Safety Relief

7/25/2019 Safety Relief

1/38

RELIEF SYSTEMS IN PROCESS PLANTS

ARE THEY NEEDED?

RELIEF SYSTEM

SAFETY INTERLOCKSYSTEM

ALARM SYSTEM

BASIC PROCESSCONTROL SYSTEM

Could

these all

fail due

to a

o!!o"

fault?

Hi"t# Yes$$


2/38


RELIEF SYSTEM

SAFETY INTERLOCKSYSTEM

ALARM SYSTEM

BASIC PROCESSCONTROL SYSTEM

Loatio"

E%ui&!e"t seletio"

Dou!e"ti"' o"

d(a)i"'s

Ma*i!u! a&ait+

,hat-s i" thisto&i?


3/38


$ I"(ease i" &(essu(e a" lead to (u&tu(e of .essel o( &i&e

a"d (elease of to*i o( fla!!a/le !ate(ial

0 Also1 )e !ust &(otet a'ai"st u"e*&eted .auu!$

$Natu(all+1 /est to &(e.e"t the &(essu(e i"(ease

0 la('e distu(/a"es1 e%ui&!e"t failu(e1 hu!a" e((o(1

&o)e( failu(e1 222

$ Relief s+ste!s &(o.ide a" e*it &ath fo( fluid

$ Be"efits# safet+1 e".i(o"!e"tal &(otetio"1 e%ui&!e"t

&(otetio"1 (edued i"su(a"e1 o!&lia"e )ith

'o.e("!e"tal ode


4/38


5/38

STANDARD RELIEF METHODS

$ BASIC PRINCIPLE: No external power required -self atuati"' 0pressure of process proides needed force!

$ 7AL7ES- close w"en pressure returns to accepta#le alue

- Relief $ale - liquid s%ste&s

- Safet% $ale - 'as and apor s%ste&s includin' stea&

- Safet% Relief $ale - liquid and(or apor s%ste&s

$ Pressure of protected

s%ste& can exceedt"e set pressure)

Copyrights by CCPS/American Institute of Chemical Engineers and copied with the permission of AIChE


6/38

STANDARD RELIEF METHODS

$ BASIC PRINCIPLE: No external power required -self ati"'

$ R8PT8RE DISKS OR B8RST DIAPHRA9MS-&ust #e replaced after openin'

)

Copyrights by CCPS/American Institute of

Chemical Engineers and copied with the

permission of AIChE


7/38

SOME INFORMATION ON RELIEF 7AL7ES

$ T)o t+&es of desi'"s dete(!i"e i"flue"e of &(essu(e

i!!ediatel+ afte( the .al.e

0 Co".e"tio"al 7al.e0&(essu(e afte( the .al.e affets the

.al.e lift a"d o&e"i"'

0 Bala"ed 7al.e0 &(essu(e afte( the .al.e does "ot affet

the .al.e lift a"d o&e"i"'

Co".e"tio"al Bala"ed



8/38

SOME INFORMATION ON RELIEF 7AL7ES

$ AD7ANTA9ES

0 si!&le1 lo) ost a"d !a"+ o!!e(ial desi'"s a.aila/le

0 (e'ai" "o(!al &(oess o&e(atio" (a&idl+ /eause the

.al.e loses )he" &(essu(e de(eases /elo) set .alue

$ DISAD7ANTA9ES

0 a" lea6 afte( o"e /ei"' o&e" 3O0(i"' (edues4

0 "ot fo( .e(+ hi'h &(essu(es 3:;1;;; &si4

0 if o.e(si


9/38

SOME INFORMATION ON R8PT8RE DISKS>

B8RST DIAPHRA9MS

$ A )ide (a"'e of !ate(ials a"d

desi'"s a(e a.aila/le

$ AD7ANTA9ES

0 "o lea6a'e u"til the /u(st0 (a&id (elease of &ote"tiall+ la('e .olu!es

0 hi'h &(essu(e a&&liatio"s

0 o((osio" leads to failu(e1 )hih is safe

0 !ate(ials a" /e slu((ies1 .isous1 a"d sti6+

$ DISAD7ANTA9ES

0 !ust shutdo)" the &(oess to (e&lae

0 '(eate( loss of !ate(ial th(ou'h (elief

0 &oo(e( au(a+ of (elief &(essu(e the .al.e

Copyrights by CCPS/American

Institute of Chemical Engineers and

copied with the permission of AIChE


10/38

SHO,IN9 RELIEF SYSTEMS ON PROCESS

INSTR8MENTATION 3PI4 DRA,IN9S

S&(i"'0loaded safet+ (elief .al.e

Process

To efflue"t ha"dli"'

Ru&tu(e dis

Process To efflue"t ha"dli"'


11/38

ADD RELIEF SYSTEM TO THE FOLLO,IN9

PROCESS DRA,IN9

F@


12/38


PROCESS DRA,IN9

F@

The d(u! a" /e isolated

)ith the o"t(ol .al.es=

&(essu(e (elief is (e%ui(ed2

,e )ould li6e to (eo.e()ithout shutdo)"= )e

selet a (elief .al.e2


13/38


PROCESS DRA,IN9

Positi.edis&lae!e"t

&u!&


14/38


PROCESS DRA,IN9

Positi.edis&lae!e"t

&u!&

The &ositi.e dis&lae!e"t

&u!& )ill /e da!a'ed ifthe flo) is sto&&ed= )e

"eed to &(o.ide (elief2

,e )ould li6e to (eo.e(

)ithout shutdo)"= )e



15/38


PROCESS DRA,IN9

,h+ a(e all

those .al.es

i" the &(oess?


16/38


PROCESS DRA,IN9

The e*t(a ha"d.al.es

e"a/le us to isolate a"d

(e!o.e the heat e*ha"'e(

)ithout sto&&i"' the&(oess2

The shell side of the heat

e*ha"'e( a" /e isolated=

)e "eed to &(o.ide (elief2

,e )ould li6e to (eo.e(

)ithout shutdo)"= )e



17/38


IN SOME CASES1 RELIEF 7AL7E AND

DIAPHRA9M ARE 8SED IN SERIES 0 ,HY?

,h+ is the &(essu(ei"diato( &(o.ided?

Is it loal o( (e!otel+

dis&la+ed? ,h+?

,hat is the ad.a"ta'e

of t)o i" se(ies?

,h+ "ot ha.e t)o

(elief .al.es

3dia&h(a'!s4 i"

se(ies?


18/38


IN SOME CASES1 RELIEF 7AL7E AND

DIAPHRA9M ARE 8SED IN SERIES 0 ,HY?

,h+ is the &(essu(e

i"diato( &(o.ided?

If the &(essu(e i"(eases1

the dis6 has a lea6 a"d

should /e (e&laed2

Is it loal o( (e!otel+

dis&la+ed? ,h+?

The dis&la+ is loal to

(edue ost1 /eause )e

do "ot ha.e to (es&o"d

i!!ediatel+ to a failed

dis6 0 the situatio" is "ot

ha


19/38


*E S+,L. ALS, PR,/EC/ A0AINS/

E1CESSI$E $AC2

The follo)i"' e*a!&le uses /u6li"' &i"s

o.e(&(essu(e

u"de(&(essu(e


20/38

SOME 7APOR AND D8ST EPLOSIONS RE8IRE

7ENTS

$ Co"t(ol a"d di(et the e*&losio" affets

Structure ent closed

Structure

explosion


21/38

,E M8ST SAFELY PROCESS OR DISPLOSE

OF MATERIAL FROM RELIEF SYSTEM$

F(o!(elief

To e".i(o"!e"t 7e"t stea!1 ai(

Holdi"' fo( late( &(oessi"' ,aste )ate( t(eati"'

Re+le to &(oess Fuel 'as1 fuel oil1 sol.e"t

Reo.e( &a(t to &(oess

I!!ediate "eut(ali


22/38


,E M8ST SAFELY PROCESS OR DISPLOSE

OF MATERIAL FROM RELIEF SYSTEM$

A &(oess e*a!&le )ith se.e(al fo(!s of efflue"t ha"dli"'


23/38

SI5IN9 RELIEF SYSTEMS

$ DETERMINE THE RELIEF FLO, 3!a*i!u!

&ossi/le4

$ DETERMINE THE SET PRESS8RE

0 /ased o" &(oess "eeds a"d e%ui&!e"t !ate(ials a"do"st(utio"

$ SELECT THE RELIEF TYPE

0 /ased o" ad.a"ta'es>disad.a"ta'es of /oth

$ CALC8LATE THE NEEDED AREA FOR FLO,

$ SELECT THE COMMERCIAL DE7ICE FROM

7ENDOR=S SPECIFICATIONS


24/38

DETERMININ9 FLO,S FOR SIMPLE SIT8ATIONS

Fi" Fout ?

Fout ?

Tsou(e T

Relief Flo)Sou(e

Fout ?

Li%uid o( .a&o(filled s+ste!

T)o0&hases+ste! )ithheat i"&ut

Li%uid s+ste!)ith "o &haseha"'e a"d)ith heatt(a"sfe(


25/38

DETERMININ9 FLO,S FOR SIMPLE SIT8ATIONS

Fi" Fout ?

Fout ?

Tsou(e T

Relief Flo)Sou(e

Fout ?

Li%uid o( .a&o(filled s+ste!

T)o0&hases+ste! )ithheat i"&ut

Filled Li%uid s+ste!)ith "o &haseha"'e a"d)ith heatt(a"sfe(

Fi"

37'07l4>

H.a&

>

C&

,hat is the !eha"is! fo( heat t(a"sfe(? Radiatio" o(

o".etio"?


26/38

DETERMINE THE MAIM8M FLO, FOR THE

O7ERHEAD 7APOR

8"de( )hat

o"ditio"s is the

.a&o( at its

!a*i!u!?3

4

q

R

.

B

LC

LC

PC

A

1.

A1B

$

Relief


27/38


O7ERHEAD 7APOR

Relief

The !a*i!u! .a&o(

ou(s )he"

@2 Ma*i!u! feed .a&o(2

:2 Ma*i!u! (e/oile( dut+2

G2 Co!&lete loss of

o"de"satio" 3loss of

ooli"' )ate(42

3

4

q

R

.

B

LC

LC

PC

A

1.

A

1B

$


28/38


RELIEF SYSTEM


29/38


RELIEF SYSTEM

I" additio" to the

shell0side fluid1 )e

!ust o"side( the

&ossi/ilit+ of a lea6

f(o! the tu/e side2

This !i'ht /e a la('e

flo) o( (e%ui(e s&eial

&(oessi"' /eause of

ha


30/38

DETERMININ9 THE AREA FOR 7AL7ES IN LI8ID

SER7ICE

$ Basi e%uatio" fo( flo)

th(ou'h a" o(ifie

$ Rea((a"'e to sol.e fo(

a(ea a"d add o((etio"

fato(s

Ps set &(essu(e = P/ /a6 &(essu(e

K..isosit+ o((etio" 3 @2; as Re la('e1 G;1;;;4

K&o.e(&(essu(e o((etio"1 de&e"ds o" the o.e(&(essu(e f(o! (elief de.ie

3lo)e( o.e(&(essu(e 'i.es a s!alle( K& a"d la('e( a(ea4

K//a6 &(essu(e o((etio"1 @2; fo( /ala"ed .al.e

@2; fo( o".e"tio"al .al.e

Pg2AC=F

c

!P"P#g2

$$$C

F=A

bscbp%


31/38

DETERMININ9 THE AREA FOR DIAPHRA9MS IN

7APOR SER7ICE

$ Basi e%uatio" fo( flo) th(ou'h a" o(ifie .e"ti"' toat!os&he(e

$ Rea((a"'e to sol.e fo(

a(ea )ithout o((etio"

fato(s

,hat s&eial fato(

is i!&o(ta"t i" the

dia&h(a'! (elie.i"' to

a (eo.e(+ s+ste!?

Pg2AC=F

c

/o flare

Liquid

recoer%

5),)dru&

Burstdiap"ra'&


32/38

DETERMININ9 THE AREAS FOR 7AL7ES AND

DIAPHRA9MS IN 7APOR OR 9AS SER7ICE

$ Ofte"1 the flo) is so"i o( Aho6ed@0 i" this situatio"1the flo) de&e"ds o" the u&st(ea! &(essu(e /ut "ot the

do)"st(ea! &(essu(e2 This ou(s )he" Ps ;2P/= this is

(ou'h esti!ate1 see (efe(e"es2

$ The defi"i"' e%uatio" is

,ith KJ de&e"di"' o" T1 heat a&ait+ (atio1 !ol2 )ei'ht1 /a6

&(essu(e1 a"d o!&(essi/ilit+

uestio"# Ho) do )e 6"o) if the flo) is ho6ed?

Does this !ea" that a" i"(ease i" /a6 &(essu(e has "o effet o" flo)?

PA$=Fcho&edJ


33/38


DIAPHRA9MS

FOR EOTHERMIC REACTORS

CA8TION$

$ T)o0&hase .e"ti"' has &(o.ed diffiult to !odel (elia/l+

0 DIERS1 3Desi'" I"st2 fo( E!e('e"+ Relief S+ste!s4fo(!ed /+

o!&a"ies a"d AIChE0 'oals a(e to dete(!i"e si


34/38


DIAPHRA9MS

FOR EOTHERMIC REACTORS

CA8TION$

$ A sta"da(d e*&e(i!e"tal a&&a(atus is used to ollet adia/ati data o"

(u"a)a+ (eatio"s

0 s!all sale so little ha


35/38

SA3E/6 RELIE3 S6S/E2S7

*+A/ +A$E *E LEARNE.8

These a(e self0atuated1 "o e*te("al &o)e( is (e%ui(ed

T)o !ao( de.ies a(e (elief .al.e a"d (u&tu(e dis6

Relief is (e%ui(ed fo( all losed .olu!es

,e !ust di.e(t !ate(ial to a ade%uate ha"dli"'

s+ste!

,e a(e "o) (ead+ to 'ai" e*&e(ie"e i" desi'"i"' a"d

e.aluati"' safet+ (elief s+ste!s2


36/38

REFERENCES

Andrew7 *) and +) *illia&s7 Applied Instru&entation in t"e Process Industries7 $olu&e I: A Sure%7 0ulf

Pu#lis"in'7 +ouston7 9;

Andrew7 *) and +) *illia&s7 Applied Instru&entation in t"e Process Industries7 $olu&e II: Practical

0uidelines7 0ulf Pu#lis"in'7 +ouston7 9) Louar7 7 C"e&ical Process Safet%: 3unda&entals wit" Applications7 Prentice +all7

En'lewood Cliffs7 9=

.ris?ell7 L)7 Control $ale Selection and Si@in'7 Instru&ent Societ% of A&erica7 9) Leun'7 New Experi&ental /ec"nique for C"aracteri@in' Runawa% C"e&ical Reactions7

CEP7 p) -7 Au'ust 9enett7 E)7 .esi'n Considerations for Pressure-Reliein' S%ste&s7 C"e&) En'r)7 Part I7 p) 9D-9=7 >ul%

9F Part II7 p) 9D9-9D


37/38

RELIEF SYSTEM LEARNIN9 TASKS

@2 Re.ie) the CCPS ,,, !ate(ial

3o" ou(se site i" (est(ited a(ea4

Lesso" @2 Relief Re%ui(ed

Lesso" :2 Ru"a)a+ Reatio"s

Lesso" G2 Safe'ua(ds 3e*&losio"s4

:2 Re.ie) this lesso" a"d solutio"s2

G2 Read Pe((+-s Ha"d/oo61 se.e"th Editio"1

&2 :0: to :0G1 :0G to :0


38/38

RELIEF SYSTEM ,ORKSHOP

@2 Re.ie) the distillatio" &(oess o" the "e*t &a'e2

:2 Loate se.e(al (elief s+ste!s2

G2 E.aluate eah s+ste! fo( &(o&e( loatio" a"dhoie of (elief de.ie

2 Fi"d a loatio" that should ha.e a (elief s+ste! /ut

does "ot2

Re!e!/e(1 the fi'u(e ould ha.e e((o(s fo(

teahi"'>lea("i"' &u(&oses2

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