RU165613U1 - DEVICE FOR MEASURING FLOWS IN A MAIN GAS PIPELINE - Google Patents

Abstract

A device for measuring flow in a main gas pipeline containing a multichannel ultrasonic flow transducer integrated in the housing, designed to be connected to a processing unit, while the housing of a multichannel ultrasonic flow transducer is made of a pipe whose diameter coincides with the diameter of the main gas pipeline and has coaxial welded joints with a supply and discharge direct sections of the main gas pipeline, characterized in that the multichannel ultrasonic transducer ra the descent is covered with a hard bandage from the surface of the housing.

Description

Device for measuring flow in the main gas pipeline

Technical field

The utility model relates to devices for measuring flow and can be used for commercial metering of gas transported through gas pipelines.

State of the art

The diameters of modern gas pipelines reach 1600 mm. Flowmeters of appropriate diameters do not provide the accuracy necessary for commercial accounting, due to errors caused by deviations of their internal section from the shape of an ideal circle. Therefore, according to the current standard “Consumption and amount of natural gas. The measurement technique using ultrasonic flow transducers ”, the inner diameter of ultrasonic flow transducers (flow meters) and adjacent measuring pipelines ranges from 100 mm to 900 mm [STO Gazprom 5.2-2005, p. 10.2.2].

Currently, gas flow in main gas pipelines is measured at gas metering stations (GIS), which, in order to ensure the accuracy necessary for commercial accounting (error of not more than 0.8%), are multi-strand from several (4-5) parallel above-ground measuring pipelines of smaller diameter (as usually 700 mm). GIS measuring pipelines are connected to the underground main gas pipeline using inlet and outlet collectors [see for example, an electronic resource http://neftegaz.ru/tech_library/view/4437/]. In order to ensure the stationary gas flows measured by flow meters, each measuring pipeline includes straight sections (inlet and outlet), the total length of which (according to STO Gazprom 5.2-2005, clause 9.2) can reach 30 diameters of the measuring gas pipeline. Given the need for maintenance, parallel measuring pipelines are located at a distance from each other and occupy a significant part of the land allocation area under the GIS.

The disadvantage of the above multi-thread devices for measuring flow in main gas pipelines is that they require a lot of pipeline equipment and a large production area.

The US-800 ultrasonic flow meter is also known (http://www.us800.ru / dvuhluch.htm, available in the price list dated June 1, 2008)., Which contains a multi-channel ultrasonic flow transducer integrated in the housing for connecting to a processing unit the case of a multi-channel ultrasonic flow transducer is made of a pipe whose diameter coincides with the diameter of the main gas pipeline, and has coaxial welded joints with inlet and outlet straight sections of the main pipeline.

This device is considered as a prototype.

The disadvantage of the prototype is the low accuracy of flow measurement, which does not allow the use of the prototype for commercial metering of gas flow in the main gas pipeline.

Utility Model Essence

The subject of a utility model is a device for measuring flow in a main gas pipeline, comprising a multichannel ultrasonic flow transducer integrated in the housing and designed to be connected to a processing unit, while the body of a multichannel ultrasonic flow transducer is made of a pipe whose diameter coincides with the diameter of the main gas pipeline and has coaxial welded joints with inlet and outlet straight sections of the main gas pipeline, characterized in that it is multi-channel ultrasonic flow transmitter is covered with a hard surface of the housing shroud.

The technical result of the utility model is to increase the measurement accuracy to the necessary for commercial metering of gas flow in the main gas pipeline.

Utility Model Implementation

The figure shows an example implementation of the inventive device.

A multichannel ultrasonic flow transducer is built into the housing 1, which is made of a pipe whose diameter coincides with the diameter of the main gas pipeline and has coaxial welded joints 2 and 3 with inlet 4 and 5 straight sections of the main gas pipeline. The lengths of the straight sections 4 and 5 are at least 15D and 2D, respectively, where D is the nominal internal diameter of the main gas pipeline and the corresponding internal diameter of the housing 1. If the main gas pipeline, including sections 4 and 5, passes underground, the claimed device is also located below the level of the earth's surface in the well, providing access to the device during operation. The dotted line shows the surface of the earth and the underground contours of such a well are outlined.

A multichannel ultrasonic flow transducer may contain, for example, eight pairs of reversible ultrasonic transducers 6 mounted using bosses around the perimeter of the housing 1 and forming eight chordal measuring channels. The chordal measuring channels are located along four channels in two mutually perpendicular planes, inclined to the axis of the housing 1 at an angle of 45 °. From the surface of the housing 1, a multi-channel ultrasonic flow transducer is covered by a rigid bandage 7 in the form of a shell.

The primary transducers 6 are equipped with leads 8 and 9 for connection to an electronic processing unit (not shown in the figure) and operate under its control.

The device operates as follows.

The reversible transducers 6 of each chord channel act alternately as transmitters and receivers of ultrasound. The location of the measuring channels in a plane inclined at an angle of 45 ° to the axis of the housing 1 allows each channel to measure time and (based on the known length L _{i of the} corresponding chord channel) the ultrasound propagation velocity in and against the gas flow. The difference in these velocities determines the local gas flow velocity in each i-th channel, and then the average (integral) velocity V of the gas flow through the section of the housing 1. Using several chord channels allows one to take into account the non-uniformity of the velocity profile over the gas flow section and calculate it with the necessary accuracy integral speed.

Q is the volumetric flow rate as a product of the integrated flow rate V and the square inner cross section of the body 1 of the formula Q = VπD ^2/4.

Groups of four chordal channels located in the same plane can work independently in duplication or backup mode.

As the studies showed, an increase in the number of chordal measuring channels of an ultrasonic flow transducer installed between two straight sections of a sufficient length of the main gas pipeline can effectively reduce the error in determining the average velocity V of the flow caused by the irregularity of the velocity profile. However, with an increase in the diameter D over 700 mm, the error significantly increases due to deviations of the geometric parameters (L _i and D) from the nominal values due to vibration of the housing 1 during the passage of the gas stream. For example, in the well-known Hyperflow-US device of the “T” design, designed for technological metering in large diameter gas pipelines, this error is 1.35-1.60%, which is unacceptable for commercial metering of gas consumption [product catalog of a research and production company "Pennant", an electronic resource http.//www.npovympel.ru].

A rigid bandage 7 in the form of a shell can significantly reduce these deviations and, accordingly, reduce their influence on the results of determining the flow rate. The necessary rigidity of the brace 7 is ensured by calculating its structural parameters (internal and external diameters) and selecting the characteristics of the material (for example, steel) so that the total relative error in determining the flow rate Q, including components due to errors in the determination of the integral velocity V and the internal cross-sectional area of the housing 1, did not exceed 0.8% for all impacts arising during the operation of the main gas pipeline.

The coverage of the multichannel ultrasonic flow transducer from the surface of the housing 1 with a rigid bandage made it possible to increase the accuracy of the flow measurement to that necessary for commercial metering of gas flow in the main gas pipeline.

The experimental error in measuring the flow rate did not exceed 0.8%, which allows the use of the inventive device as a single-line device for commercial metering of gas flow in large gas pipelines of large diameter.

Claims (1)

A device for measuring flow in a main gas pipeline containing a multichannel ultrasonic flow transducer integrated in the housing, designed to be connected to a processing unit, while the body of a multichannel ultrasonic flow transducer is made of a pipe whose diameter coincides with the diameter of the main gas pipeline and has coaxial welded joints with a supply and discharge direct sections of the main gas pipeline, characterized in that the multichannel ultrasonic transducer ra the descent is covered with a hard bandage from the surface of the housing.

Images