WO2018223441A1

WO2018223441A1 - High-speed suction gun leakage detection method and device for sealed element of large-sized transformer

Info

Publication number: WO2018223441A1
Application number: PCT/CN2017/090470
Authority: WO
Inventors: 张丛
Original assignee: 深圳市樊溪电子有限公司
Priority date: 2017-06-05
Filing date: 2017-06-28
Publication date: 2018-12-13
Also published as: CN107179163A; CN107179163B

Abstract

Provided is a high-speed suction gun leakage detection device and method for a sealed element of a large-sized transformer. The high-speed suction gun leakage detection device comprises a high-speed suction gun (1), a sampling pipe (2), a filter (3), a high-power suction pump (4), a helium separator (5), and a helium mass spectrometer (6), wherein an air carrier gas enters into a probe of the high-speed suction gun (1), passes through a first branch (2-1) of the sampling pipe (2), and is extracted by the high-power suction pump (4). After entering into the probe of the high-speed suction gun (1), helium gas leaking from a leak hole of the sealed element under detection of the large-sized transformer, travels with the air carrier gas provided by the high-power suction pump (4), passes through the helium separator (5) via a second branch (2-2) of the sampling pipe (2), enters into a mass spectrometry chamber of the helium mass spectrometer (6) and is analyzed, and a leak rate response signal is obtained.

Description

High-speed sniffer leakage detecting device and detecting method for large transformer sealing component

Technical field

The invention relates to a leak detection technology, in particular to a high-speed sniffer leak detection device and a detection method for a large transformer sealing component.

Background technique

Helium mass spectrometry leak detection is currently the most used and sensitive method of leak detection. This method can usually be divided into evacuation method and pressurization method. The evacuation method is to connect the detected component or the suspected leaked part to the leak detection valve. Using the leak detector's pumping system or specially designed pumping system to evacuate the inner cavity of the detected component, and then apply the helium gas at the outer weld of the detected component by spraying or squeezing, usually at an atmospheric pressure. Under the pressure difference, helium gas enters the inner cavity of the detected component through the leak hole and is sent to the leak detector, and helium gas is used as an output indication. The pressurization method, also known as the sniffer leak detection method, is to fill the inside of the object to be tested with a specified pressure of helium, using a special sniffer, such as a restrictive needle valve, a hole film or a capillary tube outside the object to be measured. To explore, if there is a leak in the measured object, the helium gas will escape outward through the leak hole. When the sniffer is facing the leak hole position, the helium gas is sucked into the leak detector together with the surrounding air to produce an output. Instructed to achieve the purpose of leak detection, where the sniffer is also referred to as a sniffer-sensitive probe, and the probe is connected to the leak detector through a catheter. The probe is passed through a needle valve structure or a slender capillary with a controllable flow rate. The instrument is connected, or the vacuum system of the leak detector is isolated from the outside atmosphere by a membrane that has a strong osmosis effect on the leaking gas, such as a quartz membrane, and at the same time, the leaking gas in the external atmosphere is sucked through the vacuum system. In the leak detector, the leak detector output indication changes.

The sniffer leak detection method can be understood as a process of detecting a leak by detecting a helium concentration change with a spatial position to determine a high helium concentration region, and is a space leak detection method. The sensitivity of the sniffer leak detection is related to the content of the sputum background in the air, the distance of the sniffer from the leak hole, the time the sniffer stays in the leak hole, that is, the moving speed and the response time of the sniffer to the leak signal.

Standard sniffer guns are divided into capillary type, membrane type, and needle type. However, with the rapid development of large thermal power plants, nuclear power plants, rockets, aircraft, and metallurgical industries, more and more special sealed containers are used in large transformers. The standard 2-5m sniffer can not meet the requirements of use. If the capillary type is lengthened and needs to be slender to maintain the pressure difference of at least four orders of magnitude inside and outside the sniffer, it will inevitably cause excessive flow resistance and reflect time. Too long, the time of elimination is very long, the sensitivity is extremely low, and the needle-type sniffer faces these special sealed containers, and the sealing, adjustability, repeatability and overall service life of the structure itself are questioned and challenged. At present, the most common type of film, if the length of the sniffer is lengthened, the detection time will be lengthened even if it does not affect the penetration of the quartz film into the helium gas.

Summary of the invention

The object of the present invention is to provide a high-speed sniffer leak detecting device for a large transformer sealing component, comprising: a long pipeline sniffer, a sampling pipe, a filter, a high-power suction pump, a helium separator, and a helium mass spectrometer, wherein The air carrier gas enters from the probe of the long pipeline sniffer, passes through the first branch of the sampling pipeline, is extracted by the high-power suction pump, and the helium gas leaking from the leak hole of the detected large transformer sealing component enters the long pipeline sniffer After the probe, along with the high-speed air carrier gas provided by the high-power suction pump, passing through the second branch of the sampling pipe, passing through the helium separator into the mass spectrometer of the helium mass spectrometer for analysis, and finally giving a response leak rate signal.

Preferably, the length of the long line sniffer is greater than 10 m.

Preferably, the helium separator is a fast permeable membrane that maintains a vacuum throughout the system under the action of the high velocity air carrier gas while performing rapid infiltration of helium.

Preferably, the helium mass spectrometer comprises a mass spectrometer chamber, a receiver and a signal conversion unit.

Preferably, the helium separator separates small ruthenium molecules from oxygen molecules in the air and larger helium molecules, and small ruthenium molecules are ionized after entering the mass spectrometer chamber, and thereafter are received and converted by the receiving chamber. It is converted into an electrical signal within the signal conversion unit.

Preferably, the transmission speed of the high-speed air carrier gas in the sampling conduit is determined by the conductance of the sampling conduit and the pumping speed of the high-power suction pump.

Preferably, the conductance of the sampling conduit is calculated by:

U = πd ⁴ Pa / 128ηL, where d is the diameter of the sampling pipe, the unit is m; L is the length of the pipe, the unit is m; η is the gas viscosity coefficient, the unit is NS / m ² , Pa is the average pressure in the pipe , Pa = (P1 + P0 + P2) / 3, P1, P2 are the gas pressure at both ends of the sampling pipe, and P0 is the gas pressure at the center of the sampling pipe, and the unit is Pa.

A high-speed sniffer leak detection method for a large transformer sealing component, comprising the following steps:

(1) Turn on the helium mass spectrometer leak detector and complete the calibration of the instrument;

(2) Form a certain collection bag with industrial tape at the possible leakage or standard leak of the large transformer sealing component, and set the volume of the collection bag to V. The volume is always the same, and the pressure inside the bag is collected. Is 1 standard atmospheric pressure, which is Patm;

(3) The helium mass spectrometer leak detector operates in the leak detection state for more than 1h;

(4) Restore the helium mass spectrometer leak detector to the standby state, and connect the long pipeline sniffer at the leak detection port;

(5) Press the start button, the helium mass spectrometer leak detector starts to detect the leak, and record the background value BV of the mass spectrometer at this time;

(6) Press the zero adjustment button of the helium mass spectrometer leak detector;

(7) Adjust the leakage rate of the possible leakage of the standard leak-proof sealing element to three different values respectively; align the sniffer to the normal leak or the possible leak of the sealing element, and detect the signal of the 氦 mass spectrometer response at this time. Value SV, response time T;

(8) If the display value of the helium mass spectrometer changes, it is possible to judge the leakage of the sealing element or the vicinity of the standard leak.

Preferably, the method further comprises the steps of: (9) removing the nozzle in the long line sniffer from the possible leak detected in the step (8), returning the signal to the original state, waiting for 2-5 seconds, and then approaching the nozzle again. In a suspicious place, repeat this operation multiple times to accurately determine the leak point.

Preferably, the long line squirt gun is 1-3 mm from the sealing element of the large transformer.

Preferably, the three different values of the step (7) are: 5 × 10 ^-7 Pa.m ³ , 5 × 10 ^-6 Pa.m ³ and 5 × 10 ^-5 Pa.m ³ .

The above as well as other objects, advantages and features of the present invention will become apparent to those skilled in the <

DRAWINGS

Some specific embodiments of the present invention are described in detail below by way of example, and not limitation. The same reference numbers in the drawings identify the same or similar parts. Those skilled in the art should understand that the drawings are not necessarily drawn to scale. The objects and features of the present invention will become more apparent in consideration of the following description in conjunction with the accompanying drawings.

1 is a schematic structural view of a high speed sniffer according to an embodiment of the present invention;

2 is a flow chart of a high speed sniffer leak detection method for a large transformer sealing element in accordance with an embodiment of the present invention.

detailed description

Referring to Figure 1, a high-speed sniffer leak detecting device for a large transformer sealing element, comprising: a high-speed squirt 1, a sampling pipe 2, a filter 3, a high-power suction pump 4, a krypton separator 5, and a helium mass spectrometer 6. The air carrier gas enters from the probe of the high speed sniffer 1, passes through the first branch 2-1 of the sampling pipe 2, is extracted by the high power suction pump 4, and leaks from the leak hole of the large transformer sealing element to be detected. After the helium enters the probe of the high-speed squirt 1, the high-speed air carrier gas supplied by the high-power sump pump 4 passes through the second branch 2-2 of the sampling pipe 2, passes through the 氦 separator 5, and enters the helium mass spectrometer. Mass spectrometry chamber of 6 (not shown) Analyze internally and finally give a response to the leak rate signal. The high speed squirt 1 has a length of 20 m. The helium separator 5 is a fast permeable membrane that maintains a vacuum throughout the system under the action of a high velocity air carrier gas while simultaneously performing rapid infiltration of helium. The helium mass spectrometer includes a mass spectrometer chamber, a receiver, and a signal conversion unit (not shown in detail in the drawings). The helium separator separates small helium molecules from oxygen molecules in the air and larger helium molecules. The small helium molecules are ionized after entering the mass spectrometer chamber, and then received and converted by the receiving chamber and converted into electricity in the signal conversion unit. signal.

During the test, the transmission speed of the high-speed air carrier gas in the sampling pipe is determined by the conductance of the sampling pipe and the pumping speed of the high-power suction pump. The conductance of the sampling pipe is calculated by:

U=πd ⁴ Pa/128ηL (1), where

d is the diameter of the sampling pipe, the unit is m; L is the length of the pipe, the unit is m; η is the gas viscosity coefficient, the unit is NS/m ² , Pa is the average pressure in the pipe, Pa=(P1+P0+P2 ) / 3, P1, P2 are the gas pressures at both ends of the sampling pipe, and P0 is the gas pressure at the center of the sampling pipe, and the unit is Pa.

Referring to Figure 2, there is shown a flow chart of the steps of a high speed sniffer leak detection method for a large transformer sealing element, namely:

(4) Restore the helium mass spectrometer leak detector to the standby state, and connect the high speed sniffer at the leak detection port;

(7) Adjusting the leakage rate of possible leaks of the standard leak ^- proof sealing element to 5×10 ^-7 Pa.m ³ , 5×10 ^-6 Pa.m ³ and 5×10 ^-5 Pa.m ^{3 , respectively} ; Align the sniffer with a standardized leak or a possible leak of the sealing element, and detect the signal value SV of the 氦 mass spectrometer response at this time, the response time T;

If you need to accurately locate the location of the leak, you will usually do the following: (9) Move the nozzle in the high-speed sniffer away from the possible leak detected in step (8), return the signal to its original state, wait 2-5 seconds. After the clock, close the nozzle to the suspicious place again, repeat the operation several times, and accurately determine the leak point.

The helium gas leaking from the leak hole will spread rapidly in the air. The farther the distance from the leak hole is, the lower the concentration of helium gas is, the closer the suction gun is to the leak hole, and the closer the leak rate is to the maximum value of 100%, the sniffer is away. The farther the leak is, the lower the sensitivity of the leak detection is. The distance between the sniffer and the surface of the test element is too close, and the sniffer is easily blocked by the dirt on the surface of the test piece. Usually, the distance is set to 1-3 mm.

The high-speed sniffer and the ordinary sniffer are respectively connected to the leak detection port, and the leak detector works in a vacuum mode, detects the background value of the sniffer, connects the standard leak hole to the sniffer port, and detects the signal value of the leak detector response. Record the experimental data. When the same sniffer is detected on the same 氦 mass spectrometer leak detector, the shunt ratio is a fixed value and will not change with the size of the detection signal. In the actual sniffer detection, the helium leaking from the leak point cannot be Completely guaranteed to enter the sniffer, there is a gap between the sniffer probe and the leak point, so that the helium leaking from the leak point will be diluted by the air, the concentration of helium will be reduced, and the ordinary sniffer will generate a 10 times shunt when detecting the signal. The high-speed sniffer produces 2000 times of splitting. This is because the high-speed sniffer has a suction pump inside. Most of the helium that enters the high-speed sniffer is pumped away by the suction pump. Only a small amount of helium enters the helium mass spectrometer and is detected. . Compared with the common sniffer and high-speed sniffer, the response time is 2s and 0.5s respectively. The high-speed sniffer increases the suction pumping and increases the speed of the airflow, thus reducing the response time and thus increasing the magnitude of the detection leak rate.

The present invention has been described with reference to the specific illustrative embodiments, and is not limited by the scope of the appended claims. It will be appreciated by those skilled in the art that the embodiments of the invention can be modified and modified without departing from the scope and spirit of the invention.

Claims

A high-speed sniffer leak detecting device for a large transformer sealing component, comprising: a high-speed sniffer (1), a sampling pipe (2), a filter (3), a high-power suction pump (4), and a sputum separation And (5), wherein the air carrier gas enters from the probe of the high speed sniffer (1), passes through the first branch (2-1) of the sampling pipe (2), and is sucked by high power. The pump (4) is withdrawn, and the helium gas leaking from the leak hole of the detected large transformer sealing element enters the probe of the high-speed sniffer (1), and with the high-speed air carrier gas supplied by the high-power suction pump (4), Passing through the second branch (2-2) of the sampling conduit (2), passing through the helium separator (5) into the mass spectrometer chamber of the helium mass spectrometer (6) for analysis, and finally giving a response leak rate signal.
A high speed sniffer leak detecting device for a large transformer sealing member according to claim 1, wherein said high speed sniffer (1) has a length greater than 10 m.
A high-speed sniffer leak detecting device for a large transformer sealing member according to claim 1, wherein said 氦 separator (5) is a rapid permeable membrane that maintains a vacuum throughout the system under the action of said high-speed air carrier gas, At the same time, rapid penetration of helium is carried out.
A high speed sniffer leak detecting apparatus for a large transformer sealing element according to claim 1, said helium mass spectrometer (6) comprising a mass spectrometer chamber, a receiver, and a signal conversion unit.
A high-speed sniffer leak detecting device for a large transformer sealing member according to claim 1, wherein said ruthenium separator (5) separates small ruthenium molecules from oxygen molecules in the air and larger helium molecules, and small The ruthenium molecules are ionized after entering the mass spectrometer chamber, and thereafter are received and converted by the receiving chamber and converted into electrical signals within the signal conversion unit.
A high speed sniffer leak detecting device for a large transformer sealing member according to claim 1, wherein a velocity of said high velocity air carrier gas in said sampling conduit is guided by said sample conduit (2) and said The pumping speed of the high-power suction pump is determined.
A high speed sniffer leak detecting device for a large transformer sealing member according to claim 6, wherein the conductance of said sampling conduit (2) is calculated by:

U = πd 4 Pa / 128ηL, where d is the diameter of the sampling pipe, the unit is m; L is the length of the pipe, the unit is m; η is the gas viscosity coefficient, the unit is NS / m 2 , Pa is the average pressure in the pipe , Pa = (P1 + P0 + P2) / 3, P1, P2 are the gas pressure at both ends of the sampling pipe, and P0 is the gas pressure at the center of the sampling pipe, and the unit is Pa.
A high-speed sniffer leak detection method for a large transformer sealing component, comprising the following steps:

(1) Turn on the helium mass spectrometer leak detector and complete the calibration of the instrument;

(2) Form a certain collection bag with industrial tape at the possible leakage or standard leak of the large transformer sealing component, and set the volume of the collection bag to V. The volume is always the same, and the pressure inside the bag is collected. Is 1 standard atmospheric pressure, which is Patm;

(3) The helium mass spectrometer leak detector operates in the leak detection state for more than 1h;

(4) Restore the helium mass spectrometer leak detector to the standby state, and connect the high speed sniffer at the leak detection port;

(5) Press the start button, the helium mass spectrometer leak detector starts to detect the leak, and record the background value BV of the mass spectrometer at this time;

(6) Press the zero adjustment button of the helium mass spectrometer leak detector;

(7) Adjust the leakage rate of the possible leakage of the standard leak-proof sealing element to three values, respectively align the sniffer with the normal leak or the possible leakage of the sealing element, and detect the signal value of the 氦 mass spectrometer response at this time. SV, response time T;

(8) If the display value of the helium mass spectrometer changes, it is possible to judge the leakage of the sealing element or the vicinity of the standard leak.
A high speed sniffer leak detecting method for a large transformer sealing member according to claim 8, further comprising the steps of: (9) removing the suction nozzle in the high speed sniffer from the possible leak detected in the step (8), and recovering the signal In the original state, wait 2-5 seconds, then close the nozzle to the suspicious place again, repeat the operation several times, and accurately determine the leak point.
A high-speed sniffer leak detecting method for a large-sized transformer sealing member according to claim 8, wherein said leakage rate of said step (7) is adjusted to three values of 5 × 10 -7 Pa.m 3 , respectively. 5 × 10 -6 Pa.m 3 and 5 × 10 -5 Pa.m 3 .