Automatic gravity filters

The raw water, enriched with flocculant chemicals, flows into the bottom part of the reaction tank, causing an upward spiral current. The settled matter in the form of a sludge is periodically removed from the reaction tank by means of a ring conduit placed near the bottom of the settling tank. The pre-clarifled water then flows down into the automatic gravity filter from the top of the water surface level of the reaction tank. By its own head the water moves down through the Alter layer and out to service. 

Automatic gravity sand filter inside the reaction tank... 

The process centers on a fixed-bed downflow reactor that allows catalyst replacement without causing any interruption in the operation of the unit (Figure 9-28). Feedstock is introduced to the process via a filter (backwash, automatic) after which hydrogen and recycle gas are added to the feedstock stream which is then heated to reactor temperature by means of feed-effluent heat exchangers whereupon the feed stream passes down through the reactor in trickle flow. Sulfur removal is excellent (Table 9-18), and substantial reductions in the vanadium content and asphaltenes content are also noted. In addition, a marked increase occurs in the API gravity, and the viscosity is reduced considerably. 

If the material to be removed is dust, the self-cleaning bypass filter with automatic blowback constitutes a potential solution, whereas in other instances, cyclone separators should be considered. In the former device (Figure 3.5), the process stream enters tangentially to provide a swirling action, and the cleaned sample is taken near the center. Transportation lag can be kept to less than 1 minute, and the unit is applicable to both gas and liquid samples. This type of centrifuge can also separate streams by gravity into their aqueous and organic constituents. 

Water softening is carried out on an industrial scale by means of automatic apparatussThere are two kinds, namely, intermittent and continuous. In the former the water is mixed with the necessary chemicals, the precipitated hardness is allowed to settle, and the clear softened water drawn off. In the continuous form the precipitate is removed partly by gravity but chiefly by means of a filter. The essential parts of a water softener are (i) a reagent tank, (ii) a reaction tank, (iii) a precipitation tank connected generally with a filter, and (iv) a soft-water collecting tank. 

Line pressure powered Orival water filters remove dirt down to micron size, of any specific gravity, even lighter than water. Single units handle flow rates from 10-5000 gpm and clean automatically without interruption of system flow. 

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