Development of technologies for Integrated Coal Gasification Combined Cycle (IGCC) has been actively carried out in advanced countries because of its higher thermal efficiency and superiority of environmental soundness. All the electric utility companies in Japan started the IGCC Demonstration Plant Project in 1999. This paper shows the current status of IGCC technologies and the subject for commercialization of IGCC.

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Establishment of clean coal technology is important and essential for mitigating global warming and decreasing pollutant emission. In Japan several projects have been in progress for developing new coal technologies, including entrained bed coal gasification for power generation and hydrogen production, new coal pyrolysis process for recovering gaseous products, hydrogasification of coal for producing substituted natural gas, and pressurized fluidized bed combustion for power generation. One research program, organized by university researchers for supporting the ongoing projects, supported by the Scientific Research on Priority Areas is briefly reviewed, and the result obtained by the group of author's in the program is introduced.

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Atomic force microscope (AFM) equipped with an environment-controlled chamber is used for the analyses of morphology, surface properties and mechanical properties of coal under inert atmosphere. In coal surface, three components are recognized; a layered structure at several microns, structureless and soft component, and fibrous component which gives a long range repulsive force presumably attributed to an electrostatic force. The difference of mechanical properties detected by force curve may be corresponding to heterogeneity in coal such as macerals.

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As-received and partially dried Yallourn coal (YL) and Beulah Zap coal (BZ) were subjected to a magnetic resonance relaxation analysis employing a Carr-Purcel/Meiboom-Gill (CPMG) pulse sequence. The analysis detected the protons undergoing transverse relaxation with different time constants, arisen from bulk water, pore water and coal hydroxylic groups, respectively. The relaxation of the pore water, described by that of a single component, indicated the coexistence of freezable bound water and non-freezable water in the individual pores, thus suggesting no micropores involving the latter type of water exclusively. Based on a theory on the relaxation of liquid in porous systems, the relaxation characteristics of pore water and hydroxylic groups were further analyzed. Assumin slit-like pores, their averaged dimensions were estimated as 2.9-3.1nm for YL and 2.2nm for BZ, unless the bound water is removed.

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The carbon structure of coal was measured by ^<13>C-NMR, XRD, LRM and XPS technique for CCUJ standard coals. A parameter to evaluate the carbon structure was developed for each analysis method, and their results were compared. It is found that LRM parameter and XRD parameter is available especially, because relation between both parameters and fa from NMR showed a good agreement. The 20 CCUJ standard coals were characterized by these parameters.

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Diamond method is the X-ray diffraction technique to characterize the layer size (La) of carbon by fitting between observed and theoretical X-ray intensities of a variety of model aromatic molecules. In this work, some problem arose in the application of Diamond method to coals, such as selection of model compounds and contribution of amorphous components, have been discussed.

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The carbon stacking layers in coals were evaluated by X-ray diffraction technique (STAC-XRD: Standard Analysis of Coal-by X Ray Diffraction). STAC-XRD has been applied to the treated coals with heat and solvent, and the structural changes of these treated coals were discussed. The average number of stacking layer increased with increasing the carbon content of raw coal. The enhancement of carbon stacking layers during the heat treatment depended on the condition of the treatment and kind of coal. The treatment with solvent increased the average number of stacking layer. From these results, it is confirmed that STAC-XRD is effective for the evaluation of the carbon stacking layers in coal.

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X-ray photoelectron spectroscopy (XPS) was used to quantify the carbon and nitrogen forms of coals and weathered coals. In case of carbon forms, the content of carboxyl group increased as the weathering time elapsed. The increase in the carboxyl group when 74μm under coal was used was larger than that for 1mm under coal. For nitrogen forms, the content of quaternary nitrogen species increased, whereas that of pyridinic species decreased after the weathering.

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It is known that DD/MAS measurement can afford more quantitative spectrum than CP/MAS measurement. However, the reliability of DD/MAS spectrum is affected by various factors. These factors including fluctuation of the instrument in Solid state NMR have been investigated.

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Using curve fitting of IR spectra, functional group analysis of standard coals (Jcoal, ss001-ss050) was done and estimated. Classification and Regression Tree model (CART) as a data mining tool was also utilized for searching the relation between the curve fitted spectra and some coal properties.

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Forty three coals were analyzed by FTIR and the results were compared to those for other methods. For carboxyl group, the contents in coal obtained from FTIR were quite comparable to those from the conventional chemical analysis using ion-exchange method. The peak ratio of aromatic CH and aliphatic CH for FTIR showed a good relationship with f_a value obtained from solid state ^<13>C-NMR.

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Upper Freeport coal was extracted and fractionated at room temperature. For AS fraction obtained liquid-state ^<13>C NMR spectrum was measured. A model structure for AS was constructed by using the NMR chemical shift calculation. For the extraction residue (MI), a model structure was constructed, and the calculated ^<13>C NMR spectrum was in excellent agreement with the observed one. Associated structure of coal molecules having a continuous molecular-weight distribution from the lighter fraction (AS) to the heaviest residue (MI) was assumed for the model structure of the coal. Conformation of the raw coal was determined by the MM-MD calculation under periodic boundary condition, which makes the coal have the anisotropic structure. Finally, the energy-minimum conformation was determined, and the estimated physical density was 1.28g/cm^3, in good agreement with the experimentally obtained value of 1.30g/cm^3.

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Preheat-treatment of 4 different ranking coals at low temperature (<400℃) was performed to clarify the structural changes by using XRD method and swelling technique. For low ranking coal, preheat-treatment below 300℃ increased the order of coal molecules in terms of chain entanglement by removing water, while that above 300℃ strengthened stacking of aromatic planes in coal. Upper-Freeport coal was observed fused below 400℃, but there was no significant change of its XRD when measured at room temperature. Structural change of the coals by preheat-treatment is correlated to their swelling behaviors.

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The authors have been investigating the relationship between chemical structure and coal plasticity. To obtain skeletal and low molecular components developed during plastic range of coal, highly coking coal, Goonyella coal and slightly coking coal, Witbank coal were heat-treated and the resulting char fractions were extracted with a CS_2-pyridine mixed solvent. The skeletal components (residue) and the low molecular components (extract and released compounds during heat-treatment) were characterized to discuss the diffrences in structure and pyrolytic behavior of two coals.

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Recent modified SPI, single-point ramped imaging with T_1, enhancement (SPRITE), consist of a ramped phase encode gradient in the primary phase encode direction and conventional phase encode gradients in the other directions. The use of a ramped phase gradient permits imaging with greater speed and with lower dB/dt, which is minimizes gradient vibration with compared with SPI. At the same time, a great time improvement is achieved with sample where T_1 relaxation times are on the order of the gradient rise time. Magnetization preparation is easily incorporated into the SPRITE sequence by sampling a single k-space point after each magnetization filter application. Balcom et al. have demonstrated that magnetization preparation permits accurate T_2 and T_1 mapping of samples with short relaxation times. In this paper, we at first are demonstrating 3D-SPRITE which has shown to be successful for studying short relaxation time systems and which is free from distortions due to susceptibility variations for coals with high resolution at a frequency of 400MHz. The results obtained were discussed in relation to the three dimensional distribution of mobile component for 2 kinds of coal. At the same time, inversion recovery preparation experiments (T_1 mapping), T_2 mapping based on SPRITE methods are presented in order to clarify the chemical heterogeneity of coals.

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A brown coal was swollen in binary solvents, including different pyridine/benzene and dimethyl sulfoxide/benzene mixtures. The amount of hydroxylic hydrogen remaining immobile (f_<IM(OH)>) was experimentally determined by using pulsed ^1H NMR technique as a function of the swelling ratio (Q). These observations were theoretically assessed by using the association model. The model yields a equilibrium constants for the formation of hydrogen bonds between coal molecules, K_B. Given the K_B, the Flory-Huggins equation was partially modified to account for hydrogen bonding. The modified equation was applied to the coal, resulting that the number of statistical segments between junction points is small.

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Adsorption measurements of pyridine onto a coal were performed for estimating adsorption isotherm, adsorption rate, and heat of adsorption The coal sample adsorbing pyridine was heated from room temperature up to 200℃ in an inert atmosphere, during which FTIR spectra were obtained in every 20℃ using an in-situ spectrometer. The strength distribution of hydrogen bonding (HBD) at each temperature was well estimated by analyzing the FTIR spectra by the method proposed by the authors. By utilizing the HBD the changes in enthalpies through the desorption of water and pyridine were estimated. Based on these measurements and analyses the interaction between coal and pyridine was quantitatively analyzed.

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Asphaltene, which was obtained from the residue of coal liquefaction plant, was dissolved in N-methyl-2-pyrrolidinone (NMP) and 1-methylnaphthalene (MN). The surface tension was measured for these solutions by Wilhelmy plate method. In the plot of the surface tension against the asphaltene concentration, a discontinuity point considered to correspond to the critical micelle concentration was observed. From the comparison of the results in NMP and MN solutions, it seems that the micellization of asphaltene easily occurred in the non-polar solvent, MN.

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Glass to rubber transitions in four different kinds of coals ranging from lignite to bituminous, were examined by using gas pycnometry in which helium was used as a probe molecule. The specific volumes of the coal samples were measured in the temperature range between 323 and 423K. The specific volumes of the samples were increased with temperature due to their thermal expansion. The clear discontinuous points were observed at around 380K in temperature-specific volumes plots for Beulah Zap lignite and Upper Freeport coals, Suggesting that these coals have glass to rubber transition at this temperature.

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The effect of tetrabutylammonium acetate (TBAA) addition on the aggregation of heavy coal extract component; pyridine insoluble (PI) from the extraction of Upper Freeport (UF) coal with carbon disulfide-N-methyl-2-pyrrolidinone (CS_2-NMP) mixed solvent (1:1 by volume) was investigated. PI is partially insoluble in the mixed solvent, but the addition of a small amount of TBAA, the almost entire PI molecules become soluble in the mixed solvent. Recovered PI (PI-1) obtained by the removal of CS_2, NMP and TBAA from the solution was found to become almost completely soluble in the mixed solvent and NMP. The dissolution mechanism was discussed from the change of the aggregation state of PI at solution and solid states.

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The effect of addition of various salts, the anions of which were changed systematically, on the extraction of seven different kinds of coals with carbon disulfide-N-methyl-2-pyrrolidinone (CS_2-NMP) mixed solvent (1:1 by volume) was investigated. Addition of some salts considerably increased the extraction yields of some coals. For Upper Freeport coal, in particular, the addition of very small amount, 0.25mol/kg-coal of tetrabutylammoniumfluoride (TBAF) increased the extraction yield from 59 to 84%. The effect of the anion type on the extraction yield was also examined. In the case of halogenide ions, the smaller ion was added, the higher extraction yield was gained. HSAB rule (Hard and Soft Acids and Bases) was applied to explain the relationship between the extraction yield and the anion property. The fractionations of the extracts indicate that the extracts produced with the additive contain heavier and aromatic-richer constituents than that without additives. Acid-base interactions between acidic sites of the coal samples and the anions were focused and the effect of modifying of coals to the extraction yield was investigated by means of O-methylation and acid treatment.

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This study aims at an extension of our concept of physical property estimations of hydrocarbon mixtures to boiling point estimation for hetero compounds such as phenols, pyridines, carbazoles and thiophenes in heavy oils. The estimation takes into account that the boiling points of the hetero compounds with the characteristic functional groups such as hydroxy and amino groups are higher than the reference hydrocarbon having the same molecular weight and skeleton structure and further that the boiling points of hetero compounds gradually approach to those of reference hydrocarbons with an increase in molecular weight. Plots of the ratio of the boiling point of a hetero compound to that of its reference hydrocarbon against the reciprocal of the carbon number gave approximately straight lines, which intersect the ordinate of 1. The slopes varied with the number of aromatic rings, and the type of rings such as furan, pyrole and thiophene. Based on the above findings, an equation was established by regression analysis for calculating boiling point of hetero compounds. Thus, the calculated boiling points of hetero compounds are in good agreement with those observed.

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Coal-like materials, model coals, were prepared from the thermal decomposition of cellulose and a phenolic nitrogen compound, and glicine and glucose. They were hydrogenated and characterized by Py-GC and Py-GCMS, and the nitrogen compounds in the hydrogenated products were compared with those of natural coal.

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We have recently found that some bituminous coals can be extracted up to 75% in a flowing tetralin at 350℃ without appreciable decomposition. To extend this method for the practical application, several coals were extracted by coal derived oils, carbol oil and creosote oil, under 10MPa at 350℃. Almost all the bituminous coals and brown coals were surprisingly extracted by 80% in carbol oil at 350℃. The extract was recovered as a soluble fraction (soluble) at room temperature. The contents of ash and sulfur compounds in the soluble were measured to examine the possibility of deashing and desulfurization of coal by solvent extraction. This suggests the possibility of preparing clean fuel from coal in high yield.

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Direct coal injection to a gas turbine is expected as an advanced high efficiency power generation technology. In this case, feed coal must be ash-free and alkaline and alkaline earth metal-free to prevent erosion and corrosion of turbine blade. In this study, ion exchange treatment of coal was investigated to remove Na, K, Ca and Mg.

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To increase the coal utilization, it is essential to reduce CO_2 emission by developing more efficient coal combustion systems, such as gas turbines, than the conventional PCF systems. In order to fire coals in gas turbines, however, coal should be ash-free. As a fundamental study for producing Ash-free coal (named HyperCoal), coal extraction and filtration tests were performed using several kinds of coals and organic solvents. A coal extraction rate was increased with the increase in extraction temperature. As a result, 40wt% of bituminous Nantun coal was extracted with 1-methylnaphthalene and ash content in the extracted coal decreased to 200ppm.

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Upgrading of low rank coal and biomass for the production of solid fuel and chemicals is considered to be the most promising topics from the environmental point of view. In this study, liquid-phase cracking of low rank coal (Taiheiyo, Buckskin, Yallourn and Fortuna coals), Beech wood and Maize, which are rich in oxygen, having low heating value were investigated. Decrease of heteroatoms, mainly oxygen by the reaction at 350〜440℃ using decalin as solvent under 2MPa of initial nitrogen atmosphere is obvious. The behaviors of spontaneous ignition of the upgraded product and carbonization by reaction condition are discussed by TG and X-ray measurement respectively.

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The recycling process of waste plastics using coke ovens is now being studied. The effect of plastic addition on coal caking property was investigated. The addition of polystyrene (PS), polyethylene terephthalate (PET) and terephtalic acid (TFA) decreased the maximum fluidity and total dilatation. The decomposition temperature range of these plastics were lower than or within the coal thermoplastic temperature range. The radical formation as a result of PS decomposition might be the cause of the changes in caking properties.

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A new control method was developed for toxic metal ion elution from fly ash in an acid solution. Coated fly ash pellets were prepared by covering with bottom ash produced from the same coal-fired boiler and subsequent sintering at 1300℃. The elution test was carried out in the acid solution of pH3,4 and 5.5 for the fly ash pellets with and without the bottom ash coating. The coating of fly ash pellet suppressed the elution of lead ion, independent of acidity of solution, while the fly ash pellet without coating showed an increase of lead elution with lowering of pH.

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To improve performance of absorbent for H_2S, various zinc ferrites were prepared. Zinc ferrite prepared on activated carbon exhibited a high specific surface area and afforded a high performance to H_2S absorption at 400〜500℃. AC-loaded zinc ferrite could be regenerated With air oxidation at 460℃. The regenerated ferrite showed the same H_2S absorption capability as that of fresh one.

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Characteristics of SO_2 emission of a PFBC (Pressurized Fluidized Bed Combustion) were studied with the data of a test apparatus and a commercial plant. Concentration of SO_2 at the furnace exit decreased as oxygen concentration and bed temperature increased. And SO_2 concentration decreased with decreasing load of the plant. This load dependence was thought to be caused by the high CaO concentration in bed material (BM). As the load decreased, CO_2 partial pressure decreased and low CO_2 partial pressure accelerated a production of CaO from CaCO_3. On the other hand, gradual change of SO_2 removal was observed in the operation. This phenomenon occurred because of the change of the condition of BM surfaces.

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Fly ashes trapped on the ceramic tube filter of PFBC were analyzed In detail by SEM and EDAX to account their behaviors on the filter, and desulfurization activity, Fine particles were found adhered on the larger grains, suggesting high reactivity of the for me ash minerals.

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We have shown that Loy Yang could be liquified by treatments in supercritical alcohols to give phenols such as phenol, cresols and xylenols as well as unidentified heavy components. In the present study, we conducted a preliminary study on preparation of carbon fibers from the heavy components obtained by decomposition of Loy Yang with supercritical iso-propanol at conditions of 400℃ and 280kg/cm^2. The obtained liquid products were fractionated with THE and hexane, then the obtained TS-HI and HS fractions were subjected to inspections of thermal behavior, spinnability, stabilization treatment and carbonization behavior. Particularly HS showed an excellent spinnability, so this component was spun into fiber after heat treated at 200℃ for 15min. Stabilization with an acidic formaldehyde aq. soln gave an increase in the carbon yield for carbonization up to 500℃, however finally gave only 24% of yield at 1000℃ without leaving fiber forms. It was concluded that preparing carbon fibers from brown coals should be possible by some improvements of HS component such as increasing the melting points and finding a proper stabilization techniques.

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In recent years, the development of the recycling technique for the waste plastics has become very important. For making waste plastics raw materials, the study of the waste plastics recycling process using the coke oven was examined. As a result, it was found that the waste plastics recycling process with coal in the coke oven is suitable to produce coke, tar, light oil and gas without deterioration of the coke strength.

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A new monitoring system for gas generation behavior during coking reaction has been established. Cole sample in nitrogen flow was heated with an electric furnace, and generated gas was lead to Fourier-transform infrared spectroscopic analyzer and a gas sensor for hydrogen with nitrogen gas carrier. This method has a good time-resolved of second order, so that a short time reaction of coal pyrolysis can be monitored continuously. Using this system, different gas profiles on coking reaction of two coals with opposite characters could be obtained.

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Scanning electron microscope combined with energy dispersive X-ray analysis (SEM-EDX) was used to identify inorganic species in coal ash and to measure the particle size distribution and element composition. Ashes in raw and acid-treated Nantong coal prepared by low temperature ashing (LTA) and high temperature ashing (HTA) were used as sample. Silicate-rich particles showed agglomerate shape, but aluminate-rich particles showed layer-like shape. Silicate appears to cover the aluminate particle surface. Calcium was found in ash of the raw coal, not in ash from the acid treated coal. It is noted that a small amount of aluminate was removed by the mild acid treatment. It seems that fine particle aluminates disappeared from HTA ash by the acid treatment, while the morphology of LTA ash stayed unchanged regardless of the acid treatment.

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Inorganic constituents in coal are classified into two parts; mineral matter and organically associated cation. The leaching of coal with ammonium acetate is widely used to remove organically associated cation and leave discrete mineral matter intact. In this study, we carried out the leaching of coal with several kinds of solvents to know whether the leaching with ammonium acetate or other solvents can remove only the organically associated cation. It is found that not only organically associated cation but also calcite was removed by the leaching with ammonium acetate.

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For several standard coals, the contents of trace heavy metals were determined by use of microwave-digestion and ICP-AES. When powdery coals were shaken with an aqueous solution containing EDTA, some heavy metals, such as Mn, Pb, and Zn, were efficiently leached. When a coal fly ash was shaken with an aqueous solution of gluconic acid, As was favorably removed.

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Three coals are subjected to combustion in the drop tube furnace. One kind of limestone, mixed with coal physically, is used for in situ simultaneous removal of SOx and halogen during coal combustion. The results show that SOx and halogen capture ability of added limestone varies with coal type and residence time. At a residence time of about 2.0s and the Ca/S molar ratio of ca. 2.0, a SOx removal of 89% and halogen removal of 50% could be achieved for Yanzhou with high Sulfur, while 50% SOx and 100% halogen removed for the other two coals. SEM-EDX results indicate that part of added calcium reacted with internal minerals to form Ca Al-Silicate or more complex compounds, which significantly decreases the calcium utilization efficiency.

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In order to evaluate the spontaneous combustion of coal, we conducted basic tests on the laboratory level and coal stockpile tests with a 5,000-ton simulated pile, using the same coal. Based on these results, we studied the relationship between the properties of coals and the basic test and the simulated-pile test results, the temperature-increase behavior in the simulated pile, and the changes in the composition of the gas within the pile. We report on what was learned concerning the relationship between spontaneous combustion and physical properties values indicating the degree of coalification, the mechanism of spontaneous combustion in the simulated pile, and methods of inhibition.

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Release of volatile-N (tar-N, HCN and NH_3) from 11 coals during pyrolysis at 400K/min has been studied with a fixed bed quartz reactor, and factors controlling volatile-N have been examined. When demineralized coals are pyrolyzed at 1035℃, NH_3 decreases but tar-N increases for all coals. Addition of Ca catalyst after demineralization promotes NH_3 formation at 700-135℃, whereas it suppresses tar-N. Ca catalysts are transformed upon pyrolysis into fine particles of CaO. It is suggested that the highly dispersed CaO particles catalyze NH_3 formation through the secondary decomposition of tar-N and solidphase reactions of char-N above 1000℃.

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Flash pyrolysis of five types of coals was carried out in a temperature range from 700 to 850℃ under 1.0MPa of He and H_2 using a free fall reactor. Good mass balance was obtained by taking the amount of deposited carbon into consideration. Cenosphere was formed by flash pyrolysis of some coals. CO_2-gasification reactivity of the cenosphere was lower than the char of normal morphology.

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