Open-end discharge

In the previous section, the flow of a sand-water slurry in a horizontal drum with an open-end discharge was reviewed. Slurry hold-up was found to be a function of particle size, drum speed, feed flow rate, and composition. The experimental results also showed relatively low slurry hold-up and poor radial (transverse) mixing inside the drum. To overcome these problems for the case of dry solids, an end-constriction and lifters are normally used. The effects of such additions on the slurry hold-up and mean residence times of solids and fluid phases will be discussed in the next section. 

Microstrainers. Microstrainers are rotating steel screens with extremely fine stainless steel mesh (85—170 perforations per square centimeter (13—26/in. )). The flowing Hquid enters the open end of the dmm and passes through the mesh to the effluent end. The mesh traps soHd impurities and rotates with the dmm. A wash-water spray washes the trapped soHds into a hopper for final disposal. The mesh is washed with filtered effluent discharged from jets fitted into the dmm and then exposed to uv radiation to inhibit microbial growth. The mesh is washed with chlorine water at intervals of 7 to 28 days in order to control slime growth removal efficiencies are 30—55% of the appHed BOD and 40—60% of suspended soHds. 

Ignition occnrs at the open end of the dnct. The flame propagates into the dnct nntil it reaches the flame arrester element where it is qnenched. In this case, the amonnt of heat that mnst he dissipated hy the arrester is relatively small hecanse the hot comhnstion gases discharge throngh the open end of the dnct. 

Disposal piles. Disposal piles are large-diameter (24 to 48-in.), open-ended pipes attached to the platform and extending below the surface of the water. Their main uses arc to consolidate platform discharges into one location to provide a conduit protected from wave action so that discharges can... 

The discharge end of the downcomer must project far enough into the tray liquid so that no gas bubbles can enter the open end and bypass the bubble caps. When the liquid contains no sediment, a seal pot or discharge weir is often placed around the discharge end of the downcomer to make certain that no free vapor can enter the open end. The distance between the liquid level on the loaded discharge plate and the bottom of the downcomer when no liquid is flowing is known as the downcomer liquid seal. A downcomer liquid seal, based on a perfectly level tray, in the range of to l in. is usually satisfactory. 

It should be noted that the hydrolysis reaction takes place rapidly, before full pressure is reached in the converter, even though variation of the time at full pressure is the basis for the control of the reaction. At the end of the time needed at full pressure, the steam flow into the converter is stopped, and the valve on the discharge pipe is opened. The discharge pipe extends to the bottom of the converter, so that, when the valve is opened, the pressure inside the converter forces the charge out and into a neutralizer tank, usually situated on the floor above the converter. 

Deep-well pumps of the bucket type are designed for use on non-flowing wells where the water does not stand within suction distance. Two methods are employed In the plain tube well (Fig. 6) the well pipe with open ends is sunk to the proper depth where a sufficient water-bearing stratum is penetrated. The strainer A is then lowered to bottom of the well and the well pipe drawn back far enough to expose the slotted portion. The working barrel B is then lowered into the gum packer on top of strainer and tapped firmly into place. The top of the well pipe is provided with a tee for discharge connection. The... 

However, it is not iways possible to run a pilot-plant test in order to determine the depth of cut. A well-accepted alternative approach makes use of the more sophisticated test leaf illustrated in Fig. 18-110. This test leaf is designed so that the cake and precoat are extruded axially out the open end of the leaf. The top of the retaining wall on this end of the leaf is a machined surface which serves as a support for a sharp discharge knife. This approach permits variable and known depths of cut to be made so that die minimum depth of cut may be determined. Test units are available from Betts Advanc Metal, hompoc, Calif, (805) 735-5130. 

The first option, from a falling stream, is usually used at a transfer point between conveyor belts, from under a discharging hopper or from the end of a pneumatic conveying system. Open ended scoops or shovels are unsuitable for manual sampling... 

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