Project Synopsis

Operational evaluation of a production area condenser system in a pharmaceutical manufacturing plant to minimize downtime. Simulation Diagram

Project Summary


Process Engineering Associates, LLC (PROCESS) was subcontracted by an engineering firm to perform an operational evaluation of a production area condenser system at a pharmaceutical manufacturing plant.  Specifically, PROCESS was tasked to ascertain causes for, and recommend process improvements to mitigate freezing events in the condenser system that caused significant production delays.  Project tasks included the following:

  • Process evaluation basis preparation
  • Process simulation and mass and energy balance preparation
  • Process improvements recommendations formulation
  • Project report preparation.

The main purpose of the evaluation basis preparation task was to develop detailed physical and chemical characterizations of the process vent streams treated by the condensers.  In addition, detailed engineering information relative to the existing primary and secondary condensers was obtained for the purpose of modeling both existing and modified condensers operation.  Finally, condenser system operating constraints, primarily in the form of system permit requirements, were determined for the purpose of setting limits on modified condensers operation.

Commercially-licensed computer process simulation software was used to develop mass and energy balances for the condenser system.  As part of this task, PROCESS developed an additional in-house computer program designed to calculate overall heat transfer coefficients from individual coefficients using classical heat transfer relationships.  Initial modeling of existing condenser system operation showed significant freezing of water in both the primary and secondary condensers, which matched operational experience.  Then, once again using process simulation as the primary tool, PROCESS was able to develop three options for simultaneously minimizing freezing in the system (as well as for isolating the freezing to the secondary condenser, an operational goal) and maintaining adherence to the permit requirements for operation of the system.  The three options included the following:

  • Increase the low-temperature coolant temperature from –25 oC to 5oC in the primary condenser
  • Add a chilled water condenser upstream of the primary condenser
  • Change the coolant in the primary condenser from low-temperature coolant (-25 oC) to chilled water

Since water is present in the process gas stream to the condenser system, water freezing in the secondary condenser will still eventually occur.  As such, PROCESS recommended adding a redundant secondary condenser that could be used on line while the other condenser is going through a thaw cycle.  PROCESS also recommended two potential process improvements for thawing water from the off-line secondary condenser.

The findings of the project were summarized in a project report submitted to the client.  The client later reported that implementation of PROCESS’ recommendations did in fact virtually eliminate operational downtime due to condenser freezing. The client later contracted with PROCESS to perform a similar evaluation for a similar condensing system in the same plant.

Industry Type

  • Pharmaceutical Manufacturing

Utilized Skills

  • Condenser simulation studies
  • Heat transfer analysis
  • Process troubleshooting

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