(8e) Causes and Mitigation Plan for Glycol Losses for A Natural Gas Dehydration Plant

Low-temperature separation with mono ethylene glycol (MEG) injection process is a common dehydration technique for the natural gas processing. However, the MEG-based dehydration system frequently suffers the significant glycol loss during plant upset conditions, causing double penalties of economic loss and air emissions. Thus, it is very important to minimize the MEG loss in the dehydration process. In this paper, an efficient and effective methodology to reduce the MEG loss under upset conditions of a natural gas dehydration plant has been developed and virtually demonstrated. It starts with the development of plant-wide steady-state simulation model and validation at the normal operating condition. Next, the root cause analysis for MEG loss are performed by introducing various process upsets to the simulation model, which indicates that most MEG loss is due to the unstable temperature of the stripper column overhead. After that, the plant-wide dynamic simulation model is developed to help develop a new control strategy to regulate the stripper column operation and cope with other plant upset conditions, so as to minimize the MEG loss and improve natural gas product quality and plant operating stability. Through simulation demonstration, the newly implemented control strategy could reduce the plant MEG losses by 37%.