The problem of hydrate blockage of pipelines in offshore production is becoming ever-increasing severe because oil fields in ever-increasing unusual environments have been brought in production.HCFC-141b and THF were ...The problem of hydrate blockage of pipelines in offshore production is becoming ever-increasing severe because oil fields in ever-increasing unusual environments have been brought in production.HCFC-141b and THF were selected as the substitutes to study the flow assurance of the hydrates in pipelines.There are critical hydrate volume concentrations for these two slurries.Hydrate slurries behave like Bingham fluids and have high agglomerating tendency when the hydrate volume concentrations are larger than the critical ones.Based on rheological behaviors of these two hydrates,a non-dimensional parameter is proposed through studying the driving forces of agglomeration among hydrate particles,which shows the agglomerating probability of hydrate particles in pipeline and can be used to judge the safety of the pipeline.Moreover,a safe model to judge the safely flow hydrate slurries was presented and verified with the experimental data,which demonstrates that the model is effective to judge whether the pipeline can be run safely or not.展开更多
The flow assurance problem of pipelines in offshore production is becoming more and more serious because oil fields in more and more unusual environments have been brought in production.HCFC-141b and THF were selected...The flow assurance problem of pipelines in offshore production is becoming more and more serious because oil fields in more and more unusual environments have been brought in production.HCFC-141b and THF were selected as the substitutes to study the flow behavior and mechanism of hydrate blockage in pipelines on the newly built flow loop,which was a two pass loop consisting of a 42 mm diameter stainless pipe,30 m long.Slurry-like hydrates and slush-like hydrates were observed with the formation of hydrates in pipeline.There are critical hydrate volume concentrations of 37.5% for HCFC-141b hydrate slurry and 50.6% for THF hydrate slurry respectively.The pipeline would be free of hydrate blockage when the hydrate volume concentration was lower than the critical volume concentration; while otherwise the pipeline would be easily blocked.A safe region,which is defined according the critical hydrate volume concentrations,is firstly proposed for hydrate slurry,and it can be used to judge if the pipeline can be run safely or not.展开更多
【目的】评价经鼻高流量吸氧在全麻诱导前行预充氧的有效性及在插管期延长"安全窒息时限"的效果。【方法】随机将80例非困难气道病例纳入全麻面罩组(FM)、全麻面罩复合经鼻高流量吸氧组(FM+HFNCI)、经鼻高流量吸氧组(HFNCI)...【目的】评价经鼻高流量吸氧在全麻诱导前行预充氧的有效性及在插管期延长"安全窒息时限"的效果。【方法】随机将80例非困难气道病例纳入全麻面罩组(FM)、全麻面罩复合经鼻高流量吸氧组(FM+HFNCI)、经鼻高流量吸氧组(HFNCI)以及经鼻高流量吸氧复合鼻咽通气道组(HFNCI+NPA)。麻醉诱导前预充氧阶段,FM及FM+HFNCI组经全麻面罩而HFNCI及HFNCI+NPA组经鼻导管行预充氧;在气管插管期,除FM组外,余患者均接受经鼻高流量氧吹入。记录不同时点血氧分压、血氧饱和度、心率及血压。【结果】预充氧结束时,PaO_2值、SaO_2值在各组间差异无统计学意义(P>0.05)。窒息插管期,PaO_2值在FM组下降明显,而在HFNCI+NPA组上升;FM组ΔPaO_2值最大(均数为-5.4 k Pa),与其余组比较(ΔPaO_2值均数在FM+HFNCI、HFNCI及HFNCI+NPA组分别为-0.5、-0.8、1.4 k Pa)差异有统计学意义(P<0.001)。插管成功时FM、FM+HFNCI、HFNCI、HFNCI+NPA组PaO_2值(均数分别为46.7、48.3、37.7、43.7 k Pa)、SaO_2值(均数分别为99.7%、99.8%、99.4%、99.7%)均远高于各自安全低限值。【结论】HFNCI用于非困难气道病例,麻醉诱导前预充氧有效性高、可能延长"安全窒息时限",提高围插管期安全;为达最佳氧合效果,实施HFNCI时应保证气道通畅。展开更多
文摘The problem of hydrate blockage of pipelines in offshore production is becoming ever-increasing severe because oil fields in ever-increasing unusual environments have been brought in production.HCFC-141b and THF were selected as the substitutes to study the flow assurance of the hydrates in pipelines.There are critical hydrate volume concentrations for these two slurries.Hydrate slurries behave like Bingham fluids and have high agglomerating tendency when the hydrate volume concentrations are larger than the critical ones.Based on rheological behaviors of these two hydrates,a non-dimensional parameter is proposed through studying the driving forces of agglomeration among hydrate particles,which shows the agglomerating probability of hydrate particles in pipeline and can be used to judge the safety of the pipeline.Moreover,a safe model to judge the safely flow hydrate slurries was presented and verified with the experimental data,which demonstrates that the model is effective to judge whether the pipeline can be run safely or not.
文摘The flow assurance problem of pipelines in offshore production is becoming more and more serious because oil fields in more and more unusual environments have been brought in production.HCFC-141b and THF were selected as the substitutes to study the flow behavior and mechanism of hydrate blockage in pipelines on the newly built flow loop,which was a two pass loop consisting of a 42 mm diameter stainless pipe,30 m long.Slurry-like hydrates and slush-like hydrates were observed with the formation of hydrates in pipeline.There are critical hydrate volume concentrations of 37.5% for HCFC-141b hydrate slurry and 50.6% for THF hydrate slurry respectively.The pipeline would be free of hydrate blockage when the hydrate volume concentration was lower than the critical volume concentration; while otherwise the pipeline would be easily blocked.A safe region,which is defined according the critical hydrate volume concentrations,is firstly proposed for hydrate slurry,and it can be used to judge if the pipeline can be run safely or not.
文摘【目的】评价经鼻高流量吸氧在全麻诱导前行预充氧的有效性及在插管期延长"安全窒息时限"的效果。【方法】随机将80例非困难气道病例纳入全麻面罩组(FM)、全麻面罩复合经鼻高流量吸氧组(FM+HFNCI)、经鼻高流量吸氧组(HFNCI)以及经鼻高流量吸氧复合鼻咽通气道组(HFNCI+NPA)。麻醉诱导前预充氧阶段,FM及FM+HFNCI组经全麻面罩而HFNCI及HFNCI+NPA组经鼻导管行预充氧;在气管插管期,除FM组外,余患者均接受经鼻高流量氧吹入。记录不同时点血氧分压、血氧饱和度、心率及血压。【结果】预充氧结束时,PaO_2值、SaO_2值在各组间差异无统计学意义(P>0.05)。窒息插管期,PaO_2值在FM组下降明显,而在HFNCI+NPA组上升;FM组ΔPaO_2值最大(均数为-5.4 k Pa),与其余组比较(ΔPaO_2值均数在FM+HFNCI、HFNCI及HFNCI+NPA组分别为-0.5、-0.8、1.4 k Pa)差异有统计学意义(P<0.001)。插管成功时FM、FM+HFNCI、HFNCI、HFNCI+NPA组PaO_2值(均数分别为46.7、48.3、37.7、43.7 k Pa)、SaO_2值(均数分别为99.7%、99.8%、99.4%、99.7%)均远高于各自安全低限值。【结论】HFNCI用于非困难气道病例,麻醉诱导前预充氧有效性高、可能延长"安全窒息时限",提高围插管期安全;为达最佳氧合效果,实施HFNCI时应保证气道通畅。
