Europe User Conference: ADNOC optimization of hydrocracking process as a function of operating conditions
1. ABU DHABI NATIONAL OIL COMPANYABU DHABI NATIONAL OIL COMPANY
OPTIMIZATION OF HYDROCRACKING PROCESS
AS A FUNCTION OF OPERATING CONDITIONS:
APPLICATION OF RESPONSE SURFACE METHODOLOGY
MR. RIZWAN AHMED & DR. HAITEM HASSAN-BECK
ADNOC REFINING RESEARCH CENTRE DIVISION
2. OUTLINE
• Introduction
• Hydrocracking Process Description
• Data Required
• Model Development and output
• Utilization of Model
• PIMS
• Response Surface Methodology
• Summary
OPTIMIZATIONOFHCKPORCESSUSINGRSM
3. INTRODUCTION TO
HYDROCRACKING
Hydrocracking is a flexible catalytic conversion process in presence of
hydrogen that upgrades heavy feed stocks by:
Cracking large molecules to small ones to achieve the desired
boiling range products.
Removing impurities like Metals, S, N etc.
Saturation of olefins
Hydrocracking feeds can range from heavy vacuum gas oils and
Coker gas oils to atmospheric gas oils.
OPTIMIZATIONOFHCKPORCESSUSINGRSM
4. HYDROCRACKER IN REFINERY
CDU
OVHD Gases and Naphtha
Kerosene
Diesel
Atm Residue
VDU
OVHD Gases and Naphtha
LVGO
HVGO
Vacuum Residue
HCR
Fract.
OVHD Gases and Naphtha
Kerosene
Diesel
Products Unconverted Oil
H2
Crude Oil
OPTIMIZATIONOFHCKPORCESSUSINGRSM
5. HYDROCRACKER MODE OF OPERATION
Atm.
Residue
HVGO UCO
VDU HCK BO
UNIT
Base Oil
R E C Y C L E M O D E
O N C E T H R O U G H M O D E
VDU HCK
HVGO
UCO
Products
Atm. Residue
OPTIMIZATIONOFHCKPORCESSUSINGRSM
6. TYPICAL HYDROCRACKER UNIT
R1 R2
Feed
Heater
Product
Condenser
HPS LPS
Debutanizer
Debutanizer
Heater
Debut. gas
Fractionator
Recycle gas comp.
H2 Make up
Feed
Pre-Heater
HVGO
Feed
GO
Pump Around
H Kero
Pump Around
Net H Kero
Fr. Btm
Lt Kero
Pump Around
GO
Naphtha
Lt Kero
Hy Kero
Fr. Ovhd gas
Naphtha
Splitter
Hy Naph.
UCO
Quench H2
Naph. Split. gas
Lt Naphtha
To FG
OPTIMIZATIONOFHCKPORCESSUSINGRSM
7. KEY FUNCTIONS
Hydrotreating
De-metallization
Saturations
De-sulfurization
De-nitrogenation
Hydrocracking
Hetero Aromatics
Multi-ring Aromatics
Mono Aromatics
Paraffins
HCK Aims at decreasing the average molecular weight of the
feed stock to produce lighter cuts
OPTIMIZATIONOFHCKPORCESSUSINGRSM
8. KEY PARAMETERS
Hydrocrackers are
designed to run at a
variety of conditions
depending on type of
feed, desired cycle
length, expected
product slate, typical
range of different
parameters:
Sr. No. Process Parameter Range
1
Liquid Hourly Space Velocity
(LHSV) :
0.5 to 2.0 hr-1
2 Gas to Oil Ratio: 850 to 1,700Nm3/m3
3 Hydrogen partial Pressure: 103 to 138 bars
4 SOR temperatures : 357 to 385oC
OPTIMIZATIONOFHCKPORCESSUSINGRSM
9. ADVANTAGES OF HYDROCRACKING
REAL MONEY MAKER
Convert low value feedstock to high value saleable products
Hydrocracker gives nearly 15% volume increase in products
Products are clean and do not require any further treatment
Hydrocrackers normally give 97-99% conversion with recycle of
Unconverted Oil (UCO)
Alternately, UCO is an excellent raw material for production of base oil.
OPTIMIZATIONOFHCKPORCESSUSINGRSM
10. CATALYSTS
• HDM
• HDT (hydrotreating)
NiMo / Alumina
CoMo / Alumina
• HCK (hydrocracking) Bi‐functional Catalyst
Acidic Function (Cracking): Amorphous Silica Alumina
catalyst + Zeolite based catalyst for higher cracking
activity.
Hydrogenation Function: Metals or sulfided metals
Quench
HCK
HDM
HDT
OPTIMIZATIONOFHCKPORCESSUSINGRSM
12. CHOICE OF THE CATALYST
Catalysts are selected based on specific properties
Activity
Ability to increase the rate of the reactions involved
Selectivity
Ability to favor desirable reactions rather than others
Stability
Degradation of the activity and Selectivity over time by:
Formation of coke, adsorption of poisons (metals)
Loss of volatile active agents
Change in crystalline structure
OPTIMIZATIONOFHCKPORCESSUSINGRSM
13. NEED OF SIMULATION MODEL
Simulation Models Assist us in:
• Optimization studies
• Data generation for production planning purposes.
• Debottlenecking studies.
• Revamp Studies
• Capacity enhancement studies
OPTIMIZATIONOFHCKPORCESSUSINGRSM
14. DATA REQUIRED FOR MODEL
Feed and Product properties
Operating conditions
• Flow Rates and yields
• LHSV
• WABT
Catalyst loading details
Reactor temperature and pressure profiles
OPTIMIZATIONOFHCKPORCESSUSINGRSM
25. RESPONSE SURFACE DOE
Design-Expert® Software
Factor Coding: Actual
VI (-)
Actual Factors
A: WABT = 401
B: AGE = 0.514
C: T 90 = 520
-1.000 -0.500 0.000 0.500 1.000 1.500 2.000
146
147
148
149
150
151
152
A A
B BC
C
Perturbation
X: Deviation from Reference Point (Coded Units)
Y: VI (-)
Design-Expert® Software
VI
Color points by value of
VI:
151.133
146.273
X1: Actual
X2: Predicted
Predicted vs. Actual
146
147
148
149
150
151
152
146 147 148 149 150 151 152
OPTIMIZATIONOFHCKPORCESSUSINGRSM
26. RESPONSE SURFACE
R-Squared 0.9978
Adju. R-Squared 0.9934
Predicted R-Squared 0.9493
Design-Expert® Software
Factor Coding: Actual
VI (-)
Design points above predicted value
151.133
146.273
X1 = A: WABT
X2 = B: AGE
Actual Factor
C: T 90 = 520
0.505
0.508
0.511
0.514
0.517
0.52
0.523
398.5
399.5
400.5
401.5
402.5
403.5
146
147
148
149
150
151
152
VI(-)
A: WABT (0 C)
B: AGE (oC /(m3/kg))
VI =
-5.47375E+006
+26128.77846 * WABT
+9.18909E+005 * AGE
+10445.67108 * T 90
-2290.81894 * WABT * AGE
-49.84343 * WABT * T 90
-1733.78948 * AGE * T 90
-31.14632 * WABT2
-0.016462 * T 902
+4.32230 * WABT * AGE * T 90
+0.059446 * WABT2* T 90
OPTIMIZATIONOFHCKPORCESSUSINGRSM
27. HCK OPTIMIZATION
Based on multiple responses using simultaneous optimization technique by
Derringer& Suich(1).
Desirability function procedure:
1- convert each response yi into individual desirability di
2- 0 ≪ 𝑑𝑖 ≪ 1 if di at its goal or target then di = 1
if di outside its goal or target then di = 0
3- Then the design variables are chosen to maximize the overall desirability
𝐷 = 𝑑1 ∙ 𝑑2 ∙∙∙ 𝑑 𝑚
1
𝑚
(1): Derringer , G. and Suich, R. (1980)” simultaneous optimization of several responses variables”, Journal of quality technology, 12, 214-219.
OPTIMIZATIONOFHCKPORCESSUSINGRSM
28. HCK OPTIMIZATION CONTD
Solution
WABT AGE T 90 VI Conv.
H2
consump-
tion
Desirability
400.000 0.515 530.0 147.4 72.65 219.921 0.856
fixed fixed varies varies varies minimize
Response VI
Design-Expert® Software
Factor Coding: Actual
VI (-)
151.133
146.273
X1 = C: T 90
X2 = A: WABT
Actual Factor
B: AGE = 0.516432
398.5
399.5
400.5
401.5
402.5
403.5
520
522
524
526
528
530
146
147
148
149
150
151
152
VI(-)
C: T 90 (o C)
A: WABT (0 C)
148.658
150.873
147.857
150.873
148.658
147.857
OPTIMIZATIONOFHCKPORCESSUSINGRSM
29. SUMMARY
Hydrocrackers are among key the money-makers in a
refinery.
Models can be used for parametric studies to predict unit
performance and decision making for any change in feed
quality, throughput or desired conversion.
Models can be used to provide inputs for planning in
generation of LP vectors and data generation.
Using RSM, a useful model can enable process engineers
to optimize the HCK operation for base oil production.
OPTIMIZATIONOFHCKPORCESSUSINGRSM