winter0809 marlin educational modules

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McMASTERU N I V E R S I T Y

1280 Main Street West, Hamilton, ON, Canada L8S 4L7

Thomas E. MarlinDepartment of Chemical Engineering

And McMaster Advanced Control Consortium

www.macc.mcmaster.ca

Copyright © 2007 by Thomas Marlin

Educational Modules in Process Design andOperability

AIChE Annual Meeting

Session on CACHE CorporationNovember 17, 2008



GOALS OF THE PRESENTATION

• Provide a (not the) definition of operability

- A taxonomy of issues

• Demonstrate that operability is not a collectionof “tricks”

- Improves teaching of fundamentals- Motivates students to learn/apply

• Whet your appetite , refer to WEB site forexpanded coverage

• Introduce project to develop and shareeducational materials

Toolittletime!



FC1

TC1

TC2

T10

T12

T11

T13

fuel

LC1

L2

LAHLAL

F4

To flare

DESIGN IS NOT FOR A SINGLE POINT

BECAUSE OF VARIABILITY AND UNCERTAINTY

Feedcomposition

Temperature

Production rate

Reactionkinetics

Pressure drop

Efficiency

• This is notobvious

• Must be inDesignSpecification



Key Operabilityissues

1. Operatingwindow

2. Flexibility/ controllability

3. Reliability

4. Safety &equipmentprotection

5. Operationduringtransitions

6. DynamicPerformance

7. Efficiency

8. Monitoring &diagnosis

FC1

LC

1

IS THIS PROCESS OPERABLE?

Feed tank

Feed-effluentexchanger

Packed catalyst bed, exothermic reactions

Key Operability Topics

1. Operating window

2. Flexibility/controllability

3. Reliability

4. Safety & equipment protection

5. Operation during transitions

6. Dynamic Performance

7. Efficiency

8. Monitoring & diagnosis




1. Operatingwindow


3. Reliability




7. Efficiency


Key Challenge

How do we enable students to solvecomplex problems with multiple

objectives?

• Provide superstructure for knowledge

• Link to technology basics

• Show compelling, practical examples (within thestudents grasp)

• Provide supporting professional skills

• Encourage (require) students to investigate,discover and evaluate issues in real processes




1. Operatingwindow


3. Reliability




7. Efficiency


FC1

TC1

TC2

T10

T12

T11

T13

fuel

LC1

L2

LAHLAL

F4

To flare

RELIABILITY

* Copyright by CCPS/American Institute of Chemical Engineers and copied with the permission of AIChE

What aspects contribute to reliability?




1. Operatingwindow


3. Reliability




7. Efficiency


RELIABILITY

FC1

TC1

TC2

T10

T12

T11

T13

fuel

LC1

L2

LAHLAL

F4

Parallel pumps

Diversity

By-pass valves

Hot spot




1. Operatingwindow


3. Reliability




7. Efficiency


SAFETY & EQUIP. PROTECTION

ALARMS

Safety Instrumented System

RELIEF

CONTAINMENT

EMERGENCY/COMMUNITY RESPONSE

BPCS

Layers of Safety Protection

• Concentrate

on the firstfour layers

• Stay close to

the process




1. Operatingwindow


3. Reliability




7. Efficiency


FC1

TC1

TC2

T10

T12

T11

T13

fuel

LC1

L2

LAHLAL

F4

To flare



What aspects contribute to safety?




1. Operatingwindow


3. Reliability




7. Efficiency


FC1

TC1

TC2

T10

T12

T11

T13

fuel

LC1

L2

LAHLAL

F4

To flare


Fail closed valve

Alarm

SIS for low flowrate

Safety Relief *


Temperaturecontrol




1. Operatingwindow


3. Reliability




7. Efficiency



HAZOP method provides astructured manner for safetyanalysis (using qualitative analysis)

Note the specific location

Unit: ________Fired heater ____________________

Node:___air pipe after compressor and valve_ Parameter: __Pressure____________________

Guide Word Deviation Cause Consequence Action

Stoppage of power

to motor or turbineturning thecompressor

Uncombusted fuel in

the fire box – dangerof explosion

Uncombusted fuel –wasted fuel

SIS based on the

rotation of motorshaft *

Break of coupling between motor andcompressor

“ SIS based onrotation ofcompressor shaft*

Failure ofcompressor, e.g.,

breakage of blades

“(plus danger from

flying metal)Closure of air valvedue to failure

“ Fail open valve

Any of the above “ SIS that measuresthe flow of air afterthe pipe andactivates theshutdown if the flowif too low

lower

Low pressure in the

fuel pipe node

Closure of air valvedue to poor decision

by operator

“ Air flow controllerwith ratio to fuelflow

fuel

air

feed

product

FC

TC

Principles

Engineering practice




1. Operatingwindow


3. Reliability




7. Efficiency


OPERATION DURING TRANSITIONS

FC1

TC1

TC2

T10

T12

T11

T13

fuel

LC1

L2

LAHLAL

F4

To flare

Heating requiredduring start-up

Disposition of effluentduring start-up

(recycle, flare, storage, …)

Extra sensor withlarge range




1. Operatingwindow


3. Reliability




7. Efficiency


EFFICIENCY & PROFIT

FC1

TC1

TC2

T10

T12

T11

T13

fuel

LC

1

L2

LAHLAL

F4

TC20

TY15

>

Operate at highestconversion without

excess temperature

Minimize heating using fuel,while keeping by-pass open




1. Operatingwindow


3. Reliability




7. Efficiency


MONITORING & DIAGNOSIS

Feed tank

FC

1

P3

V 3 0 0

TC

3

T4

Fueloil

F

2T7

Product

tank

C.W.

F7

Air

Intake

FC

5

ProcessTrouble

Shooting1. Engage

2. Define

3. Explore4. Plan

5. Implement

6. Evaluate

SystematicProblemSolving

Method!

Hy p o th es is In i t i al in fo rm at io n Diag n o s t ic A c t io nT sensor drift Neutral Check with temperature at

exit of reactorFuel valve is stuck open Disprove

(Temperature wouldincrease)

Place flow co ntroller inmanual and make small

change to controller outputFeed rate causing T decrease

(TC too slow)

Disprove

(previous changes werecontrolled)

________________



Highlevel inV-30

Sensorerror

Delta pressure sensor calibrated incorrectly (readinghigher level than actually exists)

Connection point (tap) blocked/corroded (levelmeasurement is constant)

Too muchliquid into thetank

TC-5 poorly tuned (oscillating andcreating too much vapor overhead)

Steam valve fails open (unsafe)

Too little liquidleaving thetank

Poorfeedbackcontrol

Magnitude of feedback controller gain (Kc) is too small

Valvemalfunction

Reflux or product flow valve failed closed (safe)

Pumpmalfunction

Vortex (unlikely with high level)

Caviation

Power loss (motor failure or coupling break)

Increased feed rate (level controller will lowerlevel in time)

Increased propane feed (level controller willlower level in time)

Distillate liquid product valve saturation

Reflux or product flow valve stuck , not respondingto control signal


1. Operatingwindow


3. Reliability




7. Efficiency


FISHBONE DIAGRAM FORMONITORING & DIAGNOSIS



INSTRUCTOR’S EXPERIENCES

• Ammonia reactor and separation loop• Milk powder evaporators and fluid bed

drier• Municipal water purification plant• Desalination plant by reverse osmosis• Ice cream production

• Penicillin production (reactor andseparation)

• Refrigeration and cooling tower plant• Boiler feed water treatment and storage• Kraft pulp digester• Wine production

• Any problem-based teaching style will likely satisfy needs

• Heavy load to develop

• Operability involves generic topics that are applicable toessentially any process (would have to be modified forproduct design). See sample projects from previous years.



STUDENTS’ EXPERIENCES

The Ugly To much (open-ended) work!

The Good• Students enjoyed the problem solving tasks

(e.g., HAZOP and Trouble Shooting)• Defined diverse projects & found good operability issues

The Bad• Difficulty recognizing causes of variability and

uncertainty

• Challenge to “work backwards”: effect cause



Educational Modules in Process Design andOperability

• Integrate Robust design/process operability in thecapstone design course

• No instructor has experience with all issues

• Limited educational material is available that is accessible to

undergraduates

Project to establish a portal

for robust design/ processoperability , witheducational materials for

public use



Educational Modules in Process Designand Operability


1. Operatingwindow


3. Reliability




7. Efficiency


For each topic

• A Chapter in pdf format

• Class materials (powerpoint, tutorials)

• Cogent process examples for undergraduates

• Links to resources for problem solving

To integrate materials

• An introductory chapter

• Several process examples



T h a n k s f o r y o u r

a t t e n t i o n

We would appreciate comments, criticism,suggestions at any time, now or by email.


1. Operatingwindow


3. Reliability




7. Efficiency


Educational Modules in Process Designand Operability

Expanded copy of white paper and power point lessons are available at

www.pc-education.mcmaster.ca/operability_home.html

winter0809 marlin educational modules

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