Hydrodynamic Characteristics of a Pilot-Scale Screw Conveyor Dryer

Waje, S. S.; Thorat, Bhaskar N.; Mujumdar, Arun S.

doi:10.1080/07373930701250120

Cited by 18 publications

(19 citation statements)

References 14 publications

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“…Tsai and Lin [9] qualitatively studied the effects of screw parameters (pitch, flight diameter, flight thickness and shaft diameter) and operating conditions (rotation speed) on the mixing quality in a single screw feeder. Their sampling and analysis method was updated by [14] for qualitatively analyzing the mixing degree in a screw dryer. Kingston and Heindel [8] analyzed sample homogeneity obtained from four different ports at the outlet, and the variance of the sampling was employed to characterize the mixing quality in a double screw mixer.…”

Section: Introductionmentioning

confidence: 99%

Numerical study of particle mixing in a lab-scale screw mixer using the discrete element method

Heindel

Wright

2017

Powder Technology

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This study employs the Discrete Element Method (DEM) to simulate particulate flow and investigate mixing performance of a lab-scale double screw mixer. The simulation employs polydispersed biomass and glass bead particles based on experiments conducted in previous studies. Visual examination of particle distribution and statistical analysis of particle residence times of experimental data served as model validation. Statistical analysis indicates a maximum 9.8% difference between the experimental and simulated biomass particle mean residence time, and visual observations suggest the simulation captures the particle mixing trends observed in the experiments. Results indicate that the particle mean mixing time, non-dimensionalized by ideal flow time in the plug flow reactor, varies between 1.008 and 1.172, and it approaches 1 with increasing biomass feed rate. The mixing index profile in the axial direction shows a mixing-demixing-mixing oscillation pattern. Increasing screw pitch length is detrimental to mixing performance; decreasing the solid particle feed rate reduces the mixing degree; and increasing the biomass to glass bead size ratio decreases mixing performance. A comparison of a binary, single-sized biomass and glass particles mixture to a multicomponent mixture indicates that the binary system has similar mixing pattern as a multicomponent system. These findings demonstrate that DEM is a valuable tool for the design and simulation of double screw mixing systems.

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Section: Introductionmentioning

confidence: 99%

Numerical study of particle mixing in a lab-scale screw mixer using the discrete element method

Heindel

Wright

2017

Powder Technology

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“…9 Waje et al conducted a series of experiments and published several papers about screw conveyor dryer. [10][11][12][13] They investigated residence time distribution (RTD) and mean residence time (MRT) in screw dryer conveyor and found out that with the increasing screw speed, degree of mixing is increased but MRT is decreased. The flow in a screw conveyor dryer approaches plug flow as the feed rate is increased, whereas an increase in the screw speed results in a mixed flow.…”

Section: Introductionmentioning

confidence: 99%

“…The discharge uniformity was found to be a strong function of the solids flow rate and the screw speed. 11 In this paper, the drying characteristics of woodchip dried in a screw dryer have been investigated and the optimum drying conditions have been determined.…”

Section: Introductionmentioning

confidence: 99%

Woodchip drying in a screw conveyor dryer

Kaplan

Celik

2012

Journal of Renewable and Sustainable Energy

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Moisture content of raw biomass materials is a crucial parameter for system efficiency and the main purpose of the drying process is to reduce moisture content of the wet biomass. In this study, the drying characteristics of woodchip dried in a screw conveyor dryer had investigated experimentally. The experimental results demonstrated that drying rate had increased with the increasing drying air temperature and flow rate; however, the amount of volatile organic matters in the sample has kept constant. Furthermore, the results have showed that the best drying conditions in this study is 30 m 3 /h drying airflow rate, 200 C drying air temperature, and co-current dryer type. With these conditions, moisture content of woodchip decreased from 60% to 27% (wet basis, mass %). V C 2012 American Institute of Physics.

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“…The single screw conveyors also present higher reaction conversion for positive-order kinetics due to a less backmixing [10]. However, most studies on screw conveyors are focused on the particle's axial backmixing performance rather than transverse mixing [11][12][13][14]. This may be due to the difficulty in measuring the real transverse mixing behavior in a screw mixer filled (or half filled) with opaque particles.…”

Section: Introductionmentioning

confidence: 99%

Characterization of transverse mixing in a screw mixer by image analysis

et al. 2015

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Transverse mixing of particles in a screw mixer is investigated by a digitized image analysis method coupled with solidification technique. The effects of screw rotation speed, filling level and particle size on the transverse mixing index and mixing rate constant are investigated experimentally. The results show that a decrease of screw rotation speed and filling level results in an increase in the mixing rate. Faster mixing is observed with large particles, and the mixing rate constant of coarse particles is 1.5~2 times higher than that of fine particles. Particle size difference of materials puts the particles at a risk of segregation.

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Hydrodynamic Characteristics of a Pilot-Scale Screw Conveyor Dryer

Cited by 18 publications

References 14 publications

Numerical study of particle mixing in a lab-scale screw mixer using the discrete element method

Numerical study of particle mixing in a lab-scale screw mixer using the discrete element method

Woodchip drying in a screw conveyor dryer

Characterization of transverse mixing in a screw mixer by image analysis

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