RU2517764C1 - Method for measurement of multiphase flow rate and device to this end - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: method for measurement of a multiphase flow rate is based on introduction into the transported fluid flow of a measured amount of mechanical energy that compensates energy losses of the flow at the measurement area, at that forward velocity, rotation velocity or any other velocity of the propeller synchronised with the volumetric flow rate of the transported fluid is the primary signal at the flow rate measurement. The device for measurement of the multiphase flow rate consists of a single-screw machine, which screw serves as a propeller for uniform delivery of the measured amount of mechanical energy to the multiphase flow and a sensitive element of the measurement device, at that the primary circuit for regulation of the screw rotational velocity for the purpose of synchronisation with the volumetric flow rate of the transported fluid consists of a speed transducer, a frequency converter and a controller while the secondary given control circuit includes a differential pressure sensor, temperature sensors, a mathematical modelling unit and a flow rate recorder, the above control circuits are used for regulation of the screw rotational velocity, calculation and recording of the volumetric and mass rate of the transported fluid and its density.

EFFECT: reduction of measurement error, increase of the range of flow rate measurement for the transported fluid as justified by metrological parameters, increase of reliability and confidence level for measurement results.

2 cl, 1 dwg

Description

The method of measuring the flow rate of multiphase flows and a device for its implementation relate to flow measurement and can be used in various industries, for example: oil and mining, metallurgical, building materials, chemical, food, agricultural and others.

Known methods for measuring the flow rate of a multiphase flow using measuring the dynamic characteristics of a multiphase flow, characterized by a decrease in the flow energy by the fraction of the energy spent by the sensor to generate a primary signal about the flow rate, and this fraction depends on the type of flowmeter (see Kremlevsky P.P. Flow measurement multiphase flows. L .: Mechanical Engineering, 1982. S. 101).

A disadvantage of the known analogue of measuring the flow rate of a multiphase flow is either their complete unsuitability for measuring the flow rate of a multiphase flow, or a significant increase in the measurement error. The heterogeneity of the composition and physicomechanical properties of the multiphase flow leads to irregular spasmodic changes in the reaction of the sensitive elements of the flow meters based on this measurement method, which are not comparable with the actual flow rates.

Known methods for measuring the flow rate of multiphase flows based on various physical phenomena: thermal (see, for example, RF patent No. 2186343 dated 07/27/2002 / Pozdnyshev G.N., Manyrin V.N., Kalugin I.V., Sivakova T. G.) electromagnetic (see, for example, RF patent No. 2381457 dated 02/10/2010 / Welt I.D., Mikhailova Yu.V., Terekhina N.V.) optical, nuclear magnetic, ionization, and others (see Kremlin) PP Measurement of the flow rate of multiphase flows. L .: Mashinostroenie, 1982.), depending on the flow rate and arising as a result of continuous or periodic input of various types of en Ergii in the transported multiphase flow.

The disadvantages of the known analogues are a significant increase in the measurement error in the field of small and large flows, stepwise and significant distortion of thermal, electric, magnetic and other fields in the flow measurement zone due to contact with solid and gas inclusions of the multiphase flow.

The technical result, which is achieved by the claimed method of measuring the flow rate of a multiphase flow, is to extend the interval of application of the measurement method according to the composition and properties of the multiphase flow, increase the reliability and reliability of the measurement results, expand the metrologically justified measurement interval and reduce the measurement error in this interval, without a significant increase errors at the boundaries of this interval.

To achieve the specified technical result in the proposed method for measuring the flow rate of a multiphase flow from an independent source, a dosed amount of mechanical energy is introduced into the transported medium by the mover, which compensates for the energy loss of the flow in the measurement section, while translational, rotational or any other speed of the mover synchronized with the volumetric flow rate of the transported medium , is the primary signal when measuring flow.

The difference of the proposed method for measuring the flow rate from known analogues is that a propulsive amount of mechanical energy is introduced into the flow from an independent source, and the primary signal is the speed of the propulsion device, as a sensitive element, synchronized with the volumetric flow rate of the medium. Moreover, the uniformity of the mechanical energy of the flow and mechanical energy uniformly supplied to all phases of the flow from an independent source reduces the influence of the composition and physicomechanical properties of the multiphase flow on the measurement error of the flow rate as an integral sum of the linear velocities of individual particles of the flow.

Known single-screw machines, the screw of which can be an analog of a sensitive element of the proposed device for measuring the multiphase flow rate, for example, single-screw conveyors, feeders and dispensers (ed. Certificate of the USSR 128775, 195238, 222781, 555289, 964458; RF patents 2012527, 2046296, 2047103, 2312807 , 2340532, 2406978, Malikov S.P. et al. Scales and batchers, weight. M: Mashinostroenie, 1981, p. 94).

The closest in technical essence to the claimed device for measuring the flow rate of a multiphase flow is a screw conveyor, selected as a prototype (see RF patent 2312807, published December 20, 2007), comprising a housing with loading and unloading nozzles and a shaft with a screw located in the housing connected to driven.

A disadvantage of the known device is its unsuitability for measuring the flow rate of a multiphase flow.

To implement the method of measuring the flow rate of a multiphase flow, the inventive device for measuring the flow rate of a multiphase flow includes a single-rotor machine, as a mover and at the same time a sensitive element of the measuring device, equipped with an automatic system for controlling the rotational speed of the screw, measuring, calculating and recording the volumetric and mass flow rate of the transported medium and its density.

A single-screw machine, as a mover and at the same time a sensitive element of the measuring device, through a power drive from an independent source, introduces a metered amount of mechanical energy into the screw stream at which the rotational speed of the screw is synchronized with the volume flow rate of the multiphase flow. This synchronous rotational speed of the screw is the primary signal of the measuring device for calculating and recording the volumetric and mass flow rate of the transported medium and its density. The decisive condition for energy metering is the compensation of the flow energy loss at the measuring section of the pipeline at the installation site of the single-screw machine, therefore, in the measurement mode, the pressure drop at the input and output of the measuring section is close to zero, taking into account the calibration characteristics of the flow meter (does not exceed the specified error).

The design of the proposed device for measuring the flow rate of a multiphase flow and the principle of its operation are illustrated in figure 1. The multiphase flow measuring device includes a single-screw machine built into the pipeline with the transported medium, consisting of a housing (1) of loading (2) and unloading (3) pipes, a single-screw (4) driven by an electric motor (5) through a gearbox (6) with support on the bearing assembly (7).

The number of screw runs and other structural, technical and technological parameters of the proposed device for measuring multiphase flow depend on the composition, physico-mechanical properties and flow rate of the transported medium and are selected individually.

The multiphase flow rate measurement is provided by the following elements of the automatic system as part of the proposed multiphase flow rate device (Fig. 1): electric motor (5), tachometer (8), frequency converter (9), screw speed controller - controller (10), components the primary screw speed control loop defined by the mathematical modeling unit (14), the circuit including the differential pressure sensor (12), temperature sensors (13), the mathematical modeling unit (14) and the register flow rate (11), which is the secondary (master) circuit for controlling the rotational speed of the screw and, together with the primary circuit, forms an automatic system for measuring, calculating and recording the flow rate of the transported multiphase flow.

When the motor (5) is turned off, the transported medium flows freely through the channels of the fixed screw (4) due to the external transportation source with the corresponding maximum hydraulic resistance and pressure drop across the screw and, consequently, with the maximum energy loss of the multiphase flow in the measurement section. When starting the electric motor with increasing speed of rotation of the screw, the hydraulic resistance, pressure drop and energy loss of the multiphase flow in the measurement area decreases. At a certain point in time during acceleration, a measurement mode is achieved in which the differential pressure on the screw does not exceed a predetermined error taking into account the calibration characteristics of the measuring device. In this case, the rotational speed of the screw synchronized with the volumetric flow rate of the multiphase flow transported by an external source is used in the mathematical modeling unit (14) (Fig. 1) to calculate the volumetric and mass flow rate of the transported medium and its density. Then, with the frequency set by the mathematical modeling unit (14), depending on the dynamic characteristics of the multiphase flow, the measured parameters and calculated values of the volumetric and mass flow rate of the transported medium and its density are transmitted to the flow recorder (11) (Fig. 1) for storage and delivery upon request.

The multiphase flow rate measurement mode is constantly supported by a two-circuit automatic control system for the continuous measurement of the screw rotation speed, calculation and recording of the volume and mass flow rates of the multiphase flow and its density.

The calculation of the desired parameters of the multiphase flow is performed in the mathematical modeling block (14) using any selected mathematical model

Q = Q (N _P, P), M = Q $$\rho =\rho (P),\left(\mathrm{one}\right)$$

where ρ is the average density of the transported medium, Q is the volumetric flow rate of the transported medium, M is the mass flow rate of the transported medium, Np is the rotational speed of the screw in the measurement mode, P is the vector of the parameters of the transported medium that determines its physical and mechanical properties: compression, rheological, cohesive and adhesive.

For the calculation, the simplest linearized form of models can be used (1)

$$\text{Q}=\text{k (P)}\cdot \text{Np}\text{,}\text{(2)}$$

where k (P) is the flow coefficient that determines the dependence of the volumetric flow rate on the vector of parameters (P) of the transported medium.

Mass flow rate and multiphase flow density are calculated similarly to (1). The choice of the mathematical model (1) or (2) depends on the composition and physico-mechanical properties of the transported medium, the required measurement error of the flow rate, and the technical capabilities of the mathematical modeling unit when implementing the model.

The present invention reduces the measurement error by up to five times, increases the metrologically justified measurement interval of the flow rate of the transported medium up to two times without significantly increasing the error at the boundaries of this interval, extends the interval of application of the measurement method in terms of composition and physico-mechanical properties of the multiphase flow, increases the reliability and reliability of the measurement results .

So, for example, for a flowmeter with a screw diameter of 50 mm, when measuring the flow rate of a model three-phase flow in the range of ± 80% of the nominal value, the error reduction on average is 4.5 times compared to the electromagnetic RISE-ERSV flowmeter.

The proposed method and device for measuring the flow rate of a multiphase flow can be used to measure the flow rate of raw materials, semi-finished products, products and wastes in the form of suspensions, emulsions and their mixtures in various industries, for example, oil-producing (emulsions and suspensions in the production of highly viscous and depleted formations pumped with a vapor-air mixture ) mining (pulp of minerals), metallurgical (ore pulp and sludge), building materials (pulp and sludge from oil refining and metallurgy), chemical (emulsion, pool Flakes and sludges in the enrichment of raw materials, extraction and production of a product, for example, catalysts, sorbents, etc.), food (emulsions and suspensions in the production of intermediates and dry concentrates), agricultural (emulsions and suspensions in the production of animal feed, organic fertilizers, macroencapsulated seeds etc.), wood processing (emulsions and suspensions in the production of wood-based plastics), mechanical engineering (composite materials) and other industries.

Claims (2)

1. A method of measuring the flow rate of a multiphase flow, comprising supplying an energy from an independent source to the transported medium to generate a primary signal that determines the flow rate resulting from the conversion, characterized in that in a multiphase flow of the transported medium by the mover a metered amount of mechanical energy, compensating for the energy loss of the flow in the measurement area, while the translational, rotational or any other speed of the propulsion device, synchronized with the volumetric flow rate of the transported medium, is the primary signal when measuring the flow rate. 2. The device according to claim 1, includes a single-rotor machine comprising a housing with loading and unloading nozzles and a shaft with a screw located in the housing connected to the drive, characterized in that the screw is the mover for uniformly supplying a dosed amount of mechanical energy to the multiphase flow and at the same time serves as a sensitive element of the measuring device, the primary screw speed control loop for synchronization with the volumetric flow rate of the transported medium consists of a tachometer, frequency converter and controller, and the secondary control control loop in differential pressure sensor, temperature sensors, mathematical modeling unit and recorder p descent is used to control the speed of rotation of the screw, as well as calculation and storage volume and mass flow of the transported medium and its density.