7/24/2019 QUIZ 1 (1)

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QUIZ 1

UNIT OPERATION

BKF3463

A 10% aqueous solution of NaOH at 37.8C and a flow rate of 13607.78 kg!r is to "e

#on#entrated to $0 wt% " e&a'oration 'ro#ess. A forward feed dou"le effe#t e&a'orator

sste( is used wit! t!e esti(ated o&erall !eat transfer #oeffi#ient of ) 1* +$$3 ,(+.- for

t!e first effe#t and )+* 186 ,(+.- for t!e se#ond effe#t. /!e "oiling 'oint rise and !eat of

solution #an "e #onsidered negligi"le. /!e &a'or s'a#e 'ressure of t!e se#ond effe#t is

3.38ka and t!e saturated stea( enters t!e first effe#t at 8+$. ka. /!e !eating area is

assu(ed to "e equal.

a Cal#ulate t!e a(ount of liquid and &a'or 'rodu#t fro( ea#! effe#t and t!e stea(

#onsu('tion in kg!r.(The difference between the assumed and exact values should

not be more than 10%)

(32 Marks)

b) Cal#ulate t!e rate of !eat transfer and !eat transfer area of ea#! effe#t. (The difference

between the average and exact values should not be more than 15%) (6 Marks)

# ,!at will !a''en to t!e e&a'oration sste( if t!e &a'or 'ressure in t!e se#ond effe#t

is in#reased +$ ka2 4'lain our answer.

(2 Marks)