Study on the causes of the blockage and countermeasures of distillation column in natural gas treatment plant

Objective To solve a series of problems caused by blocked distillation column, such as poor recovery effect of methanol products, frequent equipment shutdown and maintenance, and reduced water treatment efficiency.

Methods The test points of different heights were selected in the distillation column for corrosion monitoring, and the reasons for the blockage of the distillation column were compared and analyzed in combination with the analysis of the water quality of alcohol-containing sewage and the blockage in the laboratory and X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS), etc.

Results Compared with 2017, the salinity of alcohol-containing sewage increased significantly in 2019, and the scaling cation and chloride content also increased greatly. The predicted result of scaling was more likely to produce CaCO₃ scale.

Conclusions The main reason of distillation column blockage is scaling, and pitting corrosion is serious. In 2017, the main components of the blockage material were Fe₂O₃, CaCO₃ and CaMg(CO₃)₂, and they were Fe₃O₄ and CaCO₃ in 2019. In 2019, the main cause of distillation column blockage was CaCO₃ scale and Fe₃O₄ blocking column plate at high temperatures. By increasing pH value of alcohol-containing sewage, optimizing the type and dosage of reagents, the blockage of distillation column have been solved, and the field operation effect is good.