RU2311633C1 - Method of determination of flow mode of multiphase flux in pipeline - Google Patents

Abstract

FIELD: methods of determination of flow modes of multiple-phase flux in pipelines.

SUBSTANCE: group of converters is mounted onto external surface of pipeline for sonic test in perpendicular to longitudinal axis of pipeline of multiple-phase flux by ultrasonic oscillations by means of group pf converters. Amplitude and run time of passed-through and reflected ultrasonic signals are measured. Then signals are transformed into digital form. Digitized values are subject to comparing with available (achieved in advance) reference values of digitized ultrasonic signals. Those reference values of ultrasonic signals correspond to different modes of flow of multiple-phase fluxes. Mode of flow of multiple-phase flux is found from results of comparison. Before starting sonic test, data on temperature of multiple-phase flux is collected as well as data on pressure in pipeline and on angle of slope of pipeline in relation to horizontal surface to determine group pf standard values. Additional group of converters is mounted, which group is disposed along pipeline outside it onto wall of pipeline. Both groups of converters receive and register amplitudes and run times of passed-through and reflected signals and transform them into digital form being convenient for processing. Then those values are subject to comparison with set of available reference values and mode of flow of multiple-phase flux is determined on base of comparison.

EFFECT: improved precision.

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Description

The invention relates to instrumentation and can be used to determine the type of multiphase flow in the pipeline during its operation.

A known method of monitoring fluid discontinuities in a pipeline (A.S. 254865 USSR, IPC G01N 29/00, publ. 1969. A method for controlling fluid flow discontinuities in a pipeline), which consists in sounding the liquid in a plane perpendicular to the longitudinal axis of the pipeline, by ultrasonic vibrations, measuring the amplitudes of the received signals, which determine the discontinuities of the fluid flow.

The disadvantage of this method is its low information content, low accuracy, because the flow is sounded only in one direction, the reflected pulses are not taken into account, and also the characteristics of the pulses are not taken into account.

A known method of controlling flow discontinuities (A.S. 1631401 USSR, IPC 5 G01N 29/00, published 1991. - Method for controlling fluid flow discontinuities in a pipeline), which consists in the fact that the pipeline with a controlled medium is sounded by ultrasonic pulses in two mutually perpendicular directions, the pulses passing through the medium are recorded, their amplitudes are recorded, the pulses reflected from the phase boundary are also taken, their amplitudes and travel times are measured, and the gas phase concentration and flow regime n outflow.

The disadvantage of this method is its low information content, low accuracy and low degree of automation.

A known method of controlling a multiphase flow in a pipeline (Pat. 2198397 7 G01N 29/02, publ. 02/10/2003. - A method of controlling a multiphase flow in a pipeline), which consists in sounding a multiphase flow by ultrasonic vibrations, signals and echo pulses transmitted through the flow are recorded, reflected from the discontinuities of the multiphase flow, measure their amplitudes and arrival times, which determine the nature of the multiphase flow. Known features of this method is that the group of converters is arranged around the circumference of the pipeline in one plane of its cross section, at the same time, the amplitudes and travel times of transmitted and reflected signals are received and recorded, converted into a digital form convenient for processing, and compared with the microprocessor in the flash memory module with a set of digital standards corresponding to different multiphase flows, and the nature of the multiphase flow is determined by comparison.

The disadvantage of this method is its low accuracy, because many factors affecting the determination of the flow regime in the pipeline are not taken into account.

The task to which the claimed technical solution is directed is to increase the accuracy in determining the regime of fluid flow in the pipeline by taking into account additional parameters, as well as increasing the information content.

When implementing the invention, the task is solved by achieving a technical result, which consists in increasing the accuracy and information content when determining the flow regime in the pipeline due to the fact that additional factors affecting the nature of the multiphase flow are taken into account (flow temperature, pressure in the pipeline, angle of the pipeline relative to the horizontal surface). These additional factors significantly affect the mode of multiphase flow in the pipeline. For example, temperature affects the viscosity of a fluid in a pipeline, pressure in a pipeline affects the quality of the flow, and the angle of inclination of the pipeline relative to a horizontal surface affects not only the flow regime in the pipeline, but also the ability to change the current flow regime. Without taking these parameters into account, a correct determination of the multiphase flow regime in a pipeline would be possible only within certain boundaries of the flow temperature, pressure in the pipeline, and a certain angle of inclination of the pipeline. Given these parameters, in addition to increasing the accuracy in determining the flow regime in the pipeline, we significantly expand the application of this method of multiphase flow control in the pipeline.

The specified technical result is achieved by the fact that the method for determining the multiphase flow pattern in the pipeline includes installing a group of transducers on the outer surface of the pipeline to sound perpendicular to the longitudinal axis of the multiphase flow pipeline by ultrasonic vibrations using transducer groups, fixing the amplitude and travel time of transmitted and reflected ultrasonic signals, converting digitally, comparing the obtained digitized values with the available (pre double received) reference values of the digitized ultrasonic signals, and these reference values of ultrasonic signals correspond to different flow regimes of multiphase flows, the determination of the multiphase flow flow regime by comparison. The peculiarity is that before the sounding of the flow, data on the temperature of the multiphase flow, pressure in the pipeline and the angle of inclination of the pipeline relative to the horizontal surface are collected to determine the group of reference values, an additional group of converters is installed, which are placed along the pipeline outside on the wall of the pipeline, while both groups of converters simultaneously receive and record amplitudes and travel times of transmitted and reflected signals, convert them to a digital form suitable for processing and compared with the existing set of pre-obtained reference values corresponding to different flow regimes of multiphase flows, and from the results of the comparison, the flow regime of the multiphase flow is determined.

Reference values are determined previously, and the conditions under which the reference values are determined should be as close as possible to the operating conditions of the pipeline, in relation to which this method will be used.

Improving accuracy is also achieved due to the fact that two groups of transducers participate in the sounding. A group of transducers is a source of ultrasonic vibrations, as well as several receivers of this type of oscillation. The first group of transducers sounds flow perpendicular to the longitudinal axis of the pipeline, and the second group of transducers sounds flow along the longitudinal axis of the pipeline. Moreover, with longitudinal sounding, the path traveled by an ultrasonic wave from the emitter to each receiver is always different. Passing a longer path, the ultrasonic wave spends a longer time, i.e. the influence time of a multiphase flow on an ultrasonic wave increases with increasing path, so the receiver will receive a sound wave maximally altered by a multiphase flow, and changes in the ultrasonic wave directly depend on the composition and flow regime of the multiphase flow. Based on this, we will have a more accurate picture of the multiphase flow regime in the pipeline.

Figure 1 schematically shows a system for implementing a method for controlling a multiphase flow in a pipeline, which contains a device for measuring the temperature 1 of the flow, a device for determining the pressure 2 inside the pipeline and a device for determining the angle of inclination 3 of the pipeline relative to the horizontal surface, the second group of transducers 4 (sounds multiphase flow along the longitudinal axis of the pipeline), the first group of transducers 5 (the flow sounds perpendicular to the longitudinal axis of the pipeline), direction sounding of 6 multiphase flow by the second group of transducers, direction of sounding of 7 multiphase flow by the first group of transducers, direction of motion 8 of the multiphase flow, central axis 9 of the pipeline, pipeline 10.

Figure 2 presents a diagram for implementing a method of monitoring multiphase flow in a pipeline, which includes two emitters 11, 12 and two rows of receivers 13, 14. The emitter 11 and a number of receivers 13 form the first group of converters, which sounds multiphase flow perpendicular to the longitudinal axis the pipeline. The emitter 12 and a number of receivers 14 form a second group of converters, which sounds the flow along the longitudinal axis of the pipeline. The emitters 11, 12 and receivers 13, 14 are located outside on the walls of the pipeline 10. The outputs of the receivers 13 are connected to the inputs of the analog memory unit and timers 15, and the outputs of the receivers 14 are connected to the inputs of the analog memory unit and timers 16. The outputs of blocks 15 and 16 are connected to the inputs switches 17 and 18, respectively. One of the outputs of the switches 17 and 18 is connected to the input of an analog-to-digital converter (ADC) 19, and the other to the input of random access memory (RAM) 20. The system includes a microprocessor module (MM) 21, the outputs of which are connected to the inputs of the analog memory blocks and timers 15 and 16, switches 17 and 18, analog-to-digital Converter 19, random access memory 20 and an ultrasonic signal generator (HUS) 22.

The microprocessor module 21 controls the operation of the listed circuit elements of figure 2 and performs data processing.

The method of controlling multiphase flow in the pipeline 10 is as follows. Information about the temperature 1 of the flow, pressure 2 inside the pipeline 10 and determining the angle of inclination 3 of the pipeline 10 relative to the horizontal surface is supplied to the inputs of the analog memory 16, where, under the control of the microprocessor module 21, the values of these parameters are fixed for the current survey cycle of the receivers 13, 14. Moreover, when the next survey cycle of the receivers 13, 14, information is also initially collected from devices for measuring the temperature 1 of the flow, pressure 2 inside the pipeline 10 and determining the angle of inclination 3 of the pipe rovoda 10 relative to the horizontal surface. Then, using the switch 18, the obtained analogue signals are transmitted for the values of the flow temperature, pressure inside the pipeline 10, and the angle of inclination of the pipeline relative to the horizontal surface to the analog-to-digital converter 19 in order to convert them into a proportional digital code. After that, the obtained digital codes go to random access memory (RAM) 20, where, under the control of the microprocessor module 21, a group of reference values of various multiphase flow modes is determined for a given flow temperature, pressure inside the pipeline 10 and the angle of inclination of the pipeline 10 relative to the horizontal surface.

Then, the ultrasonic signal generator 22 under the control of the microprocessor module 21 generates electrical pulses with a frequency of (1-2.5) MHz. These pulses arrive at the emitters 11 and 12, which form ultrasonic vibrations propagating through the walls of the pipeline 10 and the controlled medium is a multiphase flow. Using receivers 13 and 14, ultrasonic vibrations transmitted through a multiphase stream are received, which are fed to the inputs of the analog memory 15 and 16, respectively, where the maximum amplitudes and signal reception time are recorded by synchronization control signals from the microprocessor module 21. Switches 17 and 18 allow sequentially interrogate blocks of analog memory - timers 15 and 16 in order to convert analog signals into a proportional digital code using an analog-to-digital converter 19, and also sequentially transmit digital timer codes proportional to the time delays of the received signals in the random access memory (RAM) 20.

The identification of the flow regime and its features is carried out by the microprocessor module 21 according to the program stored in the flash memory of the module. Based on the fact that when comparing the identical values of any values, they relate as 1: 1, the definition of the flow regime is proposed using the following formula:

N = (λ + ψ) / 2λ,

where N is the convergence coefficient, λ is the reference value, ψ is the measured value.

Moreover, the closer the convergence coefficient N to unity, the more the flow regime of the investigated multiphase flow is closer to the flow regime at which this reference result λ was obtained.

The reference values of λ for comparison with the measured ψ are taken from a certain group of reference values. The selection of a group of reference values is carried out using the following parameters:

- flow temperature;

- pressure inside the pipeline;

- the angle of inclination of the pipeline relative to the horizontal surface.

The measured values of ψ are determined in the process of using this method.

When identifying, they are guided by the amplitudes of the received sound pulses, both transmitted through the controlled medium, and reflected from the interface (s), as well as the values of the measured travel times of these signals.

The definition of the multiphase flow mode is proposed to be carried out on the basis of the “voting” principle. “Voice” is the definition of the current mode of multiphase flow in a pipeline based on data received from one receiver, and the convergence coefficient N should be closest to unity. According to the data from each of the receivers 13 and 14 in the above-described way, using each formula, each receiver “votes” for one or another multiphase flow pattern in the pipeline 10. Next, the closest multiphase flow pattern is determined, the mode that scored the most “votes” is taken as the current mode of multiphase flow in the pipeline (all “voices” are equivalent and have the same weight).

The reference values of the parameters established earlier by the researchers empirically are noted depending on the multiphase flow regime (bubble, stratified, annular, reverse-annular, slug), as well as on the initial data (flow temperature, pressure in the pipeline and the angle of the pipeline relative to the horizontal surface) and stored in flash memory of the microprocessor module 21.

The method can be the basis for long-term monitoring of the pipeline. Using this method of controlling a multiphase flow in a pipeline, it is possible to build a system that calculates the predicted rate of internal corrosion of the pipeline. Based on this method, it is possible to conduct comprehensive diagnostics of already functioning pipelines, as well as to carry out work to optimize the functioning of pipelines. The method can be used at the design stages of pipelines as one of the criteria for choosing the most effective mode of operation of the pipeline, as well as when choosing the route of the pipeline on the ground. This method can be used as part of a parametric method for determining pipeline leaks.

Claims (1)

A method for determining the flow regime of a multiphase flow in a pipeline, including installing a group of transducers on the outer surface of the pipeline to sound perpendicular to the longitudinal axis of the multiphase flow pipeline by ultrasonic vibrations using transducer groups, fixing the amplitude and travel time of transmitted and reflected ultrasonic signals, converting them to digital form, comparing received digitized values with available (previously obtained) reference values ultrasonic signals, and these reference values of ultrasonic signals correspond to different modes of multiphase flow, determining the multiphase flow mode by comparing the flow, characterized in that before starting the sounding of the flow, data is collected on the temperature of the multiphase flow, the pressure in the pipeline and the angle of the pipeline relative to horizontal surface to determine the group of reference values, establish an additional group of converters, to a shelter is placed along the pipeline outside the pipeline wall, while both groups of transducers simultaneously receive and record the amplitudes and travel times of transmitted and reflected signals, convert them into a convenient digital form for processing, and compare them with an existing set of previously obtained reference values corresponding to different multiphase flow regimes flows, and the results of the comparison determine the flow regime of a multiphase flow.

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