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EB Plant
EQUATE Petrochemical Company
Agenda
EB Unit Description
EB Plant Overview
-Basic chemistry
-Design of EB plant
- Catalyst
-Operating conditions
EB Unit Description
The Ethylbenzene Unit consists of
three main sections:
1. Alkylation Reactor Section
2. Transalkylation Reactor Section
3. Distillation Section.
EB Unit Overview
EB Block Flow Diagram
EB simple flow
Fresh BZ
E1210
E1211
C1501
C1211
E1509
E1510
F1205
C1511
G1203/4
C2501
G1213/4
G1513/4
C1810/11
C1120
C1201
LP
PC
MP
ET
G1502/3
E1310
C8520
CC
E1111
F1205
Y1118
E1112
E1311
G1230/1
H1415
E1409
E1410
N2
Flr
Y1117
C1311
C1710
EB Tank
D2001
E1320
Y1116
E1711
C1401
G1413/4
C1301
C1110
Y1115
G1313/4
C1411
BZ
E1305
E1405
E1420
G1402/3
C1307
Residue
Tank
EB Plant Overview
-Basic chemistry
The chemistry of EB reactions is centered on Benzene
molecules and Ethylene molecules. The chemistry is
fundamentally based on carbon and hydrogen atoms
arranged in various combinations.
Benzene feed to the process is a six carbon ring
compound with three double bonds alternating between
the carbons, C6H6
Ethylene feed to the process is a two carbon molecule
with double bonds between the carbons, C2H2 C = C
In the EB Process there are two types of reactions:
1- Alkylation Reaction.
2-Transalkylation Reaction.
The reaction will produce Ethyl Benzene (EB) in the
presence of Zeolite catalyst
Alkylation Reaction
Alkylation reaction is the main reaction in EB process
where one ethyl group is supplied by Ethylene molecules
is being attached to one Benzene ring to produce Ethyl
Benzene (EB)
C6H6
+
C2H4 
C8H10
BZ
Ethylene
EB
The Alkylation reaction is an exothermic reaction, it’s an
irreversible reaction and essentially all the ethylene is
reacted
Poly Ethyl Benzene (PEB’s) are also produced while
producing EB
PEB reactions as shown below:
C6H5-C2H5
+
Ethyl Benzene
C6H4-(C2H5)2
Diethyl Benzene
C2H4
 C6H4-(C2H5)2
Ethylene
+
C2H4
Ethylene
Diethyl Benzene

C6H3-(C2H5)3
Triethyl Benzene
C6H3-(C2H5)3
Triethyl Benzene
+

C2H4
Ethylene
C6H2-(C2H5)4
Tetraethyl Benzene
Other minor by product are caused by :
1-Ethylene attached at the end of an ethyl group of EB
C6H5-C2H5
+
Ethyl Benzene
C2H4

Ethylene
2-Benzene reacts with Propylene
C6H6
+
C3H6 
Benzene
Propylene
C6H5-C4H9
Butyl Benzene (BB)
C6H5-C3H7
normalpropylbenzene (NPB)
3-Benzene reacts with Propylene
C6H6
+
C3H6 
C6H5-C3H7
Propylene
Benzene
Cumene (CUM)
4-Ethylene reacts with Toluene
C6H5-CH3 +
C2H4 
Toluene
Ethylene
C6H5-C3H7
Ethyl Toluene
At the design ratio of Benzene to Ethylene feeds is
2.5 molar basis and seven catalyst beds, the
alkylation reaction creates:
a.Diethyl Benzene 9.7%
b.Triethyl Benzene 0.6%
c.Tetraethyl Benzene
0.03%
d.Butyl Benzene
0.02%
Transalkylation (TA) Reaction
The purpose of TA Reactor is to reacts recycle PEB with Benzene to produce
EB.
C6H4-(C2H5)2
+
Diethyl Benzene
C6H3-(C2H5)3
Triethyl Benzene
C6H6

Benzene
+
C6H6
Benzene
2C6H5-C2H5
Ethyl Benzene

C6H4-(C2H5)2 + C6H5-C2H5
DiethyBenzene
EthylBenzene
C6H5-C4H9
+
Butyl Benzene (BB)
C6H6
Benzene

2 C6H5-C2H5
Ethyl Benzene
Design of EB Plant
Ethylene specification
Component
Requirement
Ethylene
99.96 vol. %, minimum
Methane + Ethane
0.02 vol. %, maximum
Acetylene
1 vol. ppm, maximum
C3 and Heavier
10 vol. ppm, maximum
Free Oxygen
2 vol. ppm, maximum
Carbon Monoxide
1 vol. ppm, maximum
Carbon Dioxide
5 vol. ppm, maximum
Hydrogen
2 vol. ppm, maximum
Nitrogen (as N2)
100 ppm, maximum
Sulfur (as S)
0.1 wt. ppm, maximum
Water
5 vol. ppm, maximum
Alcohol (as Methanol)
1 vol. ppm, maximum
Dienes
5 wt. ppm, maximum
Carbonyls (as MEK)
1 vol. ppm, maximum
Total Nitrogen Compounds
0.1 wt. ppm, maximum
Page 17
Benzene specification
Component
Requirement
Benzene
99.85 wt. %, minimum
Solidification Point (Anhydrous Basis)
5.40°C, minimum
H2S and SO2
0.1 wt. ppm, maximum
Total Sulfur
1 mg/l, maximum
Thiophene
1 wt. ppm, maximum
Acidity
No free acid
Acid Wash Color (Anhydrous Basis)
No. 2, maximum
Total Chlorides (as Chlorine)
3 wt. ppm, maximum
Water
200 wt. ppm, maximum
Nitrogen Compounds
1 wt. ppm, maximum
Non-Aromatics
1000 wt. ppm, maximum
Toluene
500 wt. ppm, maximum
Copper Corrosion
Shall pass test
Bromine Index
10, maximum
EB Specification
Component
Requirement
Ethylbenzene
99.85 wt. % Min.
Nonaromatics
500 ppm wt. Max.
Benzene
1000 ppm wt. Max.
Toluene
1000 ppm wt. Max.
Benzene + Toluene
1000 ppm wt. Max.
Styrene
500 ppm wt. Max.
Xylenes
50 ppm wt. Max.
Cumene
100 ppm wt. Max.
Diethylbenzene
2 ppm wt. Max.
Sulfur
Total Chlorides (as Chlorine)
2 ppm wt. Max.
Color, Pt-Co
5 Max.
2 ppm wt. Max.
Ethylene feed system
Control Ethylene feed rate to the Alkylation
reactor
Control Plant EB Capacity
Ensure B/E ratio is acceptable
Benzene feed system
Remove catalyst poisons from benzene
Take regular samples to track guard bed
performance
Replace BZ treater4 mol-sieve as needed
Use freshest mol-sieve in “downstream”
treater
Alkylation system
React ethylene with benzene to make
Ethylbenzene
Control reaction parameters for optimum
selectivity and catalyst life



B/E ratio at 2.5 (molar) or 7.04 (weight)
Inlet temperature
Water concentration
Alkylator Reactor
Reactive Guard
Bed
Alkylator
Intercooler
Ethylene mixers
Reactive Guard Bed
Separate vessel containing catalyst
Allows replacement while keeping unit in
operation
Catalyst aging typically only in first bed
Transalkylator
React PEB with benzene to make EB
No Temperature increase
Preheater to control reactor temperature
Benzene column
Recover benzene from
reactor product
Furnace reboiler
Condenser generates
MP steam
0.5% EB in overhead
700 ppm Bz in bottom
product
EB column
Separate EB product from
PEB and heavies
Steam reboiler
Condenser generates
LP steam
1 ppm DEB in
EB product
1 wt% EB in bottom product
PEB column
Separate PEB product
from heavies
Steam reboiler
Condenser preheats
condensate (BFW)
50 ppm dicyclics
in PEB product
5 wt% TEB in
bottom product
Lights Column
Dry fresh benzene
(<25 ppm in bottoms)
Remove non-aromatics
and lights components
Heat input by vapour
stream from Bz column
Condenser preheats
fresh benzene
Portion condensed by Cooling Water
Benzene treaters
Remove organic N-components
from benzene
Mol-sieve operating at
elevated temperature (115°C)
Benzene Treaters contains
two types of molecular sieve,
which has function:
1. As water adsorber  4A molecular sieve
2. As benzene impurities adsorber  13X
molecular sieve
Volume ratio between water adsorber and
benzene impurities adsorber  1 : 3
Benzene Treater contains of two types of molecular
sieve, which has function:
1. As water adsorber  4A molecular sieve
2. As benzene impurities adsorber  13X molecular
sieve
Volume ratio between water adsorber and benzene
impurities adsorber  1 : 3
Basic chemistry in the Benzene Treater:
C6H6
Benzene
+
B
Basic compound
dissolved in Benzene
+
A
Active site on
Molecular sieve

C6H6
Benzene without
Basic compound
+
BA
Basic compound
attached
to molecularsieve
EB Plant
Catalyst:
Zeolite catalyst.
Type :
1- EM – 3300 (Alkylation Reactor)
2- EM – 3700 (TA Reactor)
Catalyst poisons:
Nitrogen compounds will deactivate the catalyst
by neutralizing acid sites. Maximum 1 ppm in
Benzene feed and 0.025 ppm out of the RGB.
Chloride will interact and weaken the catalyst
binder. Maximum 1 ppm in Benzene.
Water, will deactivate the catalyst.
Metals, will permanently deactivate the catalyst.
Operating Condition
Alkylation Reactor
1. BZ to C2 ratio : 7.04 wt/wt or 2.5mol/mol
2. C2 conversion is nearly 100%
3. Effluent Pressure : 34.1 kg/cm2
4. Inlet bed temperature : 195 °C
5. Outlet bed temperature : 257 °C
6. Catalyst : EM-3300
TA Reactor :
1.
2.
3.
4.
5.
BZ to PEB ratio
DEB Conversion
Effluent pressure
Operating temperature
Catalyst
: 2.0 wt/wt
: 62%
: 31.1 kg/cm2
: 200°C
: EM-3700
Light Column
1.
2.
3.
4.
5.
Operating pressure
Overhead temperature
Bottom temperature
Number of tray
Water content at bottom
: 1.5 kg/cm2
: 111 °C
: 115 °C
: 20 trays
: 25 ppm (design)
BENZENE TREATER
1.
2.
3.
4.
5.
Operating pressure : 18.2 kg/cm2
Inlet bed temperature : 110 °C
Delta pressure
: 0.35
N2 compound at outlet: 30 ppb (0.03 ppm)
Adsorbing media
: Molecular sieve (4A and 13X)
BENZENE COLUMN
1.
2.
3.
4.
5.
6.
7.
8.
Operating pressure
Key component temperature
Reflux ratio
Overhead temperature
Bottom temperature
Number of tray
BZ content at bottom
EB content at overhead
: 13.2 kg.cm2
: 269 °C (tray 11)
: 1.62
: 200 °C
: 280 °C
: 40 trays
: less than 700 ppm
: 0.5 % wt
EB COLUMN
1.
2.
3.
4.
5.
6.
7.
8.
Operating pressure
: 1.1 kg/cm2
Key component temperature : 221 °C (tray 5)
Overhead temperature
: 169 °C
Bottom temperature
: 231 °C
Reflux ratio
: 1.3
Number of tray
: 54 trays
EB content in the bottom
: < 1% wt
DEB content in the overhead : < 1 ppm
PEB COLUMN
1.
2.
3.
4.
5.
6.
7.
8.
Operating pressure
: -0.8 kg/cm2
Key component temperature : 176 °C (tray 4)
Overhead temperature
: 141 °C
Bottom temperature
: 229 °C
Reflux ratio
: 0.2
Number of tray
: 20 trays
TEB content in bottom
: < 5 %wt
Heavies content in overhead : < 50 ppm