• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.165-166
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• 2014

The application of particle reaction model in the packed bed process modeling is discussed for iron ore pellet induration process. Combustion of coke breeze in the pellet is estimated by using shrinking unreacted-core model and grain model in which the progress of chemical reaction is described in different concepts. Under the identical inlet gas and solid conditions, the calculation using shrinking core model showed deviated results in terms of temperature profile and conversion fraction, which may imply the significance of selecting proper particle reaction model in consideration of particle characteristics and process operation conditions.

• 한국연소학회:학술대회논문집
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• 2015.12a
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• pp.325-326
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• 2015

Combustion of coke grains in a pellet used to be modeled using the shrinking core model in the previous indurator simulations. This leads to the discussions about its propriety due to the fundamental assumptions of the model inconsistent with the particle characteristics. The current study presents the grain model as an improvemen, and the differently used reaction models are compared. In addition, the simulations assuming changed particle conditions are conducted to display the effects of using the grain model.

• Nuclear Engineering and Technology
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• v.50 no.1
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• pp.145-150
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• 2018

A new methodology, the crack-spallation model, has been developed to analyze gas-solid reactions dominated by crack growth inside of the solid reactant and spallation phenomena. The new model physically represents three processes of the reaction progress: (1) diffusion of gas reactant through pores; (2) growth of product particle in pores; and (3) crack and spallation of solid reactant. The validation of this method has been conducted by comparison of results obtained in an experiment for oxidation of $UO_2$ and the shrinking core model. The reaction progress evaluated by the crack-spallation model shows better agreement with the experimental data than that evaluated by the shrinking core model. To understand the trigger point during the reaction progress, a detailed analysis has been conducted. A parametric study also has been performed to determine mass diffusivities of the gas reactant and volume increase constants of the product particles. This method can be appropriately applied to the gas-solid reaction based on the crack and spallation phenomena such as the voloxidation process.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.1
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• pp.119-125
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• 1999

This research has been studied in terms of investigating the reaction behavior of pyrite with a cyclone reactor. The Mathematical model has developed pyrite oxidation and lime sulfation in this reactor. The model assumes a chemical control shrinking core behavior for the pyrite and a fluid film control shrinking core behavior for the lime. The model was solved and characterized numerically. Experiments have been performed to study the influence of reaction parameters such as reactor temperatures, pyrite particle sizes, air flow rates, feeding rates, and mixing ratio of pyrite and lime. The oxidation and sulfation products were characterized chemically and physically.

• Korean Chemical Engineering Research
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• v.49 no.3
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• pp.372-380
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• 2011

Char gasification is affected by operating conditions such as reaction temperature, reactants gas partial pressure, total system pressure and particle size in addition to chemical composition and physical structure of char. The aim of the present work was to characterize the effect of coal particle size on $CO_{2}$ gasification of chars prepared from two different types of bituminous coals at different reaction temperatures(1,000-$1,400{^{\circ}C}$). Lab scale experiments were carried out at atmospheric pressure in a fixed reactor where heat was supplied into a sample of char particles. When a flow of $CO_{2}$(40 vol%) was delivered into the reactor, the char reacted with $CO_{2}$ and was transformed into CO. Carbon conversion of the char was measured using a real time gas analyzer having NDIR CO/$CO_{2}$ sensor. The results showed that the gasification reactivity increased as the particle size decreased for a given temperature. The sensitivity of the reactivity to particle size became higher as the temperature increases. The size effects became remarkably prominent at higher temperatures and became a little prominent for lower reactivity coal. The particle size and coal type also affected reaction models. The shrinking core model described better for lower reactivity coal, whereas the volume reaction model described better for higher reactivity coal.

• Korean Chemical Engineering Research
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• v.48 no.1
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• pp.16-19
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• 2010

Devolatilization characteristics of municipal wood waste were measured by using an isothermal thermogravimetric analyzer(TGA) and discussed. Volatile matter was mainly released at temperatures between $250^{\circ}C$ and $350^{\circ}C$. The volatile content increased with an increase of temperature but levelled off at temperatures ${\geq}527^{\circ}C$. The rate of devolatilization could be expressed by a shrinking particle model which was ruled by the reaction rate. The activation energy ranged from 13.1 to 18.5 kJ/g mol.

• Elastomers and Composites
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• v.37 no.2
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• pp.124-133
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• 2002

Waste PBT powder was depolymerized by saponification under the mild temperature conditions($80{\sim}110^{\circ}C$) and atmospheric pressure. In depolymerization of PBT, sodium hydroxide was more effective than potassium hydroxide. The depolymerization increased with increasing reaction temperature and decreasing particle size. The reaction kinetics of depolymerization could be expressed by the shrinking unreacted core model without product layer, in which the surface reaction was a rate determining step. The activation energy was 98.1 KJ/mol. The recovery ratio of the TPA obtained from the depolymerized PBT particles of 85.1 and $105{\mu}m$ for 6 hours was about 95%.

• Journal of Environmental Science International
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• v.30 no.6
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• pp.429-439
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• 2021

Food waste is both an industrial and residential source of pollution, and there has been a great need for food waste reduction. As a preliminary step in this study, waste reduction is quantitatively modeled. This study presents two models based on kinetics: a simple kinetic model and a mass transport-shrinking model. In the simple kinetic model, the smaller is the reaction rate constant ratio k₁, the lower the rate of conversion from the raw material to intermediate products. Accordingly, the total elapsed reaction time becomes shorter. In the mass transport-shrinking model, the smaller is the microbial decomposition resistance versus the liquid mass transfer resistance, the greater is the reduction rate of the radius of spherical waste particles. Results showed that the computed reduction of waste mass in the second model agreed reasonably with that obtained from a few experimantal trials of biodegradation, in which the microbial effect appeared to dominate. All calculations were performed using MATLAB 2020 on PC.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1997.06a
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• pp.53-60
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• 1997

The roasting of pyrite with a cyclone reactor have been studied in terms of investigating the reaction behavior of pyrite. The development of a fundamental model for pyrite oxidation and lime sulfation in a vertical cyclone reactor. The model assumes a chemical control shrinking core behavior for the pyrite and a fluid film control shrinking core behavior for the lime. The oxygen and sulphur dioxide concentrations and the energy balance for the gas, pyrite and lime particles are solved. The model was solved and characterized numerically. Experiments have been performed to study the influence of reaction parameters such as reactor temperatures, pyrite particle sizes, air flow rates, feeding rates, and mixing ratio of pyrite and lime. The oxidation and sulfation products were characterized chemically and physically.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 1998.04a
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• pp.144-153
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• 1998

Sorbents of calcined limestone and oyster particles having a diameter of about 0.63mm were exposed to simulate fuel gases containing 5000ppmv H2S for temperatures ranging from 600 to 800C in a TGA. The reaction between CaO and H2S proceds via an unreacted shrinking core mechanism. The sulfidation rate is likely to be controlled primarily by countercurrent diffusion through the product layer of calcium sulfide(CaS) formed. The kinetics of the sorption of H2S by CaO is sensitive to the reaction temperature and particle size, and the reaction rate of oyster was faster than the calcined limestone.