Separation Processes

SEPARATION 1pt 1 In gas absorption, when the conditions at the bottom of the tower are xed and the gas ow rate is gi!en, the "imiting ow rate based on e#$i"ibri$m conditions that wi"" re#$ire innite"% ta"" tower is Se"ect one& a' minim$m "i#$id ow rate

b' maxim$m gas ow rate

c' minim$m gas ow rate

d' maxim$m "i#$id ow rate

(eedbac)  The correct answer answer is& maxim$m "i#$id ow rate rate * The ease of di+c$"t% of separating components b% disti""ation is determined b% the Se"ect one& a' re"ati!e !a"ati"it%

b' !iscosit%

c' weight fraction of the components

d' mo"efraction

(eedbac)  The correct answer answer is& re"ati!e !a"ati"it% !a"ati"it% - The rate e#$ation in terms of the gasphase mass transfer coe+cient transfer coe+cient is $sed in design ca"c$"ations instead of that in terms of the "i#$id phase is when Se"ect one& a' the tie "ine is hori.onta"

b' the so"$bi"it% of the so"$te in the so"!ent is !er% "ow

c' the contro""ing resistance is that of the "i#$id phase

d' the contro""ing resistance is that of the gas phase

(eedbac)  The correct answer answer is& the contro""ing resistance is that of the the gas phase / A deb$tani.er is a Se"ect one& a' si.e red$ction e#$ipmant

b' $id transfer e#$ipment

c' mass transfer e#$ipment transfer e#$ipment

d' heat transfer e#$ipment transfer e#$ipment

(eedbac)

 The correct answer answer is& mass transfer e#$ipment transfer e#$ipment 0 The mass transfer rate transfer rate of a materia" from one phase to another across an interface is increased b% Se"ect one& a' increassing

b' decreasing the dierence between the b$") concentration and the

concentration at the interface between the * phases

c' )eeping constant

d' ma)ing .ero

(eedbac)  The correct answer answer is& increassing 2 A $nit operation in which a so"$b"e component is remo!ed from an inert so"id b% a so"!ent which preferentia""% disso"!es the so"$b"e matter from the mixt$re is )nown as& Se"ect one& a' so"!ent extraction

b' sedimentation

c' adsorption

d' "eaching

(eedbac)  The correct answer answer is& adsorption 3 In a !ac$$m disti""ation co"$mn the !ac$$m is $s$a""% created b % a Se"ect one& a' !ac$$m p$mp

b' steam e4ecctor

c' centrif$ga" p$mpcompressor

(eedbac)  The correct answer answer is& !ac$$m p$mp 5 In this case a so"$te in a "i#$id so"$tion is remo!ed b% contacting with another "i#$id so"!ent which is re"ati!e"% immiscib"e with the so"$tion Se"ect one& a' Absorption

b' so"id "i#$id extraction

c' 6i#$id "i#$id extraction

(eedbac)  The correct answer answer is& 6i#$id "i#$id extraction extraction 7 8hen the re"ati!e !o"ati"% of * miscib"e are c"ose to 1'99 the components can be separated b% Se"ect one&

a' sedimentation

b' extracti!e disti""ation

c' simp"e fractionation

d' "ow press$re disti""ation

(eedbac)  The correct answer answer is& extracti!e disti""ation disti""ation 19 To impro!e the degree of separation of the more !o"ati"e component from the "ess !o"ati"e component thro$gh disti""ation the chemica" engineer ma%, witho$t changing the other !ariab"es' Se"ect one& a' increase the reboi"er temperat$re

b' increase the co"$mn press$re

c' red$ce the co"$mn press$re

d' increase the feed temperat$re

(eedbac)  The correct answer answer is& red$ce the co"$mn press$re press$re 11 :&&SEparation191&&The separation of a di"$te s"$rr% or s$spension b% gra!it% sett"ing into a c"ear $id and a s"$rr% of higher so"ids content is ca""ed ;;;;;: Se"ect one&

a' ("oatation

b' e!aporation

c' sedimentation

d' cr%sta""i.ation

(eedbac)  The correct answer is& e!aporation 1* A membrane separation process where the component from a heated "i#$id phase permeates thro$gh the membrane and is remo!ed $nder "ow press$re is Se"ect one& a' micro"tration

b' dia"%sis

c' re!erse osmosis

d' per!aporation

(eedbac)  The correct answer is& re!erse osmosis 1- In gas absorption,pac)ings are $sed Se"ect one&

a' to red$se the presss$re drop created b% the fo""owing gas

b' to increase the area of the contact between the gas and the "i#$id

c' to reinforce the absorption tower d$e to drag created b% the "i#$id and the

gas

d' to disseminate the heat generated to maintain isotherma" conditions

(eedbac)  The correct answer is& to increase the area of the contact between the gas and the "i#$id 1/ A binar% so"$tion, where A is a "ow boi"er,exhibiting a maxim$m boi"ing point, is s$b4ected to ash disti""ation' If the feed has a concentration in A "ess than the a.eotropic point, the concentration of the disti""ate wi"" be Se"ect one& a' same

b' higher in <

c' higher in A

(eedbac)  The correct answer is& higher in < 10 The temperat$re in a disti""ing co"$mn from bottom to top Se"ect one&

a' increase

b' decrease

c' maxim$m

d' between maxim$m and minim$m

(eedbac)  The correct answer is& maxim$m 12 Increasing the operating press$re of a disti""ation co"$mn Se"ect one& a' sharpens separation

b' re#$ires "ess heat in the feed heater

c' does not ma)e a dierence in components separation

d' ma)es separation di+c$"t

(eedbac)  The correct answer is& ma)es separation di+c$"t 13 The degrees of freedom associated with ternar% disti""ation process according to the =ibb>s phase r$"e is Se"ect one&

a' 0

b' *

c' /

d' -

(eedbac)  The correct answer is& 15 In a disti""ing co"$mn the highest press$re wi"" be at & Se"ect one& a' the top

b' the bottom

c' the feed p"ate

d' between the feed p"ate and the top

(eedbac)  The correct answer is& the bottom 17 The press$re drop a"ong a pac)ed tower is Se"ect one& a' direct"% proportiona" to the s#$are of the mass ow rate

b' in!erse"% proportiona" to the s#$are of the mass ow rate

c' direct"% proportiona" to the mass ow rate

d' in!erse"% proportiona" to the mass ow rate

(eedbac)  The correct answer is& direct"% proportiona" to the s#$are of the mass ow rate *9 8hen the "i#$id ow rate is xed and the composition of the "i#$id and the gas at the bottom of the absorption tower are xed , the "imiting ow rate to gi!e innite"% ta"" tower becomes Se"ect one& a' the minim$m ow of the rate of the !apor

b' the minim$m "oading of the "i#$id

c' the maxim$m ooding !e"ocit% of the !apor

d' the maxim$m ow of the rate of the !apor

(eedbac)  The correct answer is& the minim$m ow of the rate of the !apor *1 In a gas absorption co"$mn the press$re of the "ean gas is expected to be Se"ect one& a' higher than

b' "ower than

c' the same as

d' do$b"e the press$re of the rich gas entering the co"$mn

(eedbac)  The correct answer is& "ower than ** It is not !er% nessesar% to correct the rate e#$ation for the phase drift enco$ntered d$ring gas absorption,since the height ca"c$"ated is Se"ect one& a' based on the same percentage reco!er% an%wa%

b' based on e#$imo"a" co$nter di$sion an%wa%

c' s"ight"% $nder designed an%wa%

d' s"ight"% o!erdesigned an%wa%

(eedbac)  The correct answer is& s"ight"% o!erdesigned an%wa% *- In a twocomponent ash disti""ation process, when the operating press$re is specied, the concentration of the disti""ate ma% be impro!ed in the more !o"ati"e component if  Se"ect one& a' the amo$nt of disti""ation is increase

b' the operating temperat$re is decrease

c' none of the abo!e

d' the operating temperat$re is increase

(eedbac)  The correct answer is& the operating temperat$re is decrease */ 8hen the feed to the co"$mn is a sat$rated "i#$id,the feed "ine is Se"ect one& a' !ertica"

b' inc"ined to the right

c' hori.onta"

d' inc"ined to "eft

(eedbac)  The correct answer is& !ertica" *0 ?ac$$m disti""ation is resorted to in order to Se"ect one& a' $se the thinner she"" p"ates for the co"$mn

b' red$ce the n$mber of tra%s in the co"$mn

c' obtain more bottom prod$cts

d' a!oid high feed and reboi"er temperat$res

(eedbac)  The correct answer is& red$ce the n$mber of tra%s in the co"$mn *2 In teaching, the partic"e si.e in$ences the extraction rate' The sma""er si.e, I the greater is the interfacia" area between the so"id and the "i#$id II the sma""er is the distance the so"$te m$st di$se written the so"id III the "ower is the rate of transfer of materia" Se"ect one& a' both I @ II

b' both II and III

c' I on"%

d' II on"%

(eedbac)  The correct answer is& both I @ II *3 The primar% reason wh% c"ose team is $sed in an open batch steam disti""ation is to& Se"ect one& a' s$pp"% the heat needed b% !apori.ing "i#$id

b' increase the operating temperat$re

c' increase the operating press$re

d' increase the n$mber of degrees of freedom

(eedbac)  The correct answer is& increase the n$mber of degrees of freedom *5 The recent a!ai"abi"it% of digita" comp$ters res$"ted in the de!e"opment of man% ana"%tica" expressions for the e!a"$ation of !a"$es'8hich of the items be"ow is a so$rce of ana"itica" method for !a"$es& i'NRT6 ii'8i"son e#s' iii'BNICBAD i!=PA Se"ect one& a' iii on"%

b' I and i! on"%

c' none among the choices

d' a"" are so$rces

(eedbac)  The correct answer is& a"" are so$rces *7 At minim$m re$x ratio, the n$mber of p"ates is Se"ect one& a' minim$m

b' between minim$m and maxim$m

c' innite

d' maxim$m

(eedbac)  The correct answer is& innite -9 In the remo!a" of a so"$te from a water phase b% "i#$id extraction $sing a membrane, it is ad!antageo$s to $se Se"ect one& a' an ass%metric membrane

b' a po"%mer membrane

c' an% poro$s membrane

d' a h%drophobic membrane

(eedbac)  The correct answer is& a h%drophobic membrane -1 In a simp"e batch disti""ation, the boi"ing point of the disti""ate prod$ct compared to the resid$e is Se"ect one& a' the same

b' higher

c' "ower

(eedbac)  The correct answer is& "ower -* 8hen the two"m theor% is app"ied to gas absorption, the o!era"" resistance can be expressed in terms of the indi!id$a" resistance in the form 1%a F 1)%aGm)xa This is possib"e beca$se of an important ass$mption'This ass$mption is Se"ect one& a' the tie "ine has a s"ope between 9 and 1@

b' the operating "ine is "inear

c' the so"$te forms an idea" so"$tion with the so"!ent

d' the s"ope of the e#$i"ibri$m c$r!e near the tie "ine is "inear

(eedbac)  The correct answer is& the s"ope of the e#$i"ibri$m c$r!e near the tie "ine is "inear -- 8hen the re"ati!e !o"ati"% of * miscib"e are c"ose to 1'99 the components can be separated b% Se"ect one& a' simp"e fractionation

b' extracti!e disti""ation

c' "ow press$re disti""ation

d' sedimentation

(eedbac)  The correct answer is& extracti!e disti""ation -/ The ma4or prob"em in "eaching is to promote di$tion of the so"$te o$t of the so"id and into the "i#$id'The most eecti!e wa% of doing this is& Se"ect one& a' to red$ce the so"id to the sma""est si.e feasib"e

b' to $se co$nter c$rrent operation

c' none of the abo!e

d' to $se cross ow e!aporation

(eedbac)  The correct answer is& to red$ce the so"id to the sma""est si.e feasib"e -0 Hc DabeThie"e method to determine the theoretica" n$mber of stages, ma% be app"ied with acceptab"e res$"ts if  Se"ect one& a' heat "osses and heat of so"$tion are !er% neg"igib"ee

b' the components ha!e high re"ati!e !o"ati"it%

c' the components ha!e dierent boi"ing points

d' the s%stem fo""ow Tro$ton@

(eedbac)  The correct answer is& the s%stem fo""ow Tro$ton@ -2 In disti""ation where there are two components and both components are fo$nd in both phases,on"% one !ariab"e e'g', "i#$id pphase concentration, can be changed independent"% if the press$re is xed and temperat$re and !apor phase concentration wi"" fo""ow' Is this Se"ect one& a' (A6SE

b' tr$e

(eedbac)  The correct answer is& tr$e -3 This concerns the remo!a" of a so"$te s$ch as a sa"t from a so"$tion b% precipitating the so"$te from the so"$tion Se"ect one& a' Ji$sion

b' e!aporation

c' cr%sta""i.ation

d' dr%ing

(eedbac)  The correct answer is& cr%sta""i.ation -5In batch open steam disti""ation, the so"$tion to be open steam disti"""ed sho$"d be Se"ect one& a' s"ight"% immiscib"e in water

b' containing "arge non!o"ati"e imp$rities

c' comp"ete"% immiscib"e in water

d' miscib"e in water

(eedbac)  The correct answer is& comp"ete"% immiscib"e in water -7 The method of separating a partic$"ar gaseo$s component from a mixt$re of gases d$e to their dierences in so"$bi"it% in a "i#$id phase is Se"ect one& a' disti""ation

b' extraction

c' adsorption

d' absorption

(eedbac)

 The correct answer is& absorption /9 The re"ati!e !o"ati"it% of the mixt$re at the a.eotropic point where the so"$tion exhibits minim$m boi"ing point is Se"ect one& a' e#$a" to 1

b' greater than 1

c' "ess than 1

(eedbac)  The correct answer is& e#$a" to 1

/1 A 09K b% weight ben.eneto"$ene mixt$res is fed to a co"$mn at 159o( and 1 atm'  The condition of this feed is Se"ect one& a' s$b coo"ed

b' sat$rated "i#$id

c' !apor

d' mixt$re of "i#$id and !apor

(eedbac)  The correct answer is& s$b coo"ed

/* This process in!o"!es the separation of so"$te from a $id b% di$sion of this so"$te from a "i#$id or gas thro$gh a semipermeab"e membrane barrier to another "i#$id Se"ect one& a' Jisti""ation

b' membrane separation

c' absorption

(eedbac)  The correct answer is& membrane separation /- Agitation of the "i#$id in$ences the rate of extraction' Agitation osf so"!ent is important beca$se I it pre!ents sedimentation it increases edd% di$sion III it increases the transfer of materia" from the s$rface of the partic"es to the b$") of  so"$tion Se"ect one& a' I on"%

b' both I and II

c' II on"%

d' both II and III

(eedbac)  The correct answer is& both II and III

// In a simp"e batch disti""ation, the boi"ing point of the disti""ate prod$ct compared to the resid$e is Se"ect one& a' "ower

b' higher

c' the same

(eedbac)  The correct answer is& "ower /0 In a gas absorption tower, mass transfer occ$rs primari"%& Se"ect one& a' from the gas phase to the pac)ing

b' from the gas phase to the "i#$id phase

c' from the "i#$id phase to the gas phase

d' from the "i#$id phase to the pac)ing

(eedbac)  The correct answer is& from the "i#$id phase to the pac)ing /2 8hen the gas ow rate ind$ces ooding in a pac)ed co"$mn gas absober,this is best remedied if the percent reco!er% of the so"$te is to be maintained b% Se"ect one&

a' increasing the diameter of the co"$mn

b' increasing the height of the co"$mn

c' red$cing the !apor ow rate

d' red$cing the "i#$id ow rate

(eedbac)  The correct answer is& increasing the diameter of the co"$mn /3 In nonidea" "eaching conditions, the tie "ines s"ant to the right indicating that the so"$te is more high"% concentrated in the $nderow beaca$se' Se"ect one& a' the so"!ent and the so"$te are comp"ete"% miscib"e

b' of a partia""% miscib"e carrier or incomp"ete sett"ing

c' a"" of the choices

d' of e#$i"ibri$m so"$bi"it% or f in comp"ete "eaching

(eedbac)  The correct answer is& of e#$i"ibri$m so"$bi"it% or f in comp"ete "eaching /5 The temperat$re a"so aects the rate of extraction' In most cases, the so"$bi"it% of the materia" which is being extracted wi"" increase with temperat$re to I gi!e a higher rate of extraction II increase the di$sion coe+cient III pre!ention of en.%me action

Se"ect one& a' I on"%

b' both II and III

c' II on"%

d' both I and II

(eedbac)  The correct answer is& both I and II /5 In a twocomponent ash disti""ation process, when the operating press$re is specied, the concentration of the disti""ate ma% be impro!ed in the more !o"ati"e component if  Se"ect one& a' the operating temperat$re is decrease

b' the amo$nt of disti""ation is increase

c' the operating temperat$re is increase

d' none of the abo!e

(eedbac)  The correct answer is& the operating temperat$re is decrease /7 The temperat$re of the so"$tion Prob' * as disti""ation progress at constant operating press$re is

Se"ect one& a' constant

b' increasing

c' decreasing

(eedbac)  The correct answer is& constant 09 Thera are two $nderowo!erow "eaching conditions name"% idea" and non idea"'The idea" "eaching condition exist if& Se"ect one& a' a"" of the choices are correct

b' s$+cient contact time for the so"!ent to penetrate the so"$te comp"ete"% is

permitted

c' the carrier so"id is comp"ete"% inert and is not disso"!ed or entrained in the

so"!ent d' the so"$te is innite"% so"$b"e in the so"$b"e

(eedbac)  The correct answer is& a"" of the choices are correct 0* In the case of a straight or conca!e downward operating "ine and a straight or conca!e $pward e#$i"ibri$m "ine, the minim$m "i#$idrate is that at which the Se"ect one&

a' the operating "ine 4$st to$ches the e#$i"ibri$m "ine on top of the

tower

b' the s"ope of the operating "ine is sma""er than the e#$i"ibri$m "ine

c' the operating "ine 4$st to$ches the e#$i"ibri$m "ine at the bottom of the tower

d' the operating "ine intersects the e#$i"ibri$m "ine at the midd"e of the tower

(eedbac)  The correct answer is& the operating "ine 4$st to$ches the e#$i"ibri$m "ine at the bottom of the tower 0* In pac)ed co"$mns,the press$re drop for irrigated pac)ing is a"wa%s greater than the press$re drop for dr% pac)ings beca$se Se"ect one& a' the s$rface of dr% pac)ing is smoother

b' the ow area of dr% pac)ing is greater

c' none of the abo!e

d' the drag friction is "esser than the s)in friction for dr% pac)ing

(eedbac)  The correct answer is& the ow area of dr% pac)ing is greater

0- The dierence between stage operation LAM and a contin$o$s phase contact operation L