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| 1 | Non-uniform distribution of gas-solid flow through six parallel cyclones in a CFB system: An experimental study显示文摘In large-scale circulating fluidized bed (CFB) boilers, it is common to use multiple cyclones in parallel for the capture of solids, assuming that gas-solid flow to be the same in the cyclones. This article presents a study investigating gas-solid flow through six parallel cyclones in a CFB cold test rig. The six cyclones were located asymmetrically on the left and right walls of the riser. Solid volume fraction and particle velocity profiles at the riser outlets and in the horizontal ducts were measured using a fiber optical probe. Cyclone pressure drop and solid circulating rate were measured for each individual cyclone. Measurements showed good agreement as to the non-uniform distribution of the gas-solid flow, which occurred mainly across the three cyclones on one side: the middle cyclones on both sides had higher particle velocities. Conversely, the solid volume fractions, solid fluxes and solid circulating rates of the middle cyclones were lower than those of the other four cyclones. The apparent reason for the flow non-uniformity among the cyclones is the significant flow non-uniformity at the riser outlets. Under typical operating conditions, the solid volume fractions at the riser outlets had a deviation of up to 26% whereas the solid circulating rates at the stand pipes, 7%. These results are consistent with most other studies in the literature. | Xinglong Zhou Leming Cheng Qinhui Wang Zhongyang Luo Kefa Cen | 2012 | Particuology2012,10,2: | 31 |
| 2 | A comprehensive CFD combustion model for supercritical CFB boilers显示文摘A combustion model of a large-scale supercritical circulati ng fluidized bed (CFB) boiler was developed for comprehensive computational-fluid-dynamics analysis. The model incorporates gas-solid hydrodynamics, coal combustion, heat transfer on heat exchange surfaces in the furnace, and heat transfer between fumace and working medium in the heat transfer tubes. In simulating the dense and dilute phases in the fumace, the gas-solid hydrodynamics is based on the Euler-Euler model and energy-minimization multiscale drag model. Coal combustion entails evaporation, devolatilization, char combustion, gas homoge neous reaction, and pollutant emission. The coefficient ofheat transfer between gas-solid and the waterwall is estimated using the cluster renewal model, and for radiation, the discrete ordinate model is used. Moreover, thermohydraulic processes in the membrane wall are also in eluded in the heat transfer process. The model was successfully applied in simulations of a 350-MW supercritical CFB boiler. Detailed distributions of solids concentration, oxygen, heat flux, and working medium temperature in the boiler furnace are presented. | Linjie Xu Leming Cheng JieqiangJi Qinhui Wang Mengxiang Fang | 2019 | Particuology2019,17,2: | 5 |
| 3 | Predictions of NOx/N2O emissions from an ultra-supercritical CFB boiler using a 2-D comprehensive CFD combustion model显示文摘NOx and N2O emissions from an ultra-supercritical circulating fluidized bed(CFB)boiler were predicted using a two dimensional(2-D)comprehensive computational fluid dynamics(CFD)combustion model.This model was developed from a three dimensional model for a supercritical CFB boiler previously constructed by our group.Based on an analysis of the NOx and N2O conversion processes in a CFB boiler,the primary formation and destruction reactions were introduced into the 2-D model and coupled.The resulting model was validated using data from the Baima 600 MW supercritical CFB boiler,and then applied to a 660 MW ultra-supercritical CFB boiler.The effects of excess air,the secondary air(SA)to(primary air(PA)plus SA)ratio and the SA injection height on NOx and N2O emissions were investigated.The results show that a higher excess air volume increases both NOx and N2O emissions,while increasing the SA/(PA+SA)ratio somewhat reduces both the NOx and N2O concentrations.On the basis of the results of this work,optimal locations for SA injection ports so as to lower NOx and N2O emissions are recommended. | Jieqiang Ji Leming Cheng Yangjun Wei Junfeng Wang Xinyu Gao Mengxiang Fang Qinhui Wang | 2020 | Particuology2020,18,2: | 4 |
| 4 | Anti-wear beam effects on gas-solid hydrodynamics in a circulating fluidized bed显示文摘Anti-wear beams installed on water walls of circulating fluidized bed(CFB) boilers are one of the most effective ways to protect against water-wall erosion.Beam effects from,for example,beam size and superficial gas velocity were investigated on gas-solid hydrodynamics in a CFB test rig using CFD simulations and experimental methods.The downward flow of the wall layer solids is observed to be disrupted by the beam but is then restored some distance further downstream.When falling solids from the wall layer hit the anti-wear beam,the velocity of the falling solids decreases rapidly.A fraction of the solids accumulates on the beam.Below the beams,the falling solids have reduced velocities but upward-moving solids were observed on the wall.The effect of the beam increases with width and superficial gas velocity.Wear occurs mainly above the beam and its variation with width is different above to below the beam.There is an optimum width that,when combined with beam height,results in less erosion. | Yunfei Xia Leming Cheng Chunjiang Yu Linjie Xu Qinhui Wang Mengxiang Fang | 2015 | Particuology2015,13,2: | 3 |
| 5 | Papillary fistulotomy vs conventional cannulation for endoscopic biliary access:A prospective randomized trial显示文摘AIM To compare the cannulation success, biochemical profile, and complications of the papillary fistulotomy technique vs catheter and guidewire standard access.METHODS From July 2010 to May 2017, patients were prospectively randomized into two groups: Cannulation with a catheter and guidewire(Group Ⅰ) and papillary fistulotomy(Group Ⅱ). Amylase, lipase and C-reactive protein at T0, as well as 12 h and 24 h after endoscopic retrograde cholangiopancreatography, and complications(pancreatitis, bleeding, perforation) were recorded.RESULTS We included 102 patients(66 females and 36 males, mean age 59.11 ± 18.7 years). Group Ⅰ and Group Ⅱ had 51 patients each. The successful cannulation rates were 76.5% and 100%, respectively(P = 0.0002). Twelve patients(23.5%) in Group Ⅰ had a difficult cannulation and underwent fistulotomy, which led to successful secondary biliary access(Failure Group). The complication rate was 13.7%(2 perforations and 5 mild pancreatitis) vs 2.0%(1 patient with perforation and pancreatitis) in Groups Ⅰ and Ⅱ, respectively(P = 0.0597). CONCLUSION Papillary fistulotomy was more effective than guidewire cannulation, and it was associated with a lower profile of amylase and lipase. Complications were similar in both groups. | Carlos Kiyoshi Furuya Paulo Sakai Fabio Ramalho Tavares Marinho Jose Pinhata Otoch Spencer Cheng Lívia Lemes Prudencio Eduardo Guimaraes Hourneaux de Moura Everson Luiz de Almeida Artifon | 2018 | World Journal of Gastroenterology2018,24,16: | 2 |
| 6 | Problems with Circulating Fluidized Bed (CFB)Boilers in Chi- na and Their Solutions 显示文摘 | CHENG Leming ZHANG Junchun LUO Zhongyang | 2011 | VGB Powertech2011,91,10: | 1 |
| 7 | Current status of the development of premixed combustion in porous media显示文摘 | Cheng Leming Wang Enyu Luo Zhongyang | 2003 | Power System Engineering2003,19,1: | 1 |
| 8 | Secondary Air Numerical Simulation on Range in a 300 MW Single Furnace Hearth of Circulating Fluidized Bed Boiler 显示文摘 | ZHENG Chenghang CHENG Leming ZHOU Xinglong | 2009 | Power Engineering2009,29,9: | 1 |
| 9 | Effect of characteriste of sorbents on their sulfur capture capability at a fluidized bed condition显示文摘 | Cheng Leming Chen Bo Liu Ni | 2004 | Fuel2004,83,: | 1 |
| 10 | Hydrogen Production from Lignite via Supercritical Water in Flow-type Reactor 显示文摘 | Zhang Rong Jiang Wei Cheng Leming | 2010 | International Journal of Hydrogen Energy2010,35,11: | 1 |
| 11 | Numerical Studies on Flame Inclination in Porous Media Combustors 显示文摘 | ZHENG Chenghang CHENG Leming Saveliev A | 2011 | International Journal of Heat and Mass Transfer2011,54,1516: | 1 |
| 12 | Numerical Studies on the Inclined Flame Front Break of Filtration Combustion in Porous Media 显示文摘 | ZHANG Junchun CHENG Leming ZHENG Chenghang | 2013 | En- ergy and Fuels2013,27,8: | 1 |
| 13 | Numerical Studies on Flame Inclination in Porous Me- dia Combustor 显示文摘 | ZHENG Chenghang CHENG Leming Alexei Saveliev | 2011 | International Journal of Heat and Mass Transfer2011,54,1516: | 1 |
| 14 | Effect of temperature and pressure on the mineralogical and fusion characteristics of Jincheng coal ash in simulated combustion and gasification environments显示文摘 | Nijie Jing Qinhui Wang Leming Cheng Zhongyang Luo Kefa Cen Dongke Zhang | 2013 | Fuel2013,,: | 1 |
| 15 | Effect of pressure on loop seal operation for a pressurized circulating fluidized bed显示文摘 | Cheng Leming Basu Prabir | 1999 | Powder Technology1999,103,3: | 1 |
| 16 | Pyrolysis of a low-rank coal in sub- and supercritical water 显示文摘 | CHENG Leming ZHANG Rong BI Jicheng | 2004 | Fuel Processing Technology2004,85,810: | 1 |
| 17 | Filtration combustion characteristicsof low calorific gas in SIC foams 显示文摘 | Zheng CKenghuang? Cheng Leming Li Tao LuoZhongyang Cen Kefa | 2010 | Fuel2010,89,: | 1 |
| 18 | Current Status of the Development of Premixed Combustion in Porous Media 显示文摘 | CHENG Leming WANG Enyu LO Zhongyang | 2003 | Power System Engineering2003,19,1: | 1 |
| 19 | Pyrolysis of a low-rank coal in sub-and supercritical water显示文摘 | Cheng Leming Zhang rong Bi Jicheng | 2004 | Fuel Processing Technology2004,85,810: | 1 |
| 20 | Pyrolysis of Low Rank Coal in Sub-and Supercritical Water显示文摘 | Cheng Leming Zhang Rong Bi Jicheng | 2004 | Fuel Processing Technology2004,,85: | 1 |