PRODUCTION OF PARAXYLENEFINAL YEAR PROJECT
CHEMICAL ENGINEERING
PROJECT ADVISORMR. RIZWAN AHMED QAMAR
WAHAB HUSSAIN KHAN CH-12014
MUHAMMAD FAIZAN CH-12023
MUHAMMAD ASAD ALI QAZI CH-12072
SAAD SAMI CH-12303
INTRODUCTION The production of large amounts of heavy
naphtha is inevitable in refineries across Pakistan, amongst other components which are also of immense importance p-xylene holds extraordinary importance for Pakistan in virtue of its value in both foreign and domestic markets.
P-xylene forms major raw material for the production of terephthalic acid (TPA) which further converts into polyethylene terephthalate (PET).
PRODUCTION OF PARA XYLENE Toluene Methylation Process PAREX Process Isomerization of meta-xylene
ISOMER-IZATION PROCESS
PARAX PROCESS
TOLUENE PROCESS
0
10
20
30
40
50
60
70
Initial Investment/ $ Million
Initial Investment/ $ Million
ISOMER-IZATION PROCESS
PARAX PROCESS
TOLUENE PROCESS
0%10%20%30%40%50%60%70%80%90%
Yield of Para-xylene
Yield of Para-xylene
PFD FOR ISOMERIZATION UNIT
MATERIAL BALANCE ON ISOMERIZATIONSTEAM ID 1 2 3 4 5 6 7 8A 8C 8D
H2 0 3318.4 3318.4 3301.1275 2.08 3298.8 0 2.079 0 0
ETHYLBENZENE 42.7 1.1 43.8 43.8 32.07 11.6 28.89 0.169 45 3
PARAXYLENE 84 2.3 86.3 142.587 139.9 2.61 132.6 0.3506 104.97 6.998
METAXYLENE 293 5 298 211 207.24 3.72 198.6 0.4945 149.35
5 9.957
ORTHOXYLENE 21.4 1.6 23 52.0717 51.32 0.745 50.44 0 12.769
5 0.8513
DESIGNING OF MAJOR EQUIPMENTS
FURNACEMaterial Carbon
steel
L:B:H Ratio 1:2:2
Height (H) 50 ft
Air pre heat (F) 400
Furnace length (ft) 25 ft
No. of tubes 32
Tubes skin temperature (F) 1000
Flux (Btu/hr.ft2) 11500
Furnace Duty (MMBtu/hr) 17.67
Stream tag 3Description Octafiner ChargeTemperatur
e 135 oF
Pressure 217 psig
REACTOR
M PM O2M TOL + TMB
ERGUN EQUATION:
CHEMICAL REACTION:
Meta Xylene Conversion = 29.19 %
Para Xylene Selectivity = 65%
Ortho Xylene Selectivity = 33.4%
% COKE = e-αt REACTION TIME = 5.513 sec
REACTORMaterial Carbon
steel
Type Of Column
Packed
Diameter Of Bed (ft)
7
Diameter Of Particle (in)
0.25
Porosity (φ) 0.45
Bulk Density Of Catalyst
(lb/ft3)
25.82
Designed Height Of
Packing (ft)
13.6
Catalyst Precoked ZSM-5
Stream tag 3 4
DescriptionReactor
feed from furnace
Reactor Effluent
Temperature 135 oF 952 oF
Pressure 217 psig 173 psig
Flow rate of meta-xylene
Pressure
Flow rate of para-xylene
Flow rate of ortho-xylene
FLASH DRUMMaterial Carbon
steelL/D 3.3
Length of Vessel (ft)
15.19
Diameter of Vessel (ft)
4.59
Volumetric Flow rate (ft3/s)
42.89
Terminal Velocity (ft/s)
2
Maximum Allowable
Velocity (ft/s)
2.58
Height of Liquid Holdup Section
(ft)
5
Retention Time (min)
2
Stream tag 4 5 6Description Reactor
EffluentLight
Aromatic column feed
Fuel gas
Temperature 95 oF 95 oF 95 oF
Pressure 160 psig
14 psig 140 psig
HEAT EXCHANGERHeat Duty
(MMBtu/hr)3.8
No. Of Tubes 408Length Of Tube(ft) 16
Outer Diameter of Tube (in)
0.75
Pitch (in) 1Tube Passes 8
Pressure Drop In Tubes (psi)
2.26
Heat Transfer Area(ft2)
1250
Internal Diameter of Shell (in)
27
Baffle Spacing (in) 5.4 Pressure Drop in
Shell (psi)
1.34
Stream tag 5 7Description Light
Aromatic column feed
Column Bottoms
Temperature 95 oF 322 oFPressure 14 psig 14 psig
PUMPMass Flow Rate
(lb/hr) 46895
Differential Pressure (psi) 280
Horsepower (KW) 13.116
Horsepower (HP) 17.65
Efficiency 54.8
Brake Horsepower
(HP)32.2
Stream tag 1Description Octafiner chargeTemperature oF 60
Pressure psig 0
HAZOP ANALYSIS
FLASH DRUMGuide Words Parameters Causes Consequence
s Actions
LessLess Flash drum pressure
- Lower feed temperature
Higher liquid level.
Install pressure and temperature controller prior to the drum.
- Leakage in the Flash drum
Vapor lost and not recovered at the top.
Install pressure indicator on the drum or replace vessel.
Less level of liquid in the flash drum
- Blockage in the inlet stream
No separation occurs.
Low level alarm.
HighHigh Flash drum pressure
- Blockage in the vapor stream
Risk of drum explosion.
Install pressure alarm.
High liquid level in the flash drum
- Blockage in the liquid stream
Less liquid leaving the flash drum.
Install high level indicators and high level alarm should be installed.
- Liquid stream too cold
Less vapor fraction, chances non-condensable will enter the column that follows.
- Install temperature controller on the feed stream.
DISTILLATION COLUMNGuide Words Parameter Causes Consequences Actions
Less Pressure - Leakage in the column
- Vapor lost and not recovered at the top.
Install pressure indicator on the column or replace vessel.
Level- Blockage in
the inlet stream
- No separation occurs.
Low level alarm.
Flow- Pipe partially
blocked- Pipe leakage
- Level decrease in distillation column
- Off specification product
- Back flow of material
Install check valve
Temperature
- Furnace Failure
- Low power supply
- Low energy steam
- Reaction favor to reactant formation
Install monitoring system and temperature sensorSupply enough energy
High Level - Output pipe blockage
- Overpressure of reflux drum
- Condensed liquid flow back in liquid
Install high level alarmScheduling inspection
Temperature
- Furnace Malfunction
- Temperature control failure
- Difficult to remove excess heat
- Steam become superheated
Install temperature sensorRegular system checking
Flow - High pressure from source
- Flooding in Distillation column
Install bypass line with a manual valve
RECOVERY OF PARA XYLENEMethods of recovery
Adsorption method
Distillation Method
Crystallization Method
PFD FOR CRYSTALLIZATION UNIT
MATERIAL BALANCEStream ID 1 2 3 4 5 6 6a 6b 7 7a 7b 7c
Total(LB/hr)
33000
36859
18429
18429 4213 3371
1 6742 26969
14037
11230 2807 7193
EthylBenze
ne2405 2687 1343 1343 313 2865 573 2292 196 157 39 100
ParaXylene 8283 9251 4625 4625 990 4180 836 3344 1193
2 9545 2386 6114
MetaXylene
18734
20925
10462
10462 2443 2238
4 4476 17907 1586 1269 317 812
OrthoXylene 3577 3995 1997 1997 466 4281 856 3425 308 247 61 158
ENERGY BALANCE
Mass Flow rate Process
Stream18000 lb/hour
Mass Flow rate Ethylene Refrigerant
15000 lb/hour
Inlet Temperature of Ethylene
-71 F
Outlet temperature of Ethylene
-18 F
Inlet temperature of Process
Stream-11 F
Outlet Temperature of Process
Stream-45 F
Mass Flow rate Process
Stream10375 lb/hour
Mass Flow rate Propane Refrigerant
9000 lb/hour
Inlet temperature of Propane
-1 F
Outlet Temperature of Propane
59 F
Inlet temperature of Process
Stream64 F
Outlet Temperature of Process
Stream25 F
2nd Stage Crystallizer1st Stage Crystallizer
COSTING
COSTINGPurchased Cost of Equipments (PCE)
Reacto
r
Furna
ce
Distilla
tion C
olumn
Flash
Drum
Heat E
xchan
ger
Pumps
Crystal
lizers
Melt Ta
nks
Centrif
uges
Surge
Drums
0100000200000300000400000500000600000700000
Cost/ $
Cost/ $
COSTINGPurchased Cost of Equipments
(PCE)$1394897.8
Physical Plant Cost (PPC) $3040976
Fixed Capital Investment (FCI) $4575263
Working Capital Investment (WCI)
$823547
Variable Costs $21766416
Utilities Costs $55023
Fixed Costs $2276826
Annual Production Cost $33660539
Profit Per Year $184828
Payback period
13.59 years
DISCOUNTED COSTINGDiscounted Purchased Cost of
Equipments (DPCE)$209234
Discounted Physical Plant Cost (DPPC)
$456129
Discounted Fixed Capital Investment (DFCI)
$686286
Discounted Working Capital Investment (DWCI)
$123531
Discounted Variable Costs $21766416
Discounted Utilities Costs $55023
Discounted Fixed Costs $2276826
Discounted Annual Production Cost
$33660539
Discounted Profit Per Year $184828
Payback period
2.04 Years
COSTING
Equip
emen
t cost
Indire
ct cos
t
Direct
cost
Fixed
capit
al inv
estmen
t
Working
capit
al inv
estmen
t
Total
capit
al inv
estmen
t
0200000040000006000000
DISCOUNTED VS NORMAL COST
NormalDiscounted
COST
/ $
DISCOUNTED VS NORMAL COST
SOURCE:United Nations Commodity Trade Statistics
Database
Pakistan Yearly Imports in US Dollars
17%
83%
BYCO’s POSSIBLE SHARE OF DOMESTIC PARA XYLENE MARKET
BYCO'S SHARE IMPORTS
Conclusion
Stable International
Market
Growing annual
Demand In Pakistan
Increased refinery capacity
HigherPurity
Lower Initial Investment