Probability And Risk Of Hydrogen Leakage In Proton Exchange Membrane Fuel Cell Power Station

The vigorous development of hydrogen energy is conducive to optimizing the existing energy structure and achieving green development,which plays an important role in promoting the reform of China’s energy structure,improving air quality and enhancing people’s living standard.Proton Exchange Membrane Fuel Cell(PEMFC)power plant,which uses hydrogen as the main fuel,has received wide attention worldwide for its clean and efficient power generation mode.However,the concentration of hazardous sources and continuous process in hydrogen power plants will cause significant casualties and property damage in case of fire and explosion accidents.In this paper,we investigate the safety of PEMFC power plants based on quantitative risk assessment techniques.According to the four main steps of quantitative risk assessment technique(risk identification,probability analysis,consequence analysis,and risk measurement),the main work of this paper is as follows.(1)By introducing the hazard and operability analysis model,the risk points and accident patterns in the power plant were analyzed,and the causes and consequences of accidents were analyzed separately by dividing the power plant into hydrogen production area,compression and storage area,fuel cell room,and distribution room according to the process flow.Four major types of disaster-causing modes of PEMFC power plant system accidents were identified:1)hydrogen leakage accidents caused by over-temperature and over-pressure in the process;2)safety accidents caused by aging or failure of instruments;3)failure of interlocking protection devices;and 4)corrosion effects of hydrogen on vessels,pipelines and equipment.The main disaster modes in the station are identified.And specific equipment in the system was studied according to its contribution to the risk,in which instrumentation,piping and valve failures are the three main factors leading to the failure of PEMFC stations.(2)On the basis of hazard mechanism identification,the reliability of the PEMFC power plant system was studied using fault tree analysis theory.The relationship between the failure modes of the hydrogen power plant system is identified,the logical structure between the basic events is analyzed,and a new fault tree model is established for the PEMFC power plant system through layer-by-layer analysis.The FTA model developed here is more targeted and complete in terms of failure mode identification,and quantitative reliability analysis is presented by means of logic diagrams.In addition.an importance analysis of the basic events of the failure was conducted on the basis of the accident tree model,and the results of the study showed that the leakage at the connection and the failure of the overpressure protection device were the main causes of the PEMFC power plant.(3)PHAST consequence evaluation software model,studied the influence of uncertainties on the consequences of pressure ves sel and high pressure pipeline fire and explosion accidents.The study shows that:under the same conditions,the consequences of short pipe leakage accident are smaller than orifice leakage;the lower the temperature of gaseous hydrogen storage,the more serious the consequences of fire and explosion;the consequences of accident are larger when the direction of gas leakage faces downward than horizontal direction;the location of pipe break has little effect on the consequences;the consequences of explosion accident increase significantly when the hydrogen leakage in the pipe collides with the crater.The compressor is the most dangerous leakage unit in the station,and the maximum impact distance reaches 131.69m in the most serious accident consequences.(4)Based on the above research,a domino accident probability calculation method was established for hydrogen power plants based on the domino theory,equipment damage probability model and event tree analysis,and the method was used to quantitatively reflect the impact range and occurrence probability of domino accidents in hydrogen power plants by combining the consequences of fire and explosion accidents obtained from actual cases.The results show that the risk of human death is increased by considering the domino effect in the risk analysis of hydrogen power plants,and the risk of accident can be more accurately reflected by considering the domino effect in the risk analysis of hydrogen power plants.