13241477
Description
Mind Map by Diana Kathlene Matibag Dimaano, updated more than 1 year ago
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Created by Diana Kathlene Matibag Dimaano
over 6 years ago
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Process Flowsheeting
- Mass
Balance
- The Phase Rule
- DOF = n - π + 2
- Specify variables
- Simulation problem
- feed stream and unit
parameters
- feed stream and unit
parameters
- Design problems
- Other
specifications
- Other
specifications
- Simulation problem
- Specify variables
- DOF = n - π + 2
- Calculation Procedure
- Sequential Modular
- uses matrix representation to solve the
flowsheet by solving each set of equations for
each unit in order of which they appear in the
flowsheet.
- 1. Guess values for stream 4
- 2. Using these values, solve for streams 2, 3, 5 and new set of
values for stream 4
- 3. Modify the guessed values for stream 4
- 4. Redo the flowsheet calculations until calculated values are
equal to the guessed values for stream 4
- 5. When the two values are essentially the same, the procedure is
said to have converged
- What is essentially equal? When comparing the guessed value and calculated value for stream 4, a
‘tolerance’ or ‘ԑ’ value may be set as an acceptable accuracy (10-3 , 10-7 etc.)
- What is essentially equal? When comparing the guessed value and calculated value for stream 4, a
‘tolerance’ or ‘ԑ’ value may be set as an acceptable accuracy (10-3 , 10-7 etc.)
- Successive substitution
- ADV: simple, easy to implement
DIS: may diverge (unlikely), very
slow rate of convergence
- ADV: simple, easy to implement
DIS: may diverge (unlikely), very
slow rate of convergence
- Convergence acceleration techniques
- ADV: faster convergence
DIS: possible divergence,
more complex
implementation
- ADV: faster convergence
DIS: possible divergence,
more complex
implementation
- 5. When the two values are essentially the same, the procedure is
said to have converged
- 4. Redo the flowsheet calculations until calculated values are
equal to the guessed values for stream 4
- 3. Modify the guessed values for stream 4
- 2. Using these values, solve for streams 2, 3, 5 and new set of
values for stream 4
- uses matrix representation to solve the
flowsheet by solving each set of equations for
each unit in order of which they appear in the
flowsheet.
- Equation
Oriented
- uses matrix representation of material and
energy balance problems to solve the flowsheet.
It solves the equations simultaneously.
- occurrence matrix
- When the matrix is square, the degree of freedom
is zero – this means the number of equations is
equal to the number of variables, hence a solution
can be sought.
- Jacobian matrix (refer to slides on equation solving methods) to find a solution.
- When the matrix is square, the degree of freedom
is zero – this means the number of equations is
equal to the number of variables, hence a solution
can be sought.
- uses matrix representation of material and
energy balance problems to solve the flowsheet.
It solves the equations simultaneously.
- Sequential Modular
- The Phase Rule
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