Variable-Orifice Pressure Relief Valve for Hydrogen Blowdown Control

The patent applies a movable piston within a cylinder that can dynamically adjust the orifice size. The piston is biased by a spring and moves in response to pressure differentials, transitioning between a first position (restricting flow) and a second position (allowing rapid blowdown). This dynamic adjustment resolves the contradiction by enabling both controlled flame size initially and rapid tank emptying as pressure drops.

The invention changes the flow resistance parameter dynamically through piston movement. At high pressure, the piston is in the first position providing restricted flow for controlled combustion. As pressure drops, the piston moves to the second position increasing the orifice size to maintain adequate mass flow rate and reduce blowdown time. This parameter change resolves the time-flame control contradiction.

The patent introduces a dynamic piston-cylinder mechanism that automatically adjusts orifice size based on pressure differentials. The spring-biased piston moves between two positions, providing restricted flow at high pressure and open flow at low pressure. This dynamic adaptation enhances mass flow control capability while maintaining relatively simple device architecture.

The pressure relief device is self-regulating through the spring-biased piston mechanism. The piston automatically responds to pressure differential changes without external control, transitioning between restricted and open flow states. This self-service capability provides adaptive mass flow control while avoiding complex control systems.

The patent uses a dynamic piston mechanism that adjusts orifice size based on real-time pressure conditions. Initially, the piston restricts flow to control flame size. As tank pressure drops and blowdown progresses, the piston automatically moves to a more open position, increasing the effective orifice size. This enables rapid final blowdown while maintaining safe flame dimensions throughout the process.

The pressure relief device operates in distinct phases: an initial restricted flow phase for controlled flame establishment, followed by a transition phase as pressure drops, and a final rapid blowdown phase. This periodic action pattern allows the system to achieve both flame control and rapid emptying by adapting flow resistance to the current blowdown stage.