| Popis: |
Publisher Summary This chapter discusses the laser pyrolysis of entrained stream of coal particles. The simplicity of pyrolysis as a basis for deriving liquid and gaseous fuels from coal is offset by the problem of poor yields and product quality. Efforts to improve yields have been limited by a traditional mechanistic picture of pyrolysis that is, at best, incomplete. To contribute to an improved understanding of the chemical and physical processes that control the formation of volatiles during pyrolysis, an apparatus has been developed for pyrolyzing an entrained flow of coal particles with a CW infrared laser. The advantages of this pyrolysis mode are that it provides a very rapid, in-depth heating to a steady-state temperature determined by the balance between radiative input to the particle and the sum of convective and radiative heat losses and secondary reactions are minimized by the cold-gas atmosphere, which rapidly quenches the initially evolved volatiles. The observation indicating substantial nonvapor tar transport comes from the appearance of the tar collected during pyrolysis of coals into which small amounts of hydrogenated coal tar have been loaded. |
