Filter-press reactor

FIGURE 18.1 (a) Bipolar electrode (i>) filter-press reactor (1) bipolar electrode (2) gas-... 

The importance of high rates of mass transport for a clean and efficient electrosynthesis using a filter press reactor has been stressed, and the effect of inclusion of a platic mesh turbulence promoter considered [56]. A multipurpose filterpress cell for continuous electrolysis of organic compounds has been described [57], and a mathematical model of the startup of a continuous parallel-plate reactor has been published [58]. 

Trinidad P, Ponce de Leon C. Walsh F.C., The application of flow dispersion models to FM01-LC laboratory filter-press reactor. Electrochemica Acta, 52, pp. 604-613, 2006. 

Smith, C.Z., Utley, J.H.F. and Hammond, J.K. (2011) The electro-oxidative conversion at a laboratory scale of a lignosulfonate into vanillin in an FMOl filter press reactor preparative and mechanistic aspects. Journal of Applied Electrochemistry, 41, 363-375. 

Walsh, F.C. and Robinson, D. (1995) Electrochemical synthesis and processing in modern filter-press reactors. Chemical Technology Europe, May/June, 16-23. 

Corrective Action Application An acidic groundwater at a Florida site (pH 2.5-3) required treatment. The groundwater was collected by extraction wells, pumped to an above-ground reactor, and neutralized with lime. In the course of neutralizing the waste stream, precipitates were formed which were removed by clarification and filtration prior to discharge. Sludges produced from the clarification and filtration steps were dewatered by a filter press. 

A well-known high conversion reactor is the so-called polymerization press, a modified plate-and-frame filter press where polystyrene is polymerized in frames alternating between cooling platens through which water (or steam) can be circulated. Other versions of the high conversion reactor have been utilized, e.g., the early "can process of Dow, where styrene monomer was placed in sealed cans in water baths and the metal stripped off at the end of the polymerization 2). 

Surface-modified electrodes were used for prevention of high overpotentials with direct oxidation or reduction of the cofactor, electrode fouling, and dimerization of the cofactor [7cj. Membrane electrochemical reactors were designed. The regeneration of the cofactor NADH was ensured electrochemically, using a rhodium complex as electrochemical mediator. A semipermeable membrane (dialysis or ultrafiltration) was integrated in the filter-press electrochemical reactor to confine... 

With many batch processes, the production rate will decrease during the production period for example, batch reactors and plate and frame filter presses, and there will be an optimum batch size, or optimum cycle time, that will give the minimum cost per unit of production. 

As a typical pattern of a multipurpose batch plant, the authors consider a plant with multiple floors that produces various products (e.g., fine chemicals or dyes) in batches and/or semicontinuously. Raw materials are entered into premixing devices and placed together in a reactor where the chemical reaction takes place. The resulting product is separated from the mother liquor by a filter press and then packaged in various types of packaging. The mother liquor is stored and eventually recycled. The same product may even take different paths through the plant by use of alternate devices or production lines. 

L-Cysteine is a high value a-amino acid used world-wide in a scale of 1200-15001 year-1 as additive in foodstuffs, cosmetics or as intermediate or active agent (as antidote to several snake venoms) in the pharmaceutical industry. Chemical routes generally lack the efficiency of electrochemical techniques, or they produce mixtures of l- and d- forms rather than the L-isomer. The most common electrochemical route is the cathodic reduction of L-Cystine in acid (usually HC1) solution to produce the stable hydrochloride. In Table 10, the charateristic data for a laboratory bench, laboratory pilot and a product pilot reaction using a DEM filter press are compared [13]. A production scale study was carried out in a filterpress reactor divided by a cation exchange membrane with a total area of 10.5 m2. The typical product inventory was 450 kg/24-hour batch time. For more details see Ref. [13]. 

The dinitro product is then cooled and filtered (the spent acid hquor is recoverable), the cake is washed with water, and the resulting washwater is sent to the wastewater treatment plant. The dinitro compound is then dissolved in an appropriate solvent and added to the amination reactor with water and soda ash. An amine is then reacted with the dinitro compound. The crude product is passed through a filter press and decanter and finally vacuum distilled. The saltwater layer from the decanter is discharged for treatment. The solvent fraction can be recycled to the reactor, and vacuum exhausts are caustic scrubbed. Still bottoms are generally incinerated. 

Two cubic meters of a nonbiodegradable organic industrial waste water with a COD of 10 kg/m3 and a TOC of 5 kg/m3 are to be pretreated (before the biological treatment) by anodic oxidation under galvanostatic conditions (i = 1 kA/m2) using a filter press electrochemical reactor with a 20 m2 anode surface area. Consider that ... 

Fig. 19.19 Sketch of the flow plant with an undivided filter-press two-electrode electrochemical reactor fed with oxygen used for the degradation of 30 dm3 of aniline solutions by electro-Fenton and peroxi-coagulation (Brillas et al. 2002)...

A chemical process consists of four reactors, 25 pumps, and a number of compressors, distillation columns, mixing tanks, evaporators, filter presses, and other materials handling and separation units. Each individual unit either requires or releases energy. 

A transfer of this definition of the cross-flow term to the chemical reactor field implies that the so-called cell reactor [26], consisting of thin, porous catalyst plates mounted in a rack like a filter press, should also be of interest to describe here. The same may apply to the great number of different electrochemical filter-press cell reactors [27]. It may be noted that the cell reactor principle is, however, not valid for the so-called parallel-passage reactor [28,29]. In this case the same fluid flows on both sides of the catalyst plates without any need for communication and exchange between the fluids through the plates. The advantage of this reactor is its being dust-proof, since dust present... 

The three kinds of reactors already described in this section are all traditional cross-flow reactors with permeable plates or membranes. The electrochemical filter-press cell reactors used, e.g., for electrosynthesis, are equipped with cation-selective membranes to prevent mixing of the anolyte and the catholyte. These cell reactors are therefore good examples of the extended type of cross-flow reactors according to the definition transferred from the filtration field. The application of the electrochemical filter-press cell reactor technique... 

It should also be observed that the catalytic cell reactor (described in Section II.D), which is intended to be an alternative reactor to trickle beds for liquid-phase hydrogenations, is a further-developed electrochemical filter-press cell based on the firm Electro Cell AB s concept with respect to the preparation of thin, porous electrodes. 

The catalytic plates are not completely accessible in the monolithic cross-flow structure, since a certain part of the plates is lost by contact with the corrugated interstitial planes of this structure. Moreover, the successful development in the preparation of thin, porous plates for electrochemical purposes created the idea that this preparation technique should also be used to produce permeable catalyst plates for cross-flow catalyst reactors. Instead of using these plates for the complicated cross-flow structure, the whole step was taken to using them in an electrochemical cell-like design of the reactor. The catalytic plates were thus mounted in a special rack like a filter press (Fig. 13), giving the so-called cell reactor [26]. 

The easiest cross-flow reactor to scale-up may be the cell reactor. Here the scale-up of the filter press serves as a good model. 

Some filter-press type electrochemical reactors can be used both in a divided and undivided mode. This is illustrated in Ref. 51. The ICI filter-press cell system FM 21 is discussed in the context of several pilot-plant applications, most of them organic. 

BR = Batch reactor FP = Filter press IE = Ion exchange VE = Vacuum evaporator CC = Cooled crystallizer FC = Filter centrifuge VD = Vibratory drier CW = Cooling water X = Xylose... 

Molina, V.M., Frias, A., Gonzalez, J., Montiel, V., Gonzalez. D.. Dommguez. M.. and Aldaz, A. 2004. Design and development of filter-press type electrochemical reactors for their application in the resolution of environmental problems. In Trends in Electrochemistry and Corrosion at the Beginning of the 21st Century. Brillas. E.. and Cabot. P.-L.. Eds. Universitat dc Barcelona, Barcelona, pp. 383-399. 

Figure 4.30 Scheme for polyether polyol fabrication by anionic polymerisation of alkylene oxides, initiated by glycerol or diols (variant). 1 - Reactor for potassium glycerolate synthesis 2 - Reactor for prepolyether synthesis 3 - Reactor for polyether synthesis 4 - Reactor for purification 5 - Filter press 6 - Storage tank for final purified poly ether 7 - Heat exchangers for removal of the reaction heat 8 - Condensers 9 - Vacuum pumps 10 - Vessels for distilled water 11 - Recirculation pumps 12 - Gear pump or screw (or double screw) pump... 

Figure 20.2 Technological scheme for recovery of rigid PU foam wastes by glycolysis process (variant) 1 Mills for PU scrap 2 Storage of ground rigid PU foam 3 Screw for powdered materials 4 Glycolysis and alkoxylation reactor 5 Electrical induction heaters 6 Filter press 7 Storage tank for the recovered polyol 8 Gear or screw (or...

Let us construct a reactor model that will predict the effects of conversion, current density, and electrolyte circulation rate on the chemical yield and run time of a cell for the production of -anisidine (see Clark et al., 1988 for details). The electrolytic cell used will be assumed to be of the narrow gap filter press type with total recirculation of... 

As it leaves reactors N°3 or N°4, the solution is filtered using a filter press. The filtrate, free of mercury and selenium, is sent to the central treatment facility (high density sludge) for final neutralization (see Figure 2). 

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