PROCESS OPERABILITY

1
CHEMICAL ENGINEERING 4N04
PROCESS OPERABILITY Ensuring that the plant has
the capacity and flexibility to achieve a range
of operating conditions safely, reliably,
profitably and with good dynamic performance.
We already know engineering principles - now,
lets apply them and learn more about practice!
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PROCESS OPERABILITY Ensuring that the plant has
the capacity and flexibility to achieve a range
of operating conditions safely, reliably,
profitably and with good dynamic performance.

• Topic includes nine lessons and one workshop,
  each in a separate PowerPoint file
• What will we learn in this lesson?
• - How to define a design problem to yield an
  operable plant.
• - What are eight key operability issues
• Subsequent lessons cover each issues in some
  detail

3
From the simplest to most complex process, we
must think about operability!
I need to regulate the flow, but how complex
should the equipment be? Does the need for
operability affect this decision?
4
A PROCESS DESIGN PROCEDURE

• Set goals and design specifications
• Select process technology
• Define process structure (sequence)
• Simulate the flowsheet
• Design equipment
• Construct and start up

Operate the plant over a range of conditions,
many operating points and transitions between them
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PROCESS DESIGN WITH OPERABILITY
The design procedure should ensure that the plant
is operable, that it functions well. This
requires a specification that addresses a range
of conditions, for example

• Feed compositions and rates
• Product qualities
• Equipment capacities, which change
• Equipment availabilities including maintenance
• Environment (e.g., summer, winter)
• Major disturbances

6
CLASS WORKSHOP
What do the following words have in common?
Music
Love
Operability
Happiness
7
CLASS WORKSHOP
Difficult to define exactly, but we know when we
have achieved or fallen short!!
Music
Love
Operability
Happiness
8
OPERABILITY ENSURES THAT THE PLANT PERFORMS WELL
9
OPERABILITY WHEN DO WE INFLUENCE IN THE DESIGN
PROCEDURE?

• Design Procedure
• Set goals and design specifications
• Select process technology
• Define process structure (sequence)
• Simulate the flowsheet
• Design equipment

The flowsheet typically involves basic ME
balances, equilibrium and rate processes. It
does not consider practical issues for achieving
the operation.
Equipment design achieves the base case flowsheet
(plus other concerns). This sets the capacity
of the plant.
10
OPERABILITY WHEN DO WE INTRODUCE IT IN THE
DESIGN PROCEDURE?

• Design Procedure
• Set goals and design specifications
• Select process technology
• Define process structure (sequence)
• Simulate the flowsheet
• Design equipment

We must define the range of operations and goals
to achieve before we begin the design! Design
limited to the base case is not likely to be
satisfactory.
The flowsheet typically involves basic ME
balances, equilibrium and rate processes. It
does not consider practical issues for achieving
the operation.
Equipment design achieves the base case flowsheet
(plus other concerns). This sets the capacity
of the plant.
11
Operability Class Workshop Identify key aspects
of a design specifications that could change and
whose ranges must be defined.
reactors
compression
refrigeration
separation
products
feeds
12
Operability Class Workshop Identify key aspects
of a design specifications that could change and
whose ranges must be defined.
Some examples are given below (the lists are not
comprehensive)

• Feeds
• compositions
• rates
• prices
• contracts (must use?)
• impurities
• crude oil - salt
• fuels - sulfur
• polymer - acetylenes

Products composition specifications rates prices,
f(x, flow)? contracts (must satisfy?)
Effluents rates allowed compositions
allowed limits penalties
Energy utilities fuels steam electricity hydrog
en oxygen

• Environment
• ambient temperature
• cooling water
• air compressor
• steam tracing
• disturbances
• rain storms

Integrated Units supply of material supply of
energy destination for material destination for
energy
13
We have to known where we are going before we can
design!

• Design Procedure
• Set goals and design specifications
• Select process technology
• Define process structure (sequence)
• Simulate the flowsheet
• Design equipment

The design must define the range of operations to
be achieved. We can accept less than full
production rate or top efficiency for extreme
situations.
The flowsheet typically involves basic ME
balances, equilibrium and rate processes. It
does not consider practical issues for achieving
the operation.
Equipment design achieves the base case flowsheet
(plus other concerns). This sets the capacity
of the plant.
14
OPERABILITY WHEN DO WE INTRODUCE IT IN THE
DESIGN PROCEDURE?

• Design Procedure
• Set goals and design specifications
• Select process technology
• Define process structure (sequence)
• Simulate the flowsheet
• Design equipment

This might influence the range of operations! For
example, a fluidized bed reactor could have a
smaller range of flow than a packed bed.
The flowsheet typically involves basic ME
balances, equilibrium and rate processes. It
does not consider practical issues for achieving
the operation.
Equipment design achieves the base case flowsheet
(plus other concerns). This sets the capacity
of the plant.
15
OPERABILITY WHEN DO WE INTRODUCE IT IN THE
DESIGN PROCEDURE?

• Design Procedure
• Set goals and design specifications
• Select process technology
• Define process structure (sequence)
• Simulate the flowsheet
• Design equipment

This might influence the range of operations! For
example, the addition of a recycle stream might
allow a wider range.
The flowsheet typically involves basic ME
balances, equilibrium and rate processes. It
does not consider practical issues for achieving
the operation.
Equipment design achieves the base case flowsheet
(plus other concerns). This sets the capacity
of the plant.
16
OPERABILITY WHEN DO WE INTRODUCE IT IN THE
DESIGN PROCEDURE?

• Design Procedure
• Set goals and design specifications
• Select process technology
• Define process structure (sequence)
• Simulate the flowsheet
• Design equipment

Some of the flowsheet variables, such a
distillation feed location and reactor volume,
influence the achievable range of operations.
The flowsheet typically involves basic ME
balances, equilibrium and rate processes. It
does not consider practical issues for achieving
the operation.
Equipment design achieves the base case flowsheet
(plus other concerns). This sets the capacity
of the plant.
17
OPERABILITY WHEN DO WE INTRODUCE IT IN THE
DESIGN PROCEDURE?

• Design Procedure
• Set goals and design specifications
• Select process technology
• Define process structure (sequence)
• Simulate the flowsheet
• Design equipment

The flowsheet typically involves basic ME
balances, equilibrium and rate processes. It
does not consider practical issues for achieving
the operation.
Equipment design has a very strong influence on
the range of plant operation. Again, satisfying
the base case is not sufficient.
Equipment design achieves the base case flowsheet
(plus other concerns). This sets the capacity
of the plant.
18
OPERABILITY WHEN DO WE INTRODUCE IT IN THE
DESIGN PROCEDURE?

• The principle sins associated with flowsheets
  used for economic evaluation are sins of
  omission. . Other frequently omitted items
  include
• Storage tanks
• Surge tanks
• Duplicated equipment (for reliability)
• Start-up equipment
• Emergency safety equipment
• .

Valle-Riestra, J.F.(Dow Chemical Co.), Project
Evaluation in the Process Industries,
McGraw-Hill, New York, 1983 (pg 169)
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Key Operability issues 1. Operating window 2.
Flexibility/ controllability 3.
Reliability 4. Safety equipment protection 5.
Efficiency profitability 6. Operation during
transients 7. Dynamic Performance 8. Monitoring
diagnosis
OPERABILITY INVOLVES MANY ISSUES What Will We Do
In The Course?

• We will learn
• Some of the most common operability issues
• Understand typical designs
• through many class
• workshops
• Identify resources for further study and
  application
• Future 4W04 and engineering practice

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Key Operability issues 1. Operating window 2.
Flexibility/ controllability 3.
Reliability 4. Safety equipment protection 5.
Efficiency profitability 6. Operation during
transients 7. Dynamic Performance 8. Monitoring
diagnosis
OPERABILITY INVOLVES MANY ISSUES What Will We Do
In The Course?
The design procedure involves balancing many
objectives, including the eight operability
issues. Sometimes, we call this multi-objective
design or multi-disciplinary design. One way to
combine disparate objectives is through
economics, but objectives like safety and product
delivery and quality must be satisfied,
regardless of cost. (If they cannot in a
profitable manner, we do not proceed with the
project.)
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Key Operability issues 1. Operating window 2.
Flexibility/ controllability 3.
Reliability 4. Safety equipment protection 5.
Efficiency profitability 6. Operation during
transients 7. Dynamic Performance 8. Monitoring
diagnosis
OPERABILITY INVOLVES MANY ISSUES Why is
Operability in a required course?

• We will learn how to learn about a process. This
  is a general skill that
• Requires all prior knowledge (courses)
• - Great opportunity to reinforce and apply
• Can be applied to essentially any process

Plant operations
Plant design
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Key Operability issues 1. Operating window 2.
Flexibility/ controllability 3.
Reliability 4. Safety equipment protection 5.
Efficiency profitability 6. Operation during
transients 7. Dynamic Performance 8. Monitoring
diagnosis
OPERABILITY INVOLVES MANY ISSUES Can be applied
to essentially any process?
Sample of some projects completed by recent 4N04
Groups

• Milk power plant
• Ammonia plant
• Boiler water treating
• Refrigeration equipment
• Pump selection
• Heat exchanger selection
• Penicillin plant

• Waste water treating
• Desalinization rev. osmosis
• Distillation
• Valves
• Wine making (industrial)
• Water treating

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Key Operability issues 1. Operating window 2.
Flexibility/ controllability 3.
Reliability 4. Safety equipment protection 5.
Efficiency profitability 6. Operation during
transients 7. Dynamic Performance 8. Monitoring
diagnosis
OPERABILITY INVOLVES MANY ISSUES What are the
Topic Learning Goals?