|
Green and highly efficient synthesis of PVB using microreactor systems
Kai Wang, Associate Professor, Tsinghua University
Green and highly efficient methods for polyvinyl butyral (PVB) synthesis was proposed based on microreactor technology. The condensation reaction between polyvinyl alcohol (PVA) and n-butanal was successfully implemented at room temperature, allowing the energy costs associated with cooling and mixing of the reactant solutions to be reduced.[1] The microreactor system also allowed the development of a recycling technology for the reuse of HCl, water, and excess n-butanal present in the product solution. In addition, with the aid of a two-step n-butanal feeding method, the developed recycling technology resulted in a 98.7% n-butanal utilization ratio, while the consumption of HCl and water during the reaction process was reduced by 85.6%.[2] These results indicate that our novel process represents a more environmentally friendly approach to the PVB synthesis.
Photochemical Reactor Design: Technological and Safety Aspects
Alex Voronov, Head of R&D, Peschl Ultraviolet GmbH
The photochemical reactors based on Medium Pressure Mercury and Low Pressure Mercury/Amalgam Lamps are well known since decades and widely used in the modern chemical technologies. In many cases UV-initiated reactions are running in a flammable and volatile liquids with a low evaporation temperature. In the presentation the lamp physics, lamp parameters and technique in terms of safety factors are analyzed. It is shown that due to the lamp physics the lamp operation in an industrial photochemical reactor without special measures is connected with certain risks, e.g. an explosion or fire risk. The analysis of the physical reasons of these risks leads to some important conclusions which give a clear way for the reactor configuration and design. Some design solutions with APEX certification are presented and discussed.
Experimatal study of a droplet impact on cold surface
Chang Seok PARK, Ph.D. student, Pusan National University
Experimental study of a droplet impingement on a cold surface has been performed with the aim of visualizing the temporal variation of droplet impact and of observing frost formation and ice adhesion on the surface. The NaCl solution was mainly used and, droplets were formed at a tip of sharp needle by using electrostatic potential. The free falling droplet was impinged on a cold flat surface and visualized using a high-speed camera and LED light. Captured images were used to measure and calculate the falling speed (m/s) before the impingement on the surface. After having impingement on the surface, the droplet has a frost formation and ice adhesion, whereas the droplet in room temperature has a process of rebound, recoil and splash. Depending on the size of the droplet, we observed that the frost formation and ice adhesion was highly dependent upon the critical size of droplet yielding different Weber numbers.
Automated in Situ Measurement of Gas Solubility in Liquids with a Simple Tube-in-Tube Reactor
Jisong Zhang, Assistant Professor, Tsinghua University
Data on the solubilities of gases in liquids are foundational for assessing a variety of multiphase separations and gas-liquid reactions. Taking advantage of the tube-in-tube reactor design built with
semipermeable Teflon AF-2400 tubes, liquids can be rapidly saturated without direct contacting of gas and liquid. The gas solubility can be determined by performing steady-state flux balances of both the gas and liquid flowing into the reactor system. Using this type of reactor, a fully automated strategy has been developed for the rapid in situ measurement of gas solubilities in liquids. The developed strategy enables precise gas solubility measurements within 2-5 min compared with 4-5 h using conventional methods. This technique can be extended to the discrete
multipoint steady-state and continuous ramped-multipoint data acquisition methods. The accuracy of this method has been validated against several gas-liquid systems, showing less than 2% deviation from known values. Finally, this strategy has been extended to measure the temperature dependence of gas solubilities in situ and to estimate the local enthalpy of dissolution across a defined temperature range.
Several typical intensified chemical processes with microflows
Guangsheng Luo, Professor, Tsinghua University
Multiphase microflow technologies in microchemcial systems have shown high promising prospects for the development of green and low-carbon chemical industries by process intensification. In order to intensify chemical processes with microflows, we developed new microdevices and realized multiphase microflows in several microchannel devices. The mass transfer performances of multiphase microflows have been determined. The applications of multiphase microflows in separation, chemical reaction, and nanoparticle preparation have been carried out. In this presentation, some new development and applications of multiphase microflows for the chemical process intensification will be introduced. The Beckmann rearrangement is an example of fast and high exothermal reaction. In the traditional reaction reactor, it must take long time to realize high conversion with hard control ability and safety issue. We found that the process is a mass transfer controlled process, which could be greatly intensified by liquid/liquid or gas/liquid/liquid microflows. A chemical absorption process for CO2 capture is another example. We found that the CO2 capture process with amine as absorbent and TEG as solvent in a microchemical system can reach very high efficiency with low energy consumption and very small device.
Investigation of the Effect of Processing Parameters and Materials on 3D Printed Structures
CHAO ZHU, Postgraduate, University of Manchester
Additive manufacturing shows a rapid development over the last decade and hence FDM printing machines have been improved remarkablely. In this work, the effects of several set parameters on 3D printed samples’ mechanical properties and their printing quality were explored. It seems that the fill density affects samples’ mechanical properties significantly and the variation of maximum load stress and the Young’s modulus changed linearly with increased density. Moreover, the fill pattern affects fibre’s structure and determines the products’ structural properties. The mechanical properties of samples and the printing time were also affected significantly with different layer thicknesses. Samples with different fill patterns showed highly varying properties; e.g. samples with linear fill pattern showed the best tensile properties where samples with “diamond” fill pattern can have a large deformation during tests. Furthermore, the effects of different materials (e.g. PLA, ABS, carbon fibre reinforced PLA/ABS) on the properties 3D printed structures were also observed and the results showed that the samples with carbon fibre reinforced are better in tensile properties than pure polymer. However, they were found to be more brittle in nature. Moreover, the smaples printed from carbon fibre reinforced materials showed a 45-55% increase in tensile properties and a 40-55% increase in Young’s modulus comapted to pure PLA and ABS.
|
