Quench time modeling in propane ultrapyrolysis

Abstract

AbstractPyrolysis products from industrial cracking furnaces are commonly quenched indirectly in transfer line heat exchangers (TLX). To assess the performance of a TLX for a high severity furnace, a rigorous computer simulation of a TLX tube has been developed. The primary objective was to determine whether this method of indirect quenching can provide the extremely small quench times required for fast ultrapyrolysis reactions. Results indicate that extremely small quench times of approximately 10–15 ms can be achieved, typically dropping the temperature from 1100 to 900K. The model takes into account the effect of the thermal entrance region on heat transfer characteristics and can employ either a 10 equation molecular reaction scheme or an 80 equation radical reaction scheme for propane pyrolysis. The effects of adjusting the main process variables and of coke deposition on quenching performance are also discussed.