| FPSO(floating production storage and offloading)The development of offshore oil and gas has become the focus at present and in the future.Due to the intensive arrangement of deck equipment on FPSO and the harsh offshore operation environment,once there is an oil and gas leakage and deflagration accident,it will cause significant damage.In this paper,the simulation experiment and numerical simulation of FPSO fire explosion suppression process are carried out.The main work and conclusions are as follows:(1)A semi open visual simulation platform for the combustion and explosion process of FPSO upper deck is designed and built.The experimental platform includes semi open combustion chamber pipeline,gas distribution system,ignition equipment,water spray system,data acquisition system and synchronous trigger system.The characteristics of flame and overpressure in the explosion process are recorded by high-speed camera and pressure sensor respectively.Through the experiments of different obstacle spacing,water mist particle size,atomization pressure and relative position of obstacles,the density of equipment arrangement on the upper deck of FPSO,different arrangement positions of fire water spray system and water mist parameter scenarios are simulated.(2)The important conclusions of the experiment are as follows:when the distance between two obstacles of different lengths is 100mm and 200mm,compared with the distance of 300mm,the values of deflagration overpressure are reduced by 53.9%and 13.2%respectively.With the increase of the distance between obstacles,the enhancement of flame front turbulence is reduced,and the values of deflagration overpressure are reduced;when the distance between two obstacles is 45 microns,80 microns,160 microns and 200 microns,compared with that without water mist,the values of deflagration overpressure are reduced The peak pressure increases by 3.4%,22.7%,107.1%and 109.4%respectively.The time for the flame front to reach the nozzle is shortened.Part of the water mist vaporizes and absorbs heat under the action of high temperature flame,dilutes the methane concentration,and suppresses the deflagration process.The other part of the water mist droplets can not vaporize in time,acting as obstacles,which disturbs the flame.The flame front changes from "finger like" to "tooth like" The turbulent effect of the induced flame is enhanced and the deflagration process is promoted.With the increase of particle size,the process of water mist promoting deflagration is dominant;with the increase of atomization pressure,the disturbance effect of small droplets of water mist is enhanced,the value of deflagration overpressure is increased,and the time of flame reaching the nozzle is advanced;under the condition of 45 microns water mist obstacle,the value of deflagration overpressure is reduced by 18 compared with that without water mist when the water mist is in front,above and behind the obstacle 3%,2.5%and 19.8%.When the water mist is behind the obstacle,the deflagration overpressure value is the smallest,the flame passes over the obstacle and generates turbulence.When the combustion speed of methane and air is about to increase,the small water mist droplets are more likely to be broken,which can promote the effective vaporization and heat absorption of the water mist and inhibit the deflagration process.(3)Based on the offshore oil "118" as the prototype,the 1:1 physical model is established by FLACS to simulate the leakage and explosion process of combustible gas cloud on the upper deck of FPSO,analyze the influence of leakage speed,wind speed and wind direction on the leakage process,and then simulate the explosion process of FPSO under different water spray positions,and obtain the deflagration pressure value under the action of water mist in the dense area of equipment Less reduction.In addition,different conditions of water mist particle size are simulated,and the results show that with the decrease of water mist particle size,the explosion suppression effect is enhanced. |
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