Coal accounts for 21% of the primary energy supply of our country. Also, coal is important energy in which the economic stabilization extremely in not only Japan but also countries of Asia-Pacific Region. 99% of the coal consumed in Japan is import coal, and securing the stable supply is indispensable to the continuation development of our country. On the other hand, there is a possibility of obstructing stable safety production from the deterioration of resource development. However, the mining condition such as decreasing in economical reserves and making of the mining area deep, occurrences of the grave accident or the restrictions of an environmental restriction etc. in the coal-producing country in the Asia-Pacific Region. The colliery technology corresponding to a complex mining condition is accumulated in our country. The resource system engineer’s securing becomes a problem recently though an overseas resource has been evaluated from a multipronged technical field and the overall aspect.
Indonesia produces over 150million tons of clean coal annually. In Indonesia, most of the coal produced is extracted from opencut mines. Some coal measure rocks are soft in dynamic characteristic and show severely slaking behavior affected by water. Because of tropical rainforest climate, a great variety of problems, such as acid mine drainage, connecting with rock slaking and attendant structural damages have been faced. Accordingly, it is necessary to proceed an effective rehabilitation system which can minimize negative environmental impact of mining activity. This paper describes the slaking behavior of coal measure rocks and the incidence of acid water at Tanjung Enim opencut coal mine in Indonesia. The results shows following highlights: (1) incidence of acid water based on the result of water quality analysis, (2) relationship between the ratio of revegetated area and control acid mine drainage, and (3) slaking behavior of coal measured rocks categorized by NAG test.
A national project on a carbon dioxide (CO2) sequestration has been carried out from 2002 by injecting CO2 into one of the Ishikari coal seams located at the Minami Ishikari Coal Field in Hokkaido, Japan. The coal seam lies at 890 m under the surface with in-situ conditions of 29°C in temperature and 11MPa in static stress. Even if super critical CO2 over 70°C and 8 MPa is supplied at the surface, it becomes liquid CO2 with 29°C and 15MPa at the bottom of injector due to heat loss to low temperature strata and creates a problem of coal seam permeability reduction around the injector. Thus, coal characteristics for liquid CO2 injection are very important to carry out the project. However, measurements of permeability and coal swelling factor for liquid CO2 has not been presented and visualized clearly. In this study, the permeability and swelling of a core sample drilled from the coal seam has been investigated. Furthermore CO2 adsorption/desorption properties of the coal have been measured using with a volumetric method with comparisons of coal samples mined from the Kushiro Coal Mine. As a result, the swelling of the coal matrix has been observed clearly by visualization pictures of crushed coal sample and a hole drilled in the coal core sample sunk in CO2 liquid. The ratio of its area reduction by the swelling in liquid CO2 was 7% during 78hours.
A fundamental investigation on the extraction from biomass, low rank coal and their mixture during hydrothermal treatment was conducted by using a circulative equipment having a 10 cm3 cell. Beluga coal from Alaska, and Cryptomeria Japonica and empty fruit bunch of oil palm (EFB) were used as material samples of low rank coal and biomass, respectively. Biomass started to be decomposed at a temperature lower than that of low rank coal, which suggests that amorphous cellulose and hemicellulose were hydrolyzed. Frans such as furfural and 5-hydroxymethyl-2-furaldehyde (HMF) extracted from biomass were unstable as compared to phenol, and therefore decomposed and partially cyclized. It was considered that low rank coal adsorbed extracts from biomass due to the porous morphology. The possibility to predict the TOC from an on-line monitoring of the absorbance intensity in UV region during hydrothermal treatment was also shown.
In this study, a control system incorporating the know-how of the skilled operators using fuzzy logic is applied by using on-line ash monitors conventionally employed for product coal quality control as a jig control system sensor to a coal preparation plant of the Ombilin Mine in Indonesia. The computer simulation experiments demonstrate that the response can be improved by means of modification of the fuzzy rules. Based on the results of the simulation experiments, it is clear that the present proportional/integral-operation fuzzy control system is effective in mitigating the large dead times of 60 seconds due to the sampling interval of the ash monitor, and also in mitigating the parameter variations due to the properties of raw coal. The experimental results show that the coal washery jig control system developed with the use of the PI fuzzy control system is capable of controlling the clean coal ash content to within a ± 3% range of the target ash content of the clean coal.
The much renewable energy are developing to prevent rapidly increase of CO2 gas in the atmospheres. JGC developed a renewable fuel from woody biomass by hot water drying method. Woody biomass is introduced to the hot water(300°C,12MPa, 30min) and upgraded by de-oxygenation and dehydration. Upgraded test was examined by auto-clave, bench scale plant and pilot plant. The pilot plant capacity is 50 kg-dry/h. Upgraded biomass is like as coal. We can get clean solid fuel (briquette) and slurry fuel by the upgraded biomass. Combustion test was conducted by this renewable fuel. This fuel’s combust ability was much better than the bituminous coal. JGC want to use this renewable fuel and to contribute preventing CO2 gas.
Methane hydrate is anticipated to be a promising energy resource of natural gas, since a large amount of reservoir exists in marine sediments or in permafrost regions worldwide. In order to evaluate a productivity of methane gas from methane hydrate reservoirs, it is necessary to develop a gas production numeric simulator. And, for precise assessment of long-term gas productivity, it is important to consider time-dependent properties of sediments containing methane hydrate. In this study, loading rate dependency, one of important time-dependent properties, of artificial sediment containing methane hydrate was experimentally examined. Results of triaxial compression tests of water-saturated Toyoura sand (saturated-sand specimen) and Toyoura sand containing synthetic methane hydrate (hydrate-sand specimen), at conditions of confining pressure 9MPa, pore water pressure 8MPa and temperature 278K, were presented. Loading was conducted at a constant strain rate or alternating strain rate. In constant strain rate test, specimen was loaded at strain rate of 0.1%/min, 0.05%/min and 0.01%/min. In alternating strain rate test, one specimen was loaded at a strain rate alternated between the lower rate C1 and the higher rate C2 at strain intervals Δε. The conditions of C1, C2 and Δε were briefly examined in this study. Experimental results indicate that saturated-sand specimen shows very weak strain rate dependency suggesting that, in most cases, time-dependency is negligible small. Strain rate dependency of the peak strength for hydrate-sand specimen was considerably stronger than that of saturated-sand specimen. Referring to earlier works, the time-dependency of hydrate-sand specimen seemed to be weaker than that of ice or methane hydrate and comparable with that of frozen sand.
Activated carbons were manufactured from waste phenol resin in order to reuse for functional adsorbent. Waste phenol resin was carbonized with N2 and activated with CO2 or H2O. The specific surface area of carbonized materials was more than 1000m2/g, when they were carbonized at the lower temperature of 600°C for 10 minutes in N2 and activated at 900°C for 30 minutes with H2O. This value was nearly three times larger than that of carbonized materials activated with CO2 in the same conditions. Moreover, waste phenol resin which was carbonized at 600°C for 10 minutes and activated at 900°C for 30 minutes with H2O showed superior adsorption effect for NH3 gas. Ca(OH)2 was added to waste phenol resin as activator. The activated reaction and adsorption effect of PO43-, Cl-, NO3- and SO42- for the activated samples in solution were evaluated. Waste phenol resin with added Ca(OH)2 was carbonized at 800°C for 60 minutes in N2 and activated at 1000°C with CO2 or H2O. The specific surface area of carbonized materials mixed with Ca(OH)2 after activated at 1000°C for 10 minutes with H2O was about 400m2/g. This value was 50m2/g lower than that of carbonized materials mixed with Ca(OH)2 after activated in CO2 at the same condition. Therefore, the adsorption tests for PO43-, Cl-, NO3- and SO42- contained in solution were conducted with the materials which were activated with CO2. The results showed that the carbonized materials mixed with Ca(OH)2 after activated in CO2 could adsorb quickly and selectively PO43- in solution.