Reactors Liquid immersed

A fixed-bed reactor system was employed (Figure 32.2). Each of the two reactors was charged with 38 cc of Amberlyst BD20 catalyst. Sample ports located at the exit of each reactor enabled increased acquisition of residence time data. Pressure was maintained by a back pressure control valve to maintain methanol in the liquid phase. After charging, the 1st and then 2nd reactors were connected to the pumps and filled with the reaction mixture while vapor was released from each through the top vent valve. Once each reactor was filled with liquid and emptied of vapor, the pressure regulator was connected to the output and both reactors were immersed into the water bath. 

Consider die flow conditions to one of the tubes for the SO oxidation described in Example 8-10. Replace the tube with a radial flow reactor I cm in height with an inlet diameter of 0.5 cm. The reactor is immersed in the same boUing liquid as in Example 8-10. Plot the temperature and conversion as a function of radius and catalyst weight for three different inlet temperatures, Study the behavior of thi.s reactor by varying a number of parameters, such as flow rate and gas composition. 

The studies were conducted in stainless steel tubular reactors approximately 3.8 cm in diameter and about 1200 cm3 in volume. The reactors were immersed in electrically heated fluidized solids baths. A naphtha fraction to be reformed was vaporized and heated to reaction temperature before contacting the catalyst. The reactor effluent was separated into liquid and gaseous fractions. A portion of the hydrogen-rich gaseous fraction was recycled through the reactor to simulate commercial reforming practice. The recycle gas was combined with the vaporized naphtha fraction prior to the reactor inlet. The mole ratio of recycle gas to naphtha at the reactor inlet was approximately 7 in all of the runs to be discussed here. 

Computations show (Goodwin, 1990) that this cost is much less than that for the cleaning bath reactor or for the reactor with immersible transducers. A practical problem with this reactor is that the tips are exposed to a very small fraction of the liquid, hence a very efficient method of circulation is necessary. 

Burch S.F. and McKnight J.A. "The application of maximum entropy to the processing of ultrasonic images of nuclear reactor components immersed in liquid sodium, pp249-257. Acoustical Imaging, vol. 12, Plenum Publishing Corp. (1982). 

Some microbial biomonitors have been described where the biological component is in the form of a cell suspension in a stirred reactor and the electrodes are immersed in the reactor liquid to monitor changes in parameters such as pH, PO2, or PCO2. Whilst this approach has much in common with microorganism-based sensors it is not appropriate to use the term biosensor for such devices. 

Following a LOCA, the safety systems must provide make-up for the water lost so as to maintain the reactor core immersed in liquid water. Many pressurised water reactors today rely on pumped systems and large sources of water from outside the containment to provide this make-up and cooling. These types of systems require safety grade and Seismic Category I sources of ac power and water. In the case of the APIOOO, this is done without reliance on ac power. 

Catalytic hydrogenation is typically carried out in slurry reactors, where finely dispersed catalyst particles (<100 (tm) are immersed in a dispersion of gas and liquid. It has, however, been demonstrated that continuous operation is possible, either by using trickle bed [24] or monoHth technologies [37]. Elevated pressures and temperatures are needed to have a high enough reaction rate. On the other hand, too high a temperature impairs the selectivity of the desired product, as has been demonstrated by Kuusisto et al. [23]. An overview of some feasible processes and catalysts is shown in Table 8.1. 

An appreciable increase in working area of the electrodes can be attained with porous electrodes (Section 18.4). Such electrodes are widely used in batteries, and in recent years they are also found in electrolyzers. Attempts are made to use particulate electrodes which consist of a rather thick bed of particulate electrode material into which the auxiliary electrode is immersed together with a separator. Other efforts concern fiuidized-bed reactors, where a finely divided electrode material is distributed over the full electrolyte volume by an ascending liquid or gas flow and collides continuously with special current collector electrodes (Section 18.5). 

Shaker tube reactors are commonly used for the evaluation of catalysts at elevated pressure. The liquid reactant and powdered catalyst are introduced into a metal or glass ampoule, which is sealed and pressurized to a predetermined level with the gaseous reactant. The ampoule is immersed into a thermostatted liquid and maintained at this temperature for a certain period of time while shaking. Then the reactor is opened and the reaction mixture analysed. Ampoules of ca. 10-100 cm are typically used. The usefulness of data obtained using such reactors for process scale-up is nearly zero due to poor agitation and unknown hydrodynamics in the ampoule. These reactors are, however, very useful for fast screening of catalysts. 

The reactor design in terms of ratio of the diameter of the immersion transducer to reactor diameter, liquid height, position of the transducers and characteristics of the cell plays a important role in deciding the cavitational activity distribution and hence the efficacy of sonochemical reactors for the specific application. Based on a critical analysis of the existing literature, following important design related information can be recommended ... 

The extent of immersion of the transducer in an ultrasonic horn or the extent of liquid height, which affects the extent of reflection of the incident sound waves from the liquid surface as well as the reactor bottom, also shows an optimum value [53]. 

In a Hanovia 550-watt immersion photochemical reactor (Note 1) equipped with a magnetic stirrer and water condenser (Note 2) are placed 1 1. of diethyl ether, 180 g. (1.96 moles) of bicyclo[2.2. l]hepta-2,5-diene (Note 3), and 8 g. of acetophenone. The system is flushed briefly with a stream of nitrogen and then irradiated for a,bout 36-48 hours (Note 4). After irradiation, the ether is removed by distillation through a 20-cm. Vigreux column (Note 5). The residue, a clear liquid weighing about 185 g., is distilled through a spinning-band column under reduced pressure (Note 6). Quadricyclane is obtained as a colorless liquid, b.p. 70° (200 mm.). The yield is 126-145 g. (70-80%) (Note 7). 

Packed Bubble Bed Reactor (BBR) This is a tubular flow reactor with concurrent up-flow of gas and liquid (Figure 3.11). The catalyst bed is completely immersed in a continuous liquid flow while gas rises as bubbles. Some applications of BBR are the catalytic denitrification of aqueous nitrate solutions and the hydrogenation processes. 

Most combustion processes are chain-branching, but other examples of chain-branching reactions are also found in industrial systems. Chain-branching reaction systems are potentially explosive, and for this reason great care must be taken to avoid safety hazards in dealing with them. The explosion behavior of gaseous fuels as a function of stoichiometry, temperature, and pressure has been an important research area [241]. Experimental data are typically obtained in a batch reactor, a spherical vessel immersed in a liquid bath maintained at a specific temperature. The desire to understand the explosion behavior of various... 

Figure 24. Scheme of multilamp immersion-type photochemical installation for the photocatalyzed oxidative degradation of industrial waste water [12]. A Bypass circuit. B Reactor circuit. 1 Gas-liquid mixture and injection. 2 Reservoir. 3 Pump (ceramics). 4 Water pump. 5 Heating circuit. 6 Cooling circuit, hv Medium pressure mercury lamps (Pyrex). T Thermometers. 

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