关键词: Eulerian模型, 气固两相流, 超短接触旋流反应器, 混合特性

Abstract: Gas-solid two-phase flow of the quick-contact cyclone reactor was simulated with the Eulerian model, especially the volume fraction of solid in the mixing cavity was researched. The results show that tangential gas admission accelerates the gas speed in the mixing cavity, it has a great impact on shortening gas-solid residence time and ensuring short contact reaction effect. For two mixing cavity structures, the second reactor (tangential intake pipes were fixed at the top of the mixing cavity) has a shorter residence time in the same inlet velocity, it is more likely to achieve the short contact requirement. Solid particles of the first reactor (tangential intake pipes were fixed at the bottom of the mixing cavity) spread outward in the mixing cavity from the bottom of the feed inlet, nearly no particle moves to the centre space, the concentration gradient is obvious, then under the action of the tangential flow, solid spread evenly, tangential flow has a beneficial effect on the spreading of solid. In the second reactor, axial feeding contacts with the tangential flow in the mixing cavity at once, under the action of the tangential flow, solid particles are evenly distributed, enhancing the contact effect of gas-solid two-phase. The flow state of gas-solid in the separation cavity of two different structures has no difference, particles gather on the wall of the reactor because of the centrifugal force, and then flow down around a spiral. In a word, turbulent diffusion of tangential gas admission increase turbulent intensity, it has a great beneficial effect on spreading the catalyst particles effectively, enhancing gas-solid contact effect. Due to tangential gas admission, the second reactor is better to FCC reaction because of the solid particles spreading more evenly. The comparison of the numerical results and the experimental results show that the present model is available to describe the flow pattern in the reactor. This work could offer a base for the structure optimization of the quick-contact reactor and improve its efficiency.

Key words: Eulerian model, gas-solid two-phase flow, quick-contact cyclone reactor, mixing characteristics