Safety Study On Shared Compartment Of Gas And Water,Reclaimed Water Pipeline In Utility Tunnel

Due to the frequent accidents of urban pipelines,including leakage of different aperture and even fracture caused by corrosion,third party destruction,natural disasters and so on.The utility tunnel can effectively avoid the above problems,as well as the repeated excavation,so it is a well solution to lay and manage the pipeline intensively in the utility tunnel.However,taking the gas pipeline as an example,the related standard stipulates that the gas pipeline must be installed separately,which makes the cost of entering the utility tunnel and maintaining the gas pipeline too high.So laying gas pipeline and water supply or reclaimed water pipeline in one compartment is considered.Hence,the safety research under shared compartment is an important part for this engineering feasibility.The gas leakage and explosion in water-gas compartment were studied in detail.The numerical simulation software Fluent is used in established models,including single gas pipeline and single water pipeline,as well as two gas pipelines and two water pipelines,to simulate the natural gas leakage.The existing emergency measures that it can alarm in a very short time is verified,and the leakage mass is very small so it fails to be ignited.Regardless of the vertical or horizontal laying of gas pipeline and water pipeline,the leakage of 2mm-diameter-hole is still free of explosion risk even if the ventilation is interrupted for1 h;the leakage of 4 mm-diameter-hole is not at risk of explosion within 7.5 min of interrupted ventilation;while the leakage of 10 mm-diameter-hole with dynamic pressure,cutting off and emptying the pipeline in time and starting the accident ventilation at the same time,it can ensure the safety of the water-gas compartment.The 162 possible explosion cases in the narrow structure of the water-gas compartment were simulated by gas explosion simulation software FLACS,and whether the deflagration could convert into detonation is verified.The different conditions of vapour cloud were compared,and the volume of vapour cloud and its shape and concentration will influence the overpressure together.The maximum overpresusre can reach 47.14 k Pa,causing people seriously hurt.The maximum overpresusre may not be achieved in explosion center,may be at fire-proof partition at the end of compartment.Also,the coverage of flame is boarder than shock wave,influencing adjacent compartments.Two emergency protection measures including water spray and pressure relief panel were compared,and the water spray will cause the explosion overpressure to rise in some cases,and the pressure relief panel can effectively restrain the explosion power and narrower the flame coverage,and the protection of people is better.The pressure relief panel opening at 10 k Pa could reduce the overpressure 73%,higher than the value 56% of that opening at 20 k Pa.To install the gas pipeline with water pipeline in shared compartment in utility tunnel is safe and feasible.