Vortex Flowmeter Low Velocity Measurement via Differential Pressure

The patent combines two measurement methods: vortex shedding detection (for higher flow rates) and differential pressure measurement (for lower flow rates). The differential pressure sensor arrangement measures pressure differences upstream and downstream of the bluff body, enabling accurate measurement at velocities below the conventional vortex shedding limit. This merging of measurement principles eliminates the minimum velocity threshold while maintaining accuracy across the full flow range.

The bluff body serves multiple functions: it generates vortices for vortex shedding measurement at higher velocities and simultaneously creates a measurable pressure differential for low-velocity measurement. The sensor arrangement is designed to detect both vortex-induced pressure variations and steady differential pressure, making the flowmeter universally applicable across all flow conditions without requiring separate measurement systems.

The differential pressure sensor arrangement continuously monitors pressure differences even when vortex shedding is insufficient for reliable measurement. During ramp-up and ramp-down intervals in batch processes, the system maintains measurement capability through differential pressure detection before vortex shedding becomes dominant, ensuring complete flow accounting from the beginning of each batch cycle.

The flowmeter provides continuous measurement across all flow conditions by transitioning between measurement modes. At low velocities during batch process transitions, differential pressure measurement maintains continuous flow accounting. As velocity increases and vortex shedding becomes dominant, the system seamlessly continues measurement without interruption, ensuring unbroken measurement continuity throughout the entire batch process cycle.