The Experts below are selected from a list of 3462 Experts worldwide ranked by ideXlab platform
Fangqin Cheng - One of the best experts on this subject based on the ideXlab platform.
-
numerical simulation and cold experimental research of a Low nox combustion technology for pulverized Low Volatile Coal
Applied Thermal Engineering, 2017Co-Authors: Jing Wang, Kailiang Zheng, Baofeng Wang, Ravinder Singh, Fangqin ChengAbstract:Abstract Large quantities of Low-Volatile Coal are utilized in power plants throughout China. With increasingly stringent environmental regulations, it is important to develop and deploy Low-NOx combustion technologies for pulverized Coal boilers burning Low-Volatile Coal. The objective of this study was to investigate a novel decoupling combustion system for Low-Volatile Coal via experiments and computational fluid dynamics (CFD). The combustion system includes horizontal fuel-rich/lean Low-NOx burners (LNB) and the associated air distribution system for a polygonal tangentially fired boiler (PTFB). The effects of Coal particle diameter and Coal feeding rate on the gas/particle fLow characteristics of the burner, and the cold state aerodynamic field of the PTFB were analyzed in detail. The structural design of the LNB results in advantageous gas/particle fLow characteristics and the PTFB improved the distribution of the fLow field. The CFD models and simulation results were validated by comparing with those of cold experiments data. The simulation results demonstrated that this Low-NOx combustion technology enhances staged combustion at different scales, which can reduce NOx generation significantly. In the industrial application on a 300 MW pulverized Coal boiler, installation of the LNBs improved the stability of Low-Volatile Coal combustion and reduced NOx emissions significantly. These research findings provide valuable guidance to the design of Low-NOx combustion system for pulverized Coal boilers using Low Volatile Coal.
Liuyun Li - One of the best experts on this subject based on the ideXlab platform.
-
Coal combustion under calcium looping process conditions
Fuel, 2014Co-Authors: Takayuki Takahashi, Hiroko Narisawa, Ayato Yoshizawa, Liuyun LiAbstract:Abstract Coal of three kinds was burned in an oxygen-enriched atmosphere using a twin-fluidized bed solid circulation system under conditions of the Calcium Looping Process. This twin-fluidized bed system comprised a fast bed regenerator (calciner), into which fuel and oxygen-enriched gas were fed, and a bubbling bed absorber (carbonator), into which air was fed. Inert quartz sand was used as the bed material to evaluate the Coal combustion behavior, including char transportation from regenerator to absorber and formation of CO and CO 2 there. First, the circulation rate and the residence time of solids in the regenerator (calciner) were measured to determine the suitable operation conditions. The effect of gas feed staging to the regenerator on the solid residence time was evaluated. By reducing the ratio of the primary gas feed rate to total gas feed rate to 0.5, average solid residence time of about 40 s was attained. Under this gas-feed condition, Coal combustion experiments were conducted. Effects of Volatile matter content of Coal on CO and CO 2 formation in the absorber and NO x emissions from the regenerator were investigated. High-Volatile matter Coal was found to be favorable to reduce CO and CO 2 formation in the absorber, but conversion of the fuel-N to NO x of high-Volatile matter Coal was higher than that from Low-Volatile Coal.
-
role of char in nox formation during Coal combustion at a regenerator temperature of calcium looping process
Fuel, 2014Co-Authors: Takanori Higuchi, Ayato Yoshizawa, Liuyun LiAbstract:Abstract Coal of three kinds was burned in an oxygen-enriched atmosphere using two types of reactor both of which had the same fast fluidized bed for Coal combustion. One was a dual-fluidized bed system (dual-FB), simulating Calcium Looping process comprised a fast fluidized bed regenerator and a bubbling bed carbonator. The other was a conventional single circulating fluidized bed combustor (single-CFBC). In both systems, Coal combustion in oxygen-enriched atmosphere was carried out under regenerator temperature condition of Calcium Looping process. Inert quartz sand was used as the bed material to evaluate carbon consumption in the carbonator of dual-FB. Formation of NOx in the fast fluidized beds was measured for both reactors. For dual-FB, formation of CO and CO2 in the carbonator was also measured. High-Volatile matter Coal was found to be favorable to reduce CO and CO2 formation in the carbonator, but conversion of the fuel-N to NOx of high-Volatile matter Coal was higher than that from Low-Volatile Coal. The emissions of NOx from single-CFBC were less than those from the regenerator of dual-FB under the same combustion condition. From the emissions of CO and CO2 from the carbonator, the decrease in char combustion in the regenerator of dual-FB was calculated. An empirical relationship between the conversion of fuel-N to NOx in the fast fluidized bed and the ratio of fixed carbon to Volatile matter of the fuel was obtained.
Xiqian Zhang - One of the best experts on this subject based on the ideXlab platform.
-
effect of outer secondary air vane angle on the fLow and combustion characteristics and nox formation of the swirl burner in a 300 mw Low Volatile Coal fired boiler with deep air staging
Journal of The Energy Institute, 2017Co-Authors: Zhichao Chen, Bingkun Jiang, Rui Sun, Qunyi Zhu, Xiqian ZhangAbstract:Abstract Small-scale laboratory experiments of airfLow through a single burner model and industrial-scale experiments on the centrally fuel-rich, Low NO x swirl burner on a 300-MW wall-fired subcritical boiler burning Low-Volatile Coal under deep air staging were performed. The aerodynamic characteristics, flue gas temperature, and gas concentrations were measured for various vane angles of outer secondary air in the burner nozzle region. The results show that a stable, symmetric central reverse-fLow zone forms close to the exit of the burner nozzle region under deep air staging. With decreasing vane angle, i) the maximum axial, radial, and tangential velocities and swirl intensity of the airstream increase; ii) the decaying rate of velocity increases between X / D = 0 and X / D = 0.8; iii) the maximum diameter, length, and the jet divergence angle of the central reverse-fLow zone increase; and iv) the relative reverse-fLow rate increases. While the primary air concentration decreases slightly, the maximum primary air concentration decreases rapidly with decreasing vane angle. In contrast, the maximum axial relative mixing rate increases in the initial stage along the airstream direction. A decrease in vane angle increases the flue gas temperature, the rate of increase indicating a closer ignition position of the anthracite and lean Coal along the airstream direction of the burner. The O 2 consumption rate and NO x formation rate increase in the initial stage of combustion, whereas in the later stage the CO concentration increases notably and the O 2 concentration remains almost constant beLow 1%. The CO concentration can exceed 20,000 ppm, which restrains the NO x formation and reduces the NO x concentration notably, but beyond X′ = 0.8 m, the NO x concentration remains almost constant. The flue gas temperature varies slightly for different vane angles in the side-wall region. The O 2 concentration exceeds 4% near the location of the water-cooled wall. The O 2 concentrations are beLow 2% and the CO concentrations are above 5000 ppm along the radial direction 1.8375 m ≤ R′ ≤2.3375 m from the centerline of the burner in the side-wall region. With decreasing vane angle, the CO concentration increases while the NO x concentration decreases.
-
effect of secondary air mass fLow rate on the airfLow and combustion characteristics and nox formation of the Low Volatile Coal fired swirl burner
Asia-Pacific Journal of Chemical Engineering, 2015Co-Authors: Bingkun Jiang, Zhichao Chen, Xiqian ZhangAbstract:Laboratory experiments and industrial-scale experiments on 300-MW Low-Volatile Coal-fired boiler were performed under deep air staging. Aerodynamic characteristics, gas temperature and concentrations, furnace temperature, and boiler efficiency were measured for various secondary air mass fLow rates. Under deep air staging, a steady central recirculation zone forms near the burner nozzle. With a decreasing fLow rate, the swirl intensity and maximum axial, radial, and tangential velocities decrease; between X/D = 0–0.8, the velocity decay rate decreases, and the relative reverse fLow rate decreases. In the early stage, the maximum axial mixing rate decreases; the primary air concentration increases slightly. A decrease in secondary air-box damper opening decreases the gas temperature and its increasing rate, generating a farther ignition position. In the initial stage, the O2 consumption rate and CO concentration increase, while the NOx concentration decreases. In the later stage, O2 concentration remains almost constant beLow 2%, and the CO concentrations exceed 15 000 ppm, which restrain NOx formation notably. Near the water-cooled wall, flue gas temperature varies slightly, and O2 concentration exceeds 3%. Along radial direction 1.5364 ≤ R0/D0 ≤ 1.8708, the O2 concentrations are beLow 2%, and CO concentrations exceed 6000 ppm. A decreasing damper opening decreases furnace temperature in the primary combustion zone slightly. NOx emission decreases from 833.4 to 769.9 mg/m3 (6% O2), unburnt carbon increases from 5.18% to 6.84%, and boiler efficiency decreases from 91.53% to 90.99%. Copyright © 2015 Curtin University of Technology and John Wiley & Sons, Ltd.
Jing Wang - One of the best experts on this subject based on the ideXlab platform.
-
numerical simulation and cold experimental research of a Low nox combustion technology for pulverized Low Volatile Coal
Applied Thermal Engineering, 2017Co-Authors: Jing Wang, Kailiang Zheng, Baofeng Wang, Ravinder Singh, Fangqin ChengAbstract:Abstract Large quantities of Low-Volatile Coal are utilized in power plants throughout China. With increasingly stringent environmental regulations, it is important to develop and deploy Low-NOx combustion technologies for pulverized Coal boilers burning Low-Volatile Coal. The objective of this study was to investigate a novel decoupling combustion system for Low-Volatile Coal via experiments and computational fluid dynamics (CFD). The combustion system includes horizontal fuel-rich/lean Low-NOx burners (LNB) and the associated air distribution system for a polygonal tangentially fired boiler (PTFB). The effects of Coal particle diameter and Coal feeding rate on the gas/particle fLow characteristics of the burner, and the cold state aerodynamic field of the PTFB were analyzed in detail. The structural design of the LNB results in advantageous gas/particle fLow characteristics and the PTFB improved the distribution of the fLow field. The CFD models and simulation results were validated by comparing with those of cold experiments data. The simulation results demonstrated that this Low-NOx combustion technology enhances staged combustion at different scales, which can reduce NOx generation significantly. In the industrial application on a 300 MW pulverized Coal boiler, installation of the LNBs improved the stability of Low-Volatile Coal combustion and reduced NOx emissions significantly. These research findings provide valuable guidance to the design of Low-NOx combustion system for pulverized Coal boilers using Low Volatile Coal.
Qunwu Huang - One of the best experts on this subject based on the ideXlab platform.
-
co pyrolysis characteristics and kinetics of Coal and plastic blends
Energy Conversion and Management, 2009Co-Authors: Limin Zhou, Taian Luo, Qunwu HuangAbstract:Abstract Co-pyrolysis behaviors of different plastics (high density polyethylene, Low density polyethylene and polypropylene), Low Volatile Coal (LVC) and their mixtures were investigated by TGA. Experiments were conducted under N 2 atmosphere at heating rate of 20 °C/min from room temperature to 750 °C. The results showed that the thermal degradation temperature range of plastic was 438–521 °C, while that of Coal (LVC) was 174–710 °C. Plastics showed similar pyrolysis characteristics due to similar chemical bonds in their molecular structures. The overlapping degradation temperature interval between Coal and plastic provide an opportunity for free radicals from Coal pyrolysis to participate in the reactions of plastic decomposition. The difference of weight loss percent (Δ W ) between experimental and theoretical ones, calculated as an algebraic sum of those from each separated component, Δ W is 2.0–2.7% at the pyrolysis temperature higher than 530 °C, which indicates that the synergistic effect during pyrolysis occurs mainly in the high temperature region. The kinetic studies were performed according to Coats and Redfern method for first-order reaction. It was found that for plastics (HDPE, LDPE and PP), the pyrolysis process can be described by one first-order reaction. However, for LVC and LVC/plastic blends, this process can be described by three and four consecutive first-order reactions, respectively. The estimated kinetic parameters viz., activation energies and pre-exponential factors for Coal, plastic and their blends, were found to be in the range of 35.7–572.8 kJ/mol and 27–1.7 × 10 38 min −1 , respectively.
-
thermogravimetric analysis and kinetics of Coal plastic blends during co pyrolysis in nitrogen atmosphere
Fuel Processing Technology, 2008Co-Authors: Junqing Cai, Limin Zhou, Yiping Wang, Qunwu HuangAbstract:Abstract Investigations into the co-pyrolytic behaviours of different plastics (high density polyethylene, Low density polyethylene and polypropylene), Low Volatile Coal and their blends with the addition of the plastic of 5 wt.% have been conducted using a thermogravimetric analyzer. The results indicated that plastic was decomposed in the temperature range 438–521 °C, while the thermal degradation temperature of Coal was 174–710 °C. The overlapping degradation temperature interval between Coal and plastic was favorable for hydrogen transfer from plastic to Coal. The difference of weight loss (▵ W ) between experimental and theoretical ones, calculated as an algebraic sum of those from each separated component, was 2.0–2.7% at 550–650 °C. These experimental results indicated a synergistic effect during plastic and Coal co-pyrolysis at the high temperature region. In addition, a kinetic analysis was performed to fit thermogavimetric data, the estimated kinetic parameters (activation energies and pre-exponential factors) for Coal, plastic and their blends, were found to be in the range of 35.7–572.8 kJ/mol and 27–1.7 × 10 38 min − 1 , respectively.
