perancangan tangki penyimpan dan menara distilasi

7/23/2019 Perancangan Tangki Penyimpan dan Menara Distilasi

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Process Equipment Design: 3 CR

Codes such as: ASTM=American Society of Mechanical Engineers; API=American

Petroleum Institute

Brownell, L.E., and Young, E. H., 1959, Process Equipment

Design: Vessel Design, Wiley Eastern Limited, New Delhi1. Vessel/Shell

Factors influencing the design of vessels

a. Selection of the type of Vessel

Type of vessel that is suited for particular service

b. The most common types of vessels based on their geometry

are:

i. Open tanksii. Flat bottomed, vertical cylinder tanks

iii. Vertical cylindrical and horizontal vessels with formed

heads

iv. Spherical or modified spherical vessels

Vessels in each these classifications are widely used as

storage vessels and as processing vessels for fluids

c. Primary factors that must be considered as follows

i. Function and location of vessel

ii. The nature of the fluidiii. Operating pressure and temperature

iv. Volume of storage or capacity for processing

Coulson, J.M., and Richardson, J.F., 1983, Chemical Engineering

Volume 6 (SI Units) Design, Pergamon Press, Oxford

p. 622, Chapter 13; Mechanical Design of Process Equipment

The basic data needed by the specialist designer will be:

a. Vessel functionb. Process materials and services

c. Operating and design temperature and pressure

d. Materials of construction

e. Vessel dimensions and orientationf. Type of vessel heads to be usedg. Openings and connections required


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h. Specification of heating and cooling jackets or coils

i. Type of agitatorj. Specification of internal fittings

Classification ofpressure vessels are divided into two classes: thin walled vessels with a

thickness ratio of less than 1:10; and thick walled above this ratio

General design considerations: pressure vesselsa. Design pressure

Pdesign = (1.5-1.1) Poperating ;

If hydrostatic pressure in the base of the column should be

added to the operating pressure, if significant

b. Design temperature

The strength of metals decreases with increasing temperature,

so the maximum allowable design will depend on the material

temperature

c. MaterialsCarbon and alloy steels for pressure vessel construction are

covered by the following British Standards: BS 1501, plate etc.

d. Design stress (nominal design strength)

For design purposes it is necessary to decide a value of the

maximum allowable stress that can be accepted in the

material construction. For materials not subject to high

temperature the design stress is based on the yield stress or

the tensile strength of the material at design temperature

e. Welded joint efficiency, and construction categories

The strength of a welded joint will depend on the type of

joints and the quality of the welding. The soundness of welds

is checked by visual inspection and non-destructive testing

(radiography)

f. Corrosion allowance

Most design codes and standards specify a minimum

allowance of 1.0 mm. For carbon and low-alloy where severe

corrosion is not expected, a minimum allowance of 2.0 mm

should be used; where more severe conditions are anticipated

this should be increased to 4.0 mm.

g. Design loads

A structure must be designed to resist gross plasticdeformation and collapse under all conditions of loading.

Major loads

1. Design pressure including any significant static

head of liquid;

2. Maximum weight of the vessel and contents, under

operating conditions;


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3. Maximum weight of the vessel and contents under

hydraulic test conditions

4. Wind loads

5. Earthquake loads

6. Load supported by, or reacting on, the vessel

Subsidiary loads1. Local stresses caused by supports, internal

structures and connecting pipes;

2. Shock loads caused by water hammer, or by

surging of the vessel contents;

3. Bending moments caused by eccentricity of centre

of the working pressure relative to the neutral axis

of the vessel;

4. Stresses due to temperature differences and

differences in the coefficient expansion of

materials;

5. Loads caused by fluctuations in temperature and

pressure

h. Minimum practical wall thickness

(Including the corrosion allowance, 2 mm)

Vessel diameter (m) Minimum thickness (mm)

1 5

1 to 2 7

2 to 2.5 9

2.5 to 3.0 10

3.0 to 3.5 12

The design of thin-walled vessels under internal

pressurea. Cylinder Shells

( ); BS 5500

2

i i

i

P Dt

Jf P=

, , dani if P J Ddengan are design

stress, internal pressure, joint factor and internal diameter,respectively.

b. Spherical shells

( ); BS 5500

4 1.2

i i

i

P Dt

Jf P=

c. Heads and closures

i. Flat plates and formed heads


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ii. Hemispherical heads

iii. Ellipsoidal headsiv. Torispherical heads

d. Typical shell shapes

Hemispherical

Cylinder

Cylinder

Cone

Ellipse

Typical vessel shapes


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Stresses in Thin Shells Based on Membrane Theory


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Rase and Barrow


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5656

RaseRase and Barrow_3and Barrow_3PadaPada leeward side vessel,leeward side vessel, bebanbeban anginangin dan dead weightdan dead weight

mengakibatkanmengakibatkan terjadinyaterjadinya compression internal pressure (longitudinalcompression internal pressure (longitudinal

stress)stress) mengakibatkanmengakibatkan terjadinyaterjadinya tension,tension, sehinggasehingga berlawananberlawanan

dengandengan compressioncompression

(R_14)(R_14)

0w pS S S S= +

Allowable stress untuk buckling sama dengan stress

karena beban angin dan dead weight

0B wS S S= + (R_16)

5757

RaseRase and Barrow_4and Barrow_4

Donell memberikan persamaan empiris sebagai berikut:

70 , 6 1 0

1 0 , 0 0 4

B

y

t R

R tS E

E

S

= +

(R_17)


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5858


Jorgensen,Jorgensen, menyerderhanakanmenyerderhanakan rumusrumus (R_4)(R_4)

untukuntuk bajabaja karbonkarbon (usual carbon steel)(usual carbon steel)

(R_18)(R_18)62 1 0B

tS x

D

=

5959


CircumferentialCircumferential

stressstress

API_ASME CODE:API_ASME CODE:

ASME CODEASME CODE

Buckling stressBuckling stress

Leeward allowableLeeward allowable

stressstress

WindwardWindward

allowable stressallowable stress

22

' 4

w m

m

P h PDWt

D S D S S = +

22

' 4

w m

m

P h PDWt

D S D S S = +

22

'

w

B m B

P h Wt

D S D S = +

1

2

PDt c

SE P= +

1

2 0, 6

P Dt c

S E P= +


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Brownell, L.E., and Young, E. H., 1959, Process Equipment

Design: Vessel Design, Wiley Eastern Limited, New Delhi

Flat Bottomed Cylindrical Vessels


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Optimum tank proportions

2/21/20132/21/2013 8383

Vessel (Vessel (bejanabejana))

PerbandinganPerbandingandiameter (Ddiameter (Dterhadapterhadaptinggitinggi(H)(H)

terletakterletakdiantaradiantaraduaduanilainilai::

BatasBatasbawahbawahuntukuntuk: (D/H) optimum: (D/H) optimum

HalHaliniiniterjaditerjadibilabilatangkitangkivolumnyavolumnyakecilkecil,, hanyahanyaelasticelasticstability dan corrosion allowance yangstability dan corrosion allowance yangmengendalikanmengendalikan

tebaltebalshellshell

( )cos , , ( , )t of shell bottom roofs per unit area f D H

2/21/20132/21/2013 8484


BatasBatasatasatasuntuk:(Duntuk:(D/H) optimum/H) optimum

BilaBilatebaltebalshellshellsebagaisebagaifungsifungsid, H ( ),d, H ( ),

dan unit area costs of the bottom dan roofsdan unit area costs of the bottom dan roofstidaktidak

tergantungtergantungpadapadaD dan HD dan H

( ),t f D H =


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2/21/20132/21/2013 8585


MisalkanMisalkan::

D diameterD diameterdalamdalamtangkitangki, ft, ft

HHtinggitinggitangkitangkidalamdalam, ft, ft

VVvolumvolumtangkitangkidalamdalam, ft, ft33

VolumVolumtangkitangki tertentutertentu,, sehinggasehinggaHHmerupakanmerupakanfungsifungsiDD

atauatau2

4

D H

V

=

2

4V

H D =

2/21/20132/21/2013 8686


BilaBila::

AA11==luasluasshell, ftshell, ft22, A, A22==luasluasbottom (projected area), ft2, Cbottom (projected area), ft2, C11==

annual cost of fabricated shell, $/ftannual cost of fabricated shell, $/ft22

CC22= annual cost of fabricated bottom, $/ft= annual cost of fabricated bottom, $/ft22

CC33= annual cost of fabricated roof, $/ft= annual cost of fabricated roof, $/ft22

CC44= annual cost of installed foundation under the vessel,= annual cost of installed foundation under the vessel,

$/ft$/ft22bottombottom

CC55= annual cost of land in the tank area chargeable to the tank= annual cost of land in the tank area chargeable to the tank

area, $/ftarea, $/ft22bottombottom

C= total annual cost of the vessel, $/yearC= total annual cost of the vessel, $/year


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2/21/20132/21/2013 8787


JikaJikatebaltebaltangkitangki

( )2

1

2 3 4 5

4

4

VC DC C C C C

D

= + + + +

( , )t f D H

( )1 2 3 4 524

20

VCC DC C C C

D

d

dD

= + + + + =

2/21/20132/21/2013 8888


TebalTebaltidaktidakmerupakanmerupakanfungsifungsiDDdandanHHKasusKasuskhususkhusus

TangkiTangkikecilkecil(small tank)(small tank)terbukaterbuka,, hargahargatanahtanahdandanfondasifondasi diabaikandiabaikan..

BiasanyaBiasanyatebaltebalshellshellsamasamadengandengantebaltebalbottom.bottom. JikaJika

dandan,, didapatdidapat

TangkiTangkikecilkecil(small tank)(small tank)tertutuptertutup hargahargatanahtanahdandanfondasifondasidiabaikandiabaikan,, berartiberarti

nilainilai dandan,, didapatdidapat

( )2 3 4 5

12 , persamaan untuk ( , )HC C C C

CD t f D H=

+ + +

3 4 50C C C= = =

1 2C C=

2HD =

4 50C C= = 1 2 3C C C= =

HD =

( ),Ht f D


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2/21/20132/21/2013 8989


JikaJikatebaltebaltangkitangki ( , )t f D H =

( )1 6 1C C H D=

( )( )

2

2 3 4 5

64

4

1V DC C C C C

D

C H D = + + + +

HHdigantidigantidengandengan2

4VH

D =

2/21/20132/21/2013 9090


( )2

2 3 4 56 624

44 4

DC C C C C

VVC VC

D

= + + + +

( )2 3 4 52

6

2

32 2

40 0

C DC C C C

C Vd

dD D

= + + + +

=

( )2 3 4 5

14HC C C C

CD =

+ + +

Didapat, hubungan diameter dengan tinggi tangki sebagai berikut


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2/21/20132/21/2013 9191


TangkiTangkibesarbesartertutuptertutup,, atapatapdan shelldan shellharganyaharganyaduadua

kalikalihargahargabottom,bottom, dandan didapatdidapat

( )2 3

242 0 0

2 8

3H

C C

CD H=

+ + +=

1 2 32C C C= = 4 5 0C C= =

2/21/20132/21/2013 9292


Shell design of small and medium sizedShell design of small and medium sizedvessels (production tanks) pp.43 B&Y.vessels (production tanks) pp.43 B&Y.

Vertical flatVertical flatbottomsbottomsdisebutdisebutproduction tanks.production tanks.TebalTebalsamasama(single thickness).(single thickness).

UkuranUkuranoptimum:doptimum:d(diameter=(diameter=H(tinggiH(tinggi))

LihatLihatfig:3.7 danfig:3.7 dantabeltabel3.3 (B&Y, pp.433.3 (B&Y, pp.43--44)44)

Tebal:3/16 or ,Tebal:3/16 or , lebarlebarflatflat6060


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2/21/20132/21/2013 9393


Shell design of large storage tanks (pp.34Shell design of large storage tanks (pp.34B&Y).B&Y).

TanksTanksbentukbentuksilindersilinder, great structure strength, great structure strengthdandanmudahmudahdibuatdibuat

Several types of stresses yangSeveral types of stresses yangmungkinmungkinterjaditerjadi

padapadatangkitangkibentukbentuksilindersilinder::

LongitudinalLongitudinalstressstressinternalinternalpressurepressure

CircumferentialCircumferentialstressstressinternalinternalpressurepressure

Residual weldResidual weldstressesstresseslocalizedlocalizedheatingheating

2/21/20132/21/2013 9494


StressesStressessuperimposedsuperimposedloadsloadssepertiseperti::

wind, snow, and ice, auxiliarywind, snow, and ice, auxiliary

equipment, and impact loadsequipment, and impact loads

StressesStresseskarenakarenathermal differencesthermal differences OthersOthersdijumpaidijumpaididalamdidalamparaktekparaktek


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Proportioning and head selection for cylindrical vessels with

formed heads

Chapter 5, p 76-

With ellipsoidal head with dimension diameter of 2:1.

bH

a

a=2b

2/21/20132/21/2013 136136


DimensiDimensi VesselVessel

8822sampaisampaidengandengan 66

663/163/16sampaisampai22

L/DL/DTebalTebal, inches, inches

xy

y

D


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Coulson, J.M., and Richardson, J.F., 1983, Chemical Engineering

Volume 6 (SI Units) Design, Pergamon Press, Oxford

p. 622, Chapter 13; Mechanical Design of Process Equipment

2. Separation Process/Separation ColumnsDistillation process

Absorption

Scrubber

It will be emphasized on distillation processes due to basic features and

many of the design methods also apply to other multistage processes such as

stripping, absorption and extraction

The choice between packed and plate columns

Liquid-vapor transfer operation dapat dilakukan pada :Packed or plate columns

o Packed column: continuous contact

o Plate column: stage wise contact

Both system works in different modes

Pemilihan menara didasarkan pada empat(4) faktor (Barker &Hakkers):

1. Factors that depend on the system, i.e. the component,

2. Factors that depend on the fluid flow movement,3. Factors that depend upon the physical characteristics of the column and its

internals,

4. Factors that depend upon the of operation

I. SYSTEM FACTORS1. Scale: Diameter


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6. Pressure drop. Lebih rendah pada packed column dibandingkan dengan

plate column.

7. Liquid hold-up. Lebih kecil pada packed column dibanding-kan dengan

plate column. Pada plate colum selalu ada cairan sedangkan pada packed

column ada lapisan tipis cairan pada permukaan packing.

II. PHYSICAL CONSIDEARTIONS1. Maintenance. Manholes pada plate tower mudah dilengkapi, sedangkan

pad packed tower harus mengeluarkan packing.

2. Berat. Penggunaan keramik atau metal pada menara menyebabkan

menara menjadi lebih berat dibandingkan jika dipakai plate tower,

sehingga perlu memperhatikan fondasi dan penyangga packing. Hal ini

dapat diatasi dengan penggunaan packing dari plastik, karena lebih

ringan.

3. Side streams. Pengambilan side streams dan pemasukan side streams

lebih mudah pada plate tower, meskipun tray spacing pada tempat

tersebut harus dimodifikasi. Pada packed tower hal ini tidak mungkin,

karena akan mengganggu proses pemisahan.

4. Size and cost. Jika diameter lebih rendah dari 1 m, packed tower yang

dipilih, karena pembuatan plate lebih mahal untuk tujuan yang sama.

Diatas diameter 1 meter, tidak dapat dilakukan generalisasi. Terhadap

tinggi, packed column biasanya lebih lebih pendek dibandingkan dengan

plate colum untuk tujuan yang sama, meskipun plate column dapat

memberikan diameter yang lebih kecil untuk kecepatan gas yang sama.

III. MODE OF OPERATION

1. Batch distillation. Liquid recovery sangat tinggi untuk komponen yanglebih ringan (dua komponen)

2. Intermittent distillation. Plate tower, karena memberikan positive seal for

liquid.

3. Continous distillation. Tidak ada salah satu faktor yang dominan, semua

faktor harus dipertimbangkan.

4. Turndown. Perbandingan antara loading maksimum dengan loading

minimum pada kondisi flooding dan the lowest efficiency can be

accepted. Untuk umpan dengan turndown ration > 2,5:1, dipilih a plate

column

5. Semua faktor tersebut diatas harus dipertimbangkan dan untukpemilihan akhir harus ada kompromi diantaranya.

.

IV. TIPE, UKURAN PACKING, DIAMETER MENARA DAN LIQUID DISTRIBUTOR

1. RASCHIG RINGS: ukuran packing


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2. BERL OR INTALOX SADDLES:ukuran packing


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Lewis-Sorel method (equimolar overflow)

Rectifying


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Stripping

URUT - URUTAN PERANCANGAN KOLOM DISTILASI PENEKANAN PADA PROSES DISTILASI

PROSES LAINNYA SEPERTI:STRIPPING, ABSORPTION DAN EXTRACTION MEMPUNYAI

DESIGN METHOD DAN BASIC CONSTRUCTION FEATURES YANG SERUPA /MIRIP

DISTILASI MERUPAKAN POROSES PEMISAHAN YANG BANYAK DIPAKAI

PENGETAHUAN TENTANG KESETIMBANGAN SANGAT DIPERLUKAN UNTUKMERANCANG KOLUM DISTILASI ATAU PROSES - PROSES KESETIMBANGAN LAIN


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PERANCGAN KOLOM DISTLASI, ABSORPSI, STRIPPING TERUTAMA TERDIRI DARI TIGA

LANGKAH (PROCESS PLANT DESIGN OLEH J.R. BACKHURST DAN J.H. HARKER, 1983 ):

1. PEMILIHAN INTERNAL DEVICE : PLATE ATAU PACKING

2. JUMLAH TRAYS ATAU TINGGI PACKING

3. KALKULASI DIAMETER KOLUM

CEHCK LIST OF DESIGN ITEMS FOR BUBBLE-CAP, PERPORATED, AND VALVE TRAY

(DISTILLATION OLEH MATTHEW VAN WINKLE, 1967)

COLUMN

01. OPERATING TEMPERATURE AND PRESSURE

02. REFLUX RATIO

03. NUMBER OF TRAYS

04. FEED AND DRAW OFF TRAYS AND LOCATION

05. COLUMN DIAMETER

06. TRAY SPACING

TRAY

07. LIQUID-FLOW ARRANGEMENT OR TRAY TYPE

08. ACTIVE AREA

09. DWONCOMER TYPE, AREA, AND CLEARANCE

10. TRAY OUTLET WEIR TYPE, HEIGHT AND LENGTH

11. TRAY INLET WEIR TYPE, HEIGHT AND LENGTH (IF ANY)

12. TRAY OUTLET SPLASH BAFFLE, ANTI JUMP BAFFLES

13. TRAY AND WEIR LEVEL TOLERANCES

14. MATERIAL OF CONSTRUCTION

BUBBLE CAP

15. BUBBLE-CAP DIAMETER, NUMBER

16. CAP LAYOUT, PITCH, AND SPACING

17. SKIRT SEAL

18. STATIC SEAL

19. RISER DIMENSIONS

20. TRAY BAFFFLES

21. TRAY DRAIN HOLES

22. LEAKAGE

PERFORATED

15. FREE HOLE AREA

16. HOLE SIZE, PITCH PATTERN

17. TRAY THICKNESS

18. HOLE BLANKING


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VALVE

15. SIZE HOLES AND VALVE TYPE

16. NUMBER OF VALVES AND SPACING

17. TRAY THICKNESS

URUT - URUTAN PERANCANGAN KOLOM DISTILASI1. TENTUKAN SPESIFIKASI HASIL(KOM POSISI DISTILAT / BOTTOM)

2. PILIH KONDISI OPERASI ( BATCH & KONTINUE ), TEKANAN OPERASI

3. CONTACTING DEVICES ( PLATE / PACKING

4. STAGE IDEAL& REFLUKS

5. UKURAN KOLOM ( DIAMETER & JUMLAH REAL STAGE DESIGN THE COLUMN

INTERNAL : PLATES, DISTRIBUTORS, PACKING SUPPORT

6. MECHANICAL DESIGN: VESSEL & INTERNAL FITTING

LANGKAH UTAMA:

1. PERHITUNGAN JUMLAH STAGE2. REFLUX YANG DIPERLUKAN

3. JIKA CAMPURAN BINER , RELATIF MUDAH4. JIKA MULTIKOMPONEN , KOMPLEKS & SULIT

TEKANAN (P) pada puncak kolum

PENDINGIN : AIR ( PEMILIHAN PERTAMA)

SUHU AIR : 30 -36 DEG.C

DELTA SUHU APPROACH :

UMUM 20 DEG.C; AIR = 3 - 7 DEG.C

SUHU DEW POINT SEKITAR 50-56 DEG.C

TRIAL P; JIKA P TERLALU TINGGI PIKIRKAN PEMAKAIAN REFRIGERATION.

BAHAN SENSITIF THD SUHU, P < 1 ATM

P SEPANJANG KOLOM DIANGGAP SAMA ( AWAL PERHITUNGAN ), LALU

DIKOREKSI SETELAH JUMLAH STAGE DIKETAHUI

OPERASI VACUUM PRESSURE DROP PENTING

MULTICOMPONENT SYSTEM

SHORT CUT .......PRELIMANARY DESIGN

SHORT CUT ...... DIBAGI DUA

-PENYEDERHANAAN PLATE TO PLATE CAL.

- MISALNYA : METODE HENGSTEBECK-METODE EMPIRIS

- MISALNYA : KORELASI GILLILAND DAN ERBAR-MADDOX

KEY COMPONENT

LIGHT DAN HEAVY KEY COMPONENTS

LIGHT KEY COMPONENT ( LK ) .....TOP

HEAVY KEY COMPONENT (HK ) .... BOTTOM


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SPESIFIKASI PRODUK

JUMLAH LK DAN HK MENUJU TOP ATAU BOTTOM DIBATASI OLEH

SPESIFIKASI PRODUK

ADJACENT KEY COMPONENT.....

BERURUTAN PADA LISTING BERDASARKAN ALPHASPLIT KEY COMPONENT....

JIKA ADA KOMPONENT LAIN DIANTARANYA

NON KEY COMPONENT YANG ADA PADA TOP DAN BOTTOM DISEBUT

DISTRIBUTED COMPONENT. JIKA TIDAK ADA PADA SALAH SATU PRODUK

DISEBUT NONDISTRIBUTED COMPONENT.

REFLUX

R OPTIMUM = ( 1,2-1,5 ) R MINIMUM ( COLUSON DAN RICHARDSON,

1983)

R OPTIMUM = ( 1,25-1,3) R MINIMUM( PERRY DAN CHILTON, 1973)

PENGARUH REFLUX TERHADAP N = JUMLAH STAGE DAPAT DICARI

DENGAN CARA SHORT CUT METHOD

3. HEAT EXCHANGER, DESIGN OF HEAT EXCHANGERShell and Tube Exchanger

Double pipe Exchanger

4. REACTORBatchFlow reactor

a. CSTR

b. PFR

c. FBR

d. Semi batch reactor

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