Example of PSA drying unit Optimization (using RFS Consulting proprietary algorithm):

 Typical standard PSA unit with two vessels:

  Process operating conditions:

Unit simulation at current operating conditions (table above):

• Approximately 40% of the bed would not be used, considering the fresh sieves properties (At CSS, the water load in the bed at the end of adsorption step is equal to the water load at the end of regeneration within 40% of the bed)

• Ethanol recovery equal to 81%

• Recycle stream: 6.1 t/h at 82w% Ethanol

• Safety Zone considering fresh sieve equal to 58% of the bed (Typical designs suggest 20% safety zone for fresh sieve)

  1st Optimization – Purging flow rate reduction:

• Approximately 20% of the bed would not be used, considering the fresh sieve

• Ethanol recovery equal to 83%

• Recycle stream: 5.5 t/h at 80w% Ethanol

• Safety Zone for fresh sieve equal to 37% of bed

  2nd Optimization – Higher water level at feedstream:

• Approximately 10% of the bed would not be used, considering fresh sieve

• Ethanol Recovery equal to 81%

• Recycle stream: 7.0 t/h at 72w% Ethanol

• Safety Zone for fresh sieve equal to 40% of bed

Estimated savings at up-stream distillation process:

• Rectification Column simulation at 1 atm, assuming 40 ideal equilibrium stages and feedstream fed at central plate

• The Beer column energy duty at reboiler might be reduced due the possibility to feed more water in the rectification column

• Through both optimizations, it could be saved steam/energy at rectification column, mainly for higher water PSA-feedstream scenario, due lower reflux ratio required at rectification column:

33%

Reduction of steam demand at rectification column reboiler

• Capital Expenditure (CapEx) might be reduced for “greenfield” investments, mainly due the lower required reflux at the top of rectification column:

46%

Reduction in required reflux at the rectification column