Large Tank

Large filament wound 150,000 gal (568 m ) tank has been fabricated by the Rucker Co. for Aerojet-General (1966). An example is shown schematically in Fig. 4.19 of the so-called racetrack-fabricating machine. A fabricated 56 m (22 ft) high, 152 m (60 ft) wide, 318 m (125 ft) long that weighed 32 ton, of all RP, large tank is shown in Fig. 4.20. 

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Figure 3.3 shows a simple type of classifier. In this device, a large tank is subdivided into several sections. A size range of solid particles suspended in vapor or liquid enters the tank. The larger, faster-settling particles settle to the bottom close to the entrance, and the slower-settling particles settle to the bottom close to the exit. The vertical baffles in the tank allow the collection of several fractions. 

For brines having very low iodide concentrations, ie, in some facilities in Japan and in the former USSR, the activated carbon method of recovery is used. This method consists of a process involving the treating of the acidified brine with sodium nitrite in large tanks, where the following reaction takes place ... 

Liquid Dosage Forms. Simple aqueous solutions, symps, elixirs, and tinctures are prepared by dissolution of solutes in the appropriate solvent systems. Adjunct formulation ingredients include certified dyes, flavors, sweeteners, and antimicrobial preservatives. These solutions are filtered under pressure, often using selected filtering aid materials. The products are stored in large tanks, ready for filling into containers. QuaUty control analysis is then performed. 

Open Tanks These may be used to store materials that will not be harmed by water, weather, or atmospheric pollution. Otherwise, a roof, either fixed or floating, is required. Fixed roofs are usually either domed or coned. Large tanks have coned roofs with intermediate supports. Since negligible pressure is involved, snow and wind are the principal design loads. Local building codes often give required values. 

At very low temperatures with hquid air and similar substances, the tank may have double walls with the interspace evacuated. The weh-known Dewar flask is an example. Large tanks and even pipe hues are now built this way. An alternative is to use double walls without vacuum but with an insulating material in the interspace. Perlite and plastic foams are two insulating materials employed in this way. Sometimes both insulation and vacuum are used. 

Reynolds numbers in the large tank will be higher, typically on the order of 5 to 25 times higher than those in a small tank. 

Large tanks tend to develop a recirculation pattern from the impeller through the tank back to the impeller. This results in a behavior similar to that for a number of tanks in a series. The net result is that the mean circulation time is increased over what woiild be pre-dic ted from the impeller pumping capacity. This also increases the standard deviation of the circulation times around the mean. 

The shear stress in the fluid is much higher near the impeller than it is near the tank wall. The difference is greater in large tanks than in small ones. 

The fluidfoil impellers in large tanks require only two baffles, but three are usually used to provide better flow pattern asymmetiy. These fluidfoil impellers provide a true axial flow pattern, almost as though there was a draft tube around the impeller. Two or three or more impellers are used if tanks with high D/T ratios are involved. The fluidfoil impellers do not vortex vigorously even at relatively low coverage so that if gases or solids are to Be incorporated at the surface, the axial-flow turbine is often required and can be used in combination with the fluidfoil impellers also on the same shaft. 

If the blending process is between two or more fluids with relatively low viscosity such that the blending is not affected by fluid shear rates, then the difference in blend time and circulation between small and large tanks is the only factor involved. However, if the blending involves wide disparities in the density of viscosity and surface tension between the various phases, then a certain level of shear rate may be required before blending can proceed to the required degree of uniformity. 

Two men were inspecting a large tank in which other equipment was installed. The tank had two large manways attached to it, one near the bottom and one near the top. Ventilation was provided by air entering the bottom manway and leaving the top manway. A sheet of plastic had temporarily been placed over the top manway, which decreased the amount of air circiilation. One of the inspectors chmbed a ladder in the tank, became dizzy, and fell to the tank floor below. He died from the injuries received in the fall. It was found that... 

Efforts are made in the construction of new, large tank farms to achieve electrical isolation of buried and cathodically protected fuel installations from all... 

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