CAUSES ANALYSIS OF ETHYLENE GLYCOL LOSS IN NATURAL GAS DEHYDRATION PROCESS AND COUNTERMEASURES

Abstract

Abstract: Ethylene glycol is a common hydrate inhibitor in oil and gas field stations, playing a crucial role in the purification of natural gas. However, the consumption of ethylene glycol can result in significant economic losses. Therefore, finding the methods to reduce ethylene glycol consumption is of paramount importance. Employing a hypothesis-verification-conclusion analytical approach, the causes of ethylene glycol loss are analyzed, considering gas-phase losses, liquid-phase losses, and regeneration losses in conjunction with the process flow. A set of formulas for calculating the liquid levels in alcohol-hydrocarbon liquid three-phase separators and rich liquid buffer tanks is proposed, enabling the quantification of the optimal liquid levels for effectively reducing liquid-phase separation losses. Using HYSYS software, models for the dehydration and dehydrocarbonization blocks and the ethylene glycol regeneration block are established to simulate the impact of the pre-cooler inlet gas temperature on the reflux liquid amount of condensed water. The results indicate that maintaining the alcohol chamber liquid level control at around 51% for the alcohol-hydrocarbon liquid three-phase separator and setting the alcohol chamber liquid level at approximately 55% for the rich liquid buffer tank can effectively reduce liquid-phase separation losses. Within the allowable range of process parameters, lowering the inlet gas temperature before the alcohol injection point is beneficial for the separation of condensed water, thereby achieving the goal of reducing ethylene glycol consumption. Without modifying the process pipelines and pressure vessels, controlling the liquid levels of the ethylene glycol regeneration unit separator and the pre-cooler inlet gas temperature before the alcohol injection point can significantly reduce ethylene glycol consumption. In 2023, ethylene glycol consumption decreased to 6.9 mg/m³, resulting in a reduction of 31.51 t of ethylene glycol consumption and effectively reducing production costs at the processing station.

Key words: ethylene glycol loss, dehydration process, HYSYS, natural gas dehydration

References

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