Semi-continuous apparatus

A sourdough yeast strain (S. cerevisiae) and two bacterial species (S. marcescens, B. subtilis) were treated in a physiological buffer (PBS).The first experiments (with the yeast) were performed in a batch apparatus (Fig. 10) as well as in a semi-continuous apparatus (Fig. 12). As the latter device showed a higher efficiency in the microbial inactivation than the... 

Metallizers with external unwind and rewind facilities have also become known. Here the web is transported into and out of the vacuum chamber through locks. Because of demanding requirements of instruments and apparatus, these coaters have not gained acceptance for coating of polymer webs. They are successfully used in semi-continuous processes, for example glass coating. 

The semi-continuous type of reactor with the large capacity was comprised of a pyrolysis chamber, a catalytic cracking chamber and a separation and purifying section. The feed plastic material was melted and decomposed in the pyrolysis chamber held at the ambient pressure and at the temperature 723-783 K, and fed to the catalytic cracking chamber. A reflux condenser was used to separate and purify the products formed in the chamber and individual factors were obtained using fractional distillation apparatus [26]. Different types of reactors are being utilized depending on the type of feed and the expected products from the pyrolysis. 

A semi-continuous SAS apparatus, as a rule, consists of two pumps used to deliver the liquid solution and supercritical CO2, respectively. A cylindrical vessel is used as the precipitation chamber. The liquid mixture is delivered to the precipitator through an injector. Different arrangements have been proposed in the literature like nozzles, capillaries, vibrating orifices and coaxial devices. Supercritical CO2 is delivered through another inlet port that can be located on the top or the bottom of the vessel. The pressure in the precipitator is regulated by a micrometering valve located at the exit of the chamber. A stainless-steel fiit located at the bottom of the precipitator is used to collect the produced powder. A second vessel located downstream the micrometering valve is used to recover the Uquid solvent. 

Apparatus for semi-continuous vacuum distillation with column and heating of the feed... 

In industrial continuous distillations plate columns are preferably used [34]. Recent developments of laboratory and semi-technical apparatus have been thoroughly discussed by Stage who has also dealt with the question of systematic tests for efficiency- [35]. The advantages of bubble-cap columns in continuous operation have already been mentioned (cf. chap. 5.2.2.3 Fig. 167). Cyclic operation (Fig. 164) yields efficiencies >150%. 

Figure 4.19 shows a schematic representation of state-of-the-art expression apparatus. The more conventional piston press apparatus described in Section 4.5.1 is augmented with the addition of a computer driven pressure regulator which allows the pressure applied to the piston to be carefully controlled and varied according to a preset pattern (e.g. ramp, sinusoidal etc.). The interfaced rotary or linear encoder, force transducer and electronic balance allow semi-continuous measurements of piston displacement, transmitted pressure and... 

In these operations the fluid and adsorbent are in contact throughout the entire apparatus, without periodic separation of the phases. The operation can be carried out in strictly continuous, steady-state fashion, characterized by movement of the solid as well as the fluid. Alternatively, owing to the rigidity of the solid adsorbent particles, it is also possible to operate advantageously in semi-continuous fashion, characterized by a moving fluid but stationary solid. This results in unsteady-state c hditions, where compositions in the system change with time. 

Fig. 4.34 Semi-automated continuous coating apparatus for catalyst and precursor preparation. The procedure is demonstrated here using an unstructured metal foil unwound from a roll. The wash-coat slurry is fed through a slot die onto the metal foil. After coating, the foil is sent through a drying compartment and wound up.

Fig. 6.31. Schematic arrangement of an apparatus for continuous flow isoelectric focusing, a. Electrode compartment b, semi-permeable membrane c, running space.

The extent to which measuring and control devices are employed in batch and continuous distillation depends on the nature of the work and, to a considerable degree, on financial considerations [12]. In practice a distinction can be made between semi- (or partly) automatic and fuUy automatic apparatus. In the latter all operations except starting up are performed automatically in partly automatic apparatus only some of the functions are governed by regulating devices. 

A new apparatus (Fig. 12) was built for continuous extraction experiments with contaminated soil material and supercritical water [6]. It consisted of a tubular extractor, a membrane pump for delivering the suspension to the extractor, and the expansion valves. Figure 13 shows semi-batch and continuous extraction results as a function of solvent to soil ratio. Compared to semi-batch extraction, residence times can be reduced... 

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