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Experimental study of the solid circulation rate in a pressurized circulating fluidized bed 被引量:1
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作者 Jinding Hu Daoyin Liu +2 位作者 Heng Li Cai Liang Xiaoping Chen 《Particuology》 SCIE EI CAS CSCD 2021年第3期207-214,共8页
The solid circulation rate is essential for design of pressurized circulating fluidized beds(PCFBs).With increasing pressure from atmospheric pressure to a few bars,the gas density linearly increases with the pressure... The solid circulation rate is essential for design of pressurized circulating fluidized beds(PCFBs).With increasing pressure from atmospheric pressure to a few bars,the gas density linearly increases with the pressure,which affects the gas-solid flow characteristics.In this work,experiments were performed at room temperature in a cold PCFB apparatus with a riser of 3.3 m in height and 0.05 m in diameter.The solid circulation rate was studied from 20 to 80 kg/(m^(2)·s)under various conditions with increasing pressure from 0.1 to 0.6 MPa and fluidizing gas velocity from around 1.5 to 8.0 m/s for different Geldart B group particles.Most of the conditions were in the flow regimes of core-annulus flow(CAF)only and CAF with a turbulent fluidized bed at the bottom.The trend of the apparent slip factor with the dimensionless slip velocity was similar at different pressures and for different average particle sizes,and it converged to an exponential function.An empirical equation was obtained by fitting the solid circulation rate with the operating parameters(particle transport velocity,particle volume fraction,Archimedes number,and Froude number),which is helpful for design and operation of PCFBs. 展开更多
关键词 Pressurized Circulating fluidized bed Solid circulation rate Particle volume fraction Gas-solid slip velocity
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Solids flow characteristics and circulation rate in an internally circulating fluidized bed
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作者 Jinding Hu Daoyin Liu +3 位作者 Cai Liang Jiliang Ma Xiaoping Chen Tao Zhang 《Particuology》 SCIE EI CAS CSCD 2021年第1期69-77,共9页
Internally circulating fluidized beds(ICFBs)enable effective control of the reactions and heat distribution in reactors.The ICFB contains two or more connected fluidized regions with different gas velocities to promot... Internally circulating fluidized beds(ICFBs)enable effective control of the reactions and heat distribution in reactors.The ICFB contains two or more connected fluidized regions with different gas velocities to promote controlled solid circulation.The control of solid circulation rate(G_(0))is a critical factor.We recorded single particle trajectories by tracing a fluorescent particle,based on which particle flow behaviors were analyzed in different regions.G_(0)was obtained for a wide range of operating parameters.An increase in gas velocity in the down-and upflow beds shortened the particle circulation time in both beds and G_(0)increased significantly.As the static bed height increased,the differential pressure on both sides of the circulation port increased,which resulted in an increase in the solid circulation rate.As the orifice area increased,the flow resistance through the orifice decreased and thus the solid circulation rate increased.G_(0)increased with the decrease in particle size.The gas velocity in the upflowing bed and orifice area was the most important parameter to control the solid circulation rate.G_(0)was compared with the experimental measurements in literature and predictions using the correlation based on Bernoulli’s equation,and they agreed well. 展开更多
关键词 Internally CIRCULATING Fluidized bed Particle tracing Solid circulation rate
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Study on Influencing Factors of Methane Production Efficiency of Microbial Electrolytic Cell with CO_(2) as Carbon Source
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作者 Qifen Li Yuanbo Hou +2 位作者 Yongwen Yang Liting Zhang Xiaoxiao Yan 《Journal of Renewable Materials》 EI 2023年第8期3333-3350,共18页
Reducing CO_(2) to produce methane through microbial electrolytic cell(MEC)is one of the important methods of CO_(2) resource utilization.In view of the problem of low methanogenesis rate and weak CO_(2) conversion ra... Reducing CO_(2) to produce methane through microbial electrolytic cell(MEC)is one of the important methods of CO_(2) resource utilization.In view of the problem of low methanogenesis rate and weak CO_(2) conversion rate in the reduction process,theflowfield environment of the cathode chamber is changed by changing the upper gas cir-culation rate and the lower liquid circulation rate of the cathode chamber to explore the impact on the reactor startup and operation and products.The results showed that under certain conditions,the CO_(2) consumption and methane production rate could be increased by changing the upper gas recirculation rate alone,but the increase effect was not obvious,but the by-product hydrogen production decreased significantly.Changing the lower liquid circulation rate alone can effectively promote the growth of biofilm,and change the properties of biofilm at the later stage of the experiment,with the peak current density increased by 16%;The methanogenic rate decreased from the peak value of 0.561 to 0.3 mmol/d,and the CO_(2) consumption did not change signifi-cantly,which indicated that CO_(2) was converted into other organic substances instead of methane.The data after coupling the upper gas circulation rate with the lower liquid circulation rate is similar to that of only changing the lower liquid circulation rate,but changing the upper gas circulation rate can alleviate the decline of methane pro-duction rate caused by the change of biofilm properties,which not only improves the current density,but also increases the methane production rate by 0.05 mmol/d in the stable period.This study can provide theoretical and technical support for the industrial application scenario offlowfield regulation intervention of microbial elec-trolytic cell methanogenesis. 展开更多
关键词 BIOMETHANATION microbial electrolytic cell gas circulation rate liquid circulation rate methane production
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Multiobjective optimization scheme for industrial synthesis gas sweetening plant in GTL process 被引量:4
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作者 Alireza Behroozsarand Akbar Zamaniyan 《Journal of Natural Gas Chemistry》 EI CAS CSCD 2011年第1期99-109,共11页
In industrial amine plants the optimized operating conditions are obtained from the conclusion of occurred events and challenges that are normal in the working units. For the sake of reducing the costs, time consuming... In industrial amine plants the optimized operating conditions are obtained from the conclusion of occurred events and challenges that are normal in the working units. For the sake of reducing the costs, time consuming, and preventing unsuitable accidents, the optimization could be performed by a computer program. In this paper, simulation and parameter analysis of amine plant is performed at first. The optimization of this unit is studied using Non-Dominated Sorting Genetic Algorithm-II in order to produce sweet gas with CO 2 mole percentage less than 2.0% and H 2 S concentration less than 10 ppm for application in Fischer-Tropsch synthesis. The simulation of the plant in HYSYS v.3.1 software has been linked with MATLAB code for real-parameter NSGA-II to simulate and optimize the amine process. Three scenarios are selected to cover the effect of (DEA/MDEA) mass composition percent ratio at amine solution on objective functions. Results show that sour gas temperature and pressure of 33.98 ? C and 14.96 bar, DEA/CO 2 molar flow ratio of 12.58, regeneration gas temperature and pressure of 94.92 ? C and 3.0 bar, regenerator pressure of 1.53 bar, and ratio of DEA/MDEA = 20%/10% are the best values for minimizing plant energy consumption, amine circulation rate, and carbon dioxide recovery. 展开更多
关键词 amine plant multiobjective optimization Non-Dominated Sorting Genetic Algorithm amine circulation rate
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Heat Transfer in a Liquid-Solid Circulating Fluidized Bed Reactor with Low Surface Tension Media 被引量:2
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作者 H.R.Jin H.Lim +2 位作者 D.H.Lim Y.Kang Ki-Won Jun 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2013年第8期844-849,共6页
Heat transfer characteristics between the immersed heater and the bed content were studied in the riser of a liquid-solid circulating fluidized bed, whose diameter and height were 0.102 m (ID) and 2.5 m, respectively.... Heat transfer characteristics between the immersed heater and the bed content were studied in the riser of a liquid-solid circulating fluidized bed, whose diameter and height were 0.102 m (ID) and 2.5 m, respectively. Effects of liquid velocity, particle size, surface tension of liquid phase and solid circulation rate on the overall heat transfer coefficient were examined. The heat transfer coefficient increased with increasing particle size or solid circulation rate due to the higher potential of particles to contact with the heater surface and promote turbulence near the heater surface. The value of heat transfer coefficient increased gradually with increase in the surface tension of liquid phase, due to the slight increase of solid holdup. The heat transfer coefficient increased with the liquid velocity even in the higher range, due to the solid circulation prevented the decrease in solid holdup, in contrast to that in the conventional liquid-solid fluidized beds. The values of heat transfer coefficient were well correlated in terms of dimensionless groups as well as operating variables. 展开更多
关键词 heat transfer coefficient liquid-solid circulating fluidized bed liquid surface tension solid circulation rate particle size
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Modelling Effect of Circulation Flow Rate on Inclusion Removal in RH Degasser 被引量:2
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作者 Shu-guo ZHENG Miao-yong ZHU 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2016年第12期1243-1248,共6页
Based on the similarity principles, a 1 : 7 scale physical model was established to study the behavior of molten steel flow and inclusion removal in a 145 t Rheinsahl-Heraeus (RH) degasser. On the basis of the quan... Based on the similarity principles, a 1 : 7 scale physical model was established to study the behavior of molten steel flow and inclusion removal in a 145 t Rheinsahl-Heraeus (RH) degasser. On the basis of the quantitative measurements of the circulation flow rate and inclusion removal under various lifting gas flow rates, the effect of circulation flow rate on inclusion removal was investigated in the RH degasser. The inclusion removal rate shows the trend of first increase and then decrease twice with increasing the circulation flow rate when the circulation flow rates are smaller than 104.7 L/min. Whereas, the inclusion removal rate increases again with the further increase in circu- lation flow rate when the circulation flow rate is larger than 104.7 L/min. At lower circulation flow rates, inclusions are mainly removed by Stokes flotation to the slag/steel interface after inclusions are transferred near the slag/steel interface by the circulation flow. At higher circulation flow rates, the collision and aggregation of inclusions improves the inclusion removal efficiency. With the further increase in the circulation flow rate, inclusions are mainly removed by following the turbulent fluctuation (turbulent diffusion) to the slag/steel interface after inclusions are transferred near the slag/steel interface by the circulation flow. 展开更多
关键词 RH degasser lifting gas flow rate circulation flow rate inclusion removal physical modelling
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Effect of gas blowing nozzle angle on multiphase flow and mass transfer during RH refining process 被引量:2
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作者 Jiahao Wang Peiyuan Ni +2 位作者 Chao Chen Mikael Ersson Ying Li 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2023年第5期844-856,共13页
A three-dimensional mathematical model was developed to investigate the effect of gas blowing nozzle angles on multiphase flow,circulation flow rate,and mixing time during Ruhrstahl-Heraeus(RH) refining process.Also,a... A three-dimensional mathematical model was developed to investigate the effect of gas blowing nozzle angles on multiphase flow,circulation flow rate,and mixing time during Ruhrstahl-Heraeus(RH) refining process.Also,a water model with a geometric scale of 1:4 from an industrial RH furnace of 260 t was built up,and measurements were carried out to validate the mathematical model.The results show that,with a conventional gas blowing nozzle and the total gas flow rate of 40 L·min^(-1),the mixing time predicted by the mathematical model agrees well with the measured values.The deviations between the model predictions and the measured values are in the range of about 1.3%–7.3% at the selected three monitoring locations,where the mixing time was defined as the required time when the dimensionless concentration is within 3% deviation from the bath averaged value.In addition,the circulation flow rate was 9 kg·s^(-1).When the gas blowing nozzle was horizontally rotated by either 30° or 45°,the circulation flow rate was found to be increased by about 15% compared to a conventional nozzle,due to the rotational flow formed in the up-snorkel.Furthermore,the mixing time at the monitoring point 1,2,and 3 was shortened by around 21.3%,28.2%,and 12.3%,respectively.With the nozzle angle of 30° and 45°,the averaged residence time of 128 bubbles in liquid was increased by around 33.3%. 展开更多
关键词 Ruhrstahl-Heraeus refining gas blowing nozzle angle circulation flow rate mixing time multiphase flow
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Relationship between heart rate variability and posterior circulation cerebral infarction and its value in prognosis prediction
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作者 巩莉 《China Medical Abstracts(Internal Medicine)》 2017年第1期60-61,共2页
Objective To investigate the characteristic of heart rate variability(HRV)changes in patients with posteriorcirculation cerebral infarction and its value in prognosis prediction.Methods Fifty-four cases continuously d... Objective To investigate the characteristic of heart rate variability(HRV)changes in patients with posteriorcirculation cerebral infarction and its value in prognosis prediction.Methods Fifty-four cases continuously diagnosed with acute posterior circulation cerebral infarction from March 2015 to November 2015 in the Department 展开更多
关键词 SDANN SDNN HF LF Relationship between heart rate variability and posterior circulation cerebral infarction and its value in prognosis prediction HRV
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Gas-solid Flow Characteristics in High-density CFB 被引量:2
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作者 Xue-yao Wang Bao-guo Fan +2 位作者 Sheng-dian Wang Xiang Xu Yun-han Xiao 《Journal of Thermal Science》 SCIE EI CAS CSCD 2012年第4期354-358,共5页
The gas-solid flow characteristics in the riser of a high density CFB of square (0.27 m×0.27 m×10.4 m) or circu-lar (? 0.187m×10.4 m) cross section, using Geldart B particles (quartz sand), was investig... The gas-solid flow characteristics in the riser of a high density CFB of square (0.27 m×0.27 m×10.4 m) or circu-lar (? 0.187m×10.4 m) cross section, using Geldart B particles (quartz sand), was investigated experimentally. The influence of riser structure on the hydrodynamic behaviors of a high-density circulating fluidized bed was investigated. The solid circulation rate was up to 321 kg/(m2s) with the circular cross-section under the operating conditions of the main bed air velocity 12.1 m/s and loosen wind and back-feed wind flow 25.1 m3/h. Different operating conditions on realizing high density circulation was analyzed, while both solids circulation rate and particle holdup depended highly on operating conditions. The circulating gas-solid flow was accompanied by an evidently-dense character in the riser's bottom zone and became fully developed in the middle and upper zones. 展开更多
关键词 HDCFB gas-solid flow solids circulation rate
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Hydrodynamic performance of spouted beds with different types of draft tubes 被引量:6
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作者 Hiroshi Nagashima Kazumi Suzukawa Toshifumi Ishikura 《Particuology》 SCIE EI CAS CSCD 2013年第5期475-482,共8页
Hydrodynamic performance of spouted beds with four different types of draft tubes has been investigated experimentally. In this work, irregular and angular particles were used as the spouting solids and the results we... Hydrodynamic performance of spouted beds with four different types of draft tubes has been investigated experimentally. In this work, irregular and angular particles were used as the spouting solids and the results were compared with those of the previous work in which regular and round particles had been used. It was found that the conical-cylindrical porous draft tube was the best option for solid-gas contact and solids circulation as in the case of round particles. Moreover, by using conical-cylindrical porous draft tube, the gas flow rate through the annulus reached 65-70%, equal to the level of a conventional spouted bed. 展开更多
关键词 Spouted bedConical-cylindrical porous draft tubeAngular sandGas-solid contactSolids circulation rate
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Hydrodynamic behavior of an internally circulating fluidized bed with tubular gas distributors 被引量:1
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作者 Wenli Zhao Tiefeng Wang +1 位作者 Chenjing Wang Zuoliang Sha 《Particuology》 SCIE EI CAS CSCD 2013年第6期664-672,共9页
To better understand the hydrodynamic behavior of an internally circulating fluidized bed, solids holdup in the down-comer (Eso), solids circulation rate (Gs) and gas bypassing fraction (from down-comer to riser ... To better understand the hydrodynamic behavior of an internally circulating fluidized bed, solids holdup in the down-comer (Eso), solids circulation rate (Gs) and gas bypassing fraction (from down-comer to riser y^R, and from riser to down-comer yRD) were experimentally studied. The effects of gas velocities in the riser and in the down-comer (UR and UD), orifice diameter in the draft tube (dor), and draft tube height (HR) were investigated. Experimental results showed that increase of gas velocities led to increase in Gs and yDR, and slight decrease in yeD. Larger orifice diameter on the draft tube led to higher 8sD, Gs and yDR, but had insignificant influence on YRD. with increasing draft tube height, both Gs and YDR first increased and then decreased, while yRD first decreased and then increased. Proposed correlations for predicting the hydrodynamic parameters agreed reasonably well with experimental values. 展开更多
关键词 Internally circulating fluidized bed Solids holdup Solids circulation rate Gas bypassing fraction
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Hydrodynamics in a new liquid–solid circulating conventional fluidized bed
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作者 Jingya Fu Xinyu Pan +3 位作者 Zeneng Sun Ruoting Liu Ying Zheng Jesse Zhu 《Particuology》 SCIE EI CAS CSCD 2022年第11期20-29,共10页
A new type of liquid–solid fluidized bed,named circulating conventional fluidized bed(CCFB)which operates below particle terminal velocity was proposed and experimentally studied.The hydrodynamic behavior was systema... A new type of liquid–solid fluidized bed,named circulating conventional fluidized bed(CCFB)which operates below particle terminal velocity was proposed and experimentally studied.The hydrodynamic behavior was systematically studied in a liquid–solid CCFB of 0.032 m I.D.and 4.5 m in height with five different types of particles.Liquid–solid fluidization with external particle circulation was experimentally realized below the particle terminal velocity.The axial distribution of local solids holdup was obtained and found to be fairly uniform in a wide range of liquid velocities and solids circulation rates.The average solids holdup is found to be significantly increased compared with conventional fluidization at similar conditions.The effect of particle properties and operating conditions on bed behavior was investigated as well.Results show that particles with higher terminal velocity have higher average solids holdup. 展开更多
关键词 Circulating conventional fluidized bed(CCFB) Solids holdup Solids circulation rate Superficial liquid velocity Particle properties Operating conditions
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Non-uniform distribution of gas-solid flow through six parallel cyclones in a CFB system: An experimental study 被引量:32
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作者 Xinglong Zhou Leming Cheng +2 位作者 Qinhui Wang Zhongyang Luo Kefa Cen 《Particuology》 SCIE EI CAS CSCD 2012年第2期170-175,共6页
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... 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. Measure- ments 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 veloc- ities. 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. 展开更多
关键词 Circulating fluidized bed600-MW CFBParallel cycloneSolid circulating rate
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