Overview of Pyrolysis, Thermal Gasification, and Liquefaction

36

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Overview of Pyrolysis, Thermal Gasification, and Liquefaction Processes in Japan M. HIRAOKA Department of Sanitary Engineering, Kyoto University, Kyoto, Japan

The system of treatment and disposal of municipal refuse in Japan since 1963, is made up of collection and transportation followed by the incineration and disposal of the residues or direct landfilling. A large number of incineration facilities have been constructed in many cities, with grant-in-aid from the government. Indeed, the incineration process is excellent in the respect that perishable organic refuse can be converted to stable inert mater i a l , reduced in volume and disposed under good sanitary conditions, and for recovering energy from refuse. But it is inevitably apt to cause some pollution problems such as air and water pollution and leaching of heavy metals from ash. The facilities for air pollution control, water treatment, stabilization of ash in the incineration process and residues disposal, have become more costly as new standards are promulgated. On the basis of these circumstances, the need for a better solid waste disposal system has stimulated a great deal of interest in the application of pyrolysis to solid wastes instead of the traditional incineration system in our country. Since the Agency of Industrial Science & Technology, MITI had launched the national project on development of technology and system of resource recovery from refuse in 1973, more than a dozen processes of PTGL* are being developed at the national level, municipal level, and the level of private companies as shown in Table I. On the other hand, the spread of the activated sludge method to treat sewage has created problems of sludge disposal. The incineration process has been increasingly adopted as the method for reducing the volume and residues. But it has been recently pointed out that incineration of sewage sludge causes air and water pollution and leaching of heavy metals (especially Cr+6 compounds) from ash, the same as in incineration of domestic refuse. To cope with this situation, the drying-pyrolysis process has been developed as *PTGL = pyrolysis, thermal gasification and liquefaction 0-8412-0565-5/80/47-130-493$05.00/0 © 1980 American Chemical Society In Thermal Conversion of Solid Wastes and Biomass; Jones, Jerry L., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1980.

494

THERMAL CONVERSION OF

SOLID WASTES AND

BIOMASS

Table I. Pyrolysis Process Developing in Japan Process Name

Company or Organization

Type of Reactor

Phase of R&D

1

Dual chamber fluidized bed system

AIST (MITI) & Ebara MFG. Co. Ltd.

Dual chamber fluidized bed

5 t/d p i l o t plant test, 100 t/d DP i s under construction

Pyrolysis/ Gas

2

A fluidized bed system

AIST & Hitachi Ltd.

Single fluidized bed

5 t/d p i l o t plant test

Pyrolysis/ Gas

3

Pyroxsys tem

Tsukishima Kikai Co. Ltd.

Dual chamber fluidized bed

150 t/d p r a c t i c a l plant i s being planned

Pyrolysis/ Gas, O i l

4

Incineration system

IHI Co. Ltd.

Single fluidized bed

5

Waste melting system

Nippon Steel Co. Ltd.

Moving bed shaft k i l n

6

Magma bed process

Shinmeiwa Industry Co.

Bench-scale Fixed bed el e c t r i c furnace test

7

Shaft Kiln pyrolysis system

Hitachi Ship-building Co. Ltd.


20 t/d p i l o t plant test

Pyrolysis/ Gas

8

Destragas process

Hitachi Plant Const. Ltd.


Pilot plant test

Pyrolysis/ Gas

9

Purox system

Showa Denko Co. Ltd.


75 t/d p r a c t i c a l plant i s being planned

Pyrolysis/ Gas

10

Torrax system

Takuma Co. Ltd.


11

Landgard process

Kawasaki Heavy Industries Ltd.

Rotary k i l n

30 t/d p i l o t plant

Pyrolysis/ Gas/Steam

12

M. Gallet system

Mitsubishi Heavy Industries Ltd.

Flash type reactor

Bench-scale test

Pyrolysis/

13

Pyrolysis of scrap tires

Kobe Steel Ltd.

External heated 23 t/d p r a c t i c a l plant i s under rotary k i l n construction

Pyrolysis/ Gas/Oil

14

Pyrolysis of sewage sludge

NGK. Insulators Ltd.

Multiple hearth 40 t/d p r a c t i c a l plant i s furnace installed

Pyrolysis


No.

Process

Incineration/Steam

Pilot plant 30 t/d 150 t/d p r a c t i c a l plant i s under construction

Pyrolysis/ Gas

Pyrolysis/ Gas

Pyrolysis/ Gas

In Thermal Conversion of Solid Wastes and Biomass; Jones, Jerry L., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1980.

Oil

and Combustion

36.

HiRAOKA

PTGL

495

Processes in Japan

the most f e a s i b l e method of sludge treatment and d i s p o s a l which minimizes the secondary p o l l u t i o n problems as discussed by Hiraoka et a l . (1). The aim of t h i s paper i s to describe the present status of development and a p p l i c a t i o n , and e v a l u a t i o n of PTGL processes i n our country.


C h a r a c t e r i s t i c s of M u n i c i p a l Refuse (MR) i n Japan

and Sewage Sludge

(SSL)

The general c h a r a c t e r i s t i c s of MR and SSL i n Japan are shown i n Table I I and Table I I I . The Japanese MR has, on the average, a heating value of 1,300 Kcal/Kg, g e n e r a l l y ranging from 800 to 1,800 Kcal/Kg, and has a water content ranging 40-607 . Although, the c a l o r i f i c value of MR tends to i n c r e a s e , t h i s r e l a t i v e l y lower heating value and high moisture content compared with that of the United States must be considered i n the design of resource recovery systems from MR i n Japan. o

Heat Recovery System from MR. Since the Japanese government adopted i n c i n e r a t i o n and l a n d f i l l systems f o r treatment of MR i n 1963, the technology of European i n c i n e r a t i o n has been used mainly f o r c o n s t r u c t i n g the l a r g e s c a l e i n c i n e r a t o r ; except f o r a few i n c i n e r a t o r s , the Japanese i n c i n e r a t i o n system does not have the heat recovery subsystem as i n Europe. Since the Arab O i l Embargo i n 1973, the need f o r heat recovery from i n c i n e r a t o r s i n l a r g e c i t i e s i s i n c r e a s i n g l y emphasized. As the main c i t i e s i n Japan are l o c a t e d i n the temperate climate r e g i o n , d i s t r i c t heating i s not p r a c t i c a l except i n Hokkaido. E l e c t r i c a l power generation i s , i n p r i n c i p l e , q u i t e reasonable f o r recovering the energy from MR i n Japan. The Nishiyodo i n c i n e r a t i o n p l a n t of Osaka C i t y has a processing c a p a c i t y of 400 tons of MR per day, and i s equipped with two 2,700 KW generators, with output voltage of 6,600 V. In Tokyo, Katsushika i n c i n e r a t i o n plant which i s i n operation generates e l e c t r i c i t y of 12,000 KW, with a refuse feed of 1,200 tons per day. A p p l i c a t i o n of PTGL Processes as an A l t e r n a t i v e to Incinerat i o n f o r Treatment of MR. As stated above, as a f i r s t stage, various PTGL process systems o f f e r the p o s s i b i l i t y of decreasing several p o l l u t i o n problems caused i n the i n c i n e r a t i o n process. The p y r o l y s i s and melting process developed by Nippon Steel Co., L t d . was adopted at Ibaraki C i t y to t r e a t 450 tons/day (150 tons/ day X 3) of MR, and i s under c o n s t r u c t i o n . Funabashi C i t y has decided to use the dual f l u i d i z e d bed r e a c t o r system (Pyrox process) to t r e a t 450 tons/day (150 tons/day X 3) of MR, and Chichibu C i t y has decided to use the Purox process developed by Showa Denko Co., L t d . and Union Carbide Co., L t d . . The design and construct i o n of these p l a n t s were s t a r t e d t h i s A p r i l .


496

THERMAL CONVERSION OF SOLID WASTES AND BIOMASS

Table TI (a). General C h a r a c t e r i s t i c s of MR

1. P h y s i c a l

Properties


Garbage Combus t i b l e s Uncombustibles Moisture

15-30% 20-50% 10-20% 40-60%

2. Chemical P r o p e r t i e s C H 0 Ν Cl S

(WB)

10-25% 1.5-3.0% 10-20% 0.5-1.0% 0.2-1.0% 0.2-0.3%

3. C a l o r i f i c Value

800-1,800 Kcal/Kg

Table IL ( b ) . General C h a r a c t e r i s t i c s of Sewage Sludge

1. P h y s i c a l

Properties

Comb us t i b l e s Uncombustibles Moisture

15-50% 10-20% 60-85%

2. Chemical P r o p e r t i e s

(DB)

C

15-25%

H 0 Ν S

1- 5% 15-20% 2- 7% 0.2-1%

3. C a l o r i f i c Value

0-300 Kcal-Kg


In Thermal Conversion of Solid Wastes and Biomass; Jones, Jerry L., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1980. 3.0 4.8 100.0 95.5 30.0

17.3

47.0 55.2 0.0 0.0 19.7

38.6

50.0 40.0 0.0 4.5 50.3

44.0

5.0 2.5 2.3 5.5 8.0

4. Wood

5. Cloth

6. Ferrous metals

7. Glass, b r i c k & pebbles 8. Miseelleneous & uncategorized

Total

11.1

63.3

25.6

10.8

3. P l a s t i c s

8.6

53.4

38.0

40.6

2. Paper

9.6

19.1

71.3

25.3

Un comb us t ib l e (%)

Comb us t i b l e (%)

Moisture (%)

1. Garbage

Wet b a s i s content (%)

Table ΊΠ. An Example of Composition o f MR



498


Resource Recovery Process System Developed by National Project. Phase I of the n a t i o n a l p r o j e c t was c a r r i e d out from 1973 to 1976 f o r developing the f e a s i b l e technology and systems of resource recovery from s o l i d wastes, and the demonstration plant (100 tons/day) f o r the m a t e r i a l - reclamation system i n phase II i s under c o n s t r u c t i o n . The p y r o l y s i s processes which have been developed i n phase I of the n a t i o n a l p r o j e c t are as f o l l o w s : a) Dual F l u i d i z e d Bed Reactor System f o r Fuel Gas Recovery (Ebara Corporation) b) F l u i d i z e d - B e d P y r o l y s i s f o r O i l Recovery ( H i t a c h i Ltd.) These reclamation systems may be s u i t a b l e f o r the c h a r a c t e r i s t i c Japanese MR. As the MR i n Japan has a r e l a t i v e l y high moisture content, d i r e c t a i r c l a s s i f i c a t i o n of the crushed refuse as seen i n the United States i s hard to apply. A d r y i n g process may be necessary p r i o r to the a i r c l a s s i f i c a t i o n . In t h i s respect, a s e l e c t i v e p u l v e r i z i n g c l a s s i f i e r has been developed i n the nationa l p r o j e c t which i s q u i t e s u i t a b l e to separate garbage of high moisture content and paper i n Japanese MR. This demonstration plant with a c a p a c i t y of 100 tons/day w i l l be i n f u l l operation on November of 1979. A p p l i c a t i o n of PTGL Processes to I n d u s t r i a l Wastes. Indust r i a l wastes which have a high c a l o r i f i c value such as scrap t i r e s and p l a s t i c s are s u i t a b l e f o r PTGL processes. Though the many processes as shown i n Table I can be a p p l i e d to t r e a t i n d u s t r i a l wastes, a PTGL process using a external-heated r o t a r y k i l n has been developed by Kobe S t e e l Co., L t d . to decompose the scrap t i r e s and to get a l i q u e f i e d f u e l . The Clean Japan Center which was e s t a b l i s h e d to promote the resource recovery e f f o r t sponsored by MITI and the r e l a t e d p r i v a t e companies, are planning to cons t r u c t the commercial p l a n t which w i l l t r e a t the scrap t i r e s by use of t h i s technology and use the l i q u e f i e d o i l as the f u e l f o r a cement k i l n . E v a l u a t i o n of PTGL Processes Various PTGL processes have been developed and are i n demons t r a t i o n and commercial stages. From a comparison of municipal refuse handling options, we w i l l determine i f p y r o l y s i s can be competitive with conventional handling options and how recovered m a t e r i a l and energy values a f f e c t the operation c o s t s . Three municipal refuse handling options were c o n c e p t i o n a l l y designed and compared i n t h i s study. These are: Option 1, I n c i n e r a t i o n System, Option 2, P y r o l y s i s - M e l t i n g System, and Option 3, M a t e r i a l Recovery and P y r o l y s i s System. Option 1 i s a conventional stoker i n c i n e r a t i o n system with heat recovery. E l e c t r i c power w i l l be generated with the steam from the waste heat b o i l e r . To meet the a i r p o l l u t i o n standards, exhaust gas has to be cleaned by an e l e c t r o s t a t i c p r e c i p i t a t o r and



36.

HiRAOKA

PTGL

Processes in Japan

499

a scrubber. Caustic soda s o l u t i o n w i l l be a p p l i e d i n the scrubber to absorb hydrogen c h l o r i d e and s u l f u r oxides. Residual ash w i l l be disposed of by l a n d f i l l i n g . In option 2, municipal refuse w i l l be size-reduced by a crusher and fed i n t o the converter. Oxygen w i l l be supplied to the converter and municipal refuse w i l l be d r i e d , pyrolyzed and melted at high temperature. P y r o l y s i s gas w i l l be d i r e c t l y combusted i n the combustor, where waste water w i l l be evaporated and o x i d i z e d . Energy w i l l be recovered i n the form of steam by a waste heat b o i l e r and e l e c t r i c power w i l l be generated. Lime w i l l be applied to absorb hydrogen c h l o r i d e and s u l f u r oxides i n the f l u e gas. Slag may be used f o r the c o n s t r u c t i o n of roads, e t c . . Option 3 includes both m a t e r i a l and heat recovery. A semiwet p u l v e r i z i n g c l a s s i f i e r developed by the Agency of I n d u s t r i a l Science and Technology, MITI i s a p p l i e d to recover garbage which has low c a l o r i f i c value and high moisture content. The h i g h l y c a l o r i f i c part of municipal refuse which mainly contains paper and p l a s t i c s w i l l be supplied to p y r o l y s i s r e a c t o r . The p y r o l y s i s reactor c o n s i s t s of two f l u i d i z e d beds; cracking r e a c t o r and regener a t o r . P y r o l y s i s gas w i l l be cleaned through the scrubber and stored i n the storage tank. The cleaned gas w i l l be combusted to produce high pressure steam with which e l e c t r i c power w i l l be generated e f f i c i e n t l y . Compost w i l l be obtained from garbage through a process c o n t a i n i n g fermentator, dryer and separators. E l e c t r i c i t y , f e r r o u s metal, and compost w i l l be recovered i n t h i s system. Basis f o r Plant Design. The composition of municipal refuse i s assumed as shown i n Table I I I . The municipal refuse has the lower c a l o r i f i c value of ca. 1,500 Kcal/Kg. Plant s i z e of 600 T/D i s assumed. The c a p i t a l investment c o s t s , u t i l i t i e s , e t c . were c a l c u l a t e d using contacts with equipment vendors. Cost f o r rep a i r s are assumed to be two percent of the plant c o n s t r u c t i o n cost per year. Unit costs of u t i l i t i e s and u n i t p r i c e s of recovered energy and m a t e r i a l are assumed, based on the a c t u a l p r i c e s i n 1979. Ash and other residues d i s p o s a l cost i s assumed to be 2,450 Yen/T, taking note of the r e p r e s e n t a t i v e cost data of l a r g e c i t i e s i n Japan. The grant a v a i l a b l e to a m u n i c i p a l i t y i s assumed to pay up to f i f t y percent of the c a p i t a l investment. The remaining i n vestment cost must be amortized i n f i f t e e n years with the i n t e r e s t rate of s i x percent. I n c i n e r a t i o n System (Option 1). The system flow diagram i s shown i n Figure 1. About 70.5 percent of the heat of the municipal refuse i s recovered i n the form of steam (265°C). A p o r t i o n of the steam i s used i n the a u x i l i a r y equipment i n the i n c i n e r a t i o n system such as the a i r heater. The e f f i c i e n c y of the low pressure turbine generator i s about 0.21. U t i l i t i e s f o r the o p e r a t i o n of the system and operating costs are l i s t e d i n Table IV. The caustic soda s o l u t i o n costs to meet the a i r p o l l u t i o n standards are high.


500

THERMAL CONVERSION OF SOLID WASTES AND

Turbine

BIOMASS

Generator

£5 Downloaded by UNIV OF CALIFORNIA SAN DIEGO on February 21, 2016 | http://pubs.acs.org Publication Date: August 29, 1980 | doi: 10.1021/bk-1980-0130.ch036

600

T/D

^170 Waste Water Treatment

T/D^

Effluent

EP: E l e c t r o s t a t i c Precipitator Electricity

C i t y Water

Figure 1.

Industrial Water

Flow diagram of incineration option

Table Έ . U t i l i t i e s and O p e r a t i n g Cost ( I n c i n e r a t i o n )

City Water Industrial Water NaOH (48 wt%)

6

T/D

X10 Yen/year

91

5.9

337

6.1

7.3

65.8

other Consumption Material

151.7

Repairs

183.3

Ash Disposal

149

Total

Revenue(Electric Power)

131.4

544.2

72 MWH/D

129.6


36.

HiRAOKA

PTGL

Processes in Japan

501


As t h i s o p t i o n i n c l u d e s no m a t e r i a l recovery process, the r e s i d u a l ash which amounts to about 25 percent of the raw municipal refuse i n weight has to be disposed of. The generated e l e c t r i c i t y amounts to 117 MWH/D, and the plant operation needs 45 MWH/D of e l e c t r i c i t y . The outcome of t h i s i s that 72 MWH/D of e l e c t r i c i t y can be d e l i vered. P y r o l y s i s - M e l t i n g System (Option 2). The system flow diagram i s shown i n Figure 2. The heat recovery e f f i c i e n c i e s of the conv e r t e r and combustor are 0.81 and 0.71, r e s p e c t i v e l y . About 60 percent of fed heat i s recovered i n the form of steam. The e f f i ciency of the low pressure turbine generator i s about 0.21 as i n option 1. The 104 tons per day of s l a g are assumed to be taken by the c o n s t r u c t i o n f i r m s . U t i l i t i e s f o r the operation of the system and operating costs are l i s t e d i n Table V. A u x i l i a r y f u e l cost takes the greater part of the t o t a l operating c o s t . As the oxygen generator needs much e l e c t r i c i t y (about 41 percent of the t o t a l usage of e l e c t r i c i t y ) , d e l i v e r a b l e e l e c t r i c i t y i s only 17 MWH per day. The recovered energy i s used f o r the improvement of the char a c t e r i s t i c s of the residues i n t h i s system. Thus, ash d i s p o s a l cost i s small; on the other hand, revenue from the s a l e of e l e c t r i c i t y i s small. M a t e r i a l Recovery and P y r o l y s i s System (Option 3). The system flow diagram i s shown i n Figure 3. A semi-wet p u l v e r i z i n g c l a s s i f i e r and a magnetic separator recover garbage and f e r r o u s metal. M a t e r i a l fed to the p y r o l y s i s r e a c t o r w i l l have a c a l o r i f i c value of about 2,200 Kcal/Kg. About 54 percent of the heat of the feed m a t e r i a l i s recovered i n the form of gaseous f u e l . The conv e r s i o n of the f u e l gas to steam (390°C) i s about 65.6 percent. About 29 percent of steam i s used f o r d r y i n g the fermentated garbage. The e f f i c i e n c y of the intermediate high pressure turbine generator i s about 0.46. The cleaned gas f u e l through the scrubber make i t p o s s i b l e to r a i s e the steam temperature to 390°C. The strength of the waste water q u a l i t y i s o f f e r e d up i n the i n t e r e s t of the high e f f i c i e n c y of the turbine generator i n t h i s system. The u t i l i t i e s f o r the operation of the system and the operating costs are l i s t e d i n Table VI. The consumptive m a t e r i a l s take the greater part i n the t o t a l operating c o s t , r e f l e c t i n g much r e q u i r e ment f o r the maintenance of the complex system. The recovery i n t h i s system includes e l e c t r i c i t y , f e r r o u s metal and compost. The t o t a l revenue i s the maximum of the three systems. Comparison. The t o t a l operating costs are compared i n Figure 4 f o r the aforementioned three options. Revenues from recovered m a t e r i a l s and energy are a l s o shown i n the f i g u r e . Gross operating cost i s lowest f o r P y r o l y s i s - M e l t i n g Process (Option 2). Gross operating cost minus revenue, or net d i s p o s a l cost i s lowest f o r I n c i n e r a t i o n Process (Option 1). However, d i f f e r e n c e s i n the net d i s p o s a l costs are small f o r these three



502

THERMAL CONVERSION OE SOLID WASTES AND BIOMASS

EP: E l e c t r o s t a t i c P r e c i p i t a t o r

Electricity

Figure 2.

C i t y Water

Industrial Water

Flow diagram of pyrolysis-melting option

Table V. U t i l i t i e s and Operating Cost

T/D

(Pyrolysis-Melting)

X10° Yen/Year

C i t y Water

120

7.8

I n d u s t r i a l Water

972

17.5

Oil Lime

19.7

212.8

3.3

16.6

Other Consumptive M a t e r i a l

17.3

Repairs

176.2

Ash D i s p o s a l

11

Total

Revenue(Electric

9.7 457.9

Power)

17MW

30.6



£S

0T/D|

MWHAD}

( ^ * 9 1

City

T/D

Water

Figure 3.

>

o

separator

Industrial Water

Landfill

)

23.9 T / D j

55.9 T/D

Electrostatic Separator

to

Grade

Compost

Lower Grade Compost

Higher

Flow diagram of material recovery and pyrolysis option

SPC: Semi-wet P u l v e r i z i n g C l a s s i f i e r MS : M a g n e t i c S e p a r a t o r EP : E l e c t r o s t a t i c P r e c i p i t a t o r

**69

Electricity


^^T^^/D^


504


Table M . U t i l i t i e s and Operating Cost ( M a t e r i a l Recovery + Pyrolysis)

T/D C i t y Water

171

11.1

I n d u s t r i a l Water

268

4.8

Other Consumptive M a t e r i a l

301.0

Repairs

216.4

Residue

Disposal

107

Total

94.3 627.6

Revenue E l e c t r i c Power

68 MWH/D

122.4

Ferrous Metals

13.8 T/D

23.0

Higher Grade Compost

55.9

30.2

Lower Grade Compost

23.9

4.3

Total

179.9


36.

PTGL

HiRAOKA

505

Processes in Japan


6735 Yen/T Yen/T

Residues Disposal

(%)

4903 Yen/T

Labor 542 (10.3) Repairs 849 (16.2)

(6.5)

Labor 1250 (18.6)

5246 Yen/T Ash D i s p o s a l 608 (11.6)

%37

Ash D i s p o s a l 45 (0.9)

Labor 750 (15.3)

Repairs 1002 (14.9)

Repairs 816 (16.6) Utility 1467 (21.8)

Utility 1063 (20.3)

Amortization 2184 (41.6)

Electricity 600

Incineration

Figure 4.

Utility 1259 (25.7)

Amortization 2579 (38.3) Amortization 2078 (424)

'Electricity 142

Pyrolysis-Melting

Electricity 567

F e r r o u s M e t a l 106 ^Compost 160

MR + P y r o l y s i s

Total operating costs for MR handling options



Nm /D)

72 — —

170 149

3.39 364 155 88

a) Almost a l l water i s used f o r cooling

E l e c t r i c i t y (MWH/D) Ferrous Metals (T/D) Compost (T/D)

Recovery

Waste Wat e r (T/D) Residue (T/D)

X

Flue Gas Volume (X10 NO as NO (Kg/D) S 0 as SO (Kg/D) HCÏ (Kg/Dj

Effluence

Incineration

17 — —

N

3.30 308 131 75 _ a) nearly zero ' 11

Pyrolysis-Me1ting

Table VLT. Comparison of E f f l u e n c e and Recovery

68 14 56 (Higher grade) 24 (Lower grade)

154 107

0.91 103 20 11

M a t e r i a l Recovery + P y r o l y s i s



36.

HiRAOKA

PTGL Processes in Japan

507

options. For Pyrolysis-Melting System and Material Recovery and Pyrolysis (Options 2 and 3), the shares of the labor cost and utility cost are higher than Incineration System (Option 1). The high percentages of labor cost in option 2 and 3 are due to the increase of the number of unit operations. Those of utility costs for option 2 and 3 are due to the expenditure for auxiliary fuel and deodorizing chemicals, respectively. The inflation of the selling prices of electricity and other recovered materials makes option 3 to be competitive to other options. The shortage of landfilling site makes option 2 relative to others. A comparison of effluents and recovery from the systems is shown in Table VII. The table shows Pyrolysis-Melting System, and Material Recovery and Pyrolysis System (Option 2 and 3) are favorable in the respect of the air and water pollution protection. Acknowledgment The authors wish to acknowledge Dr. N. Takeda for his assistance of a portion of the work presented in this article. References 1. Majima, T.; Kasakura, T.; Naruse, M.; Hiraoka, M. Prog. Wat. Tech., 1977, 9, 381. 2. Hiraoka, M.; Kawamura, M. The Third Japan - U.S. Conference on Solid Waste Management - Special Subject 2, 1976, May, 12, at Tokyo, Japan. 3. Hiraoka, M.; Takeda, N.; Fujita, K. 2nd Recycling World Congress , 1979, March 19-22, at Manila, Philippines. 4. Hiraoka, M. The International Congress of Scientist on The Human Environment, 1975, November 17-26, at Kyoto, Japan. RECEIVED November 16, 1979.


Overview of Pyrolysis, Thermal Gasification, and Liquefaction

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