Numerical simulation of diffusion/accumulation characteristics of hydrogen-blended natural gas leakage in compressor room
Based on the computational fluid dynamics method,a multicomponent diffusion unsteady state three-dimensional numerical model is constructed to study the diffusion and accu-mulation characteristics of hydrogen-blended natural gas leakage in the compressor room.The simulation results show that under 3 MPa pressure,after the hydrogen blending ratio increases from 10％to 20％and 30％,the time to reach the alarm concentration decreases from 490 s to 437 s and 397 s.And the time to reach the lower limit of ignition and detonation decreases from 2 859 s to 2 742 s and 2 560 s;under the hydrogen blending ratio of 30％.The pressure rises from 3 MPa to 3.5 MPa and 4 MPa,and the time to reach the alarm concentration decreases from 397 s to 367 s,348 s,the time to reach the lower limit of combustion from 2 560 s to 2 400 s,2 306 s.An increase in the hydrogen blending ratio leads to hydrogen"carry"to enhance the role of increased diffusion rate increases,the increase in pipeline pressure leads to an increase in the amount of leakage,so the two increases lead to reaching the lower limit of the alarm concentration and combustion shorten the time.The change in the direction of leakage makes the hydrogen-blended natural gas encounter obstacles to change the chance of encountering obstacles to cause the gas diffusion is blocked,more likely to accumulate,and the danger of the place to increase.After 500 s of leakage,the concentration of hydrogen-blended natural gas at the bottom is 91％of that at the top,while after 1 000 s and 2 000 s,the concentration at the bottom is about 95％and 97.5％of that at the top,so the arrangement of the sensors at the top allows for a faster response and prevents the continuous leakage from leading to an increase in the danger of the whole space.Considering the uncertainty of the location and direction of the leak,it should be arranged densely in the area close to the compressor and sparsely in the area far away from it.
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