40 Pyrolysis Process for Scrap Tires SHIGEO KAWAKAMI, KIMIO INOUE, HIDEKI TANAKA, and TAMIHARU SAKAI
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Kobe Steel, Ltd., Mechanical Engineering Research Laboratory, 1-Chome, Fukiai-Ku, Kobe, Japan
The number of scrap tires in Japan in 1977 was estimated to be approximately 47 million with a total weight of 550 thousand tons. Although some of them are reused as reclaimed rubber, re capped tires, etc., it is difficult to recycle a l l of the scrap tires by the usual methods, therefore, there is a demand for new recycling systems for scrap tires. Kobe Steel, Ltd. formerly developed a new process for produc ing powdered rubber and constructed an actual plant with a capa city of 7,000 ton per year in Osaka in 1976 (l,2). The powdered rubber is used as shock absorbing material for railway beds or as a f i l l e r for rubber products. Several pyrolysis processes using reactors such as a fluidiz ed bed (3), a shaft furnace, an extruder and a rotary kiln have also been studied in Japan. Pyrolysis using a rotary kiln has been studied since 1973 (4). A pilot plant test was finished in 1976, and an actual plant with a capacity of 7,000 ton per year has been constructed at Sumitomo Cement Co., Ltd. in ΑΚO City, Hyogo Prefecture, in 1979 (1). The plant will recover fuel o i l and carbon black from the scrap tires. I.
Process Flow.
An outline of the process flow from crushing and pyrolysis of the scrap tires to refining of char into carbon black is shown in Fig. 1. The figures in the parentheses in Fig. 1 show the material balance obtained from the pilot plant tests. The ratio of the re covered products changes according to the pyrolysis temperature as shown in Fig. 2. The main products are char and oil, which amount to approximately one third and one half of the total products re covered, respectively. Though the rate of pyrolysis increases at higher temperatures, the pyrolysis temperature has to be kept under 600°C in order to get the char from which high quality car bon black can be produced. 0-8412-0565-5/80/47-130-557$05.00/0 © 1980 American Chemical Society
In Thermal Conversion of Solid Wastes and Biomass; Jones, J., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1980.
In Thermal Conversion of Solid Wastes and Biomass; Jones, J., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1980.
1
1
2
4
1
W
Na S0 ί ! Solution ' J L
a
s
t
e
,
Stack
Desulfurizing
ψ_ _
NaOH
(1000 Kg)
Scrap Tires
G a s i
„
.
± Steel Figure 1.
(50 Kg)
Shredding
^
Pulverizingh^Pelletizing
(20 Kg)
(400 Kg)
(5 Kg)
L
Heavy Oil
j Carbon < Sludge_|
Quenching
Flow sheet of the pyrolysis plant
Carbon
Reheating
Magnetic Separation
Char
Pyrolysis
( 60 Kg )
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(340 Kg)
Carbon Black
(100 Kg)
> α
Η W
03
1
Ο C/3 Ο r
2!
δ
r ο ο
X w
Η
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KAWAKAMI ET AL.
559
Pyrolysis Process for Scrap Tires
60
0 I
1
500
1
•
600 TEMPERATURE
Figure 2.
t
TOO
t _
800
(°C)
Effect of the pyrolysis temperature on the ratio of recovered products (PP test)
In Thermal Conversion of Solid Wastes and Biomass; Jones, J., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1980.
560
THERMAL CONVERSION OF
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II.
SOLID WASTES AND
BIOMASS
Research and Development
To examine the p y r o l y s i s r e a c t i o n o f the scrap t i r e s , p u l v e r i z e d scrap t i r e s were heated i n a quartz tube by an e l e c t r i c furnace (h). Then the continuous p y r o l y s i s t e s t p l a n t s i n Table I were constructed t o get the engineering data r e q u i r e d f o r the design o f an a c t u a l p l a n t . The p i l o t p l a n t i s shown i n F i g . 3. The longest p e r i o d of continuous operation of the p i l o t p l a n t was 120 h r s . In the mini p l a n t t e s t s (MP Test) scrap t i r e s shredded i n t o pieces about 10 mm i n s i z e were used. In the p i l o t p l a n t t e s t s (PP Test) scrap t i r e s shredded i n t o p i e c e s about 50 mm i n s i z e as w e l l as the f i n e shredded t i r e s were used. Table I .
Test p l a n t s f o r the p y r o l y s i s process
Dimensions of the k i l n Heating
system
Feeding
system
Discharge
system
Capacity
(Kg/H)
(mm)
P y r o l y s i s Bench Test (MP t e s t )
P i l o t Plant Test (PP t e s t )
100^ χ 1,200*
k25
