Carbon materials exert growth-promoting effect on certain kind of microorganisms through emitting ultra-sonic signal created by photo-acoustic effect.

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Long-term hydrous treatments of two brown coals (A coal and B coal) were investigated. The experiments were carried out in a batch reactor under nitrogen atmosphere at 350℃ for 2-72h. Oil from the treatment of B coal was less than A coal. The products from each coal were analyzed to discuss the differences in chemical structural features of the original coals and the treated coals and to evaluate structural changes.

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Water treatments of Argonne Premium coals were carried out at 500 and 600K, and the effect of the treatments on the extraction yields with CS_2/N-methyl-2-pyrrolidinone (NMP) mixed solvent and other single solvents such as NMP and 1-methylnaphthalene was investigated. The mechanism for the extraction yield enhancement by the water treatment was discussed.

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We have presented a new coal solvent extraction method that realizes not only demineralization of coal but also coal fractionation in terms of molecular mass. It was found that five extraction steps could fractionate the coal into 8 fractions. Ultimate analysis and molecular mass measurement showed that the fractions obtained at lower temperature consisted of smaller molecular mass compounds which were existent in the parent coal and have larger atomic H/C ratio. H-NMR analysis indicated that the chemical structures of the extracts obtained below 300℃ were rather close.

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Ashless coal (HyperCoal) was produced through solvent extraction of coals at 360℃. An attempt at searching a powerful solvent to produce HyperCoal more efficiently was made. Some polar constituents fractionated from crude methyl-naphthalene oil (CMNO) were used as the extraction solvent. It was found that one constituent gave high extraction yields of 63-73wt% (daf) for Wyodak Anderson subbituminous coal. The reason for the high yields was explained by effect of indole contained in the fractionated solvent.

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In order to obtain high yields of "HyperCoal" (ash-free coal), the effect of CO_2/H_2O pretreatment on the extraction yields for low-rank coals using cost-effective industrial solvents such as CMNO and CQ, was investigated. A remarkable positive effect of CO_2/H_2O pretreatment was found under lower treatment pressures (0.1-0.5MPa); the thermal extraction yields at 360℃ were increased by 7-15%, resulting in the high extraction yields of about 52% and 45% for WY coal and ND coal, respectively. In addition, 4-11% higher extraction yields were obtained for pretreated WY coal with CMNO at lower extraction temperatures (320-360℃), than those for the untreated coals.

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This study concerns with applying the Hyper-coal process for the low rank coal upgrading. Hyper-coal process has been developed based on the solvent de-ashing technology. Coal is extracted with coal derivative 2-ring aromatic recycle solvent and insoluble matter is removed by gravity settling. From the coal extraction examination with a number of coals, we found that the Hyper-coal yields of brown coals were not higher (20-40wt.% daf), but the heat values of both Hyper-coal and the insoluble coal were highly increased by the effects of the elimination reactions of the oxygen containing functional groups. It was observed that the carboxyl group and the hydroxyl group were constantly decreased with the increase in temperature, but the ether linkage was suddenly increased at 350-400℃. There was a possibility that such a bridge formation inhibited the coal dissolving.

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Effect of mild air-oxidation on non-fluidization of "HyperCoals" (ash-free coal) which were produced by thermal extraction (370℃) with organic solvent, was investigated using the dynamic viscoelastic technique with a temperature-variable rheometer. Fluidity of HyperCoals was reduced greatly by air-oxidation at 200℃ with calorific loss of 3-4%. Mechanism of oxidation on the non-fluidization was discussed based on the structural analysis.

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[in Japanese]

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Desulfurization using Ca ion-exchanged brown coal was studied at moderate temperature of 300〜400℃. Ca loading of Ca ion-exchange brown coal was very important factor on desulfurization. The calcium conversions of high Ca loading samples such as 7 and 13wt% were lower than those of lower Ca loading samples. The specific surface areas of high Ca loading samples were lower than those of low Ca loading samples. The diffusion rate of SO_2 gas through the pore in Ca loaded char may affect the calcium conversion.

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Simultaneous removal of COS and H_2S was studied at 400℃ using a commercial active carbon and a gasified coal char. The char obtained from CO_2 gasification of a brown coal showed high performance in the removal of COS and H_2S. Demineralization of the coal lowered the ability of the char to remove H_2S, but showed little influence on the removal of COS. It indicates that COS and H_2S may be removed through different mechanisms.

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Biodesulfurisation (BDS) of coal by use of Thiobacillus ferrooxidans was examined. For three Argonne premium coals, the % removal of inorganic S was 56-85% when the BDS was carried out for 30 days. An appreciable correlation was observed between the amounts of S and Fe leached. The % removals of S and trace elements obtained for the BDS were comparable to those when an acid-leaching was performed. The amount of acid used for the BDS was much less than that for the acid-leaching.

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When various coals were subjected to hot water extraction (HWE), the leaching of organic matters from coal was examined and evaluated in terms of total organic carbon (TOC). The degree of TOC in the HWE eluent greatly varied with kind of coals, and it tended to increase as the O/C value of coal increased. The degree of TOC in the eluent was also affected by specific surface area of coal. Ecotoxicities of the HWE eluents were evaluated by the Ames Salmonella mutagenicity assay and the estrogen receptor binding assay. The same examination was investigated for the elution behavior of organic matters in the waste water from hydrothermal treatment process.

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A Wyodak coal (WD coal) and an Illinois No.6 (IL coal) were thermally extracted with N-methy-2-pyrrolidone (NMP) and 1-methynaphthalene (1-MN) to produce clean coal extract. This study has focused on the behaviors of major and trace metals with various extraction processes. It was found that the extraction with 1-MN achieved 60-100% reductions in the concentration of Li, Be, V, Ga, As, Sr, Cd, Ba, Hg, and Pb. The extraction with NMP yielded more extract than with 1-MN, but it retained more organically associated major and trace metals in the extracts. The acid pretreatment not only substantially increased the extraction yield in the extraction of WD coal with NMP but also significantly reduced the concentrations of alkaline earth elements such as Ca, Mg, Be, Sr, and Ba.

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Ash particles in gasified coal chars were analyzed by a computer-controlled scanning electron microscope (CCSEM) to understand the fate of organically associated metal, especially organically associated calcium, during gasification. From the CCSEM analysis, it was found that organically associated calcium was first converted into fine Ca-containing fine particles during devolatilization process and then the fine particles interacted with kaolinite to form complex aluminosilicate during gasification. Such Ca-containing aluminosilicates would promote coalescence or agglomeration of mineral particles.

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Four kinds of coal samples whose Cl-contents vary from 30ppm to 300ppm were pyrolyzed and burned, and the release behavior of Zn was examined. In the coal pyrolysis step, as the increase of Cl contents in coal, the release amounts of Zn also increased. It was considered that the generation of ZnCl2 was one reason for Zn emission. In the coal combustion, a part of Zn was released as ZnCl2 and the other part was remained in the ash as non-volatile ZnO, because some of Zn in the coal was reacted with Cl and others were oxidized during volatilization.

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It is reported that the ion-exchanged calcium deeply participates to formation of PM_<2.5>. In this study, the reaction between ion-exchanged calcium and organically combined Si during heat treatment was investigated using model compounds, as a fundamental study of PM_<2.5> formation.

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About half amount of the Cl in a sub-bituminous coal is released as HCl in the fixed bed pyrolysis, the rest being retained mostly in the pyrolyzed char. In the CO_2 gasification at 1000℃ and 2.5MPa, HCl can not be detected significantly, and about 90% of the Cl in the char remains unreleased at char conversion of 50%. When the pulverized coal is injected into an O_2-blown, entrained bed gasifier at 1200-1400℃ and 2.6MPa, the partial oxidation of the resulting char proceeds, and conversion of the C in it reaches 95%, whereas the Cl is delayed to be gasified compared with the C and thus enriched in the remaining char even at the latter stage of reaction.

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Six Chinese coals were subjected to pyrolysis in N_2 at the temperatures ranging from 1200 to 1450℃. Emission of metals and their combination with the organic carbon were studied by investigating the properties of sub-micron particles formed from coal pyrolysis. The sub-micron particles were size-segregated by low-pressure-impactor; each size was characterized for its elemental composition, microstructure, etc. Finally, the emission of individual metal was linked with its existence in raw coals. The results indicated that, a multi-mode distribution was formed for most of the metals during coal pyrolysis. At least three peaks, 0.06 or smaller, 0.2 and 2.5μm were formed. The smallest one was assigned as those formed by the decomposition of organically bound metals in raw coals, the medium size was caused by the release of included inorganic metals in the char, whereas the largest one was to large extent linked with the excluded inorganic metals in raw coals. The emission degree as well as the magnitude of each peak in the particle size distribution varies with the elemental type greatly. The influence of reaction temperature was significant too.

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To develop gas clean-up methods of coal and/or biomass gasification gas during high temperature condition, various kinds of sorbent are prepared. Mineral matter, inorganic matter and Ca compounds are mixed for the sorbents. The US-16 sorbent containing compound A mainly had maximum adsorption. The surface of the sorbent was analyzed by SEM and XPS, and control factors of adsorption were investigated.

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Mercury distribution in fly ash from a pulverized coal fired plant was investigated for three coals to elucidate the partitioning mechanisms in combustion processes. The fly ashes were classified by an acoustic sieve. Obtained seven classes of particle diameter was measured its Hg content. It is found that mercury concentration in the sieved fly ash is increased with increasing the average particle diameter. Since large size particles contain much unburned carbons, mercury seemed to be adsorbed on its surface. Relation between unburned carbon and Hg concentration had good correlation for three coal types, however, other factors such as surface area and carbon structure of the unburned carbons should be investigated to establish the Hg partitioning mechanisms on solid phase.

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The partitioning behavior of boron in pulverized coal combustion is investigated to estimate boron concentration in waste water from power station. Boron content in fly ash that was collected by cyclone is analyzed for ten coals. Boron recovery is different from coal type; for example, a significant amount of boron is retained in the fly ash for some types of coal. The recovery is compared with boron content and various properties of the coal and the fly ash. However, almost all the properties have not directly correlation with the boron recovery, although Ca and Mg content in fly ash indicates roughly relationship. To clear effects of coal types on the partitioning behavior of boron, it is important to understand boron vaporization process and coagulation process. Fundamental tests for boron vaporization also were performed to determine control process of boron behavior during combustion.

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Boron emissions and unburned carbon during pulverized coal combustion in the drop tube furnace (DTF) were measured, and the rate constant was determined. Computational fluid dynamics (CFD) simulation was applied to estimate thermal history with unburned carbon and boron emissions. The rate constant of boron emissions was calculated for a coal under calculated 1-D temperature distribution.

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A prediction, prompt detection and suitable control of ash deposition on heat transfer surface are one of the most important factors for a stable and highly efficient operation of pulverized coal fired boiler. In order to directly observe a clinker formation behavior, high temperature resistant CCD camera was installed at the actual boiler. This observation was quite useful to determine the location and extent of clinker formation.

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The behavior of recycling ash and volatile elements in char recycling line of an entrained bed gasifier were predicted by FactSage/Aspen Plus/ChemAPP computer packages. The accuracy of the prediction was above practical level. B, Cl, Cu, F, K, P, S, V, and Zn were sensitive elements in the gasifier. B, Cl, Cu, F, K, P, Ti, and Zn elements were enriched in recycle line. It is important to monitor the composition of recycled ash. If the gasifier operates for a long time, the concentrations of Zn, Cl, F and B will become high level.

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Calcination/carbonation reactions of calcium compound were performed in atmospheric and pressurized thermogravimetri analyzer (TGA). Raw limestone and in limestone with 10%wt of coal ash were used as samples. Calcination rate of re-carbonated CaCO_3 become slower after 5^<th> cycle of calcination/carbonation reactions in atmospheric TGA, and it became uncompleted calcination in pressurized TGA. Ash addition accelerated calcinaton reactions of re-carbonated CaCO_3 in atmospheric and pressurized TGA. Crysitallization of CaCO_3 was suggested to decrease calcination reaction rate of re-carbonated CaCO_3. Ash addition prevented crystallization through reaction of CaO with ash to form calcium aluminosilicate compounds.

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The Thermoselect process is a completely new solid waste treatment process which achieves pollution-free recycling of municipal solid waste and industrial waste by a high temperature gasification and reforming process. The process effectively recovers fuel gas from waste and recycles metal and other byproducts as resources. A stable gas engine power generation system using purified synthesis gas from the Thermoselect process was also developed.

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We have made a study to use waste wood as a coke making material. The 3 mass% addition of raw waste wood into coal charge deteriorated coke qualities (I^<600>_<9.5>; measured with I-type drum tester). However preheating of waste wood at appropriate temperature improved the coke qualities. To get the reason, the gieseler maximum fluidity (MF) of coal blended with raw or preheated wood samples were measured, because the fluidity of coal has relation to coke strength. Raw waste wood addition to coal showed considerable decrease in MF. However pretreated wood addition showed minor decrease in fluidity.

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The coke forming process during the carbonization of coal is poorly understood because of the difficulty of the analysis of the solid amorphous carbons, although it is recognized that the carbonization process affects significantly the strength of cokes produced. Raman spectroscopy has been well known to be powerful to characterize graphitic carbons. In this study, it was utilized to characterize amorphous carbons prepared from the carbonization of coal. The absolute intensity of the spectrum was found to decrease with the increase of the final temperature. The decrease was well correlated with the yield of H_2, indicating that the Raman spectrum reflects the degree of carbonization of coal.

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Steam gasification of two Hyper-coals with the physical addition of about 6% K_2CO_3 was conducted at 1023K on a thermogravimetric apparatus equipped with an on-line quadruple mass spectrometer. The catalytic gasification of the Hyper-coals demonstrated much higher gasification rate than the catalytic gasification of the raw coals. Interaction of K_2CO_3 with mineral matter in raw coal formed water-insoluble potassium compounds such as potassium aluminosilicates and thus reduced the catalytic activity, while no such negative reactions occurred for the Hyper-coals. The steam gasification of the Hyper-coals with K_2CO_3 was also found to be favorable for the high-yield production of hydrogen.

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Reaction rates of char gasification and CaO hydration which are two important reactions in the HyPr-RING method for hydrogen production were investigated. Various kinds of char, and char/CaO mixture were gasified with high pressure steam by using a flow-type reactor. It was found that, with CaO addition the hydrogen produced from char gasification was higher about 10-20% than that from char only gasification. Lignite and sub-bituminous coals had higher conversion to hydrogen than that of the high rank coals. CaO hydration rate was measured by using a high pressure TGA technique. CaO converted nearly 100% at high temperature 923K in about 5 minutes.

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In order to clarify mechanism in deactivation of Ca-based sorbents caused by solid-solid interaction with coal-derived minerals during lime-enhanced steam gasification of coal, first, multi-cycle CO_2 sorption tests of sorbents/ash mixtures at elevated temperature and pressure were performed with a laboratory-scale horizontal-tube reactor. The sorbents tended to undergo a solid-solid reaction with ash components during multi-cycle CO_2 sorption with an intermediate hydration stage. This reaction formed complex inorganics and substantially decreased the sorbents' CO_2 sorption ability. This chemical interaction was further examined by chemical analyses of residual solids obtained from high-pressure steam gasification of coal/sorbent mixtures. Our results indicate that the solid-solid interaction became significant at the higher temperature.

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On the co-liquefaction of high rank coal (Huaipei coal) and Co exchanged low rank coal (Adaro coal), the yield of residue was higher than the yield calculated from those individual liquefactions. On the other hand, the yield of residue was lower than the calculated yield on the co-liquefaction of Yilan coal and Co exchanged Morwell coal. It was considered that the catalytic effect of Co for the liquefaction of coal appeared due to the fine dispersion of Co on the coal surface.

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The pyrolysis and hydrogasification behavior of ion-exchanged nickel species supported on Loy Yang brown coal was studied. The evolution profiles of volatile components during pyrolysis and hydrogasification were affected by the amount of exchanged nickel species. For pyrolysis, two peaks of CO evolution appeared, one at 650-770K, depending on the amount of exchanged nickel species and the other at ca. 880K, comparable to a broader peak at 870K for an acid washed coal. The CO evolution peaks became larger with increasing nickel loading. The CO_2 evolution peak appeared at 650K and it became larger with increasing nickel loading, and a new CO_2 evolution peak appeared at 850K for the nickel loadings more than 4.2wt%, which was negligible for the acid-washed coal. The decomposition behavior of Loy Yang coal is explained by the aggregation behavior of nickel species. For hydrogasification, the peak of CH_4 evolution appeared at 860-1010K, depending on the amount of exchanged nickel species, became larger with increasing nickel loading. The total amounts of CO evolved were not enhanced by the presence of nickel, however, the maximum temperature shifted to 640-700K, depending on the amounts of exchanged nickel species, comparable to a broader peak at 810K for the acid washed coal. The CO_2 evolution peak at 650K became slightly greater with nickel loadings, but the peak top temperature did not change. Larger nickel metal particles catalyzed the CH_4 formation from the Loy Yang coal under hydrogen atmosphere.

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Coal gasification in entrained bed type of gasifier is performed under high temperature (〜1400℃), high pressure (〜3MPa), and high heating rate of coal particles (〜10,000K/s). Then little is known on the pyrolysis and gasification behavior of coal in the entrained bed type of gasifier due to experimental difficulty. In this paper coal pyrolysis was performed using a pressurized drop tube furnace (PDTF) which can simulate the entrained bed gasifier very well. The pyrolysis behavior was examined in detail, and detailed characterization of the solid product was also performed. These examinations clarified that the pyrolysis behavior of coal in the entrained bed gasifier is significantly different from that under ambient pressure and slow heating rate.

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In order to clarify the influence among ash behavior, carbonaceous structural change and char reactivity, the analysis method from a microscopic viewpoint was proposed. This novel method utilized overlaying both the distribution mapping of carbonaceous structure by LRS and the distribution mapping of elements by SEM/EDX. Consequently, the function of ash content on carbonaceous structure was clarified by this novel method.

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In order to elucidate the secondary reaction process in the coal pyrolysis, SRI's result obtained by Radiant Coal Flow Reactor was analized in the same way as AIST did. In the case of SRI, carbon deposition on char has almost never been found in the carbon balance. Water-gas reaction and shift conversion proceeded more slowly than in AIST. The differrence in reaction behaviors between AIST and SRI suggested that the temperature of the gas and the concentration of coal particles and volatile matter in the reaction chamber affected on the progress of the secondary reactions.

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Mixture of a coal and three kinds of plastics was liquefied by using a non-hydrogen donor solvent, the effects of reaction temperature and time on the coprocessing were investigated. Radicals are derived from coal at about 300℃, those attack plastics. Therefore, the possibility of a lowering of the initial reaction temperature on this coprocessing was suggested. The combination of radicals from coal and plastics produced radicals having large molecular weight, so the yield of residue increased. The residue decomposed with the increase of the reaction time. As the reaction temperature increased, the decomposition rate of residue was becoming faster. However, the over-decomposition of plastic radicals occurred, the interaction of radicals from plastics and coal would be inhibited. In conclusion, the increase of reaction time rather than that of reaction temperature was effective for the appearance of interaction of coal and plastics to bring about the decrease of residue.

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Gasification technology of solid fuels in molten carbonates has been selected as one of the advanced gasification systems. The molten carbonates employed in this study are eutectic salts of Na_2CO_3 (43mol%) and K_2CO_3 (57mol%). As the advantages of utilization of the eutectic salts for coal gasification, the alkali metals play a role for the gasification catalyst, desulfurization solvent and capture material of ash particles. The gasification test results show that the main compositions in the product gas are CO and H_2. H_2S and COS concentrations in the product gas is low enough to introduce the gasified gas into an Molten Carbonate Fuel Cell (MCFC) system, in which H_2S and COS concentrations should be less than 1ppm in the gasified gas.

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The grindability, the air carrier ability and the combustion characteristics in woody biomass co-firing with coal were investigated by a coal combustion test facility (combustion rate: 100kg/h). The almost of woody biomass after grinding became fiber form. The size was larger than pulverized coal particles. When the length of fiber was extremely long, the carrier air pipe was blocked with biomass fiber. At two-stage combustion ratio of 30%, NO_x concentration in co-firing of woody biomass was lower than that in coal combustion. In case of co-firing for bark, the unburned carbon concentration in fly ash increased in comparison with coal combustion.

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Catalytic decomposition of NH_3 in inert gas, syngas (CO/H_2=2), H_2O and H_2S has been studied with a fixed bed quartz reactor to develop a novel hot gas cleanup method of removing NH_3 from coal gasification products. Limonite with a large amount of α-FeOOH achieves the complete decomposition of 2000ppm NH_3 diluted with He at ≧550℃, and such a high performance is stable. The coexistence of syngas lowers considerably the catalytic activity at 850℃, whereas the addition of H_2O to syngas restores the performance to the high level without syngas. Further, the limonite is very active even in the presence of 100ppm H_2S, and it maintains NH_3 conversion of 100% during 50h reaction. The limonite is thus promising as the catalyst for NH_3 decomposition.

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Kinetics on in-situ CO_2 removal gasification of woody biomass for hydrogen production in elevated temperature was fundamentally examined. From the experimental results using an autoclave, it is found that primary degradation, which is degradation of woody biomass, mainly controls degradation characteristics under 500℃ and that secondary degradation, which is conversion of tar to gas, strongly progresses above 500℃. The each kinetic parameter was obtained from these results. The activation energies were 21.4-34.9kJ/mol for the primary degradation and the activation energy for the secondary degradation was 29.3kJ/mol. Although they were relatively small value, it might depend on lower heating rate and presence of a CO_2 sorbent.

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In H_2 production from woody biomass by steam gasification in the presence of a CO_2 sorbent (CO_2 absorptive gasification), the effect of the types of woody biomass and a CO_2 sorbent was investigated on gasification such as H_2 yield at 650℃, 0.9MPa using a conventional autoclave. Japanese oak, Japanese cedar, and Japanese red pine bark were employed as a biomass feedstock. MgO, CaO, SrO, and BaO were used as a CO_2 sorbent. In all runs, the product gas mainly contained clean gas such as H_2 and CH_4, and no CO_2. The H_2 yields on a carbon basis in the feedstock were 0.48 to 0.60 H_2-mol/C-mol, and were almost independent of the type of biomass feedstock. The gasification of lignin in the woody biomass could largely contribute to the H_2 production in the CO_2 absorptive gasification. The H_2 yields in CaO, SrO, and BaO were almost 0.55 to 0.59 H_2-mol/C-mol, and were higher than that in MgO (0.17 H_2-mol/C-mol).

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A production of carbon nanotube (CNT) from heavy hydrocarbons such as natural asphalt and petroleum heavy oils by chemical vapor deposition (CVD) method with iron catalyst was explored. Under selected conditions including the reaction temperature and the amount of catalyst, CNT with diameter of 10-100nm was successfully found.

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A novel gasification of biomass using black liquor was conducted. Woody biomass was gasified with black liquor in H_2O atmosphere in a thermo-balance or autoclave reactor. Na compounds in black liquor enormously enhanced the gasification rate of woody biomass char. The characteristics of carbonaceous material produced from black liquor were investigated in detail.

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