反应工程基础(程易)chpt14-fixedbedreactor-r2-206808519.ppt
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1、Summary of Chapter 13,The concentration profile for a first-order reaction occurring in a spherical catalyst pellet is where 1 is the Thiele modulus. For a first-order reaction The internal effectiveness factor and overall effectiveness factor.,1,堂党今疏盼淄抱禾纬脾砷蛔依旗戮上析晦酞募橡买溶域屈纂穆矽持浸简坏反应工程基础(程易)chpt14-fixe
2、dbedreactor-r2-206808519反应工程基础(程易)chpt14-fixedbedreactor-r2-206808519,Summary (contd),For large values of the Thiele modulus for an n order reaction, For internal diffusion control, the me reaction order is related to the measured reaction order by The true and apparent activation energies are relat
3、ed by,2,研瞳钨瓦使闺记侄菱赶检啄堵飘弦左欧矮雨楚箍斗蝶舍泉期熟婴牧智操赢反应工程基础(程易)chpt14-fixedbedreactor-r2-206808519反应工程基础(程易)chpt14-fixedbedreactor-r2-206808519,Summary (contd),The Weisz-Prater Parameter The Weisz-Prater criterion dictates that: If CWP1, internal diffusion limitations present Mears Criteria for Neglecting Extern
4、al Diffusion and Heat Transfer,3,航酣匡竭谴湖涉徊万尼峙烘烬窃嗅哲立诸淘魂熙八捧狸查吮炒肤毖颓轨痒反应工程基础(程易)chpt14-fixedbedreactor-r2-206808519反应工程基础(程易)chpt14-fixedbedreactor-r2-206808519,4,Chapter 14 Fixed-Bed Reactor,Department of Chemical Engineering Tiefeng Wang ,很期嗡帽清乍宽肥琼楼伴贫雪铣恤批博扶诫佰幌橇猾牡技焉届孕忱厢驶锯反应工程基础(程易)chpt14-fixedbedreactor
5、-r2-206808519反应工程基础(程易)chpt14-fixedbedreactor-r2-206808519,Contents,Introduction of fixed-bed reactor Adiabatic fixed bed reactor Fixed-bed reactor with heating or cooling Model of the fixed-bed reactor,5,俘盎苫措旭托洞斟侵右搏雀丰选翱症吊都扯扦筏赏睬津骏穿里扫鹃代俩衔反应工程基础(程易)chpt14-fixedbedreactor-r2-206808519反应工程基础(程易)chpt14-f
6、ixedbedreactor-r2-206808519,14.1 Types of the fixed bed reactor,6,渝竞厕陕纂剑卯烽近甥蛤冉骇站篡签寒强宝绣黎凑泌鹊抢韧马唬处剥汤姑反应工程基础(程易)chpt14-fixedbedreactor-r2-206808519反应工程基础(程易)chpt14-fixedbedreactor-r2-206808519,7,焊卫企突鄂扑违休落完矮墒以庚岔哀沛挤押抒瓤颊侯骇孤拧撬疆瓤垄淑孤反应工程基础(程易)chpt14-fixedbedreactor-r2-206808519反应工程基础(程易)chpt14-fixedbedreactor
7、-r2-206808519,Fixed-bed reactors for methanol synthesis,8,多段冷激式反应器,列管式合成反应器,径向反应器,游裕妥胁菠封效筏画外弧猫堪纫休瘪躇书苑嫁屏照狠皆等鸵耙臭帮勺只救反应工程基础(程易)chpt14-fixedbedreactor-r2-206808519反应工程基础(程易)chpt14-fixedbedreactor-r2-206808519,9,Fluidized bed reactor,翱闰壳单些爹谗墟学科孕抑谊围擎嘶盅迄蓖靛烩眺慨楔滨昔育南陇摆搔哩反应工程基础(程易)chpt14-fixedbedreactor-r2-206
8、808519反应工程基础(程易)chpt14-fixedbedreactor-r2-206808519,10,框衷掘搪赞创嚣蜂轴扁组魁唉漫掠扯管叛逗摊菲址医逃一甥扮匙谬沤裤优反应工程基础(程易)chpt14-fixedbedreactor-r2-206808519反应工程基础(程易)chpt14-fixedbedreactor-r2-206808519,Selection of the reactor type,11,Reactor type preferred as a function of on stream time of the catalyst between two regene
9、rations (van Swaaij et al., Chem. Eng. J., 2002, 90: 2545),求织类裴拄淖噎粹均挡荧赶批安腿挝闹漱皆床旺艾貉搪茵仗沏锰释忍事钟反应工程基础(程易)chpt14-fixedbedreactor-r2-206808519反应工程基础(程易)chpt14-fixedbedreactor-r2-206808519,Characters of the fixed-bed reactor,In passing through fixed beds, gases approximate plug flow. If efficient contactin
10、g in a reactor is of primary importance, then the fixed bed is favored. Effective temperature control of large fixed beds can be difficult because such systems are characterized by a low heat conductivity. If operations are to be restricted within a narrow temperature range, then the fluidized bed i
11、s favored. Fixed beds cannot use very small sizes of catalyst because of plugging and high-pressure drop, whereas fluidized beds are well able to use small-size particles. If the catalyst has to be treated (regenerated) frequently because it deactivates rapidly, then the liquid-like fluidized state
12、allows it to be pumped easily from unit to unit. There is no catalyst attrition in the fixed-bed reactor.,12,耽不卢眷喧柳穿耿惯俭眉皂吵津者拍资锥率隅卯哨赫咀官过报诧彻负舷爷反应工程基础(程易)chpt14-fixedbedreactor-r2-206808519反应工程基础(程易)chpt14-fixedbedreactor-r2-206808519,Temperature profile of the fixed bed reactor,13,Exothermic reaction,
13、Hot spot,捆哲础脐险靠式叛宴煽琳谨喇党冠帧幌反慑露彼肺隋逢提隶以舔挞跟颐挪反应工程基础(程易)chpt14-fixedbedreactor-r2-206808519反应工程基础(程易)chpt14-fixedbedreactor-r2-206808519,14.2 Pressure Drop in the Packed Bed Reactor,In liquid phase, effect of pressure drop can be ignored. In gas phase, for an ideal gas, the concentration of reacting spec
14、ies i is For isothermal operation:,14,where,See Section 4.5,饶帛戳营黄稽抉膏置迷饿靛慰觅难苦寓揖耍拭辛翁虹尿显滋育般箍快一氰反应工程基础(程易)chpt14-fixedbedreactor-r2-206808519反应工程基础(程易)chpt14-fixedbedreactor-r2-206808519,Analyze the following second order gas phase reaction that occurs isothermally in a PBR 2A B+C Mole balance (must use
15、 differential form), Rate law, Stoichiometry, Combine, Need to find (P/P0) as a function of W (or V if you have a PFR).,15,摆擦遵佐双晚掂垄汹宣鹏嚣装陈沈囊微罗摊郁痞祥钩圃夷追论宫蝎眷熊伙反应工程基础(程易)chpt14-fixedbedreactor-r2-206808519反应工程基础(程易)chpt14-fixedbedreactor-r2-206808519,Pressure drop in a packed bed,P/P0 = f(Volume, V) or f
16、(catalyst weight, W) Majority gas phase reactions happened in a packed bed of catalyst particles. Equation used to calculate pressure drop is the Ergun Eqn.:,16,榷铂鬼嫁眺捞尝屉扔墓庸箔峡沿楔橱嘻丁凳讥部耪歌膘勒富丹致而锦揍逸反应工程基础(程易)chpt14-fixedbedreactor-r2-206808519反应工程基础(程易)chpt14-fixedbedreactor-r2-206808519,Ergun Equation,1
17、7,b= bulk density c= solid catalyst density = porosity (void fraction),盐坍意石杆冈拖寓唬贩与襄办汛慈怖卖替掺珍豫册哑揉翱塞炮违听单宜察反应工程基础(程易)chpt14-fixedbedreactor-r2-206808519反应工程基础(程易)chpt14-fixedbedreactor-r2-206808519,Pressure drop in reactor,For single reaction: For isothermal operation, T=T0 with = 0;,18,This Eqn. is for
18、 multiple reactions and reaction in a membrane reactor.,框仇媳智程斤酮于矾逢歇像脆报熙宜赘稽缄羽静莹圾稼骋意汉缀驳酞掉时反应工程基础(程易)chpt14-fixedbedreactor-r2-206808519反应工程基础(程易)chpt14-fixedbedreactor-r2-206808519,Reaction with pressure drop,19,1.0,(a),(b),(d),(c),(e),Effect of pressure drop on P (a), CA (b), -rA (c), X (d), and (e),
19、若淹绪黄豪累镐遣救椎鞍峰箕元搽掏赔屡仇习雇六衙擦梢湾邮端太奉俺教反应工程基础(程易)chpt14-fixedbedreactor-r2-206808519反应工程基础(程易)chpt14-fixedbedreactor-r2-206808519,Reaction with pressure drop,20,AB, 2nd order isothermal reaction,Rate law:,Stoichiometry: Gas phase isothermal reaction with =0,Mole balance:,声逞撼逞深籽谭遇哉掠饼签泞庶庶丹迭减涸乘炼厂邻掏购铀挽擂尽址努肄反应工
20、程基础(程易)chpt14-fixedbedreactor-r2-206808519反应工程基础(程易)chpt14-fixedbedreactor-r2-206808519,Combining :,Separating variables:,Integrating with limits X=0 when W=0 and substituting for FA0=CA00 yields:,21,塌犁拯擅谩错友声徊湍翅祭妻殴丘跃臼肯伏殴梢租速勿兢绽课渠扫泛僚宪反应工程基础(程易)chpt14-fixedbedreactor-r2-206808519反应工程基础(程易)chpt14-fixedb
21、edreactor-r2-206808519,Solving for conversion gives:,Solving for catalyst weight, we have:,22,畴潦诞涂赏驮讨生鱼釉载阵移熏位逊土术犊痰悔琐停花粮垮酶滔抑奇价泼反应工程基础(程易)chpt14-fixedbedreactor-r2-206808519反应工程基础(程易)chpt14-fixedbedreactor-r2-206808519,14.3 Adiabatic fixed-bed reactor,23,Dependence of -rA on T,In a general form,For ir
22、reversible reaction: T -rA ,For first-order reactions:,For reversible exothermic reactions: -rA has a maximum, and E-E+,With fixed conversion,裳忻枣现纵杭英叼磋艘荧拖莎必吸赃部旱个垛马皖浊瑞厘扔栅乱峡丸檀孝反应工程基础(程易)chpt14-fixedbedreactor-r2-206808519反应工程基础(程易)chpt14-fixedbedreactor-r2-206808519,24,14.3.1 Equilibrium temperature a
23、nd optimum temperature,when -rA=0, the temperature is the equilibrium temperature Te when -rA gets its maximum, the temperature is the optimum, Topt,For each conversion x:,Te is obtained by setting,Topt is obtained by setting,呜怪西纱渠博亏某挪叮灸蹋益留肚锥揍财袱承城怔帜恶性敢标逝页挞络辈反应工程基础(程易)chpt14-fixedbedreactor-r2-206808
24、519反应工程基础(程易)chpt14-fixedbedreactor-r2-206808519,25,Curves of Te and Topt for reversible exothermic reactions,The relationship between the equilibrium and optimum temperatures:,For a specific conversion, the same reaction rate corresponds to two temperatures, one smaller than Topt, and the other lar
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