Reactor continuous loop

Dilution, separation, and neutralization can take place in the same reactor or several batch units may be used for the consecutive steps (see also Sec. XX.X). Sulfuric acid sulfonation in a continuous loop reactor system is feasible when an H2S04/AB ratio of at least 1.80 is applied. In this case, as well as when 20% oleum is used, reasonably short reaction times are sufficient to complete the reaction. With increasing H2S04/AB ratio, the amount of dark 80% sulfuric acid (spent acid) will increase proportionally. 

Abad C, de la Cal JC, Asua JM (1995) Start-up procedures in the emulsion copolymerization of vinyl esters in a continuous loop reactor. Polymer 36 4293-4299... 

The continuous loop reactor is likely to be the only tubular reactor used on commercial production of emulsion polymers [71], although its use is limited to production of vinyl acetate homopolymers and copolymers (with ethylene and VeovalO) [77-79]. A continuous-loop reactor consists of a tubular loop that connects the inlet and the outlet of a recycle pump. These reactors combine the heat transfer characteristics of a tubular reactor with the RTD of a CSTR. The main drawback of this reactor is that the requirements for the mechanical stability of the latex are stringent because the recycling pump may induce shear coagulation. 

Figure 3.6. Measurement set-up (a) for determining the mixing time, and inhomogeneity, J, for a continuous loop reactor with differing degrees of mixing as a function of the strength of the recycled stream, F. (b) CSTR ,n, behavior with t

Loop process Experimental investigations and modeling of emulsion copolymerization in continuous loop reactors 175... 

Wasserscheid, P., Eichmann, M. (2001). Selective dimerisation of 1-butene in biphasic mode using buffered chloroaluminate ionic liquid solvents - Design and application of a continuous loop reactor. Catal. Today, 66,2-4, (March 2001) 309-316, ISSN 0920-5861... 

Nickel sulfate also is made by the reaction of black nickel oxide and hot dilute sulfuric acid, or of dilute sulfuric acid and nickel carbonate. The reaction of nickel oxide and sulfuric acid has been studied and a reaction induction temperature of 49°C deterrnined (39). High purity nickel sulfate is made from the reaction of nickel carbonyl, sulfur dioxide, and oxygen in the gas phase at 100°C (40). Another method for the continuous manufacture of nickel sulfate is the gas-phase reaction of nickel carbonyl and nitric acid, recovering the soHd product in sulfuric acid, and continuously removing the soHd nickel sulfate from the acid mixture (41). In this last method, nickel carbonyl and sulfuric acid are fed into a closed-loop reactor. Nickel sulfate and carbon monoxide are produced the CO is thus recycled to form nickel carbonyl. 

Continuous polymerization systems offer the possibiUty of several advantages including better heat transfer and cooling capacity, reduction in downtime, more uniform products, and less raw material handling (59,60). In some continuous emulsion homopolymerization processes, materials are added continuously to a first ketde and partially polymerized, then passed into a second reactor where, with additional initiator, the reaction is concluded. Continuous emulsion copolymerizations of vinyl acetate with ethylene have been described (61—64). Recirculating loop reactors which have high heat-transfer rates have found use for the manufacture of latexes for paint appHcations (59). 

Continuous slurry reactors are generally either of one of two designs. One type uses a reactor loop, generally known as a Buss loop design the other is a co-current hydrogen/fatty acid/catalyst system mainly marketed by Lurgi. Continuous slurry reactors are more popular in Europe, Asia, and South America than in the United States. 

A loop reactor is a continuous steel tube or pipe which connects the outlet of a circulation pump to its inlet (Figure 3.1). Reactants are fed... 

Cyclization via continuous flow reactor (380 °C, 45 s loop) and decarboxylation have been described neat. The change in selectivity of cyclization is notable and will be addressed later (compare conversion of 51-52 with 56-57). 

To produce reliable data on the lifetime and overall activity of the ionic catalyst system, a loop reactor was constructed and the reaction was carried out in continuous mode [105]. Some results of these studies are presented in Section 5.3, together with much more detailed information about the processing of biphasic reactions with an ionic liquid catalyst phase. 

A similar catalytic dimerization system has been investigated [40] in a continuous flow loop reactor in order to study the stability of the ionic liquid solution. The catalyst used is the organometallic nickel(II) complex (Hcod)Ni(hfacac) (Hcod = cyclooct-4-ene-l-yl and hfacac = l,l,l,5,5,5-hexafluoro-2,4-pentanedionato-0,0 ), and the ionic liquid is an acidic chloroaluminate based on the acidic mixture of 1-butyl-4-methylpyridinium chloride and aluminium chloride. No alkylaluminium is added, but an organic Lewis base is added to buffer the acidity of the medium. The ionic catalyst solution is introduced into the reactor loop at the beginning of the reaction and the loop is filled with the reactants (total volume 160 mL). The feed enters continuously into the loop and the products are continuously separated in a settler. The overall activity is 18,000 (TON). The selectivity to dimers is in the 98 % range and the selectivity to linear octenes is 52 %. 

Figure 2.5 Possible technological solutions to bioprocess problems a) Fed-batch culture b) Continuous product removal (eg dialysis, vacuum fermentation, solvent extraction, ion exchange etc) c) Two-phase system combined with extractive fermentation (liquid-impelled loop reactor) d) Continuous culture, internal multi-stage reactor e) Continuous culture, dual-stream multi-stage reactor f) Continuous culture with biomass feedback (cell recycling). (See text for further details).

A real continuous-flow stirred tank will approximate a perfectly mixed CSTR provided that tmix h/i and tmix i. Mixing time correlations are developed using batch vessels, but they can be applied to flow vessels provided the ratio of throughput to circulatory flow is small. This idea is explored in Section 4.5.3 where a recycle loop reactor is used as a model of an internally agitated vessel. 

The Eulerian multiphase model is used to predict the dispersed gas-liquid flow in the airlift loop reactor. It involves a set of momentum and continuity equations for each phase. Model equation coupling is achieved through the pressure and interphase exchange coefBcdents [5],... 

Column reactors can contain a draft tube - possibly filled with a packing characterized by low pressure drop - or be coupled with a loop tube, to make the gas recirculating within the reaction zone (see Fig. 5.4-9). In recent years, the Buss loop reactor has found many applications in two- and three-phase processes About 200 Buss loop systems are now in operation worldwide, also in fine chemicals plants. This is due to the high mass-transfer rate between the gas and the liquid phase. The Buss loop reactor can be operated semibatch-wise or continuously. As a semibach reactor it is mostly used for catalytic hydrogenations. 

Solid catalysts can be conveniently studied in loop reactors, which allow measuring the rates by difference measurement across the catalyst bed. When operated continuously, they usually can be modelled as well-stirred tanks. Here the case of catalyst deactivation is studied. 

Continuous extraction loop reactor Ethanol production with glucose fermentation Saccharomyces cerevisiae 126... 

Loop reactors continuous flow reactors in which all or part of the product stream is recirculated to the reactor, either directly or mixed with a reactant supply stream. 

Fig. 1 A continuous recycle-loop reactor for catalyst studies.

Continuous operation In flow-type reactors, e.g., loop reactors, the space velocity of the reaction is determined through the installed static mixing device that is used to generate the dispersion, together with the velocity of the circiflating medium (catalyst- and substrate/product phase). Knowledge of these parameters allows one to set up a kinetic model for the investigated reaction. 

As the next step in multiphasic hydrogenation, the design and implementation of a continuously driven loop reactor as a laboratory-scale plant model led to comparable selectivity applying the same water soluble ruthenium-based catalyst system. 

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