SF6 recovery device and method with recovery rate measurement function

Abstract

An SF6 recovery device and method with recovery rate measurement function is disclosed. The device includes: a first buffer tank, a second buffer tank, an external storage tank, and a PLC controller. The inlet of the first buffer tank is connected to a charging / discharging interface via a first pipeline. The first pipeline is equipped with a temperature sensor, a first pressure sensor, a first solenoid valve, and a first compressor. The outlet of the first buffer tank is connected to the inlet of the second buffer tank via a second pipeline and a third pipeline. The second pipeline is sequentially equipped with a second solenoid valve, a pressure reducing valve, a mass flow controller, and a fourth solenoid valve. The third pipeline is sequentially equipped with a third solenoid valve and a fifth solenoid valve. The outlet of the second buffer tank is connected to the external storage tank via a fourth pipeline. The fourth pipeline is equipped with a proportional valve and a second compressor. This invention can accurately measure data such as recovery rate, gas volume in the gas chamber, and effective volume without reducing the recovery speed, and can also completely calculate the recovery rate and recovery amount throughout the entire recovery process.

Description

Technical Field

[0001] This invention relates to the field of SF6 gas recovery, specifically to an SF6 recovery device and method with recovery rate measurement function. Background Technology

[0002] Accurately determining the recovery rate during the SF6 gas recovery process and obtaining data such as gas volume and effective volume in the filling equipment's gas chambers are crucial for strengthening SF6 gas management and achieving lean management throughout its entire lifecycle. For example... Figure 1 As shown, existing methods for measuring recovery rate mainly involve connecting a recovery rate measuring device in series between the gas chamber charging / discharging interface and the SF6 recovery device connection pipeline. This device detects the gas chamber pressure and temperature at each stage of recovery, as well as the pressure of the SF6 recovery device. Based on the output gas volume of the mass flow controller and the Beattie-Bridgman empirical formula, data such as recovery rate, gas chamber volume, and effective volume are calculated. Since the pressure at the front end of the mass flow controller cannot be too high, a pressure reducing valve is designed. After a period of recovery, the pressure in the gas chamber decreases, and the pressure difference between the front and rear ends of the mass flow controller no longer meets its requirements, making it impossible to control the output gas normally. At this point, solenoid valve 2 needs to be opened, and the gas flows out through the bypass.

[0003] The existing technology has the following main problems:

[0004] (1) Reduced recovery speed: The core module of the recovery rate measurement device is a built-in mass flow controller, which controls the SF6 gas flow rate. To achieve precise flow control, the pressure difference between the front and rear ends of the mass flow controller must be kept stable. As the recovery process proceeds, the SF6 gas pressure in the gas chamber will gradually decrease. Therefore, a pressure reducing valve needs to be installed at the front end to fix the pressure at the front end of the mass flow controller at a certain value. Compared to directly connecting the gas chamber charging and discharging interface to the SF6 recovery device, the presence of the pressure reducing valve will reduce the recovery speed. In addition, while controlling the SF6 gas flow rate, the mass flow controller will also hinder gas flow, thereby reducing the recovery speed.

[0005] (2) Large measurement error: Since the pressure difference between the front and back ends of the mass flow controller affects the flow control error, the pressure at the front end can be kept stable by the pressure reducing valve, but the back end is connected to the SF6 recovery device. Due to the compressor and as the recovery process proceeds (the internal pressure of the recovery device increases), the pressure at the back end of the flow meter is extremely unstable. Therefore, the pressure difference between the front and back ends of the flow meter is unstable, and the flow control error is large.

[0006] (3) The full recovery rate cannot be accurately measured: When the pressure in the gas chamber drops to a certain level, the pressure reducing valve and the mass flow controller will seriously interfere with the recovery speed. At this time, the gas can only bypass the pipeline where the pressure reducing valve and the mass flow controller are located and flow through the bypass. This part of the gas cannot be calculated, resulting in inaccurate measurement results. Summary of the Invention

[0007] This invention provides an SF6 recovery device and method with recovery rate measurement function, which can accurately measure data such as recovery rate, gas volume in the gas chamber and effective volume without reducing the recovery speed; in addition, the mass flow controller of this invention maintains a stable pressure difference between the front and rear ends throughout the process, and the flow control is precise, and the recovery rate and recovery amount can be calculated completely throughout the entire recovery process.

[0008] An SF6 recovery device with recovery rate measurement function includes a first buffer tank, a second buffer tank, an external storage tank, and a PLC controller. The inlet of the first buffer tank is connected to a charging / discharging interface via a first pipeline. The first pipeline is equipped with a temperature sensor, a first pressure sensor, a first solenoid valve, and a first compressor. The first buffer tank is equipped with a second pressure sensor. The outlet of the first buffer tank is connected to the inlet of the second buffer tank via a second pipeline and a third pipeline. The second pipeline is equipped with a second solenoid valve, a pressure reducing valve, a mass flow controller, and a fourth solenoid valve in sequence. The second buffer tank is equipped with a third pressure sensor. The third pipeline is equipped with a third solenoid valve and a fifth solenoid valve in sequence. The outlet of the second buffer tank is connected to the external storage tank via a fourth pipeline. The fourth pipeline is equipped with a proportional valve and a second compressor. The temperature sensor, each pressure sensor, each solenoid valve, each compressor, the pressure reducing valve, the mass flow controller, and the proportional valve are all connected to the PLC controller.

[0009] Furthermore, the temperature sensor and the first pressure sensor are used to measure the initial temperature T0 and initial pressure P0 of the air chamber of the inflation device, respectively. The PLC controller is used to calculate the gas density ρ0 of the air chamber before recovery based on the measured initial temperature T0 and initial pressure P0 of the air chamber of the inflation device and the Ti-Bridgeman empirical formula.

[0010] Furthermore, during the recovery process, the second pressure sensor 8 is used to monitor the pressure P of the first buffer tank in real time. b If the pressure P in the first buffer tank b Below (P) a If the pressure is increased by 0.05 MPa, the PLC controller will close the second solenoid valve, the fourth solenoid valve, and the mass flow controller until the pressure in the first buffer tank reaches P. b Higher than (P) a +0.05) MPa and then restart, where P a The pressure after the pressure is reduced by the pressure reducing valve.

[0011] Furthermore, during the recovery process, a third pressure sensor is used to monitor the pressure P of the second buffer tank in real time. c The PLC controller is used to monitor the pressure P of the second buffer tank based on the third pressure sensor. c The internal orifice size of the proportional valve is controlled to adjust the pressure P of the second buffer tank. c Conditions met: (P) d -0.03) < P c < (P d +0.03) MPa, where P d Take 0.1 MPa.

[0012] Furthermore, the PLC controller is also used to control the pressure P in the first buffer tank after SF6 recycling is completed. b Below (P) a If the pressure is +0.05 MPa, then close the second and fourth solenoid valves, remove the pressure reducing valve and mass flow controller from the gas path, and calculate the recovery rate, gas volume, and effective volume.

[0013] 9. Further, the PLC controller calculates the recovery rate, gas volume, and effective volume, specifically including the following steps:

[0014] The PLC controller has a built-in timer that records the time t1 for the mass flow controller to output gas. Therefore, the output gas volume V1 = t1Q, and the density of SF6 gas at normal pressure is ρ. SF6 =6.0886kg / m 3 The amount of gas recovered during this time period is m. k1 = V1×ρ SF6 ;

[0015] The gas pressure P in the first buffer tank at time t1 c1 The temperature is equal to the current temperature T1 of the gas in the gas chamber. The gas density ρ in the first buffer tank is calculated using empirical formulas. c1 Given the volume V of the first buffer tank c The mass of gas in the first buffer tank is m k2 =V c ×ρ c1 ;

[0016] Calculate the amount of gas reduction m in the gas chamber during the time t1 at the start of recovery. s1 =m k1 +m k2 ;

[0017] Based on the temperature T1 and pressure P1 of the recovered gas chamber, and using empirical formulas to calculate the gas density ρ1 of the recovered gas chamber, the effective volume V of the gas chamber can be further calculated:

[0018] V= m s1 / (ρ0-ρ1)

[0019] The gas volume is: m = V × ρ0;

[0020] Recovery rate: ξ = m s1 / m.

[0021] A method for recovering SF6 with a recovery rate measurement function, which uses the above-mentioned apparatus, includes:

[0022] (1) The temperature sensor and the first pressure sensor measure the initial temperature T0 and initial pressure P0 of the gas chamber of the inflation device, and calculate the gas density ρ0 of the gas chamber before recovery according to the T.-Bridgeman empirical formula.

[0023] (2) Open the first solenoid valve, the second solenoid valve, and the fourth solenoid valve; open the pressure reducing valve and the proportional valve 18; and start the first compressor and the second compressor; wherein the pressure after pressure reduction by the pressure reducing valve is set to P. a The mass flow controller outputs a flow rate of Qm. 3 / h;

[0024] (3) During the recovery process, the second pressure sensor and the third pressure sensor monitor the pressure of the first buffer tank and the second buffer tank in real time, respectively. If the pressure P in the first buffer tank... b Below (P) a If the pressure is increased by 0.05 MPa, then the second solenoid valve, the fourth solenoid valve, and the mass flow controller will be closed until the pressure in the first buffer tank reaches P. b Higher than (P) a Restarting at +0.05 MPa; the PLC controller monitors the pressure P of the second buffer tank based on the third pressure sensor. c The internal orifice size of the proportional valve is controlled to adjust the pressure P of the second buffer tank. c Conditions met: (P) d -0.03) < P c < (P d +0.03) MPa, where P d Take 0.1 MPa;

[0025] (4) After SF6 recovery is completed, and the pressure P in the first buffer tank is... b Below (P) a If the pressure is +0.05 MPa, then close the second and fourth solenoid valves, remove the pressure reducing valve and mass flow controller from the gas path, and calculate the recovery rate, gas volume and effective volume.

[0026] (5) After the calculation is completed, open the third solenoid valve and the fifth solenoid valve to recover all the residual gas in the first buffer tank to the storage tank for liquefaction and storage by the second compressor.

[0027] Furthermore, the PLC controller calculates the recovery rate, gas volume, and effective volume, specifically including the following steps:

[0028] The PLC controller has a built-in timer that records the time t1 for the mass flow controller to output gas. Therefore, the output gas volume V1 = t1Q, and the density of SF6 gas at normal pressure is ρ. SF6 =6.0886kg / m 3 The amount of gas recovered during this time period is m. k1 = V1×ρ SF6 ;

[0029] The gas pressure P in the first buffer tank at time t1 c1 The temperature is equal to the current temperature T1 of the gas in the gas chamber. The gas density ρ in the first buffer tank is calculated using empirical formulas. c1 Given the volume V of the first buffer tank c The mass of gas in the first buffer tank is m k2 =V c ×ρ c1 ;

[0030] Calculate the amount of gas reduction m in the gas chamber during the time t1 at the start of recovery. s1 =m k1 +m k2 ;

[0031] Based on the temperature T1 and pressure P1 of the recovered gas chamber, and using empirical formulas to calculate the gas density ρ1 of the recovered gas chamber, the effective volume V of the gas chamber can be further calculated:

[0032] V= m s1 / (ρ0-ρ1)

[0033] The gas volume is: m = V × ρ0;

[0034] Recovery rate: ξ = m s1 / m.

[0035] Furthermore, a vacuum gauge and a vacuum pump are installed on the pipeline between the third and fifth solenoid valves. The output end of the vacuum pump is connected to the exhaust port, and the vacuum gauge and vacuum pump are connected to the PLC controller.

[0036] Furthermore, if it is necessary to evacuate the device, close the second and fourth solenoid valves, open the first, third, and fifth solenoid valves, start the vacuum pump to discharge the residual gas, and stop evacuating when the vacuum gauge pressure is detected to be lower than 10 Pa.

[0037] This invention uses a dual control system of a pressure reducing valve and a proportional valve to ensure a stable pressure difference between the front and rear ends of the mass flow controller, thereby improving the accuracy of the flow output. A first buffer tank is installed at the front end of the pressure reducing valve, so the recovered gas first enters the first buffer tank without the need for a pressure reducing valve to reduce the pressure and without reducing the recovery speed. The pressure at the front end of the pressure reducing valve is always kept within the set range, so the mass flow controller can still output gas even when the gas chamber pressure is low in the later stage of recovery. All recovered gas volumes can be measured, and the recovery rate and recovery volume of the entire process can be calculated completely. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the structure of an existing SF6 recovery rate measurement device and an SF6 recovery device used in combination;

[0039] Figure 2 This is a schematic diagram of the SF6 recycling device with recovery rate measurement function according to an embodiment of the present invention.

[0040] The reference numerals in the figure are described as follows: 1—First buffer tank, 2—Second buffer tank, 3—External storage tank, 4—Temperature sensor, 5—First pressure sensor, 6—First solenoid valve, 7—First compressor, 8—Second pressure sensor, 9—Second solenoid valve, 10—Pressure reducing valve, 11—Mass flow controller, 12—Fourth solenoid valve, 13—Third pressure sensor, 14—Third solenoid valve, 15—Fifth solenoid valve, 16—Vacuum gauge, 17—Vacuum pump, 18—Proportional valve, 19—Second compressor, 20—PLC controller. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] like Figure 2 As shown, this embodiment of the invention proposes an SF6 recovery device with a recovery rate measurement function. The recovery rate measurement module is built into the SF6 recovery device. First, the gas is recovered into the recovery equipment, and then the recovery rate is measured. At the same time, the pressure reducing valve 10 and the proportional valve 18 control the pressure at the front and rear ends of the mass flow controller 11 to stabilize, thereby reducing the flow control error.

[0043] The SF6 recovery device includes a first buffer tank 1, a second buffer tank 2, an external storage tank 3, and a PLC controller 20. The input port of the first buffer tank 1 is connected to the gas filling and discharging interface through a first pipeline. The first pipeline is equipped with a temperature sensor 4, a first pressure sensor 5, a first solenoid valve 6, and a first compressor 7. The first buffer tank 1 is equipped with a second pressure sensor 8.

[0044] The output port of the first buffer tank 1 is connected to the input port of the second buffer tank 2 through the second and third pipelines. The second pipeline is equipped with a second solenoid valve 9, a pressure reducing valve 10, a mass flow controller 11 and a fourth solenoid valve 12 in sequence. The second buffer tank 2 is equipped with a third pressure sensor 13. The third pipeline is equipped with a third solenoid valve 14 and a fifth solenoid valve 15 in sequence. The pipeline between the third solenoid valve 14 and the fifth solenoid valve 15 is equipped with a vacuum gauge 16 and a vacuum pump 17. The output end of the vacuum pump 17 is connected to the exhaust port.

[0045] The output port of the second buffer tank 2 is connected to the external storage tank 3 through a fourth pipeline, which is equipped with a proportional valve 18 and a second compressor 19.

[0046] The working principle of the SF6 recovery device is as follows:

[0047] (1) Connect the inflation / deflation interface of the inflation device and the recovery device through a dedicated pipeline. Temperature sensor 4 and first pressure sensor 5 measure the initial temperature T0 and initial pressure P0 of the air chamber of the inflation device. Calculate the gas density ρ0 of the air chamber before recovery according to the Beattie-Bridgman empirical formula (1).

[0048] P = 56.2ρT(1+B) - ρ 2 A (1)

[0049] A = 74.9(1 - 0.727 × 10) -3 ρ)

[0050] B = 2.51 × 10 -3 ρ(1-0.846×10 -3 ρ)

[0051] In the formula:

[0052] The absolute pressure of P-SF6 gas, expressed in MPa;

[0053] ρ—the density of SF6 gas, in kg / m³ 3 ;

[0054] R—gas constant, in J (kg·K), SF6 is 56.2 J / (kg·K).

[0055] T—The thermodynamic temperature of SF6 gas, expressed in K.

[0056] (2) Open the first solenoid valve 6, the second solenoid valve 9, and the fourth solenoid valve 12; open the pressure reducing valve 10 and the proportional valve 18; and start the first compressor 7 and the second compressor 19; wherein the pressure after pressure reduction by the pressure reducing valve 10 is set to P. a (Typically 0.2 MPa is used), the output flow rate of mass flow controller 11 is Qm. 3 / h (value under standard conditions; this flow rate must be greater than the SF6 recovery rate to prevent the inlet speed of the first buffer tank 1 from being greater than the outlet speed).

[0057] (3) During the recovery process, the second pressure sensor 8 and the third pressure sensor 13 monitor the pressure of the first buffer tank 1 and the second buffer tank 2 in real time, respectively. If the pressure P in the first buffer tank 1 is... b Below (P) a If the pressure is increased by 0.05 MPa, then the second solenoid valve 9, the fourth solenoid valve 12, and the mass flow controller 11 will be closed until the pressure in the first buffer tank 1 reaches P. b Higher than (P) a +0.05) MPa and then restart;

[0058] If the pressure P in the second buffer tank 2 c (Equal to the pressure at the back end of mass flow controller 11) exists: (P) d -0.03) < P c < (P d +0.03) MPa, where P d Generally, 0.1 MPa is selected, and the pressure difference between the front and rear ends is generally maintained at 0.1 MPa. At this time, the control system does not need to adjust the orifice diameter of the proportional valve 18; if P c > (P d (+0.03) The pressure in the second buffer tank 2 is high, and the pressure difference between the front and rear ends of the mass flow controller 11 is too small. The control system controls the proportional valve 18 to increase the internal orifice diameter, thereby accelerating the pressurization and liquefaction of the gas in the second buffer tank 2 by the second compressor 19 and storing it in the storage tank, thus reducing the gas pressure P in the second buffer tank 2. c This increases the pressure difference between the front and rear ends of the mass flow controller 11; if P c < (P d (+0.03) The pressure in the second buffer tank 2 is low, and the pressure difference between the front and rear ends of the mass flow controller 11 is too large. The control system controls the proportional valve 18 to reduce the internal orifice diameter, thereby slowing down the pressurization and liquefaction of the gas in the second buffer tank 2 by the second compressor 19 and storing it in the storage tank, thus increasing the gas pressure P in the second buffer tank 2. c This reduces the pressure difference between the front and rear ends of the mass flow controller 11.

[0059] (4) After the SF6 recovery is completed, and the pressure P in the first buffer tank 1 is... b Below (P) a If the pressure is +0.05 MPa, then close the second solenoid valve 9 and the fourth solenoid valve 12, remove the pressure reducing valve 10 and the mass flow controller 11 from the gas path, and calculate the recovery rate, gas volume, and effective volume:

[0060] The PLC controller 20 has a built-in timer that records the gas output time t1 of the mass flow controller 11. Therefore, the output gas volume V1 = t1Q, and the density of SF6 gas at normal pressure is ρ. SF6 =6.0886kg / m 3 The amount of gas recovered during this time period is m. k1 =V1×ρ SF6 .

[0061] The gas pressure P in the first buffer tank 1 at time t1 c1 The temperature is equal to the current temperature T1 of the gas in the gas chamber (the gas temperature can be considered constant during the recovery process). The gas density ρ in the first buffer tank 1 is calculated using empirical formulas. c1 Given the volume V of the first buffer tank 1 c (m) 3 Then, the mass m of the gas in the first buffer tank 1 is... k2 = V c ×ρ c1 .

[0062] Therefore, the amount of gas reduction m in the gas chamber during the time t1 at the start of recovery can be calculated. s1 =m k1 +m k2 .

[0063] Based on the temperature T1 and pressure P1 of the recovered gas chamber, and using empirical formulas to calculate the gas density ρ1 of the recovered gas chamber, the effective volume V of the gas chamber can be further calculated:

[0064] V= m s1 / (ρ0-ρ1)

[0065] Gas volume: m = V × ρ0

[0066] Recovery rate: ξ = m s1 / m

[0067] (5) After the above data is calculated, open the third solenoid valve 14 and the fifth solenoid valve 15 to recover all the residual gas in the first buffer tank 1 to the external storage tank 3 for liquefaction and storage by the second compressor 19.

[0068] (6) If it is necessary to evacuate the device, close the second solenoid valve 9 and the fourth solenoid valve 12, open the first solenoid valve 6, the third solenoid valve 14 and the fifth solenoid valve 15, start the vacuum pump 17 to discharge the residual gas, and stop evacuating when the pressure of the vacuum gauge 16 is detected to be lower than 10 Pa.

[0069] The present invention has the following beneficial effects:

[0070] (1) By using the pressure reducing valve 10 and the proportional valve 18 for dual regulation, the pressure difference between the front and rear ends of the mass flow controller 11 is kept stable, thereby improving the accuracy of the flow output.

[0071] (2) A first buffer tank 1 is provided at the front end of the pressure reducing valve 10. The recovered gas first enters the first buffer tank 1, so there is no need for the pressure reducing valve 10 to reduce the pressure and the recovery speed is not reduced.

[0072] (3) The pressure at the front end of the pressure reducing valve 10 is always kept within the set range. The mass flow controller 11 can still output gas even when the gas pressure in the gas chamber is low in the later stage of recovery. All recovered gas volume can be measured, and the recovery rate and recovery amount of the whole process can be calculated completely.

[0073] (4) The two devices of recycling and measurement are integrated into one device, which is convenient for field use.

[0074] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An SF6 recovery device with a recovery rate measuring function, characterized by: The device comprises a first buffer tank, a second buffer tank, an external liquid storage tank and a PLC controller, the input port of the first buffer tank is connected with the gas charging and discharging interface through a first pipeline, and a temperature sensor, a first pressure sensor, a first electromagnetic valve and a first compressor are arranged on the first pipeline, and a second pressure sensor is arranged on the first buffer tank; the output port of the first buffer tank is connected with the input port of the second buffer tank through a second pipeline and a third pipeline, a second electromagnetic valve, a pressure reducing valve, a mass flow controller and a fourth electromagnetic valve are sequentially arranged on the second pipeline, and a third pressure sensor is arranged on the second buffer tank; a third electromagnetic valve and a fifth electromagnetic valve are sequentially arranged on the third pipeline; the output port of the second buffer tank is connected with the external liquid storage tank through a fourth pipeline, and a proportional valve and a second compressor are arranged on the fourth pipeline; the temperature sensor, the pressure sensors, the electromagnetic valves, the compressors, the pressure reducing valve, the mass flow controller and the proportional valve are connected with the PLC controller; The PLC controller is used for calculating the recovery rate, the gas volume and the effective volume, and the specific steps comprise: The PLC controller has a built-in timer, which records the time t1 of the output gas from the mass flow controller. The volume V1 of the output gas is t1Q, and the density of SF6 gas under normal pressure is p SF6 = 6.0886 kg / m 3 Therefore, the volume of the recovered gas in this time period is m k1 = V1 x p SF6 ; The gas pressure P in the first buffer tank at time t1 c1 The temperature is equal to the current temperature T1 of the gas in the gas chamber. The gas density ρ in the first buffer tank is calculated using empirical formulas. c1 Given the volume V of the first buffer tank c The mass of gas in the first buffer tank is m k2 = V c ×ρ c1 ; The amount of gas reduction m in the gas chamber during the time t1 from the start of recovery is calculated s1 = m k1 + m k2 ; According to the temperature T1 and the pressure P1 of the gas chamber after recovery, the gas density ρ1 of the gas chamber after recovery is calculated by combining the empirical formula, and the effective volume V of the gas chamber can be further calculated: V = m s1 / (p0-p1); The gas volume is m=V×ρ0. Recovery: ξ = m s1 / m.

2. The SF6 recovery apparatus with a recovery rate measuring function according to claim 1, characterized by: The temperature sensor and the first pressure sensor are respectively used for measuring the initial temperature T0 and the initial pressure P0 of the gas chamber of the inflating device, and the PLC controller is used for calculating the gas density ρ0 of the gas chamber before recovery according to the measured initial temperature T0 and the initial pressure P0 of the gas chamber of the inflating device and the Ti-Bridgman empirical formula.

3. The SF6 recovery apparatus with a recovery rate measuring function according to claim 2, characterized by: During the recovery process, the second pressure sensor is used to monitor the pressure P of the first buffer tank in real time. b If the pressure P in the first buffer tank b Below (P) a If the pressure is increased by 0.05 MPa, the PLC controller will close the second solenoid valve, the fourth solenoid valve, and the mass flow controller until the pressure in the first buffer tank reaches P. b Higher than (P) a +0.05) MPa and then restart, where P a The pressure after the pressure is reduced by the pressure reducing valve.

4. The SF6 recovery apparatus with a recovery rate measuring function according to claim 1, characterized by: During the recovery process, a third pressure sensor is used to monitor the pressure P of the second buffer tank in real time. c The PLC controller is used to monitor the pressure P of the second buffer tank based on the third pressure sensor. c The internal orifice size of the proportional valve is controlled to adjust the pressure P of the second buffer tank. c Conditions met: (P) d -0.03) < P c < (P d +0.03) MPa, where P d Take 0.1 MPa.

5. The SF6 recovery apparatus with a recovery rate measuring function according to claim 3, characterized by: The PLC controller is also used to close the second electromagnetic valve and the fourth electromagnetic valve, remove the pressure reducing valve and the mass flow controller from the gas circuit, and calculate the recovery rate, the gas volume, and the effective volume after the SF6 recovery is completed and the pressure P b is lower than (P a -0.05) MPa. +0.05) MPa, then close the second electromagnetic valve, the fourth electromagnetic valve, remove the pressure reducing valve and the mass flow controller from the gas circuit, and calculate the recovery rate, the gas volume, and the effective volume.

6. A method of recovering SF6 with a recovery rate measuring function, characterized by, The method is performed by using the device of any one of claims 1-5, and the method comprises: (1) the temperature sensor and the first pressure sensor measure the initial temperature T0 and the initial pressure P0 of the gas chamber of the inflating device, and the gas density ρ0 of the gas chamber before recovery is calculated according to the Ti-Bridgman empirical formula; (2) open the first electromagnetic valve, the second electromagnetic valve, the fourth electromagnetic valve, open the pressure reducing valve, the proportional valve 18, start the first compressor, the second compressor; wherein the pressure reducing valve is set to P a , the mass flow controller output flow is Qm 3 / h; (3) The second pressure sensor and the third pressure sensor respectively monitor the pressure of the first buffer tank and the second buffer tank in real time during the recovery process. If the pressure P b in the first buffer tank is lower than (P a +0.05) MPa, the second electromagnetic valve, the fourth electromagnetic valve and the mass flow controller are closed until the pressure P b in the first buffer tank is higher than (P a +0.05) MPa and then are reopened; the PLC controller controls the internal aperture size of the proportional valve according to the pressure P c of the second buffer tank monitored by the third pressure sensor, so that the pressure P c of the second buffer tank satisfies the condition: (P d -0.03) < P c < (P d +0.03) MPa, wherein P d is 0.1 MPa. (4) When the SF6 recovery is completed, and the pressure P b in the first buffer tank is lower than (P a +0.05) MPa, then the second electromagnetic valve and the fourth electromagnetic valve are closed, the pressure reducing valve and the mass flow controller are removed from the gas path, and the recovery rate, the gas volume, and the effective volume are calculated. (5) after the calculation is completed, the third electromagnetic valve and the fifth electromagnetic valve are opened, and the residual gas in the first buffer tank is completely recovered to the liquid storage tank by the second compressor for liquefied storage.

7. The SF6 recovery method with recovery rate measurement function according to claim 6, characterized by: The PLC controller calculates the recovery rate, the gas volume and the effective volume, and the specific steps comprise: The PLC controller has a built-in timer, which records the time t1 of the output gas from the mass flow controller. The volume V1 of the output gas is t1Q, and the density of SF6 gas under normal pressure is p SF6 = 6.0886 kg / m 3 The volume of the recovered gas in this time period is m k1 = V1 x p SF6 ; The gas pressure P in the first buffer tank at time t1 c1 The temperature is equal to the current temperature T1 of the gas in the gas chamber. The gas density ρ in the first buffer tank is calculated using empirical formulas. c1 Given the volume V of the first buffer tank c The mass of gas in the first buffer tank is m k2 = V c ×ρ c1 ; The amount of gas reduction m in the gas chamber during the time t1 from the start of recovery is calculated s1 = m k1 + m k2 ; According to the temperature T1 and the pressure P1 of the gas chamber after recovery, the gas density ρ1 of the gas chamber after recovery is calculated by combining the empirical formula, and the effective volume V of the gas chamber can be further calculated: V = m s1 / (p0-p1); The gas volume is m=V×ρ0. Recovery: ξ = m s1 / m.

8. The SF6 recovery method with recovery rate measurement function according to claim 6, characterized by: A vacuum gauge and a vacuum pump are arranged on the pipeline between the third electromagnetic valve and the fifth electromagnetic valve, the output end of the vacuum pump is communicated with an exhaust port, and the vacuum gauge and the vacuum pump are connected with the PLC controller.

9. The SF6 recovery method with recovery rate measurement function according to claim 8, characterized by: If it is necessary to vacuumize the device, the second electromagnetic valve and the fourth electromagnetic valve are closed, the first electromagnetic valve, the third electromagnetic valve and the fifth electromagnetic valve are opened, and the vacuum pump is started to exhaust the residual gas, and the vacuumization is stopped when it is detected that the pressure of the vacuum gauge is lower than 10 Pa.

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