Synthesis And Design Of A Simplified Ideal Heat-Integrated Distillation Column (Ideal Hidic)

Although the ideal heat-integrated distillation column (ideal HIDiC) is much more thermodynamically efficient than its conventional analogues, its applications in the chemical and petrochemical process industries have been restrained. The reason can be attributed to the great difficulties and complexities in the design and implementation of internal heat integration between the rectifying section and the stripping section because all the attempts arrange internal heat transfer within the column shell so far. For the avoidance of these difficulties, a breakthrough in process synthesis and design must be made in these aspects.In this dissertation, internal heat integration between the rectifying section and the stripping section is suggested to move to the outside of the column shell, and this leads to the creation of a novel simplified configuration for the ideal HIDiC, termed the SIHIDiC. Only are three or even fewer internal heat exchangers used to approximate the internal heat integration. The top internal heat exchanger is arranged between the tops of the rectifying section and the stripping section respectively, enabling the SIHIDiC to operate in a reflux-free operation mode. The bottom internal heat exchanger is fixed between the bottom of the rectifying section and the stripping section respectively, enabling the SIHIDiC to operate in a reboil-free operation mode. The intermediate internal heat exchanger is located between the middles of the rectifying section and the stripping section respectively, generating secondary or additional reflux flow for the rectifying section and vapor flow for the stripping section. The locations and sizes of the three heat exchangers are key decision variables for process synthesis and design and should be considered to enhance thermodynamic efficiency in process development.A simple stepwise procedure is thus derived for process synthesis and design and the SIHIDiC is evaluated through intensive comparison with the conventional distillation column and the ideal HIDiC in terms of the separations of an ethylene/ethane and benzene/toluene binary mixtures. The results obtained indicate that the SIHIDiC could be an excellent candidate to approximate the ideal HIDiC with somewhat similar (if not smaller) capital investment and operating cost and it can implement in the chemical and petrochemical process industries.