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Treatment of wastes for fuel manufacture
18 Energy conversion and recycling
:;0666
Recycling method of polystyrene foams as solid
Nishimura, K. Jpn. Kokai Tokkyo Koho JP 11302,439 [99 302,430] (Cl. CO8J11/04), 2 Nov 1999, Appl. 1998/142,019, 15 Apr 1998. 5. (In Japanese) The recycling process of waste polystyrene foams involves a grinding process, dissolving with steam and then a drying step for solidification. Claims are also made on the granular solid fuels or powder fuels that are obtained when the solids of the drying step are ground. Small-size equipment that operates at low cost and does not require solvents are used to obtain the products.
W/W667
Recycling of carbon-enriched coal fly ash
Yang, F. Hlavacek, V. Powder Technol., 1999, 104, (2), 190-195. Flotation was used to obtain carbon-enriched fly ash powder. It contains 80% carbon, 20% minerals and also phosphorus with a concentration much htgher than that required for metallurgical coke or. boiler fuel. Before it can be reused as a fuel. the hieh ornanic content, in particular the phosphorous has to be .removgd. ,i chlorination process was attempted to treat the carbon enriched coal fly ash in order io recycle carbonaceous materials and to extract minerals. Thermodynamic simulation of the fly ash-& reaction system shows that a complete conversion of the inorganic part is feasible in a temperature range of 200-1400°C. However, experimental results indicate that reactivity of minerals with Clz is strongly dependent on temperature and is high at the first 10 minutes of reaction. At 1000°C phosphorus content can be reduced from 2,100 ppm to 24 ppm and 68% of the inorganic compounds can be removed (or recovered) in 10 minutes.
66100666 Technology and the quest for sustainability
Barker, B. EPRI Journal, 2000, 25, (2), S-17. The world is threatened by a basic conflict between the need to preserve finite, sometimes delicate environmental resources and the desire of a erowine oooulation to oromote economic develonment and a better q&ty of iif;. Despite this centuries-old problem; there are encouraging - - signs that barriers to a sustainable future will yield to technology and a growing understanding of the problems and opportunities of the coming century.
OOKlO669 Treatment of wastes for fuel manufacture Takeyama, Y. and Imaizumi, Y. Jpn. Kokai Tokkyo Koho JP 11 222,534 [99 222,534] (Cl. C08Jll/l2),17 Aug 1999, Appl. 1998/26,224, 6 Feb 1998. 8. (In Japanese) Vinyl chloride polymer wastes are treated by the addition of bivalent metal comuounds (as fine inhibitors) to the wastes, thermaldecompostion and dkhydrochTorinating in’ oxygen concentration = O12 ~01% at 200-400” under fluid state or rolling state to become removal ratio of HCI 270% and producing unfixed residual chars. Thus, poly(vinyl chloride) wastes (showing primary particle diameter = 0.2-3 urn and secondarv oarticle diameter = 0.2-60 urn) and MzO were blended in aqueous medium while stirring, dried and’crushed to give test materials (showing particle diameter 1.99-2.36 mm and Cl ratio 53.6%). The final step involved the test materials being thermallydecomposed in air/I+ (0 concentration = 53 ~01%) at 260” under a fluid state to produce a residual char showing a dehydrochlorination ratio 92.5% and a Cl ratio of 7.98%.
72
Fuel and Energy
Abstracts
January 2001
00100669 Basic mechanisms of coking pressure generation and the identification of potentially-dangerous coking coals
Eur. Comm.. [Rep.] EUR, 1999, l-42. The objectives of this study were to analyse the properties that influence the escape of volatiles from carbonizing coal charges with the intention of identifying dangerous coking coals. Correlations were sought between the internal gas pressure measured in a small doublewall oven and other coal properties. An attempt was made to establish whether the chemical changes occurring within the plastic temperature range are important by chemically analysing samples heated to a range of temperatures within the plastic range. The rate of volatile evolution and degree of Gieseler olasticitv were comnared to ascertain if excessive pressure could bk identified with high volatile release rates occurring when specific plastic properties were evident. A novel coking reactor was constructed to measure gas pressures and release rates of volatiles from the coal and coke sides of the plastic layer of carbonizing coals. in order to orobe the mechanism of cokine oressure neneration. The internal gas ‘pressure generated by coals, when carb&ized in a small double-wall oven, appears to be related sufficiently to: (a) the nitrogen content of the coal, (b) the closed porosity of the coal, (c) the d002 X-ray crystallite soacing in the 500°C semicoke. (d) the difference between (he -temperaiures >f maximum rate of volatile release in thermogravimetric analysis of a tightly-packed coal bed and of coal/ sand mixtures and (e) the difference between the temperatures of maximum Gieseler fluidity and maximum rate of volatile release, to allow such relationships to be used, after further verification, as means of identifying dangerously-coking coals. Internal gas pressures can be measured directly by using a small coking reactor taking a 20g coal charge. The pressure so measured places coals in the same order of safe to dangerous coking as that detected using the double-wall oven. After further validation and standardization, the coking reactor test offers the prospect of becoming a very useful preliminary sorting test for potentially dangerous coking coals. In the coking reactor, the gas released from a carbonizing charge initially exits from the coke-side exit but, as carbonization proceeds and the coke/semicoke layer becomes thicker, the direction of gas escape changes to the coal-side exit. Irrespective of the coking pressure that is generated, the above effect is observed for all coals. In larger ovens this effect is not observed and it believed to be due to the fissures which form in the a large coke cake. The pressure needed to maintain a nitrogen flow into the coking reactor via the gas pressure probe reaches a peak value at a temperature close to that of the directly measured internal gas pressure peak but then subsides only slowly, falling to zero at about 650°C. The slow fall indicates a low permeabiiity of coke/semicoke to gases but not as low as that of the plastic layer itself. For an internal gas pressure to be generated within the plastic coal, volatiles released from the coal substance must be trapped by low permeability layers, one on each side of the plastic layer. At the coal side the low-permeability layer is considered to consist of partially softened coal, tars and coal liquids while the low permeability at the coke side results from the nature of the pore structure of the coke/semicoke. The permeability can be increased by fissures in the coke/semicoke. All coals form a lowtemperature, low-permeability layer, so the overall resistance to gas flow of the coke/semiwke layer controls the internal gas pressure generated. Highly-fissured cokes are produced from high volatile coals, therefore they very rarely develop coking pressures. High volatile wals give highly-fissured cokes, hence very rarely do they develop coking pressures.
:;0666
Recycling method of polystyrene foams as solid
Nishimura, K. Jpn. Kokai Tokkyo Koho JP 11302,439 [99 302,430] (Cl. CO8J11/04), 2 Nov 1999, Appl. 1998/142,019, 15 Apr 1998. 5. (In Japanese) The recycling process of waste polystyrene foams involves a grinding process, dissolving with steam and then a drying step for solidification. Claims are also made on the granular solid fuels or powder fuels that are obtained when the solids of the drying step are ground. Small-size equipment that operates at low cost and does not require solvents are used to obtain the products.
W/W667
Recycling of carbon-enriched coal fly ash
Yang, F. Hlavacek, V. Powder Technol., 1999, 104, (2), 190-195. Flotation was used to obtain carbon-enriched fly ash powder. It contains 80% carbon, 20% minerals and also phosphorus with a concentration much htgher than that required for metallurgical coke or. boiler fuel. Before it can be reused as a fuel. the hieh ornanic content, in particular the phosphorous has to be .removgd. ,i chlorination process was attempted to treat the carbon enriched coal fly ash in order io recycle carbonaceous materials and to extract minerals. Thermodynamic simulation of the fly ash-& reaction system shows that a complete conversion of the inorganic part is feasible in a temperature range of 200-1400°C. However, experimental results indicate that reactivity of minerals with Clz is strongly dependent on temperature and is high at the first 10 minutes of reaction. At 1000°C phosphorus content can be reduced from 2,100 ppm to 24 ppm and 68% of the inorganic compounds can be removed (or recovered) in 10 minutes.
66100666 Technology and the quest for sustainability
Barker, B. EPRI Journal, 2000, 25, (2), S-17. The world is threatened by a basic conflict between the need to preserve finite, sometimes delicate environmental resources and the desire of a erowine oooulation to oromote economic develonment and a better q&ty of iif;. Despite this centuries-old problem; there are encouraging - - signs that barriers to a sustainable future will yield to technology and a growing understanding of the problems and opportunities of the coming century.
OOKlO669 Treatment of wastes for fuel manufacture Takeyama, Y. and Imaizumi, Y. Jpn. Kokai Tokkyo Koho JP 11 222,534 [99 222,534] (Cl. C08Jll/l2),17 Aug 1999, Appl. 1998/26,224, 6 Feb 1998. 8. (In Japanese) Vinyl chloride polymer wastes are treated by the addition of bivalent metal comuounds (as fine inhibitors) to the wastes, thermaldecompostion and dkhydrochTorinating in’ oxygen concentration = O12 ~01% at 200-400” under fluid state or rolling state to become removal ratio of HCI 270% and producing unfixed residual chars. Thus, poly(vinyl chloride) wastes (showing primary particle diameter = 0.2-3 urn and secondarv oarticle diameter = 0.2-60 urn) and MzO were blended in aqueous medium while stirring, dried and’crushed to give test materials (showing particle diameter 1.99-2.36 mm and Cl ratio 53.6%). The final step involved the test materials being thermallydecomposed in air/I+ (0 concentration = 53 ~01%) at 260” under a fluid state to produce a residual char showing a dehydrochlorination ratio 92.5% and a Cl ratio of 7.98%.
72
Fuel and Energy
Abstracts
January 2001
00100669 Basic mechanisms of coking pressure generation and the identification of potentially-dangerous coking coals
Eur. Comm.. [Rep.] EUR, 1999, l-42. The objectives of this study were to analyse the properties that influence the escape of volatiles from carbonizing coal charges with the intention of identifying dangerous coking coals. Correlations were sought between the internal gas pressure measured in a small doublewall oven and other coal properties. An attempt was made to establish whether the chemical changes occurring within the plastic temperature range are important by chemically analysing samples heated to a range of temperatures within the plastic range. The rate of volatile evolution and degree of Gieseler olasticitv were comnared to ascertain if excessive pressure could bk identified with high volatile release rates occurring when specific plastic properties were evident. A novel coking reactor was constructed to measure gas pressures and release rates of volatiles from the coal and coke sides of the plastic layer of carbonizing coals. in order to orobe the mechanism of cokine oressure neneration. The internal gas ‘pressure generated by coals, when carb&ized in a small double-wall oven, appears to be related sufficiently to: (a) the nitrogen content of the coal, (b) the closed porosity of the coal, (c) the d002 X-ray crystallite soacing in the 500°C semicoke. (d) the difference between (he -temperaiures >f maximum rate of volatile release in thermogravimetric analysis of a tightly-packed coal bed and of coal/ sand mixtures and (e) the difference between the temperatures of maximum Gieseler fluidity and maximum rate of volatile release, to allow such relationships to be used, after further verification, as means of identifying dangerously-coking coals. Internal gas pressures can be measured directly by using a small coking reactor taking a 20g coal charge. The pressure so measured places coals in the same order of safe to dangerous coking as that detected using the double-wall oven. After further validation and standardization, the coking reactor test offers the prospect of becoming a very useful preliminary sorting test for potentially dangerous coking coals. In the coking reactor, the gas released from a carbonizing charge initially exits from the coke-side exit but, as carbonization proceeds and the coke/semicoke layer becomes thicker, the direction of gas escape changes to the coal-side exit. Irrespective of the coking pressure that is generated, the above effect is observed for all coals. In larger ovens this effect is not observed and it believed to be due to the fissures which form in the a large coke cake. The pressure needed to maintain a nitrogen flow into the coking reactor via the gas pressure probe reaches a peak value at a temperature close to that of the directly measured internal gas pressure peak but then subsides only slowly, falling to zero at about 650°C. The slow fall indicates a low permeabiiity of coke/semicoke to gases but not as low as that of the plastic layer itself. For an internal gas pressure to be generated within the plastic coal, volatiles released from the coal substance must be trapped by low permeability layers, one on each side of the plastic layer. At the coal side the low-permeability layer is considered to consist of partially softened coal, tars and coal liquids while the low permeability at the coke side results from the nature of the pore structure of the coke/semicoke. The permeability can be increased by fissures in the coke/semicoke. All coals form a lowtemperature, low-permeability layer, so the overall resistance to gas flow of the coke/semiwke layer controls the internal gas pressure generated. Highly-fissured cokes are produced from high volatile coals, therefore they very rarely develop coking pressures. High volatile wals give highly-fissured cokes, hence very rarely do they develop coking pressures.