Study on solid deposit appeared in hot high pressure separator in coal liquefaction 150t/d pilot plant

The development of coal liquefaction technology using a Pilot Plant(150t/d) of NEDOL process has been carried out in Kashima city, Japan. Since December 1996 to September 1998, the sum of coal-in-operation including 3 kinds of coal was 269 days containing the stable continuous operation of 1920 hours. Through those operations, the high oil yield and long-term consecutive operability have been verified and various engineering data for designing a DP have been obtained. In those operations, a variety of solid deposits have appeared in local position of the plant especially in the Hot High Pressure Separator and Reactor. In this paper, in order to enhance operability and reliability of coal liquefaction plant, those solid deposits have been studied by using many analytical methods. From these analyses, characteristics of solid deposit, the mechanism of their formation and the original material of the solid deposit have been determined. These results should be used to design a rational DP or CP in the future.