Study on the failure analysis of four metals for anaerobic fermentation reactor based on numerical simulation and electrochemical method

Abstract

The core problem of low energy consumption anaerobic fermentation reactor is that the reactor can make reasonable and effective use of energy from two aspects of quantity and quality, so as to ensure the anaerobic fermentation performance of the reactor and make it run efficiently and energy-saving. However, serious corrosion of metal for reactors was found during operation, and the selection of reactor materials became the key to restrict biogas production. In this paper, the corrosion characteristics of the four metals including Q235A steel, Q345A steel, 45# steel and 3Cr13 steel were determined by corrosion morphology, mechanical and electrochemical experiments. The results showed that the corrosion product particles of Q235A steel were polygonal, showing a good cross-linking feature, which was better than that of Q345A and 45# steels. However, there was no obvious boundary between corrosion product particles of 3Cr13 steel. The presence of Fe3C in the corrosion products of 3Cr13 steel and the observation of micro-cracks on the surface at nanometer scale indicated that the intergranular corrosion of 3Cr13 steel was dominated. For another aspect, with the increase of CO2 and CH4 content, the corrosion rate of the four metals was generally accelerated, in which the Q235A steel showed the best performance under different conditions. In addition, Q345A and 45# steels showed relatively good corrosion resistance, under which the total mole of mixed gas (CO2/H2O/CH4) was lowest.