A soft measurement method for gas flow of pipeline butterfly valve

Abstract

The present invention proposes a soft measurement method for gas flow of a pipeline butterfly valve. The method uses the pipeline gas flow and its corresponding valve opening and pre-valve pressure data collected in actual production. Based on the flow characteristics of the valve, the method centralizes the influence of valve opening and pre-valve pressure on pipeline gas flow through offline modeling, and establishes a relationship model between pipeline flow, valve opening and pre-valve pressure. The method does not require a traditional flow meter, and can achieve rapid prediction of pipeline gas flow. The calculation results of the present invention show that the actual value of the gas flow in the pipeline is very close to the predicted value of the present invention, which is of great significance for strengthening process supervision and control and reducing the complexity of measurement.

Description

Technical Field

[0001] The invention belongs to the technical field of flow soft measurement, and relates to a soft measurement method for gas flow of a pipeline butterfly valve. Background Art

[0002] Butterfly valves are a common flow control device for industrial pipelines, such as online control of coal gas and air flow in steel rolling heating furnaces. At present, flow measurement instruments are usually used for industrial pipeline flow detection. However, due to the influence of factors such as complex test conditions and aging of flow meters during actual operation, flow measurement instruments may be inaccurate and untimely when measuring flow. Under some working conditions, the device may not respond sensitively, and the flow measured by the flow meter may have a large error with the actual flow, which has a certain impact on process supervision and control. Summary of the invention

[0003] In order to solve the above technical problems, the purpose of the present invention is to provide a soft measurement method for the gas flow of a pipeline butterfly valve, which can determine the pipeline gas flow through the pressure before the valve and the valve position opening.

[0004] The present invention provides a soft measurement method for gas flow of a pipeline butterfly valve, comprising:

[0005] Step 1: Collect the measured data of pipeline gas flow and its corresponding valve opening and pressure before the valve measured by the traditional flow meter in the initial operation of actual production, and record and store them;

[0006] Step 2: Based on the collected measured data and the principle of fluid flow, the relationship between pipeline gas flow and valve front pressure is analyzed and obtained when the valve opening remains unchanged;

[0007] Step 3: Based on the collected measured data and the flow characteristics of the butterfly valve, the relationship between the pipeline gas flow and the valve opening is fitted when the pressure before the valve remains unchanged;

[0008] Step 4: According to the single influence relationship between the valve front pressure or valve opening on the pipeline flow obtained in step 2 and step 3, the relationship between the pipeline gas flow, valve opening and valve front pressure is constructed as a soft measurement model of pipeline butterfly valve gas flow;

[0009] Step 5: Input the real-time valve opening and valve front pressure in the production process into the soft measurement model to complete the real-time online soft measurement of pipeline gas flow.

[0010] In the soft measurement method of pipeline butterfly valve gas flow of the present invention, according to the collected measured data and the principle of fluid flow, it can be known in step 2 that when the valve opening remains unchanged, the pipeline flow and the pressure before the valve are linearly related, and the relationship is as follows:

[0011] Q(P)=QP (a+kP) (1)

[0012] Where, Q(P) is the pipeline gas flow rate when the valve opening remains unchanged, Q P is a constant term, k and a are coefficients, and P is the pressure before the valve. The relationship is determined by automatic fitting based on the measured reasonable data.

[0013] In the soft measurement method of pipeline butterfly valve gas flow of the present invention, the flow characteristic of the butterfly valve in step 3 is a fast-opening flow characteristic. According to the collected measured data and flow characteristics, when the pressure before the valve remains unchanged, the pipeline flow and the valve opening are nonlinearly related, and a polynomial is used to approximate it as follows:

[0014]

[0015] In the formula, Q(V) is the pipeline gas flow rate when the pressure before the valve remains unchanged, Q(V) is a constant term, and k i are the polynomial coefficients, V i is the valve opening; based on the measured reasonable data, the expression of the polynomial is determined by automatic fitting.

[0016] In the soft measurement method of pipeline butterfly valve gas flow of the present invention, in order to simultaneously consider the influence of the valve front pressure and the valve opening on the pipeline gas flow in step 4, the polynomial coefficients in formula (2) are corrected according to formula (1) to achieve the effect of the pressure change on the pipeline gas flow when the valve position changes, and construct a relationship between the gas flow, the valve opening and the valve front pressure, such as formula (3):

[0017]

[0018] In the formula, Q(P,V) is the gas flow rate taking into account both the pressure before the valve and the gas flow rate when the valve is open. 0 is a constant term, a i , b i is the polynomial coefficient, P is the pressure before the valve, V i is the valve opening, n is selected according to the situation, generally n=3 or n=4.

[0019] In the soft measurement method of pipeline butterfly valve gas flow of the present invention, steps 1-4 are performed offline, step 5 is performed online, and the valve opening and the pressure before the valve in step 5 are real-time data.

[0020] In the soft measurement method of the gas flow of the pipeline butterfly valve of the present invention, in step 1 and step 5, only the pressure at the front end of the valve is collected, and there is no need to measure the pressure difference between the front and rear ends of the valve.

[0021] The soft measurement method of gas flow of a pipeline butterfly valve of the present invention has at least the following beneficial effects:

[0022] (1) Compared with the prior art, the soft measurement method of pipeline butterfly valve gas flow proposed in the present invention can obtain a unified mathematical relationship among valve opening, valve front pressure and pipeline gas flow through a pipeline butterfly valve gas flow soft measurement model, and estimate the corresponding gas flow in combination with real-time data during operation, thereby realizing soft measurement of pipeline gas flow, which is of great significance for strengthening process supervision and control.

[0023] (2) Compared with conventional industrial pipeline flow detection methods, the pipeline butterfly valve gas flow soft measurement method of the present invention does not require a traditional flow meter, and only requires known parameters such as the valve front pressure and valve opening to obtain high-precision pipeline gas flow. This method can not only reduce the flow detection cost, but also avoid the problems of inaccurate and untimely flow measurement data due to complex test conditions, aging of flow meters and other factors in conventional industrial pipeline flow detection methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic flow chart of a soft measurement method of gas flow of a pipeline butterfly valve according to the present invention;

[0025] Figure 2 This is a schematic diagram for comparing and verifying the soft measurement results and actual measurement results of the gas in the heating furnace of the embodiment;

[0026] Figure 3 It is a schematic diagram for comparing and verifying the soft measurement results and actual measurement results of the air in the heating furnace of the embodiment. DETAILED DESCRIPTION

[0027] In view of the technical deficiencies in existing pipeline gas flow detection, especially to overcome the problems of abnormal display or slow data reflection caused by complex test conditions and aging of flowmeters in current industrial pipeline flow detection, the present invention provides a soft measurement method for pipeline butterfly valve gas flow, while considering the influence of valve opening and pre-valve pressure on pipeline flow, constructing a flow relationship considering the influence of pipeline gas pressure and valve opening, so as to achieve soft measurement of pipeline gas flow without online flow instrument detection. This technology can solve the problems of online flow meter failure, zero drift in the measurement process, and online flow estimation when maintenance is poor, and provide accurate and real-time gas flow data for online control systems.

[0028] A soft measurement method for gas flow of a pipeline butterfly valve of the present invention comprises:

[0029] Step 1: Collect the measured data of pipeline gas flow and its corresponding valve opening and pressure before the valve measured by the traditional flow meter in the initial operation of actual production, and record and store them;

[0030] Step 2: Based on the collected measured data and the principle of fluid flow, the relationship between pipeline gas flow and valve front pressure is analyzed and obtained when the valve opening remains unchanged;

[0031] According to the collected measured data and the principle of fluid flow, when the valve opening remains unchanged, the pipeline flow rate and the pressure before the valve are linearly related, and the relationship is as follows:

[0032] Q(P)=Q P (a+kP) (1)

[0033] Where, Q(P) is the pipeline gas flow rate when the valve opening remains unchanged, Q P is a constant term, k and a are coefficients, and P is the pressure before the valve. The relationship is determined by automatic fitting based on the measured reasonable data.

[0034] Step 3: Based on the collected measured data and the flow characteristics of the butterfly valve, the relationship between the pipeline gas flow and the valve opening is fitted when the pressure before the valve remains unchanged;

[0035] The flow characteristic of the butterfly valve is a fast-opening flow characteristic. According to the collected measured data and flow characteristics, when the pressure before the valve remains unchanged, the pipeline flow and the valve opening are nonlinearly related, which can be approximated by a polynomial as follows:

[0036]

[0037] In the formula, Q(V) is the pipeline gas flow rate when the pressure before the valve remains unchanged, Q(V) is a constant term, and k i are the polynomial coefficients, V i is the valve opening; based on the measured reasonable data, the expression of the polynomial is determined by automatic fitting.

[0038] Step 4: According to the single influence relationship between the valve front pressure or valve opening on the pipeline flow obtained in step 2 and step 3, the relationship between the pipeline gas flow, valve opening and valve front pressure is constructed as a soft measurement model of pipeline butterfly valve gas flow;

[0039] In order to simultaneously consider the influence of the valve front pressure and valve opening on the pipeline gas flow, the polynomial coefficients in formula (2) are corrected according to formula (1) to simultaneously consider the influence of pressure change on the pipeline gas flow when the valve position changes, and construct the relationship between gas flow, valve opening and valve front pressure, as shown in formula (3):

[0040]

[0041] In the formula, Q(P,V) is the gas flow rate taking into account both the pressure before the valve and the gas flow rate when the valve is open. 0 is a constant term, a i 、b i is the polynomial coefficient, P is the pressure before the valve, V i is the valve opening, n is selected according to the situation, generally n=3 or n=4.

[0042] Step 5: Input the real-time valve opening and valve front pressure in the production process into the soft measurement model to complete the real-time online soft measurement of pipeline gas flow.

[0043] In specific implementation, steps 1-4 can be performed offline, and step 5 can be performed online. The valve opening and the pressure before the valve in step 5 are real-time data. In the soft measurement method of the pipeline butterfly valve gas flow of the present invention, only the pressure at the front end of the valve is collected in steps 1 and 5, and there is no need to measure the pressure difference between the front and rear ends of the valve.

[0044] The following is an example of a heat exchange walking beam heating furnace, which is divided into preheating section, heating section 1, heating section 2 and soaking section. The heating section 1, heating section 2 and soaking section are combustion sections, and the valves used in the gas and air pipelines of the heating furnace are butterfly valves. A total of 18,246 sets of data collected from the gas and air of the heating section 1, heating section 2 and soaking section are modeled. The opening range of the coal and air valves in the collected data is 20% to 90%, the gas pipeline pressure range is 3 to 20 kPa, and the air pipeline pressure range is 2 to 10 kPa.

[0045] The coal and air flow, valve opening and valve front pressure of different combustion sections in the data are classified, and 6 data sets are established. The influence of valve opening and valve front pressure on flow is centralized to obtain a single equation between the three. Taking the heating section 2 of the heating furnace as an example, the soft measurement formulas of coal gas and air flow of the heating section 2 are:

[0046] Gas flow:

[0047] Q gas =43.13V-5.37V 2 -0.041V 3 -844.24P+64.89P·V-0.57P·V 2 +0.0013P·V 3 -2558.3

[0048] Air flow:

[0049] Q air =599.79V-10V 2 +0.049V 3+2161.13P-107.17P·V+2.72P·V 2 -0.016P·V 3 -8379.14

[0050] Tables 1 and 2 compare the results of some gas and air flow calculated by the gas flow soft measurement model with the measured data. It can be seen that the error between the soft measurement results and the measured data can be controlled within 10%. In order to verify the accuracy and effectiveness of the model under multiple working conditions, the actual operation data over a continuous period of time are used for comparison and verification. Figure 2 and Figure 3 It can be proved that the gas flow soft measurement model has high accuracy. It is believed that the gas flow soft measurement model can directly estimate the coal and air flow rates in the operation of the heating furnace without the need for traditional flow meters, which is of great significance to the operation control of the heating furnace.

[0051] Table 1 Heating Second Stage Gas Flow

[0052]

[0053] Table 2 Heating Second Stage Air Flow

[0054]

[0055]

[0056] The above description is only a preferred embodiment of the present invention and is not intended to limit the concept of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A soft measurement method for gas flow of pipeline butterfly valve, It is characterized in that include: Step 1: Collect the measured data of pipeline gas flow and its corresponding valve opening and pressure before the valve measured by the traditional flow meter in the initial operation of actual production, and record and store them; Step 2: Based on the collected measured data and the principle of fluid flow, the relationship between pipeline gas flow and valve front pressure is analyzed and obtained when the valve opening remains unchanged; Step 3: Based on the collected measured data and the flow characteristics of the butterfly valve, the relationship between the pipeline gas flow and the valve opening is fitted when the pressure before the valve remains unchanged; Step 4: According to the single influence relationship between the valve front pressure or valve opening on the pipeline flow obtained in step 2 and step 3, the relationship between the pipeline gas flow, valve opening and valve front pressure is constructed as a soft measurement model of pipeline butterfly valve gas flow; Step 5: Input the real-time valve opening and valve front pressure in the production process into the soft measurement model to complete the real-time online soft measurement of pipeline gas flow.

2. The soft measurement method for gas flow of a pipeline butterfly valve according to claim 1, It is characterized in that According to the collected measured data and the principle of fluid flow, it can be known from step 2 that when the valve opening remains unchanged, the pipeline flow rate and the pressure before the valve are linearly related, and the relationship is as follows: Q(P)=Q P (a+kP) (1) Where, Q(P) is the pipeline gas flow rate when the valve opening remains unchanged, Q P is a constant term, k and a are coefficients, and P is the pressure before the valve. The relationship is determined by automatic fitting based on the measured reasonable data.

3. The soft measurement method for gas flow of a pipeline butterfly valve as claimed in claim 2, It is characterized in that The flow characteristic of the butterfly valve in step 3 is a fast-opening flow characteristic. According to the collected measured data and flow characteristics, when the pressure before the valve remains unchanged, the pipeline flow and the valve opening are nonlinearly related, which can be approximated by a polynomial as follows: In the formula, Q(V) is the pipeline gas flow rate when the pressure before the valve remains unchanged, Q(V) is a constant term, and k i are the polynomial coefficients, V i is the valve opening; based on the measured reasonable data, the expression of the polynomial is determined by automatic fitting.

4. The soft measurement method for gas flow of a pipeline butterfly valve as claimed in claim 3, It is characterized in that In order to simultaneously consider the influence of the valve front pressure and the valve opening on the pipeline gas flow in step 4, the polynomial coefficients in formula (2) are corrected according to formula (1) to simultaneously consider the influence of the pressure change on the pipeline gas flow when the valve position changes, and construct a relationship between the gas flow, the valve opening and the valve front pressure, such as formula (3): In the formula, Q(P,V) is the gas flow rate taking into account both the pressure before the valve and the gas flow rate when the valve is open. 0 is a constant term, a i 、b i is the polynomial coefficient, P is the pressure before the valve, V i is the valve opening, n is selected according to the situation, generally n=3 or n=4.

5. The soft measurement method for gas flow of a pipeline butterfly valve as claimed in claim 3, It is characterized in that The steps 1 to 4 are performed offline, and step 5 is performed online. The valve opening and the pressure before the valve in step 5 are real-time data.

6. The soft measurement method for gas flow of a pipeline butterfly valve according to claim 1, Features: In the steps 1 and 5, only the pressure at the front end of the valve is collected, and there is no need to measure the pressure difference between the front and rear ends of the valve.

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