CN113435727B - Method for acquiring gas diffusion range under single-point alarm of communication pipeline - Google Patents
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Abstract
A method for obtaining a gas diffusion range under single-point alarm of a communicating pipeline belongs to the technical field of gas safety monitoring, and solves the problem of how to design a method for obtaining the gas diffusion range under single-point alarm of the communicating pipeline, which is used for obtaining the farthest diffusion distance of gas in the communicating pipeline during single-point alarm; for the rain and sewage pipeline, the influence of water flow in the communicating pipeline on gas diffusion is considered, and the calculation is more accurate.
Description
Technical Field
The invention belongs to the technical field of gas safety monitoring, and relates to a method for acquiring a gas diffusion range under single-point alarm of a communicating pipeline.
Background
In recent years, frequent gas pipeline accidents in cities and towns cause great threats to the normal operation of cities and the safety of lives and properties of people, and the statistics shows that nearly 1000 gas explosion accidents occur in 2017 of China, so that huge economic losses are caused. In addition, various pipe networks in cities are distributed in the underground in an intricate manner, and the pipelines are inevitably crossed and adjacent. Once the gas leaks and spreads to adjacent rain sewage and other communication pipelines to be gathered, explosion can happen when meeting an ignition source, and the accidents have occurred in recent years, such as 200 deaths caused by an explosion event of Mexico melon Dala and Ha and 1470 injuries in 1992. By researching the gas diffusion speed and concentration change rule of the leaked combustible gas in the communication pipeline, the change rule of the combustible gas diffusion danger area in the communication pipeline along with time is analyzed, and the city manager can be helped to classify and manage the explosion risk of the communication pipeline in a targeted manner.
At present, most researches on gas leakage diffusion are focused on the aspects of atmospheric diffusion, soil diffusion and the like (related researches on atmospheric diffusion are mature, the soil diffusion cannot obtain accurate gas diffusion distance due to the influence of factors such as soil anisotropy, porosity and water content, but related documents mention that the maximum diffusion range is 12.5 meters), and few people research on the diffusion condition of gas leakage into adjacent underground spaces. The gas leaks and diffuses into an adjacent communicating pipeline such as a rainwater and sewage pipeline through soil, and further diffuses to a longer distance under the action of water flow in the pipeline, so that once an ignition source is exploded, the influence range is larger. Therefore, the diffusion rule of the gas leakage entering the communicating pipeline is explored, and people can better analyze the explosion effect of the gas pipeline leakage.
In the prior art, the chinese patent application "a method and a system for predicting and tracing the diffusion of combustible gas in a communication pipeline" published on 2021, 4, 16 days discloses a method and a system for calculating the diffusion distance of the combustible gas in the communication pipeline, which mainly aims at the condition of the diffusion distance of the combustible gas when at least two monitoring points (alarm of combustible gas monitoring equipment) are arranged on the communication pipeline, and does not consider the influence of water flow in the communication pipeline on the diffusion of the combustible gas, but in practical engineering application, because of the influences of cost, equipment monitoring effectiveness, complexity of field construction environment and the like, only one monitoring equipment can be arranged on one communication pipeline for alarm under many conditions, so that the diffusion rule of the combustible gas in the communication pipeline during single-point alarm needs to be researched, and the diffusion range of the concentration of the farthest diffusion distance of the combustible gas and the lower limit of 50% explosion (lel) under the condition is obtained.
Disclosure of Invention
The problem to be solved by the present invention is how to design a method for acquiring the gas diffusion range in a single-point alarm of a communication line, which is used for acquiring the farthest diffusion distance of gas in the communication line at the time of single-point alarm and the diffusion range of 50% LEL.
The invention solves the technical problems through the following technical scheme:
a method for acquiring a gas diffusion range under single-point alarm of a communicating pipeline is used for a scene when a single inspection well in the communicating pipeline for alarming by monitoring equipment is arranged in adjacent underground spaces around an urban gas pipeline, and the communicating pipeline comprises a power pipe ditch and a rainwater and sewage pipeline;
when the combustible gas diffuses in the electric power pipe trench, in the case of a single-point alarm, the diffusion distance of the combustible gas is calculated in terms of a concentration of 50% or more of the lower explosion limit (50% lel) of methane:
wherein x is 1 Is the diffusion distance of the combustible gas (50 LEL) upstream or downstream in the power pipe trench after t minutes with respect to the alarm point, q represents the rate of leakage of the combustible gas into the power pipe trench in m 3 B represents the section width of the power pipe ditch, and the unit is m; t is input time, min; when the formula is adopted for calculation, the input time is more than 1;
when combustible gas diffuses in the rainwater and sewage pipeline, because the flow of water in the rainwater and sewage pipeline has shearing force to the gas above the pipeline, the combustible gas is driven to flow downstream and accelerate the gas and stabilize the speed of the gas, and under the condition of single-point alarm, the diffusion range of the combustible gas is calculated according to the following mode:
the flow velocity of the rainwater and sewage pipeline under the constant flow condition is calculated according to the following formula:
wherein v is water Is the water flow speed, and the unit is m/s; d is the diameter of the pipeline, m; r is the hydraulic radius of the rain sewage pipeline, and the unit is m; i is hydraulic slope; n is a roughness coefficient; lambda is the pipeline fullness; theta is radian; d is the diameter of the rain sewage pipeline;
the flow velocity of combustible gas in the rain and sewage pipeline is 30 percent of that of sewage, so the gas diffusion velocity v gas Expressed as:
v gas ＝0.3v water
the diffusion range of the combustible gas in the storm sewage line is expressed as:
x 2 ＝v gas (60t)
wherein x is 2 The distance of diffusion of combustible gas in the rain sewage pipeline downstream relative to the alarm point after t minutes.
The technical scheme of the invention is combined with practical engineering application, and the influence of cost, equipment monitoring effectiveness, complexity of field construction environment and the like is considered, the diffusion rule of the fuel gas in a communication pipeline during single-point alarm is researched, the farthest diffusion distance of the fuel gas in the state is obtained, and auxiliary support is provided for a city manager to explore the influence result after the fuel gas is leaked; for the rain and sewage pipeline, the influence of water flow in the communicating pipeline on gas diffusion is considered, and the calculation is more accurate.
As a further improvement of the technical scheme of the invention, when combustible gas diffuses in the electric power pipe ditch, when the pipeline where the alarm point A is located has other monitoring equipment B, when x is 1 Is greater than the distance L between the alarm point A and other monitoring equipment B AB And the other monitoring equipment B does not give an alarm, the diffusion of the combustible gas is stopped at the other monitoring equipment B, and the diffusion ranges of the upstream or downstream of the alarm point A are L AB 。
As a further improvement of the technical solution of the present invention, when the requirement of the calculation accuracy is high, the diffusion speed of the combustible gas in the storm sewage pipeline can be further expressed by the following way:
v gas ＝0.397(Wv water /P air ) 0.7234
P air ＝πD-0.5Dθ
wherein W is the water surface width, P air The circumference of the air layer in the tube.
As a further improvement of the technical scheme of the invention, when combustible gas diffuses in the rainwater and sewage pipeline, when other monitoring equipment B exists in the range of the downstream threshold value of the pipeline where the alarm point A is located, when x is 2 Is greater than the distance L between the alarm point A and other monitoring equipment B AB And the other monitoring equipment B does not give an alarm, the diffusion of the combustible gas is stopped at the other monitoring equipment B, and the diffusion ranges of the upstream and downstream of the alarm point A are L at the moment AB 。
As a further improvement of the technical scheme of the invention, when combustible gas diffuses in the rainwater and sewage pipeline, when other monitoring equipment B exists in the upstream threshold range of the pipeline where the alarm point A is located, and when x is the threshold range of the pipeline where the alarm point A is located 2 Is greater than the distance L between the alarm point A and other monitoring equipment B AB And the other monitoring equipment B does not give an alarm, the diffusion of the upstream combustible gas is stopped at the other monitoring equipment B, and the diffusion range of the upstream of the alarm point A is L at the moment AB Downstream diffusion range is x 2 。
As a further improvement of the technical scheme of the invention, leaked gas is mixed with gas in the pipeline under the action of water flow of the rainwater and sewage pipeline, so that the on-way attenuation of the gas concentration is intensified, and according to the maximum injury criterion, for a concentration area of the rainwater and sewage pipeline, which is greater than or equal to 50% of the lower explosion limit of methane, the diffusion range of the combustible gas is calculated in the absence of water flow, at the moment:
as a further improvement of the technical scheme of the invention, the rate q of the combustible gas leaking into the electric power pipe ditch is 1.44m 3 /h。
As a further improvement of the technical solution of the present invention, the threshold range is: less than or equal to 200m.
As a further improvement of the technical scheme of the invention, when the actual pipeline fullness lambda is unknown, the pipeline fullness is taken to be 0.25.
As a further improvement of the technical scheme of the invention, the value range of the roughness coefficient is 0.013-0.014.
The invention has the advantages that:
the technical scheme of the invention is combined with practical engineering application, and the influence of cost, equipment monitoring effectiveness, complexity of field construction environment and the like is considered, the diffusion rule of the fuel gas in a communication pipeline during single-point alarm is researched, the farthest diffusion distance of the fuel gas and the diffusion range of the concentration of 50% explosion lower limit in the state are obtained, and auxiliary support is provided for a city manager to explore the influence consequence after the fuel gas is leaked; for the rain sewage pipeline, the influence of water flow in the communicating pipeline on gas diffusion is considered, and the calculation is more accurate.
Drawings
Fig. 1 is a flowchart of a method for acquiring a gas diffusion range under a single-point alarm of a communication pipeline according to an embodiment of the present invention;
fig. 2 is a schematic view of a hydraulic radius calculation of a rainwater and sewage pipeline according to a method for acquiring a gas diffusion range under a single-point alarm of a communication pipeline in an embodiment of the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The technical scheme of the invention is further described by combining the drawings and specific embodiments in the specification:
example one
As shown in fig. 1, a method for acquiring a gas diffusion range under single-point alarm of a communication pipeline is implemented according to position information of the communication pipeline, the type of the communication pipeline, the position of an inspection well of the communication pipeline, elevation data, the material of the communication pipeline, alarm concentration and alarm time; and the size of the electric power pipe ditch, the gradient of the rain and sewage pipeline, the water flow speed, the gas diffusion speed and the prediction time are used for predicting the combustible gas diffusion range. The farthest diffusion distance of the gas under the situation is obtained by analyzing the gas diffusion rule when a single inspection well in a communicating pipeline for monitoring equipment to alarm is arranged in the adjacent underground space around the urban gas pipeline, and then auxiliary support is provided for a city manager to explore the influence result after the gas is leaked. The method is suitable for analyzing the gas diffusion range in the communicating pipeline for the alarm of the monitoring equipment installed in the adjacent underground space around the urban gas pipeline.
The method is an effective means for monitoring gas leakage by installing combustible gas monitoring equipment for alarming in adjacent underground spaces around the urban gas pipeline. When the diffusion range of the combustible gas communication pipeline is analyzed, when the pipeline where the alarm well is located is a power cable trench, a rainwater pipeline, a sewage pipeline and a rainwater-sewage combined pipeline, no simultaneous alarm device exists in 200m upstream and downstream of the same pipeline, or when a plurality of alarm points exist on the same communication pipeline, but the distance interval between the alarm points is more than 200m (or the interval is less than 200m but the initial alarm time interval between two adjacent points is more than 200 min), the alarm point of the communication pipeline caused by the same leakage is considered to be a single alarm point, and the diffusion range of the combustible gas in the pipeline is calculated by adopting the following rule.
The connecting pipeline mainly comprises two types, one type is a power pipe ditch, and the combustible gas is diffused under the combined action of the entering speed and the concentration gradient after entering; the second type is a rain sewage pipeline, and the flow of water in the rain sewage pipeline has shearing force on gas above the rain sewage pipeline, so that combustible gas is driven to flow downstream, and meanwhile, the gas is accelerated in a short range and can be accelerated to have stable speed.
1. Diffusion range of gas in electric power pipe ditch during single-point alarm
In order to explore the diffusion rule of gas leakage in the electric power pipe ditch, a gas diffusion experiment model in a micro leakage state is designed according to the maximum damage criterion. The model comprises a square pipeline, a gas leakage system, an alarm system and the like. Experiments were conducted in a pipeline of 25 meters in length using 99.99% gas, and the alarm times at 50% LEL (lower explosion limit) were recorded at alarm points 1.02 meters, 5.89 meters, 10.77 meters, 15.65 meters, 20.52 meters, 22.95 meters from the leak point.
As the diffusion of the gas in the electric power pipe ditch is mainly influenced by the leakage amount, the section size of the pipeline and the like, the relevant parameters are set as follows:
table 1 experimental parameter settings
| Serial number | Leakage q/(m) 3 /h) | Section size (mm X mm) |
| 1 | 0.5 | 300×300 |
| 2 | 1.0 | 600×600 |
| 3 | 1.5 | |
| 4 | 2.0 | |
| 5 | 2.5 |
The experimental results are as follows:
TABLE 2 Experimental results Table (alarm concentration 50% LEL)
(1) Model experiment similarity analysis
According to experimental results, the alarm is shorter when the leakage quantity is larger, and the alarm time is longer when the section width is larger, so that the influences of the leakage quantity and the section width on the alarm time are opposite. The relative size of the leak and the impact on the experiment were described by the ratio of the two (q/b), i.e. the single wide leak.
In the formula: the subscripts m and p represent the model and the actual project, respectively. Thus, the leak rate scale is equal to the width scale.
When the experimental gas and the actual natural gas are basically consistent, the early diffusion time of the tiny leakage in the narrow and long space is less than 15min, and the aspect ratio of the pipeline section is more than 1/3,
λ q ＝λ b (2)
the transverse concentration gradient of methane can be approximately 0, which is a two-dimensional diffusion with insufficient vertical diffusion (there is a larger concentration gradient in the longitudinal and vertical directions, and the latter is much larger than the former). The formula is similar diffusion model promptly, and alarm time scale and the probe longitudinal position scale are 1 this moment, promptly:
λ t ＝λ x ＝1 (3)
according to the influence trend of single wide leakage quantity on the alarm response curve of the experimental result, according to the parabolic function t = a 1 x 2 +a 2 x+a 3 The data fitting was performed separately for each set of experiments,their fitting parameters were determined as in table 2 (where the alarm response time was derived from the average of each set of experiments). By analyzing the influence of single-width leakage on the parabolic fitting parameters, a 1 、a 2 、a 3 All decrease with increasing amount of single width leakage, i.e.
Then, the functional relationship is determined according to the negative power exponential function, namely the empirical formula of the alarm response curve is determined as follows:
after the inspection well alarm is obtained by converting the above formula, the upward (downward) diffusion distance (50% LEL concentration) is as follows:
q is the rate of gas leakage into the pipeline, m 3 H; b is the section width m; t is input time, min; when the formula is adopted for calculation, the input time is larger than 1,x 1 Diffusion distance after t minutes; for leaks that diffuse through the soil, the rate of entry into the pipeline is generally less than 1.44m 3 H (400 ml/s), where q is preferably 1.44m 3 /h。
During real-time calculation, when other monitoring equipment B exists in the pipeline where the alarm point A is located, when the diffusion range x is predicted 1 Greater than L AB But B is not alarming, then B diffusesAnd terminates. The diffusion ranges of the upstream and the downstream are L AB . At the moment, calculation can be carried out according to longitude and latitude coordinates between A, B to obtain an upstream and downstream diffusion range L AB 。
2. Diffusion range of gas in rain and sewage pipeline during single-point alarm
As shown in figure 2, for the municipal rainwater and sewage pipeline, the water flow is mainly gravity flow, the water flow direction is judged according to the pipe top ground elevations at the two ends of the pipe section, and the water flow flows from the height of the pipe top ground elevation to the height of the pipe top ground elevation.
The calculated water flow rate of the sewer line under constant flow conditions can be calculated as follows:
in the formula v water The water flow speed is m/s; d is the diameter of the pipeline, m; r is the hydraulic radius of the drain pipe, m; i is hydraulic slope, which is approximate to the available slope and is the ratio of the vertical height h from the alarm inspection well to the slope surface of the next inspection well and the distance l in the horizontal direction, and the minimum slope of the drainage pipeline is shown in a table 3; n is a roughness coefficient. The value range of the roughness coefficient of the concrete pipe is 0.013-0.014.λ is the pipe fullness, table 4 shows the maximum design fullness corresponding to different pipe diameters required by the standard, and when the actual fullness is unknown, the above calculation can be performed under the assumption that the pipe fullness is 0.25. Theta is radian.
The velocity of the gas in the sewer pipe is about 30% of the flow velocity of the sewage, so the gas diffusion velocity can be expressed as
v gas ＝0.3v water (12)
The distance that the gas diffuses downstream in the storm sewage line may be expressed as:
x 2 ＝v gas (60t) (13)
because the position of the leaked gas entering the pipeline is not necessarily at the alarm inspection well, the leaked gas possibly diffuses from the upstream and enters the alarm inspection well along with the water flow. So that the gas is defined by x 2 The length is diffused upwards and downwards.
TABLE 3 minimum pipe diameter and corresponding minimum design grade
| Caliber (mm) | Minimum design gradient of reinforced concrete non-full flow pipe |
| 300 | 0.003 |
| 400 | 0.0015 |
| 500 | 0.0012 |
| 600 | 0.0010 |
| 800 | 0.0008 |
| 1000；1200 | 0.0006 |
| 1400，1500 | 0.0005 |
TABLE 4 maximum fullness
| Pipe diameter or canal height (mm) | Maximum design fullness |
| 200-300 | 0.55 |
| 350-450 | 0.65 |
| 500-900 | 0.70 |
| ≥1000 | 0.75 |
When the calculation accuracy is required to be high, the gas diffusion velocity can be expressed in the following manner.
The air flow velocity calculation formula in the drain pipe is as follows:
v gas ＝0.397(Wv water /P air ) 0.7234 (14)
wherein W is the width of the water surface, P air The circumference of the air layer in the tube.
P air ＝πD-0.5Dθ (16)
When other monitoring equipment B exists in the range of 200m downstream of the pipeline where the alarm point A is positioned, when the diffusion range x is predicted 2 Greater than L AB And B does not alarm, the downstream diffusion is terminated at B. The diffusion ranges of the upstream and the downstream are L AB 。
When other monitoring equipment B exists in the range of 200m upstream of the pipeline where the alarm point A is located, when the diffusion range x is predicted 2 Greater than L AB If B is not alarming, the upstream diffusion is terminated at B, and the range of the upstream diffusion is L AB . Diffusion continues downstream.
The leaked gas will be mixed with the gas in the pipeline under the action of the water flow of the rain sewage pipeline, so that the gas concentration is attenuated along the way and is increased. According to the injury maximization criterion, the calculation error of the rainwater and sewage pipeline is modified as follows for the high concentration area (50% LEL) of the rainwater and sewage pipeline to be calculated in the high concentration range without water flow according to the following formula (8):
the above examples are only intended to illustrate the technical solution of the present invention, and not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (7)
1. A method for acquiring a gas diffusion range under single-point alarm of a communicating pipeline is characterized by being used in a scene when a single inspection well in the communicating pipeline for monitoring equipment alarm is arranged in adjacent underground spaces around an urban gas pipeline, wherein the communicating pipeline comprises a power pipe ditch and a rainwater and sewage pipeline;
when the combustible gas diffuses in the electric power pipe ditch, under the condition of single-point alarm, the diffusion distance of the combustible gas is calculated according to the concentration of more than or equal to 50% of the lower explosion limit of methane:
wherein x is 1 The diffusion distance of the combustible gas in the electric power pipe trench after t minutes relative to the upstream or downstream of the alarm point is represented by q, which represents the rate of combustible gas leakage into the electric power pipe trench and is expressed in m 3 B represents the section width of the power pipe ditch, and the unit is m; t is input time, min; when the formula is adopted for calculation, the input time is more than 1;
when the combustible gas diffuses in the electric power pipe ditch, when the pipeline where the alarm point A is located has other monitoring equipment B, and when x1 is larger than the distance L between the alarm point A and the other monitoring equipment B AB And the other monitoring equipment B does not give an alarm, the diffusion of the combustible gas is stopped at the other monitoring equipment B, and the diffusion ranges of the upstream and downstream of the alarm point A are L at the moment AB ；
When combustible gas diffuses in the rain sewage pipeline, because the flow of water in the rain sewage pipeline has shearing force on the gas above the rain sewage pipeline, the combustible gas is driven to flow downstream and accelerate the gas and stabilize the speed of the gas, and under the condition of single-point alarm, the diffusion range of the combustible gas is calculated according to the following mode:
the flow velocity of the rainwater and sewage pipeline under the constant flow condition is calculated according to the following formula:
wherein v is water Is the water flow speed, and the unit is m/s; d is the diameter of the pipeline, m; r is the hydraulic radius of the rain sewage pipeline, and the unit is m; i is water powerDescending the slope; n is a roughness coefficient; lambda is the pipeline fullness; theta is radian; d is the diameter of the rain sewage pipeline;
the flow speed of combustible gas in the rain and sewage pipeline is 30 percent of the flow speed of sewage, so the gas diffusion speed v gas Expressed as:
v gas ＝0.3v water
the diffusion range of the combustible gas in the storm sewage line is expressed as:
x 2 ＝v gas (60t)
wherein x is 2 The diffusion distance of the combustible gas in the rainwater and sewage pipeline relative to the alarm point in the downstream direction after t minutes;
when combustible gas diffuses in the rainwater and sewage pipeline, when the alarm point A is in the downstream threshold range of the pipeline, other monitoring equipment B exists, and when x is 2 Is greater than the distance L between the alarm point A and other monitoring equipment B AB And the other monitoring equipment B does not give an alarm, the diffusion of the combustible gas is stopped at the other monitoring equipment B, and the diffusion ranges of the upstream and downstream of the alarm point A are L at the moment AB ；
When combustible gas diffuses in the rain and sewage pipeline, when the alarm point A is in the upstream threshold range of the pipeline, other monitoring equipment B exists, when x 2 Is greater than the distance L between the alarm point A and other monitoring equipment B AB And the other monitoring equipment B does not give an alarm, the diffusion of the upstream combustible gas is stopped at the other monitoring equipment B, and the diffusion range of the upstream of the alarm point A is L AB Downstream diffusion range is x 2 。
2. The method for obtaining the gas diffusion range under the single-point alarm of the communication pipeline according to claim 1, wherein when the combustible gas diffuses in the rainwater and sewage pipeline, the gas diffusion speed is accurately calculated by the following method:
v gas ＝0.397(Wv water /P air ) 0.7234
P air ＝πD-0.5Dθ
wherein W is the water surface width, P air The circumference of the air layer in the tube.
3. The method for obtaining the gas diffusion range under the single-point alarm of the communicating pipeline according to claim 1, wherein the leaked gas is mixed with the gas in the pipeline under the action of the water flow of the storm sewage pipeline, so that the gas concentration is gradually attenuated, and according to the maximum damage criterion, the diffusion range of the combustible gas is calculated in the absence of the water flow for a concentration area of the storm sewage pipeline, which is greater than or equal to 50% of the lower explosion limit of methane, at the moment:
4. the method for acquiring the gas diffusion range under the single-point alarm of the communicating pipeline according to any one of claims 1 to 3, wherein the rate q of the combustible gas leaking into the electric power pipe ditch is 1.44m 3 /h。
5. The method for obtaining the gas diffusion range under the single-point alarm of the communication pipeline according to claim 1, wherein the threshold range is as follows: less than or equal to 200m.
6. The method for acquiring the gas diffusion range under the single-point alarm of the communicating pipeline according to any one of claims 1 to 3, wherein when the actual pipeline fullness lambda is unknown, the pipeline fullness is taken to be 0.25.
7. The method for acquiring the gas diffusion range under the single-point alarm of the communicating pipeline according to any one of claims 1 to 3, wherein the rough coefficient is in a value range of 0.013 to 0.014.
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Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH08303699A (en) * | 1995-04-28 | 1996-11-22 | Kawasaki Steel Corp | Detecting method and device for abnormality of fluid transport piping system |
| JP2009287665A (en) * | 2008-05-29 | 2009-12-10 | Hitachi Ltd | Hazardous area monitoring system for pipeline |
| CN102518947A (en) * | 2011-12-06 | 2012-06-27 | 北京大方科技有限责任公司 | Real-time monitoring method for urban pipeline network leakage |
| CN104776319A (en) * | 2015-02-05 | 2015-07-15 | 北京理工大学 | Multi-path air sampling type online monitoring method and system for fuel gas in inspection well |
| CN107526905A (en) * | 2017-10-16 | 2017-12-29 | 哈尔滨理工大学 | The research method of chlorine leakage obstacle thing diffusion based on FLUENT |
| CN108119760A (en) * | 2017-12-06 | 2018-06-05 | 北京理工大学 | A kind of localization method and system of underground gas pipeline leakage region |
| CN110043806A (en) * | 2019-05-16 | 2019-07-23 | 哈尔滨工业大学 | It is traced to the source based on two o'clock optimizing the method for positioning combustion gas direct-burried pipeline leakage point |
| CN110230779A (en) * | 2019-07-02 | 2019-09-13 | 安徽理工大学 | A kind of urban underground gas pepe monitoring system |
| CN112880931A (en) * | 2021-01-13 | 2021-06-01 | 盐城墨韵电子科技有限公司 | Gas safety monitoring method and cloud monitoring platform based on synergistic effect of Internet of things and big data |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006275228A (en) * | 2005-03-30 | 2006-10-12 | Sumitomo Chemical Co Ltd | Gas diffusion preventive barrier, effectiveness evaluating method of diffusion preventive function, evaluating system and evaluating program |
| CN112633552B (en) * | 2020-11-27 | 2022-05-13 | 合肥泽众城市智能科技有限公司 | Gas pipeline and peripheral pipeline coupling hidden danger identification and risk assessment method and system |
| CN112664839B (en) * | 2020-11-27 | 2021-12-24 | 合肥泽众城市智能科技有限公司 | Method and system for predicting and tracing combustible gas diffusion of communication pipeline |
-
2021
- 2021-06-22 CN CN202110692670.4A patent/CN113435727B/en active Active
Patent Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH08303699A (en) * | 1995-04-28 | 1996-11-22 | Kawasaki Steel Corp | Detecting method and device for abnormality of fluid transport piping system |
| JP2009287665A (en) * | 2008-05-29 | 2009-12-10 | Hitachi Ltd | Hazardous area monitoring system for pipeline |
| CN102518947A (en) * | 2011-12-06 | 2012-06-27 | 北京大方科技有限责任公司 | Real-time monitoring method for urban pipeline network leakage |
| CN104776319A (en) * | 2015-02-05 | 2015-07-15 | 北京理工大学 | Multi-path air sampling type online monitoring method and system for fuel gas in inspection well |
| CN107526905A (en) * | 2017-10-16 | 2017-12-29 | 哈尔滨理工大学 | The research method of chlorine leakage obstacle thing diffusion based on FLUENT |
| CN108119760A (en) * | 2017-12-06 | 2018-06-05 | 北京理工大学 | A kind of localization method and system of underground gas pipeline leakage region |
| CN110043806A (en) * | 2019-05-16 | 2019-07-23 | 哈尔滨工业大学 | It is traced to the source based on two o'clock optimizing the method for positioning combustion gas direct-burried pipeline leakage point |
| CN110230779A (en) * | 2019-07-02 | 2019-09-13 | 安徽理工大学 | A kind of urban underground gas pepe monitoring system |
| CN112880931A (en) * | 2021-01-13 | 2021-06-01 | 盐城墨韵电子科技有限公司 | Gas safety monitoring method and cloud monitoring platform based on synergistic effect of Internet of things and big data |
Non-Patent Citations (3)
| Title |
|---|
| 地下空间燃气聚集报警分级模型研究;侯龙飞;《科技创新与应用》;20210531;全文 * |
| 燃气管道非稳态泄漏及扩散的模拟;张甫仁等;《哈尔滨工业大学学报》;20090515(第05期);全文 * |
| 长输燃气管道风险分析及安全防护距离研究;张润菊;《中国优秀博硕士学位论文全文数据库（硕士） 工程科技1辑》;20170315;全文 * |
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