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Experimental investigation of the consequences of release of liquified hydrogen onto and under water
(2022)
Large-scale experiments have been performed to investigate the possible consequences of realistic amounts of liquified hydrogen (LH2) encountering water. The tests were performed at the Test Site Technical Safety of the Bundesanstalt für Materialforschung und –prüfung (BAM) in Horstwalde, Germany.
The experiments aimed at investigating that upon contact with water, the evaporation rate of LH2 can be that high that physical explosions or even rapid phase transitions (RPTs), could occur. RPTs can generate air and underwater blast pressures which could damage adjacent plant or structures (which has been demonstrated when releasing LNG).
The tests were performed in a 10 m x 10 x 1.5 m basin filled with water. LH2 releases with mass flows ranging from approximately 0.25 kg/s to approximately 0.8 kg/s were established releasing directly from a trailer carrying LH2. The LH2 was released through a 46 m long flexible double vacuum insulated transfer line (inner diameter 39 mm). The releases occurred from a height of 50 cm above the water surface pointing downwards, 30 cm under the water surface pointing downwards and 30 cm under the water surface pointing along the water surface. The release system allowed for an initial phase to release flashed LH2 into the air before redirecting the flow towards the water surface for liquid release. A thermocouple inserted near the nozzle is used to indicate the presence of LH2 at the nozzle. The nozzle could be moved up and downwards relative to the water surface and also moved into the water. The release system was purged with helium before starting a release. A mouthpiece at the end of the release line as well as a manually operated valve at the trailer were used to vary the release rate.
The temperature of the water and the air was measured at multiple locations. The temperature of the air was also measured at H2 concentration probe locations. In addition, the temperature in the filling line was measured (1 at the outlet and 1 further down into the filling line). The pressure in the filling line was also measured at 3 locations, one located directly at the outlet. The release rate was determined based on the weight loss rate of the road tanker. To this end the trailer was placed onto load cells. Special blast pressure sensors were used to measure the shock waves generated by the rapid evaporation or other phenomena both in the water and in the air. At several locations the gas concentration development in time was measured. Heat radiation was measured at 3 distances from the point of release. High speed, Infra-Red (IR) cameras and normal cameras were used to record events and to follow the gas cloud behaviour in time. This includes cameras mounted on a drone and an underwater camera. Two weather stations were used to measure wind speed, wind direction, temperature and humidity during all tests performed.
All investigated release configurations resulted in a very chaotic LH2-water mixing zone, causing considerable evaporation and resulting in minor over pressures. The main phenomenon observed was an ignition of the released gas cloud, resulting in significant blast wave overpressures and heat radiation to the surroundings. The ignition occurred in all under-water releases and in about 90 % of the releases above the water surface. The location of the ignition occurred in free air at some distance from the instrumentation and release location.
Large-scale experiments have been performed to investigate the possible consequences of realistic amounts of liquified hydrogen (LH2) encountering water. The experiments aimed at simulating an accidental release of LH2 during especially the fuelling of a ship. For liquified natural gas (LNG) it has been demonstrated that when spilled onto water the evaporation rate can be that high that physical explosions occur which are referred as rapid phase transitions (RPTs). It cannot be excluded that RPTs are also possible in the case of LH2. The tests were performed in a 10 m x 10 m x 1.5 m basin filled with water, at the Test Site Technical Safety of the Bundesanstalt für Materialforschung und –prüfung (BAM) in Horstwalde, Germany within a research cooperation between BAM and Gexcon as part of
the SH2IFT program. LH2 releases were established releasing directly from a trailer carrying LH2 through a long flexible double vacuum insulated transfer line. The releases occurred from a height of 50 cm above and 30 cm under the water surface both pointing downwards and 30 cm under the water surface pointing along the water surface too. The release rate was determined based on the weight loss rate of the road tanker which was placed onto load cells. Special blast pressure sensors were used to measure the shock waves generated by the release processes both in the water and in the air. At several locations the gas concentration was measured. Heat radiation was measured at 3 distances from the point of release. High speed,
Infrared (IR) and normal cameras were used to record events and to follow the gas cloud behaviour in time. This includes cameras mounted on a UAV and underwater cameras. Two weather stations were used to measure wind speed, wind direction, temperature and humidity during all tests performed. All investigated release configurations resulted in a very chaotic LH2-water mixing zone, causing considerable evaporation but only minor over pressures.
The main phenomenon observed was an ignition of the released gas cloud, resulting in significant blast wave overpressures and heat radiation to the surroundings. The location of the ignition occurred in free air at some distance from the instrumentation and release location.
Large-scale experiments have been performed to investigate the possible consequences of realistic amounts of liquified hydrogen (LH2) encountering water. The experiments aimed at simulating an accidental release of LH2 onto water, for instance during the fuelling of a ship. For liquified natural gas (LNG), it has been demonstrated that physical explosions may occur when it is spilled onto water. These phenomena are referred as rapid phase transitions (RPTs). It cannot be excluded that RPTs are also possible in the case of LH2. The tests were performed at the Test Site Technical Safety of the Bundesanstalt für Materialforschung und –prüfung (BAM) in Horstwalde, Germany. The tests were performed in a 10 m x 10 x 1.5 m basin filled with water. LH2 releases of up to about 1 kg/s were established releasing directly from a trailer carrying LH2. The releases occurred from a height of 50 cm above the water surface pointing downwards, 30 cm under the water surface pointing downwards and 30 cm under the water surface pointed along the water surface. All release configurations resulted in a very chaotic LH2-water mixing zone, causing considerable evaporation and resulting in minor over pressures. No RPTs were observed. The main phenomenon to be observed is, however, an ignition of the released gas cloud resulting in significant blast wave overpressures and heat radiation to the surroundings. The ignition occurred in all under-water releases and in about 90 % of the releases above the water surface.