Big bangs in the gas industry
15 Jan 2000
Twenty years ago, it was thought that gas explosions occurred when a flammable gas mixed with air to produce an explosive combination, which exploded when it came into contact with a spark. However, according to Jonathan Puttock of Shell Global Solutions' research centre in Cheshire, the key to explosions is the presence of obstacles such as vessels and pipes.
Puttock explains that a spark will start a flammable mixture burning, but the combustion is quite slow. However, as the flame goes past obstacles, the surrounding gases become more turbulent, which makes the flame burn faster and expand by a factor of about eight. This extra volume pushes the flame forward; moreover, it generates a greater volume of expanding gas which pushes a pressure wave ahead of it. Once pressure reaches a certain critical point, an explosion will occur.
Puttock and his team are involved with developing computer modelling techniques to understand how flames develop, and how to control and avoid explosions. The models are highly complex - a PC workstation can take some 20 hours to simulate the turbulence caused by a flame.
