SF6 gas equipment gas supply device and method for calculating total gas volume in low-temperature environment
By introducing a gas storage tank and a semiconductor refrigerator into the SF6 gas equipment gas replenishment device, combined with a constant temperature box and a heat exchanger, the problem of inaccurate total gas volume measurement in a low-temperature environment is solved, and accurate total gas volume calculation is achieved.
Patent Information
- Application Number
- CN202310233660.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-03-10
- Publication Date
- 2025-09-30
- Estimated Expiration
- 2043-03-10
AI Technical Summary
In low-temperature environments, existing technologies cannot accurately measure the total amount of gas in SF6 gas equipment, especially during large-scale gas replenishment operations in winter. The range utilization rate of mass flow controllers and pressure sensors is not high, resulting in inaccurate flow control, and the temperature sensor cannot accurately reflect the internal temperature of the gas equipment, resulting in large measurement errors.
Abstract: In order to improve the measurement accuracy of the gas supply device, a gas supply device with gas supply pipeline and auxiliary measurement pipeline was designed. The gas temperature was adjusted by using a gas storage tank and a semiconductor cooler. The total amount of gas was calculated by the gas pressure balance of the gas storage tank. A constant temperature box and a heat exchanger were used to keep the gas temperature consistent, reducing the impact of temperature changes on the measurement. The experimental results show that the gas supply device has a good performance in the field of gas measurement and has a good effect on the measurement accuracy ...
It realizes the accurate total gas volume measurement of SF6 gas equipment in low temperature environment, reduces the measurement error caused by insufficient pressure sensor accuracy and temperature change, and ensures the accuracy of gas replenishment.
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Figure CN116336379B_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of sulfur hexafluoride gas recovery, and relates to a gas replenishing device and method for SF6 gas equipment used for calculating the total amount of gas in a low-temperature environment. Background Art
[0002] Calculating the total amount of sulfur hexafluoride (SF6) gas in operating SF6 gas equipment and achieving lean management of the entire SF6 gas life cycle are important measures to achieve emission reduction goals. Currently, the total amount of SF6 gas is calculated by measuring the total amount of gas through a confined space gas total amount measuring device when the SF6 gas equipment is undergoing recovery and refilling operations. The principle is to use a mass flow controller to calculate the amount of gas to be recovered or replenished, and based on the temperature and pressure data monitored by the pressure and temperature sensors before and after recovery and refilling, combined with the Beattie-Bridgman density empirical model, to calculate the effective volume and total amount of gas in the confined space. However, SF6 gas equipment often only undergoes recovery and refilling operations once every few years, and using the above-mentioned devices to calculate SF6 usage and emissions is extremely inefficient.
[0003] According to field maintenance and inspection experience, due to the low winter temperatures in northern China and other provinces, large-scale gas replenishment operations are often carried out during the winter to ensure the arc extinguishing and insulation properties of SF6 gas. The replenishment pressure is generally around 0.02-0.03 MPa, and the replenishment volume is relatively small, far lower than the replenishment volume and pressure of 0.3-0.7 MPa required for refilling operations. Therefore, using existing confined space gas volume measurement devices for winter replenishment operations can lead to inaccurate control or measurement results at low flow rates and slight pressure changes due to the large range of mass flow controllers and pressure sensors. Furthermore, due to the low winter temperatures in northern China, the bottled SF6 undergoes a vaporization process when filled into the gas equipment, further lowering the SF6 gas temperature. Due to the limitations of the temperature sensor's detection location, the measured temperature value cannot represent the SF6 gas temperature inside the gas equipment, resulting in unreliable effective volume and gas volume calculated based on this temperature.
[0004] In summary, the existing technology of using a confined space gas total amount measuring device to measure the total amount of gas in the operation of sulfur hexafluoride gas equipment has the following disadvantages:
[0005] (1) For mass flow controllers, the control results are generally most accurate when the full scale is around 80%. In winter, the air supply volume is small. If a large-scale mass flow controller is used, the range utilization rate is not high and the flow control is not accurate.
[0006] (2) For pressure sensors, the commonly used pressure sensor measurement error is ±0.001MPa, while the pressure difference of air replenishment in winter is usually 0.02~0.03MPa, and the measurement error cannot be ignored.
[0007] (3) For the temperature sensor, the temperature of the SF6 liquid in the cylinder will drop after it is vaporized. The temperature difference between the filling gas and the original SF6 gas inside the equipment is large. The temperature sensor is close to the filling and discharging interface, and its temperature cannot represent the internal temperature of the gas equipment, which will lead to excessive gas replenishment and inaccurate measurement of the total amount of SF6 gas in the SF6 gas transportation equipment. Summary of the Invention
[0008] The technical problem to be solved by the present invention is how to design a gas replenishment device and method for calculating the total amount of gas in a low-temperature environment, so as to accurately obtain the total amount of SF6 gas in the operating SF6 gas equipment during large-scale gas replenishment operations in winter.
[0009] The present invention solves the above technical problems through the following technical solutions:
[0010] A gas supply device for SF6 gas equipment used for calculating the total amount of gas in a low-temperature environment comprises: a gas supply pipeline and an auxiliary measurement pipeline; the gas supply pipeline comprises: a first temperature sensor (1), a first pressure sensor (2), a first solenoid valve (3), a third solenoid valve (9), a fourth solenoid valve (10), a mass flow controller (11), a third temperature sensor (12), a constant temperature box (14), a heat exchanger (15), and a fifth solenoid valve (16); the auxiliary measurement pipeline comprises: a semiconductor refrigerator (4), a gas storage tank (5), a second temperature sensor (6), a second pressure sensor (7), a second solenoid valve (8), and an exhaust port (13); the first temperature sensor (1) and the first pressure sensor (2) are respectively installed on the pipeline at one end of the first solenoid valve (3), the other end of the first solenoid valve (3) is sealedly connected to one end of the third solenoid valve (9), the other end of the third solenoid valve (9) is sealedly connected to one end of the mass flow controller (11), and the other end of the mass flow controller (11) is sealed to the heat exchanger. One end of the heat exchanger (15) is sealed and connected to the heat exchanger (15), and the other end of the heat exchanger (15) is sealed and connected to one end of the fifth solenoid valve (16); the heat exchanger (15) is placed in the constant temperature box (14); the third temperature sensor (12) is installed between the mass flow controller (11) and the heat exchanger (15) and is used to detect the gas temperature at the output end of the heat exchanger (15); one end of the second solenoid valve (8) is sealed and connected between the first solenoid valve (3) and the third solenoid valve (9), and the other end of the second solenoid valve (8) is sealed and connected to the heat exchanger (15). The end of the gas storage tank (5) is sealed and connected to the input end of the gas storage tank (5), the output end of the gas storage tank (5) is sealed and connected to one end of the fourth solenoid valve (10), and the other end of the fourth solenoid valve (10) is sealed and connected to the exhaust port (13); the second temperature sensor (6) and the second pressure sensor (7) are respectively sealed and installed on the top of the gas storage tank (5) for measuring the temperature and pressure inside the gas storage tank (5); a semiconductor refrigerator (4) is installed on the shell of the gas storage tank (5) for heating or cooling the gas storage tank (5).
[0011] A method for applying the SF6 gas equipment gas replenishment device for calculating the total amount of gas in a low-temperature environment comprises the following steps:
[0012] S1. Measure the initial temperature and pressure in the SF6 gas equipment and the gas storage tank (5), and calculate the initial SF6 gas density ρ in the SF6 gas equipment s0 ;
[0013] After the first pressure balance between S2, SF6 gas equipment and gas storage tank (5), calculate the SF6 gas density ρ in the SF6 gas equipment s1 ;
[0014] S3. Calculate the mass m of SF6 gas in the gas tank (5) after the first pressure balance. k1;
[0015] S4. The gas supply pipeline charges the SF6 gas equipment and calculates the mass m1 of SF6 gas charged into the SF6 gas equipment;
[0016] After the second pressure balance of S5, SF6 gas equipment and gas storage tank (5), the SF6 gas density ρ in the SF6 gas equipment is calculated again. s3 ;
[0017] S6. Calculate the mass m of SF6 gas in the gas tank (5) after the second pressure balance. k4 ;
[0018] S7. Calculate the gas supply volume of SF6 gas equipment;
[0019] S8. Tail gas recovery.
[0020] Furthermore, the initial temperature and pressure in the SF6 gas equipment and the gas storage tank (5) are measured in step S1, and the initial SF6 gas density ρ in the SF6 gas equipment is calculated. s0 The method is as follows:
[0021] S11, the device is sealed and connected to the SF6 gas equipment and the SF6 cylinder respectively, and the first temperature sensor (1) and the first pressure sensor (2) measure the gas temperature and pressure inside the SF6 gas equipment as T s0 and P s0 ;
[0022] S12. Calculate the initial SF6 gas density ρ in the SF6 gas equipment based on the Beattie-Bridgman density empirical model s0 ;
[0023] The formula of the Beattie-Bridgman density empirical model is as follows:
[0024]
[0025] Where ρ is the density of SF6 gas, unit is kg / m 3 ; T is the thermodynamic temperature of sulfur hexafluoride gas, which is 293K.
[0026] Furthermore, after the first pressure balance between the SF6 gas equipment and the gas storage tank (5) in step S2, the SF6 gas density ρ in the SF6 gas equipment is calculated. s1The method is specifically as follows: the first solenoid valve (3) and the second solenoid valve (8) are opened, and the other solenoid valves are closed. The SF6 gas in the SF6 gas equipment enters the gas storage tank (5) under the action of the pressure difference. After the pressure is balanced, the temperature and pressure values inside the SF6 gas equipment measured by the first temperature sensor (1) and the first pressure sensor (2) are the same as the temperature and pressure values inside the gas storage tank (5) measured by the second temperature sensor (6) and the second pressure sensor (7), which are recorded as T s1 、P s1 Then, close the first solenoid valve (3) and the second solenoid valve (8), and calculate the density ρ of the SF6 gas equipment by formula (1) s1 .
[0027] Furthermore, the calculation of the SF6 gas mass m in the gas storage tank (5) after the first pressure balance in step S3 is performed. k1 The method is as follows: the semiconductor refrigerator (4) is turned on to heat the gas storage tank (5); when the second temperature sensor (6) detects the SF6 gas temperature T in the gas storage tank (5), k1 When the threshold is reached, heating is stopped and the pressure P in the gas storage tank (5) is measured by the second pressure sensor (7). k1 , and calculate the density ρ according to formula (1) k1 , further calculate the SF6 gas mass m in the gas tank (5) k1 =V k ×ρ k1 Then, the semiconductor refrigerator (4) starts to cool the SF6 gas in the gas tank (5) down to the ambient temperature T d .
[0028] Furthermore, the method for charging the SF6 gas equipment with the gas supply pipeline in step S4 and calculating the mass m1 of SF6 gas charged into the SF6 gas equipment is as follows: the temperature of the thermostat (14) is set at T c ℃, at this time, the fifth solenoid valve (16) is opened, and the SF6 gas enters the heat exchanger (15), and the temperature of the SF6 gas is increased; the output flow of the mass flow controller (11) is set to Q, the first solenoid valve (3) and the third solenoid valve (9) are opened to continuously inflate the SF6 gas equipment, the first temperature sensor (1) and the first pressure sensor (2) continuously monitor the temperature and pressure of the SF6 gas equipment, and the detected pressure value P s2 The pressure value P calculated to 20℃ 20 s2 , when P 20 s2 =P t When the third solenoid valve (9) and the fifth solenoid valve (16) are closed, the gas supply to the gas equipment stops, and P tis the target inflation pressure set at 20°C; record the gas output time t1 of the mass flow controller (11), and calculate the mass of SF6 gas that has been filled into the SF6 gas equipment. The calculation method is: the total volume of SF6 gas filled into the SF6 gas equipment during this period V1 = t1 × Q, and the density of SF6 gas at standard pressure ρ = 6.0886 kg / m 3 , and further calculate the SF6 gas mass in this stage: m1 = V1 × ρ.
[0029] Furthermore, after the second pressure balance between the SF6 gas equipment and the gas storage tank (5) in step S5, the SF6 gas density ρ in the SF6 gas equipment is calculated again. s3 The method is specifically as follows: the second solenoid valve (8) is opened, and the switch states of the other solenoid valves remain unchanged. Under the action of the pressure difference, the pressure of the SF6 gas inside the SF6 gas equipment and the pressure inside the gas storage tank (5) will be balanced again. After the pressure is balanced, the temperature and pressure values inside the SF6 gas equipment measured by the first temperature sensor (1) and the first pressure sensor (2) are the same as the temperature and pressure values inside the gas storage tank (5) measured by the second temperature sensor (6) and the second pressure sensor (7), which are recorded as T s3 、P s3 Then, close the first solenoid valve (3) and the second solenoid valve (8), and calculate the density ρ of the gas equipment by formula (1) s3 .
[0030] Furthermore, the calculation of the SF6 gas mass m in the gas storage tank (5) after the second pressure balance in step S6 is performed. k4 The method is specifically as follows: turning on the semiconductor refrigerator (4) to heat the gas storage tank (5); when the second temperature sensor (6) detects the SF6 gas temperature T in the gas storage tank (5), k1 When the threshold is reached, heating is stopped and the pressure P in the gas tank (5) is measured by the second pressure sensor (7). k4 , and calculate the density ρ according to formula (1) k4 , further calculate the SF6 gas mass m in the gas tank (5) k4 =V k ×ρ k4 Then, the semiconductor refrigerator (4) starts to cool the SF6 gas in the gas tank (5) down to the ambient temperature T d .
[0031] Furthermore, the method for calculating the gas supply volume of the SF6 gas equipment in step S7 is as follows: the mass of the gas filled into the gas storage tank (5) is △m k =m k1 -m k4 , so the mass of gas filled into the SF6 gas equipment is △m s=m1-△m k Since the pressure of the SF6 gas equipment and the gas storage tank 5 are balanced and the temperature is the same at the beginning and end of the t1 period, the density is also the same. Therefore, the ratio of the mass of the gas filled into the SF6 gas equipment to the mass of the gas filled into the gas storage tank (5) is equal to the ratio of the effective volume of the SF6 gas equipment to the effective volume of the gas storage tank (5), that is: V s =△m s ×V k / △m k ; According to the effective volume V of SF6 gas equipment s , calculate the total amount of gas in the SF6 gas equipment m s =ρ s3 ×V s .
[0032] Furthermore, the tail gas recovery method described in step S8 is specifically as follows: after the gas replenishment is completed, all solenoid valves are closed, and the empty cylinder is sealed and connected to the exhaust port (13). At this time, the fourth solenoid valve (10) is opened again, and the SF6 gas remaining in the gas storage tank (5) will flow into the empty cylinder for recovery under the action of the pressure difference.
[0033] The advantages of the present invention are:
[0034] The invention discloses an SF6 gas equipment gas supply device for calculating the total amount of gas in a low-temperature environment. The device supplies gas to the SF6 gas equipment through a gas supply pipeline. An auxiliary measuring pipeline is provided on the gas supply pipeline. A gas storage tank (5) is provided in the auxiliary measuring pipeline. The pressure between the SF6 gas equipment and the gas storage tank (5) is balanced twice. The total amount of gas in the SF6 gas equipment is calculated by detecting the gas pressure of the gas storage tank (5) instead of directly detecting the gas pressure of the SF6 gas equipment. The total amount of gas in the SF6 gas equipment is accurately measured while supplying gas, thereby reducing the measurement error of the total amount of gas in the SF6 gas equipment caused by insufficient accuracy of the pressure sensor when the pressure difference before and after the gas supply is small. At the same time, a constant temperature box (14) and a heat exchanger (15) are provided in the gas supply pipeline, so that the temperature of the SF6 gas filled into the SF6 gas equipment is close to the ambient temperature, thereby avoiding the phenomenon that the temperature of the SF6 gas filled into the SF6 gas equipment is too low due to the absorption of heat by gasification of liquid SF6, thereby causing excessive gas supply and inaccurate measurement of the total amount of gas in the SF6 gas equipment. The device can well adapt to the working environment of gas supply in winter. BRIEF DESCRIPTION OF THE DRAWINGS
[0035] Figure 1 This is a structural diagram of a gas replenishing device for SF6 gas equipment used for calculating the total amount of gas in a low-temperature environment according to a first embodiment of the present invention. DETAILED DESCRIPTION
[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.
[0037] The technical solution of the present invention is further described below with reference to the accompanying drawings and specific embodiments:
[0038] Example 1
[0039] 1. Composition and structure of the device
[0040] like Figure 1 As shown, a gas supply device for SF6 gas equipment for calculating the total amount of gas in a low-temperature environment comprises: a first temperature sensor (1), a first pressure sensor (2), a first solenoid valve (3), a semiconductor refrigerator (4), a gas storage tank (5), a second temperature sensor (6), a second pressure sensor (7), a second solenoid valve (8), a third solenoid valve (9), a fourth solenoid valve (10), a mass flow controller (11), a third temperature sensor (12), an exhaust port (13), a constant temperature box (14), a heat exchanger (15), and a fifth solenoid valve (16).
[0041] One end of the first solenoid valve (3) is connected to the gas charging and discharging interface of the SF6 gas equipment through a pipeline seal, the other end of the first solenoid valve (3) is connected to one end of the third solenoid valve (9) through a pipeline seal, the other end of the third solenoid valve (9) is connected to one end of the mass flow controller (11) through a pipeline seal, the other end of the mass flow controller (11) is connected to one end of the heat exchanger (15) through a pipeline seal, the other end of the heat exchanger (15) is connected to one end of the fifth solenoid valve (16) through a pipeline seal, the other end of the fifth solenoid valve (16) is connected to one end of the pressure reducing valve (17) through a pipeline seal. The pipeline is sealed and connected, and the other end of the pressure reducing valve (17) is sealed and connected to the SF6 cylinder through the pipeline; the first temperature sensor (1) and the first pressure sensor (2) are respectively sealed and installed on the pipeline between the charging and discharging interface of the SF6 gas equipment and the first solenoid valve (3), and are used to measure the temperature and pressure inside the SF6 gas equipment; the third temperature sensor (12) is sealed and installed on the pipeline between the mass flow controller (11) and the heat exchanger (15), and is used to detect the gas temperature at the output end of the heat exchanger (15); the heat exchanger (15) is placed in a constant temperature box (14).
[0042] One end of the second solenoid valve (8) is sealedly connected to the pipeline between the first solenoid valve (3) and the third solenoid valve (9) through a pipeline, the other end of the second solenoid valve (8) is sealedly connected to the input end of the gas storage tank (5) through a pipeline, the output end of the gas storage tank (5) is sealedly connected to one end of the fourth solenoid valve (10) through a pipeline, and the other end of the fourth solenoid valve (10) is sealedly connected to the exhaust port (13) through a pipeline; the second temperature sensor (6) and the second pressure sensor (7) are respectively sealedly installed on the top of the gas storage tank (5) for measuring the temperature and pressure inside the gas storage tank (5); a semiconductor refrigerator (4) is installed on the shell of the gas storage tank (5) for heating or cooling the gas storage tank (5).
[0043] 2. Workflow of the device
[0044] The working process of the device for measuring the total amount of gas in low-temperature environment SF6 gas equipment is as follows:
[0045] (1) All valves in the device are initially in the closed state. The gas inlet end of the device is sealed and connected to the SF6 cylinder through the pressure reducing valve (17), and the gas outlet end of the device is sealed and connected to the charging and discharging interface of the SF6 gas equipment. At this time, the first temperature sensor (1) and the first pressure sensor (2) measure the gas temperature and pressure inside the SF6 gas equipment as T s0 and P s0 The second temperature sensor (6) and the second pressure sensor (7) measure the initial temperature T in the gas storage tank (5) (a small amount of SF6 gas remains inside, and the pressure is much lower than the pressure of the SF6 gas equipment) k0 and pressure P k0 ;
[0046] The initial SF6 gas density ρ in the SF6 gas equipment and gas tank (5) is calculated based on the Beattie-Bridgman density empirical model. s0 and ρ k0 :
[0047] The formula of the Beattie-Bridgman density empirical model is as follows:
[0048]
[0049] Where ρ is the density of SF6 gas, unit is kg / m 3 ; T is the thermodynamic temperature of sulfur hexafluoride gas, which is 293K.
[0050] It is known that the effective volume of the gas tank (5) is V k =5L, so the initial mass m of SF6 gas in the gas tank (5) can be calculated k0 =V k×ρ k0 .
[0051] (2) Open the first solenoid valve (3) and the second solenoid valve (8), and close the other solenoid valves. The SF6 gas in the SF6 gas equipment enters the gas storage tank (5) under the action of the pressure difference. Due to the effective volume V k =5L. Compared with the SF6 gas equipment with a volume unit of cubic meters, the pressure drop is only tens of kPa, which will not affect the normal operation of the SF6 gas equipment. After the pressure is balanced, the temperature and pressure values inside the SF6 gas equipment measured by the first temperature sensor (1) and the first pressure sensor (2) are the same as the temperature and pressure values inside the gas storage tank (5) measured by the second temperature sensor (6) and the second pressure sensor (7), which are recorded as T s1 、P s1 Then, close the first solenoid valve (3) and the second solenoid valve (8), and calculate the density ρ of the gas equipment by formula (1) s1 .
[0052] (3) At this time, the semiconductor refrigerator (4) is turned on to heat the gas storage tank (5). When the second temperature sensor (6) detects the SF6 gas temperature T in the gas storage tank (5), k1 =60℃, the heating is stopped, and the pressure P in the gas storage tank (5) is measured by the second pressure sensor (7). k1 , and calculate the density ρ according to formula (1) k1 , further calculate the SF6 gas mass m in the gas tank (5) k1 =V k ×ρ k1 Then, the semiconductor refrigerator (4) starts to cool the SF6 gas in the gas tank (5) down to the ambient temperature T d Heating the gas storage tank (5) increases the pressure of the SF6 gas in the tank, which helps the second pressure sensor (7) reduce measurement errors.
[0053] (4) Set the temperature of the thermostat (14) to T c ℃, where T c =T d +10℃, preheat for 3 minutes in advance, adjust the pressure reducing valve (17) to reduce the SF6 gas pressure in the SF6 cylinder to 0.8MPa; at this time, open the fifth solenoid valve (16), and the SF6 gas enters the heat exchanger (15), and the SF6 gas is heated. The third temperature sensor (12) detects the gas temperature T after the heat exchanger (15) is heated. p , if |T p -T d |≤2℃, then keep the temperature of the thermostat (14) unchanged; if T p <T d-2, then the temperature of the thermostat (14) is T c Increase by 4℃, that is, T c =T d +14℃; On the contrary, if T p >T d +2, then the temperature of the thermostat (14) is T c Lower by 4℃, that is, T c =T d +6℃; then the third temperature sensor (12) detects the gas temperature T after the heat exchanger (15) is heated again p If it meets the requirements, proceed to the next step. If it does not meet the requirements, continue to heat up or cool down according to the above mode.
[0054] (5) Set the output flow rate of the mass flow controller (11) to Q = 14.4m 3 / h (The range of mass flow controller should not be too large, generally not more than 15m 3 / h, because the gas volume of the replenishment gas in winter is small, if a large range is used, the range utilization rate is low, and the output gas flow error is also large. Generally, the output accuracy is highest at 80% of the range, such as the range of 18m 3 / h, the output flow rate is set to 14.4m 3 / h or so), the error is lowest), the first solenoid valve (3) and the third solenoid valve (9) are opened to continuously inflate the SF6 gas equipment, the first temperature sensor (1) and the first pressure sensor (2) continuously monitor the temperature and pressure of the SF6 gas equipment, and the detected pressure value P s2 The pressure value P calculated to 20℃ 20 s2 , when P 20 s2 =P t When the third solenoid valve (9), the fifth solenoid valve (16) and the pressure reducing valve (17) are closed, the gas supply to the gas equipment is stopped, and P t is the target inflation pressure set at 20°C; record the gas output time t1 of the mass flow controller (11), and calculate the mass of SF6 gas that has been filled into the SF6 gas equipment. The calculation method is: the total volume of SF6 gas filled into the SF6 gas equipment during this period V1 = t1 × Q, and the density of SF6 gas at standard pressure ρ = 6.0886 kg / m 3 , the SF6 gas mass in this stage can be further calculated as m1=V1×ρ.
[0055] (6) At this time, the first temperature sensor (1) measures P s2 >P k1, open the second solenoid valve (8) again, and the switch states of other solenoid valves remain unchanged. Under the action of the pressure difference, the pressure of the SF6 gas inside the SF6 gas equipment and the pressure inside the gas storage tank (5) will be balanced again. After the pressure is balanced, the temperature and pressure values inside the SF6 gas equipment measured by the first temperature sensor (1) and the first pressure sensor (2) are the same as the temperature and pressure values inside the gas storage tank (5) measured by the second temperature sensor (6) and the second pressure sensor (7), which are recorded as T s3 、P s3 Then, close the first solenoid valve (3) and the second solenoid valve (8), and calculate the density ρ of the gas equipment by formula (1) s3 .
[0056] (7) At this time, the semiconductor refrigerator (4) is turned on again to heat the gas storage tank (5). When the second temperature sensor (6) detects the SF6 gas temperature T in the gas storage tank (5), k1 =60℃, the heating is stopped, and the pressure P in the gas storage tank (5) is measured by the second pressure sensor (7). k4 , and calculate the density ρ according to formula (1) k4 , further calculate the SF6 gas mass m in the gas tank (5) k4 =V k ×ρ k4 Then, the semiconductor refrigerator (4) starts to cool the SF6 gas in the gas tank (5) down to the ambient temperature T d .
[0057] (8) The mass of gas filled into the gas tank (5) is △m k =m k1 -m k4 , so the mass of gas filled into the SF6 gas equipment is △m s =m1-△m k Since the pressure of the SF6 gas equipment and the gas storage tank 5 are balanced and the temperature is the same at the beginning and end of the t1 period, the density is also the same. Therefore, the ratio of the mass of the gas filled into the SF6 gas equipment to the mass of the gas filled into the gas storage tank (5) is equal to the ratio of the effective volume of the SF6 gas equipment to the effective volume of the gas storage tank (5), that is: V s =△m s ×V k / △m k ; According to the effective volume V of SF6 gas equipment s , the total amount of gas in the SF6 gas equipment can be calculated m s =ρ s3 ×V s , then the gas supply volume of SF6 gas equipment is m 1 s =(ρ s3-ρ s0 )×V s .
[0058] (9) After the gas replenishment is completed, all electromagnetic valves are closed and the empty cylinder is sealed and connected to the exhaust port (13). At this time, the fourth electromagnetic valve (10) is opened again. Under the action of the pressure difference, the SF6 gas remaining in the gas storage tank (5) will flow into the empty cylinder for recovery.
[0059] 3. Test measurement data
[0060] Take the volume as 0.3m 3 and 11.0m 3 The two gas devices have initial pressures of 0.35 MPa and 0.65 MPa (relative pressure, at 20° C.), and the pressure values at different temperatures are measured at the "initial" stage, the "starting" stage when the gas in the SF6 gas device enters the gas storage tank (5), and the "t moment" stage at the end of the t time period. As can be seen from the table below, compared with the gas supply pressure differences of 0.015 MPa, 0.020 MPa and 0.030 MPa, the pressure difference of the device of the present invention is increased by about 1.5 times, which can effectively reduce the gas volume calculation error caused by the small change of the gas supply pressure difference.
[0061]
[0062]
[0063] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.
Claims
1. A method for calculating the total amount of gas in a low-temperature environment using an SF6 gas equipment gas supply device, characterized in that: The SF6 gas supply device for calculating the total amount of gas in a low-temperature environment comprises: a supply pipeline and an auxiliary measuring pipeline; the supply pipeline comprises: a first temperature sensor (1), a first pressure sensor (2), a first solenoid valve (3), a third solenoid valve (9), a fourth solenoid valve (10), a mass flow controller (11), a third temperature sensor (12), a constant temperature box (14), a heat exchanger (15), and a fifth solenoid valve (16); the auxiliary measuring pipeline comprises: a semiconductor refrigerator (4), a gas storage tank (5), a second temperature sensor (6), a second pressure sensor (7), a second solenoid valve (8), and an exhaust port (13); the first temperature sensor (1) and the first pressure sensor (2) are respectively installed on the pipeline at one end of the first solenoid valve (3), the other end of the first solenoid valve (3) is sealedly connected to one end of the third solenoid valve (9), the other end of the third solenoid valve (9) is sealedly connected to one end of the mass flow controller (11), and the other end of the mass flow controller (11) is sealed to the heat exchanger. (15) is sealed and connected to one end of the heat exchanger (15), and the other end of the heat exchanger (15) is sealed and connected to one end of the fifth solenoid valve (16); the heat exchanger (15) is placed in the constant temperature box (14); the third temperature sensor (12) is installed between the mass flow controller (11) and the heat exchanger (15) and is used to detect the gas temperature at the output end of the heat exchanger (15); one end of the second solenoid valve (8) is sealed and connected between the first solenoid valve (3) and the third solenoid valve (9), and the other end of the second solenoid valve (8) is sealed and connected to the first solenoid valve (3) and the third solenoid valve (9). The end of the gas storage tank (5) is sealed and connected to the input end of the gas storage tank (5), the output end of the gas storage tank (5) is sealed and connected to one end of the fourth solenoid valve (10), and the other end of the fourth solenoid valve (10) is sealed and connected to the exhaust port (13); the second temperature sensor (6) and the second pressure sensor (7) are respectively sealed and installed on the top of the gas storage tank (5) for measuring the temperature and pressure inside the gas storage tank (5); a semiconductor refrigerator (4) is installed on the shell of the gas storage tank (5) for heating or cooling the gas storage tank (5); The method comprises the following steps: S1. Measure the initial temperature and pressure in the SF6 gas equipment and the gas tank (5), and calculate the initial SF6 gas density ρ in the SF6 gas equipment. s0 , the specific method is as follows: S11. The device is sealed and connected to the SF6 gas equipment and the SF6 cylinder respectively. The first temperature sensor (1) and the first pressure sensor (2) measure the gas temperature and pressure inside the SF6 gas equipment as T. s0 and P s0 ; S12. Calculate the initial SF6 gas density ρ in the SF6 gas equipment based on the Beattie-Bridgman density empirical model s0 ; The formula of the Beattie-Bridgman density empirical model is as follows: P=(R×T×BA)ρ 2 +R×T×ρ A=73.882×10 -5 -5.132105×10 -7 r B=2.50695×10 -3 -2.12283×10 -6 r R=56.9502×10 -5 Where ρ is the density of SF6 gas, unit is kg / m 3 ; T is the thermodynamic temperature of sulfur hexafluoride gas, which is 293K; After the first pressure balance between S2, SF6 gas equipment and gas tank (5), calculate the SF6 gas density ρ in the SF6 gas equipment. s1 The method is as follows: open the first solenoid valve (3) and the second solenoid valve (8), and close all other solenoid valves. The SF6 gas in the SF6 gas equipment enters the gas storage tank (5) under the action of the pressure difference. After the pressure is balanced, the temperature and pressure values inside the SF6 gas equipment measured by the first temperature sensor (1) and the first pressure sensor (2) are the same as the temperature and pressure values inside the gas storage tank (5) measured by the second temperature sensor (6) and the second pressure sensor (7), which are recorded as T s1 、P s1 Then, close the first solenoid valve (3) and the second solenoid valve (8), and calculate the density ρ of the SF6 gas equipment by the formula of the Beattie-Bridgman density empirical model. s1 ; S3. Calculate the mass m of SF6 gas in the gas tank (5) after the first pressure balance. k1 ; S4. The gas supply pipeline charges the SF6 gas equipment and calculates the mass m1 of SF6 gas charged into the SF6 gas equipment; After the second pressure balance between S5, SF6 gas equipment and gas storage tank (5), calculate the SF6 gas density ρ in the SF6 gas equipment again. s3 ; S6. Calculate the mass m of SF6 gas in the gas tank (5) after the second pressure balance. k4 ; S7. Calculate the gas supply volume of SF6 gas equipment; S8. Tail gas recovery.
2. The method according to claim 1, characterized in that The calculation in step S3 of the SF6 gas mass m in the gas storage tank (5) after the first pressure balance is performed is: k1 The method is as follows: the semiconductor refrigerator (4) is turned on to heat the gas storage tank (5); when the second temperature sensor (6) detects the SF6 gas temperature T in the gas storage tank (5), k1 When the threshold is reached, heating is stopped and the pressure P in the gas tank (5) is measured by the second pressure sensor (7). k1 , and calculate the density ρ according to the formula of the Beattie-Bridgman density empirical model k1 , further calculate the SF6 gas mass m in the gas tank (5) k1 =V k ×ρ k1 Then, the semiconductor refrigerator (4) starts to cool the SF6 gas in the gas storage tank (5) down to the ambient temperature T d .
3. The method according to claim 2, characterized in that The method of charging the SF6 gas equipment with the gas supply pipeline in step S4 and calculating the mass m1 of SF6 gas charged into the SF6 gas equipment is as follows: the temperature of the thermostat (14) is set at T c ℃, at this time, the fifth solenoid valve (16) is opened, and the SF6 gas enters the heat exchanger (15), and the temperature of the SF6 gas is increased; the output flow of the mass flow controller (11) is set to Q, and the first solenoid valve (3) and the third solenoid valve (9) are opened to continuously inflate the SF6 gas equipment, and the first temperature sensor (1) and the first pressure sensor (2) continuously monitor the temperature and pressure of the SF6 gas equipment, and the detected pressure value P s2 The pressure value P calculated to 20℃ 20 s2 , when P 20 s2 =P t When the third solenoid valve (9) and the fifth solenoid valve (16) are closed, the charging of the SF6 gas equipment is stopped, and P t is the target inflation pressure set at 20°C; record the gas output time t1 of the mass flow controller (11), and calculate the mass of SF6 gas that has been filled into the SF6 gas equipment. The calculation method is: the total volume of SF6 gas filled into the SF6 gas equipment during this period is V1=t1×Q, and the density of SF6 gas at standard pressure is ρ=6.0886kg / m 3 , and further calculate the SF6 gas mass m1=V1×ρ in this stage.
4. The method according to claim 3, characterized in that After the second pressure balance between the SF6 gas equipment and the gas storage tank (5) in step S5, the SF6 gas density ρ in the SF6 gas equipment is calculated again. s3 The method is specifically as follows: the second solenoid valve (8) is opened, and the switch states of the other solenoid valves remain unchanged. Under the action of the pressure difference, the pressure of the SF6 gas inside the SF6 gas equipment and the pressure inside the gas storage tank (5) will be balanced again. After the pressure is balanced, the temperature and pressure values inside the SF6 gas equipment measured by the first temperature sensor (1) and the first pressure sensor (2) are the same as the temperature and pressure values inside the gas storage tank (5) measured by the second temperature sensor (6) and the second pressure sensor (7), which are recorded as T s3 、P s3 Then, close the first solenoid valve (3) and the second solenoid valve (8), and calculate the density ρ of the SF6 gas equipment by the formula of the Beattie-Bridgman density empirical model. s3 .
5. The method according to claim 4, characterized in that The calculation of the SF6 gas mass m in the gas storage tank (5) after the second pressure balance described in step S6 is k4 The method is specifically as follows: the semiconductor refrigerator (4) is turned on to heat the gas storage tank (5); when the second temperature sensor (6) detects the SF6 gas temperature T in the gas storage tank (5), k1 When the threshold is reached, heating is stopped and the pressure P in the gas tank (5) is measured by the second pressure sensor (7). k4 , and calculate the density ρ according to the formula of the Beattie-Bridgman density empirical model k4 , further calculate the SF6 gas mass m in the gas tank (5) k4 =V k ×ρ k4 Then, the semiconductor refrigerator (4) starts to cool the SF6 gas in the gas storage tank (5) down to the ambient temperature T d .
6. The method according to claim 5, characterized in that The method for calculating the gas supply volume of the SF6 gas equipment in step S7 is as follows: the mass of gas filled into the gas storage tank (5) is △m k =m k1 -m k4 , so the mass of gas filled into the SF6 gas equipment is △m s =m1-△m k Since the pressure of the SF6 gas equipment and the gas storage tank (5) are balanced and the temperature is the same at the beginning and end of the t1 period, the density is also the same. Therefore, the ratio of the mass of the gas filled into the SF6 gas equipment to the mass of the gas filled into the gas storage tank (5) is equal to the ratio of the effective volume of the SF6 gas equipment to the effective volume of the gas storage tank (5), that is: V s =△m s ×V k / △m k ; According to the effective volume V of SF6 gas equipment s , calculate the total amount of gas in the SF6 gas equipment m s =ρ s3 ×V s .
7. The method according to claim 6, characterized in that The tail gas recovery method described in step S8 is specifically as follows: after the gas replenishment is completed, all solenoid valves are closed, and the empty cylinder is sealed and connected to the exhaust port (13). At this time, the fourth solenoid valve (10) is opened, and the SF6 gas remaining in the gas storage tank (5) will flow into the empty cylinder for recovery under the action of the pressure difference.