基于能量法的裂纹梁振动特性分析

研究了含常开裂纹梁的横向振动,基于断裂力学中的能量法,推导了裂纹梁基于能量分布的连续弯曲及剪切刚度表达式;而后基于矩阵传递法,计算了含裂纹Timoshenko梁的振动特性,分析了裂纹深度及位置等裂纹参数对固有频率衰减的影响,同时将计算结果与有限元软件计算结果进行了比较,验证了该方法的有效性。     

Analytical investigation of elastic period of infilled RC MRF buildings

Fundamental period of vibration, dependent on mass and stiffness structure characteristics, is a key parameter in assessing seismic demand. The period can be evaluated both by means of empirical formulas and modal analysis carried out on a structure numerical model. The presence of external or internal infill elements, usually considered as “non-structural” elements, is generally not taken into account in structural modelling, although these elements can significantly increase the lateral stiffness of a Reinforced Concrete (RC) Moment Resisting Frame (MRF) building leading to a modification in dynamic properties.In this study, results of modal analyses carried out on 3D numerical RC MRF building models are presented, varying structure morphology (height, surface area, ratio between plan dimensions) and infill characteristics. Simplified formulas based on regression analysis of obtained numerical data are presented and discussed. These relationships are also compared with similar literature numerical expressions and empirical data from experimental measurements on existing buildings.     

尾油循环条件下悬浮床加氢产物氮分布的研究

以克拉玛依炼油厂常压渣油为原料,在高压釜中进行悬浮床加氢反应。反应时间为1h,反应温度为440℃,催化剂质量分数为1 000μg/g,尾油循环量分别为0,15.0%,20.0%和25.0%,对反应后产物进行常减压蒸馏,切割馏分为IBP～180℃(汽油),180～360℃(柴油),360～500℃(蜡油)及大于500℃(尾油)。得到的各馏分用非水电位滴定法测定碱性氮含量,用化学发光定氮法测定总氮含量。研究表明:增大尾油循环量使进料中总氮和碱性氮增加,而增加的这部分碱性氮和总氮在反应过程中主要富集到尾油中。产物中的碱性氮和总氮主要集中在蜡油和尾油中,只有10%左右分布到汽油和柴油中,悬浮床加氢汽油和柴油中的碱性氮占馏分氮的质量分数较高,为50%～70%,蜡油、尾油中约为30%。     

复合型加载条件下扁平巴西圆盘应力强度因子计算方法

复合型裂纹的研究具有重要的工程实用价值。使用解析分析与有限元数值分析相结合的方法,对复合型加载条件下扁平巴西圆盘试件的应力强度因子进行了系统的分析。计算结果表明:在一定载荷分布角范围内,可使用分布载荷作用下巴西圆盘应力强度因子的公式去计算扁平巴西圆盘试件的应力强度因子;在断裂力学中圣维南原理依然成立。根据计算结果,推荐在扁平巴西圆盘断裂实验中使用载荷分布角为7.25°的扁平巴西圆盘试件。     

凝液汽提塔在乙烯装置前脱乙烷流程中的应用探讨

在百万吨级前脱乙烷流程的乙烯装置裂解气压缩机工艺系统中进行了凝液汽提工艺的研究。模拟计算了凝液汽提塔在裂解气压缩机第四与五段之间时裂解气压缩、分离和制冷系统的变化情况,考察了该塔塔压的变化对这些系统的影响。研究结果表明,应用凝液汽提塔可降低脱乙烷塔塔底温度13℃以上,减少低压蒸汽消耗量,不会增加乙烯制冷压缩机的功率,但增加裂解气压缩机和丙烯制冷压缩机的功率,使综合能耗有所上升;凝液汽提塔塔压对低压蒸汽消耗量的影响较大,而对裂解气压缩机、丙烯和乙烯制冷压缩机的功率影响较小,当塔压为0．9MPa时,综合能耗最低。当凝液汽提塔被设置在裂解气压缩机第四与五段之间时,不建议在新建前脱乙烷流程的乙烯装置中应用它。     

含缺陷压力管道的失效模式与缺陷评定方法分析

本文介绍了含缺陷压力管道失效模式,分析了三种缺陷失效评定方法,即脆性断裂失效评定、弹塑性断裂失效评定及塑性极限载荷失效评定,其中,以ＮＳＣ准则为基础的塑料极限载荷失效评定方法,使用非常方便,有广泛的适用价值。     

新型水火管锅壳式热水锅炉的改进设计

针对新型水火管锅壳式热水锅炉爆管等问题,介绍了一种改进设计方案,并对运行效果和运行中应注意的问题进行了讨论。     

Exploring N-best solution space for heat integrated hydrogen regeneration network using sequential graph-theoretic approach

To achieve the ever-stringent sustainable goals, this paper aims to synthesize a heat integrated hydrogen regeneration network (HIHRN) using a graph-theoretic-based sequential method. Firstly, the optimal and near-optimal structures for a hydrogen regeneration networks (HRN) are determined using P-graph model with consideration of both impurity and pressure constraints. These networks are then used as inputs in P-HENS software to generate a list of optimal and near-optimal heat exchanger network (HEN) structures. An eight source and sink problem is used to demonstrate the effectiveness of the proposed method. There are 199,677 feasible HIHRN structures identified, while the 6 near-optimal solutions which are within 0.05% tolerance of the optimal network cost (i.e., less than 33.04 M$/y) are presented together with the top four HEN designs that can offer comparable costs (～115,500 $/y). In addition, the impacts of pressure swing adsorber (PSA) pressure drop consideration and minimum temperature difference on the optimal design are also presented.