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APC - Pygas

The Pygas advanced control package combines Axens Horizon' latest generation multivariable controller MVAC with on line reactor models, in association with inferentials; it is designed to maximize the benefits from Pygas process at the lowest operating cost. As process licensor, catalyst manufacturer and advanced control technology supplier, Axens Horizon combines all the necessary expertise for successful Pygas APC projects.

An eight step control strategy is implemented

  • Precise control of product specifications
  • adjustment of hydrogen make-up for optimal H2/HC ratio (last reactor)
  • control of reactor bed temperature profiles (both reactors)
  • control of reactor LHSV (both reactors)
  • control of catalyst deactivation
  • depentanizer fractionation control
  • deoctanizer fractionation control
  • compensation of the effects of feed flow variations

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On-line reactor model

Assuming on-line styrene analyzer is available for effluent of first reactor, the Pygas control package uses Axens Horizon' SHU reactor models to estimate on-line diene value (MAV), bromine index, catalyst activity and styrene.


  • catalyst run length maximization
  • ability to absorb more feed flow:
  • no limitation for the upstream plant (ethylene,¡K)
  • product on specification at all times
  • reduction of hydrogen make up
  • reduction of benzene losses in the C5 cut
  • safe and proper operation of the unit
  • minimization of energy consumption

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Documentation Center

APC - Pygas Hydrogenation - Commercial Bulletin cadenas