Corrosive Activity of Coal-Tar Wash Oils and Life of Equipment in Benzene Recovery

Resumo

The corrosive activity of coal-tar wash oils is investigated. An electrochemical method is proposed for assessing the corrosive activity of the oil with respect to carbon steel. The main sources of corrosive impurities in the absorbers are identified. The contamination of the oil is assessed on the basis of its breakdown voltage. The results are in excellent agreement with analytical monitoring of the wash oils. Gravimetric data for the corrosive activity of the fluids in the existing system show that alloyed molybdenum steels are the most durable structural materials in the distillation department. In systems with a closed final-cooling cycle, the corrosive activity of the coal-tar oils may be reduced by scrubbing with water. Quantitative selection criteria are established for the water used.