Application of microbubbles for cleaning coal powder
Keywords:bubble size, clean coal technology, coal, coal analysis, flotation column, microbubble generator
It is known that Thailand has been using natural gas as its main fuel in producing electricity at the present time. A number of these reserved natural gases are likely to be dramatically decreased in the future. However, Thailand also has abundance of another fuel resource, which are the lignite coals that are considered lower quality but cheaper compared to other fuel resources. Even though lignite is not fully accepted and has bad reputation for its harmful impact on environment is being developed and used with clean coal technology in order to lower the pollution from the coal. This aims to study characteristics of bubbles produced by three different bubble generators: porous stones, ejector nozzle and pressure tank. Moreover, this study also investigates the result of coal cleaning by using the generated bubbles in order to carry the coal to the water surface. The result shows that the size of bubbles produced by porous material are appeared larger compares to the bubbles produced by the ejector nozzle combined with pressure tank are smallest. For the coal cleaning, it is found that the bubbles from the ejector nozzle combined with pressure tank can carry more coal powder to the water surface. In addition, flotation time also affects to remove sulfur and ash of the coal. The removal of sulfur content and ash content in coals, decreased with increasing flotation time. In addition, the fixed carbon and gross calorific value of the coals were increased with increasing flotation time.
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