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The optimized design of processes is a complex but promising approach in terms of the expected benefits for the efficiency of industrial systems and their operating performance.

It is an area that was the focus of a PhD thesis(1) conducted in partnership with the École polytechnique fédérale de Lausanne (EPFL), based on an example relating to alternative fuels: the production of bioethanol from sugarcane and its leaves, associated with cogeneration. The objective was to reduce the energy consumption of the unit, while maximizing the export of surplus energy(1-2).

The optimization strategy consisted in considering the process as a whole, i.e. simultaneously:
 

  • the sequence of equipment (reactors, exchangers, distillation columns), 
      
  • the network of utilities (steam and electricity),
      
  • and operating conditions (temperatures, pressures, etc.).

In order to implement this strategy, it was necessary to model and simulate the entire process and the production of utilities.

A few figures illustrate the complexity of the problem:
 

  • 28 equipment optimization variables, 
      
  • 50 material flows to be thermally integrated,
      
  • and 75 pieces of equipment.
     

As a multi-objective optimization, it was possible to generate the full range of solutions regarding economic and energy compromise associated with one or several of the “objective” functions defined by the user.

The research demonstrated that it was possible to increase global energy efficiency by 7% and electricity production by 20%(1)while maintaining the same level of ethanol production.

 

Schéma d’un procédé de production d’éthanol et de cogénération de chaleur/électricité.
Diagram showing an ethanol production and heat/electricity cogeneration process.

(1)  R. Bechara, Methodology for the design of optimal processes: application to sugarcane conversion processes, thèse de doctorat, université Lyon 1 (2015)
>> https://tel.archives-ouvertes.fr/tel-01276302/document
    
(2)  
R. Bechara, A. Gomez, V. Saint-Antonin, J-M. Schweitzer, F. Maréchal, Methodology for the optimal design of an integrated sugarcane distillery and cogeneration process for ethanol and power production - Energy 117 (2016). 
>> DOI: 10.1016/j.energy.2016.07.018 

(3) R. Bechara, A. Gomez, V. Saint-Antonin, J-M. Schweitzer, F. Maréchal, Methodology for the design and comparison of optimal production configurations of first and first and second generation ethanol with power, Applied Energy, 2016 
>> DOI: 10.1016/j.apenergy.2016.09.100   

(4) R. Bechara, A. Gomez, V. Saint-Antonin, J-M. Schweitzer, F. Maréchal, Methodology for the optimal design of an integrated first and second generation ethanol production plant combined with power cogeneration, Bioresource Technology, 2016
>> DOI: 10.1016/j.biortech.2016.04.130

 


Scientific contact: adrien.gomez@ifpen.fr

ISSUE 30 OF SCIENCE@IFPEN