Batch process filtration

In a batch process, NaOH is chlorinated in the presence of recycled neutral Ca(OCl)2 mother Hquor. After separation of salt, lime slurry is added and chlorinated (205). The Ca(OCl)2 2H20 crystals are recovered by filtration. In another version, classification of the Ca(OCl)2—NaCl slurry gives a Ca(OCl)2-rich fraction that is filtered and the filtrate recycled along with the NaCl-rich fraction to the first chlorinator (206). Also, 50% NaOH and soHd slaked lime are used in the second chlorination. 

In cake or surface filtration, there are two primary areas of consideration continuous filtration, in which the resistance of the filter cake (deposited process solids) is veiy large with respec t to that of the filter media and filtrate drainage, and batch pressure filtration, in which the resistance of the filter cake is not veiy Targe with respect to that of the filter media and filtrate drainage. Batch pressure filters are generally fitted with heavy, tight filter cloths plus a layer of precoat and these represent a significant resistance that must be taken into account. Continuous filters, except for precoats, use relatively open cloths that offer little resistance compared to that of the filter cake. 

A better solution for preparative columns is the development of separation media with substantially increased selectivities. This approach allows the use of shorter columns with smaller number of theoretical plates. Ultimately, it may even lead to a batch process in which one enantiomer is adsorbed selectively by the sorbent while the other remains in the solution and can be removed by filtration (single plate separation). Higher selectivities also allow overloading of the column. Therefore, much larger quantities of racemic mixtures can be separated in a single run, thus increasing the throughput of the separation unit. Operation under these overload conditions would not be possible on low selectivity columns without total loss of resolution. 

A flow diagram of a simple cross-flow system is shown in Figure 16.12. This is the system likely to be used for batch processing or development rigs it is in essence a basic pump recirculation loop. The process feed is concentrated by pumping it from the tank and across the membrane in the module at an appropriate velocity. The partly concentrated retentate is recycled into the tank for further processing while the permeate is stored or discarded as required. In cross-flow filtration applications, product washing is frequently necessary and... 

Figure 4.12 Precipitation of product synthesis of aspartame from phenylalanine methylester applying a batch process in combination with two filtration steps...

Figure 4.14 Chemical adducts for by-product removal synthesis of isopropyl-cis-Ag-hexadecanoate from isopropylpalmitate applying a repetitive batch process using a sequence of stirred-tank reactor, extraction module, filtration step and chromatographic downstream processing...

Figure 4.17 Substrate adsorption synthesis of ((S)-3,4-methylenedioxyphenyl)-2-propanol from 3,4-methylenedioxyphenylacetone applying a batch process followed by a filtration step and resin extraction...

By using this technique only water insoluble monomers can be polymerised. In this process, the monomer is suspended as discrete droplets (0.1 to 1.0 mm diameter) in dilute aqueous solution containing protective colloids like polyvinyl alcohol and surfactants, etc. The droplets have large surface area and can readily transfer heat to water. Suspension is brought about by agitating the suspension. Protective colloids prevent coalescence of the droplets. A monomer soluble initiator is used. The product is obtained by filtration or spray drying. This process cannot be carried out yet in a continuous process hence batch processing has to be used. 

Weak anion-exchange resins (Dowex Marathon WBA, 25-50 mesh) obtained from Aldrich (Milwaukee, WI) were equilibrated with 0.1 M NaOH and then washed with water and filtered until a neutral effluent was obtained. The hydrolysate was treated with resins in a batch process at room temperature. The amount of resins added to the hydrolysate was sufficient to obtain pH 5.5. Thereafter, the resin beads were removed by filtration (Whatman no. 1 filter paper). 

Figure 2.4 Dead-end filtration is a batch process that produces one effluent stream given one influent stream.

Dead end filtration is a batch process. That means that the filter will accumulate and eventually blind off with particulates such that water can no longer pass through. The filtration system will need to be taken off line and the filter will need to be either cleaned or replaced. 

Many processes are carried out by the use of cyclic operations which involve periodic shutdowns for discharging, cleanout, or reactivation. This type of operation occurs when the product is produced by a batch process or when the rate of production decreases with time, as in the operation of a plate-and-frame filtration unit. In a true batch operation, no product is obtained until the unit is shut down for discharging. In semicontinuous cyclic operations, product is delivered continuously while the unit is in operation, but the rate of delivery decreases with time. Thus, in batch or semicontinuous cyclic operations, the... 

As the basis for a continuous process, always choose a unit of time or a consistent set of flow rates per unit of time. For batch processes, the appropriate basis is 1 batch. In the present (continuous) process, let the basis be 1 h. Let C be the mass flow rate of filter cake and F the mass flow rate of filtrate, in kilograms per hour. Figure 2.1 is a sketch of the system. 

Each group may be further subdivided into filters employed in continuous or batch processes although, due to technical difficulties, continuous pressure filters are uncommon and expensive. Centrifugation is another means of removing filtrate. Extensive surveys can be found in the literature. ... 

The purpose of this work was to optimize mixing, various pretreatment (coagulation and sedimentation) and filtration processes, utilizing artificial asbestos suspensions containing asbestos levels of the order of 5.10 ° to 10 f/1. At first, tests were carried out through a batch process to obtain the optimum conditions which were then applied to the pilot plant. Also, the pilot plant effectiveness was evaluated for asbestos fiber removal. 

Continuous addition of filter aid (body feeding) is accomplished either by feeding filter aid as a slurry or by dry feeding. Slurry feeding is usually done with plunger or diaphragm pumps. If filtration is a batch process, the filter aid can be added directly to the batch. 

The insoluble calcium carbonate is separated from the sodium hydroxide solution by simple settling in a batch process, or by settling in a thickener (Fig. 6.6) followed by filtration of the more concentrated slurry from the thickener in a continuous process (Fig. 7.3). 

In this batch process, after filtration of the zeolite at 80 °C, we can purify the p-benzophenone by crystallization with a very good yield. The excess phenetole was distilled and recycled. 

It is batch process and filtration conditions vary with time as the filter cake is building, with correlative pressure drop buildup and... 

Dual-Filtration Vessels. In order to transform a batch process into a semibatch process, the particle-loaded fluid is directed to one of at least two collection vessels that are operated altenatively in fluid filtration and particle harvesting. 

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