Experiment and Neural Network Model of Primary Fragmentation of Oil Shale in Fluidized Bed

Cui, Zhigang; Han, Xiangxin; Jiang, Xiumin; Liu, Jianguo

doi:10.3176/oil.2009.2.04

Cited by 7 publications

(5 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Besides pore structure change, the fragmentation of specimens during the retorting also helps to enhance the pore volume and specific surface area. It is well-known that primary fragmentation of fossil fuel particles can be induced by both the thermal stress from the temperature gradient and the internal pressure from the devolatilization. − In this work, the average heating rate is <10 °C/min and the size of all sample particles is <3.0 mm. Because of the slow heating rate, the temperature distribution within particles is relatively uniform and devolatilization is slow, so that high stress cannot be formed within sample particles.…”

Section: Resultsmentioning

confidence: 83%

Effects of Retorting Factors on Combustion Properties of Shale Char. 2. Pore Structure

et al. 2010

View full text Add to dashboard Cite

The devolatilization of solid fuels will cause remarkable changes to the pore structures of the resulting char particles, which has a significant influence on successive reactions, such as the combustion of the char particles and the formation of ash. In the present work, the pore structures of shale chars prepared under different retorting conditions were measured by employing a N2 adsorption−desorption method. On the basis of the measured results and thermal degradation mechanisms of the kerogen within oil shale, the effects of four retorting parameters on the pore structures of shale char were discussed. An elevating retorting temperature will notably increase the pore volume and specific surface area in shale char. However, at the higher retorting temperatures, the cracking and carbonization of residual organic matter within shale char become more intensive. Subsequently, the pores are easily blocked (especially small pores), and the specific surface area of the char particles decreases slightly. In terms of the residence time of retorting at a low temperature of 430 °C, sufficient residence time is required for forming more extensive porosity within shale char particles. The particle size and low heating rate were found to have little effect on the surface area and pore volume of shale char.

show abstract

Section: Resultsmentioning

confidence: 83%

Effects of Retorting Factors on Combustion Properties of Shale Char. 2. Pore Structure

et al. 2010

View full text Add to dashboard Cite

show abstract

“…An important step in the modeling process is a determination of the adequate number of neurons in the hidden layer. The optimal number of neurons in the hidden layer was determined by varying the number of hidden neurons and observing the root-mean-square error between the experimental results and the calculated output of the BP network . The number of neurons used for the hidden layer is optimized by trial-and-error training assays, and it is confirmed that choosing 11 hidden neurons can make the network model move toward convergence in a short time.…”

Section: Resultsmentioning

confidence: 95%

Morphological Characterization of Superfine Pulverized Coal Particles. 1. Fractal Characteristics and Economic Fineness

et al. 2009

View full text Add to dashboard Cite

Superfine pulverized coal combustion is a new pulverized coal combustion technology which has better combustion stability, higher combustion efficiency, lower NO x and SO 2 emissions, and higher comprehensive efficiency than when using conventional particle sizes. In this paper, we novelly applied both the classical single power law fractal dimension and a piecewise approach to analyze the particle-size distribution (PSD) of superfine pulverized coal particles. In addition, we introduced the fractal theory into scanning electron microscopy image analysis by adopting the slit island method. The grey relational analysis was used to study the degree of relative importance of the influencing factors about fractal dimensions. Furthermore, the piecewise characteristics of the PSD of coal particles were studied in detail. All curves on the log-log scale can be approximated by two intersecting lines, and each curve can be quantified by four variables. The grey relational analysis was also used for further study on the relationships between the four parameters. Finally, a new method for identifying the economic granule size of pulverized coal particles, that is, economic fineness based on the power consumption of coal mills, E 2 , was proposed by a utilizing neural network method. Final results indicate that the economic fineness of Shenhua pulverized coal particles based on E 2 is about 18.94, while that of Neimenggu pulverized coal particles is about 36.13. This provides some reference for a coal-fired power plant to confirm the economic granule size, which has certain guidance meaning for economical operation and low power consumption.

show abstract

“…Just as obtained in Ref. [12], the devolatilization and thermal stress have little effects on the fragmentation of small-size particles (<0.6 mm). As particle size increases, the platy structure becomes more obvious, which can still make whole particle temperature uniform and reach the critical temperature quickly, due to the heat transfer along the thickness direction.…”

Section: Effects Of Particle Size and Heating Rate On The Heating Promentioning

confidence: 85%

“…When the internal pressure and thermal stresses are larger than tensile failure strength of the oil shale particles, the primary fragmentation will occur to produce smaller particles [12].…”

Section: Analysis Of the Heat Transfer During The Retortingmentioning

confidence: 99%

“…Too short time for the retorting will make oil shale decompose incompletely, reducing oil yield; however, too long time for staying in the retorts will bring about a lot of heat loss. In addition, fast heating rate can form a large temperature gradient within oil shale particles and the resulting thermal stress fragmentation and devolatilizationinduced fragmentation of oil shale particles [12]. For analyzing the effects of thermal behavior inside oil shale particle, Braun and Rothman [13] coupled heat conduction with published literature data of Colorado oil shale to obtain a concise interpretation of the kinetics of oil production.…”

Section: Introductionmentioning

confidence: 98%

See 1 more Smart Citation

Heat transfer characteristic of oil shale particle during the retorting

Han

Liu

Jiang

2015

International Journal of Heat and Mass Transfer

View full text Add to dashboard Cite

Experiment and Neural Network Model of Primary Fragmentation of Oil Shale in Fluidized Bed

Cited by 7 publications

References 18 publications

Effects of Retorting Factors on Combustion Properties of Shale Char. 2. Pore Structure

Effects of Retorting Factors on Combustion Properties of Shale Char. 2. Pore Structure

Morphological Characterization of Superfine Pulverized Coal Particles. 1. Fractal Characteristics and Economic Fineness

Heat transfer characteristic of oil shale particle during the retorting

Contact Info

Product

Resources

About