Thermal Conversion of Solid Wastes and Biomass - American

42 Integrated System for Solid Waste Disposal with Energy Recovery and Volumetric Reduction by a New Pyrolysis Furnace TATSUHIRO FUJII

Downloaded by CORNELL UNIV on October 15, 2016 | http://pubs.acs.org Publication Date: August 29, 1980 | doi: 10.1021/bk-1980-0130.ch042

Technology & Development Headquarters, Hitachi Shipbuilding & Engineering Co., Ltd., 6-14, Edobori 1-chome, Nishi-Ku, Osaka 550, Japan

Rapid progress in incineration technology has been brought about in the field of solid waste disposal. With the aim of reducing solid wastes to render them harmless, great progress has been advanced due to the traditional priority placed on incineration in Japan. Recent years have seen a great improvement being made in the quality of life, with the population being concentrated in modern cities. However, rising criticism has emerged against pollution problems, calling for greater controls to protect people's health and safety. To meet these needs, administrative measures have been taken to tighten the regulations on pollutioncreating factors. At the same time, a growing problem has developed over the acquisition of incineration plant sites, ash dumping grounds, etc. Under these circumstances, new needs have arisen for improved technological approaches to meet the diversified requirements of communities, each with its own particular refuse disposal problems. Steady technological progress in this field has brought about alternative possibilities to incineration as methods for waste disposal. Hitachi Zosen, in its effort to meet the growing needs of modern Japan, started early to develop a new type of "pyrolysis" furnace. Now, with technological difficulties worked out, this product is now ready for the commercial market. The following outline is to acquaint you with this new type of furnace and the technology it represents. Process D e s c r i p t i o n As i l l u s t r a t e d i n Figure 1, the process o f the p y r o l y s i s (thermal g a s i f i c a t i o n ) system c o n s i s t s p r i m a r i l y o f the f o l l o w i n g steps: r e c e i v i n g and s t o r i n g refuse; p y r o l y z i n g i t ;

0-8412-0565-5/80/47-130-587$05.00/0 © 1980 American Chemical Society Jones and Radding; Thermal Conversion of Solid Wastes and Biomass ACS Symposium Series; American Chemical Society: Washington, DC, 1980.

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burning the gas thereby produced and f i n a l l y , melting the ash. The system i s planned so that the production o f harmful substances i n the p y r o l y z i n g process i s completely i n h i b i t e d . The generation o f N 0 i n the heat recovery process through secondary combustion i s minimized by c o n t r o l l i n g the excess a i r ratio. Meanwhile, the p y r o l y t i c ash and the dust r e s u l t i n g from combustion o f the produced gas and then c o l l e c t e d by the 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 are melted i n the ash-melting furnace which i s separate from the p y r o l y s i s furnace. These r e s i d u e s w i l l subsequently be s o l i d i f i e d by water c o o l i n g . The produced gas i s burnt i n the recombustion b o i l e r . T h i s process converts the refuse i n t o energy i n the form o f steam, which i s u t i l i z e d as a source f o r generation o r h e a t i n g .


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Outline o f Test P l a n t and Experimental R e s u l t s C o n s t r u c t i o n o f G a s i f i e r . The c o n s t r u c t i o n o f the p y r o l y s i s furnace, the heart o f the p y r o l y s i s - i n c i n e r a t i o n system f o r municipal refuse i s shown i n Figures 2 and 3» I t i s a shaft furnace with a r o t a r y grate on the bottom and a refuse feeding hopper a t the top. The a i r and steam f o r the water-gas r e a c t i o n are s u p p l i e d through the r o t a r y g r a t e . The gas produced by p y r o l y s i s i s l e d out through the top o f the furnace, while the ash remover c l e a r s out the r e s i d u e s . The p a r t i c u l a r s o f t h i s t e s t p l a n t are as f o l l o w s : Capacity : 20 t/day Uses : M u n i c i p a l r e f u s e , i n d u s t r i a l waste Type o f furnace : Shaft furnace with r o t a r y grate Experimental r e s u l t s . The r e s u l t s o f experimentation with the above-mentioned t e s t p l a n t are as f o l l o w s : (1) Composition o f M u n i c i p a l Refuse. The experiment was c a r r i e d out with municipal r e f u s e , as w e l l as with a simulated u n c l a s s i f i e d municipal refuse prepared by admixing the c l a s s i f i e d municipal refuse with p l a s t i c s , g l a s s , metals, e t c . The compositions o f the r e s p e c t i v e refuse are shown i n Table I . (2) R e s u l t s o f Analyses o f P y r o l y t i c Gas and Exhaust Gas. The compositions o f the samples o f produced gases from the p y r o l y s i s furnace are as shown i n Table I I . The compositions o f p y r o l y t i c gases given i n Table I I are, as mentioned above, experimental values when the c a l o r i f i c value o f the refuse i s i n the range o f Hu = 1,265 ~ 1,330 k c a l / k g . The r e s u l t s o f the combustion t e s t s c a r r i e d out with these produced gases show that when the c a l o r i f i c value o f the gas i s as low as approx. 764 kcal/Nm , unaided combustion i s d i f f i c u l t , with a s s i s t a n c e from 3 ~ 13 % o f the heat content o f the produced gas being e s s e n t i a l . 3


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