Gravity flow line

Gravity flow is a liquid flow. Many cases, the sounce and destination pressures are the same, equalized, fhe flow from the source to the destination Is relied on static height difference to move the fluid. The liquid in the source is drained into the destination. 

Available drain line design shows the line pleasure drop varies from 1.0 to 0.1 psi/lOD ff. More study should be done to find out which line ptessure drop should be us for gravity flow line. For preliminary gravity line sizing, it is suggested to use line pressure drop at O.l to 0.15 psi/100 ft. 

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Gravity flow lines are often set at VA inch to 2 inch minimum, disregarding any smaller calculated size as a potential source of trouble. 

Horizontal tube bundle with coolant in tubes (Figure 3.3). The vapor comes up from below and condensate drops into an annular space around the vapor nozzle. The latter has a haf over it to prevent condensate from dropping back down the column. Reflux may return internally via an overflow weir, or externally through a gravity flow line with a control valve. 

When alloy piping or large bore piping is required, the associated equipment is located together as much as possible to keep the pipe mns short, preferably nozzle-to-nozzle by avoiding the piperack. Items such as elevated overhead condensers are located near the source and destination. Similarly, thermosyphon reboHers need to be placed adjacent to the column they reboH. Where gravity flow is required, these lines must be kept short and sloped. Space allocation for future additions must also be considered. 

The principal mechanisms of disposition in dust collectors are (1) gravitational deposition, (2) flow-line interception, (3) inertial deposition, (4) diffusional deposition, and (5) electrostatic deposition. During the initial operating period, particle deposition takes place mainly by inertial and flow-line interception, diffusion, and gravity. Once the dust layer has been fully established, sieving is probably the dominant deposition mechanism. 

Alternatively, but not commonly, propulsion of the solutions can be achieved by gravity-based units, which rely on the difference in height between the solution(s) reservoir(s) and the flow lines of the manifold. Also, gas-pressure units, which rely on the action of pressure by an inert gas inside the vessels, which contain the solutions, can be used. Both these uncommon propulsion units yield pulse-free flow but require periodic refilling of solution reservoirs and adjustment of the desired flow rate is very difficult. 

Example 2.9. The gravity-flow tank system described in Chap. 1 provides a simple example of the application of the equations of motion to a macroscopic system. Referring to Fig. 1.1, let the length of the exit line be L (ft) and its cross-sectional area be A, The vertical, cylindrical tank has a cross-sectional area of A,... 

The gravity-flow tank that we considered in Chap. 1 and later in Example 2.9 makes a nice simple system to start our simulation examples. The force balance on the outlet line gave us the nonlinear ODE... 

Washing experiments have been conducted on a pilot-scale rayon washing line that employs the rain-pan technique of gravity-flow wetting. In this system, precision-drilled, stainless-steel pans are used to "rain" measured quantities of solutions onto a batt of cotton. The batt is conveyed by a perforated stainless-... 

Fresh catalyst is normally delivered in hopper-bottom railroad cars. The catalyst may be withdrawn by gravity flow from the bottom of the car through a hose to a Fuller-Kinyon screw pump and transferred to the hopper by means of an air stream loss of catalyst is prevented by a cyclone on the air discharge from the hopper. Alternatively, the catalyst may be unloaded from the top of the ear by a vacuum lift. In this case, the suction line passes through a separator with bag filters, located above the storage hoppers. The catalyst collects in a chute and flows down through a rotating barrel-valve feeder into a screw conveyor which transfers the catalyst to the hopper (105). 

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