CN214621611U - On-line analysis integrated cabinet for natural gas trace leakage detection - Google Patents
On-line analysis integrated cabinet for natural gas trace leakage detection Download PDFInfo
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Abstract
The utility model relates to an integrated rack of online analysis of natural gas trace leak testing, it includes: the device comprises a cabinet body, a control unit, a sampling unit, an industrial computer, an online analyzer combination unit, a mark gas generation unit, a mark gas interface and a sample gas interface, wherein the mark gas interface and the sample gas interface are arranged on the side part of the cabinet body; the industrial computer is provided with a touch screen and is used for realizing the functions of parameter setting, system control and analysis result display; the control unit is connected with the sampling unit, the online analyzer combination unit and the marker gas generation unit; the sampling unit is communicated with one end of the pipeline to be detected through a sample gas interface and is used for extracting sample gas in the pipeline to be detected; the online analyzer combination unit is used for detecting the sample gas conveyed by the sampling unit and sending a detection result to the control unit; the mark gas generating unit is communicated with the other end of the pipeline to be detected through a mark gas interface. The utility model discloses can the wide application in defeated natural gas of pipe reveals the detection technology field.
Description
Technical Field
The utility model belongs to the technical field of defeated natural gas leak testing of pipe, concretely relates to integrated rack of online analysis based on natural gas trace leak testing that a plurality of different gaseous test probe combinations formed, the on-line monitoring who mainly is applicable to long-distance natural gas pipeline trace and leaks.
Background
The natural gas long-distance pipeline leakage accident has serious consequences and large influence range, and is the key point of safety production attention. Because natural gas pipelines are usually buried and laid, the space span is large, and how to timely and effectively find natural gas leakage is always a hotspot and a difficulty of research in the industry.
The existing leakage detection technology, such as infrasonic wave detection technology, vibration optical fiber detection technology and the like, converts pipeline vibration after gas leakage into sound and optical signals for detection, and generally the leakage is obvious when the detection is carried out, and the detection capability for tiny leakage generated by tiny cracks and the like is unavailable, so that the gas leakage cannot be detected at an extremely early stage.
In recent years, a leak detection technique based on a detection tube has also appeared. The technology is characterized in that a detection pipe made of special materials is laid in the same ditch of a natural gas pipeline to collect natural gas in the environment, the natural gas collected in a complementary mode is conveyed to a gas detector in a positive pressure or negative pressure driving mode to be analyzed, the natural gas leaked in a trace amount can be detected, and accurate positioning is carried out. However, in the detection technology, a set of on-line analysis device and a set of marker gas generation device are usually arranged at two ends of the detection tube respectively, and the devices are complex and limited by the space of a separate transportation station or a valve chamber when in application. Moreover, due to the limited capacity of the driving power source, the coverage distance of a single set of devices is typically within 40 km. Meanwhile, the currently adopted equal mass positioning algorithm assumes that the gas in the detection tube is uniform in density, and the water content in the air is not uniform in distribution, which may cause certain influence on the positioning algorithm and generate positioning errors. In addition, gases such as methane exist in the nature, and the gases may permeate into the detection pipe to be extracted and analyzed, so that false alarm is easily caused, and interference is generated on natural gas leakage detection.
Disclosure of Invention
To the problem, the utility model aims at providing an integrated rack of online analysis of natural gas trace leak testing can leak the natural gas trace of long-distance pipeline and carry out effective on-line measuring.
In order to achieve the purpose, the utility model adopts the following technical proposal: an integrated rack of on-line analysis of natural gas trace leakage detection, it includes: the device comprises a cabinet body, a control unit, a sampling unit, an industrial computer, an online analyzer combination unit, a mark gas generation unit, a mark gas interface and a sample gas interface, wherein the mark gas interface and the sample gas interface are arranged on the side part of the cabinet body; the industrial computer is provided with a touch screen and is used for realizing the functions of parameter setting, system control and analysis result display; the control unit is connected with the sampling unit, the online analyzer combination unit and the marker gas generation unit; the sampling unit is communicated with one end of the pipeline to be detected through the sample gas interface, and is used for extracting the sample gas in the pipeline to be detected and conveying the sample gas to the online analyzer combination unit; the online analyzer combination unit is used for detecting the sample gas conveyed by the sampling unit and sending a detection result to the control unit; the mark gas generating unit is communicated with the other end of the pipeline to be detected through the mark gas interface and is used for conveying mark gas into the pipeline to be detected.
Further, the sampling unit comprises a first electromagnetic valve group, a first mass flow controller and a sampling pump; the first electromagnetic valve group comprises two connecting ports, the two connecting ports are respectively connected with a first pipeline to be detected and/or a second pipeline to be detected through the sample gas interface, the output end of the first electromagnetic valve group is connected with the input end of the sampling pump, and the output end of the sampling pump is connected with the first mass flow controller; the electromagnetic valve group, the sampling pump and the first mass flow controller are all connected with the control unit.
Further, the sampling pump adopts a negative pressure type constant flow sampling pump.
Further, the first mass flow controller adopts an integrated mass flow meter and an electromagnetic control valve.
Further, the online analyzer combination unit comprises a methane gas analyzer, a C3+ gas detector, a hydrogen detector and a water dew point detector; the input end of the methane gas analyzer is connected with the output end of the sampling unit, the output end of the methane gas analyzer is sequentially connected with the C3+ gas detector, the hydrogen detector and the water dew point detector, and the output end of the water dew point detector is directly discharged to the atmosphere through a pipeline; the methane gas analyzer, the C3+ gas detector, the hydrogen detector and the water dew point detector are all connected with the control unit, and are respectively used for detecting the contents of methane, C2, C3, hydrogen and moisture in the gas in the pipeline to be detected and sending the contents to the control unit.
Further, the methane gas analyzer adopts a double-channel laser methane gas analyzer.
Further, the hydrogen detection range of the hydrogen detector is 0-500 ppm.
Further, the mark gas generation unit comprises a second mass flow controller, a second electromagnetic valve group, a first filtering unit, a second filtering unit, an air compressor and a C3+ standard gas cylinder; the second electromagnetic valve group comprises two input ends and two output ends; the first input end of the second mass flow controller is connected with the output end of the second mass flow controller, the input end of the second mass flow controller is connected with the air compressor arranged outside the cabinet through the first filtering unit to form a purging branch, and the second mass flow controller is connected with the control unit; the second input end is connected with the C3+ standard gas bottle arranged outside the cabinet through the second filtering unit to form a mark gas branch; and two output ends of the second electromagnetic valve group are connected with the pipeline to be detected.
Furthermore, the second electromagnetic valve group comprises a first three-way electromagnetic valve, a second three-way electromagnetic valve and a third three-way electromagnetic valve, wherein one through port of the first three-way electromagnetic valve and one through port of the second three-way electromagnetic valve are connected in parallel and then are used as a first input end to be connected with the mark gas branch; bypass ports of the first three-way electromagnetic valve and the second three-way electromagnetic valve are connected in parallel and then serve as a second input end to be connected with the mark gas branch; the other through ports of the first three-way electromagnetic valve and the second three-way electromagnetic valve are respectively connected with one through port of the third three-way electromagnetic valve and one through port of the fourth three-way electromagnetic valve; bypass ports of the third three-way electromagnetic valve and the fourth three-way electromagnetic valve are connected in parallel and then are connected with the atmosphere; and the other through ports of the third three-way electromagnetic valve and the fourth three-way electromagnetic valve are used as two mark gas interfaces of the cabinet and are respectively connected with a pipeline to be detected.
Further, the first filtering unit adopts a molecular sieve air filtering dryer.
The utility model discloses owing to take above technical scheme, it has following advantage:
(1) the integrated online analysis cabinet integrates the sampling unit (sampling pump, sampling pipeline, online analyzer, emptying pipeline, etc.), the mark gas generating unit (electromagnetic valve, mark gas cylinder interface, etc.), the PLC control system and the industrial control computer of the whole system in a set of standard cabinet, realizes the integration, miniaturization and automation of the device, saves the occupied area and can be used in a plug-and-play manner.
(2) The integrated cabinet and the detection tube can be connected in a loop mode or in an open circuit mode. The loop connection can arrange the system in a single station, avoids the receiving and sending devices from being respectively arranged in an upstream station and a downstream station, and avoids the problems of arranging an independent control system and communication between the upstream station and the downstream station. The open circuit connection can realize the series connection of a plurality of cabinets, expand the detection range and is suitable for long-distance natural gas pipelines of hundreds and thousands of kilometers.
(3) The combination of a plurality of gas on-line analyzers is adopted. The utility model discloses the laser formula analysis appearance that adopts is binary channels gas analysis appearance, can detect methane and ethane concentration simultaneously. Because natural gas generally contains ethane components, and the ethane content in natural interference gas such as methane is zero, the detection of ethane concentration can be used as a supplementary criterion for natural gas detection. Besides, the utility model discloses be equipped with the hydrogen detector, can detect out the hydrogen concentration that contains in the gas. The biogas usually contains a certain amount of hydrogen, and if the hydrogen is detected at the same time of detecting the methane, the hydrogen can be used as the criterion of the biogas, thereby reducing false alarms.
(4) A laser methane gas analyzer is adopted. In principle, the laser analyzer has the advantages of higher sensitivity and high response speed compared with electrochemical and infrared analyzers, and can detect methane gas with lower concentration.
(5) The water content analyzer can be used for detecting the water content in the sampled gas on line and correcting the water content in the air to cause uneven density distribution and cause errors in system positioning calculation.
Therefore, the utility model discloses can wide application in defeated natural gas of pipe leakage detection technical field.
Drawings
Fig. 1(a) and fig. 1(b) are schematic structural diagrams of an online analysis integrated cabinet for detecting trace leakage of natural gas according to the present invention, wherein fig. 1(a) is a schematic structural diagram of a back side of the online analysis integrated cabinet, and fig. 1(b) is a schematic structural diagram of a front side of the online analysis integrated cabinet;
fig. 2 is a pipeline diagram of the on-line analysis integrated cabinet for detecting trace leakage of natural gas according to the present invention;
FIG. 3 is a loop connection method of an online analysis integrated cabinet for detecting trace leakage of natural gas according to the present invention;
fig. 4 is an open circuit connection method of an on-line analysis integrated cabinet for detecting trace leakage of natural gas according to the present invention;
the respective symbols in the figure are as follows:
1. a control unit; 2. a sampling unit; 21. a first solenoid valve group; 22. a first mass flow controller; 23. a sampling pump; 3. an industrial computer; 31. a touch screen; 32. an upper computer; 4. an online analyzer combination unit; 41. a methane gas analyzer; 42. c3+ gas detector; 43. a hydrogen detector; 44. a water dew point detector; 5. a marker gas generation unit; 51. a second mass flow controller; 52. a second solenoid valve group; 53. a first filter unit; 54. a second filter unit; 55. an air compressor; 56. c3+ standard gas cylinder; 6. a marker gas interface; 7. a sample gas interface; 8. a first pipeline to be detected; 9. and a second pipeline to be detected.
Detailed Description
The present invention will be described in detail with reference to the accompanying drawings and examples.
The utility model provides an integrated rack of online analysis of natural gas trace leak testing to solve trace natural gas leak on-line measuring and analysis problem. The utility model solves the integration, miniaturization and automation of the on-line analysis system; the problem that a single system is limited in monitoring distance and cannot meet long-distance pipeline leakage monitoring is solved; the sensitivity and the response speed of the on-line analysis of the natural gas are improved through the combination of a plurality of gas analyzers, and the influence of interference gases such as methane and the like on the detection of the natural gas is solved; and correcting the positioning error caused by the water content in the air through a moisture analyzer.
As shown in fig. 1(a) and fig. 1(b), the utility model provides an integrated rack of online analysis of natural gas micro leakage detection, it includes: the device comprises a control unit 1 arranged on the upper portion of the back of the cabinet, a sampling unit 2 arranged on the lower portion of the back of the cabinet, an industrial computer 3 arranged on the upper portion of the front of the cabinet, an online analyzer combination unit 4 arranged in the middle of the front of the cabinet, a mark gas generation unit 5 arranged on the lower portion of the front of the cabinet, and a mark gas interface 6 and a sample gas interface 7 arranged on the side portion of the cabinet. The industrial computer 3 is provided with a touch screen 31 for realizing the functions of parameter setting, system control, analysis result display and the like, and sending the received parameter setting and system control signals to the control unit 1; the control unit 1 is used for controlling the sampling unit 2, the on-line analyzer combination unit 4 and the mark gas generation unit 5 according to the received parameter setting and system control signals; the sampling unit 2 is communicated with one end of the pipeline to be detected through a sample gas interface 7, and is used for extracting the sample gas in the pipeline to be detected and conveying the sample gas to the online analyzer combination unit 4; the online analyzer combination unit 4 is used for detecting the sample gas delivered by the sampling unit 2 and sending the detection result to the control unit 1; the mark gas generating unit 5 is communicated with the other end of the pipeline to be detected through a mark gas interface 6 and is used for conveying mark gas into the pipeline to be detected; the control unit 1 sends all received detection data to the industrial computer 3, the industrial computer 3 realizes detection and positioning analysis of trace natural gas leakage according to detection results, performs early warning according to analysis results, and simultaneously stores all detection data.
Further, the control unit 1 adopts a PLC controller, and a data acquisition unit and an automatic control unit are arranged in the PLC controller. The data acquisition unit is used for receiving all detection signals sent by the online analyzer combination unit; the automatic control unit is used for setting signals according to received parameters such as sampling flow and time interval, and realizes automatic control of the whole analysis process, and comprises the following steps: purging a pipeline, standing (permeation and collection of a detection tube), extracting a sample, carrying out online analysis, emptying and the like.
Further, the industrial computer 3 is provided with an upper computer 32, and the upper computer 22 is provided with a database, a pre-loaded carrier gas real-time analysis system and a leakage positioning system. The preassembly carrier gas real-time analysis system and the leakage positioning system are respectively used for completing system leakage alarm and leakage point positioning functions according to monitoring data sent by the control unit, and the database is used for storing all detection data sent by the control unit and leakage alarm and leakage point fixed-point analysis results obtained by the preassembly carrier gas real-time analysis system and the leakage positioning system.
Further, as shown in fig. 2, the sampling unit 2 includes a first solenoid valve group 21, a first mass flow controller 22, and a sampling pump 23. The first solenoid valve group 21 includes two connection ports, the two connection ports are connected to the first pipeline 8 to be detected and/or the second pipeline 9 to be detected through the sample gas interface 7, the output end of the first solenoid valve group 21 is connected to the input end of the sampling pump 23, and the output end of the sampling pump 23 is connected to the first mass flow controller 22. The electromagnetic valve group 21, the sampling pump 23 and the first mass flow controller 22 are all connected with the control unit 1, and the electromagnetic valve group 21 is used for switching pipelines according to control signals sent by the control unit 1, including selectively pumping gas in the first pipeline 8 to be detected or the second pipeline 9 to be detected for analysis, or switching purging of the first pipeline 8 to be detected and the second pipeline 9 to be detected; the sampling pump 23 is used for extracting the sample gas in the pipeline 8 or 9 to be detected according to the control signal sent by the control unit 1; the output end of the first mass flow controller 22 is connected to the online analyzer combination unit 4 as the output end of the sampling unit 2, and is used for performing flow measurement and control on the gas in the pipeline 8 or 9 to be detected according to the control signal sent by the control unit 1, so that the gas in the pipeline 8 or 9 to be detected is extracted according to a uniform and stable flow rate and is output to the online gas analyzer combination unit 4 for analysis.
Preferably, the sampling pump 23 is a negative pressure type constant flow sampling pump.
Preferably, the first mass flow controller 22 employs an integrated mass flow meter and solenoid controlled valve.
Further, the online analyzer combination unit 4 includes a methane gas analyzer 41, a C3+ gas detector 42, a hydrogen gas detector 43, and a water dew point detector 44. Wherein, the input end of the methane gas analyzer 41 is connected with the output end of the sampling unit, i.e. the output end of the mass flow controller 22, the output end of the methane gas analyzer 41 is sequentially connected with the C3+ gas detector 42, the hydrogen detector 43 and the water dew point detector 44, and the output end of the water dew point detector 44 is directly discharged to the atmosphere through a pipeline. The methane gas analyzer 41, the C3+ gas detector 42, the hydrogen gas detector 43 and the water dew point detector 44 are all connected to the control unit 1, and are respectively used for detecting the contents of methane, C2, C3, hydrogen and moisture in the gas in the pipeline 8 or 9 to be detected, and sending the contents to the control unit 1.
Preferably, the methane gas analyzer 41 adopts a high-precision dual-channel laser methane gas analyzer, and compared with electrochemical analyzers and infrared analyzers, the laser methane gas analyzer has the advantages of higher sensitivity and high response speed; the two-channel detection allows simultaneous analysis of methane and ethane concentrations. The detection range of the methane concentration is 0-100ppm, and the detection range of the ethane concentration is 0-1000 ppm.
Preferably, the hydrogen detector 43 has a hydrogen detection range of 0-500 ppm.
Further, the marker gas generation unit 5 includes a second mass flow controller 51, a second solenoid valve group 52, a first filter unit 53, a second filter unit 54, and an air compressor 55 and a C3+ standard gas cylinder 56. The second electromagnetic valve group 52 comprises two input ends and two output ends, the first input end is connected with the output end of the second mass flow controller 51, the input end of the second mass flow controller 51 is connected with an air compressor 55 arranged outside the cabinet through a first filtering unit 53 to form a purging branch, the second mass flow controller 51 is connected with the control unit 1, and the flow measurement and control of the gas in the purging branch are carried out under the control of the control unit 1; the second input end is connected with a C3+ standard gas bottle 56 arranged outside the cabinet through a second filtering unit 54 to form a mark gas branch; two output ends of the second electromagnetic valve group 52 are respectively connected to the pipeline 8 to be detected and/or the pipeline 9 to be detected, and are used for switching the air path under the control of the control unit 1, so that the air or the mark gas provided by the purging branch or the mark gas branch is input into the pipeline 8 to be detected or the pipeline 9 to be detected.
Further, the second electromagnetic valve set 52 comprises four three-way electromagnetic valves 521-524, and one of the through ports of the three-way electromagnetic valve 521 and the three-way electromagnetic valve 522 is connected in parallel and then is used as a first input end to be connected with the mark gas branch; bypass ports of the three-way electromagnetic valve 521 and the three-way electromagnetic valve 522 are connected in parallel and then serve as a second input end to be connected with the sign gas branch; the other through ports of the three-way electromagnetic valve 521 and the three-way electromagnetic valve 522 are respectively connected with one through port of the three-way electromagnetic valve 523 and one through port of the three-way electromagnetic valve 524; bypass ports of the three-way electromagnetic valve 523 and the three-way electromagnetic valve 524 are connected in parallel and then are connected with the atmosphere; the other through ports of the three-way electromagnetic valve 523 and the three-way electromagnetic valve 524 are used as two label gas interfaces of the cabinet to be connected with the pipeline to be detected respectively.
Further, the first filtering unit 53 employs a molecular sieve air filtration dryer.
Based on the integrated rack of on-line analysis of above-mentioned natural gas trace leak testing, the utility model also provides a detection method of the integrated rack of on-line analysis of natural gas trace leak testing, including following step:
1) and connecting the pipeline to be detected with a mark gas interface 6 and a sample gas interface 7 of the on-line analysis integrated cabinet for detecting the trace leakage of the natural gas according to the detection requirement.
As shown in fig. 3, when the method is used for monitoring small-scale leakage of a station yard, a storage tank and the like, a ring detection mode is selected, and the specific connection method is as follows: and respectively connecting a sample gas interface 7 and a mark gas interface 6 on the side part of the integrated cabinet with two ends of a pipeline to be detected to form a detection passage. The other end of the sample gas interface 7 is connected to the sampling unit 2, and the sample gas is sampled by the sampling unit 2 and then is conveyed to the online analysis meter combination unit 4 to analyze the sample gas; the other end of the mark gas interface 6 is connected with the mark gas generating unit 5, and the mark gas generating unit 5 provides mark gas to the pipeline to be detected. At the beginning of each detection cycle, the control unit 1 controls the marker gas generation unit 5 to inject C3 gas with a certain concentration as a marker, and when the online analyzer combination unit 4 detects the peak value of the concentration of C3 gas, it is determined that one detection cycle is finished.
Preferably, because the first solenoid valve set 21 and the second solenoid valve set 52 in the integrated cabinet both have two connection ports, the integrated cabinet can be connected to two pipelines to be detected simultaneously, and automatic alternate detection is realized. At the beginning of each detection cycle, the control unit 1 controls the marker gas generation unit 5 to inject C3 gas with a certain concentration as a marker, and when the online analyzer combination unit 4 detects the peak value of the concentration of C3 gas, it is determined that one detection cycle is finished.
As shown in fig. 4, when a long natural gas pipeline of hundreds and thousands of kilometers needs to be detected, an open-circuit detection mode is selected, and at this time, a plurality of integrated cabinets are required to be connected in series, and the specific connection method is as follows: one end of a first section of pipeline to be detected is connected with a mark gas generating unit of a first cabinet through a mark gas interface, and the other end of the first section of pipeline to be detected is connected with a sampling unit of a second cabinet through a sample gas interface; one end of the second section of pipeline to be detected is connected with the mark gas generating unit of the second cabinet, the other end of the second section of pipeline to be detected is connected with the sampling unit of the third cabinet, and other sections of pipeline to be detected are sequentially connected by the same method to form a serial detection passage. And when the second cabinet detects that the concentration of the C3 gas reaches the peak value, the detection cycle is judged to be finished. As the monitoring distance of a single cabinet can reach 40km, the detection range can be expanded by connecting a plurality of cabinets in series in an open circuit detection mode.
2) And determining the working mode of the cabinet, and controlling the mark gas generation unit and the sampling unit through the control unit to convey the sample gas in the detection pipe to the online analyzer combination unit.
The working modes of the cabinet comprise a negative pressure extraction mode and a positive pressure conveying mode, and the sampling pump 23 is adopted as a power source to pump air in the negative pressure extraction mode; in the positive pressure conveyance mode, air is supplied using the air compressor 55 as a power source.
The negative pressure extraction mode is as follows:
the utility model discloses in regard as the characteristic gas that judges that the detection cycle ends with C3+ gas. When the detection cycle starts (the system records the detection start time), the second solenoid valve set 52 is controlled, that is, the solenoid valve 521 and the solenoid valve 523 are controlled to be switched on, and the sampling pump 23 is controlled to be started (at this time, the air compressor 55 does not work), so that the C3+ gas enters the pipeline 8 to be detected, and is extracted into the C3+ detector 42 in the cabinet along with the sample gas for detection. The system identifies the moment at which the C3+ gas concentration peak occurs from the data analysis and takes this moment as the end point of the detection cycle. For the line 9 to be tested, it is controlled in the same way by means of the solenoid valves 522 and 524.
The positive pressure delivery mode refers to:
and an air compressor 55 is used as a power source to replace the vacuum pump 23, and the gas in the pipeline to be detected is conveyed into the cabinet for detection. In this mode, before the start of the detection cycle, the air compressor 55 is first opened to purge, and after the purge is completed, the air compressor 55 is closed; when the detection cycle starts, the electromagnetic valve 521 and the electromagnetic valve 523 are controlled to be conducted, so that the pipeline 8 to be detected is communicated with the mark gas steel cylinder 56, and C3+ mark gas is injected into the cabinet; then, the air compressor 18 is controlled to work (at this time, the sampling pump does not work), so that the air in the air compressor 55 enters the pipeline 8 to be detected, and enters the online analyzer combination unit in the cabinet along with the sample gas to be detected, and the system identifies the moment when the C3+ gas concentration peak value appears according to data analysis and takes the moment as the end point of the detection cycle. For the line 3 to be tested, the control solenoid 522 and the solenoid 524 are controlled in the same way.
3) The online analyzer combination unit detects the sample gas conveyed by the sampling unit, the detection result is sent to the industrial computer through the control unit, the industrial computer detects and positions and analyzes the trace natural gas leakage based on the detection result, and early warning is carried out according to the analysis result.
Specifically, the method comprises the following steps:
3.1) the methane gas analyzer 41, the C3+ gas detector 42, the hydrogen gas detector 43 and the water dew point detector 44 in the on-line analyzer combination unit 4 respectively detect the methane and ethane concentration, the C3 gas concentration, the hydrogen gas concentration and the moisture content in the sample gas, and send the detection results to the control unit 1.
3.2) the control unit 1 sends all detection results to the industrial computer 3, the industrial computer 3 detects and performs positioning analysis on the trace natural gas leakage based on the detection results, and performs early warning according to the analysis results.
Specifically, the analysis method comprises the following steps:
firstly, judging whether the methane or the natural gas leaks in the detection pipe according to the hydrogen content detected by the hydrogen detector 43, and if the methane concentration is detected and a hydrogen concentration signal is detected, determining that the methane but not the natural gas leaks in the detection pipe; otherwise, it is considered a natural gas leak;
secondly, according to the moisture content detected by the water dew point detector 44, the error of the system positioning calculation caused by the uneven gas density distribution caused by the moisture content is corrected.
The principle of correcting and positioning by adopting a water dew point detector is as follows: the integrated analysis cabinet is provided with a mass flow controller which can control sample gas to be pumped into the online analysis meter combination unit for detection at constant mass flow. According to the monitored gas mass flow, the gas temperature and the gas pressure before monitoring, the gas flow is converted into the distance with the corresponding length, the position of the leakage point is further inversely calculated, and the position of the first derivative zero point of the leakage signal curve is solved to determine the leakage point.
However, in practical situations, the density of the air in the detection pipe is not uniformly distributed, and especially when the distance between the pipelines is long, the density is affected by the difference of the water content of the air at different positions. The utility model discloses in, adopt the water dew point detector to carry out synchronous on-line measuring to the water content in the sample gas, combine the temperature measurement value under this moment simultaneously, obtain sample gas density correction coefficient to fix a position and revise the leak source.
Specifically, since the molecular weight of air is 29 and the molecular weight of water is 18, the calculation formula of the density correction coefficient is as follows:
wherein h is the water content (volume ratio) in the air, and T is the temperature, and the unit is ℃.
Accordingly, the location of the leak should be multiplied by a correction factor:
C1＝1/C0
above-mentioned each embodiment only is used for explaining the utility model discloses, wherein structure, connected mode and the preparation technology etc. of each part all can change to some extent, all are in the utility model discloses equal transform and improvement of going on technical scheme's the basis all should not exclude outside the protection scope of the utility model.
Claims (10)
1. The utility model provides an integrated rack of online analysis of natural gas trace leak testing which characterized in that includes:
the device comprises a cabinet body, a control unit, a sampling unit, an industrial computer, an online analyzer combination unit, a mark gas generation unit, a mark gas interface and a sample gas interface, wherein the mark gas interface and the sample gas interface are arranged on the side part of the cabinet body;
the industrial computer is provided with a touch screen and is used for realizing the functions of parameter setting, system control and analysis result display;
the control unit is connected with the sampling unit, the online analyzer combination unit and the marker gas generation unit;
the sampling unit is communicated with one end of the pipeline to be detected through the sample gas interface, and is used for extracting the sample gas in the pipeline to be detected and conveying the sample gas to the online analyzer combination unit;
the online analyzer combination unit is used for detecting the sample gas conveyed by the sampling unit and sending a detection result to the control unit;
the mark gas generating unit is communicated with the other end of the pipeline to be detected through the mark gas interface and is used for conveying mark gas into the pipeline to be detected.
2. The integrated cabinet for on-line analysis and detection of trace leakage of natural gas as claimed in claim 1, wherein: the sampling unit comprises a first electromagnetic valve group, a first mass flow controller and a sampling pump;
the first electromagnetic valve group comprises two connecting ports, the two connecting ports are respectively connected with a first pipeline to be detected and/or a second pipeline to be detected through the sample gas interface, the output end of the first electromagnetic valve group is connected with the input end of the sampling pump, and the output end of the sampling pump is connected with the first mass flow controller;
the electromagnetic valve group, the sampling pump and the first mass flow controller are all connected with the control unit.
3. The integrated cabinet for on-line analysis and detection of trace leakage of natural gas as claimed in claim 2, wherein: the sampling pump adopts a negative pressure type constant flow sampling pump.
4. The integrated cabinet for on-line analysis and detection of trace leakage of natural gas as claimed in claim 2, wherein: the first mass flow controller adopts an integrated mass flow meter and an electromagnetic control valve.
5. The integrated cabinet for on-line analysis and detection of trace leakage of natural gas as claimed in claim 1, wherein: the online analyzer combination unit comprises a methane gas analyzer, a C3+ gas detector, a hydrogen detector and a water dew point detector;
the input end of the methane gas analyzer is connected with the output end of the sampling unit, the output end of the methane gas analyzer is sequentially connected with the C3+ gas detector, the hydrogen detector and the water dew point detector, and the output end of the water dew point detector is directly discharged to the atmosphere through a pipeline;
the methane gas analyzer, the C3+ gas detector, the hydrogen detector and the water dew point detector are all connected with the control unit, and are respectively used for detecting the contents of methane, C2, C3, hydrogen and moisture in the gas in the pipeline to be detected and sending the contents to the control unit.
6. The integrated cabinet for on-line analysis and detection of trace leakage of natural gas as claimed in claim 5, wherein: the methane gas analyzer adopts a double-channel laser methane gas analyzer.
7. The integrated cabinet for on-line analysis and detection of trace leakage of natural gas as claimed in claim 5, wherein: the hydrogen detection range of the hydrogen detector is 0-500 ppm.
8. The integrated cabinet for on-line analysis and detection of trace leakage of natural gas as claimed in claim 1, wherein: the mark gas generating unit comprises a second mass flow controller, a second electromagnetic valve group, a first filtering unit, a second filtering unit, an air compressor and a C3+ standard gas cylinder;
the second electromagnetic valve group comprises two input ends and two output ends;
the first input end of the second mass flow controller is connected with the output end of the second mass flow controller, the input end of the second mass flow controller is connected with the air compressor arranged outside the cabinet through the first filtering unit to form a purging branch, and the second mass flow controller is connected with the control unit;
the second input end is connected with the C3+ standard gas bottle arranged outside the cabinet through the second filtering unit to form a mark gas branch;
and two output ends of the second electromagnetic valve group are connected with the pipeline to be detected.
9. The integrated cabinet for on-line analysis and detection of trace leakage of natural gas as claimed in claim 8, wherein: the second electromagnetic valve group comprises a first three-way electromagnetic valve, a second three-way electromagnetic valve and a third three-way electromagnetic valve, wherein one through port of the first three-way electromagnetic valve and one through port of the second three-way electromagnetic valve are connected in parallel and then are used as a first input end to be connected with the mark gas branch; bypass ports of the first three-way electromagnetic valve and the second three-way electromagnetic valve are connected in parallel and then serve as a second input end to be connected with the mark gas branch; the other through ports of the first three-way electromagnetic valve and the second three-way electromagnetic valve are respectively connected with one through port of the third three-way electromagnetic valve and one through port of the fourth three-way electromagnetic valve; bypass ports of the third three-way electromagnetic valve and the fourth three-way electromagnetic valve are connected in parallel and then are connected with the atmosphere; and the other through ports of the third three-way electromagnetic valve and the fourth three-way electromagnetic valve are used as two mark gas interfaces of the cabinet and are respectively connected with a pipeline to be detected.
10. The integrated cabinet for on-line analysis and detection of trace leakage of natural gas as claimed in claim 8, wherein: the first filtering unit adopts a molecular sieve air filtering dryer.
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