Isomer is at Ion of Light Naphtha.final

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Transcript of Isomer is at Ion of Light Naphtha.final

ISOMERIZTION

Compounds having same molecular formula but different arrangement of atoms are called isomer & phenomena is called ISOMERIZATION

TYPES OF ISOMERIZATIONISOMERIZATION

Chain Isomerization Functional isomerization

Position Isomerization Metamerism

BACKGROUND OBJECT:

Petroleum industry looking for Economical solutions to produce environmentally clean fuels. GLOBAL AIM:

Reduction of Benzene concentration in gasoline pool due to worldwide legislation.

WHY ISOMERIZATION? Iso-paraffin demand increases. Ability to reduce the benzene concentration in the

gasoline pool. Maintaining or increasing the gasoline pool octane.

INTRODUCTION The ISOMERISATION unit produces high-octane

light-naphtha isomerate. Isomerate is an excellent blending component. Isomerate has reduced benzene, aromatics and

olefins.

INTRODUCTION Converts n-paraffins into Iso-paraffins. Iso-paraffins contains higher RON than n-paraffins.

INTRODUCTIONISOM UNIT PENEX

MOLEX

Penex unit (n-paraffins

iso paraffins).

Molex unit separation between n-paraffin and iso-

paraffins.

SECTIONS OF ISOM UNIT

FEED PREPARATION PENEX PROCESS MOLEX PROCESS

FEED PREPARATION

FEED PREPARATIONC5 47.4% C6 45.1% Cyclics 7.2% MCP CH BENZENE H2O 0.3% Water n-C5 i-C5 2,2-DMB 2,3-DMB MP n-C6

FEED PREPARATION Preparation of feed and hydrogen to remove

contaminants for catalyst protection. Filter removes particulates Coalescer removes free water. Feed passes through Feed-Effluent exchangers and steam heater, Feed temperature rises to 220F.

FEED PREPARATION Sulfur guard bed (Nickel based adsorbent)

removes sulfur. Temperature decreased to 100F by passing

through air cooler. Feed is send to the liquid feed dryers, which

decreases dissolved water upto 0.1 ppm.

LIQUID FEED PREPRATION

FEED PREPARATIONfor saturation of benzeneHydrogen To suppress the Cracking Moleculer sieve dryers removes moisture from

hydrogen to < 0.1 ppm

MAKE-UP GAS FEED PREPRATION

PROCESS CONTAMINANTSy Sulphur y Water & other oxygenated compounds. y Nitrogen y Flouride y Heavy ends

UNDESIREABLE COMPOUNDy Olefins

y Cyclic compounds

y C7 hydrocarbon

LIMITS OF IMPURITIES FOR PENEX REACTOR CHARGEIMPURITIESSulphur Nitrogen Oxygenated compounds Water(H2O) Flouride

LIMITS0.1 ppm 0.1 ppm 0.1 ppm 0.05 ppm 0.5 ppm

PENEX

PENEX(Reactor)Feed + Make up hydrogen + Perchloroethylene

HEAT EXCHANGERS

PENEX (Reactors)300 *F 290*F

REACTOR 1Liquid 60% Vapor 40% Benzene Saturation Reaction (Exothermic)

COOLING

REACTOR 2Liquid 80% Vapor 20 %

Isomerization Reaction (Exothermic)

IMPORTANT REACTIONSy Benzene Saturation y Naphthene Ring Opening y Paraffin Isomerization y Hydrocracking

PENEX (STABILIZER) Remove lighter ends and HCl from the reactor

effluent. Bottom becomes Molex Feed.Diameter 5 -6 7 -6 9 -0 Height No. of Trays

77

30

PENEX (Stabilizer)164*F Lighter Ends

264*F

Molex Feed 312*F

PENEX (NET GAS SCRUBBER) Feed from stabilizer overhead. NaOH solution is used to scrub HCl from gas

stream. Scrubbed gas goes to gas plant for recovery of propane.Dia 3 8 Height 59 Packing Ring Packing

PENEX (Net Gas Scruber)99*F Gas Plant

Fresh Caustic Stabilizer O.H 100*F 100 *F Caustic to Kero Wash

PENEX PFD

PROCESS CHEMISTRYy Reaction mechanism:y Carbonium Ion Formationy

R- CH= CH2+ HAlCl4

R+- CH- CH3+ ALCl4+

y STEPSCH3- CH- CH2- CH2- CH3 CH3- C+(CH3)+CH2- CH3 y R+-CHCH3 +CH3-CH2-CH2-CH2-CH3 R-CH2-CH3+CH3-+CH-CH2-CH2-CH3y

y Skeletal rearrangement,y

CH3-+CH-CH2-CH2-CH3

CH3-C+(CH3)-CH2-CH3

y Iso-pentane is then formed and the chain propagated by the generation of new ncarbonium ion.y

CH3-C+(CH3)-CH2-CH3 + CH3-CH2-CH2-CH2-CH3 CH3-CH-CH2-CH3 + CH3-C+ (CH3)CH-CH2-CH2-CH3

MOLEX

MOLEXChlorine Guard Bed

Molex Main Stages

Adstorbent Chamber

Rotary Valve

Rafinate Column

Extract Column

MOLEX Stabilizer s bottom feed to Molex unit. Separation of normal and iso-paraffins. n-paraffins recycles to penex feed dryers. iso-paraffins refer ed as isomerate and runs down to

the storage tank.

MOLEX ADVANTAGESy Simple flow scheme. y Smooth operation. y Very little maintenance. y Rotary valve replaces need of great many switching

valves. y Molex required smaller adsorbent inventory. y No high temperature metallurgies required. y Heat requirement can be met with LP steam.

MOLEX (Chloride Guard Bed) Feed comes from bottom of stabilizer. Hot Stabilizer Bottom

312*F

Cooling Via H.E and Trim coolers

200*F

Chloride guard bed

Chloride guard bed removes remaining traces of HCl

from Molex charge. Zeolite molecular sieve beds are used.

MOLEX (Rotary Valve) Flow directing device and alternative of multiple

Control valves, Rotary valve is hydraulic driven.

Basic functional parts of RV

Stationary Bottom Head

Rotating Rotor plate

Top Dome

MOLEX (Rotary Valve) Bottom head is stationary and the process streams enter and exit through this plate. 16 bed line ports are machined in to the bottom head . Rotor plate aligns inlet and outlet streams with correct bed line and rests on the top of the bottom head . Teflon sealing sheet prevents leakage between the various fluids.

MOLEX (Rotary Valve) A seating pressure is applied to a rotor plate to hold it

against stationary bottom plate. Seating pressure provides by stream of desorbent

flowing through DOME. Allowed maximum product quality and lower

maintenance cost.

MOLEX (Adsorbent Chamber) Containing eight beds of molecular sieve

material(crystalline zeollite).

Although it is stationary bed but by using rotary valve

we are able to get same result as fluidized bed operation.

Two streams are entering and two are leaving at a same

time, to and from chamber.

MOLEX (Adsorbent Chamber) Normal parafins are adsorb in selective pore of

molecular sieves. Iso-parafins are flush out from non selective void of molecular sieves.Streams In Let Out Let

Feed

Desorbent

Raffinate

Extract

MOLEX (Adsorption Column)y Feed : Product of Penex. y Desorbent contain n-butane and iso-butane with

ratio of 85:15. y Raffinate contains iso-butane and iso-parafins . y Extract contain n-butane and n-parafins.Dia 9 Height 45 No of Beds 8

MOLEXAdsorbent Chamber Zone

Adsorption Zone

Purification Zone

Desorption Zone

Buffer Zone

MOLEX (Adsorbent Chamber) Adsorption Zone:

Between Feed & Raffinate Bed line. Purification Zone:

Between Feed and Extract Bed line. Desorption Zone:

Between Desorbent and Extract Bed line. Buffer Zone:

Between Desorbent and Raffinate Bed line.

ROTARY VALVE & ADSORPBTION CHAMBER

MOLEX(Rafinate Column)117 *FiC4 to Surge drum

Rafinate from Adsorption Chamber, 177 *F

214 *F i-Paraffins to storage

MOLEX (Raffinate Column)214 0F i-Paraffin Heat Exchanger 90 0F Storage

Diameter

Height

No. of Plates

09

137

60

MOLEX (Extract Column)y

122 0Fn-C4 to Surge drum

Extract from Adsorption Chamber, 171 0F

2350F

n-Paraffins Re-cycle to Penex Feed dryer

MOLEX (Extract Column)

Diameter

Height

No. of Plates

5 .6

119

50

DESIGNING

COLUMN EFFICIENCYTotal Average Viscosity(a ) = 0.1322 mNs/m2 m Average relative volatility of n-butane (Light key)( a)=1.95 aa = 0.2577 By using Eduljee Equation Expressing O Connell s Correlation Eo = 51-32.5 log ( aa) Eo = 51-32.5 log (0.2577) Eo = 71.13

DIAMETERFLV = L/V ( V/ L) (Csb 0.065) Vnf = Csb ( /20)0.2 ( V - L/ V)0.5 Assume 85% flooding. Vn = 0.85 * Vnf Column Area (An) =54m2 Cross Sectional Area (Ac)= An/0.85 D = (4Ac / )1/2 = 8.992ft (Approx 9 ft.)

MINIMUM NO. OF PLATES

Nm = (log[XLK/XHK]di[XHK/ XLK]bi)/ log[ Nm = 16.11

LK]

MINIMUM REFLUX RATIO

/ ( i- ) = 1 - q As feed is at B.P. q=0

n

i=1 -(

ixFi )

xid/( i- ) = Rm+1 Rm = 2.911i

TOTAL NUMBER OF PLATES(N-Nm) / (N+1)= 0.75 [ 1-(3.20-2.911) / (3.2+1) ] 0.566 N = 60.17

LOCATION OF THE FEED PLATELog ND/NB = 0.206 log [ B/D (XHK / XLK) F { (XLK)B / (XHK)D }2 ]ND = 0.6998NB ND + NB = 60.17 ND = 24.76 NB = 35.39 Feed will enter in the column above bottom stage at plate no. 36

COLUMN HEIGHTNumber of Plate Taking plate spacing = 60.11 = 2 ft.

We should take some free space at the top and the bottom i-e, about 5. The curve on top and bottom side of column is to ensure that vapor and liquid go along the shape without change in velocity = (60.11*2) + 5 + 5 = 130.22 ft