JP5189897B2 - Pipeline hazardous area monitoring system - Google Patents

Description

  The present invention relates to a gas pipeline monitoring system for transporting natural gas or the like, and more particularly to a method for defining a dangerous concentration region when transport gas leaks, and a method for reducing the size of the dangerous concentration region.

  Japanese Patent Laid-Open No. 5-223200 describes that a means for automatically opening and closing the gas intake valve is added so that the LNG gas flowing out to the ground surface due to a crack in a LNG (Liquefied Natural Gas) tank does not diffuse beyond the flammable concentration. ing. Japanese Patent Application Laid-Open No. 6-294500 discloses a gas shut-off device, and describes that a shut-off valve is determined using map information and operated so that gas flows in a safe direction. Japanese Patent Application Laid-Open No. 7-101490 describes that if the wind speed is lower than the critical wind speed at the time of gas leakage, a fan is rotated to accelerate the diffusion and to prevent explosion. Japanese Patent Application Laid-Open No. 9-35168 describes that when a fire or the like occurs in an oil storage facility, a change in the disaster situation is predicted. Japanese Unexamined Patent Publication No. 2000-213700 describes that a pipeline is opened and closed by remote control. Japanese Patent Application Laid-Open No. 2006-275228 describes that a gas diffusion protection barrier is provided to suppress gas diffusion itself. Japanese Patent Application Laid-Open No. 2006-329383 describes that a pipe of an existing pipe is divided into a plurality of sections and diagnosis is performed for each section.

The alert range of the pipeline is called High Consequence Area (HCA), and the definition method is shown in each country. The definition of HCA is set forth in the regulations for the country in which it is adopted. In the United States, “MANAGING SYSTEM INTEGRITY OF GAS PIPELINES” AMSE B31.8S-2001 describes it,
r = 0.69 ・ d ・ √p
It is said that. Here, d is the outer shape of the pipe (inch), p is the maximum allowable pressure in the pipe section, and r is the impact circle (feet).

JP-A-5-223200 JP-A-6-294500 JP-A-7-101490 Japanese Patent Laid-Open No. 9-035168 JP 2000-213700 A JP 2006-275228 A JP 2006-329383 A MANAGING SYSTEM INTEGRITY OF GAS PIPELINES / AMSE B31.8S-2001

  The conventional HCA definition can be used to calculate the alert area throughout the pipeline. However, if a gas leaks from the pipeline, it is expected that the gas will diffuse through the air, and the threat of this gas diffusion needs to be monitored.

  An object of the present invention is to provide a method for determining a monitoring range when there is a risk of transportation gas leaking from a pipeline, and to narrow the influence range of gas diffusion by further suppressing gas diffusion.

  In the present invention, in a gas pipeline, if a pipe section that is weakened due to corrosion is broken, how the gas spreads is simulated. Specifically, the pipe section where the stress load is applied is calculated from a place where corrosion is large by stress (stress) calculation, and the diffusion of the gas when the gas is assumed to be ejected from the section is analyzed by the diffusion equation. Areas with high gas concentration are searched for figures of spread due to gas diffusion, buildings such as buildings and public facilities inside it are searched from map data, and the risk level is set based on the gas concentration at the location of the building. Ascertain the public facilities such as buildings and railways that will be used as priority warning areas. The gas diffusion takes into account the momentary change in consideration of the wind direction and wind speed, and calculates the change in the priority alert area. When data of buildings and public facilities are crossed and included in high-risk areas, search for bypass or detour routes, and in some cases, the risk is determined by allocating the transport flow rate to another route pipeline. Calculate the gas transport pressure to lower the pressure. And by controlling the distribution of the flow rate to the new pipeline route, changing the gas transport pressure distribution in the pipeline, and suppressing the gas diffusion range when the pipeline breaks down, building and public facilities To reduce the impact.

  By simulating gas leakage / diffusion from a place where there is a possibility of rupture, a dangerous concentration region accompanying gas diffusion is known, and a monitoring range can be specified. Since this monitoring range changes based on the wind direction and the wind speed, it is possible to identify a dangerous area that changes every moment by acquiring these data via SCADA (Supervisory Control And Data Acquisition). Furthermore, it is possible to reduce the range of gas diffusion by performing control to reduce the transport pressure by distributing a part of the gas flow rate that should flow to the pipeline that is at risk of breakage to the bypass pipeline and bypass route, It will help to avoid damage to human life and health.

  Although the present invention is implemented by software, it is particularly useful to use a monitoring control system such as SCADA in cooperation with a network or the like. When connecting to SCADA, pressure sensor information is received from SCADA, and the gas injection velocity value of the dangerous pipe section is obtained using the sensor information, and the velocity vector value of the ejection is obtained from the velocity value. And the influence range of gas ejection is calculated | required by calculating | requiring the speed force spread.

Pipelines that transport natural gas, etc., have cracks (corrosion cracks) in the place where there is no damage to the soil due to leakage, such as oil, when the pipes are damaged, such as corrosion. Leakage occurs and gas diffuses into the surrounding atmosphere. In the dangerous concentration range, explosions may occur due to factors such as static electricity. In the case of an explosion, the effect is significant, and explosion holes can occur over hundreds of meters. For this reason, an advanced warning area called HCA (High Consequence Area) as shown in FIG. 5 is set along the pipeline to prevent people from entering it, and construction restrictions are imposed on the building. . However, when a building already exists, an effort is made to search for the buildings 508, 509, and 510 included in the range of the HCA, and to reduce the risk by periodic inspection. As a result, the stress determination 507 is performed based on the corrosion 506 included in the pipeline 501, specified as a dangerous pipe section 502, and further, along with pipe sections that are likely to break, such as pipe bending sections and pipe-valve connection sections. The definition is made as the monitoring priority range 504 included in the HCA. The buildings 508 included in the monitoring priority range 504 have a high degree of danger and a high monitoring priority. HCA standards are set in each country. According to the US standard (ASME B31.8), this HCA depends on the maximum allowable operating pressure (MAOP) and is calculated by the equation (1).
r = 0.69 · d · √p (1)
Here, d is the outer shape (inch) of the pipe, p is the maximum allowable operating pressure (MAOP) of the pipe section, and r is the impact circle (feet). r is the distance from the pipeline and is the radius of the circle of the impact circle. The HCA is calculated as band information obtained by connecting the outer circumferences of these circles. Outside the United States, r may be defined by a predetermined distance.

  The HCA is defined throughout the pipeline, but the extent of gas diffusion when a leak occurs is not shown. Especially for gases such as natural gas, petrochemical fluid, carbon dioxide, etc., there is an impact on human life and health. Therefore, the impact range is calculated, and transport control is performed to suppress the gas diffusion range based on the impact range. That is important. FIG. 3 shows an example of a gas diffusion prediction calculation. An HCA is defined along the pipeline 301. It is assumed that gas leaks from the dangerous pipe section 302 in the monitoring priority range 304 of the pipeline 301. At time T1, since the wind direction is the arrow 313, the gas diffuses in the leeward direction. The gas diffusion ranges are 305, 306, 307, and 308 in descending order of concentration, and the regions 305, 306, and 307 are dangerous concentration regions. The dangerous concentration area includes building shapes 315 and 316, and the buildings 317 and 318 are in the gas diffusion range. However, since the concentration is low, the monitoring priority is low. At time T2, the gas diffusion range is 309, 310, 311 and 312 for each gas concentration range because the wind direction is arrow 314, and regions 309, 310 and 311 are dangerous concentration regions. Buildings 319, 320, 321, and 322 are included in the dangerous concentration region. The buildings 319, 320, and 321 have higher monitoring priority than the building 322. Moreover, compared with the buildings 315 to 322 included in the dangerous concentration region, the buildings 324 and 325 are included in the HCA but are not included in the dangerous gas concentration region, so the monitoring priority is low.

  As seen at times T1 and T2, the gas diffusion range changes from moment to moment due to the influence of weather conditions, so a priority monitoring region is set in consideration of gas diffusion at each time. In the present invention, the monitoring priority area is dynamically defined based on not only the setting of the monitoring range by the HCA but also the gas diffusion prediction.

  FIG. 4 is a diagram showing an example in which an influence range search is applied not only to buildings but also to public facilities such as railways and roads. Here, a situation is shown in which gas leaks from the dangerous pipe section 402 in the monitoring priority range 404 of the pipeline 401 and diffuses in accordance with the wind direction 409. Here, it is shown that gas is diffused in the ranges 410, 411, 412 and 413 for each concentration range, and the section 407 of the railway 405 and the section 408 of the road 406 are included in the dangerous concentration region. Therefore, the section of these public facilities becomes the monitoring priority area. In this way, the monitoring priority area can be set by referring to the dangerous concentration area that changes every moment.

  Further, by using this gas diffusion prediction result, it is possible to reduce the influence of gas diffusion by performing transport control that selects a bypass pipeline or a bypass pipeline and distributes the flow rate. FIG. 1 shows the effect of such transport control. When gas diffusion is predicted to occur in the pipe section 107 in the main pipeline 101, the gas diffusion prediction range is 103, which includes buildings 111, 112, and 113, and the priority monitoring range. It becomes. However, by operating the SCADA 109 to open and close the valve 110 and distributing the gas flow to the bypass pipeline (called looping pipeline) 102, the pressure inside the main pipeline 101 is reduced, and the gas diffusion range is 104. It is reduced as follows. The buildings 111, 112, and 113 are out of the dangerous gas concentration region. On the other hand, in the bypass pipeline 102, when it is known that there is a risk of gas diffusion in the pipe section 108, the gas diffusion range when the transport amount is increased is calculated. As a result, the gas diffusion range is 105 at the beginning, but expands to 106. However, there are no buildings in the gas diffusion range 106. By changing the pipe transportation method in this way, the range of gas diffusion can be changed, and the number of dangerous concentration areas and the number of buildings and public facilities included therein can be reduced.

  FIG. 2 shows a system configuration for searching for buildings and public facilities in such a dangerous concentration region and performing transportation control. The system components are shown below.

  Pipe shape database 201: a graphic database storing the shape of pipes. The graphic data is represented by a coordinate sequence including an X coordinate, a Y coordinate, and, in the case of three dimensions, a Z coordinate. The graphic data represents the overall configuration of the pipeline that constitutes the network.

  Corrosion database 202: a database storing information on corrosion inside / outside the pipeline. The basic information of corrosion is the length of pipe in the direction of corrosion, the width in the circumferential direction, the depth (or relative depth in proportion to the pipe wall thickness), the start distance of corrosion (pipe from a reference point on the pipeline) Distance), circumferential start position (starting position is expressed by time, assuming the cross section of the pipe as a clock), and corrosion position (inside / outside). It may also contain information on the type of corrosion (General, Groove, etc.) and the safety factor for corrosion.

  Monitoring range database 203: This database stores the calculated HCA and the shape of the dangerous concentration area. The shape of the HCA and the dangerous concentration area is described by a boundary line of two-dimensional coordinates or three-dimensional coordinates.

  Pipe attribute database 204: a database storing material (pipe steel category, grade, inner diameter, wall thickness, etc.) for each pipe section of the pipeline.

  Map database 205: a database storing feature data represented by vector graphics represented by coordinate strings, such as public facilities such as buildings, railways, and roads.

  Pipe section extraction unit 206: A processing section that extracts line segment data of a pipe section constituting a pipeline described by a coordinate sequence. Since the pipeline itself is described by a coordinate sequence, a line segment designated by two consecutive coordinates is selected from the pipeline.

  Widthening unit 207: A processing unit that performs linewidthing on the line segment data selected by the pipe section extraction unit 206, calculates an HCA, and extracts the result as coordinate data.

  Stress calculation unit 208: a processing unit that calculates a stress value serving as a load on the corrosion portion based on the corrosion data and the pipe attribute.

  Monitoring section identification unit 209: A processing section that identifies a pipe section having a stress greater than or equal to a threshold value in a corroded portion from a pipe section having corrosion, and determines that pipe section as a dangerous pipe section. Further, the HCA of this dangerous pipe section is recalculated and set as a monitoring priority area.

  Gas pressure calculation unit 210: a processing unit that calculates the transport pressure distribution of the pipeline.

  Gas leakage / explosion influence range calculation unit 211: A processing unit that determines the gas leakage reach range using the pressure value and flow velocity value obtained by the gas pressure calculation unit 210 as initial values in the dangerous pipe section. The diffusion range of gas generated by gas leakage is calculated according to the partial differential equation. Also, calculate the impact range when an explosion occurs.

  Building / public facility search unit 212: A processing unit that searches for a building graphic that intersects or is included in a gas diffusion range graphic or an explosion influence range graphic or a public facility graphic such as a school, a hospital, a railway, or a road.

  Safety judgment unit 213: When houses and public facilities are crossed and included in the gas diffusion range, the degree of danger is judged based on the designated evaluation method, and the degree of danger when included in the dangerous concentration region is determined. A processing unit for calculating.

  Pipeline route selection unit 214: a processing unit that selects a pipeline from the pipe shape database 201. In particular, when the pipeline is networked, a process for searching for an alternative route (bypass pipeline route, bypass pipeline route) for a specific pipeline is performed.

  Flow rate adjusting unit 215: a processing unit that performs calculation to change the flow rate of gas flowing through the pipeline and distribute the flow rate of gas to a plurality of pipelines. In addition, when the gas leakage / explosion influence range calculation unit 211 recalculates the influence of gas diffusion as a result of the distribution, if it is included in the dangerous concentration area in the same way, a new pipeline is selected to adjust the flow rate. Will do.

  Valve signal generation unit 216: a processing unit that generates a valve opening / closing signal based on the flow rate change result by the flow rate adjustment unit 215.

  SCADA 217: Process for acquiring pressure and flow measurement data at the inlet and outlet of the pipeline, sending the data to the gas pressure calculator 210, and scattering the signal generated by the valve signal generator 216 to open and close the valve Part.

  In this system configuration, the functions 206 to 216 are collectively referred to as a dangerous area monitoring system hereinafter.

  FIG. 6 shows an algorithm flow for calculating the dynamically changing dangerous concentration region and the monitoring priority region.

(1) Step 11: High alert area determination along the pipeline A band area representing the HCA is set along the pipeline. As shown in FIG. 5, the calculation of the band area is performed by generating a band figure by adding a certain width to the line segment representing the pipeline. As shown in FIG. 7, this band information can be generated as width line segments (HCA boundary lines) 802 and 803 of the pipeline line segment 801 as follows.

  The pipe section extraction unit 206 extracts two continuous line segments constituting the pipeline from the pipe shape database 201. The line segment is composed of points P1, P2, and P2, P3. For these line segments, the width increasing unit 207 generates a band figure having a width of 2d. The band graphic corresponds to the generation of the HCA boundary line graphic 802,803.

  When the coordinates of P0 to P4 are P0 (X0, Y0), P1 (X1, Y1), P2 (X2, Y2), P3 (X3, Y3), and P4 (X4, Y4), the following results.

  Further, the width line 803 on the opposite side is as follows.

Here, A = X2-X1, B = Y2-Y1, C = X3-X2, and D = Y3-Y2. However, the above formula is BC-AD ≠ 0. For BC-AD = 0,
(Y2-Y1) (X3-X2) = (X2-X1) (Y3-Y2) (4)
Because it corresponds to, we carry out through case classification. Assuming that the intersections of the line segment perpendicular to the HCA boundary line 802 from P2 are points 808 and 809, the figure is replaced between the points 808 and 809 by circular interpolation of the center point P2 and the radius d. In addition, when there is an end of a line segment, circular arc interpolation is performed with a radius d. Thereby, the HCA area can be defined as a figure by the boundary lines 802 and 803.

(2) Step 12: Retrieval of Corrosion Distribution The stress calculation unit 208 retrieves corrosion data from the corrosion database 202. Since this corrosion data is managed by the distance from the pipeline reference point, the distance is searched as a keyword.

(3) Step 13: Selection of Hazardous Pipe Section The stress calculation unit 208 includes pipe attribute data having the corrosion data retrieved in Step 12 and the characteristic information (grade, category, inner diameter, wall thickness, etc.) of the pipe steel material related to the pipe section. From the pipe attribute database 204, and using these data, the stress is calculated for the corrosion range, and the stress applied to the corrosion portion is calculated. This stress calculation is obtained by a finite element method or an algebraic method based on mechanical / material mechanics. The algebraic method is as follows.

  The displacement values due to the axial stress and the circumferential stress are given by the following equations.

として、μ_p（せん断弾塑性係数）は以下のようになる。σ_i≦σ_t のときμ_p＝μ、μはせん断弾性係数であり、式(7)で与えられる。 Here, σ _Θ is an axial stress, σ _Z is a circumferential stress, α _Θ is an axial correction coefficient, and α _Z is a circumferential correction coefficient. by this

The μ _p (shear elasto-plastic coefficient) is When σ _i ≦ σ _t , μ _p = μ, μ is a shear elastic modulus, and is given by equation (7).

Here, E _{0 is the} elastic modulus (Young's modulus), and r is the Poisson's ratio. When σ _i > σ _t , equation (8) is obtained. m and σ _{τ depend} on the mechanical attributes of the material. K is a bulk modulus and is given by equation (9).

  As described above, the corrected pipe thickness, the corrected outer diameter, and the representative stress F are obtained as follows.

When the stress value F obtained by the above calculation in the monitoring section specifying unit 209 is larger than a predetermined threshold value F _th , that is, F> F _th (11)
Then, it becomes the dangerous pipe section 302. Then, the HCA is calculated for the dangerous pipe section, and the monitoring priority range 304 is specified. The dangerous pipe section 302 is stored in the monitoring range database 203 by the monitoring section specifying unit 209 together with the coordinate data.

(4) Step 14: Calculation of gas pressure distribution The gas pressure calculation unit 210 calculates a transport pressure distribution along the pipeline. This calculation can be performed by a generally known gas transport flow rate calculation formula.

Here, Q: flow rate, K: coefficient depending on unit system, T _s : reference temperature, P _s : reference pressure, G: gas weight, T _G : gas temperature, h ₂ : downstream height, h ₁ : Height on the upstream side, Z: compression coefficient, f: friction coefficient, D: inner diameter of the pipe. Assuming that the flow rate Q and pressure P _{2 at} the outlet side of the pipeline are known, P ₁ is determined.

(5) Step 15: Acquisition / Update of Wind Direction Data The gas leakage / explosion range calculation unit 211 acquires data on the wind direction from the wind speed, anemometer, or weather information. These data can be obtained from SCADA 217. In the monitoring system shown in FIG. 8, an example in which weather information is acquired from SCADA 904 is shown.

(6) Step 16: Calculation of Gas Diffusion Area The gas leakage / explosion range calculation unit 211 calculates the gas diffusion range by solving the diffusion equation shown in Expression (13). The Navier-Stokes equation, continuity equation, and gas diffusion equation are used to calculate the leakage reach. The following partial differential equation is used.

These equations can be solved by numerical calculation by differentiating them. Various schemas for differentiating can be considered, but any may be used as long as they are stable in numerical calculation. In equation (13), V: velocity vector, ρ: density, μ: kinematic viscosity coefficient, V _out : discharge speed, λ: gas diffusion coefficient, t: time, p: pressure, g: gravitational acceleration, R : Resistance characteristic coefficient of gas cracked part, D: concentration, _Dout : discharge concentration. Here, the initial value u _ini of the velocity u is obtained from the transport pressure value P and the cross-sectional area of corrosion in the corroded portion of the dangerous pipe section of the gas pipeline. The diffusion direction is determined by the wind direction.

  The gas diffusion range is calculated by dividing the area of the gas pipeline into small square meshes having a certain size and calculating each square mesh. The diffusion is terminated when the density value becomes equal to or less than the threshold value. When the gas diffusion simulation is performed and a stable solution is obtained, or when it is within a specific time (simulation time) range, the process is terminated.

The result of the obtained gas diffusion range is as shown by shapes 305 to 308 in FIG. This is a result of dividing the region for each density range. For example, let C be the gas concentration calculated with a square mesh. At this time,
C _a <C <C _b (15)
In the case where the C value falls within the predetermined thresholds C _a and C _b as shown above, it is included in the gas concentration region figure in this range. Then, after obtaining the value of C by numerical calculation with a plurality of square meshes, a mesh that becomes the boundary of the gas concentration range is obtained and registered as a boundary figure. Shapes 305, 306, 307, and 308 represent boundary lines of the obtained density region.

(7) Step 17: Search for public facilities / buildings The housing / public facility search unit 212 uses map data to determine whether the gas diffusion area includes public facilities such as buildings, railways, and roads. Use to search. Specifically, since the inside of the gas diffusion region is described by the gas concentration, the figure included in the inside of the boundary (contour line) figure of the dangerous gas concentration obtained in step 16 is searched. A constituent point coordinate is selected from each figure, a line segment is extended vertically from the constituent point, and the number of times that the line segment completely intersects the contour line is counted. If it completely intersects the same contour line an odd number of times, it is inside the gas diffusion region, and if it completely intersects an even number of times, it is outside the gas diffusion region.

  Since the dangerous concentration range is 309, 310, 311 at time T2 in FIG. 3, building figures 319 to 322 included in this range are searched. In FIG. 4, since the dangerous concentration range is 410, 411, and 412, the railway and road sections 407 and 408 included in this range are searched.

(8) Step 18: Assigning a risk level The safety judgment unit 213 adds a risk level to an area included in the gas diffusion range. This risk is added after the gas diffusion simulation has a stable result. Specifically, the maximum gas concentration C _max is obtained for the mesh-divided region,
C _n <C _max <C _{n + 1}
Then, the risk level R is
R = n (16)
And At this time, when a mesh having C _max is included in the HCA, the risk m is added inside the HCA, and the overall risk R is
R = n + m (17)
And In the equation (16), the thresholds C _n and C _{n + 1} are determined by the user. The result obtained here is stored in the monitoring range database 203 by the safety determination unit 213.

(9) Step 19: Checking the dangerous pipe section The monitoring section specifying unit 209 checks whether or not the processing of steps 12 to 18 has been performed in all the dangerous pipe sections. If another dangerous pipe section exists, gas diffusion prediction is performed in that section.

  A configuration example of the entire monitoring system is shown in FIG. Sensor information acquired in a metering station 902 installed in the pipeline 901 is taken into the SCADA 904 via the network line 903 and monitored. The sensor information is information on pressure and flow rate. Further, the sensor information is sent to the hazardous area monitoring system 906 and used as initial value data of gas diffusion. The SCADA 904 also acquires wind direction and wind speed data and sends them to the hazardous area monitoring system 906.

  The hazardous area monitoring system 906 is based on a geographic information system, calculates the pipeline shape and gas diffusion range as shown in FIG. 1 on a map, and includes a building such as a school or a hospital included in the range, Furthermore, the inclusion relations of public facilities such as roads and railways are calculated.

  The hazardous area monitoring system 906 includes a pipeline maintenance management database that manages corrosion data and pipe replacement data (this database includes a pipe shape database 201, a corrosion database 202, a monitoring range database 203, a pipe attribute database 204, a map database 205). Corrosion data and the like are acquired from the pipeline maintenance management DBMS (database management system) 907. These data are input from the database input system 909. By inputting data in a separate system, it becomes possible to immediately use the input results of corrosion data and pipe replacement data for the calculation of the monitoring priority area and the dangerous concentration area. The calculation result of the dangerous concentration area is notified as alarm information 912 to a building or public facility 910 in the vicinity of the relevant pipeline, and calls attention.

  Next, a transport control method that considers the influence of gas diffusion by obtaining the gas diffusion range will be described. In order to reduce the influence of gas diffusion, a method of distributing the amount of gas transport to a plurality of pipelines can be considered. Thereby, the pressure of transport gas can be reduced and the diffusion range of gas can be suppressed. In FIG. 1, a part of gas transportation by the main pipeline 101 is distributed to the bypass pipeline 102.

This calculation is performed in the dangerous pipe section where the stress in the corroded portion is close to the threshold value. When the stress threshold is F _th , the calculated stress F is F> F _th (18)
In this case, the gas diffusion at break is calculated. And the influence range when gas diffuses is calculated | required. Pipeline transport pressure varies from time to time, and the expected gas diffusion range varies with wind speed and direction.

A method for switching the range of gas diffusion with the change of pressure is shown below. In core pipeline 101, it had sent a flow rate Q _a, large corrosion of the pipe section 107, and there are signs of corrosion cracking, and stress is high. In this case, the gas diffusion is calculated and the flow rate is adjusted. Q = Q _a −Q _b (19)
And At this time, the pressure of the compressor station is determined by decreasing the discharge pressure. This can be obtained from equation (12). When written in a simplified form, QA = F (Q _a , P ₂ , P ₁ )
QB = F (Q _b , P ₂ , P ₁ ) (20)
To adjust the pressure.

In the bypass pipeline, the pressure values are the same at the connection (two locations) with the main pipeline. For this reason, after setting the outlet pressure P ₂ as an initial value, the inlet pressure P ₁ is calculated in both pipelines by equation (12). Then, the flow rate values are distributed so that both the inlet pressures coincide with each other. By reducing the pressure, the transport pressure load in the pipe section 107 can be reduced. On the other hand, when pressure is applied to the bypass pipeline 102, pressure is applied to the pipe section 108 having corrosion. This causes the possibility of breakage (corrosion cracking) at the corroded portion. In this case, the gas diffusion in the pipe section 108 of the bypass pipeline is calculated in the same manner. And it confirms that the diffusion range of gas has little influence on houses and public facilities. However, in the main pipeline 101 or the bypass pipeline 102, when the gas diffusion range includes a building or a public facility in the dangerous concentration region, the flow rate is further distributed to a new bypass pipeline or a bypass pipeline. Then, the gas diffusion calculation is performed again to determine the influence range.

  Next, by changing the flow rate and recalculating the gas diffusion range, the transportation flow rate at the time when the gas concentration including the residential area and public facilities becomes lower than a predetermined threshold value is determined. If the concentration does not fall below the critical concentration even after changing the flow rate to a predetermined bypass pipeline or bypass pipeline, if there is another bypass route or bypass route, distribute the flow to that route. Do. Specifically, the pipeline flow rate, assuming that gas is already flowing, is sequentially reduced and distributed to a new route to determine the influence of gas diffusion.

  FIG. 9 shows an algorithm for distributing such a flow rate.

(1) Step 21: Calculation of gas distribution Steps 11 to 14 shown in FIG. 6 are performed, and the gas pressure calculation unit 210 calculates the transport pressure distribution in the pipe and calculates the pressure value in the dangerous pipe section. .

(2) Step 22: Calculation of gas diffusion range The same processing as in steps 15 to 16 shown in FIG. 6 is performed to calculate the gas diffusion range.

(3) Step 23: Search for buildings / public facilities within the gas diffusion range The building / public facility search unit 212 and the safety judgment unit 213 include buildings included in the dangerous gas concentration region based on a predetermined threshold. And search for public facilities.

(4) Step 24: Inclusion determination If the dangerous gas concentration area does not include a building or public facility, the process ends. If yes, go to Step 25.

(5) Step 25: Search for Bypass / Bypass Route The pipeline route selection unit 214 selects a currently available bypass pipeline and a route having the shortest distance from the bypass pipeline. This is retrieved from the pipe shape database 201.

(6) Step 26: Determination of bypass route and bypass route If no new bypass route or bypass route exists, the process ends. If it exists, go to step 27.

(7) Step 27: Change of flow distribution The flow controller 215 sets the current flow rate of the conventional pipeline as Q ₁ and the changed flow rate as ΔQ as follows. In addition, to set the flow rate Q ₂ of the new pipeline in the following manner.
Q ₁ (NEW) = Q ₁ (CURRENT) −ΔQ (21)
Q ₂ (NEW) = Q ₂ (CURRENT) + ΔQ (22)
Based on this flow rate, the equation (12) is executed, the outlet pressure is made the same, and ΔQ is adjusted so that the inlet pressures of the main pipeline and the bypass pipeline coincide. Thereafter, step 21 is executed.

  With the above flow, it is possible to control transportation focusing on the gas diffusion range. In FIG. 8, the adjustment result of the flow rate in the hazardous area monitoring system 906 is sent to the SCADA 904, and further a signal is sent to the valve 915 through the valve control line 914, and the flow rate is adjusted by opening and closing the valve.

  The above shows the case of gas leakage, but in the case of gas, there is a risk of explosion. The range of influence can be retrieved by introducing an explosion simulation following the diffusion algorithm. Explosion simulation corresponds to shock wave simulation.

  As described above, the calculation result of the gas diffusion range is obtained by coordinating with SCADA, using the flow rate and pressure data acquired by SCADA to obtain the gas pressure distribution in the pipeline, and using the result as the initial value. By simulating diffusion, it is possible to present a dangerous concentration region that changes from moment to moment. Moreover, the danger of a building or a public facility can be grasped | ascertained by displaying a dangerous concentration area | region on a map as graphic information. By taking in wind direction and wind speed data, it is possible to grasp daily changes in the dangerous area. Moreover, in order to reduce the gas diffusion range, the safety of the pipeline can be enhanced by the control for distributing the flow rate. In addition, the effects of gas on human life and health problems can be reduced.

  The gas diffusion countermeasures described above can be applied not only to natural gas but also to petrochemical products such as ethylene and benzene, and carbon dioxide. Ethylene and benzene are liquids, but become gas when they are ejected at the gas break. It is important to follow the movement of this gas. In application to these gases, the density, kinematic viscosity coefficient, thermal expansion coefficient, and diffusion coefficient are changed in equation (13).

  The present invention applies not only to natural gas pipelines, but also from volatile petrochemical products such as ethylene and toxic gases to the public facilities and buildings from gas air diffusion when assuming that the gas has been ejected by pipeline breakage. Predict the arrival of As a result, it is possible to set a monitoring priority range and to quickly respond to an accident. If the pipelines are connected in a network and multiple pipelines can be used, the transportation pressure between the pipelines is adjusted so that the gas does not affect these public facilities and residential areas. The transportation pressure in the dangerous pipe section can be reduced and transported. In this way, gas transportation considering the environment and health can be realized.

It is a figure which shows the method of switching the transport route of gas based on the idea of reduction of the diffusion range of gas. It is the figure which showed the function structure of the system. It is a figure which shows the calculation result of the dangerous concentration area | region and dangerous feature which change dynamically. It is a figure which shows the calculation result of the dangerous concentration area | region and dangerous feature which change dynamically. It is the figure which showed the system which calculates | requires the conventional high alert area (HCA). It is a figure which shows the processing flow which grasps | ascertains the dangerous concentration area | region which fluctuates dynamically. It is a figure which assists the calculation method of HCA. It is a figure which shows the structural example of a monitoring system. It is a figure which shows the processing flow of the transport route switching of a pipeline.

Explanation of symbols

DESCRIPTION OF SYMBOLS 201 ... Pipe shape database, 202 ... Corrosion database, 203 ... Monitoring range database, 204 ... Pipe attribute database, 205 ... Map database, 206 ... Pipe section extraction part, 207 ... Widening part, 208 ... Stress calculation part, 209 ... Monitoring Section specifying unit 210 ... Gas pressure calculation unit 211 ... Gas leakage / explosion range calculation unit 212 ... Building / public facility search unit 213 ... Safety judgment unit 214 ... Pipeline route selection unit 215 ... Flow rate adjustment unit 216 ... Valve signal generation unit, 217 ... SCADA, 901 ... Pipeline, 902 ... Metering station, 904 ... SCADA, 906 ... Hazardous area monitoring system, 907 ... Pipeline maintenance management DBMS, 908 ... Pipeline maintenance management database, 909 ... Database input system 910 ... pipeline near the buildings and public facilities, 915 ... valve

Claims (6)

A pipe shape database storing the shape information of the pipelines constituting the network;
A corrosion database storing information about corrosion present in the pipeline;
A map database storing information on buildings and public facilities near the pipeline;
A stress calculator that calculates stress on the corroded portion of the pipeline based on the information about the corrosion stored in the corrosion database;
A monitoring section identifying unit that extracts a pipe section where stress above the threshold is applied to the corroded portion as a dangerous pipe section;
A pressure calculation unit for calculating the transport pressure distribution of the pipeline;
A gas leakage range calculation unit that predicts and calculates the diffusion of gas ejected from the fractured portion when the dangerous pipe section is assumed to have fractured;
A search unit that searches the map database for buildings and public facilities that enter the dangerous gas concentration range calculated by the gas leakage range calculation unit;
A pipeline route selection unit that searches for an alternative route of the route including the dangerous pipe section from the pipeline shape database;
A flow rate adjusting unit that distributes the flow rate of gas flowing through the pipeline to the alternative route so that there are fewer buildings and public facilities included in the dangerous concentration range;
A pipeline hazardous area monitoring system characterized by comprising:   2. The pipeline hazardous area monitoring system according to claim 1, wherein the pressure calculation unit uses the pressure value and flow rate information sent from SCADA that monitors the pressure and flow rate at the inlet and outlet of the pipeline. Pipeline Hazardous Area Monitoring System characterized by calculating distribution.   2. The pipeline danger area monitoring system according to claim 1, wherein the gas leakage range calculation unit predicts and calculates gas diffusion in consideration of wind direction and wind speed data in the vicinity of the danger pipe section. Regional monitoring system.   2. The pipeline hazardous area monitoring system according to claim 1, wherein the pipeline transports gas.   2. The pipeline hazardous area monitoring system according to claim 1, wherein the pipeline transports a volatile liquid.   The pipeline hazardous area monitoring system according to claim 1, wherein alarm information is notified to a building or public facility included in the dangerous concentration range.

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