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