CHE 425
Introduction
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MOTIVES FOR NEW PROJECT
• PRIMERLY ECONOMICS (PROFIT
MAXIMIZATION)
• Other motives:
– Strategic
– Compliance
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HOW CHEMICAL PROJECTS ARE
INITIATED?
• I spot a gap in the supply and demand of a
product (or forecast a gap)
• I have feedstock I want to monetize
• I have an existing facility, but I want to
maximize my value chain
• I exploit a new technology
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CHEMICAL PRODUCT TREE
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PRODUCT CYCLES
• Chemical engineers deal with products
• Most products naturally have a life cycle
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PRODUCT TYPES
• Commodity/Bulk Chemicals
• Fine Chemicals
• Specialty/effect/functional chemicals
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PRODUCT TYPES
Copyright - R. Turton and J. Shaeiwitz,
2012
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CHEMICAL PRODUCTS
• Undifferentiated vs differentiated product
Copyright - R. Turton and J. Shaeiwitz,
2012
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IMPLICATION OF PRODUCT TYPE
ON PROCESS DESIGN
• In commodity chemical:
– it is usually important to keep operating costs as
low as possible.
– Focus on process innovation
– Dedicated equipment for specific process
• In specialty chemicals:
– Product innovation
– Multipurpose equipment
Copyright - R. Turton and J. Shaeiwitz,
2012
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DESIGN PROBLEM FORMULATION
• Usually ill-defined
• Higher level examination
• Don’t jump into design,
it is costly
Copyright - R. Turton and J. Shaeiwitz,
2012
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SOME DEFINITIONS
•
•
•
•
•
Process Design
Process Synthesis
Process Analysis
Process Simulation
Process Flowsheet
Copyright - R. Turton and J. Shaeiwitz,
2012
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SOME DEFINITIONS
Process
Synthesis
Process
Analysis
?
?
Copyright - R. Turton and J. Shaeiwitz,
2012
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What is Process Synthesis?
Process
Inputs
(Given)
Process
Structure
& Parameters
(Unknown)
Process
Outputs
(Given)
Process synthesis is concerned with the activities in which the various process
elements are combined and the flowsheet of the system is generated so as to
meet certain objectives. Hence, in process synthesis we know process inputs
and outputs and are required to revise the structure and parameters of the
flowsheet (for retrofitting design of an existing plant) or create a new flowsheet
(for grass-root design of a new plant).
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What is Process Analysis/Simulation
Process
Inputs
(Given)
Process
Structure
& Parameters
(Given)
Process
Outputs
(Unknown)
Analysis is aimed at predicting how the synthesized process will perform. It involves the
decomposition of the process into its constituent elements (e.g. units) for individual study
of performance. Hence, once a process is synthesized, its detailed characteristics (e.g.
flowrates, compositions, temperature, pressure, etc.) are predicted using analysis
techniques. These techniques include mathematical models, empirical correlations and
computer-aided process simulation tools (e.g. ASPEN Plus). In addition, process
analysis may involve the use of experimental means to predict and validate
performance. Therefore, in process simulation, we are given the process inputs and
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flowsheet and are required to predict process outputs.
Process Design =
Process Synthesis + Process Analysis
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SOME DEFINITIONS
• Chemical Process
– Unit operations
– Unit conversions
• Three Scales
– Unit operations scale
– Task scale
– Phenomena scale
Copyright - R. Turton and J. Shaeiwitz,
2012
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SOME DEFINITIONS
• Textbook:
• “This crucial step in the design of the chemical
plant involves all subareas of chemical
engineering: reaction engineering,
thermodynamics, process control, unit
operations, transport phenomena, and
material and energy balances”
Copyright - R. Turton and J. Shaeiwitz,
2012
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Homework
• Homework #1:
– Write a one-page essay on one chemical product of your
choice, elaborating on the following:
– Which category does the product belong to?
– How the product exemplifies the features of its category?
– Where does the product lie in the “chemical product
tree”?
– Line spacing: 1.5
– Font size: 11
Copyright - R. Turton and J. Shaeiwitz,
2012
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