Distillation sequencing heat integration

Much work has been carried out to find methods for the synthesis of distillation sequences of simple columns that do not involve heat integration. However, heat integration may have a significant... 

Heat Integration of Sequences of Simple Distillation Columns... 

Unless there are constraints severely restricting heat integration, sequencing of simple distillation columns can be carried out in two steps (1) identify the best few nonintegrated sequences and (2) study... 

Stephanopoulos, G., Linnhoff, B., and Sophos, A., Synthesis of Heat Integrated Distillation Sequences, IChemE Symp. Ser., 74 111, 1982. 

The following steps are necessary in establishing a heat integrated distillation sequence... 

Andrecovich, M. J., and Westerberg, A. W., A Simple S3mthesis Method Based on Utility Bounding for Heat-Integrated Distillation Sequences, A/CAE 7, 31(3) 363, 1985. 

Thus, there may be many ways in which the separation can be carried out to produce the same products. The problem is that there may be significant differences in the capital and operating costs between different distillation sequences that can produce the same products. In addition, heat integration may have a significant effect on operating costs. Heat integration of distillation will be considered later in Chapter 21. 

The problem of distillation sequencing was discussed in Chapter 11, where the distillation columns in the sequence were operated on a stand-alone basis using utilities for the reboilers and condensers. Following the approach in Chapter 11, the best few nonintegrated distillation sequences would be found. These sequences would then be heat integrated as discussed above. Figure 21.8 shows how heat integration can be applied within a two-column direct... 

Figure 21.8 Heat integration of a sequence of two simple distillation columns. (From Smith R and Linnhoff B, 1988, Trans IChemE, CHERD, 66 195, reproduced by permission of the Institution of Chemical Engineers.)...

This approach to the overall problem breaks down the design procedure into two steps of first determining the best nonintegrated sequence and then heat integrating. This assumes that the two problems of distillation sequencing... 

All of these arguments demand a more sophisticated approach to the heat integration of distillation sequences, such that the sequence and heat integration (including complex columns) are explored simultaneously. 

Example 21.1 Two distillation columns have been sequenced to be in the direct sequence (see Figure 21.8). Opportunities for heat integration between the two columns are to be explored. The operating pressures of the two columns need to be chosen to allow heat recovery. Data for Column 1 and Column 2 at various pressures are given in Tables 21.1 and 21.2. 

HEAT-INTEGRATED DISTILLATION SEQUENCES BASED ON THE OPTIMIZATION OF A SUPERSTRUCTURE... 

In order to explore distillation sequencing and heat integration simultaneously, a more automated approach to... 

Samanta A (2001) Modelling and Optimisation for Synthesis of Heat-Integrated Distillation Sequences in the Context of Overall Processes, PhD Thesis, UMIST, UK. 

Floudas, C. A. and G. E. Paules. A Mixed-Integer Nonlinear Programming Formulation for the Synthesis of Heat-Integrated Distillation Sequences. Comput Chem Eng 12 531-546 (1988). 

Remark 5 Another application of the logarithmic transformation for convexification is presented in Floudas and Paules (1988) for the synthesis of heat-integrated sharp distillation sequences. 

This chapter presents two applications of MINLP methods in the area of separations. Section 9.1 provides an overall introduction to the synthesis of separation systems. Section 9.2 focuses on sharp heat-integrated distillation sequencing. Section 9.3 presents an application of nonsharp separation synthesis. 

Synthesis of Heat-integrated Sharp Distillation Sequences... 

The significant contribution of the utilities to the total cost of a distillation-based separation sequence provides an incentive to synthesize the sequences of distillation columns which feature heat integration alternatives. 

The basic idea in the synthesis approach of heat-integrated distillation sequences proposed by Floudas and Paules (1988) consists of... 

In postulating a superstructure of alternatives for the heat-integrated distillation sequencing problem, we simultaneously embed ... 

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