During a 70-MPa fueling, the fueling hose breakaway separated. The separation occurred without any extraneous forces other than the pressure of the gas internal to the fueling hose. Upon investigation, it was determined the pull force set point was incorrectly adjusted. No further issues or actions.
A metal hydride storage system was refilled using compressed hydrogen in a closed lab environment. The tank system is an in-house development and is optimized for high hydrogen storage density and use with an air-cooled fuel cell. The system is equipped with a pressure relief valve that opens gradually at 35 bar to protect the tank from overpressure conditions. The tank itself is designed to adsorb 400 g of hydrogen at a pressure less than 15 bar.
For refueling, the secondary pressure on the compressed hydrogen supply container was set to 20 bar and the adsorption of the hydride was started without hydrogen flow limitation. Due to the exothermic nature of the hydride upon recharge, as expected a sharp increase in tank temperature was measured. The tank was uncooled because the view more
A fueler drove away without disconnecting the fueling hose from the vehicle. The breakaway did not open and the receptacle fitting sheared off the vehicle. Subsequent testing of the breakaway showed that the breakaway operated at 210 lbs, which was above the design value of 133 lbs. The hydrogen contained in the hose between the dispenser shutoff valve and the vehicle check valve was released.
Forty-six hydrogen cylinders were accidentally charged with air instead of additional hydrogen during recharging operations at a synthetic liquid fuels laboratory. Cylinders were manifolded in batches of 10 or 12 to the utility compressor outside the laboratory. In normal operations, partly used cylinders containing hydrogen at a pressure of 800-900 psi were recharged to a pressure of 2000-2100 psi. Since the contaminated cylinders contained a highly explosive mixture of about 40% hydrogen and 60% air, it was decided to release the compressed gas to the atmosphere outside the building after grounding the cylinders. Two of the cylinders were successfully discharged, but an explosion occurred while the third cylinder was being discharged. Two chemical engineers were killed by the blast, view more
A safety research laboratory experienced two similar air-actuated ball valve failures in a 6-month period while performing hydrogen release experiments. The hydrogen release system contains a number of air-actuated ball valves which are sequenced by a Programmable Logic Controller (PLC) in order to obtain the desired release parameters. During an experimental release sequence, a PLC valve command failed to open the valve even though the PLC valve position confirm signal indicated the valve had opened. On further investigation, the valve actuator and valve stem were found to be moving correctly, but the valve was not opening. The system was depressurized and purged with nitrogen, and the valve was removed for inspection. Inspection required dismantling the valve, and in both incidents a view more
The hydrogen sensor at a hydrogen fueling station detected a slight leakage from the ground packing of the flow control valve during refueling. The refueling operation was stopped immediately. The leak was stopped by tightening the ground packing sealing screw, but it started leaking again in about a week.
The flow control valve was disassembled and inspected. Dust was found at the ground seal and the packing was distorted. Leakage was believed to be due to the dust invasion and repeated tightening of the sealing screw. The packing had been used for four years and two months without replacement.
The hydrogen fueling dispenser nozzle could not be completely disconnected from the vehicle after refueling. It was finally disconnected after trying several times. The cover of the nozzle interfered with the disconnection operation. No malfunction of the nozzle was found. It can be easily disconnected when it is withdrawn along its axis. Sometimes misalignment occurred due to the weight of the dispenser hose.
A hydrogen reformer furnace at a refinery was shutdown for maintenance to remove and cap the inlet and outlet headers of some radiant tubes that had previously developed hot spots and been isolated by externally pinching them off at the inlet. A decision was made to leave steam in the steam-generating circuit during this maintenance operation to prevent freezing. After maintenance was complete, the startup procedure required the furnace to be first heated up to 350°C (662°F) prior to introducing 4136 kPa (600 psig) steam into the radiant tubes. Just after the 4136 kPa (600 psig) startup steam was introduced into the reformer furnace inlet, the control room alarm journal reported an extreme positive pressure spike at the same time a single loud bang was reported by the operations view more
A hydrogen leak occurred at a plant's hydrogen fill station when a vendor's hydrogen fill truck trailer pulled away after filling and caught an improperly stored hydrogen fill line. The driver of the hydrogen truck trailer did not properly stow the hydrogen fill line after filling and failed to verify that the hydrogen fill line was clear of the trailer prior to departure. As the driver pulled away from the fill station, the hydrogen fill line caught on the trailer and subsequently pulled on the hydrogen fill station's ground storage tubes distribution manifold. The force of this pull bent the plant's hydrogen distribution manifold and hydrogen began leaking from a threaded connection and from the hydrogen fill line. The truck trailer driver reported hearing a view more
Hydrogen and water leakage in the main generator stator cooling water (SCW) equipment forced two separate shutdowns of a nuclear plant in a three-month period. Manufacturer weld defects on the SCW exciter end ring header are the likely cause for the hydrogen leakage.
The first nuclear plant shutdown was initiated in mid-May when an SCW leak internal to the main generator was confirmed. Events that led up to the shutdown decision started three days earlier and included an upward trend in stator coil temperatures. After two days of an elevated temperature trend, an SCW tank high-pressure alarm indicated hydrogen leakage. Per alarm response procedure, the operators vented the tank. Hydrogen leakage was determined to have increased from about 300 to 1400 ft3/day with stator water view more