Prediction of concentration and temperature profiles for non-isothermal ethane cracking in a pipe reactor

Abstract

Thermal crackers are mostly modeled as plug flow systems, disregarding the lateral gradients present. In this paper, a 2-dimensional model has been established for ethane cracking in a thermal cracker in laminar flow, using a molecular mechanistic model for ethane cracking. The model, consisting of 9-coupled partial differential equations, is solved using the backward implicit numerical scheme. The resulting product distribution and temperature profiles are predicted throughout the reactor. The concentrations of acetylene and propylene show a maximum within the reactor. The effect of certain operational parameters — tube radius, wall temperature and mass flow rate — is also studied on these profiles. The parameters are varied in the range of 0.005–0.0125 m for tube radius, 1.25 kg/hr-2.5 kg/hr for mass flow rate and 850–1,050 ‡C for tube wall temperature. It is observed that an increase in wall temperature and an increase in tube radius or decrease in flow rate favours the conversion of ethane.