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Article

Investigation of the Factors and Mechanisms Affecting the Foaming of Triethylene Glycol in Natural Gas Purification

by
Hongyi Liang
,
Qian Huang
,
Xin Li
,
Quan Wu
,
Han Yan
,
Jiang Meng
* and
Xueyuan Long
*
College of Petroleum and Natural Gas Engineering, Chongqing University of Science and Technology, Chongqing 401331, China
*
Authors to whom correspondence should be addressed.
Processes 2025, 13(5), 1261; https://doi.org/10.3390/pr13051261
Submission received: 27 February 2025 / Revised: 11 April 2025 / Accepted: 15 April 2025 / Published: 22 April 2025
(This article belongs to the Section Chemical Processes and Systems)
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Versions Notes

Abstract

:
With increasing natural gas processing demands, triethylene glycol (TEG) in dehydration systems becomes contaminated by gas-carried impurities, leading to problematic foaming, degradation, and significant glycol losses that compromise operational economics, pipeline integrity, and product quality. To systematically investigate impurity effects, we conducted comprehensive single-factor TEG regeneration experiments simulating field conditions. Through precise measurements of foaming height, defoaming time, and interfacial tension, we established clear correlations between impurity types and TEG foaming characteristics. Our results demonstrate a distinct hierarchy of foaming influence: chemical additives > solid impurities > water-soluble inorganic salts > MDEA > hydrogen sulfide > hydrocarbons. Chemical additives showed the most pronounced effect on surface tension, reducing it to 31.1 mN/m at 1500 mg/L. Water-soluble inorganic salts affected foaming through combined decomposition and crystalline morphology effects, ranked as MgCl2 > NaHCO3 > KCl > NaCl > Na2SO4 > CaCl2 (MgCl2 achieving 33.8 mN/m at 2000 mg/L). Solid impurity impacts correlated strongly with particle morphology (CaCO3 > Fe2O3 > CaSO4 > ZnO > CuO > Al2O3 > FeS), stabilizing at 1.5 mg/L. Hydrocarbons showed negligible influence, while hydrogen sulfide and MDEA caused only minor surface tension reductions with limited foaming effects. Based on these findings, we propose targeted mitigation strategies for industrial implementation.

1. Introduction

Natural gas serves as both a transitional fuel in the shift from conventional fossil fuels to renewable energy sources and a fundamental component in future energy systems, with its significance in the global energy mix steadily increasing [1,2]. The purification of natural gas plays a pivotal role in energy production, ensuring operational safety and pro-longing equipment lifespan through the effective removal of corrosive components (e.g., H2S and CO2) and particulate matter, thereby mitigating corrosion-induced equipment degradation and minimizing potential safety hazards [3]. Furthermore, purification enhances fuel quality and utilization efficiency by preventing hydrate formation, optimizing calorific value, and improving combustion characteristics to meet stringent environmental standards. In the process of natural gas dehydration, impurities such as organic matter carried by mineralized formation water and natural gas enter the dehydration system, resulting in triethylene glycol foaming and deterioration, resulting in increased loss [4,5]. The purification plant needs to be replenished or replaced frequently, and the high price of triethylene glycol makes its consumption a key factor affecting the cost [6,7]. In addition, with the expansion of processing capacity, the cycle frequency of triethylene glycol increases, and the solid and liquid impurities in the natural gas residue change their physical and chemical properties in the process of regeneration and water absorption, which makes the natural gas more likely to form a hydrate, threatening the safety of the pipeline, leading to equipment corrosion, reducing the quality of natural gas and increasing the resistance of natural gas transmission [8,9,10]. Determining the key factors affecting the foaming performance of triethylene glycol and exploring the mechanism of different impurities on it are the key to studying the change in the foaming performance of triethylene glycol.
Extensive studies [11,12,13] have established the universal occurrence of foaming phenomena in natural gas purification towers regardless of configuration. Foam formation triggers the destabilization of gas-liquid hydrodynamics, severely compromising process stability and product quality [14]. Moderate foaming cases exhibit characteristic 20–30% pressure differential surges and 15–25% liquid level fluctuations, rendering product gas off-specification. Severe episodes progress to flooding conditions with 40–50% solvent losses, 60–70% capacity reductions, and eventual system shutdowns [15,16]. The root mechanism involves triethylene glycol (TEG) solution degradation through four primary pathways as characterized by Guo et al. [17]: (1) contaminant ingress (aqueous/organic phases, chemicals, particulates) from inadequate feed gas pretreatment; (2) acid-catalyzed degradation via H2S dissolution; (3) thermal decomposition/polycondensation during high-temperature regeneration; and (4) oxidative degradation in storage. Jin et al. [18] quantified critical thresholds: exponential efficiency decline beyond 3% water content, hydrocarbon condensates as dominant foam nucleation sites, and corrosion inhibitors demonstrating concentration-dependent stabilization (critical concentration: 0.2 wt%).
Guo et al. [19] identified specific impurity classes that markedly accelerate TEG degradation, with acetic acid, glycolic acids, divalent cations (Mg2+, Ca2+), and iron sulfide (FeS) exhibiting the most significant deactivation effects. Complementary studies by Jiang [20] and Li et al. [21] revealed that inorganic salts primarily promote foaming through interfacial property modification when introduced via contaminated feed gas. Al-Aiderous [22] demonstrated that hydrocarbon contaminants and suspended solids predominantly enhance foaming via surface tension reduction mechanisms. Operational parameters critically influence foaming behavior, as evidenced by Arubi et al. [23] who thermodynamically verified that TEG regeneration above 204 °C initiates decomposition/oxidation reactions producing organic impurities. Soliman and Arne [24,25] systematically characterized five key foaming triggers: (1) hydrocarbon condensation, (2) lean TEG-process gas temperature differentials, (3) abrupt pressure variations (>10% operating pressure), (4) gas-phase contaminants, and (5) heavy hydrocarbon accumulation in contactors, with TEG thermal decomposition occurring at reboiler temperatures exceeding 204 °C (404 °F).
Building upon previous research on triethylene glycol (TEG) foaming characteristics, this study establishes the absence of inter-factor interference in our experimental design. The key innovation lies in our comprehensive simulation of TEG regeneration under single-impurity conditions, achieved through precise on-site compositional analysis of TEG samples, thereby effectively eliminating cross-impurity effects. Our objectives are threefold: (1) to identify the dominant factors governing TEG foaming behavior, (2) to systematically characterize individual impurity impacts, and (3) to establish a theoretical framework for understanding fundamental foaming mechanisms. These findings provide critical insights for mitigating dehydration system failures caused by TEG foaming, ultimately enabling cost reduction and enhanced economic performance in natural gas purification facilities.

2. Materials and Methods

2.1. Experimental Apparatus and Drugs

The experimental setup illustrated in Figure 1a enables simulation of triethylene glycol regeneration cycles, while the configuration in Figure 1b facilitates evaluation of regenerated triethylene glycol’s foaming characteristics. Essential equipment and chemical reagents required for these experiments are detailed in Table 1 and Table 2, respectively.

2.2. Experimental Methods

2.2.1. Triethylene Glycol Regeneration Experiments

Simulate the rich triethylene glycol regeneration process with a super thermostatic oil bath. Then, start the oil bath and set the temperature at 200 °C. The experimental setup for the simulated dehydration system is illustrated in Figure 1. A measured quantity of distilled water was combined with chemical reagents (inorganic salts, organics, etc.) to prepare solutions with concentration gradients ranging from 250 mg/L to 2000 mg/L. Subsequently, 40 mL (45.096 g) of pure triethylene glycol (TEG) was introduced into a three-necked flask, followed by the addition of 1.394 g of the prepared solution to obtain a 97 wt% TEG-enriched mixture. To prevent oxidation during regeneration, the system was purged with high-purity nitrogen (>99.99%) for over 30 min to displace residual air. A thermometer (0–200 °C, ±0.5 °C) monitored the TEG solution temperature throughout the process. The three-necked flask was then immersed in a 200 °C oil bath for regeneration. After 10 min of heating, the flask was removed to observe experimental phenomena, and the TEG was cooled to 50 °C. This cycle was repeated 50 times. Finally, samples of the regenerated TEG were collected for surface tension and foaming performance analysis.

2.2.2. Measurement of Foaming Performance

The foaming performance of regenerated triethylene glycol (TEG) samples was evaluated following GB/T 7462-1994 (Determination of Foaming Power of Surfactants) using a custom-built aeration apparatus (Figure 1b) [26]. Foam height, indicative of foaming capacity, and defoaming time, reflecting foam stability, were measured [27]. Higher foam height signifies stronger foaming tendency, while prolonged defoaming time suggests greater foam stability.
The experimental procedure was as follows:
A digital thermostatic water bath was set to 50 ± 0.5 °C. A 5 mL TEG sample was introduced into a glass absorber bottle. The bottle was immersed in the water bath for 10 min to equilibrate. Compressed air was introduced for 5 min via an air pump, after which the pump was switched off. Foam height and defoaming time were immediately recorded.

2.2.3. Measurement Experiments

The gas-liquid surface tension of the samples after the regeneration simulation experiment of triethylene glycol was determined at 50 °C using a JJ2000B rotary drop interfacial tensiometer (Shanghai Zhongchen Digital Technology Equipment Co., Shanghai, China).

3. Results

3.1. The Influence of Impurities on the Properties of Triethylene Glycol

Experimental results demonstrate that impurity presence constitutes the primary factor affecting triethylene glycol (TEG) properties. Among various contaminants, water-soluble inorganic salts, solid particulates, corrosion inhibitors, and foaming agents exert particularly significant impacts on TEG, whereas heavy hydrocarbons show relatively minor influence. For natural gas dehydration applications, stringent control of TEG impurities is essential to mitigate foaming incidents and maintain dehydration system stability and operational safety [28,29].
The complex organic reactions of triethylene glycol under prolonged thermal exposure yield numerous products, making comprehensive pathway elucidation challenging. Below are proposed reaction equations for the principal degradation products:
Ethylene oxide and ethylene glycol to form diethylene glycol:
C H 2 O C H 2 + H O C H 2 C H 2 O H → H O C H 2 C H 2 C H 2 O H
Triethylene glycol generates diethylene glycol and acetaldehyde:
H O C 2 H 4 O C 2 H 4 O C 2 H 4 O H → H O C H 2 C H 2 O C H 2 C H 2 O H + C 2 H 4 O
Dehydration of diethylene glycol to generate 1,4-dioxane:
H O C H 2 C H 2 O C H 2 C H 2 O H → C H 2 C H 2 O C H 2 C H 2 O + H 2 O
Dehydration of diethylene glycol to produce tetraethylene glycol:
H O C H 2 C H 2 O C H 2 C H 2 O H → O H C 2 H 4 O C 2 H 4 O C 2 H 4 O C 2 H 4 O H + H 2 O

3.2. Effect of Water-Soluble Heat-Stable Salts on Triethylene Glycol Foaming Bulleted Lists Look Like This

Previous studies [30] on triethylene glycol (TEG) under continuous 48 h heating demonstrate the formation of significant impurities (>60% total) including diethylene glycol, tetraethylene glycol, pentaethylene glycol, hexaethylene glycol, and glycol. Minor quantities of ethers, cyclic compounds, and acidic byproducts were also observed. Water-soluble inorganic salts and their hydrolysis products act as catalysts, promoting TEG molecular decomposition and condensation reactions (both inter- and intramolecular). This catalytic degradation accelerates TEG deterioration, altering its foaming characteristics and surface tension. Specifically, enhanced foaming leads to bubble encapsulation of TEG, ultimately increasing glycol carryover losses.
The cyclic regeneration experiments reveal that the prepared triethylene glycol (TEG) sample contains minimal impurities (0.094 g), with water-soluble inorganic salts reaching a maximum concentration of 2.03 mg/g—significantly lower than field-observed levels of 15.5 mg/g. This indicates that under cyclic regeneration conditions with limited heating duration, inorganic salts exhibit negligible decomposition effects on TEG. Organic impurities primarily originate from thermal decomposition of TEG molecules themselves. While each cycle produces only minor quantities, prolonged accumulation progressively degrades solution properties, notably enhancing foaming tendency and increasing glycol carryover losses. Interestingly, inorganic salts influence foaming performance not merely through decomposition, but more critically via their physical dispersion state. When present as finely divided, uniformly distributed crystals, they promote higher foam stability (increased foam height and prolonged drainage time). This phenomenon stems from crystal aggregation at gas-liquid interfaces, where van der Waals interactions between particles and liquid films impede hydrodynamic drainage. Hydrophobic modification further intensifies this effect by amplifying interfacial polarity contrast, thereby substantially enhancing foam stability [31,32,33].
The foaming height exhibited a non-monotonic response to increasing inorganic salt concentration, initially rising before declining. Monodisperse particles in foam systems provide exceptional interfacial stabilization through three key mechanisms: (1) efficient gas-liquid interface adsorption forming dense particulate monolayers, (2) simultaneous reduction of surface tension and enhancement of elastic modulus, and (3) creation of continuous supporting architectures within foam lamellae that mechanically inhibit film thinning [34,35,36,37].
Comparative analysis revealed stark performance differences, as shown in Figure 2a: KCl demonstrated superior stabilization (0.85 mm foam height at 1100 mg/L) versus CaCl2 (0.37 mm at 1000 mg/L). Although both salts form large crystals, CaCl2’s particularly non-uniform size distribution critically impacts performance. Monodisperse particles maintain interfacial integrity through dynamic repositioning during film expansion, while CaCl2’s agglomerated crystals readily detach from expanding interfaces due to: (i) inadequate adhesion from excessive mass, and (ii) uneven liquid film stresses from polydisperse particle sizes. Higher surface activity substances rapidly migrate to gas-liquid interfaces forming tightly-packed adsorption layers that initially enhance foaming. However, their ultimate foaming performance remains constrained by excessive crystal dimensions, demonstrating that interfacial stabilization requires optimal balance between surface activity and particle morphology.
The defoaming time demonstrates a complex dependence on inorganic salt concentration, as shown in Figure 2b: characterized by an initial increase followed by a slight decrease before stabilization. This behavior is governed by both salt type and concentration. Notably, Na2SO4 exhibited the minimal impact on defoaming time across the 0–2000 mg/L range, consistently showing shorter durations compared to other salts at equivalent concentrations (e.g., 2.8 s at 1250 mg/L). This results from Na2SO4’s small, homogeneous crystals in the triethylene glycol solution, which promote crystalline alcohol formation and significantly increase viscosity. While this viscosity suppresses bubble generation during foaming, it paradoxically accelerates defoaming through enhanced surface viscosity that facilitates rapid film drainage. Conversely, NaHCO3 showed the most pronounced effect on defoaming time, maintaining consistently higher values throughout the 0–2000 mg/L range (reaching 2.8 s at 1500 mg/L). The fine, uniformly dispersed NaHCO3 crystals strongly adsorb to foam bilayers, effectively obstructing liquid flow within the film and impeding drainage. This particle-mediated stabilization mechanism substantially increases foam persistence and defoaming difficulty.
The surface tension exhibited a linear decrease with increasing inorganic salt concentration, as indicated by the data in Figure 2c. Quantitative analysis revealed MgCl2 demonstrated the most pronounced effect, reducing surface tension to 33.8 mN/m at 2000 mg/L, while CaCl2 showed the least impact (35 mN/m at equivalent concentration). This variation stems from differing abilities of the salts to disrupt triethylene glycol’s intermolecular forces. MgCl2 more effectively destabilizes surface molecular interactions, leading to greater tension reduction, whereas CaCl2 exerts a comparatively moderate influence.
The mixed salt system (NaCl:KCl:CaCl2:NaHCO3:MgCl2:Na2SO4 = 10:2:0.8:0.5:0.4:0.3) was designed to simulate field conditions. Analysis revealed that the foaming height and surface tension profiles of the mixed salt most closely resembled those of NaCl, indicating NaCl’s dominant role in these parameters. Interestingly, the defoaming time curve followed MgCl2’s trend, despite MgCl2 constituting only 2.9% of the mixture.Surface tension measurements identified MgCl2 as the most influential factor in foaming performance, exhibiting the steepest decline in interfacial tension among single-salt tests. Secondary parameters (foaming height and defoaming time) further confirmed MgCl2’s significant impact. Based on comprehensive evaluation of surface tension, foaming characteristics, and compositional ratios, the inorganic salts were ranked by foaming influence: MgCl2 > NaHCO3 > KCl > NaCl > Na2SO4 > CaCl2. These findings underscore the necessity for stringent control of inorganic salt content in industrial operations to mitigate their effects on triethylene glycol’s foaming behavior.

3.3. Effect of Solid Impurities on the Foaming of Triethylene Glycol

Similar to salt crystallization effects, the morphology of solid impurities in triethylene glycol (TEG) significantly influences its foaming performance. Smaller, uniformly-sized solid particles enhance both foaming height and defoaming time by effectively adhering to foam bilayer liquid films. This adhesion increases hydrodynamic resistance within the liquid film, thereby improving foam formation and stability [38,39]. Conversely, larger particles exhibit poor adhesion to bubble films due to gravitational effects, reducing foaming capacity. Furthermore, polydisperse particle distributions create non-uniform stress distributions at the liquid film interface, ultimately compromising foam stability.
The addition of solid impurities significantly enhanced both foaming height and defoaming time compared to triethylene glycol (TEG) containing only distilled water, with these parameters reaching plateaus at higher impurity concentrations [40,41]. Among tested solids, as shown in Figure 3a, CaCO3 exhibited the most dramatic foaming enhancement, producing a maximum foam height of 2.6 mm at 1.5 mg/L. This superior performance originates from CaCO3’s monodisperse particle distribution in TEG, which promotes efficient gas adsorption and optimizes bubble nucleation/stabilization. In contrast, CaSO4 forms crystalline alcohol complexes that markedly increase solution viscosity, consequently suppressing bubble formation and restricting foam development.
Defoaming time, as shown in Figure 3b, exhibits a concentration-dependent relationship with solid content, initially increasing until reaching a plateau at 1.5 mg/L. CaCO3 demonstrates the most significant impact, extending defoaming time to 38 s at this concentration, while Al2O3 shows the minimal effect (25 s). This behavior stems [42] from fundamental differences in particle characteristics:CaCO3’s uniform, fine particles (a) tightly adhere to bubble films and (b) effectively impede liquid drainage through the lamellae, substantially enhancing foam stabilityFeS’s polydisperse particles create structural defects in the foam matrix, facilitating rapid liquid drainage and consequently shorter defoaming times.Surface tension, as shown in Figure 3c, exhibited a continuous decline with increasing solid content, reaching minimum values at 15 mg/L. CaCO3 demonstrated the most pronounced effect, reducing surface tension to 33.1 mN/m, while CuO showed the weakest influence (36 mN/m). This variation arises from differential solid-TEG molecular interactions: CaCO3 effectively disrupts the surface molecular arrangement of TEG through strong interfacial interactions, whereas CuO exhibits limited surface activity.
Based on surface tension reduction efficiency, the solids can be ranked as follows: CaCO3 > Fe2O3 > CaSO4 > ZnO > CuO > Al2O3 > FeS. This order reflects their varying capacities to modify TEG’s surface molecular organization, with uniformly-sized particles generally demonstrating greater effects.

3.4. Effect of Corrosion Inhibitor and Foam Inhibitor on the Foaming of Triethylene Glycol

Corrosion inhibitors, defoamers, and foaming agents primarily contain functional groups including amino, acyl, amide, silane, and phenyl moieties. The cationic amino groups adsorb at the negatively charged gas-liquid interface through electrostatic interactions, forming an oriented monolayer that reduces surface tension. Simultaneously, amide groups establish hydrogen bonds with water molecules, creating a three-dimensional network structure within the liquid film that enhances bubble stability. The introduction of these chemical additives markedly improves foaming performance while substantially lowering surface tension. This enhancement originates from surfactant components present in both corrosion inhibitors and foam inhibitors, which effectively decrease solution surface tension and promote foam formation. At the foam bilayer interface, these surfactants orient with their hydrophobic groups extending into the gas phase and hydrophilic groups interacting with the aqueous phase [43]. This molecular arrangement significantly increases liquid film elasticity and mechanical strength, thereby dramatically improving foam stability.
These observations demonstrate that chemical additives profoundly alter triethylene glycol’s foaming characteristics and surface properties, indicating their significant role in TEG degradation processes.
Through systematic analysis of single-factor cyclic regeneration experiments examining chemical reagents’ effects on triethylene glycol’s foaming performance, we observed consistent trends across measured parameters. All tested chemical additives, as shown in Figure 4c, demonstrated concentration-dependent reductions in surface tension until reaching plateaus at 750 mg/L, with the buffer yielding 31.1 mN/m, the blocking agent 30.1 mN/m, and their 1:1 combination 29.6 mN/m. Similarly, as shown in Figure 4a, foaming heights increased with concentration before stabilizing, peaking at 34 mm for corrosion inhibitor (1500 mg/L), 28 mm for foam inhibitor (1250 mg/L), and 37 mm for their 1:1 mixture (1500 mg/L), with subsequent minor fluctuations around these maxima. Defoaming times, as shown in Figure 4b, followed analogous patterns, reaching plateaus of 7.6 s for corrosion inhibitor (1500 mg/L), 7.8 s for foam inhibitor (2000 mg/L), and 7.9 s for their combination (1500 mg/L). These comprehensive results demonstrate that while individual chemical additives significantly influence TEG’s foaming characteristics, their effects become concentration-independent beyond specific thresholds, with synergistic combinations generally exhibiting enhanced performance over single-component systems.
Experimental investigations simulating field conditions (1:1 corrosion inhibitor:antifoam agent ratio) revealed consistent trends in triethylene glycol’s (TEG) foaming behavior. Both defoaming time and foam height increased with additive concentration until reaching plateaus at 1500 mg/L, beyond which further concentration increases showed minimal effects. The corrosion inhibitor demonstrated greater influence than the foam inhibitor individually, with its effects remaining dominant in mixed systems [44]. Surface tension measurements showed an initial decrease followed by stabilization above 750 mg/L concentration. Comparative analysis revealed the antifoam agent reduced TEG’s surface tension more significantly than the corrosion inhibitor alone. The 1:1 mixture exhibited synergistic effects, producing the most pronounced surface tension reduction, with the antifoam agent’s contribution being particularly prominent in the combined system [45]. These findings demonstrate the complex interplay between chemical additives in governing TEG’s surface properties under simulated operational conditions.

3.5. Impact of Hydrocarbons on Foaming in Triethylene Glycol Dehydration Plants

Hydrocarbons exhibit minimal influence on triethylene glycol’s foaming characteristics. While increased surface tension typically correlates with reduced foaming performance, excessive hydrocarbon content paradoxically enhances both foaming duration and foam height in TEG systems.
Single-factor cyclic regeneration experiments examining hydrocarbon effects on triethylene glycol revealed distinct concentration-dependent trends. Surface tension, as shown in Figure 5c, increased progressively with hydrocarbon content, exhibiting accelerated growth above 2000 mg/L, reaching 38.5 mN/m for light hydrocarbons (3000 mg/L), 38.3 mN/m for heavy hydrocarbons, and 38.6 mN/m for their 4:1 mixture. Foaming height, as shown in Figure 5a, demonstrated rapid initial growth below 500 mg/L, ultimately reaching 0.97 mm (light), 0.8 mm (heavy), and 1.48 mm (mixed) at 3000 mg/L. Defoaming time, as shown in Figure 5b, showed similar concentration dependence, with an accelerated increase beyond 1500 mg/L, culminating in 11 s (light), 13.5 s (heavy), and 14.8 s (mixed) at maximum concentration. These results demonstrate that while all hydrocarbon types influence TEG’s foaming characteristics, their mixed systems exhibit synergistic effects, particularly evident in foaming height enhancement.
Petroleum ether and gasoline were employed to model light and heavy hydrocarbon effects on triethylene glycol (TEG) solutions, with a 4:1 mixture ratio simulating field conditions. While hydrocarbon concentration increases elevated TEG’s surface tension moderately, the overall impact on foaming performance remained limited. Comparative analysis revealed light hydrocarbons exerted greater influence on surface tension alterations, dominating this effect in mixed systems, whereas heavy hydrocarbons showed more pronounced effects on defoaming time extension. Conversely, light hydrocarbons demonstrated a stronger influence on foaming height enhancement, maintaining this dominant role in mixed hydrocarbon scenarios. These differential effects highlight the distinct roles of hydrocarbon types in modifying TEG’s physicochemical properties.

3.6. Effect of Hydrogen Sulfide and MDEA on Triethylene Glycol Foaming

During hydrogen sulfide adsorption, multiple external factors can compromise MDEA solution stability. Acidic compounds, hydrocarbons, oxygen, and elevated temperatures promote irreversible degradation products and heat-stable salt (HSS) formation in MDEA solutions. Certain HSS possess amphiphilic molecular structures, exhibiting both lipophilic and hydrophilic characteristics that confer superior surface activity and foaming potential. When present in MDEA solutions, these salts dramatically increase foaming propensity [46]. Notably, unidirectional regeneration experiments demonstrated the minimal impact of MDEA solutions on triethylene glycol’s foaming characteristics, with Na2S substituted for hydrogen sulfide to ensure experimental safety.
Single-factor cyclic regeneration experiments examining hydrogen sulfide and MDEA effects on triethylene glycol revealed distinct concentration-dependent behaviors. Both chemicals, as shown in Figure 6c, reduced surface tension until reaching plateaus at 1500 mg/L (H2S: 34.8 mN/m; MDEA: 34.3 mN/m). Foaming height trends, as shown in Figure 6a, differed significantly: H2S showed a gradual increase (0.7 mm at 2000 mg/L) with slowing above 500 mg/L, while MDEA exhibited dramatic acceleration above 1500 mg/L, peaking at 2.4 mm (2000 mg/L). Defoaming times, as shown in Figure 6b, for both compounds increased rapidly below 500 mg/L before moderating, reaching 12 s (H2S) and 14 s (MDEA) at 2000 mg/L. These results demonstrate MDEA’s substantially greater impact on foam formation compared to hydrogen sulfide under identical conditions.
Experimental results demonstrate that triethylene glycol’s (TEG) surface tension decreases modestly with increasing concentrations of both hydrogen sulfide (as sodium sulfide) and MDEA, with MDEA exhibiting a more pronounced effect [47]. Foaming height shows concentration-dependent enhancement for both additives, though MDEA produces significantly greater foam formation, particularly above 750 mg/L where the increase becomes markedly steeper. Similarly, defoaming time extends progressively with rising concentrations of both compounds, with MDEA again demonstrating a stronger impact. These findings suggest maintaining hydrogen sulfide and MDEA concentrations below 750 mg/L in TEG systems optimizes performance stability, preventing excessive surface tension reduction, foam formation, and defoaming difficulties associated with higher concentrations.

3.7. Measures for Impurity Control and Foaming Inhibition in TEG Dehydration System

The TEG dehydration system primarily accumulates impurities from feed gas constituents, including water-soluble inorganic salts, solid particulates, and hydrocarbons. Effective impurity control requires comprehensive feed gas pretreatment: installation of high-efficiency three-phase separators coupled with filter separators to remove gaseous, liquid, and solid impurities before absorption tower entry. Hydrocarbon management demands tiered approaches: light hydrocarbons (maximum 1% content) are removed through flash tank heating with extended residence time, while heavy hydrocarbons (maximum 0.1% content) are captured by activated carbon filtration to prevent TEG foaming-induced carryover. Solid impurities (<300 mg/L) and total residues (<2%) require precise regulation via optimized TEG filtration, with regular compositional monitoring of residues (solids, salts, heavy hydrocarbons, and degradation products) to evaluate contamination levels. Process parameter optimization is equally critical: maintaining dehydration temperatures within 27–37 °C, controlling absorber pressure ≤ 8 MPa, limiting reboiler regeneration temperature ≤ 205 °C to prevent TEG thermal degradation, and implementing real-time system monitoring to mitigate foaming risks from operational fluctuations.

4. Conclusions

Under cyclic regeneration, triethylene glycol (TEG) degradation occurs primarily through molecular decomposition, generating organic impurities. Various contaminants differentially influence TEG’s foaming performance: chemical additives > solid impurities > water-soluble inorganic salts > MDEA > hydrogen sulfide > hydrocarbons.
Inorganic salt effects depend on crystalline morphology—finely dispersed, uniform particles increase both foaming height and defoaming time. The relative impact follows: MgCl2 > NaHCO3 > KCl > NaCl > Na2SO4 > CaCl2.
Solid impurities significantly affect foaming characteristics. Small, monodisperse particles enhance foam stability and prolong defoaming time, while large or polydisperse particles show opposite effects. The performance hierarchy is: CaCO3 > Fe2O3 > CaSO4 > ZnO > CuO > Al2O3 > FeS.
Surfactant components in corrosion/foam inhibitors substantially modify foaming behavior. These additives orient at gas-liquid interfaces, forming stable films that simultaneously reduce surface tension and enhance film elasticity, facilitating foam formation and dramatically improving stability.
Hydrocarbons exhibit minimal foaming influence, with increasing concentrations actually raising surface tension and weakening foam formation. Light hydrocarbons predominantly affect surface tension, while heavy hydrocarbons impact defoaming time more significantly.

Author Contributions

Conceptualization, H.L. and J.M.; methodology, H.L.; validation, H.L., X.L. (Xin Li) and H.Y.; formal analysis, Q.H.; investigation, H.L.; resources, Q.W.; data curation, X.L. (Xin Li); writing—original draft preparation, H.L.; writing—review and editing, H.L.; visualization, Q.H.; supervision, J.M. and X.L. (Xueyuan Long); project administration, J.M. and X.L. (Xueyuan Long); funding acquisition, J.M. and X.L. (Xueyuan Long). All authors have read and agreed to the published version of the manuscript.

Funding

This research was supported by the National Natural Science Foundation of China (51904051), the Natural Science Foundation of Chongqing, China (CSTB2024NSCQ-MSX1103, cstc2021jcyj-msxmX0978).

Data Availability Statement

Data are unavailable due to privacy and ethical restrictions.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Ma, X.; Dou, L.; Wang, H.; Liu, D.; Ba, D.; Zhao, Q.; Zhao, S.; Li, Q.; Liao, X.; Qu, J.; et al. The Future of Sustainable Development Driven by Natural Gas—Overview of the 28th World Natural Gas Conference. Nat. Gas Ind. 2022, 42, 1–6. [Google Scholar]
  2. Zhou, Q. The Position of China’s Petroleum and Natural Gas in the World. Pet. Nat. Gas Geol. 2020, 41, 888. [Google Scholar]
  3. Alcheikhhamdon, Y.; Hoorfar, M. Natural gas quality enhancement: A review of the conventional treatment processes, and the industrial challenges facing emerging technologies. J. Nat. Gas Sci. Eng. 2016, 34, 689–701. [Google Scholar] [CrossRef]
  4. Eldemerdash, U.N.; Abdrabou, M.; El-Sheltawy, S.T.; Abdelghany, A. Assessment of chemical enhancement and energy consumption of natural gas dehydration processes. Gas Sci. Eng. 2024, 123, 205226. [Google Scholar] [CrossRef]
  5. Gonfa, G.; Kidanu, A.; Prabhu, S.V.; Gomadurai, C. Introduction to natural gas dehydration methods and technologies. In Advances in Natural Gas: Formation, Processing, and Applications; Natural Gas Dehydration, Rahimpour, M.R., Makarem, M.A., Meshksar, M., Eds.; Elsevier: Amsterdam, The Netherlands, 2024; Volume 4, pp. 3–27. [Google Scholar]
  6. Ma, C.; Liu, X.; Zheng, H.; Wu, X.; Zhang, C. Research on the regulation method of triglycol dehydration system based on sensitivity analysis. Oil Nat. Gas Chem. Ind. 2021, 50, 1–8. [Google Scholar]
  7. Yang, Y.; Chen, Q.; Li, Z. Application of triglycol dehydration technology in Yuanba gas field purification device. Oil Nat. Gas Chem. Ind. 2021, 50, 9–14+19. [Google Scholar]
  8. Wang, Y.; San, C.; Wu, K. Research on the evaluation of the dehydration effect of shale gas triglycol dehydration device. Oil Nat. Gas Chem. Ind. 2020, 49, 1–7. [Google Scholar]
  9. Guo, P.; Ran, W.; Liu, H. Research progress on the prediction of natural gas hydrate generation conditions. Sci. Technol. Eng. 2018, 18, 133–139. [Google Scholar]
  10. Zhao, H.; Xia, Y.; Zhang, D.; Niu, M.; Ma, H.; Li, W. Research on the influence of impurities on the dehydration ability of triglycol. Nat. Gas Chem. Ind. (C1Chemistry Chem. Ind.) 2016, 41, 47–51. [Google Scholar]
  11. Li, C.; Li, Y.; Ran, S.; Chen, S.; Wu, M.; Yang, Y. Design and Application of Amine Liquid Online Deep Resurrection Device. Pet. Nat. Gas Chem. Ind. 2024, 53, 26–30. [Google Scholar]
  12. Chen, Q.; Peng, X.; Wu, M.; Zhang, X.; Huang, H. Analysis of Potential Bubbling Substances in Upstream Operations of Natural Gas Purification Plants. Pet. Nat. Gas Chem. Ind. 2022, 51, 33–37. [Google Scholar]
  13. Gao, C.; Liu, R.; Yang, J.; Zhao, H.; Wei, W.; Xie, J. Experimental study on removal of hydrocarbon impurities in MDEA and optimization of filtration system. Pet. Nat. Gas Chem. Ind. 2023, 52, 19–24. [Google Scholar]
  14. Jiang, J.; Yue, Y.; Chen, S. Analysis of the influence of process parameters on the safe and stable operation of MDEA desulfurization unit. Pet. Nat. Gas Chem. Ind. 2019, 48, 28–33. [Google Scholar]
  15. Alhseinat, E.; Pal, P.; Ganesan, A.; Banat, F. Effect of MDEA degradation products on foaming behavior and physical properties of aqueous MDEA solutions. Int. J. Greenh. Gas Control 2015, 37, 280–286. [Google Scholar] [CrossRef]
  16. Alhseinat, E.; Amr, M.; Jumah, R.; Banat, F. Removal of MDEA foam creators using foam fractionation: Parametric study coupled with foam characterization. J. Nat. Gas Sci. Eng. 2015, 26, 502–509. [Google Scholar] [CrossRef]
  17. Guo, B.; He, Z.; Liu, X.; Jiang, A.; Wang, L.; Liu, C. Analysis and recovery research on the failure cause of triglycol. Nat. Gas Ind. 2006, 9, 152–153+181. [Google Scholar]
  18. Jin, X.; Zhang, N.; Wu, X.; Chen, Z. Research on the impact of pollutants on the dehydration and foaming of triglycol. Nat. Gas Ind. 2005, 25, 97–98+105. [Google Scholar]
  19. Guo, H.; Li, D.; Lei, X.; Zhao, H.; Wang, X.; Gao, J.; Li, W. Inactivation analysis and degradation characteristics of triglycol solution. J. Chem. Eng. Coll. Univ. 2017, 31, 1127–1134. [Google Scholar]
  20. Jiang, H.; Yang, C.; Zhu, C. Process analysis and improvement of natural gas dehydration device. Nat. Gas Chem. Ind. (C1 Chem. Chem. Ind.) 2009, 34, 49–53+58. [Google Scholar]
  21. Li, M.; Xu, L.; Zhang, Y.; Fan, J.; Du, Y.; Pu, Y. The use of triglycol in natural gas dehydration production. Drill. Process 2005, 28, 107–108. [Google Scholar]
  22. Al-Aiderous, A. Troubleshooting Gas Dehydration Systems ULZ 001066 Using Data Analysis. In Proceedings of the Abu Dhabi International Petroleum Exhibition & Conference, Abu Dhabi, United Arab Emirates, 15–18 November 2021. [Google Scholar]
  23. Arubi, T.I.M.; Duru, U.I. Optimizing Glycol Dehydration SystemFor Maximum Efficiency: A Case Study of a Gas Plant in Nigeria. In Proceedings of the CIPC/SPE Gas Technology Symposium 2008 Joint Conference, Calgary, AB, Canada, 16–19 June 2008; SPE: Calgary, AB, Canada, 2016; p. 113781. [Google Scholar]
  24. Soliman; Mohamed; Alwani; Abdo, M.; Aiderous, A.Y. Troubleshooting Glycol Loss in Gas De-hydration Systems Using Data Analysis at Upstream Operation. In Proceedings of the Abu Dhabi International Petroleum EXhibition & Conference, Abu Dhabi, United Arab Emirates, 11–14 November 2019. [Google Scholar]
  25. Dugstad, A.; Sirnes, H. Experimental Study of Black Powder Formation in Field TEG solutions. In Proceedings of the CORROSION 2011, Houston, TX, USA, 13–17 March 2011; p. 11083. [Google Scholar]
  26. GB/T 7462-1994; Surfactant, Determination of Foaming Power, Improvement Ross-Miles Law. General Administration of Quality Supervision, Inspection and Quarantine of the People’s Republic of China: Beijing, China, 1994.
  27. Wu, X.; Kang, X. Methyldiethanolamine(MDEA)Research on the influencing factors and mechanism of desulfurization solution foaming. Nat. Gas Chem. Ind. (C1 Chem. Chem. Ind.) 2008, 33, 31–36. [Google Scholar]
  28. Xiao, F.; Bai, B.; Gao, F. The influence of inorganic salts and hydrogen sulfide on the dehydration of natural gas triglycol ULZ 001094. Oil Nat. Gas Chem. Ind. 2022, 51, 1–6. [Google Scholar]
  29. Weng, J.; Xia, Y.; Huang, C.; Chen, X.; Song, L.; Zhang, Z.; Xun, R. Research on the purification method of triglycol dehydration solution in Jingbian gas field. Oil Gas Chem. Ind. 2017, 46, 16–21. [Google Scholar]
  30. Long, X.; Zhou, Q.; Meng, J. Experimental study on the effect of water-soluble inorganic salts on the dehydration performance of triglycol. Oil Nat. Gas Chem. Ind. 2023, 52, 9–15. [Google Scholar]
  31. Dong, X.Q.; Xu, J.; Cao, C.B.; Sun, D.J.; Jiang, X. Aqueous foam stabilized by hydrophobically modified silica particles and liqui D paraffin droplets. Colloids Surf. A. 2010, 353, 181–188. [Google Scholar] [CrossRef]
  32. Zhao, G.; Fang, J.; Dai, C.; Yan, Y.; Yan, Z.; Qing, Y. Enhanced Foam Stability By Adding Dispersed Particle Gel: A New 3-Phase Foam Study. In Proceedings of the SPE Asia PAcific Enhanced Oil Recovery Conference, Kuala Lumpur, Malaysia, 11–13 August 2015. [Google Scholar]
  33. Meng, J.; Yuan, L.; Liu, T.; Dong, B. The effect of inorganic salts on triglycol rheusity. Oil Gas Storage Transp. 2015, 34, 849–853. [Google Scholar]
  34. Jiang, N.; Yu, X.; Sheng, Y.; Zong, R.; Li, C. Role of salts in performance of foam stAbilized with sodium dodecyl sulfate. Chem. Eng. Sci. 2020, 216, 115474. [Google Scholar] [CrossRef]
  35. Zhao, H.; Cui, G. Research on the forced defoaming of coal sludge flotation foam by polydimethylsiloxane. Clean Coal Technol. 2021, 27, 212–217. [Google Scholar]
  36. Wang, H.; Liang, H.; Liu, Y.; Bai, J.; He, Y.; Gao, W. Research on the dehydration and defoaming characteristics of foam-assisted deoxidation air-driven extraction liquid. Oil Gas Field Ground Eng. 2023, 42, 23–27. [Google Scholar]
  37. Wu, G. Research on the Mechanism of the Influence of Inorganic Salts on the Foam Stability of Surfactants and Their Composite Systems. Ph.D. Thesis, China University of Petroleum (East China), Qingdao, China, 2017. [Google Scholar]
  38. Ibrahim, T.K.; Abdulrahman, R.K.; Khalaf, F.H.; Kamal, I.M. The Impact of Stripping Gas Flow Rate on Triethylene Glycol Losses fromGlycol Regeneration Unit: Si Mulation study. J. Chem. Eng. Process Technol. 2017, 8, 1000337. [Google Scholar]
  39. Long, X.; Cheng, H.; Zhang, Q. Experimental research on the effect of solid impurities on the quality of triglycol for natural gas dehydration Study intensively. Nat. Gas Chem. Ind. (C1 Chem. Chem. Ind.) 2022, 47, 106–112. [Google Scholar]
  40. Fang, C.; Ma, J.; Duan, X. Analysis of the impact of shale gas well return discharge on dehydration devices at different stages. Nat. Gas Oil 2021, 39, 7–11. [Google Scholar]
  41. Wu, J.; Wu, X.; Zhang, N.; Wang, X. Changqing Gas Field Second Purification Plant MDEA Desulfurization Solution Foaming Cause (II)—Foaming Causes and Treatment Measures. Nat. Gas Ind. 2005, 4, 171–174+26. [Google Scholar]
  42. Lai, X.; Zhang, Y.; Guo, L.; Yao, B.; Liu, J.; Yang, H. Research on the oil-repellent properties of ultra-low interface tension surfactants. Fine Petrochem. 2014, 31, 40–44. [Google Scholar]
  43. Parvaneh, R.; Riahi, S.; Lotfollahi, M.N. Experimental Evaluation of a Polymer Foam Agent on the Foam Stability, Concern to Surfactant, Nanop Article, and Salinity. SPE J. 2022, 27, 1462–1479. [Google Scholar] [CrossRef]
  44. Deng, L.; Li, G.; Cao, Y.; Wang, J. Research on the effect of flotation foaming agent on bubble merger behavior. J. China Min. Univ. 2017, 46, 410–414. [Google Scholar]
  45. Wang, C.; Yi, Y.; Sun, C.; Ding, F.; Mao, R.; Han, J. The influence of the properties of the gas/liquid interface membrane of the defoamer on its defoaming performance. Dly. Chem. Ind. 2017, 47, 13–17. [Google Scholar]
  46. Zhu, W.; Peng, X.; Ye, H. MDEA Desulfurization Solution Foaming Research. Pet. Nat. Gas Chem. Ind. 2015, 44, 22–27. [Google Scholar]
  47. Liu, Q.; Yang, C.; Tang, J. Analysis of the foaming characteristics of natural gas selective dethiamine solution formula. Nat. Gas Chem. Ind. (C1 Chem. Chem. Ind.) 2020, 45, 81–89. [Google Scholar]
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Figure 1. (a) Triethylene glycol regeneration device. (b) Triethylene glycol foaming detection device.
Figure 1. (a) Triethylene glycol regeneration device. (b) Triethylene glycol foaming detection device.
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Figure 2. (a) Relationship between foaming height and inorganic salt concentration curve; (b) Relationship between defoaming time and inorganic salt concentration curve; (c) Relationship between surface tension and inorganic salt concentration.
Figure 2. (a) Relationship between foaming height and inorganic salt concentration curve; (b) Relationship between defoaming time and inorganic salt concentration curve; (c) Relationship between surface tension and inorganic salt concentration.
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Figure 3. (a) Relationship between the foaming height and the concentration curve of solid impurities; (b) Relationship between defoaming time and solid impurity concentration curve; (c) Relationship between surface tension and solid impurity concentration.
Figure 3. (a) Relationship between the foaming height and the concentration curve of solid impurities; (b) Relationship between defoaming time and solid impurity concentration curve; (c) Relationship between surface tension and solid impurity concentration.
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Figure 4. (a) Relationship curve between corrosion inhibitor, defoamer concentration and height of triethylene glycol; (b) Relationship curve between corrosion inhibitor, defoamer concentration and defoaming time of triethylene glycol; (c) Relationship between surface tension and solid impurity concentration.
Figure 4. (a) Relationship curve between corrosion inhibitor, defoamer concentration and height of triethylene glycol; (b) Relationship curve between corrosion inhibitor, defoamer concentration and defoaming time of triethylene glycol; (c) Relationship between surface tension and solid impurity concentration.
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Figure 5. (a) Relationship curve between concentration of hydrocarbon substances and foaming height of triethylene glycol; (b) Relationship curve between concentration of hydrocarbon substances and defoaming time of triethylene glycol; (c) Relationship curve between hydrocarbon concentration and surface tension of triethylene glycol.
Figure 5. (a) Relationship curve between concentration of hydrocarbon substances and foaming height of triethylene glycol; (b) Relationship curve between concentration of hydrocarbon substances and defoaming time of triethylene glycol; (c) Relationship curve between hydrocarbon concentration and surface tension of triethylene glycol.
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Figure 6. (a) Relationship diagram between hydrogen sulfide, MDEA concentration and triethylene glycol foaming height; (b) Relationship between hydrogen sulfide, MDEA concentration and defoaming time of triethylene glycol; (c) Relationship diagram between hydrogen sulfide, MDEA concentration and surface tension of triethylene glycol.
Figure 6. (a) Relationship diagram between hydrogen sulfide, MDEA concentration and triethylene glycol foaming height; (b) Relationship between hydrogen sulfide, MDEA concentration and defoaming time of triethylene glycol; (c) Relationship diagram between hydrogen sulfide, MDEA concentration and surface tension of triethylene glycol.
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Table 1. Main experimental devices and their suppliers.
Table 1. Main experimental devices and their suppliers.
Experimental SetupProvider
HH-W602 Super Constant Temperature Oil BathTianjing Experimental Instrument Factory, Changzhou, Jiangsu, China
JJ2000B Rotating Drop Surface tension/Contact Angle Measuring InstrumentShanghai Zhongchen Digital Technology Equipment Co, Shanghai, China.
Self-constructed experimental equipment for regeneration of triethylene glycolself-build
Self-constructed triethylene glycol foaming equipmentself-build
Experimental reagents.
Table 2. Main experimental reagents and their suppliers.
Table 2. Main experimental reagents and their suppliers.
Experimental ReagentsSupplier, Purity
C6H14O4, NaCl, KCl, MgCl2·6H2O, CaCl2, NaHCO3, BaCl2·2H2O, anhydrous Na2SO4, petroleum ether, gasolineChengdu Cologne Chemical Co., Ltd., Chengdu, Sichuan, China, analytical pure
Na2SO4, FeCl3·6H2O, CuO, Al2O3Tianjin Zhiyuan Chemical Reagent Co., Ltd., Tianjin, China, analytical pure
Fe2O3, FeS, CaSO4·H2O, CaCO3Xilong Science Co., Ltd., Chaoshan, Shantou, Chian, analytical pure
ZnOShandong Miguel Mirabella Chemical Co., yanggu, Shandong, China.
Corrosion inhibitor, defoamerLongwangmiao natural gas purification plant use
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Liang, H.; Huang, Q.; Li, X.; Wu, Q.; Yan, H.; Meng, J.; Long, X. Investigation of the Factors and Mechanisms Affecting the Foaming of Triethylene Glycol in Natural Gas Purification. Processes 2025, 13, 1261. https://doi.org/10.3390/pr13051261

AMA Style

Liang H, Huang Q, Li X, Wu Q, Yan H, Meng J, Long X. Investigation of the Factors and Mechanisms Affecting the Foaming of Triethylene Glycol in Natural Gas Purification. Processes. 2025; 13(5):1261. https://doi.org/10.3390/pr13051261

Chicago/Turabian Style

Liang, Hongyi, Qian Huang, Xin Li, Quan Wu, Han Yan, Jiang Meng, and Xueyuan Long. 2025. "Investigation of the Factors and Mechanisms Affecting the Foaming of Triethylene Glycol in Natural Gas Purification" Processes 13, no. 5: 1261. https://doi.org/10.3390/pr13051261

APA Style

Liang, H., Huang, Q., Li, X., Wu, Q., Yan, H., Meng, J., & Long, X. (2025). Investigation of the Factors and Mechanisms Affecting the Foaming of Triethylene Glycol in Natural Gas Purification. Processes, 13(5), 1261. https://doi.org/10.3390/pr13051261

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