KKA 3306 PROCESS AND PLANT DESIGN Lecture 3

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KKA 3306 - PROCESS AND PLANT DESIGN Lecture 3

• By
• Robiah yunus
• Faculty of engineering
• Universiti putra malaysia
• Serdang,43400 selangor.

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PRELIMINARY PROCESS DESIGNOverview

• A synthesis activity
• Convert an abstract description of a process into
  a more refined description
• discover better process configurations for the
  stated design goals
• Generates alternatives and carry out performance
  analyses
• only 15-20 of the total costs
• Fix 80 of the subsequent costs
• grassroots or retrofit design

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PRELIMINARY PROCESS DESIGNBasic Steps

• Objectives
• to discover good alternatives without exhaustive
  search
• to evaluate better alternatives based on stated
  criteria
• Steps
• Gathering Information
• Representing Alternatives
• Criteria for Assessing Preliminary Designs
• Generating and Searching Among Alternatives

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PRELIMINARY PROCESS DESIGN Gathering Information

• Objectives
• to uncover existing process alternatives
• Sources of Information
• Kirk-Othmer Encyclopedia of Technology
• Chemical Process Industries by Shreve and Brink
• Chemical Abstracts, ACS and Engineering Index,EI
• Journals
• Chemical Engineering Progress
• Chemical Engineering
• Hydrocarbon Processing , etc
• Webb sites www.company-name.com

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PRELIMINARY PROCESS DESIGN Representing
Alternatives

• Objectives
• to represent alternatives in a concise way for
  decision making purposes
• Representation schemes depends on ways to
  generate and search among alternatives
• Representation schemes
• Flowsheet or aggregation of equipment
• Tasks i.e. heating, reaction, separation
• Specialized representations
• Heat exchange between process, Q vs. T
• Composition space

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PRELIMINARY PROCESS DESIGN Representing
Alternatives

• Flowsheet or aggregation of equipment

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PRELIMINARY PROCESS DESIGN Representing
Alternatives

• Representing Processes Using Tasks

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PRELIMINARY PROCESS DESIGN Representing
Alternatives

• Specialized Representations

T
T vs. Q
Heat Flow, kW
water
reaction
separation
Ethanol
Ethylene
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PRELIMINARY PROCESS DESIGN Criteria for
Assessing Preliminary Designs

• Objectives
• to decide on measures to use to assess
  performance of design alternatives
• Basic criteria
• Economic evaluation
• Environmental Concerns
• Safety Analysis
• Flexibility
• Controllability

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PRELIMINARY PROCESS DESIGN Criteria for
Assessing Preliminary Designs

• Economic evaluation
• to establish the cost of equipment and utilities
• based on the the completed mass and energy
  balances
• based on the the preliminary equipment sizing
• criteria for assessing the worth of project as
  compared to competing projects

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PRELIMINARY PROCESS DESIGN Criteria for
Assessing Preliminary Designs

• Environmental Concerns
• satisfying government regulations from agencies
  such s DOE
• air pollution
• waste water
• landfill
• handling of hazardous chemicals

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PRELIMINARY PROCESS DESIGN Criteria for
Assessing Preliminary Designs

• Safety Analysis
• to determine whether any treasonable combination
  of events may lead to unsafe situations
• fires
• explosions
• release of toxic chemicals
• HAZOP - A study to determine and reduce potential
  hazards
• look at every part of process and ask what would
  happen if it fails and provide solution.

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PRELIMINARY PROCESS DESIGN Criteria for
Assessing Preliminary Designs

• Flexibility
• The process must be able to handle variations in
• raw materials/feed
• temperature of cooling water due to different
  seasons
• heat transfer coefficients of heat exchangers
• Flexible processes are costly
• Precise definition and analyses of flexibility
  are necessary for optimal operability

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PRELIMINARY PROCESS DESIGN Criteria for
Assessing Preliminary Designs

• Controllability
• to determine the ability to operate the process
  satisfactorily while undergoing dynamic changes
  from one operating condition to another
• to assess the ability to recover from unknown
  disturbances