Abstract:

To address the significant increase in monoethylene glycol (MEG) loss and abnormal operation of the regeneration system during high-load gas production from an underground gas storage facility, this study investigates the main loss mechanisms and develops an integrated process optimization strategy based on field data, compositional analysis, and Aspen HYSYS simulations. A steady-state model of the surface gas-production process was established and validated using representative operating data, and HYSYS Dynamics was further used to evaluate transient MEG entrainment during load variations. The model reproduced the pressure and temperature responses of the actual process with acceptable accuracy, providing a basis for subsequent mechanism analysis and optimization. The results show that increasing the gas production rate from 400×10⁴ m³/d to 560×10⁴ m³/d deteriorates the separation performance of the low-temperature separator because of higher gas velocity and shorter liquid residence time. Under steady-state conditions, the gas-phase MEG entrainment rate increases from 12.48 kg/h to 17.47 kg/h, while during the transient ramp-up process it reaches a peak of 26.80 kg/h, 53.4% higher than the final high-load steady-state value. Meanwhile, enhanced interfacial disturbance and reduced residence time promote oil-glycol emulsification and liquid-phase entrainment, causing part of the glycol-rich liquid and condensate to enter the regeneration system. Compositional analysis indicates that the condensate contains relatively high fractions of heavy hydrocarbons and aromatics, which can aggravate fouling, carbon deposition, foaming, and vapor-liquid entrainment in the regeneration section. Based on these findings, a coordinated optimization strategy is proposed by controlling the air-cooler outlet temperature, adjusting the export pressure-regulating valve, and utilizing the available pipeline pressure potential to enhance Joule-Thomson cooling. When the low-temperature separator temperature is reduced from -5 °C to -10 °C, the recovered MEG flow rate increases from 34.66 kg/h to 35.17 kg/h. The predicted hydrate formation temperature under the current MEG injection condition is approximately -13.32 °C, leaving a safety margin of about 3.3 °C at -10 °C. Further optimization of the regeneration system, including hydrocarbon removal and operating-parameter adjustment, can reduce the adverse effects of heavy components and impurities. Economic evaluation shows that, although the reboiler duty increases from 215 kW to 248 kW, the optimized scheme can still provide a net benefit of approximately 446-626 CNY/d. The results demonstrate that abnormal MEG loss under high production rates is caused by the combined effects of deteriorated front-end separation, transient load disturbances, and regeneration-system contamination. The proposed coordinated optimization strategy can effectively reduce MEG loss while satisfying hydrate-prevention and downstream pressure constraints, thereby providing technical support for the safe, stable, and economical operation of underground gas storage facilities under high-load production conditions.

Key words: underground gas storage, surface process, glycol loss, process optimization, HYSYS

摘要：

针对某地下储气库高负荷采气过程中乙二醇损耗显著增加及再生系统运行异常的问题，结合现场运行数据、组分化验结果与Aspen HYSYS稳态和动态仿真，分析高采出量工况下乙二醇损耗机理，并提出相应的工艺优化策略。建立并验证储气库地面采气工艺模型后，对日采气量由400×10⁴ m³/d增至560×10⁴ m³/d的运行过程进行模拟。结果表明，高负荷工况下气相流速增大、液相停留时间缩短，使低温分离器分离性能下降。稳态条件下，气相乙二醇携带量由12.48 kg/h增至17.47 kg/h；升量瞬态过程中携带量峰值达到26.80 kg/h，较最终高负荷稳态值增加53.4%。同时，液相停留时间缩短和界面扰动增强加剧油—醇乳化及液相夹带，使部分凝析油和乙二醇富液进入再生系统；其中重烃、芳烃及固体杂质会进一步引发积碳、发泡和气液夹带。针对上述问题，提出空冷器温度、外输压力与J-T阀节流过程协同调控的低温分离优化策略，充分利用管网余压强化焦耳—汤姆逊效应。模拟结果表明，将低温分离器温度由-5 ℃降至-10 ℃后，乙二醇回收量由34.66 kg/h增至35.17 kg/h；当前注醇条件下水合物生成温度约为-13.32 ℃，-10 ℃工况仍具有约3.3 ℃的安全裕量。结合再生系统除烃及运行参数优化，可进一步减弱重组分和杂质的不利影响。经济性分析表明，尽管重沸器热负荷由215 kW增至248 kW，优化方案仍可获得约446~626 元/d的净收益。研究表明，高采出量条件下乙二醇异常损耗是前端分离性能恶化、瞬态负荷扰动和再生系统污染共同作用的结果，采用压力—温度协同调控可在满足水合物防控及下游供气压力约束的前提下有效降低乙二醇损耗。

关键词: 地下储气库, 地面工艺, 乙二醇损耗, 工艺优化, HYSYS