The effect of temperature on the phenomenon of defluidization in fluidized bed production process

The results in Figs. In this test, an gram sample of the particulate oxide was distributed in a small Coors alumina boat. Examples of suitable oxidants include oxygen, air, peroxide compounds, carbon dioxide, carbon monoxide and, preferably, water in the form of steam.

Show others and affiliations English In: This is because the silicon and boron cations will migrate from below the outer surface of the particles into the outer surface layer during synthesis gas operations and collect at the surface in concentrations sufficient to promote sintering and agglomeration of the particles.

A method for reducing molybdenum oxide, comprising the steps of: Primary Reaction Mechanisms R. Design criteria and performance predictions for fluid bed units working at high temperature have been largely based on fluid-dynamic models and correlations established from tests developed at ambient temperature.

This characterizes a different fluidization state from Umf, since the in the latter the bed is in an expanded but not bubbling state.

The low defluidization temperature for the rapeseed cake can be attributed to the formation of sticky ash, which is dominated by phosphates. Effects of PSDs on Particle Adhesion The effects of particle adhesion and inter-particle force were considered as to be dominant in fluidization behavior at high temperatures.

Fluidization behavior of biomass particles and its improvement in a cold visualized fluidized bed

Agglomeration occurs all too quickly whether the surface contaminated heat transfer solid particles are added ab initio to the fluidized bed of the synthesis gas reactor, or agglomerated at synthesis gas operating conditions as a result of the transport of bulk impurities from the interior of the particles to the outer surface where the particulate solids contain excessive amounts of these elements as bulk impurities.

Such an underflow discharge preferentially removes the larger reduced particles. The Umf and Ubb for the three types of mixing were typically in the following sequence: In such solids, the calcium is more-or-less uniformly distributed throughout the oxide matrix and the material will display characteristic features in the X-ray diffraction pattern which are indicative of the spinel structure rather than that of alpha alumina.

The dilatometry results of contraction as a function of temperature for the iron powders are presented in Fig. After approximately thirty minutes, the bed differential pressure increased to 64 cm WC and, after approximately forty-five minutes, the bed differential pressure increased to 90 cm WC indicating fluidization was regained.

US3562780A - Temperature control of iron ore reducing fluidized beds - Google Patents

It is apparent that the acid washed materials with improved agglomeration resistance displayed reduced surface concentrations of impurity species. The catalyst component of the fluidized bed contains preferably from about 1 percent to about 20 percent nickel, more preferably from about 5 percent to about 10 percent nickel, composited with an alumina support, preferably an alpha alumina support.

The experimental results are in agreement with the prediction based on the ternary phase diagram analysis. Furthermore, in glassy systems the flow is unlikely to be Newtonian in essence.

Field of the Invention This invention relates to a process for producing novel heat transfer solids, and process utilizing a combination of said heat transfer solid in admixture with a catalyst, or catalysts, to provide a fluidizable contact mass useful for conducting chemical reactions at high temperature, oxidizing, reducing and hydrothermal conditions, especially synthesis gas generation.

Materials used have included low-density ploy-ethylene and poly-propylene, soda glasses, metals, and inorganic crystalline salts. John Bonica worked to define pain as a clinical field and a worthwhile subject for multidisciplinary neuroscience. In all cases, it can be seen that nitric acid treatment resulted in improved agglomeration resistance.

The variation of defluidization temperature with PSD was in accordance with the observed trend of the surface viscosity measured. The materials studied included a spherical spray dried alpha alumina produced by a commercial supplier Ba spherical fused low density alpha alumina produced by the same supplier Ca fused high purity magnesium oxide manufactured by another commercial supplier Dand a tabular magnesium aluminate manufactured by yet another commercial supplier E.

The apparent surface viscosity of iron powder at defluidization temperature for different PSDs.and the Kroll(1) process for the production of titanium is an example. Different titanium-bearing minerals fluidized bed reactor shown in Fig.

6 consists of a The effect of temperature on the chlorination process within the range ~℃ is shown in Fig. 7. The time-conversion curves for two beds of.

Influence of Particle Shape and Bed Height on Fluidization

The total defluidization temperature for pure bark was above degrees C, whereas, for rapeseed cake, defluidization occurred during combustion ( degrees C). During the combustion of bark, the formation of a potassium-rich layer on the silica-bed grains.

In comparison with the fixed-bed reactor, the fluidized-bed reactor is better suited for the syngas-to-methane process because of its excellent heat removal capability (5).

This study focused on the effect of particle size distribution (PSD) on agglomeration and defluidization in a fluidized bed.

The four PSDs studied. After the defluidization of the bed, the water injection was stopped and the rotating distributor was switched on as a counteracting measure against the agglomeration of the bed, trying to recover the fluidization quality of the controlled state of the bed. Feb 22,  · fluidized bed can operate under nearly isothermal conditions.

The maximum operating temperature is limited by the melting point of the bed material and will typically lie between and C.

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The effect of temperature on the phenomenon of defluidization in fluidized bed production process
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