EA044454B1 - IN-TUBE SEPARATOR - Google Patents

Description

Field of technology

The invention relates to the field of devices for separating liquid from gas, in particular to separators widely used in the oil and gas industry for separating hydrocarbon condensate and water from natural or associated gas.

State of the art

A method of separating gas mixtures using axial cyclones is known from the prior art (see [1] RF patent for invention No. 2458298, IPC F25J3/08, published on August 10, 2012), in which the separation of water from gas is carried out in a system of two consecutive axial cyclones. Each cyclone separator includes a swirler, a liquid separation section, and a gas-liquid/liquid flow selection section.

The disadvantage of this analogue is that in the second cyclone separator it is impossible to ensure high efficiency in the selection of liquid flow from gas, because the liquid selection section of the second cyclone separator, which is a slotted cylindrical channel, receives a gas-liquid mixture formed in a two-phase boundary layer on the walls of the liquid separation section and representing a suspension of gas and liquid droplets. In this regard, the efficiency of liquid separation throughout the system is quite low.

A thermogas-dynamic separator is known from the prior art (see [2] RF patent for utility model No. 74308, IPC B01D45/12; B01D53/26, publ. 06/27/2008), including a housing, an input pipe for the initial multicomponent hydrocarbon gas, a gas swirler, a nozzle Laval, a separation chamber with a condensate outlet hole, a condensate collector, an ejection chamber with a gas intake pipe, pipes for removing the gas phase and condensate from the condensate collector, a purified gas flow diffuser, transverse partitions, each of the transverse partitions is made of two parts, the first of which is rigidly connected to the body, the second is located inside the first and is made removable, the nozzle, separation chamber and diffuser are installed sequentially inside the second parts of the transverse partitions. The disadvantage of this analogue is the low efficiency of liquid separation, due to the lack of special liquid separation devices in the gas recirculation channel connecting the condensate collector and the ejection chamber.

The closest analogue to the claimed invention in terms of the set of characteristics, adopted as a prototype, is an installation for low-temperature separation of gas or gas-liquid mixtures (see [3] RF patent for utility model No. 93513, IPC F25J3/06, publ. 04/27/2010), containing a connected with a source of a high-pressure gas or gas-liquid mixture, a first cyclone separator, including a channel located along its central axis for supplying a low-pressure gas or gas-liquid mixture and a coaxially enclosing swirler, behind which a nozzle and separation channels are sequentially placed along the flow direction, the latter being made with outlets for a two-phase mixture and for purified gas, wherein the outlet for the two-phase mixture is connected to the inlet of the separator for separating liquid, the gas outlet of which is connected to the inlet of the second cyclone separator, the outlet for the two-phase mixture of which is connected to the channel for supplying a low-pressure gas or gas-liquid mixture of the first cyclone separator, and the gas outlet of the second cyclone separator is connected to the purified gas outlet of the first cyclone separator.

The disadvantage of the prototype is that the liquid outlet from the second cyclone separator is connected to purified gas, which leads to deterioration of liquid separation of the entire system. In addition, the described system involves the use of both compact cyclone separators and a conventional capacitive separator, which leads to the complication of the entire separation system, an increase in the weight and size characteristics of the system and a corresponding increase in its cost.

The essence of the invention

The technical challenge facing the invention is to ensure high efficiency of liquid-gas separation with minimal size and weight of the separation system.

The technical result of the claimed invention is to increase the efficiency of selection of the liquid fraction from the gas fraction.

According to the invention, the technical problem is solved, and the technical result is achieved due to the fact that the in-line separator contains a main channel, which is a section of a pipeline with a first swirler, a first liquid separation section, a gas-liquid flow selection section, sequentially mounted inside it and axially located, and to the section gas-liquid flow selection, perpendicular to the main channel, the first additional channel is docked, which is a section of the pipeline with a second swirler, a second liquid separation section, a liquid selection section and a liquid collection tank sequentially mounted inside it and axially located, with the second liquid collection section connected by a second additional channel to an ejector located in the main channel between the first swirler and the first liquid separation section, while a control valve can be installed in the second additional channel.

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Brief description of drawings

The figure shows a general diagram of an in-line separator, on which the following positions are indicated:

- main channel;

- first swirler;

- first liquid separation section;

- gas-liquid flow sampling section;

- first additional channel;

- second swirler;

- second liquid separation section;

- liquid selection sections;

- capacity;

- second additional channel;

- ejector;

- control valve.

Carrying out the invention

The in-line separator consists of elements rigidly connected to each other by any known methods in the art, and consists of a main channel 1 and two additional channels 5 and 10, respectively. The main channel 1 is made in the form of a pipeline section, inside which the first swirler 2, the first liquid separation section 3 and the gas-liquid flow selection section 4 are sequentially and axially mounted. Also, the main channel 1 contains an ejector 11 located between the first swirler 2 and the gas-liquid flow separation section 4 .

To the gas-liquid flow sampling section 4, perpendicular to the main channel 1, the first additional channel 5 is connected by a joining method (i.e., docked), which is a section of a pipeline with a second swirler 6, a second liquid separation section 7, and a liquid extraction section mounted sequentially inside it and axially located 8 and capacity 9 for collecting separated liquid.

The liquid selection section 7 is connected by a second additional channel 10 to the ejector 11. In this case, a control valve 12 can be installed in the second additional channel.

The device works as follows.

The in-line separator operates according to the following scheme. The gas flow with condensate drops is directed into the main channel 1, where, passing through the first swirler 2, the flow acquires a tangential speed (begins to rotate). The swirling flow enters the ejector 11, where it is mixed with the recirculation gas flow. Next, the mixture of flows, which also has a tangential swirl of the flow after mixing, is sent to the first liquid separation section 3, which is a cylindrical channel in which, due to the action of centrifugal forces, liquid droplets move towards the channel walls. At the exit from the first liquid separation section 3 there is a gas-liquid flow sampling section 4, where a two-phase boundary layer containing separated droplets and a small amount of gas is taken from the walls of the liquid separation section. Purified gas (output flow) is taken from the central axial part of section 4. A two-phase flow (two-phase boundary layer) is removed from the main channel 1 and directed into the first additional channel 5, in which the flow swirls in the second swirler 6, then in the swirling flow in the second liquid separation section 7, droplets are separated and a central axial flow is formed at the exit of it. a core consisting of pure gas and a boundary two-phase layer on the walls of section 7, containing all the separated liquid. In the liquid selection section 8, gas with a small liquid content is selected, which through the second additional channel 10 enters the ejector 11 as a low-pressure flow. Liquid is also taken from section 8 and flows into container 9.

The first and second swirlers are stationary elements that can be made in the form of a central body with blades mounted on it (similar to the presented swirler [1]).

The ejector 11, installed between the first swirler 2 and the first liquid separation section 3, is made according to the classical ejector design. In it, the flow swirling in the first swirler 2 is accelerated in the nozzle, due to which a vacuum is created at the nozzle exit. A low-pressure gas flow with a small liquid content is supplied to the zone of this rarefaction through the second additional channel 10. The mixing of these flows occurs already in the channel of the first liquid separation section 3. In this case, the channel of the first liquid separation section 3 can be either conical tapering, conical expanding, or cylindrical. The channel configuration of the liquid separation section 3 depends on the specific parameters of the inlet flow, in particular on the liquid content in the inlet flow and the permissible pressure drop across the in-line separator. When the pressure drop across the in-line separator is small and the liquid content is low, a cylindrical channel is preferable. The selection of the geometric parameters of the ejector can be carried out in accordance with the calculation methodology presented in the book Collection of research works, BNI TsAGI, 1961, pp. 332-336 [4]. With a high liquid content - an expanding channel, because in this case there is an increase in thickness

- 2 044454 two-phase boundary layer on the walls of the section; accordingly, the expansion of the channel compensates for the increase in the thickness of the boundary layer. The degree of channel expansion can accordingly be assessed by calculating a two-phase boundary layer using the method presented, for example, in the ANSYS CFX software package designed for calculating two-phase flows. With a large pressure drop across the in-line separator, there is a narrowing channel, because in this case, the efficiency of the ejector increases (see [4])

Installation of a control valve in the second additional channel 10 allows you to regulate the flow of gas taken from the liquid selection section 8, and thus ensure the optimal operating mode of this section.

By creating a high flow swirl rate in the gas-liquid flow separation sections 3 and the liquid separation section 7, the described in-line separator allows for a high degree of separation of even submicron liquid droplets. As computational modeling of the gas-dynamic channel of the in-line separator shows, at flow swirl rates of 150 m/s, the in-line separator ensures the separation of 90% of droplets 0.3 μm in size. This indicator is unattainable for separators currently used in the oil and gas industry, which can provide separation of droplets no larger than 5 microns in size. This fact was confirmed during instrumental measurements of droplet entrainment at the outlet of the presented in-line separator.

In this case, the separator is mounted as an element of the pipeline, which significantly reduces the capital costs of its installation.

Claims (2)

1. An in-line separator containing a main channel (1), which is a section of a pipeline with a first swirler (2), a first liquid separation section (3), a gas-liquid flow selection section (4) sequentially mounted inside it and axially located, and to the section gas-liquid flow selection (4) perpendicular to the main channel, the first additional channel (5) is docked, which is a section of the pipeline with a second swirler (6), a second liquid separation section (7), a liquid extraction section (8) and axially located sequentially mounted inside it and capacity (9), and the second liquid selection section (8) is connected by a second additional channel (10) to an ejector (I) located in the main channel (1) between the first swirler (2) and the first liquid separation section (3). 2. In-line separator according to claim 1, characterized in that a control valve (12) is installed in the second additional channel (10).