Liquid overflowing

Liquid reaching the bottom of the column is partially vaporized in a heated r eboiler to provide boil-up, which is sent back up the column. The remainder of the bottom liquid is withdrawn as bottoms, or bottom product. Vapor reaching the top of the column is cooled and condensed to liquid in the over head conden.ser. Part of this liquid is returned to the column as r eflux to provide liquid overflow. The remainder of the overhead stream is withdrawn as distillate, or overhead product . In some cases only part of the vapor is condensed so that a vapor distillate can be withdrawn. 

Because the radius of the solid discharge port is ususally less than the radius of the liquid overflow at the broader end of the bowl, part of the settled solids is submerged in the pond. 

Liquid Overflow Inflow exceeds outflow Liquid slug How Blocked or restricted liquid outlet Level control system failure High liquid level... 

This represents feed as a superheated vapor, and there is a decrease in liquid overflow from feed plate. 

Z2 = height from datum to heavy liquid overflow, m,... 

Z2 Height to heavy liquid overflow from a decanter L... 

The process of thickening involves the concentration of a slurry, suspension, or sludge, usually by gravity settling. Because concentrated suspensions and/ or fine particle dispersions are often involved, the result is usually not a complete separation of the solids from the liquid but is instead a separation into a more concentrated (underflow) stream and a diluted (overflow) stream. Thickeners and clarifiers are essentially identical. The only difference is that the clarifier is designed to produce a clean liquid overflow with a specified purity, whereas the thickener is designed to produce a concentrated underflow product with a specified concentration (Christian, 1994 Tiller and Tarng, 1995 McCabe et al., 1993). 

A sludge is to be clarified in a thickener that is 50 ft in diameter. The sludge contains 35% solids by volume (SG = 1.8) in water, with an average particle size of 25 pm. The sludge is pumped into the center of the tank, where the solids are allowed to settle and the clarified liquid overflows the top. Estimate the maximum flow rate of the sludge (in gpm) that this thickener can handle. Assume that the solids are uniformly distributed across the tank and that all particle motion is vertical. 

In a batch thickener, an aqueous sludge containing 35% by volume of solids (SG = 1.6), with an average particle size of 50 pm, is allowed to settle. The sludge is fed to the settler at a rate of 1000 gpm, and the clear liquid overflows the top. Estimate the minimum tank diameter required for this separation. 

Fig. 3.7. Hydrometer (left) with large weighted bulb and calibrated scale. Pycnometer (right) is filled with fluid and when thermometer is inserted the liquid overflows into the small bulb.

L and w denote solute and solution, respectively, in the liquid overflows and... 

Thus the solute in the liquid overflow from the system as a whole is given by ... 

A, B, S refer to solute, insoluble solid, solvent respectively 1refer to liquid overflow or underflow from units 1, 0 refers to the liquid underflow feed to unit 1. 

This equation relates the composition of the vapour rising to the plate to the composition of the liquid on any plate above the feed plate. Since the molar liquid overflow is constant, Ln may be replaced by Ln+ and ... 

Because the dilference between the densities of the two phases is often small, and may vary from one stage to the next, //can vary strongly with h. Thus it is often necessary to make the height of the weir adjustable. Similarly, if there are significant differences in flow rate, then the depth of the liquid overflowing the weir has an effect on h and thus on the height of the interface. 

A long, hollow, cylindrical bowl is suspended by a flexible spindle and driven from the top as shown in Figure 13. Axial ribs in the bowl ensure full acceleration of the liquid during its short time in the bowl. Feed is jetted into the bottom of the bowl and clarified liquid overflows at the top, leaving deposited solids as compacted cake on the bowl wall. The clarifying performance of the bowl is reduced as the deposited cake decreases the effective outer radius of the bowl in accordance with equation 11. Consequently, cake capacity of the industrial model is limited to 0.1—10 L. For liquid—liquid separation, the interface position (eq. 26) is determined by selection of ring-dam diameter or by the length of a hollow nozzle-type screw dam. 

A recent processing development has been the continuous oxidizer, shown in Figure 3 (91). The charge is fed to the bottom of the column, where air is also introduced. At the top of the column the liquid overflows into a buffer tank. From this the oxidized asphalt is drawn off by means of a pump, provision being made for recirculation. 

Since in an extractive distillation process based on this ternary system the extractive agent is nonvolatile and remains in the liquid phase, and since because of the similarity of the molar latent heats of nitric acid and water there is substantially constant molar liquid overflow, the mole fraction of magnesium nitrate remains almost constant throughout the process. It is appropriate to represent the equilibrium situation as a pseudo-binary system for each magnesium nitrate concentration, and Figure 7 shows vapor-liquid equilibria on a nitric acid-water basis at a series of magnesium nitrate concentrations from zero to 0.25 mole fraction in the liquid phase. 

Liquid flows across a tray deck toward the outlet weir. The liquid overflows the weir, and drains through the downcomer, to the tray below. 

Crest height of liquid overflowing the outlet weir. 

The liquid overflows the baffle. The baffle is set high enough to keep the tubes submerged. This liquid is the bottoms product. 

Each tray in a tower is inherently a vapor-liquid redistributor. The outlet weir, or more exactly the crest height of the liquid overflowing the weir forces the liquid to flow evenly across the tray. Even if the weir... 

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