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Sui R.,Shandong University | Sui R.,Engineering and Technology Research Center for Special Equipment Safety of Shandong Province | Sui R.,Shandong Agriculture and Engineering College | Wang W.,Shandong University | And 5 more authors.
Engineering Failure Analysis | Year: 2014

Leakage at the tube-to-tubesheet joints occurred in a waste heat boiler. The mode and the root cause of the failure were investigated by chemical composition analysis of the tube material, metallographic structure and crack observation, and corrosion product analysis of the damaged tubes, as well as the operation condition examination of the waste heat boiler. Results revealed that failure of the tubes occurred due to the stress corrosion cracking (SCC), which was caused by tensile stress and chloride-buildup in the narrow and long gap between the tube and tubesheet hole. The gap formation was further analyzed by comparison of the minimum expansion pressure from the common formula provided by the manufacturer, with that from finite element method computations. It is found that the minimum expansion pressure used in manufacture is small and cannot eliminate the initial gap. Meanwhile, the enrichment of chloride in the gap was briefly discussed. © 2014 Elsevier Ltd. Source


Yu F.-H.,Shandong Hualu Hengsheng Chemical Co. | Wang X.-W.,De Zhou Vocational and Technical College | Cui L.-F.,Shandong Hualu Hengsheng Chemical Co. | Cui L.-F.,Tianjin University | And 2 more authors.
Huaxue Gongcheng/Chemical Engineering (China) | Year: 2014

By using Benson group contribution method, the standard enthalpy of formation, standard entropy and isobaric molar heat capacity of aldol condensation reaction by saturated fatty acid or ester and formaldehyde to form α,β-unsaturated fatty acid or ester with more than a carbon were estimated. The thermodynamic properties of the reaction system were calculated. The direction and limit of the reaction were analyzed. The influence of temperature on the thermodynamic properties was investigated. The thermodynamic data changing with molecular structure of the products were compared. The results show that the reaction generating the products with general formula CH2=CR1COOH involved herein is an spontaneous exothermic reaction ranged from 498 K to 698 K. Compared with the alkanes substituent, the degree of spontaneous exothermic reaction is smaller when R1 is H. The influence of the carbon chain growth of R1 alkanes on the thermodynamic properties of aldol condensation reaction can be ignored. For the reaction of generating the products with general formula CH2=CHCOOR2, the reaction heat and extent decline with the carbon atoms connected with oxygen changing from -CH3 and -CH2 to -CH. Source


Yang D.-H.,Tianjin University | Yang D.-H.,Shandong Hualu Hengsheng Chemical Co. | Cui L.-F.,Shandong Hualu Hengsheng Chemical Co. | Chen Q.-Z.,Shandong Hualu Hengsheng Chemical Co. | Li X.-G.,Tianjin University
Huaxue Gongcheng/Chemical Engineering (China) | Year: 2016

Dialdehyde starch-Schiff base cobalt (II) complex was synthesized, and its structure was characterized by FT-IR and UV-vis. The complex was tested as a catalyst for epoxidation of cyclohexene in acetonitrile when H2O2 and isobutylaldehyde were used as oxidant, oxidant promoter. The influence of reaction parameters, such as amount of catalyst, temperature and material ratio on epoxidation was investigated. The results show that under the best condition for the preparation of the epoxidation hexamethylene of catalyst 20 mg, n(H2O2)∶n(cyclohexene)=2∶1, n(isobutylaldehyde)∶n(cyclohexene) =2∶1, 60 ℃, 6 h, the conversion of cyclohexene is 53.8%, and the selectivity of epoxycyclohexane is 61.2%. © 2016, Editorial Office of "CHEMICAL ENGINEERING" (CHINA). All right reserved. Source


Yang D.-H.,Tianjin University | Yang D.-H.,Shandong Hualu Hengsheng Chemical Co. | Cui L.-F.,Shandong Hualu Hengsheng Chemical Co. | Chen Q.-Z.,Shandong Hualu Hengsheng Chemical Co. | Li X.-G.,Tianjin University
Huaxue Gongcheng/Chemical Engineering (China) | Year: 2015

Under the conditions of excluding of mass transfer resistance, with dialdehyde starch Schiff base cobalt complex as catalyst, the kinetics of selective catalytic oxidation of cyclohexene to cyclohexenone with oxygen in the gas-liquid-solid system was systematically studied. The results show that the effects of stirring speed and temperature on the reaction process are significant. When the stirring speed was 400 r/min, the influence of the mass transfer resistance could be effectively eliminated; as the temperature increased, the reaction rate was accelerated. The reaction order of cyclohexene was 1. Based on Arrhenius equation, activation energy 28.29 kJ/mol and pre-exponential factor 2 689.47 min-1 were obtained. The kinetic equation of selective catalytic oxidation of cyclohexene to cyclohexenone was given. It was proved that the equation could be used to describe the kinetics of selective catalytic oxidation of cyclohexene to cyclohexenone. © 2015, Editorial Office of "CHEMICAL ENGINEERING" (China). All right reserved. Source

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