A coalescer is a technology device that performs coalescence. They are primarily used to separate emulsions into their components through various processes; operate in reverse to the emulsifier.
There are two types of coalescers. Coalescers mechanically use filters or baffles to make the droplets fuse while electrostatic coalescers use DC or AC (or combination) electric fields.
Video Coalescer
Technique coalescers
Coalescer that operates by the method of physical change or droplet involvement is influenced by mechanical , or physical, means. The more common type of coalescer, mechanical coalescers applied in the oil and gas industry worldwide to remove water or hydrocarbon condensates. While coalescers by definition function as a separation tool for liquids, they are usually used, and incorrectly referred to, as filters.
In the field of compressed air purification, the combine filter is used to separate water and liquid oil from compressed air using the effect of incorporation. This filter also removes particles. The most commonly used medium in this regard is micro-fiber Borosilicate.
In the Oil and Gas, Petrochemical and Refining Oil industries, Gas-Gas coalescers are widely used to remove water and hydrocarbon liquids into & lt; 0.011 ppmw (plus particles to & lt; 0.3Ã, um in size) of natural gas to ensure quality natural gas and protect downstream equipment such as compressors, gas turbines, amine or glycol reducers, molecular sieves, PSAs, gauges, beds mercury protectors, gas-fired heaters or furnaces, heat exchangers or purification membranes of gases.
In the Natural Gas industry, gas/liquid coalescers are used for downstream compressor oil recovery. All liquids will be removed but the recovery of lubricating oil is the main reason for installing coalescer at compressor outlet. The liquid from the upstream of the compressor, which may include aerosol particles, trapped liquids or large amounts of fluid called "slugs" and which may be water and/or hydrocarbon fluid combinations shall be removed by the upstream compounding/filtering vessel. The efficiency of gas/liquid coalescers is typically 0.3 microns of liquid particles, with an efficiency of up to 99.98%.
Liquid-liquid coalesers can also be used to separate hydrocarbons from aqueous phases such as removal of oil from the resulting water. They have also been used in the removal of petrol pyrolysis (benzene) from quench water in ethylene factories, although in this application, constant changes in cartridges may cause operator exposure to BTX (benzene, toluene and xylene), as well as discharge problems and high operational costs of replacement often.
Maps Coalescer
Electrostatic coupling
Electrostatic couplers use an electric field to induce droplet coalescence in a water-in-oil-crude emulsion to increase the droplet size. Quadratic dependence of the droplet diameter in Stokes Law, increases the speed of precipitation and destabilizes the emulsion. The effects on water droplets arise from dielectric properties that are very different from the conductive water droplets scattered in the insulating oil. Water droplets have a much higher permittivity than the surrounding oil. Furthermore, water with dissolved salt is also an excellent conductor. When unattended droplets are subjected to an AC power field, the field will polarize the droplets that create an electric field around the droplet to counter the external field. Because the water droplets are highly conductive, the induced charge will be on the surface. The drip does not have a net charge but one positive side and one negative side. Inside the droplet, the electric field is zero. When two droplets with polished induced close together, they will experience a force that draws the droplets closer until they join.
In oil production, the water produced together is mixed with oil in the choke valve and the process equipment produces a water emulsion in the oil. The amount of water increases during the reservoir production period. The emulsion is destabilized using a gravitational separator, and the settling rate increases by applying heat, demulsifiers, and AC electric fields. AC electric field generates an attractive force between water droplets and increases the likelihood of coalescence on contact. According to Stokes' law, the deposition rate increases proportionally with the square of the drop diameter. By promoting the coalescence of small water droplets, the deposition rate can be greatly increased. The water content is usually reduced to & lt; 0.5 vol% if this is the final treatment stage before crude oil is exported.
Typical electrocoalescers are large deposition tanks containing electrodes and operate under laminar-flow conditions with bare electrodes that may be susceptible to short circuit. An alternative to this type of coalescer is the flow through pre-coalescer mounted upstream in the separator tank. In Electrostatic Compact Coalescer. droplet coalescence is achieved by applying an AC power field (50-60 Hz) to a water-in-oil emulsion under turbulent flow conditions. Turbulence increases the frequency of collisions between water droplets. Electrodes are isolated to prevent short circuits, and allow up to 40% water content as well as water slugs. This equipment is a separate electrostatic treatment portion of the flow-stream mounted in the upper reaches of gravity separator to improve performance. By maintaining the treatment and completing the parts separately, a compact electrostatic coalescer can be obtained that can also be reassembled.
Liquid-liquid coalecers are also widely used in the oil refining industry to eliminate the last traces of contaminants such as amines or caustics from intermediate products in oil refineries, as well as to dewatering the last stage of final products such as jet fuel, LPG, gasoline and diesel to & lt; 15 ppmw of free water in the hydrocarbon phase. These coalescers are often the electrostatic type, in which the DC electric field pushes the water droplets to unite so that it is settled by gravity.
References
airclear.net
External links
- Coalescer (Design Guidance Techniques)
Source of the article : Wikipedia
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