Multivariate Sensitivity
STUDY

What is Multivariate Sensitivity Study?

Multivariate Sensitivity Study calculates the multidimensional solution space (hypercube) of a CHEMCAD flowsheet simulation. The number of input parameters can be increased freely to widen the solution space.

For a fast calculation, Multivariate Sensitivity Studies are calculated on a cluster of CHEMCAD instances.

Why use the Multivariate Sensitivity Study?

Cover a large solution space

Analyze the whole solution space of flowsheets even with convergence problems with brute force to save time.

Find Pareto-Optimal Solutions

Visualize solution spaces for multi-objective optimization problems with pareto optimal points to support decision making.

Apply Constraints with Filters

Discover the correlations of design variables and dependent variables in response to your process and product specifications.

Use Case 1

Optimization of a Batch Distillation for Solvent Recovery

Problem

Solution

Results

Challenges

Objectives

Set-Up of the Multivariate Sensitivity Study

Increase efficiency of Solvent Recovery

  • Minimize energy demand
  • Minimize operation time
  • Maximize product yield
  • Five design variables
  • Equidistant grid (per variable)
  • 78.125 flowsheet runs (mass transfer batch column simulation)
  • Calculation time on 6 machines*: approx. 3 days
  • 74% energy saving
  • 4.5 h reduction in operation time
  • 7% increase in product yield
  • Infeasible design specifications may cause convergence problems
  • Product concentration as a constraint
  • Product specifications must be given indirectly as design specifications due to the accumulated product
  • The correlation of design and state variables are not obvious

Use Case 2

Distillation of an Ethanol-Water Mixture

Problem

Solution

Results

Challenges

Objectives

Set-Up of the Multivariate Sensitivity Study

Understand the correlations between variables

  • Maximize product yield
  • Minimize energy demand
  • Two design variables
  • Equidistant grid (per variable)
  • 9.550 flowsheet runs (SCDS distillation simulation)
  • Calculation time on 7 machines*: approx. 2 hours
  • Use the sliders on the report below to apply limitations
  • Observe the relationship between variables.
  • Check the sensitivities by varying:
    • EtOH fraction
    • Reboiler duty
  • Distillate rate
  • Product concentration as a constraint