Reactor counter-flow

The reducing gas is distributed in reactor 4 by an ahoy grid, passes through the fluid bed, then exits the reactor via cyclones. The gas passes through reactors 3 and 2 so that a counter flow between gas and soHds is estabUshed. The spent reducing gas is scmbbed to remove dust and water vapor. Part of the cleaned top gas is recycled and the remainder is used as fuel. 

Reactor 6 [R 6] Counter-flow Multi-plate Stack Micro Reactor... 

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].

Reactor type Multi-plate-stack with counter-flow guidance Total number of reaction platelets 6 10... 

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... 

In advance, comparative fixed-bed measurements were undertaken. It was ensured that the performance of a plug-flow operation with both flows having the same direction is superior to trickle-bed operation, using counter-flow instead. The plug flow was assumed to model the slug-flow behavior in the micro reactor. 

FlameMaster v3.3 A C+ + Computer Program for OD Combustion and ID Laminar Flame Calculations. FlameMaster was developed by H. Pitsch. The code includes homogeneous reactor or plug flow reactors, steady counter-flow diffusion flames with potential flow or plug flow boundary conditions, freely propagating premixed flames, and the steady and unsteady flamelet equations. More information can be obtained from http //www.stanford.edu/group/pitsch/Downloads.htm. 

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... 

The R D requirement exists solely in the production of synthesis gas from wood, since the catalytic production of methanol is well developed. The vertical shaft counter flow reactor developed by Union Carbide for municipal waste... 

Polycrystalline ZnSe nanoparticles were synthesized from Me2Zn NEts and H2Se gas diluted in H2 [120] using a flexible vapor-phase technique [121]. In a counter-flow jet reactor (CJR) the vapors of Me2Zn NEts and H2Se react to form nanoparticles of ZnSe. This method provides a direct vapor-phase route for nanoparticles preparation. 

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.

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. 

Tonkovich et al. [123] claimed a 90% size reduction due to the introduction of micro channel systems into their device, which made use of the hydrogen off-gas of the fuel cell anode burnt in monoliths at palladium catalyst to deliver the energy for the fuel evaporation. A metallic nickel foam 0.63 cm high was etched and impregnated with palladium to act as a reactor for the anode effluent It was attached to a micro structured device consisting of liquid feed supply channels and outlet channels for the vapor, the latter flowing counter-flow to the anode effluent... 

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... 

Counter-current moving bed In this reactor solids flow is downward with the oxide concentration C° at the top of the 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. 

The simulated moving bed reactor (SMBR) based on the simulated moving bed (SMB) process is a practical alternative for implementing counter-current continuous reactors. Counter-current movement of the phases is simulated by sequentially switching the inlet and outlet ports located between the columns in direction of the liquid flow (Fig. 8.4). As with the SMB process, two different concepts are known to realize the counter-current flow. One is based on switching the ports and the other on the movement of columns. However, both require elaborate process control concepts to realize the movement. Owing to the periodical changes of the set-up the pro-... 

Complete membrane systems can be operated in a variety of modes with e.g. CO- or counter flow of feed (high pressure side) and permeate (low pressure side) streams and with membrane modules coupled in different ways. Permeation and separation in these complex engineering systems will not be treated in this chapter. Heat and mass transfer limitations on the gas-membrane surfaces or interfaces can be important with high fluxes and/or strongly adsorbing gases as well as in membrane reactors. These effects will not be treated explicitly but are introduced in experimental results, e.g., by variation of sweep rates of permeated gases. 

Equipment consists of four externally heated, screw-fed, horizontal reactors positioned vertically one above another. The reactors are made of 309 Nb stainless steel, and the screw of Inconel and Illium R. Solids flow through the four reactors in series. In the first reactor, counterflowing air at 650 to 675°C removes residual H2O and COj. Anhydrous HF vapor enters the fourth reactor and flows counter to the solids through the fourth reactor held at 566 C, the third at 370°C, and the second at 260°C, In this way, ThOj can be converted completely to ThF, the highly exothermic reaction can be controlled and most of the HF can be reacted. However, the process was usually operated to produce 70 w/o aqueous hydrofluoric acid, which was sold as a by-product. 

With regard to other significant factors, oxygen transfer can be singled out as of paramount importance. To enhance this transport step, we operated the spiral wound reactor counter-currently. In other words, a special provision was incorporated into the reactor design to allow flow of pure oxygen countercurrent... 

In order to operate the reaction continuously for a long time, both solid and gas must be continuously introduced to the reactor. There are three types of continuous reactor counter-current (c, d), co-current (e, f), and cross-current (g), depending on the flow direction of solid and gas, as shown in Figure 14.14. A fluidized bed is the most sophisticated method of solid gas reaction, in which the temperature is well controlled, and the solid can effectively contact with the gas. However, caution must be paid to maintain continuous fluidization and not to block the flow system. Continuous flow (h) and batch (i) type reactors are illustrated in Figure 14.14. 

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