Energy-integrated distillation

Reboiler section 1 Column H Comp. Condenser section condenser 

The economics of VRD favors separations involving components with similar boiling points (e.g., the separation of propane and propylene in an oil refinery, in a column that is typically referred to as a C3 splitter ) so that the temperatures of the top and bottom streams of the distillation column are close. This reduces the power consumption of the compressor as well as the duty (and associated heat-transfer area) of the trim condenser. Given the above, we can make the following observations and assumptions concerning the various steady-state energy flows in the process. 

This observation also implies that the internal energy flows (iff s, Hv s, and ffCjS) are comparable in magnitude to iftr,s- 

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O. Annakou, A. Meszaros, Z. Fonyo, and P. Mizsey. Operability investigation of energy integrated distillation schemes. Hung. J. Ind. Chem., 24 155-160, 1996. 

O. Armakou and P. Mizsey. Rigorous comparative study of energy - integrated distillation schemes. Ind. Eng. Chem. Res., 35 1877-1885, 1996. 

P. Mizsey and Z. Fonyo. Energy integrated distillation system design enhanced by heat pumping distillation and absorption. Inst. Chem,. Eng., pages B69-B75, 1992. 

Mizsey, P., Hau, N.T., Benko, N., Kalmar, I. and Fonyo, Z. 1998, Process control for energy integrated distillation schemes. Comp chem Eng, 22, S427. 

I. Meszarus and Z. Fonyo. A new bounding strategy for synthesizing distillation schemes with energy integration. Comp. Chem. Eng., 10 545,1986. 

R. N.S. Rathore, K.A. Van Wormer, and G.J. Powers. Synthesis of distillation systems with energy integration. AIChE J., 20(5) 940,1974b. 

Nakaiwa M et al. Potential energy saving in an ideal heat-integrated distillation column. Appl Thermal Eng 1998 18 1077-1087. 

Faith, D.C. and Morari, M., "Synthesis of Distillation Schemes with Energy Integration," CACE 79, Montreux, Switzerland, April 8-11, 1979. 

While these techniques have been applied to energy-related processes such as heat-integrated distillation columns and fluid catalytic cracking reactors, there is still extensive research required before the concept of plant design/control is reduced to practice. 

In conclusion, compared with the previous design the flowsheet based on reactive distillation appears to be more economical as hardware and more efficient from an energy-integration viewpoint. However, the premise of feasibility is the availability of a catalyst with superior properties in terms of activity and selectivity compared with those used in a liquid-phase reactor. 

The goal of this book is to help chemical engineering students and practicing engineers develop effective control structures for chemical and petroleum plants. Our focus is on the entire plant, not just the individual unit operations. An apparently appropriate control scheme for a single reactor or distillation column may actually lead to an inoperable plant when that reactor or column is connected to other unit operations in a process with recycle streams and energy integration. 

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