Process synthesis configurations

The result of process synthesis is a flowsheet which represents the configuration of the various pieces of equipment and their interconnection. Next, it is necessary to analyze the performance of this flowsheet. 

Process synthesis is a task of formulating the process configuration for a purpose by defining which operations or equipment are used and how they are connected together. There are two basic approaches for process synthesis 1) classical process synthesis, analysis and evaluation, and 2) optimization of process structure by using a suitable objective function. 

Process synthesis and design of these non-conventional distillation processes proceed in two steps. The first step—process synthesis—is the selection of one or more candidate entrainers along with the computation of thermodynamic properties like residue curve maps that help assess many column features such as the adequate column configuration and the corresponding product cuts sequence. The second step—process design—involves the search for optimal values of batch distillation parameters such as the entrainer amount, reflux ratio, boiler duty and number of stages. The complexity of the second step depends on the solutions obtained at the previous level, because efficiency in azeotropic and extractive distillation is largely determined by the mixture thermodynamic properties that are closely linked to the nature of the entrainer. Hence, we have established a complete set of rules for the selection of feasible entrainers for the separation of non ideal mixtures... 

Douglas (1977, 1979) has been pursuing a quite different approach to process synthesis. He has been developing techniques which permit the designer to analyze and optimize alternative configurations quickly and by hand. His "synthesis" strategy is to teach people to recognize valid approximations for the problem at hand it has proved a rather controversial exercise since people... 

Therefore, in the first place the process synthesis should solve a structural problem, the configuration of the optimal reactor system. Then detailed design and refinement can follow. If there are several candidates close to optimum, these could be assembled in a superstructure and submitted to structural optimisation. 

Starting with the given thermophysical and kinetic data, a heuristic-numeric process synthesis has been carried out. This procedure led to the specific column configuration displayed in Fig. 10.18 for the production of DEC. 

As discussed earlier, preliminary process synthesis occurs after an alternative processing concept has been created. Having defined the concept and assembled the preliminary database, usually with some experimentation, the design team sets out to synthesize a flowsheet of process operations to convert the raw materials to the desired products. First, it decides on the state of the raw materials, products, and byproducts, before assembling different configurations of the process operations. 

Choice of Process Configuration. The sequence of processing steps and flowsheet configuration must be selected concurrently with the choice of extraction chemistry. Some of the established heuristics of separation process synthesis may be helpful here. For example, in multimetal fractionation it is probably better to tiy selective stripping from a single organic stream than to do multiple selective-extraction oper-... 

In the effort of total synthesis of discodemolide, the Still-Gennari type HWE reaction was also used by Paterson and Lyothier to form the Cg-C9 olefin. Phosphonate 94 was treated with NaH in THE at 0 °C for 30 min prior to the addition of aldehyde 93. The crude product showed a mixture of (Z)- and ( )-olefins, 95 and 96, in a 5 1 ratio. The desired (Z)-isomer 96 could be isolated by flash chromatography in 73% yield. The (Z)-enone 96 was further treated with K-Selectride at 25 C for 24 h. A single diastereomeric alcohol 97 was formed selectively and isolated in 59% yield. This alcohol processing (7/ )-configuration was leading to 1-epi-discodermolide 98 as final product by four additional reactions. 

Pham, V., El-Halwagi, M. (2012). Process synthesis and optimization of biorefmery configurations, AIChE Journal, 58, 1212-1221. 

Methanol Synthesis. AH commercial methanol processes employ a synthesis loop, and Figure 6 shows a typical example as part of the overall process flow sheet. This configuration overcomes equiUbtium conversion limitations at typical catalyst operating conditions as shown in Figure 1. A recycle system that gives high overall conversions is feasible because product methanol and water can be removed from the loop by condensation. 

---