35 Gasification of Solid Waste in Accordance with the SFW-FUNK Process Downloaded by UNIV OF MASSACHUSETTS AMHERST on May 31, 2018 | https://pubs.acs.org Publication Date: August 29, 1980 | doi: 10.1021/bk-1980-0130.ch035
HARALD FUNK and HORST HUMMELSIEP Saarberg-Fernwärme, GmbH, Sulzbachstrasse 26, 66 Saarbruecken 3, West Germany
The Saarberg-Fernwärme i n Saarbrücken, West Germany, decided to b u i l d a p i l o t plant to demonstrate the feasibility of s o l i d waste g a s i f i c a t i o n after having gained long range experience i n operating i n c i n e r a t o r s . The Federal M i n i s t r y of Research and Technology of West Germany agreed to support t h i s project because the two committees, one for energy conservation and the other for environmental p r o t e c t i o n , recommended it for implementation. Incentives for
gasification
The reason for developing such a g a s i f i c a t i o n process was a c e r t a i n shortcoming of the i n c i n e r a t o r . The incinerator with i t s moving grates cannot burn i n d u s t r i a l waste or t o x i c waste or used l u b r i c a t ing oil since the generation of excessive heat w i l l cause some damage. Furthermore the i n c i n e r a t o r , a l though equipped with waterwalls, secondary combustion chamber, e l e c t r i c p r e c i p i t a t o r , large scrubbing facility and a tall stack, still i s an open system. In spite of all the extra equipment, a tall stack i s r e quired to d i s t r i b u t e impurities widely. Furthermore, some components of the flue gas are corrosive and the r e s u l t s are c o s t l y r e p a i r s . Another disadvantage i s the large amount of water required for scrubbing which i n average amounts to at least 120 gallons per ton of solid waste burnt. After all, the volume of flue gas i s about 10 times that of the gas generated i n a gas producer. The steam y i e l d e d from an incinerator has to be used r i g h t there since the distance of steam transport is rather l i m i t e d i n contrast to p i p i n g of gas. These shortcomings of the incinerator gave an incentive to compensate i n a g a s i f i c a t i o n u n i t .
0-8412-0565-5/80/47-130-485$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.
THERMAL CONVERSION OF SOLID WASTES AND BIOMASS
486
Downloaded by UNIV OF MASSACHUSETTS AMHERST on May 31, 2018 | https://pubs.acs.org Publication Date: August 29, 1980 | doi: 10.1021/bk-1980-0130.ch035
Process
description
The g a s i f i c a t i o n u n i t i s b a s i c a l l y a s i m p l e d e s i g n i n the form o f a s h a f t f u r n a c e w i t h r e v o l v i n g g r a t e s . The s o l i d waste i s f e d through locks from t h e t o p and then the ash i s d i s c a r d e d i n charges from t h e bottom, avoid ing t h e e s c a p e o f gas o r h a r m f u l components. The gas d i s c h a r g e d o v e r h e a d f r o m t h e r e a c t o r i s c o o l e d down t o ambient temperature, thus condensing t a r s , l i g h t oils and steam. The t a r s a n d o i l s a f t e r t h e i r s e p a r a t i o n f r o m water a r e r e c y c l e d t o t h e r e a c t o r t o e n r i c h t h e gas s t r e a m b y means o f a c a r b u r e t t i n g e f f e c t . A p o r t i o n o f the water recovered i n t h e condensation phase i s used for c o o l i n g the gas and t h e excess i s d i s c a r d e d a f t e r t r e a t m e n t . The a s h d i s c h a r g e d i s i n e r t a n d c a n be d i s c a r d e d f o r l a n d f i l l o p e r a t i o n s . The p r i m a r y o b j e c t o f t h i s system i s t o y i e l d gas a t a h i g h thermal e f f i c i e n c y (Figure 1). The p r o c e s s i s c a r r i e d o u t i n p h a s e s : a) Raw m a t e r i a l p r e p a r a t i o n b) Gasification c) C o n d e n s a t i o n d) Gas p u r i f i c a t i o n House-hold and i n d u s t r i a l waste i s shredded i n a hammer m i l l w h e r e p i e c e s o f 4 i n c h maximum l u m p s i z e are c a r r i e d by a conveyor t o screens through which glass, ceramics, slag, ash and other inerts smaller than 3/8 a r e d i s c a r d e d . P i e c e s l a r g e r t h a n 4" a r e s e p arated by gravity. Then t h e s o l i d waste i s charged t o t h e r e a c t o r t h r o u g h l o c k s . W h i l e t h e m a t e r i a l s l i d e s down t h r o u g h the v a r i o u s zones a s : Drying, Devolatilizing or carbonizing, Reducing, Reaction or p a r t i a l oxidation. The g a s d i s c h a r g e d f r o m t h e t o p o f t h e r e a c t o r h a s a temperature o f 500 t o 600 Κ and a f t e r c o n d e n s i b l e s are s e t t l e d o u t , i t i s compressed and charged t o t h e p u r i f i c a t i o n s e c t i o n . This gas p u r i f i c a t i o n system works on a p h y s i c a l p r i n c i p l e , s i n c e t h e h e a v i e r and h a r m f u l components a r e f r o z e n o u t - e i t h e r condensed o r s u b l i m e d - i n t h e r e g e n e r a t o r b y c o o l i n g down t h e s t e a m t o 1 7 0 o r 1 3 0 K. T h e n t h e i m p u r i t i e s r e t a i n e d i n t h e r e g e n e r a t o r a r e r e c o v e r e d b y s w i t c h i n g t o a vacuum c y c l e , w h i l e t h e p u r e g a s c o n t a i n i n g m a i n l y H^* C O , C H ^ a n d some C 0 ~ i s y i e l d e d a t a m b i e n t t e m p e r a t u r e . T h e s e 3 c y c l e s , tlie l o a d i n g phase ( r e t a i n i n g h e a v i e r components) M
Jones and Radding; Thermal Conversion of Solid Wastes and Biomass ACS Symposium Series; American Chemical Society: Washington, DC, 1980.
FUNK AND HUMMELSIEP
SFW-FUNK
Gasification of Solid Waste 487
Downloaded by UNIV OF MASSACHUSETTS AMHERST on May 31, 2018 | https://pubs.acs.org Publication Date: August 29, 1980 | doi: 10.1021/bk-1980-0130.ch035
35.
2 κ •S
1 ÛO
1 s
Jones and Radding; Thermal Conversion of Solid Wastes and Biomass ACS Symposium Series; American Chemical Society: Washington, DC, 1980.
THERMAL CONVERSION OF SOLID WASTES AND BIOMASS
488
are
r e c o v e r y phase (vacuum c y c l e ) c o o l i n g down p h a s e ( y i e l d i n g p u r e switched every 6 or 8 minutes.
Downloaded by UNIV OF MASSACHUSETTS AMHERST on May 31, 2018 | https://pubs.acs.org Publication Date: August 29, 1980 | doi: 10.1021/bk-1980-0130.ch035
Product
gas)
gas
The r a w g a s a f t e r c o n d e n s a t i o n o f l i q u i d s a t a m b i e n t temperature i s r e c o v e r e d a t a volume o f 500 t o 1000 normal cubic meters p e r t o n o f s o l i d waste (about 19 0 0 0 t o 37 0 0 0 S C F / t ) c o n t a i n i n g u p t o 8 0 % o f t h e heating value charged w i t h s o l i d waste. I t c a n be used f o r h e a t i n g , power g e n e r a t i o n o r as reducing gas f o r m e t a l l u r g i c a l processes o r as a synt h e s i s gas f o r t h e p r o d u c t i o n o f methanol. Methanol i n turn i s a clean f u e l and can be charged t o a gas t u r b i n e f o r power g e n e r a t i o n o r as a d d i t i v e o r b l e n d i n g component t o g a s o l i n e . I t c a n be s t o r e d more c h e a p l y t h a n LNG ( l i q u i d n a t u r a l g a s ) a t l e s s o f a r i s k , t o make i t more s u i t a b l e f o r p e a k s h a v i n g , s i n c e i t c a n b e c o n v e r t e d t o pure methane i n a matter o f hours. M e t h y l a l c o h o l i s used as a base product f o r formaldehyde (for p l a s t i c s ) or a c e t i c acid (pharmaceutical industry) or f o r t h e p r o d u c t i o n o f p r o t e i n s and even f o r h i g h octane gasoline (via Mobil process). Earlier
test
runs
Prior to the erection of the pilot plant at Velsen, a s m a l l t e s t r e a c t o r consuming up t o 60 k g / h o f s o l i d w a s t e was i n s t a l l e d a t N e u n k i r c h e n n e x t t o a n i n c i n e r a t o r , w h i c h was t o p r o v e f e a s i b i l i t y o f s o l i d waste g a s i f i c a t i o n . D u r i n g 2 1/2 y e a r s o f t e s t r u n s amounting t o about 10 000 hours, a l l k i n d s o f m a t e r i a l s were charged t o t h i s reactor. For instance: rubber, plast i c s , wood, used l u b r i c a t i n g o i lmixed w i t h h o u s e h o l d waste. A reasonable gas composition could be maintained for any length of time: H : 30 V o l . - % 2
CO C0
2
:
20
:
36
plus
CH^ a n d some h i g h e r h y d r o c a r b o n s w i t h n i t r o g e n . As a r u l e about 10 % o f oxygen was added t o t h e c h a r g e a n d 0.25 t o 0.40 k g o f s t e a m p e r k g o f s o l i d waste t o keep t h e r e a c t i o n temperature a t a l e v e l bet w e e n 1 1 0 0 a n d 1 2 0 0 K. T h e r e s u l t s w e r e e n c o u r a g i n g and t h e r e f o r e i t was d e c i d e d t o p r o c e e d w i t h t h e l a t t e r approach t o s o l i d waste gasification.
Jones and Radding; Thermal Conversion of Solid Wastes and Biomass ACS Symposium Series; American Chemical Society: Washington, DC, 1980.
35.
FUNK AND HUMMELSIEP
Sampling
SFW-FUNK
Gasification of Solid Waste 489
o f rawmaterial and product
Downloaded by UNIV OF MASSACHUSETTS AMHERST on May 31, 2018 | https://pubs.acs.org Publication Date: August 29, 1980 | doi: 10.1021/bk-1980-0130.ch035
The s o l i d w a s t e f r o m h o u s e h o l d w a s s a m p l e d l y s e d f r e q u e n t l y a n d v a r i e s i nc o m p o s i t i o n 22 20 20 3.0 20 0.34 0.30 0.36 0.014
Moisture Inerts Carbon Hydrogen Oxygen Nitrogen Sulfur Chlorine Fluorine
-
and anaas follows:
3 6 WT.~% 47 43 6.0 42 (by d i f f e r e n c e ) 0.75 0.45 0.53 0.02
Upper
heating
value:
as delivered 9500-12000 dry 13500-15500
k J A g k J A g
Lower
heating
value:
as delivered 8500-10500 dry 12000-14500
kJ/kg k J A g
Shredded Lower
and screened:
heating
value:
moist dry
9500-12500 12500-17000
k J A g k J A g
The lower h e a t i n g value o f the product gas p r i o r t o g a s p u r i f i c a t i o n was measured a t 7500 t o 9500 k J / normal-cubic meter w h i l e a volume o f g a s o f 700 t o 1100 n r p e rt o n o f g a s was p r o d u c e d a t n o r m a l o p e r a t i n g conditions keeping the r e a c t i o n temperature a t about 1300 K. The c o m p o s i t i o n o f t h e g a s v a r i e s a s f o l l o w i n g : H : 25 - 35 V o l . - % 2
CO
:
C0 : 2
CH : illuminants. 4
plus
some
13 - 40 18 - 4 0 5 - 1 0
Conclusion The Saarberg-Fernwârme C o . , i s t h e o n l y c o m p a n y i n E u r o p e w h i c h i s e n g a g e d i na l l k i n d s o f s o l i d w a s t e utilization, i.e. incineration, recycling operations and g a s i f i c a t i o n , t o conserve r a wm a t e r i a l s a n d energy. The g a s i f i c a t i o n o f s o l i d w a s t e a s a s u p p l e m e n t t o o p e r a t i o n o f i n c i n e r a t o r s i si n t e r e s t i n g enough t o continue t h e development o f such an approach. The intermediate step f o r commercialization i s the design o f a gasproducer a t a capacity o f 3 t o 5 tons p e r h o u r o f s o l i d w a s t e w h i c h i s now i nt h e p l a n n i n g stage. RECEIVED
December 3, 1979
Jones and Radding; Thermal Conversion of Solid Wastes and Biomass ACS Symposium Series; American Chemical Society: Washington, DC, 1980.
