Analysis of performance of spiral groove dry gas seal considered effects of both real gas and slip flow

doi:10.11949/j.issn.0438-1157.20151358

Abstract

Abstract:

In order to analyze the performance of the spiral groove dry gas seal considered effects of both real gas and slip flow simultaneously, the modified pressure governing equations of the seal based on the narrow groove theory by taking the effective viscosity coefficient instead of the gas dynamic viscosity and the real gas Virial state equation instead of the ideal gas state equation. N₂, H₂, CO₂ were taken as examples. The leakage, the pressure at groove root radius and the opening force of the seal were calculated. Meanwhile, the leakage, the pressure at groove root radius and the opening force under the condition of ideal gas without slip flow, ideal gas with slip flow, real gas without slip flow and real gas with slip flow were compared, respectively. The results showed that the effect of slip flow made the leakage increase, and the pressure at groove root radius and the opening force decrease. The effect of real gas made the leakage, the pressure at groove root radius and opening force of susceptible compressed gas (Z<1) increase whereas the leakage, the pressure at groove root and opening force of non-susceptible compressed gas (Z>1) decrease. With increasing sealed pressure p_o, the effect of slip flow was reduced, while that of the real gas was strengthened. Under the condition of low sealed pressure, the slip flow effect was significant. On the contrary, the real gas effect played a predominant role under the condition of high sealed pressure.

Key words: dry gas seal, spiral groove, slip flow, real gas, spiral narrow groove theory, carbon dioxide

摘要：

为分析考虑实际气体效应和滑移流效应的螺旋槽干气密封性能,通过维里实际气体状态方程代替理想气体状态方程、有效黏性系数代替动力黏度修正窄槽理论螺旋槽干气密封气膜压力控制方程。以氮气(N₂)、氢气(H₂)、二氧化碳(CO₂)为例,分别计算、对比无滑移理想气体、滑移理想气体、无滑移实际气体、滑移实际气体时螺旋槽干气密封的泄漏率、槽根处压力、端面开启力。结果表明:滑移流效应使气体泄漏率增大、槽根处压力和端面开启力降低;实际气体效应使易受压缩气体(压缩因子Z<1)的泄漏率、槽根压力、端面开启力增大,使不易受压缩气体(压缩因子Z>1)泄漏率、槽根压力、端面开启力减小。随着气体压力增大,滑移流效应逐渐减弱,而实际气体效应增强;低压下滑移流效应起主导作用,高压下实际气体效应起主导作用。

关键词: 干气密封, 螺旋槽, 滑移流, 实际气体, 窄槽理论, 二氧化碳

CLC Number:

S277.9
TH136

SONG Pengyun, ZHANG Shuai, XU Hengjie. Analysis of performance of spiral groove dry gas seal considered effects of both real gas and slip flow[J]. CIESC Journal, 2016, 67(4): 1405-1415.

宋鹏云, 张帅, 许恒杰. 同时考虑实际气体效应和滑移流效应螺旋槽干气密封性能分析[J]. 化工学报, 2016, 67(4): 1405-1415.

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