4528.R380.02 Slide Handout for Students

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Dynamic Modeling using UniSim® Design4528 (UDS-310)Slides for student use

Dynamic Modeling usingUniSim® Design

4528 (UDS-310)

Presenter NameDate

Client Name (optional)

2 © 2009 HONEYWELL. All Rights Reserved HONEYWELL - CONFIDENTIAL 4528.R380.02

Introductions

• About You:- Your name?- Your job role?- How you currently use modeling tools?- Your experience with UniSim Design?- The one thing that you want to take away from this course?

• About Me?- My Name- My Experience

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Getting Help after the course is finished

You can contact the UniSim Design Support Team:

• Via Email at [email protected]• Via phone at 1-866-392-8748 (NALA)

+32 (0) 2 728 2200 (EMEA)• Via the internet at www.honeywell.com/ps


Course Outline

• Introduction to UniSim Design and the UniSim Design Suite

• What is this course all about?• Outline of the course modules• Course modules and workshops

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UniSim Design is a process simulation tool.

• Steady State Capabilities - Full Component Database, over 3000 available components- Diverse selection of unit operations, including:

Piping equipment – pipes, valves, mixers, tees, etc.Heat exchanger equipment – heaters, air coolers, LNG, etc.Vessels – two and three phase separators, tanks, etc.Reactors – conversion, kinetic, PFR, CSTR, etc.Rotating Equipment – pumps, compressors, expanders.Columns – distillation, absorbers, short-cut, etc.

• Dynamic Capabilities- Most of the steady state operations work in dynamics- Plus…

Controllers (PID & MPC), Digital ops, Relief Valves, Fired Heater, etc.


Process Simulation – UniSim® Design

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Process Simulation – Dynamic Option


UniSim® Design Suite – Integrated Modeling

• UniSim® Design can bring the steady state and dynamic worlds together

- with Integrated Modeling:

a steady state case can easily be converted to a dynamic one you can use the same program for both steady state and dynamicsimulationssteady state cases do not have to be rebuilt in order to create the dynamic simulation

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Course Objective

• An introduction to Dynamic Modeling using UniSim® Design Dynamic Option

- Course Notes assume no knowledge of UniSim® Design Steady State / Dynamic Option

• Learning/Using UniSim® Design Dynamic Option• Based around an offshore platform model


Housekeeping Items

• Course Materials – this is your own copy to keep

• Introduction to course area- Location of Washrooms- Coffee/Tea and refreshments- Arrangements for lunch- Use of Cellular phones, please be considerate.

• Timing Issues- 9:00 – 17:00- Lunch: 12:00 – 13:00- If we return from breaks on time, we should be able to stay

on track for a 17:00 finish.

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- Build Steady State Model- Transition to Dynamics- Add Dynamic Details


- Expanding the Model

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-Add Compressor Section-Add Anti-Surge Loop and Controller


-Add TEG Column+ Event Scheduler+ Cause & Effect Matrix

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Structure of Training Material

• Material is broken into several modules (chapters)• Each module will focus on one or more areas• Most of your time will be spent working on your

own. This type of “Hands on” training is very effective.

“Tell me and I forget,Show me and I may remember,Involve me and I understand.”Benjamin FranklinScientist, Statesman


Modules Covered

1. Getting Started in Steady State2. Pressure Flow Solver and Dynamic Concepts3. Transitioning from Steady State to Dynamics4. Control Theory Review (reading only)5. Dynamic Details6. Expanding the Model7. Compressor8. TEG Dehydration Tower9. Event Scheduler10.Cause and Effect Matrix11.Building a Fired Heater

Day One

Day Two

Day Three

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Modules Covered



Module 1 – Getting Started in Steady State

• Learning Objectives

- Methods for moving through the different environments- Selecting property packages and components- Adding streams- Adding unit operations

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Process Simulation

• What information do we need to enter?

• Thermodynamic Information- A list of all the components that are needed.- Selection of an appropriate model. Could be:

EOS (PR or SRK)Activity Coefficient Model (NTRL or UNIQUAC)Other (Steam Tables, Antoine, etc.)

• Process Information- Feed stream conditions. (T, P, Flow, Composition)- Unit operation information.- What unit operations are needed?


How do we do this in USD?

• Via the two main USD Environments

- Basis Environment Flowsheet Environment

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UniSim Design ArchitectureSi

mul

atio

nEn

viro

nmen

t

Oil

Envi

ronm

ent

Bas

isEn

viro

nmen

t

Property Package

FLUID PACKAGE

Hypo Cpts

HYPO GROUP ASSAY

BLEND

ASSAY

BLEND

StreamsOperations

SUB-FLOWSHEET

SimultaneousSolver

COL SUB-FLWSHT

Column -Operation

Special typeof OperationStreams

Operations

MAIN FLOWSHEET

Each Sub-Flowsheet has its own “Environment”

StreamsOperations

SUB-FLOWSHEETStreamsOperations

SUB-FLOWSHEET

Components

CPT LIST

Property Package

FLUID PACKAGE

Property Package

FLUID PACKAGE Components

CPT LISTHypo Cpts

HYPO GROUP


UniSim Design Structure

Simulation Environment

Basis Environment

Oil Environment

PFD

Workbook

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UniSim Design

• USD Key Features- Calculates Bi-Directionally- Calculates as much as it can,

as soon as it can• Primary Interface Elements

- PFD- Workbook- Object Property Views


Tips for working in the Basis Environment

• Every Fluid Package needs a component list and a property package.

• The Peng-Robinson EOS has been optimized for use with most “Oil & Gas” applications in UniSim Design.

• It is very important the right property package is chosen. The accuracy of the model depends on this choice.

• The “Master” component list is a superset of all components in the other lists. It can not be selected as the component list for use in a fluid package.

• Fluid Packages can be exported and shared with colleagues.

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Preferred UniSim Property Package

PR, PR OptionsReservoir Systems

PRTEG Dehydration with AromaticsPRSV, NRTL HF AlkylationActivity Models, PRSVChemical SystemsPRHydrate InhibitionSteam Package, CS or GSSteam Systems

PR, ZJ or GS (see T/P limits)High H2 SystemsLee Kesler PlockerEthylene Towers

PR, PR Options, GS(<10mmHg), Braun K10, Esso K

Vacuum TowersPR, PR Options, GSAtm Crude TowersPR, PRSVAir SeparationPR, PRSVCryogenic Gas ProcessingSour PRSour WaterPRTEG DehydrationRecommended Property MethodType of System


Tips for adding streams and operations

• There are four methods for adding objects- Flowsheet Menu, - F11 or F12,- Object Palette,- Workbook

• Streams can also be added by typing their name into the connections page for a unit operation. - Use this option carefully as a simple typo will result in a

undesired connection.

• To connect objects, use the drop-down lists or the PFD attach mode

• Hold down the Ctrl key to quick access this mode

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Stream Calculations

• Intensive Calculations- Flash (Phase Equilibrium) & Property Calculations- “Stream” Utilities – Phase Envelope, Property Table, Hydrate

Formation, CO2 Freeze Out, BP Curves, etc.

• Extensive Calculations (required for flowsheeting)- Material Flows- Energy Flows


Degrees of Freedom in UniSim Design

• For streams, only two of the five “state” variables can be specified. (P, T, H, S, or VF).

• Normally, the user will specify T-P, T-VF, or P-VF.• For dew point calculations, Set the VF = 1, and enter

T or P. UniSim Design will calculate the other parameters based on the thermo model that has been chosen.

• Likewise, the bubble point can be found by setting the VF to 0.

• Never specify more than one type of flow. - Mole, Mass, Liquid Volume @ std. cond. or Std. Ideal Liquid

Volume

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Stream Property View – Input & Output

Enter Data “in place”

Unit Conversions “in place”

Colour Coding: red, blue, black


Modules Covered

1. Getting Started in Steady State2. Pressure Flow Solver and Dynamic Concepts3. Transitioning from Steady State to Dynamics4. Control Theory Review (Reading only)5. Dynamic Details6. Expanding the Model7. Compressor8. TEG Dehydration Tower9. Event Scheduler10.Cause and Effect Matrix11.Building a Fired Heater

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Module 2 – Pressure-Flow Theory

• Learning Objectives:

- The basic concepts of dynamic simulation with UniSim®

Design- Dynamic pressure flow specifications


Lecture Content

• Solving Method in UniSim Design Dynamics• Lumped Models• Integration Techniques• Types of Operation

- Pressure Nodes- Resistance Devices

• Pressure-Flow Networks• Simultaneous Solution Approach for P-F balances• Degrees of Freedom Analysis• Dynamic Assistant

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Solving Method in UniSim Design Dynamics

• The Dynamic Solver in UniSim® Design is not the same as the Steady State Solver

• In Dynamics UniSim Design uses a hybrid solver:- Integrates numerically over time- Solves simultaneous equations for pressure-flow network- + Sequential modular solution of

Energy BalancesControl / Logic CalculationsComposition

- Not all calculations are done all the time…


Assumption - UniSim uses a Lumped Model

• Distributed system –- thermal and component gradients in 3D (x, y, z) are taken

into account with the timeNeeds partial differential equations in space and time domain

• Lumped system –- x, y, z gradients are ignored and all the physical properties

are considered to be equal in spacecan be represented with a set of ordinary differential equations (ODEs)

• The lumped method saves calculation time and provides a solution reasonably close to the distributed model solution

• UniSim® Design can also consider static headcontribution to pressures

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Integration Techniques

• Integration of pressures-flow network, enthalpies and composition

- Four different time step sizes:- Pressure-flow network ← smallest time step- Control & Logic ← smallest time step- Enthalpy balances ← intermediate time step- Composition calculations ← largest time step

(tend to changemore gradually)

• Integration Method- Fully Implicit Euler integration method- Has characteristics of being stable and fast


Types of Operations

• In Dynamics, with the P-F solver, unit operations can be classified in two categories described by a model using: - Pressure Node equations

e.g.: separator, tray section…when allowance is made for accumulation (holdup)

- Resistance (or Conductance) equations e.g.: valves, heater, pump, cooler

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Pressure Nodes – Principle

All Unit Operations with significant holdup- In this type of operation, allowance is made for the accumulation of

material in the operation –Volume is important

- The Pressure-Flow relationship can be defined as:

• In words: the pressure in the operation is a function of the Volume, Temperature, and Net Flow of the operation

Vessel has fixed geometry (Volume) thus 0=dtdV

( )TMVfdtdP

,,=


Pressure Nodes – Principle

A volumetric flow balance can be expressed as:

(Volume change due to pressure change) +(Volume change due to flow change) +

(Volume change due to temp change) = 0

0=ΔΔ

+ΔΔ

+ΔΔ

tV

tV

tV TFP

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Assumptions

• Modeling Strategy - model actual configuration by a number of compartments or

holdups- i.e. each unit op can have more than one holdup volume

• Key assumptions - each phase is assumed to be perfectly mixed

(lumped model)- mass and heat transfer occur between feeds to the holdup

and material already in the holdup- mass and heat transfer occur between phases in the holdup


Resistance (or Conductance Equations)

• The P-F relationship of these operations can be defined as:

- The “k” term is determined from the steady state flow and pressure drop

- Examples of this type of operation include:Heater and CoolersHeat ExchangersPumps and Compressors (although k is not entered by the user)

PkF Δ= ρ

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Resistance Equations – for the Valve

• For the Valve, UniSim uses the turbulent flow equation:

- Valve operation uses a different equation to the general ones.

- The “k” term is replaced by another term that incorporates the Cv of the valve and its opening percentage.

( )21 PPCvfF ,,=


Pressure-Flow Network

• In terms of pressure and flow, the model is considered in terms of nodes and resistances (or conductance)

• Flows are related to the change of pressure at nodes, the resistance across valves and the conductance through process equipment

• The result: Significant coupling between the pressure-flow equations

• Flows and pressures are determined from simultaneous solution of a set of linear and non-linear equations

Note that each pair of pressure nodes, needs some

way to calculate the flow between them!

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Simultaneous Solution of Pressure-Flow Network

• Pressure/Flow specs made on boundary streams (feeds/product)

• Internal pressures and flows solved at each integration step by simultaneous Pressure-Flow solver, based on the Pressure-Flow network


Pressure-Flow Network Degrees of Freedom Analysis

• 7 variables will define the system- P,F of

Feed1 (2)Product1 (2)Product2 (2)

- V-100 Pressure (1)

• 4 equations define the flowsheet- Turbulent Flow Equation:

(3)

- V-100(1)

• DOF: 7 - 4 = 3- Specification of 3 variables

completely defines this system.

12 PPkF −=

( )TMVfdtdP

,,=

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Consistent Pressure-Flow Specs

• A variety of specifications can be made:- Pressure specification on

material stream- Flow specification on material

stream- Fixed pressure drop across

equipment- Pressure-Flow equation (for

valves)- Conductance equations (for

process equipment)


Inconsistent Solution

Possible Solution:• Specify:

- Feed (P)- Stream 1 (P)- VLV-100 (ΔP)- DOF=0

• But Feed P, Stream 1 P and ΔP are related by the equation:- P1 - P2 = ΔP- Hence Inconsistent solution

Flowsheet under-specifiedThe specifications are redundant

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Consistent Solution

Consistent Solution:

- Pressure Specification made on all boundary streams

- Vessel Pressure calculated by Holdup Equation

- Stream pressures calculated by Resistance Equation


Another solution

Consistent Solution

- No Valves on Boundaries- UniSim® Design uses a lumped

parameter model (no pressure gradients inside vessel)

- If one pressure is known, then all pressures known

• Solution:- 1 Pressure Spec - 2 Flow Specs

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Pressure-Flow Guidelines

• One P or F spec must be made on every boundary streams (feeds/product):- Use P Specs on boundary streams attached to valves and other

resistance equation operations- Use F Specs on boundary streams attached to all other operations

• Before a dynamic simulation can be run, a pressure gradient must be established through the entire flowsheet

• UniSim® Design will use the defined pressure-flow specifications and the pressure-flow equations from the unit operations to solve the pressure-flow network

• A very important point to remember: - Pay attention to the pressure gradient in your flow sheet:

No Pressure Gradient = NO FLOWPositive Pressure Gradient = INVERSE OR NEGATIVE FLOW


Pressure Flow Theory - Summary

• Pressure – Flow Solver used in Dynamics

• Two Types of Operations- Pressure Node Operations – Calculate a Pressure- Resistance Device Operations – Calculate a Pressure Drop

• Pressure/Flow specs are required in the boundary streams

• No Pressure gradient = No Flow- Use Shift-P on PFD to verify pressure gradient

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Solution Procedure - Summary

• Solve Pressure-Flow Network for entire flowsheet- Every Time Step

Pressure NodesResistance DevicesMaterial Balances (Holdup)

• Logical operations- Every Time Step

Controllers and Boolean operations

• Solve Energy - Every 2 Time Steps (Configurable)

Heat transfer

• Solve Composition (Flash) Calculations- Every 10 Time Steps (Configurable)

VLE / Thermo


The Dynamics Assistant

• Reviews the Process flowsheet and recommends appropriate P-F and dynamic specifications

• Identifies Process Equipment that has not been sized

• Can be accessed on demand at any time

• You do NOT NEED to follow its recommendations!

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Equation Summary View

• Used to provide specification and convergence information

• Useful for troubleshooting convergence issues


Integrator Properties

• Used to define numerical integration parameters• Define execution rates• CTRL I for quick access.

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Integrator Dialogue Box

• Pressure-Flow Specifications- While integrating, values for the P-F specs can be changed,

however, the structure of specifications may not be altered- When the integration is stopped the structure of P-F specs

as well as their values can be changed • Static head contributions can be activated• Static head is a function of

- Equipment holdup- Nozzle elevation difference


Dynamics Toolbar

Integrator in Automatic

Set multiple steps

Take multiple time steps

Set desired real time factor

Real time

Take one time step

• Dynamics Toolbar allows single click control of Integrator functions in Dynamic mode

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Modules Covered



Module 3 - Transitioning from Steady State

• Learning Objectives- Size equipment- Define pressure-flow specifications- Add Controllers- Add Strip Charts- Run a simple dynamic simulation and observe the role of the

various controllers

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Process Overview - Module 3


Transitioning from Steady State

• Key Points to consider:- Equipment Sizing- P-F Specifications- Controllers- Strip Charts

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Equipment Sizing

• Size the ValvesValve TypeNormal valve opening positionPressure drop across the valveCurrent flow rate

• Size the SeparatorVolume = 127 m3

• Size the CoolerVolume = 15 m3


• Boundary Material StreamsPressure SpecificationFlow Specification

• EquipmentFixed Pressure DropPressure/Flow equations

• ‘Cv’ – Valves• ‘k’ – process equipment

Pressure Drop Specifications

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Boundary Streams

• Valves on Boundary Streams- Minimum

Insert a valve on all boundary streams (feed and product) which are not already connected to a conductance device (heat exchanger, coolers, heaters)

- IdealInsert a valve on all boundary streams (feed and product)

• All boundary streams must have a pressure and/or flow specification

Ideally only pressure specifications should be used on boundary streamsCan use flow specifications but need to be careful


Process Equipment

• Vessel Rating informationVessel Volume – including boot capacity if applicableNozzle location

• Valve Rating InformationValve type and Cv valueUse pressure / flow relationship for pressure drop

• Conductance Equipment InformationEquipment volume and ‘k’ valueNozzle location – if applicableUser ‘k’ value relationship for pressure drop

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Controllers

• Once the controller has been added- Select Process Variable Source- Select the Minimum and Maximum

values of Process Variable- Select Output Target Object - Size the valve – set controller range - Select Controller Action,

Reverse or Direct- Input controller Tuning Parameters

Kc controller gainTi integration timeTd differential time

- Choose the mode of the controllerManual, AutomaticLocal or Remoted Set Point (Cascade)


Controller Action

- Direct Acting If the PV increases - Open the ValveIf the PV decreases - Close the Valve

- Reverse ActingIf the PV increases - Close the ValveIf the PV decreases - Open the Valve

Reverse

Reverse

Direct

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Cascade Control

• Cascade control is a common control technique loop that uses two controllers within one feedback loop

• The two controllers are not independent, but linked together with the ‘primary’ controller setting the SP for the ‘secondary’controller

• Cascade controller can improve the dynamic response and controllability of a process that has considerable dead time, orwhere the time response of the primary loop is very large


Controlling Streams Directly

• Controller can connect directly to energy and material streams

• In both cases need to size the “Control Valve”- Specify Minimum and Maximum

values

• If controlling streams directly need to have a Flow specification on stream- If controlling molar flow, need

molar Flow spec etc.

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Modules Covered



Module 4 – Basic Control Theory

Not meant to teach Process Control…

Would recommend…

Svreck, Mahoney, Young“A Real-Time Approach to Process Control”,

Wiley & Sons, (2000)[ ISBN 0 471 8045 25]

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Modules Covered

1. Getting Started in Steady State2. Pressure Flow Solver and Dynamic Concepts3. Transitioning from Steady State to Dynamics4. Control Theory Review (reading only)5. Dynamic Details6. Expanding the Model7. Compressor8. TEG Dehydration Tower9. Event Scheduler10.Cause and Effect Matrix


Module 5 – Dynamic Details


Add valve characteristicsAdd heat loss modelsUnderstand nozzle locationsMake changes/additions to the dynamic model

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High Fidelity Dynamic modeling in UniSim

• UniSim Design allows extra ‘High Fidelity’ settings to be made within the model

Static head contributions – Explicit or ImplicitNozzle LocationsNozzle EfficienciesDetailed Valve Actuator InformationDetailed Heat LossRotating Equipment Inertia

• Historically, to use these a separate ‘Fidelity’ option needed to be turned on

This is now switched on by default


Valve Actuator Details

• Actuator Dynamics- Instantaneous- Linear (Actuator Linear Rate)- First Order (Actuator Time Constant)- Second Order (Actuator Time constant

and Damping Coefficient)• Actuator Dead Time

• Stickiness Time Constant

• Leaky Valves- Minimum valve close position

• Emergency Shut Down Trip- Open valve- Shut valve- Hold valve position

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Valve Characteristics

% C

vor

F(x

)

% Valve Position

From HYSYS Ops Guide Manual

Valve Linear

Valve Linear


Nozzle Location

• Default nozzle settings:- Nozzle location as percentage

of vessel height:Vapour product 100%Feed 50%Liquid product 0%

- Nozzle diameter: 5% of vessel height/diameter

• Outlet product vapour phase is determined by phase level in nozzle

Vapour product nozzle with 50% liquid coverage will have VF=0.5Heavy liquid product nozzle with 50% light liquid coverage will have VF=0 but liquid will be 50% light liquid

• Nozzles are always in the vessel side wall

What if the real vessel has nozzles in the bottom surface?

Model the nozzle at 0% height with very small diameter

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Molar phase fraction depends linearly on liquid level in nozzle

i.e. 25% level in nozzle = 0.25 phase fraction in product stream

Nozzle Location


Accumulation

• Calculated As:

Accumulation = MaterialRecycle + MaterialFeed - MaterialProducts

• Recycle Stream- Not a physical stream in the unit operation- Represents the material already inside the holdup volume

Vapour

Liquid

Feeds Products

Recycle

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Nozzle (Flash) Efficiencies

• Amount of mixing that occurs between the feed phase and the existing holdup

• If all efficiencies are 1 than all feeds reach equilibrium• If the values are lower, the phases can not be in equilibrium

and can have different temperatures• Flash efficiency is the fraction of feed stream that participates

in the rigorous flash.

Products

Feeds

Vapour

Liquid

Recycle


Nozzle Efficiencies

• Available from the “Advanced”button on the Dynamics tab,Holdup page

• Allows modeling ofnon-equilibrium vapour spacelike

High purity condensersColumn sumpsGas (N2, fuel gas) blanket pressure control

• Nozzle EfficiencyControls the amount of feed which takes part in equilibrium flashTypically only vapour value is changedFeed nozzle used with forward flowProduct nozzle used with reverse flow

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Static Head

• Enabled on the Integrator window• Static head pressure contribution

superimposed on P-F solver calcs


Detailed Heat Loss

• Allows detailed modeling of heat loss

Specify metal and insulation thermal propertiesSpecify individual heat transfer coefficients

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Modules Covered



Module 6 – Expanding the Model


- Add unit operations and controllers in Dynamics mode- Make necessary P-F Specs for the system- Implement appropriate control strategies- Install a relief valve

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Model Details


Model Details

• Knock Out DrumLevel – Flow cascade

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Model Details

• Low Pressure Separator - LevelOn/Off level control for aqueous liquidLevel – Flow cascade control for hydrocarbon liquid


Model Details

• Low Pressure Separator – PressureSplit range pressure controlRelief Valve

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Model Details

• Heat Exchangerk value estimation


Digital Point Operation

• Digital Point Operation- Translates PV into Boolean input- Or connects Boolean output to

valve opening On/Off ControllerOptional input and output to model equipmentManual or Automatic modesOutput can be pulse (pulse On or pulse Off) or latchedOptional dead band (above and/or below threshold)

- NB Use valve Actuator Digital Position as OP

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Digital Point Example

- Threshold = 100- Upper Dead Band = 45- Lower Dead Band = 20- On when PV >= Threshold


Relief Valve

• Required informationSet PressureFull Open PressureStandard Orifice DesignationorOrifice Area

• Optional informationViscosity CoefficientDischarge CoefficientBack Pressure CoefficientValve Head Differential Coefficient

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Relief Valve

• Enable Valve HysteresisClosing PressureReseating Pressure

• Enable Liquid ServiceSolves the valve opening simultaneously with pressure and flow.Provides greater stability for liquid service and fast transient vapour systems


Air Cooler and Pump

• Air Cooler –- Specify UA and fan details, - Control fan speed to give required outlet

temperature

• Pump –- Generate Characteristic curves, - Specify pump speed

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Heat Exchanger

• Supply:- k values for each side- Overall UA- Possibility for k and UA

scaling with flow


Valve ESD and Actuator Malfunctions

• Set Valve ESD trip behavior • Program possible valve malfunctions

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Revision Control

• Can configure a standard file naming convention with automatic version number increase etc…

• Pop up box appears on Save As allowing values to be entered


Modules Covered


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Module 7 - Compressor


Specify head and efficiency curves for compressorUse multiple curves to model compressors


Model Details

• CompressorSurge ControllerDischarge Pressure control

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Centrifugal Compressor

• Allows single or multiple curves

Curves entered in tabular formDisplayed in tabular or graphical form

• Will interpolate or extrapolate as required


Compressor – Electric Motor

• Can add an Electric Motor as the driver for the compressor

Enter torque curveGear ratioTakes one dynamic specification

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Surge Controller

• Surge controller added from Dynamics tab Specs page of Compressor

• Enter regular controller tuning parameters

• Surge Controller parameters4th order polynomialControl LineBackup LineQuick Opening rate


Surge, Control and Backup Lines

( ) ( ) ( )433323 smQDsmQCsmQBAHead ⋅+⋅+⋅+=

• Surge Flow Equation:

• Control, Backup Line = Fixed percentage above Surge Flow Values

Compressor Surge Control

0.0

500.0

1000.0

1500.0

2000.0

2500.0

3000.0

3500.0

4000.0

4500.0

0.0 2000.0 4000.0 6000.0 8000.0 10000.0 12000.0 14000.0 16000.0 18000.0

Flow (m3/h)

Head

(m)

2488 rpm

3733 rpm

4977 rpm

6177 rpm

Surge Line

Control line

Backup line

Surge Line

Backup Line

Control Line

Page 53



Modules Covered



Module 8 – TEG Dehydration Tower


Configure a distillation column in steady state modePrepare a distillation column for dynamic simulation

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Model Details

• TEG ContactorTEG flow controlColumn pressure control

• TEG Contactor SumpModel as a Separate VesselLevel control


Preparing for Steady State

• Its easiest to model the column in steady state first…

• Hence 2 choices:

• 1. Convert the whole model from dynamics back to steady state- Issues/Concerns:

Steady state and dynamic solvers are different, need to change the dynamic model to prepare it for steady stateNot generally the best idea if working with a very large dynamic model

• 2. Create a new steady state case and build the column there, then copy/paste into dyn model- Issues/Concerns:

Do not need to make any changes to the dynamic model

Page 55



Procedure to Follow

1. Start with a lined out dynamic model2. Add TEG to the component list3. Export the fluid package4. Create a new case using the exported Fluid

Package5. Create a copy of the column feed stream in the

new case• Will have to manually copy the temperature, pressure, flow and

composition

6. Build the column and sump in the new case• Build the column in steady state and then copy?• Build the column in steady state, convert to dynamics and then

copy?

7. Copy the column and sump into the dynamic case


Steady State Model and Dynamic Model

• Steady State ModelTray Sizing Utility defines pressure profile

• Dynamic ModelConvergeWith controls

Page 56



Sizing the Column Tray Section

• In Dynamics, the column pressure profile is calculated by the column hydraulics

• The column requires the following information:DiameterWeir heightWeir lengthTray spacing

• If converting from Steady State to Dynamics it isimportant to make the steady state pressure profile match the dynamic profile

• The Tray Sizing Utility performs the hydraulic calculations on the steady state column


Tray Sizing Utility

Page 57



Modules Covered

1. Getting Started in Steady State2. Pressure Flow Solver and Dynamic Concepts3. Transitioning from Steady State to Dynamics4. Control Theory Review (Reading only)5. Dynamic Details6. Expanding the Model7. Compressor8. TEG Dehydration Tower9. Event Scheduler10.Cause and Effect Matrix11.Building a Fired Heater


Module 9 – Event Scheduler


Use the Event Scheduler ManagerCreate Event SchedulesCreate SequencesCreate Event Conditions

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Event Scheduler

• The Event Scheduler allows UniSim to perform tasks

at a given time or when a given condition occurs

• Suitable for - relief scenarios,- emergency shutdown,- batch processes, etc.


Model Details

• Event SchedulerUse the Event Scheduler:

To ESD Trip: Valve Fail Open the HP liquid outlet valve if the level rises past 90% in the separator,Then after 10 minutes return everything to normal

Page 59



Event Scheduler


Modules Covered


Page 60



Module 10 – Cause and Effect Matrix


Understand the use of the Cause and Effect Matrix


Cause and Effect Matrix

• Combination of Inputs cause Outputs to be triggered- This example duplicates the functionality of the Event Scheduler Module- X = Cause Output to Trip when Input goes to 0- R = Reset Output when Input goes to 1

- 0 = Tripped, 1 = Healthy

- Set Trip, High and Invert options

Page 61



Cause and Effect Matrix


Modules Covered


Page 62



Module 11 – Building a Fired Heater


Work with the Fired Heater unit operation (Dynamics only)


Process Overview - Module 11

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4528.R380.02 Slide Handout for Students

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