Development of Pilot Plant for the Production of Vapor Grown Carbon Fiber from Ohio Coal. Final Report, July 1997 to July 2000.

摘要

The objective of this project was to develop, build, and operate a pilot-scale plant for the production of Pyrograf-III? carbon nanofiber from Ohio high-sulfur coal. The fiber production scale-up program was conducted in three phases. In Phase I, the design parameters were developed using a single reactor system, for a process where sulfur bearing coal replaced hydrogen sulfide as the sulfur source. Optimization trials for different reactor tube dimensions were conducted and compared to theoretical predictions for temperature and flow conditions in the reactor as a function of the reactor dimensions. The process was also refined to optimize intrinsic and surface properties of the carbon fiber. Methods of separating fiber from coal ash and de-bulking the fiber were also developed and demonstrated. Under Phase I, a considerable body of knowledge was developed that yielded valuable data bearing on the design of fiber production and handling equipment. The Phase I effort was comprised of complementary programs sponsored by the Ohio Coal Development Office (OCDO), the U.S. Department of Energy (DOE), the Delphi Chassis Division of General Motors Corporation, and the U.S. Department of Commerce (DOC). In Phase II, equipment was designed based upon the body of knowledge developed under Phase I. The pilot plant equipment was designed to have a production capacity up to 100,000 pounds of fiber per year based on a process (PR-11) that generates a fiber diameter of 200 nm and a model indicating energy throughput as the rate-limiting variable. As the program progressed, it become evident that the near-term customers required a fiber with a much smaller diameter, PR-24 grade, to achieve the required performance in the end product. In order to meet the needs of the initial customer base, modifications were made to the pilot plant reactors to produce the smaller diameter fiber. This change in the intrinsic properties of the fiber caused the production capacity to be cut to a minimum of approximately 25,000 pounds of fiber per year, with production of up to 50,000 pound per year feasible. All of the essential components of the pilot plant were received and installed by January 2000. In Phase III of the program, the performance checks were completed in January and fiber production was initiated in the same month. The fiber was evaluated by customers and deemed to be a suitable replacement for fiber made at the laboratory scale. Optimization trials were performed to increase production and reduce surface residuals without changing the intrinsic properties of the fiber. Once the process was "frozen", statistical quality control techniques were applied to the process and the fiber. Analysis of the emissions from the pilot plant shows that the process continues to be free of sulfur dioxide and, otherwise, environmentally friendly. Economic analysis of the pilot plant shows that profitability can be achieved at a price level of $85 per pound.