RU2709590C1 - Method of feeding reagent into pipeline - Google Patents

Abstract

FIELD: transportation.

SUBSTANCE: invention relates to a method of transporting gas products with inhibition of formation in a fluid of products preventing transportation, namely methods of introducing inhibitory substances into pipelines, and can be used in inhibiting formation of gas hydrates in a pipeline used for transportation of gaseous hydrocarbons. Reagent is supplied from at least two nozzles connected to reagent source, each of which has different flow characteristics. Amount of reagent is determined by parameters of gas flow in injection point: pressure, flow rate, temperature, moisture content, concentration of removed admixture in flow. Nozzles are included in different combination providing required quantity and degree of reagent spraying, at that each nozzle provides high degree of reagent spraying.

EFFECT: technical result obtained during implementation of the developed method consists in increasing the service life of the pipeline without accident on account of reducing the deposition of undesirable formations on the walls of the pipeline and shutoff valves, as well as optimization of the inhibitor consumption.

5 cl

Description

The invention relates to a method for transporting gas products with the inhibition of the formation of fluid blocking the transportation of products, namely, methods for introducing inhibitory substances into pipelines, and can be used to inhibit the formation of gas hydrates in a pipeline used for transporting gaseous hydrocarbons.

Natural gas, like other hydrocarbon fluids, contains carbon dioxide, hydrogen sulfide, and various hydrocarbons, such as methane, ethane, propane, normal butane, and isobutane. It has been found that water is typically reacted with such components of a hydrocarbon fluid in varying amounts. When such components of a hydrocarbon fluid or other substances capable of forming hydrates interact with water under conditions of high pressure and low temperature, clathrate hydrates can form. Clathrate hydrates are aqueous crystals that form around guest molecules, such as hydrate-forming hydrocarbons or gases, a prism-like structure, some hydrate-forming hydrocarbons include methane, ethane, propane, isobutane, butane, neopentane, ethylene, propylene, isobutylene, cyclopropane, cyclobutane, cyclopentane, cyclohexane and benzene, as well as other hydrocarbons.

Crystals of gas hydrate or gas hydrates are a class of clathrate hydrates and are of particular importance in the production and / or transportation of natural gas and other hydrocarbon gaseous media, they can form plugs in the pipeline. So, for example, at a pressure of about 1 MPa, ethane can form gas hydrates at temperatures below 4 ° C, and at a pressure of 3 MPa ethane can form gas hydrates at temperatures below 14 ° C. Such temperatures and pressures are common in many operating conditions in which natural gas and other hydrocarbon fluids / liquids are produced and transported.

Since gas hydrates are prone to accumulation, they can form hydrate plugs in the pipe or pipe used to produce and / or transport natural gas or other hydrocarbon fluids. The formation of such hydrate plugs can lead to equipment downtime during the extraction, transportation and processing of hydrocarbon raw materials, and as a result, significant financial costs. In addition, the re-launch of idle equipment, in particular equipment on the high seas or transport equipment, can be difficult due to the fact that significant amounts of time, energy and materials, as well as various mechanical devices, are required to safely remove hydrated plugs.

Various measures are used to prevent the formation of hydrate plugs in hydrocarbon fluid or natural gas streams (https://studfiles.net/preview/6864280/pageause/). Such measures include maintaining external temperatures that prevent the formation of hydrate plugs and / or pressure and introducing antifreeze, for example, methanol, ethanol, propanol or ethylene glycol. From an engineering point of view, to maintain external temperature and / or pressure, modification of equipment is necessary, for example, the use of an insulated or jacketed pipeline. Such modifications are very expensive to implement and reproduce.

Currently, in the gas industry, pipelines, in places where various fittings are located, on which hydrates are preferably formed, are mainly supplied with methanol to prevent hydrate formation (i.e., the formation of a C + H ₂ O crystalline structure at the fittings inside the pipeline). Injection is usually carried out through one nozzle, which was installed along the axis of the pipeline.

Known (RU, patent 2532822, publ. 10.11.2014) a method of introducing a reagent into the pipeline using an ejector, including the supply of gas and reagent to the ejector. When implementing the method, low-pressure and high-pressure gas are supplied to the ejector through appropriate means, and high-pressure gas is supplied from the high-pressure gas supply means through a four-way valve to the volume of the pneumatic cylinder, inside of which an axis is installed with the possibility of movement, two pistons are placed in series at one end and the other end at the other end the axis of the ejector shutter is installed, between the shutter of the ejector and the piston closest to it, displacing the pistons of the pneumatic cylinder and the shutter of the ejector with the release of the bore in the ejector e, and at the same time, high-pressure gas is supplied to the pneumatic reagent supply valve to the ejector with the reagent entering from the line into the ejector and then to the pipeline; to stop the reagent supply, high-pressure gas is fed into the pipeline by closing the pneumatic valve and simultaneously into the space between the pistons with subsequent displacement of the pistons and the ejector shutter with overlapping ejector.

Known (RU. Patent 2559383, publ. 08/10/2015) a method of introducing an inhibitor of hydrate formation in the pipeline of natural gas. A hydrate inhibitor from a main source of methanol or a pumping unit at a pressure higher than the pressure of the gas stream is supplied to the inlet of the device, to the inlet pipe. The input line is divided into two input channels of the inhibitor. The inhibitor is fed to a micrometer and an electric flow regulator. By a command formed from the operator's automated workstation (AWP), the control unit supplies power to the electric motor drive, which changes the flow area of the flow regulator. The fluid flow flowing through the product pipeline passes through a micrometer. The control system receives data from the micro flow meter on the missed flow rate of the inhibitor. If necessary, block the automatic line for controlling the supply of inhibitor.

Known (RU. Patent 2574159, publ. 02/10/2016) a method of supplying a hydrate inhibitor to a natural gas pipeline, comprising supplying an inhibitor with flow control. The method is carried out by means of a device for controlling the flow of an inhibitor, comprising a housing with inlet and outlet fittings and a working body in the form of a plunger pair placed inside the housing and made with a piston in the form of a cylinder having the possibility of reciprocating motion by an electric drive, while on the outer surface of the aforementioned the cylinder of the plunger pair perform radial grooves and at least one longitudinal groove of variable cross section, the passage area, which is reduced from the periphery part of the said cylinder to its central part, and the flow rate of the inhibitor is controlled by changing the bore of the channel formed by the plunger pair, by axially moving the said cylinder to the output or from the output fitting of the housing of the said device, or by changing the frequency of the electric current supplied to the electric drive of the said cylinder plunger couples.

The disadvantage of all the technical solutions given should be recognized as their lack of effectiveness, leading to the formation of hydrates in the pipeline.

The technical problem to be solved using the developed method consists in improving the supply of inhibitors to the pipeline for transporting natural gas.

The technical result obtained by the implementation of the developed method consists in increasing the resource of trouble-free operation of the pipeline by reducing the deposition of unwanted formations on the walls of the pipeline and valves, as well as optimizing the flow of the inhibitor.

To achieve the specified technical result, it is proposed to use the developed method for supplying the reagent to the pipeline. When implementing the developed method, the reagent is supplied from at least two nozzles connected to the source of the reagent, each of which has different flow characteristics, while the amount of reagent is determined by the parameters of the gas flow at the injection point: pressure, flow, temperature, moisture content, concentration removed impurities in the stream, and the nozzles are included in a different combination, providing the necessary amount of reagent, while each nozzle provides a high degree of atomization of the reagent (the concept of “with spray temperature "is disclosed at www.chem21.info/info/1037484/).

In some embodiments of the method, three or more nozzles are used that are connected to a reagent source, each of which has different flow characteristics

In some embodiments, the reagent inlet nodes are arranged along an axial line of the pipeline.

A possible implementation of the method when the nodes of the input of the reagent is located around the circumference of the pipeline.

When methanol is supplied to the pipeline as a methanol reagent, the flow rate of the condensate — methanol solvent — is additionally checked.

To implement the developed method, the following reagent supply system to the natural gas pipeline can be used. The system contains a reagent source line, then two nozzles connected to the indicated line, each of which has a first shut-off valve, a filter and a second shut-off valve in series, the outputs of the second shut-off valves are connected to the input of the reagent flow sensor, the output of which is connected to the check valve input the output of which is connected through shut-off valves with drives to the nozzle inputs. In addition, the system further comprises a control unit, as well as at least one of the pressure, temperature, reagent flow sensors installed on the pipeline, preferably, but not exclusively, in the vicinity of the inhibitor input point, which are connected to the input of the control unit, outputs the control unit is connected to the actuators of the shut-off valves, and the control unit is made with the possibility, depending on the measured parameters of the transported gas, to establish the optimal reagent consumption by switching on the necessary GOVERNMENTAL valves which are mounted on the input reactant nozzles, and the nozzles used various capacities or with different flow rate characteristics. The system may further comprise a first control pressure gauge mounted to measure pressure in the reagent source line. Also, the system may further comprise a second control pressure gauge mounted to measure pressure at the outlet of the check valve. In addition, the system may further comprise a shut-off valve installed with the possibility of venting gas from the pipeline through nozzles for cleaning them.

In order to achieve fine adjustment of the reagent flow, three nozzles are made with different flow characteristics, namely, 15%, 25% and 60% of the nominal value. Extensive flow control on one nozzle will lead to a sharp deterioration or complete cessation of reagent spray. For this reason, when implementing the developed method, several nozzles with different flow characteristics were used, which will provide both regulation of the reagent consumption and the required atomization fineness. In this case, including one, two or three nozzles in different combinations, the following values of methanol consumption from the nominal can be obtained: 15%, 25%, 40%, 60%, 75%, 85%, 100%, in addition, each nozzle gives adjustment flow rate with a good spray of methanol in the range of 10% -15%. In this case, with the required spray - not more than 10 microns, it is possible to continuously control the flow of methanol from 12% to 115%.

The reagent flow rate is determined by the gas flow parameters at the injection point: pressure, flow rate, temperature, moisture content, etc. These values are used to calculate the required reagent flow rate.

Using the developed system allows to increase the work of the pipeline between cleaning operations, at least 2.7 times, and also to reduce the consumption of methanol by spraying the reagent by 50%.

Claims (5)

1. The method of supplying the reagent to the pipeline, characterized in that the reagent is fed from at least two nozzles connected to a source of reagent, each of which has different flow characteristics, while the amount of reagent is determined by the parameters of the gas flow at the injection point: pressure , flow rate, temperature, moisture content, concentration of the removed impurity in the stream, and nozzles are included in various combinations providing the required amount and degree of spraying of the reagent, while each nozzle provides high the degree of atomization of the reagent. 2. The method according to p. 1, characterized in that use three or more nozzles, each of which has different flow characteristics. 3. The method according to p. 1, characterized in that the nodes of the input reagent are located on the axial line of the pipeline. 4. The method according to p. 1, characterized in that the input nodes of the reagent are arranged around the circumference of the pipeline. 5. The method according to p. 1, characterized in that when the methanol reagent is supplied to the pipeline, the condensate flow is additionally checked.