plate and frame heat exchanger_ss

7/21/2019 Plate and Frame Heat Exchanger_ss

1/51

PLATE AND FRAME HEATEXCHANGER


2/51

OUTLINE

Introduction Construction

Principle o Oper!tion

Applic!tions Ad"!nt!#es

Li$it!tions o Oper!tion

Co$p!rison o %it& 'TH Desi#n steps %it& 'ol"ed e(!$ple


3/51

INTRODUCTION

It is ! t)pe o co$p!ct &e!t e(c&!n#er

A pl!te &e!t e(c&!n#er is ! t)pe o &e!t

e(c&!n#er t&!t uses $et!l pl!tes totr!nser &e!t *et%een t%o luids


4/51

CON'TRUCTION

+!sed on t&eir construction pl!te !nd

r!$e &e!t e(c&!n#ers !re cl!ssiied into

,!- G!s.eted/pl!te

,*- 0elded1pl!te


5/51

GA'2ETED1PLATE HEAT

EXCHANGER,GPHE-

P!r!llel corru#!ted pl!tes cl!$ped in ! r!$e

%it& e!c& pl!te se!led *) #!s.ets !nd %it& our

corners ports3 one p!ir or e!c& o t&e t%o luids4

T&e luids !re !t !ll ti$es sep!r!ted *) 5

#!s.ets3 e!c& open to t&e !t$osp&ere4 G!s.et

!ilure c!nnot result in luid inter$i(in# *ut$erel) in le!.!#e to !t$osp&ere3 &ence !

protecti"e co"er is t&ere4


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7/51


8/51

CON'TRUCTION OF GPHE

Pl!tes

G!s.ets

Pl!te r!$e


9/51

PLATE'

Pl!te t&ic.ness is 647 to 648 $$

C&!nnel len#t&s !re 519 $eters

Pl!tes !re !"!il!*le in: 't!inless 'teel3Tit!niu$3 Tit!niu$1P!ll!diu$3 Nic.el
http://en.wikipedia.org/wiki/File:Plate_frame_2.png


10/51

PLATE'

PATTERN';- Induce tur*ulence or &i#& HT coeicient5-Reinorce$ent !nd pl!te support points t&!t

$!int!ins inter1pl!te sep!r!tion4

T


11/51

CHE=RON OR HERRING+ONE

Most co$$on t)pe

Corru#!tions !re pressed to s!$e dept&

!s pl!te sp!cin#

Oper!te !t Hi#& pressure

Corru#!tion dept& 9$$ to >$$

=elocit) 64; to ; $?s


12/51

CHE=RON CORRUGATION'


13/51


14/51

INTERMATING TROUGH PATTERN'

Pressed deeper t&!n sp!cin#

Fe%er connection points

Oper!te !t Lo%er pressure M!( c&!nnel #!p 9$$ to >$$

Min c&!nnel #!p ;4> $$ to 9 $$

=elocit) r!n#e in tur*ulent re#ion is 645 to 9 $?s


15/51


16/51

DIMPLE CORRUGATION'


17/51

GA'2ET'

G!s.ets li$it t&e $!(i$u$ oper!tin#te$per!ture or ! pl!te &e!t e(c&!n#er

M!teri!l selection depends upon

;-C&e$ic!l resist!nce

5-Te$per!ture resist!nce

9-'e!lin# properties

7-'&!pe o"er !n !ccept!*le period o ti$e


18/51

GA'2ET MATERIAL'

T)pic!l #!s.et $!teri!ls !re:

N!tur!l ru**er st)rene

Resin cured *ut)l

Co$pressed !s*estos i*er #!s.ets


19/51

FRAME'

Fr!$e $!teri!ls !re

;-C!r*on steel %it& ! s)nt&etic resin inis&

5-st!inless steel


20/51

0ELDED PLATE HEAT

EXCHAGER',0PHE-

De"eloped to o"erco$e t&e li$it!tions o

t&e #!s.et in GPHE

In!*ilt) o &e!t tr!nser !re! inspection

!nd $ec&!nic!l cle!nin# o t&!t sur!ce


21/51

OPERATION

C&!nnels !re or$ed *et%een t&e pl!tes!nd corner ports !re !rr!n#ed so t&!t t&et%o $edi! lo% t&rou#& !ltern!te c&!nnels4

T&e &e!t is tr!nserred t&rou#& t&e t&inpl!te *et%een t&e c&!nnels3 !nd co$pletecounter current lo% is cre!ted or &i#&estpossi*le eicienc)4 No inter$i(in# o t&e$edi! or le!.!#e to t&e surroundin#s %illt!.e pl!ce !s #!s.ets !round t&e ed#es ot&e pl!tes se!l t&e unit4


22/51


23/51


24/51

LIBUID1LIBUID 'ER=ICE'

It is %ell1suited to liuid?liuid duties in

tur*ulent lo%3 i4e4 ! luid suicientl)

"iscous to produce l!$in!r lo% in !

s$oot& sur!ce &e!t e(c&!n#er $!) %ell*e in tur*ulent lo% in PHE4

It &!s $!@or !pplic!tions in t&e ood

industr)4


25/51

CONDEN'ATION AND

=APORIATION

Condens!tion o "!por ,includin# ste!$-

!t $oder!te pressure3 s!) to 6 Psi3 is

!lso econo$ic!ll) &!ndled *) PHEs3 *ut

duties in"ol"in# l!r#e "olu$es o "er) lo%

pressure #!s or "!por !re *etter suited to

ot&er or$s o &e!t e(c&!n#ers


26/51

CENTRAL COOLING

It is t&e coolin# o ! closed circuit o res&

non1corrosi"e !nd non1oulin# %!ter or

use inside ! pl!nt3 *) $e!ns o *r!c.is&

%!ter4 Centr!l coolers !re $!de otit!niu$3 to %it&st!nd t&e *r!c.is& %!ter


27/51

AD=ANTAGE'

Co$p!ctness

Fle(i*ilit)

=er) &i#& &e!t tr!nser coeicients on*ot& sides o t&e e(c&!n#er

Close !ppro!c& te$per!tures !nd ull)counter1current lo%

E!se o $!inten!nce4 He!t tr!nser !re!c!n *e !dded or su*tr!cted %it& outco$plete dis$!ntlin# t&e euip$ent


28/51

CONTD44

E!se o inspection on *ot& sides

E!se o cle!nin#

'!"in#s in reuired lo% !re!

Lo% &old1up "olu$e

Lo% cost

No Loc!l o"er &e!tin# !nd possi*ilit) ost!#n!nt ones is !lso reduced

Foulin# tendenc) is less


29/51

LIMITATION'

Lo% Pressure

upto 966 psi

Lo% te$per!ture upto 966 F

Li$ited c!p!cit)

Li$ited pl!te sie 6465 s4$ to ;4> s4$


30/51

L!r#e dierence *?% lo% r!tes c!nt *e

&!ndled

Hi#& pressure drop

Potenti!l or le!.!#e


31/51

COMPARI'ON +ET0EEN PHE

AND 'THE

FEATURE'

Multiple dut)

Hold up "olu$eG!s.ets

$odiic!tions

PHE

Possi*le

Lo%On e!c& pl!te

E!s) *) !ddin#or re$o"in#pl!tes

'THE

I$possi*le

Hi#&On l!n#ed

@oints

i$possi*le


32/51

FEATURE' PHE 'THE

Rep!ir

Detection ole!.!#e

Access or

inspectionTi$e red4 oropenin#

Foulin#

'ensiti"it) to"i*r!tions

E!s) to repl!cepl!tes !nd #!s.ets

E!s) to detect

On e!c& side o

pl!te;> $in

;> to 56 o 'THENot sensiti"e

Reuires tu*eplu##in#

Diicult todetect

Li$ited

6 to 6 $in

'ensiti"e


33/51

DE'IGN 'TEP' 0ITH

'OL=ED EXAMPLE


34/51

'TATEMENT OF PRO+LEM

A pl!te &e!t e(c&!n#er %!s use to pre&e!t 7.#?s o do%t&er$ ro$ ;6 to J6KC %it& ! &ot%!ter condens!te t&!t %!s cooled ro$ > to6KC4Deter$ine t&e nu$*er o pl!tes reuiredor ! sin#le1p!ss counter lo% pl!te !nd r!$ee(c&!n#er4 Assu$e t&!t e!c& $ild st!inless1steel pl!te .%7>@?s4$42&!s ! len#t& o ;46$!nd ! %idt& o 645>$ %it& ! sp!cin# *et%een t&e

pl!tes o 6466>$4Also3esti$!te t&e pressuredrop o t&e &ot %!ter stre!$ !s it lo%s t&rou#&t&e e(c&!n#er4


35/51

DATA REBUIRED

T&e peror$!nce c&!r!cteristics or t&e c&e"ronconi#ur!tion selected or t&e pl!tes !re s&o%n 4

For Re ;663Nu !nd c!n *e represented *)t&e ollo%in# rel!tions&ips:

Nu 647 Re647Pr647

54J8Re164;8


36/51

A''UMPTION'

T&e pl!te &e!t e(c&!n#er oper!tes under ste!d)st!te conditions4 No p&!se c&!n#e occurs: *ot& luids !re sin#le

p&!se !nd !re un$i(ed4 He!t losses !re ne#li#i*le t&e e(c&!n#er s&ell

is !di!*!tic4 T&e te$per!ture in t&e luid stre!$s is unior$

o"er t&e lo% cross section4 T&ere is no t&er$!l ener#) source or sin. in t&e

&e!t e(c&!n#er4 T&e luids &!"e const!nt speciic &e!ts4 T&e oulin# resist!nce is ne#li#i*le4


37/51

Properties o e!c& luid !t t&e $e!n

te$per!ture in t&e e(c&!n#er !re

propert) Do%t&er$ !t 76KC 0!ter !t JJKC

He!t c!p!cit) CP ;455Q;69 ?.#42

74;8Q;69?.#42

T&er$!l conducti"it) . 64;98 ?4$42 648?s4$42

=iscosit) S 54J6Q;619P!4s 94J5Q;617P!4s

Densit) ;4677Q;65.#?$9 4J7Q;65.#?$9


38/51

'OLUTION

APPROACH TO THE PRO+LEM:

To !"oid !n iter!ti"e c!lcul!tion *ec!use o t&e

interdependenc) *et%een t&e &e!t tr!nser !re!!nd t&e tot!l lo% !re!3 use t&e NTU !ppro!c& todeter$ine t&e NTU$inreuired3 notin# t&!tNTU$inUA?,$Cp-$in4t&e !re! o t&e pl!te !nd

r!$e e(c&!n#er c!n *e c!lcul!ted once t&eo"er!ll &e!t tr!nser coeicient &!s *eene"!lu!ted4


39/51

CALCULATION OF HT AREA

For ! sin#le p!ss coni#ur!tion %it& Nppl!tes

!nd NP; lo% p!ss!#es3solution o t&e pro*le$

c!n *e si$pliied $!t&e$!tic!ll) *) !ssu$in# n

lo% p!ss!#es !nd n1; pl!tes 3since lo%"elocities in"ol"e lo% p!ss!#es !nd not pl!tes4

%it& t&is $odiic!tion3 t&e &e!t tr!nser sur!ce

!re! o t&e e(c&!n#er in ter$s o n is

A,n1;-L0,n1;-,;-,645>-645>,n1;-$5


40/51

CALCULATION OF FLOW AREA

The flow area for each stream with n/2flow

passages is given by:

'n?5,0-,*- n?5,645>-,6466>- ,6.25*10-!n.


41/51

CALCULATION OF HEAT DUT?,4J7Q;65-,45>Q;617-n ,749>?n-$?s


42/51

EQUIVALENT DIAMETER:

De5*

646;$


43/51

CALCULATION OF HOT 'IDE

HT COEFFICIENT

REYNOLD NUMBER:

Re&De=&&?S& 646;,749>?n-,4J7Q;65-?,94J5Q;617- 1.1"$*105/n

T&is indic!tes t&!t Re)nold nu$*er is #re!ter t&!n ;66 !nd correl!tion

or Nu c!n *e used4

Pr NUMBER:

Pr& CpS?. ,74;8Q;69-,94J5Q;617-?648 2."

&& ,647-,.&?De-Re647Pr647 648?646;;4;9Q;6>?n647,5497-647

6.6'*10/n0.6%/m2.&


44/51

CALCULATION OF COLD 'IDE HT

COEFFICIENT

T&e s!$e c!lcul!tions !re repe!ted or cold stre!$4

=$c?c ' 746?,;4677Q;69-,45>Q;617-n 6.1"/n

ReDe=cc?Sc 646;,4;9?n-,;4677Q;69-?,54J6Q;619- 2."'*10/n

Prc,;455Q;69-,54J6Q;619-?,64;98- "1.'"

T&is !lso indic!tes t&!t Re;66

&c ,647-,.c?De-Re647Pr647 ,647-,64;98?646;-,59JQ;67?n-647,9;4J9-647

1."##*10/n0.6 %/m2.&


45/51

CALCULATION OF O=ERALL

HT COEFFICIENT

T&e o"er!ll &e!t tr!nser coeicient c!n no% *e

deter$ined in ter$s o n4 'ince t&e sur!ce

!re!s on eit&er side o t&e pl!te !re t&e s!$e3

no correction or !re! is reuired4 Assu$e ! t&ic.ness o t&e pl!te (%o 646695$

;?U;?&&(%?.%;?&c

n64D7

?,47JQ;67

-,646695-?,7>-n64D7

?,;4988Q;67

- #.'51*10-5n0.6'('.11*10-5m. )/%


46/51

U'ING THE NTU METHOD

A NTU$inor cold stre!$ %it& ! $ini$u$ $cpis deined

NTU$inUA?,Mcp-$in Tc3out/Tc3in? VTK3lo# $e!n

LOG MEAN TEMPERATURE DIFF: T,log !"#

,T&3in1Tc3out-1,T&3out/Tc3in-?ln,T&3in1Tc3out-?T&3out1Tc3in-

,>1J6-1,61;6-?ln,>1J6-?,61;6-

946J 24

For ! sin#le p!ss counter lo% pl!te !nd r!$e &e!te(c&!n#er 3F;4


47/51

NTU J61;6?946J ;47

To s!tis) t&e ot&er NTU deinition o

UA?,Mc- in ter$s o results in t&e rel!tion

;

84J>;Q;6>n647J4;;Q;61>;47 , -,

645>,n1;-

746,;455Q;69--


48/51

ITERATI=E METHOD

T&is eu!tion c!n *e sol"ed %it& itrer!tion

to indic!te t&!t n>;4T&us >6 pl!tes !re

reuired to $eet to t&e &e!t tr!nser

needs to pre&e!t 7.#?s o do%t&er$ ro$;6 to J6KC4


49/51

H?>;6468>9$?s

Re&;4;9Q;6>

?>;5599 'ince Re;66

54J8Re164;8

54J8,5599-164;8

647


50/51

CONTD44

Ne#lectin# riction due to entr!nce !nd e(it

losses !s %ell !s te$per!ture eects on t&e

"iscosit) *et%een t&e %!ll !nd t&e *ul. luids4

'o pressure drop is c!lcul!ted ro$ t&e ollo%in#eu!tion:

VP7,L?De-&=&5?5

7,647-,;?646;- ,4J7Q;6

5

-,6468>9-5

?5 87N?$5

87P!


51/51

CONCLU'ION

'ince t&e entr!nce !nd e(it losses %ill *e

s$!ll3 t&e pressure drop per pl!te

is s$!ll3 !nd ! ne% coni#ur!tion %it&

$odiied di$ensions s&ould *e

considered4

plate and frame heat exchanger_ss

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