A new model of critical gas velocities for liquid accumulations in wet gas pipelines

doi:10.11949/0438-1157.20200393

Abstract

Abstract:

Gas field development often adopts wet gas gathering and transportation schemes. Based on minimum interfacial shear stress criterion and velocity profile in liquid film with flat gas-liquid interface for stratified pipe flow, a new model for predicting the critical gas velocity is developed to find out when liquid accumulations occur in wet gas pipelines. The formula of interfacial shear stress is deduced from combination of liquid-film flow field description with gas momentum equation. After the surface of interfacial shear stress is demonstrated, the critical gas velocity can be easily obtained by derivation of interfacial shear stress with respect to liquid holdup. The new model is compared with other three typical models to evaluate their agreements with experimental critical gas velocities, and shows the best prediction precision.

Key words: wet gas pipeline, stratified flow, minimum interfacial shear stress, liquid accumulation, critical gas velocity

摘要：

气田开发经常采用湿气集输方案。针对湿气输送管道出现的积液问题，基于分层流最小界面剪切应力准则，利用气液平界面分层流液膜区的速度分布规律，建立了求解积液临界气速的新机理模型。由分层流液膜区的流场描述和气相动量方程得到气液界面剪切应力的表达式；利用界面剪切应力函数曲线特性，可以通过界面剪切应力关于持液率求导获得临界气速。以不同文献中收集的临界气速实验数据，对新模型和其他具有代表性的湿气管道积液模型进行验证对比，表明新模型的预测精度要优于其他模型。

关键词: 湿气管道, 分层流, 最小界面剪切应力, 积液, 临界气速

CLC Number:

TE 372

Guohao LI,Daoming DENG,Jing GONG. A new model of critical gas velocities for liquid accumulations in wet gas pipelines[J]. CIESC Journal, 2020, 71(11): 5107-5116.

李国豪,邓道明,宫敬. 湿气管道积液临界气速预测的新模型[J]. 化工学报, 2020, 71(11): 5107-5116.

Figures/Tables 12

Fig.1 Regional schematic diagram for multiple liquid holdup solutions

Fig.2 Schematic diagram of minimum interfacial shear stress

Fig.3 Film distribution of stratified flow in wet gas pipeline

Fig.4 Weight functions φB(?)and φi(?)

Fig.5 Interfacial shear stress τivs holdup Hl and superficial gas velocity usg[Eq.(9)]

Table 1 Air-water experimental parameters in 3″ upwardly inclined pipeline

θ/

（°）

ρ_l/

(kg/m³)

ρ_g/

(kg/m³)

μ_l/

(Pa·s)

u_s_l/

(m/s)

μ_g/

(Pa·s)

Fig.6 Intersection of τifrom Eq.(9) and τ?i from Eq.(10)

Fig.7 Flow chart for calculating critical gas velocity

Table 2 Parameters of liquid accumulation experiments

Ref.	D/mm	θ/(°)	流体	p/MPa	u_s_l/(m/s)	ρ_l/(kg/m³)	ρ_g/(kg/m³)
[9]	76.2	2~30	空气/水	0.1	0.01~0.1	1000	1.18
[27]	50.8	1	空气/水	0.1	0.0015~0.023	1000	1.18
[17]	76.2	2~20	空气/水	0.1	0.001~0.01	1000	1.18
[15]	100	0.5~5	SF6/水；SF6/Exxosal D80	0.34~0.69	0.001	998；812、821	22.6~46.9
[14]	100	1~2	SF6/Exxosal D80	0.71	0.005	829	50.0
[33]	154.9	2	N2/Isopar-L	1.38~2.76	0.0015~0.023	760	1.18
[34]	152.4	1	空气/水	0.1	0.0015~0.023	1000	1.18
[21]	151.5	2	空气/水；空气/ Isopar-L	0.1	0.01~0.05	1000；760	1.18

Fig.8 Comparison of predictions from new model with experimental data Ref.[9,17] studies

Fig.9 Comparison of predicted critical gas velocities from new and other typical models with experimental data

Table 3 Prediction deviations for new and other models

模型	与全部实验数据对比		与模拟高压实验数据对比
模型	平均相对偏差 $ε 1 ˉ$ /%	标准差s/%	平均相对偏差 $ε 1 ˉ$ /%	标准差s/%
新模型	5	16	-1	8
Ref.[19]	4	27	-15	13
Ref.[21]	-11	17	-22	8
Ref.[27]	10	47	5	61

Table 3 Prediction deviations for new and other models

模型	与全部实验数据对比		与模拟高压实验数据对比
模型	平均相对偏差 $ε 1 ˉ$ /%	标准差s/%	平均相对偏差 $ε 1 ˉ$ /%	标准差s/%
新模型	5	16	-1	8
Ref.[19]	4	27	-15	13
Ref.[21]	-11	17	-22	8
Ref.[27]	10	47	5	61

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