(四川大学 化工学院, 四川 成都 610065)
The Reliability of Static Pressure Measurement With An Inertial Gas Gap Between Transducer and Viscous Slurries
本文已被:浏览 1308次   下载 1
中文摘要: 针对所提出的气柱隔离式静压测量方法用于在线检测粘稠、强腐蚀料浆流动体系密度和液位的可靠性问题,依据热力学和流体静力学原理导出了测量管内气液界面高度随系统温度、压力变化的关系式。以水-空气体系为例计算了160 ℃、0.7 MPa范围内测量管内气液界面的涨落,获得了测量管可靠的工作范围及气柱溢出、测量失效的判定公式。进一步分析了气体通过气液界面扩散传质可能引起的测量失效问题,建立了传质模型,计算表明难溶性气-液体系过程十分缓慢。选用空气-水体系进行了实验验证,在压力0.2 MPa、温度分别为50 ℃和80 ℃两工况下,测量管内通过气液界面传质而引起的界面高度变化量在90 d内小于5%,与理论预测值相当吻合,验证了该方法的可靠性。
中文关键词: 粘稠料浆  气柱隔离  静压测量  可靠性
Abstract:Based on the principles of thermodynamics and hydromechanics, an equation was deduced to predict the vertical position of the interface formed by an inertial gas gap, by which the static pressure transducer is protected from contacting with viscous and corrosive slurries inside a special tube for on-line measurement of the density and level of liquid surface for the flowing system. The interface fluctuation due to the change of temperature and pressure inside the measuring tube was calculated for water and air system within the range of 160 ℃ and 0.7 MPa. An analytic criterion for gas escape which eventually leads to invalidation of measurement was obtained. Furthermore a mass transfer model was proposed to analyze the negative effect of mass transfer of gas molecules through the interface to the flowing liquid, which may cause invalidation of measurement if the majority of gas loses from the measuring tube. It was demonstrated by the calculation that this process of mass transfer is very slow for the slightly dissolved gas liquid system. Taking air water as an trial system, the experiments were made to verify the model. Under a constant pressure of 0.2 MPa and the temperature of 50 ℃ and 80 ℃ respectively, the change of interface position inside the measuring tube due to mass transfer was less than 5% during a period of 90 days, well consistent with the model prediction. It was indicated that the method was fitted well with the engineering requirement for reliable application.
文章编号:20060413     中图分类号:    文献标志码:
.The Reliability of Static Pressure Measurement With An Inertial Gas Gap Between Transducer and Viscous Slurries[J].Advanced Engineering Sciences,2006,38(4):58-63.