Flow Distributor System

The simulated FBAC consists of an acrylic main reactor (0.5m-H x 0.5m-W x l.Om-L), an air distributor system, particles feeding system including a feed hopper, a discharging sampler, a bag filter for capture of the elutriated fine particles and, pressure and flow rate measurement systems (Fig. 1). The air distributor system has ten air headers. An individual air header is connected with 5 air nozzles and can regulate the airflow rate. The opening ratio of the distributor is 2.1% and each nozzle has four holes for uniform air supply. To measure the pressure fluctuation at an individual air header, high frequency pressure transmitters were mounted at the approach and the exit headers of the FBAC. 

The hydraulic system consists of oil reservoir, electric motor, hydraulic pump, heat exchange for oil cooling, oil filters, oil level indicator, electric valves and flow distributors. An hydraulic plant which has been properly installed and care has been taken during the start-up phase, should enjoy long life and not need much maintenance. 

Some applications may require more sophisticated flow distributors. Shallow horizontal beds often heve such large cross-sect ions 1 flow area diet a single inlet and outlet nozzle is insufficient. For these vessels, carefully designed nozzle headers are needed to balance cbe flow to each puir of nozzles. In liquid systems, a single inlet may enter the vessel and branch into several pipes that are often perforated along their length. Such "spiders and "Chriaimas trees msy need holes, which are not necessarily uniformly spaced or sized, to provide equal flow per bed area. 

Indeed, the hot air distribution is one of the crucial points in a spray drying system design. Today, there are three types of hot air distributors which can be found in spray drying systems in the food industry, i.e., rotating air flow distributor, plug air flow distributor, and central pipe air distributor, A schematic representation of each of these systems is shown in Figure 4.4. 

Hsing et al. [66] presented simulations of two- and three-dimensional fluid flows, thermal fields, and chemical species concentrations in microreactors for the Pt-catalyzed NH3 oxidation in the T-shaped microreactor. Simulations and experiments showed good agreement and reactions were mass transfer limited. Therefore, it is not possible to obtain kinetic information, that is, details of the kinetic mechanism from the simulation data. Nevertheless, the comparison of predicted and experimental data demonstrates that it is possible to accurately predict and understand transport phenomena in microreactors, which is often difficult to obtain with macroscopic systems because of flow distributors, baffles, and turbulence. 

The solution is oxidized by contact with air in a flooded perforated tray column located in the center of the absorber. Spent dilute sulfuric acid is punned from the absorber sump to the bottom of the oxidizer and flows upward through this unit cocurrently with 1,900 scfrn of air. The oxidized absorbent overflows from the oxidizer to a distributor system, then percolates down through the absorber, which is packed with 3-in. Tellerettes. 

Adsorbent particles can be supported in one of two ways in an adsorption vessel. The first comprises a series of grids with each successively higher layer having a finer mesh. The second comprises a graded system of inert particles which may range from ceramic balls down in size to gravel. For those applications where the adsorbent may have to be removed from the bottom outlet there may be no support system but the flow distributors may, as a result, be complex. 

Semicontinuous and continuous systems are, with few exceptions, practiced in columns. Most columnar systems are semicontinuous since flow of the stream being processed must be intermpted for regeneration. Columnar installations almost always involve the process stream flowing down through a resin bed. Those that are upflow use a flow rate that either partially fluidizes the bed, or forms a packed bed against an upper porous barrier or distributor for process streams. 

The space immediately above the resin bed may or may not be filled with Hquid in downward flow systems, depending on the design. If not filled, water entering the column from the top and impinging on the upper surface of the resin bed forms hills and valleys unless the flow is dispersed over the cross-sectional area. A distributor similar to the one used to collect resin below the bed, or splash plate, is placed a short distance above the resin bed to improve the distribution of the process stream flow. 

A distributor is frequently installed at the top of the column for use during backwash. It collects water evenly and prevents resin from escaping the column should unexpected surges develop in the water flow during backwash. Columns lacking an upper distributor or screen to prevent loss of resin should have an external system to prevent resin from being lost to the drain. It is referred to as a resin trap and may consist of a porous bag that fits over the outlet pipe or a tank designed to lower the linear velocity. Resin drops to the bottom of the tank and is returned to the column when convenient. 

Pulsed beds of ac tivated carbon are used in water and wastewater treatment systems. The adsorber tank is usually a vertical cylindrical pressure vessel, with fluid distributors at top and bottom, similar to the arrangement of an ion exchanger. The column is filled with granular carbon. Fluid flow is upward, and carbon is intermittently dis-... 

The use of V-notches in a trough wall for overflow is more sensitive to leveling problems than the other designs, and for the same %- to Me-in. level tolerance produces a more severe non-uniform flow distribution. The quality of distribution from a V-notch is poor compared to the other types of trough distributor, but does have advantages in slurry systems [131]. It should not be used for critical distillation applications, but is good for heat transfer and where solids are in the system. 

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