Ignition during hydrogen release from high pressure into the atmosphere

Abstract

The first investigations concerned with a problem of hydrogen jet ignition, during outflow from a high-pressure vessel were carried out nearly 40 years ago by Wolanski and Wojcicki. The research resulted from a dramatic accident in the Chorzow Chemical Plant Azoty, where the explosion of a synthesis gas made up of a mixture composed of three moles of hydrogen per mole of nitrogen, at 300 • C and 30 MPa killed four people. Initial investigation had excluded potential external ignition sources and the main aim of the research was to determine the cause of ignition. Hydrogen is currently considered as a potential fuel for various vehicles such as cars, trucks, buses, etc. Crucial safety issues are of potential concern, associated with the storage of hydrogen at a very high pressure. Indeed, the evidence obtained nearly 40 years ago shows that sudden rupture of a highpressure hydrogen storage tank or other component can result in ignition and potentially explosion. The aim of the present research is identification of the conditions under which hydrogen ignition occurs as a result of compression and heating of the air by the shock wave generated by discharge of high-pressure hydrogen. Experiments have been conducted using a facility constructed in the performed to determine critical conditions for occurrence of high-pressure hydrogen ignition. The results show that a critical pressure exists, leading to ignition, which depends mainly on the geometric configuration of the outflow system, such as tube diameter, and on the presence of obstacles.

Experimental and numerical study on spontaneous ignition of hydrogen and hydrogen-methane jets in air

“…One of the possible reasons for this stochastic ignition feature is different membrane breaking process which affects the initial turbulence conditions of the flow. Similar behaviour has already been recorded by several researchers [3,4,6,8,9]. It was also observed that for burst pressures up to 16.0 MPa and 25 mm tube length, ignition did not occur for any investigated diameter.…”

“…The comparison between the present and previously performed works [4,6,9,11,12] for pure hydrogen flow ignition is presented in Fig. 10.…”

“…Then the reaction zone is being stretched and propagates along the mixing zone. In this case Comparison between present and referenced works [4,6,9,11,12]. i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y 3 9 ( 2 0 1 4 ) 2 0 3 8 8 e2 0 3 9 5 the ignition is a result of leading shock only, which increases the temperature of the downstream air.…”

Self-ignition of hydrogen–nitrogen mixtures during high-pressure release into air

“…In recent years one could observe an increased interest in hydrogen technologies and safety issues corresponding to them, including uncontrolled ignition during discharge into the air from high-pressure installations. Latest experimental [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] as well numerical [19][20][21][22][23][24] works focus mainly on the detailed description of the self-ignition mechanism according to different initial and boundary conditions including: extension channel geometry: diameter [4][5][6][7]19], length [5][6][7][8][9][10][11][12][13][14][15][16][17][20][21][22], cross-section shape [7,8,18,23] or obstacle presence in front of the hydrogen stream [18,…”

“…However, the results obtained by the researchers using the same experimental stands but applying different geometrical configurations (i.e. Mogi et al [4,10], Oleszczak and Wolanski [7]) group in particular diagram areas. There could be no clear quantitative conclusion regarding extension tube cross-section shape (rectangular or circular) or tube diameter influence on the selfignition propensity.…”