Detailed Kinetic Modeling of Gas Evolution and Energy Recovery during Chemical Quenching of Acetylene Production in Thermal Plasma

摘要

Thermal plasma pyrolysis provides a convenient way to realize the one-step conversion from coal to acetylene. Taking advantage of the ultra-high temperature field provided by thermal plasma, the coal feedstock is heated up in milliseconds to give out volatiles. The volatiles undergo gas phase reactions afterwards to form acetylene owing to the fact that acetylene is thermodynamically stable at above 1500 K among small-molecule-hydrocarbons. However, acetylene will decompose into hydrogen and carbon black during cooling process. So efficient quenching is necessary to prevent acetylene decomposition so as to maintain the target products. It is noticed, on the other hand, that the hightemperature gas products still contain about 40% of the total energy input. So it is vital to make use of the latent energy during the quenching process. In addition to the common physical quenching by water spray, chemical quenching method is an alternative solution to the process design. In chemical quenching, hydrocarbons are used as quenching media instead of water, which brings about co-products (e.g., ethylene) during the decomposition of hydrocarbons by the afterheat in gas products. The process profit can be accordingly improved as well.