Korean Journal of Chemical Engineering (v.24, #3)
Controlled output variance based diagnosis tree for feedforward/cascade control systems by Junghui Chen; Cho-Kai Kong (379-390).
This paper aims at providing a framework for detection and diagnosis of the performance of a combinational feedforward (FF) and cascade (CC) control system. It is the extension of our previous work [1,2]. The main idea is to extract the only CC effect and the combination of FF with CC effects, respectively. In the only CC effect, the output variances of the primary and the secondary loops can be turned into the cascade-invariant and cascade-dependent terms, respectively. The combination of FF with CC effect can also be decomposed into the cascade/feedforward invariant term, the cascade-invariant/feedforward-dependent term and the cascade/feedforward dependent term. The diagnosis tree based on these decomposition terms is proposed to assess the performance of the FF/CC control system. The sequence of the statistical inference system is developed to diagnose fault causes. The capability of the proposed method is demonstrated via a cascade control system with the feedforward loops and multiple faults.
Keywords: Cascade Control; Control Loop Performance; Feedforward Control; Monitoring and Diagnosis
Effects of desorbent flowrate on simulated moving bed process by Young-Il Lim (391-396).
This article presents the effects of the desorbent flowrate (or m1) on simulated moving bed (SMB) process performance at constant m2, m3 and m4, where the m-values (m j ) are defined as the net flowrate ratios of the zone, j, to the solid flowrate. A complete m-plane analysis of SMB systems (ComPASS) has been developed that illustrates how the desorbent flowrate is determined within the complete m-plane (i.e., fluid-solid flowrate ratio plane) to enhance the SMB process performance. The effects of desorbent flowrate are presented numerically for linear/equilibrium and nonlinear/nonequilibrium SMB processes. The results of the studies using ComPASS show that for linear/equilibrium SMB process, it is desirable to determine the minimum desorbent flowrate (m1) within the complete separation region. For the nonlinear/nonequilibrium SMB process, the desorbent flowrate can be determined at the minimum value which maximizes the raffinate purity.
Keywords: Simulated Moving Bed (SMB) Chromatography; Desorbent Consumption; Triangle Theory; Process Simulation and Optimization; Complete m-Plane Analysis of SMB Systems (ComPASS)
Synthesis of nanocrystalline alumina by thermal decomposition of aluminum isopropoxide in 1-butanol and their applications as cobalt catalyst support by Kamonchanok Pansanga; Okorn Mekasuwandumrong; Jongjai Panpranot; Piyasan Praserthdam (397-402).
Nanocrystalline alumina powders were prepared by thermal decomposition of aluminum isopropoxide (AIP) in 1-butanol at 300 °C for 2 h and employed as cobalt catalyst supports. The crystallization of alumina was found to be influenced by the concentration of AIP in the solution. At low AIP content, wrinkled sheets-link structure of γ-Al2O3 was formed, while at high AIP concentrations, fine spherical particles of χ-Al2O3 were obtained. It was found that using these fine particles alumina as cobalt catalyst supports resulted in much higher amounts of cobalt active sites measured by H2 chemisorption and higher CO hydrogenation activities.
Keywords: Nanocrystalline Alumina; Thermal Decomposition; Cobalt Catalyst; Solvothermal Method; CO Hydrogenation
Effect of cocatalyst on the chemical composition distribution and microstructure of ethylene-hexene copolymer produced by a metallocene/Ziegler-Natta hybrid catalyst by Hai Woong Park; Kyung Won La; Jin Suk Chung; In Kyu Song (403-407).
A silica-magnesium bisupport (SMB) was prepared by a sol-gel method for use as a support for metallocene/Ziegler-Natta hybrid catalyst. The SMB was treated with methylaluminoxane (MAO) prior to the immobilization of TiCl4 and rac-Et(Ind)2ZrCl2. The prepared rac-Et(Ind)2ZrCl2/TiCl4/MAO/SMB catalyst was applied to the ethylenehexene copolymerization with a variation of cocatalyst species (polymerization run 1: triisobutylaluminum (TIBAL) and methylaluminoxane (MAO), polymerization run 2: triethylaluminum (TEA) and methylaluminoxane (MAO)). The effect of cocatalysts on the chemical composition distributions (CCDs) and microstructures of ethylene-hexene copolymers was examined. It was found that the catalytic activity in polymerization run 1 was a little higher than that in polymerization run 2, because of the enhanced catalytic activity at the initial stage in polymerization run 1. The chemical composition distributions (CCDs) in the two copolymers showed six peaks and exhibited a similar trend. However, the lamellas in the ethylene-hexene copolymer produced in polymerization run 1 were distributed over smaller sizes than those in the copolymer produced in polymerization run 2. It was also revealed that the rac-Et(Ind)2ZrCl2/TiCl4/MAO/SMB catalyst preferably produced the ethylene-hexene copolymer with non-blocky sequence when TEA and MAO were used as cocatalysts.
Keywords: Metallocene/Ziegler-Natta Hybrid Catalyst; Ethylene-Hexene Copolymer; Chemical Composition Distribution (CCD); Microstructure; Cocatalyst
Homology search of genus Pleurotus using an internal transcribed spacer region by Du Bok Choi; Ji Lu Ding; Wol-Suk Cha (408-412).
In order to establish the phylogenetic relationships of genus Pleurotus, internal transcribed spacer (ITS) regions of nine strains of mushrooms were amplified and sequenced. Fungi-Seq-F1 primer and fungi-Seq-R1 were perfectly matched with 2007 and 2935 kinds of fungi, respectively. These results show that these primers can be used not only in the types of mushroom used in this study, but also in DNA sequencing analysis of the ITS region of any other mushroom. A BLAST search using about 500 bp of the 5′ terminus of ITS region was carried out. The observed homology between some mushrooms and the ITS region was 98–100%. In order to investigate these results, we searched the GenBank databases. At the time of our search, the ITS region of the mushrooms was unknown and could not be found in the results of our database search in GenBank. Therefore, whole DNA sequencing of ITS region of the mushroom is considered to be of critical significance in view of future phylogenetic analyses. Additionally, the sequences of four mushrooms were aligned and showed 95–98% of homology.
Keywords: Pleurotus ; ITS Region; Homology
Classification of particles in particle-laden stream through a stainless steel fibrous filter by Cheng-Hsiung Huang; Chung-Liang Chang; Tser-Sheng Lin (413-417).
This investigation experimentally explores the penetration curve of particles shot onto a stainless steel fibrous filter or a flat surface. The effect of the pore size of the stainless steel fibrous filter, with or without an oil coating, on the particle penetration was examined at various flow rates, nozzle diameters and dimensionless particle diameters, Sqrt(Stk). The penetration of the flat surface by particles was also determined for comparison. Experimental results demonstrate that oleic acid particles larger than Sqrt(Stk)50 are collected on the stainless steel fibrous filter with a low penetration, while smaller particles stay in the particle-laden stream with high penetration. The penetration of potassium chloride particles exceeds that of oleic acid particles, because potassium chloride particles bounce off the stainless steel fibrous filter and the flat surface. Particles bounce off the metal filter less easily than the flat surface. Coating the stainless steel fibrous filter with oil effectively reduces problems of particle bounce. The potassium chloride particles sucked the coated oil forming a small mountain on the surface. When the loaded particle mass on the coated stainless steel fibrous filter ranges between 0.4 and 2.3 mg, Sqrt(Stk)50 is a constant 0.35.
Keywords: Classification; Penetration; Particle; Stainless Steel Fibrous Filter; Particle-laden Stream
New numerical model for solubility of light alkanes in triethylene glycol by Alireza Bahadori (418-425).
A new numerical model, which covers the full range of dehydration-plant operating conditions and wide range of experimental data results, estimates the amount of CH4, C2H6 and C3H8 absorbed per volume of triethylene glycol (TEG) circulated vs. the partial pressure of light alkanes and the absorber temperature. This article shows that the proposed numerical approach is more accurate than routine equation of states in predicting the solubility of light hydrocarbons in TEG. This article also provides comparisons between the results of the proposed model with experimental data and an equation of state results.
Keywords: Alkane; Solubility; Gas Dehydration; Numerical Model
Arsenic adsorption mechanism on clay minerals and its dependence on temperature by Debasish Mohapatra; Debaraj Mishra; Gautam Roy Chaudhury; Radhanath Prasad Das (426-430).
In the present study, the As(V) removal efficiency of different clay minerals was investigated as a function of solution pH, time, As(V) concentration, and temperature. Arsenic mobility was also investigated by determining the As(V) released from the loaded samples by leaching with various aqueous solutions. The kinetics of adsorption was observed to be fast and reached equilibrium within 3 h. As(V) adsorption on studied clays was pH dependent and maximum adsorption was achieved at pH 5.0. The maximum adsorption capacity was calculated by fitting the Langmuir equation to the adsorption isotherms and found to be 0.86, 0.64, and 0.52 mg As(V)/g of kaolinite, montmorillonite, and illite, respectively. The negative effect of temperature on As(V) adsorption showed the interactions to be exothermic. Based on the results, it was found that among the studied clay minerals, kaolinite was the best As(V) adsorbent and montmorillonite had strong retention capacity. The electrokinetic behavior of kaolinite and montmorillonite was modified in the presence of As(V), indicating that adsorption involves inner sphere surface complexation and strong specific ion adsorption.
Keywords: Adsorption; Leaching; Arsenic; Clay; Langmuir Isotherm; Isoelectric Point
Influence of polyethylene oxide on absorption of carbon dioxide into aqueous N-methyldiethanolamine solution by Sang-Wook Park; Byoung-Sik Choi; Jae-Wook Lee (431-435).
Carbon dioxide was absorbed into aqueous polyethylene oxide (PEO) solution containing N-methyldiethanolamine (MDEA) in a flat-stirred vessel to investigate the effect of non-Newtonian rheological behavior of PEO on the chemical absorption rate of CO2, where the reaction between CO2 and MDEA was assumed to be a first-order reaction with respect to the concentration of CO2 and MDEA, respectively. A unified correlation equation containing the Deborah number, which reflects the viscoelastic properties of a non-Newtonian liquid, was used to obtain the volumetric liquid-side mass transfer coefficient of carbon dioxide in aqueous PEO solution. The elastic properties of PEO accelerated the absorption rate of CO2 compared with that of a Newtonian liquid based on the same values of viscosity.
Keywords: Absorption; Carbon Dioxide; Polyethylene Oxide; N-Methyldiethanolamine; Viscoelastic Liquid
Recovery of magnetic ionic liquid [bmim]FeCl4 using electromagnet by Sang Hyun Lee; Sung Ho Ha; Chun-Yeol You; Yoon-Mo Koo (436-437).
Recovery of 1-butyl-3-methylimidazolium tetrachloroferrate ([bmim]FeCl4) from its mixture with water was investigated. The [bmim]FeCl4 rich phase in the mixture forming two-phase was successfully separated, while homogeneous mixtures could not be separated. However, the concentration of the homogeneous mixture varied as a function of the magnetic field strength. Therefore, a combination of magnetic field and conventional methods to recover magnetic ILs from reaction mixtures will be very useful and have great potential.
Keywords: Magnetic Ionic Liquid; Magnetic Behavior; Electromagnet; Reuse; Separation
Comparison of distillation arrangement for the recovery process of dimethyl sulfoxide by Jungho Cho; Dong Min Kim (438-444).
In this study, computer modeling and comparative works have been performed to obtain highly pure dimethyl sulfoxide (DMSO) which is used for fiber spinning solvent for two different distillation sequences. These two distillation sequences remove methanol and water and recover DMSO solvent from the mixture of methanol and water using two distillation columns. Non random two liquid mixture (NRTL) liquid activity coefficient model was used for the modeling of each binary vapor-liquid equilibria for DMSO, methanol and water systems and we used PRO/II with PROVISION release 7.1 as a commercial chemical process simulator. As a result of computational simulation, we obtained a highly pure DMSO with its purity over 99.9 wt% and water contents which is main impurity was very low weight percent under 500 ppm.
Keywords: Direct Sequence; Indirect Sequence; Dimethyl Sulfoxide; NRTL Liquid Activity Coefficient Model; Simulation; Modeling
Simulation of bubbling fluidized bed of fine particles using CFD by Jimin Kim; Gui Young Han (445-450).
Computational fluid dynamics (CFD) simulation for bubbling fluidized bed of fine particles was carried out. The reliability and accuracy of CFD simulation was investigated by comparison with experimental data. The experimental facility of the fluidized bed was 6 cm in diameter and 70 cm in height and an agitator of pitched-blade turbine type was installed to prevent severe agglomeration of fine particles. Phosphor particles were employed as the bed material. Particle size was 22 μm and particle density was 3,938 kg/m3. CFD simulation was carried by two-fluid module which was composed of viscosity input model and fan model. CFD simulation and experiment were carried out by changing the fluidizing gas velocity and agitation velocity. The results showed that CFD simulation results in this study showed good agreement with experimental data. From results of CFD simulation, it was observed that the agitation prevents agglomeration of fine particles in a fluidized bed.
Keywords: Fluidized Bed; CFD; Fine Particle; Agglomeration
Examination of the surface properties of kaolinites by inverse gas chromatography: Acid-base properties by Young Cheol Yang; Pyoung Ran Yoon (451-456).
The specific component of the free energy of adsorption,-ΔG A SP , of untreated kaolinite and kaolinites surface-treated with isopropyl triisostearoyl titanate (ITT) and isopropyl tri(dioctylpyrophosphato) titanate (ITDT) was estimated, using the adsorption of several polar and non-polar probes on these surfaces at various measuring temperatures, by the inverse gas chromatography (IGC) method. The acid-base properties of the untreated kaolinite and surface-treated kaolinites were quantified by K A and K D parameters, reflecting the ability of the surface to act as an electron acceptor and donor, respectively. In the result, all kaolinite surfaces were amphoteric and were able to function as both an electron acceptor and an electron donor.
Keywords: Inverse Gas Chromatography (IGC); Specific Component of the Free Energy of Adsorption (ΔG A SP ); Enthalpy of Specific Adsorption (ΔH A SP ); Surface Acid-base Characteristics
Effect of water pretreatment on CO2 capture using a potassium-based solid sorbent in a bubbling fluidized bed reactor by Yongwon Seo; Sung-Ho Jo; Ho-Jung Ryu; Hee Dal Bae; Chong Kul Ryu; Chang-Keun Yi (457-460).
A bubbling fluidized bed reactor was used to study CO2 capture from flue gas by using a potassium-based solid sorbent, sorbKX35 which was manufactured by the Korea Electric Power Research Institute. A dry sorbent, sorbKX35, consists of K2CO3 for absorption and supporters for mechanical strength. To increase initial CO2 removal, some amount of H2O was absorbed in the sorbent before injecting simulated flue gas. It was possible to achieve 100% CO2 removal for more than 10 minutes at 60°C and a residence time of 2 s with H2O pretreatment. When H2O pretreatment time was long enough to convert K2CO3 of sorbKX35 into K2CO3 · 1.5H2O, CO2 removal was excellent. The results obtained in this study can be used as basic data for designing and operating a large scale CO2 capture process with two fluidized bed reactors.
Keywords: Solid Sorbent; Fluidized Bed Reactor; CO2 ; H2O Pretreatment
Co-combustion of Korean anthracite with bituminous coal in two circulating fluidized bed combustors by Dong Won Kim; Jong Min Lee; Jae Sung Kim; Jong Jin Kim (461-465).
The co-combustion characteristics for Korean anthracites and bituminous coals were determined in a lab-scale CFB reactor and the commercial scale Tonghae CFB Power Plant. In the lab-scale CFB combustion tests, the effluent rate of the emission gases, which can indicate the reactivity of the combustion, did not change appreciably when each coal burned. As the bituminous coal was added, however, the effluent rate of the emissions increased. The amount of the unburned carbon in ash decreased with increasing the ratio of the bituminous coal during the co-combustion. When the co-combustion was tested in the Tonghae CFB power plant, the temperatures at the upper part of the combustor and the cyclones, which were somewhat higher than designed and expected, could be reduced as the bituminous coal ratio increased. Consequently, more stable operation of the CFB boiler was achieved. The efficiency of the CFB boiler also increased due to increasing the reactivity of the combustion.
Keywords: CFB; Co-combustion; Korean Anthracite; Tonghae Boiler
Comparison of fractal properties of porous structures during coal devolatilization by Xiaoliang Wang; Rong He (466-470).
This paper investigates fractal property changes of pore structures during coal devolatilization. Similar to char pores, coal pores can also be classified as micro pores and macro pores based on their fractal dimensions. The specific surface area and fractal dimension of micro pores in coal particles are basically unchanged after devolatilization. However, the specific surface area and fractal dimension of macro pores, which are key factors in char combustion, are increased after devolatilization. In fact, the fractal dimensions are basically doubled. These parameters will affect another fractal geometrical factor β in char pores that is correlated to char combustion rate. Since the rate of char combustion can be predicted from their fractal pore properties, it may be possible to predict char combustion directly from the properties of their parent coal pores in the future.
Keywords: Fractal; Coal/Char; Pores; Devolatilization
Mass transfer and kinetics study on the sulfite forced oxidation with manganese ion catalyst by Zhao Bo; Li Yan; Zhuo Yuqun; Tong Huiling; Zhang Xiaowen; Chen Changhe (471-476).
Wet limestone scrubbing is the most common flue gas desulfurization process (FGD) for control of sulfur dioxide emissions from the combustion of fossil fuels. Forced oxidation, which controls the overall reaction of the sulfur dioxide absorption, is the key path of the process. Manganese which comes from the coal is one of the catalysts during the forced oxidation process. In the present work, the two-film theory was used to analyze the sulfite forced oxidation reaction with an image boundary recognition technique, and the oxidation rate was experimentally studied by contacting pure oxygen with a sodium sulfite solution. There was a critical sulfite concentration 0.328 mol/L without catalyst or at a constant catalyst concentration value. The kinetics study focused on the active energy of the reaction and the reaction constant k; furthermore, we obtained the order with respect to the sulfite and Mn2+ concentrations. When the Mn2+ catalyst concentration was kept unchanged, the sulfite oxidation reaction rate was controlled by dual film and the reaction kinetics was first order with respect to sulfite while SO 3 2− concentration was below 0.328 mol/L; the sulfite oxidation reaction rate was controlled by gas film only and the reaction kinetics was zero order with respect to sulfite while SO 3 2− concentration over 0.328 mol/L. When SO 3 2− concentration was kept unchanged, the sulfite oxidation reaction rate depended on gas-liquid mass transfer and the reaction kinetics was different in various stages with respect to Mn2+ concentrations.
Keywords: Kinetics; Forced Oxidation; Mass Transfer; Manganese Ion Catalyst
Performance of Ni catalyst supported on La-hexaaluminate in CO2 reforming of CH4 by Heeyeon Kim; Seung Jae Lee; Kwang Sup Song (477-480).
CO2 reforming of CH4 was performed using Ni catalyst supported on La-hexaaluminate which has been an well-known material for high-temperature combustion. La-hexaaluminate was synthesized by sol-gel method at various conditions where different amount of Ni (5–20 wt%) was loaded. Ni/La-hexaaluminate experienced 72 h reaction and its catalytic activity was compared with that of Ni/Al2O3, Ni/La-hexaaluminate shows higher reforming activity and resistance to coke deposition compared to the Ni/Al2O3 model catalyst. Coke deposition increases proportionally to Ni content. Consequently, Ni(5)/La-hexaaluminate(700) is the most efficient catalyst among various Ni/La-hexaaluminate catalysts regarding the cost of Ni in Ni(X)/La-hexaaluminate catalysts. BET surface area, XRD, EA, TGA and TPO were performed for surface characterization.
Keywords: CO2 Reforming of CH4 ; Ni; La-hexaaluminate; Al2O3 ; Coke Deposition
Mass transfer and reaction process of the wet desulfurization reactor with falling film by cross-flow scrubbing by Juncong Sai; Shaohua Wu; Rui Xu; Rui Sun; Yan Zhao; Yukun Qin (481-488).
In the present study, a series of wet flue gas desulfurization experiments have been carried out in comparison with different slurry feeding ways, i.e., by series connection and by parallel connection, by means of cross-flow scrubbing with falling film. The experiment results show that there is optimal desulfurization performance for the slurry feeding way by series connection. A liquid side mass transfer-reaction model and desulfurization mass transfer by cross-flow scrubbing model have been developed. The pH values of the outlet slurry inside the reactor and the ion concentration distributions of H2SO3, HSO 3 − and SO 3 2− along the axial direction of the tubes were obtained by analyzing and calculating the models. The calculation values agree well with the experimental values. It shows that the models can predict well the ion concentration distributions along the axial direction of the tubes.
Keywords: Cross-flow Scrubbing; Falling Film; Mass Transfer-reaction Process
Catalytic coal partial gasification in an atmospheric fluidized bed by Hongcang Zhou; Baosheng Jin; Zhaoping Zhong; Yaji Huang; Rui Xiao; Youfei Zheng (489-494).
The coal partial gasification catalyzed by limestone, sodium carbonate and dolomite was studied using a bench-scale atmospheric fluidized bed in the presence of air and steam at 900 °C. The effects of limestone, sodium carbonate and dolomite on composition, heating value, gas yield of product gas and carbon conversion in the catalytic coal partial gasification have been examined. The experimental results show that the catalysts can effectively improve the gas quality, the heating value and the gas yield of product gas and carbon conversion. The catalytic effect of sodium carbonate is better than that of limestone and dolomite. The increase of limestone loading can enhance the quality of product gas, such as the content of combustible gas, the high heating value and the gas yield, during coal partial gasification.
Keywords: Coal; Partial Gasification; Catalyze; Fluidized Bed
Life cycle emissions of greenhouse gas for ammonia scrubbing technology by Shujuan Wang; Fang Liu; Changhe Chen; Xuchang Xu (495-498).
It is thought that the CO2 emissions from coal-fired power plants contribute greatly to the total anthropogenic CO2 emissions. Ammonia solvent can be used to absorb the CO2, called ammonia scrubbing. However, as has been pointed out, the production of ammonia would emit CO2; therefore, the effectiveness of ammonia scrubbing is doubted. The paper focuses on the problem. Two systems are defined in the paper. System I is CO2 absorption by ammonia scrubbing, and system II is industrial production of ammonium bicarbonate. The total CO2 emissions of the two systems are calculated by means of life cycle assessment. The paper shows that the total CO2 emissions of ammonia scrubbing are less than that of the industrial production of fertilizer ammonium bicarbonate. It can be concluded that ammonia scrubbing is an effective way to reduce the anthropogenic CO2 emissions.
Keywords: Ammonia Scrubbing; CO2 Emissions; Life Cycle Assessment; Coal-fired Power Plant; Ammonia Bicarbonate
Investigation on characteristics of pulverized coal dense-phase pneumatic conveying under high pressure by Xiaoping Chen; Chunlei Fan; Cai Liang; Wenhao Pu; Peng Lu; Changsui Zhao (499-502).
Experiments of dense-phase pneumatic conveying of pulverized coal were carried out in a test facility with a conveying pressure up to 4 MPa. The influence of fluidization nitrogen flow rate, the flow rate of supplementary nitrogen, and the pressure difference between sending hopper and receiving hopper on the solids to gas ratio and the solid mass flow rate was investigated. Test results indicate that with the increase in fluidization nitrogen flow rate, the solid mass flow rate increases, and the solids to gas ratio increases at first and then declines. When the fluidization of pulverized coal in the sending vessel becomes intensive, with the increase in supplementary nitrogen flow rate, the solids to gas ratio declines and the solid mass flow rate increases. And the solid mass flow rate increases linearly with the increase in pressure difference between two hoppers. The experimental results provide a database for the design and operation of a dense-phase pneumatic conveying system.
Keywords: Pneumatic Conveying; Dense Phase; Pulverized Coal; High Pressure; Two Phase Flow
Influences of A- or B-site substitution on the activity of LaMnO3 perovskite-type catalyst in oxidation of diesel particle by Bailei He; Qiang Song; Qiang Yao; Zhongwei Meng; Changhe Chen (503-507).
LaMnO3 was partially substituted at A- or B-site by Sol-Gel method and characterized by XRD, SEM and BET. Perovskite oxides were formed in all substitutions. The catalytic activities of substituted catalysts on carbon black oxidation were measured by Temperature Programming Oxidation (TPO). Experimental results showed that all substitutions increased the catalytic activity of LaMnO3, and La0.8Cs0.2MnO3 showed the highest catalytic activity. Under tight contact, the activity enhancement of different substitutions decreased in the order Cs>K>V>Ce>Co>Cu>Fe. Dynamic analysis showed that partial substitutions increased the pre-exponential factor and the catalytic activity by increasing the oxygen vacancy on the catalyst surface. The active components on the surfaces of La0.8Ce0.2MnO3 and LaMn0.8V0.2O3 included CeO2 and LaVO4, which changed the apparent activities and dynamic parameters of these two catalysts.
Keywords: Substitution; LaMnO3 ; Diesel Particle; Oxidation
Co-pyrolysis characteristics of coal and natural gas by Lirong Kang; Jianmin Zhang; Hui Lian; Ming Luo (508-511).
A co-pyrolysis experiment of coal and natural gas was investigated on a fixed-bed reactor. SEM was used to study the structure changes of the exterior surface of char prepared in this co-pyrolysis experiment, while GC was also utilized to analyze the associated gas. The result showed that, with increasing temperature, the coal char tended to agglomerate. GC and SEM results show that the CH4 decomposition on the exterior surface of char was turned to filamentous char and extended around like coral. It was also proved that the co-pyrolysis of coal and natural gas promoted syngas production. A synergistic effect of coal and natural gas does exist during this process.
Keywords: Coal and Natural Gas; Co-pyrolysis; Syngas; Char; Synergistic Effect
Thermogravimetric study of coal and petroleum coke for co-gasification by Sang Jun Yoon; Young-Chan Choi; See-Hoon Lee; Jae-Goo Lee (512-517).
As a preliminary study of gasification of coal and petroleum coke mixtures, thermogravimetric analyses were performed at various temperatures (1,100, 1,200, 1,300, and 1,400 °C) and the isothermal kinetics were analyzed and compared. The activation energies of coal, petroleum coke and coal/petroleum coke mixture were calculated by using both a shrinking core model and a modified volumetric model. The results showed that the activation energies for the anthracite and petroleum coke used in this study were 9.56 and 11.92 kcal/mol and reaction times were 15.8 and 27.0 min. In the case of mixed fuel, however, the activation energy (6.97 kcal/mol) and reaction time (17.0 min) were lower than the average value of the individual fuels, confirming that a synergistic effect was observed in the coprocessing of coal and petroleum coke.
Keywords: Coal; Petroleum Coke; TGA; Gasification
Preparation of Pt-Pd catalysts for direct formic acid fuel cell and their characteristics by Ki Ho Kim; Jae-Keun Yu; Hyo Song Lee; Jae Ho Choi; Soon Young Noh; Soo Kyung Yoon; Chang-Soo Lee; Taek-Sung Hwang; Young Woo Rhee (518-521).
Pt-Pd catalysts were prepared by using the spontaneous deposition method and their characteristics were analyzed in a direct formic acid fuel cell (DFAFC). Effects of calcination temperature and atmosphere on the cell performance were investigated. The calcination temperatures were 300, 400 and 500 °C and the calcination atmospheres were air and nitrogen. The fuel cell with the catalyst calcined at 400 °C showed the best cell performance of 58.8 mW/cm2. The effect of calcination atmosphere on the overall performance of fuel cell was negligible. The fuel cell with catalyst calcined at air atmosphere showed high open circuit potential (OCP) of 0.812 V. Also the effects of anode and cathode catalyst loadings on the DFAFC performance using Pt-Pd (1: 1) catalyst were investigated to optimize the catalyst loading. The catalyst loading had a significant effect on the fuel cell performance. Especially, the fuel cell with anode catalyst loading of 4 mg/cm2 and cathode catalyst loading of 5 mg/cm2 showed the best power density of 64.7 mW/cm2 at current density of 200 mA/cm2.
Keywords: Pt-Pd Catalyst; Formic Acid; DFAFC
Effective combination of non-thermal plasma and catalyst for removal of volatile organic compounds and NOx by Sang Goo Jeon; Kwang-Ho Kim; Dae Hyun Shin; Nam-Sun Nho; Kyong-Hwan Lee (522-526).
A plasma/catalyst hybrid reactor was designed to overcome the limits of plasma and catalyst technologies. A two-plasma/catalyst hybrid system was used to decompose VOCs (toluene) and NOx at temperature lower than 150 °C. The single-stage type (Plasma-driven catalyst process) is the system in which catalysts are installed in a non-thermal plasma reactor. And the two-stage type (Plasma-enhanced process) is the system in which a plasma and a catalyst reactor are connected in series. The catalysts prepared in this experiment were Pt/TiO2 and Pt/Al2O3 of powder type and Pd/ZrO2, Pt/ZrO2 and Pt/Al2O3 which were catalysts of honeycomb type. When a plasma-driven catalyst reactor with Pt/Al2O3 decomposed only toluene, it removed just more 20% than the only plasma reactor but the selectivity of CO2 was remarkably elevated as compared with only the plasma reactor. In case of decomposing VOCs (toluene) and NOx using plasma-enhanced catalyst reactor with Pt/ZrO2 or Pt/Al2O3, the conversion of toluene to CO2 was nearly 100% and about 80% of NOx was removed.
Keywords: Non-thermal Plasma; Catalyst; Volatile Organic Compounds; NOx
Chemical-looping hydrogen generation system: Performance estimation and process selection by Ho-Jung Ryu; Gyoung-Tae Jin (527-531).
To find a suitable metal component in an oxygen carrier particle for a chemical-looping hydrogen generation system (CLH), oxygen transfer capacities of metal components were investigated, and Ni was selected as the best metal component. The optimum operating conditions to have maximum hydrogen generation rate have been determined based on the chemical-equilibrium composition analysis in a water splitting reactor. Moreover, suitable compositions of syngas from a gasifier of heavy residue oil to provide high energy efficiency have been determined based on the heat of reaction. With the selected operating conditions, the best configuration of two interconnected fluidized beds system for the chemical-looping hydrogen generator has been devised.
Keywords: Chemical-looping Hydrogen Generation System; CLH; Hydrogen; Carbon Dioxide
Hydrogasification of various carbonaceous sources using pressure change properties by Seog Cha Wang; Hyun Il Baek; Hyun Tae Jang (532-536).
Hydrogasification experiments were carried out in a batch reactor capable of operating at 800 °C and 8 MPa. Carbonaceous matters used in the experiments were bituminous and anthracite coal and sawdust. It was found that the decreasing rate of hydrogen gas pressure was closely related to the rate of gas production. This result was confirmed by the change of char conversion. The methane content in the gas products and char conversion rose with the increase of temperature and pressure. The addition of water activated the hydrogasification reaction until the proper level of water amount (up to 30 wt%), but an excess level of water inhibited the reaction. The activation energy of bituminous coal and sawdust char obtained by the Arrhenius plot was 187 KJ/mole and 77 KJ/mole, respectively. In case of loading of catalysts, all catalysts loaded to the char did not give a positive effect in hydrogasification, but the catalytic effect depended on type of catalyst metals and char. In the present hydrogasification of bituminous coal and sawdust, the order of activities for the catalysts tested was K2CO3>Na2CO3>Fe(NO3)2>Ni(NO3)2>FeSO4.
Keywords: Hydrogasification; Gas Composition; Pressure Decrease; Char Conversion; Catalyst
Modeling and economic analysis of CO2 separation process with hollow fiber membrane modules by Hyun Min Shim; Joon Soo Lee; Hong Yue Wang; Seung Hak Choi; Jeong Hoon Kim; Hyung Taek Kim (537-541).
The main purpose of the study was to develop a model using ASPEN and Excel simulation method to establish optimum CO2 separation process utilizing hollow fiber membrane modules to treat exhaust gas from LNG combustion. During the simulation, optimum conditions of each CO2 separation scenario were determined while operating parameters of CO2 separation process were varied. The characteristics of hollow fibers membrane were assigned as 60 GPU of permeability and 25 of selectivity for the simulation. The simulation results illustrated that 4 stage connection of membrane module is required in order to achieve over 99% of CO2 purity and 90% of recovery rate. The resulted optimum design and operation parameters throughout the simulation were also correlated with the experimental data from the actual CO2 separation facility which has a capacity of 1,000 Nm3/day located in the Korea Research Institute of Chemical Technology. Throughout the simulation, the operating parameters of minimum energy consumption were evaluated. Economic analysis of pilot scale of CO2 separation plant was done with the comparison of energy cost of CO2 recovery and equipment cost of the plant based on the simulation model.
Keywords: CO2 Separation; Membrane; Simulation; Economic Analysis
Hydrogen production in fluidized bed by chemical-looping cycle by Gyoung Tae Jin; Ho-Jung Ryu; Sung-Ho Jo; Seung-Yong Lee; Sung Real Son; Sang Done Kim (542-546).
To investigate the feasibility of a chemical-looping hydrogen generation system, we investigated the reduction and water splitting reaction characteristics for three mediators and two reducing gas in a bubbling fluidized bed reactor (0.02 m I.D.). For three oxygen carrier particles (NiO/bentonite, Fe2O3/bentonite, (NiO:Fe2O3)/bentonite), hydrogen was used as a reduction gas and water was used as an oxidation gas. For (NiO: Fe2O3)/bentonite particle, carbon monoxide, which is the main component in the syngas from coal or heavy residue, was used as a reducing gas to check reactivity for the carbon containing fuels and carbon deposition characteristics. Based on the reactivity tests, (NiO: Fe2O3)/bentonite particle was selected as the best mediator for the chemical-looping hydrogen generation system to achieve stable continuous operation.
Keywords: Chemical-looping Cycle; Hydrogen Production; Inherent CO2 Capture; Redox; Mediator
Cycloaddition of carbon dioxide to epichlorohydrin using ionic liquid as a catalyst by Eun-Ha Lee; So-Wan Cha; Manju Mamparambath Dharma; Youngson Choe; Ji-Yun Ahn; Dae-Won Park (547-550).
The cycloaddition of carbon dioxide to epichlorohydrin was performed without any solvent in the presence of ionic liquid as catalyst. 1-Alkyl-3-methyl imidazolium salts of different alkyl group (C2, C4, C6, C8) and anions (Cl−, BF 4 − , Br−, PF 6 − ) were used for this reaction carried out in a batch autoclave reactor. The conversion of epichlorohydrin was affected by the structure of the imidazolium salt ionic liquid; the one with the cation of longer alkyl chain length and with more nucleophilic anion showed better reactivity. The conversion of epichlorohydrin increased as the temperature increased from 60°C to 140°C. It also increased with increasing carbon dioxide pressure probably due to the increase of the absorption of carbon dioxide into the mixture of epichlorohydrin and the ionic liquid. Zinc bromide was also tested for its use as a cocatalyst in this reaction.
Keywords: Cycloaddition; Epichlorohydrin; Ionic Liquid; Carbon Dioxide