Flash Pyrolysis of Coal in Methane

Flash Pyrolysis of Coal in an Atmosphere of Methane Cody Anderson, Chris Demars, Alex Hardy, Brett Peterson, and Justin Kostelecky with John Myers Chemical Engineering University of Wyoming Oral Presentation Honors Cheyenne, Wyoming With growing regulations on coal, a new challenge arises to find an alternative use for it. For this process, coal is flash pyrolyzed in an atmosphere of methane at 1832°F and 500 psi. In order to maximize useful products from this process, the residence time within the reactor must be less than one second and the product stream must be immediately quenched with a water stream to cool the products to 400°F. Higher residence times allow undesirable reactions to take place. The most valuable products from this process are benzene, toluene, xylene, and ethylene. Several steps must be taken to purify these products. However, in this process, ethylene is not purified from the other components. The first stage of separation is a filter used to remove the char that remains in the stream after the reactor. This char is combusted to heat the reactor. The resulting stream is then cooled before being fed to a flash drum to remove as much water as possible. The gaseous stream from the flash drum is then fed to a cryogenic turboexpander to condense the benzene, toluene, and xylene while leaving the other components from the reactor in the gaseous phase. The benzene, toluene, and xylene are then purified further in a centrifugal decanter.