共查询到20条相似文献,搜索用时 62 毫秒
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目前对加氢裂化反应过程的整体能量衡算以及反应器大尺度空间放热情况报道较多,但对于反应过程中催化剂体系自身的温度分布情况却讨论极少。本文以真实蜂巢型加氢裂化催化剂三维体相环境为计算实体,以模拟工业运行温度的函数作为边界条件,采用无网格数值方法求解傅里叶传热方程。并使用计算结果分析加氢裂化催化反应过程中外界温度波动对于催化剂内部温度分布的影响。同时使用能谱面扫描的方法分析积炭的蜂巢型催化剂截面,标示截面的碳元素分布,进而对计算获取的催化剂内部温度分布计算进行实验辅证。计算结果表明:实际反应过程中催化剂内部并非等温反应,在加氢裂化反应过程中外界的反应温度以及催化剂内部的几何形态对于催化剂团簇内部的温度场分布有一定的影响作用。催化剂体相内部的平均温度也随着反应体系放热情况、催化剂粒径、原料油密度、反应空速以及催化剂内部热点分布情况的不同而有所变化。 相似文献
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采用共沉淀-水热复合法制备Ni-Mg/Al2O3催化剂,考察焙烧和还原温度对其结构和甲烷化催化性能的影响,通过XRD,H2-TPR,TEM等表征,发现随焙烧温度升高,催化剂中NiAl2O4物相呈增多趋势,至900℃时,催化剂中镍物种完全以NiAl2O4形式存在,催化剂表面积从500℃焙烧的130m2/g降至900℃焙烧的34m2/g.针对600℃焙烧的催化剂,反应活性随还原温度升高呈现先增加后降低的趋势,其最佳还原温度为650℃,这主要是受Ni物种还原度、还原后Ni晶粒尺寸等多重因素影响.通过关联甲烷化性能与催化剂结构发现,NiO与载体之间相互作用适中,还原后表面能够形成较小的镍晶粒,催化剂具有较好的甲烷化活性和稳定性. 相似文献
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根据常用的6种氨合成催化剂的本征活性测定数据,用焦姆金动力学方程回归得到反应速率常数与温度的关系。利用所得反应速率常数,模拟了这6种氨合成催化剂在中型氮肥厂φ1000mm三套管氨合成塔的反应结果。从催化剂的使用温度来看,从A106、A109、A110-1、A110-2、ICI74-1到ZA-5最佳活性使用温度不断降低。 相似文献
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针对常规PID调节无法满足低温水浴电加热反应器控制要求的问题,提出采用PID参数优化、限制输出等方法,最终完成反应器的调试,满足工艺生产要求。 相似文献
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《Journal of the European Ceramic Society》1999,19(3):373-379
Three ceramic magnetic compositions within the CuZnTi ferrite system, having the Curie temperatures centered around 60, 80 and 100°C, respectively, were investigated in order to determine the time-temperature stability of their main magnetic properties. Permeability and the slope of permeability around their Curie points were determined on ring shaped samples, before and after being subjected to long term (over 6000 h) ageing at their Curie temperature and for a shorter time of about 50 h at higher temperatures up to 700°C. Rates of changes of 33, 66 and 100 ppm h−1 of the maximum slopes of permeability were found for the samples aged at 60, 80 and 100°C, respectively. The samples aged at temperatures higher than 200°C show a rather sudden decrease of maximum slope of permeability, but no shift of the Curie temperature and the working point, corresponding to the temperature where the slope has the maximum value. This is the most interesting result as concerns the use of such magnetic temperature sensors for the construction of highly sensitive temperature controllers, for example ultrathermostats. The results are discussed in terms of the migration processes of the cations, especially Cu2+, from metastable positions on which they were frozen during the rapid cooling of the sample from the sintering temperature, to the more stable ones, namely the octahedral sites into the spinel lattice. © 相似文献
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T. Vladimiroff Y. P. Carignan D. S. Chiu A. K. Macpherson 《Propellants, Explosives, Pyrotechnics》1994,19(6):281-285
In the past, real gas effects on the flame temperature were evaluated using the virial equation of state. Usually, the virial expansion was truncated after the third term. In this work the equation of state for dense gases proposed by Haar and Shenker is considered. The implementation developed for H2O, CO, CO2, H2, and N2 by Powell, Wilmot, Haar and Klein is used. The contribution of all minor species is assumed to be approximated by a Lennard-Jones gas with ϵ/k = 100 K and σ = 3.0 Å. It is found that the more conventional approach is valid up to a loading density of 0.2 g/cm3. As density increases real gas effects cause the calculated flame temperature to decrease and the calculated pressure to increase. A computer program to perform the calculations has been devised for a personal computer. 相似文献
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探讨了2CaO-SiO2(C2S)的固相反应热效应的温升测试方法,发现阶跃升温法适合研究类似C2S大吸热小放热固相反应自放热引起的温升。通过观察阶跃升温法中C2S形成过程中的温度变化,看到在1250℃下不同尺寸的试样内部温升不同,尺寸越大,试样内部的温度越高,φ16 mm试样的温升达到92℃;同时C2S固相反应的速率提高1.6倍,转化率提高1.4倍。 相似文献
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温度对温敏性固定化酶的相对活力影响研究 总被引:1,自引:0,他引:1
以N 异丙基丙烯酰胺 (PNIPAM)均聚凝胶和N 异丙基丙烯酰胺与丙烯酰胺 [P(NIPAM -AM) ]共聚凝胶为载体制备了四种温敏性固定化酶。其相对活力 (f)随温度的升高而降低 ,在凝胶低临界溶解温度LCST(32 0℃ )附近骤降 (均聚枯草杆菌蛋白酶的f在 32 0℃前后由 86 2 %降至 18 8% ) ,即高温下 (LCST以上 )酶从凝胶中释放出来 ,说明温敏性凝胶可用作生物固定化催化剂的功能性载体。 相似文献