Isomer is at Ion of Light Naphtha.final
-
Upload
sohaib-ahmed-khan -
Category
Documents
-
view
136 -
download
5
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