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[Gazza.JYMan]

Dear Sir/ Madam,

 

I am a Master student within the United Kingdom, studying the production of Ethylene from a renewable source, Ethanol.

 

Our team have successfully proposed design structure of producing Bio-ethanol via Algal cultivation, however, we have gained difficulty when step foot to the second stage to produce Ethylene, which is on the design procedure to how a reactive distillation calculation and sketch proceed in reactive graphical methods, such as Reactive McCabe-Thiele or Ponchon-Savarit methods. Below are the specific of the project so far, I hope you may spark insight to our issues.

 

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First, the idea of employing reactive distillation was enlighten by BP patent US20080275283 A1. Stating, due to the low conversion of " Ethanol <=> Ethylene + Water" within an equilibrium state, a combination of simultaneous reactive and distillation will yield to achieve a high conversion 99.9%. In our case, this is the conversion we wish to achieve.

 

The McCabe-Thiele or Ponchon-Savarit are possible, you may state the assumption of Constant Molar Over Flow is non valid due to components mole changes as reaction proceed, that is correct, therefore, the operating lines for both the rectifying and stripping section are derived in transformed composition by weight, constant mass flow. They are then calculated as a standard distillation column.

 

- Both graphical method can be referenced to " A graphical method for designing reactive distillation columns I/ II" by J.W. Lee; S. Hauan; K. M. Lien; and A. W. Westerberg.

- Shortcut Method based on distillation lines and tray-by-tray calculation from the use of Ternary Composition diagrams can be referenced to "A short method for the design of reactive distillation column" by M. Carrera-Rodriguez; J. G. Segovia-Hernandez; and A. Bonilla-Petriciolet

- Operating Line derivation can be referenced to " Design and minimum-reflux calculation for single-feed multicomponent reactive distillation columns" by Domingos Barbosa and Michael F. Doherty

 

There are more paper regards to the design of reactive Distillation, however the MAIN problem is, although each paper provides an initial equation and a final distilled composition as well as the tray numbers to the their case study, no specific stream data were given and it became unfeasible for us to follow the method.

 

We kindly ask if you have produced a case study with stream data that may guide us with such calculations?

(or any ideas on both Rectifying/ Stripping plots, and catalyzed tray or counter-current Plug Flow calculations for the Reactive Zone)

 

Stream data and its relevant are provided below:

Flow-rate of Feed, Distillate and Bottoms are set to: 653, 618 and 653 kmol.

Composition mole fraction of Feed (order of Ethanol, Ethylene, Water) are set to: 0.95, 0, 0.05.

Composition mole fraction of Distillation (order of Ethanol, Ethylene, Water) are set to: 0, 0.99, 0.01 [Trace of Ethanol, almost to nil]

Composition mole fraction of Bottom (order of Ethanol, Ethylene, Water) are set to: 0, 0.01, 0.99  [Trace of Ethanol, almost to nil]

Reactor operating Temperature and Pressure are set to: 190 Degree C and 25Bar

 

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We appreciate your read and for any contributions on this topic.

 

Best Regards,

Gareth