52,150 research outputs found

    Systems and methods for monitoring solids using mechanical resonator

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    Multi-phase system monitoringmethods, systems and apparatus aredisclosed. Preferred embodiments comprise one or more mechanical resonator sensing elements. In preferred embodiments a sensor or a sensor subassembly is ported to a fluidized bed vessel such as a fluidized bed polymerization reactor

    Comparison of fibre optical measurements and discrete element simulations for the study of granulation in a spout fluidized bed

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    Spout fluidized beds are frequently used for the production of granules or particles through granulation. The products find application in a large variety of applications, for example detergents, fertilizers, pharmaceuticals and food. Spout fluidized beds have a number of advantageous properties, such as a high mobility of the particles, which prevents undesired agglomeration and yields excellent heat transfer properties. The particle growth mechanism in a spout fluidized bed as function of particle-droplet interaction has a profound influence on the particle morphology and thus on the product quality. Nevertheless, little is known about the details of the granulation process. This is mainly due to the fact that the granulation process is not visually accessible. In this work we use fundamental, deterministic models to enable the detailed investigation of granulation behaviour in a spout fluidized bed. A discrete element model is used describing the dynamics of the continuous gas-phase and the discrete droplets and particles. For each element momentum balances are solved. The momentum transfer among each of the three phases is described in detail at the level of individual elements. The results from the discrete element model simulations are compared with local measurements of particle volume fractions as well as particle velocities by using a novel fibre optical probe in a fluidized bed of 400 mm I.D. Simulations and experiments were carried out for three different cases using Geldart B type aluminium oxide particles: a freely bubbling fluidized bed; a spout fluidized bed without the presence of droplets and a spout fluidized bed with the presence of droplets. It is demonstrated how the discrete element model can be used to obtain information about the interaction of the discrete phases, i.e. the growth zone in a spout fluidized bed. Eventually this kind of information can be used to obtain closure information required in more coarse grained models

    Particle Size Control by Torque Measurements in Fluidized Beds during Drying and Granulation from Solutions

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    The fluidized bed process presented in this paper is suitable to recover solids from solution in form of granules. Solution is sprayed into the bed and, as the solvent evaporates, solid material is deposited on the surface of fluidizing particles. During this process, particle growth takes place by surface layering and/or agglomeration. A special grinder is used in the fluidized bed to control particle growth by causing selective disintegration of large particles. For steady state operation, the most important task is to determine the existing particle size distribution in the fluidized bed. A special method was developed to measure torque and stress fluctuations in the bed of particles. Using a correlation between torque and particle size, this method and device can be used for direct control of the rotation speed of the grinder to produce granules of given size in the fluidized bed. In this paper, the results of torque measurements and their correlation with particle size are presented

    Method for Particle Size Control During the Drying and Granulation in Fluidized Bed

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    The fluidized bed process presented in this paper is suitable for recovery of solids from solutions in the form of granules. The solution is sprayed into the bed and as solvent evaporates, solid material is deposited on the surface of fluidizing particles. During this process, particle growth takes place by surface layering and/or agglomeration. A special grinder is used in the fluidized bed to control particle growth by causing selective disintegration of large particles. For steady state operation, the most important task is to determine the existing particle size distribution in the fluidized bed. A special method was developed to measure torque and stress fluctuations* in the bed of particles. Using a correlation between torque and stress fluctuations and particle size, this method and device can be used for direct control of the rotation speed of the grinder to produce granules of given size in the fluidized bed. Results of torque and stress measurements and their correlation to particle size are presented

    Discrete element modeling and fibre optical measurements for fluidized bed spray granulation

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    Spout fluidized beds are frequently used for the production of granules or\ud particles through granulation. The products find application in a large variety of\ud applications, for example detergents, fertilizers, pharmaceuticals and food. Spout fluidized\ud beds have a number of advantageous properties, such as a high mobility of the particles,\ud which prevents undesired agglomeration and yields excellent heat transfer properties. The\ud particle growth mechanism in a spout fluidized bed as function of particle-droplet\ud interaction has a profound influence on the particle morphology and thus on the product\ud quality. Nevertheless, little is known about the details of the granulation process. This is\ud mainly due to the fact that the granulation process is not visually accessible. In this work\ud we use fundamental, deterministic models to enable the detailed investigation of\ud granulation behaviour in a spout fluidized bed. A discrete element model is used\ud describing the dynamics of the continuous gas-phase and the discrete droplets and\ud particles. For each element momentum balances are solved. The momentum transfer\ud among each of the three phases is described in detail at the level of individual elements.\ud The results from the discrete element model simulations are compared with local\ud measurements of particle volume fractions as well as particle velocities by using a novel\ud fibre optical probe in a fluidized bed of 400 mm I.D. Simulations and experiments were\ud carried out for two different cases using Geldart B type aluminium oxide particles: a\ud freely bubbling fluidized bed and a spout fluidized bed with the presence of droplets. It is\ud demonstrated how the discrete element model can be used to obtain information about the\ud interaction of the discrete phases, i.e. the growth zone in a spout fluidized bed. Eventually\ud this kind of information can be used to obtain closure information required in more coarse\ud grained model

    Supercritical fluid coating of API on excipient enhances drug release

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    A process to coat particles of active pharmaceutical ingredient (API) onto microcrystalline cellulose (MCC) excipient shows promise as a new way to dosage forms showing enhanced drug release. The process consists of a fluidized bed operated at elevated pressure in which API particles are precipitated from a Supercritical Anti-Solvent process (SAS). MCC particles were used as an excipient in the fluidized bed and collect the SAS-generated API particles. Naringin was selected as the model API to coat onto MCC. A number of operational parameters of the process were investigated: fluidization velocity, coating pressure, temperature, concentration of drug solution, drug solution flow rate, drug mass, organic solvent, MCC mass and size and CO2-to-organic solution ratio. SEM and SPM analyses showed that the MCC particle surfaces were covered with near-spherical nanoparticles with a diameter of approximately 100–200 nm, substantially smaller than the as-received API material. XRD showed that naringin changed from crystalline to amorphous during processing. The coated particles resulting from the SAS fluidized bed process have a higher loading of API, gave faster release rates and higher release ratios in comparison with those produced using a conventional fluidized bed coating process. The approach could be transferred to other industries where release is important such as agrochemical, cosmetic and food

    Fluidized bed desulfurization

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    High sulfur content carbonaceous material, such as coal is desulfurized by continuous fluidized suspension in a reactor with chlorine gas, inert dechlorinating gas and hydrogen gas. A source of chlorine gas, a source of inert gas and a source of hydrogen gas are connected to the bottom inlet through a manifold and a heater. A flow controler operates servos in a manner to continuously and sequentially suspend coal in the three gases. The sulfur content is reduced at least 50% by the treatment

    Measurement of Flow Characteristics in a Bubbling Fluidized Bed Using Electrostatic Sensor Arrays

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    Fluidized beds are widely applied in a range of industrial processes. In order to maintain the efficient operation of a fluidized bed, the flow parameters in the bed should be monitored continuously. In this paper, electrostatic sensor arrays are used to measure the flow characteristics in a bubbling fluidized bed. In order to investigate the electrostatic charge distribution and the flow dynamics of solid particles in the dense region, time and frequency domain analysis of the electrostatic signals is conducted. In addition, the correlation velocities and weighted average velocity of Geldart A particles in the dense and transit regions are calculated, and the flow dynamics of Geldart A and D particles in the dense and transit regions are compared. Finally, the influence of liquid antistatic agents on the performance of the electrostatic sensor array is investigated. According to the experimental results, it is proved that the flow characteristics in the dense and transit regions of a bubbling fluidized bed can be measured using electrostatic sensor arrays

    Modeling of fluidized bed silicon deposition process

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    The model is intended for use as a means of improving fluidized bed reactor design and for the formulation of the research program in support of the contracts of Silicon Material Task for the development of the fluidized bed silicon deposition process. A computer program derived from the simple modeling is also described. Results of some sample calculations using the computer program are shown

    An experimental study on heat transfer in liquid-solid packed fluidization

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    Gas-solid fluidized beds are widely used in various process and allied industries for their inherent advantage of high rates of heat and mass transfer and quickly achievable isothermal condition inside bed. This conventional gas-solid fluidized bed may be referred as unary fluidized bed, because the particles used in such fluidized beds are generally within close size range. There are another type of fluidized bed used in case of some typical applications, in which small particles are allowed to fluidize in the interstitial void of relatively large and stationary bed of pebbles, called packing. This type of fluidized beds is called binary packed fluidized Bed [1-3]. Heat transfers in gas-solid unary fluidized bed was well studied and are reported in literature, but till date few studies were conducted and reported in literature on the heat transfer in gas-solid packed fluidized bed [4, 5]. Mandal et al, studied the hydrodynamic behavior of gas-solid [3] as well as liquid-solid packed fluidized bed [6], but no study has been reported on the study of heat transfer in liquid–solid binary packed fluidized bed. It was found that the rate of heat transfer in gas-solid packed fluidized enhances many folds compared to that of packed bed under similar operating conditions [4, 5] and a correlation (Eq. (1)) has been developed to determine the effective thermal conductivity of packed fluidized bed (). In Eq.(1) and are thermal conductivity of solid and gas, is the void fraction of packed fluidized bed, and are size of particle and pebbles, is the volume fraction of the interstitial void volume of packed bed filled with particles and is the Peclet number of packed fluidized bed defined somewhere else. [5]. Please click Additional Files below to see the full abstract
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