Biobriquette (Biocoal) is a sort of composite fuel consisting of 70 to 85 percent of coal and 15 to 30 percent of biomass by weight. The coal materials used are over a wide range of coal grades while the biomass used include various woody wastes and agricultural wastes such as bark, saw dust, baggase, rice husk and so on. The mass production technique for Biobriquette without any binder has already been developed through adoption of the high pressure briquetting method with compression only in the roll press technique. Its characteristics as compared with the lumpy size coal can be summarized as follows; 1) It generates very little smoke and the sulfur oxides emission can be significantly reduced by mixing any desulfurizing agent in it. 2) It is excellent in ignitability, combustibility and combustion controllability. 3) It hardly generates clinker during combustion, thus permitting easy ash disposal 4) It is uniform in shape and size, and generates less dust during handling. International cooperation on Biobriquette technology has been requested by many countries, mainly developing ones. Of these countries, the feasibility studies on Biobriquette were carried out so far in Pakistan and Thailand, and also its cooperation for the alternative energy development project is now being gone to Nepal through JICA. As for its technology transfer MITI is now going through “Green Aid Plan”to the developing countries in order to establish the suppression of air pollution and energy-saving in coal combustion, and the Biobriquette production plant will be constructed at Linyi, China lately in 1995.
The concept of “Coalbed Technology” (=CBT) was introduced. The CBT consists of various technologies related to the energy recovery from coalbed and the multi-pourpose use of coalbed. These technologies are consisted of the following development and utilization methods of coalbed. They are; surface coal mining, underground coal mining, gas drainage, coalbed methane, undeground coal gasification, underground coal combustion, underground coal liquefaction, underground coal pulverization, underground gas storage, cavity filling and underground disposal of waste. Combining these methods for increasing the yield and optimizing the economy, the concept of Integrated Coalbed Development System (=ICODES) is proposed. The importance of making a long-term plan for developing and utilizing the coalbed in considering these technologies is discussed.
In order to investigate the steam gasification reactivity of char from flash hydropyrolysis of coal, Loy Yang coal (Australpyroian brown coal) and Manvers coal (British bituminous coal) were pyrolyzed, using a small-scale pilot reactor of entrained flow type, in an atmosphere of hydrogen gas of 70 atm at 860-960°C. The gasi-fication reactivity of hydropyrolysis chars was measured at 800°C-1200°C using a thermo-balance and was compared with that of pyrolysis chars. In addition, to -ly study the relationship between the coal pyrolysis conditions and the gasification reactivity of generated char, the coal was pyrolyzed using a heated grid reactor, while varying the heating rate, the kind of atmospheric gases and pressure. Thus the following findings have been obtained. The steam gasification reactivity of hydropyrolysis char was higher than that of pyrolysis char. The difference in the reactivity of both type of char is affected by the type of raw coal. The gasification reactivity of char from British bituminous coal was strongly affected by the reaction conditions and atmosphere during char production; the reactivity of the char which was generated under the condition of heating rate being 500°C/sec or more was high; the reactivity of the char generated in a high pressure hydrogen atmosphere was higher than that of the char generated in an inert atmosphere. Regarding influence of coal pyrolysis conditions on char reactivity, heating rate has greater effects than atmospheric gases or pressure.
For material recycling of used tires, liquid- phase cracking of tires was studied using various kinds of solvent under H2 or N2 pressure. Experiments were carried out using a 200 ml autoclave with magnetic stirrer at 300-440°, initial H2 or N2 pressure of 2.0-8.5 MPa, reaction time of 20-60 min with solvent to tire weight ratio of 1-2.5. When hydrogen donating solvent such as tetralin was used for cracking, almost all organic matter could be converted to light oil with very low sulfur content of 0.5 wt% by the reaction under low nitrogen pressure. Reaction residue can also be reused as carbon black for rubber manufacturing.
In a direct coal liquefaction process, in addition to the liquefaction condition, the distillation condition of the liquid product is an important factor to develop the process because it strongly affects the properties and yields of the distillate and bottom. Therefore, this paper investigates the effects of the vacuum distillation temperature on the yields and properties of the bottom and distillate, using the liquid products obtained from the primary hydrogenation section of the two-stage Victorian brown coal liquefaction (BCL) process with various feed solvents. When recycled distillate (b. p.180-420°C) was used as a feed solvent, almost all of the n-hexane solubles (HS) in the heavy product were distillable up to a temperature of ca.315°C at 10 mmHg. As a result, the distillate yield increased with the temperature. However, the preasphaltenes also increased gradually with the temperature. On the other hand, when the solvent containing a bottom derived from primary and/or secondary hydrogenation was used as a feed solvent, the HS in the bottom remained at the same temperature (315°C), and the amount of preasphaltenes was constant. These differences were explained by the fact that the HS and asphaltenes derived from the bottom-containing solvent were more hydrogenated and stabilized, and their molecular weight was larger than that derived from the distillate solvent. It is also found that the viscosity of the bottom from the bottom-containing solvent was higher than that from the distillate solvent.
Capture and recovery of nitrogen compounds in methylnaphthalene oil are examined using 10 wt% Al2 (SO4) 3/SiO2 as a solid acid in the fixed bed with a supercritical CO2 extraction apparatus . Model methylnaphthalene oil (quinoline and isoquinoline: 8wt%; 1- and 2-methylnaphthalenes: 42wt%) of 3 .2g was charged into the extraction vesssel under the supercritical CO2 (50°C, 80atm) flow of 6 1/min to pass through the fixed bed of the adsorbent (3 .3g). No nitrogen compounds was eluted until the extraction time of 120 min, while 62% of the fed methylnaphthalene was recovered. Regeneration and repeated use of the solid acid were achieved by purging the adsorbed nitrogen compounds almost completely with higher pressure (150atm) CO2 for 60 min followed by the extraction including methanol as an entrainer solvent for about 30 min, recovering the concentrated quinoline bases . The adsorption capacity of the solid acid gradually decreased with the repeated number of adsorption/desorption cycle probably due to small amounts of nitrogen compounds strongly adsorbed and water on the adso rbent. More polar and/or dry entrainer solvents should be designed for a completely reversible adsorption/desorption procedure.