Impingement separators Efficiencies

Katz (R-16) also siwdied wave-plate impingement separators (Fig. 14-Il0b) made up of 90° formed arcs with an 11.1-mm (0.44-iu) radius auda 3.8-mm (0.15-iu) clearance between sheets. The pressure drop is a function of system geometiy. The pressure drop for Katz s system and collection efficiency for seven waves are shown in Fig. 14-111. Katz used the Souders-Brown expression to define a design velocity for the gas between the waves ... 

There are many baffle type impingement separators. The efficiency of operation for entrainment is entirely a function of the contacting action inside the particular unit. There are no general performance equations which will predict performance for this type of unit therefore manufacturers performance data and recommendations should be used. A few of the many available units are shown in Figures 4-28 to 4-31. Many use the Chevron-style verdcal plates as shown in Figures 4-17A and 4-30. 

Impingement separators, 246, 257 Chevron style, 248, 255 Efficiencies, 246 Knitted wire mesh, 246 York-vane efficiencies, 248 Inertial centrifugal separators, 266, 268 Kinetic energy, pump system, 187 Lamella plate classifiers, 239 Line sizing work sheet, 107... 

Tightly packed fiber bed mist eliminators are another option for impingement separations. These devices were developed by the Monsanto Company for sulfuric acid plant mist applications, but they are now also available fiom various companies. Their main advantage is to allow efficient removal of particles down to the 0.1-1 pm range. These veiy small particles are not separated by having greater mommtum than the vapor or gas, but by the random Brownian movement or random diffiision. The particles diffuse to die fibrn-surface in the very densely packed beds. Brownian movement actually increases as particle size decreases, improving the separation of veiy small particles. 

The efficiency of this type of unit varies, and is a function of the effectiveness of the impingement baffling arrangement. About 70% of separator applications can use the line-type unit the other 30% require the vessel construction. The preference of the designer and problems of the plant operator are important in the final selection of a unit to fit a separation application. 

Sizing, 451, 453, 455, 459, 462 Sonic flow, 461 Types, illustrations, 411-421 Rupture disk, liquids, 462, 466 Rupture disk/pressure-relief valves combination, 463 Safely relief valve, 400 See Relief valve Safety valve, 400, 434 Safety, vacuum, 343 Scale-up, mixing, 312, 314—316 Design procedure, 316-318 Schedules/summaries Equipment, 30, 31 Lines, 23, 24 Screen particle size, 225 Scrubber, spray, 269, 270 Impingement, 269, 272 Separator applications, liquid particles, 235 Liquid particles, 235 Separator selection, 224, 225 Comparison chart, 230 Efficiency, 231... 

The device resembles a cylindrical differential mobility analyzer (DMA) in that a sample flow is introduced around the periphery of the annulus between two concentric cylinders, and charged particles migrate inward towards the inner cylinder in the presence of a radial electric field. Instead of being transmitted to an outlet flow, the sample is collected onto a Nichrome filament located on the inner cylinder. The primary benefit of this mode of size-resolved sampling, as opposed to aerodynamic separation into a vacuum, is that chemical ionization of the vapor molecules is feasible. Because there is no outlet aerosol flow, the collection efficiency is determined by desorption of the particles from the filament, chemical ionization of the vapor, separation in a mobility drift cell, and continuous measurement of the current produced when the ions impinge on a Faraday plate. 

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