T3he

Steam

HRSG

Storage

Compression

Figure 11: System flow of IGCC with CO2 removal.

6 Upgrading of low rank coal and biomass

In chapter 2 and 3, the utilization technology of the low rank coal and biomass is introduced. For the utilization of the low rank coal and biomass, the big problem is the included moisture. Although many kinds of upgrading technology of low rank coal and biomass are developed, the drying technology is one of most important methods. But the moisture in low rank coal and biomass is not only bulk moisture but also moisture in the pore, so it is difficult to remove the moisture efficiently. For the high performance of moisture removal, the methods using evaporation are effective. On the other hand, these methods require the higher power consumption for the increase of coal temperature.

Liquid DME

High moisture Solid

Extraction

Dry Solid

^sJ DME gas

Water

Dry Solid

Figure 12: Concept of the extraction method using DME.

In CRIEPI, the extraction method using DME (di-methyl-ether) is investigated. Figure 12 shows the concept of this method [5]. DME is gas phase in ambient pressure and temperature, but it becomes liquid phase by

ÉWIT Transactions on Ecology and the Environment, Vol 154, © 2011 WIT Press www.witpress.com, ISSN 1743-3541 (on-line)

pressurization in ambient temperature. And the liquefied DME can include moisture. So, in this system, the liquefied DME is mixed with the low rank coal or biomass, and DME extracts moisture. After the separation of liquefied DME including moisture with dried coal or biomass, DME converted to gas phase by decompression. And gaseous DME is separated with liquid water. The gaseous DME can be converted to liquid phase by pressurization, and DME is used again by recycling. This method can reduce the power consumption required for the drying of low rank coal and biomass.

7 Conclusion

Coal is an important energy resource for meeting the further demand for electricity, as coal reserves are much more abundant than those of other fossil fuels. For the coal utilization in the future, it is necessary to reduce CO2 emission. To reduce the CO2 emission, it is very important to develop new technology of high efficiency power generation system and utilize low carbonized coal and biomass energy of carbon neutral. For the further reduction of CO2 emission, the CO2 removal technology is effective one, but it requires high power consumption and cost.

It is necessary to apply the smart technology for new function material design and powder handing technology for the development of new type coal utilized power generation system including high efficiency power generation system and carbon dioxide removal power generation system. For the utilization of low rank coal and biomass energy, it is very important to develop the smart technology for the handling of low rank coal and biomass like drying, pulverizing and combustion. We'll continue to develop these technologies.

References

[1] Ikeda M., H. Makino, Y. Kozai, Emission Characteristics of NOx and Unburned Carbon in Fly Ash of Sub-bituminous Coal Combustion. JSME International Journal, Series B, 15, 3, pp506-511, 2002

[2] Ikeda M., H. Makino, H. Morinaga, K. Higashiyama, Y. Kozai, Emission Characteristics of NOx and Unburned Carbon in Fly Ash during Combustion of Blends of Bituminous/Sub-bituminous Coal Combustion. Fuel, 82, 13, pp1851-1857, 2003

[3] Tsuji H., H. Makino, H. Shirai, N. Ikemoto, K. Murai, S. Momoda, Blended Combustion of Dried Sludge Pellet with Pulverized Coal. Journal of the Japan Institute of Energy, 85, 9, pp769-772, 2006

[4] Oki Y., J. Inumaru, S. Hara, M. Kobayashi, H. Watanabe, S. Umemoto, H. Makino, Development of oxy-fuel IGCC system with CO2 recirculation for CO2 capture. Proc. of the l(fh Int. Conf. On Greenhouse Gas Control Technology, 2010

[5] Kanda H., H. Makino, M. Miyahara, Energy-Saving Drying Technology for Porous Media using Liquefied DME Gas. Adsorption, 14, 2, 2008

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