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Energy Efficiency Analysis of Oxy-Fuel Circulating Fluidized Bed Combustion System with High Oxygen Concentration

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Journal of Thermal Science 2023年第5期32卷 1737-1749页

作者： KONG Runjuan LI Wei wang haigang REN Qiangqiang Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

The low net efficiency of oxy-fuel circulating fluidized bed(CFB)combustion is mainly due to the addition of air separation unit(ASU)and carbon dioxide compression and purification unit(CPU).High oxygen concentration is one of the effective methods to improve the net efficiency of oxy-fuel combustion technology in *** this research,a series of calculation and simulation were carried out based on Aspen Plus platform to provide valuable information for further investigation on the CFB oxy-fuel combustion system with high oxygen concentration(40%,50%).A CFB oxy-fuel combustion system model with high oxygen concentration was established including ASU,CPU and CFB oxy-fuel combustion and heat exchange *** on the simulation data,energy and exergy efficiency were analyzed to obtain the following *** cross-sectional area of furnace and tail flue of 50%CFB oxy-fuel combustion boiler are 43%and 56%of the original size respectively,reducing the construction and investment cost *** the increase of oxygen concentration,the net efficiency of power generation increased significantly,reaching 24.85%and increasing by 6.09%under the condition of 50%oxy-fuel *** total exergy loss increases with the increase of oxygen *** addition,the exergy loss of radiation heat transfer is far higher than convection heat transfer.

关键词： circulating fluidized bed oxy-fuel combustion high oxygen concentration process simulation

The properties of flax fiber reinforced wood flour/high density polyethylene composites

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Journal of Forestry Research 2018年第2期29卷 524-531页

作者： Jingfa Zhang haigang wang Rongxian Ou Qingwen wang Key Laboratory of Bio-Based Material Science and Technology (Ministry of Education) Northeast Forestry University College of Materials and Energy South China Agricultural University

Flax fiber(FF) was used to reinforce wood flour/high density polyethylene composites(WF/PE).WF/PE particles were uniformly mixed with FF via high-speed mixing and then extruded with a single screw extruder to prepare FF reinforced WF/PE composites(FF/WF/PE).Mechanical testing,dynamic mechanical analysis,scanning electron microscopy(SEM),creep measurement and Torque rheology were used to characterize the resulting *** results indicate that the mechanical performance of the composites could be remarkably improved by adding a limited amount of *** flexural strength and modulus increased by 14.6 and 51.4%,respectively(FF content of 9 wt%),while the unnotched impact strength could be increased by 26.5%(FF content of12 wt%).The creep resistance and toughness of thecomposite was markedly improved without changing the plastic content of the composite material.

关键词： Wood-plastic composites Flax fiber Reinforcement Processing Mechanical property Creep resistance

Effects of pressure on flow characteristics in a pressurized circulating fluidized bed

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Particuology 2021年第6期19卷 16-23页

作者： Pengfei Dong Qiuya Tu haigang wang Zhiping Zhu Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing 10090China University of Chinese Academy of Sciences Beijing 100049China

The effects of operating pressure on the gas-solid flow characteristics in a pressurized circulating fluidized bed(CFB)gasification system were studied by experiment and *** operating pressure was found to increase the particle uniformity in the axial and radial *** and simulations both showed that as the operating pressure increased,the pressure drops along the riser height *** experimental pressure drops at the same locations decreased when the operating pressure increased,but the opposite trend was observed in the simulation results.A proper drag model must be developed for the accurate simulation of pressurized CFB operation,and the accuracy of electrical capacitance tomography(ECT)measurement and cross-correlation analysis should be improved for better prediction of the particle circulation flux.

关键词： Pressurized circulating fluidized bed Pressure effect Drag model Uniformity

Bubble behaviors of geldart B particle in a pseudo two-dimensional pressurized fluidized bed

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Particuology 2023年第8期79卷 121-132页

作者： Xiaoli Zhu Yibo Liu Yuehuan Li haigang wang Zhenbo wang College of New Energy China University of Petroleum(East China)Qingdao266580China Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing100190China

Pressurized fluidized beds have been developed in quite a few industrial applications because of intensified heat and mass transfer and chemical *** bubble behaviors under elevated pressure,strongly influencing the fluidization and reaction conversion of the whole system,are of great research *** this work,the bubble behaviors of Geldart B particle in a pseudo two-dimensional(2D)pressurized fluidized bed were experimentally studied based on digital image analysis *** effects of pressure and fluidization gas velocity on the general bubble behaviors(i.e.,size,shape and spatial distribution)and the dynamic characteristics,such as the time-evolution of voidage distribution and local flow regimes,were comprehensively *** show that increasing pressure re-duces the stability of bubbles and facilitates gas passing through the emulsion phase,resulting in the"smoother"fluidization state with smaller bubbles and declined bubble fraction and standard *** equivalent bubble diameter and bubble aspect ratio increase with the increasing gas velocity while decrease as pressure *** elevated pressure reduces bubbles extension in the vertical direction,prohibits the"short pass"of fluidization gas in large oblong bubbles/slugs and benefits the gas-solid *** flow regimes variation with gas velocity is affected by the elevated pressure,and demonstrates different features in different local positions of the bed.

关键词： Pressurized fluidizedbed Bubble behaviors Geldart Bparticle Local flowregimes Digital image analysis

Investigation of gas-solids flow hydrodynamics in a cold model of a dual fluidised bed gasifier using electrical capacitance tomography sensors

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Particuology 2020年第4期18卷 193-204页

作者： Zhan Luo Yonglei Lin Qiuya Tu Wuqiang Yang haigang wang Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China Department of Electrical and Electronic Engineering University of ManchesterManchesterM139PLUK

The flow characteristics of a dual fluidised bed gasifier(DFBG)are more complex than those of a single fluidised bed *** stable operation and appropriate control,a cold DFBG test facility with both an upper and a lower U-valve was built,and electrical capacitance tomography(ECT)sensors were installed with pressure transducers to investigate the effects of operating conditions on gas-solids flow *** operating parameters included gas velocities in the riser and in the bubbling fluidised bed,aeration velocity in the lower U-valve,bed material inventory,and particle *** is the first time that ECT was applied in different flow zones of a dual fluidised bed gasifier *** experimental results indicated that ECT in the recycle chamber could monitor the performance of the lower U-valve under different operating conditions for early detection of gas shortcut from the riser to the bubbling *** main flow regimes in the riser and the differences between the reactors were identified by two sets of ECT sensors with pressure ***,the effects of the operating conditions on the pressure drop in different parts of the DFBG was investigated.

关键词： Dual fluidised bed gasifier Hydrodynamics Electrical capacitance tomography Flow regime identification

Effect of an antioxidant on the life cycle of wood flour/polypropylene composites

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Journal of Forestry Research 2020年第4期31卷 1435-1443页

作者： haigang wang Jingfa Zhang Haitao Fu Weihong wang Qingwen wang Key Laboratory of Bio-Based Material Science and Technology(Ministry of Education) Northeast Forestry UniversityHarbin 150040People’s Republic of China College of Materials and Energy South China Agricultural UniversityGuangzhou 510642People’s Republic of China

This study assessed the life cycle of biocomposites with antioxidants by repeated *** effects of antioxidants on the life cycle of wood flour/polypropylene(PP)composites were determined by analyzing their mechanical and thermal *** composites were repeatedly processed for seven times with pelletizing and *** antioxidant,pentaerythritoltetrakys 3-(3,5-ditert-butyl-4-hydroxyphenyl)propionate,was *** mechanical strength of the biocomposites decreased after *** transformed infrared analysis showed that thermo-oxidative aging occurred during *** thermal performance of the resulting composites decreased because of *** flour/PP has a long lifetime and antioxidants can slow the thermo-oxidative and mechanical degradation during reprocessing.

关键词： Wood-plastic composites Polypropylene Reprocessing Antioxidant

Non-isothermal crystallization kinetics of wood-flour/polypropylene composites in the presence of b-nucleating agent

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Journal of Forestry Research 2016年第4期27卷 949-958页

作者： Lang Huang haigang wang Weihong wang Qingwen wang Yongming Song Key Laboratory of Bio-Based Material Science and Technology (Ministry of Education) Northeast Forestry University

The influence of aryl amide compounds（TMB）as b-nucleating agents, on the non-isothermal crystallization of a wood-flour/polypropylene composite（WF/PP）prepared by compression molding was investigated by wide-angle X-ray diffraction and differential scanning calorimetry. TMB was proved to be an effective b-crystalline nucleating agent for WF/PP. The DSC data showed that the crystallization peak temperature（Tp） increased and the half-time（t1/2） decreased with the addition of *** theoretical models were used to analyze the nonisothermal crystallization process. The modified Avrami method and Mo method successfully explained the nonisothermal crystallization behavior of PP and its composites. Their activation energies for non-isothermal crystallization were determined basing on the Kissinger method.

关键词： isothermal kinetics crystalline polypropylene calorimetry nucleation flour molding crystallinity amide

The air flow and heat transfer in gravel embankment in permafrost areas

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Science China Earth Sciences 2004年第Z1期47卷 142-151页

作者： JIANG Fan LIU Shi wang haigang CHEN Huanzhuo Institute of Engineering Thermophysics Chinese Academy of Sciences P.O. Box 2706 Beijing 100080 China Institute of Engineering Thermophysics Chinese Academy of Sciences P.O. Box 2706 Beijing 100080 China Institute of Engineering Thermophysics Chinese Academy of Sciences P.O. Box 2706 Beijing 100080 China Institute of Engineering Thermophysics Chinese Academy of Sciences P.O. Box 2706 Beijing 100080 China

A comparative numerical investigation of transient temperature profile and pore-air velocities in horizontal rock block embankments are conducted using the "gravels model", in which the embankment is composed of stones and air, and the "porous media model" respectively. As the velocities from the "gravels model" directly reflect the true flow of air and winter-time convection, in this paper it can be concluded that computational results from the "gravels model"are superior to the "porous media model". In addition, the "gravels model" has the advantages of reflecting the effect of the dimensions and collocation of gravels upon the temperature ***, the computation of the gravels embankment is mainly based on the gravels *** results show that in summer, a clockwise circulation of the pore-air extends throughout most of the embankment. However its motion is very weak that results in relatively straight horizontal isotherm lines. And heat transfer is mainly maintained through conduction. But in winter, the pore-air velocities are higher and multiple vortexes are formed in the *** convection then becomes the dominant influence on the isotherm shapes within the embankment. The isotherms are complex and alternative upward and downward flowing plumes exist. The winter-time convection can further reduce the temperature of the foundation soil beneath the gravel embankment. In addition, the effects of the gravel dimensions within the embankment have been analyzed and compared in the gravels model. It shows that in winter, large stones, e.g. 200 mm, lead to stronger vortexes than those of small stones, say 60 mm. Consequently, the zone of low-temperature beneath the large-stone embankment extends deeper into the ground.

关键词： permafrost, gravel embankment, numerical computation, gravels model, porous media model.

Experimental Study on Wavy-Flow Pneumatic Conveying in Horizontal Pipe

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Journal of Thermal Science 2002年第2期11卷 114-120页

作者： Hua Xu Shi Liu haigang wang Fan Jiang Chinese Acad Sci Inst Engn Thermophys Beijing 100080 Peoples R China

Low-velocity pneumatic conveying systems have been developed to meet the requirement of low operation costs and have been widely used in chemical and process industries. However, the understanding of the mechanism is limited. This paper reports an experimental study on a slug-flow pneumatic conveying. Electrical capacitance tomography has been used to visualize plug shape and identify the flow pattern. Comparison was made between the experimental data of pressure drop with existed models.

关键词： pneumatic conveying wavy flow pressure drop electrical capacitance tomography.