Evaluation of hydrodynamic behavior of the perforated gas distributor of industrial gas phase polymerization reactor using CFD-PBM coupled model

A 2D computational fluid dynamics (Eulerian–Eulerian) multiphase flow model coupled with a population balance model (CFD-PBM) was implemented to investigate the fluidization structure in terms of entrance region in an industrial-scale gas phase fluidized bed reactor. The simulation results were compared with the industrial data, and good agreement was observed. Two cases including perforated distributor and complete sparger were applied to examine the flow structure through the bed. The parametric sensitivity analysis of time step, number of node, drag coefficient, and specularity coefficient was carried out. It was found that the results were more sensitive to the drag model. The results showed that the entrance configuration has significant effect on the flow structure. While the dead zones are created in both corners of the distributors, the perforated distributor generates more startup bubbles, heterogeneous flow field, and better gas–solid interaction above the entrance region due to jet formation.     

Detection of Multiple Blockages in Parallelized Microreactors

In a plant consisting of parallelized microreactors (MRs), the product quality is lowered because of a lack of flow uniformity among them when blockage occurs. It is not practical to install sensors in every MR from the viewpoint of cost when detecting the blocked MRs. In the previous study, the multiple blockage detection (MBD) method using a small number of sensors was proposed, but its performance became low when the number of sensors decreased. Here, the conventional algorithm for MBD is improved by considering the process behavior on blockage occurrence, and the effectiveness of the improved algorithm is demonstrated through a numerical case study. The effects of flow distributor types and sensor types on the MBD performance are numerically investigated.     

FCC装置主风分布管喷嘴磨损的气相流场分析

用FLUENT流体计算软件对FCC装置再生器树枝状分布管喷嘴流场进行了计算,分析了喷嘴发生磨损的机理.对喷嘴流场的计算表明喷嘴磨损是催化剂颗粒造成的,属于气固两相流冲蚀磨损.由于某些喷嘴的压力降偏低和流场存在偏流,造成催化剂颗粒倒流至喷嘴内部或分布支管内部.催化剂颗粒流经喷嘴时,斜向冲击内壁产生冲蚀磨损.磨损首先发生在喷嘴内壁局部区域,形成圆弧状磨损痕迹,再将喷嘴磨穿,逐渐扩大为整个喷嘴,磨掉喷嘴.这些分析结果可为主风分布管的设计提供帮助.     

油气润滑系统在四切分轧制技术上的应用

本文介绍了油气润滑技术的工作原理及特点，阐述了该系统在四切分轧制技术上的应用与延伸。     

基于可寻址分支分配器的CATV收费系统

给出了一种基于可寻址分支分配器的ＣＡＴＶ收费管理系统设计方案，并着重介绍了系统的工作原理及可寻址分支分配器的设计。     

在65t/h锅炉上应用小型集散控制系统

针对湘钢６５ｔ／ｈ链条钢炉气煤混烧特点，设计了给水、燃烧、汽温调节，应用美国Ｈｏｎеｙｗеｌｌ９０００系列小型集散控制系统，保证了锅炉安全、经济运行，达到了节能目的。     

PVT Measurements on tetrafluoroethane (R134a) along the vapor-liquid equilibrium boundary between 288 and 373 K and in the liquid state from the triple point to 265 K

For the investigations of the gas-liquid phase equilibria, a new apparatus has been developed capable of simultaneously determining the pressure and the liquid and vapor densities using Archimedes' principle. The relative measurement uncertainties of the liquid and vapor densities of R134a (purity, 99.999%) at 313 K are 2×10^–4 and 7×10^–4, respectively (95% confidence level). For the measurements in the liquid region along nine quasi-isochores at pressures up to 5 MPa, an isochoric apparatus was used. The relative measurement uncertainty ofpv/(RT) is less than 1×10^–3. In addition to the investigation of the (p, v, T) properties, the temperature and pressure at the triple point and the vapor pressure between the triple point and 265 K were measured. On the basis of these data, a vapor pressure correlation has been developed that reproduces the measured vapor pressures within the uncertainty of measurement. The results of our measurements are compared with a fundamental equation for R134a, which is based on the measurements of other research groups.Paper presented at the Twelfth Symposium on Thermophysical Properties, June 19–24, 1994, Boulder, Colorado, U.S.A.     

井下气液混输泵试验台架设计及试验

为了对新研制的井下螺旋轴流式气液混输泵样机进行试验研究,建立了1套气液混输泵试验台架。整个试验台架由泵级部分、吸入部分、排出部分和数据采集部分组成。在给出试验样机基本结构和试验原理的基础上,阐述了样机的试验方法和步骤,通过试验得出样机在设计转速下输送纯水和含气体积分数为40%气液混输工况下的外特性曲线。前期的试验研究验证了新建立的井下气液混输泵试验台架和研制的井下螺旋轴流式气液混输泵样机均满足设计要求,同时也为下一步完善设计和今后样机的试验研究提供了依据。     

叶片式泵内气液两相泡状流的三维数值计算

为研究旋转叶片式泵中的气液两相流动规律及泵性能，本文根据气泡泡状流模型提出了一个两相流三维数值分析方法。该数值计算由两部分的计算迭代完成，第一部分是已知含气率分布的连续相(液相)流场的计算。液相流动方程的三维数值求解采用了流面坐标迭代法。第二部分是已知液相流场后的分散相(气泡)轨迹的计算。气泡运动方程中考虑了流场压力梯度差产生的力、气泡周围液体产生的阻力及由于液相质量产生的惯性力等影响气泡运动的因素。通过对气泡运动方程进行数值求解，可得到泵内的含气率分布。再将两部分的计算进行反复迭代，最终得到收敛解。本文将该三维两相流数值计算方法用于多级螺旋轴流式增压泵叶轮的计算、设计。计算结果表明：从叶轮回转面上看，气泡运动转轨并不明显地偏离液相流线。然而从叶轮子午面上看，几乎所有的气泡，不论其初始位置如何，它们最终都移向轮毂表面。该三维两相流数值计算以其简单实用的特点，有望成为工程中气液两相增压泵的一种有效设计工具。     

Improvement of Air-Distributing System of the Pneumatic Impact Machines for Trenchless Technologies

The process of actuation is considered for the inertial element in the improved air-distributing system of pneumatic puncher whose dimensionless parameters are determined.