Vertical Gravity Separator

Liquid-phase separation (if necessary)—These calculations are similar to those for the vertical gravity separator. except that Eq. (14) is used when Dpt is not known and is assumed to be 500 jun. 

Gravity separators can take many shapes and arrangement, depending in part on the characteristics of the waste. Typical design configurations include horizontal cylindrical decanters, vertical cylindrical decanters, and cone-bottomed settlers. 

Gravity separators—horizontal and vertical (also called blowdown... 

Gravity Separators Three types of gravity separators are commonly used in the chemical process industries (CPI) horizontal blowdown drum/catch tank, vertical blowdown drum/catch tank, and multireactor knockout drum/catch tank. 

Gravity Separators (Horizontal and Vertical Drums/Catch Tanks)... 

Vapor-Liquid Gravity Separator Design Fundamentals The critical factors in the performance of a horizontal separator are the vapor residence time and the settling rate of the liquid droplets. However, two other factors enter into the design—the vapor velocity must be limited to avoid liquid entrainment, and there must be sufficient freeboard within the vessel to allow for a feed distributor. For vertical separators, the design is based on a vapor velocity that must be less than the settling velocity of the smallest droplet that is to be collected, with due allowance for turbulence and maldistribution of the feed. The vapor residence time is a function of the vapor flow rate (mass), vapor density, and volume of vapor space in the separator, based on the following ... 

Gravity separation. Most commonly used water treating equipment relies on gravity to separate oil droplets and the water continuous phase. Oil droplets, being lighter than the volume of water they displace, have a buoyant force exerted upon them. This is resisted by a drag force caused by their vertical movement through the water. When the two forces are equal, a constant velocity is reached that can be computed from Stokes Law ... 

The sizing of gravity separator can be calculated from the minimum vertical cross-sectional area of basin as follows ... 

The first applications of size exclusion chromatography involved typical vertical gravity flow columns in which sample and solvent were added alternately as described above. In the late 1980 s ion exclusion columns were placed in HPLC instruments and a one-pass-size exclusion separation was made. The advantage of this technique is that, in a complex mixture, the ionics are separated immediately from the nonionics, and then the nonionics can be separated in a regular manner. 

Consider the separation of liquid from gas in a vertical gravitational separator where the flow is directed against the force of gravity. Obviously, the drops that reach the exit of the separator will be the ones that satisfy the inequality Uj < U , where Uj is the sedimentation velocity of a drop with the radius R, and is the flow velocity, which is assumed to be constant. The minimum size of drops is determined from the condition Uj = U . Let us invoke the expression (18.28) for velocity Ug. Then in order to determine the minimum drop radius, one should solve the following equation ... 

The laboratory tests were conducted to qualify the separation rig by performing tests as tsimilar as possible to the field tests done previously. An important difference between the tests performed offshore and in the laboratory is the type of separator. The field tests were performed in a horizontal continuous gravity separator whereas the separation in the laboratory rig took place in a vertical batch separator. The oils and brine used in the laboratory were sampled offshore and kept under pressure until the tests were performed. 

By calculating the mean residence time between two heights inside the separator, the smallest particle diameter that will traverse the vertical distance can be calculated. This is known as cut size. It is customary in gravity-separator design to calculate the cut size for an oil drop between the bottom of the vessel (BV) and the various oil/water interfaces (NIL, LIL, HIL). Likewise, the cut size for a water drop between the various liquid interfaces (NOL, LOL, HOL) and the interface is calculated. The vertical velocity criterion thus becomes ... 

All five models discussed above have been subjected to comparison with data on gravity separation of bidis-perse suspensions in which light and heavy particles of the same size are vertically separated from each other in a liquid of intermediate density (Law et ah, 1987), and with data on sedimentation of polydisperse concentrated suspensions (Al-Naafa and Selim, 1989). The unequivocally inferior model that emerges from a combination of these comparisons is that of Lockett and Al-Habbooby (1973), while the equivocally superior one is that of Selim et al. (1983a,b). 

Nasr-El-Din H, Masliyah JH, Nandakumar K, Law D H-S. Continuous gravity separation of a bidisperse suspension in a vertical column. Chem Eng Sci 43 3225-3234, 1988. 

Counter-current gravity separators (dust settling chambers with vertical gas flow) the particles are precipitated by the action of gravity, i.e., they descend in the rising stream of gas, which is thus relieved of its dust burden... 

IV.2.1 a Sizing vertical gravity settling vapor/liquid separator... 

Horizontal flow treaters are not common. Figure 1.4 illustrates one design, which consists of a cylindrical treating tank incorporating internal baffles. The internal baffles establish a horizontal flow pattern in the cylindrical tank, which is more efficient for gravity separation than vertical flow and is less subject to short-circuiting. 

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