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01405 Condensing economizers for efficiency improvement and emissions control in industrial boilers
08 Steam raising (boiler operation/design) Boiler online optimization
99l01403 (BOOST)
software technology
P. Combust. Can. ‘96 Conf.: Future Changing Can. Efjic. Environ., 1996, Paper 46/l-Paper 46114.
Reinermann,
Role Combust.
In the search to decrease NO, emissions and simultaneously optimize boiler efficiency and reduce carbon-in-ash levels, recent advances in software technology for modelling, optimizing and controlling industrial processes were applied to coal-fired boilers. In addition, this technology, BOOST (boiler on-line optimization software technology), was used to increase boiler efficiency and maintaining NO, emission levels. BOOST, which is an advanced on-line control and optimization neural network and part of EPRI’s Generic NO, Control Intelligent System (GNOCIS), uses nonlinear models to satisfy objective functions and perform constrained-mixedinteger optimization such as deciding burner configuration. The results of two installations and the theory behind BOOST were presented.
Cofiring wood waste for NO, control in cyclone 99lO14Q4 boilers: identifying the mechanisms Tillman, Mater.,
D. et al. Proc.
Making Bus. Biomass Energy, Environ., Chem., Fibers Biomass Conf. Am., 3rd. 1997, (l), 391-399. Edited by
Overend, R. P. and Chornet, E., Elsevier, Oxford, UK. At the Allen Fossil Plant (ALF) of TVA during 1994-1996, wood co-firing in cyclone boilers was tested extensively as an element of NO, control strategy. The tests, conducted in a 275MW boiler at co-firing levels of S-20 mass%, were conducted with biomass particles ranging in size from sawdust to 1” chips. In addition, tests included co-firing of wood waste with tyrederived fuel and both eastern and western bituminous coal. The test programme included extensive fuel characterization using thermogravimetric analysis as well as traditional proximate and ultimate analysis, plant testing and extensive computer modelling. Co-firing with wood waste can be used for NO, control. Strong statistical correlations were observed between such factors as: (1) fuel nitrogen content, (2) fuel volatility, (3) firing rate and (4) excess oxygen content and NO, emissions.
Condensing economizers for efficiency improvement and emissions control In industrial boilers
99iO1405
Butcher, Combust.
T. A. et al.
Combust. Can. 1996 Conf.: Can. Eff7c. Environ., 1996, Paper711-7115.
Future
Changing
Role
In thermal efficiency, condensing economizers recover sensible and latent heat from boiler flue gas, leading to marked improvements. These economizers can, in addition, be used to reduce emissions of particulates and sulfur dioxide. This paper summarizes the current commercial status and continuing development efforts with one type of condensing economizer. In this design Teflon covered tubes and enclosure walls are used to handle the corrosive condensate. Originally, these economizers were developed only for heat recovery and involved a single heat exchanger. Over 100 of these single-stage economizes are currently in operation in industrial and commercial boiler plants. In addition to improving thermal efficiency, condensing economizers can also be used to reduce particulate emissions primarily by inertial impaction of particles on tube surfaces, water droplets and added impactors. Collected particles are then removed with condensate. With coal-firing, tests have shown particle removal efficiencies as high as 98%. To enhance the missions control potential of condensing economizer technology a two-stage economizer system concept has been developed. Two heat exchanger modules are used. The first is a downflow design and recovers primarily sensible heat from the flue gas. The second is upflow and recovers mostly latent heat. Condensate is collected in a transition plenum between the two stages. Termed the integrated flue gas treatment system (IFGT), this configuration provides great flexibility for implementing emissions reduction strategies. Particulate emissions can be reduced without impacting sensible heat recovery by recirculating collected condensate to spray nozzles at the top of the second stage heat exchanger. In tests with heavy oil firing, particulate reductions over 90% and final emission rates on the order of 0.005 Ib/MBtu are achieved. Adding sorbents to the recirculated condensate reduces sulfur dioxide emissions and SO2 removal efficiencies over 95% are achieved. Such economizers are now being offered on a commercial basis. Also, condensing economizers show great potential for the removal of certain air toxics.
Design and functions of the furnace-front briquet99i01406 tina ores8 in industrial brlauet makina H. and Zhang, X. Zhejiang Daxue Fuebao, Ziran Kexueban, 1998, (In Chinese) High efficiency and low pollution are needed due to the development in the domestic economy. There are good environmental and energy saving profits when burning briquettes in industrial boilers. Compared with burning raw coal, boiler efficiency increases about S-10% and dust concentration decreases about 50-60%. Ringelmann blackness of the flue gas is less than 0.5-1.0. The desulfurization efficiency is 40%-50%.
design cost is reduced by 25%. Emission of nitrogen oxides during firing with natural gas is 50-55 mg/m’. The coefficient of performance of the retrofitted boiler is 94.4%. 99lO14Q8 Experience with combustion tuning and fuel system modifications to inexpensively reduce NO, emissions from eleven coal-fired tangential boilers
Mazzi, E. A. and Haythornthwaite, S. M. EC (Am. Sot. Mech. Eng.), 1997, 5, (l), 219-229. Discussed are commercially-available, low-cost options to achieve NO, compliance on pulverized coal-fired tangential boilers which require 5-50% reductions. Often, NO, reductions and economic benefits (e.g. increased efficiency, reduced maintenance) can be achieved simultaneously. Actual performance data are presented based on direct experience applying combustion tuning and fuel system modifications on 11 coal-fired, drybottom tangential boilers in the USA. Presented are several low-cost options, some of which are generally unknown to electrical utility engineers. Frequently, combustion tuning efforts fall short of required NO, reduction goals because it is not known how to inexpensively overcome common limiting factors (e.g. unburnt carbon, slagging). To overcome these factors important limiting factors are described, including low-cost methods.
Experimental and numerical studies on re burn jet 99101409 penetration and mixing with application to boilers and municipal waste incinerators Weber, R. et al. .I. Inst. Energv, 1998, 71, (487). 94-109. One of the most important parameters affecting NO, reduction is the mixing of the re-burn fuel with primary combustion-zone products. The mixing can be controlled by re-burn jet parameters. The study has a twofold objective: (1) to assess the ability of computational fluid dynamics (COD) for predicting properties of the jets and (2) to develop a methodology for scaling the results obtained for isothermal flows into combusting flows in boilers and municipal-waste incinerators. Using the IFRF [International Flame Research Foundation] stand for simulating flows in boilers and incinerators, fluid-flow experiments were carried out. The Laser Doppler technique is used to measure three-dimensional flows and the Laser Sheet technique is used to visualize the reburn jets, their trajectories and mixing. The CFD-computed time-mean three-dimensional flow fields agreed well with the measured flow patterns. Each of the eight reburn jets responded to the local flow conditions prevailing upstream of the injection position. Numerical simulations of the reburn-jet penetration depth and mixing required a good knowledge of the overall flow pattern within the boiler. This paper contains correlations for estimating the jetpenetration depth under isothermal and combustion conditions.
99lO1410 in China
Feasibility of AIJ pilot project options: CFBC 81CHP
Liu, D. et al.
Greenhouse Gas Mitigation, Proc. Technology Act. Imple1997 (Pub. 1998). 425-435. Edited by Riemer, P. W. F. et al.,
mented.lointly,
Elsevier, Oxford, UK. This paper discusses co-generation in the Activities Implemented Jointly (AIJ) programme in China and technology options and simulation case studies in the field of industrial boiler retrofitting. The existing situation of industrial boilers and greenhouse gas emission mitigation potential is discussed. This topic area includes, installed industrial boilers (coal consumption and CO;? emissions, low thermal and operational efficiency of installed boilers) and CO2 emission mitigation technologies for industrial boilers (technical characteristics of advanced industrial boilers, advanced burners for fluidized-bed combustors [FBC] and pulverized coal-fired boilers, advanced boiler technologies, fluidized-bed technology development, potential global environmental benefits from circulating FBC technologies). The discussion then moves to the combined heat and power development situation in China. Priority technologies options and recommended AU pilot projects are examined. The feasibility of AIJ pilot project options and major barriers hindering AIJ co-operation are also discussed. Liaocheng Thermal Power co-generation plant in Shangdong Province is the case study. It comprises background, project description, validity as AIJ project, cost/benefit assessment of COz emission mitigation, other environmental impact assessments and foreign technology input and impact.
Zh&g,
32, (2), 213-219.
Experience on the retrofitting of energy equipment 99101497 by using retrofitting of boiler TP-80 as an example Anon. Elektr. Stn., 1998, (3). 2-5. (In Russian) The capacity of a retrofitted Kusnetsk coal or natural gas fired boiler is improved from 420-500 tons per hour. The reliability of main components and heating surface of the boiler are improved. Compared to new boiler design, metal consumption during retrofitting is decreased by 500 tons. The
142
Fuel and Energy Abstracts
March 1999
99101411 section
Heat transfer assessment of a boiler convective
Azevedo, J. L. T. et al. New Dev. Heat Exch., (Sel. Pap. Semin.], 1993, 117129. Edited by Afgan, N. H., Gordon & Breach, Amsterdam, the Netherlands. _ The present work is concerned with the convective section of a coal-fired boiler and the on-line monitoring of the heat transfer capacity of the heat exchangers in it. The developed monitoring system performs mass and energy balances with available values from the process computer allowing the calculation of the heat transfer coefficients. The system installed at the boiler was assembled in order to assist the operators in the decision procedure of the soot blowing operations. In the present work the global heat exchange coefficients from each individual exchanger is assessed, showing the degradation along time due to fouling. The temporal evolution of the boiler efficiency is analysed using this data for different sequences of soot blowing operations.
99l01403 (BOOST)
software technology
P. Combust. Can. ‘96 Conf.: Future Changing Can. Efjic. Environ., 1996, Paper 46/l-Paper 46114.
Reinermann,
Role Combust.
In the search to decrease NO, emissions and simultaneously optimize boiler efficiency and reduce carbon-in-ash levels, recent advances in software technology for modelling, optimizing and controlling industrial processes were applied to coal-fired boilers. In addition, this technology, BOOST (boiler on-line optimization software technology), was used to increase boiler efficiency and maintaining NO, emission levels. BOOST, which is an advanced on-line control and optimization neural network and part of EPRI’s Generic NO, Control Intelligent System (GNOCIS), uses nonlinear models to satisfy objective functions and perform constrained-mixedinteger optimization such as deciding burner configuration. The results of two installations and the theory behind BOOST were presented.
Cofiring wood waste for NO, control in cyclone 99lO14Q4 boilers: identifying the mechanisms Tillman, Mater.,
D. et al. Proc.
Making Bus. Biomass Energy, Environ., Chem., Fibers Biomass Conf. Am., 3rd. 1997, (l), 391-399. Edited by
Overend, R. P. and Chornet, E., Elsevier, Oxford, UK. At the Allen Fossil Plant (ALF) of TVA during 1994-1996, wood co-firing in cyclone boilers was tested extensively as an element of NO, control strategy. The tests, conducted in a 275MW boiler at co-firing levels of S-20 mass%, were conducted with biomass particles ranging in size from sawdust to 1” chips. In addition, tests included co-firing of wood waste with tyrederived fuel and both eastern and western bituminous coal. The test programme included extensive fuel characterization using thermogravimetric analysis as well as traditional proximate and ultimate analysis, plant testing and extensive computer modelling. Co-firing with wood waste can be used for NO, control. Strong statistical correlations were observed between such factors as: (1) fuel nitrogen content, (2) fuel volatility, (3) firing rate and (4) excess oxygen content and NO, emissions.
Condensing economizers for efficiency improvement and emissions control In industrial boilers
99iO1405
Butcher, Combust.
T. A. et al.
Combust. Can. 1996 Conf.: Can. Eff7c. Environ., 1996, Paper711-7115.
Future
Changing
Role
In thermal efficiency, condensing economizers recover sensible and latent heat from boiler flue gas, leading to marked improvements. These economizers can, in addition, be used to reduce emissions of particulates and sulfur dioxide. This paper summarizes the current commercial status and continuing development efforts with one type of condensing economizer. In this design Teflon covered tubes and enclosure walls are used to handle the corrosive condensate. Originally, these economizers were developed only for heat recovery and involved a single heat exchanger. Over 100 of these single-stage economizes are currently in operation in industrial and commercial boiler plants. In addition to improving thermal efficiency, condensing economizers can also be used to reduce particulate emissions primarily by inertial impaction of particles on tube surfaces, water droplets and added impactors. Collected particles are then removed with condensate. With coal-firing, tests have shown particle removal efficiencies as high as 98%. To enhance the missions control potential of condensing economizer technology a two-stage economizer system concept has been developed. Two heat exchanger modules are used. The first is a downflow design and recovers primarily sensible heat from the flue gas. The second is upflow and recovers mostly latent heat. Condensate is collected in a transition plenum between the two stages. Termed the integrated flue gas treatment system (IFGT), this configuration provides great flexibility for implementing emissions reduction strategies. Particulate emissions can be reduced without impacting sensible heat recovery by recirculating collected condensate to spray nozzles at the top of the second stage heat exchanger. In tests with heavy oil firing, particulate reductions over 90% and final emission rates on the order of 0.005 Ib/MBtu are achieved. Adding sorbents to the recirculated condensate reduces sulfur dioxide emissions and SO2 removal efficiencies over 95% are achieved. Such economizers are now being offered on a commercial basis. Also, condensing economizers show great potential for the removal of certain air toxics.
Design and functions of the furnace-front briquet99i01406 tina ores8 in industrial brlauet makina H. and Zhang, X. Zhejiang Daxue Fuebao, Ziran Kexueban, 1998, (In Chinese) High efficiency and low pollution are needed due to the development in the domestic economy. There are good environmental and energy saving profits when burning briquettes in industrial boilers. Compared with burning raw coal, boiler efficiency increases about S-10% and dust concentration decreases about 50-60%. Ringelmann blackness of the flue gas is less than 0.5-1.0. The desulfurization efficiency is 40%-50%.
design cost is reduced by 25%. Emission of nitrogen oxides during firing with natural gas is 50-55 mg/m’. The coefficient of performance of the retrofitted boiler is 94.4%. 99lO14Q8 Experience with combustion tuning and fuel system modifications to inexpensively reduce NO, emissions from eleven coal-fired tangential boilers
Mazzi, E. A. and Haythornthwaite, S. M. EC (Am. Sot. Mech. Eng.), 1997, 5, (l), 219-229. Discussed are commercially-available, low-cost options to achieve NO, compliance on pulverized coal-fired tangential boilers which require 5-50% reductions. Often, NO, reductions and economic benefits (e.g. increased efficiency, reduced maintenance) can be achieved simultaneously. Actual performance data are presented based on direct experience applying combustion tuning and fuel system modifications on 11 coal-fired, drybottom tangential boilers in the USA. Presented are several low-cost options, some of which are generally unknown to electrical utility engineers. Frequently, combustion tuning efforts fall short of required NO, reduction goals because it is not known how to inexpensively overcome common limiting factors (e.g. unburnt carbon, slagging). To overcome these factors important limiting factors are described, including low-cost methods.
Experimental and numerical studies on re burn jet 99101409 penetration and mixing with application to boilers and municipal waste incinerators Weber, R. et al. .I. Inst. Energv, 1998, 71, (487). 94-109. One of the most important parameters affecting NO, reduction is the mixing of the re-burn fuel with primary combustion-zone products. The mixing can be controlled by re-burn jet parameters. The study has a twofold objective: (1) to assess the ability of computational fluid dynamics (COD) for predicting properties of the jets and (2) to develop a methodology for scaling the results obtained for isothermal flows into combusting flows in boilers and municipal-waste incinerators. Using the IFRF [International Flame Research Foundation] stand for simulating flows in boilers and incinerators, fluid-flow experiments were carried out. The Laser Doppler technique is used to measure three-dimensional flows and the Laser Sheet technique is used to visualize the reburn jets, their trajectories and mixing. The CFD-computed time-mean three-dimensional flow fields agreed well with the measured flow patterns. Each of the eight reburn jets responded to the local flow conditions prevailing upstream of the injection position. Numerical simulations of the reburn-jet penetration depth and mixing required a good knowledge of the overall flow pattern within the boiler. This paper contains correlations for estimating the jetpenetration depth under isothermal and combustion conditions.
99lO1410 in China
Feasibility of AIJ pilot project options: CFBC 81CHP
Liu, D. et al.
Greenhouse Gas Mitigation, Proc. Technology Act. Imple1997 (Pub. 1998). 425-435. Edited by Riemer, P. W. F. et al.,
mented.lointly,
Elsevier, Oxford, UK. This paper discusses co-generation in the Activities Implemented Jointly (AIJ) programme in China and technology options and simulation case studies in the field of industrial boiler retrofitting. The existing situation of industrial boilers and greenhouse gas emission mitigation potential is discussed. This topic area includes, installed industrial boilers (coal consumption and CO;? emissions, low thermal and operational efficiency of installed boilers) and CO2 emission mitigation technologies for industrial boilers (technical characteristics of advanced industrial boilers, advanced burners for fluidized-bed combustors [FBC] and pulverized coal-fired boilers, advanced boiler technologies, fluidized-bed technology development, potential global environmental benefits from circulating FBC technologies). The discussion then moves to the combined heat and power development situation in China. Priority technologies options and recommended AU pilot projects are examined. The feasibility of AIJ pilot project options and major barriers hindering AIJ co-operation are also discussed. Liaocheng Thermal Power co-generation plant in Shangdong Province is the case study. It comprises background, project description, validity as AIJ project, cost/benefit assessment of COz emission mitigation, other environmental impact assessments and foreign technology input and impact.
Zh&g,
32, (2), 213-219.
Experience on the retrofitting of energy equipment 99101497 by using retrofitting of boiler TP-80 as an example Anon. Elektr. Stn., 1998, (3). 2-5. (In Russian) The capacity of a retrofitted Kusnetsk coal or natural gas fired boiler is improved from 420-500 tons per hour. The reliability of main components and heating surface of the boiler are improved. Compared to new boiler design, metal consumption during retrofitting is decreased by 500 tons. The
142
Fuel and Energy Abstracts
March 1999
99101411 section
Heat transfer assessment of a boiler convective
Azevedo, J. L. T. et al. New Dev. Heat Exch., (Sel. Pap. Semin.], 1993, 117129. Edited by Afgan, N. H., Gordon & Breach, Amsterdam, the Netherlands. _ The present work is concerned with the convective section of a coal-fired boiler and the on-line monitoring of the heat transfer capacity of the heat exchangers in it. The developed monitoring system performs mass and energy balances with available values from the process computer allowing the calculation of the heat transfer coefficients. The system installed at the boiler was assembled in order to assist the operators in the decision procedure of the soot blowing operations. In the present work the global heat exchange coefficients from each individual exchanger is assessed, showing the degradation along time due to fouling. The temporal evolution of the boiler efficiency is analysed using this data for different sequences of soot blowing operations.