Project Synopsis

Validate the design of a triple-effect evaporator system with a final product stripper column in a sugar processing facility.

Project Summary


The client contacted Process Engineering Associates, LLC (PROCESS) to validate the design of a triple-effect evaporator system with a final product stripper column.  The system had been designed by one of their clients to concentrate sugar solutions containing water and ethanol.  The design information included cursory data regarding the temperature, pressure, and sugar concentration at each evaporator stage, as well as the heat transfer area required at each stage.  PROCESS simulated operation of the system for the purpose of determining the following:

  • Feasibility of the system for obtaining the required product concentration
  • Operating conditions in each stage required to obtain the desired product concentration
  • Adequacy of the heat exchangers (falling film evaporators) for the required duty

Four different cases were simulated to verify operation at various conditions:

  • Case 1 – Stage operating temperatures of 125 oC, 90 oC, 70 oC, and 120 oC for the first, second, and third stages, and stripper column, respectively (the original design condition provided by their client)
  • Case 2 – Operation at 140 oC in the first stage
  • Case 3 – Operation at 105 oC in the first stage
  • Case 2 – Operation at 96 oC in the first stage

PROCESS initially obtained basic data for the system operating temperatures and the product concentration at each stage as it had been designed, as well as basic configuration data for the heat exchangers that the client intended to use.  With this information, PROCESS developed an evaluation basis that governed the process simulation and evaluation tasks.  Missing heat exchanger data was calculated in order to perform a detailed thermal rating.  Licensed commercial computer process simulation software was utilized to characterize system operation as well as to thermally rate the heat exchangers for the required duties.  Each case was simulated with the software for the purpose of first determining case feasibility and then for the purpose of determining system operating conditions.  Operating conditions determined included product concentration; operating pressure and temperature in each stage; heat exchanger size rating; stage recirculation rates; and steam consumption.  Process Flow Diagrams (PFDs) with Heat and Material Balances (HMBs) for each case were prepared to show system operating conditions.

The client initially contacted PROCESS for purposes of validating the system design.  However, based on the results of the first case simulation, the client requested simulation of additional cases.  The results of these cases were used by the client in discussions with the designers of the evaporation system to finalize the system design parameters.  The original design was performed using hand calculations, and the results of the simulation were valuable in validating that design.  In particular, the required operating conditions determined by simulation were found to be different from what the hand calculations showed, and recommendations were made regarding the mechanical design of the heat exchangers to improve operation and service life.

Industry Type

  • Foods Processing

Utilized Skills

  • Feasibility design evaluation
  • Process simulation
  • Heat exchanger design
  • Process design optimization

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