Simulation study of citric acid effects on pyrolysis of hydrochloric acid pickling waste liquor

Abstract

During pyrolysis of hydrochloric acid pickling waste liquid in a Venturi Reactor from iron and steel enterprises, the reaction products agglomera ted and hindered product recovery. Addition of citric acid to materials at the inlet improved product distribution. In this paper, a numerical simulation of the combustion, phase change, and gas-solid chemistry involved in a citric acid-added pickling waste liquid was conducted. These results showed that citric acid added to the inlet resulted in a peak concentration of carbon dioxide (CO2) in the back half of the venturi throat, and some ferric oxide (Fe2O3) underwent a secondary reaction to afford ferroferric oxide (Fe3O4). As the addition of citric acid increased, the flow of Fe2O3 at the outlet first increased and then decreased, while the flow rate of Fe3O4 first decreased and then increased. When the ratio of citric acid was 7%, the flow rate of Fe2O3 was the smallest and the flow rate of Fe3O4 was the largest.