Failure Analysis Of Oxychlorination Reactor And Its Prevention

Oxychlorination reactor (OC) is the core equipment of VCM device which belongs to PVC plant of Shanghai Chlor-alkali Chemical co., Ltd. It was made of304L, a kind of austenitic stainless steel. The corrosion cracks on the upper head and coilers often caused the leakage and device shutdown. According to the practical situation, an investigation has been carried out for finding the failure reasons of OC, eliminating the correlative conditions of failure, preventing and controlling them to avoid the failure and prolong the life of the equipment.Some tests were performed on the samples of upper head materials including nondestructive examination, mechanical test, chemical composition analysis, micro structure observation, SEM and EDS analyses, etc. It shows the feature of stress corrosion cracking (SCC) due to the macrocosmic and microcosmic pattern of the cracks on the upper head of OC. The corrosion source is determined as medium Cl-with atmosphere testing and checking of process, catalyzer and heat insulator. The stress concentration area is also determined by a finite element analysis (FEA). The mechanisms of the failure are revealed by analyzing process of manufacturing, historical running, environmental factors and maintenance conditions, based on the corrosion theory and the results of the investigation. Finally, a reasonable prevention and maintenance measures are suggested for a guidance of operation safety and running reliability.