The Experts below are selected from a list of 228 Experts worldwide ranked by ideXlab platform
Zhengqi Li - One of the best experts on this subject based on the ideXlab platform.
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secondary air distribution in a 600 mwe multi injection multi staging down fired Boiler a comprehensive study
Journal of The Energy Institute, 2020Co-Authors: Minhang Song, Lingyan Zeng, Yan Zhao, Zhengqi LiAbstract:Abstract Multi-injection multi-staging combustion technology was designed to provide high Boiler Efficiency together with low pollutant emissions when employing hard-to-burn coal, and showed good application prospects. In this technology, to achieve the first staged air and more flexible combustion regulation on the arches, the secondary air employs a more complicated distribution surrounding the coal/air flows. This design concept significantly affects the flow and combustion characteristics of the actual Boiler. Elucidating the underlying mechanisms by which the various secondary air parameters affect the Boiler operation requires a comprehensive analysis of the secondary air distribution on the arches. In this work, small-scale cold modeling tests combined with industrial-scale trials using two actual 600 MWe down-fired Boilers were conducted. The results show that the secondary air distribution can significantly affect the near-burner flow and mixing as well as the decay of the downward airflow velocity. High velocity secondary air, especially the secondary air surrounding the fuel-rich flow, evidently promotes the advanced mixing of fuel-rich and fuel-lean flows. Increasing the secondary air flux around the fuel-rich flow and raising the secondary air velocity decrease the pulverized coal heating rate, while a decreased inner secondary air velocity advances the coal ignition. Adjusting the secondary air also greatly affects the downward flame depth and the unburnt coal proportion in the near wall region of the furnace hopper, such that the flame kernel location and the temperatures near the hopper wall are modified. In addition, NOx formation can be accelerated by a high secondary air flux near the fuel-rich flow or a large contact area between the secondary air and the fuel-rich flow.
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effects of the inner secondary air damper opening on flow and combustion in a 600 mwe down fired Boiler incorporating multiple injection and multiple staging
Asia-Pacific Journal of Chemical Engineering, 2017Co-Authors: Minhang Song, Zhengqi Li, Lingyan Zeng, Zhichao Chen, Xiaoguang LiAbstract:Effects of adjusting the inner-secondary-air damper opening among 100%, 70%, and 50% on the flow, combustion, and NOx emissions of a 600-MWe down-fired Boiler incorporating multiple-injection and multiple-staging technology were investigated. Both 1 : 20-scale aerodynamic tests and industrial experiments were conducted. The small-scale tests showed that symmetric flow patterns formed in all cases, and the velocities of boundary and outer secondary air decayed more quickly than the velocity of inner secondary air. As the inner-secondary-air damper opening decreased from 100% to 50%, the average dimensionless depth of downward airflow reduced from 0.830 to 0.788 while the horizontal velocity in the recirculation zone increased. Industrial experiments demonstrated that, as the inner-secondary-air damper opening decreased from 100% to 50%, the heating rate of fuel-rich coal/air flow increased from 572 to 687°C/m, the corresponding ignition distance shortened from 1.36 to 1.11 m, and the hopper near-wall temperature decreased by approximately 50°C. Carbon in fly ash decreased from 7.31% to 6.93%, and NOx emissions rose from 343 to 371 ppm at 6% O2. The Boiler Efficiency improved from 89.78% to 89.92%. An inner-secondary-air damper opening of 70% is more reasonable than 50% and 100% considering the ignition distance, carbon in fly ash, and NOx emissions. Copyright © 2017 Curtin University of Technology and John Wiley & Sons, Ltd.
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influence of outer secondary air vane angle on combustion characteristics and nox emissions of a down fired pulverized coal 300 mwe utility Boiler
Fuel, 2010Co-Authors: Zhengqi Li, Xuehai Yang, Zhichao ChenAbstract:Abstract Industrial experiments were performed on a down-fired pulverized-coal 300 MWe utility Boiler with swirl burners. Gas temperature, concentrations of gas components (O 2 , CO, CO 2 and NO x ) in the burning region and carbon content in the fly ash were measured with outer secondary-air vane angles of 25°, 32.5° and 50°. Results indicate that with increasing vane angle, NO x emission and Boiler Efficiency decrease. Overall evaluation Boiler Efficiency and NO x emission, the vane angle of 32.5° is optimum. Using an IFA300 constant-temperature anemometer system, cold air experiments on a quarter-scaled burner model were also carried out to investigate the influence of various outer secondary-air vane angles on the flow characteristics in the burner nozzle region. No central recirculation zone appeared for vane angles of 25° and 32.5°. Most of the pulverized-coal was ignited in the external recirculation zone. For vane angles of 45° and 55°, a central recirculation zone could be observed, and air flow rigidity and axial velocities decreased rapidly.
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influence of staged air on airflow combustion characteristics and nox emissions of a down fired pulverized coal 300 mwe utility Boiler with direct flow split burners
Environmental Science & Technology, 2010Co-Authors: Zhengqi Li, Min Kuang, Jia Zhang, Lianjie Yang, Weiguang KongAbstract:Cold airflow experiments were conducted to investigate the aerodynamic field in a small-scale furnace of a down-fired pulverized-coal 300 MWe utility Boiler arranged with direct flow split burners enriched by cyclones. By increasing the staged-air ratio, a deflected flow field appeared in the lower furnace; larger staged-air ratios produced larger deflections. Industrial-sized experiments on a full-scale Boiler were also performed at different staged-air damper openings with measurements taken of gas temperatures in the burner region and near the right-side wall, wall heat fluxes, and gas components (O2, CO, and NOx) in the near-wall region. Combustion was unstable at staged-air damper openings below 30%. For openings of 30% and 40%, late ignition of the pulverized coal developed and large differences arose in gas temperatures and heat fluxes between the regions near the front and rear walls. In conjunction, carbon content in the fly ash was high and Boiler Efficiency was low with high NOx emission above ...
Zhichao Chen - One of the best experts on this subject based on the ideXlab platform.
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effects of the inner secondary air damper opening on flow and combustion in a 600 mwe down fired Boiler incorporating multiple injection and multiple staging
Asia-Pacific Journal of Chemical Engineering, 2017Co-Authors: Minhang Song, Zhengqi Li, Lingyan Zeng, Zhichao Chen, Xiaoguang LiAbstract:Effects of adjusting the inner-secondary-air damper opening among 100%, 70%, and 50% on the flow, combustion, and NOx emissions of a 600-MWe down-fired Boiler incorporating multiple-injection and multiple-staging technology were investigated. Both 1 : 20-scale aerodynamic tests and industrial experiments were conducted. The small-scale tests showed that symmetric flow patterns formed in all cases, and the velocities of boundary and outer secondary air decayed more quickly than the velocity of inner secondary air. As the inner-secondary-air damper opening decreased from 100% to 50%, the average dimensionless depth of downward airflow reduced from 0.830 to 0.788 while the horizontal velocity in the recirculation zone increased. Industrial experiments demonstrated that, as the inner-secondary-air damper opening decreased from 100% to 50%, the heating rate of fuel-rich coal/air flow increased from 572 to 687°C/m, the corresponding ignition distance shortened from 1.36 to 1.11 m, and the hopper near-wall temperature decreased by approximately 50°C. Carbon in fly ash decreased from 7.31% to 6.93%, and NOx emissions rose from 343 to 371 ppm at 6% O2. The Boiler Efficiency improved from 89.78% to 89.92%. An inner-secondary-air damper opening of 70% is more reasonable than 50% and 100% considering the ignition distance, carbon in fly ash, and NOx emissions. Copyright © 2017 Curtin University of Technology and John Wiley & Sons, Ltd.
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influence of outer secondary air vane angle on combustion characteristics and nox emissions of a down fired pulverized coal 300 mwe utility Boiler
Fuel, 2010Co-Authors: Zhengqi Li, Xuehai Yang, Zhichao ChenAbstract:Abstract Industrial experiments were performed on a down-fired pulverized-coal 300 MWe utility Boiler with swirl burners. Gas temperature, concentrations of gas components (O 2 , CO, CO 2 and NO x ) in the burning region and carbon content in the fly ash were measured with outer secondary-air vane angles of 25°, 32.5° and 50°. Results indicate that with increasing vane angle, NO x emission and Boiler Efficiency decrease. Overall evaluation Boiler Efficiency and NO x emission, the vane angle of 32.5° is optimum. Using an IFA300 constant-temperature anemometer system, cold air experiments on a quarter-scaled burner model were also carried out to investigate the influence of various outer secondary-air vane angles on the flow characteristics in the burner nozzle region. No central recirculation zone appeared for vane angles of 25° and 32.5°. Most of the pulverized-coal was ignited in the external recirculation zone. For vane angles of 45° and 55°, a central recirculation zone could be observed, and air flow rigidity and axial velocities decreased rapidly.
Antonio Lozano - One of the best experts on this subject based on the ideXlab platform.
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on the optimization of Boiler Efficiency using bagasse as fuel
Fuel, 2003Co-Authors: Jorge Arroso, Feli Arreras, H Amaveda, Antonio LozanoAbstract:The present investigation has been carried out in order to increase the Efficiency of the RETAL-type Boiler, used in the Cuban sugar mills. Test methods generally used in the evaluation process and further adjustment of the Boilers operation have been analyzed, pointing the attention on the importance of the stoichiometric ratio and steam power on the overall Efficiency. Important general rules have been extracted from the complete regular tests following ASME and GOST methodologies, and, as a result, a simplified test code has been obtained. Boiler design optimization has also been achieved determining the optimum waste heat recovery scheme from both, thermal and economical viewpoints. As a result, the optimal stack gas temperature has been calculated as well as the range of the optimal value for the excess air fraction. Their influence on the Efficiency has been analyzed and the total costs determined. Once the total costs are included in the analysis, the most efficient low-temperature heat recovery scheme results to be the combination of an economizer followed, in the direction of the exhaust gas flow, by an air heater.
Jorge Arroso - One of the best experts on this subject based on the ideXlab platform.
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on the optimization of Boiler Efficiency using bagasse as fuel
Fuel, 2003Co-Authors: Jorge Arroso, Feli Arreras, H Amaveda, Antonio LozanoAbstract:The present investigation has been carried out in order to increase the Efficiency of the RETAL-type Boiler, used in the Cuban sugar mills. Test methods generally used in the evaluation process and further adjustment of the Boilers operation have been analyzed, pointing the attention on the importance of the stoichiometric ratio and steam power on the overall Efficiency. Important general rules have been extracted from the complete regular tests following ASME and GOST methodologies, and, as a result, a simplified test code has been obtained. Boiler design optimization has also been achieved determining the optimum waste heat recovery scheme from both, thermal and economical viewpoints. As a result, the optimal stack gas temperature has been calculated as well as the range of the optimal value for the excess air fraction. Their influence on the Efficiency has been analyzed and the total costs determined. Once the total costs are included in the analysis, the most efficient low-temperature heat recovery scheme results to be the combination of an economizer followed, in the direction of the exhaust gas flow, by an air heater.
Wasakorn Treedet - One of the best experts on this subject based on the ideXlab platform.
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improvement of Boiler s Efficiency using heat recovery and automatic combustion control system
Energy Procedia, 2016Co-Authors: Ratchaphon Suntivarakorn, Wasakorn TreedetAbstract:Abstract This research was conducted to improve the Efficiency of a fire tube Boiler with a fixed gate and screw conveyor for feeding fuel. The Efficiency improvement was based on the use of flue gas heat for fuel drying, air preheating before combustion, and controlling amount of air for fuel combustion before entering the combustion chamber using the fuzzy logic control algorithm. The experimental result indicates that using heat recovery and fuel drying reduces 3%wt of fuel moisture content and Boiler Efficiency increases 0.41%. Preheating air means a 35 °C increase of temperature or a 0.72% increase of Boiler Efficiency. The average accuracy of air control is 89.15%, indicating a 4.34% increase of Boiler Efficiency. If the three systems are operated simultaneously, 5.15% increase of Boiler Efficiency will be achieved or 246.88 tons/year saving of fuel.