1. Overview of NEDOL Process development
The conceptual design of a 250 t/day pilot plant began in FY1984. Owing to changes in economic conditions, however, the design of a 150 t/d PP began in FY1988. As a support study to the pilot plant, the operational study of a 1 t/d process support unit (PSU) was carried out. The 1 t/d PSU, constructed in FY1988 at Kimitsu Ironworks of Nippon Steel Corp., consisted of four stages: coal storage and pretreatment, liquefaction reaction, liquefied coal distillation, and solvent hydrogenation. Over the ten-year period from FY1989 to FY1998, a joint study team from Nippon Steel Corp., Mitsui Coal Liquefaction Co., Ltd., and Nippon Coal Oil Co., Ltd. conducted operational studies on nine coal grades under 72 conditions. Through the 26,949 hours of cumulative coal slurry operations, the stability and the overall operability of the NEDOL Process were confirmed, and optimization of the process was established. Finally, the necessary design data was acquired. Construction of the 150 t/d pilot plant was launched in 1991 at Sumitomo Metal Industries, Ltd.’s Kashima Steelworks (Kashima City, Ibaraki), requiring nearly five years for completion. The pilot plant consisted of five main facilities: the coal treatment unit, the consisted liquefaction reaction unit, the liquefied coal distillation unit, the solvent hydrogenation unit, and the hydrogen production unit.
2. Evaluation of NEDOL Process
Figure 1 shows the progress of coal liquefaction technology since before World War II, expressed by the relation between the severity of the liquefaction reaction and the yield of coal-liquefied oil by generation. As seen in Figure 1, the NEDOL Process is competitive with the processes in Europe and the United States in terms of technology, economics, and operational stability, and thus the NEDOL Process is one of the most advanced processes in the field, reaching a position to shift to commercialization in the shortest amount of time.
3. Features of NEDOL Process
The NEDOL Process is a coal liquefaction process developed exclusively in Japan. The process has integrated the advantages of three bituminous liquefaction processes (Direct Hydrogenation Process, Solvent Extraction Process, and Solvolysis Process), thus providing superiority in both technology and economics. The advantages of the NEDOL Process include:
- attaining high liquid yield under mild liquefaction reaction conditions owing to the iron-based fine powder catalyst and to the hydrogen-donating solvent;
- producing coal-liquefied oil rich in light distillate;
- assuring high process stability because of the highly reliable core process stages; and
- applicability to a wide range of coal ranks, ranging from sub- bituminous coal to low coalification grade bituminous coal.
4. Typical reaction conditions of NEDOL Process
5. Pilot plant: Objectives and achievements
6. Research and development timetable of NEDOL Process pilot plants
7. Research and development results
All the acquired data, including the pilot plant data, the basic research data, and the support study data, were summarized in a technology package in preparation for practical application. At the Development and Assessment Committee Meeting for Bituminous Coal Liquefaction Technology in the Assessment Work Group of the Industrial Technology Council, held on December 22, 1999, the NEDOL Process was highly evaluated: "The NEDOL Process is at the highest technology level in the world, and has reached the stage where worldwide diffusion is expected." Thus, the development of coal liquefaction technology in Japan has already exited the research and development stage and entered the practical application stage.
Furthermore, the developed materials and new processes are expected to significantly influence development in other industries.
References
1) Sadao Wasaka: "Bulletin of The Japan Institute of Energy," 78 (798), 1999.
2) "Development of Coal Liquefaction Technology - A Bridge for Commercialization," Nippon Coal Oil Co., Ltd.
3) Haruhiko Yoshida: "Coal Liquefaction Pilot Plant," New Energy and Industrial Technology Development Organization.
Source: New Energy and Industrial Technology Development Organization (NEDO), Japan Coal Energy Center (JCOAL)
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