Reactors CSTRs

Styrene—maleic anhydride (SMA) copolymers are used where improved resistance to heat is required. Processes similar to those used for SAN copolymers are used. Because of the tendency of maleic anhydride to form alternating copolymers with styrene, composition drift is extremely severe unless the polymerization is carried out in CSTR reactors having high degrees of back-mixing. 

Fig. 28. Linear and CSTR reactor configuration used commercially for PS manufacture (see also Fig. 20).

The Pt film, with a surface area corresponding to NG=4.2-10 9 mol Pt, measured via surface titration of oxygen with C2H4,1,4 is exposed to po2 — 4.6 kPa, PC2H4 = 0.36 kPa at 370°C in a continuous flow gradientless (CSTR) reactor of volume 30 cm3. The rate of C02 formation is monitored via an infrared analyzer.1,4... 

Friis and Hamielec (48) offered some comments on the continuous reactor design problem suggesting that the dispersed particles have the same residence time distribution as the dispersing fluid and the system can be modeled as a segregated CSTR reactor. 

We begin the discussion of EPM by elaborating on this physical picture. Figure 1 shows a typical emulsion CSTR reactor and polymerization recipe. The magnified portion of the latex shows the various phases and the major species involved. The latex consists of monomers, water, surfactant, initiator, chain transfer agent, and added electrolyte. We used the mechanism for particle formation as described in Feeney et al. (8-9) and Hansen and Ugelstad (2). We have not found it necessary to invoke the micellar entry theory 2, 2/ 6./ 11/ 12/ 14. 

Figure 8.2 Reaction profile of batch and CSTR reactors...

As reported, the effluent of the first anaerobic UASB reactor (Runl) was used as the influent of the second UASB reactor (Run2), and the effluent of the second UASB reactor was used for the influent of the aerobic CSTR reactor (Run3). COD removal efficiencies for the first UASB reactor and in the whole system (two-step UASB + CSTR) were 58%, 62%, 65%, 72%, 74%, 79%, and 96%, 96.8%, 97.3%, 98%, 98%, and 98%, respectively. As the OLR increased from 4.3 to 16kg/m3/d, the COD removal efficiency reached a maximum of 80%. NH4-N removal efficiency was ca. 99.6% after the aerobic stage. The maximum methane percentages of the first and second UASB reactors were 64% and 43%, respectively. 

In this study, anaerobic and aerobic processes using sequential two-step UASB/CSTR reactors were found to form a feasible process for treating the leachate from food solid waste. COD removal efficiencies for the first and second anaerobic, aerobic and total system processes were 79%, 42%, 89%, and 98%, respectively. The COD loading rate used ranged from 4.3 to 16kg/m3/d. 

Comparison of performance of a series of N equal-size CSTR reactors with a plug flow reactor for the first-order reaction... 

Equations 9.3.11 and 9.3.12 are also applicable to a CSTR reactor, since they represent overall... 

Figure 8.7 demonstrates that the H2-activated catalysts that were calcined using nitric oxide resulted in higher initial CO conversion rates on a per gram of catalyst basis in a CSTR reactor at 220°C and 280 psig, and using a Fl2/CO ratio of 2.5. 

The GPC traces in Fig. 24 reveal a broad molecular weight distribution, MJMn = 4.42, for the dual reactor blend sample. On the other hand, the diblock OBC displays an overall MJMn of 1.67. The narrowing of the distribution indicates that the polymerization has CCTP characteristics. The theoretical molecular weight distribution from an ideal living polymerization in a series of two CSTR reactors is given by the following equation, where/j and/2 are the mass fractions of polymer comprising the two blocks [11] ... 

The operating parameter for the CSTR reactor is the liquid flow rate Q, which sets the residence time of the liquid through the ratio Q/VL and finally the conversion. From a production viewpoint, the (residence) time required to achieve a given conversion of S (or outlet concentration of S) is obtained by solving the set of Eqs. (33) and (34). The characteristics of the reactor kLa and VL must be known. In general, whereas VL is easily determined in a batch reactor, it is not in a CSTR. Rather, VL=fiLVR will be used, which requires knowledge of the liquid hold-up L. Correlations provide kLo (see below) and L characteristics for the different reactor types [3]. 

Continuous-stirred-tank-reactor system, 11 198-199, 204. See also CSTR reactor system... 

CSTR reactor system, 23 396. See also Continuous- stirred tank reactor (CSTR) anionic polymerization C-toxiferine, 2 74, 99 C-type inks, 14 324, 326 C-type natriuretic peptide (CNP), 5 186-187... 

Continuous Flow Plug-Flow and CSTR Reactors... 

Figure 4.3 Schematic chart of a CSTR reactor for the 0-methylation of phenols with DMC. Liquid reagents are vaporized by contact with the hot slurry (mechanically stirred) and bubbled through it. Reaction takes place instantaneously and anisoles are picked up from the vapor phase.

Figure 1. Comparison of the effects of feedstock cellulose content on specific ceUulase enzyme activities in sludge from 4 CSTR reactors operated under similar conditions. Although the cellulose content of the feedstock was varied, the total volatile solids content for all reactors was equivalent.

Gibilaro [49] has considered a recycle model of the form of eqn. (60) where Gj (s) and G2(s) are general series combinations of PFR and equal size CSTR reactors and he gives sixteen references to published work involving more restricted forms of Gj (s) and G2 is). With an infinite choice over the forms of G (s) and G2(s) and the magnitude of R, the recycle model is seen to be the most flexible of all flow-mixing models. The performance of each specific form of Gj (s) as a potential reactor must be investigated individually in practice, the model is often reduced to a pure PFR element... 

For first-order kinetics with equal-volume CSTR reactors (and therefore for all TS equal), the mass balances on species A become... 

Figure 3-9 Total residence time from 1 /r plot for a series of CSTR reactors for 1, 2, 3,4, and n equal-volimie...

Figure 3-15 Possible transients in CSTR reactors. The upper panel shows the situation starting with pure solvent (CA = 0) in the reactor initially, Cn = C o at I = 0 with no reaction. The concentration in the reactor in steady state approadies Cas- Ttt shows the situation where the reactor initially contains pure reactant at C40. at f = 0 reactant flow at Qo is begun and eventually approaches a steady-state concentration Cas-...

Calculate the reactor volumes required to process 100 liter/min of 3 molar A in the aqueous reaction A -4 2B for PFTR and CSTR reactors. 

Note that now Tj is a variable that is a function of position Zc in the cooling coif while T, the reactor temperature in the CSTR reactor, is a constant. We can solve this differential equation separately to obtain an average coolant temperature to insert in the reactor energy-balance equation. However, the heat load on the cooling coil can be comphcated to calculate because the heat transfer coefficient may not be constant. 

These are exactly the expressions for conversions for a first-order irreversible reaction in PFTR and CSTR reactors that we derived much earlier (and with much less mathematical manipulation). 

Sohds reactors are multiphase reactors so we must consider both the conversions of sohd Xs and of fluid phases X to specify these reactors. In this chapter we have not considered the reactor equations that must be solved to predict the overall conversion of reactants in the reactor. As might be expected, we assume PFTR and CSTR reactors, and solve for conversion X in the reactor. 

In CSTR reactors, both phases are considered to be in complete mixed and continuous-flow condition. In the general case where reactants can be gases and liquids, the following material balances can be applied (for simplicity we consider constant-density systems) (Hopper et al., 2001)... 

The gas-phase material balances can be written in the classic form of CSTR reactor material balances (Levenspiel, 1972) ... 

Continuous flow of both phases in upflow and complete mixing of phases For packed bubble columns (upflow of both gas and liquid phases), under the assumption of complete mixed flow, the backmixing model of Ramachandran and Chaudhari (1980) is applicable. The relevant equations are presented in Section 3.5.1 for the continuous flow of gas and slurry phases in complete mixed-flow conditions (slurry CSTR reactor). 

In reality, of course, mixing cannot be perfectly instantaneous. In practice, CSTR reactors are designed to create high-intensity turbulence that enhances mixing. Also very low-pressure systems can often be considered as stirred reactors. At low pressure (e.g., below 1 Torr), the molecular-diffusion rate is very high owing to long mean-free paths. 

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