Cylindrical tanks

There are three types of thickener designs cylindrical, lameUa, and deep cone. The cylindrical design is the most common (Fig. 20). It is also continuous. It comprises a large (up to 200 m dia, 1—7 m deep) cylindrical tank, a shallow conical base (80—140 mm/m), and a central stmeture carrying... 

Tank Bottoms. The shape of cylindrical tank closures, both top and bottom, is a strong function of the internal pressure. Because of the varying conditions to which a tank bottom may be subjected, several types of tank bottoms (Fig. 7 Table 4) have evolved. These may be broadly classified as flat bottom, conical, or domed or spherical. Flat-bottom tanks only appear flat. These usually have designed slope and shape and are subclassifted according to the following flat, cone up, cone down, or single slope. 

Double Wall. Double-wall tanks have become more common for both above- and underground appHcations because the outer tank can contain a leak from the inner tank. This also serves as a means of detecting leaks. Such tanks are usually cylindrical tanks and may have either vertical or horizontal orientation. 

In the large-diameter vertical cylindrical tanks, because hoop stress is proportional to diameter, the thickness is set by the hydrostatic hoop stresses. Although the hydrostatic forces increase proportionally with the depth of Hquid in the tank, the thickness must be based on the hydrostatic pressure at the point of greatest depth in the tank. At the bottom, however, the expansion of the shell owing to internal hydrostatic pressure is limited so that the actual point of maximum stress is slightly above the bottom. Assuming this point to be about 1 ft (0.305 m) above the tank bottom provides tank shells of adequate strength. The basic equation modified for this anomaly is... 

Tank Roof. The roof of a vertical cylindrical tank is treated like a building stmcture and uses the same basic rules as the building codes. For example, the API codes require a roof to be designed for the dead load plus a 122-kg/m (25-lb /ft ) Hve load. The minimum fabrication thickness of roof plates is 3/16 in. (4.8 mm). 

Posttensioned Concrete This material is frequently used for tanks to about 57,000 m (15 X 10 gal), usually containing water. Their design is treated in detail by Creasy (Pre.stre.s.sed Concrete Cylindrical Tanks, Wiley, New York, 1961). For the most economical design of... 

Pressure Tanks Vertical cylindrical tanks constructed with domed or coned roofs, which operate at pressures above several hundred pascals (a few pounds per square foot) but which are still relatively close to atmospheric pressure, can be built according to API Standard 650. The pressure force acting against the roof is transmitted to the shell, which may have sufficient weight to resist it. If not, the uplift will act on the tank bottom. The strength of the bottom, however, is limited, and if it is not sufficient, an anchor ring or a heavy... 

Hydraulic cylindrical tank classifier Om tp (M-F) Hydraulic form of overloaded thickener. Siphon-Sizer (N-F) uses siphon to discharge underflow instead of rotating rake. 1.0 to 40 1.4 mm to 45 im (25 mm) 1 to 150 Not critical 0.4 to 15 20 to 35 0.75 to 11 Two-product device giving very clean underflow. Requires relatively little hydraulic water (2 t/t solids feed). Used for washing, desliming, and closed circuit grinding. 

Cone classifier (N-S) Similar to cylindrical tank classifier, except tank is conical to eliminate need for rake. 0.6 to 3.7 600 im to 45 im (6 mm) 2 to 100 Not critical 5 to 30. 35 to 60 None Low cost (simple enough to he made locally), and simplicity can justify relatively inefficient separation. Used for desliming and primary dewatering. Solids buildup can be a problem. 

Pietersen (1988) describes the San Juan Ixhuatepec disaster. The storage site consisted of four spheres of LPG with a volume of 16(X) m (56,500 ft ) and two spheres with a volume of 2400 m (85,000 ft ). An additional 48 horizontal cylindrical tanks of various dimensions were present (Figure 2.24). At the time of the disaster, the total site inventory may have been approximately 11,000-12,000 m (390,000-420,000 ft ) of LPG. 

At 5 45 A.M., a flash fire resulted. The vapor cloud is assumed to have penetrated houses, which were subsequently destroyed by internal explosions. A violent explosion, probably involving the BLEVE of several storage tanks, occurred 1 minute after the flash fire. It resulted in a fireball and the propulsion of one or two cylindrical tanks. Heat and fragments resulted in additional BLEVEs. 

Pittman (1972) performed five experiments with titanium-alloy pressure vessels which were pressurized with nitrogen until they burst. Two cylindrical tanks burst at approximately 4 MPa, and three spherical tanks burst at approximately 55 MPa. The volume of the tanks ranged from 0.0067 m to 0.170 m. A few years later, Pittman (1976) reported on seven experiments with 0.028-m steel spheres that were pressurized to extremely high pressures with argon until they burst. Nominal burst pressures ranged from 100 MPa to 345 MPa. Experiments were performed just above ground surface. 

Solar water heating became commercially available in Southern California in the 1890s. Early models consisted of four large cylindrical tanks of heavy galvanized iron mounted horizontally in a wooden box under a glass cover. 

Total volume or length of shell in cylindrical tank with ellipsiodal or hemispherical heads ... 

Volume or conlents of partially filled horizontal cylindrical tanks ... 

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