Method for improving accuracy of pitot flowmeter based on segmented correction

Abstract

The invention relates to the technical field of industrial automation instruments, in particular to a method for improving the accuracy of a pitot flowmeter based on segmented correction. Comprising the following steps: calculating a medium flow velocity through a medium flow velocity calculation formula according to a differential pressure signal detected by a pitot flowmeter; determining a medium flow calculation formula according to the medium flow velocity; according to the medium flow velocity, determining a pitot flowmeter test point coefficient corresponding to the segmented medium flow velocity; and calculating the medium flow according to the medium flow calculation formula and the pitot flowmeter test point coefficient corresponding to the segmented medium flow velocity. According to the method, the segmented medium flow velocity is matched with the corresponding pitot flowmeter test point coefficient, the coefficient difference under different flow velocities is adapted, the problem of metering deviation of an existing fixed coefficient under the working conditions of large blast furnace gas consumption fluctuation amplitude and low flow velocity is solved, and the flow measurement accuracy is improved.

Description

Technical Field

[0001] This invention relates to the field of industrial automation instrumentation technology, and in particular to a method for improving the accuracy of a Pitot flow meter based on segmented correction. Background Technology

[0002] Metering of blast furnace gas in steel enterprises is a key aspect of energy management in blast furnace production. Currently, insertion-type Pitot flow meters, which are easy to maintain, are commonly used for gas flow measurement.

[0003] The standard insertion-type Pitot flowmeter used for blast furnace gas metering is a point velocity flowmeter. The measuring rod of the standard insertion-type Pitot flowmeter is inserted into the center of the pipe. The flow-facing side has only one measuring hole located at the center of the pipe to measure the total pressure at the center point. The static pressure tap on the measuring surface of the probe measures the static pressure of the fluid. The measuring tube transmits the differential pressure signal formed by the total pressure and the static pressure. The output is after passing through a differential pressure transmitter. This flow meter needs to be used with a differential pressure transmitter and a flow display instrument. The working principle is as follows: by using the difference between the total pressure and static pressure of the fluid, combined with the definite numerical relationship between the two and the flow velocity of the fluid being measured, the fluid velocity is calculated through the differential pressure signal, and then the fluid flow rate is obtained.

[0004] In the metering scenario of blast furnace gas in steel enterprises, blast furnace gas contains water and dust, the pipe diameter is large, and the gas consumption fluctuates greatly, with a high proportion of low flow rate conditions. Historical calibration data of Pitot flowmeters revealed differences in the test point coefficients corresponding to different flow rates; the lower the flow rate, the larger the test point coefficient, with a deviation of up to 19.7% between the maximum and minimum flow rates. Furthermore, in existing technologies, Pitot flowmeter technical documentation only provides a single, fixed test point coefficient, which cannot be adjusted according to flow rate changes during flow calculation. Therefore, when the gas consumption is low, the actual test point coefficient corresponding to low flow rates does not match the fixed coefficient, leading to deviations in flow measurement results and a common problem of underestimation. Summary of the Invention

[0005] In view of this, the purpose of this invention is to propose a method for improving the accuracy of Pitot flow meters based on segmented correction, so as to solve the problem of metering deviation when Pitot flow meters use fixed test point coefficients under conditions of large fluctuations in blast furnace gas consumption and low flow rate.

[0006] To achieve the above objectives, the technical solution adopted by this invention is: a method for improving the accuracy of a Pitot flow meter based on segmented correction, comprising the following steps:

[0007] S1. Calculate the medium velocity using the medium velocity calculation formula based on the differential pressure signal detected by the Pitot flow meter.

[0008] S2. Determine the formula for calculating the flow rate of the medium based on the medium flow velocity.

[0009] S3. Based on the medium flow velocity, determine the test point coefficient of the Pitot flowmeter corresponding to the segmented medium flow velocity.

[0010] S4. Calculate the medium flow rate according to the medium flow rate calculation formula and the test point coefficient of the Pitot flowmeter corresponding to the segmented medium flow velocity.

[0011] Preferably, the formula for calculating the medium flow velocity is: ,in, It is the flow velocity of the medium, and the unit is meters per second (m / s). It is a constant calculated based on the outflow coefficient, expansion coefficient, etc. in the technical documentation of the Pitot flow meter; It is the differential pressure signal detected by the Pitot flow meter; The density of the medium is determined according to the technical documentation of the Pitot flow meter or by direct detection using a density sensor.

[0012] Preferably, the formula for calculating the medium flow rate is: Where Q is the medium flow rate; It is the pipe diameter, determined using high-precision measuring tools; This is the test point coefficient of the Pitot flowmeter, obtained through laboratory calibration of the Pitot flowmeter, and can be found in the Pitot flowmeter calibration report. ; It is the pipeline velocity distribution coefficient, which characterizes the spatial distribution of velocity within a pipeline. It is determined through velocity profile experiments based on parameters such as pipeline flow regime and roughness.

[0013] Preferably, the coefficient of the Pitot flowmeter test point corresponding to the segmented medium flow velocity is specifically: when v ≤ 0.5 m / s, When 0.5m / s < v ≤ 1m / s, When 1 m / s < v ≤ 2 m / s, When 2m / s < v ≤ 3m / s, When 3m / s < v ≤ 4m / s, When 4 m / s < v ≤ 5 m / s, When 5m / s < v ≤ 7m / s, When 7 m / s < v ≤ 10 m / s, When 10m / s < v ≤ 15m / s, When 15m / s < v ≤ 20m / s, When 20m / s < v ≤ 25m / s, When v > 25 m / s, .

[0014] The beneficial effects of this invention are as follows: by matching the test point coefficient of the corresponding Pitot flowmeter with the segmented medium flow velocity, the coefficient difference under different flow velocities is adapted, which solves the problem of metering deviation under the existing fixed coefficient with large fluctuation range of blast furnace gas consumption and low flow velocity conditions, and improves the accuracy of flow measurement. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only for this invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the structure of the present invention;

[0017] Figure 2 This is a schematic diagram of the logic flow for calculating and outputting medium flow rate based on compensation correction according to the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be noted that, unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains.

[0019] like Figure 1 , Figure 2 As shown, a method for improving the accuracy of a Pitot flow meter based on segmented correction includes the following steps:

[0020] S1. Calculate the medium velocity using the medium velocity calculation formula based on the differential pressure signal detected by the Pitot flow meter.

[0021] Pitot flow meters are a type of differential pressure flow meter. The flow velocity of the measured medium can be calculated from the differential pressure signal detected by the Pitot flow meter. The formula for calculating the medium flow velocity is:

[0022] (1)

[0023] in, It is the flow velocity of the medium, and the unit is meters per second (m / s). It is a constant calculated based on the outflow coefficient, expansion coefficient, etc. in the technical documentation of the Pitot flow meter; It is the differential pressure signal detected by the Pitot flow meter; The density of the medium is determined according to the technical documentation of the Pitot flow meter or by direct detection using a density sensor.

[0024] S2. Determine the formula for calculating the flow rate of the medium based on the medium flow velocity.

[0025] The medium flow velocity calculated according to formula (1) The formula for calculating the flow rate of the medium is:

[0026] (2)

[0027] Where Q is the medium flow rate; It is the pipe diameter, determined using high-precision measuring tools; This is the test point coefficient of the Pitot flowmeter, obtained through laboratory calibration of the Pitot flowmeter, and can be found in the Pitot flowmeter calibration report. ; It is the pipeline velocity distribution coefficient, which characterizes the spatial distribution of velocity within a pipeline. It is determined through velocity profile experiments based on parameters such as pipeline flow regime and roughness.

[0028] S3. Based on the medium flow velocity, determine the test point coefficient of the Pitot flowmeter corresponding to the segmented medium flow velocity.

[0029] To solve for the medium flow rate in step S2 The test point coefficient of the Pitot flowmeter needs to be determined. The coefficients for the test points of the Pitot flowmeter corresponding to the segmented medium flow velocities are shown in the table below:

[0030]

[0031] S4. Calculate the medium flow rate according to the medium flow rate calculation formula and the test point coefficient of the Pitot flowmeter corresponding to the segmented medium flow velocity.

[0032] Taking the data measured by a Pitot flow meter as an example, its medium flow velocity Coefficient of test points for Pitot flowmeter The values ​​are shown in the table below:

[0033]

[0034] Substituting the values ​​from the table above into formula (2) allows us to calculate the flow velocities of different media. The measured flow rate of the medium is Q.

[0035] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

[0036] This invention aims to cover all such substitutions, modifications, and variations that fall within the scope of protection. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for improving the accuracy of a Pitot flow meter based on segmented correction, characterized in that, Includes the following steps: S1. Calculate the medium velocity using the medium velocity calculation formula based on the differential pressure signal detected by the Pitot flow meter. S2. Determine the formula for calculating the flow rate of the medium based on the medium flow velocity; S3. Determine the test point coefficient of the Pitot flowmeter corresponding to the segmented medium flow velocity based on the medium flow velocity. S4. Calculate the medium flow rate according to the medium flow rate calculation formula and the test point coefficient of the Pitot flowmeter corresponding to the segmented medium flow velocity.

2. The method according to claim 1, characterized in that, The formula for calculating the medium flow velocity is: ,in, It is the flow velocity of the medium, and the unit is meters per second (m / s). It is a constant calculated based on the outflow coefficient, expansion coefficient, etc. in the technical documentation of the Pitot flow meter; It is the differential pressure signal detected by the Pitot flow meter; The density of the medium is determined according to the technical documentation of the Pitot flow meter or by direct detection using a density sensor.

3. The method according to claim 1, characterized in that, The formula for calculating the medium flow rate is: Where Q is the medium flow rate; It is the pipe diameter, determined using high-precision measuring tools; This is the test point coefficient of the Pitot flowmeter, obtained through laboratory calibration of the Pitot flowmeter, and can be found in the Pitot flowmeter calibration report. ; It is the pipeline velocity distribution coefficient, which characterizes the spatial distribution of velocity within a pipeline. It is determined through velocity profile experiments based on parameters such as pipeline flow regime and roughness.

4. The method according to claim 1, characterized in that, The specific coefficients for the Pitot flowmeter test points corresponding to the segmented medium flow velocities are as follows: when v ≤ 0.5 m / s, When 0.5m / s < v ≤ 1m / s, When 1 m / s < v ≤ 2 m / s, When 2m / s < v ≤ 3m / s, When 3m / s < v ≤ 4m / s, When 4 m / s < v ≤ 5 m / s, When 5m / s < v ≤ 7m / s, When 7 m / s < v ≤ 10 m / s, When 10m / s < v ≤ 15m / s, When 15m / s < v ≤ 20m / s, When 20m / s < v ≤ 25m / s, When v > 25 m / s, .

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