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02868 Reduction of N2O emissions from a coal-fired circulating fluidized-bed combustor by secondary fuel injection
11 Process heating, power and incineration
00/02861 Making a stronger case for industrial energy efficiency by quantifying non-energy benefits Pye, M. and McKane, A. Resources. Conserva/ion and Recycling, 2000, 28, (3/4), 171-183. This paper describes a more compelling case for industry to promote the non-energy benefits of energy efficiency investments. This is done in two ways to actively appeal to chief executive officers (CEOs) and chief financial officers’ (CFOs) primary responsibility: to enhance shareholder value. First, a description is given on the use of a project-by-project corporate financial analysis approach to quantify a broader range of productivity benefits that stem from investments in energy-efficient technologies, including waste reduction and pollution prevention. Second, and perhaps just as important, such information is presented in corporate financial terms. These standard, widely-accepted analysis procedures are more credible to industry than the economic modelling done in the past because they are structured in the same way corporate financial analysts perform discounted cash-flow investment analyses on individual projects. Case studies including such financial analyses, which quantify both energy and non-energy benefits from investments in energy-efficient technologies, are presented. Experience shows that energy efficiency projects’ non-energy benefits often exceed the value of energy savings, so energy savings should be viewed more correctly as part of the total benefits, rather than the focus of the results. Quantifying the total benefits of energy efficiency projects helps companies understand the financial opportunities of investments in energy-efficient technologies. Making a case for investing in energyefficient technologies based on energy savings alone has not always proven successful. Evidence suggests, however, that industrial decision makers will understand energy efficiency investments as part of a broader set of parameters that affect company productivity and profitability. 00102862 Modeling of solid material drying in a fluidized bed Zaporozhets, E. P. et al. Theor. Found. Chem. Eng., 1999, 33, (2), 172-180. The finite element method is used to model thermodynamic, gas dynamic and heat- and mass-transfer processes in a fluidized-bed during the drying of a solid material. Momentum, mass and energy equations and their relations in a finite element of the triangle network are presented in the integrated form. The number of solid particles and their distribution in the bed, moisture content in the final solid cross-sectional area and ejection efficiency can be calculated from this model. 00/02863 New steam parameters for advanced hard coalfired power plants Karweina, D. e/ al. P WR (Am. Sot. Mech. Eng.), 1998, 2, 937-940. The novel ferritic-martensitic materials E911 and NF616 allow for temperatures of 625°C at the steam generator outlet. Within the framework of the research programme, uncertainties regarding ferritic austentic weld connections are being studied. For a marketable unit size of 500 MW using a wide bandwidth of coal, an efficiency increase of over 47% at a flue gas temperature of 105°C downstream of the air pre-heater seems realistic. The upper unit capacity of the presented concept ranges at approximately 1000 MW. 00102864 Numerical prediction of in-furnace desulfurization with limestone Rang, W. e, ol. Hucr,_hong Ligong Dame X~rchrro. 1999. 27, (3), 4648. (In Chinese) The sulfation of CaO is described by an empirical modification of the grain model in order to simulate the kinetics of the reaction between calcium oxide and sulfur dioxide in furnace conditions. The influence of product layer diffusion and grain swelling are quantified. The time dependent decrease in CaO reactivity due to sintering is simulated through increasing the grain radius. A simpler solution scheme for the non-linear differential equation is used according to the assumption of pseudo steady state. There is good agreement between the model predictions and the published differential reactor data. 00102865 On the optimum heat exchanger sizing for heat recovery Soylemez, M. S. Energy Convers. Mancrgr., 2000, 41, (l3), 1419-1427. A thermoeconomic optimization analysis is presented yielding simple algebraic formulas for estimating the optimum heat exchanger area for energy recovery applications. The Pt-P, method is used in the present study, together with the well known Effectiveness-NTU method, for thermoeconomic analyses of three different unmixed type heat exchangers, namely, counter-current flow, parallel flow and single fluid or phase change. 00/02866 Oxidation reaction of calcium sulfide in an advanced PFBC [pressurized fluidired-bed coal combustion] condition. Effects of O2 concentration, type of limestone and particle size. Dong, Z. B. er al. Nippon Enerugi Gakkoishi., 1999, 78, (2). 99-109. Thermo-gravimetric-differential thermal analysis was used to investigate the performance of chemical reactions of CaS particles under oxidizing atmospheric conditions, in a temperature range of 700-1300’. The chemical reaction was found to be complicated process with the products of CaO, CaSO,, and the release of SO* gas. The weight of sample altered in the following three different ways: gain, loss and oscillation. The whole reaction process could be classified into three reaction steps: The reaction of CaS + 2Oa - CaSOJ took place as the weight gain in the first step. The weight loss
(energy applications
in industry)
with release of SO* gas resulted from the reaction of CaS + 3/20z - CaG + SO.2 in the second step. In the third step the oscillation behaviour can be explatned through the decomposition and formation of calcium sulfate. The Oz concentration of inlet gas strongly dictated the temperature range of the second step. Higher bulk 0s condition led to the higher O2 concentratton at the reaction front, so that the temperature of second step shifted to higher one. The reaction rate of CaS to CaO between 950 and 105fl” at 1% O? was expressed as 1.1 + 10” exp(-54847/T) s ‘. 00102867 Powder discharge structure of fluidized-bed drying apparatus Sadaki, N. Jpn. Kokai Tokkyo Koho JP II 142,056 [99 142,056] (Cl, F?6B3/ 084), 28 May 1999. Appl. 971323,853. 10 Nov 1997. 7. Fluidized-bed drying apparatus consists of a drying means for the continuous heat-treating and drying of wet powder, and overflow and underflow discharge openings for dried powder via upper and lower paths respectively. In the apparatus, prescribed numbers of rotor blades are arranged in longitudinal direction and powder discharge means are provided for controlling of discharge by rotary valve mechapism having length extended over the overflow and underflow discharge openings respectively. The structure can be used for the heat treatment of various wet powders, such as synthetic resins, feed, food, slack coal, chemicals, fertilizers, and limestone. 00/02868 Reduction of N20 emissions from a coal-fired circulating fluidired-bed combustor by secondary fuel injection Liu, H. and Gibbs, 8. M. Symp. I1nt.i Cowdmsr /Proc./. 1998. 2. 30773083. The authors investigated the reduction of NzO emrssions by secondary fuel injection. Experiments were conducted on a pilot-scale, coal-fired circulating fluidized-bed combustion (CFBC) system with a riser dimension of 161 mm (inside diameter) x 6.2 m (height). Three secondary fuels (methane, ethane, propane) and two injection positions, 350 and 1372 mm below the riser exit, were investigated. More than 7070 NzO reduction was easily achieved with either ethane or propane injection; however, when methane was used, only -30% NzO reduction was obtained due to incomplete methane combustion at higher thermal input levels within the available residence time (0.3-0.5 s). NaO emission reduction by injecting anv of the secondary fuels was always accompanied by a small increase In NO, increase versus its NaO reduction. Methane is also the least effective secondary fuel from the point of view of thermal input, whereas ethane and propane have similar ability to reduce NaO emissions. Gas-phase modelling showed that thermal decomposition of NzO plays only a minor role in the reduction of NzO emissions versus NaO reduction by radical reactions, In addition, the fact that methane is less effective than ethane in reducing NzO emissions was also confirmed by the modelling. 00102869 Seven years of operating experience with high bustDENOX plants downstream of slag tap furnaces-consequences for tailing plant. Schonrok, M. and Hein, M. PWR (Am. Sm. Mm’. Eng.1, 1998,2, 331-334. This paper presents operating experience of two coal-fired slag tap furnace power plant units retrofitted with high dust DENOX catalytic converter units and includes their performance and the remedial actions taken. The unsatisfactory geometry of the flue gas pathways, which encouraged deposition of dust, and adhesive properties of fly ash led to clogging of the catalytic converter units, reflected in excessive pressure drops. Specific issues such as the pressure loss and fuel range, ammonia nitrogen concentration in fly ash, ammonium nitrogen in flue gas desulfurization effluent, and secondary measures to remove ammonium nitrogen are all addressed. Subcritical crack growth and creep behavior of 00/02870 silicon carbide for heat exchanger applications Steen, M. Kc), Eng. Marer., 1999, 166, 73-80. In this study, sintered a-Sic was investigated for its long-term mechanical behaviour at temperatures relevant for use as a heat exchanger material in advanced gas turbine coal-fired power plants. Constant load tests in air were carried out at 1250 and 1400” under flexural and at 1400” under uniaxial tensile loading. A Dobes-Milicka plot of constant load flexural data indicated that failure under short term monotonic and long term constant load was strain controlled. The Monkman-Grant (MC) plot of all the constant load data showed a good agreement with similar literature data and confirm the temperature independence of the MC relationship. Failure mechanism maps summarize the failure mechanisms for specimens with an effective surface of lo3 and lo6 mm’, respectively. They also delineate the regions where fast fracture, sub-critical crack growth and creep are found to be life-limiting. 00/02871 Transition metal oxides for hot gas desulphurisation Elseviers, W. F. and Verelst, H. Fuel, 1999, 78, (5). 601-612. Suitable materials for the intensive desulfurization of fuel gases from an IGCC were sought by thermodynamic equilibrium simulations. A sorbent containing zinc oxide and titanium dioxide, which was able to reduce HzS levels from 3250 ppm to the thermodynamic equilibrium values in a synthetic fuel gas mixture at atmospheric pressure, was synthesized. At 600°C the material could be regenerated completely. Sorbent sulfur capacity increased upon regeneration until 100% sorbent usage. On
Fuel and Energy Abstracts
September
2000
317
00/02861 Making a stronger case for industrial energy efficiency by quantifying non-energy benefits Pye, M. and McKane, A. Resources. Conserva/ion and Recycling, 2000, 28, (3/4), 171-183. This paper describes a more compelling case for industry to promote the non-energy benefits of energy efficiency investments. This is done in two ways to actively appeal to chief executive officers (CEOs) and chief financial officers’ (CFOs) primary responsibility: to enhance shareholder value. First, a description is given on the use of a project-by-project corporate financial analysis approach to quantify a broader range of productivity benefits that stem from investments in energy-efficient technologies, including waste reduction and pollution prevention. Second, and perhaps just as important, such information is presented in corporate financial terms. These standard, widely-accepted analysis procedures are more credible to industry than the economic modelling done in the past because they are structured in the same way corporate financial analysts perform discounted cash-flow investment analyses on individual projects. Case studies including such financial analyses, which quantify both energy and non-energy benefits from investments in energy-efficient technologies, are presented. Experience shows that energy efficiency projects’ non-energy benefits often exceed the value of energy savings, so energy savings should be viewed more correctly as part of the total benefits, rather than the focus of the results. Quantifying the total benefits of energy efficiency projects helps companies understand the financial opportunities of investments in energy-efficient technologies. Making a case for investing in energyefficient technologies based on energy savings alone has not always proven successful. Evidence suggests, however, that industrial decision makers will understand energy efficiency investments as part of a broader set of parameters that affect company productivity and profitability. 00102862 Modeling of solid material drying in a fluidized bed Zaporozhets, E. P. et al. Theor. Found. Chem. Eng., 1999, 33, (2), 172-180. The finite element method is used to model thermodynamic, gas dynamic and heat- and mass-transfer processes in a fluidized-bed during the drying of a solid material. Momentum, mass and energy equations and their relations in a finite element of the triangle network are presented in the integrated form. The number of solid particles and their distribution in the bed, moisture content in the final solid cross-sectional area and ejection efficiency can be calculated from this model. 00/02863 New steam parameters for advanced hard coalfired power plants Karweina, D. e/ al. P WR (Am. Sot. Mech. Eng.), 1998, 2, 937-940. The novel ferritic-martensitic materials E911 and NF616 allow for temperatures of 625°C at the steam generator outlet. Within the framework of the research programme, uncertainties regarding ferritic austentic weld connections are being studied. For a marketable unit size of 500 MW using a wide bandwidth of coal, an efficiency increase of over 47% at a flue gas temperature of 105°C downstream of the air pre-heater seems realistic. The upper unit capacity of the presented concept ranges at approximately 1000 MW. 00102864 Numerical prediction of in-furnace desulfurization with limestone Rang, W. e, ol. Hucr,_hong Ligong Dame X~rchrro. 1999. 27, (3), 4648. (In Chinese) The sulfation of CaO is described by an empirical modification of the grain model in order to simulate the kinetics of the reaction between calcium oxide and sulfur dioxide in furnace conditions. The influence of product layer diffusion and grain swelling are quantified. The time dependent decrease in CaO reactivity due to sintering is simulated through increasing the grain radius. A simpler solution scheme for the non-linear differential equation is used according to the assumption of pseudo steady state. There is good agreement between the model predictions and the published differential reactor data. 00102865 On the optimum heat exchanger sizing for heat recovery Soylemez, M. S. Energy Convers. Mancrgr., 2000, 41, (l3), 1419-1427. A thermoeconomic optimization analysis is presented yielding simple algebraic formulas for estimating the optimum heat exchanger area for energy recovery applications. The Pt-P, method is used in the present study, together with the well known Effectiveness-NTU method, for thermoeconomic analyses of three different unmixed type heat exchangers, namely, counter-current flow, parallel flow and single fluid or phase change. 00/02866 Oxidation reaction of calcium sulfide in an advanced PFBC [pressurized fluidired-bed coal combustion] condition. Effects of O2 concentration, type of limestone and particle size. Dong, Z. B. er al. Nippon Enerugi Gakkoishi., 1999, 78, (2). 99-109. Thermo-gravimetric-differential thermal analysis was used to investigate the performance of chemical reactions of CaS particles under oxidizing atmospheric conditions, in a temperature range of 700-1300’. The chemical reaction was found to be complicated process with the products of CaO, CaSO,, and the release of SO* gas. The weight of sample altered in the following three different ways: gain, loss and oscillation. The whole reaction process could be classified into three reaction steps: The reaction of CaS + 2Oa - CaSOJ took place as the weight gain in the first step. The weight loss
(energy applications
in industry)
with release of SO* gas resulted from the reaction of CaS + 3/20z - CaG + SO.2 in the second step. In the third step the oscillation behaviour can be explatned through the decomposition and formation of calcium sulfate. The Oz concentration of inlet gas strongly dictated the temperature range of the second step. Higher bulk 0s condition led to the higher O2 concentratton at the reaction front, so that the temperature of second step shifted to higher one. The reaction rate of CaS to CaO between 950 and 105fl” at 1% O? was expressed as 1.1 + 10” exp(-54847/T) s ‘. 00102867 Powder discharge structure of fluidized-bed drying apparatus Sadaki, N. Jpn. Kokai Tokkyo Koho JP II 142,056 [99 142,056] (Cl, F?6B3/ 084), 28 May 1999. Appl. 971323,853. 10 Nov 1997. 7. Fluidized-bed drying apparatus consists of a drying means for the continuous heat-treating and drying of wet powder, and overflow and underflow discharge openings for dried powder via upper and lower paths respectively. In the apparatus, prescribed numbers of rotor blades are arranged in longitudinal direction and powder discharge means are provided for controlling of discharge by rotary valve mechapism having length extended over the overflow and underflow discharge openings respectively. The structure can be used for the heat treatment of various wet powders, such as synthetic resins, feed, food, slack coal, chemicals, fertilizers, and limestone. 00/02868 Reduction of N20 emissions from a coal-fired circulating fluidired-bed combustor by secondary fuel injection Liu, H. and Gibbs, 8. M. Symp. I1nt.i Cowdmsr /Proc./. 1998. 2. 30773083. The authors investigated the reduction of NzO emrssions by secondary fuel injection. Experiments were conducted on a pilot-scale, coal-fired circulating fluidized-bed combustion (CFBC) system with a riser dimension of 161 mm (inside diameter) x 6.2 m (height). Three secondary fuels (methane, ethane, propane) and two injection positions, 350 and 1372 mm below the riser exit, were investigated. More than 7070 NzO reduction was easily achieved with either ethane or propane injection; however, when methane was used, only -30% NzO reduction was obtained due to incomplete methane combustion at higher thermal input levels within the available residence time (0.3-0.5 s). NaO emission reduction by injecting anv of the secondary fuels was always accompanied by a small increase In NO, increase versus its NaO reduction. Methane is also the least effective secondary fuel from the point of view of thermal input, whereas ethane and propane have similar ability to reduce NaO emissions. Gas-phase modelling showed that thermal decomposition of NzO plays only a minor role in the reduction of NzO emissions versus NaO reduction by radical reactions, In addition, the fact that methane is less effective than ethane in reducing NzO emissions was also confirmed by the modelling. 00102869 Seven years of operating experience with high bustDENOX plants downstream of slag tap furnaces-consequences for tailing plant. Schonrok, M. and Hein, M. PWR (Am. Sm. Mm’. Eng.1, 1998,2, 331-334. This paper presents operating experience of two coal-fired slag tap furnace power plant units retrofitted with high dust DENOX catalytic converter units and includes their performance and the remedial actions taken. The unsatisfactory geometry of the flue gas pathways, which encouraged deposition of dust, and adhesive properties of fly ash led to clogging of the catalytic converter units, reflected in excessive pressure drops. Specific issues such as the pressure loss and fuel range, ammonia nitrogen concentration in fly ash, ammonium nitrogen in flue gas desulfurization effluent, and secondary measures to remove ammonium nitrogen are all addressed. Subcritical crack growth and creep behavior of 00/02870 silicon carbide for heat exchanger applications Steen, M. Kc), Eng. Marer., 1999, 166, 73-80. In this study, sintered a-Sic was investigated for its long-term mechanical behaviour at temperatures relevant for use as a heat exchanger material in advanced gas turbine coal-fired power plants. Constant load tests in air were carried out at 1250 and 1400” under flexural and at 1400” under uniaxial tensile loading. A Dobes-Milicka plot of constant load flexural data indicated that failure under short term monotonic and long term constant load was strain controlled. The Monkman-Grant (MC) plot of all the constant load data showed a good agreement with similar literature data and confirm the temperature independence of the MC relationship. Failure mechanism maps summarize the failure mechanisms for specimens with an effective surface of lo3 and lo6 mm’, respectively. They also delineate the regions where fast fracture, sub-critical crack growth and creep are found to be life-limiting. 00/02871 Transition metal oxides for hot gas desulphurisation Elseviers, W. F. and Verelst, H. Fuel, 1999, 78, (5). 601-612. Suitable materials for the intensive desulfurization of fuel gases from an IGCC were sought by thermodynamic equilibrium simulations. A sorbent containing zinc oxide and titanium dioxide, which was able to reduce HzS levels from 3250 ppm to the thermodynamic equilibrium values in a synthetic fuel gas mixture at atmospheric pressure, was synthesized. At 600°C the material could be regenerated completely. Sorbent sulfur capacity increased upon regeneration until 100% sorbent usage. On
Fuel and Energy Abstracts
September
2000
317