Multipak packing

In the past few years, a large number of CD processes on esterification using Katapak packing such as Katapak-S or Multipak packing together with solid acid catalyst such as Amberlyst 15 have been reviewed in detail and hence these processes will not be reviewed here. All these processes operate at mild temperature and pressure with conversions and selectivities in excess of 95% and in some cases close to 100%. 

Figure 9 (a) Catalytic structured packing Montz Multipak and (b) an example of reactive trays. (Part b from Ref. 53.)... 

The catalytic packing MULTIPAK (147) applied in this case study consists of corrugated wire gauze sheets and catalyst bags of the same material assembled in alternate sequence. Sufficient mass transfer between gas and liquid phase is... 

A batch distillation column with a diameter of 100 mm and a reactive packing height of 2 m (MULTIPAK I ) in the bottom section and an additional meter of conventional packing (ROMBOPAK 6M ) in the top section was used. The flow sheet of the column is shown in Figure 22. 

The mass balances [Eqs. (Al) and (A2)] assume plug-flow behavior for both the gas/vapor and liquid phases. However, real flow behavior is much more complex and constitutes a fundamental issue in multiphase reactor design. It has a strong influence on the reactor performance, for example, due to back-mixing of both phases, which is responsible for significant effects on the reaction rates and product selectivity. Possible development of stagnant zones results in secondary undesired reactions. To ensure an optimum model development for CD processes, experimental studies on the nonideal flow behavior in the catalytic packing MULTIPAK are performed (168). 

Figure 31 Comparison between the experimental RTD curve for the catalytic packing MULTIPAK (dc = 0.1 m), the ADM model, and the PDE model.

Experimental studies were carried out to derive correlations for mass transfer coefficients, reaction kinetics, liquid holdup, and pressure drop for the packing MULTIPAK (35). Suitable correlations for ROMBOPAK 6M are taken from Refs. 90 and 196. The nonideal thermodynamic behavior of the investigated multicomponent system was described by the NRTL model for activity coefficients concerning nonidealities caused by the dimerisation (see Ref. 72). 

Fig. 4 (A) Random packings (Raschig rings). (B) Structured packings, KATAPAK (Sulzer). (C) Structured packings, MULTIPAK (Sulzer).

Experimental studies were carried out to derive correlations for mass-transfer coefficients, reaction kinetics, liquid holdup and pressure drop for the new catalytic packing MULTIPAK (see [9,10]). Suitable correlations for ROMBOPAK 6M were taken from [70] and [92], The vapor-liquid equilibrium is calculated using the modification of the Wilson method [9]. For the vapor phase, the dimerization of acetic acid is taken into account using the chemical theory to correct vapor-phase fugacity coefficients [93]. Binary diffusion coefficients for the vapor phase and for the liquid phase are estimated via the method purposed by Fuller et al. and Tyn and Calus, respectively (see [94]). Physical properties like densities, viscosities and thermal conductivities are calculated from the methods given in [94]. 

MTBE synthesis has been investigated both theoretically and experimentally [80, 98]. In this paper, we present some results for a pilot-scale RD column, with a catalytic section in the middle part. This section consists either of a packed bed of catalytically active rings (see [99]) or of catalytic packing MULTIPAK [31]. The rectifying and stripping sections are filled with Intalox Metal Tower Packing. The methanol is fed just above and the hydrocarbon feed just below the catalyst section. 

Figure 10.10 demonstrates the simulated and measured concentration profiles for the pilot column with the reactive section filled with catalytically active rings. In the simulations, four components, namely, methanol, isobutene, MTBE and 1-butene, were chosen to represent the chemical system under consideration. Here, segment 1 corresponds to the reboiler. A satisfactory agreement between calculated and measured values can be clearly observed. In Fig. 10.11, the simulation results for the column packed with MULTIPAK are shown. Here, 16 components are considered, and, again, the liquid bulk composition profiles agree well with the experimental data. 

Figure 70.13 Experimental and simulated liquid distillate compositions (all 11 test runs) for the column with the reactive section filled with catalytic structured packing Montz Multipak.

The separation efficiency for the different laboratory-scale packings is considerably high (HETS between 0.33 and 0.25m), while for the industrial-type KATA-PAK -S 250.Y it is lower because of the smaller specific surface area (see Table 10.3). The laboratory-scale internals mainly differ in catalyst content. Further information on KATAPAK -S and MULTIPAK is given elsewhere (see, e.g. [105]). 

There are several possibilities of immobilising the solid catalyst in industrial CD columns on basis of trays, random and structured packings. A survey on available catalytic column internals is presented by Krishna and Taylor (2000). In this paper structured packing Montz MULTIPAK -2 filled with catalyst Amberlyst 35 WET is applied for the TAME synthesis from light gasoline from the FCC process. 

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