• Title, Summary, Keyword: Random Pore Model

Search Result 20, Processing Time 0.045 seconds

Study of Pore Development Model in Low Rank Solid Fuel Using FERPM (FERPM을 적용한 저등급 고체연료의 기공발달 모델 특성 연구)

  • PARK, KYUNG-WON;KIM, GYEONG-MIN;JEON, CHUNG-HWAN
    • Transactions of the Korean hydrogen and new energy society
    • /
    • v.30 no.2
    • /
    • pp.178-187
    • /
    • 2019
  • Due to the increasing demand of high rank coal, the use of low rank coal, which has economically advantage, is rising in various industries using carbonaceous solid fuels. In addition, the severe disaster of global warming caused by greenhouse gas emissions is becoming more serious. The Republic of Korea set a goal to reduce greenhouse gas emissions by supporting the use of biomass from the Paris International Climate Change Conference and the 8th Basic Plan for Electricity Supply and Demand. In line with these worldwide trends, this paper focuses on investigating the combustibility of high rank coal Carboone, low rank coal Adaro from Indonesia, Baganuur from Mongolia and, In biomass, wood pellet and herbaceous type Kenaf were simulated as kinetic reactivity model. The accuracy of the pore development model were compared with experimental result and analyzed using carbon conversion and tau with grain model, random pore model, and flexibility-enhanced random pore model. In row lank coal and biomass, FERPM is well-matched kinetic model than GM and RPM to using numerical simulations.

Effect of Pore Geometry on Gas Adsorption: Grand Canonical Monte Carlo Simulation Studies

  • Lee, Eon-Ji;Chang, Rak-Woo;Han, Ji-Hyung;Chung, Taek-Dong
    • Bulletin of the Korean Chemical Society
    • /
    • v.33 no.3
    • /
    • pp.901-905
    • /
    • 2012
  • In this study, we investigated the pure geometrical effect of porous materials in gas adsorption using the grand canonical Monte Carlo simulations of primitive gas-pore models with various pore geometries such as planar, cylindrical, and random pore geometries. Although the model does not possess atomistic level details of porous materials, our simulation results provided many insightful information in the effect of pore geometry on the adsorption behavior of gas molecules. First, the surface curvature of porous materials plays a significant role in the amount of adsorbed gas molecules: the concave surface such as in cylindrical pores induces more attraction between gas molecules and pore, which results in the enhanced gas adsorption. On the contrary, the convex surface of random pores gives the opposite effect. Second, this geometrical effect shows a nonmonotonic dependence on the gas-pore interaction strength and length. Third, as the external gas pressure is increased, the change in the gas adsorption due to pore geometry is reduced. Finally, the pore geometry also affects the collision dynamics of gas molecules. Since our model is based on primitive description of fluid molecules, our conclusion can be applied to any fluidic systems including reactant-electrode systems.

Gasification reactivity of Chinese Shinwha Coal Chars with Steam (스팀을 이용한 중국산 신화 석탄 촤 가스화 반응에 관한 연구)

  • Kang, Min-Woong;Seo, Dong-Kyun;Kim, Yong-Tak;Hwang, Jung-Ho
    • Journal of the Korean Society of Combustion
    • /
    • v.15 no.1
    • /
    • pp.22-29
    • /
    • 2010
  • In this study, carbon conversion was measured using an electronic mass balance. In a lab scale furnace, each coal sample was pyrolyzed in a nitrogen environment and became coal char, which was then gasified with steam under isothermal conditions. The reactivity of coal char was investigated at various temperatures and steam concentrations. The VRM(volume reaction model), SCM(shrinking core model), and RPM(random pore model) were used to interpret experimental data. For each model the activation energy(Ea), pre-exponential factor (A), and reaction order(n) of the coal char-steam reaction were determined by applying the Arrhenius equation into the data obtained with thermo-gravimetric analysis(TGA). According to this study, it was found that experimental data agreed better with the VRM and SCM for 1,000 and $1,100^{\circ}C$, and the RPM for 1,200 and $1,300^{\circ}C$. The reactivity of chars increased with the increase of gasification temperature. The structure parameter(${\psi}$) of the surface area for the RPM was obtained.

The Effect of Micro-Pore Configuration on the Flow and Thermal Fields of Supercritical CO2

  • Choi, Hang-Seok;Park, Hoon-Chae;Choi, Yeon-Seok
    • Environmental Engineering Research
    • /
    • v.17 no.2
    • /
    • pp.83-88
    • /
    • 2012
  • Currently, the technology of $CO_2$ capture and storage (CCS) has become the main issue for climate change and global warming. Among CCS technologies, the prediction of $CO_2$ behavior underground is very critical for $CO_2$ storage design, especially for its safety. Hence, the purpose of this paper is to model and simulate $CO_2$ flow and its heat transfer characteristics in a storage site, for more accurate evaluation of the safety for $CO_2$ storage process. In the present study, as part of the storage design, a micro pore-scale model was developed to mimic real porous structure, and computational fluid dynamics was applied to calculate the $CO_2$ flow and thermal fields in the micro pore-scale porous structure. Three different configurations of 3-dimensional (3D) micro-pore structures were developed, and compared. In particular, the technique of assigning random pore size in 3D porous media was considered. For the computation, physical conditions such as temperature and pressure were set up, equivalent to the underground condition at which the $CO_2$ fluid was injected. From the results, the characteristics of the flow and thermal fields of $CO_2$ were scrutinized, and the influence of the configuration of the micro-pore structure on the flow and scalar transport was investigated.

A Probabilistic Analysis of Liquefaction Potential and Pore Water Pressure Build up due to Earthquake (지진하중에 의한 액화의 가능성과 간극수압의 발생에 관한 확률론적 연구)

  • Kim, Young-Su;Lee, Song;Cho, Woo-Chul
    • Geotechnical Engineering
    • /
    • v.8 no.2
    • /
    • pp.31-44
    • /
    • 1992
  • The probabilistic and statistical model is used to estimate the probability of liquefaction potential and pore water pressure build up due to earthquake in fully saturated sand deposit for each case of being structure(anisotropic) or not(isotropic). To execute this paper, dynamic shear strength parameters to show the relationship between shear strength and cyclic loading under isotropic or anisotropic condition in saturated sand deposit are presented. Using these parameters, the program which Predicts Pore water Pressure build up due to earthquake is developed. Using the 3-dimensional Random Field Model considering uncertainty of resistance and strength parameter, the program which computes the probability of liquefaction potential is developed. The developed program is applied to a case study, and then the result shows that the probability of liquefaction in isotropic condition is higher than in anisotropic condition. The ratio of pore water pressure tends to decrease as Kc increases.

  • PDF

Kinetic Studies of CO2 Gasification by Non-isothermal Method on Fly Ash Char (비등온법에 의한 비산재 촤의 CO2 가스화 특성)

  • Kang, Suk-Hwan;Ryu, Jae-Hong;Lee, Jin-Wook;Yun, Yongseung;Kim, Gyoo Tae;Kim, Yongjeon
    • Korean Chemical Engineering Research
    • /
    • v.51 no.4
    • /
    • pp.493-499
    • /
    • 2013
  • For the purpose of utilizing fly ash from gasification of low rank coal, we performed the series of experiments such as pyrolysis and char-$CO_2$ gasification on fly ash by using the thermogravimetric analyzer (TGA) at non-isothermal heating conditions (10, 20 and $30^{\circ}C/min$). Pyrolysis rate has been analyzed by Kissinger method as a first order, the reliability of the model was lower because of the low content of volatile matter contained in the fly ash. The experimental results for the fly ash char-$CO_2$ gasification were analyzed by the shrinking core model, homogeneous model and random pore model and then were compared with them for the coal char-$CO_2$ gasification. The fly ash char (LG coal) with low-carbon has been successfully simulated by the homogeneous model as an activation energy of 200.8 kJ/mol. In particular, the fly ash char of KPU coal with high-carbon has been successfully described by the random pore model with the activation energy of 198.3 kJ/mol and was similar to the behavior for the $CO_2$ gasification of the coal char. As a result, the activation energy for the $CO_2$ gasification of two fly ash chars don't show a large difference, but we can confirm that the models for their $CO_2$ gasification depend on the amount of fixed carbon.

Kinetic Study of Coal/Biomass Blended Char-CO2 Gasification Reaction at Various temperature (다양한 온도에서 석탄/바이오매스의 혼합 촤-CO2 가스화 반응특성 연구)

  • Kim, Jung Su;Kim, Sang Kyum;Cho, Jong Hoon;Lee, Si Hoon;Rhee, Young Woo
    • Korean Chemical Engineering Research
    • /
    • v.53 no.6
    • /
    • pp.746-754
    • /
    • 2015
  • In this study, we investigated the effects of the temperature on the coal/biomass $char-CO_2$ gasification reaction under isothermal conditions of $700{\sim}900^{\circ}C$ using the lignite(Indonesia Eco coal) with biomass (korea cypress). Ni catalysts were impregnated on the coal by the ion-exchange method. Four kinetic models which are shrinking core model (SCM), volumetric reaction model (VRM), random pore model (RPM) and modified volumetric reaction model (MVRM) for gas-solid reaction were applied to the experimental data against the measured kinetic data. The Activation energy of Ni-coal/biomass, non-catalyst coal/biomass $Char-CO_2$ gasification was calculated from the Arrhenius equation.

Low-rank Coal Char Gasification Research with Mixed Catalysts at Fixed Reactor (고정층 반응기에서의 저등급 석탄 혼합촉매가스화 반응특성)

  • An, Seung Ho;Park, Ji Yun;Jin, Gyoung Tae;Rhee, Young Woo
    • Korean Chemical Engineering Research
    • /
    • v.55 no.1
    • /
    • pp.99-106
    • /
    • 2017
  • In this study, mixed catalytic char gasification of Indonesia low-rank coal Kideco was investigated under nitrogen atmosphere and isothermal conditions at a fixed reactor. The effects of the temperature were investigated at various temperature (700, 750, 800, $850^{\circ}C$). The effects of blend ratio of catalysts ($K_2CO_3$, Ni) were investigated with different blend ratios (1:9, 3:7, 5:5, 7:3 and 9:1). The sample was prepared by mixing with $K_2CO_3$ physically and by ionexchange method with Ni. The data from thermogravimetric analyzer and gas chromatography were applied to four gassolid reaction kinetic models including shrinking core model, volumetric reaction model, random pore model and modified volumetric reaction model.

Study on the Combustion Reactivity of Residual Oil as a New Fuel for Power Generation (발전용 신종액체 연료의 연소반응성 해석)

  • Park, Ho-Young;Seo, Sang-Il;Kim, Young-Joo;Kim, Tae-Hyung;Chung, Jae-Hwa;Lee, Sung-Ho;Ahn, Kwang-Ick;Jeong, Young-Gap
    • Transactions of the Korean hydrogen and new energy society
    • /
    • v.22 no.4
    • /
    • pp.534-545
    • /
    • 2011
  • This paper describes the evaluation of kinetic parameters for pyrolysis and carbon char oxidation of residual oil. The non-isothermal pyrolysis of residual oil was carried out with TGA (Thermo-Gravimetric Analyzer) at heating rate of 2, 5, 10 and $20^{\circ}C/min$ up to $800^{\circ}C$ under N2 atmosphere. The first order and nth order pyrolysis models were used to fit the experimental data, and the nth order model was turned out to follow the experimental data more precisely than the first order model. For carbon char oxidation experiment, TGA and four heating rates used in pyrolysis experiment were also adapted. The kinetic parameters for the residual carbon char particle were obtained with three char oxidation model, that is, volume reaction, grain and random pore model. Among them, the random pore model described the char oxidation behaviour quite well, compared to other two models. The non-linear regression method was used to obtain kinetic parameters for both pyrolysis and carbon char oxidation of residual oil.

Reaction Rate Analysis of Combustion for Indonesian Coal Char Applied by External/Internal Diffusion (외부 및 내부 확산을 적용한 인도네시아 석탄촤의 연소 반응율 분석)

  • Hwang, Chan-Won;Kim, Ryang-Gyoon;Ryu, Kwang-Il;Wu, Ze-Lin;Jeon, Chung-Hwan
    • Korean Chemical Engineering Research
    • /
    • v.52 no.1
    • /
    • pp.133-140
    • /
    • 2014
  • The experiment was designed to compare the char combustion kinetics of pulverized Indonesia coals commonly utilized in Korea power plants. The reaction rate of coal char has been formulated using the external and internal effectiveness factors to describe the diffusion effect quantitatively. The Random Pore Model (RPM) was used for applying internal specific surface area as a function of carbon conversion ratio. Reaction rate was obtained from reaction time using the Wire Heating Reactor (WHR) which can heat and measure the char particle temperature at the same time. BET and TGA were used to obtain physical properties such as internal specific surface area and structural parameter. Three kinds of Indonesia Sub-bituminous coals "BARAMULTI, ENERGYMAN, AGM" were used in order to derive the activation energy and pre-exponential factor. The results of this study showed that the effect of internal diffusion than that of external diffusion is the dominant as comparison of kinetics was reflected in external and internal effectiveness factors. For three kinds of coal char, finally, activation energy of intrinsic kinetics indicates 110~118 kJ/mol.