Single pass reactor

Figure 3a Maximum conversion in a single pass reactor and the initial rate (no TCE) vs. literature second order hydroxyl rate constants. (Same symbols as (2a)).

DeNeal, D.L., Historical Events Single Pass Reactors and Fuels Fabrication, DUN-6888, Douglas United Nuclear Inc., Richland, WA, 1970. 

Consider the comparison between an adiabatic RFR and a single-pass reactor to treat a feed with carbon monoxide (with data available in Table 1 and performance depicted in Fig. 3). Invoking the... 

Fig. 3 Comparison of RFR (solid lines) with single-pass reactor (dashed lines). (A) the maximum temperature within the reactor and (B) the ignited length of the reactor. (Data taken from the numerical model in Ref f)...

For systems where the adiabatic temperature rise is low (as is the case considered here) the thermal spikes introduced by the flow reversals do not dramatically affect the reactor performance. However, the concentration of feed streams to such treatment reactors can fluctuate to a high level which can result in a high temperature thermal spike developing within the reactor. Pinjala, Chen, and Luss characterized this dynamic response and showed that reactor runaway could occur within the single-pass reactor. Their work is directly applicable to the RFR as the forced oscillations in the gas flow direction can result in a thermal spike formation at the beginning of each half cycle. Thus, there is a need to understand thermal stability within these systems. Further complicating the matter is the fact that the temperature spikes are very narrow and are thus difficult to detect using thermocouples or other sensors imbedded within the reactor. 

Photocatalytic degradation of Reactive Orange 84(RO 84) in dye-house effluent using single pass reactor... 

Keywords Reactive Orange 84 Degradation Photocatalysis Single-pass reactor. 

The single pass reactor fabricated mainly using perspex hose (dia. 4.5 ) and PVC block, houses a 400 W water cooled Hg lamp, has facilities for stirring, aerating and irradiating the contents of the reactor, a reservoir of the dye stock solution (influent) which is admitted into the reactor at a chosen rate, a UF membrane located in a PVC block assembly for filtering the catalyst and a stopcock attached to it for collecting the catalyst-free treated... 

Fig. 2 Photodegradation of RO 84 Removal of COD and its maintenance at a lower level using single pass reactor.

Fig. 3 Influence of flow-rate on the efficiency of COD removal using a single pass reactor.

At the highest flow rate (5.4 ml min ) about 1.3 1 treated water is collected in 4h having slight color and 84% lesser COD compared to that of influent. At flow rates S 3.5 ml min" the dye molecule appears to have sufficient residence time in contact with the catalyst and therefore lead to complete color removal and significant COD reduction. It may be noted that the applied flow rates are not satisfactory for any practical application. There is need to enhance the rate of COD removal in the single pass reactor so as to be compatible with the desirable flow rates for collecting the treated water. 

Struis and Stuck [6.12] have evaluated the application of membrane reactors for methanol synthesis using methanol permselective Nafion membranes. In their design calculations they utilize kinetic and membrane permeation data measured in their laboratory. They estimate that with 10 im thin membrane under methanol synthesis plant technically relevant conditions (T = 200 C, P = 40 bar, GHSV = 5000 h ), the single pass reactor yield improves by 40 %, and that the additional costs for the membrane materials correspond only to two production months. The ability of the Nafion membranes to withstand such conditions for prolonged periods still remains, however, questionable. 

The accumulation and retention of biomass lends itself readily to the employment of continuous single pass reactors such as plug-flow or fluidized-bed reactors. When high quantities of biomass are retained, greater total quantities of nutrients may be delivered and greater quantities of waste products may be removed per unit time. Any mechanism that can be offered to retain the cells in high concentrations, deliver the nutrients rapidly, and remove waste products should offer a highly efficient reactor. 

Catalytic WO can be considered nowadays as a mature technology. Nevertheless, due to the variety of wastewater that has to be treated, one type of catalyst cannot fulfill all the needs. Therefore the catalyst must be tailored for each particular application and made of inexpensive materials. In order to reduce leaching, the catalytically active compounds have to be incorporated into a lattice of catalyst support. It would be advantageous to design a catalyst for treatment in single-pass reactors that had a minimum lifetime of over 500 h. 

Pletcher, D., Whyte, L, Walsh, F.C., and Millington, P.J. (1991) Reticulated vitreous carbon cathodes for metal ions removal from process streams. Part III Studies of a single pass reactor. J. Appl. Electrochem., 21, 659-666. 

The phosphate covered grains are removed from the bottom of the bed and replaced intermittently by fresh sand grains. In most studies reported in the literature (Morse et al., 1998), the phosphate removal efficiency of a single pass reactor, even at industrial scale, has an order of magnitude of only 50%. Let us recall that the pellet reactor efficiency depends not only on pH but also on the hydrodynamical conditions (Montastruc et al., 2002a). 

Fig. U7 Definition sketch showing e amm modes of operation for reactors, (a) Simple batch reactor, (b) Single-pass reactor, (c) tetcb-mlfEylatioii reactor, (d) Cascade of n identical reactors, PFR, plug flow reactor CSTR. oootuiiowl r stirred tank reactor.

Consider the general case of a single-pass reactor, where a steady volumetric Dow rate Q of electrolyte passes through the reactor. The inlet concentration of reactant qiMp is reduced to the outlet. Both and C(out] time-... 

In practice, the fractional conversion over a single-pass reactor is often limited, e.g. if the flow rate is reduced in an attempt to tachicvcoa, higher... 

Single-pass reactor cooling during reactor shutdowns. ... 

Table 5 Economic Impact of Single-Pass Reactor Conversion (Plus Heat Integration) on Process Economics (All EAOC cost figures in millions.)...

Whenever one of the reactants differs in phase from products and other reactants, it may be automatically added at the same rate as it is consumed, by controlling its inventory within the reactor. Figure 10.7 shows single-pass reactors with either a liquid or a gas as the manipulated flow. 

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