Investigation on the Behavior of Liquefied Fuel Gases Escaping into the Open Atmosphere. Part 2. Experiments with Liquefied Propane and Butane - Evaluation of Tests - Final Conclusions

摘要

The experiments on the escape of gaseous and liquefied propane and butane were performed outdoors. The escape took place at a height of 0.28 m above the ground in, against and at right angles of the direction in which the wind blows. The emergence mass flow rates were in general between approximately 100 and 300 kg/h, i.e., they were leak rates which could not be ignored or overlooked. The experiments with gaseous propane were evaluated on the basis of the free jet theory and were compared with the results for a circular free jet. The thermal concentration field is critical for the assessment of the maximum ignition distances from the emergence location. It was established that for similar experimental conditions it was possible to assess in a first approximation the maximum ignition distance by the free jet theory even when the wind exercised an effect. The case of dead calm is included in this connection. On assumption of an emergence mass flow rate of 3 kg/min equivalent to 180 kg/h for the maximum leak rate as limiting value we obtained at dead calm for propane an estimated figure of 2.4 m from the emergence location for propane, and 2.7 m for butane. No ignitions at greater distances from the place of emergence of the gaseous liquefied gas under the given experimental conditions need be feared. The results of the emergence experiments with liquefied propane and butane were plotted on graphs and on the basis of the formula postulated by Sutton we formulated an empirical equation for assessing the maximum ignition distance under similar experimental conditions. On employing an emergence mass flow rate of 180 kg/h as critical value for a maximum possible leakage, we found both for propane and butane related to a wind velocity of 1 m/s on emergence in the direction of the wind a maximum ignition distance of approximately 8 m and on emergence against the direction of the wind a maximum ignition distance of approximately 7.5 m. (ERA citation 10:046258)