A new type of FCC feed injection scheme in which the feed is injected downward into the riser to realize a countercurrent contact of feed oil with catalyst particles is put forward. The dispersion of feed spray and flow behaviors of particles in the new type of feed injection scheme are investigated via a large scale cold-riser model. Experimental results show that the proposed scheme provides a better contact of feed oil with catalyst particles. Furthermore, the centerline equations of both the feed main flow and the secondary flow in the riser are given by introducing a density correction coefficient. The momentum-ratio of the secondary flow to the main flow is then obtained and the trajectory of the feed main jets as well as the secondary flow is estimated by the centerline equation. The computed results give a reasonable agreement with the experimental data.

As with all stylish 2D functional materials, tellurene and tellurides possessing excellent physical and chemical properties such as high environmental stability, tunable narrow bandgap, and lower thermal conductivity, have aroused the great interest of the researchers. These properties of such materials also form the basis for relatively newfangled scholarly fields involving advanced topics, especially for broadband photodetectors. Integrating the excellent properties of many 2D materials, tellurene/telluride‐based photodetectors show great flexibility, higher frequency response or faster time response, high signal‐to‐noise ratio, and so on, which make them leading the frontier of photodetector research. To fully understand the excellent properties of tellurene/tellurides and their optoelectronic applications, the recent advances in tellurene/telluride‐based photodetectors are maximally summarized. Benefiting from the solid research in this field, the challenges and opportunities of tellurene/tellurides for future optoelectronic applications are also discussed in this review, which might provide possibilities for the realization of state‐of‐the‐art high‐performance tellurene/telluride‐based devices.

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The helium tracer method is used to investigate the residence time distribution and flow patterns of feed spray in different fluid catalytic cracking feed injection schemes by cold model experiments. The axial Peclet number in the upward and downward oriented feed injection schemes was obtained by fitting the residence time distribution into the one-dimensional axial dispersion model with an open−open boundary condition. Results suggest that the flow pattern of the mixed stream is closer to complete mixing in the initial contact region of spray with catalysts when the nozzles are mounted downward. A flow pattern variation index β is proposed to show the flow patterns in the feed injection schemes quantitatively. It is shown that a larger β is obtained when the feed nozzles are faced downward, meaning that the flow pattern of mixed stream in the feeding zone can develop more quickly from a likely complete mixed flow into a likely plug flow.

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