Transcript PPT Template

Slide 1
SSE TSS-1
What you need to know about
Petroleum Refining Simulation
Mike Donahue
NA Technical Support
Lake Forest, CA
© 2012 Invensys. All Rights Reserved. The names, logos, and taglines identifying the products and services of Invensys are proprietary marks of
Invensys or its subsidiaries. All third party trademarks and service marks are the proprietary marks of their respective owners.
What you need to know about
Petroleum Refining Simulation
1) All process simulators are not created equal
2) What you don’t know can hurt you
3) Good simulation design practice
4) Thermodynamics
5) Petroleum characterization
Slide 3
All Process Simulators are not Created Equal
Nor should they be….
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Invensys or its subsidiaries. All third party trademarks and service marks are the proprietary marks of their respective owners.
Refinery Process Modeling
Design
Operation
Regulatory Compliance
Safety Systems
Advanced Controls
Blending
Inventory Management
Asset Management
Energy Management
Slide 5
Refinery Process Modeling
Design
Dynamic
Operation
Regulatory Compliance
Safety Systems
Steady State
Advanced Controls
Blending
Inventory Management
Optimization
Asset Management
Energy Management
Slide 6
Simultaneous Equation Oriented Solvers
Dynamic
•
An equation based pressure/flow solver
•
Extremely efficient
•
Calculation simplifications required
•
Large computing power requirements
•
Slide 7
Designed to be spread over several machines
Simultaneous Equation Oriented Solvers
Optimization
•
A general EO solver
•
Very robust for well posed simulations
•
Small radius of convergence
-
•
Not practical for design
Large computing power requirement
-
Slide 8
Ideal for optimization
Single crude unit is typically over 5,000 eqns.
Steady State Solution Approach
Sequential-Modular
Steady State
•
•
•
Flowsheet is decomposed (sequenced)
Calculations are performed one unit at a time
Iterate tear streams
Simultaneous-Modular
Slide 9
•
Flowsheet is developed as a collection of subflowsheets (SFS)
•
Each SFS and collection of streams are solved
together
Advantages of Sequential Simulation
(Disadvantages of Simultaneous Approaches)
•
Intuitive
-
•
The resolution is divided-up into several subsets that are treated sequentially
This facilitates rigorous convergence, even in presence of extremely complex
modules that are treated in an autonomous way
Good heuristics for initialization and convergence
Slide 10
Problems localized to individual unit operations / recycles
Robust
-
•
Clear / understandable error messages
No over-specifications (inconsistencies)
Recycles estimates not required
Recycle blocks not required
Disadvantages of Sequential Simulation
(Advantages of a Simultaneous Approach)
•
Computation Time – Multiple passes are typically required to solve the flowsheet
~ 1,000
~ 50% increase in speed
~ 500 increase in computing
power
4 hours / 500
= 30 seconds
Slide 11
Notable Quotes
“Nonlinear equation solvers are not as robust and reliable as
the sequential modular approach.”
“The equation oriented approach is not currently a viable competitor to the sequential
modular approach for steady-state process simulation.”
Paul I. Barton
Department of Chemical Engineering
Massachusetts Institute of Technology
Cambridge, MA 02139
Optimization
Dynamic
Steady State
Optimization, Dynamic, and Steady State simulation all have their own simulation
requirements.
A solver designed to work in all three areas will never be as efficient as a solver
designed for one.
Slide 12
What you don’t know can hurt you
© 2012 Invensys. All Rights Reserved. The names, logos, and taglines identifying the products and services of Invensys are proprietary marks of
Invensys or its subsidiaries. All third party trademarks and service marks are the proprietary marks of their respective owners.
The Simplicity Trap
• “Easy to use and easy to train”
• “Very flexible / intuitive”
• “Shortens the learning curve”
• “Users with little prior knowledge can pick up and train quickly
and effectively”
Slide 14
The Simplicity Trap
• The goal of process simulation is to fundamentally understand
the behavior of your process system
• To accomplish this you need to fundamentally understand your
process simulator
Slide 15
Defaults
•
•
•
•
Slide 16
(One of the largest sources of error)
What is a default?
Where are they?
Have they been changed?
Should you use them?
Example Defaults in PRO/II
Slide 17
Example Defaults in PRO/II
Default Cut-Point Set
Modified Cut Point Set
-141.1 MM BTU/HR
5%
11%
657 BBL/HR
2027 BBL/HR
Slide 18
-149.3 MM BTU/HR
4.4%
736 BBL/HR
1941 BBL/HR
PRO/II Defaults
Iterations vs. Tolerance
Recycle Methane
8000
600
538
7500
500
Pounds/hour
Iterations
7775
7776
0.001
0.0001
0.00001
0.000001
6500
400
318
300
206
200
6000
5500
5000
4500
102
4000
100
3500
22
3433
3000
0
0.1
0.01
0.001
0.0001
0.00001
0.000001
0.1
Tolerance
Simulation time for 318 iterations – 38 seconds
Slide 19
7767
6939
7000
430
7680
0.01
Tolerance
Default Modifications
Slide 20
(have they been changed)
Default Error Mitigation
• Imperative for the engineer to understand the what, where, and
why’s of simulation defaults
• Manuals / release notes / training / tech support
Slide 21
Practice good simulation design
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Invensys or its subsidiaries. All third party trademarks and service marks are the proprietary marks of their respective owners.
Good Simulation Design
There are two ways of designing a process model:
•
One way is to make it so simple that there are obviously no problems
•
The other way is to make it so complicated that there are no obvious problems
The first method is far more difficult
Slide 23
Design Strategy
• Start Simple
1
DECANT
2
3
7
• Keep it Simple
8
– Justify Simulation Granularity
11
• Design for Change
12
NAPHTHA
KEROSTM
KERODRAW
DIESLSTM
DIESLDRAW
– Use Relative Specifications
– Calculate Enthalpies
15
16
• Document Complexity
CRUDE
MAINSTM
AGOSTM
AGODRAW
18
20 QFZ
RESID
Slide 24
Thermodynamics
Chaos will reign (2nd Law)
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Invensys or its subsidiaries. All third party trademarks and service marks are the proprietary marks of their respective owners.
Thermodynamic Chaos
Slide 26
•
Thermodynamic Method Selection
•
Thermodynamic Tuning
Thermodynamic Method Selection
•
Thermodynamic characterization is the most important aspect of
accurate process simulation
• There may be any number of thermodynamic methods suitable for a
given application
• Some are better than others (PR is not the answer to everything)
• There are several places where to can find thermodynamic guidelines
• Simulation Case books
• Application Briefs Manual
• Thermodynamic Application Guidelines
• 1 800 SIMSCI-1
Slide 27
Thermo Selection
Propane-Propylene Splitter
Does choice of Thermo affect the results?
Thermodynamic Condenser Reflux/Feed
System
Duty
Ratio
Slide 28
Peng-Robinson
-59.6
13.1
Grayson-Streed
-37.3
8.2
Amine Transfer Line Example
Sink Pressure vs. Mixture Velocity
35.00
30.00
25.00
SRK Thermo
SRKM Thermo
Mixture Velocity, ft/sec
Amine Thermo
20.00
15.00
10.00
5.00
0.00
25.00
50.00
75.00
100.00
Sink Pressure, psig
Slide 29
125.00
150.00
Thermodynamic Method Selection
• The thermodynamic method chosen should ideally be used
only in the temperature and pressure ranges at which the
parameters were regressed.
• Ideally, for each simulation, actual experimental or plant
data should be regressed in order to obtain the best
interaction parameters for the application.
Slide 30
Thermodynamic Tuning
Thermodynamic Systems
• K Values
• Enthalpy
• Vapor and Liquid Density
VLE/VLLE Equilibrium Modifications
• K-Value Data
• Binary Interaction Parameters
- Cubic Equations of State
- Liquid Activity Coefficient Models
• Alpha Formulations (PR & SRK)
Slide 31
Interaction Parameters
Effect of k12 on bubble point pressure of CO2 and Pentadecane at 313.15K
8
7
Bubble Poit Pressure, MPa
Pro/II
6
No Interactions
Data
5
4
3
2
1
0
20
25
30
35
40
CO2 mol%
Slide
Slide 32
45
50
55
60
Petroleum Characterization
© 2012 Invensys. All Rights Reserved. The names, logos, and taglines identifying the products and services of Invensys are proprietary marks of
Invensys or its subsidiaries. All third party trademarks and service marks are the proprietary marks of their respective owners.
Oil Characterization Issues
Slide 34
•
Fundamental Limitations
•
Oversimplification
•
Heavy Oil Characterization
Pseudocomponent Background
Why we use them
API Project 6
• Isolated over 16,000 distinct hydrocarbon compounds from a
single sample of Oklahoma crude.
• C40 has 62,491,178,805,831 isomers
Petroleum assays were utilized to reduce
the dimensionality of the calculations
• Molecular Modeling
– Molecular representation may be a viable alternative approach to the
characterization of petroleum fluids
– More work needs to be done
Slide 35
Fundamental Limitations
• Pseudo-components are developed to represent the unknown components
• Each pseudo-component corresponds to several unknown actual
components
• Doing this introduces a degree of uncertainty
Pseudo-component Properties (FCC Gasoline)
Slide 36
•
Cut-point range on TBP
150-175 F
•
Average NBP
164F
•
Average API
63.4
•
Average MW
84.4
Component
Class
NBP
API
MW
Octane
Hexane
paraffin
155.7
81.6
86.2
24.8
2,2 dimethylpentane
paraffin
174.6
77.1
100.2
92.8
MCP
naphtene
161.3
56.2
84.2
91.3
Hexene
olefin
146.3
72.2
84.2
83.0
1-M-cyclopentene
olefin
158.4
48.7
82.1
>100
4-M-cyclopentene
olefin
167.4
48.8
82.1
>100
Fundamental Limitations
Assays Change
Over Time
The general rule of thumb is to be wary of assays more than 2 years old for
simulation work
Slide 37
Oversimplification
Average Gravity Input
3rd Cut
First, Integrate
to Get NBP’s . . . .
1st Cut
2nd Cut
Light Ends
Temperature
3
API Gravity
Percent Distilled
. . . Then Use Watson K
Factor to Compute Gravity
Volume % Distilled
Slide 38
"K" =
NBP
SPGR
Oversimplification
No Bulk Properties
1.00
Measured
Specifivc Gravity
0.95
0.90
0.85
0.80
0.75
0.70
0
20
40
60
Wt. Percent
Slide 39
80
100
Oversimplification
No Bulk Properties
1.00
Pro/II
Measured
Specifivc Gravity
0.95
0.90
0.85
0.80
0.75
0.70
0
20
40
60
Wt. Percent
Slide 40
80
100
Oversimplification
No Bulk Properties
1.00
Pro/II
HYSYS
Brand X
Measured
Specifivc Gravity
0.95
0.90
0.85
0.80
0.75
0.70
0
20
40
60
Wt. Percent
Slide 41
80
100
Oversimplification
Petroleum Component Development
•
•
Cyclohexane
PRO/II
NBP
API
Brand X
NBP
MW
Tc
Pc
96.00
550
650
94.00
540
600
92.00
530
95.03
536.77
590.74
86.00
500
500
84.00
490
526.98
555.39
90.00
520
550
88.00
510
F
Tc,
PSIA
Pc,
•
84.16
85.54
491.51
455.05
82.00
480
450
80.00
470
78.00
460
400
Cyclohexane
Cyclohexane
Slide 42
ProII
ProII
BrandXXNBP
NBP
Brand
Oversimplification
Phase Envelope for L004 - Base Case
2000
1500
1500
Pressure, PSIG
Pressure, PSIG
Phase Envelope for L004 - Base Case
2000
1000
500
1000
500
0
-80
-60
-40
-20
0
20
40
Temperature, DEG F
Fluid
C6+ characterized as hexane
Slide 43
Fluid Traverse
60
80
100
120
0
-80
-60
-40
-20
0
20
40
60
80
100
Temperature, DEG F
Fluid
Fluid Traverse
C6+ characterized as petroleum component
120
Closing Thoughts
•
The goal of process simulation is to fundamentally understand the
behavior of your process system
•
To accomplish this you need to fundamentally understand your
process simulator
•
From development to training, it has always been our goal to
provide our customers with the best available tools for success
•
The only thing worse than no answer is the wrong answer
Thank You
Slide 44
Mike Donahue
(909) 593-1999
[email protected]
© 2012 Invensys. All Rights Reserved. The names, logos, and taglines identifying the products and services of Invensys are proprietary marks of
Invensys or its subsidiaries. All third party trademarks and service marks are the proprietary marks of their respective owners.