Substantiation of a rational method for drying granules in a fluidized bed and the hydrodynamic regime of their interaction with a fluidizing agent

Gluten is produced from wheat grains and is used in the food industry as an improver in flour baking properties. On the basis of a comparative analysis of the methods of dehydration of frozen granules of wheat gluten with a surface dry crust, a rational method of drying them in a fluidized bed has been selected. In the process of calculating units with a fluidized bed, its hydrodynamic parameters have been determined: loss of the pressure of the fluidizing agent; the speed at the transition of the bed from the state of rest to the pseudo-boiling mode; layer porosity; the rate of entrainment of particles in unrestricted conditions roughly corresponding to the rate of soaring, at which a single particle is in equilibrium in the gas flow. During the dewatering operation, the rate of entrainment of the granules varies; therefore, it is advisable to use the passing fluidization mode depending on the decrease in their moisture content. In the variant of the active hydrodynamic regime in the drying unit, the dehydration procedure is intensified without a noticeable decrease in the economic efficiency of its functioning and high quality indicators of the finished product with the given final moisture are provided, which is due to the specific conditions of contact of the granules with the coolant. For granules with a moisture content of 0.19 kg/kg, the values of hydrodynamic characteristics have been determined: the area of critical pseudo-boiling rates is 4.1-5.5 m/s; the carryover rate of the fines is 12.5-14.5 m/s. As a result of the study, the choice has been substantiated in favor of drying the studied granules in a fluidized bed due to the prevalence of its advantages over the dehydration of the object in drum dryers.

INVESTIGATION OF THE PROCESS OF OBTAINING PYROCARBON IN AN ELECTROTHERMAL FLUIDIZED BED

Carbon materials with a wide range of performance properties are used in various science, technology, and industry fields. For example, Pyrocarbon has the prospect of being used in nuclear power engineering, special metallurgy, aerospace technologies, heat exchange equipment, medicine, mechanical engineering, reactor building and other industries. The research described in the article aims to study the process of obtaining pyrocarbon in an electrothermal fluidized bed. The research is based on experimental methods of studying the process of obtaining pyrolytic carbon. Pyrocarbon is precipitated during pyrolysis (thermal destruction) of hydrocarbons in an electrothermal fluidized bed reactor. Natural gas was used as a fluidizing agent, and crushed fine electrode graphite of the GE model was used as a fluidized bed. When producing batches of pyrocarbon material, taking into account that the particle size will increase, these particles were crushed and subsequently used as a fluidized bed, thereby replacing graphite with pyrocarbon. As a result of the experimental studies carried out in the reactor with the electrothermal fluidized bed reactor, the batches of pyrocarbon material that were produced based on artificial graphite were produced. Studies using electron microscopy showed a change in the color and structure of the pyrocarbon coating depending on the processing cycle in the electrothermal fluidized bed reactor at temperatures of 900–1200 °C. Diffractometric analysis showed that pyrocarbon was identified in the treated material. Therefore, the adequacy of the method for calculating the heat balance has been confirmed. Bibl. 36, Fig. 7, Table 1.

Experimental study of convective dryer with centrifugal fluidized bed

Nowadays, the units with a fluidized bed hold a special place among all heat-mass transfer plants currently used in industry. First of all, it is due to the highly developed surface of interaction between the fluidizing agent (air) and dispersed materials in such units, their low hydraulic resistance, relatively simple design and small sizes. At the same time, the units with a centrifugal fluidized bed, which is formed in an annular channel of the working chamber when a fluidizing agent is added under the fixed angle, are of particular interest. Currently, a limited number of experimental and theoretical studies of hydrodynamics and heat-mass transfer in a fluidized bed are known. Besides, these studies were carried out mainly in respect to regenerative heat exchangers and absorbers. In this regard, such studies in respect to the devices for other purposes, such as dryers, seem to be relevant. The results of these studies are the scientific backgrpund for development of an engineering calculation methodology of such units and their design. The study has been carried out based on an experimental plant using means for measuring temperature, relative air humidity, differential pressure, air velocity, and moisture content of solids. A TPM 148 PID controller has been used as a secondary device. Experimental data have been recorded in MasterSCADA SCADA system. Data processing has been carried out using interpolation by cubic splines. The article describes in detail an experimental plant that allows carrying out a full factor experiment to study the hydrodynamic and thermal parameters of a convective dryer with a centrifugal fluidized bed. The article presents the results of a preliminary series of experiments in which silica gel is used as a dispersed material. As a result of visual observations over the dispersed material in the working chamber, the values of the minimum and maximum speed of the drying agent have been determined. The grafic relationship of the hydraulic resistance of the working chamber and the height of the material layer are obtained depending on the speed of the drying agent and the mass of the material, as well as the temperature and moisture content of the material and the drying agent depending on the drying time. The results obtained make it possible to determine the design and operational parameters of the centrifugal fluidized bed drying plant and select a fan to supply the drying agent.

Quantifying Uncertainty in the Residence Time of the Drug and Carrier Particles in a Dry Powder Inhaler

Dry powder inhalers, used as a means for pulmonary drug delivery, typically contain a combination of active pharmaceutical ingredients (API) and significantly larger carrier particles. The micro-sized drug particles - which have a strong propensity to aggregate and poor aerosolization performance - are mixed with significantly large carrier particles that cannot penetrate the mouth-throat region to deagglomerate and entrain the smaller API particles in the inhaled airflow. Therefore, a DPI's performance depends on the carrier-API combination particles' entrainment and the time and thoroughness of the individual API particles' deagglomeration from the carrier particles. Since DPI particle transport is significantly affected by particle-particle interactions, particle sizes and shapes present significant challenges to CFD modelers to model regional lung deposition from a DPI. We employed the Particle-In-Cell method for studying the transport/deposition and the agglomeration and deagglomeration for DPI carrier and API particles in the present work. The proposed development will leverage CFD-PIC and sensitivity analysis capabilities from the Department of Energy laboratories: Multiphase Flow Interface Flow Exchange and Dakota UQ software. A data-driven framework is used to obtain the reliable low order statics of the particle's residence time in the inhaler. The framework is further used to study the effect of drug particle density, carrier particle density and size, fluidizing agent density and velocity, and some numerical parameters on the particles' residence time in the inhaler.

Devolatilization of Residual Biomasses for Chemical Looping Gasification in Fluidized Beds Made up of Oxygen-Carriers

The chemical looping gasification of residual biomasses—operated in fluidized beds composed of oxygen-carriers—may allow the production of biofuels from syngas. This biomass-to-fuel chain can contribute to mitigate climate change, avoiding the accumulation of greenhouse gases in our atmosphere. The ongoing European research project Horizon2020 CLARA (G.A. 817841) investigates wheat-straw-pellets (WSP) and raw-pine-forest-residue (RPR) pellets as feedstocks for chemical looping gasification. This work presents experimental results from devolatilizations of WSP and RPR, in bubbling beds made of three different oxygen-carriers or sand (inert reference), at 700, 800, 900 °C. Devolatilization is a key step of gasification, influencing syngas quality and quantity. Tests were performed at laboratory-scale, by a quartz reactor (fluidizing agent: N2). For each pellet, collected data allowed the quantification of released gases (H2, CO, CO2, CH4, hydrocarbons) and mass balances, to obtain gas yield (ηav), carbon conversion (χavC), H2/CO ratio (λav) and syngas composition. A simplified single-first order-reaction model was adopted to kinetically analyze experimental data. WSP performed as RPR; this is a good indication, considering that RPR is similar to commercial pellets. Temperature is the dominating parameter: at 900 °C, the highest quality and quantity of syngas was obtained (WSP: ηav = 0.035–0.042 molgas gbiomass−1, χavC = 73–83%, λav = 0.8–1.0); RPR: ηav = 0.036–0.041 molgas gbiomass−1, χavC = 67–71%, λav = 0.9–1.0), and oxygen-carries generally performed better than sand. The kinetic analysis suggested that the oxygen-carrier ilmenite ensured the fastest conversion of C and H atoms into gases, at tested conditions.

Korelacja skuteczności działania środków dyspergujących o różnym mechanizmie upłynniania

Effective borehole sealing depends on many properties of the cement slurry. The rheological parameters are the most important. Designing the cement slurry with the required values of plastic viscosity, yield point or consistency coefficient contributes to the efficient performance of the cementing procedure and allows for effective filling of the cemented space outside the tubing. In order to adjust rheological parameters to technological requirements, dispersants are used. The operation of these plasticizers or superplasticizers is related to their chemical structure, which determines their liquefaction mechanism. Therefore, in order to properly select a fluidizing agent, it is beneficial to become familiar with its mechanism of operation, thanks to which it will be possible to use the optimal amounts for a given cement slurry recipe. The publication discusses the effectiveness of dispersing agents depending on their liquefaction mechanism. The research work carried out consisted in the modification of the cement slurry with the use of sodium salts of polycondensates of naphthalene sulfonic acids and a polymer dispersant based on carboxylates. Amounts of dispersant ranging from 0.05% (bwoc) to 1.0% (bwoc) were used. The rheological parameters described by means of five rheological models, i.e. Newton, Bingham, Ostwald de Waele, Casson and Herschele-Bulkley, were tested for the cement slurries. The main goal of the work presented in the article was to conduct a correlation analysis of the change in rheological parameters of slurries modified with dispersants belonging to different groups depending on their liquefaction mechanism. Thanks to this, it was possible to indicate the effectiveness of the dispersing additives depending on the amount of the fluid used belonging to a specific group. The work carried out is helpful in determining the optimal amount of dispersing agent depending on its type (mechanism of action).

Uncertainty Quantification of a Fluidized Bed Reactor

Fluidized beds are used in a wide range of applications in gasification, combustion, and process engineering. Multiphase flow in such applications involves numerous uncertain parameters. Uncertainty quantification provides uncertainty in syngas yield and efficiency of coal/biomass gasification in a power plant. Techniques such as sensitivity analysis are useful in identifying parameters that have the most influence on the quantities of interest. Also, it helps to decrease the computational cost of the uncertainty quantification and optimize the reactor. We carried out a nondeterministic analysis of flow in a biomass reactor. The flow in the reactor is simulated with National Energy Technology Laboratory’s open source multiphase fluid dynamics suite MFiX. It does not possess tools for uncertainty quantification. Therefore, we developed a C++ wrapper to integrate an uncertainty quantification toolkit developed at Sandia National Laboratory with MFiX. The wrapper exchanges uncertain input parameters and critical output parameters among Dakota and MFiX. We quantify uncertainty in key output parameters via a sampling method. In addition, sensitivity analysis is carried out for all eight uncertain input parameters namely particle-particle restitution coefficient, angle of internal friction, coefficient of friction between two-phases, velocity of the fluidizing agent at the inlet, velocity of the biomass particles at the inlet, diameter of the biomass particles, viscosity of the fluidizing agent, and the percentage of nitrogen/oxygen in the fluidizing agent.

INVESTIGATION OF THE INFLUENCE OF MECHANICAL-VIBRATIONAL SOUND ON HYDRODYNAMICS OF A FLUIDIZED BED

The main purpose of this paper is to investigate the concept of a heat treatment of a small amount of solid material with the maximum contact of the gas and solid material. The solution of this problem consists in passing the process in a fluidized bed. However, the key issue of this solution is the problem of entrainment of solid material. Among feasible ways of the fluid bed hydrodynamics creation is a sound waves transmission through a solid granular material. A visual study on the fluid bed hydrodynamics creation with sound waves was conducted. The estimation of the impact of the trajectory of the particles on the thermophysical properties of the fluidized system was determined. The exploitation of sound waves should increase the intensity of heat exchange inside and between the solid and gas phases. Reactor design scheme for pyrocarbon coatings creation was developed. This scheme implies a small amount of material to be treated. The results obtained can be subsequently applied in the process of developing new fluidized bed apparatus, when the usage of a gas or a liquid as a fluidizing agent is technically impossible (or insufficiently). The prospects for further research include homogenization of the agglomerate layer by means of sound waves. Bibl. 9, Fig. 4.