CR—244氯丁胶乳闪蒸脱挥

介绍了管式薄膜蒸汽闪蒸脱挥装置的结构及特点，通过管式薄膜蒸汽闪蒸脱挥中试，对温度，真空度，水蒸气，胶乳中氯丁残留量等影响CR－244氯丁胶乳脱挥的因素进行了试验，着重考察了水蒸气在传热，传质中的作用，结果表明，管式薄膜蒸汽闪蒸脱挥装置操作条件温和，适用于机械稳定性差的胶乳脱挥，适宜的脱挥温度为55－60℃，压力15－25kPa，蒸汽流量增加，可强化传热传质过程，有利于实现闪蒸。     

聚合物高效脱挥技术进展

聚合物中挥发分含量的不同导致聚合物脱挥过程遵循不同的热质传递机理，基于脱挥过程关键机制开发高能效的聚合物脱挥技术与装备具有重要工程意义。本文分别简述了闪蒸脱挥、起泡脱挥以及扩散脱挥3种脱挥方式的传递机理、过程特征以及过程模型，在此基础上从脱挥工艺和装备两个方面综述了近年来聚合物脱挥过程强化的手段与方法，并系统介绍了栅缝降膜脱挥、超重力旋转强化脱挥、超临界流体辅助脱挥、超声空化强化脱挥等过程强化新技术及其应用现状，提出了未来聚合物脱挥理论与工程实践的研究方向：一方面仍需深入研究扩散脱挥与起泡脱挥的耦合作用机制，建立精准、普适的脱挥过程模型；另一方面指出立式降膜脱挥技术因其能效优势，有望成为未来大规模工业脱挥器的重要选择。     

超临界流体增强聚酯薄膜中的质量传递

聚合物中杂质/挥分的存在对聚合物的终端使用将产生负面影响,因此必须将其除去.传统的脱挥方法效率有限,使用超临界流体技术可增强脱挥效率.测定了温度为343 K、压力为30 MPa、CO₂流量为4.0 L•min^-1条件下,PET聚酯薄膜中的乙二醇单体挥分含量与时间的关系,以研究聚合物系超临界流体脱挥过程中的质量传递规律;根据传质理论建立了一个理想的超临界流体脱挥过程的质量传递模型,并用该模型分析处理实验数据,结果表明该模型较好地反映了聚合物系超临界流体脱挥过程的基本特征.     

聚合物系超临界流体脱挥研究进展

综述了聚合物系超临界流体脱挥（SFDV）中的相平衡和质量传递研究进展,分析、总结了超临界流体（SCF）对聚合物的溶胀、温度、压力及SCF流速等因素对脱挥过程的影响。     

聚合物系脱挥研究进展

综述了聚合物系脱挥中脱挥表征方法、影响因素基本规律、脱挥基本理论和超泡脱挥动力学及脱挥设备等方面的研究现状,指出了今后可能的发展趋势。     

乙丙橡胶湿法脱挥工艺研究

采用乙丙橡胶(J-2070)胶液进行了凝聚、挤出脱挥的实验研究。采用改造后的喷嘴结构及合理的加料方式,有效地提高了胶液凝聚过程中的脱挥效率。采用改造后的Ⅱ型模头,进行乙丙橡胶水凝聚样品的挤出脱挥实验,实验结果表明:在挤出机模头压力3.6 MPa机头温度为154℃时,挤出样品的w(总挥发分)0.5%;在挤出机转速为50~120 r/min的范围内,挤出样品不发生降解,说明该脱挥工艺可行,满足乙丙橡胶脱挥的要求。     

板缝聚合物脱挥作用

P.L.Maffettone 和 G.Astarita 等研究者对最近(1990年)研制的一种新的静态聚合物脱挥技术进行脱挥的过程(这种新脱挥技术是这样的:让聚合物溶液在装配成互相垂直的平板群的壁缝中流过而脱挥.板内设有孔,热油在这些孔内循环流动使板壁保持一个高的温度,平板群置于真空闪蒸室内。)进行了模拟。模型同时考虑了动     

羟基聚硅氧烷在单螺杆挤出机中的脱挥

研究了α,ω-二羟基聚二甲基硅氧烷在单螺杆挤出机中的脱挥,分析了影响脱挥效果的因素。结果表明,温度与真空度是影响脱挥效果的关键参数。温度升高,脱挥效果提高,最佳温度200～220℃;真空度升高,脱挥效果提高,但同时增加了冒料的可能性,适宜的真空度为24～28kPa。得出了实验范围内的挥发分最终质量分数与螺杆转速及进料流量的关联式。     

双螺杆挤出机在高比例溶剂POE脱挥及挤压造粒中的应用

对双螺杆挤出机在聚烯烃弹性体（POE）制备过程中高比例溶剂脱挥及挤压造粒应用进行了介绍,并经过试验平台验证,探索出“可控分布脱挥技术”,通过脱挥过程中各个区段不同的工艺要求,设置不同的工艺温度和螺杆的组合排列,同时通过合理控制各个区段不同的真空要求;最终利用双螺杆挤出机将POE流体中的高比例溶剂（质量分数为75 %的溶剂）脱挥至50~200 ppm;同时,阐述了在脱挥过程中的技术关键点,这对大型双螺杆脱挥机组的设计起到了良好的技术支撑作用。     

PET缩聚过程反应与传质Ⅱ传质规律研究

聚对苯二甲酸乙二醇酯缩聚过程是反应－传质耦合过程，本文利用不同膜厚的静上膜实验考察了ＰＥＴ缩聚过程中传质的影响，分析出实验过程脱挥是泡沫脱挥，建立了泡沫脱挥时的传质速率方程。     

射流流场特性对氯磺化聚乙烯乳液脱挥的影响

针对射流流场特性对氯磺化聚乙烯乳液脱挥的影响开展研究,借助Fluent软件对喷嘴内部流场特性进行数值模拟和分析,同时利用实际实验来研究影响射流流场的主要因素。最终模拟和试验结果表明:在一定范围内,水流射流速度越大,喷嘴入射角度的越大,CSM胶乳受到的剪切越大,最终CSM胶体中低挥发组份含量越低。     

Modeling and experimental studies on single particle coal devolatilization and residual char combustion in fluidized bed

Single particle devolatilization followed by combustion of the residual coal char particle has been analyzed in a batch-fluidized bed. The kinetic scheme with distributed activation energy is used for coal devolatilization while multiple chemical reactions with volume reaction mechanism are considered for residual char combustion. Both the models couple kinetics with heat transfer. Finite Volume Method (FVM) is employed to solve fully transient partial differential equations coupled with reaction kinetics. The devolatilization model is used to predict the devolatilization time along with residual mass and particle temperature, while the combined devolatilization and char combustion model is used to predict the overall mass loss and temperature profile of coal. The computed results are compared with the experimental results of the present authors for combustion of Indian sub-bituminous coal (15% ash) in a fluidized bed combustor as well as with published experimental results for coal with low ash high volatile matter. The effects of various operating parameters like bed temperature, oxygen mole fraction in bulk phase on devolatilization time and burn-out time of coal particle in bubbling fluidized bed have been examined through simulation.     

Ambient-pressure thermogravimetric characterization of four different coals and their chars

Ambient-pressure thermogravimetric characterization of four different coals and their chars was performed to obtain fundamental information on pyrolysis and coal and char reactivity for these materials. Using a Perkin-Elmer TGS-1 thermobalance, weight loss as a function of temperature was systematically determined for each coal heated in helium at 40 and 160 °C/min under various experimental conditions, and for its derived char heated in air over a temperature range of 20 to 1000 °C. The results indicate that the temperature of maximum rate of devolatilization increases with increasing heating rate for all four coals. However, heating rate does not have a significant effect on the ultimate yield of total volatiles upon heating in helium to 1000 °C; furthermore, coupled with previous data⁹ for identical coal samples, this conclusion extends over a wide range of heating rate from 0.7 to 1.5 × 10⁴ °C/s. Using the temperature of maximum rate of devolatilization as an indication of relative reactivity, the devolatilization reactivity differences among the four coals tested that were suggested by this criterion are not large. For combustion in air, the overall coal/char reactivity sequence as determined by comparison of sample ignition temperature is: N. Dakota lignite coal ≈ Montana lignite coal > North Dakota lignite char > III. No. 6 bituminous coal ≈ Pittsburgh Seam bituminous coal > Montana lignite char > III. No. 6 bituminous char > Pittsburgh Seam bituminous char. The reactivity differences are significantly larger than those for devolatilization. The reactivity results obtained suggest that coal type appears to be the most important determinant of coal and char reactivity in air. The weight loss data were fitted to a distributed-activation-energy model for coal pyrolysis; the kinetic parameters so computed are consistent with the view that coal pyrolysis involves numerous parallel first-order organic decomposition reactions.     

Modeling and experimental study on multi-level humidifying of the underfeed circulating spouted bed for flue gas desulfurization

In this study, a detailed model was proposed to simulate the process characteristic of flue gas desulfurization with multi-level humidifying in the underfeed circulating spouted bed (UCSB). The model conducted a steady state one-dimensional model by means of infinitesimal analysis, incorporating with the models of droplet evaporation, shrinking core and sulfur absorption. The trends of moisture, temperature, and sulfur concentration along the axial direction are calculated. The predictions were also compared with the experimental results, and they are in very good agreement. The results indicate: The inlet temperature and jet water flow rate are found to be very important factors to the sulfur removal efficiency. Applying multi-level humidifying, the outlet temperature decreases. As a result, the droplet evaporation gets slower and the sulfur removal efficiency increases. Degressive distribution of jet water is also found beneficial to acquiring higher desulfurization efficiency.     

Heat transfer and kinetics of lignite devolatilization in wire-mesh apparatus

A model of lignite devolatilization in a wire-mesh apparatus is proposed in this paper. The model couples the heat transfer between grid and particle with a multiple-reaction kinetic model. The kinetic parameters are derived from the experiments, in which two Chinese lignites are devolatized. The model predictions of heating-rate and particle-size dependence of particle temperature, devolatilization rate and weight loss are presented. An index is suggested to assess the cumulative effect of heat transfer limitation on devolatilization. The model reveals that under a typical condition (particle size 50 μm, heating rate < 1000°Cs⁻¹), the heat transfer limitation could be negligible. However, with further increasing particle size and heating rate, the heat transfer limitation seems to become somewhat important.     

Devolatilization characteristics of large particles of tyre rubber under combustion conditions

A systematic experimental study has been performed in order to investigate the effect of particle size and temperature on the devolatilization rate of large tyre rubber particles. Cylindrical tyre particles with diameters between 7.5 and 22 mm were devolatilised in a macro-TGA reactor, at temperatures between 490 and 840 °C in an inert atmosphere. The effect of particle size and surrounding temperature on the rate of devolatilization was observed to be significant, i.e. larger particle diameters and lower temperatures increased the devolatilization time. A detailed mathematical model for the devolatilization process including internal and external heat transfer, three parallel independent devolatilization reactions and reaction enthalpy effects has been developed and solved using an implicit finite difference method. Comparison of the model predictions with experimental data, reveals that the devolatilization process of large tyre rubber particles at temperatures above 490 °C can be considered to be controlled mainly by heat transfer and reaction kinetics. The model analysis further shows that exothermic devolatilization reaction enthalpy effects cannot be neglected in the prediction of the intra particle temperature rise. A sensitivity analysis of the model parameters, demonstrates that the specific heat capacity of the virgin fuel and the activation energies of the devolatilization reactions is the most important model parameters in the prediction of devolatilization times of large tyre rubber particles.     

二醋酸纤维素塑料生产中挥发分的脱除与利用

分别研究了二醋酸纤维素塑料水分、增塑剂吸收量及生产过程中螺杆转速、喂料量、螺杆组合对脱挥效率的影响。结果表明，水分作为助脱挥剂，有利于脱挥；增塑剂吸收量高，不利于脱挥；高螺杆转速、低喂料量、排气口前高屏障型螺纹元件均有利于脱挥；挥发分的有效脱除可改善产品通透度和热稳定性；挥发分中60 %以上为邻苯二甲酸二乙酯（DEP）成分；通过设计冷凝系统，实现了挥发分中增塑剂的分离，从而实现了DEP的回收利用。     

Emulsion copolymerization of styrene and butyl acrylate in the presence of a chain transfer agent.: Part 1: Modelling and experimentation of batch and fedbatch processes

This paper deals with the development of a mathematical model for emulsion copolymerization of styrene and butyl acrylate carried out in the presence of n-dodecyl mercaptan as chain transfer agent (CTA). The model consisted of a system of differential algebraic equations in which the population balances are based on a new approach that reduces significantly the number of equations involved and the corresponding computational time. Most of the unknown kinetic and thermodynamic parameters of the model were estimated from experimental measurements using a stochastic optimization method based on a genetic algorithm. The results showed a fairly good agreement between model predictions and experiments. The model was then successfully validated through additional experiments carried out in batch and fedbatch reactors and clearly showed that the model was able to predict the time-evolution of overall conversion, amounts of each residual monomer, number and weight average molecular weights of the resulting copolymers and average diameters of the corresponding latex particles for different operating conditions, mainly CTA concentration and reaction temperature. The model was finally used to investigate and confirm the effects of CTA concentration, previously observed by several authors, on the kinetics of this polymerization process and on the main properties of the resulting macromolecules and latex particles.