Backpressure valves

For now, we assume that all operating conditions are known. This specifically includes Pout and Tout, which correspond to conditions within the vessel. There may be a backpressure valve at the reactor exit, but it is ignored for the purposes of the design equations. Suppose also that the inlet concentrations ajn,bm,..., volumetric flow rate and working volume V are all known. Then... 

Membrane Flux Performance for the Hollow Fiber Units. Figures 3a and 3b show the results of a cell separation pilot scale run in which transmembrane pressure was maintained constant at 4.0 psi and linear velocity through the fibers was maintained at 1.0 m/sec (100 1pm). Transmembrane pressure was controlled with a backpressure valve on the combined permeates from the hollow fibers. Note that the flux vs. concentration curve for this run does not conform to theoretical predictions for concentration polarization (see Figure 3b). Flux on this semi-log plot does not decline linearly, but, rather, shows two phases of fouling. The initial phase (approximately 20 minutes in duration) is characterized by a rapid loss in flux, while the second stage (approximately 90 minutes in duration) is more gradual. The initially rapid decline caused an unacceptably low average flux of 10 l/m -hr. 

Gas and liquid are mixed before entering the reactor bed in a gas-liquid chamber 17 at the inlet of the reactor. The gas leaving the reactor flows through a condenser 18, where evaporated solvent is condensed, and then to the gas-liquid separator 19. The condensed solvent is collected in a separate buffer vessel 20 and returned to the reactor if necessary, the gas leaves the system through a backpressure valve controlling the pressure in the system. The volumetric flow of the effluent gas is measured with a gas meter 21. 

When applying chemicals, it is important to establish safeguards to prevent siphoning of too much chemical during unusual vacuum conditions. Examples of siphoning controls are three-way valves, backpressure valves, or nonflooded suction-type installations. 

FIGURE 9.12 Dielectric barrier discharge configuration and experimental setup MFC is the mass flow controller, and BPV is the backpressure valve [211]. 

FIGURE 5.7. Left BatchSYNTH. Right FlowSYNTH, A Backpressure valve, B Reactor outlet, C Column-stirrer motor, D Water-cooled jacket, E Reactor cavity, F Control terminal, G High-pressure pump, and H Water chiller. (Reproduced with kind permission from Milestone Manufacturer (www.milestonesrl.com)). 

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