RU2114678C1 - Three-phase separator - Google Patents

Abstract

FIELD: technique of preliminary dewatering of oil at oil fields for separation of mixtures of liquids and gas in other industries. SUBSTANCE: separator includes vessel with pipe unions for inlet of oil emulsion and outlet of separated phases with partition not reaching the vessel top and separating it into settling and oil collection chambers and with device for inlet of emulsion into settling chamber. The separator has one or several discharge devices for separated oil installed in settling chamber along the vessel. The device is in the form of trough whose bottom is inclined towards partition. Upper edge of trough is horizontal at the level of discharge edge of partition, and lower end is open and secured to cutout made in upper part of partition. Installed inside the trough, parallel to bottom, are shelves forming channel by themselves and together with trough bottom, connecting the settling and oil collecting chambers. Upper edges of shelves are located across the trough horizontally at the level of partition edge, and lower edges are attached to partition cutout in the form in it horizontal slots. Lower edge of upper shelf is below the level of oil in settling chamber. EFFECT: higher quality of oil and gas; prevention of water pollution with oil. 3 cl, 5 dwg

Description

 The invention relates to techniques for preliminary dehydration and oil separation in the fields and can be used in other industries for the separation of mixtures of liquids and gas.

 Known sump for separating water from oil, including a horizontal tank, in which a partition is placed to stabilize the level of the oil layer (Oil industry, N 2, 1974, p. 62, Fig. 5). The disadvantage of this sump is the turbulence of the flow of oil-water emulsion in the sump chamber, which significantly impairs the quality of the separated phases.

 Known sump for separating water from oil, containing a cylindrical tank divided by a partition into a receiving and settling chamber (French patent N 2220298, CL B 01 D 17/02, 1974).

 This apparatus has a low utilization rate of the volume of the chamber sump and, accordingly, low productivity and quality of the final emulsion separation products.

 Known apparatus for the separation of three-phase mixtures (oil - water - gas), in which the quality of the separated phases is improved by isolating the volume in them in the form of a chamber for collecting the separated oil (ed. St. USSR N 801847, class B 01 D 17 / 04, 1981; US patent N 3971719, CL 210-104, 1976; ed. St. USSR N 1142136, CL B 01 D 17/04, 1985). The apparatuses contain a horizontal cylindrical tank with fittings for introducing the oil emulsion and outputting the separated phases, a system of partitions and half-walls dividing the tank into compartments, and in the middle of the tank there is a chamber for collecting the separated oil. The design of these devices allows you to improve the quality of the separated oil, but due to cluttering the device with complex design elements, especially in the settling chamber, its working volume is reduced and, accordingly, the productivity of the device as a whole, as well as the quality of the separated water, are reduced.

 A known apparatus for the separation and preliminary dehydration of oil (Kasparyants K. S. et al. Processes and apparatuses for objects of oil and gas field preparation. - M .: Nedra, 1977, p. 156, Fig. 51), containing a horizontal cylindrical tank with fittings for entering the emulsion and withdrawing the separated phases, with a vertical partition that does not reach the top of the apparatus and separates the prepared oil collection chamber in the tank, and a semi-partition that does not reach the top of the apparatus and separates the water collection compartment. A disadvantage of this type of apparatus is the large volume of the gas zone (up to 30%), the duration of the separation process and, accordingly, the low productivity of the apparatus in terms of liquid, the significant entrainment of droplet oil and gas due to the active process of gas evolution on the surface of the separated oil, and the small volume of the settling zone in the apparatus.

 For the prototype, the installation separator (ed. St. USSR, N 1755863, class B 01 D 19/00, 1992), which contains a horizontal cylindrical tank with fittings for the input of oil emulsion and output of the separated phases, with a vertical partition that does not reach the top tanks and dividing the tank into a settling chamber and a dehydrated oil collection chamber. This separator is also characterized by a large volume of the gas zone, the duration of the separation process, a significant entrainment of the droplet oil with gas. In addition, in the settling chamber of this separator, at the partition separating the oil collecting chamber, a zone is formed in which the oil separated from the emulsion stagnates. This zone in its lower part almost reaches the bottom of the tank, which leads to oil pollution from the water removed from the apparatus.

 The objective of this solution is to create an apparatus for oil preparation at the fields, reliable in operation at remote fields, with increased productivity and quality of the separated phases at all stages of field operation, i.e. both at low and high water cuts of produced oil, with different content of dissolved hydrocarbon gas in it.

 The problem is solved in that the three-phase separator, which includes a tank with fittings for introducing the oil emulsion and outputting the separated phases, with a partition that does not reach the top of the tank and dividing it into the settling and oil collecting chambers, and with a device for introducing the emulsion into the settling chamber, contains one or several discharge devices for separated oil installed in a settling chamber along the tank. The device is a tray, the bottom of which is inclined towards the partition, and the upper generatrix (drain edge) is located horizontally, at the level of the drain edge of the partition. The bottom end of the tray is open and attached to the cutout made at the top of the partition. Inside the tray, parallel to its bottom, shelves are attached to its walls, forming through channels between themselves and with the bottom of the tray. These channels connect the settling and oil collection chambers and serve to withdraw the settled dehydrated oil from the settling chamber of the chamber to the oil collecting chamber. The upper edges of the shelves are located across the tray at the level of the drain edge of the partition. For a more uniform output of dehydrated oil from the settling chamber, the shelves divide the surface of the tray into equal parts. The lower edges of the shelves are attached to the cutout in the partition in such a way that they form horizontal slots, the lower edge of the upper shelf being located below the oil level in the settling chamber. This arrangement of the edges contributes to a uniform outflow of oil from the channels along the entire length of the lower edges of the shelves.

 The proposed solution, which multiplies the length of the edge of the oil overflow by adding the length of the drain edge of the tray, allows you to collect the most dehydrated settled oil from the top of the layer of settled oil. Drainage is a thin layer, with a low volumetric rate of collection, which allows it to be subjected to additional separation (separation of gas dissolved in oil). Perturbation of the layers in the volume of the settling chamber is prevented, which makes it possible to obtain the highest quality of oil, clean water and dry gas. An increase in the degree of oil separation is also facilitated by a thin-layer, on the surface of the shelves and bottom of the tray, oil outlet from the settling chamber through the channels into the oil collecting chamber. In addition, since oil enters the oil collection chamber not in one stream, but in several from the edge of the partition and from the edges of the shelves and the bottom of the tray from the slots in the cutout in the partition, by flat jets from different heights, foaming in the oil collection chamber is reduced and the entrainment of oil from the exhaust gas is prevented. The greatest effect is achieved by eliminating the stagnation zone of the separated oil in the settling chamber at the septum formed in the prototype due to turbulence caused by the flow of oil overflowing through the septum. Its elimination leads to the effect of increasing the working volume of the settling chamber prevents the entrainment of oil with water, which ultimately leads to an increase in the separator performance and the quality of the separated phases. The elimination of the stagnant zone is achieved by changing the direction of flow of oil removed from the settling chamber from solid, along the axis of the tank in the prototype, to complex, in which oil is drained along the shortest path to the nearest section of the drainage partition. Moreover, all flows are formed only on the surface of the settled oil and do not affect it in the depth of the layer.

 The number of trays installed in the separator depends on the size of the apparatus. An additional claim is proposed to perform the drain edges of the partition and the tray with a curved profile, because this will make it possible to lengthen the oil drain line even more, and, in addition, to cushion the pulsating mode of supplying oil-water emulsion to the apparatus.

 In FIG. 1 shows a General view of the separator in section; in FIG. 2 is a section AA in FIG. 1 (top view), with arrows showing the directions of oil flows when draining it through a partition and through the drain edges of the tray; in FIG. 3 - section BB in FIG. 1 (side view); in FIG. 4 - a perspective view of the apparatus with a breakout; in FIG. 5 - application.

 The separation unit, which includes a three-phase separator, contains a tank 1 with fittings for introducing an oil emulsion 2, an outlet for settled oil 3, water 4, gas 5. A depulsator is connected to the emulsion inlet in front of the separator tank, and a pipe 6 is inside the tank. A partition 7 separates the settling chamber 8 from the oil collecting chamber 9. In the settling chamber 8 along the tank 1, a tray 10 is installed to collect the separated light phase - oil. The upper generatrix 11 of the tray 10 is located in a horizontal plane at the level of the drain edge 12 of the partition 7, and the bottom 13 is inclined towards the oil collecting chamber 9. The lower end of the tray 10 is open and connected to the cutout 14 in the partition 7. Inside the tray, shelves 15 are installed parallel to its bottom attached by the side edges to the walls of the tray, and the bottom edge to the cutout 14, so that they form drain slots 16 in the cutout.

 Three-phase separator operates as follows. Gas-saturated emulsions of oil and water, passing the depulsator, through the nozzle 2 and the pipe 6 enters the settling chamber 8. In the chamber 8, the emulsion is destroyed with the separation of gas, oil and water. Gas is collected in the upper part of the separator and discharged through the nozzle 5, water settles to the bottom of the settling chamber 8 and is discharged from it through the nozzle 4, and oil is collected in the upper part of the chamber 8. The oil level in the tank 1 of the three-phase separator is maintained by the height of the partition 7. As sedimentation, the most dehydrated oil is concentrated in a thin upper layer and flows through the edges 12 of the partition 7 into the oil collecting chamber 9, and through the upper generatrix 11 of the tray 10 - to its bottom 13 and shelf 15. An additional gas evolution and separators take place on them The dehydrated dehydrated oil through the slots 16 is discharged into the oil collection chamber, from which it is discharged through the nozzle 3.

 This solution allows to improve the quality of oil by collecting the most dehydrated part of it, to prevent water pollution by oil by eliminating the stagnant zone near the partition of the settling chamber, to improve the quality of gas by preventing entrainment of droplet oil by it, and to improve the performance of the separator due to the rational distribution of oil and water in the settling the camera.

 The proposed design was tested in an oil field and showed high reliability and productivity, 20% higher than the industrial design of the prototype, with high quality separated phases. Moreover, it has high manufacturability, which, in combination with its other characteristics, is especially important in small remote fields.

Claims (3)

 1. Three-phase separator, including a tank with fittings for the input of the oil emulsion and the output of the separated phases, with a partition that does not reach the top of the tank and dividing it into the settling and oil collecting chambers, and a device for introducing the emulsion into the settling chamber, characterized in that in the settling chamber , along the tank, one or more drainage devices for the light phase are installed, which are a tray, the bottom of which is inclined towards the partition, the upper edge is located in a horizontal plane at the level of the edge of the partition, the lower torus The center is open and attached to the cutout in the upper part of the partition, inside the tray, parallel to its bottom, shelves are attached to its walls, the upper edges of which are located across the tray at the level of its upper edge, and the lower edges are attached to the cutout in the partition in such a way that they form horizontal slots, the lower edge of the upper shelf located below the oil level in the settling chamber, and the shelves form between themselves and the bottom of the tray channels connecting the settling and oil collecting chamber of the separator tank.  2. The separator according to claim 1, characterized in that the upper edges of the septum and the drain device are made curly, for example, toothed.  3. The separator according to claim 1, characterized in that the upper edges of the shelves divide the surface of the tray into equal parts.

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