Anti-coking oxide films were prepared on a 25Cr35Ni and 35Cr45Ni alloy surface under the low oxygen partialpressure atmosphere of a H2-H2O mixture. The composition and phase structure of the oxide films were analyzed ...Anti-coking oxide films were prepared on a 25Cr35Ni and 35Cr45Ni alloy surface under the low oxygen partialpressure atmosphere of a H2-H2O mixture. The composition and phase structure of the oxide films were analyzed by energydispersive spectroscopy (EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The anti-cokingperformance of a mini tube made of a HP40 (25Cr35Ni) alloy was evaluated on a bench scale pyrolysis and coking test unit.The results showed that the surface Fe and Ni content decreased after the oxidation of the two alloys in a low oxygen partialpressure atmosphere. The oxide films were mainly composed of MnCr_(2)O_(4) and Cr_(2)O_(3). The average mass of coke in the minitube with oxide film decreased by 87% relative to that of a tube without an oxide film when the cracking temperature was 900℃. The ethylene, propylene, and butadiene yields in the pyrolysis tests were almost the same for the mini tubes withand without an oxide film. The oxide film on the alloy surface effectively inhibited catalytic filamentous coke formation.An industrial test showed that the run length of the cracking furnace with the in-situ coating technology was significantlyextended.展开更多
The oxidation of two phase Cu Cr alloys containing 25% and 50% Cr prepared by powder metallurgy (PM) with a rather uniform two phase microstructure has been studied at 700～900 ℃ under oxygen pressure below the stabi...The oxidation of two phase Cu Cr alloys containing 25% and 50% Cr prepared by powder metallurgy (PM) with a rather uniform two phase microstructure has been studied at 700～900 ℃ under oxygen pressure below the stability of the copper oxides. The two PM alloys oxidized very slowly and formed only external Cr 2O 3 scales rather than undergoing an internal oxidation of chromium. This result is attributed mainly to a supply of chromium from the small Cr rich particles dispersed within the Cu rich phase. The oxidation kinetics of the two PM Cu Cr alloys approximately followed the parabolic rate law. The scaling rates are of the same order as those measured for pure chromium under the same oxygen pressure, but smaller than those for the alloys of similar composition prepared by normal arc melting techniques, whose compositions were largely non uniform. The results are interpreted in terms of the two phase nature of these alloys.展开更多
基金the scientific research project of China Petroleum&Chemical Corporation(Grant No.411048).
文摘Anti-coking oxide films were prepared on a 25Cr35Ni and 35Cr45Ni alloy surface under the low oxygen partialpressure atmosphere of a H2-H2O mixture. The composition and phase structure of the oxide films were analyzed by energydispersive spectroscopy (EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The anti-cokingperformance of a mini tube made of a HP40 (25Cr35Ni) alloy was evaluated on a bench scale pyrolysis and coking test unit.The results showed that the surface Fe and Ni content decreased after the oxidation of the two alloys in a low oxygen partialpressure atmosphere. The oxide films were mainly composed of MnCr_(2)O_(4) and Cr_(2)O_(3). The average mass of coke in the minitube with oxide film decreased by 87% relative to that of a tube without an oxide film when the cracking temperature was 900℃. The ethylene, propylene, and butadiene yields in the pyrolysis tests were almost the same for the mini tubes withand without an oxide film. The oxide film on the alloy surface effectively inhibited catalytic filamentous coke formation.An industrial test showed that the run length of the cracking furnace with the in-situ coating technology was significantlyextended.
文摘The oxidation of two phase Cu Cr alloys containing 25% and 50% Cr prepared by powder metallurgy (PM) with a rather uniform two phase microstructure has been studied at 700～900 ℃ under oxygen pressure below the stability of the copper oxides. The two PM alloys oxidized very slowly and formed only external Cr 2O 3 scales rather than undergoing an internal oxidation of chromium. This result is attributed mainly to a supply of chromium from the small Cr rich particles dispersed within the Cu rich phase. The oxidation kinetics of the two PM Cu Cr alloys approximately followed the parabolic rate law. The scaling rates are of the same order as those measured for pure chromium under the same oxygen pressure, but smaller than those for the alloys of similar composition prepared by normal arc melting techniques, whose compositions were largely non uniform. The results are interpreted in terms of the two phase nature of these alloys.
