A gas-solid circulating fluidized bed heat exchanger is designed and built to investigate the particle collision behavior and heat transfer performance under different operating parameters, such as air flow rate, heat flux, and particle type. Air, Polyoxymethylene (POM) and three sizes of glass beads (GB) are selected as working media. Time-domain and frequency-domain analyses are conducted for the collision acceleration signals. The results show that adding solid particles can enhance heat transfer and increase pressure drop of system. The heat transfer enhancing factor reaches up to 33.4%, and the maximum pressure drop ratio is no more than 15.7%. The frequency distribution range of pure gas phase collisions is 0-1000 Hz, and the solid phase plays a dominant role in the collision of gas-solid two-phase flow, distributed between 2000 and 25,000 Hz. The signal power increases with the increase in air flow rate. The heat transfer enhancing factor of POM particles decreases with the increase in air flow rate, but those of GB particles first increases and then decreases. The signal power of POM particles is generally greater than those of GB particles. The heat transfer enhancing factor of POM particles is obviously higher than those of GB particles, especially at low air flow rate. The pressure drop ratio fluctuates with the increase in air flow rate, and generally increases with the increase in heat flux. The drop ratio of the POM particles is higher than those of the GB particles.
In response to the problem that the conventional concentrated sulfuric acid catalyst for esterification reactions are prone to corrosion and generate large amounts of acid-containing wastewater, highly efficient gel resin-loaded ionic liquid solid acid (SA-ILs) catalysts were prepared by a one-pot method of loading ionic liquids onto gel resins. It is shown that the gel resin carrier has a strong water-absorbing structure, and the ionic liquids are covalently loaded on the gel resin carrier through chemical bonding, leading to SA-ILs catalysts with excellent acidity and good structural stability. With an optimal ionic liquid loading of 11
The Ce-modified OMS-2 catalyst (Cex-OMS-2) was synthesized by the hydrothermal synthesis method, after which its catalytic efficacy in the selective reduction of NO by CO was assessed. The experiments showed that Ce0.08-OMS-2 was capable of 100% NO conversion between 175 and 300 degrees C when 0.05%NO, 0.1%CO, 5%O2 and N2 were used as equilibrium gases, and the N2 selectivity peaked at 93.2% at 175 degrees C. Additionally, Ce0.08-OMS-2 exhibits good sulfur resistance in the presence of 0.02% SO2 and maintains more than 88% NO conversion at 175-275 degrees C. By using BET, XPS, H2-TPR, NH3-TPD, and In situ DRIFTS to characterize the catalysts, the effects of doping the active metal Ce on the physicochemical characteristics of OMS-2 catalysts were under investigation. In conclusion, the improvement of the low-temperature activity of the Cex-OMS-2 catalyst is facilitated by lower agglomeration and crystallinity, larger specific surface area, smaller average pore size, enhanced surface oxygen vacancies, increased Mn4+ concentration, and richer Bronsted acid. Reaction gas adsorbed species and intermediates on the catalyst surface were dynamically captured during In situ DRIFTS experiments. The CO-SCR reaction of the catalyst was found to follow the E-R mechanism below 200 degrees C and the L-H mechanism at 200-350 degrees C.
The particle collision behavior and heat transfer performance are investigated to reveal the heat transfer enhancement and fouling prevention mechanism in a Na2SO4 circulating fluidized bed evaporator. The particle collision signals are analyzed with standard deviation by varying the amount of added particles epsilon (1%-3%), circulation flow velocity u (0.37-1.78 m.s(-1)), and heat flux q (7.29-12.14 kW.m(-2)). The results show that the enhancement factor reach up to 14.6% by adding polytetrafluoroethylene particles at epsilon = 3%, u = 1.78 m.s(-1), and q = 7.29 kW.m(-2). Both the standard deviation of the particle collision signal and enhancement factor increase with the increase in the amount of added particles. The standard deviation increases with the increase in circulation flow velocity; however, the enhancement factor initially decreases and then increases. The standard deviation slightly decreases with the increase in heat flux at low circulation flow velocity, but initially increases and then decreases at high circulation flow velocity. The enhancement factor decreases with the increase in heat flux. The enhancement factor in Na2SO4 solution is superior to that in water at high amount of added particles. The empirical correlation for heat transfer is established, and the model results agree well with the experimental data. (C) 2021 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights reserved.
采用简单的一步水热法制备了硅烷偶联剂功能化氧化石墨烯(KGO),并将其与环氧树脂复合,制备了一种高性能的防腐涂料.采用傅里叶变换红外光谱、拉曼光谱、扫描电子显微镜和X射线衍射分析对KGO的各项性能及微观形貌进行了表征.随后通过电化学阻抗谱(EIS)和盐雾试验对添加了质量分数为0.1％、0.2％和0.3％的环氧树脂复合涂料的耐腐蚀性能进行表征.结果表明,KGO显著提高了环氧树脂复合涂层的屏蔽性能和耐腐蚀性能.环氧树脂复合涂层腐蚀电流密度由8.8×10-8 A·cm-2最低下降到2.0×10-8 A.cm-2.其中,0.2 KGO/EP涂层的低频阻抗模量在浓度为3.5％的NaCl溶液中浸泡72 h后仍维持在较高水平,约高出纯环氧树脂涂层2个数量级.当KGO的添加量为0.2％时,环氧树脂复合涂层具有最优异的耐腐蚀性能.
