Reactor schematic, countercurrent

Figure 7.9. Concentration profiles of reactant A in the supply phase, of reactant B and product P in the reaction phase, in cocurrent (a) and countercurrent (b) flow reactors (schematically).

There are essentially three types of coal gasifiers moving-bed or countercurrent reactors fluidized-bed or back-mixed reactors and entrained-flow or plug-flow reactors. The three types are shown schematically in Eigure 2. 

Another approach to continuous reaction chromatography is the countercurrent moving-bed chromatographic reactor (CMCR). In this type of reactor the stationary (solid) phase travels in the opposite direction to the liquid phase. In practice this is performed by introducing the stationary phase from the top of the reactor. The stationary phase flows downwards under the influence of gravity while the liquid phase is pumped upwards from the bottom. A schematic presentation of such a system is shown in Fig. 7. Depending on the adsorption characteristics of the different components, they can travel in the direction of the liquid or the solid phase resulting in their separation. 

Fig. 7. Schematic presentation of a true countercurrent moving bed chromatographic reactor. (Reprinted with permission from [151])...

Fig. 1.2. Schematic flow configurations of heat-integrated processes for coupling endothermic and exothermic reactions, (a) Countercurrent flow of process streams, (b) Cocurrent flow of the process streams in the reactor stages and heat recovery in separate circuits.

Figure 25. Equivalence of operation with periodical flow re versa and countercurrent heat exchange A) Fixed-bed reactor with periodic flow reversal, B) Temperature profiles with rapid flow reversal, C) Countercurrent reactor with catalyst at the wall D) Schematic concentration and temperature profiles m both reactors [141...

Figure 1. Schematic of a Countercurrent CO2 Selective Membrane Reactor Containing Catalyst Particles...

We have developed a one-dimensional non-isothermal model for the countercurrent WGS membrane reactor with a C02-selective membrane in the hollow-fiber configuration using air as the sweep gas. Figure 1 shows the schematic of each hollow-fiber membrane with catalyst particles in the reactor. The modeling study of the membrane reactor is based on (1) the CO2 / H2 selectivity and CO2 permeance reported by Ho [1, 2] and (2) low-temperature WGS reaction kinetics for the commercial catalyst copper oxide, zinc oxide, aluminum oxide (CuO/ZnO/ AI2O3) reported by Moe [3] and others [4]. In this modeling study, the model that we have developed has taken into account critical system parameters including temperature, pressure, feed gas flow rate, sweep gas (air) flow rate, CO2 permeance, CO2 /H2 selectivity, CO concentration, CO conversion, H2 purity, H2 recovery, CO2 concentration, membrane area, water (H20)/C0 ratio, and reaction equilibrium. 

In the fixed-bed -process, shown schematically in Fig. 11-12, soluble cobalt salts of fatty acids or naphthenates are pumped with the olefin to the top of the first reactor and flow countercurrent to the synthesis gas. One type of fixed-bed catalyst consists of 2 per cent metallic cobalt on a pumice carrier. Part of the cobalt is converted to carbonyl, leaves the reactor with the overhead product, and is replaced by the cobalt salts in the feed. A high recycle of cooled crude product to the converter mds in controlling the reaction temperature. Unreacted synthesis gas leaving the top of the reactor is coo ed, passed through a packed tower countercurrent to the olefin feed to remove cobalt carbonyl, and recycled to the reactor. 

Ideally, purely from a reactor efficiency point of view, the ideal three-phase reactor would be a countercurrent one (shown schematically in Figure 6.3a), in which gas and liquid (with species A and B, respectively) enter from opposite directions, and where there is higher concentration of A (near gas inlet), one would have a depleted liquid stream (lower concentration of B) and vice versa at the other end. The catalyst particles would be suspended in slurry phase, and with this countercurrent trick, one would ensure relatively uniform rate on the catalyst particles no matter what their locations in the vessel. The ideal contacting flow pattern involves the countercurrent movement of gas and liquid (slurry) phases in a plug flow manner. 

Figure 1.14 Schematic diagram showing tubular membrane reactors (a) catalyst on tube side with concurrent flow (b) catalyst on shell side with countercurrent flow.

When the reaction is exothermic, a common approach to preheating the feed Stream is to use a feed/product (F/P) heat exchanger. This arrangement is shown schematically in Figure 8-13. The feed is heated by exchanging it against the hott Stream leaving the reactor. Flow of the two Streams is countercurrent... 

---