Method and system suitable for producing saturated C5 by pyrolysis gasoline hydrogenation device

Abstract

The invention discloses a method and a system suitable for producing saturated C5 by a pyrolysis gasoline hydrogenation device, and belongs to the technical field of petrochemical industry. Comprising the following steps: S1, carrying out first-stage hydrogenation reaction to remove diolefin in crude pyrolysis gasoline; s2, C9 separation: cutting out a C9 < + > component through a C9 < + > removal tower, and obtaining C5-C8 fractions at the tower top; s3, carrying out second-stage hydrogenation reaction, deeply saturating monoolefine and removing sulfide; and S4, refining and separating the product, desulfurizing, feeding into a depentanizer, extracting high-purity saturated C5 from the top of the depentanizer, and producing C6-C8 hydrogenated gasoline from the bottom of the depentanizer. The pentane removal tower is arranged at the tail end of the whole process, accurate cutting of C5 after complete hydrogenation purification is ensured, the product purity and stability are effectively improved, low-value unsaturated C5 can be converted into a high-added-value ethylene cracking raw material without changing the main body structure of an existing device, the delivery balance problem of C5 is solved, and the production cost is reduced. The self-sufficient capacity and the economic benefit of the light raw material are obviously enhanced.

Description

Technical Field

[0001] This invention belongs to the field of petrochemical technology, specifically relating to a method and system for producing saturated C5 in a cracked gasoline hydrogenation unit. Background Technology

[0002] Currently, cracked gasoline hydrogenation units generally adopt the "pre-dehydrogenation of C5" process, which involves pre-separating the unhydrogenated C5 fraction from the feedstock and sending it to downstream chemical C5 separation units for comprehensive utilization.

[0003] However, due to limitations in the design capacity of downstream units, the amount of unhydrogenated C5 that the C5 separation unit can receive is nearing its limit, making it difficult to meet the needs of upstream units to expand capacity or operate at high loads. At the same time, the export market for unsaturated C5 continues to shrink, and product prices are low, resulting in a significant reduction in the economic value of its direct sales.

[0004] The above factors together pose a severe challenge to the C5 component balance of the cracked gasoline hydrogenation unit: on the one hand, it cannot effectively digest all C5 fractions, and on the other hand, the existing product structure is difficult to maximize efficiency, which restricts the overall operational flexibility and economic benefits of the unit. Summary of the Invention

[0005] This invention addresses the aforementioned problems in the prior art by proposing a method and system for producing saturated C5 in a cracked gasoline hydrogenation unit.

[0006] This invention can be achieved through the following technical solutions:

[0007] A method for producing saturated C5 from cracked gasoline hydrotreating units includes:

[0008] S1, First-stage hydrogenation reaction: Crude cracked gasoline containing C5 to C9 components and hydrogen are injected into a first-stage hydrogenation reactor. Under preset reaction conditions, a first-stage hydrogenation reaction is carried out to remove diolefins from the cracked crude gasoline and obtain monoolefins and alkanes.

[0009] S2, C9 separation: The product of the first-stage hydrogenation reactor is separated into gas and liquid and injected into the decarbonization tower for diversion. The bottom of the decarbonization tower produces C9 product, and the top of the tower outputs a product containing C5-C8 components.

[0010] S3, Second-stage hydrogenation reaction: The product output from the top of the decarbonization tower is injected into the second-stage hydrogenation reactor. Under preset reaction conditions, the second-stage hydrogenation reaction is carried out to remove monoolefins and sulfides, and saturated hydrogenation products are obtained.

[0011] S4. Product Refining and Separation: After desulfurization, the product from the two-stage hydrogenation reactor is sent to the depentane tower for fractionation. Saturated C5 product is collected at the top of the tower, and hydrogenated gasoline containing C6-C8 components is produced at the bottom of the tower.

[0012] As a further improvement of the present invention, in step S1, the product of the hydrogenation reactor is sequentially separated into a high-pressure separator and a low-pressure separator for gas-liquid separation, wherein...

[0013] Hydrogen separated from the high-pressure separator is discharged from the top of the tower, and liquid products are output from the bottom of the tower. Part of the liquid products are injected into the low-pressure separator, and the other part is returned to the hydrogenation reactor as a circulating diluent.

[0014] Hydrogen and ammonia separated in a low-pressure separator are discharged from the top of the tower, while the liquid products are injected into the decarbonization tower from the bottom of the tower.

[0015] As a further improvement of the present invention, in step S1, the mixing ratio of crude cracked gasoline and first-stage circulating diluent is controlled so that the total concentration of dienes and styrene in the mixed feed is less than 10 wt%.

[0016] As a further improvement of the present invention, in step S1, the reaction pressure of the first hydrogenation reaction is 2.7-2.9 MPaG, and the inlet temperature of the first hydrogenation reactor is 60-80℃.

[0017] As a further improvement of the present invention, in step S3, the product from the bottom of the two-stage hydrogenation reactor is sequentially cooled by an air cooler and then sequentially injected into the two-stage high-pressure separator and the two-stage buffer tank.

[0018] The product obtained after hydrogen separation in the second-stage high-pressure separator flows out of the bottom of the tower. Part of it is used for downstream transport, and the other part is returned to the second-stage hydrogenation reactor as a second-stage circulating diluent.

[0019] The hydrogen separated from the second-stage high-pressure separator flows out from the top of the tower and is injected into the second-stage buffer tank. The hydrogen in the second-stage buffer tank is then injected back into the second-stage hydrogenation reactor as circulating hydrogen.

[0020] As a further improvement of the present invention, in step S3, the inlet temperature of the two-stage hydrogenation reactor is 230-300°C.

[0021] As a further improvement of the present invention, when the bed temperature of the second-stage hydrogenation reactor exceeds 70°C, the second-stage circulating diluent with an output temperature of 30-40°C from the second-stage high-pressure separator is injected into the feed pipeline of the second-stage hydrogenation reactor to control the inlet temperature of the second-stage hydrogenation reactor.

[0022] As a further improvement of the present invention, in step S4, the product separated from the two-stage high-pressure separator is desulfurized by a stripping tower, hydrogen sulfide is discharged from the top of the stripping tower, and the hydrogenated gasoline product containing C5-C8 components collected from the bottom of the tower is transported to the depentane tower.

[0023] A system for producing saturated C5 in a cracked gasoline hydrogenation unit is also provided, employing the aforementioned method for producing saturated C5 in a cracked gasoline hydrogenation unit, comprising a first-stage hydrogenation reactor, a decarbonization nine-stage tower, a second-stage hydrogenation reactor, a stripping tower, and a depentane tower connected in sequence, wherein...

[0024] A high-pressure separation tank and a low-pressure separation tank are installed between the hydrogenation reactor and the decarbonization tower.

[0025] A two-stage high-pressure separator and a two-stage buffer tank are installed between the two-stage hydrogenation reactor and the stripping tower.

[0026] As a further improvement of the present invention, a high-pressure separator is connected to a hydrogenation reactor via a circulation pump to form a circulation system, a high-pressure separator is connected to a low-pressure separator, and a low-pressure separator is connected to a decarbonization tower.

[0027] The top of the decarbonization tower is connected to a first buffer tank, which is connected to the top of the decarbonization tower via a circulation pump. The first buffer tank is also connected to the second-stage hydrogenation reactor via a circulation pump.

[0028] The two-stage hydrogenation reactor and the two-stage high-pressure separator are connected to form a two-stage circulation system. The two-stage high-pressure separator is also connected to the stripping tower. The two-stage hydrogenation reactor, the two-stage high-pressure separator, and the two-stage buffer tank are connected to form a two-stage hydrogen circulation system.

[0029] A second buffer tank is connected to the top of the stripping tower, and the second buffer tank is connected to the top of the stripping tower via a circulating pump;

[0030] The top of the depentanizer is connected to a third buffer tank, which is connected to the top of the depentanizer via a circulating pump.

[0031] Reboilers are installed on the circulation lines at the bottom of the decarbonization tower, stripping tower, and depentane tower, as well as on the feed lines of the first-stage hydrogenation reactor and the second-stage hydrogenation reactor.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. Achieve efficient conversion of unsaturated C5 to high-value-added saturated C5.

[0034] By placing the depentanizer at the final stage of the entire hydrogenation and refining process, the C5 fraction undergoes final C5 / C6+ separation only after completing all purification steps, including selective hydrogenation, removal of C9+ heavy components, deep hydrogenation, and stripping desulfurization. This design avoids product contamination or subsequent processing difficulties caused by premature separation of unhydrogenated or sulfur- or olefin-containing C5 fractions. This ensures the high purity and chemical stability of the saturated C5 product at the source, and the resulting product can be directly recycled as a high-quality light cracking feedstock for ethylene plants, significantly improving resource utilization efficiency and economic benefits.

[0035] 2. Effectively solves the problem of C5 factory balance and enhances the operational flexibility of the unit.

[0036] Without altering the main structure of the existing cracked gasoline hydrogenation unit, a new fully hydrogenated saturated C5 production mode is added, freeing the unit from dependence on the processing capacity of downstream C5 separation units and external markets, allowing for flexible responses to market fluctuations and ensuring stable high-load operation of the unit.

[0037] 3. Multiple temperature control and dilution mechanisms ensure safe and controllable reaction.

[0038] By setting up a low-temperature circulating diluent and a temperature rise-responsive control strategy, the violent exothermic reaction of hydrogenation is precisely suppressed, avoiding runaway temperatures, coking, or catalyst sintering, thus significantly improving operational safety and long-term operational reliability.

[0039] 4. Highly efficient recycling of hydrogen and materials reduces energy and raw material consumption.

[0040] A closed-loop hydrogen circulation system (including buffer tanks and compressors) and a liquid diluent recycling network are constructed to significantly reduce the amount of fresh hydrogen replenishment. At the same time, light components are completely removed through two-stage gas-liquid separation (high pressure + low pressure) to prevent impurities such as ammonia and H2S from interfering with subsequent fractionation and improve the overall energy efficiency of the system.

[0041] 5. High product purity and high-value by-products maximize resource utilization.

[0042] After stripping desulfurization and precise depentane fractionation, the saturated C5 product has high purity and extremely low sulfur content, fully meeting the standards for ethylene cracking feedstock; the by-product C6–C8 hydrogenated gasoline has a moderate octane number and good stability, and can be used as a high-quality blending component or chemical raw material, achieving "high value for both main and by-products". Attached Figure Description

[0043] Figure 1 This is a process flow diagram of the present invention applicable to the production of saturated C5 in a cracked gasoline hydrogenation unit.

[0044] In the diagram, 100 represents the feed buffer tank.

[0045] 200. First-stage hydrogenation reactor; 210. First-stage high-pressure separator; 220. First-stage low-pressure separator;

[0046] 300. Decarbonization Tower 9; 310. First Buffer Tank;

[0047] 400. Two-stage hydrogenation reactor; 410. Air cooler; 420. Two-stage high-pressure separator; 430. Two-stage buffer tank; 431. Two-stage hydrogen compressor;

[0048] 500. Stripping tower; 510. Second buffer tank;

[0049] 600. Depentanizer; 610. Third buffer tank;

[0050] 700. Circulating pump; 710. Reboiler. Detailed Implementation

[0051] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings to further illustrate the technical methods of the present invention. However, the present invention is not limited to these embodiments.

[0052] like Figure 1 As shown, the present invention provides a method for producing saturated C5 in a cracked gasoline hydrotreating unit, comprising:

[0053] S1. First-stage hydrogenation reaction: Crude cracked gasoline containing C5 to C9 components is injected into the feed buffer tank 100, and then injected into the first-stage hydrogenation reactor 200 along with hydrogen. Under preset reaction conditions, the first-stage hydrogenation reaction is carried out to remove diolefins from the cracked crude gasoline and obtain monoolefins and alkanes. The selective hydrogenation effectively removes easily polymerizable diolefins, significantly reducing the coking tendency of the material in the subsequent fractionation and transportation process, and ensuring the long-term stable operation of the unit.

[0054] S2, C9 Separation: After gas-liquid separation of the product from the first-stage hydrogenation reactor 200, it is injected into the C9 removal tower 300 for distillation. Under appropriate reflux ratio and bottom reboiling heat load, it is distilled to ensure that C9 and above heavy components (such as indene, naphthalene, etc.) are effectively retained in the bottom of the tower, while C5-C8 light components are distilled off from the top of the tower with high purity. Efficient removal of C9+ heavy components can prevent them from condensing or coking in the second-stage hydrogenation reactor 400, extend the catalyst life, and ensure that the composition of the feedstock entering the second-stage hydrogenation is stable and the impurity content is low, which is conducive to obtaining high-quality saturated C5 and hydrogenated gasoline products.

[0055] S3, Second-stage hydrogenation reaction: The product output from the top of the decarbonization tower 300 is injected into the second-stage hydrogenation reactor 400. Under preset reaction conditions, the second-stage hydrogenation reaction is carried out to completely saturate the residual monoolefins into alkanes and simultaneously convert organic sulfides into hydrogen sulfide, achieving synergistic purification of olefin removal and desulfurization, and obtaining saturated hydrogenated products. Through deep hydrogenation, unsaturated bonds are eliminated, and the C5 component is converted into chemically stable saturated alkanes, meeting the purity and stability requirements of the ethylene cracking unit for light cracking feedstock.

[0056] S4. Product Refining and Separation: The second-stage hydrogenation product is first stripped to remove acidic gases such as hydrogen sulfide, and then enters the 600 depentanizer tower. Under precise control of the tower top pressure and reflux ratio, precision fractionation is carried out to ensure that the C5 component is almost completely distilled off from the top of the tower, while the C6-C8 components are enriched in the bottom of the tower. This achieves effective separation of saturated C5 and hydrogenated gasoline. The precise fractionation operation can obtain high-purity saturated C5 product, which meets the feedstock requirements for ethylene cracking. At the same time, the by-product C6-C8 hydrogenated gasoline has a moderate octane number and extremely low sulfur content, which can be used as a high-quality blending component or chemical feedstock, maximizing resource utilization and significantly improving the overall economic benefits of the unit.

[0057] Overall, this application constructs a stable, efficient, and high-value-added saturated C5 production path by placing the depentanizer at the end of the entire process and optimizing the internal operating logic and reaction / separation objectives of the four core processes. Without changing the main structure of the existing plant, it successfully converts low-value unsaturated C5 into high-value-added ethylene cracking feedstock, solves the problem of C5 output balance, and significantly improves the plant's self-sufficiency and profitability of light feedstock.

[0058] Preferably, in step S1, the product of the hydrogenation reactor 200 is sequentially separated into gas and liquid phases by passing it through a high-pressure separator 210 and a low-pressure separator 220.

[0059] Hydrogen separated from the first-stage high-pressure separator 210 is discharged from the top of the tower and can be partially recycled back to the reaction system after compression. The liquid product is output from the bottom of the tower, part of which is returned to the inlet of the first-stage hydrogenation reactor 200 after cooling as a circulating diluent to adjust the concentration of diolefins in the feed and the reaction temperature rise. The other part is sent to the first-stage low-pressure separator 220.

[0060] Hydrogen and ammonia separated by a low-pressure separator 220 are discharged from the top of the tower, and the liquid product is injected into the decarbonization tower 300 from the bottom of the tower. The residual dissolved hydrogen and ammonia generated by the reaction (from the hydrogenation conversion of trace nitrogen compounds in the raw material) are further removed by the low-pressure separator 220 to ensure that the liquid material entering the subsequent fractionation system does not contain light gaseous impurities.

[0061] This two-stage gas-liquid separation and circulating dilution design not only effectively recovers unreacted hydrogen and reduces fresh hydrogen consumption, but also precisely controls the feed composition and heat load of the first-stage hydrogenation reactor 200 through circulating diluent, suppressing the side reaction of diolefin polymerization and ensuring a stable and controllable reaction. At the same time, it removes light components such as ammonia, preventing them from accumulating in the decarbonization tower 300 and causing corrosion or affecting fractionation efficiency, thereby improving the system's operational stability, catalyst life, and subsequent separation accuracy.

[0062] Preferably, in step S1, the feed composition after mixing the crude cracked gasoline is dynamically controlled by adjusting the feed flow rate of the crude cracked gasoline and the return flow rate of the first-stage circulating diluent (i.e., part of the liquid phase product extracted from the bottom of the first-stage high-pressure separator 210). This ensures that the total mass concentration of diolefins and styrene is strictly controlled below 10 wt%. This concentration threshold is set based on the selective hydrogenation performance of the catalyst and the thermodynamic characteristics of the reaction, which can effectively avoid the risks of local overheating and polymerization coking.

[0063] By controlling the total concentration of dienes and styrene in the mixed feed to below 10 wt%, the exothermic nature of the hydrogenation reaction is significantly reduced, effectively suppressing the formation of gums and heavy polymers. This prevents the rapid increase in pressure drop in the 200-bed section of the hydrogenation reactor and catalyst deactivation, ensuring long-term stable operation of the unit under high load, while improving the selectivity of the target product and the yield of C5 fraction.

[0064] Preferably, in step S1, the reaction pressure of the first-stage hydrogenation reaction is 2.7-2.9 MPaG, and the inlet temperature of the first-stage hydrogenation reactor 200 is 60-80°C. This pressure range is sufficient to maintain the good solubility of hydrogen in the liquid phase and ensure that the diene and hydrogen are in full contact on the catalyst surface. The lower inlet temperature is beneficial to suppress the excessive hydrogenation of monoolefins and the occurrence of side reactions (such as polymerization and cyclization), while reserving a reasonable temperature rise space for the reactor bed to avoid overheating.

[0065] By controlling the reaction pressure at 2.7–2.9 MPaG and limiting the inlet temperature to 60–80 °C, while ensuring efficient and selective hydrogenation of diolefins, the loss of monoolefins and the formation of byproducts are minimized. This not only improves the selectivity and safety of the hydrogenation process but also extends the catalyst lifespan, laying a stable raw material foundation for the subsequent high-yield preparation of saturated C5.

[0066] Preferably, in step S3, the product from the bottom of the second-stage hydrogenation reactor 400 is first cooled to 30–50°C by an air cooler 410 to reduce the partial pressure of the gas phase and promote gas-liquid separation. Then, it enters the second-stage high-pressure separator 420, where unreacted hydrogen and a small amount of light hydrocarbons are separated from the top of the column, while the liquid hydrogenation product is discharged from the bottom of the column. A portion of the liquid phase is sent back to the inlet of the second-stage hydrogenation reactor 400 as a second-stage circulating diluent via the second-stage hydrogen compressor 431 to regulate the feed temperature and reaction intensity, while the other portion is sent to the subsequent desulfurization unit.

[0067] In addition, the separated hydrogen enters the second-stage buffer tank 430 for pressure stabilization and gas-liquid rebalancing. The high-purity hydrogen at the top of the second-stage buffer tank 430 is compressed and then reinjected into the second-stage hydrogenation reactor 400 as circulating hydrogen, thus achieving efficient recovery and utilization of hydrogen.

[0068] This cooling-separation-recirculation system not only effectively recovers unreacted hydrogen and significantly reduces the consumption of fresh hydrogen, but also allows for flexible control of the inlet temperature and reaction heat load of the second-stage hydrogenation reactor 400 by introducing a low-temperature liquid-phase circulating diluent, avoiding bed overheating or catalyst sintering caused by strong exothermic reactions. At the same time, the buffer tank stabilizes the circulating hydrogen pressure and flow rate, ensuring the stability of the second-stage hydrogenation process and the deep deolefin / desulfurization effect, thereby ensuring the high purity and stability of the saturated C5 product.

[0069] Preferably, in step S3, the inlet temperature of the two-stage hydrogenation reactor 400 is 230-300°C. This temperature range is sufficient to activate the hydrogenation reaction of monoolefins and organic sulfides, achieve deep saturation of residual olefins in C5–C8 fractions and effective removal of sulfides (such as thiophenes), while avoiding side reactions such as cracking and coking caused by excessively high temperatures.

[0070] When the bed temperature rise of the second-stage hydrogenation reactor 400 exceeds 70°C (i.e., the reaction is exothermic and there is a risk of runaway temperature), the system automatically uses liquid products from the bottom of the second-stage high-pressure separator 420 at a temperature of 30–40°C as a low-temperature circulating diluent. This product is injected into the feed line of the second-stage hydrogenation reactor 400 through a regulating valve. After mixing with the main feed, it lowers the temperature of the inlet gas / liquid mixture, thereby effectively suppressing the abnormal rise in reactor inlet temperature and maintaining the reaction within a controllable thermodynamic window.

[0071] This temperature-response dilution control mechanism can quickly intervene when the reaction is highly exothermic. By introducing a low-temperature circulating diluent, it actively intervenes in the feed temperature, avoiding catalyst sintering, aggravated side reactions, or equipment overheating caused by excessive temperature rise. It not only significantly improves the operational safety and stability of the two-stage hydrogenation process, but also ensures the quality consistency of saturated C5 products. At the same time, it does not require additional cooling equipment and has the advantages of simple structure, rapid response, and low energy consumption.

[0072] Preferably, in step S4, the liquid-phase hydrogenation product output from the bottom of the second-stage high-pressure separator 420 enters the stripping tower 500. Under the heat provided by the reboiler 710 at the bottom of the tower and the low-pressure operating conditions at the top of the tower, water vapor or its own light components are used as the stripping medium to fully remove hydrogen sulfide and other trace amounts of light acidic gases dissolved in the liquid phase. The removed hydrogen sulfide is discharged from the top of the stripping tower 500 and sent to the sulfur recovery system, while the clean C5–C8 hydrogenated gasoline product obtained from the bottom of the tower does not contain corrosive sulfides and is then transported to the depentanizer tower 600 for the separation of C5 and heavy components.

[0073] The hydrogenation products are subjected to deep desulfurization treatment in stripping tower 500, which effectively removes the hydrogen sulfide generated in the reaction and prevents it from causing equipment corrosion or contaminating saturated C5 products in the subsequent fractionation system. At the same time, it ensures that the material entering the depentanizer tower 600 has high chemical stability and low impurity content, which not only guarantees the quality requirements of saturated C5 as ethylene cracking feedstock, but also improves the storage stability and environmental compliance of hydrogenated gasoline by-products, thereby enhancing the overall safety of the process and the value of the products.

[0074] This invention also provides a system for producing saturated C5 in a cracked gasoline hydrogenation unit, employing the aforementioned method for producing saturated C5 in a cracked gasoline hydrogenation unit, comprising a first-stage hydrogenation reactor 200, a decarbonization tower 300, a second-stage hydrogenation reactor 400, a stripping tower 500, and a depentane tower 600 connected in sequence, wherein...

[0075] A high-pressure separator 210 and a low-pressure separator 220 are installed between a hydrogenation reactor 200 and a decarbonization tower 300.

[0076] A second-stage high-pressure separator 420 and a second-stage buffer tank 430 are installed between the second-stage hydrogenation reactor 400 and the stripping tower 500.

[0077] The system has a reasonable structure and layout, and the equipment configuration and process steps are highly matched. Without adding any large core equipment, it makes full use of the existing framework of the cracked gasoline hydrogenation unit. By optimizing the material flow and adding key separation / buffer units, it has achieved a flexible switch from the traditional "pre-C5 removal" mode to the "full hydrogenation followed by C5 removal" mode.

[0078] It not only ensures the high purity and stability of saturated C5 products, but also improves hydrogen utilization, reduces energy consumption and corrosion risks. Overall, it has the advantages of stable operation, high operational flexibility, and ease of industrial implementation, providing a reliable engineering solution for the high-value utilization of C5 resources in the ethylene industry chain.

[0079] Preferably, this system, based on the core process equipment, is further configured with a complete circulation and reflux auxiliary system:

[0080] The bottom of the high-pressure separator 210 is fed back to the inlet of the hydrogenation reactor 200 via the circulation pump 700, forming a liquid phase circulation dilution system for controlling the feed concentration and reaction temperature rise. The remaining liquid phase is depressurized and then enters the low-pressure separator 220. After removing light components, it is sent to the decarbonization tower 300.

[0081] After being condensed, the vapor phase at the top of the decarbonization tower 300 enters the first buffer tank 310. This tank provides the reflux liquid required for distillation to the top of the tower through a reflux pump, and stably supplies the C5–C8 fraction to the second-stage hydrogenation reactor 400 through a transfer pump.

[0082] A two-stage liquid phase circulation loop is formed between the two-stage hydrogenation reactor 400 and the two-stage high-pressure separator 420 for temperature control. At the same time, hydrogen gas from the top of the two-stage high-pressure separator 420 enters the two-stage buffer tank 430, is compressed, and then returned to the reactor as circulating hydrogen, forming a closed hydrogen circulation system.

[0083] The top of the stripping tower 500 and the depentane tower 600 are respectively equipped with a second buffer tank 510 and a third buffer tank 610, which, together with the circulating pump 700, realize the reflux control of the gas phase condensate to ensure the accuracy of desulfurization and fractionation.

[0084] In addition, reboilers 710 are installed on the circulation pipelines of all main towers (decarbonization tower 300, stripping tower 500, and depentane tower 600) and on the feed pipelines of the first-stage hydrogenation reactor 200 and the second-stage hydrogenation reactor 400 to provide the necessary heat load and ensure the efficient and stable operation of each separation process.

[0085] This system, through the installation of multi-stage buffer tanks, circulating pump 700, and reboiler 710, constructs a sophisticated control network covering the entire process of reaction, separation, reflux, and circulation. This not only achieves efficient recovery and utilization of hydrogen and liquid diluent, significantly reducing raw material and energy consumption, but also greatly improves the purity and yield of saturated C5 products by precisely controlling the reflux ratio, feed temperature, and pressure stability of each unit. Simultaneously, the synergistic effect of the reboiler 710 and the buffer system ensures the stability and anti-fluctuation capability of the fractionation process, giving the entire unit high operational flexibility, strong adaptability, and long-term operational reliability, providing solid technical support for the industrial continuous production of saturated C5.

[0086] The technical means disclosed in this invention are not limited to those described above, but also include technical solutions composed of any combination of the above technical features. The above are specific embodiments of this invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of this invention, and these improvements and modifications are also considered within the scope of protection of this invention.

[0087] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0088] Furthermore, in this invention, the use of terms such as "first," "second," and "a" is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified. The terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two elements or the interaction between two elements, unless otherwise explicitly specified. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0089] The technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0090] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A method for producing saturated C5 in a cracked gasoline hydrotreating unit, characterized in that, include: S1, First-stage hydrogenation reaction: Crude cracked gasoline containing C5 to C9 components and hydrogen are injected into a first-stage hydrogenation reactor. Under preset reaction conditions, a first-stage hydrogenation reaction is carried out to remove diolefins from the cracked crude gasoline and obtain monoolefins and alkanes. S2, C9 separation: The product of the first-stage hydrogenation reactor is separated into gas and liquid and injected into the decarbonization tower for diversion. The bottom of the decarbonization tower produces C9 product, and the top of the tower outputs a product containing C5-C8 components. S3, Second-stage hydrogenation reaction: The product output from the top of the decarbonization tower is injected into the second-stage hydrogenation reactor. Under preset reaction conditions, the second-stage hydrogenation reaction is carried out to remove monoolefins and sulfides, and saturated hydrogenation products are obtained. S4. Product Refining and Separation: After desulfurization, the product from the two-stage hydrogenation reactor is sent to the depentane tower for fractionation. Saturated C5 product is collected at the top of the tower, and hydrogenated gasoline containing C6-C8 components is produced at the bottom of the tower.

2. The method for producing saturated C5 in a cracked gasoline hydrotreating unit according to claim 1, characterized in that, In step S1, the product from the hydrogenation reactor is sequentially separated into a high-pressure separator and a low-pressure separator for gas-liquid separation. Hydrogen separated from the high-pressure separator is discharged from the top of the tower, and liquid products are output from the bottom of the tower. Part of the liquid products are injected into the low-pressure separator, and the other part is returned to the hydrogenation reactor as a circulating diluent. Hydrogen and ammonia separated in a low-pressure separator are discharged from the top of the tower, while the liquid products are injected into the decarbonization tower from the bottom of the tower.

3. A method for producing saturated C5 in a cracked gasoline hydrotreating unit according to claim 2, characterized in that, In step S1, the mixing ratio of crude cracked gasoline and first-stage circulating diluent is controlled so that the total concentration of dienes and styrene in the mixed feed is less than 10 wt%.

4. A method for producing saturated C5 in a cracked gasoline hydrotreating unit according to claim 1, characterized in that, In step S1, the reaction pressure of the first hydrogenation reaction is 2.7-2.9 MPaG, and the inlet temperature of the first hydrogenation reactor is 60-80℃.

5. A method for producing saturated C5 in a cracked gasoline hydrotreating unit according to claim 1, characterized in that, In step S3, the product from the bottom of the two-stage hydrogenation reactor is sequentially cooled by an air cooler and then sequentially injected into the two-stage high-pressure separator and the two-stage buffer tank. The product obtained after hydrogen separation in the second-stage high-pressure separator flows out of the bottom of the tower. Part of it is used for downstream transport, and the other part is returned to the second-stage hydrogenation reactor as a second-stage circulating diluent. The hydrogen separated from the second-stage high-pressure separator flows out from the top of the tower and is injected into the second-stage buffer tank. The hydrogen in the second-stage buffer tank is then injected back into the second-stage hydrogenation reactor as circulating hydrogen.

6. A method for producing saturated C5 in a cracked gasoline hydrotreating unit according to claim 1, characterized in that, In step S3, the inlet temperature of the two-stage hydrogenation reactor is 230-300℃.

7. A method for producing saturated C5 in a cracked gasoline hydrotreating unit according to claim 5, characterized in that, When the bed temperature of the second-stage hydrogenation reactor exceeds 70°C, the second-stage circulating diluent with an output temperature of 30-40°C from the second-stage high-pressure separator is injected into the feed line of the second-stage hydrogenation reactor to control the inlet temperature of the second-stage hydrogenation reactor.

8. A method for producing saturated C5 in a cracked gasoline hydrotreating unit according to claim 1, characterized in that, In step S4, the product separated from the second-stage high-pressure separator is desulfurized by a stripping tower. Hydrogen sulfide is discharged from the top of the stripping tower, and the hydrogenated gasoline product containing C5-C8 components collected from the bottom of the tower is transported to the depentane tower.

9. A system for producing saturated C5 in a cracked gasoline hydrogenation unit, employing the method for producing saturated C5 in a cracked gasoline hydrogenation unit as described in any one of claims 1-8, characterized in that, It includes a first-stage hydrogenation reactor, a nine-stage decarbonization tower, a second-stage hydrogenation reactor, a stripping tower, and a depentane removal tower connected in sequence. A high-pressure separation tank and a low-pressure separation tank are installed between the hydrogenation reactor and the decarbonization tower. A two-stage high-pressure separator and a two-stage buffer tank are installed between the two-stage hydrogenation reactor and the stripping tower.

10. A system for producing saturated C5 in a cracked gasoline hydrogenation unit according to claim 9, characterized in that, A high-pressure separator is connected to a hydrogenation reactor via a circulation pump to form a circulation system. The high-pressure separator is connected to a low-pressure separator, and the low-pressure separator is connected to the decarbonization tower. The top of the decarbonization tower is connected to a first buffer tank, which is connected to the top of the decarbonization tower via a circulation pump. The first buffer tank is also connected to the second-stage hydrogenation reactor via a circulation pump. The two-stage hydrogenation reactor and the two-stage high-pressure separator are connected to form a two-stage circulation system. The two-stage high-pressure separator is also connected to the stripping tower. The two-stage hydrogenation reactor, the two-stage high-pressure separator, and the two-stage buffer tank are connected to form a two-stage hydrogen circulation system. A second buffer tank is connected to the top of the stripping tower, and the second buffer tank is connected to the top of the stripping tower via a circulating pump; The top of the depentanizer is connected to a third buffer tank, which is connected to the top of the depentanizer via a circulating pump. Reboilers are installed on the circulation lines at the bottom of the decarbonization tower, stripping tower, and depentane tower, as well as on the feed lines of the first-stage hydrogenation reactor and the second-stage hydrogenation reactor.

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