Sprayers cross-flow

The collection of particles is achieved in a countercurrent flow between the water droplets and the particulates. In a cyclonic scrubber, water is injected into the cyclone chamber from sprayers located along the central axis, as shown in Fig. 7.19. The water droplets capture particles mainly in the cross-flow motion and are thrown to the wall by centrifugal force, forming a layer of slurry flow moving downward to the outlet at the bottom of the cyclone. Another type of scrubber employs a venturi, as shown in Fig. 7.20. The velocity of the gas-solid suspension flow is accelerated to a maximum value at the venturi throat. The inlet of the water spray is located just before the venturi throat so that the maximum difference in velocity between droplets and particles is obtained to achieve higher collection efficiency by inertial impaction. A venturi scrubber is usually operated with a particle collector such as a settling chamber or cyclone for slurry collection. 

Table 3.8 summarises the deposition of spray on soil surface underneath apple trees in orchards. When spraying apple trees in full leaf, spray deposition on the ground is on average 25% (18-35%), (Heer and Schut, 1986 Crum and de Heer, 1991 Porskamp et al., 1994a, 1994/ Ganzelmeier and Osteroth, 1994 Heijne et al., 1995). Spray deposition on the soil is not significantly different between axial and cross-flow sprayers, but tunnel sprayers (Zande et al., 1998) can decrease soil deposition by 50%. When trees are not in leaf, spray... 

The short length of pipe in Fig. 7.24 is used on a sprayer. The pipe and hose both have cross-sectional areas of lin The flow velocity is 200 ft/s. The pressure as measured at the flanged joint is 30 psig. 

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