Reactor components

V. N. Shah and P. E. MacDonald, Mging andEfe Extension ofMajorEight Water Reactor Components, Elsevier, Amsterdam, the Netherlands, 1993. 

Glass-lined reactor systems ate used occasionally for halogenated resins to prevent corrosion of the reactor components. Copper and brass fitting should be avoided due to the significant induence on resin cute characteristics. 

Zirconium alloys have been much less thoroughly studied than titanium alloys. The main application of interest has been for nuclear reactor components where good corrosion resistance combined with a low neutron capture cross-section has been required. Corrosion fatigue crack growth in these alloys in high temperature (260-290°C) aqueous environments typical of... 

Many other, less obvious physical consequences of miniaturization are a result of the scaling behavior of the governing physical laws, which are usually assumed to be the common macroscopic descriptions of flow, heat and mass transfer [3,107]. There are, however, a few cases where the usual continuum descriptions cease to be valid, which are discussed in Chapter 2. When the size of reaction channels or other generic micro-reactor components decreases, the surface-to-volume ratio increases and the mean distance of the specific fluid volume to the reactor walls or to the domain of a second fluid is reduced. As a consequence, the exchange of heat and matter either with the channel walls or with a second fluid is enhanced. 

Figure 1.27 Standardized fluidic backbone for connecting micro-reactor components from different suppliers, yielding a small, compact micro-plant with multiple functions.

Accordingly, serious commercially oriented attempts are currently being made to develop special gas-phase micro and mini reactors for reformer technology [91, 247-259], This is a complex task since the reaction step itself, hydrogen formation, covers several individual processes. Additionally, heat exchangers are required to optimize the energy balance and the use of liquid reactants demands micro evaporators [254, 260, 261], Moreover, further systems are required to reduce the CO content to a level that is no longer poisonous for a fuel cell. Overall, three to six micro-reactor components are typically needed to construct a complete, ready-to-use micro-reformer system. 

Figure 10 Real-time plot of reactor component concentrations in catalytic hydrogenation step illustrating early detection of baseline upset by on-line micro-HPLC.

In a chemical reactor, components in the inlet streams are consumed and new components, not necessarily in the inlet streams, are formed. The components formed cannot be shown as split-fractions of the inlet flows and must therefore be shown as pseudo fresh-feeds. 

Enhancement of CHF subcooled water flow boiling was sought to improve the thermal hydraulic design of thermonuclear fusion reactor components. Experimental study was carried out by Celata et al. (1994b), who used two SS-304 test sections of inside diameters 0.6 and 0.8 cm (0.24 and 0.31 in.). Compared with smooth channels, an increase of the CHF up to 50% was reported. Weisman et al. (1994) suggested a phenomenological model for CHF in tubes containing twisted tapes. 

The liquid effluent, which consists of water from the evaporator/crystallizer used to produce the solid filter cake produced by the brine-recovery operation, should not pose a significant hazard to human health or to the environment. While the evaporator/crystallizer system has not been tested yet, the composition of the water and solid filter cake can be readily determined from an analysis of the SCWO liquid effluent. As shown in Table 5-10, the liquid effluent is essentially free of organics. The source of the chromium and nickel that were found in some of the effluents is generally believed to be corrosion products from the SCWO reactor components. These elevated levels of metals indicate that the solid filter cake will need to be treated (e.g., by stabilization) prior to disposal in a hazardous waste landfill. 7... 

If a colleague reports that Q — 0.2 C o in the exit stream of a plug flow reactor,what can you say about the concentration of the other reactor components. A, R, T, and U in the exit stream ... 

Neutralizing acids created during processing can cause the formation of salts that can plug reactor components. 

T he unique properties of polymers make them desirable for use in A space vehicles and apparatus, as well as in nuclear reactor components and auxiliaries. In both applications intense radiation fields can be encountered routinely or occasionally. Several books have been written about the effects of radiation on polymers (I, 2, 4, 5) in general, the effects of high intensity radiation have been measured by exposing the polymer to a given amount of radiation followed by testing of properties later, outside the radiation field. 

Reactor Component Development — Corrosion of heat-transport tubing — Growth of passive oxides — Hydrogen embrittlement — Surface chloride contamination... 

As a cheap, recyclable construction material for micro reactors with sufficient short-term chemical resistance, polymers were explicitly mentioned. A further argument for the use of polymers is that for this material flexible computer-aided rapid prototyping methods are available in order to produce reactor components of complex shapes at moderate cost. The low thermal stability of polymers, however, demands advanced heating concepts when carrying out high-temperature reactions. 

In Chapter 2 (Section 2.9.2) the steady-state design of a reactor-stripper process was studied. Now we investigate the dynamic controllability of this process. The dynamic model of the reactor is the same as Eqs. (3.9)—(3.11) except there is a second stream entering the reactor, the recycle stream D (kmol/s) from the column with composition. Vj) (mole fraction A). The reactor effluent is F (kmol/s) with composition z (mole fraction A). The reactor component and energy balances are ... 

An initial charge of component A (5 m3 with concentration 0.5 kmol/m3) is placed in a 7.5-m3 reactor. Component B is fed into the reactor at a flowrate FU) (m3/min), which can be a function of time. The initial concentration of B in the reactor is zero, but the concentration builds up with time as pure B is fed (CBo = 5 kmol/m3). Table 4.1 gives the values of the kinetic and process parameters. 

Levels of many trace elements in Illinois No. 6 and Pittsburgh No. 8 coals were significantly reduced by treatments with molten caustic mixtures or aqueous alkali solutions, followed by washing with acid. Treating run-of-mine Illinois No. 6 coal with aqueous Na2C03 at elevated temperatures and pressures and washing the product coal subsequently with acid reduced Mn, Pb, and Zn concentrations by 75% or more, while levels of Cd and Ni were reduced by lesser amounts. In one of these samples, substantial reductions in levels of Ba, Cr, Rb, and Sr were also observed. Coals which were treated with molten NaOH/KOH mixtures at atmospheric pressure showed substantial reductions 1n concentrations of As, Cd, Hg, Pb, Rb, Se, Sr, and Zn. The amounts of several elements, such as Cr, Cu, and Ni, were elevated in some of the treated coals, but this can be attributed to corrosion of reactor components. 

Corrosion of reactor components during chenical coal cleaning can significantly elevate levels of various trace elements. ... 

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