Spouted Bed Research Articles

The Effect of Operating Conditions on SO2 Removal in Semidry Desulfurization Process by Powder-Particle Spouted Bed.

本研究では噴流型粉粒流動層を用い, 水処理を必要としない新しいタイプの半乾式脱硫装置を開発した.ベンチスケール規模の噴流型粉粒流動層脱硫装置へ, 脱硫剤微粒子のスラリーを連続供給し, 乾燥しながらSO2と反応させ, 飛び出された反応済み脱硫剤の微粒子を捕集した.使用した脱硫剤は消石灰と消白雲石の微粒子のスラリーである.本研究では脱硫率に及ぼす静止層高, 空塔基準ガス速度, ガス中のSO2に対する脱硫剤の化学量論比, 層内ガス温度と対応する飽和状態の温度 (湿球温度) との差即ち飽和接近温度, 媒体粒子の粒子径などの影響を調べた.諸因子のうち, 脱硫率はガス中のSO2モル流量に対する供給した脱硫剤のモル流量との比, つまり化学量論比Ca/Sと飽和接近度に大きく影響をうけた.すなわち飽和接近度の値を小さくすると脱硫率を著しく向上させた.脱硫率はCa/Sの値が12以上, 飽和接近度の値が13K以下であれば, 脱流率は95%以上となった.本装置では脱硫率は媒体粒子の層高が高いほどまた空塔基準ガス速度が小さいほど大きくなった.すなわち, 層内でのガスの平均滞留時間が大きいほど大きくなった.また, 本流動層における媒体粒子は流動化が正常であれば, そのサイズが脱硫反応へ影響を及ぼさないことを確認した.

EXPERIMENTAL STUDY ON THE DYNAMICS OF A SPOUTED BED WITH PARTICLE FEED THROUGH THE BASE

A draft tube spouted bed was constructed with a screw conveyor attached at its base to feed particles into the column. Results on fluid dynamic characteristics and particle movement in this system are presented and discussed. Two methods of measuring the superficial air velocity in the annular region are compared. The particle velocity and recirculation rates have been determined in a half column with transparent walls. The effects of the particle feed rate, air flow rate and bed height on the spouted bed dynamics have been analysed and compared with those in the literature. Keywords: Spouted bed, continuous feed, dynamics

Design and Operation of a Catalytic Polymerization Reactor in a Dilute Spouted Bed Regime

A simulation model for a catalytic polymerization reactor in a dilute spouted bed regime is described. The model, which is of dispersed plug flow, is based on solving the mass conservation equation...

Scale-up studies of spouted beds

The scaling relationships proposed by Glicksman ( Chem. Engng Sci. 39, 1373–1379, 1984) for fluidized-bed scale-up have been modified to provide a full set of scaling parameters for spouted bed scale-up. A force balance for particles in the annulus region of a spouted bed leads to addition of two non-dimensional parameters, the internal friction angle (ϕ) and the loose packed voidage ( ε 0) to the original Glicksman scaling relationships. Experimental verification of the full set of modified scaling parameters was conducted, first in a series of small spouted beds, then in larger columns up to 0.914 m in diameter, and finally in a pair of high-temperature (500°C) columns. Both viscous and inertial forces were important for the conditions investigated so that the full set of scaling parameters is tested initially. It is demonstrated that the full set of modified scaling parameters is valid for spouted beds when all dimensionless parameters are matched between the prototype bed and model beds. For example, a corresponding dead zone was observed at the bottom of the annulus not only in the 0.914 m diameter column, but also in a properly scaled 0.152 m diameter column. Reasonably, close similarity could also be achieved by substituting U U ms for the Reynolds number as a dimensionless group. Successful scaling could not be achieved by varying only the bed and particle dimensions. Internal angles of particle friction and sphericities significantly influence the maximum spoutable depth, fountain height and longitudinal pressure profiles, showing that particle-particle interaction forces cannot be ignored in spouted bed scale-up.

Drying Of Pastes In Spouted Beds Of Inert Particles: Design Criteria And Modeling

ABSTRACT The drying of pastelike materials can be performed well in spouted beds (SB) of inert particles. In this work the drying performance of pastes in conical pastes in conical spouted beds is analyzed as a function of column dimensions, fluid flow characteristics and paste properties. imulated data on fluid flow together with the experimental results on drying of different pastelike materials are presented and discussed to provide criteria for the design of a conical spouted bed dryer for suspensions.

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ドラフトチューブ付噴流層の流動特性と応用技術

ドラフトチューブ付噴流層の流動特性と応用技術

A Two-Dimensional Finite Element Model For Wheat Drying In A Novel Rotating Jet Spouted Bed

ABSTRACT Based on Liquid diffusion model a two-dimensional finite element simulator was developed for the drying of wheat. Simulations were carried out for the drying of a single wheat particle in a novel rotating jet spouted bed. The effects of the choice of the geometric model for the wheat kernel, the temperature and flow rate of the drying air on the moisture removal rate as well as kernel temperature were investigated. Numerical experiments showed that the accuracy of the model geometry chosen has great influence on the computed moisture removal rate partly because of the way the moisture published diffusivily correlations were obtained. Sample results are presented and discussed.

Influence of the conical section geometry on the hydrodynamics of shallow spouted beds

The hydrodynamics of shallow spouted beds and a comparison with the hydrodynamics of conventional spouted beds were studied on a pilot plant scale unit by operating under a wide range of geometric characteristics of the contractor—particle system (base angle, inlet diameter to contactor base diameter ratio, inlet diameter to particle diameter ratio, inlet diameter to column diameter ratio); the ranges of these parameters in which stable operation is possible were delimited. The peculiar hydrodynamic behaviour of shallow spouted beds is attributed to the influence of the conical section of the base, which is an important fraction of the bed. Assuming that the shallow spouted beds are made up of the conical section of the base and the posterior cylindrical section, correlations are proposed for the calculation of the minimum spouting velocity, maximum pressure drop of the bed, operating pressure drop and the bed voidage corresponding to minimum spouting in shallow spouted beds; these are a combination of the correlations proposed in previous papers for totally conical and totally cylindrical contactors.

Solid Flow in Jet Spouted Beds

Filming equipment combined with an image treatment program has been used to study the positions of the particles in the jet spouted bed (or dilute spouted bed in conical contactor). The properties determined were the density functions for distribution of particle trajectories and of their maximum heights in the bed and local bed voidages. The spout geometry has been determined for this regime. By extending the experimental study to systems with different values of contactor inlet diameter, stagnant bed height, and relative air velocity with respect to the minimum needed for the jet spouted bed, the effect of these variables on the properties that describe the solid flow has been analyzed.

Process Development of Effective Semi-Dry Flue Gas Desulfurization by Powder-Particle Spouted Bed.

現在, 湿式の排煙脱硫法が広く採用されているが, 低廉, 高効率でしかも排水のない脱硫法が望まれている.本研究では半乾式の新しいタイプ脱硫装置の開発を目的として, 噴流型粉粒流動層を用いて低温脱硫実験を行った.500～1500ppmのSO2を含む空気で, 媒体粒子を激しく流動化させているところに, 消石灰あるいは他のアルカリ性微粒子のスラリーを連続供給し, 一定の温度条件下で乾燥しながら, 脱硫を行った.反応後の乾いた微粒子は流動層より飛び出し, 集塵器内に捕集される.本研究では主に脱硫剤に消石灰のスラリーを用い, 脱硫率に及ぼす諸因子の影響を調べた.実験結果によると, 脱硫率は消石灰と供給SO2との化学量論比Ca/S, 層内温度及び湿度などの諸因子によって影響を受けた.脱硫温度が 330～340Kにおいては, Ca/Sが1.0で脱硫率が90%以上となることが分かった.従って, 本研究で開発した装置は水処理が要らず, 脱硫率を90%以上とすることができるので, 新しいタイプの排煙脱硫プロセスとして開発される可能性があると思われる.

A Mathematical Model for Constant and Intermittent Batch Drying of Grains in a Novel Rotating Jet Spouted bed

ABSTRACT A diffusion-bared mathdcal model is prswmed for batch drying of corn in a novel rotating jn spouted bcd device under constant as well as intermitted drying conditions. Such a device is suited for drying of large partides (e.g. grains, beam, seed, etc) for which internal heat and mass tranfer rates control the drying kinetics. Based on literature data for moisture diffusivities the model predictions are compared with experimental data for both continous and time-dependend air supply and/or heat input. Effects of dcvant parameter are evaluated and discussed in the light of potential pnrctieal applications.

95/03513 Formation of C 1-C 3 hydrocarbons during pressure pyrolysis and hydrogasification in relation to structural changes in coal

This paper describes preliminary studies carried out to develop a system made up of two interconnected spouted beds for heat integration in highly endothermic processes, such as pyrolysis and gasification. Four different configurations of a dual spouted bed system have been studied depending on the location of the feeding and discharging points in the interconnection pipes, i.e., annulus–annulus, annulus–spout, fountain–spout and fountain–annulus. Fountain–annulus configuration has been determined to be the optimum option based on its stability, solid transfer rate (around 120 kg h− 1) and gas bypassing from one contactor to the other (below 1.5%). Once the optimum system has been established, the viability of the dual spouted bed system has been assessed for heat integration in the biomass pyrolysis, with the minimum temperature difference between the pyrolyser and combustor being 280 °C for attaining allothermal operation. Furthermore, studies have been carried out on the solid circulation rate (energy balance), gas bypassing from one contactor to the other and system stability against different perturbations, which have allowed determining the optimum configuration

Gas Holdup in Highly Viscous Liquids in Gas-Liquid Spouted Beds.

Gas holdup in highly viscous fluid in two phase spouted bed operated continuously with respect to the gas flow and batchwise with respect to the liquid was investigated using bed expansion technique. Experiments were carried out in three cylindrical spouted beds having diameters of 74 mm, 114 mm and 144 mm and height of 1000 mm under the conditions of superficial gas velocities between 0.0018 m·s–1 and 0.29 m·s–1, liquid viscosities between 0.063 Pa·s and 0.320 Pa·s, six static bed heights of 0.12 m, 0.18 m, 0.24 m, 0.30 m, 0.36 m and 0.48 m, surface tension between 0.0248 N·m–1 and 0.035 N·m–1 and density between 906 kg·m–3 to 928 kg· m–3 using a single nozzle sparger of 10.0 mm diameter. A correlation for the gas holdup was presented, with maximum deviation of 9%. This correlation was compared with those available in the literature.

Effect of a peripheral gas supply on the hydrodynamics of a spouting bed

The results of experimental investigations of the resistance of a pyramidal spouting bed with a peripheral gas supply are discussed, including the rates at the beginning and end of the process of spouting and material entrainment from an apparatus. Data is generalized in the form of dimensionless relations.

二段噴流層式石炭ガス化装置の開発

The application of the spouted bed technique to a coal gasifier has been studied in order to operate at the optimum temperature range of the gasification. The gasifier developed is composed of two parts. Jet-spouted bed reaction proceeds at the first stage in the lower part of the gasifier, and conventional spouted bed reaction at the second stage in the upper part of the gasifier. Regime maps of the jet spoutability and conventional spoutability in a column were determined.Taiheiyo coal was gasified with oxygen-steam mixtures in the dry ash mode under atmospheric pressure at temperatures up to 1350K. The effects of the oxygen/coal ratio and coal feed rate on the gasification performance were investigated. As a result, it was found that both the carbon conversion and thermal efficiency were mainly affected by the oxygen/coal ratio. The fractional conversion of carbon was 0.93 and cold gas thermal efficiency was 0.74 at the oxygen/coal ratio of 0.87. The product gases contained about 43% hydrogen and 20-30% carbon monoxide.The gasifier contains the jet-spouted bed where the partial combustion reaction mainly occurs so that the gasifier was able to be operated at around optimum gasification temperature as high as 1350K without clinkering troubles. The reactor has been demonstrated to be an efficient dry-ash coal gasifier for the production of good quality gases.

Continuous Drying of Slurry in a Jet Spouted Bed

ABSTRACT he performance of a laboratory scale jet spouted bed (JSB) for drying rice flour slurry was studied. The bed consisted of ceramic balls (5028 mm diameter) and the rice flour slurry was sprayed onto the moving particle surface near the inlet part. All the experiments were carried out at the jet spouting regime. This regime has high bed void fraction and violent movement and collision of bed particles. As a result, the dried product layer is attrited from particle surface as a fine powder and entrained from the bed by the spouting air. The experimental result were presented to show the effects of static bed height, inlet air flow rate and temperature, and feed concentration and flow rate on the outlet air temperature, thernal efficiency, and mean particle size and moisture content of the product. Asimple mathematical model, which is based on the conservation of mass and energy equations, was developed. Predicted results agreed well with those obtained from the experiment.

Flow and Drying Characteristics of a Rotatinc Jet Spouted Bed

Flow and Drying Characteristics of a Rotatinc Jet Spouted Bed

Hydrodynamics of nearly flat base spouted beds

The hydrodynamic behaviour of a nearly flat base spouted bed (angle 150▿) was studied in a pilot plant unit,using solids of different densities and particle diameters and with different values of the contactor inlet diameter. It was determined that the equation of Mathur and Gishler with an exponent of 0.10 for the ( D 0/ D c) modulus is suitable for calculation of the minimum spouting velocity. Original correlations for prediction of the maximum pressure drop, of the pressure drop for stable operation and of bed viodage in the bed expansion are proposed. It is proved that the maximum spoutable bed height can be calculated using the equation proposed by Morgan et al. for conventional spouted beds. For small particle diameters the equation of Malek and Lu is also valid.

Minimum spouting velocity in multiple spouted beds

AbstractStudies have been carried out in multiple spouted beds having 2, 3 and 4 spout cells; different fluid inlet orifices and different solids have been used with air and water as spouting fluids. The minimum spouting velocities are measured for different bed depths. The experimental data for particle Reynolds number at minimum spouting have been correlated and the square root mean deviation between the calculated and experimental values is found to be 8.75 %.