Side reactor

JM proprietary methanol synthesis catalyst is packed in the shell side of the reactor. Reaction heat is recovered and used to efficiently generate steam in the tube side. Reactor effluent gas is cooled to condense the crude methanol. The crude methanol is separated in a separator (10). The unreacted gas is circulated for further conversion. A purge is taken from the recycling gas used as fuels in the reformer (3). 

The very first NS with LMC (design 645) was equipped with two-reactor Power Reactor Installation (PRI). After the port-side-reactor accident during the second fuel lifetime (1968), the NS was kept afloat for some period. Then, after filling of free reactor cavities and the whole Reactor Compartment (RC) with preservative agents, the NS was dumped in the Kara Sea close to the Novaya Zemlia (New Land) archipelago at 50-m depth (1981). Some characteristics of NS, design 645, are given in Table 2. 

Distillation columns with multiple conventional side reactors were first suggested by Schoenmakers and Buehler German Chem. Eng., 5, 292 (1982)] and have the potential to accommodate gas-phase reactions, highly exo- or endothermic reactions, catalyst deactivation, and operating conditions ontside the normal range snitable for distillation (e.g., short contact times, high temperatnre and pressure, etc). Krishna (chap. 7 in Sundmacher and Kienle, eds.. Reactive Distillation, Wiley-VCH, 2003). 

The fluid-bed process differs from the fixed-bed and moving-bed processes, insofar as the powdered catalyst is circulated essentially as a fluid with the feedstock. The several fluid catalytic cracking processes in use differ primarily in mechanical design. Side-by-side reactor-regenerator construction along with unitary vessel construction (the reactor either above or below the regenerator) are the two main mechanical variations. 

Figure 3 Selected schemes for the production of A (F - feed, S - solvent, SR - solvent removed), a) Reactor-separator-recycle system w/ four zones and solvent removal, b) Partially integrated process w/ three zones and side reactors, c) Fully integrated process w/ four zones, distributed reaction and solvent removal, d) Fully integrated scheme w/ three zones and distributed reaction.

Concerning the level of integration, classical flowsheet-integrated processes as reactor-separator-recycle systems (Fig. 3a) and the use of side reactors ( Hashimoto process . 

The design of pipeline, coil, and heat exchanger (reaction on tube or shell side) reactors and their optimization are illustrated and discussed. 

If a development engineer has to design an industrial column purely on the basis of miniplant experiments, he has to maintain not only the separation performance but also the ratio of separation performance/reactor performance so that main and secondary reactions proceed to a comparable extent in the industrial-scale reaction column. One way in which this can be achieved is in terms of construction by separating reaction and product separation from one another both in miniplant tests and on an industrial scale. This is possible, for example, when the reaction is carried out in the presence of a heterogeneous catalyst in the downcoming stream or with side reactors at the column. An alternative is to use structured packing with well-defined paths for the liquid flow. This problem has not yet been solved, the main reason being the lack of reference columns on an industrial scale. As we see it, the way forward is either ... 

One approach to solving the incompatibility in the requirements of reaction (high liquid or catalyst hold-up) and separation (high vapor-Uquid interfacial area) is to employ the side-reactor or external reactor concept [51], Fig. 7.21. The liquid is withdrawn from stage j, passes through the side reactor, and is fed back to the column at stage k. The amount of liquid pumped around, Igp = Rp Lj, where RpA is the pump-around ratio. By providing adequate residence time for reaction, equilibrium conversion is achieved in the side reactor. 

For the production of MeOAc, let us compare the RD column with a distillation column with either three or five side reactors. Fig. 7.22. The side-reactor could be a tubular reactor, packed with, say, Amberlyst-15 for acid catalysis. It could also be a homogeneous liquid-phase tubular reactor, catalyzed by H2SO4. Clearly the location... 

Fig. 7.22 Alternative configurations for MeOAc production a) RD column b) distillation column A/ith three side reactors c) distillation column A/ith five side reactors...

The (non-reactive) distillation columns linked to the side reactors can be much smaller in diameter than the RD column and no specially designed trays (e. g., with higher weirs or additional sumps) or proprietary devices such as Katapak-S are necessary. The side-reactor concept is particularly attractive when the conversion requirements are not as stringent as assumed in the MeOAc case study above. 

Many of the conflicting hardware issues can be resolved by de-coupling the separation and reaction function by employing the side-reactor concept. 

K. Jakobsson, A. Pyhalathi, S. Pakkanen, K. Keskinen, J. Aittamaa, Modelling of a Configuration Combining Distillation and Reaction in a Side-Reactor, Proc. 2nd Int. Symp. on Multifunctional Reactors (ISMR-2), Nuremberg, Germany, 2001. 

The heat-storage and heat-release reactions occur at different pressure levels. The low-temperature side has a higher reaction equilibrium pressure. The CHP, as studied earlier, operates as a batch system with a heat-storing step followed by a heat-releasing step. For example, hydration and carbonation reactions can be used on the high-temperature (600 to 1200 K) side reactor. Evaporation and condensation of the reactant media are often used on the low-temperature (273 to 523 K) side reactor. 

Figure 15.12 Operation principle of the chemical heat pump H—high-temperature side reactor, L—low-temperature side reactor).

In the heat-storing step, the heat Qu is stored in the form of thermochemical energy by decomposition of the reactant AC(s) in the high-temperature side reactor. The released gas C(g) flows into the low-temperature side reactor due to a pressure difference maintained between the two reactors. The gas C(g) reacts with the reactant B(s), releasing low-temperature heat Ql. As long as the reactant A(s) is separated from the gas C(g), the reaction heat can be stored for any period in the form of chemical energy. 

In the heat-releasing step, the gas C(g) flows from the low-temperature side reactor to the high-temperature side reactor by opening a valve (Figure 15.12) due to the pressure difference between the reactors. The exothermic reaction of the reactant A(s) at a high-temperature level with the gas C(g) takes place in the high-temperature side reactor. The low-temperature side reactor stores the low-temperature heat Ql or is cooled down by releasing its decomposition heat when it is insulated. 

The coimectivity rules, however, imposed some configuration limitations (i) heat integration over volume elements is not considered (i.e. carrying heat from high temperature to low temperature elements) ( ) side reactors are not present and (in) no parallel structures are considered. 

Answer. Reduction in the number of reactive trays, more uneven distribution of catalyst and identification of suitable spots for side reactors. 

The standard CCR Platforming process has a single reactor stack design as shown in Figure 8. However, CCR Platforming units have also been designed as a combination of stacked and single side-by-side reactors. The reactors are... 

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