Gas recovery measurement method and system based on segmented integral calibration

Abstract

The present application provides a gas recovery measurement method and system based on segmented integral calibration, the method comprising the following steps: preparing an SF6 gas tank to be recovered with an initial pressure of P0, connecting the gas tank to be recovered to the gas inlet of a mass flow meter, connecting the gas outlet of the mass flow meter to the gas inlet of a recovery device, connecting the gas outlet of the recovery device to the recovery gas cylinder, and weighing the weight of the recovery gas cylinder as m0; starting the recovery device to recover SF6 gas; the calibration coefficient k1 of the pressure of the recovery gas tank in the segment from P0 to P1; the calibration coefficient k2 of the pressure of the recovery gas tank in the segment from P1 to P2; and so on to calculate the calibration coefficient of each segment, after obtaining the calibration coefficient of each pressure segment, calculate the cumulative flow mass, and obtain the gas recovery amount. The present application uses segmented calibration on the basis of the integral algorithm to obtain a more accurate measurement result of the SF6 gas recovery amount.

Description

Technical Field

[0001] The present application relates to the field of SF6 gas quantity measurement, and specifically to a gas recovery quantity measurement method and system based on segmented integral calibration. Background Art

[0002] SF6 gas is widely used as an insulating and arc-extinguishing medium in systems with voltage levels of 110kV and above. SF6 gas is restricted in use due to its serious potential threat to the environment. In order to save costs and protect the environment, SF6 gas needs to be recycled. In recent years, power grid companies in various regions have successively introduced relevant measures to strengthen SF6 gas management. Accurately grasping the effective volume and gas volume of electrical equipment is the basis for achieving lean management of SF6 gas throughout its life cycle and emission data accounting.

[0003] However, the accurate measurement of SF6 gas volume in equipment chambers currently faces many difficulties, such as the complex internal structure of the equipment chamber, which makes it impossible to estimate the effective volume; the traditional weighing method is easily restricted by site limitations and cannot provide accurate measurement data. Therefore, in order to facilitate the lean management of SF6 gas and accurately calculate data emissions, accurate measurement of SF6 gas is very necessary. Summary of the invention

[0004] The purpose of this application is to propose a gas recovery amount measurement method and system based on segmented integral calibration to solve the problem of insufficient accuracy of SF6 gas amount measurement by existing measurement methods.

[0005] The technical solution of this application:

[0006] In a first aspect, an embodiment of the present application provides a method for measuring gas recovery based on segmented integral calibration, comprising the following steps:

[0007] Prepare a SF6 gas cylinder to be recovered with an initial pressure of P0, connect the gas cylinder to be recovered with the gas inlet of the mass flow meter, connect the gas outlet of the mass flow meter with the gas inlet of the recovery device, connect the gas outlet of the recovery device with the recovery gas cylinder, and weigh the weight of the recovery gas cylinder as m0;

[0008] Start the recovery device and evacuate the gas. When the vacuum gauge in the recovery device shows less than 10Pa, start SF6 gas recovery.

[0009] When the pressure of the gas in the recovery gas tank decreases by 0.1MPa from P0 to P1, record the cumulative flow mass W1 of the mass flow meter and the weight m1 of the recovery gas cylinder, then the calibration coefficient k1 of the pressure of the recovery gas tank from P0 to P1;

[0010] When the pressure of the gas in the recovery gas tank continues to decrease by 0.1MPa from P1 to P2, record the cumulative flow mass W2 of the mass flow meter and the weight m2 of the recovery gas cylinder, then the calibration coefficient k2 of the pressure of the recovery gas tank from P1 to P2;

[0011] The calibration coefficient of each segment is calculated in this way. After the calibration coefficient of each pressure segment is obtained, the cumulative flow mass is calculated to obtain the gas recovery amount.

[0012] The calculation method of the calibration coefficient k1 of the recovery gas tank pressure from P0 to P1 is, k1 = (the weight m1 of the recovery gas tank when the recovery gas tank pressure is P1 - the weight m0 of the empty recovery gas tank) / the cumulative flow mass W1 of the mass flow meter in the time period when the gas pressure in the recovery gas tank decreases from P0 to P1.

[0013] The calculation method of the calibration coefficient k2 of the recovery gas tank pressure from P1 to P2 is, k2 = (the weight m2 of the recovery gas tank when the recovery gas tank pressure is P2 - the weight m1 of the recovery gas tank when the recovery gas tank pressure is P1) / the cumulative flow mass W2-W1 of the mass flow meter in the time period when the gas pressure in the recovery gas tank decreases from P1 to P2.

[0014] The cumulative flow quality calculation is specifically: Q = k1*W1+k2(W2-W1)+...k n (W n -W n-1 ), the k n is the calibration coefficient of the nth segment, W n -W n-1 is the cumulative flow quality in the nth segment.

[0015] In a second aspect, an embodiment of the present application provides a gas recovery quantity measurement system based on segmented integral calibration, comprising a gas tank to be recovered, the gas tank to be recovered is connected to the air inlet of a mass flow meter, the air outlet of the mass flow meter is connected to the air inlet of a recovery device, the air outlet of the recovery device is connected to a recovery gas cylinder, the recovery device comprises a vacuum gauge and a recovery gas cylinder weighing device, the mass flow meter, the recovery device and the recovery gas cylinder weighing device are connected to a measuring computer, the measuring computer calculates the calibration coefficient of each segment through the cumulative flow mass data collected by the mass flow meter, the pressure segment data of the recovery device and the weight data of the recovery gas cylinder, and after obtaining the calibration coefficient of each pressure segment, calculates the cumulative flow mass to obtain the gas recovery quantity.

[0016] Compared with the prior art, the beneficial effects of the present application are as follows: the present application utilizes segmented calibration based on the integral algorithm, and performs segmented calibration on the cumulative flow obtained by integrating each pressure interval and the actual flow, and then performs cumulative summation, so as to obtain a more accurate measurement result of the SF6 gas recovery amount. The present application utilizes the integral algorithm to obtain the cumulative flow in real-time integration during the recovery process, and can realize online measurement of the SF6 gas recovery amount. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the method flow of this application.

[0018] Figure 2 This is a system diagram of the present application. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0020] like Figure 1 As shown, the embodiment of the present application provides a gas recovery amount measurement method based on segmented integral calibration, comprising the following steps:

[0021] Prepare a SF6 gas cylinder to be recovered with an initial pressure of P0, connect the gas cylinder to be recovered with the gas inlet of the mass flow meter, connect the gas outlet of the mass flow meter with the gas inlet of the recovery device, connect the gas outlet of the recovery device with the recovery gas cylinder, and weigh the weight of the recovery gas cylinder as m0;

[0022] Start the recovery device and evacuate the gas. When the vacuum gauge in the recovery device shows less than 10Pa, start SF6 gas recovery.

[0023] When the pressure of the gas in the recovery gas tank decreases by 0.1MPa from P0 to P1, record the cumulative flow mass W1 of the mass flow meter and the weight m1 of the recovery gas cylinder, then the calibration coefficient k1 of the pressure of the recovery gas tank from P0 to P1;

[0024] When the pressure of the gas in the recovery gas tank continues to decrease by 0.1MPa from P1 to P2, record the cumulative flow mass W2 of the mass flow meter and the weight m2 of the recovery gas cylinder, then the calibration coefficient k2 of the pressure of the recovery gas tank from P1 to P2;

[0025] The calibration coefficient of each segment is calculated in this way. After the calibration coefficient of each pressure segment is obtained, the cumulative flow mass is calculated to obtain the gas recovery amount.

[0026] The calculation method of the calibration coefficient k1 of the recovery gas tank pressure from P0 to P1 is, k1 = (the weight m1 of the recovery gas tank when the recovery gas tank pressure is P1 - the weight m0 of the empty recovery gas tank) / the cumulative flow mass W1 of the mass flow meter in the time period when the gas pressure in the recovery gas tank decreases from P0 to P1.

[0027] The calculation method of the calibration coefficient k2 of the recovery gas tank pressure from P1 to P2 is, k2 = (the weight m2 of the recovery gas tank when the recovery gas tank pressure is P2 - the weight m1 of the recovery gas tank when the recovery gas tank pressure is P1) / the cumulative flow mass W2-W1 of the mass flow meter in the time period when the gas pressure in the recovery gas tank decreases from P1 to P2.

[0028] The cumulative flow quality calculation is specifically: Q = k1*W1+k2(W2-W1)+...k n (W n -W n-1 ), the k n is the calibration coefficient of the nth segment, W n -W n-1 is the cumulative flow quality in the nth segment.

[0029] like Figure 2 As shown, the embodiment:

[0030] Prepare a SF6 gas tank 1 to be recovered with an initial pressure of 1 MPa;

[0031] Connect the gas tank 1 to be recovered to the gas inlet of the mass flow meter 2;

[0032] Connect the gas outlet of the mass flow meter 2 to the gas inlet of the recovery device 3;

[0033] Connect the gas outlet of the recovery device 3 to the recovery gas cylinder 4, and weigh the weight of the empty recovery gas cylinder 4 to be 5 kg;

[0034] Start the recovery device 3 and evacuate the pipeline. When the vacuum gauge in the recovery device 3 shows less than 10Pa,

[0035] SF6 gas recovery;

[0036] When the gas pressure of the recovery gas tank 1 decreases by 0.1MPa from 1MPa to 0.9MPa, the cumulative flow mass of the SF6 gas mass flowmeter 2 is 25.928kg and the weight of the recovery gas cylinder 4 is 34.843kg. Then the calibration coefficient k1 of the recovery gas tank 1 in the segment from 1MPa to 0.9MPa is = (the weight of the recovery gas cylinder 4 when the pressure of the recovery gas tank 1 is 0.9MPa is 34.843kg-the weight of the empty recovery gas cylinder 4 is 5kg) / the cumulative flow mass of the mass flowmeter 2 in the time period when the gas pressure in the recovery gas tank 1 decreases from 0.9MPa to 0.9MPa is 25.928kg = 1.151, that is, the calibration coefficient k1 of this segment is 1.151;

[0037] When the pressure of the gas in the recovery gas tank 1 continues to decrease by 0.1MPa from 0.9MPa to 0.8MPa, the cumulative flow mass of the SF6 gas mass flowmeter 2 is 48.623kg and the weight of the recovery gas cylinder 4 is 60.08kg. Then the calibration coefficient k2 of the recovery gas tank 1 in the segment from 0.9MPa to 0.8MPa = (the weight of the recovery gas cylinder 4 when the pressure of the recovery gas tank 1 is 0.8MPa is 60.08kg - the weight of the recovery gas cylinder 4 when the pressure of the recovery gas tank 1 is 0.9MPa is 34.843kg) / the cumulative flow mass of the mass flowmeter 2 in the time period when the pressure of the gas in the recovery gas tank 1 decreases from 0.9MPa to 0.8MPa (48.623-25.928kg) = 1.112, that is, the calibration coefficient k2 of this segment is 1.112;

[0038] When the pressure of the gas in the recovery gas tank 1 continues to decrease by 0.1MPa from 0.8MPa to 0.7MPa, the cumulative flow mass of the SF6 gas mass flowmeter 2 is 67.105kg and the weight of the recovery gas cylinder 4 is 79.985kg. Then the calibration coefficient k3 of the recovery gas tank 1 in the segment from 0.8MPa to 0.7MPa = (the weight of the recovery gas cylinder 4 when the pressure of the recovery gas tank 1 is 0.7MPa is 79.985kg - the weight of the recovery gas cylinder 4 when the pressure of the recovery gas tank 1 is 0.8MPa is 60.08kg) / the cumulative flow mass of the mass flowmeter 2 in the time period when the pressure of the gas in the recovery gas tank 1 decreases from 0.8MPa to 0.7MPa (67.105-48.623kg) = 1.077, that is, the calibration coefficient k3 of this segment is 1.077;

[0039] By analogy, the calibration coefficients for each segment are calculated as follows:

[0040] k1=1.151; k2=1.112; k3=1.077; k4=1.051; k5=1.021; k6=1.012;

[0041] k7=0.974; k8=0.942; k9=0.906; k10=0.875; k11=0.853;

[0042] Afterwards, this calibration coefficient is written into the cumulative flow mass calculation program of the measuring computer 5 through programming, and the true cumulative flow mass of the calibrated pressure from 1MPa to -0.1MPa can be obtained. The final accurate SF6 gas cumulative recovery mass Q = 1.151W1 + 1.112 (W2-W1) + 1.077 (W3-W2) + 1.051 (W4-W3) + 1.021 (W5-W4) + 1.012 (W6-W5) + 0.974 (W7-W6) + 0.942 (W8-W7) + 0.906 (W9-W8) + 0.875 (W11-W10) + 0.853 (W12-W11).

[0043] The calibration coefficient k calculated by this method does not change with the volume of the gas chamber. In the actual recovery process, when recovering in a certain pressure range, it is only necessary to use the calibration coefficient corresponding to the range for accurate measurement.

[0044] The experiment shows that in the process of recycling from 1MPa pressure to -0.1MPa, the total cumulative flow mass is 125.669kg, and the total recovery volume of the recycling bottle is 126.425kg. After the segmented calibration, the deviation between the cumulative flow mass of the recycled gas and the standard value is (126.425-125.662) / 126.425=0.6%;

[0045] The calibration coefficient was used to conduct SF6 gas recovery test on the gas cylinder with a recovery volume of 0.3m3 and an initial pressure of 0.8MPa, and the recovery weight pressure was 0.2MPa. Before the segmented calibration, the cumulative flow mass of the mass flow meter was 65.076kg; after the segmented calibration, the cumulative flow mass of the mass flow meter was 67.381kg; the standard recovery gas weight of the recovery cylinder was 67.788kg, that is, the accuracy after calibration was improved by (67.381-65.076) / 67.788×100%=3.4% compared with that before calibration.

[0046] Theoretical proof that the calibration coefficient k corresponding to each segment remains unchanged:

[0047] Experiment 1: Let k a is the calibration coefficient between the pressure P1 and P2 segments of the recovery gas tank with a volume of V1, then:

[0048]

[0049] In the formula, m 标准1 The standard value of the recovered weight measured by weighing;

[0050] m 累计1 The accumulated value of recovered weight for integral calculation.

[0051] Experiment 2: Let k b is the calibration coefficient between the pressure P1 and P2 segments of the recovery gas tank with a volume of V2, then:

[0052]

[0053] In the formula, m 标准2 The standard value of the recovered weight measured by weighing;

[0054] m 累计2 The accumulated value of recovered weight for integral calculation.

[0055] According to the ideal gas state equation, we have:

[0056] PV=nRT(3)

[0057] Transform (3) to get:

[0058] PM=ρRT(4)

[0059] In formulas (3) and (4), P is the pressure, MPa; V is the gas volume, m 3 ; n is the amount of gas, mol; M is the molecular weight of the gas; ρ is the density of the gas, kg / m 3 ; R is the molar gas constant; T is the temperature, K.

[0060] According to formula (4), the recovery rate θ can be calculated:

[0061]

[0062] (5) where θ is the recovery rate, m 3 / h; V g is the volume of the recovery gas tank, m 3 ;P c is the standard atmospheric pressure, MPa; P1 is the pressure difference of the gas tank before recovery, MPa; P2 is the pressure difference of the gas tank after recovery, MPa; Δt is the recovery time, h. ρ2 is the density of the gas in the gas tank after recovery, kg / m 3 ; ρ1 is the density of the gas in the gas tank before recovery, kg / m 3 .

[0063] Since P1, P2 and θ are equal in Experiment 1 and Experiment 2 and P0 is a constant value of standard atmospheric pressure, combined with formula (5), we can obtain:

[0064]

[0065]

[0066] The cumulative flow weight of Experiment 1 in this pressure range is calculated by the integral algorithm (F(t)1 represents the relationship between the instantaneous flow and time in Experiment 1 in this time period):

[0067]

[0068] The cumulative flow weight of Experiment 2 in this pressure range is calculated by the integral algorithm (F(t)2 represents the relationship between the instantaneous flow and time in Experiment 1 during this time period):

[0069]

[0070] According to the geometric meaning of integral, when Δt 累计 As time goes to infinity, we have:

[0071]

[0072]

[0073] Therefore, according to equations (1), (2), (6) and (11), we have:

[0074]

[0075] That is, the calibration coefficient within this pressure segment remains unchanged.

[0076] Through the above embodiments, it can be known that the present application utilizes segmented calibration based on the integral algorithm, and the cumulative flow obtained by integrating each pressure interval is segmentedly calibrated with the actual flow, and then cumulatively summed, so as to obtain a more accurate measurement result of the SF6 gas recovery amount. The present application utilizes the integral algorithm to obtain the cumulative flow in real-time integration during the recovery process, and can realize online measurement of the SF6 gas recovery amount.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present application rather than to limit it. Although the present application has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present application can still be modified or replaced by equivalents, and any modifications or equivalent replacements that do not depart from the spirit and scope of the present application should be included in the scope of protection of the claims of the present application.

Claims

1. A gas recovery measurement method based on segmented integral calibration, characterized in that: The following steps are involved: Prepare a SF6 gas cylinder to be recovered with an initial pressure of P0, connect the gas cylinder to be recovered with the gas inlet of the mass flow meter, connect the gas outlet of the mass flow meter with the gas inlet of the recovery device, connect the gas outlet of the recovery device with the recovery gas cylinder, and weigh the weight of the recovery gas cylinder as m0; Start the recovery device and evacuate the gas. When the vacuum gauge in the recovery device shows less than 10Pa, start SF6 gas recovery. When the pressure of the gas in the recovery gas tank decreases by 0.1MPa from P0 to P1, record the cumulative flow mass W1 of the mass flow meter and the weight m1 of the recovery gas cylinder, then the calibration coefficient k1 of the pressure of the recovery gas tank from P0 to P1; When the pressure of the gas in the recovery gas tank continues to decrease by 0.1MPa from P1 to P2, record the cumulative flow mass W2 of the mass flow meter and the weight m2 of the recovery gas cylinder, then the calibration coefficient k2 of the pressure of the recovery gas tank from P1 to P2; The calibration coefficient of each segment is calculated in this way. After the calibration coefficient of each pressure segment is obtained, the cumulative flow mass is calculated to obtain the gas recovery amount. The calculation method of the calibration coefficient k1 of the recovery gas tank pressure from P0 to P1 is: k1 = (the weight of the recovery gas tank when the recovery gas tank pressure is P1 is m1-the weight of the empty recovery gas tank is m0) / the cumulative flow mass W1 of the mass flow meter during the time period when the gas pressure in the recovery gas tank decreases from P0 to P1; The calculation method of the calibration coefficient k2 of the recovery gas tank pressure from P1 to P2 is: k2 = (the weight of the recovery gas tank when the recovery gas tank pressure is P2 m2-the weight of the recovery gas tank when the recovery gas tank pressure is P1 m1) / the cumulative flow mass W2-W1 of the mass flow meter during the time period when the gas pressure in the recovery gas tank decreases from P1 to P2; The cumulative flow quality calculation is specifically: Q = k1*W1+k2(W2-W1)+...k n (W n -W n-1 ), the k n is the calibration coefficient of the nth segment, W n -W n-1 is the cumulative flow quality in the nth segment.

2. A gas recovery measurement system based on segmented integral calibration, used to implement the method of claim 1, characterized in that: The invention comprises a gas cylinder (1) to be recovered, wherein the gas cylinder (1) to be recovered is connected to the air inlet of a mass flow meter (2), the air outlet of the mass flow meter (2) is connected to the air inlet of a recovery device (3), the air outlet of the recovery device (3) is connected to the recovery gas cylinder (4), the recovery device (3) comprises a vacuum gauge and a recovery gas cylinder weighing device, the mass flow meter (2), the recovery device (3) and the recovery gas cylinder weighing device are connected to a measuring computer (5), the measuring computer (5) calculates the calibration coefficient of each segment through the accumulated flow mass data collected by the mass flow meter (2), the pressure segment data of the recovery device (3) and the weight data of the recovery gas cylinder, and after obtaining the calibration coefficient of each pressure segment, calculates the accumulated flow mass to obtain the gas recovery amount.

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