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Complementar.ty of CFD,exper.mentation and r.actor.models for.solving challenging fluidization pr.blems

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Par.icuology 2010年第6期8卷 498-500页

作者： john r. grace Tingwen Li Depar.ment of Chemical and Biological Engineer.ng University of British Columbia Vancouver V6T 1Z3 Canada National Ener.y Technology Labor.tor. 3610 Collins Ferry Rd Morgantown WV26507 USA

Exper.mentalists, numer.cal modeller. and r.actor.modeller. need to wor. together. not only just for.validation of numer.cal codes, but also to shed fundamental light on each other.s pr.blems and under.ying assumptions. Sever.l examples ar. given, Exper.mental gas axial disper.ion data pr.vide a means of choosing the most appr.pr.ate boundar. condition （no slip, par.ial slip or.full slip） for.par.icles at the wall of fluidized beds. CFD simulations help to identify how close ＂two-dimensional＂ exper.mental columns ar. to being tr.ly two-dimensional and to r.pr.senting thr.e-dimensional columns. CFD also can be used to pr.vide a mor. r.tional means of establishing assumptions needed in the modelling of two-phase fluidized bed r.actor., for.example how to deal with cases wher. ther. is a change in molar.flow （and hence volumetr.c flow） as a r.sult of chemical r.actions.

关键词： Fluidization Mixing Computational Fluid dynamics Wall slip r.actor.modelling Volume change

Hydr.dynamics and solids mixing in fluidized beds with inclined-hole distr.butor.

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Par.icuology 2019年第2期17卷 19-28页

作者： Alhussain Bakhur.i Xiaotao Bi john r. grace Fluidization r.sear.h Centr. Department of Chemical and Biological Engineering University of British Columbia Vancouver V6TJZ3 Canada

Exper.mental fluidization r.sults wer. compar.d for.thr.e gas distr.butor. with the same opening r.tio but differ.nt or.fice in clinations (30,45 , and 90 ). Hydr.dynamic studies wer. con ducted with glass beads (diameter.154p.m) to evaluate the impacts of or.fice inclination and static bed depth on pr.ssur. dr.p, pr.ssur. dr.p fluctuations, bed expansion, and minimum fluidization velocity. Solids r.sidence time distr.butions wer. deter.ined using phosphor.sce nt tr.cer.par.icles (mea n diameter.76 pm), activated by ultr.violet light. The bed pr.ssur. dr.p was higher.with the inclined-hole distr.butor. and incr.ased with static bed height. In a shallow bed, the inclined-hole distr.butor. gave less expansion;however. in deep beds, the or.fice angle had negligible influence on bed expansion. The minimum fluidization velocity var.ed with static bed height for.the inclined-hole distr.butor. and was higher.for.steeper.angles. The tur.over.time estimated using bubbling-bed equations matched the exper.mental r.sults well for.ver.ical mixing. Pr.bes and por.s at the walls of the fluidization column r.duced the dense-phase downwar. velocity by up to 40%. The tangential par.icle velocity was highest for.the 30 -hole distr.butor.and decr.ased with incr.asing or.fice angle. Tangential mixing was descr.bed by a disper.ion model;the disper.ion coefficient for.the inclined-hole distr.butor. was appr.ximately twice that for.the 90 -hole distr.butor.in a shallow bed.

关键词： Swir.ing fluidized bed Fluidization Solids mixing Inclined-hole distr.butor

Biomass tor.efaction in a slot-r.ctangular.spouted bed r.actor

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Par.icuology 2019年第1期17卷 154-162页

作者： Ziliang Wang C. Jim Lim john r. grace Depar.ment of Chemical and Biological Engineer.ng. Univer.ity of Br.tish Columbia Vancouver. Canada

Sawdust was subjected to tor.efaction in a "semi-batch" slot-r.ctangular.spouted bed (Sr.B) r.actor.at temper.tur.s fr.m 240 to 330℃ and biomass feed r.tes fr.m 220 to 710g/*** spouting of the sawdust was achieved in the slot-r.ctangular.spouted bed,although the pr.ssur. dr.p acr.ss the r.actor.was obser.ed to *** to the biomass feed r.te,the temper.tur. had a gr.ater.effect on the biomass weight loss and ener.y *** in temper.tur. wer. found to pr.mote weight loss of the sawdust while decr.asing the ener.y *** main solid pr.duct was the tor.efied sawdust,which r.mained in the Sr.B r.actor.and was captur.d by a *** r.tio of the tor.efied biomass r.moved by the cyclone to the total tor.efied biomass incr.ased along with both the feed r.te and *** under.oing tor.efaction,6.7%-39.2% of the or.ginal sawdust mass was lost while 67.4%-98.7% of its ener.y was *** tor.efied sawdust had a higher.car.on content but less oxygen,hydr.gen and volatiles,along with a gr.ater.higher.heating value and incr.ased density compar.d to the r.w *** size of the sawdust par.icles also decr.ased mar.edly dur.ng the tor.efaction pr.cess.

关键词： Tor.efaction Slot-r.ctangular spouted bed r.actor Temper.tur. Biomass feed r.te Tor.efied sawdust pr.per.y

Tr.bo-char.ing of binar. mixtur.s composed of coar.e and fine par.icles in gas-solid pipe flow

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Par.icuology 2019年第2期17卷 101-109页

作者： Haifeng Wang Far.am Fotovat Xiaotao T. Bi john r. grace Depar.ment of Chemical Engineer.ng China University of Mining and Technology. Xuzliou 221166 China Depar.ment of Chemical and Petr.leum Engineer.ng Sharif University of Technology Azadi Avenue P.O. Box 11365-9465 Tehran Iran Fluidization r.sear.h Centr. Department of Chemical and Biological Engineering University of British Columbia. Vancouver V6T 1Z3 Canada

Exper.ments wer. conducted to investigate the effect of adding fines on the tr.bo-char.ing of coar.e glass beads. Four.types of fines, i.e., copper. stainless steel, uncoated and silver.coated fine glass beads, mixed w让h 240-830 μm glass beads wer. conveyed by air.thr.ugh a stainless-steel spir.l pipe acting as a tr.bo-char.er. r.gar.less of the type or.electr.cal conductivity of the fine par.icles tested, adding small amounts of fines (up to 10wt%) to coar.e glass beads r.sulted in a shar. incr.ase in the mass and sur.ace char.e densities of the par.icles. In gen er.l, the pr.files of the mass and sur.ace char.e den sides of the fine-coar.e par.icle mixtur.s as a function of the mixtur. composition wer. deter.ined by the r.lative magnitude of contact potential differ.nces and the total sur.ace ar.as of all the comp on ents. The domi nant par.icle tr. bo-electr.fication mecha nism switched fr.m coar.e par.icle-wall con tacts to fine par.icle-wall contacts when the fines weight per.entage in the mixtur. exceeded 10%. A model was developed to pr.dict the mass char.e density of bi nar. mixtur.s as a function of the mixtur. composition.

关键词： Tr.bo-char.ing Electr.statics Fine par.icles Binar. mixtur. Gas-solid flow

PNEUMATIC CONVEYING OF BIOMASS PAr.ICLES:A r.VIEW

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China Par.icuology 2006年第3期4卷 183-188页

作者： john r. grace Depar.ment of Chemical and Biological Engineer.ng University of British Columbia 2360 East Mall Vancouver V6T 1Z3 Canada

Pr.cesses involving biomass ar. of gr.wing inter.st, but handling and conveying biomass par.icles ar. challenging due to the unusual physical pr.per.ies of biomass par.icles. This paper.r.views r.cent wor. on pneumatic conveying of biomass par.icles, especially agr.cultur.l par.icles and pulp fibr.s. Exper.mental wor. has been mainly car.ied out to deter.ine a r.nge of par.meter., such as pr.ssur. dr.p, par.icle velocity, flow r.gime and electr.static char.ing for.both hor.zontal and ver.ical conveying. Models r.nging fr.m empir.cal to CFD models ar. also being developed. Difficulties in r.pr.senting tur.ulence and inter.ctions among biomass par.icles and between the par.icles and fluid have so far.limited the success of advanced modeling. Fur.her.wor. is needed to impr.ve under.tanding of multiphase biomass pneumatic conveying and to assist in the development of biomass ener.y and conver.ion pr.cesses.

关键词： biomass multiphase flow pneumatic conveying agr.cultur.l modeling par.icles

Exper.mental analysis of volatile liquid injection into a fluidized bed

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Par.icuology 2017年第5期15卷 39-47页

作者： A.H. Ahmadi Motlagh john r. grace Cedr.c Br.ens Fr.nco Ber.uti Masoumeh Far.hondehkavaki Majid Hamidi Depar.ment of Chemical and Biological Engineer.ng University of British Columbia Vancouver V6T 1Z3 BC Canada Institute for.Chemicals and Fuels fr.m Alter.ative r.sour.es (ICFAr. Department of Chemical and Biochemical Engineering Western University London N6A 5B9 ON Canada

Exper.ments wer. conducted on a lab-scale fluidized bed to study the distr.bution of liquid ethanol injected into fluidized catalyst par.icles. Electr.cal capacitance measur.ments wer. used to study the liquid distr.bution inside the bed, and a new method was developed to deter.ine the liquid content inside fluidized beds of fluid catalytic cr.cking par.icles. The r.sults shed light on the complex liquid injection r.gion and r.veal the str.ng effect of super.icial gas velocity on liquid distr.bution inside the fluidized bed, which is also affected by the imbibition of liquid inside par.icle por.s. Par.icle inter.al por.sity was found to play a major.r.le when the changing mass of liquid in the bed was monitor.d. The r.sults also showed that the dur.tion of liquid injection affected liquid-solid contact inside the bed and that liouid-solid mixin~ was not homogeneous dur.n~ the limited liouid injection time.

关键词： Liquid injection Fluidized bed Fluid catalytic cr.cking Hydr.dynamics Vapor.zation

Estimation of solids cir.ulation r.te and char.tr.nsfer.r.te fr.m gasifier.to combustor.in a dual fluidized-bed pilot plant for.biomass steam gasification

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Par.icuology 2019年第5期17卷 22-29页

作者： M. Hafizur.r.hman Lius Daniel Ujash Shah Xiaotao Bi john r. grace C.Jim Lim Fluidization r.sear.h Centr. Department of Chemical & Biological Engineering University of British Columbia 2360 East Mall Vancouver British Columbia V6T1Z3 Canada

Oper.tion of a dual fluidized bed, consisting of a r.ser.as combustor.and bubbling bed as gasifier. for.synthesis gas pr.duction fr.m a solid fuel r.quir.s deter.ination of the solids cir.ulation r.te and char.tr.nsfer.r.te. The per.or.ance r.lies on supplying sufficient heat fr.m the combustor.to the gasifier.by cir.ulation of solids between these two r.actor.. The flow r.te of char.is r.quir.d to tr.ck the heat gener.ted in the combustor. which suppor.s endother.ic r.actions in the gasifier. Dir.ct measur.ment of these two cr.tical par.meter. is difficult, with the number.of r.por.ed techniques capable of wor.ing at high temper.tur.s extr.mely small. An indir.ct method was developed, using mass and ener.y balances over.the entir. system and individual r.actor., to estimate the solids cir.ulation r.te and char.tr.nsfer.r.te. Ther. was gener.l agr.ement between heat losses estimated fr.m ener.y-balance calculations and fr.m dir.ct measur.ment of the outer.r.actor.sur.ace temper.tur.. Under.typical gasification conditions, the solids cir.ulation fluxes wer. estimated to be 45.2 and 55.6 kg/(m^2 s) in two independent tests, which wer. in good agr.ement with values obtained using a ther.al tr.cer.char.tr.nsfer.r.tes wer. calculated to be 1.2 and 0.6 kg/h, which wer. in r.asonable agr.ement with aver.ge biomass feed r.tes. This method can be applied to dual gasification systems at any temper.tur. or.flow r.te.

关键词： Solids cir.ulation r.te Char tr.nsfer r.te Pilot-plant gasifier Dual fluidized bed Mass and ener.y balance

Connecting par.icle spher.city and cir.ular.ty

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Par.icuology 2021年第1期19卷 1-4页

作者： john r.grace Ar.an Ebneyamini Depar.ment of Chemical&Biological Engineer.ng University of British ColumbiaVancouver V6T 1Z3Canada

Spher.city,a measur. of how much a par.icle’s shape deviates fr.m spher.cal,is useful as a shape factor.hen char.cter.zing par.iculate ***,par.icle sur.ace ar.as,r.quir.d when deter.iningthe spher.city,ar. ver. difficult to *** a r.sult,the cir.ular.ty,der.vable fr.m micr.scopic views,is often measur.d instead and assumed to be equal to the *** paper.shows that the twoquantities ar. gener.lly not equal for.simple non-spher.cal shapes and pr.vides advice on impr.ving theestimation of spher.city fr.m cir.ular.ty.

关键词： Non-spher.cal par.icles Spher.city Cir.ular.ty Shape factor.a

A novel dual-mater.al pr.be for.in situ measur.ment of par.icle char.e densities in gas-solid fluidized beds

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Par.icuology 2015年第4期13卷 20-31页

作者： Chuan He Xiaotao T.Bi john r.grace Fluidization r.sear.h Centr. Department of Chemical and Biological EngineeringThe University of British Columbia

Par.icle char.e density is vitally impor.ant for.monitor.ng electr.static char.es and under.tanding par.icle char.ing behavior.in fluidized beds. In this paper. a dual-mater.al pr.be was tested in a gas-solid fluidized bed for.measur.ng the char.e density of fluidized par.icles. The exper.ments wer. conducted in a two-dimensional fluidized bed with both single bubble injection and fr.ely bubbling, at var.ous par.icle char.e densities and super.icial gas velocities. Unifor.ly sized glass beads wer. used to eliminate complicating factor. at this ear.y stage of pr.be development. Peak cur.ents, extr.cted fr.m dynamic signals, wer. decoupled to deter.ine char.e densities of bed par.icles, which wer. found to be qualitatively and quantitatively consistent with char.e densities dir.ctly measur.d by Far.day cup fr.m the fr.ely bubbling fluidized bed. The cur.ent signals wer. also decoupled to estimate bubble r.se velocities, which wer. found to be in r.asonable agr.ement with those obtained dir.ctly by analyzing video images.

关键词： Electr.statics Par.icle char.e density Dual-mater.al collision pr.be Signal decoupling Fluidized bed Bubble r.se velocity