present invention which achieves the above objects, the method is first described. In this method, waste tires are thermally decomposed using a fluidized bed formed of a non-flammable medium, and then the medium is heated by wind power. This is a method for treating unburned carbon after pyrolysis of a waste tire, in which the unburnt carbon generated from the waste tire mixed in the medium is separated from the medium by classification.

Next, we will discuss the processing equipment. It consists of a fluidized bed section provided at the bottom of the waste tire charging chamber and containing a nonflammable medium; a pyrolysis gas exhaust port formed in the charging chamber; A reflux port for refluxing the medium: a seal layer forming part formed at the bottom of the fluidized bed; an opening formed at the bottom of the seal layer forming part; provided between the opening and the reflux port; This is an apparatus for processing unburned carbon after pyrolysis of waste tires, which comprises an air classifier for processing the medium.

Embodiment FIGS. 1 and 2 show an embodiment of the present invention, and since the waste tire pyrolysis furnace itself in the figures is the same as the disclosed invention, the names and drawing symbols of each part of the pyrolysis furnace are etc. are the same as those disclosed above. Therefore, some of the explanations of each part are omitted because they are redundant.

In the figure, a fluid 416 is formed by a medium 7 such as silica sand, and is constantly maintained at about 700°C, and the waste tire 2 that has been thrown in is immediately vaporized in the fluidized bed 16, and the rubber content is immediately volatilized, and the carbon black is removed from the medium. It is peeled off from the steel cord 17 by the flow of 7, is further made into fine particles, is entrained in the volatilized gas, and is transported from the gas outlet 3 to the combustion chamber of a cement firing kiln or boiler (not shown) through piping. Ru.

The sealing layer 18 seals the gas generated in the pyrolysis furnace so that it does not leak out of the furnace due to the filled medium 7, and also serves as a zone in which the steel cord 17 of the tire residue is transferred together with the medium 7. and steel code 17
and the medium 7 are discharged out of the furnace by a conveyor 12 such as a conveyor. Then, the steel cord 17 and the medium 7 are separated by the separating device 13. The medium 7 is lifted up by a circulation device 15 such as a packet elevator, stored in a hopper 20, quantitatively fed by a supply device 21 such as a screw conveyor, and introduced into the furnace through the reflux port 4 for circulation and reuse.

However, the carbon black in the tire 2 is not completely pulverized by the pulverizing action caused by the flow of the medium 7 in the fluidized bed 16, and the terminal velocity of unburned carbon particles is higher than the superficial velocity in the furnace. The materials remain in the fluidized bed, and some of them are transferred to the fluidized bed 16 by the sieve feeder 12 installed under the pyrolysis furnace.
It then moves to the sealing layer I8 together with the medium 7 and the steel coat 17 soaked in the tire. In the sealing layer 18, since there is almost no air flow, the medium 7 is in a stationary state, so that coarse unburned carbon is not crushed. Also, car phones have almost no self-combustion. That is, in the seal layer 18, the shape of unburned carbon is hardly reduced in diameter, and is discharged from the bottom of the furnace to the outside.

The medium 7 also follows the same process and is returned to the pyrolysis furnace. As described above, the circulation and reuse of this unburned carbon black causes various problems in the pyrolysis furnace.

In order to avoid this adverse effect, the inventor of the present invention focused on the fact that there is a considerable difference in the apparent specific gravity between the medium 7 such as silica sand and unburned carbon black, and as a result of research, the inventor of the present invention has developed a system as shown in FIG. As shown in FIG. 1 or 2, a wind classifier 23, which is a combination of a wind classifier and a sieve, is installed in the middle of the medium circulation path of the pyrolysis furnace to separate the medium 7 and the unused material. We have obtained knowledge that can efficiently classify combustion carbon. Now, to describe the wind classifier 23, in FIG. 3, 24 is a classification hopper, 25 is a valve, and 26 is a classification chamber. Further, 27 is a discharge passage formed in the falling passage 28;
9 is a lower sieve tank, 3o is an upper sieve tank, 31 is a feeding F@ machine, 32 is a damper, 33 is a sieve provided in the classification chamber 26, 34 is a lower sieve passage, and 35 is an upper sieve passage.

A carbon-containing medium 36 is dropped from the classification hopper 24 toward the classification chamber 26, and when air is blown from the blower 31, the carbon-containing medium 36 is passed through a sieve containing a small amount of unburned carbon in the classification chamber 26. It is divided into a lower recovery medium 37 and an upper sieve recovery medium 38 containing a large amount of unburned carbon, and these are placed in the lower sieve layer 29 and the upper sieve layer 3o, respectively.

A portion is also discharged from the discharge passage 27 as a scattering medium.

In this case, the content of unburned carbon in both of the recovery media 37, 438 varies depending on the speed of the blown air, as will be described later.

Next, Tables 1 and 2 show the particle size distribution of the carbon-containing medium 36 discharged from the bottom of the furnace in the conventional waste tire pyrolysis furnace shown in FIG. This is an example showing the ratio. This carbon-containing medium 3
6 to the wind classifier 23 which combines a wind classifier and a sieve as shown in FIG.
It is shown in Table-3. When this classified sample was analyzed,
As shown in Table 4, the distribution ratio of medium 7 and unburned carbon was clarified.

FIG. 4 is a graph of the distribution ratio data in Table 4.

Table-1 Particle size distribution table of test carbon-containing media for classification-4/! This is an example in which a distribution ratio of 23 between medium and unburnt carbon based on l-speed is incorporated into the process of a conventional waste tire pyrolysis furnace. After removing the steel cord 17 discharged from the pyrolysis furnace, the carbon-containing medium 36 is introduced into the wind classifier 23 to remove some percentage of the unburned carbon in the medium 36, and then returned to the furnace. Table 5 shows the experimental results for one month when the device was operated and when the conventional process was operated without using this wind classifier 23.

From FIG. 4, in the case of this test carbon-containing medium, the sieve opening of the classifier 23 was set to 2 mm, and the air velocity in the tower was set to 4 to 5'm.
It can be seen that if it is set to /sec, 20 to 40% of unburned carbon can be separated with almost no scattering of the medium. From the standpoint of effective heat utilization, it is also desirable to supply this separated carbon to a combustion chamber of a cement kiln, boiler, or the like (not shown) as a fuel.

Figures 1 and 2 show that the guideline for replenishing the medium shown in Table 5 of the wind classifier of the present invention is that the sealing performance of the sealing layer of the pyrolysis furnace deteriorates over time ( (This is because the proportion of unburned carbon increases over time, and this carbon is porous.) When a phenomenon occurs in which the furnace gas leaks from the opening 11 at the lower end of the sealing layer 18, the medium 7 is heated until the phenomenon disappears. I am trying to replenish it. By incorporating and using the wind classifier 23 of the present invention in the process of this pyrolysis furnace, the amount of replenishment of the medium is drastically reduced and the furnace can be operated stably, thereby increasing the throughput of tires. This is the result I got.

Effects of the Invention The present invention is constructed as described above, and is capable of efficiently removing unburned carbon in the medium by thermally decomposing waste tires using a fluidized bed formed of a non-flammable fluidized medium, and then classifying the medium with wind power. Since it can be removed well, it is possible to prevent performance deterioration over time in the fluidized bed and seal bed of this pyrolysis furnace. Therefore, the complexity of replenishing and replenishing the medium is also reduced, thereby reducing the costs involved. or,
Since the performance of the pyrolysis furnace can be maintained well at all times, the throughput of tires can be increased compared to the conventional method.

[Brief explanation of the drawing]

Fig. 1 shows an embodiment of the present invention, and is a diagram schematically showing a processing device for unburned carbon after pyrolysis of waste tires, and Fig. 2 shows another embodiment of the invention, and corresponds to Fig. 1. 3 is a detailed view of the portion shown in FIGS. 1 and 2, FIG. 4 is a graph showing the distribution ratio of the medium and unburned carbon when the apparatus shown in FIG. 3 is used, and FIG. The figure is a cross-sectional view of the waste tire pyrolysis furnace previously disclosed by the inventor of this invention, and Figure 6 is the V of Figure 5.
1-Vl line arrow view. ■... Input chamber 3... Discharge port 4... Reflux port 6... Fluidized bed section 7... Medium 11... Opening section 23... Wind classifier representative Patent attorney Saito Yu (
2 people outside)

Claims (1)

[Claims] 1. A waste tire is thermally decomposed using a fluidized bed formed of a non-flammable medium, and then the medium is subjected to air classification, and the waste tire produced from the waste tire mixed with the medium is A method for processing unburned carbon after pyrolysis of waste tires, characterized by separating unburned carbon. 2. A fluidized bed section containing a nonflammable medium provided at the lower part of the waste tire charging chamber; A pyrolysis gas exhaust port and a reflux port for refluxing the medium formed in the charging chamber; A sealing layer forming part formed at the bottom of the layer; an opening formed at the bottom of the sealing layer forming part; a wind classifier for processing the medium provided between the opening and the reflux port; An apparatus for processing unburned carbon after thermal decomposition of waste tires, characterized by: