A unified theory on solid-liquid separation: Filtration, expression, sedimentation, filtration by centrifugal force, and cross flow filtration

Based upon a new conception that the solid compressive pressure on a cake surface is not null, almost of all solid-liquid separation operations have been re-examined. For cake filtration, the phenomenon caused by the solid compressive pressure on a cake surface is discussed for thin cake. New expression and hindered sed-imentation theories are developed by above new conception using Darcy’s equation. Application of the new conception to centrifugal filtration and tangential filtration is also discussed. Above results lead to the conclusion that cake filtration, expression, hindered sedimentation, centrifugal filtration and tangential filtration can be described with a unified theory, and the main difference between the operations is only the boundary condition of cake.     

聚丙烯制真空设备及其应用

概念用聚丙烯制作的真空设备的使用情况，着重介绍真空设备的设计与计算，并对不同的计算公式进行了比较，这们便于了解和掌握聚丙烯真空设备的设计和使用。     

温度对密闭式微波辅助提取二氢杨梅素的影响

以藤茶为原料,水为溶剂,采用密闭式提取罐在微波加速反应系统(MARS5)中提取二氢杨梅素,研究提取温度对二氢杨梅素提取效率的影响。结果表明,在80℃以下,二氢杨梅素的提取率很低,80℃~110℃范围内,随着提取温度的提高,二氢杨梅素的提取率呈上升趋势,在110℃时达到最高。此后,随着提取温度的升高,二氢杨梅素的提取率呈下降趋势。HPLC分析结果表明,二氢杨梅素在高温水相体系发生了分解,在180℃下分解产物又进一步发生分解。所以,在本实验条件下110℃是二氢杨梅素的最佳提取温度。     

MCPVT测定1,3-丁二烯氧化动力学

用小型密闭压力容器实验(MCPVT)分别跟踪测定了1,3-丁二烯在氮气和氧气氛围下温度随时间的变化(T-t)和压力随时间的变化(p-t)。利用p-t曲线构建了1,3-丁二烯初期氧化反应动力学。结果表明,在氮气条件下,即使温度达到388.15 K也未检测到1,3-丁二烯发生化学反应。1,3-丁二烯与氧气在343.15～363.15 K范围内发生了氧化反应,反应器内的压力减小。1,3-丁二烯与氧气的初期氧化反应动力学是二级反应。另外,还考察了氧气过量和1,3-丁二烯过量时两种特殊情况下的假一级氧化反应动力学。探讨了过渡态的热力学参数,计算结果表明,1,3-丁二烯的热氧化是一个有序的分子数减少过程。用气相色谱-质谱联用仪和碘量法分析了氧化反应产物,其产物有呋喃和过氧化物。     

Experimental and theoretical study on H2/CO2 separation by a five-step one-column psa process

An experimental and theoretical study is performed for bulk separation of H₂/CO₂ mixture (70/30 volume %) by PSA process with zeolite 5A, a process widely used commercially in conjunction with the catalytic steam reforming of natural gas or naphtha. For the optimized adsorption conditions of PSA, the characteristics of adsorption/desorption characteristics have been studied through breakthrough and desorption experiments under various conditions. The purge-to-feed ratio is important to the H₂ product purity only at a long adsorption step time. H₂ could be concentrated from 70% in the feed to 99.99% at H₂ recovery of 67.5%. The results of all five steps in PSA are successfully predicted by the LDF model considering an energy balance and nonlinear isotherm. For the model, the effective diffusivities (D,) are obtained separately from the uptake curves of H₂ and CO₂. The Langmuir-Freundlich isotherm is used to correlate the experimental equilibrium data and is very well fitted to the results.     

压力容器环焊缝事故率高的剖析及对策

本文从压力容器设计、制造及标准三方面分析了压力容器环焊缝事故率高的原因,提出了相应的对策。希压力容器有关工程技术人员要充分重视压力容器环焊缝的质量问题,以确保压力容器的安全使用。     

勃劳特换热器的性能

勃劳特换热器的性能周绪美，陈建铭，张鹏远，冯元鼎，丁华（北京化工大学化学工程系）关键词勃劳特换热器；压降１引言在生产过程中，气体与气体之间进行热量交换的换热器，在性能评比时，应该用两项指标来衡量。其一是单位产品所需传热面积要小，其二是单位压降的传热膜...     

邻二甲苯泵用机械密封的失效分析

针对国产化过程中，邻二甲苯泵用机械密封工作时产生的故障，进行了失效分析。为邻二甲苯泵用机械密封的改造提供了依据。     

压力容器与气瓶在材料检验方面异同点的分析

分析了压力容器与气瓶在材料检验方面的异同点，并提出了一些建议。     

Solid circulation characteristics in an internally circulating fluidized bed with orifice-type draft tube

Effects of superficial gas velocities to a draft tube, to an annulus section and particle size on the solid circulation rate (G,) have been determined in an internally circulating fluidized bed (0.28 m I.D. × 2m high) with an orifice type draft tube. The solid circulation rate from the draft tube to an annulus section increases with increasing gas velocities to the draft tube(U _d ) and annulus section (U_a) and consequent increase in pressure drop across the orifice (ΔP_or). However, the values ofG _s decrease by 7–21% with increasing particle size from 86 to 288 μm. The pressure drop across the orifice increases with increasingU _d andU _a . However, ΔP_or decreases by 5–23% with increasing particle size. To predictG _s in an internally circulating fluidized bed, a correlation is proposed as a function of ΔP_or This paper is dedicated to Professor Dong Sup Doh on the occasion of his retirement Korea University.