CN114323176A - Mass flow measuring method for large pipeline component-variable gas - Google Patents

Abstract

The invention discloses a method for measuring mass flow of large-pipeline variable-component gas, which comprises the following steps of: the method comprises the following steps: introducing mixed component gas into the reactor; step two: measuring differential pressure and volume flow per unit time; step three: substituting the obtained data into a calculation formula corresponding to the mass flow, and obtaining an expression of the real-time density and a calculation formula of the mass flow according to the conservation of mass; step four: leading the flow into a flow integrating instrument, calculating and displaying the result; the invention redesigns the measuring method of the quality of the large-caliber variable-component mixed gas in principle, integrates the differential pressure transmitter and the precession volume flowmeter, and obtains the real-time density and the mass flow of the mixed component gas by utilizing the difference of the two measuring principles, thereby breaking the technical monopoly of the measuring field, greatly reducing the production cost, having no relation between the implementation scene of the measuring method and the diameter of the pipeline, and having high adaptability and application prospect.

Description

Measurement method of gas mass flow rate of variable composition in large pipeline

technical field

The invention relates to the field of gas quality measurement, in particular to a method for measuring gas mass flow with variable components in a large pipeline.

Background technique

In the field of gas measurement, the pressure or flow rate of the gas is generally measured, while the gas quality measurement methods are relatively few. In the case of large-diameter pipelines and variable gas components, only the GE ultrasonic flowmeter can achieve accurate measurement. For the purpose of measurement, it obtains the molecular weight of the medium by measuring the sound velocity of the medium and using the database that comes with the meter, and then obtains the mass of the corresponding mixed gas. It is often used for the mass flow measurement of acid gas in the sulfur plant, and is also used for natural gas and torches. The mass flow measurement of combustible gas mixtures such as gas and gas, but its cost is too high, and it is difficult to popularize and apply on a large scale. For this reason, we propose a large pipeline variable composition gas mass flow measurement method.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a method for measuring the mass flow of gas with variable components in a large pipeline, which adopts a principle different from that of a GE ultrasonic flowmeter to realize the measurement of the quality of mixed gas with variable components in a large pipeline.

The technical problem solved by the present invention is:

How to obtain the real-time density and mass flow of mixed component gas by integrating the differential pressure transmitter and the precession volume flowmeter, and use the difference in the measurement principles of the two to solve the complex principle of the existing technology and the cost of introducing equipment high question.

The present invention can be realized through the following technical solutions: a method for measuring the mass flow of gas with variable components in a large pipeline, the measuring method is realized based on a precession dual-parameter vortex flowmeter, and specifically includes the following steps:

Step 1: introduce a mixed component gas composed of more than one gas into the body of the precession dual-parameter vortex flowmeter;

Step 2: measure the differential pressure between the two detection points of the spinner through the differential pressure transmitter, and measure the volume flow per unit time through the meter body through the precession volume flowmeter;

Step 3: Substitute the data obtained by the differential pressure transmitter and the precession volume flowmeter into the corresponding mass flow calculation formula, and obtain the real-time density expression according to the mass conservation, and then obtain the mass flow calculation formula and its related variable factors;

Step 4: Import the calculation formula of mass flow into the flow totalizer, and the flow totalizer will calculate and display the result.

A further technical improvement of the present invention is that: the precession dual-parameter vortex flowmeter uses the existing physical model of the precession vortex flowmeter to carry out three-dimensional modeling, and the key dimension data of the precession vortex flowmeter is adjusted. Including inlet and outlet diameter, shrinkage ratio, included angle of shrinking section, included angle of expanding section and included angle of spinner blade.

A further technical improvement of the present invention is that the variable factors of the mass flow include the differential pressure at the detection point and the operating frequency of the precession signal detection head, other related parameters are calibrated values, and the mass flow has nothing to do with the diameter of the pipeline for transporting the fluid.

A further technical improvement of the present invention is that: the differential pressure transmitter converts the differential pressure into a differential piezoelectric signal, and is introduced into the flow totalizer together with the pulse signal output by the precession volume flowmeter. The pulse signal obtains the differential pressure at the detection point and the operating frequency of the precession signal detection head respectively.

A further technical improvement of the present invention is: the calibration of the relevant parameters is obtained by obtaining corresponding data at a given temperature, pressure and gas composition ratio for many times in a laboratory environment, and obtaining the corresponding data through data volatility analysis and mean value calculation.

A further technical improvement of the present invention is that the gas component ratio of the mixed component gas is dynamically changed.

Compared with the prior art, the present invention has the following beneficial effects:

The invention redesigns the measurement method of the mass of the large-diameter variable-component mixed gas in principle. The real-time density and mass flow of the mixed component gas breaks the technical monopoly in this field of measurement and greatly reduces the production cost, and the implementation scene of the measurement method mentioned in the present invention has nothing to do with the diameter of the pipeline, and has a high adaptability. compatibility and application prospects.

Description of drawings

In order to facilitate the understanding of those skilled in the art, the present invention will be further described below with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of the device structure of the present invention.

In the figure: 1. Meter body; 2. Spinner; 3. Differential pressure transmitter; 4. Negative pressure inlet; 5. Positive pressure inlet; 6. Precession signal processor; 7. Precession signal detection head; 8. Flow totalizer.

Detailed ways

In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific embodiments, structures, features and effects of the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments.

Please refer to Figure 1. The method for measuring gas mass flow with variable components in large pipelines is based on a precession dual-parameter vortex flowmeter, which includes a precession volume flowmeter and a differential pressure transmitter 3 The assembly consists of two parts. The precession volume flowmeter includes a meter body 1. The inside of the meter body 1 is fixed with a spinner 2. The outer side of the meter body 1 is provided with a positive pressure inlet 5 and a negative pressure inlet 4. The meter body 1 There is a differential pressure transmitter 3 directly above the differential pressure transmitter 3. The two pressure taking pipes of the differential pressure transmitter 3 are sealed with the positive pressure lead port 5 and the negative pressure lead port 4 respectively, and the two pressure taking pipes are connected to the meter body 1. It should be noted that the positive pressure inlet 5 and the negative pressure inlet 4 are respectively arranged on both sides of the spinner 2, and the output end of the differential pressure transmitter 3 is electrically connected with a flow totalizer 8 The middle section of the meter body 1 is provided with a precession volume flowmeter. The precession volume flowmeter includes a precession signal detection head 7 and a precession signal processor 6. One end of the precession signal detection head 7 is arranged inside the meter body 1 , the other end of the precession signal detection head 7 passes through the precession signal processing circuit and the flow totalizer 8 .

The above-mentioned precession dual-parameter vortex flowmeter is used to implement the measurement method, which is as follows:

Step 1: introducing a mixed component gas in which two or more gases are mixed into the watch body 1, and the mixing ratio of each gas component in the mixed component gas is variable;

Step 2: The mixed component gas enters the meter body 1, and a vortex is generated through the spinner 2 to form a pressure drop. The positive pressure inlet 5 and the negative pressure inlet 4 are respectively measured. The pressure value of the second detection point is marked as the first detection pressure P ₁ and the second detection pressure P ₂ respectively, and the difference calculation is performed between the two to obtain ΔP=P ₁ -P ₂ ;

Step 3: Through the differential pressure ΔP at the detection point obtained in Step 2, the differential pressure transmitter 3 is essentially a differential pressure flowmeter. For the data measurement stage of the differential pressure transmitter 3, it is based on the working principle of the differential pressure flowmeter. , substitute the differential pressure ΔP at the detection point into the differential pressure mass flow derivation formula:

Among them, q _m1 represents the mass flow corresponding to the differential pressure at the detection point, and the unit is kg/s;

ρ represents the real-time fluid density of the mixed component gas in the measurement interval of the differential pressure transmitter 3, and the unit is kg/m ³ ;

α represents the flow coefficient. The flow coefficient refers to the constant pressure of the pipeline in unit time and under the test conditions. The volume flow or mass flow of the pipeline medium flowing through the valve defines the flow capacity of the corresponding pipeline and valve. The larger the flow coefficient, the more the valve. Or the stronger the fluid passability of the pipeline, the specific value of α is obtained by calibrating the standard data in the test environment;

Step 4: Calculate and analyze the mass flow of the mixed component gas in the measurement interval of the precession volume flowmeter, mark the volume flow measured by the precession volume flowmeter as q _v , and substitute it into the precession mass flow derivation formula middle:

Among them, q _m2 represents the mass flow through the precession signal detection head 7, and the unit is kg/s;

f represents the operating frequency of the precession signal detection head 7, in Hz/s;

ρ represents the real-time fluid density of the mixed component gas passing through the precession signal detection head 7, and the unit is kg/m ³ ;

K represents the meter coefficient of the precession volume flowmeter, that is, the number of signal pulses sent out when the unit volume flow flows through the flowmeter, and the unit is Hz/m ³ ;

Step 4: According to the formulas in Steps 2 and 3, the gas mass flow through the same pipeline in unit time follows the law of mass conservation, so that q _m1 =q _m2 , namely:

进而得出单位时间内通过旋进双参量旋涡流量计的质量流量，将通过旋进双参量旋涡流量计的实时密度ρ代回到步骤四中的公式中，得到Thereby calculating the real-time density through the precession two-parameter vortex flowmeter

Then, the mass flow through the precession dual-parameter vortex flowmeter per unit time is obtained, and the real-time density ρ passing through the precession dual-parameter vortex flowmeter is substituted back into the formula in step 4 to obtain

According to the above formula, the mass flow q _m has nothing to do with the pipe diameter of the pipeline for transporting the fluid, but is only related to the differential pressure of the detection points on both sides of the spinner 2 and the operating frequency of the precession signal detection head 7. Other parameters in the formula can be Through the calibration in the laboratory test environment, the combination of the precession volume flowmeter and the differential pressure transmitter 3 is used to measure the real-time density and mass flow of the mixed component gas when the gas components are unknown;

The calibration of relevant parameters is obtained by obtaining corresponding data at a given temperature, pressure and gas composition ratio for many times in the laboratory environment, and the corresponding data is obtained through data volatility analysis and mean calculation. The processing methods include regression, standard deviation and weighted average. calculate.

It should be noted that if the gas composition is stable, the density of the gas is fixed under certain temperature and pressure conditions, and the temperature and pressure of the gas are compensated to keep the data stable, then the mass flow rate can be calculated and measured, for For variable composition gas, even if the temperature and pressure compensation method is used to keep the temperature and pressure stable, the density of the gas will change in a large range, so the conventional measurement method cannot measure the mass flow of the variable composition gas;

The realization of the measurement method is based on the three-dimensional modeling of the physical model of the mature DN350 precession vortex flowmeter in the prior art, and the fluid force field analysis is carried out on the three-dimensional model, and the key dimensions of the precession vortex flowmeter are parameterized using the analysis results Correction, such as: inlet and outlet diameter, shrinkage ratio, included angle of shrinking section, included angle of expanding section, and included angle of spinner blades, etc., to obtain DN700 precession vortex flowmeter, and the gas flows in turbulent flow inside the precession vortex flowmeter.

The above-mentioned data processing process is imported into the flow totalizer 8 in the form of a program, and the differential piezoelectric signal output by the differential pressure transmitter 3 and the pulse signal output by the precession volume flowmeter are imported into the flow totalizer 8, and simultaneously. Input the relevant parameters of the calibration, and the flow totalizer 8 directly displays the corresponding data such as volume flow, real-time density and mass flow, etc., and the staff uses the displayed data to guide the production.

The above descriptions are only preferred embodiments of the present invention, and do not limit the present invention in any form. Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art , without departing from the scope of the technical solution of the present invention, when the technical content disclosed above can be used to make some changes or modifications to equivalent embodiments of equivalent changes, as long as it does not depart from the technical solution content of the present invention, according to the technical solution of the present invention Substantially any simple modifications, equivalent changes and modifications made to the above embodiments still fall within the scope of the technical solutions of the present invention.

Claims (6)

1. The mass flow measuring method of the large-pipeline variable-component gas is characterized in that the measuring method is realized based on a precession double-parameter vortex flowmeter and specifically comprises the following steps:

the method comprises the following steps: introducing mixed component gas consisting of more than one gas into a meter body (1) of the precession double-parameter vortex flowmeter;

step two: measuring the differential pressure between two detection points of the screw driver (2) through a differential pressure transmitter (3), and simultaneously measuring the volume flow passing through the meter body (1) in unit time through a precession volume flowmeter;

step three: respectively substituting data acquired by the differential pressure transmitter (3) and the precession volume flowmeter into a calculation formula corresponding to the mass flow, and simultaneously obtaining an expression of real-time density according to mass conservation so as to obtain a calculation formula of the mass flow and related variable factors thereof;

step four: the formula for calculating the mass flow rate is introduced into a flow rate integrating meter (8), and the flow rate integrating meter (8) calculates and displays the result.

2. The method according to claim 1, wherein the precession dual parameter vortex flowmeter is three-dimensionally modeled using a physical model of an existing precession vortex flowmeter, and critical dimension data of the precession vortex flowmeter is adjusted according to a fluid force field analysis result, wherein the critical dimension data includes an inlet/outlet diameter, a contraction ratio, a contraction section included angle, an expansion section included angle, and a spinner blade included angle.

3. The method for measuring the mass flow of the large-pipeline variable-component gas as claimed in claim 1, wherein the variable factors of the mass flow comprise the differential pressure of a detection point and the working frequency of a precession signal detection head (7), other related parameters are calibrated values, and the mass flow is independent of the pipeline diameter of the transport fluid.

4. The mass flow measurement method of large-pipeline variable-component gas according to claim 1, characterized in that the differential pressure transmitter (3) converts differential pressure into a differential pressure electrical signal, and the differential pressure electrical signal and a pulse signal output by the precession volume flowmeter are led into the flow integrator (8), and the working frequency of the detection point differential pressure and the precession signal detection head (7) are respectively obtained according to the differential pressure electrical signal and the pulse signal.

5. The method for measuring the mass flow of the large-pipeline variable-component gas as claimed in claim 3, wherein the calibration of the relevant parameters is performed by obtaining corresponding data under the given temperature, pressure and gas component proportion for a plurality of times in a laboratory environment, and performing data fluctuation analysis and mean value calculation on the corresponding data.

6. The large pipe variable component gas mass flow measurement method of claim 1, wherein the gas component ratio of the mixed component gas is dynamically varied.

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