RU2409411C1 - Method of gas-fluid mix separation and gas-fluid separator to this end - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: set of invention relates to equipment intended for separation of free gas inclusions from fluid. Proposed method consists in swirling gas-fluid mix fed into the cylinder and discharging gas and fluid phases. Mix flow is swirled by feeding degassed fluid jet to mix inlet along tangential line to cylinder inner wall circumference, degassed fluid being bled at outlet at constant flow rate. Separator comprises cylinder, gas-fluid mix feed branch pipe, gas discharge branch pipe and degassed fluid discharge branch pipe. Nozzle directed tangentially to cylinder wall and communicated via tube with pump with cylinder bottom section inner space is arranged nearby feed branch pipe. Inlet of tube with pump represents a branch pipe with its open end located in cylinder zone, above degassed fluid discharge branch pipe, to face cylinder top section. Separator is furnished with crosswise web or funnel arranged in the cylinder with clearance with respect to cylindrical wall to separate degassed fluid bleed space by tube with pump from space communicated with degassed fluid discharge branch pipe.

EFFECT: stable bleed of pure gas from fluid, discharge of minor bubbles drawn downstream by forces of viscosity.

4 cl, 1 dwg

Description

The group of inventions relates to equipment for separating free gas inclusions from a liquid and can be used in the oil and gas industry to separate oil from gas.

There is a method of separating free gas inclusions from a liquid under the action of a pressure gradient created in a swirling flow of a gas-liquid mixture (for example, RU 2355463, 08.20.2008). The gas-liquid mixture is twisted in a cylindrical pipe, feeding it through a device (nozzle, screw, etc.), creating a flow with a velocity component directed tangentially to the circumference of the pipe wall. As a result of the rotation of the fluid around the axis, a centripetal acceleration occurs, directed towards the axis of the pipe, creating a radial pressure gradient. Under the influence of this pressure gradient on gas inclusions in the fluid, a buoyant force is applied to the axis of the pipe, which moves the gas inclusions to the axis of the pipe, where a gas cavity with a gas-liquid interface is formed, from which the gas phase is taken. Due to hydraulic losses at some distance from the place of creation of the tangential flow velocity, the phase boundary is closed and, if gas is removed from the gas cavity, a degassed liquid will flow after the phase boundary is closed. A liquid phase is taken from the bottom of the cylindrical tube. The operation of all cyclone-type separators is based on this method. A gas-liquid separator is known (see ibid.), Comprising a cylinder fixed tangentially on its upper part to a nozzle for supplying a gas-liquid mixture, fixed on its upper end to a gas outlet pipe and fixed on its lower part to a nozzle for removing a degassed liquid.

However, this method and the separator have two significant drawbacks:

1. With a large uneven flow of gas-liquid mixture, the gas-liquid interface becomes blurred until the flow is completely mixed over the entire cross section of the pipe, and continuous selection of pure gas and clean liquid becomes impossible.

2. High tangential velocity - this is the high kinetic energy of the flow, which is obtained from the potential energy of the flow (pressure) and then completely dissipated. (In practice, the allowable pressure loss in the gas-liquid mixture flow is often quite limited). To obtain a high tangential velocity at the existing flow rate, it is necessary to reduce the area of the passage section of the gas-liquid mixture inlet channel, which leads to large irreplaceable hydraulic losses. In practice, it is not allowed to exceed hydraulic losses in the separator of more than a few tenths of the atmosphere. Therefore, obtaining the required tangential velocity is not always possible.

3. In a viscous fluid, the movement of small gas bubbles is more determined by viscosity rather than buoyancy. For this reason, quite a lot of small bubbles can remain at the outlet of the separator in the liquid stream.

The technical result of the group of inventions is to eliminate these disadvantages. EFFECT: inventions ensure stable selection of pure gas from a liquid, as well as provide for the removal of small bubbles from a liquid that are carried downstream through a swirling flow by viscosity forces.

The technical result is achieved by the fact that in the method of separating a gas-liquid mixture by swirling the gas-liquid mixture flow supplied to the cylinder and withdrawing the gas phase from the gas cavity formed along the pipe axis, and the liquid phase from the downstream cavity filled with a degassed liquid, according to the invention swirling the flow of the gas-liquid mixture is carried out by feeding to the place of its supply tangentially to the circumference of the inner wall of the cylinder a stream of degassed liquid taken at the outlet of Lindrum at a constant rate.

The technical result is also achieved by the fact that in the gas-liquid separator comprising a cylinder, a gas-liquid mixture supply pipe fixed to its upper part, a gas discharge pipe fixed to its upper end and a degassed liquid discharge pipe fixed to its lower part, according to the invention, near said gas supply pipe to a nozzle directed tangentially to the cylinder wall and connected via a pipe to a pump with an internal cavity of the lower part of the cylinder is installed. In this case, the inlet section of the pipe with the pump is made in the form of a branch pipe, the open end of which is located in the area of the cylinder axis above the branch pipe for degassed liquid and faces the upper part of the cylinder. Thus, a significant part of the small bubbles concentrated along the axis of the flow, which are sent to the entrance to the separator for re-separation, is diverted to the pipe section with the pump.

In addition, the separator is equipped with a transverse partition installed in the cylinder with a gap relative to the cylindrical wall and separating the cavity in which the indicated open end of the pipe is placed from the cavity with which the pipe of drainage of the degassed liquid is connected.

In accordance with the proposed method, the twisting of the gas-liquid mixture supplied for separation occurs in contact with a commensurate flow rate of a highly swirling degassed liquid stream supplied at a constant flow rate (for example, a pump) into the cylinder near the point of supply of the gas-liquid mixture. Used degassed liquid is taken from the zone located beyond the closure of the gas-liquid interface on the liquid side.

Thus, the continuous selection of pure gas and pure liquid is ensured due to the fact that the unevenness of the total flow obtained after mixing the uneven gas-liquid flow with a powerful uniform liquid flow will be significantly lower.

The disadvantage according to claim 2 is absent, since the unwinding of the liquid occurs due to the energy of the stream of degassed liquid taken downstream (i.e., due to the energy of the pump pumping the liquid from the liquid zone beyond the point of closure of the interface).

The gas-liquid separator may take the form shown schematically in the drawing.

The gas-liquid separator comprises a cylinder 1 on which a nozzle 2 for supplying a gas-liquid mixture is fixed in the upper part, a nozzle 3 for venting gas at the upper end and a nozzle 8 for removing the degassed liquid from the separator at the bottom. In the upper part of the cylinder 1 near the supply pipe 2, a nozzle 4 is installed, which is directed tangentially to the wall of the cylinder 1. The nozzle 4 is connected via a pipe to the pump 5 with an internal liquid cavity 7 in the lower part of the cylinder 1.

The inlet section of the pipe with the pump 5 is made in the form of a pipe 6, the open end of which is located in the area of the axis of the cylinder 1 above the pipe 8 of the outlet of the degassed liquid and faces upwards towards the upper part of the cylinder.

The separator is equipped with a transverse baffle 9 installed in the cylinder with a gap relative to the cylindrical wall and separating the cavity in which the indicated open end of the pipe is placed from the cavity with which the pipe of drainage of the degassed liquid is connected.

In another embodiment, instead of a partition on the open end of the pipe 6, a socket 10 can be installed, the edges of which form a gap relative to the cylindrical wall and the cavity from which the degassed liquid is taken by the pipe 6 is separated from the cavity with which the pipe 8 of the drain of the degassed liquid is connected.

The method of separation of a gas-liquid mixture is as follows.

A gas-liquid mixture is introduced through the pipe 2 into the cylinder 1. The nozzle 4, directed tangentially to the wall of the cylinder 1, creates a stream of degassed liquid rotating along the wall of the cylinder 1, which is drawn by the pump 5 through the nozzle 6 from the fluid cavity 7 at the outlet of the cylinder 1. The inlet to the nozzle 6 is located above the nozzle 8, so that at the inlet to the nozzle 6, a shallow funnel forms, collecting small bubbles and a gas-liquid emulsion and sending the gas remaining after separation to re-separation through the nozzle 4. To prevent small bubbles from entering the nozzle 8 of the outlet of the degassed liquid a bone is provided with a baffle 9 or a bell 10, leaving a duct to the branch pipe 8 with a passage area of more than two times less than the passage area of the cylinder 1. Position 11 denotes the annular channel of preliminary twisting of the gas-liquid mixture flowing through the pipe 2 by a stream of degassed liquid, coming from nozzle 4.

Claims (4)

1. The method of separation of a gas-liquid mixture by swirling the flow of a gas-liquid mixture supplied to the cylinder and removing the gas phase from the gas cavity formed along the axis of the pipe, and the liquid phase from the downstream cavity filled with a degassed liquid, characterized in that the gas-liquid flow swirls the mixture is carried out by feeding to the place of its supply tangentially to the circumference of the inner wall of the cylinder a jet of degassed liquid, taken at the exit from the cylinder with a constant flow rate. 2. A gas-liquid separator comprising a cylinder fixed on its upper part to a nozzle for supplying a gas-liquid mixture, fixed on its upper end to a nozzle for gas removal and fixed on its lower part to a nozzle for removing degassed liquid, characterized in that a nozzle is installed on the cylinder near the specified nozzle for supplying directed tangentially to the cylinder wall and connected by means of a pipe to a pump with an internal cavity of the lower part of the cylinder, and the inlet pipe to the pump is made in the form of a pipe, open whose end face is located in the area of the cylinder axis above the branch pipe for degassed liquid removal and faces the upper part of the cylinder. 3. The separator according to claim 2, characterized in that it is provided with a transverse partition installed in the cylinder with a gap relative to the cylindrical wall and separating the cavity in which the indicated open end of the pipe is placed from the cavity with which the pipe for drainage of degassed liquid is connected. 4. The separator according to claim 2, characterized in that a socket is installed on the indicated open end of the pipe, the edges of which form a gap relative to the cylindrical wall and separate the cavity in communication with the specified pipe from the cavity with which the pipe for removing the degassed liquid is connected.

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