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Italy |
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High efficiency separator for natural gas processing
U. Spinelli, inventor, L. Ciccarelli, ENI div. E&P and A. Bennardo, Enitecnologie
The “Wringing separator” is a system designed and supplied by Italy’s Micronsep S.r.l. to separate very small particles from gas feed. The minimum size of the solids particles is 1 micron, with an efficiency of 99.5%, see figure.
These performances may be increased if the system is used for liquid particles where droplet coalescence can increase their diameters, giving a more effective separation effect on liquid dispersed in the gas phase. One of the most important characteristics of the system is the constant efficiency at various flowrates from 0% to 100% design rate. In this way, it is possible to change flowrate and pressure and keep the efficiency practically constant.
The high efficiency and flexibility is accompanied with compact dimensions that can create significant savings in cost, space and weight, especially in platform applications where such parameters are important. The reduced dimensions are emphasized if the separator works at high flowrate and pressure.
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Solids removal efficiency of Wringing separator.
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An important recent application is the Brugherio plant near Milan, owned by Stogit for natural gas storage and winter distribution. The wellhead separator and the low temperature separator (LTS) are realized, with the Wringing separator achieving the important result of an efficient system, avoiding dew point performances depression, and the minimum dimension that gives very little transitional-phase varying flowrate or other parameters. Also, plant cost was minimized by the separator’s dimension. And a successful separator application has been carried out separating very small particles of FE2O3 for a commissioned 500-km pipeline.
The “Wringing separator” is neither centrifugal, cyclonic nor inertial in operation. Its function is based on the formation, inside its duct, of a particular secondary path flow which assumes a downward right-angled trend compared with main flow. This flow, by lapping the entire surface of the duct, acts as a hopper, transporter and ejector of all the contaminate (liquid and solid) through drain holes made on the bottom of the duct.
Once expelled, the finest part of the pollution (<5 microns) is “sucked up” by a vortex created below the drainage hole in the central area and, from there, using the drop current operating in the eye of the vortex, it is effected downward.
This vortex is the result of a system of “climbing” currents fed by the route set by the outgoing secondary current. This mechanism of currents is generated as soon as the gas flow starts and, therefore, the entire process, which oversees the separation of the extraneous parts from the gaseous one, is immediately set in motion.
By basing the system on existence of a boundary layer current kept close to the sides, the separation efficiency remains rigorously constant at all capacity levels within the maximum design level, and that is the reason why the separator must be scaled for the maximum effective volumetric capacity that can be generated in the system. 
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