Equipment High pressure processing

Another example is the purification of a P-lactam antibiotic, where process-scale reversed-phase separations began to be used around 1983 when suitable, high pressure process-scale equipment became available. A reversed-phase microparticulate (55—105 p.m particle size) C g siUca column, with a mobile phase of aqueous methanol having 0.1 Af ammonium phosphate at pH 5.3, was able to fractionate out impurities not readily removed by hquid—hquid extraction (37). Optimization of the separation resulted in recovery of product at 93% purity and 95% yield. This type of separation differs markedly from protein purification in feed concentration ( i 50 200 g/L for cefonicid vs 1 to 10 g/L for protein), molecular weight of impurities (<5000 compared to 10,000—100,000 for proteins), and throughputs ( i l-2 mg/(g stationary phasemin) compared to 0.01—0.1 mg/(gmin) for proteins). 

The main disadvantage of SFE is the elevated pressure, requiring more expensive process equipment. The critical pressures, however, are below the pressures used in many high-pressure processes in the petrochemical industry today. 

J.P. Komer, M. Kopl Equipment for high pressure processes in the Chemical Industry, UHDEDoc. Nr. 924.3, 1993... 

High temperature and high pressure processing of materials often involves the use of supercritical fluids. Corrosion studies are quite essential for evaluation of the equipment in supercritical fluid operations. Previous electrochemical measurements for alloys in supercritical fluids are rare (1-1). The reported measurements (3) show that passivation of iron alloys is different at supercritical conditions compared to ambient conditions. The study of the electrochemistry of iron alloys can lead to control of corrosion of equipment utilizing the alloys. Thermodynamic analysis provides the information about stable species, i.e. corrosion products under given temperatures and pressures. 

The high-pressure process reaction operates at llOpsig and offers reduced equipment size at the expense of slightly lower NO selectivity. In the split-pressure process, the ammonia conversion is carried out at an intermediate pressure of about 30 psig, while the water absorption is carried out at higher pressure. The NO that is formed in the ammonia converter... 

Final assemblies should be pressure-tested and leak-tested to ensure their integrity. Laboratory workers are strongly advised to consult an expert on high-pressure work as they design, build, and operate a high-pressure process. Finally, extreme care should be exercised when disassembling pressure equipment for repair, modification, or decommissioning. Protective equipment should be worn just in case a line or vessel that is opened contains material under pressure. 

The plant in the high-pressure process is much smaller than conventional plant and can be prefabricated. There are obviously fewer pieces of equipment than in inter-pass absorption equipment. This gives considerably lower capital... 

These families of resin are produced in commercial scale high pressure processes. To produce these types of polymers, additional investment is needed, e.g. in corrosion protection, refrigeration capacity, extrusion equipment and process units to recycle the comonomers after purification back into the process. 

Industrial processes proposed for the extraction of natural products with near-critical solvents work in a pressure range between 50 bar and 500 bar, and in some exceptional cases up to LOOO bar. Therefore this type of extraction must be regarded as a high pressure process. The pressure vessels are very important, since it is in these that the initial extraction takes place and also in which the saturated solvent is separated from the product. The design and operation of the pressure vessels have a decisive influence on the successful performance of equipment for extracting natural products with near-critical solvents. While the calculation of the necessary wall thicknesses is based on well-established codes of practice for pressure vessels, the mechanical design and especially the operation itself are specific to the type of extraction process considered. 

Although the direct measurement of equilibrium data for mixtures at high pressures requires detailed experimental experience and expensive equipment, it is still an es sential and reliable way in order to obtain the data needed for the evaluation of high-pressure processes. Recently, Dohrn et al. (10] presented a classification of experimental methods for high-pressure phase equilibria. Figure 2.4 illustrates the two main groups analytical methods and synthetic methods. In case of analytical... 

The physical properties that affect the high-pressure processes are changed due to two reasons (i) mechanical effect of high pressure, and (ii) increased mutual solubilities of the two adjacent phases at high pressure. The physical properties (such as density, viscosity, and interfacial tension) have an impact on the multiphase flow, phase separation, and process efficiency. Diffusivity and wetting characteristics are related to the properties mentioned, and thus also subject to alterations. Equipment available for experimental determination of physicochemical quantities at elevated pressures are also described in Chapter 14. 

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