Filter Separators

Design Conditions Required | Sizing Info | Technical Info | Picture Gallery

Design Conditions Required

• Gas Flow Rate MMSCF / Day
• Sales Line Pressure
• Oil Rate BBL / Day
• Water Rate BBL / Day
• Flowing Temperature
• Specific Gravity
• Sour Gas
• CO2

Sizing Information

• Filter Separator w/ Vane Type Mist Extractor
• Filter Separator w/ Wire Mesh Extractor

Technical Information

Coalescing Gas Separators

Coalescing gas separators are designed specifically for the removal of mist, fogs, and dust from gas streams. These contaminants usually exist with the bulk of the particles having diameters considerably less than 10 microns; therefore, standard separators or scrubbers are not capable of effectively removing these minute particles.

Coalescing gas separators consist of a vessel combining specially constructed fiberglass coalescing elements and a separation section with either a wire mesh or vane type mist extractor. A liquid accumulation section is provided to properly collect and discharge the liquid for further processing or disposal. Coalescing takes place as the gas passes through the fiberglass in the sock-type replaceable filter elements. The fiberglass forces small particles to agglomerate (coalesce)-forming larger drops or particles. The resulting larger droplets are then removed from the gas as the stream flows through the separator section. Further removal of entrained droplets is provided by the wire mesh or vanes of the mist extractor. All separated droplets are then collected in the liquid accumulation section. Any dirt, dust, rust, and scale in the gas will be removed on the outside surface of the filter elements.

Applications

Typical application for coalescing gas separators: 

1. Ahead of compressors to remove dust and liquids, which could cause damage to the compressor valves and cylinders.

2. Ahead of dry desiccant dehydrators to prevent compressor lube oil fog or other liquid contaminants from entering the absorber bed and causing degradation and excessive loss of effectiveness of the desiccant or treating media.

3. Ahead of glycol dehydrators to remove compressor lube oil fog, salt water fog, dust, rust, and scale from the gas stream and prevent contamination of the glycol solution. (KW International considers installation of a coalescing separator a "Must" ahead of a glycol dehydrator when gas is to be dried following compression.

4. Ahead of amine treating units to prevent contamination of the amine solution by dust, rust, iron sulfide, scale, and liquid contaminants.

5. Ahead of lean oil absorption plants to prevent contamination of the system by dust, rust, scale, and salt water.

6. Ahead of short cycle hydrocarbon recovery units to prevent "poisoning" of the desiccant.

7. In the compressor fuel system to prevent plugging of the various orifices and valves.      

8. In refrigerant compressor discharge to recover the refrigeration compressor lube oil and to prevent contamination of the heat transfer surface in the process chiller or exchanger.

9. Downstream of glycol absorbers or contactors to recover the entrained glycol mist carried overhead.

10. Downstream of amine treating units to recover the amine solution and to prevent contamination of subsequent process equipment.

11. Following lean oil absorbers to recover the lean oil (reducing operating costs), and to eliminate possible contamination of process equipment.

12. Ahead of metering and regulating town border stations to assure long life and low maintenance of the turbine meter or standard orifice meter

Features

1. Quick opening closure allows easy and rapid access to the filter assembly for cartridge replacement.

2. All filter elements are readily accessible and can be changed quickly.

3. Pressure taps are furnished to check the differential pressure drop across the coalescing elements. (Normally the pressure drop is approximately 0.5 psig with new cartridges. When the pressure drop reaches 5 to 7 psig, the cartridges should be replaced.)

4. Choice of wire mesh mist extractor or vane type mist extractor.

5. ASME Code construction throughout.

6. Wide range of sizes and capacities are available. Large sizes, providing high capacity, are available as horizontal units only.

7. High temperature filter elements are available for use with molecular sieve and short-cycle hydrocarbon recovery units.

8. Models are available with a section ahead of the coalescing elements to accumulate and remove sizable quantities of free liquids.

9. Small diameter units are available in either vertical or horizontal models.

Foam

Many wellstreams are encountered today that produce foam or have a tendency to foam under certain conditions. Foam can be produced either by mechanical agitation or chemical reaction. Foaming problems can be caused by changes in pressure or temperature, or the presence of minute particles of solids, surfactants from the producing formation, corrosion protection chemicals injected into the stream or any combinations of these factors. The heavier crudes tend to be more susceptible to foam formation.

Foam is a two-phase material, which can be present or created within the gas-liquid mixture as it is produced from the formation. It can be further aggravated by pressure reductions, turbulence caused by flow thru valves or piping, and temperature changes in the system. If the volume of the foam is too high or the stability of the foam is too great to allow the foam to break, the foamy fluids will pass through a separator and on into the gas line, thereby reducing the separation efficiency. The foam layer on top of the oil also interferes with the movement of liquid particles out of the gaseous phase and the release of solution gas from the oil phase.

Mechanically induced foam can usually be "broken" by mechanical means. Chemically induced foam may require chemical foam breakers as well as mechanical means. Foam separators are designed to provide increased contact surface to the foam to break up the stable foam. The use of special wire mesh foam pads and parallel plate surfaces are typical ways of providing this. The surface area must be great enough so that the rate of foam breakup will be faster than the rate of buildup. Horizontal separators are generally considered to be the best configuration for foamy production.

Waxes, Paraffins and Hydrates

Another group of problems encountered are wellstreams containing waxes, paraffins or hydrates. The only sure solution to wax or paraffin problems is to heat the wellstream above the wax or paraffin formation temperature before it enters the separator. Internals of the separator must be designed so that accumulations do not cause excessive pressure differentials, which could damage the internals. The internal construction must also allow for ease in steam cleaning, or back washing with solvents. Vane type mist extractors are usually preferred with wellstreams that have a tendency to deposit wax or paraffin. Separators cannot be designed to handle hydrates. The operating temperature of the separator must be kept above the hydrate forming range.

How It Works

Gas containing entrained liquid mist or fog, dust, rust, or scale (singly or in combination) enters the vessel through the inlet connection into the large inlet chamber ahead of the coalescing elements. This allows the gas to distribute around the coalescing elements for efficient use of the available filter surface area. Solid particulate materials are trapped by the filter element fibers as the gas and liquids pass through. The liquid mist or fog is retained by the fibers of the filter element until enough liquid accumulates to form a large drop. The gas then forces the large drops through the filter element. These large drops are then separated from the gas by gravity or by the action of the mist extractor section.

The liquid accumulates in the liquid chamber where it is removed by the action of the liquid level controller and dump valve.  The gas, free from its particulate contaminants and liquids, leaves the vessel through the gas outlet.

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