Electrically Heated Fluidized Bed for Graphite Purification: Heat Transfer and Electric Resistivity Models for Scale-Up

Chemical looping combustion of Victorian brown coal using Fe-based oxygen carriers

99/00352 Modeling of gasification behavior in freeboard of fluidized bed gasifier

Catalytic deoxygenating characteristics of oxygen-bearing coal mine methane in the fluidized bed reactor

The present study introduces the first coupled model of the finite element method and Mie theory that predicts the heat transfer mechanism inside the expanded perlite vacuum insulation panels at a temperature range of 300–800 K. The finite element method is applied to discretise the governing equation of the steady state heat transfer and the three-dimensional Fourier's law is used. COMSOL Multiphysics is the finite element numerical solver which predicts solid and gaseous thermal conductivity inside the VIPs. Moreover, Mie theory predicts the radiative conductivity. Heat transfer radiation is superimposed on the heat transfer through conduction. The model is capable of predicting total thermal conductivity of VIPs at high temperatures ≥ 500 K, which makes it a unique model with clear advantage over previously developed numerical models. The numerical predictions of the developed coupled model are validated experimentally. The predictions of the coupled model are in good agreement with the experimental measurements, which indicate the capability of the developed model to predict the mechanisms of heat transfer at high temperatures. For instance, the values of total thermal conductivity for numerical prediction and experimental measurement, at 557 K, are 14.6 and 14.7±1.2 mW/m/K, respectively, excellently agreeing within ± 8.9 %.

Hydrodynamics of a reactor for thermocatalytic oxidation of sewage sludge

Fossil hydrogen with reduced [formula omitted] emission: Modeling thermocatalytic decomposition of methane in a fluidized bed of carbon particles

The aim of this research is to investigate the influence of various ion exchange methods in the assembly of nanostructured kaolin-SAPO-34 catalyst using silica sol as binder by spray drying for conversion of methanol to light olefins in a fluidized bed reactor. Physiochemical properties of the catalysts were identified by XRD, FESEM, EDX, BET, NH3-TPD and FTIR techniques. The results of XRD analysis exhibit typical SAPO-34 and kaolinite phase for all the three spray dried samples. It represents the successful spray drying that the crystallite structure of the shaped samples assumes by the spray dryer that is composed of both kaolinite and SAPO-34 phase. With the comparison of FESEM results of the samples, it can be implied that use of resin as an ion-exchange agent resulted in smoother and larger particles. According to NH3-TPD results at high calcination temperatures, the reaction of silica from the binder with the extra-framework alumina of kaolin or SAPO-34 results in new acid sites. The catalysts mechanical strength was evaluated by the fluidized bed attrition test. MTO Performance tests were carried out to study the activity of the catalysts in a fixed bed reactor. The optimized catalyst was also tested in a fluidized bed reactor. The optimal shaped sample showed excellent activity of near 22 h during MTO reaction in a fluidized bed reactor.

A mathematical model for thermo-catalytic decomposition of methane over carbon black catalysts in a fluidized bed was proposed. The simplified isothermal, uniform flow model was considered and implemented into a computer code to predict the reactor performance. The experiment of methane decomposition into hydrogen and carbon was carried out in a fluidized bed of I.D of 0.055 m and height of 1.0 m. The range of reaction temperature was 850–900 °C, gas velocity was 1.0–3.0 Umf, and catalyst loading was 50–200 g. The reaction parameters for model equation were determined from the curve fittings and the comparison of experimental data with simulation results showed good agreement for fluidized bed reactor system. From the simulation results, the fluidized bed performance with different operating conditions were obtained, and this simple model can be used to predict the performance of a larger scale fluidized bed reactor and also in determining the optimum operating conditions.

Process simulation and thermodynamic evaluation for chemical looping air separation using fluidized bed reactors

The operation of a number of small and large scale biological fluidized bed pilot plants over the past ten years has resulted in the derivation of process and component information for design of commercial facilities. The General Motors (GM) Corporation represents the single, largest industrial user of the technology in the United States. Ten fluidized bed reactors are located at GM automotive manufacturing facilities. Nine of the reactors are designed to treat wastewaters originating from metalworking operations pretreated for removal of petroleum oils. The other reactor is designed for treatment of sanitary waste-water. In 1984 and 1985, GM completed extensive pilot plant studies and on the basis of the results selected the aerobic fluidized bed (AFB) process configuration for full scale implementation at various plant sites. The fluidized bed reactors located at the sites range in reactor volume from approximately 60 to 730 m3. The pilot plant results which formed the basis for process design of the full scale reactors involved operation of 77 l fluidized bed reactors. Operating information and performance results were derived from evaluation of full scale GM fluidized bed reactors located at the New Departure Hyatt (NDH) plant in Sandusky, Ohio and the Oldsmobile engine plant in Lansing, Michigan. The full scale results were compared to the pilot plant results with the objective of understanding the effects of scale-up on system operation and performance. A comparable level of reactor attached volatile solids (VS) was measured in the pilot and full scale reactors. Biomass net yield coefficients were higher in the full scale reactors, likely due to differences in the composition of the wastewater fed to the full scale versus the pilot scale units. Oxygen utilization coefficients were comparable. The full scale performance results compared favorably with results from the pilot plant studies on the basis of the relationship between effluent quality and reactor solids retention time (SRT).

CFD-DEM simulation of fluorination reaction in fluidized beds with local grid and time refinement method

An array of zeolites varying in the channel structural design and acidity was investigated in toluene methylation with methanol, together with toluene disproportionation, using fluidized-bed and fixed-bed reactors. The conversions of toluene in the methylation and disproportionation reactions in the fixed-bed reactor were higher than those in the fluidized-bed reactor over the zeolite based catalysts at similar reaction conditions. The unique pore architecture of zeolite TNU-9, with 10-ring channel systems, being slightly larger zeolite compared with ZSM-5, can offer new opportunities for toluene disproportionation, as well as for toluene methylation. The medium pore zeolite TNU-9 was found to possess the highest conversion in toluene disproportionation as compared with other zeolite based catalysts under study. In toluene methylation, the highest toluene conversion was achieved with mordenite based catalyst (MOR-A), while the xylene selectivity follows the order: ZSM-5 > TNU-9 > MOR-A > SSZ-33 > MOR-B. This order indicates that xylene selectivity is directly related to the size of channels from medium to large pore zeolites. Using the fluidized bed, the apparent activation energies for toluene methylation follow the order: ZSM-5 (46.8 kJ/mol) > TNU-9 (33.9 kJ/mol) > MOR-B (13.9 kJ/mol) ≈ MOR-A (13.1 kJ/mol) > SSZ-33 (8.2 kJ/mol).

A model for catalytic synthesis of carbon nanotubes in a fluidized-bed reactor: Effect of reaction heat

Experimental and numerical simulation of lignite chemical looping gasification with phosphogypsum as oxygen carrier in a fluidized bed

Methanation of biosyngas in a fluidized bed reactor