Downstream processing separations

Conduct of extensive pilot-scale manufacturing development fermentation and downstream processing (separation and purification)... 

Figure 7.13 Depletion behavior of an impurity using different downstream processes separately and combined with each other. The starting material had a content of 14.2% Beta that was enriched to 29.1% in the mother liquor.

The numerator of Equation (JAlti) is the profit from Product B minus the cost of unused reactant A minus the cost of cleaning. The denominator is singly the total time for the cycle and thus averages the profit over the cycle time. This formulation of the OF assumes that the unused reactant is not recovered and recycled and that the cost of downstream processing (separation of B from A, and purification of B) are not affected by the extent of reaction. Both these assunptions should be relaxed if information about the downstream processes is available. 

The main advantage of SCCO2 lies in the easiness of the possible downstream processing. Separating products from reactants can be greatly facilitated by the ease with which the solvent power of SCF solvents can be adjusted. By coupling a series of depressurization steps at the outflow of the reaction vessel, it is possible to selectively fractionate products and residual substrates of a reaction [9]. The fluid can be recycled after repressurizing. Different methods are described for the calculation of solubility in SCFs [10-13]. 

Refining crude oil into useful petroleum products can be separated into two phases and a number of supporting operations. The first phase is desalting of crude oil and the subsequent distillation into its various components or "fractions." The second phase is made up of three different types of "downstream" processes combining, breaking, and reshaping. 

Product separation for main fractionators is also often called black oil separation. Main fractionators are typically used for such operations as preflash separation, atmospheric crude, gas oil crude, vacuum preflash crude, vacuum crude, visbreaking, coking, and fluid catalytic cracking. In all these services the object is to recover clean, boiling range components from a black multicomponent mixture. But main fractionators are also used in hydrocracker downstream processing. This operation has a clean feed. Nevertheless, whenever you hear the term black oil, understand that what is really meant is main fractionator processing. 

Thus, methods are now becoming available such that process systems can be designed to manufacture crystal products of desired chemical and physical properties and characteristics under optimal conditions. In this chapter, the essential features of methods for the analysis of particulate crystal formation and subsequent solid-liquid separation operations discussed in Chapters 3 and 4 will be recapitulated. The interaction between crystallization and downstream processing will be illustrated by practical examples and problems highlighted. Procedures for industrial crystallization process analysis, synthesis and optimization will then be considered and aspects of process simulation, control and sustainable manufacture reviewed. 

When ionic liquids are used as replacements for organic solvents in processes with nonvolatile products, downstream processing may become complicated. This may apply to many biotransformations in which the better selectivity of the biocatalyst is used to transform more complex molecules. In such cases, product isolation can be achieved by, for example, extraction with supercritical CO2 [50]. Recently, membrane processes such as pervaporation and nanofiltration have been used. The use of pervaporation for less volatile compounds such as phenylethanol has been reported by Crespo and co-workers [51]. We have developed a separation process based on nanofiltration [52, 53] which is especially well suited for isolation of nonvolatile compounds such as carbohydrates or charged compounds. It may also be used for easy recovery and/or purification of ionic liquids. 

The culture can be used directly for the conversion of phenylpyruvic add to resting cells L-phenylalanine. Therefore, a batch process with resting cells can be carried out, with some glucose added for maintenance (fed-batch fermentation). Another approach is to harvest the cells from the fermentation broth and to use them in a separate bioreactor in higher concentrations than the ones obtained in the cell cultivation. An advantage of the last method can be that the concentration of compounds other than L-phenylalanine is lower, so that downstream processing may be cheaper. 

The boiler steam-water circulation system is designed to promote the delivery of steam from the various generating tubes to the boiler steam drum (top drum). From here the steam is separated from the BW and transferred to the steam delivery system for possible superheating and subsequent use in a turbine generator or other downstream process application. 

In terms of downstream processes, the flow-rates, compositions, and so on, dictate the size and number of each unit operation for example, while a batch distillation may be used to separate a single feed into a number of different product streams, a continuous distillation train would in general require N columns for N different product streams. The fact that a high degree of modeling is used in the design of each MPI, results in the generally held belief that continuous processes... 

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