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Low NOx retrofit of cell-fired coal boilers
08 Steam raising (boiler OparatiotVdesign) essentially no effect of coal Cl content on corrosion rates, unlike some of the UK results. Possible reasons for these differences are presented and discussed.
Expanded use of high-sulfur, low-fusion coals in utility boilers: effect of additives
02/01601
Pohl, J.H. el al. Proc. In!. Tech. Conf. Coal Util. Fuel Syst., 2001, 26th, 597-608. This paper reports on the ability of Mg(OH)z to control slagging at the Petersburg plant of Indianapolis Power and Light. This plant fires the 8.5-10% ash (ar), 20-25% FezOs in ash, and 3-82 CaO in ash, 10501100°C initial deformation temperature (reducing) Lynville Coal into a 440 MWe taneentiallv-fired boiler with olantent suoerheaters. This combination p;oduce; difficult slagging deposits on {he north side of the boiler between the nose and the reheater. A slurry of Mg(OH)z was injected in the corners of the boiler above the burners, The injection of Mg(OH)z increased the MgO (oxidization product of Mg(OH)z) in the deposits, reduced the FezOs concentration in the south reheater deposit, and did not eliminate slagging, but did make the north side reheater deposit more friable. Use of X-ray mapping techniques shows that MgO enters the melt by direct infusion into the melt, ingestion into the melt, and partial infusion which coats the fly ash particles. The MgO is specifically ingested into Fe0 - AlzOs - SiOz melt. There, MgO exchanges with Fe0 to form equivalent MgO- AlzOs - SiOs. The MgO compounds all have higher melting points than the corresponding Fe0 compounds. This paper used phase diagrams to estimate that the slagging problem at the Petersburg plant would be eliminated if the amount of MgO in the deposit was approximately doubled.
coal typically used. The aim of the LLOy Kymijiirvi Power Plant gasification project is a commercial scale demonstration of direct gasification of wet biofuel and the use of hot, raw and very low calorific gas directly in the existing coal fired boiler. The gasification of biofuels and co-combustion of gases in the existinn coal-fired boiler offers manv advantages such as: -recycling of CO; decreased SOz and NO, emissions, efftcient way to utilize biofuels and recycled refuse fuels, low investment and operation costs, and utilization of the existing power plant capacity. Furthermore, only small modifications were reauired in the boiler and nrocess unsets in the nasilier do not shut down the power plant. The I&St two years of operaGon (1998 and 1999) have been excellent with good availability for the gasifier and its related components. During 1998 several measurements and tests with different fuel combinations were nerformed. This namer oresents the project in detail as well as the most important iesults ‘of the first measurements. The EU Thermie program has supported this project.
02/01606 Practice and thoughts on sulfur-removing coalwater-slurry pro]ect
Liu, Y. China Pet. Process. Perrochem. Technol., 2001, 2, 9-14. This paper describes the research project (demonstration) and operation a 220 t/h coal-water-slurry-fired boiler, with use of limestone as a sorbent for SOz removal.
02/01606 Prediction of gaseous emissions from a chain rate stoker boiler using neuml networks of ARX Pautoregressive wlth exogenous inputs] structure firg, A.Z.S. er al. IEE Proc.: Sci., Meas. Technol., 2001, 148, (3). 95-
02/01602 Low NO, retrofit of cell-fired coal boilers Laux, S. er al. Proc. Inr. Tech. Conf. Coal Util. Fuel Sysr., 2001, 26th, 285-296. The boilers at TVA’s Cumberland station are among the largest pulverized coal fired boilers world-wide. These two cell-fired oncethrough boilers have a maximum Continuous Rating of 10 Mlb/h (1260 k&l _ , main steam flow for a net ratine of 1292 MWe. Each unit was retrofitted with 88 Foster Wheeler Low NO. Burners and a Boundary Air System. The final reheater was also replaced. NO, emissions from cell-fired furnaces are the highest among wall-fired furnaces due to the tight burner spacing an high burner zone heat release rates. Since the boilers fire coal with 3.25% sulfur, a specially designed boundary air system was employee for corrosion reduction The paper describes a unique approach to lower the NOx emission on cell-fired boilers. The long term results frontover 1 year of operation are presented.
The authors present the application of feed-forward multi-layered perceptron networks as a simplistic means to model the gaseous emissions emanating from the combustion of lump coal on a chaingrate stoker-fired boiler. The resultant ‘black-box’ models of the oxygen concentration, nitrogen oxides, and carbon monoxide in the flue gas were able to represent the dynamics of the process and delivered accurate one-step-ahead predictions over a wide range of unseen data. This system identification approach is an alternative to the mathematical modelling of the physical process, which although lacking in model transparency and elegance, is able to produce accurate one-step-ahead predictions of the derivatives of combustion. This has been demonstrated not onlv with data sets that were obtained from the same series of experiments (which also demonstrated the repeatability of the model) but also for data with a temporal separation of almost 8 months from the training data set.
Numerical simulation of pulverized coal combustion and NO, emission In a front-wall fired boiler Xu, M-H. er al. Gongcheng Rewuli Xuebao, 2001, 22, (2). 249-252. (In
02lO1607 Radiation effects in combustion chambers of coal-flred boilers with a fixed bed
02/01603
Chinese) Numerical simulation of the flow, combustion process, and NO, emission in a front-wall coal fired boiler of 350MW with 24 swirl burners is presented. Five different cases with lOO%, 95%, 85%, 70% and 50% boiler full load are simulated. The comparison between the simulation and the plant data shows a good agreement for all cases except the one of 50% boiler load. The calculated results illustrate that the NO, model used shows a higher sensitivity to temperature than to oxygen level in the furnace.
Power boiler fuel augmentation with a biomass fired atmospheric circulating fluid-bed gasifier
02/01604
Raskin, N. et al. Biomass and Bioenergy, 2001, 20, (6), 471481. The successful experience in developing the advanced Foster Wheeler atmospheric circulating fluidized-bed (ACFB) combustion system subsequently led to the development of the ACFB gasification (ACFBG) Technology in the early 1980s. The driving force for the development work was the dramatic increase in oil price during this period. The primary advantage of the ACFBG technology is that it enables the substitution of expensive fuels (e.g. oil or gas) with cheaper solid fuels. Prior to this Lahti project, Foster Wheeler had supplied four waste wood fired commercial scale ACFBGs in the mid-1980s to the pulp and paper industry with capacities from 17 to 35 MW,s based on fuel input. These units are still in successful operation today. Lahden Liimpiivoima Oy (LLOv) is a Finnish power company producing power and distiict‘heat-for the City of Lahti. The company is jointly owned by the city of Lahti and by Fortum Oy, the largest utility power company in Finland. LLOy operates the Kymijlrvi Power Plant located nearby the city of Lahti in Southern Finland. To keep the energy prices as low as possible, Plant personnel are continuously looking for the most economical fuel sources, and simultaneously, trying to improve the environmental aspects of the energy production. Currently, about 300 GW h/a of different types of biofuels and refuse fuels are available in the Lahti area. On an annual basis, the available amount of biofuels and refuse fuels is enough to substitute for about 15% of the fuels burned in the main boiler, equalling up to 30% of the 204
Fuel and Energy Abstmcts
May 2002
Biyikoglu, A. and Sivrioglu, M. Radiat. Transfer-III, Proc. Int. Symp. Radiar. Transfer. 3rd, 2001, 547-557. Edited by Menguc M. P. and Selcuk N. Steady state combustion was investigated for the simulation of reactive turbulent flow within the combustion chamber of a small-scale coalfired boiler with a fixed bed. For this purpose, the one-dimensional code, CLAYER developed for determining the thermochemical field of coal combustion in a fixed bed, the zero-dimensional code, CREK used in determining the thermochemical field of reactive turbulent flows and the two-dimensional code, TEACH used in determining the hydrodynamical flow field in the combustion chamber, are combined and modified. The Unreacted Shrinking Core Model is used for coal combustion. The turbulent reactive flow in combustion chamber is analysed using k-c turbulence, four-flux radiation and combustion models including chemical equilibrium and kinetics calculations The comparison of the existing experimental data with the emission calculations at the exit of combustion chamber has resulted in an agreement with an acceptable degree. The effects of radiative heat transfer on temperature distribution and concentrations of combustion products are analysed.
02/01606
Sootblowing optlmixation in coal-fired boilers
Romero, C.E. et al. Proc. Int. Tech. Conf. Coal Util. Fuel Sysr., 2001, 26th. 1003-1014. Needs for performance improvement, NO, emissions control, and changes in fuel quality have increased the emphasis on slagging and soot deposition control in utility boilers. The challenge in developing optimized sootblowing strategies is to determine which portions of the boiler to clean and on what schedule, considering the tradeoffs between NO,, heat rate, steam temperatures, stack opacity, and sootblower steam consumption. This paper describes sootblow optimization studies at four-coal-fired units which vary in size, firing configuration and type of coal, and utilize different methods of slagging/fouling condition monitoring ranging from the real-time cleanliness calculations to the furnace exit gas temperature measurement. The paper emphasizes the sootblowing tradeoffs between NO. emissions and heat rate.
Expanded use of high-sulfur, low-fusion coals in utility boilers: effect of additives
02/01601
Pohl, J.H. el al. Proc. In!. Tech. Conf. Coal Util. Fuel Syst., 2001, 26th, 597-608. This paper reports on the ability of Mg(OH)z to control slagging at the Petersburg plant of Indianapolis Power and Light. This plant fires the 8.5-10% ash (ar), 20-25% FezOs in ash, and 3-82 CaO in ash, 10501100°C initial deformation temperature (reducing) Lynville Coal into a 440 MWe taneentiallv-fired boiler with olantent suoerheaters. This combination p;oduce; difficult slagging deposits on {he north side of the boiler between the nose and the reheater. A slurry of Mg(OH)z was injected in the corners of the boiler above the burners, The injection of Mg(OH)z increased the MgO (oxidization product of Mg(OH)z) in the deposits, reduced the FezOs concentration in the south reheater deposit, and did not eliminate slagging, but did make the north side reheater deposit more friable. Use of X-ray mapping techniques shows that MgO enters the melt by direct infusion into the melt, ingestion into the melt, and partial infusion which coats the fly ash particles. The MgO is specifically ingested into Fe0 - AlzOs - SiOz melt. There, MgO exchanges with Fe0 to form equivalent MgO- AlzOs - SiOs. The MgO compounds all have higher melting points than the corresponding Fe0 compounds. This paper used phase diagrams to estimate that the slagging problem at the Petersburg plant would be eliminated if the amount of MgO in the deposit was approximately doubled.
coal typically used. The aim of the LLOy Kymijiirvi Power Plant gasification project is a commercial scale demonstration of direct gasification of wet biofuel and the use of hot, raw and very low calorific gas directly in the existing coal fired boiler. The gasification of biofuels and co-combustion of gases in the existinn coal-fired boiler offers manv advantages such as: -recycling of CO; decreased SOz and NO, emissions, efftcient way to utilize biofuels and recycled refuse fuels, low investment and operation costs, and utilization of the existing power plant capacity. Furthermore, only small modifications were reauired in the boiler and nrocess unsets in the nasilier do not shut down the power plant. The I&St two years of operaGon (1998 and 1999) have been excellent with good availability for the gasifier and its related components. During 1998 several measurements and tests with different fuel combinations were nerformed. This namer oresents the project in detail as well as the most important iesults ‘of the first measurements. The EU Thermie program has supported this project.
02/01606 Practice and thoughts on sulfur-removing coalwater-slurry pro]ect
Liu, Y. China Pet. Process. Perrochem. Technol., 2001, 2, 9-14. This paper describes the research project (demonstration) and operation a 220 t/h coal-water-slurry-fired boiler, with use of limestone as a sorbent for SOz removal.
02/01606 Prediction of gaseous emissions from a chain rate stoker boiler using neuml networks of ARX Pautoregressive wlth exogenous inputs] structure firg, A.Z.S. er al. IEE Proc.: Sci., Meas. Technol., 2001, 148, (3). 95-
02/01602 Low NO, retrofit of cell-fired coal boilers Laux, S. er al. Proc. Inr. Tech. Conf. Coal Util. Fuel Sysr., 2001, 26th, 285-296. The boilers at TVA’s Cumberland station are among the largest pulverized coal fired boilers world-wide. These two cell-fired oncethrough boilers have a maximum Continuous Rating of 10 Mlb/h (1260 k&l _ , main steam flow for a net ratine of 1292 MWe. Each unit was retrofitted with 88 Foster Wheeler Low NO. Burners and a Boundary Air System. The final reheater was also replaced. NO, emissions from cell-fired furnaces are the highest among wall-fired furnaces due to the tight burner spacing an high burner zone heat release rates. Since the boilers fire coal with 3.25% sulfur, a specially designed boundary air system was employee for corrosion reduction The paper describes a unique approach to lower the NOx emission on cell-fired boilers. The long term results frontover 1 year of operation are presented.
The authors present the application of feed-forward multi-layered perceptron networks as a simplistic means to model the gaseous emissions emanating from the combustion of lump coal on a chaingrate stoker-fired boiler. The resultant ‘black-box’ models of the oxygen concentration, nitrogen oxides, and carbon monoxide in the flue gas were able to represent the dynamics of the process and delivered accurate one-step-ahead predictions over a wide range of unseen data. This system identification approach is an alternative to the mathematical modelling of the physical process, which although lacking in model transparency and elegance, is able to produce accurate one-step-ahead predictions of the derivatives of combustion. This has been demonstrated not onlv with data sets that were obtained from the same series of experiments (which also demonstrated the repeatability of the model) but also for data with a temporal separation of almost 8 months from the training data set.
Numerical simulation of pulverized coal combustion and NO, emission In a front-wall fired boiler Xu, M-H. er al. Gongcheng Rewuli Xuebao, 2001, 22, (2). 249-252. (In
02lO1607 Radiation effects in combustion chambers of coal-flred boilers with a fixed bed
02/01603
Chinese) Numerical simulation of the flow, combustion process, and NO, emission in a front-wall coal fired boiler of 350MW with 24 swirl burners is presented. Five different cases with lOO%, 95%, 85%, 70% and 50% boiler full load are simulated. The comparison between the simulation and the plant data shows a good agreement for all cases except the one of 50% boiler load. The calculated results illustrate that the NO, model used shows a higher sensitivity to temperature than to oxygen level in the furnace.
Power boiler fuel augmentation with a biomass fired atmospheric circulating fluid-bed gasifier
02/01604
Raskin, N. et al. Biomass and Bioenergy, 2001, 20, (6), 471481. The successful experience in developing the advanced Foster Wheeler atmospheric circulating fluidized-bed (ACFB) combustion system subsequently led to the development of the ACFB gasification (ACFBG) Technology in the early 1980s. The driving force for the development work was the dramatic increase in oil price during this period. The primary advantage of the ACFBG technology is that it enables the substitution of expensive fuels (e.g. oil or gas) with cheaper solid fuels. Prior to this Lahti project, Foster Wheeler had supplied four waste wood fired commercial scale ACFBGs in the mid-1980s to the pulp and paper industry with capacities from 17 to 35 MW,s based on fuel input. These units are still in successful operation today. Lahden Liimpiivoima Oy (LLOv) is a Finnish power company producing power and distiict‘heat-for the City of Lahti. The company is jointly owned by the city of Lahti and by Fortum Oy, the largest utility power company in Finland. LLOy operates the Kymijlrvi Power Plant located nearby the city of Lahti in Southern Finland. To keep the energy prices as low as possible, Plant personnel are continuously looking for the most economical fuel sources, and simultaneously, trying to improve the environmental aspects of the energy production. Currently, about 300 GW h/a of different types of biofuels and refuse fuels are available in the Lahti area. On an annual basis, the available amount of biofuels and refuse fuels is enough to substitute for about 15% of the fuels burned in the main boiler, equalling up to 30% of the 204
Fuel and Energy Abstmcts
May 2002
Biyikoglu, A. and Sivrioglu, M. Radiat. Transfer-III, Proc. Int. Symp. Radiar. Transfer. 3rd, 2001, 547-557. Edited by Menguc M. P. and Selcuk N. Steady state combustion was investigated for the simulation of reactive turbulent flow within the combustion chamber of a small-scale coalfired boiler with a fixed bed. For this purpose, the one-dimensional code, CLAYER developed for determining the thermochemical field of coal combustion in a fixed bed, the zero-dimensional code, CREK used in determining the thermochemical field of reactive turbulent flows and the two-dimensional code, TEACH used in determining the hydrodynamical flow field in the combustion chamber, are combined and modified. The Unreacted Shrinking Core Model is used for coal combustion. The turbulent reactive flow in combustion chamber is analysed using k-c turbulence, four-flux radiation and combustion models including chemical equilibrium and kinetics calculations The comparison of the existing experimental data with the emission calculations at the exit of combustion chamber has resulted in an agreement with an acceptable degree. The effects of radiative heat transfer on temperature distribution and concentrations of combustion products are analysed.
02/01606
Sootblowing optlmixation in coal-fired boilers
Romero, C.E. et al. Proc. Int. Tech. Conf. Coal Util. Fuel Sysr., 2001, 26th. 1003-1014. Needs for performance improvement, NO, emissions control, and changes in fuel quality have increased the emphasis on slagging and soot deposition control in utility boilers. The challenge in developing optimized sootblowing strategies is to determine which portions of the boiler to clean and on what schedule, considering the tradeoffs between NO,, heat rate, steam temperatures, stack opacity, and sootblower steam consumption. This paper describes sootblow optimization studies at four-coal-fired units which vary in size, firing configuration and type of coal, and utilize different methods of slagging/fouling condition monitoring ranging from the real-time cleanliness calculations to the furnace exit gas temperature measurement. The paper emphasizes the sootblowing tradeoffs between NO. emissions and heat rate.