Abstract:

To achieve accurate flow measurement of CO₂ in pipeline transportation under carbon capture, utilization, and storage conditions, during which liquid phase is the primary phase in the gas-liquid two-phase CO₂, a flow measurement method using the differential pressure ratio from the contraction and expansion sections of a Venturi tube is proposed for gas-liquid two-phase CO₂ flow based on the over-reading model. Through theoretical analysis and experimental verification, the corresponding law between the differential pressure ratio and the Lockhart-Martinelli (L-M) parameter and the virtual height of the liquid phase is revealed. A model for the iterative calculation of the liquid-gas mass flow ratio is proposed, which can address issues in the classical models and enable accurate liquid and gas phase flow measurement of gas-liquid two-phase CO₂. Under conditions of the pressure in pipeline ranging from 4.9 MPa to 5.2 MPa, temperature changing from 14℃ to 17℃, and liquid-gas mass flow ratio between 8.78 and 28.85, the relative error of total mass flow rate is within ±2.3%, the relative error of liquid phase mass flow rate is within ±2.2% and the relative error of gas phase mass flow rate is within ±6.3%. The results prove that the Venturi flowmeter based on dual differential pressure model provides simple, reliable and economic solution for the flow measurement of gas-liquid two-phase CO₂.

Key words: carbon capture, utilization and storage, carbon dioxide, instrumentation, gas-liquid two-phase flow, Venturi tube

摘要：

为了实现碳捕集、利用与封存条件下CO₂管道输送流量的准确测量，在液相为连续相的CO₂气液两相流工况下，基于虚高模型提出了一种利用文丘里管收缩段和扩张段差压比值的气液两相CO₂流量测量方法。通过理论分析与实验验证，揭示了差压比值与Lockhart-Martinelli（L-M）参数及液相虚高之间的对应规律。针对经典模型存在的问题，提出了一种使用迭代方法计算液气质量流量比的模型，实现了CO₂气液两相流分相流量的准确测量。在管道压力为4.9~5.2 MPa，温度为14~17℃，液气质量流量比在8.78~28.85的条件下，总质量流量测量相对误差优于±2.3%，液相流量相对误差优于±2.2%，气相流量相对误差优于±6.3%。结果表明基于双差压模型的文丘里流量计为气液两相CO₂流量测量提供了一种简单可靠、经济实用的解决方案。

关键词: 碳捕集、利用与封存, 二氧化碳, 仪表, 气液两相流, 文丘里管