Large-Scale Exploitation of Bimodal Reaction Sequences Including Degradation: Comparison of Jet Loop and Trickle Bed Reactors

Abstract

Product yield optimization in bimodal reaction sequences including degradation has been performed considering three-phase reactors such as the jet loop and trickle bed reactors. The considered reaction network comprises two consecutive homogeneous reaction steps toward intermediates which are converted to the corresponding final products by heterogeneously catalyzed reactions, while the reactant and these intermediates are susceptible to irreversible degradation. In the jet loop reactor, the so-called "homogeneous product" is the main product; hence, the remaining challenge is the reduction of degradation. For the trickle bed reactor, gas−liquid mass phase transfer plays a very pronounced role in its ultimate performance. Higher gas flow rates may be employed in the trickle bed reactor to overcome potential mass-transfer limitations and selectively form the "heterogeneous product". Lower gas flow rates result in a less effective gas dissolution, and product selectivities change toward the homogeneous product, rendering avoiding degradation difficult.

Particle Velocity Distribution and Its Prediction in a 14 m Two-Dimensional Circulating Fluidized Bed Riser

“…As is known, two of the key hydrodynamic parameters, solids holdup (ε s ) and particle velocity ( V p ) for CFB systems, can be used to describe the flow characteristics to better understand heat transfer, mass transfer, and gas–solids contacting efficiency in the CFB reactors. , These two parameters are also the basis for commercial CFB reactor modelling, optimization, and design. From a modelling point of view, proper quantification of ε s and V p is crucial for obtaining good numerical results. , While a large number of papers have quantitatively reported on the hydrodynamics, ,,− few of them deal with ε s and/or V p under HF or HD conditions, especially for the quantitative discretion of V p distribution. , Information of particle velocity can reflect solids resident time, gas–solids interaction, and contacting and mixing behavior . Thus, quantitative studies on V p can be used to estimate the gas–solids conversion which depends on the reaction rate and the residence time in the reactor .…”

Perspective on Overcoming Scale-Up Hurdles for the Reductive Catalytic Fractionation of Lignocellulose Biomass

“…18,19 While bigger wood chips require less safety regulations, they generate other challenges, such as efficient mixing, i.e., obtaining the minimum suspension criteria via stirring in the case of batch reactors 20 or via a jet generated by an ejector, used in jet or venturi loop reactors. 21,22 Larger wood chips could also induce channeling phenomena in flowthrough reactors 23,24 or hinder effective pumping in biomass transport. 25 Nonetheless, the selection of lignocellulose feedstock does not only require consideration in relation to handling, transport, reactor design, and safety but also in relation to the chemical process.…”

“…108 Jet or venturi loop reactors are, for example, interesting alternatives. 21,22 Such reactors consist of a reactor vessel and a recirculation loop. The liquid phase is continuously withdrawn from the reactor vessel, recycled through the loop (typically at very high flow rates), and injected back in the reactor by means of a venturi loop reactor.…”

“…Moreover, working with small biomass particles implies the need for additional precautions in terms of the overall health of the biorefinery personnel and the increased risk of dust explosions. , While bigger wood chips require less safety regulations, they generate other challenges, such as efficient mixing, i.e. , obtaining the minimum suspension criteria via stirring in the case of batch reactors or via a jet generated by an ejector, used in jet or venturi loop reactors. , Larger wood chips could also induce channeling phenomena in flowthrough reactors , or hinder effective pumping in biomass transport …”

“…Additionally, stirring could be complicated by using large, irregularly shaped biomass particles at high biomass loading. , In this aspect, other mixing strategies could provide elegant solutions . Jet or venturi loop reactors are, for example, interesting alternatives. , Such reactors consist of a reactor vessel and a recirculation loop. The liquid phase is continuously withdrawn from the reactor vessel, recycled through the loop (typically at very high flow rates), and injected back in the reactor by means of a venturi loop reactor.…”