Separators mist extractor

Kig. 1. Typical vertical separator with mist extractor. 

Test results from various vaoe type mist extractors showed that they remove almost all particles larger than 25 microns in diameter. This will produce efficient separation in most oilfield applications. 

Impingement type mist extractor exemplified by knitted wire mesh pads are widely used in oilfield liquid and gas separation equipment. Their liquid and gas handling capacities are good with high liquid droplet removal efficiencies with small gas pressure drop. 

Fig. 1— Horizontal separator employs four basic mechanisms to liberate gaa from liquid. Inlet diverter imposes a sudden direction and momentum change on the flowstrearn, causing heavier liquids to drop out. Gravity settling section provides opportunity for smaller droplets to leave gas stream, and mist extractor coalesces remaining liquids as gas exits vessel. In addition, entrained gas escapes In liquid collection section.

Another type of separator used in certain high-gaa/low-liquid flow applications is a filter separator. These can be either horizontal or vertical in configuration. Fig. 4 shows a horizontal design. Filter tubes in the initial separation section coalesce liquid mist into larger droplets as gas passes through the tubes. A secondary section, consisting of vanes or other mist extractor elements, removes these coalesced droplets. 

Fig. 11—For vortical separators, vortical apace available to liquids is seam-to-seam length, less space tor mist extractor, gas separation ectlon and outlet clearance.

Paraffin. Separator operation can be adversely affected by paraffin accumulation. Coalescing plates in the liquid section and mesh pad mist extractors in the gas section are particularly prone to plugging by paraffin. If paraffin is an actual or potential problem, use of plate type or centrifugal mist extractors should be considered. Manways, handholes and nozzles should be provided to allow steam, solvent or other types of cleaning of separator internals. 

FIG. 14-110 Typical impingement separators, (a) Jet impactor. (b) Wave plate, (c) Staggered channels. (Blaw-Knox Food 6- Chemical Equipment, Inc.) (d) Vane-type mist extractor. (Maloney-Crawford Tank and Mfg. Co.) (e) Peerless line separator. (Peerless Mfg. Co.) (/) Strong separator. (Strong Carlisle and Hammond.) (g) Karbate line separator. (Union Catbide Corporation) (h) Type E horizontal separator. (Wright-Austin Co.) (0 PL separator. (Ingersoll Rand.) (/) Wire-mesh demister. (Otto H. York Co.)... 

Most vessel internals used for vapor and liquid separation arc 1) inlet divotcr - It is used for primaiy separation of vapor and liquid in feed due to their difleiencc in momentum. 2) mist extractor- It is u to further remove fine liquid droplets from v r. 3) vortex bieiiker - It is used to prevent vapor be drawn into the outlet liquid. It should be provided, if liquid is fed to a pump to avoid malfunction of pump. 4) overflow baflie plate (wicir) - It is used to separate light and heavy liquid compartments in a vapor/liquid iquid separator (three-phase separator J. Some three-phase separator is designed without overflow weir and relied on control interface level to separate the light and heavy liquid streams-... 

Although baffles, louver-like constructions, and wire mesh have long - been employed in efforts to alleviate entrainment, not until recently has the use of wire-mesh entrainment blankets become widespread. The aflowable velocity u (ft per sec) i gas separators equipped with wire-mesh mist extractors is ... 

The most commonly used single-well treater is the vertical heater-treater, which is shown in Figure 1.7. The vertical heater-treater consists of four major sections gas separation, FWKO, heating and water-wash, and coalescing-settling sections. Incoming fluid enters the top of the treater into a gas separation section, where gas separates from the liquid and leaves through the gas line. Care must be exercised to size this section so that it has adequate dimensions to separate the gas from the inlet flow. If the treater is located downstream of a separator, the gas separation section can be very small. The gas separation section should have an inlet diverter and a mist extractor. 

Filter chamber. The filter cartridges in the filter chamber have two functions— first, to coalesce fine liquid droplets into larger ones that are subsequently separated in the mist extractor chamber, and second, to filter out all remaining solid particles that have not been removed in the inlet chamber. 

Primary separator section. The inlet section has been designed to utilize the forces of gravity and centrifugal force through the use of small diameter cyclones to remove liquid and solid particles. In some applications the vane-type mist extractor will be used. 

Design features. Replacement of the final separation elements can be made with a minimum of time and effort through the use of a full opening O-ring or float ring closure. The primary separation elements (vane-type mist extractor or cyclone section) are completely maintenance-free and self-cleaning, with no replacement or moving parts to cause shutdown. 

These vessels employ many physical means to separate the liquids from gases in addition to the mist extractor. Foremost among these various separation forces are impingement, centrifugal force, gravitational force, and surface tension. See Fig. S-27. 

This settling effect, utilized in the vertical gas separator, removes all but a very small portion of the liquid. This remaining liquid continues to rise toward the gas outlet in the form of a fine spray. To solve this final separation problem, the mist extractor is used. 

These separators incorporate the vane-t5 e mist extractor as the separating element. This tinit offers a number of operating characteristics not found in other types of separators ... 

It is significant to note that the liquid drainage in the vane-type mist extractor differs from the drainage in other impingement-type mist extractors, in that vane drainage occurs with the liquid out of the gas flow and at a ri t an e to the direction of flow through the separator. 

The individual vane corrugations, depth and size of the liquid pockets, and the vane spacing are critical features of the vane-type mist extractor. Many years of testing and operating experience eventually arrive at optimum dimensions and spacing. The slightest variation in any one of these three features will materially decrease the capacity and performance of this type of separator. 

Efficiency and capacities. The vane-type line separator (see Fig. S-33) will remove all of the entrained liquid droplets that are 8-10 microns and larger. The efficienty of the unit decreases on droplet sizes less than 8 microns as shown on the chart. In order to separate these smaller droplets, the separator must be preceded by an ag omerating or coalescing device to increase the size of the droplets so that they can be removed by the mist extractor. Several types of ag omerating devices are available. Some of these are capable of achieving efficiencies as high as 99 /2 percent removal of 1 micron size droplets. 

Low-pressure drop. Since the vane-type mist extractor is self-cleaning and contains no small openings that can fill up and restrict the flow—such as are present in wire mesh pads or filter screens— the pressure drop across the separator is very low. The drop is as small as 2-3 in of water in the larger sizes. 

Capacities. Horizontal separators have high gas capacities because the mist extractor is installed longitudinally in the vessel. This arrangement permits the use of a large mist extractor inlet area. 

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