Biodegradation of an Organic Compounds using Fluidized Bed Reactor

Fluidized beds reactors are used for different purposes; they are still used to produce gasoline and other fuels, along with many other chemicals. Many industrially produced polymers are made using FBR technology, such as rubber, vinyl chloride, polyethylene, and styrene’s. Various utilities also use Fluidized bed reactor for coal gasification, nuclear power plants, and water and waste treatment settings. Used in these applications, fluidized bed reactors allow for a cleaner, more efficient process than previous standard reactor technologies. In this paper a theoretical study about fluidized bed reactors arecarried out and also a fluidized bed reactor for three different reaction schemes (oxidation of benzene to form maleic anhydride, oxidation of naphthalene to form phthalic anhydride and oxidation of ethylene to form ethylene oxide) is designed. Costoptimization for multiple fluidized bed reactors with continuous transport of an immobilized enzyme is also studied and calculated

A MINLP Solution for Pellet Reactor Modeling

A fluidized bed reactor for phosphate precipitation and removal from wastewater is modeled according to a two-step procedure. The first modeling phase, based on the development of a thermodynamic model for the computation of phosphate conversion, previously presented elsewhere is not reported here. The second step is related to the reactor modeling in the core of this paper. The pellet reactor is modeled as a reactor network involving a set of elementary cells representing ideal flow patterns. All the potential solutions are imbedded into a superstructure and the modeling problem is expressed as a MINLP problem. The MINLP problem is solved by means of the GAMS package, first for two flow rate values corresponding to two experimental fluidized bed behaviours, and then for the two flow rates considered simultaneously. In each case, the problem consists in finding an output concentration as close as possible to the experimental output concentration. Three objective functions are studied. The results are compared with those of Montastruc et al. (2004) who used a different numerical procedure. Whatever the considered case, the solutions found are structurally simpler than the ones of Montastruc et al. (2004). A major assessment of this study is that the reactor efficiency can easily be deduced, without any precise knowledge of some key parameters such as the density and thickness of the calcium phosphate layer. Finally a last numerical study concerning the superstructure definition shows that too complex a superstructure does not provide significant refinements on the solution

Safe design and operation of fluidized-bed reactors: Choice between reactor models

For three different catalytic fluidized bed reactor models, two models presented by Werther and a model presented by van Deemter, the region of safe and unique operation for a chosen reaction system was investigated. Three reaction systems were used: the oxidation of benzene to maleic anhydride, the oxidation of naphthalene to phthalic anhydride, and the oxidation of ethylene to ethylene oxide. Predictions of the optimal yield, the operating temperature and the conversion were also subjects of our study. It appeared that for reactions carried out in a fluidized bed operating under conditions of good fluidization all models predicted the same region of safe and unique operation. For a well-designed fluidized bed only the constraint of uniqueness is affected by the reactor model chosen. Predictions of the yield, conversion and operating temperature appeared to fit slightly less well. But still a good indication can be obtained from any of the models since the deviation in the results was less then a few percent for all three reaction systems. The strongest deviations between the models occurs in the region of gas loads only slightly higher than the minimum fluidization velocity. As the heat transfer characteristics are bad at low gas loads this region is unsuitable for highly exothermic reactions where large amounts of heat have to be removed by the coolant. In the region of good heat transfer with gas loads at least several times higher than the minimum the three models predict the same results. For this reason we finally recommed the use of simple models

Influence of Bubble-Bubble Interactions on the Macroscale Circulation Patterns in a Bubbling Gas-Solid Fluidized Bed

The macro-scale circulation patterns in the emulsion phase of a gas-solid fluidized bed in the bubbling regime have been studied with a 3D Discrete Bubble Model. It has been shown that bubble-bubble interactions strongly influence the extent of the solids circulation and the bubble size distribution

Autothermal reactor concept for combined oxidative coupling and methane reforming

A novel autothermal reactor concept has been developed for the simultaneous production of ethylene by oxidative coupling (OCM) and synthesis gas by steam reforming of methane (SRM), supported by a detailed numerical modeling study. The proposed reactor consists of two separate reaction chambers which are thermally coupled. The OCM is carried out in packed bed reverse flow membrane reactor tubes submerged in a fluidized bed where the unconverted methane and by-products, from which the valuable C2 components have been separated, are reformed together with some additional steam producing synthesis gas and consuming the reaction enthalpy emerged from the exothermic OCM

Hydrometallurgy of the delta sulfide ores, second stage report

This report contains results of the Fluidized-Bed Leaching (FBL) initially adapted to improve Leaching-Flotation processing of Delta ores in sulfate solution. The research carried out in the continuous laboratory installation show, however, that the new, 3-phase (solid-liquid-gaseous) reactor also performs satisfactorily in other leaching systems. A new process of pyritic matrix destruction for precious metals recovery in the FBL reactor, and a new process for recovery of zinc and other metals in a chloride system are proposed on the basis of laboratory results.Submitted to: Nerco Minerals Compan

Autothermal Reforming of Methane with Integrated CO2 Capture in a Novel Fluidized Bed Membrane Reactor. Part 2 Comparison of Reactor Configurations

The reactor performance of two novel fluidized bed membrane reactor configurations for hydrogen production with integrated CO2 capture by autothermal reforming of methane (experimentally investigated in Part 1) have been compared using a phenomenological reactor model over a wide range of operating conditions (temperature, pressure, H2O/CH4 ratio and membrane area). It was found that the methane combustion configuration (where part of the CH4 is combusted in situ with pure O2) largely outperforms the hydrogen combustion concept (oxidative sweeping combusting part of the permeated H2) at low H2O/CH4 ratios (<2) due to in situ steam production, but gives a slightly lower hydrogen production rate at higher H2O/CH4 ratios due to dilution with combustion products. The CO selectivity was always much lower with the methane combustion configuration. Whether the methane combustion or hydrogen combustion configuration is preferred depends strongly on the economics associated with the H2O/CH4 ratio

Experimental study on solids circulation patterns and bubble behavior using particle imagevelocimetry combined with digital image analysis

The hydrodynamics, viz. the solids circulation patterns and\ud bubble behavior, of a freely bubbling gas-solid fluidized bed\ud has been investigated experimentally using Particle Image\ud Velocimetry (PIV) combined with Digital Image Analysis\ud (DIA). Coupling of these non-invasive measuring techniques\ud allows us to obtain information on both the bubble behavior\ud and emulsion phase circulation patterns simultaneously, in\ud order to study in detail their intricate interaction. In\ud particular, the combination of DIA with PIV allows correcting\ud for the influence of particle raining through the roof of the\ud bubbles on the time-averaged emulsion phase velocity\ud profiles. Because of the required visual access, this technique\ud can only be applied for pseudo-2D fluidized beds.\ud The bubble rise velocity as a function of the equivalent\ud bubble diameter and the average bubble diameter as a\ud function of the position above the distributor were\ud determined with DIA and compared with literature\ud correlations. Subsequently, the importance was demonstrated\ud of filtering the instantaneous emulsion phase velocity profiles\ud obtained with PIV for particle raining, using DIA, to obtain\ud the time-averaged emulsion phase velocity profiles. The timeaveraged\ud solids circulation patterns have been studied as a\ud function of the superficial gas velocity and bed aspect rati