Oxy-Fuel coal combustion has drawn attention in the world as useful technique to achieve carbon dioxide capture and storage (CCS). It is a technology to enrich CO2 in exhaust gas by the flue gas recirculation with additional pure O2 to combustion atmosphere, which makes easy to capture CO2. Meanwhile, bubbling fluidized bed coal combustion has advantages of direct sulfur capturing in bed material and decreasing of thermal NOX in low combustion temperature. Objectives of this paper are to understand hazardous emission behaviors during the oxy-coal fluidized bed combustion under the actual flue gas recirculation condition, compared with those under the air and CO2-O2 combustion conditions. A lab-scale fluidized bed reactor was utilized as the experimental equipment. Dusts were separated from flue gas via cyclone downstream, and carbon contents in them were analyzed to estimate carbon balances through the reactor.
Coal combustion is one of the major mercury emission sources. The majority of mercury emissions from coal combustion is an elemental mercury. This is because oxidized mercury is water-soluble and easily captured, but on the other hand elemental mercury is water-insoluble and difficult to capture. In this study, we expected the De-NOx catalyst to have a mercury capture/oxidation performance and performed mercury capture/oxidation experiment using the De-NOx catalyst as a sorbent. In the result, when HCl is present in the atmosphere, the De-NOx catalyst oxidized mercury and when HCl is not present in the atmosphere, the De-NOx catalyst showed high mercury capture performance. Furthermore, De-NOx catalyst maintained high mercury capture performance at a relatively high temperature (673 K).
One of the major problems in pulverized coal combustion process is ash deposit phenomena such as slagging and fouling. The behaviors of Included Minerals (IM) and Excluded Minerals (EM) are an important factor to predict and control such ash deposit phenomena. Then, we sampled pulverized coal particles in different carbon conversion and coal types using Drop Tube Furnace (DTF) and analyzed ash particles by Computer Controlled Scanning Electric Microscope (CCSEM) in previous study3). In this study, we made the models of single pulverized coal particle in combustion process using data gotten by CCSEM analysis and evaluated IM/EM particle properties such as particle number, particle diameter and composition in different carbon conversion and coal types through the simulation.
Coal gasification is a key technology for converting coal into substitute natural gas (SNG), the common feedstock for synthesis of chemicals and electricity generation. Now, the development of coal gasification technologies is conducted for commercialization all over the world. Nippon Steel & Sumikin Engineering Co., Ltd. developed the innovative coal gasification technology using the highly efficient two-stage entrained flow gasifier (ECOPRO®). The development of this process is now under the pilot plant stage with 20t/d coal gasification capacity. As a result, it was found that this process had the stability of this process and applicability of verification of low-rank coals including high ash brown coal. This paper reports on the results from operating the pilot plant using high ash brown coal as feedstock.
To utilize low rank biomass energy, we are proposing co-gasification process that coal is mixed. For co-gasification of sludge and coal, it is important to reveal characteristics of co-char produced from sludge and coal by pyrolysis. So, we reported gasification behavior of co-char and difference of reactivity between single chars (sludge char and coal char) and co-char previously. In this study, it was revealed the difference of property between single chars and co-char from points of elemental analysis, SEM image and raman spectrum. And it was considered about interaction of co-pyrolysis when sludge and coal were pyrolized at the same time.
We investigated the effects of high H2 and H2O (Steam) partial pressure on coal char and Ca loaded coal char gasification rate by using thermogravimetric apparatus. It is found that the H2 gas existence strongly inhibits the char steam gasification rate. However, gasification rate of Ca loaded coal char was much higher than that of coal char gasification, and the inhibition of H2 presence on gasification rate for Ca loaded coal char gasification was smaller than that for char gasification.
Concerning to the integrated gasification combined cycle (IGCC) which is a highly effective coal power plant, the improvement of cold gas efficiency is expected by utilizing steam as a gasifying agent effectively. However, the temperature in the gasification furnace will decrease owning to steam injection, so evaluating the effects of temperature on gasification reaction is an important study. In this study, the effects of pyrolysis temperature on char gasification reactivity were investigated. Pyrolysis experiments of sub-bituminous coal were carried out at 1173K, 1273K, 1373K, 1473K and 1673K using drop tube furnace (DTF) to produce the several types of char, and then gasification experiments were carried out using thermogravimetric analysis (TGA). As a result, char gasification reaction ratio was raised when the pyrolysis temperature was lower and it was found that pyrolysis temperature influenced on the characteristics of char. In order to investigate the relation between pyrolysis temperature and gasification reaction ratio, prepared char was analyzed by BET, XRD, and TEM-EDX. According the result of X-ray diffraction (XRD) analysis, it was found that graphitization degree was different owning to the difference of pyrolysis temperature. Moreover, according to the result of TEM-EDX analysis, it was found that iron contents were highly dispersed in char.
The numerical simulation of pulverized coal combustion is performed to investigate the effect of gasification reaction on char reaction process in blowpipe. The results of the simulation without gasification were compared to those with gasification in gas and particle temperatures. Although the difference of gas temperatures between with and without gasification was small, that of particle temperatures was large at the downstream of blowpipe. This is because the gasification reaction occurs at the downstream of blowpipe, and the effect of gasification on small particles was larger than that of large particles. In addition, the conversion of fixed carbon with gasification was slightly higher than that without gasification. The results suggest that the inhibition effect due to the endothermic gasification is small and the char consumption in blowpipe increases by the gasification.
Advanced Integrated coal Gasification Combined Cycle (A-IGCC) systems have been proposed to obtain higher thermal efficiency than that of IGCC systems by recuperating exhaust heat from a gas turbine as a heat source of a gasifier. To date, A-IGCC system that consists of gasification, gas cleaning, CO2 capturing, and combined cycle power generation units has not been designed. In this study, performances of A-IGCC systems were evaluated by using process simulator Aspen Plus. Results indicated that net thermal efficiencies of A-IGCC model with a hot gas desulfurizing unit (HGDU) were higher than those of the model with a cold gas desulfurizing unit (CGDU) by 0.4–2.5% due to losses in heat in the gas cleaning units and higher heating value of fuel gas. By assuming to use 1650 °C-class gas turbine, HGDU and above 20% of CO2 capturing, CO2 emission factors can be reduced below 503.2 kg-CO2/MWh.
Some thermal power plants experience problems due to increasing chemical oxygen demand (COD) and total nitrogen concentration (T-N) in flue gas desulfurization (FGD) wastewater. Nitrogen-Sulfur (NS) compounds are speculated as the cause of increasing COD and T-N. However, even the current emissions of NS compounds are not understood because a analysis method of NS compounds with high sensitivity and accuracy has not been reported. Herein, we report the development of an analysis method for NS compounds. Furthermore, characteristic features of dissolved organic matter in FGD wastewater as the COD components were analyzed by LC-OCD and excitation-emission matrix.
It is known that decrease in flowability and hardening of coal ash is due to moisture absorption and compression during transportation and storage. This can lead to blockage accidents of coal ash in the hopper and pipe and similar situations. In this paper, the sulfate amount and compounds that affect the moisture absorption of coal ash were investigated. As a result, it was found that sulfuric acid mist and compounds on the coal ash combine to form sulfate compounds. The adsorption capacity of the sulfuric acid mist is affected by the coal ash characteristics.
We have prepared a unique iron ore-carbon composite (IOC) from a low grade iron ore by inserting a thermoplastic carbonaceous material into the slit like pores of 0.8 nm width that are formed by dehydration of the iron ore. The IOC prepared at 500 °C consists of layered Fe3O4 and coke, coming from the plastic carbonaceous material and filling the pores. In inert atmospheres the layered Fe3O4 in the IOC is reduced to Fe by solid-solid reaction between the layered Fe3O4 and the coke at less than 900 °C. In oxidizing reagents such as CO2 and H2O, the coke is gasified very rapidly by catalytic effect of Fe3O4. The mechanism and the rate of the gasification of the unique coke were examined.
Although it is required hardness for coke in the blast furnace, CO2 is generated by reduction of iron ore and the CO2 gasify coke and make coke brittle. However, there is a case where the strength does not easily lowered. One of the reasons is difference of coke optical textures. So, there are many studies about influence of gasification on coke optical textures. However, almost of these reasearches are about CO2 gasification and there is a little about CO2/H2O mixed gas. In this study, since H2 rich gas is used for reducing gas and CO2/H2O gasification is occured in NEDO project COURSE50, influence of CO2, H2O, CO2/H2O gasification on coke optical textures was investigated by using image analysis of the coke cross-section. As a result, it was revealed that inert and isotropic textures had higher reactivity and ratio of inert, isotropic and mosaic textures reactivity was 1.00:0.71:0.20. This ratio was almost same in all gas.
The effect of inertinite size change in coal by crush on coke strength was investigated. The inertinite size was measured automatically by image analysis. Coke strength increased with decreasing inertinite size larger than 34,500 μm2 in coal with low fluidity.
The fluidity and evolution of gaseous O-containing species (CO, CO2 and H2O) during carbonization of caking coal, non- or slightly-caking coals and their coal blends at a heating rate of 3 °C/min have been studied with gieseler plastometer and a flow-type quartz-made fixed bed reactor to make clear the influence of particle size, blend ratio and oxygen species on coal fluidity. The gieseler maximum fluidity (MF) values decrease with increasing the amount of non- or slightly-caking coals added to caking coal. In addition, blend coals fluidity trends decrease with decreasing particles size of non- or slightly-caking coals in blend coals. When caking coal and non- or slightly-caking coals are absolutely carbonized, the MF value decreases almost linearly with increasing total amount of gaseous O-containing species evolved up to the initial softening temperature. Furthermore, H2O formation rates during carbonization of coal blends (250-425 μm-caking coal and 250-425 μm or 53-150 μm-non- or slightly-caking coal) are different from their calculation values based on the results of 250-425 μm-caking coal and 250-425 μm or 53-150 μm-non- or slightly-caking coal. It may be thus probable that H2O derived from non- or slightly-caking coal gives a negative effect on coal fluidity of coal blends.
Cokes are used in the blast furnace and the direct melting system, etc. Good quality coking coals are needed in the conventional coke making process. However, high quality coking coal will be exhausted in the future. Therefore, the development of the new coke making process (Formed Coke Process) for direct melting system using low grade coal instead of coking coal has been conducted. As a result, it was clarified that it is possible to produce high strength formed coke using low grade coals introducing these technologies as follows. Optimization of volatile matter by coal blending operation, pre-carbonization.
To avoid pushing trouble at old coke oven, it is essential to maintain sufficient clearance between coke cake and heating wall. Clearance depends on swelling pressure in the plastic layer and contraction of the semicoke layer. Those parameters are influenced by bulk density of coal charge, coke oven temperature, and the values of blending parameters. The vertical distribution of bulk density is thought to vary the clearance with location in coke oven chamber. In this study, two dimensional model, which considers heat transfer, swelling pressure, and contraction, is proposed to estimate the vertical distribution of clearance. It showed the clearance is minimized near the position of the highest bulk density of coal charge.
In a series of studies on the development of advance desulfurization process, coal soluble was prepared by heating low-grade coals at a temperature of 350°C for 1 h in 1-methylnaphthalene as a solvent according to the Miura’s process. The sulfur distribution from the raw coals to products was investigated and the chemical forms of sulfur in the raw coals and coal soluble were identified by XANES analysis. The selective removal behaviour of organic sulfur from the coal soluble during the multistep extraction using the ionic liquids was investigated.
Hyper-coal is an ash-free coal produced by the solvent de-ashing technology. Coal is thermally (360-420 °C) extracted into the coal-derived solvent. HPC has excellent thermoplasticity and large potential for coke additive to make a strong coke. The yield of Hyper-coal depends on the coal solubility. Therefore, it is important for Hyper-coal process to optimize extraction condition to increase extraction yield. In previous research, we researched the effect of heating rate by bath test (500cc scale autoclave) and that the extraction yield was increased with increasing heating rate.
We are developing Hyper-coal process by using bench scale units (BSU) to acquire the process design data. In conventional method, after coal and solvent are mixed, the slurry is heated to the temperature of extraction (380 °C). In this method, the heating rate is approximately 100 °C /min. In order to increase the heating rate, BSU was remodeled that is able to mix the coal slurry and high temperature solvent in extractor. In this method, we study the extraction yield and material balance of effect of rapid heating extraction.
Hyper-coal (HPC) process, a thermal extraction process of coal uses methylnapthalene-like solvent, presupposes the solvent recycling. It means that there is no need to replenish the fresh solvent from outside. To perform this, coal-derived fraction, which is distillable oil produced by the thermal decomposition reaction of coal, will be utilized as the solvent. Solvent loss will be replenished by the coal-derived fraction repeatedly, and composition of the coal derived fraction will become the equilibrium composition. Therefore, to satisfying the necessary and sufficient condition for solvent recycling, the process produces enough quantity and quality of coal-derived fraction. Recent study revealed that the yield of coal-derived fraction was several percent on coal and consisted with compounds having naphthalene ring structure mainly1)2). Improved estimation of the composition of coal-derived fraction was carried out subjecting the rapid-heating process. The rapid heating process improved coal extraction yield and produced several percent of distillate, same yield as conventional heating3)4). Compound compositions of coal-derived fractions were investigated by coal extraction experiments in diphenylether (DPE) as solvent. DPE was regarded thermally stable and not having interaction with coal5). As a result, coal-derived fraction was consisted with compounds having naphthalene ring structure (80%) and benzene ring structure (20%). In compounds having naphthalene ring structure, main compounds were 73% of 1-methylnaphthalene (1-MN) and 27% of dimethylnaphthalene (D-MN). On the other hand, composition of the naphthalene ring compounds was changed by using 1-MN as solvent. Composition of 1-MN and D-MN were decreased, instead of that, naphthalene (NP) and 2-methynaphthalene (2-MN) were increased. It was considered that those changing of component structure should be occurred by interaction between coal and solvent caused by active free radicals.
The leaching of trace elements in coal fly ash such as As, Se, and B is desired to be controlled. Development of suppression the leaching of the trace elements has been studied using paper sludge ash (PS) containing the high calcium content. When the high cacium content paper sludge ash (PS#3) was mixed to a coal fly ash by weight percentages of 20−25%, the leaching ratios of As, Se, and B was strongly decreased than the environmental regulation. To find a dominant chemical compound for the suppression of trace elements, effect of CaO and Ca(OH)2 were examined. Both calsium compound have effectively decreased the leaching of As, Se, and B. It found that PS#3 contained 8.2% CaO and 1.0% Ca(OH)2, which were the dominant compound for the suppression of trace elements.
Calcium has been known has a good decreasing in the leaching concentration of arsenic (As) and selenium (Se). Suppressing material, as the by-product of some industries which contains of high calcium, had been proven in decreasing of arsenic (As) leaching concentration from coal fly ash. This study aims to provide the useful reference in controlling As and Se leaching concentration into the environment through the effect of suppressing material addition. There are three suppressing materials that have been tested, that are: paper sludge ash (PS 3 and PS 4) and filter cake (FC). PS 3 shows the closest effect to Ca(OH)2 which is used as the standard, it shows almost 85-90% decreasing in As and Se leaching concentration based on ICP analysis. FC did not show an effect in As leaching concentration, but in the contrary with Se leaching concentration, it shows almost 60% decreasing. Calcium oxide has been known as the almost calcium compound which is containing in PS 3 and also known has the best decreasing on As and Se leaching concentration amongst the others calcium compound tested. Could be concluded that CaO is the most wanted calcium compound in controlling the As and Se leaching concentration into the environment.
Calcium compounds affected the trace element leaching concentration from coal fly ash through the addition of suppressing material. Suppressing material which is used in this research is paper sludge and filter cake. Paper sludge (PS) is a waste generated by the paper recycling industries. The kinds of paper sludge which is used in this research is PS3 and PS8. Filter cake (FC) is formed by the substances that are retained on a filter. Filter cake come from lime industry. The determination of calcium compound in coal fly ash and suppressing material have been done by using X-ray Diffraction (XRD) analysis. XRD analysis is an instrument that work based on Bragg`s law and present the result in peaks therefore each compound has peaks suitable with its characteristic. The result from XRD analysis will give good information about the calcium effect which could be used in controlling leaching of trace element from coal fly ash.
In this suduy, we investigated the influences of residucal carbon and ash composition in coal ash on the melting behavior by measuring the melting temperatures of the ash and char with diffrent residual carbon and CaCO3 contents. The melting temperatures evaluated by JIS M 8801 increased wih increasing the residual carbon content, while the temperatures decreased with the addtion of CaCO3. The decrease of the temperatures of CaCO3-added ash and char depended on their residucal carbon content.
Spent printed circuit board is a typical E-waste which contains valuable elements such as precious and rare metals. In order to develop an efficient recovery process of valuable elements from the spent circuit board, volatilization behavior of gold and silver was followed during chlorination of an incinerated spent circuit board. It was observed that temperature of 1000°C is needed to volatilize gold and silver completely from the sample. 3 types of coal were demineralized by acid leaching and pyrolyzed under a nitrogen stream to obtain the chars without minerals. These chars showed a potential to capture gold selectively from the various elements volatilized from the incinerated circuit board during chlorination. Some effects of treatment temperature and types of carbon on the recovery extent of precious metals were investigated.
This paper studied the performance of the direct carbon fuel cell (DCFCs) using the activated carbon particles. In the DCFC, the anode was inserted to the carbon/carbonate slurry in which carbon particles were dispersed into the molten carbonate. The cell voltage and efficiency increased with decreasing the size of carbon particles. In addition, carbon surface characteristics after discharge were analyzed using AES (Auger Electron Spectroscopy). O/C ratio on the carbon surface after discharge increased, indicating CRSO was intermediate during the electrochemical oxidation of carbon.
A series of organic microspheres (OM) were prepared from three brown coals directly using a simple treatment in water at 350°C and 20 MPa. The method can be applied to various coals with carbon yields above 20%, which would meet the requirement for industrial application. The diameters of OMs are ranging from 0.2-3.7 μm. The spherical morphology of OMs changes slightly with different resources, and some microcapsules have been found. OMs from coal are expected to be used as carriers and/or supporters. This methodology provides a novel low-cost resource with world-wide abundance and stable supply for OMs, opening up a novel avenue in the conversion of natural fossil fuel to advanced materials.
To investigate the acceleration mechanism of the coal oxidation at low temperature by chemical species such as water, we evaluated the oxidation behaviour of coals with various coal rank in the presence of water. The results revealed that coal with higher oxygen content such as brown coal were significantly affected by the acceleration of water, which indicates that hydrophilicity of the coal is one of the important factors affecting the oxidation in the presence of water.
Spontaneous combustibility of Indonesian lignite was studied with field test of 150-ton simulated pile and numerical simulation of the stockpile. The experimental results showed that the temperature of the coal was significantly increased from the bottom and outer part of the stockpile. 3D numerical simulation was performed for better understanding of the experimental results. The simulation predicted that the decrease of the moisture content leads to increase of the spontaneous combustibility. The results also indicated that the balance of oxidation reactivity and moisture content was one of the important factors for evaluation of the spontaneous combustibility.
We have proposed a method called degradative solvent extraction for dewatering and upgrading low rank coals and biomass wastes. In this study, the spontaneous combustibility of the upgraded products were examined using TGA and DSC, in which weight change and heat generation rate during oxidation in dry and humid airs were measured at temperature ranging between 30 to 150 °C. The upgraded products showed higher heat generation rates than the raw materials in dry air, but it showed smaller heat generation rates in humid air even over 100 °C. These results suggested that the spontaneous combustibility of upgraded products are smaller than the raw materials based on our recent works showing that the spontaneous combustibility of low rank coal is affected by the heat generation coming from adsorption of water vapour.
The Osaki Coolgen Project began in April 2012 as an "Integrated coal Gasification Fuel Cell combined cycle (IGFC) demonstration project" subsidized by the Ministry of Economy, Trade and Industry. This project aims to realize innovative low-carbon coal-fired thermal power generation that combines IGFC, an extremely efficient coal-fired thermal power generation technology, with innovative CO2 capture technologies. The first stage of this project, to demonstrate the oxygen-blown Integrated coal Gasification Combined Cycle (IGCC), is progressing in commission toward demonstration testing start in March 2017.
Authors have analyzed the high-temperature gasification reactivity of several coal samples using a drop tube furnace to estimate the performance of an entrained-flow coal gasifier for IGCC system. The char samples were prepared at 1400 °C and gasified in these tests. In this study, the properties of 18 char samples were measured and discussed their influence on the gasification reactivity. As a result, it was found that the amounts of CO2 adsorption on char at 300 °C showed good correlation with gasification reaction rate at both low and high temperature. Ion-exchangeable Ca and Na have also important effect on gasification reactivity and the index was proposed. It was found that their catalytic activity was still maintained at high-temperature gasification.
In this study, we measured time-series and 2-dimentional distributions of temperature and H2O concentration in pulverized coal combustion field using Computed Tomography-Tunable Diode Laser Absorption Spectroscopy (CT-TDLAS). Results show that the temperature increased with increasing the coal feed rate. The H2O concentration didn’t change significantly. These results show CT-TDLAS is able to be applied to measure 2-dimensional temperature distribution in pulverized coal combustion field which has a lot of dust. Therefore, we will perform time-series and 3-dimentional distributions of temperature and H2O concentration using three-tiered CT-TDLAS.
The online selenium monitor, a fully automated process monitor for aqueous selenium in desulfurization wastewaters, measures selenium concentration in process effluents with a Galvanic cell gas detector for hydrogen selenide. We added the function to humidify carrier gas onto the online selenium monitor, to prevent a decline in performance of the gas sensor. The improved selenium monitor was installed in a full-scale coal-fired power plant and monitored the selenium concentration in flue gas desulfurization effluents, i.e., the influent and effluent of the wastewater treatment facility for selenium removal. The concentration of selenium varied in the range of 0.05 and 1.06 mg/L for the influent, whereas the effluent remained almost below the effluent standard (0.1 mg/L). We had three months of measurement failure, but except those data a fairly good correlation (r2 = 0.961 for n=326) was obtained in the measurements between the monitor and the official method (ICP-OES), which demonstrated the improved monitor serves as a useful tool for managing selenium emission in process effluents. The causes for the malfunction in the test were due to the sensor life, operational fraud in a stirrer and chemicals addition and so on. We established a protocol for the regular maintenance to prevent operational malfunctions and criteria to evaluate the life of sensor.
In the regenerator of Calcium-Looping CO2 capture process, CaCO3 is thermally decomposed to CaO under high CO2 partial pressure conditions at high temperatures about 1223 K. It is known that the decomposition of CaCO3 is enhanced by H2O vapor. A possible mechanism is that CO2 in the gas phase adsorbs on CaO surface and inhibit desorption of CO2 which is formed by the decomposition reaction, but the CO2 adsorption is inhibited by H2O vapor. In the present work, change in weight of CaO was measured by TGA, feeding gas containing CO2 and H2O. By feeding solely CO2 or H2O, the adsorption of each component was found to be described by Langmuir-type isotherm. The inhibition of CO2 adsorption by H2O, however, was more pronounced than the estimated inhibition assuming competitive adsorption.
In thermal power generation equipment, wall thinning on boiler tubes due to sulfide corrosion has been a problem. The methods for resolving or preventing the problem are coating of a nickel-chromium film by plasma spraying, weld cladding, and replacement of water wall tubing. These methods are expensive and time consuming. Therefore, an economical and straightforward coating technique was developed for preventing sulfide corrosion on boiler tubes. The developed coating (CRIEPI coating) has a four-layered structure comprising, in order from the boiler tube substrate, thin films of (1) a SiO2 layer, (2) a TiO2 layer, (3) an Al2O3-based layer, and (4) a TiO2 layer. CRIEPI coating reduced corrosion to 25% or less compared with an uncoated part. It was found that CRIEPI coating on boiler tubes is exceptionally durable and continues to be effective for more than 2 years in actual power plants.
We developed an evaluation method of grinding characteristics for a blend of coals with different grindability. HGI represents an initial grinding characteristic. We also developed a simple method for estimating a grinding rate constant distribution. An HGI test and a semi-continuous test by an HGI test equipment were conducted. Each averaged HGI calculated by feeding basis and mill accumulation basis was predicted by a first-order grinding-rate equation. When there was difference in HGI between blended coals, we could predict that the averaged HGI of the feeding basis was different from that of the mill accumulation basis. Grinding rate constant distribution was derived from a multicomponent consecutive grinding model for the semi-continuous test. Grinding rate constant distributions derived from the model were obtained and a blending ratio in a mill was predicted. The grinding rate constant distributions of high ash coal and low ash coal having approximately same HGI were different. Grinding rate constant distributions were used to predict a mill accumulation rate.
To raise the co-firing rate of the woody biomass is one method for CO2 reduction in pulverized coal power stations. Since the carbonization of raw woody biomass can improve the grindability in the mill, it is effective to grind in single-fuel of biomass. CRIEPI investigated the single-firing characteristics using carbonized woody biomass by a small scale coal combustion test facility with a single burner.
NOx and SO2 concentration at the exit of furnace in the single-firing of carbonized woody biomass became very lower than those of coal firing. The combustion efficiency of carbonized woody biomass was extremely higher than that of coal. The combustion process of carbonized woody biomass near the burner was different from that of coal greatly.
One-pot direct catalytic conversion of cellulose to light hydrocarbons at low temperature (443 K) in the presence of Pt-supported zeolite catalysts and water was investigated. Results revealed that Pt supported on NH4+-form USY-type zeolite catalyst (Pt/NH4-USY) enabled direct conversion of cellulose into C3 and C4 hydrocarbons without hydrogen or other expensive reagent. Pt/NH4-USY catalyst with highly dispersed Pt particle showed higher hydrocarbon yield than Pt/H-USY catalyst. Effect of the supported Pt surface area on activity and selectivity was also investigated. Results revealed that Pt/H-USY catalyst with high Pt surface area showed high C3 and C4 hydrocarbon yield.
The woody biomass co-combustion with coal in the coal fired power plant is one of effective measure to reduce the greenhouse gases, but it is difficult to increase the mixing ratio of woody biomass with coal because of its grindability. The carbonization technology of woody biomass enables to upgrade the grindability and heat value of woody biomass, so it allows the co-combustion use of woody biomass in high mixing ratio. In this study, the performance of woody biomass carbonization process is estimated by the heat balance analysis of the carbonization process with the results of 4t/d biomass carbonization test facility.
Preparation of a carbon fiber precursor from the so called Soluble, an extract obtained by the degradative solvent extraction of rice straw, was performed by using an oxidation and N2 purge treatment methods at 100-360 °C. Changes in the functional groups were measured by an in-situ FTIR technique. During the treatments, small weight change was observed during the air oxidation treatment. The molecular weight of Soluble treated by the air oxidation was larger than that treated by the N2 purge. The melting point of Soluble was also found to increase significantly after the air oxidation treatment. Cross-linking reactions among low-molecular-weight compounds were judged to play the important role on the modification of Soluble through the air oxidation treatment.
Electrospinning technique was applied to Hypercoal (HPC) prepared by high temperature solvent extraction of coal using methylnaphthalene-based solvent. Thick pyridine solutions of HPC, ca. 35 wt% can be continuously electro-spun into micro fibers whose diameter is in a range of a few micrometer or less. Thus obtained precursor fibers were converted into micro carbon fibers without fusion or sticking by heat-treating in an inert atmosphere. The elctrospun micro carbon fibers from HPC carbonized at 900°C exhibited surprisingly high specific surface areas exceeding 1000 m2/g without any activating treatment. The electric double layer capacitors (EDLC) were fabricated using the micro carbon fibers from HPC as electrode and their properties were evaluated in an aqueous electrolytic media. EDLC using HPC micro carbon fibers possessed a stable charge-discharge performance and its capacitance was as high as 400 F/g.
Benzene as a tar model compound was decomposed by using iron-loaded catalyst, which were produced by the pyrolysis and hydrogen reduction of Indonesian Adaro subbituminous coal (AD) with iron salts (iron oxide, iron chloride and iron nitrate), at 750 and 800 °C in 1700 ppm C6H6 / 45 %H2 /15 % H2O / He atmosphere. When the AD without iron species was used as a catalyst, the benzene conversion was about 3 and 18 mol% at 750°C and 800°C, respectively. By using the AD with 3.3 wt% iron prepared from iron oxide and iron chloride, the benzene conversion increased to about 40 mol% at 800°C. On the other hand, the AD with 3.7 wt% iron nitrate decomposed only 22 mol% of benzene even at 800°C. Also, it was found that the benzene conversion increased with increasing iron loading. The XRD patterns for the catalysts after decomposition of benzene at 800°C reveal that the iron species existed as α-Fe or austenite in the case of high benzene conversion.
The fuel cell is widely known to obtain power generation without combustion and pollution. Direct Carbon Fuel Cell (DCFC) is also a power generation device by converting the chemical energy of carbon directly into electricity. The DCFC have many better characteristics, for example, various solid carbon resources including coal, the petroleum coke and biomass carbon are used as fuel. Further, the DCFC is expected for emergency power supply when a natural disaster occurs. However, the DCFC is still in the preliminary stage of development. In this study, effects of scale-up on the DCFC efficiency for practical application were studied.