Tanks, cylindrical, flat-bottomed

Joosten et al. (1977) and Kolar (1967) also studied suspension of solids in stirred vessels. The correlations of Baldi et al. (1978) and Zwietering (1958) are based on data over a wide range of conditions and are also in good agreement with each other. Baldi et al. (1978) also proposed a new model to explain the mechanism of complete suspension of solid particles in cylindrical flat-bottomed stirred vessels. According to this model the suspension of particles at rest on certain zones of the tank bottom is mainly due to turbulent eddies of a scale of the order of the particle size. The model leads to an expression... 

BS EN 14015 2004 Specification for the design and manufacture of site built, vertical, cylindrical, flat-bottomed, above ground, welded, steel tanks for the storage of liquids at ambient temperature and above British Standards Institution... 

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. 

Atmospheric Tanks The term atmospheric tank as used here applies to any tank that is designed to be used within plus or minus several hundred pascals (a few pounds per square foot) of atmospheric pressure. It may be either open to the atmosphere or enclosed. Minimum cost is usually obtained with a vertical cylindrical shape and a relatively flat bottom at ground level. 

The whirlpool was introduced in the eady 1960s (Fig. 8). The tank is cylindrical with a flat bottom its diameter in ratio to height is usually 1 1.4. The hot wort is led tangentially into the tank, approximately in the middle of its side. 

Flat-bottomed, vertical, cylindrical storage tanks for low-temperature service , BSi, BS 7777 Part 1. 1993... 

Flat Bottoms Flat bottom vertical cylindrical tanks present particular problems. The bottom must be so constructed and supported as to be completely rigid and well ventilated from the sides and underneath. This may usually be provided by I beams. The bottom shall be tack welded to the I beam so that the bottom will not flex and crack the lining when it is installed. (Reference 8, p 74). The maximum free span between I beams can be calculated on the basis that the maximum deflection under full load conditions shall not exceed the free span divided by 1000. However, in the case of vessels containing only gas at atmospheric pressure and no internal spheres, then the deflection can be as great as the distance divided by 500. It is good design to leave sufficient space between I beams to allow for maintenance perhaps enough space for a man to crawl between them. 

From the standpoint of long life and freedom from maintenance, dished, hemispherical and cone bottoms are the best for cylindrical tanks, and are the designs of necessity if a vessel is to be "prestressed" (see Chapter 47), or if there is a desire or necessity to eliminate expansion joints. Flat bottoms, unless provided with properly designed expansion joints, will heave upward with brick growth. In addition, adequate and frequent stiffening is required if flexing and... 

Yamasaki et al. (1992) flat-bottom cylindrical tank 60 mm id. glass beads dp 0.042, ps 2350 sand dp 0.163, ft. 2650 PVCpowderdp 0.164, p, 1500 pair of P.O.F. fd 2nxn,pd 6mm with glass window LED modulated at 460 Hz personal conputer in liquid-solid system... 

STR, stirred tank reactor consisting of a cylindrical vessel (diameter 30 cm, volume 21.2 1) with a flat bottom and four symmetrical baffles and a six-blade disc impeller with a diameter of 10 cm. Screw loop reactor, with the volume of the dispersing zone about 64 ml and a reactor volume of 1.67 1. 

Adams, N.J.I. (1992) Seismic design rules for flat bottom cylindrical liquid storage tanks , Int. Journal Pressure Vessels and Piping, 49, pp. 61-95. 

Geometry For a stirred tank, the geometry is cylindrical, with a small aspect ratio (the height of fluid in the tank [H], is one to three times the tank diameter [T]). Although many industrial vessels have a dished bottom (especially if solids suspension is involved), simulations to date have used the simpler flat bottom geometry. The impeller, of diameter D = T/4 to T/2, is placed at the desired off-bottom clearance (C). Around the tank walls, two to four rectangular baffles are evenly... 

The system consists of a cylindrical tank with a flat bottom, the liquid level H of which is equal to the diameter, T. The impeller consists of two vertical plane blades fixed on a cylindrical central shaft, the diameter of which is equal to 0.05T. The ratio between the impeller diameter and the tank diameter D/T is equal to 0.5. All results are presented in dimensionless values, which enables the user to investigate any size vessel. 

If a cylindrical tank is operating at an elevated temperature, the steel walls will expand and so will the flat bottom. The steel expands outward and the masonry also expands, but often not quite as much as... 

The proportioning of a simple vessel may be based either on the cost per pound of the material or the cc t per unit area of the material. In Chapter 3 the proportioning of flat-bottomed, cylindrical, cone-roofed tanks was tesed on the cost per unit area because land and foundation costs, which are important for such vessels, can best be considered on a unit-area basis. In addition, the cost of coned rtxifs and flat bottoms are relatively constant on a unit-area basis for large-diameter tanks. However, cylindncal tanks with formed ends for various pressure services have wide variations in thickness and therefore vary in cost per unit area. The cost of land area and foundations is usually a minor consideration for such vessels. Therefore, it is more advantageous to consider the ( ost of shell arid heads in terms of unit weight rather than in terms of unit area. 

Cone-Roof Tanks. Cone-roof tanks are cylindrical shells having a vertical axis of symmetry. The bottom is usually flat and the top made ia the form of a shallow cone. These are the most widely used tanks for storage of relatively large quantities of fluid because they are economic to build and the market supports a number of contractors capable of building them. They can be shop-fabricated ia small sizes but are most often field-erected. Cone-roof tanks typically have roof rafters and support columns except ia very small-diameter tanks when they are self-supporting (see Fig. 4b and c Table 3). 

A typical stirred-tank reactor is shown in Fig. 5.4-3. It is a cylindrical vessel with elliptical or torospherical bottom and cover. It is equipped with an axially mounted stirrer rotating with a speed from 25 rpm (large scale) to 2000 rpm (laboratory). Fig. 5.4-4 shows the stirrers that are mostly used in fine chemicals manufacture, viz. the marine propeller, turbine, flat- or pitched-blade agitator, and anchor. Agitators move the fluid into axial and radial direction. Marine propellers and pitched-blade stirrers predominantly impose axial motion. 

The cost of a closed atmospheric cylindrical storage vessels can be considered to be proportional to the mass of steel required. Derive a simple expression for the dimensions of such a storage tank to give minimum capital cost. Assume the top and bottom are both flat. 

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