Batch process, principles

The process for manufacture of a chloroprene sulfur copolymer, Du Pont type GN, illustrates the principles of the batch process (77,78). In this case, sulfur is used to control polymer molecular weight. The copolymer formed initially is carried to fairly high conversion, gelled, and must be treated with a peptising agent to provide a final product of the proper viscosity. Key control parameters are the temperature of polymerisation, the conversion of monomer and the amount/type of modifier used. 

Medicinal products and bulk pharmaceutical chemicals are produced mainly in batch processes. Controlling these products and chemicals at the end of their manufacturing processes is not in line with the general principle of quality assurance, which is that quality should be built into the product. It is then necessary to ensure that appropriate good manufacturing practices are adhered to throughout the manufacture of both bulk pharmaceutical chemicals (active ingredients as well as excipients) and medicinal products. 

An important consequence of MSPC in the context of this chapter is that it is a key tool in the development of process understanding [157]. These references also illustrate the utility of multivariate control charts in identifying abnormal events and how these can then be used to aid understanding of the underlying fault conditions. It has to be said that most literature examples apply to batch processes, but the principles are equally applicable to continuous processes. 

Perhaps the hypersorption process (7) of recent years may be thought new and it is new in applying the mechanical principle of continuous operation to charcoal adsorption, but such adsorption on a batch process was in use more than 25 years ago and became obsolete in competition with absorption. Now the continuous hypersorption method appears to be finding a real field of usefulness, especially in making very high recoveries of propane and in recovering substantial amounts of ethane. Recovery of ethane is beginning to be important, in connection with its use as a chemical raw material for the reactions mentioned previously in this paper. 

The first spectra obtained with the mass spectrometer date back to 2007, where gas mixtures of Neon, Air and Argon were measured [23], This PIMMS-device was the first in which the separation principle relied on the new Synchronous Ion Shield (SIS) Separator, and the first proof-of-principle for the total integration of a mass spectrometer using batch processes of MEMS technology. Also a quantitative correlation could be stated from the peak heights for different gas concentrations. 

After cooling the resin in the reactor, the resin is pumped to the buffer tank of the connected spray dryer plant. Usually, the complete batch processing takes 4-5 h. The urea-formaldehyde resin solution can be dried in a spray dryer based on co-current flow principle. 

In order to increase the efficiency of such a batch process and to reduce the inconvenience of discontinuous operation when the extractor is decompressed and opened for replacing the spent material against fresh one the extraction volume is spread over three or four vessels. These are switched into the gas circulation in a battery-type sequence utilizing the countercurrent principle. This means the extractor containing already depleted material is first contacted with the fresh gas and the extractor with the fresh material containing the full extract concentration is contacted in the second or last position in order to benefit as much as possible from the dissolving capacity of the gas. 

The basic principles of effective procedure writing previously presented apply equally well to batch processes, but batch processes also have specific procedure considerations. Batch equipment often is used to produce multiple products with the same components. Typical batch operations are ... 

Magnetic-field sensors are widely used in automotive applications because of their robust design, their non-contacting and thus wear-free operation and their low manufacturing costs, in particular for solid-state sensors, which can be fabricated using batch processes. Their main fields of application in automobiles are speed and position sensing. In total, about one third of today s automotive sensors are based on the magnetic principle [1],... 

Compared to batch processes, continuous processes often show a higher space-time yield. Reaction conditions may be kept within certain limits more easily. For easier scale-up of some enzyme-catalyzed reactions, the Enzyme Membrane Reactor (EMR) has been developed. The principle is shown in Fig. 7-26 A. The difference in size between a biocatalyst and the reactants enables continuous homogeneous catalysis to be achieved while retaining the catalyst in the vessel. For this purpose, commercially available ultrafiltration membranes are used. When continuously operated, the EMR behaves as a continuous stirred tank reactor (CSTR) with complete backmixing. For large-scale membrane reactors, hollow-fiber membranes or stacked flat membranes are used 129. To prevent concentration polarization on the membrane, the reaction mixture is circulated along the membrane surface by a low-shear recirculation pump (Fig. 7-26 B). 

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