Project Synopsis

Troubleshoot beer columns at an operating ethanol plant and identify design and/or operational changes to improve the operation.

Project Summary


The client operates a large commercial corn ethanol plant in the U.S. that produces fuel ethanol for blending with gasoline.  The plant had not be able to achieve the design production rates since start-up.  The client identified the distillation area as a major contributor to the production bottleneck.  Process Engineering Associates, LLC (PROCESS) was contracted to execute an Alternatives Study to identify process modifications that might restore production to design rates.

The distillation area of the plant includes two beer columns and one high-pressure rectification column.  The three-column arrangement and energy integration is based on a licensed process design technology.  The beer feed from the Fermentation Tanks is split between two Beer Columns (Beer Column 1 and Beer Column 2) operating in parallel with respect to the feed.  The Rectifier Column is heated by steam and the overhead from the rectifier is directed to the Beer Column 1 Reboiler which serves as a condenser for the Rectifier Column.  The Beer Column 1 overhead heats the Beer Column 2 Reboiler.  Both Beer Columns operate under vacuum.  The condensate from the Beer Column overheads is collected and fed to the Rectifier.  Ethanol product is removed as a vapor portion of the Rectifier overheads and routed to the Mol Sieves for final purification.

The client was experiencing various operational issues with the distillation process that affected production.  These include solids carryover causing fouling of overhead equipment, low heat transfer rates in reboilers, inability to maintain Beer Column vacuum, and tray fouling in all columns.  PROCESS visited the facility to review the operation and subsequently developed alternatives to address the issues.  As a part of this investigation, PROCESS also updated the facility’s distillation Heat and Mass Balance (HMB) and used licensed commercial computer process simulation software (CHEMCAD) to produce HMB cases that represented current operation and debottlenecked cases representing 110% and 125% of current operation.

PROCESS recommended increasing the size of the feed nozzle to Beer Column 2 and extending the height of the column to reduce carryover and subsequent fouling.  A new overhead condenser was recommended to improve condensing capacity and vacuum levels.  Larger piping from the Beer Column 2 Reboiler shell side (Beer Column 1 overhead) was recommended to reduce the back pressure at the top of Beer Column 1.

PROCESS submitted a report with the recommendations and a preliminary cost estimate.

Industry Type

  • Alternatives Fuels Production

Utilized Skills

  • Process troubleshooting
  • Distillation design

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