The corrosion under insulation dominates metal loss in the case of API （American Petroleum Institute） 5L Grade B geothermal pipeline, whereas, the other possible corrosion causes, such as stress corrosion and therma...The corrosion under insulation dominates metal loss in the case of API （American Petroleum Institute） 5L Grade B geothermal pipeline, whereas, the other possible corrosion causes, such as stress corrosion and thermal cracking, did not serve a role as critical factors regarding to pipeline degradation during 26-years working operation. Actually, the header pipe diameter 32 inches and 40 inches require priority for inspection due to higher corrosion rate compared to smaller pipe diameters. By simulation method on similar heavy duty service condition in which the working pressure of 15 bars and temperature of 183 ℃, it was proved that corrosion rate will severely occur at corrosion rate more than 10 mpy in the pipe diameters of 20 inches, 32 inches and 40 inches. Further,condensation factor may contribute more significant in the case of corrosion under insulation. Practically, the metal loss at a half initial thickness requires priority for inspection, intensive maintenance or possible partial replacement.展开更多
Although organic electrode materials have merits of abundant resources,diverse structures and environmental friendliness,their performance for electrochemical energy storage is far insufficient.In this work,a thiourea...Although organic electrode materials have merits of abundant resources,diverse structures and environmental friendliness,their performance for electrochemical energy storage is far insufficient.In this work,a thiourea-based polyimide/reduced graphene oxide(PNTCSA/RGO)composite was synthesized via a condensation polymerization method.As a cathode material in lithium-ion batteries,excellent performance is demonstrated with high reversible capacity(144.2 mA h g^−1),high discharge voltage(∼2.5 V),and long cycling life(over 2000 cycles at 500 mA g^−1),which are comparable to those of other well documented in organic electrodes.Encouraging electrochemical performance is also demonstrated for sodium ion batteries(a cycling life of 800 cycles at 500 mA g^−1),while poor performance is delivered in potassium ion batteries.Theoretical studies reveal that the active sites are carbonyl groups for all alkali ions but one inserted alkali metal ion is shared by two carbonyl groups from the two neighbor units.More importantly,K ions have stronger interaction with S atoms than Li/Na ions,which may lead to poor structure reversibility and account for the poor cycling performance.Our findings provide a fundamental understanding of polyimide based polymer electrodes and help to design and develop high performance organic electrode materials for alkali metal ion batteries.展开更多
文摘The corrosion under insulation dominates metal loss in the case of API （American Petroleum Institute） 5L Grade B geothermal pipeline, whereas, the other possible corrosion causes, such as stress corrosion and thermal cracking, did not serve a role as critical factors regarding to pipeline degradation during 26-years working operation. Actually, the header pipe diameter 32 inches and 40 inches require priority for inspection due to higher corrosion rate compared to smaller pipe diameters. By simulation method on similar heavy duty service condition in which the working pressure of 15 bars and temperature of 183 ℃, it was proved that corrosion rate will severely occur at corrosion rate more than 10 mpy in the pipe diameters of 20 inches, 32 inches and 40 inches. Further,condensation factor may contribute more significant in the case of corrosion under insulation. Practically, the metal loss at a half initial thickness requires priority for inspection, intensive maintenance or possible partial replacement.
基金This work was financially supported by the National Natural Science Foundation of China(51672188 and 21703036).
文摘Although organic electrode materials have merits of abundant resources,diverse structures and environmental friendliness,their performance for electrochemical energy storage is far insufficient.In this work,a thiourea-based polyimide/reduced graphene oxide(PNTCSA/RGO)composite was synthesized via a condensation polymerization method.As a cathode material in lithium-ion batteries,excellent performance is demonstrated with high reversible capacity(144.2 mA h g^−1),high discharge voltage(∼2.5 V),and long cycling life(over 2000 cycles at 500 mA g^−1),which are comparable to those of other well documented in organic electrodes.Encouraging electrochemical performance is also demonstrated for sodium ion batteries(a cycling life of 800 cycles at 500 mA g^−1),while poor performance is delivered in potassium ion batteries.Theoretical studies reveal that the active sites are carbonyl groups for all alkali ions but one inserted alkali metal ion is shared by two carbonyl groups from the two neighbor units.More importantly,K ions have stronger interaction with S atoms than Li/Na ions,which may lead to poor structure reversibility and account for the poor cycling performance.Our findings provide a fundamental understanding of polyimide based polymer electrodes and help to design and develop high performance organic electrode materials for alkali metal ion batteries.
