Gravity settling device

Gravity settling device A chamber in which a change in velocity and/or direction of a dust-laden airstream allows the dust to settle into a collection hopper. 

Fig. 1—SP packs are gravity settling devices that promote oil drooiet coalescence by moans ot turbulence the drawing shows a typical two-stage vertical configuration graphs plot removal efficiencies for 8 and 10-ft tanks...

A gravity settling device processing a feed with size distribution F x) and operates with a grade efficiency G x). Its total efficiency is defined as ... 

The emulsions in produced water will become oil in the form of dispersed droplets after the emulsion film is broken. The droplets will coalesce to yield an oily film that can be separated from the produced water using gravity settling devices such as skim vessels, coalescers, and plate separators. However, small droplets require excessive gravity settling time, so flotation cells or acceleration enhanced methods such as hydrocyclones and centrifuges are used. Equipment selection is based on the inlet oil s droplet diameter and concentration. 

Coalescence. Coalescence by gravity in simple settling devices can often be used to separate immiscible liquid-liquid mixtures. The coalescence can be enhanced by the use of mesh pads and centrifugal forces, as discussed in Chapter 8. 

Chemical additives are demulsifiers generally injected in the oil upstream of the dehydration system. The use of demulsifiers with a gravity separation device such as a three phase separator or settling tank can successfully remove as much as 95 percent of the produced water present in the oil. Removal of the remainder of the water droplets through... 

Equations (4.3a) and (4.3b) may be used to size any of several types of equipment designed to use gravity settling. Such devices as settling ponds, pits, flumes, and tanks are commonly used onshore where space is available. 

Time is a critical variable because the magnetite settles if the mixture is held too long in a static condition. Use of hydrocyclones makes possible the separation in a fraction of a minute (21). These devices impart centrifugal force to the system, thereby permitting a separation to be made at a specific gravity less than that required in static, heavy-Hquid separations. 

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