Stabilized operation method for inhibiting acidic discoloration and corrosion of sulfolane extraction agent and reducing energy consumption

Abstract

The invention relates to the technical field of stable operation of aromatic hydrocarbon extraction solvents, in particular to a stable operation method for inhibiting acidic discoloration and corrosion of a sulfolane extraction agent and reducing energy consumption. A core film-forming agent concentrated solution, a first water-containing sulfolane dispersion solution, a cerium source concentrated solution and a second water-containing sulfolane dispersion solution are sequentially added into a lean solvent main line, a stable protective layer is formed on the metal surface through the progressive interface reaction design of position opening, repairing and sealing, the vicious circle of solvent degradation and equipment corrosion is effectively cut off, and the service life of the metal surface is prolonged. Meanwhile, the regeneration energy consumption is reduced, and the method is suitable for stable operation of a sulfolane aromatic hydrocarbon extraction device.

Description

Technical Field

[0001] This invention relates to the field of aromatic hydrocarbon extraction solvent stabilization operation technology, specifically to a stabilization operation method that inhibits acidic discoloration and corrosion of sulfolane extractant and reduces energy consumption. Background Technology

[0002] Sulfolane, as an excellent polar solvent, is widely used in petrochemical fields such as aromatic hydrocarbon extraction and gas purification. However, in long-term industrial applications, the degradation of sulfolane has consistently been a key factor affecting the long-term stable operation of equipment. Existing research shows that in the presence of moisture and oxygen, sulfolane readily undergoes hydrolysis and oxidation reactions, generating acidic byproducts such as sulfonic acids and sulfate esters. These acidic substances not only exacerbate the color increase and quality deterioration of the sulfolane solvent itself but also pose a serious corrosion threat to commonly used equipment materials such as carbon steel and stainless steel. Especially in high-temperature loops such as the bottom of the regeneration tower, reboiler, and lean / rich solvent heat exchangers, local temperatures can reach above 160°C. The superposition of acid corrosion and thermal stress makes these areas high-risk sites for corrosion failure in the entire unit. Corrosion products such as iron ions further enter the solvent system, catalyzing the degradation reaction of sulfolane, forming a vicious cycle of solvent deterioration - equipment corrosion - further solvent deterioration.

[0003] To address these issues, common industrial measures include: setting up solvent regeneration units to remove some acidic degradation products through intermittent or continuous regeneration; periodically adding fresh sulfolane to the system to dilute degraded components; and cleaning or replacing severely corroded equipment during plant shutdowns for maintenance. However, these methods are essentially reactive strategies, intervening only after corrosion and solvent degradation have occurred and reached a certain severity. They are insufficient to break the chain of continuous degradation of metal surfaces at its source. For example, even if regeneration reduces the bulk acid value, the iron oxide micro-regions and active sites already formed on the equipment walls will continue to catalyze localized solvent degradation and induce pitting corrosion and other localized corrosion. These problems are particularly prominent on the surfaces of high-temperature heat exchangers and reboiler tube bundles.

[0004] Therefore, there is an urgent need to develop a stable operation method that can actively construct a stable protective layer at the metal / solvent interface, thereby cutting off the corrosion and degradation chain. Summary of the Invention

[0005] In view of this, the purpose of this invention is to propose a stable operation method that inhibits acid discoloration and corrosion of sulfolane extractant and reduces energy consumption, so as to solve the problem that in the existing sulfolane device regeneration circuit, the vicious cycle of continuous induction of solvent deterioration and corrosion by active sites on metal surfaces is difficult to be effectively cut off, resulting in high equipment corrosion rate, large increase in solvent color, and high regeneration energy consumption.

[0006] To achieve the above objectives, the present invention provides a stable operation method for inhibiting acidic discoloration and corrosion of sulfolane extractant and reducing energy consumption, comprising the following steps:

[0007] The device is kept in normal operation with circulating sulfolane. The core film-forming agent concentrate is continuously added to the lean solvent main line between the reboiler outlet and the lean-rich solvent heat exchanger inlet. After the core film-forming agent concentrate is added, the device circulating sulfolane is drawn out from the lean solvent side line, cooled, and then deionized water is added to form a first aqueous sulfolane dispersion. The first aqueous sulfolane dispersion is then reinjected into the lean solvent main line. After the first aqueous sulfolane dispersion is reinjected, cerium source concentrate is added to the lean solvent main line. After the cerium source concentrate is added, the device circulating sulfolane is drawn out from the lean solvent side line again, cooled, and then deionized water is added to form a second aqueous sulfolane dispersion. The second aqueous sulfolane dispersion is then reinjected into the lean solvent main line. After the second aqueous sulfolane dispersion is reinjected, the original circulation and conventional dehydration conditions of the device are maintained.

[0008] The core film-forming agent concentrate is prepared from sulfolane and silane-functionalized imidazoline film-forming agent;

[0009] The silane-functionalized imidazoline film-forming agent is obtained by reacting tridecanoic acid, pentadecanoic acid and silane coupling agent Silquest A-1120;

[0010] The cerium source concentrate was prepared from cerium octanoate and sulfolane;

[0011] The amount of water added to the second aqueous sulfolane dispersion is lower than the amount of water added to the first aqueous sulfolane dispersion.

[0012] The core film-forming agent concentrate is prepared by mixing a silane-functionalized imidazoline film-forming agent and sulfolane.

[0013] The mass ratio of the silane-functionalized imidazoline film-forming agent to sulfolane is 10-14:86-90.

[0014] The mass ratio of tridecanoic acid, pentadecanoic acid and silane coupling agent Silquest A-1120 is 86-129:97-145:229;

[0015] The specific preparation steps of the silane-functionalized imidazoline film-forming agent are as follows: under a nitrogen atmosphere, tridecanoic acid and pentadecanoic acid are first heated and melted, then silane coupling agent Silquest A-1120 is added, and after being kept at 140°C for 2 hours, the reaction is continued for 3 hours under reduced pressure of 170-180°C and 25-30 kPa.

[0016] Preferably, the mass ratio of cerium octanoate to sulfolane is 18-20:80-82.

[0017] Preferably, based on a 10,000 kg device circulating sulfolane, the core film-forming agent concentrate is continuously added through the conventional reagent injection port of the lean solvent main line, and the amount of core film-forming agent concentrate added is 4,000-4,500 g, with an addition time of 90-120 min.

[0018] Preferably, based on a 10,000 kg unit circulating sulfolane, after adding the core film-forming agent concentrate for 75-90 minutes, 40-60 kg of unit circulating sulfolane is drawn from the lean solvent side line and cooled to 40°C. 600-900 g of deionized water is added, and the mixture is stirred for 10 minutes to form the first aqueous sulfolane dispersion. This dispersion is then reinjected into the lean solvent main line through the conventional reagent injection port within 10-15 minutes.

[0019] Preferably, based on a 10,000 kg device circulating sulfolane, 15-18 minutes after the first aqueous sulfolane dispersion is reinjected, 600-840 g of cerium source concentrate is continuously added through a conventional reagent injection port over a period of 15-25 minutes.

[0020] Preferably, based on a 10,000 kg unit circulating sulfolane, 20-30 minutes after the addition of the cerium source concentrate, another 15-25 kg of unit circulating sulfolane is drawn from the lean solvent side line and cooled to 40°C. 200-300 g of deionized water is added, and the mixture is stirred for 5 minutes to form the second aqueous sulfolane dispersion. The dispersion is then reinjected into the lean solvent main line through a conventional reagent injection port within 6-10 minutes.

[0021] Preferably, after the second aqueous sulfolane dispersion is reinjected, the original circulation and conventional dehydration conditions of the device are maintained for 6 hours to reduce the water content of the system to below 500 mg / kg.

[0022] Preferably, after the initial film formation is completed, the stabilization operation method continues to operate stably for 48-72 hours, then the core film-forming agent concentrate is added again, and thereafter the cerium source concentrate is added once every 7-10 days.

[0023] Preferably, the amount of elemental cerium added when adding cerium source concentrate every 7-10 days is 0.5 mg / kg.

[0024] Preferably, in the stabilization operation method, when the sulfolane acid value increases twice consecutively, the daily color increase exceeds level 1, or fresh active points appear on the reboiler outlet plate, the process of forming and reinjecting the first aqueous sulfolane dispersion, adding cerium source concentrate, and forming and reinjecting the second aqueous sulfolane dispersion is repeated.

[0025] The beneficial effects of this invention are:

[0026] Compared with existing technologies, the stabilization operation method provided by this invention, through the active interface protection design for the regeneration tower bottom-reboiler-lean / rich solvent heat exchanger loop, constructs a dense and orderly protective film layer on the metal wall, achieving source control of corrosion and solvent degradation, and bringing about a comprehensive improvement in operational efficiency:

[0027] First, this invention utilizes a core film-forming agent to construct a dense and ordered film at the metal / solvent interface, which can effectively isolate sulfolane and its degradation products from direct contact with the metal surface, thereby significantly inhibiting the catalytic effect of metal ions on solvent degradation, breaking the vicious cycle of continuous generation of acidic byproducts and aggravated corrosion, and achieving a fundamental improvement in the stability of the solvent phase.

[0028] Secondly, the present invention achieves densification and long-lasting protection through a progressive interface reaction window design. This refined timing control enables the membrane to maintain structural integrity in high-temperature sulfolane regeneration and heat exchange interface scenarios, avoiding the problems of loose membrane or bulk phase condensation side reactions in traditional methods, and ensuring the continuity and stability of the protective effect.

[0029] Finally, while effectively controlling corrosion and solvent degradation, this invention also brings significant energy-saving and consumption-reducing effects.

[0030] In summary, this invention not only achieves excellent results in equipment protection and solvent quality maintenance, but also provides key technical support for the low-carbon and low-cost operation of sulfolane plants, realizing a balance between safety, environmental protection and economic benefits. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0032] Raw material sources and parameters: Silquest A-1120 silane coupling agent: Momentive, typical specific gravity 1.03, viscosity at 25℃ 6cSt, flash point 138℃, boiling point 259℃; Cerium octoate: Chengdu Dayang Chemical, model CEOC-1, cerium content greater than 23%, mechanical impurities less than 0.1%, moisture less than 1%; Sulfolane: bulk phase water content controlled below 500mg / kg.

[0033] Example 1: A method for stabilizing operation by inhibiting acidic discoloration and corrosion of sulfolane extractant and reducing energy consumption, the specific steps of which are as follows:

[0034] Preparation of S1 silane-functionalized imidazoline film-forming agent: Dry nitrogen gas was introduced into a conventional glass-lined reactor that had been dried at 120℃ for 2 hours. 107g of tridecanoic acid and 121g of pentadecanoic acid were added, and the mixture was heated to 60℃ and stirred until completely melted. Then, 229g of silane coupling agent Silquest A-1120 was slowly added at 60-70℃, with the addition completed over 30 minutes, followed by stirring for another 30 minutes. The temperature was then raised to 140℃ and held for 2 hours to allow the carboxyl group to preferentially amidate with the amino group in the diaminosilane. The temperature was then raised to 175℃ and the reaction continued for 3 hours under reduced pressure of 30kPa, continuously removing condensation water and a small amount of low-boiling substances. After a sample was taken and the acid value was measured to be no higher than 10mgKOH / g, the temperature was lowered to 80℃ and the mixture was hot-filtered through a 100-mesh stainless steel filter to obtain the silane-functionalized imidazoline film-forming agent.

[0035] Preparation of S2 core film-forming agent concentrate: Add 1200g of silane-functionalized imidazoline film-forming agent and 8800g of sulfolane to a dry container, stir at 50℃ for 30min until the liquid is uniform and transparent and there are no insoluble substances visible to the naked eye, to obtain the core film-forming agent concentrate.

[0036] Preparation of S3 cerium source concentrate: Add 1800g cerium octanoate and 8200g sulfolane to a dry container and stir at 60℃ for 60min until the liquid is in a homogeneous flow state to obtain cerium source concentrate.

[0037] S4 First Interface Pre-Adsorption Dosing: After maintaining the 10000kg unit circulating sulfolane in normal operation and confirming that the main line of lean solvent between the reboiler outlet and the inlet of the lean and rich solvent heat exchanger is in a stable flow state, 4000g of the core film-forming agent concentrate obtained from S2 is continuously added from the conventional reagent injection port of this main line. The addition time is controlled at 120min. During the addition process, the original filtration, circulation and conventional dehydration conditions of the unit are kept unchanged. Do not add directly to the bottom of the regeneration tower or the storage tank.

[0038] Implementation of the first aqueous sulfolane pulse in S5: After the reaction of the S4 system has proceeded for 90 minutes, 50 kg of sulfolane is drawn from the solvent-poor side line and circulated to cool to 40°C. Then, 800 g of deionized water is added and stirred for 10 minutes to form a uniform first aqueous sulfolane dispersion. The first aqueous sulfolane dispersion is then reinjected into the main line of S4 through the same reagent injection port within 12 minutes.

[0039] S6 Cerium Source Addition: 18 minutes after the S5 system reaction is completed, add 720g of cerium source concentrate continuously through the same reagent injection port, controlling the addition time to be 20 minutes;

[0040] Implementation of the second aqueous sulfolane pulse in S7: 25 min after the start of the reaction in the S6 system, 20 kg of sulfolane was drawn from the solvent-poor side line and circulated to 40°C. 250 g of deionized water was added to the circulated sulfolane and stirred for 5 min to form a uniform second aqueous sulfolane dispersion. The second aqueous sulfolane dispersion was then reinjected into the main line through the same reagent injection port within 8 min.

[0041] S8 Post-treatment and Maintenance Operation: After the reaction of the S7 system is completed, continue to maintain the original circulation and conventional dehydration conditions of the device for 6 hours to reduce the water content of the bulk phase of the system to below 500 mg / kg. After the first film formation is completed, run continuously and stably for 72 hours, then add 670 g of the core film-forming agent concentrate once to make the core film-forming agent replenishment amount 8 mg / kg; thereafter, add 120 g of cerium source concentrate once every 7 days to maintain the elemental cerium maintenance addition amount at 0.5 mg / kg; only when the sulfolane acid value increases twice consecutively, the daily color increase exceeds 1 level, or fresh active points appear on the reboiler outlet coupon, should S5 to S7 be executed again.

[0042] Example 2: A stable operation method for inhibiting acidic discoloration and corrosion of sulfolane extractant and reducing energy consumption, differing from Example 1 in that: in S1, 129g of tridecanoic acid, 97g of pentadecanoic acid, and 229g of silane coupling agent Silquest A-1120 are added; in S2, 1000g of silane-functionalized imidazoline film-forming agent and 9000g of sulfolane are added; in S3, 2000g of cerium octanoate and 8000g of sulfolane are added; in S4, 4000g of core film-forming agent concentrate is added over a period of 120 minutes; in S5, 40kg of sulfolane is circulated from the solvent-poor sideline and cooled to 40°C, 600g of deionized water is added, and after stirring for 10 minutes, a first aqueous sulfolane dispersion is formed, which is then reinjected into the mainline within 10 minutes; In step S6, 600g of cerium source concentrate was added over a period of 15 minutes. In step S7, 15kg of sulfolane was drawn from the solvent-poor side line and circulated to 40°C. 200g of deionized water was added and stirred for 5 minutes to form a second aqueous sulfolane dispersion, which was then reinjected into the main line within 6 minutes. In step S8, after the initial film formation was completed, the system was continuously and stably operated for 48 hours. Then, 500g of the core film-forming agent concentrate was added once, followed by 100g of cerium source concentrate every 10 days. The remaining conditions were the same as in Example 1.

[0043] Example 3: A stable operation method for inhibiting acid discoloration and corrosion of sulfolane extractant and reducing energy consumption, differing from Example 1 in that: S1, 86g of tridecanoic acid, 145g of pentadecanoic acid, and 229g of silane coupling agent Silquest A-1120 are added; S2, 1400g of silane-functionalized imidazoline film-forming agent and 8600g of sulfolane are added; S3, 1900g of cerium octanoate and 8100g of sulfolane are added; S4, 4200g of core film-forming agent concentrate is added over 90 minutes; S5, 60kg of sulfolane is circulated from the lean solvent sideline and cooled to 40°C, 900g of deionized water is added, and after stirring for 10 minutes, a first aqueous sulfolane dispersion is formed, which is then reinjected into the main line within 15 minutes; S6 Add 840g of cerium source concentrate over 25 minutes; in S7, draw 25kg of sulfolane from the lean solvent side line and cool it to 40°C, add 300g of deionized water, stir for 5 minutes to form a second aqueous sulfolane dispersion, and reinject it into the main line within 10 minutes; in S8, after the first film formation is completed, run continuously and stably for 72 hours, then add 700g of core film-forming agent concentrate once, and then add 140g of cerium source concentrate once every 7 days thereafter, with the remaining conditions the same as in Example 1.

[0044] Example 4: A stabilization operation method for inhibiting acidic discoloration and corrosion of sulfolane extractant and reducing energy consumption, differing from Example 1 in that: in S1, 107g of tridecanoic acid, 121g of pentadecanoic acid, and 229g of silane coupling agent Silquest A-1120 are added; in S2, 1200g of silane-functionalized imidazoline film-forming agent and 8800g of sulfolane are added; in S3, 1900g of cerium octanoate and 8100g of sulfolane are added; in S4, 4500g of core film-forming agent concentrate is added over 90 minutes; in S5, after the reaction in the S4 system proceeds for 75 minutes, 45kg of sulfolane is drawn from the solvent-poor side stream for circulating and cooled to 40°C, 700g of deionized water is added, and after stirring for 10 minutes, a first aqueous sulfolane dispersion is formed, which is then reinjected into the main stream within 10 minutes; in S6, the reaction in the S5 system proceeds... After 15 minutes, add 780g of cerium source concentrate over 18 minutes. In S7, 20 minutes after the start of the reaction in the S6 system, draw 20kg of sulfolane from the solvent-poor side stream to circulate the device and cool it to 40°C. Add 250g of deionized water and stir for 5 minutes to form a second aqueous sulfolane dispersion. Recycle the dispersion into the main stream within 6 minutes. In S8, after the first film formation is completed, run the device continuously and stably for 60 hours. Then add 600g of the core film-forming agent concentrate once. After that, add 110g of cerium source concentrate once every 8 days. The other conditions are the same as in Example 1.

[0045] Comparative Example 1: The difference from Example 1 is that in S1, 107g of tridecanoic acid and 121g of pentadecanoic acid are replaced with 214g of tridecanoic acid, pentadecanoic acid is no longer added, and silane coupling agent Silquest A-1120 is still added to prepare silane-functionalized imidazoline film-forming agent. The other conditions are the same as in Example 1.

[0046] Comparative Example 2: The difference from Example 1 is that in S1, 107g of tridecanoic acid and 121g of pentadecanoic acid are replaced with 214g of pentadecanoic acid, and tridecanoic acid is no longer added. Silquest A-1120, a silane coupling agent, is still added to prepare a silane-functionalized imidazoline film-forming agent. The other conditions are the same as in Example 1.

[0047] Comparative Example 3: The difference from Example 1 is that the first aqueous sulfolane dispersion in S5 and the second aqueous sulfolane dispersion in S7 are combined and added at once. Specifically, after the reaction in the S4 system has proceeded for 90 minutes, 70 kg of sulfolane is drawn from the lean solvent side stream for circulating circulation and cooled to 40°C. 1050 g of deionized water is added, and after stirring for 10 minutes, an aqueous sulfolane dispersion is formed. This dispersion is then reinjected into the main line through the same reagent injection port within 20 minutes, and S7 is not performed. In S6, 720 g of cerium source concentrate is added 18 minutes after the reinjection of the above aqueous sulfolane dispersion is completed, with an addition time of 20 minutes. The remaining conditions are the same as in Example 1.

[0048] Comparative Example 4: The difference from Example 1 is that S6 is changed to adding 720g of cerium source concentrate 18min after the reaction of the S7 system ends, and the addition time is 20min. The cerium source concentrate is no longer inserted between S5 and S7. The other conditions are the same as in Example 1.

[0049] Comparative Example 5: The difference from Example 1 is that the core film-forming agent concentrate and the cerium source concentrate are mixed and added together in S4, while the other conditions are the same as in Example 1.

[0050] Comparative Example 6: The difference from Example 1 is that in S5, 35 kg of sulfolane was drawn from the lean solvent sideline and circulated to 40°C, then 525 g of deionized water was added, and after stirring for 10 min, a first aqueous sulfolane dispersion was formed, which was then reinjected into the main line within 12 min; in S7, another 35 kg of sulfolane was drawn from the lean solvent sideline and circulated to 40°C, then 525 g of deionized water was added, and after stirring for 5 min, a second aqueous sulfolane dispersion was formed, which was then reinjected into the main line within 8 min. All other conditions were the same as in Example 1.

[0051] Performance testing

[0052] On the same sulfolane aromatics extraction unit, the examples and comparative examples were carried out sequentially. Before each test, conventional regeneration, conventional dehydration, and replenishment with the same batch of fresh sulfolane were used to adjust the initial state of 10,000 kg of circulating sulfolane to: bulk water content 500 mg / kg, acid value 0.064 mg KOH / g, color 6.0, regeneration tower bottom operating temperature 165℃, reboiler outlet lean solvent temperature 157℃, and the unit throughput controlled at 100% of the rated load. The same batch of No. 20 carbon steel was installed between the reboiler outlet and the inlet of the lean / rich solvent heat exchanger. Six standard hanging plates were used, all taken from the same set of equipment and the same material of pipeline scraps. The plates were wire-cut to a size of 50.0mm × 5.0mm × 2.0mm with a hanging hole diameter of 4.0mm. The surfaces of the hanging plates were successively polished with 240#, 400#, 800#, and 1200# sandpaper, then degreased with anhydrous ethanol, dried with hot air, and accurately weighed. Each scheme was run continuously for 168 hours. At 0h, 6h, 24h, 72h, and 168h, 250mL of sulfolane sample was taken from the same sampling port. The hanging plates were removed at 168h for corrosion rate testing using the weight loss method.

[0053] Water content test of sulfolane in bulk phase: The test was conducted in accordance with GB / T 11133-2015. Sulfolane samples collected at 0h, 6h, 24h, 72h and 168h were taken for each scheme. The samples were first allowed to stand at room temperature for 10min to remove visible air bubbles, and then the water content was determined by Karl Fischer coulometric titration. Each time point was measured in parallel 3 times and the arithmetic mean was taken.

[0054] Sulfolane acid value test: The test was conducted according to Method A in GB / T 7304-2014. Sulfolane samples collected at 0h, 24h, 72h and 168h were taken as samples, and the acid value was determined by potentiometric titration. The results were expressed as mgKOH / g.

[0055] Sulfolane colorimetric test: The test was conducted in accordance with GB / T 6540-1986. Sulfolane samples collected at 24h, 72h and 168h for each scheme were taken, and 50mL of each sample was added to the specified colorimetric container. The samples were visually compared with the standard color glass slides at 25℃, and the results were expressed by color number.

[0056] Carbon steel immersion strip corrosion rate test: The test was conducted according to GB / T 19291-2003. Sample size and full immersion test conditions were in accordance with JB / T 7901-2023. Corrosion product removal was performed according to GB / T 16545-2025. After each test was run for 168 hours, the immersion strips were removed. The surface residual liquid was first rinsed with sulfolane, and then the corrosion products were removed according to the corresponding carbon steel sample removal method in GB / T 16545-2025. After drying, the weight loss was measured. The corrosion rate was calculated using the weight loss method.

[0057] Operating energy consumption index test: Steam flow measurement was carried out in accordance with GB / T 2624.1-2006 and GB / T 2624.2-2006. During the test, the unit's throughput was maintained at 100% of the rated load. During the continuous operation of each scheme for 168 hours, the cumulative steam mass, average operating temperature of the regenerator reboiler steam branch orifice plate differential pressure flow meter, the average operating temperature of the regenerator bottom and the average temperature of the lean solvent at the reboiler outlet were recorded, and the cumulative steam consumption and average operating temperature of the regenerator bottom were calculated for 168 hours.

[0058] The test results are shown in Table 1.

[0059] Table 1 Performance Test Results

[0060]

[0061] Data Analysis: As can be seen from the data in Table 1 of the embodiments, the stabilized operating system prepared by the present invention shows a relatively consistent improvement trend in the sulfolane regeneration and heat exchange loop, namely, the enrichment degree of silicon and cerium on the wall surface is increased, the density of corrosion pits is reduced, the increase of sulfolane acid value and color is controlled, and the average operating temperature and cumulative steam consumption of the regeneration tower bottom decrease simultaneously.

[0062] As can be seen from the data in Table 1 for Examples 1, 1, and 2, when only tridecanoic acid and pentadecanoic acid are used, although an interface film containing trimethoxysilylpropyl groups can still be formed, the wall protection effect and the bulk stability effect are not as balanced as in Example 1. The reason is that a single chain length cannot simultaneously achieve dispersion stability in sulfolane, tight wall arrangement, and hydrophobic shielding effect under high-temperature flow conditions.

[0063] As can be seen from the data in Example 1 and Comparative Example 3 in Table 1, when the first and second aqueous sulfolane dispersions were added together in a single step, the bulk stability of sulfolane, the continuity of wall protection, and the improvement in operating energy consumption all significantly deteriorated. The main reason is that the single-step aqueous sulfolane dispersion amplifies both local hydrolysis and bulk condensation, causing the opening and sealing processes, which should have occurred near the metal wall, to overlap in time. This weakens the directionality of the orderly transformation of trimethoxysilylpropyl groups into the silicon-oxygen network. Simultaneously, the cerium source concentrate loses the window between the two aqueous sulfolane dispersions, making it difficult to preferentially occupy newly formed defect sites.

[0064] As can be seen from the data in Table 1 for Example 1 and Comparative Example 4, when the cerium source concentrate was added after the second aqueous sulfolane pulse, the cerium enrichment on the wall surface was significantly insufficient, while the density of corrosion pits and the corrosion rate deteriorated accordingly. This is because the cerium source concentrate entered the system after the first aqueous sulfolane pulse and before the second aqueous sulfolane pulse. At this time, the first batch of silanol sites and incompletely covered active sites had already formed near the metal wall, making it easier for the cerium source to perform directional defect repair.

[0065] As can be seen from the data in Table 1 for Example 1 and Comparative Example 5, when the core film-forming agent concentrate and the cerium source concentrate are mixed and added simultaneously, although both film-forming components and cerium components are present in the system, the overall effect is significantly reduced. The main reason is that the core film-forming agent concentrate and the cerium source concentrate are not simply used together, but must rely on the interfacial reaction window between them to produce an effect greater than the sum of its parts.

[0066] As can be seen from the data in Table 1 for Example 1 and Comparative Example 6, although both aqueous sulfolane dispersions were retained, the film density and bulk stability were still lower than in Example 1 even after adjusting the water volume to be the same. This is because the first aqueous sulfolane pulse functions as an on-site formation agent to create reaction sites, while the second aqueous sulfolane pulse functions as a catalyst for the post-condensation of residual methoxy groups and interfacial sealing, requiring a lower water volume to avoid further amplification of the bulk reaction.

[0067] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

Claims

1. A method for stabilizing operation that inhibits acidic discoloration and corrosion of sulfolane extractant and reduces energy consumption, characterized in that, Includes the following steps: The device is kept in normal operation with circulating sulfolane. The core film-forming agent concentrate is continuously added to the lean solvent main line between the reboiler outlet and the lean-rich solvent heat exchanger inlet. After the core film-forming agent concentrate is added, the device circulating sulfolane is drawn out from the lean solvent side line, cooled, and then deionized water is added to form a first aqueous sulfolane dispersion. The first aqueous sulfolane dispersion is then reinjected into the lean solvent main line. After the first aqueous sulfolane dispersion is reinjected, cerium source concentrate is added to the lean solvent main line. After the cerium source concentrate is added, the device circulating sulfolane is drawn out from the lean solvent side line again, cooled, and then deionized water is added to form a second aqueous sulfolane dispersion. The second aqueous sulfolane dispersion is then reinjected into the lean solvent main line. After the second aqueous sulfolane dispersion is reinjected, the original circulation and conventional dehydration conditions of the device are maintained. The core film-forming agent concentrate is prepared from sulfolane and silane-functionalized imidazoline film-forming agent; The silane-functionalized imidazoline film-forming agent is obtained by reacting tridecanoic acid, pentadecanoic acid and silane coupling agent Silquest A-1120; The cerium source concentrate was prepared from cerium octanoate and sulfolane; The amount of water added to the second aqueous sulfolane dispersion is lower than the amount of water added to the first aqueous sulfolane dispersion.

2. The stable operation method according to claim 1, characterized in that, The mass ratio of the silane-functionalized imidazoline film-forming agent to sulfolane is 10-14:86-90.

3. The stable operation method according to claim 1, characterized in that, The mass ratio of the tridecanoic acid, pentadecanoic acid and silane coupling agent Silquest A-1120 is 86-129:97-145:

229.

4. The stable operation method according to claim 1, characterized in that, The reaction was first kept at 140℃ for 2 hours, and then continued for 3 hours under reduced pressure of 170-180℃ and 25-30kPa.

5. The stable operation method according to claim 1, characterized in that, The mass ratio of cerium octanoate to sulfolane is 16-20:80-84.

6. The stable operation method according to claim 1, characterized in that, Based on a 10,000 kg device with circulating sulfolane, the amount of the core film-forming agent concentrate added is 4,000-4,500 g, and the addition time is 90-120 min.

7. The stable operation method according to claim 1, characterized in that, Based on a 10,000 kg unit circulating sulfolane, after adding the core film-forming agent concentrate for 75-90 minutes, 40-60 kg of the unit circulating sulfolane is drawn from the solvent-poor side stream and cooled to 40°C. Then, 600-900 g of deionized water is added to form the first aqueous sulfolane dispersion.

8. The stable operation method according to claim 1, characterized in that, The amount of cerium source concentrate added is 600-840g, based on the circulating sulfolane in a 10000kg device.

9. The stable operation method according to claim 1, characterized in that, Based on a 10,000 kg device circulating sulfolane, 20-30 minutes after the addition of the cerium source concentrate, another 15-25 kg of device circulating sulfolane is drawn from the lean solvent side stream and cooled to 40°C. Then, 200-300 g of deionized water is added to form a second aqueous sulfolane dispersion.

10. The stable operation method according to claim 1, characterized in that, After the initial film formation is completed, the stabilized operation method is continuously and stably operated for 48-72 hours, and then the core film-forming agent concentrate is added again. Thereafter, cerium source concentrate is added once every 7-10 days.

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