A Wet Gas Metering System Based on the Extended-Throat Venturi Tube

Area of Science:

• * Fluid Dynamics
• * Multiphase Flow Measurement
• * Engineering

Background:

• * Classical Venturi tubes are widely used for wet gas metering.
• * Extended-throat Venturi (ETV) tubes, proposed in 1999, have limited theoretical and experimental investigation.
• * The multiphase flow complexity hinders the establishment of a complete theoretical model for ETVs.

Purpose of the Study:

• * To develop theoretical models for the convergent and throat sections of an ETV.
• * To analytically derive differential pressure gradients and propose flowrate algorithms.
• * To analyze the performance of ETVs in wet gas metering and compare them with classical Venturi tubes.

Main Methods:

• * Development of analytical theoretical models for ETV convergent and throat sections.
• * Derivation of front and rear differential pressure gradients.
• * Proposal and comparison of several flowrate algorithms, identifying the iteration algorithm as optimal.
• * Study of the relationship between differential pressure gradient and flowrate relative error.

Main Results:

• * The iteration algorithm demonstrates superior performance for flowrate calculation in ETVs.
• * ETVs exhibit higher accuracy than classical Venturi tubes in wet gas metering.
• * Gas flowrate error increases with liquid content, while liquid flowrate error decreases.
• * Liquid flowrate relative errors are 2-3 times larger than gas flowrate errors.
• * ETVs allow for more compact designs due to higher throat velocities.

Conclusions:

• * The developed theoretical models and algorithms provide a foundation for ETV application in wet gas metering.
• * ETVs present a more accurate and compact alternative to classical Venturi tubes.
• * Understanding the error dependencies on liquid content is crucial for optimizing ETV performance.