Topological structures of energy flow: Poynting vector skyrmions

Topological properties of energy flow of light are fundamentally interesting and have rich practical applications in optical manipulations. Here, skyrmion-like structures formed by Poynting vectors are unveiled in the focal region of a pair of counter-propagating cylindrical vector vortex beams in free space. A N\'eel-Bloch-N\'eel skyrmion type transformation of Poynting vectors is observed along the light propagating direction within a volume with subwavelength feature sizes. The corresponding skyrmion type can be determined by the phase singularities of the individual components of the coherently superposed electromagnetic field in the focal region. This work reveals a new family member of optical skyrmions and may introduce novel physical phenomena associated with light scattering and optical force

Simulation and assessment of manufacturing ethylene carbonate from ethylene oxide in multiple process routes

Ethylene oxide (EO) is an important raw material for producing ethylene carbonate (EC). However, the traditional method for the separation of EO from mixture gas by water in the refining process is high energy consumption. In this paper, two processes of manufacturing EC from EO mixture gas were studied by process simulation. Two processes for producing EC from EO mixture as raw materials without EO purification, called the OSAC process and the Modified OSAC process, were developed and assessed systematically. Both processes use EC as the absorbent to capture EO, avoiding the separation process of EO from solution. For comparisons, the EC producing process containing EO absorption by water, EO refinement and carbonylation process were also modeled, which was called the ERC process. Three schemes were designed for the EO absorber using EC as absorbent. Compared with the initial absorber scheme, the optimal liquid-vapor ratio is reduced from 1.66 to 1.45 (mass). Moreover, the mass distribution analysis for the three processes were carried out in the form of the material chain. It was found that, compared with the ERC process, the energy consumption of the OSAC and the Modified OSAC process is reduced by 56.89% and 30.03%, respectively. This work will provide helpful information for the industrialization of the OSAC process. (C) 2020 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights reserved