Objective  In order to reduce the dangerous consequences caused by carbonyl chloride leakage during TDI production, a computational fluid dynamics (CFD) model of production leakage accident in a TDI chemical plant was established.

  Methods  The effect of both wind speed and leak rate on the three-dimensional damaging range of threshold concentration and lethal concentration was analyzed, and its result data was used to fit the fast estimation formula of damage space of threshold concentration cloud under the combined influence of these two factors.

  Results  The simulation results showed that the harmful range of threshold concentration and the lethal concentration cloud decreased with the increase of the wind speed. The harmful range of threshold concentration cloud decreased by half with wind speed increasing from 1.5 m/s to 4.5 m/s. The damaging length of threshold concentration cloud was much greater than the width and height. Under the most unfavorable conditions, the damaging length of the threshold concentration cloud just may reach the position of the downwind protection distance of 1 000, 1 500 and 2 000 m when the leak rate was 0.018, 0.031 and 0.045 kg/s, respectively. With the increase of leakage rate, both the damaging range of threshold concentration and the lethal concentration cloud could increased in way of linear growth. For a leakage accident of usually normal scale, the lethal concentration cloud would not harm outside the plant.

  Conclusion  Exploring the three-dimensional damaging space can provide theoretical and data support for the emergency rescue of carbonyl chloride leakage accidents.