sim21

Open source simulator for typical process/chemical/refinery engineering applications with rigorous thermodynamics. Revival of legacy Sim42 simulator for Python 3 with custom thermodynamics.

• Learn more about legacy Sim42 https://web.archive.org/web/20050204025650/http://manual.sim42.org/
• Free software: MIT license
• Documentation: https://sim21.readthedocs.io.

Under continual development, breaking changes are to be expected.

Status

• Nov 11, 2021

  • Not dead yet - Just busy with other things
  • Code requires a significant rewrite
    • Most of the current code moved to a separate 'old' package.
    • All tests still pass

• Feb 2, 2021

  • Implemented Activity Coefficient Models: NRTL, Wilson with some sample interations

• Jan 23, 2021

  • Finished implementation of a seperate steam/water Thermo using IFC-97
  • Included example of a very simple steam cycle flowsheet

• Jan 21, 2021

  • Signficant speed ups in the distillation simulation, now quite fast
  • Other smaller speed-ups
  • Runtime is about 2-3x faster over all examples

• Jan 20, 2021

  • All example cases now converge with some massaging
  • Fixed a nasty bug that was preventing one phase results in Flash unitops

• Jan 12, 2021

  • Many more test cases working including PipeSegment
  • All column examples now work with different types of specs including recoveries, deg. of subcooling, etc.

Highlights

• Independent steam model with high accuracy IFC-97 Steam model

  • Sample steam cycle included in flowsheet examples

• Many examples with output now available with PR/SRK EOS Thermo:

  • Air Separation Unit (ASU)
  • Natural Gas Separation Train
  • Refrigeration Loops
  • Nitrogen Rejection
  • Compressors/Expanders with given efficiencies and performance curves
  • Many examples of wide and narrow boiling distillation/absorption/stripping (DeC1, DeC2, DeC3s)
  • Towers with pumparounds/efficiencies
  • Superfractionator example with C3= Splitter
  • Ejector
  • Heat Exchangers with multiple sides (Coldboxes)
  • Basic Controllers

• Cubic EOS Thermodynamics provider is largely complete

  • Additional examples found where the PH-solver fails dramatically - Needs improvement.
  • Implement Newton based solver to speed up flashes
  • No support for critical properties/phase envelopes yet

• Tower/Distillation Column model is fully functional (Supporting Pumparounds, Bypass, Efficiencies and Side-Strippers)

TODO

• Support component addition/deletion on the fly
• Cleanup command line interface
• Provide Python based alternate interface to run simulator to integrate better with Python ecosystem
• Revamp web/HTML interface to use for models

Features

• Updated for Python 3.x and removed major incompatibilities
• Removed obsolete references and updated to use modern replacements (numpy, scipy)
• Thermodynamics:
  • Equation of State (EOS)
    • Peng-Robinson (PR) /Soave-Redlich-Kwong (RK)
  • IAPWS97 implementation based on https://github.com/KurtJacobson/XSteam
  • Two-phase flashes for common specifications using inside-out method
• Builtin database of 400+ common components using ChemSep: http://www.chemsep.com/ database

Next Steps

• Fully implement basic thermodynamic provider with component database
• Massive code cleanup (Use snake_case instead of CamelCase, Exception Handling)