Batch-wise operation

Generally, although not exclusively, a scrubber with a recycle loop of the caustic scrubbing liquor is used cases of once-through scrubbing liquor operation do exist. The scrubber may be operated in batch, semi-batch or continuous mode with respect to the liquid. Process hazards exist in batch and continuous mode, the most significant of which is over-chlorination. Batch-wise operations leads to periodic high loads on the hypochlorite destruction unit. In order to even out these loads, and improve the process safety, a study of alternative treatment options has been undertaken. 

The promising results obtained under batch-wise operation could be confirmed also under continuous-flow conditions. As schematically shown in Fig. 2, the substrate was injected with an HPLC pump into a stream of premixed CO2 and O2 before entering the reactor. The supercritical mixture was bubbled through the stationary PEG phase containing the Pd nanoparticles. 

One of the most attractive features of the IL/CO2 approach to homogeneous catalysis is the development of continuous processes [7]. Consequently it needs to be demonstrated that the combination of a suitable IL and compressed CO2 can offer more potential for process optimisation than just a simple protocol for batch-wise catalyst recycling. As an example we were able to activate, tune and immobilise Ni catalyst 13 in a continuous-flow system for the hydroviny-lation of styrene (Scheme 3). Styrene is co-dimerised with ethene yielding 3-substituted 1-butenes [26,27]. We could show that this powerful carbon-carbon bond-forming reaction can be achieved with high enantioselectivity in batch-wise operation and in continuous-flow systems. 

Disadvantages batch-wise operation expensive (automated system) ... 

If the dependence (12.74) is known, a batch-wise operated full-scale flotation cell can be scaled up according to (12.74). 

Conical Mixer Dryer The conical mixer dryer is a batch-wise operating unit commonly used in the pharmaceutical and specialty chemical industries for the drying of solvent or water wet, free-flowing powders. The process area is a vertically oriented conical vessel with an internally mounted screw. Figure 12-80 shows a schematic of the bottom drive conical mixer dryer. The dryer utilizes the heatable, internal rotating screw to provide agitation of the batch of material and thus improve the heat and mass transfer of the process. Because it rotates around the full circumference of the vessel, the screw provides a self-cleaning effect for the heated vessel walls. 

Fig. 4 Flow-chart of Integrated Gasifier with Redox Filter in batch-wise operation.

Wood derived fast pyrolysis oil and slaked lime produce a Calcium-Enriched Bio-oil (CEB) capable to remove SO2 while combusting sulphur-containing fuels. The bio-oil required is produced in a 200 kg/hr fast pyrolysis plant, while CEB is made in batch-wise operation by slowly mixing slaked lime with bio-oil at controlled conditions. 

The principal actinides separation step is performed at low acidity, at pH of about 2. Denitration of HAW is therefore a crucial operation step on which little information is available. The operational margin is rather restricted. A too high pH would leak to heavy precipitate formation with actinides adsorbed on them. Only a batch-wise operation mode can satisfy the chemical and operational requirements and furthermore the utilisation of boiling formic acid raises material corrosion problems. 

Cross-linked crystals of lipase from Candida rugosa (CRL) were applied in the resolution of racemic ketoprofen chloroethyl ester. In batch-wise operation, the half-life of the catalyst was reached after about 18 cycles or, in terms of enzyme consumption, about 5.6 g of enzyme protein were consumed to prepare 1 kg of (S)-ketoprofen. CRL suffers from a low specific activity towards this poorly water-soluble substrate which may explain the high enzyme input [117]. 

A highly specific hydrolysis of sucrose could also be achieved by use of invertase from Saccharomyces cerevisiae (P-o-fructofuranosidase). Nevertheless high enzyme costs and the batch-wise operation mode proved economically disadvantageous over the ion exchange process. 

The pressure driven laminar flow platform is especially interesting for online monitoring applications, since it enables continuous flows compared to the merely batch-wise operation of most of the other microfluidic platforms (i.e. handling discrete liquid volumes). 

Both batch and continuous reactor operation were studied. The latter was utilized, as although, fine chemicals are usually produced in batch-wise operating slurry reactors, continuous reactors offer several benefits, e.g. minimization of the time between batches, exclusion of catalyst separation and abrasion problems. 

Naturally, a computer implementation of this procedure is required. An example of the application of the algorithm is provided for the case of hydrogenation of D-xylose to xylitol, which was carried out in the laboratory of the authors in a batch wise operating slurry reactor. 

Batch distillation (Fig. 3.15) is a capability included in some flowsheeting software that can be used as stand-alone or in combination with a continuous process. The model solves the unsteady state MESH equations under the constraints of batch-wise operation, as variable reflux, variable column pressure, time-programmed collection of fractions, or controlled thermal policy. A powerful feature is the investigation of a distillation strategy that minimises the time of a batch. 

Heijnen, R, and Lukszo, Z. (2006), Continuous improvement of batch wise operation A decision support framework, Production Planning Control, 17(4) 355-366. 

The above chemical transformations are of importance to the way the coprecipitation is carried out. In principle, there are several modes of operation. In a batch-wise operation, the base can be added to the acidic metal solution, or vice versa (forward and reverse coprecipitation, respectively), or both solutions can be added simultaneously. 

In a batch-wise operation, the product formed at the beginning of the precipitation is different from that formed at the end of the process and the final product is expected to be a mixture that is mostly suboptimal. Thus, in forward precipitation the pH rises gradually and, as expected for a product produced under acidic or neutral conditions, the material is rich in counterions like carbonate, nitrate, chloride, and sulfate. Extensive aging at higher pH is required to convert the material to a hydroxide-like precipitate. In addition, the least-soluble product will precipitate first leading to a sometimes undesirable... 

Batch Wise-Operated Stirred Tank Reactor (BSTR)... 

Figure 2.3 Batch-wise operated stirred tank reactor (BSTR).

Some of the chemical methods that have been used to investigate the mixing quality in different types of reactors are briefed in the text below. Most of the methods were developed for batch wise operated reactors and must be revisited and carefully adapted for the use in continuous microstructured devices. 

Type C reactions are considered as slow t. > 10 min). They are normally carried out in batch-wise operated vessels. Nevertheless, microstructured devices may be advantageous, if safety or product quality is an important issue. 

Bioreactor operation is either batch-wise or continuous. Batch-wise operation or batch cultures include aU the nutrients required for the growth of cells prior to cultivation of the oi anisms. After inoculation, cell growth commences and ceases once the organisms have exhausted all the available nutrients in the culture medium. A modification of this type of operation is a fed-batch or semi-batch operation in which the reactants are continuously fed into the bioreactor, and the reaction is allowed to go to completion, after which the products are recovered. Continuously operated hioreactors, use continuous culture systems that continuously feed culture medium into... 

Typical reaction equipment for fine and specialty chemicals production is a batch-wise operated multi-purpose plant (MPP). A common MPP set-up includes a stirred stainless-steel or glass-lined batch reactor with reflux condenser, feed systems for reactants and inert gases, as well as equipment for different, optional separation... 

As described above, for the continuously working process, it is not known whether the enrichment of the liquid with CO2 reaches the state of saturation. In order to estimate the fundamental influence of the dissolved CO2 on the spray formation and hence on the particle formation, first experiments with the batch wise operated lab... 

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