RU214745U1 - Ejector installation - Google Patents

Abstract

The utility model relates to ejector plants designed to compress low-pressure gases using the energy of high-pressure gases, and can be used in any industry where it is possible to mix flows with different pressures. The proposed solution is of particular interest for oil and gas facilities, where the excess energy of gas condensate, gas or gas-oil reservoirs can be used to compress low-pressure gases. At the same time, the ejector can be installed both directly near the wells, for compressing flows from low-pressure wells due to the energy of high-pressure wells, and at complex gas treatment plants (CGTP) for compressing low-pressure gases formed during the stabilization of condensate or oil. The ejector unit includes a main ejector, consisting of a high-pressure gas inlet pipe and a high-pressure gas supply chamber, a high-pressure gas nozzle, a low-pressure gas supply pipe, a low-pressure gas supply chamber, a low-pressure gas nozzle, a mixing chamber, a diffuser and a gas mixture sampling chamber. In front of the high-pressure gas supply chamber, inside the high-pressure gas inlet pipe, a swirler is installed in series and axially, and a gas-liquid flow selection section, the gas-liquid flow selection section is connected by a channel to the gas mixture selection chamber. The high-pressure gas supply chamber, the low-pressure gas supply chamber and the gas mixture extraction chamber are connected by pipelines to the corresponding chambers of four additional ejectors, and shut-off and control valves are installed in the pipelines connecting the corresponding high-pressure gas supply chambers and the gas mixture extraction chambers of the main and additional ejectors. The utility model makes it possible to increase the efficiency of the low-pressure gas ejection process in an ejector installation, in the presence of a liquid fraction in the high-pressure gas. 3 ill.

Description

Technical field

The utility model relates to ejector plants designed to compress low-pressure gases using the energy of high-pressure gases, and can be used in any industry where it is possible to mix flows with different pressures. The proposed solution is of particular interest for oil and gas facilities, where the excess energy of gas condensate, gas or gas-oil reservoirs can be used to compress low-pressure gases. In this case, the ejector can be installed both directly near the wells to compress flows from low-pressure wells due to the energy of high-pressure wells, and at complex gas treatment plants (CGTP) to compress low-pressure gases formed during the stabilization of condensate or oil.

State of the art

Gas ejectors installed in the oil and gas industry usually work with natural or associated gases, which are, in most cases, a mixture of alkane hydrocarbons, water, carbon dioxide and inert gases. In the case of installation of ejectors in wells for compressing gases from low-pressure wells using excess energy from high-pressure gas wells, natural gas entering the ejector installation usually also contains hydrocarbon condensate and water.

The situation is similar in the case of using ejectors at complex gas treatment plants (GTP), where ejectors are usually used to compress condensate stabilization gases. In this case, even if a separator is installed before the ejector to remove the liquid phase from natural gas, after the separator, the gas flows into the ejector through the pipeline, in which, due to hydraulic losses, the gas is throttled and cooled due to the Joule-Thomson effect. During cooling, the heavy fractions contained in natural gas condense, and thus, at the inlet to the ejector, the gas contains a liquid phase.

The presence of a liquid phase at the inlet of gas ejectors significantly reduces the efficiency of the ejectors, because the energy of the high-pressure gas is additionally spent on accelerating the liquid phase and crushing large droplets.

Details on the process of using ejectors at the GTP can be found in the monograph (see [1] Gritsenko A.I., Istomin V.A., Kulkov A.N., Suleimanov R.S. Gathering and field treatment of gas at the northern fields of Russia, - M.: Nedra, 1999. - 473 p.).

The scheme of a classic gas ejector is described in numerous monographs and consists of a high-pressure gas inlet pipe and a high-pressure gas supply chamber, a high-pressure gas nozzle, a low-pressure gas supply pipe, a low-pressure gas supply chamber, a low-pressure gas nozzle, a mixing chamber, a diffuser and a gas mixture sampling chamber (see ., for example, Fig. 1). A detailed description of the classical ejector and methods for calculating the optimal geometry of the gas-dynamic elements of the classical gas ejector are presented in the monograph (see [2] Arkadov Yu.K., New gas ejectors and ejection processes. - M. : Fizmatlit, 2001). The disadvantage of this ejector is its low efficiency in the presence of a droplet liquid phase in a high-pressure gas. Another disadvantage of such an ejector is the narrow range of normal operation of the ejector when the flow rate of high-pressure gas changes. The fact is that when the gas flow rate changes, the gas flow rate at the outlet of the high-pressure nozzle changes, which significantly affects the efficiency of the ejector.

A direct-flow centrifugal separator is known from the prior art (see [3] RF patent for invention No. 2125905, IPC B01D 45/12, publ. 10.02.1999), which is an outer cylindrical pipe with a coaxially integrated separation chamber in the form of a cylindrical pipe, in in front of the partition separating the annular cavity into the inlet part and the collector for collecting the trapped phase, there is a tangential swirler, and at the outlet of the separation chamber - a branch pipe for removing the purified gas, having a smaller diameter than the pipe of the separation chamber, and forming with its inner wall a receiving annular slot to output the trapped phase. Said separator is designed to separate the gas-liquid phase and does not have the ability to compress low-pressure gases.

From the prior art, a system of controlled pressure boosting of low-pressure gas is known (see [4] RF patent for invention No. 2415307, IPC F04F 5/54, publ. 03/27/2011), which contains at least two which additionally has a control valve of the active fluid bypass line, a low-pressure gas line is connected to the ejector inlets, and a high-pressure fluid line is connected to the inlets of the ejectors and the control valve through shut-off valves, the ejector outlets are connected to the outlet line through shut-off valves, the output of the specified control valve connected in the case of using a gaseous high-pressure fluid to the output line. A significant disadvantage of the described scheme is that the gas passing through the control valve is not used to perform the work of compressing low-pressure gas in the ejector, which significantly reduces the efficiency of the ejector system. Another disadvantage of the described system is its low efficiency in the presence of a liquid phase in a high-pressure gas.

The closest analogue to the claimed utility model in terms of the set of features taken as a prototype is a gas mixture preparation plant (supersonic separator), (see [4] RF patent for utility model No. 150781, IPC F25J 3/00, publ. 27.02. 2015), containing a nozzle with a prechamber, in which a means for swirling the gas flow is placed, which can be used as swirling blades, tangential gas supply, screw mechanism, etc. The prechamber is connected to a supersonic nozzle, inside which a combination of diffusers - supersonic and subsonic - is installed at a certain distance from the outlet section of the nozzle. Said combination of diffusers is connected to the walls of the nozzle in a known manner (for example, by means of pylons), so that an annular gap is formed between the walls of the nozzle and the supersonic diffuser for the extraction of the condensed phase. The disadvantage of the device, in comparison with the claimed utility model, is the inability to use it for ejection of low-pressure gases.

The essence of the utility model

The purpose of the utility model is to ensure the operability and high efficiency of the ejector installation under conditions where the high-pressure gas is a gas-liquid mixture, and the flow rate of the high-pressure gas changes with time.

The technical tasks facing the utility model are:

1) ensuring reliable operation of the ejector installation under conditions in which the high-pressure gas entering the ejector installation contains liquid;

2) ensuring the most complete use of the energy of high-pressure gas in the process of ejection of low-pressure gas while regulating the flow rate of high-pressure gas passing through the ejector installation.

The technical result of the claimed utility model is to increase the efficiency of the low-pressure gas ejection process in the ejector installation, in the presence of a liquid fraction in the high-pressure gas.

The technical problem is solved, and the technical result is achieved by the proposed ejector installation, which includes the main ejector, consisting of a high-pressure gas inlet pipe and a high-pressure gas supply chamber, a high-pressure gas nozzle, a low-pressure gas supply pipe, a low-pressure gas supply chamber, a low-pressure gas nozzle, a mixing chamber, a diffuser and a gas mixture sampling chamber, while in front of the high-pressure gas supply chamber, inside the high-pressure gas inlet pipe, a swirler is installed in series and axially, and a gas-liquid flow sampling section, the gas-liquid flow sampling section is connected by a channel to the gas mixture sampling chamber, and the chamber high-pressure gas supply chamber, a low-pressure gas supply chamber and a gas mixture extraction chamber are connected by pipelines to the corresponding chambers of four additional ejectors, and in the pipelines connecting the corresponding high-pressure gas supply chambers and the gas mixture extraction chambers, the main th and additional ejectors, shut-off and control valves are installed.

Brief description of the drawings

Fig. 1 - General scheme of a classic ejector.

Fig. 2 - General scheme of the proposed ejector installation.

Fig. 3 - Appearance of the proposed ejector installation.

The figures show the following positions:

1 - inlet pipe of high-pressure gas,

2 - high-pressure gas supply chamber,

3 - high-pressure gas nozzle,

4 - branch pipe for supplying low-pressure gas,

5 - low-pressure gas supply chamber,

6 - low-pressure gas nozzle,

7 - mixing chamber,

8 - diffuser,

9 - chamber for sampling a mixture of gases,

10 - the inner part of the high-pressure gas inlet pipe,

11 - swirler,

12 - gas-liquid flow selection section,

13 - channel connecting the gas-liquid flow sampling section with the gas mixture sampling chamber,

14, 17, 19 - pipelines,

15 - additional ejectors,

16 - shut-off and control valves,

18 - stopcocks.

Implementation of the utility model

The proposed ejector installation includes the main ejector, consisting of an inlet pipe 1 of high-pressure gas and a chamber 2 for supplying high-pressure gas, a nozzle for high-pressure gas 3, a branch pipe 4 for supplying low-pressure gas, a chamber 5 for supplying low-pressure gas, a nozzle 6 for low-pressure gas, a mixing chamber 7, diffuser 8 and chamber 9 for sampling a mixture of gases. In front of the chamber 2 for supplying high-pressure gas, on the inner part 10 of the inlet pipe 1 of high-pressure gas, a swirler 11 and a gas-liquid flow selection section 12 are installed in series and axially. Section 12 selection of the gas-liquid flow is connected by a channel 13 with the chamber 9 selection of a mixture of gases. High-pressure gas supply chamber 2, low-pressure gas supply chamber 5, and gas mixture extraction chamber 9 are connected by pipelines 14, 17, 19 to the corresponding chambers of four additional ejectors 15. For a clearer presentation of the design of the ejector installation, Fig. 2 shows only two of the four additional ejectors . Moreover, in the pipelines 14 connecting the chamber 2 for supplying high-pressure gas with additional ejectors 15, shut-off and control valves 16 are installed, and in the pipelines 17 connecting the chamber 9 for selecting a mixture of gases with additional ejectors 15, shut-off valves 18 are installed.

Ejector installation works as follows.

The high-pressure gas containing the liquid phase enters the inlet pipe 1 of the high-pressure gas, in the inner part 10 of the inlet pipe, the high-pressure gas passes the swirler 11 and acquires a tangential velocity component and begins to rotate, due to the action of centrifugal forces, drops of the liquid phase begin to move towards the walls of the inlet pipe 1 high-pressure gas, the swirling velocity of the flow in the swirler is selected in such a way that at the outlet of the inlet pipe 1 of the high-pressure gas, the entire liquid phase is separated onto the walls of the inlet pipe. At the outlet of the inlet pipe there is a section 12 of the selection of the gas-liquid flow, which is a conical insert, clean gas is taken in the center of the conical rate, and the gas-liquid flow is taken from the walls. The pure gas is then sent to the nozzle 3 of high-pressure gas, and is also sent through pipelines 14 to additional ejectors 15. Shut-off and control valves 16 are installed in pipelines 14. In nozzle 3, high-pressure gas accelerates and mixes with low-pressure gas, which passed in series through branch pipe 4 of low-pressure gas, a chamber 5 for supplying low-pressure gas; and a nozzle 6 for low-pressure gas. The process of mixing high-pressure and low-pressure gas takes place in the mixing chamber 7, at the outlet of the mixing chamber, the mixture of high-pressure and low-pressure gas enters the chamber 9 for sampling the mixture of gases. Through pipelines 19, low-pressure gas from the chamber 5 for supplying low-pressure gas is also supplied to additional ejectors 15. The mixture of gases from the outlet of additional ejectors 15 is fed through pipelines 17 into the chamber 9 for extracting a mixture of gases. Shut-off valves 18 are mounted in pipelines 17, but shut-off and control valves can also be installed.

An important part of the proposed ejector installation is a shut-off and control valve 16 installed in the pipeline 14. The shut-off and control valve 16 allows you to control the flow of high-pressure gas sent to additional ejectors 15 and ensure the required flow of high-pressure gas through the ejector installation. With a strong decrease in the flow of high-pressure gas, shut-off and control valves can be completely closed.

The performance of an ejector installation can be demonstrated by the example of tests of such an ejector installation, carried out at one of the installations for the complex preparation of natural gas. The ejector unit was designed to compress low-pressure gases with a pressure of 30 atm, which are formed during condensate stabilization. The high-pressure gas was gas with a pressure of 120 atm, supplied to the GTP from gas condensate wells. The content of the liquid phase in the high-pressure gas reached values of 50 kg/1000 nm ³ . The pressure at the outlet of the ejector installation was 40 atm. At the same time, the flow rate of high-pressure gas changed from 2.5 million Nm ³ /day to 5 million Nm ³ /day, the flow rate of low-pressure gas was 0.12 million Nm ³ /day. An ejector plant was installed at the facility, which has one main ejector designed for a maximum high-pressure gas flow rate of 2.5 million nm ³ /day and 4 additional ejectors with a maximum high-pressure gas flow rate of 0.625 million nm ³ /day. Vane swirler 11 provided flow swirl at the level of 50 m/s, high-pressure gas inlet pipe 1 had an internal cylindrical channel with a diameter of 250 mm. The gas-liquid flow selection section 12, made in the form of a conical diffuser pipe with an inlet diameter of 200 mm and an outlet diameter of 300 mm, and a total expansion angle of 6 degrees, ensured the selection of a pure gas flow to the inlet of a high-pressure nozzle. The selection of the gas-liquid flow was carried out through the channel connecting the section 12 selection of the gas-liquid flow with the chamber 9 selection of a mixture of gases. The diameter of this channel was 10 mm. This channel was mounted inside the body of the main ejector. The geometry of the swirler 11 and section 12 of the gas-liquid flow selection can be calculated in the ANSYS CFX software package, taking into account the condition that in the section 12 of the gas-liquid flow selection all drops larger than 10 μm in diameter should be selected from the high-pressure flow. That, as the experience of designing centrifugal separators shows, makes it possible to ensure the degree of separation of the liquid phase from the gas at a level exceeding 98%, sufficient for the normal operation of the ejector unit.

The diameters of the nozzle and mixing chamber were calculated using the AEROSYM software package, specially designed for calculating ejectors for the oil and gas industry. The diameter of the critical section of the high-pressure gas nozzle was 46 mm, while the outer diameter of the mixing chamber was 75 mm. The geometry of the additional ejectors was calculated from the condition of guaranteed provision of the required degree of compression of the low-pressure gas with a change in the flow rate of the high-pressure gas. The diffuser had a total expansion angle of 6 degrees.

The ejector control scheme was as follows:

- at a high-pressure gas flow rate of 5 million nm ³ /day, all 4 additional ejectors were turned on (all valves 18 were open),

- at a flow rate of high-pressure gas from 4.675 million nm ³ /day to 5 million nm ³ /day, all 4 additional ejectors were turned on (all valves 18 were open), but valve 16 was adjusted on the first additional ejector,

- at a flow rate of high-pressure gas from 4.35 million nm ³ /day to 4.675 million nm ³ /day, all 4 additional ejectors were turned on (all valves 18 were open), but valves 16 were adjusted on the first and second additional ejectors,

- at a flow rate of high-pressure gas from 4.025 million nm ³ /day to 4.35 million nm ³ /day, 3 additional ejectors are turned on, the first additional ejector is blocked, but valve 16 was adjusted on the second additional ejector,

- at a flow rate of high-pressure gas from 3.375 million nm ³ /day to 4.025 million nm ³ /day, 3 additional ejectors are turned on, the first additional ejector is blocked, but valve 16 was adjusted on the second and third additional ejectors,

- at a flow rate of high-pressure gas from 2.725 million nm ³ /day to 3.375 million nm ³ /day, 2 additional ejectors are turned on, the first and second additional ejectors are blocked, but valve 16 was adjusted on the third and fourth additional ejectors,

- at a flow rate of high-pressure gas from 2.5 million nm ³ /day to 2.725 million nm ³ /day, 1 additional ejector is turned on, the first, second, third additional ejectors are blocked, but valve 16 was adjusted on the fourth additional ejector,

The adjustment was carried out in automatic mode; if necessary, the ejector system can also be made with manual control valves.

The ejector plant tested with these parameters demonstrated a high degree of reliability and maximum efficiency of the low-pressure gas ejection process in the ejector plant, under conditions of a high content of the liquid phase in the high-pressure gas (reaching values of 50 kg/1000 nm ³ ), and when the flow rate of the high-pressure gas changes in the range from 2.5 million nm ³ /day to 5.0 million nm ³ /day. All parts of the claimed utility model are firmly interconnected by welding, bolts, rivets, etc. and form a single product aimed at improving the efficiency of the low-pressure gas ejection process in the ejector installation.

Claims (1)

Ejector installation, including the main ejector, consisting of a high-pressure gas inlet pipe and a high-pressure gas supply chamber, a high-pressure gas nozzle, a low-pressure gas supply pipe, a low-pressure gas supply chamber, a low-pressure gas nozzle, a mixing chamber, a diffuser and a gas mixture extraction chamber, differing by the fact that in front of the high-pressure gas supply chamber, inside the high-pressure gas inlet pipe, a swirler and a gas-liquid flow selection section are installed in series and axially, connected by a channel to the gas mixture selection chamber, and the high-pressure gas supply chamber and the low-pressure gas supply chamber are configured to select high-pressure gas and low-pressure gas, respectively, into four additional ejectors, and the gas mixture extraction chamber is configured to select a mixture of high-pressure and low-pressure gases from four additional ejectors.

Images