Counter-flow heat exchanger-reactors

Figure 3.11 Photograph of the multi-plate stack reactor, originally designed as a counter-flow heat exchanger this type of reactor was also used for periodic operation [13].

P 68] No detailed experimental protocol was given [61, 62,142,143]. Two reactant streams, the solution of the reactant in hexane and concentrated sulfuric acid, were fed separately in a specially designed micro reactor by pumping action. There, a bilayer was formed initially, potentially decomposed to a dispersion, and led to rapid mass transfer between the phases. From this point, temperature was controlled by counter-flow heat exchange between the reaction channel and surrounding heat-transfer channel. The reaction was typically carried out at temperatures from 0 to 50 °C and using residence times of only a few seconds. If needed, a delay loop of... 

The recuperator uses heat from the turbine exhaust on the recuperator hot side to preheat the gas in the recuperator cold side returning to the reactor, increasing cycle efficiency. The hot and cold sides of the recuperator are each 20 sub-volume pipes that are coupled via a heat structure. The heat structure utilizes a staggered coupling scheme developed specifically for counter flow heat exchangers that is fully described in Reference 12-20. Five separate heat structures are used a staggered mesh connecting the two components, a hot side end volume heat correction, a cold side end volume heat correction, a hot side heat balance structure, and a cold side heat balance structure as described in References 12-20 and 12-5. 

Integrated reactors One type of integrated reactor is micro structured heat exchanger/reactor concepts, which may work as cross- or counter-flow reactors. Another type couples endothermic and exothermic reactions in two separate flow paths normally operated in the co-current mode. Both reactor types are designed as prototype components of future fuel processors for mobile applications. 

Copper and aluminum are alternative metals for low-temperature processes such as alcohol reforming [22, 85] and gas purification. The higher heat conductivity of these metals (401 and 236 W m-1 K-1), respectively, compared with stainless steel (ca. 15 W nf1 KT1) makes them attractive, in case isothermal conditions are required, which may well be the case for evaporators or reactors with heat-exchanging capabilities. On the other hand, the efficiency of small-scale counter-flow heat... 

Fig. 11.14. Process flow sheet of cyclohexane/benzene heat pump using hydrogen permeable membranes Rdit and R/rdehydrogenation and hydrogenation reactors C, compressors T, turbine HE, heat exchangers CHE, counter-current heat exchangers P, liquid pump M, hydrogen membranes. Reproduced from Cacciola et al. [133] with permission.

Counter Current Heat Exchangers in Plug Flow Reactors... 

The EB entering the styrene plant is generally heated to the threshold cracking temperature (about 1100°F) in a heat exchanger The counter flow in the exchanger is the effluent from the second stage reactor, as shown... 

Figure 17.11. Types of contactors for reacting gases with liquids many of these also are suitable for reacting immiscible liquids. Tanks (a) with a gas entraining impeller (b) with baffled impellers (c) with a draft tube (d) with gas input through a rotating hollow shaft, (e) Venturi mixer for rapid reactions, (f) Self-priming turbine pump as a mixer-reactor, (g) Multispray chamber. Towers (h) parallel flow falling film (i) spray tower with gas as continuous phase (j) parallel flow packed tower (k) counter flow tray tower. (1) A doublepipe heat exchanger used as a tubular reactor.

The mixture of gas and carbon black leaving the reactor is cooled to temperatures of 250-350 °C in heat exchangers by counter flowing combustion air and then conducted into the collecting system. 

Most of the simulators allow heat input or removal from a plug-flow reactor. Heat transfer can be with a constant wall temperature (as encountered in a fired tube, steam-jacketed pipe, or immersed coil) or with counter-current flow of a utility stream (as in a heat exchanger tube or jacketed pipe with cooling water). 

The water cooled tubular reactor (WCTR) represents the optimal solution for the etherification because it is the best compromise between kinetics and thermodynamics [7]. The Snamprogetti (now Saipem) WCTR (Figure 11.5) is a bundle-type heat exchanger with the catalyst in the tube side and the tempered cooling water flowing co-current or counter-current in the shell side. The catalyst is self-supporting in the bottom shell of the reactor, in the tubes and above the upper tube sheet. 

The reformate left the reformer with a temperature of 814 °C and entered a zinc oxide trap. However, this would he not feasible in a practical system, because zinc oxide adsorbent materials cannot tolerate temperatures exceeding 450 °C. The reformate, which was cooled to 440 °C in heat-exchanger E-2 was then passed to the water-gas shift reactor. This reactor was cooled by steam generation at 15-bar pressure and a temperature of200 °C in a counternoble metal based rhenium/alumina catalyst at the inlet section followed by a copper/zinc oxide catalyst at the outlet section. Despite the fact that a water-gas shift catalyst of fairly low activity had been chosen for the... 

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