Perancangan Proses Teknik
Kimia
Kuliah 3 – Introduction to Process Design (Part 2)
Semester Genap 2021/2022
Program Sarjana Teknik Kimia (Kelas A)
Universitas Riau
PROCESS DESIGN TASK
Flowsheet Mass Balances
• Mass balances using approximate models are often carried
out by using paper and pencil, spreadsheets, and even process
simulators.
• For a promising base-case flowsheet, block and initial
process flow diagrams are often prepared, along with
preliminary material balances.
• Subsequently, mass balances are prepared using a process
simulator.
Process Stream Conditions
• During preliminary process synthesis, initial stream
conditions are specified, for example, temperatures and
pressures, often at the bubble or dew points, or at specified
vapor or liquid fractions.
• The latter are computed assuming phase equilibrium, often by
a process simulator.
Flowsheet Material and Energy Balances
• Simple energy balances are also carried out during
preliminary process synthesis, often using a process
simulator.
• Energy balances require estimates of the thermophysical
properties (e.g., heat capacities, latent heats, internal energies,
and enthalpies).
• For base-case designs, strategies for carrying out material and
energy balances for entire flowsheets are
• These are especially important for multicomponent recycle
streams.
Equipment Sizing and Costing
• Estimating key equipment sizes and costs.
• Often these are estimated initially using approximate models
by the process simulators.
• Subsequently, more accurate models are inserted.
• Models to calculate the heat to be added or removed from a
stream are replaced by models for shell-and-tube heat
exchangers.
Economic Evaluation
• In some cases, just the total permanent investment is
estimated, often approximately when comparing flowsheets
during process synthesis.
• For promising base-case designs, more accurate calculations
are carried out.
• The approximate and rigorous cost and profitability analysis
methods.
Heat and Mass Integration
• Heat and mass integrations are important to achieve
profitable chemical processes.
Environment, Sustainability, and Safety
• Issues of environmental impact, sustainability, and process
safety are considered carefully by most process design teams.
Controllability Assessment
• It is important to check that the final flowsheet can be
maintained at its desired operating conditions.
• There may be insufficient degrees of freedom to enable this
to be carried out, and controllability assessment will uncover
such deficiencies.
• Short-cut controllability assessment methods and introduces a
conceptual plant-wide control system configuration
methodology.
Optimization
• At the process synthesis, process design teams seek to select
the best choices, often using optimizers within the process
simulators.
• Optimization strategies often used in process design, with
emphasis on steady-state operation of large-scale continuous
processes.
• The optimal design and scheduling of batch processes.
PRELIMINARY FLOWSHEET
MASSBALANCES
• Materials balance results are normally displayed with process
flow diagrams.
• Three kinds of flow diagrams are normally prepared to
describe the base-case design(s):
• the block flow diagram,
• the process flow diagram, and
• the piping and instrumentation diagram (P&ID).
Block Flow Diagram (BFD)
• The block flow diagram represents the main processing
sections in terms of functional blocks.
• The diagram also indicates the overall material balances and
the conditions at each stage, where appropriate.
• This level of detail is helpful to summarize the principal
processing sections and is appropriate in the early design
stages, where alternative processes are usually under
consideration.
Block Flow Diagram (BFD)
Process Flow Diagram (PFD)
• Process flow diagrams provide a more detailed view of the
process.
• These diagrams display all of the major processing units in
the process (including heat exchangers, pumps, and
compressors), provide stream information, and include the
main control loops that enable the process to be regulated
under normal operating conditions.
Process Flow Diagram (PFD)
• Often, preliminary PFDs are constructed using the process
simulators
• Subsequently, more detailed PFDs are prepared using
software such as AUTOCAD and VISIO.
• The conventions typically used when preparing PFDs.
Process Flow Diagram (PFD)
