生物分离工程第二章过滤ppt课件

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1、Chapter 2 Filtration 第二章第二章 过过 滤滤1 1大家好大家好Key knowledge points(知知识识点点)A Pretreatment A Pretreatment 预处理预处理预处理预处理1 1、Heating Heating 加热加热加热加热2 2、Coagulation and flocculation Coagulation and flocculation 凝聚和絮凝凝聚和絮凝凝聚和絮凝凝聚和絮凝3 3、Adsorption on filter aids Adsorption on filter aids 助滤剂上的吸附助滤剂上的吸附助滤剂上的吸附助

2、滤剂上的吸附B General Theory for FiltrationB General Theory for Filtration1 1、Darcys Law Darcys Law 达西方程达西方程达西方程达西方程 2 2、Incompressible Cakes Incompressible Cakes 不可压缩滤饼不可压缩滤饼不可压缩滤饼不可压缩滤饼t t(o o/(2/(2 P)*(V/A)P)*(V/A)2 23 3、 Compressible cake Compressible cake 可压缩的滤饼可压缩的滤饼可压缩的滤饼可压缩的滤饼C C Continuous Rotary

3、 FilterContinuous Rotary Filter连续旋转式过滤机连续旋转式过滤机连续旋转式过滤机连续旋转式过滤机D D Equipment for Conventional Filtration Equipment for Conventional Filtration 传统的传统的过滤设备过滤设备 2 2大家好大家好Filtration separates solid from a liquid by forcing Filtration separates solid from a liquid by forcing the liquid through a solid su

4、pport or filter the liquid through a solid support or filter medium. This is a straightforward procedure for medium. This is a straightforward procedure for well defined crystals.well defined crystals. 过滤是将料液通过固体支持或者过滤介质时，使得固过滤是将料液通过固体支持或者过滤介质时，使得固过滤是将料液通过固体支持或者过滤介质时，使得固过滤是将料液通过固体支持或者过滤介质时，使得固体物质从溶液

5、中分离，对于好的定形的晶体，这是一体物质从溶液中分离，对于好的定形的晶体，这是一体物质从溶液中分离，对于好的定形的晶体，这是一体物质从溶液中分离，对于好的定形的晶体，这是一种最直接的步骤。种最直接的步骤。种最直接的步骤。种最直接的步骤。3 3大家好大家好滤饼滤饼传统的过滤cakeConventional filtration大家好under大家好大家好However the small size of microorganisms make However the small size of microorganisms make filtration of fermentation beer

6、s or other biological filtration of fermentation beers or other biological solutions considerably more complicated. solutions considerably more complicated. 但对微小而形状多变的微生物细胞，但对微小而形状多变的微生物细胞，但对微小而形状多变的微生物细胞，但对微小而形状多变的微生物细胞，发酵液和其它生发酵液和其它生发酵液和其它生发酵液和其它生物溶液的过滤就变得复杂了物溶液的过滤就变得复杂了物溶液的过滤就变得复杂了物溶液的过滤就变得复杂了 。7

7、 7大家好大家好Generally, Generally, fermentation fermentation beers beers and and other other biological biological solutions solutions are are notoriously notoriously hard hard to to filter. filter. They They are are often often hard hard to to filter filter because because of of high high non-Newtonian

8、non-Newtonian viscosity viscosity or or highly highly compressible compressible cakes. cakes. That That is is to to say, say, we we must must modify modify these these procedures procedures for for bio-bio-separations.separations. 一一一一般般般般，由由由由于于于于料料料料液液液液通通通通常常常常都都都都是是是是高高高高的的的的非非非非牛牛牛牛顿顿顿顿粘粘粘粘度度度度

9、流流流流体体体体或或或或者者者者是是是是高高高高度度度度可可可可压压压压缩缩缩缩滤滤滤滤饼饼饼饼，发发发发酵酵酵酵液液液液和和和和其其其其它它它它生生生生物物物物溶溶溶溶液液液液是是是是极极极极其其其其难难难难以以以以过过过过滤滤滤滤的的的的，也也也也就就就就是是是是说说说说，我我我我们们们们必必必必须须须须对对对对这这这这些生物分离程序进行修改。些生物分离程序进行修改。些生物分离程序进行修改。些生物分离程序进行修改。8 8大家好大家好A Pretreatment 预处理预处理1 1、Heating Heating 加热加热加热加热2 2、Coagulation and flocculatio

10、n Coagulation and flocculation 凝聚和絮凝凝聚和絮凝凝聚和絮凝凝聚和絮凝3 3、Adsorption on filter aids Adsorption on filter aids 助滤剂上的吸附助滤剂上的吸附助滤剂上的吸附助滤剂上的吸附 These These treatments treatments are are also also useful useful for for centrifugation and sedimentation. centrifugation and sedimentation. 这些方法也适用于对于离心和沉淀过程。这些方法

11、也适用于对于离心和沉淀过程。这些方法也适用于对于离心和沉淀过程。这些方法也适用于对于离心和沉淀过程。9 9大家好大家好1、 Heating 加热加热The The simplest simplest pretreatment pretreatment and and the the least least expensive expensive method method is is to to heat heat the the feed. feed. Such Such heating heating can can not not only only improve improve th

12、e the feeds feeds handling handling characteristics, characteristics, but but also also may may pasteurize pasteurize it. it. The The chief chief constraint constraint of of this this approach approach is is the the thermal thermal stability stability of of the the product. product. (lead (lead to i

13、rreversible reaction).to irreversible reaction). 最最最最简简简简单单单单、最最最最经经经经济济济济的的的的预预预预处处处处理理理理方方方方法法法法是是是是加加加加热热热热，加加加加热热热热不不不不仅仅仅仅可可可可以以以以增增增增加加加加料料料料液液液液的的的的操操操操作作作作特特特特性性性性，也也也也可可可可以以以以对对对对其其其其进进进进行行行行灭灭灭灭菌菌菌菌。但但但但加加加加热热热热变变变变性性性性的的的的方方方方法只适合于对热稳定性的产物。法只适合于对热稳定性的产物。法只适合于对热稳定性的产物。法只适合于对热稳定性的产物。1010大家好

14、大家好2、Coagulation and flocculation 凝聚和絮凝凝聚和絮凝The The second second pretreatment pretreatment method method is is the the addition addition of of electrolytes electrolytes to to promote promote coagulation coagulation and and flocculation flocculation in in the the initial initial solution. solution.

15、Useful Useful agents agents rang rang from from simple simple electrolytes electrolytes through through acids acids and and bases bases to to synthetic polyelectrolytes.synthetic polyelectrolytes. 第第第第二二二二种种种种预预预预处处处处理理理理方方方方法法法法是是是是通通通通过过过过电电电电解解解解质质质质的的的的加加加加入入入入促促促促进进进进原原原原始始始始溶溶溶溶液液液液的的的的凝凝凝凝聚聚聚

16、聚和和和和絮絮絮絮凝凝凝凝，试试试试剂剂剂剂有有有有简简简简单单单单的的的的电电电电解解解解质质质质、酸酸酸酸、碱碱碱碱、合合合合成成成成的的的的聚聚聚聚合合合合电解质。电解质。电解质。电解质。1111大家好大家好Simple Simple electrolytes electrolytes act act by by screening screening the the electrostatic electrostatic repulsion repulsion which which commonly commonly exists exists between between col

17、loidal colloidal particles. particles. When When this this electrostatic electrostatic repulsion repulsion is is reduced, reduced, attractive attractive London-vander London-vander waals waals forces forces predominate. predominate. The The colloids colloids can can then then coagulate coagulate as

18、as larger, larger, dense dense particles particles which which are are more more easily filtered.easily filtered. 简简简简单单单单电电电电解解解解质质质质降降降降低低低低了了了了胶胶胶胶体体体体粒粒粒粒子子子子间间间间的的的的排排排排斥斥斥斥电电电电位位位位，从从从从而而而而使使使使得得得得范范范范德德德德华华华华引引引引力力力力起起起起主导作用，聚合成较大的胶粒，粒子的密度越大，越易分离。主导作用，聚合成较大的胶粒，粒子的密度越大，越易分离。主导作用，聚合成较大的胶粒，粒子的密度

19、越大，越易分离。主导作用，聚合成较大的胶粒，粒子的密度越大，越易分离。1212大家好大家好18pH3.8pH2.8TheeffectonfiltratevolumeofpHpH值对过滤体积的影响00200400600612pH4.6pH4.2FiltrateVolume(cm)3Time(min)大家好Time(min)181%filteraidinfeed2%3%5%00100400600612FiltrateVolume(cm)3Theeffectonfiltratevolumeoffilteraid助滤剂对过滤体积的影响大家好Simple acids and basesSimple ac

20、ids and bases（简单的酸或碱）简单的酸或碱）简单的酸或碱）简单的酸或碱）AlumAlum（明矾）（明矾）（明矾）（明矾）Ferric chloride crystalsFerric chloride crystals（三氯化铁）（三氯化铁）（三氯化铁）（三氯化铁）1515大家好大家好Synthetic Synthetic polyelectrolytes polyelectrolytes added added as as pretreatments pretreatments can can both both reduce reduce electrostatic electr

21、ostatic repulsion repulsion and and adsorb adsorb on on adjacent adjacent particles, particles, forming forming bridges bridges between between them. them. As As a a result, result, the the colloidal colloidal particles particles flocculate flocculate as as large, large, less less dense dense aggreg

22、ates aggregates which which are are more more easily easily filtered. filtered. These These polyelectrolytes polyelectrolytes can can be be anionic, cationic or nonionic.anionic, cationic or nonionic. 预预预预处处处处理理理理时时时时加加加加入入入入合合合合成成成成聚聚聚聚合合合合电电电电解解解解质质质质既既既既能能能能降降降降低低低低排排排排斥斥斥斥电电电电位位位位，又又又又吸吸吸吸附附附附了了

23、了了周周周周围围围围的的的的微微微微粒粒粒粒，形形形形成成成成桥桥桥桥架架架架作作作作用用用用，促促促促使使使使胶胶胶胶粒粒粒粒形形形形成成成成粗粗粗粗大大大大，密密密密度度度度低低低低的的的的絮絮絮絮凝凝凝凝团团团团。这这这这些些些些絮絮絮絮凝凝凝凝团很容易被过滤得到。团很容易被过滤得到。团很容易被过滤得到。团很容易被过滤得到。PolyacrylamidesPolyacrylamides（聚丙烯酰胺）聚丙烯酰胺）聚丙烯酰胺）聚丙烯酰胺）PolyethyleniminesPolyethylenimines（聚乙烯亚胺）聚乙烯亚胺）聚乙烯亚胺）聚乙烯亚胺）Polyamine derivative

24、sPolyamine derivatives（多聚胺衍生物）多聚胺衍生物）多聚胺衍生物）多聚胺衍生物） 1616大家好大家好 （1 1）、）、）、）、Diatomaceous earths Diatomaceous earths 硅藻土硅藻土硅藻土硅藻土 Diatomaceous Diatomaceous earths earths are are the the skeletal skeletal remains remains of of the the tiny tiny aquatic plants deposited centuries ago.aquatic plants depo

25、sited centuries ago. 硅藻土是百年前水生植物沉淀下来的遗骸。硅藻土是百年前水生植物沉淀下来的遗骸。硅藻土是百年前水生植物沉淀下来的遗骸。硅藻土是百年前水生植物沉淀下来的遗骸。 （2 2）、）、）、）、Perlites Perlites 珍珠岩珍珠岩珍珠岩珍珠岩 The The perlites perlites are are volcanic volcanic rock rock processed processed to to yield yield an an expanded form.expanded form. 珍珠岩是处理过的膨胀火山岩。珍珠岩是处理过的膨胀

26、火山岩。珍珠岩是处理过的膨胀火山岩。珍珠岩是处理过的膨胀火山岩。3、AdsorptiononFilterAids助滤剂上的吸附1717大家好大家好Table2.1.TypicalpropertiesofFilterAids1818大家好大家好B. General Theory for Filtration Now Now we we turn turn to to the the mathematical mathematical description of filtration. description of filtration. 现在我们现在我们现在我们现在我们对过滤过程进行数学描述对

27、过滤过程进行数学描述对过滤过程进行数学描述对过滤过程进行数学描述 。1919大家好大家好 DarcyDarcy方方方方程程程程fluid fluid mechanics mechanics for for filtration filtration Darcys law Darcys law ： 1 1、for incompressible cake, simplest case for incompressible cake, simplest case 适用于不可压缩和简单的可压缩滤饼适用于不可压缩和简单的可压缩滤饼适用于不可压缩和简单的可压缩滤饼适用于不可压缩和简单的可压缩滤饼 2 2、

28、 for for compressible compressible cake, cake, common common for for bio-bio-separationsseparations 适用于可压缩滤饼，普遍使用于生物分离过程适用于可压缩滤饼，普遍使用于生物分离过程适用于可压缩滤饼，普遍使用于生物分离过程适用于可压缩滤饼，普遍使用于生物分离过程2020大家好大家好Darcys law （达西定律）达西定律）Darcys Darcys law law relates relates the the flow flow rate rate through through a a po

29、rous porous bed of solids to the pressure drop causing that flow bed of solids to the pressure drop causing that flow Darcy Darcy定律把流速与通过固体多孔床产生的压降联系起来。定律把流速与通过固体多孔床产生的压降联系起来。定律把流速与通过固体多孔床产生的压降联系起来。定律把流速与通过固体多孔床产生的压降联系起来。v=kv=kP/lP/lP/lP/l (2.1) (2.1) v v directly proportional to directly proportion

30、al to directly proportional to directly proportional to P P P P 流速正比于压降流速正比于压降流速正比于压降流速正比于压降 v v inversely proportional to inversely proportional to inversely proportional to inversely proportional to l/kl/k 流速反比于阻力流速反比于阻力流速反比于阻力流速反比于阻力l/kl/k2121大家好大家好v v is the velocity of the liquid is the velocit

31、y of the liquid v v 流体流速流体流速流体流速流体流速k k： proportionality proportionality constant, constant, usually usually called called the the Darcys law permeability of the bedDarcys law permeability of the bed k k比例常数比例常数比例常数比例常数, ,通常叫达西方程参数通常叫达西方程参数通常叫达西方程参数通常叫达西方程参数P: the pressure drop across the bed of thi

32、ckness P: the pressure drop across the bed of thickness P P通过厚度为通过厚度为通过厚度为通过厚度为l l的床产生的压降的床产生的压降的床产生的压降的床产生的压降: viscosity of the liquid : viscosity of the liquid 液体粘度液体粘度液体粘度液体粘度2222大家好大家好 Darcys law holds only when Re5Darcys law holds only when Re5 当当当当Re5Re5时达西定律才成立时达西定律才成立时达西定律才成立时达西定律才成立 Re= dv/

33、(1-) (2.2)Re= dv/(1-) (2.2) d-particle size or pore diameter in the filter cake d-particle size or pore diameter in the filter cake 滤饼粒子的大小或孔的直径滤饼粒子的大小或孔的直径滤饼粒子的大小或孔的直径滤饼粒子的大小或孔的直径 -the void fraction in the cake -the void fraction in the cake 滤饼空隙率滤饼空隙率滤饼空隙率滤饼空隙率 -the liquid density -the liquid dens

34、ity 液体的密度液体的密度液体的密度液体的密度 v is the velocity of the liquid v is the velocity of the liquid 流体流速流体流速流体流速流体流速 Re Reynolds number Re Reynolds number 雷诺准数雷诺准数雷诺准数雷诺准数2323大家好大家好For batch filtration, the velocity isFor batch filtration, the velocity is对于板框式过滤对于板框式过滤对于板框式过滤对于板框式过滤, ,速率方程为：速率方程为：速率方程为：速率方程为：

35、v=(1/A)*dV/dt v=(1/A)*dV/dt (2.3)(2.3)A filtration area A filtration area 过滤面积过滤面积过滤面积过滤面积V the total volume of filtration V the total volume of filtration 过滤液体积过滤液体积过滤液体积过滤液体积t the filtration time t the filtration time 过滤时间过滤时间过滤时间过滤时间2424大家好大家好 The The resistance resistance to to include include e

36、xplicitly explicitly the the contributions of cake and filter medium.contributions of cake and filter medium. 滤饼和过滤介质所产生的阻力：滤饼和过滤介质所产生的阻力：滤饼和过滤介质所产生的阻力：滤饼和过滤介质所产生的阻力： l/k= Rl/k= Rmm + R + Rc c (2.4 (2.4）R Rmm the resistance of the filter medium the resistance of the filter medium 过滤介质的阻力过滤介质的阻力过滤介质的

37、阻力过滤介质的阻力R Rc c the resistance of accumulate cake bio-mass the resistance of accumulate cake bio-mass 滤饼的阻力滤饼的阻力滤饼的阻力滤饼的阻力 2525大家好大家好Combining E.q. (2.1) (2.3) (2.4) Combining E.q. (2.1) (2.3) (2.4) we we find find differential differential equation equation for for batch batch filtration filtration

38、 at at the the constant constant pressure droppressure drop： 我们发现板筐式过滤压降是一个常数我们发现板筐式过滤压降是一个常数我们发现板筐式过滤压降是一个常数我们发现板筐式过滤压降是一个常数 (1/A)*dV/dt = (1/A)*dV/dt = P/(RP/(Rmm + R + Rc c) (2.5) (2.5) R Rmm is a constant independent of the cake is a constant independent of the cake； R Rmm是常数，与滤饼无关；是常数，与滤饼无关；是常数

39、，与滤饼无关；是常数，与滤饼无关； R RCC the cakes resistance varies with total volume of filtration the cakes resistance varies with total volume of filtration ； R Rc c与滤液总体积有关；与滤液总体积有关；与滤液总体积有关；与滤液总体积有关； The The exact exact nature nature of of this this variation variation depends depends on on whether whether the

40、 the cake cake is is incompressible or not .incompressible or not . R Rc c的变化取决于滤饼是不可压缩还是可压缩。的变化取决于滤饼是不可压缩还是可压缩。的变化取决于滤饼是不可压缩还是可压缩。的变化取决于滤饼是不可压缩还是可压缩。2626大家好大家好 If the cake is in compressible (rigid), the cake If the cake is in compressible (rigid), the cake thickness is directly proportional filtra

41、te volume and thickness is directly proportional filtrate volume and inversely proportional to the filter area. inversely proportional to the filter area. 如果滤饼是不可压缩的，则滤饼的厚度正比于过滤液的如果滤饼是不可压缩的，则滤饼的厚度正比于过滤液的如果滤饼是不可压缩的，则滤饼的厚度正比于过滤液的如果滤饼是不可压缩的，则滤饼的厚度正比于过滤液的体积，反比于过滤面积。体积，反比于过滤面积。体积，反比于过滤面积。体积，反比于过滤面积。1 1、I

42、ncompressible Cakes Incompressible Cakes 不可压缩滤饼不可压缩滤饼2727大家好大家好 As a result the cakes resistance R As a result the cakes resistance Rc c is is 滤饼的阻力滤饼的阻力滤饼的阻力滤饼的阻力R Rc c可以用（可以用（可以用（可以用（2.62.6）来描述）来描述）来描述）来描述 R Rc c= = o o(V/A) (2.6)(V/A) (2.6)- represents the specific cake resistance - represents th

43、e specific cake resistance 滤饼的阻力特性滤饼的阻力特性滤饼的阻力特性滤饼的阻力特性 o o - the mass of cake solids per volume of filtrate - the mass of cake solids per volume of filtrate 单位体积滤液含固体滤饼量单位体积滤液含固体滤饼量单位体积滤液含固体滤饼量单位体积滤液含固体滤饼量2828大家好大家好 Substituted Substituted of of (2.6) (2.6) into into (2.5). (2.5). Differential Diff

44、erential equation equation for incompressible cake is:for incompressible cake is: 把方程（把方程（把方程（把方程（2.62.6）代入（）代入（）代入（）代入（2.52.5）得到：）得到：）得到：）得到：(1/A)*dV/dt=(1/A)*dV/dt= P/(P/(o o(V/A)+R(V/A)+Rmm) ( 2.7) ) ( 2.7) The equation is subject to the initial condition The equation is subject to the initial co

45、ndition 初始条件为：初始条件为：初始条件为：初始条件为： T=0 V=0 (2.8)T=0 V=0 (2.8) This This condition condition says says that that at at the the start start of of the the experiment, no solution has been filtered. experiment, no solution has been filtered. 开始时没有滤液被过滤开始时没有滤液被过滤开始时没有滤液被过滤开始时没有滤液被过滤2929大家好大家好 (2.7) integra

46、ted and rearranged to give (2.7) integrated and rearranged to give （2.72.7）积分后整理得）积分后整理得）积分后整理得）积分后整理得(At/V)=K(V/A)+B (2.9)(At/V)=K(V/A)+B (2.9)K=K=o o/(2/(2 P) (2.10)P) (2.10)B=RB=Rmm/ / P (2.11)P (2.11)thus the plot of (At/V) versus (V/A) should be linear. thus the plot of (At/V) versus (V/A) shou

47、ld be linear. 用用用用At/VAt/V对对对对 V/AV/A作图应该是线性的。作图应该是线性的。作图应该是线性的。作图应该是线性的。K- the slope is a function of the pressure drop and of the properties of the K- the slope is a function of the pressure drop and of the properties of the cakecake； 斜率斜率斜率斜率K K是压降是压降是压降是压降P P及滤饼特性及滤饼特性及滤饼特性及滤饼特性 、 o o的函数的函数的函数的函

48、数B- the Intercept is independent of the properties of the cake, but it is B- the Intercept is independent of the properties of the cake, but it is proportional to the mediums resistance, usually Rproportional to the mediums resistance, usually Rmm is insignificant. is insignificant. 截距截距截距截距B B与滤饼特性

49、无关，但它正比于介质阻力与滤饼特性无关，但它正比于介质阻力与滤饼特性无关，但它正比于介质阻力与滤饼特性无关，但它正比于介质阻力R Rmm。通常。通常。通常。通常R Rmm可忽略不计可忽略不计可忽略不计可忽略不计3030大家好大家好Eq.(2.9) becomes simpleEq.(2.9) becomes simpleEq.(2.9) becomes simpleEq.(2.9) becomes simple方程（方程（方程（方程（2.92.92.92.9）可简化为：）可简化为：）可简化为：）可简化为： t t t t(o/(2P)*(V/A)(o/(2P)*(V/A)(o/(2P)*(V/

50、A)(o/(2P)*(V/A)2 2 2 2 (2.12) (2.12) (2.12) (2.12) These equations are valid for incompressible These equations are valid for incompressible These equations are valid for incompressible These equations are valid for incompressible cakes.cakes.cakes.cakes. （该式仅适合不可压缩的滤饼）（该式仅适合不可压缩的滤饼）（该式仅适合不可压缩的滤饼）（该

51、式仅适合不可压缩的滤饼）3131大家好大家好2 2 2 2、 Compressible cakeCompressible cake 可压缩的滤饼可压缩的滤饼可压缩的滤饼可压缩的滤饼 Almost all cakes formed of biological materials are Almost all cakes formed of biological materials are compressible, and so cannot be described with the compressible, and so cannot be described with the simpl

52、e equation just outlined. As these cakes simple equation just outlined. As these cakes compress, filtration rates drop. This in turn results in compress, filtration rates drop. This in turn results in compromised economics. compromised economics. 绝大多数生物滤饼都可压缩，因此，不能仅仅用作图法的简绝大多数生物滤饼都可压缩，因此，不能仅仅用作图法的简绝

53、大多数生物滤饼都可压缩，因此，不能仅仅用作图法的简绝大多数生物滤饼都可压缩，因此，不能仅仅用作图法的简单方法来描述，滤饼可压缩，则过滤速度降低，能耗增大。单方法来描述，滤饼可压缩，则过滤速度降低，能耗增大。单方法来描述，滤饼可压缩，则过滤速度降低，能耗增大。单方法来描述，滤饼可压缩，则过滤速度降低，能耗增大。3232大家好大家好 To estimate the effects of compressibility, we assume that To estimate the effects of compressibility, we assume that the cake resista

54、nce is a function of the pressure drop.the cake resistance is a function of the pressure drop. 为了估计可压缩性的影响，我们假设滤饼阻力为了估计可压缩性的影响，我们假设滤饼阻力为了估计可压缩性的影响，我们假设滤饼阻力为了估计可压缩性的影响，我们假设滤饼阻力 是压降的函数。是压降的函数。是压降的函数。是压降的函数。 =(=( P)P)s s (2.13) (2.13)- a constant related largely to the size & shape of the - a constant

55、related largely to the size & shape of the particles, forming the cake. particles, forming the cake. 是一个与滤饼组成、粒子大小和形状相关的常数是一个与滤饼组成、粒子大小和形状相关的常数是一个与滤饼组成、粒子大小和形状相关的常数是一个与滤饼组成、粒子大小和形状相关的常数s sthe cake compressibility the cake compressibility 滤饼的压缩系数滤饼的压缩系数滤饼的压缩系数滤饼的压缩系数 s=0 a rigid & highly incompressib

56、le cake s=0 a rigid & highly incompressible cake 理想的不可压缩理想的不可压缩理想的不可压缩理想的不可压缩滤饼滤饼滤饼滤饼 s=1 a highly compressible cake s=1 s=1 a highly compressible cake s=1 高度可压缩滤饼高度可压缩滤饼高度可压缩滤饼高度可压缩滤饼 s=0.1-0.8 in practice s=0.1-0.8 in practice （实践中，（实践中，（实践中，（实践中，s s的变化范围是的变化范围是的变化范围是的变化范围是0.1-0.80.1-0.8）3333大家好大家

57、好Valuesofsarehigh,weshouldconsiderpretreatingthefeedwithfilteraids.当s的数值很高时，须加入助滤剂对原液进行预处理。Values of s & are most easily determined by plotting Values of s & are most easily determined by plotting the logarithm of versus the logarithm of the logarithm of versus the logarithm of P as shown P as shown

58、 in fig.(2.2).in fig.(2.2). 为计算出为计算出为计算出为计算出s s和和和和，可用，可用，可用，可用loglog对对对对loglog P P作图，如图作图，如图作图，如图作图，如图2.22.2：Slope=slogPlogFigCakeresistanceversuspressuredrop3434大家好大家好C、 Continuous Rotary Filter 连续旋转式过滤机连续旋转式过滤机 A filtration cycle on this filter consists of three chiefs. A filtration cycle on this

59、 filter consists of three chiefs. 一个完整的过滤过程主要为三个步骤一个完整的过滤过程主要为三个步骤一个完整的过滤过程主要为三个步骤一个完整的过滤过程主要为三个步骤a. cake formation a. cake formation 滤饼的形成滤饼的形成滤饼的形成滤饼的形成b. cake washing to remove either valuable or unwanted b. cake washing to remove either valuable or unwanted solutes. solutes. 洗涤滤饼以除去有用或不需要的溶质洗涤滤饼

60、以除去有用或不需要的溶质洗涤滤饼以除去有用或不需要的溶质洗涤滤饼以除去有用或不需要的溶质c. cake discharge c. cake discharge 滤饼的清除滤饼的清除滤饼的清除滤饼的清除3535大家好大家好DryWashImmersionKnifeCakeFeedRotaryvacuumfilter真空旋转过滤机大家好we first consider the cake formation which begins as the rotating we first consider the cake formation which begins as the rotating d

61、rum first drops into the broth.drum first drops into the broth. 滤饼形成是从转鼓一开始接触培养基开始的滤饼形成是从转鼓一开始接触培养基开始的滤饼形成是从转鼓一开始接触培养基开始的滤饼形成是从转鼓一开始接触培养基开始的we assume that the resistance of the filter medium Rwe assume that the resistance of the filter medium Rmm is negligible, is negligible, so that we can use equa

62、tion (2.5) the basic expression for filtration. so that we can use equation (2.5) the basic expression for filtration. 假设过滤介质的阻力假设过滤介质的阻力假设过滤介质的阻力假设过滤介质的阻力R Rmm可忽略不计，式（可忽略不计，式（可忽略不计，式（可忽略不计，式（2.52.5）可以用下式表示：）可以用下式表示：）可以用下式表示：）可以用下式表示： (1/A)*dV/dt = (1/A)*dV/dt = P/( RP/( Rc c) (3.1) (3.1)initial con

63、dition that is initial condition that is 初始条件是初始条件是初始条件是初始条件是 t=0 v=0 (3.2)t=0 v=0 (3.2)3737大家好大家好 We rewrite RWe rewrite Rc c for a compressible cake by combining (2.6) for a compressible cake by combining (2.6) & (2.13)& (2.13) 结合方程（结合方程（结合方程（结合方程（2.62.6）和（）和（）和（）和（2.132.13）可以改写滤饼阻力）可以改写滤饼阻力）可以改写滤

64、饼阻力）可以改写滤饼阻力R Rc c为：为：为：为： R Rc c = = o o (V/A) (V/A) = =o o(V/A)(V/A)( P)P)s s (3.3) (3.3)t tf f=(=(o o/(2/(2 P P1-s1-s)*(V)*(Vf f/A) /A) 2 2 (3.4) (3.4) t tf f- the cake formation time - the cake formation time 滤饼形成时间滤饼形成时间滤饼形成时间滤饼形成时间 V Vf f- the volume of filtrate collected during that period.-

65、the volume of filtrate collected during that period. 滤饼形成期间被集中的滤液体积（滤液流量）滤饼形成期间被集中的滤液体积（滤液流量）滤饼形成期间被集中的滤液体积（滤液流量）滤饼形成期间被集中的滤液体积（滤液流量）3838大家好大家好This relationship is sometimes written in terms of the This relationship is sometimes written in terms of the cycle time:cycle time: 这个关系有时也可用旋转周期这个关系有时也可用旋转

66、周期这个关系有时也可用旋转周期这个关系有时也可用旋转周期t tc c来表示：来表示：来表示：来表示： t tf f=t=tc c （3.53.5）the fraction of time that the filter is submerged. the fraction of time that the filter is submerged. That is the fraction of the cycle devoted to cake That is the fraction of the cycle devoted to cake formation formation 过滤器被浸

67、渍的时间分数，即旋转周期形成滤饼所用的时过滤器被浸渍的时间分数，即旋转周期形成滤饼所用的时过滤器被浸渍的时间分数，即旋转周期形成滤饼所用的时过滤器被浸渍的时间分数，即旋转周期形成滤饼所用的时间分数间分数间分数间分数t tc c- the cycle time - the cycle time 旋转周期旋转周期旋转周期旋转周期 3939大家好大家好We find a relation for filtration flux expressed in We find a relation for filtration flux expressed in terms of cycle time: t

68、erms of cycle time: 用旋转周期表示为：用旋转周期表示为：用旋转周期表示为：用旋转周期表示为：V Vf f/(At/(Atc c)=(2()=(2( P P1-s1-s) /( ) /( o o t tc c) )0.5 0.5 （3.63.6）4040大家好大家好1、cake washing（滤饼的洗涤）（滤饼的洗涤）After formation, the cake contains a significant After formation, the cake contains a significant amount of solute-rich liquid bro

69、th. This broth is amount of solute-rich liquid broth. This broth is usually removed by washing the cake. usually removed by washing the cake. 滤饼形成以后，滤饼中还含有许多溶质需要进一步洗涤。滤饼形成以后，滤饼中还含有许多溶质需要进一步洗涤。滤饼形成以后，滤饼中还含有许多溶质需要进一步洗涤。滤饼形成以后，滤饼中还含有许多溶质需要进一步洗涤。4141大家好大家好The washing has two functions：洗涤有两个作用：洗涤有两个作用：Fi

70、rst, it displays the solution-rich broth trapped in First, it displays the solution-rich broth trapped in pores in the cake.pores in the cake. 将孔中含有的发酵液洗出；将孔中含有的发酵液洗出；将孔中含有的发酵液洗出；将孔中含有的发酵液洗出；Second, Second, it it allows allows diffusion diffusion of of solute solute out out of of the the biomass bio

71、mass in in the the cake. cake. Such Such diffusion diffusion will will enhance enhance recovery, if the desired product is in the biomass.recovery, if the desired product is in the biomass. 滤滤滤滤饼饼饼饼中中中中，溶溶溶溶质质质质可可可可以以以以从从从从生生生生物物物物机机机机体体体体中中中中扩扩扩扩散散散散出出出出，如如如如果果果果目目目目标标标标产产产产物存在于生物机体中，这种扩散可以提高回收。物存在

72、于生物机体中，这种扩散可以提高回收。物存在于生物机体中，这种扩散可以提高回收。物存在于生物机体中，这种扩散可以提高回收。4242大家好大家好Two factors are involved in the washing： 两个因素两个因素:The first is that fraction of soluble material The first is that fraction of soluble material remaining after the wash, this governs the remaining after the wash, this governs the

73、volume of wash liquid required.volume of wash liquid required. 一是洗涤之后残留在滤饼中的可溶物质的部分，这个一是洗涤之后残留在滤饼中的可溶物质的部分，这个一是洗涤之后残留在滤饼中的可溶物质的部分，这个一是洗涤之后残留在滤饼中的可溶物质的部分，这个部分决定着所需洗液的体积部分决定着所需洗液的体积部分决定着所需洗液的体积部分决定着所需洗液的体积The rate at which wash liquid passed through the cakethis The rate at which wash liquid passed th

74、rough the cakethis rate of wash controls the time of the cycle devoted to rate of wash controls the time of the cycle devoted to washing. washing. 洗液通过过滤饼速率，这个速率控制着时间洗液通过过滤饼速率，这个速率控制着时间洗液通过过滤饼速率，这个速率控制着时间洗液通过过滤饼速率，这个速率控制着时间4343大家好大家好The function of soluble material remaining is often related to The

75、function of soluble material remaining is often related to the volumes of wash liquid by the equation. the volumes of wash liquid by the equation. 残留可溶物的分数残留可溶物的分数残留可溶物的分数残留可溶物的分数常与洗液体积有关常与洗液体积有关常与洗液体积有关常与洗液体积有关 r=(1-)r=(1-)n n (3.7)(3.7)r-the ratio of solubles remaining after the wash to that origi

76、nally present in the r-the ratio of solubles remaining after the wash to that originally present in the cake prior to the wash. rcake prior to the wash. r为洗涤之后的滤饼中溶质含量与洗涤之前滤饼中最初溶质含量为洗涤之后的滤饼中溶质含量与洗涤之前滤饼中最初溶质含量为洗涤之后的滤饼中溶质含量与洗涤之前滤饼中最初溶质含量为洗涤之后的滤饼中溶质含量与洗涤之前滤饼中最初溶质含量比。比。比。比。n-the volume of wash liquid di

77、vided by the volume of the liquid retained in the n-the volume of wash liquid divided by the volume of the liquid retained in the cake. cake. 洗液的体积与滤饼中残液的体积之比洗液的体积与滤饼中残液的体积之比洗液的体积与滤饼中残液的体积之比洗液的体积与滤饼中残液的体积之比-washing efficiency of the cake -washing efficiency of the cake 滤饼的洗涤效率滤饼的洗涤效率滤饼的洗涤效率滤饼的洗涤效率th

78、e fraction r varies from 0the fraction r varies from 01.1.lower values of r correspond to more effective washing.lower values of r correspond to more effective washing. r r值越低，洗涤效果越好值越低，洗涤效果越好值越低，洗涤效果越好值越低，洗涤效果越好 if =0 r=1 we get no reduction of solubles. no matter what volume of wash is if =0 r=1 w

79、e get no reduction of solubles. no matter what volume of wash is used. used. 如果如果如果如果=0 r=1=0 r=1，此时不论使用多少洗液均没有效果，此时不论使用多少洗液均没有效果，此时不论使用多少洗液均没有效果，此时不论使用多少洗液均没有效果 if r=0 =1 more effective washing. if r=0 =1 more effective washing. 洗涤效果很好洗涤效果很好洗涤效果很好洗涤效果很好 Equation (3.7) is an empirical result from a

80、variety of filtrations. Equation (3.7) is an empirical result from a variety of filtrations. 式式式式3.73.7是大量实践得到的经验方程式是大量实践得到的经验方程式是大量实践得到的经验方程式是大量实践得到的经验方程式4444大家好大家好We may wonder how well such an empiricism works for We may wonder how well such an empiricism works for bioseparations . bioseparations

81、 . 我们会思考该方程对于生物分离的准确性我们会思考该方程对于生物分离的准确性我们会思考该方程对于生物分离的准确性我们会思考该方程对于生物分离的准确性One test of the empiricism is given in Fig on next slide for a One test of the empiricism is given in Fig on next slide for a beer containing the antibiotic in a cake of bacteria. The figure is beer containing the antibiotic

82、in a cake of bacteria. The figure is a plot of the logarithm of r versus n, the straight lines on this a plot of the logarithm of r versus n, the straight lines on this plot, for efficiencies, have slopes of log(1-).plot, for efficiencies, have slopes of log(1-). 滤饼中包含抗生素的发酵液的过滤，图由滤饼中包含抗生素的发酵液的过滤，图由

83、滤饼中包含抗生素的发酵液的过滤，图由滤饼中包含抗生素的发酵液的过滤，图由logrlogr对应对应对应对应n n组成，对于不同效组成，对于不同效组成，对于不同效组成，对于不同效率，有不同的斜率率，有不同的斜率率，有不同的斜率率，有不同的斜率loglog（1-1-）log r=nlog(1-) log rlog r=nlog(1-) log rn slope=log(1-)n slope=log(1-)4545大家好大家好pH5.0pH9.300.020.040.100.200.400.601.001.02.03.00.900.800.600.400.20WASH LIQUID / RETAINE

84、D LIQUID nRETAINED SOLUTES / ORIGINAL SOLUTES rEfficiencyofwashing洗涤效率大家好Data for measurements at two values of pH show that Data for measurements at two values of pH show that efficiency does vary with pH.efficiency does vary with pH. 两个不同两个不同两个不同两个不同pHpH值下的测量数据说明效率随着值下的测量数据说明效率随着值下的测量数据说明效率随着值下的测量

85、数据说明效率随着pHpH变化而变化变化而变化变化而变化变化而变化The The scatter scatter of of these these data data is is typical typical and and illustrates illustrates the the accuracy of the empirical Fig(3.7).accuracy of the empirical Fig(3.7). 这这这这些些些些数数数数据据据据的的的的离离离离散散散散度度度度是是是是典典典典型型型型的的的的，很很很很好好好好的的的的表表表表示示示示了了了了经经经经验验验验式式

86、式式3.73.7的的的的准准准准确确确确性。性。性。性。Thus we can estimate how much wash liquid will be Thus we can estimate how much wash liquid will be needed to wash the cake . needed to wash the cake . 我们可以估计洗涤滤饼所需要洗涤液的用量。我们可以估计洗涤滤饼所需要洗涤液的用量。我们可以估计洗涤滤饼所需要洗涤液的用量。我们可以估计洗涤滤饼所需要洗涤液的用量。4747大家好大家好We now turn to how fast this l

87、iquid will flow though the We now turn to how fast this liquid will flow though the cake , which is the second key factors.cake , which is the second key factors. 现在我们开始讨论另一个因素现在我们开始讨论另一个因素现在我们开始讨论另一个因素现在我们开始讨论另一个因素: :流过滤饼的流速。流过滤饼的流速。流过滤饼的流速。流过滤饼的流速。The wash liquid contains no additional solids, so

88、the The wash liquid contains no additional solids, so the flow of wash liquid will be constant and equal to the flow of wash liquid will be constant and equal to the final instantaneous filtrate rate at the end of the cake final instantaneous filtrate rate at the end of the cake formation. This rate

89、 isformation. This rate is 洗液不包含所加的固体物，因此，洗液的流量是一个常量，洗液不包含所加的固体物，因此，洗液的流量是一个常量，洗液不包含所加的固体物，因此，洗液的流量是一个常量，洗液不包含所加的固体物，因此，洗液的流量是一个常量，且等于滤饼形成的最后瞬间过滤液的速率，这个速率是：且等于滤饼形成的最后瞬间过滤液的速率，这个速率是：且等于滤饼形成的最后瞬间过滤液的速率，这个速率是：且等于滤饼形成的最后瞬间过滤液的速率，这个速率是： v vww /A=2( /A=2( p)p)1-s1-s / / 0 0 0 0 1/21/2(t (tww) )1/21/2 (3.8

90、(3.8）v vww- the volume of wash water required - the volume of wash water required 所需的洗液体积所需的洗液体积所需的洗液体积所需的洗液体积 t tww- the time required for washing - the time required for washing 洗涤时间洗涤时间洗涤时间洗涤时间4848大家好大家好 In many cases, we may find it useful to divide this In many cases, we may find it useful to d

91、ivide this result by eq(3.9), to obtain:result by eq(3.9), to obtain: 许多情况下，通过式许多情况下，通过式许多情况下，通过式许多情况下，通过式3.93.9得到的结果是十分有用的得到的结果是十分有用的得到的结果是十分有用的得到的结果是十分有用的 t tw w / t/ tf f =2 v=2 vww/ v/ vf f (3.9) (3.9) =2(v =2(vww/v/vr r)( v)( vr r/ v/ vf f) ) =2nf (3.10) =2nf (3.10)V Vr rthe volume of liquid re

92、tained by the cake the volume of liquid retained by the cake 滤饼中残液的体积滤饼中残液的体积滤饼中残液的体积滤饼中残液的体积 f fthe ratio of this volume to the volume of filtratethe ratio of this volume to the volume of filtrate 体积体积体积体积V Vr r占总滤液体积的分数占总滤液体积的分数占总滤液体积的分数占总滤液体积的分数4949大家好大家好Equipment for filtration various widely, f

93、rom the Equipment for filtration various widely, from the conventional plat-and-frame press to rotary vacuum conventional plat-and-frame press to rotary vacuum filters. filters. 过滤设备从传统的板框式过滤机到旋转式真空过滤设备，过滤设备从传统的板框式过滤机到旋转式真空过滤设备，过滤设备从传统的板框式过滤机到旋转式真空过滤设备，过滤设备从传统的板框式过滤机到旋转式真空过滤设备，种类很多。种类很多。种类很多。种类很多。D、

94、EquipmentforConventionalFiltration传统的过滤设备5050大家好大家好5151大家好大家好5252大家好大家好The most common, the plate-and-frame press, contains caulked, The most common, the plate-and-frame press, contains caulked, metal septa and a recessed cake space.metal septa and a recessed cake space. 最普遍的是板框式过滤机，有可填充的、金属隔片的和凹显空间

95、滤饼的。最普遍的是板框式过滤机，有可填充的、金属隔片的和凹显空间滤饼的。最普遍的是板框式过滤机，有可填充的、金属隔片的和凹显空间滤饼的。最普遍的是板框式过滤机，有可填充的、金属隔片的和凹显空间滤饼的。Other types have flushed plates that can be used with a paper or Other types have flushed plates that can be used with a paper or cloth filter medium separated by open frames where the cake is cloth f

96、ilter medium separated by open frames where the cake is formed. This type of filter is used where a relatively dry cake formed. This type of filter is used where a relatively dry cake discharged is desired. It should not be used where there are toxic discharged is desired. It should not be used wher

97、e there are toxic fumes or biohazards.fumes or biohazards. 其它类型还有平的金属板，可用滤纸或滤布过滤介质在开放式框架上分其它类型还有平的金属板，可用滤纸或滤布过滤介质在开放式框架上分其它类型还有平的金属板，可用滤纸或滤布过滤介质在开放式框架上分其它类型还有平的金属板，可用滤纸或滤布过滤介质在开放式框架上分离形成滤饼。这种过滤机适合于相对的干性滤饼，能被清除，不适合有离形成滤饼。这种过滤机适合于相对的干性滤饼，能被清除，不适合有离形成滤饼。这种过滤机适合于相对的干性滤饼，能被清除，不适合有离形成滤饼。这种过滤机适合于相对的干性滤饼，能被

98、清除，不适合有毒气和生物危害物的滤饼。毒气和生物危害物的滤饼。毒气和生物危害物的滤饼。毒气和生物危害物的滤饼。5353大家好大家好The other three filters are enclosed and hence The other three filters are enclosed and hence can be used with aerosols or biohazards. can be used with aerosols or biohazards. Because their use is labor intensive, they are Because thei

99、r use is labor intensive, they are used on for relatively small scale work.used on for relatively small scale work. 其它三种过滤机是封闭型的，可过滤悬浮颗粒和有生物其它三种过滤机是封闭型的，可过滤悬浮颗粒和有生物其它三种过滤机是封闭型的，可过滤悬浮颗粒和有生物其它三种过滤机是封闭型的，可过滤悬浮颗粒和有生物危害物质，一般用于小规模生产。危害物质，一般用于小规模生产。危害物质，一般用于小规模生产。危害物质，一般用于小规模生产。5454大家好大家好思考题：思考题：思考题：思考题：1.

100、 1. 发酵液进行过滤的目的是什么？影响发酵液过滤速度的因素有哪些？发酵液进行过滤的目的是什么？影响发酵液过滤速度的因素有哪些？发酵液进行过滤的目的是什么？影响发酵液过滤速度的因素有哪些？发酵液进行过滤的目的是什么？影响发酵液过滤速度的因素有哪些？2. 2. 发酵液过滤的方法有哪些？并简述各种方法的类型、特点及应用。发酵液过滤的方法有哪些？并简述各种方法的类型、特点及应用。发酵液过滤的方法有哪些？并简述各种方法的类型、特点及应用。发酵液过滤的方法有哪些？并简述各种方法的类型、特点及应用。3. 3. 如何进行过滤介质的选择和过滤条件的优化？如何进行过滤介质的选择和过滤条件的优化？如何进行过滤介质

101、的选择和过滤条件的优化？如何进行过滤介质的选择和过滤条件的优化？4. 4. 发酵液过滤所用的过滤机类型有哪些？并简述各种过滤机的结构、特发酵液过滤所用的过滤机类型有哪些？并简述各种过滤机的结构、特发酵液过滤所用的过滤机类型有哪些？并简述各种过滤机的结构、特发酵液过滤所用的过滤机类型有哪些？并简述各种过滤机的结构、特点和应用。点和应用。点和应用。点和应用。5. 5. 提高过滤压力和增大过滤面积是否为强化过滤的最有效措施提高过滤压力和增大过滤面积是否为强化过滤的最有效措施提高过滤压力和增大过滤面积是否为强化过滤的最有效措施提高过滤压力和增大过滤面积是否为强化过滤的最有效措施? ?6. 6. 针对不可压缩和可压缩滤饼进行过滤时间的公式推导以及可能的应用针对不可压缩和可压缩滤饼进行过滤时间的公式推导以及可能的应用针对不可压缩和可压缩滤饼进行过滤时间的公式推导以及可能的应用针对不可压缩和可压缩滤饼进行过滤时间的公式推导以及可能的应用计算计算计算计算5555大家好大家好结束5656大家好大家好