Multiphase Flow Reactor Research Articles

Development of a Novel Multi-Phase Flow Reactor and Optimization of Mixing Effect Based on a Liquid-Liquid System

Development of a Novel Multi-Phase Flow Reactor and Optimization of Mixing Effect Based on a Liquid-Liquid System

General Approach to Silica-Supported Salens and Salophens and Their Use as Catalysts for the Synthesis of Cyclic Carbonates from Epoxides and Carbon Dioxide.

General routes for the synthesis of silica-immobilized symmetrical and unsymmetrical salophen and salen ligands and metal complexes have been developed starting from the natural product 4-allylanisole (methyl-chavicol and estragole). The key step of the syntheses is a microwave-assisted, platinum oxide catalyzed hydrosilylation of the terminal alkene of 5-allyl-2-hydroxybenzaldehyde to afford a sol-gel precursor which can be immobilized into silica before or after conversion to salen and salophen ligands to afford unsymmetrical and symmetrical silica-supported ligands, respectively. Both the symmetrical and unsymmetrical silica-supported salophens were found to catalyze the formation of cyclic carbonates from epoxides and carbon dioxide with catalytic activities at least comparable to those previously reported for non-immobilized homogeneous salophens. This reaction could also be carried out in a multi-phase flow reactor using ethyl acetate solutions of 3-phenoxypropylene oxide. Metal complexes of the silica-immobilized ligands could be prepared, and the aluminum complexes were also found to catalyze cyclic carbonate formation.

Experimental Study on the Removal of Flue Gas Mercury by Coal Fly Ash under UV Light Conditions

The mercury removal performance of the 150 mesh coal fly ash was evaluated through multiphase flow reactor designed by Shanghai University of Electric Power and different types of fly ash and absorption liquid were analyzed with HYDRA AA. The results showed that UV light almost had no oxidation capacity for gaseous mercury without fly ash, but the removal efficiency was significantly improved from 38.5% to 66.1% in the UV light by adding fly ash into the simulated flue gas. The fly ash after exposure to UV irradiation can improve the removal efficiency of Hg and the capture capacity of oxidized Hg had been greatly enhanced. Most of mercury adsorbed on the surface of fly ash in light conditions was Hg0 (g) and most Hg2+(g) stayed in the simulated flue gas and then was absorbed by absorption liquid.

Experimental Study on the Characteristics of Modified Ca-Based Sorbents and its Mercury Adsorption Capability in the Flue Gas

In this paper, Ca-based sorbent, Ca(OH)2 and CaCO3, was modified with different concentration of KMnO4 and their mercury adsorption capability in the flue gas was experimentally conducted by using a lab-scale multi-phase flow reactor system developed by Shanghai University of Electric Power, and the result showed that the removal efficiency of flue gas mercury of Ca-based sorbent was greatly improved with modification by different concentration of KMnO4, and the removal efficiencies were 80.92%，85.38%，82.35%，83.51% and 89.84% respectively. The removal efficiencies of Ca(OH)2 modified with KMnO4 is increased significantly may be because strong oxidation of KMnO4 made Hg0 convert into oxidized mercury, Hg2 +, which is easier to be removed, as well as, the modification by KMnO4 may change the surface properties of Ca(OH)2 so that it became more active to capture mercury in the flue gas.

Downer reactor: From fundamental study to industrial application

Downer reactor, in which gas and solids move downward co-currently, has unique features such as the plug-flow reactor performance and relatively uniform flow structure compared to other gas–solids fluidized bed reactors, e.g., bubbling bed, turbulent bed and riser. Downer is therefore acknowledged as a novel multiphase flow reactor with great potential in high-severity operated processes, such as the high temperature, ultra-short contact time reactions with the intermediates as the desired products. Typical process developments in industry have directed to (1) the new-generation refinery process for cracking of heavier feedstock to gasoline and light olefins (e.g., propylene) as by-products; and (2) coal pyrolysis in hydrogen plasma which opens up a direct means for producing acetylene, i.e., a new route to synthesize chemicals from a clean coal utilization process. This paper is to give a comprehensive review on the development of fundamental researches on downer reactors as well as the particular industrial demonstrations for the fluid catalytic cracking (FCC) of heavy oils and coal pyrolysis in thermal plasma.

Evaluation of mercury sorbents in a lab-scale multiphase flow reactor, a pilot-scale slipstream reactor and full-scale power plant

Due to its adverse effects on human health and ecosystem, mercury emission from the coal-fired utility boiler has been generating more and more concern. Sorbent injection upstream of the electrostatic precipitator (ESP) or bag-house has been deemed one of the recommended mature technologies to reduce mercury emission. Before a sorbent is used in practice, its mercury capture ability needs to be evaluated, but has until recently only been demonstrated in bench-, pilot- or full-scale experiments separately. In this paper, a lab-scale multiphase flow reactor and a pilot-scale slipstream reactor were set up and conducted such evaluation on the two scales. After that, some kinds of sorbents were injected at a full-scale power station. The experimental results show that the lab- and pilot-scale reactor systems in this paper can provide accurate information of sorbent evaluation under flue gas atmosphere. There was significant difference between the mercury removal efficiency of tested sorbents, varying from 98.3% down to 23%. SO 2 in the flue gas was shown to inhibit mercury oxidization and capture. The sorbents have higher mercury capturing efficiency with higher injection rate and longer residence time when other conditions were held constant. In the pilot-scale, four injection ports vertical to the flue gas flow direction could help improve mixture of sorbent and flue gas so that the mercury removal efficiency became higher. The pilot-scale data can be used to predict the full-scale results. Some of the chemical and physical mechanisms responsible for the mercury removal of the sorbents were identified.

Modelling of Multiphase Flow in a Blast Furnace: Recent Developments and Future Work

An ironmaking blast furnace is a complex multiphase flow reactor involving gas, powder, liquid and solid phases. Understanding the flow behaviour of these phases is of paramount importance to the control and optimization of the process. Mathematical modelling, often coupled with physical modelling, plays an important role in this development. Yagi1) gave a comprehensive review of the early studies in this area in 1993. Significant progress has since been made, partially driven by the needs in research but mainly as a result of the rapid development of computer and computational technologies. This paper reviews these developments, covering the formulation, validation and application of mathematical models for gas–solid, gas–liquid, gas–powder and multiphase flows. The need for further developments is also discussed.

Kinetic Modeling of Hydrodesulfurization of Oil Fractions: Light Cycle Oil

The paper presents a methodology for the kinetic modeling of hydrodesulfurization of oil fractions. Instead of lumping the S components, these are considered individually. To avoid an untractable number of parameters, a structural contribution approach is applied. This implies relating the rate equations of substituted S-containing components to those of the heads of the family. By way of example, hydrodesulfurization of a light cycle oil on a commercial CoMo/Al2O3 catalyst was studied in a completely mixed multiphase flow reactor. The surface reaction between adsorbed reactants and two competitively adsorbed hydrogen atoms was the rate-determining step for both hydrogenolysis on σ sites and hydrogenation on τ sites. Structural contributions were derived for hydrogenolysis and hydrogenation of methyl-substituted benzothiophenes and dibenzothiophenes.

Hydrodesulfurization of 4-Methyldibenzothiophene and 4,6-Dimethyldibenzothiophene on a CoMo/Al2O3 Catalyst: Reaction Network and Kinetics

The hydrodesulfurization of 4-methyldibenzothiophene and 4,6-dimethyldibenzothiophene on a commercial CoMo/Al2O3 catalyst was studied in a multiphase flow reactor in the presence of dibenzothiophene. Hougen−Watson rate equations for the hydrogenolysis of 4-methyldibenzothiophene into 3-methylbiphenyl and H2S and for the hydrogenation of 4-methyldibenzothiophene into partially hydrogenated intermediates were developed. In an identical manner Hougen−Watson kinetics were determined for the hydrogenolysis of 4,6-dimethyldibenzothiophene into 3,3‘-dimethylbiphenyl and H2S and for the hydrogenation of 4,6-dimethyldibenzothiophene into dimethyltetra- and dimethylhexahydrodibenzothiophene. Two different types of active sites exist on the catalyst surface: σ sites for hydrogenolysis and τ sites for hydrogenation reactions. The surface reaction between adsorbed reactants and two competitively adsorbed hydrogen atoms was the rate-determining step for both types of reaction.

Water Treatment With Multiphase Flow Reactor and Cationic Surfactants

Outlined here is research into a process by which raw water and contaminated waters can be effectively treated by using a foam separation reactor in which cationic quaternary ammonium compound is used as both collector and disinfectant.