To understand the flow field distribution inside the steam distributor, and to compare the distribution effect of the three vertical steam distributor and the three spheres steam distributor, the inside flow field was simulated by Fluent and the effect of density distribution, gas phase distribution and velocity field on steam distribution was analyzed. From the results of numerical simulation, it can be seen that, in the process of steam dryness and flow distribution, three ball steam distributor is better than three vertical distributor. The establishment of a three spherical steam distributor provides a reference for the construction of actual field operations and high temperature and high pressure spherical distributor.

Based on the risk of steam injection boiler, and contingency and uncertainty of each basic events , the triangular fuzzy number was used to show the probability of events, then get the top event probability. Combined with the fault tree analysis and fuzzy mathematics, through the fuzzy operation, the interval value of failure probability of hazards of steam injection boiler was obtained, and the fuzzy importance degree, sequence and main factors were determined. Drawing a fault tree based on various risk factors, using the method of minimal cut sets and Boolean algebra method, the boiler burst pathway tubes were showed, and fuzzy probability causing the accident was arrived. The causes of the accidents were analyzed, and protective measures of the steam injection boiler were proposed.