A Design Method for L-shaped Lateral Explosion Relief Duct Structure

Abstract

The present invention relates to the technical field of safety prevention and control, and particularly to a design method for an L-shaped lateral explosion relief duct structure, which includes collecting on-site environmental data and performing scaling in the same proportion; designing a structural proportionality coefficient and calculating the length of the horizontal duct and the length of the vertical duct; constructing n explosion chambers through FLACS; and setting pressure detection points to measure the pressure value of the explosion relief duct on the explosion chamber; calculating the final explosion relief duct structure coefficient, and obtaining the values of the length of the horizontal duct and the length of the vertical duct according to the explosion relief duct structure coefficient. The present invention provides a combined analysis of the explosion relief effect with numerical simulation, improves the design of the explosion relief duct structure, and provides a reference for the safety prevention and control work of underground spaces.

Description

Technical Field

[0001] The present invention relates to the technical field of safety prevention and control, and particularly to a design method for an L-shaped lateral explosion relief duct structure. Background Art

[0002] With the continuous development of society, people's pursuit of green life has been continuously improved, and domestic gas construction projects have become increasingly perfect. When buried long-distance pipelines are in service, pipe leakage and fracture will occur under the combined action of factors such as corrosion, external force damage, terrain changes, and internal pressure. If a gas pipeline fails and leaks, it is extremely easy to cause an explosion accident when encountering a fire source. If effective preventive measures cannot be taken, it will inevitably cause serious personal injuries and property losses.

[0003] In view of the various openings such as ventilation openings, drainage openings, and inspection openings in the urban underground space, and discharging the explosion wave and flame of gas explosion through these openings, the explosion relief technology in the urban underground space is an important consideration. Aiming at the potential damage hazards that may be generated by an explosion in a confined space, an explosion relief opening is generally set, and many scholars have also carried out research on this. However, the explosion relief opening has great limitations and is affected by the on-site environment. In many cases, safe discharge cannot be achieved. Therefore, in the underground space, a lateral explosion relief method is adopted, and an L-shaped duct is used to guide the substances and energy generated after the explosion to a safe area to protect the underground space structure. Summary of the Invention

[0004] Aiming at the deficiencies of the existing algorithms, the present invention provides an analysis of the explosion relief effect in combination with numerical simulation, improves the design of the explosion relief duct structure, and provides a reference for the safety prevention and control work in the underground space.

[0005] The technical solution adopted by the present invention is: a design method for an L-shaped lateral explosion relief duct structure includes the following steps:

[0006] Step 1: Collect on-site environmental data and perform scaling in the same proportion;

[0007] Furthermore, the on-site environmental data includes: underground space environmental parameters and underground space design parameters.

[0008] Furthermore, the underground space environmental parameters include gas components and concentration, pressure, and temperature.

[0009] Furthermore, the underground space design parameters include the internal size of the underground space, the total length of the explosion relief duct, and the effective explosion relief area.

[0010] Step 2: Design a structural proportionality coefficient and calculate the length of the horizontal duct and the length of the vertical duct;

[0011] Furthermore, the formula for the structural proportionality coefficient is:

[0012]

[0013] Among them, n is the average number of segmented sections of the total length of the explosion venting duct, and the value range is {1, 2, 3...}; i is a variable, and the value range is {0, 1, 2, 3...}; K i is the structural proportion coefficient of the explosion venting duct for the i-th group; is the length of the horizontal duct for the i-th group, with the unit of m; is the length of the vertical duct for the i-th group, with the unit of m.

[0014] Furthermore, the formulas for the length of the horizontal duct and the length of the vertical duct are:

[0015]

[0016]

[0017] In the formula, L is the total length of the explosion venting duct, with the unit of m; K i is the structural proportion coefficient of the explosion venting duct for the i-th group.

[0018] Step 3: Construct n explosion chambers through FLACS; among them, the first explosion chamber is provided with an explosion vent for comparative analysis, and the n - 1 explosion chambers are respectively provided with explosion venting ducts with corresponding structural proportion coefficients for studying the explosion venting effects of explosion venting ducts with different structural proportion coefficients;

[0019] And set the pressure detection point P i , 0 ≤ i ≤ n, and measure the pressure value of the explosion chamber by the FLACS software through the explosion venting duct;

[0020] Step 4: Calculate the final structural coefficient of the explosion venting duct, and obtain the values of the length of the horizontal duct and the length of the vertical duct according to the structural coefficient of the explosion venting duct;

[0021] Furthermore, when calculating the final structural coefficient of the explosion venting duct, select the time of the maximum pressure peak value and the explosion venting duct structural coefficient corresponding to the smallest difference between the pressure value of the explosion chamber and the pressure value of the explosion vent.

[0022] Step 5: Obtain the corresponding length of the horizontal duct and the length of the vertical duct according to the final structural coefficient of the explosion venting duct.

[0023] Advantages of the present invention:

[0024] 1. Introduce the structural proportion coefficient, and optimize the structural design of the explosion venting duct in combination with numerical simulation, rationally design the explosion venting duct, provide a reference for the safety prevention and control work of underground spaces; and ensure the safe discharge of substances and energy generated by the explosion, reduce the explosion pressure in the underground space, thereby protecting the internal structure of the underground space;

[0025] 2. Optimize the structural design of the explosion venting duct, greatly save costs, enhance the explosion venting effect, and have great engineering application value. Brief Description of the Drawings

[0026] Figure 1 is the flowchart of the structural design method of the L-shaped lateral explosion venting duct of the present invention;

[0027] Figure 2 is the three-dimensional model structure diagram of different explosion chambers of the present invention;

[0028] Figure 3 is the curve graph of the pressure change of different structural proportion coefficients of the present invention;

[0029] Figure 4 is the curve graph of the peak pressure and time at different explosion chamber center positions of the present invention. Detailed Embodiment

[0030] The present invention will be further described below in conjunction with the drawings and embodiments. This figure is a simplified schematic diagram, which only illustrates the basic structure of the present invention in a schematic manner. Therefore, it only shows the components related to the present invention.

[0031] As Figure 1 shown, it is the flowchart of a structural design method of an L-shaped lateral explosion venting duct provided by the detailed embodiment of the present invention. The method includes the following steps:

[0032] Step 1: Collect on-site environmental data;

[0033] In this embodiment, the following set working conditions are selected. The environmental parameter settings include a methane concentration of 10%, an environmental pressure of standard atmospheric pressure, and an environmental temperature of 20°C; the internal dimensions of the underground space are 1.8m × 2.8 × 10m, the total length of the explosion venting duct is 6m, and the effective explosion venting area is 0.25m 2 ; In order to improve the computer operation speed and accuracy, the model is scaled down by 5 times. In the simulation, the size of the explosion chamber is 0.36m × 0.56m × 2m, the length of the explosion venting duct is 1.2m, and the effective explosion venting area is 0.01m 2 .

[0034] Step 2: Introduce the structural proportion coefficient K i , calculate the horizontal duct length and the horizontal duct length

[0035] Substitute the explosion venting duct length of 1.2m in Step 1 into formulas (1)-(3), set n = 6, and the calculation results are shown in Table 1; among them, when i = 0, set the explosion vent; when i ≥ 1, set the explosion venting duct.

[0036] Table 1 Different explosion chamber setting working conditions

[0037]

[0038] Step 3: Construct 6 explosion chambers through FLACS and set pressure monitoring point P i 。

[0039] According to Step 1, construct 6 explosion chambers with dimensions of 0.36m×0.56m×2m. Combine the working conditions set in Tables 1 of Step 2 and Step 3. The explosion chamber codes are: 001, 002, 003, 004, 005, 006; and set pressure monitoring point P at the center position of the explosion chamber i ,and the 3D model is as Figure 2 。

[0040] Step 4: Determine the optimal structural proportion coefficient

[0041] According to the pressure monitoring points set in Step 3, output the pressure values through the FLACS software and draw the pressure change curves of different structural proportion coefficients Figure 3 ,compare the influence of explosion relief ducts with different structural proportion coefficients on the pressure in the explosion chamber; the pressure peak value of the curve corresponding to K5 is obviously smaller than that of other curves, and the time to reach the peak value is delayed, with a significant buffering effect. It is thus found that when 0 < i ≤ 4, the influence on the explosion relief effect is relatively small

[0042] As Figure 4 shown, the peak pressure and time curve graph at different explosion chamber center positions. For explosion chamber 001, the time is 0.118s and the peak pressure reached is 0.328MPa; for explosion chamber 002, the time is 0.101s and the peak pressure reached is 0.542MPa; for explosion chamber 003, the time is 0.105s and the peak pressure reached is 0.526MPa; for explosion chamber 004, the time is 0.096s and the peak pressure reached is 0.568MPa; for explosion chamber 005, the time is 0.105s and the peak pressure reached is 0.536MPa; for explosion chamber 006, the time is 0.150s and the peak pressure reached is 0.377MPa

[0043] Step 5: Obtain the corresponding horizontal duct length and vertical duct length according to the final explosion relief duct structure coefficient

[0044] It is thus obtained that when i = 5 and the explosion relief duct structure coefficient is 5 / 1, the peak pressure is close to the direct explosion relief method (explosion relief opening i = 0), and the time to reach the peak value is delayed, with a good buffering effect. Therefore, set n = 6, and K5 is the optimal structural proportion coefficient. The horizontal duct length and the vertical duct length

[0045] Model verification

[0046] To verify the accuracy of the numerical model, the numerical simulation results were compared with the experimental results of the deflagration pressure of methane-air mixture in a rectangular duct carried out by Wen Hu. Under the condition of no explosion vent, the absolute error value of the numerical simulation pressure peak was 0.005 MPa, and the relative error value was 0.6%. The relative error was much less than 10%, meeting the requirements and conforming to the simulation experimental conditions.

[0047] The present invention introduces the structural proportion coefficient into the structural design of the explosion vent duct, combines with numerical simulation to analyze the explosion vent effect, and reasonably designs the explosion vent duct, providing a reference for the safety prevention and control work of underground spaces.

[0048] Taking the ideal embodiments based on the present invention as the inspiration, through the above description, relevant staff can completely make various changes and modifications within the scope not deviating from the technical idea of this invention. The technical scope of this invention is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A design method for an L-shaped lateral explosion relief duct structure, characterized in that It includes the following steps: Step 1: Collect on-site environmental data and perform scaling at the same ratio; Step 2: Design the structural proportion coefficient and calculate the horizontal duct length and vertical duct length; The formula for the structural proportion coefficient is: Among them, n is the average number of equally divided segments of the total length of the explosion venting ducts, with values {1, 2, 3...}; i is a variable, with values {0, 1, 2, 3...}; K i is the structural proportion coefficient of the explosion venting ducts in the i-th group; is the length of the horizontal ducts in the i-th group; is the length of the vertical ducts in the i-th group; The formulas for the horizontal duct length and vertical duct length are: Where L is the total length of the explosion venting duct, in m; K i is the structural proportion coefficient of the i-th group of explosion venting ducts; Step 3: Construct n explosion chambers through FLACS. Among them, the first explosion chamber is provided with a pressure relief opening for comparative analysis, and the n - 1 explosion chambers are respectively provided with explosion relief ducts corresponding to the structural proportion coefficients; and pressure detection points are set to measure the pressure values of the explosion relief ducts on the explosion chambers; Step 4: Calculate the final structural proportion coefficient of the explosion relief duct, and obtain the values of the horizontal duct length and vertical duct length according to the structural proportion coefficient of the explosion relief duct; Calculating the final structural proportion coefficient of the explosion relief duct is to select the time of the maximum pressure peak value and the explosion chamber pressure value with the smallest difference from the pressure value of the pressure relief opening, corresponding to the structural proportion coefficient of the explosion relief duct.

2. The L-shaped lateral explosion venting duct structure design method according to claim 1, characterized in that, The on-site environmental data includes: underground space environmental parameters and underground space design parameters.

3. The L-shaped lateral explosion venting duct structure design method according to claim 2, characterized in that, The underground space environmental parameters include: gas components and concentrations, pressure, and temperature.

4. The L-shaped lateral explosion relief duct structure design method according to claim 2, characterized in that The underground space design parameters include: internal dimensions of the underground space, total length of the explosion relief duct, and effective explosion relief area.

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