Water spray

Water spray systems have been demonstrated to assist in the dispersion of vapor releases. The sprays assist in the dilution of the vapors with the induced air currents created by the velocity of the projected water particles. They cannot guarantee that a gas will reach an ignition source but do improve that probabilities that dispersion mechanisms will be enhanced. 

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Shipment. The DOT/IMO shipping information is shown in Table 6. Approved materials of constmction for shipping, storage, and associated transportation equipment are lined carbon steel (DOT spec. 105 S 500W) and type 316 stainless steel. Water spray, carbon dioxide, chemical-foam, or dry-chemical fire extinguishers may be used. 

Humidification. For wiater operation, or for special process requirements, humidification maybe required (see Simultaneous HEAT and mass transfer). Humidification can be effected by an air washer which employs direct water sprays (see Evaporation). Regulation is maintained by cycling the water sprays or by temperature control of the air or water. Where a large humidification capacity is required, an ejector which direcdy mixes air and water in a no22le may be employed. Steam may be used to power the no22le. Live low pressure steam can also be released directly into the air stream. Capillary-type humidifiers employ wetted porous media to provide extended air and water contact. Pan-type humidifiers are employed where the required capacity is small. A water filled pan is located on one side of the air duct. The water is heated electrically or by steam. The use of steam, however, necessitates additional boiler feed water treatment and may add odors to the air stream. Direct use of steam for humidification also requires careful attention to indoor air quahty. 

Direct water spray cooling must be carried out with care. The spray chamber must be designed to ensure complete evaporation of all Hquid droplets before the gas enters the baghouse. Spray impinging on the chamber walls can result ia a dust mud iaside the chamber and any increase ia gas dewpoint may result in baghouse problems or atmospheric plume condensation. Spray nozzle wear can result in coarse or distorted spray and wetted bags, and water pressure failure can cause high temperature bag deterioration. 

A filter cake from the wringer is washed to remove absorbed acid, transferred to a slurry tank of water, and quickly submerged, after which the nitrocellulose is pumped to the stabilization operation as a diluted water slurry. Exhaust systems are installed to protect personnel and equipment from acid fumes, and water sprays and cyclone separators are used for acid fume recovery before venting to the air. 

An important variation of this filter is based on replacing the rigid outer waU necessary for containing the feed and the cake on the rotating table by an endless mbber belt. The belt is held under tension and rotates with the table. It is in contact with the table rim except for the sector where the discharge screw is positioned, and where the belt is deflected away from the table to aUow the soHds to be pushed off the table. The cloth can also be washed in this section by high pressure water sprays. This filter, recendy developed in Belgium, is avaUable in sizes up to 250 m, operated at speeds of 2 minutes per revolution, and cake thicknesses up to 200 mm. 

Effectiveness ofi Water Spray Mitigation Systems fior Accidental Releases ofiHydrogen Fluoride, Summary Report, National Technical Information Service, June 1989. 

In one extractor (FMC Inc.), the fmit is located between two cups having sharp-edged metal tubes at their base. The upper cup descends and the many fingers on each cup mesh to express the juice as the tubes cut holes in the top and bottom of the fmit. On further compression, the rag, seeds, and juice sacs are compressed into the bottom tube between the two plugs of peel. A piston moves up inside the bottom tube forcing the juice through perforations in the tube wall. A simultaneous water spray washes the peel oil expressed during extraction away from the peel as an oil—water emulsion the peel oil is recovered separately from the emulsion. 

Normally ca 50% of the coal ash is removed from the bottom of the gasifier as a quenched slag. The balance is carried overhead in the gas as droplets which are solidified when the gas is cooled with a water spray. A fluxing agent is added, if required, to the coal to lower the ash fusion temperature and increase the molten slag viscosity. 

The gas leaving the heat recovery equipment contains soot and ash some ash is deposited in the bottom of the reactor for removal during periodic inspection shutdowns. The gas passes to a quench vessel containing multiple water-sprays which scmb most of the soot from the gas. Additional heat recovery can be accompHshed downstream of the quench vessel by heat exchange of the gas with cold feed water. Product gas contains less than 5 ppm soot. 

Fig. 8. Magnetherm reactor central electrode, A secondary circuit, B grounding electrode, C refractory lining, D carbon lining, E primary material feed, F slag taphole to FeSi recovery, G vacuum line, H water spray ring, I condenser, cmcible, K trap, L filter, M and transformer, N.

Fig. 3. Flame hardening (a) tempeiatuie—time heating curves of a 25 x 50 x 100 mm specimen at a feed of 75 mm /min and burner distance of 8 mm showing temperatures of A, surface B, 2 mm below surface and C, 10 mm below surface (b) hardness—depth curves for a 0.50% C steel 25 X 75 X 100 mm specimen at a feed of 50 mm /min, temperatures ia °C measured 10 mm below the surface, and burner distances ia mm, respectively, of A, 530 and 50 B, 540 and 12 C, 545 and 10 D, 550 and 8 and E, 565 and 6. Flame heating followed by water spray quenching. HV = Vickers hardness.

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