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04170 Pressurized fluidized bed combustion of coals in mixtures of recycled flue gas and oxygen
09
Combustion
(burners,
combustion
systems)
of near-planar spinning premixed An ObseNathI 96104165 flames in a sudden expansion tube Kwon, M. J. et al., Combustion & Flame, Apr. 1996, 105, (l), 180-188. Unusual structures of premixed flames are observed experimentally in a sudden expansion tube. A unique flame having a near-planar surface spinning inside a sudden expansion tube exists in both propane/air and methane/air flames which resembles an X-shape in bare eyes. Stable near-planar spinning flames are observed in rich propane and lean methane flames and lifted spinning flames which migrate slowly toward the downstream through the expanded tube and having the speed in the order of 1 cmlmin are found in lean propane and rich methane flames. Variations of nearplanar spinning flames are also observed which include the top part of the spinning flame surface is bent toward the upstream with axisymmetric and asymmetric spinning and both the rep and the bottom parts bent horizontally.
On stretch-affected flame propagation in vertical 96104166 flows Helenbrook B. T. et al., Combusrio/z & Flante, Mar. 1996, 104, (4), 460-468. Flame propagation through an array of vortices was studied with a model which incorporated the variation of the local burning velocity with stretch. Assuming incompressible flow. the mean burning velocities were calculated and-comparkd to those of the Huygens limit.‘it was found that stretch causes a decrease in the mean burning velocity, and a mechanism which explains the trend was identified. The study also demonstrated that, as expected, stretch only has a significant effect on the mean burning velocity for vortices whose size is of the same order as that of Ihe flame thickness. 96104167 On the ‘Tulip flame’ phenomenon Clanet, C. and Searby, G. Combusdou 8~ Flajue, Apr. 1996, 105, (l), 225-238. The authors present an experimental study of the ‘Tulip flame’ phenomenon using high-speed photography. Contrary to most previous studies, the work is in a simplified quasi-constant pressure configuration in a half-open tube. It is shown that the salient features of the different stages of the flame propagation and shape can be explained by a simple geometrical model of the interaction between the flame front and rhe gas dynamics. In particular, the tulip flame results from an inversion of the flame front curvature caused by the deceleration related to loss of flame surface area. Finally, the experimental results obtained by other authors in closed vessels are in reasonable agreement with the analysis presented. 96104166 1-Pentene oxldatlon and Its lnteractlon wlth nltrlc oxlde In the low and negative temperature coefflclent regions Prabhu. S. K. et al., Cornbustiort & Flarw Mar. 1996. 104. (4). 377-390. The oxidation of l-pentene and the effeci of nitric oxide (N’O) on this oxidation has been examined in a pressurized flow reactor facility. The experiments were conducted at 6 atmospheres over the temperature range of 600-800 K and an equivalence ratio of 0.4. l-Pentene showed alkane type behaviour exhibiting low temperature reactivity and strong negative temperature coefficient behaviour. An examination of the stable species composition revealed that hydrogen abstraction reactions leading lo ally,1 radicals are more important than radical addition to the double bond. This is in contrast to previous studies on terminal olefins where the addition route was proposed as the dominant fuel consumption pathway. 96104169 Practical studles on combustion technologies of micro-pulverized coal Tamura, M. et al., Ishikawajir,la-Harr,,la Giho, 1995, 35, (5), 301-305. (In Japanese) Micro-pulverized coal (mean particle diameter 20 urn) is expected lo have advantages in improving boiler efficiency, reducing NO, emissions, and better combustion of low grade coals. The authors conducted a series of tests to evaluate the production and combustion characteristics of micropulverized coal using test furnaces. The results showed that micro-pulverized coal could be economically obtained by improving the shape of the pulverizing section and classifier, and also improve combustion efficiency and NO, emission.
96104172 Pulsating combustion applied to domestic boilers Arribas, C. Gaz d’aujourd’hui, Apr. 1996, 120, (4), 183-184. (In French) Despite numerous technical innovations, the basic principle remains the same, i.e. a gas burner is associated with a heating body. This contribution introduces a combustion method rarely used in domestic boilers, known as pulsating combuslion. This method has been used in a new range of boilers marketed by Auer. Quenching distance of laminar flame in aluminum 96104173 dust clouds Goroshin, S. er al., Combustiorl & Flame, Apr. 1996, 105, (l), 147-160. Quenching distances for aluminum dust flames have been measured in an improved flow system which can yield stable, controlled, uniform dust mixtures. Experiments were performed with fine atomized aluminum dust. The dust dispersion technique uses an annual high-speed jet which disperses dust continuously supplied via a piston-type dust feeding system. The reactivity of ulverized coal and char in shock 96104174 tube experiments with 0, an rf CO, Commissaris, F. A. et al., Coal Sci. Techrzol., 1995, 24, (l), 519-522. Describes shock tube experiments which were carried out to study the effect of CO, on the kinetics of pulverized coal and char combustion. 961047 75 Reduction of N,O emissions from circulating fluidized bed combustors by injection of fuel gases and changing of coal feed point Suzuki, Y. and Moritomi, H. Ettergy Corlvers. Mgmt., Jun.-Aug. 1996,37, (6). 1285-1290. ?h’epaper describes the reduction techniques of N,O emitted from circulating fluidized bed combustion (CFBC) of coal. Two methods, injecting the fuel gases into the riser and changing the position where coal was supplied, were tried lo decrease N,O emission. A small laboratory-scale CFBC whose whole parts were made of quartz was used. In the first method, methane, propane and hydrogen were used as a fuel gas. By injecting these gases into the riser, N, emission was decreased remarkably. Redu :tion rate was almost in proportional to the volumetric flow rate of injected gas. At this time, NO emission did not increase. Required flow rate of injected gas to achieve the same N,O reduction was different among the above gases. 96104176 Reduction of NO, emlsslons In the combustion of problematic bitumlnous coals Simon, E. et al., VGB Krafrwerkstech., 1995, 75, (8), 722-726. (In German) Presents the combustion engineering results and experiences with the various types of coal used in a power plant commissioned in Germany in 1992. 96104177 Regenerable sulfur sorbents In coal combustion. Thermodynamics and testlng by TG Hakvoort, G. Thert?lochirn. Acra, 1995, (269), 697-704. Fluidized bed combustion (FBC) at low temperatures (llOO-1300K) can be combined with sulphur removal by regenerable sorbents. Thermodynamic calculations prove that CaO-containing sorbents, chemically bound to a second compared like Al2O3 are the best. These compunds can be tested by TG in a sulphation-regeneraton-oxidation cycle by which essential properties, such as sulpharion rate and capacity, and regeneration behavior can be determined. 96104176 Regeneratlve desulfurlzatlon In coal converslon processes applylng the Interconnected fluldlzed bed system Snip, 0. C. er al., Coal Sci. Techrlol., 1995, 24, (2), 1847-1850. A mathematical model was used for an operational analysis of an interconnected fluidized-bed sorbent-based flue gas desulphurization facility. The influence of hydrodynamic parameters on the solids circulation rate was determined. Orifice dimensions and the position greatly influenced the solids circulation rate. The size can be chosen in such a way that the attainable range of solids circulation meets process requirements. Mathematical modelling results especially showed that the interconnected fluidized-bed facility can be effectively used in a regenerative desulphurization process.
Pressurlzed fluldlzed bed combustion of coals In mlxtures of recycled flue gas and oxygen Bonn, B. and Baumann, H. Coat&i. Tech~ol., 1995, 24, (2), 1923.1926. Experiments in a laboratory-scale pressurized fluidized-bed combustor showed that conversions of fuel-N to NO and N,O, of C lo CO, and of S 10 SO, are considerably lower with incorporation of flue gas recirculation and use of injected limestone sorbents than in conventional combusrion in air. The decrease in conversion can be attributed ro decomposition and reduction reactions and SO, capture with the limestone.
96104179 Relation between coal tars and formatlon of carbon deposits In coke ovens Pajak, J. et al., Coal Sci. Techrtol., 1995, 24, (l), 937-940. It was found that tars are the first intermediates from which carbon deposits are formed. Condensation of light products during secondary cracking of parts of primary tars (most probably hydrocarbons, phenols and alkyl aromatics) seems lo strongly contribute 10 pyrolytic carbon deposit formation.
96104171 Process for rapid pyrolysis of coal with Improved yields of products Kotsuru, H. et al., (Ass&led to) Shiu/rippo/f Seifetw KK, JAP. Par. JP.O7,331,256, Dec. 1995. The process is carried out by adding steam into the low portion of the pyrolyis reactor or high-temperature gases of rhe coal gasifier to decrease the residing time of the products and eliminating secondary decomposition to improve the yields of tar.
96104160 Role of coal maceral composltlon In reducing sulfur dloxlde and oxldes of nltrogen emlsslons from pulverlzed coal flames Rajan, S. and Raghavan, J. K. Coal Sci. Techuol., 1995, 24, (2), 1815.1818. Describes how seven coals of the same rank and sulphur content but with various maceral composirion were burned to study the effect coal maceral composition on sulphur dioxide and nitrogen oxides emissions,
96104170
290
Fuel and Energy Abstracts
July 1996
Combustion
(burners,
combustion
systems)
of near-planar spinning premixed An ObseNathI 96104165 flames in a sudden expansion tube Kwon, M. J. et al., Combustion & Flame, Apr. 1996, 105, (l), 180-188. Unusual structures of premixed flames are observed experimentally in a sudden expansion tube. A unique flame having a near-planar surface spinning inside a sudden expansion tube exists in both propane/air and methane/air flames which resembles an X-shape in bare eyes. Stable near-planar spinning flames are observed in rich propane and lean methane flames and lifted spinning flames which migrate slowly toward the downstream through the expanded tube and having the speed in the order of 1 cmlmin are found in lean propane and rich methane flames. Variations of nearplanar spinning flames are also observed which include the top part of the spinning flame surface is bent toward the upstream with axisymmetric and asymmetric spinning and both the rep and the bottom parts bent horizontally.
On stretch-affected flame propagation in vertical 96104166 flows Helenbrook B. T. et al., Combusrio/z & Flante, Mar. 1996, 104, (4), 460-468. Flame propagation through an array of vortices was studied with a model which incorporated the variation of the local burning velocity with stretch. Assuming incompressible flow. the mean burning velocities were calculated and-comparkd to those of the Huygens limit.‘it was found that stretch causes a decrease in the mean burning velocity, and a mechanism which explains the trend was identified. The study also demonstrated that, as expected, stretch only has a significant effect on the mean burning velocity for vortices whose size is of the same order as that of Ihe flame thickness. 96104167 On the ‘Tulip flame’ phenomenon Clanet, C. and Searby, G. Combusdou 8~ Flajue, Apr. 1996, 105, (l), 225-238. The authors present an experimental study of the ‘Tulip flame’ phenomenon using high-speed photography. Contrary to most previous studies, the work is in a simplified quasi-constant pressure configuration in a half-open tube. It is shown that the salient features of the different stages of the flame propagation and shape can be explained by a simple geometrical model of the interaction between the flame front and rhe gas dynamics. In particular, the tulip flame results from an inversion of the flame front curvature caused by the deceleration related to loss of flame surface area. Finally, the experimental results obtained by other authors in closed vessels are in reasonable agreement with the analysis presented. 96104166 1-Pentene oxldatlon and Its lnteractlon wlth nltrlc oxlde In the low and negative temperature coefflclent regions Prabhu. S. K. et al., Cornbustiort & Flarw Mar. 1996. 104. (4). 377-390. The oxidation of l-pentene and the effeci of nitric oxide (N’O) on this oxidation has been examined in a pressurized flow reactor facility. The experiments were conducted at 6 atmospheres over the temperature range of 600-800 K and an equivalence ratio of 0.4. l-Pentene showed alkane type behaviour exhibiting low temperature reactivity and strong negative temperature coefficient behaviour. An examination of the stable species composition revealed that hydrogen abstraction reactions leading lo ally,1 radicals are more important than radical addition to the double bond. This is in contrast to previous studies on terminal olefins where the addition route was proposed as the dominant fuel consumption pathway. 96104169 Practical studles on combustion technologies of micro-pulverized coal Tamura, M. et al., Ishikawajir,la-Harr,,la Giho, 1995, 35, (5), 301-305. (In Japanese) Micro-pulverized coal (mean particle diameter 20 urn) is expected lo have advantages in improving boiler efficiency, reducing NO, emissions, and better combustion of low grade coals. The authors conducted a series of tests to evaluate the production and combustion characteristics of micropulverized coal using test furnaces. The results showed that micro-pulverized coal could be economically obtained by improving the shape of the pulverizing section and classifier, and also improve combustion efficiency and NO, emission.
96104172 Pulsating combustion applied to domestic boilers Arribas, C. Gaz d’aujourd’hui, Apr. 1996, 120, (4), 183-184. (In French) Despite numerous technical innovations, the basic principle remains the same, i.e. a gas burner is associated with a heating body. This contribution introduces a combustion method rarely used in domestic boilers, known as pulsating combuslion. This method has been used in a new range of boilers marketed by Auer. Quenching distance of laminar flame in aluminum 96104173 dust clouds Goroshin, S. er al., Combustiorl & Flame, Apr. 1996, 105, (l), 147-160. Quenching distances for aluminum dust flames have been measured in an improved flow system which can yield stable, controlled, uniform dust mixtures. Experiments were performed with fine atomized aluminum dust. The dust dispersion technique uses an annual high-speed jet which disperses dust continuously supplied via a piston-type dust feeding system. The reactivity of ulverized coal and char in shock 96104174 tube experiments with 0, an rf CO, Commissaris, F. A. et al., Coal Sci. Techrzol., 1995, 24, (l), 519-522. Describes shock tube experiments which were carried out to study the effect of CO, on the kinetics of pulverized coal and char combustion. 961047 75 Reduction of N,O emissions from circulating fluidized bed combustors by injection of fuel gases and changing of coal feed point Suzuki, Y. and Moritomi, H. Ettergy Corlvers. Mgmt., Jun.-Aug. 1996,37, (6). 1285-1290. ?h’epaper describes the reduction techniques of N,O emitted from circulating fluidized bed combustion (CFBC) of coal. Two methods, injecting the fuel gases into the riser and changing the position where coal was supplied, were tried lo decrease N,O emission. A small laboratory-scale CFBC whose whole parts were made of quartz was used. In the first method, methane, propane and hydrogen were used as a fuel gas. By injecting these gases into the riser, N, emission was decreased remarkably. Redu :tion rate was almost in proportional to the volumetric flow rate of injected gas. At this time, NO emission did not increase. Required flow rate of injected gas to achieve the same N,O reduction was different among the above gases. 96104176 Reduction of NO, emlsslons In the combustion of problematic bitumlnous coals Simon, E. et al., VGB Krafrwerkstech., 1995, 75, (8), 722-726. (In German) Presents the combustion engineering results and experiences with the various types of coal used in a power plant commissioned in Germany in 1992. 96104177 Regenerable sulfur sorbents In coal combustion. Thermodynamics and testlng by TG Hakvoort, G. Thert?lochirn. Acra, 1995, (269), 697-704. Fluidized bed combustion (FBC) at low temperatures (llOO-1300K) can be combined with sulphur removal by regenerable sorbents. Thermodynamic calculations prove that CaO-containing sorbents, chemically bound to a second compared like Al2O3 are the best. These compunds can be tested by TG in a sulphation-regeneraton-oxidation cycle by which essential properties, such as sulpharion rate and capacity, and regeneration behavior can be determined. 96104176 Regeneratlve desulfurlzatlon In coal converslon processes applylng the Interconnected fluldlzed bed system Snip, 0. C. er al., Coal Sci. Techrlol., 1995, 24, (2), 1847-1850. A mathematical model was used for an operational analysis of an interconnected fluidized-bed sorbent-based flue gas desulphurization facility. The influence of hydrodynamic parameters on the solids circulation rate was determined. Orifice dimensions and the position greatly influenced the solids circulation rate. The size can be chosen in such a way that the attainable range of solids circulation meets process requirements. Mathematical modelling results especially showed that the interconnected fluidized-bed facility can be effectively used in a regenerative desulphurization process.
Pressurlzed fluldlzed bed combustion of coals In mlxtures of recycled flue gas and oxygen Bonn, B. and Baumann, H. Coat&i. Tech~ol., 1995, 24, (2), 1923.1926. Experiments in a laboratory-scale pressurized fluidized-bed combustor showed that conversions of fuel-N to NO and N,O, of C lo CO, and of S 10 SO, are considerably lower with incorporation of flue gas recirculation and use of injected limestone sorbents than in conventional combusrion in air. The decrease in conversion can be attributed ro decomposition and reduction reactions and SO, capture with the limestone.
96104179 Relation between coal tars and formatlon of carbon deposits In coke ovens Pajak, J. et al., Coal Sci. Techrtol., 1995, 24, (l), 937-940. It was found that tars are the first intermediates from which carbon deposits are formed. Condensation of light products during secondary cracking of parts of primary tars (most probably hydrocarbons, phenols and alkyl aromatics) seems lo strongly contribute 10 pyrolytic carbon deposit formation.
96104171 Process for rapid pyrolysis of coal with Improved yields of products Kotsuru, H. et al., (Ass&led to) Shiu/rippo/f Seifetw KK, JAP. Par. JP.O7,331,256, Dec. 1995. The process is carried out by adding steam into the low portion of the pyrolyis reactor or high-temperature gases of rhe coal gasifier to decrease the residing time of the products and eliminating secondary decomposition to improve the yields of tar.
96104160 Role of coal maceral composltlon In reducing sulfur dloxlde and oxldes of nltrogen emlsslons from pulverlzed coal flames Rajan, S. and Raghavan, J. K. Coal Sci. Techuol., 1995, 24, (2), 1815.1818. Describes how seven coals of the same rank and sulphur content but with various maceral composirion were burned to study the effect coal maceral composition on sulphur dioxide and nitrogen oxides emissions,
96104170
290
Fuel and Energy Abstracts
July 1996