A core gradient temperature-controlled sulfur recovery system and method

Abstract

The application discloses a core gradient temperature control sulfur recovery system and method, which comprises: a first reactor, in which an upper adiabatic catalytic reaction zone and a lower isothermal catalytic reaction zone are sequentially arranged; the lower isothermal catalytic reaction zone controls the reaction temperature to be lower than the upper zone through an embedded heat extraction device; a second reactor, in which a Claus reaction zone and a hydrogenation reaction zone are arranged; the Claus reaction zone controls the reaction temperature to be lower than the lower isothermal catalytic reaction zone of the first reactor and higher than the sulfur dew point temperature; a third reactor, which is an adiabatic oxidation reactor; a dynamic temperature control unit, which is based on a thermodynamic equilibrium nonlinear model of sulfur vapor partial pressure and sulfur dew point temperature, on-line monitors the sulfur vapor partial pressure at the outlet of the lower section of the first reactor, calculates the sulfur dew point temperature in real time, and dynamically adjusts the heat extraction amount of the embedded heat extraction device, so that the temperature of the lower isothermal catalytic reaction zone is always higher than the real-time sulfur dew point temperature. In this way, a balance between high sulfur recovery rate and long-period stable operation is achieved.

Description

Technical Field

[0001] This invention relates to sulfur recovery technology, and more particularly to a sulfur recovery system and method based on core gradient temperature control technology. Background Technology

[0002] In petroleum refining, natural gas purification, and coal chemical processes, the resulting acidic gases contain large amounts of hydrogen sulfide (H2S). The Claus process is currently the most important industrial technology for treating H2S-containing acidic gases and recovering elemental sulfur. Traditional sulfur recovery processes typically employ two or three catalytic reactors connected in series. In this process, H2S and SO2 in the gas undergo the Claus main reaction (2H2S + SO2) under the action of a catalyst. 3S + 2H2O) produces elemental sulfur.

[0003] However, the traditional Claus process also has some inherent drawbacks. For example, the bed temperature of a traditional first-stage Claus reactor is usually controlled at 310℃~320℃. The main basis for setting this temperature is to achieve two objectives: first, to improve the reaction kinetic efficiency, as higher temperatures can significantly accelerate the forward reaction rate of the Claus main reaction and shorten the time required to reach chemical equilibrium; second, to promote the hydrolysis and conversion of organic sulfur compounds (such as COS and CS2) into H2S before they participate in the main reaction.

[0004] However, the Claus main reaction is exothermic and reversible. According to Le Chatelier's principle, lowering the temperature is beneficial to increasing the equilibrium conversion rate. Therefore, traditional single-stage reactors face a trade-off between "high-temperature hydrolysis" and "low-temperature high conversion rate," resulting in limited single-stage conversion. Correspondingly, traditional two-stage Claus reactors typically control the reaction temperature between 240℃ and 260℃ to satisfy the requirement that lower reaction temperatures are beneficial for increasing conversion while avoiding excessively low temperatures that could cause sulfur vapor in the process gas to condense into liquid sulfur, clogging catalyst micropores or covering active sites, leading to catalyst deactivation. Through this design, the final total sulfur recovery rate of traditional three-stage Claus processes is typically ≤97%.

[0005] To address this, existing technologies have proposed a sub-dewpoint sulfur recovery process, which aims to reduce the reaction temperature to below the sulfur dew point (typically around 160°C) so that sulfur vapor can be condensed and adsorbed in the catalyst pores, thereby shifting the Claus reaction equilibrium to the positive direction and increasing the sulfur recovery rate to a maximum of approximately 99.5%.

[0006] However, in practical applications, this process still has some significant drawbacks, such as sulfur blockage and catalyst deactivation: because the operating temperature is lower than the sulfur dew point, sulfur vapor in the gas phase continues to condense and deposit in the catalyst micropores, causing catalyst pore blockage and active sites to be covered. The catalyst life is usually less than 24 months, requiring frequent reactor switching for regeneration. The operation fluctuates greatly, and the three-way or four-way rotary valve is easily damaged.

[0007] Therefore, in the existing technologies, although the sub-dew point process improves the sulfur recovery rate, it comes at the cost of short catalyst life, complex equipment, high investment, and difficult maintenance; while the traditional three-stage Claus process, although relatively simple in process, has a low sulfur recovery rate.

[0008] Therefore, designing a sulfur recovery process that can both improve sulfur recovery rate and ensure long-term stable operation is a difficult problem in this field. Summary of the Invention

[0009] Therefore, the main objective of this invention is to provide a sulfur recovery system and method with core gradient temperature control, so as to achieve a balance between high sulfur recovery rate and long-term stable operation.

[0010] To achieve the above objectives, according to one aspect of the present invention, a core gradient temperature-controlled sulfur recovery system is provided, comprising: a primary reactor, a secondary reactor, a tertiary reactor, and a sulfur condenser, wherein the primary reactor is a combined reactor, and an upper adiabatic catalytic reaction zone and a lower isothermal catalytic reaction zone are sequentially arranged along the process gas flow direction inside the primary reactor; the upper adiabatic catalytic reaction zone is used for organic sulfur hydrolysis and Claus reaction, and the lower isothermal catalytic reaction zone has its reaction temperature controlled by an embedded heat extraction device to be lower than that of the upper zone and always higher than the real-time sulfur dew point temperature;

[0011] The secondary reactor is a composite reactor, in which a Claus reaction zone and a hydrogenation reaction zone are arranged sequentially along the flow direction of the process gas. The Claus reaction zone controls the reaction temperature to be lower than that of the isothermal catalytic reaction zone in the lower section of the primary reactor and higher than the sulfur dew point temperature. The hydrogenation reaction zone is used to reduce the residual SO2 in the process gas to elemental sulfur under the action of a catalyst.

[0012] The third-stage reactor is an adiabatic oxidation reactor, used to oxidize residual H2S into elemental sulfur;

[0013] The system also includes a dynamic temperature control unit, which monitors the sulfur vapor partial pressure at the outlet of the lower section of the first-stage reactor online based on a nonlinear thermodynamic equilibrium model of sulfur vapor partial pressure and sulfur dew point temperature, calculates the sulfur dew point temperature in real time, and dynamically adjusts the heat output of the embedded heat extraction device so that the temperature of the lower isothermal catalytic reaction zone is always higher than the real-time sulfur dew point temperature.

[0014] In a possible preferred embodiment, the upper adiabatic catalytic reaction zone of the primary reactor is controlled at a reaction temperature of 310℃~320℃, and the lower isothermal catalytic reaction zone is controlled at a reaction temperature of 240℃~260℃, always 8℃~15℃ higher than the sulfur dew point temperature; the inlet temperature of the upper Claus reaction zone of the secondary reactor is controlled at 185℃~195℃, the bed temperature is controlled at 200℃~220℃, and the temperature of the lower hydrogenation reaction zone is controlled at 200℃~210℃.

[0015] In a possible preferred embodiment, the thermodynamic equilibrium nonlinear model is:

[0016]

[0017] in This is the vapor pressure of sulfur. For temperature;

[0018] The sulfur dew point temperature is determined using the following iterative method:

[0019] Calculate the partial pressure of sulfur ,in The absolute total pressure of the bed in the isothermal section. This refers to the concentration of sulfur vapor.

[0020] Define a function: Given an initial temperature Iterate through the values ​​until the error between two consecutive iterations is less than 0.1K. The converged solution is the sulfur dew point temperature. Converted to Celsius The target bed temperature is set to ,in .

[0021] In a possible preferred embodiment, the embedded heat extraction device adopts a heat exchange tube structure with uneven gaps and a feedwater evaporator based on water circulation to achieve a uniform temperature distribution across the reactor cross-section.

[0022] In a possible preferred embodiment, the sulfur condenser includes: a secondary sulfur condenser disposed on the outlet pipe of the primary reactor, a tertiary sulfur condenser disposed on the outlet pipe of the secondary reactor, and a quaternary sulfur condenser disposed on the outlet pipe of the tertiary reactor; the secondary, tertiary, and quaternary sulfur condensers adopt an integrated structure with the same shell, and the outlet gas phase temperatures are controlled by progressive cryogenic control to be approximately 130°C, approximately 130°C, and approximately 125°C, respectively.

[0023] In a possible preferred embodiment, the sulfur recovery system further includes a tail gas treatment unit, comprising: a tail gas collector, a thermal incinerator, a waste heat recovery unit, and a flue gas desulfurization device arranged sequentially. The tail gas collector is connected to a final-stage sulfur condenser, receiving tail gas and processing it sequentially before passing it on. The flue gas desulfurization device includes a packed quench tower and a dry adsorption tower. The quench tower receives the sulfur-producing tail gas, reduces its temperature from approximately 240°C to approximately 70°C, and removes approximately 2 / 3 of the moisture before feeding it into the dry adsorption tower, which is filled with a desulfurizing agent with a sulfur capacity ≥ 25 wt%.

[0024] In a possible preferred embodiment, the upper adiabatic catalytic reaction zone of the primary reactor is filled with a hydrolysis catalyst to hydrolyze COS and CS2 in the raw acid gas into H2S, and the lower isothermal catalytic reaction zone is filled with a Claus catalyst.

[0025] In a possible preferred embodiment, the upper Claus reaction zone of the secondary reactor is filled with an Al-based or Ti-based Claus catalyst, and the lower hydrogenation reaction zone is filled with a Co-Mo-based hydrogenation catalyst.

[0026] To achieve the above objectives, corresponding to the above-described system, according to another aspect of the present invention, a sulfur recovery method with core gradient temperature control is also provided for controlling any of the sulfur recovery systems described above, the steps of which include:

[0027] Step S1 introduces the process gas into the primary reactor, which then passes through the upper adiabatic catalytic reaction zone and the lower isothermal catalytic reaction zone in sequence. The upper adiabatic catalytic reaction zone is controlled to carry out organic sulfur hydrolysis and Claus reaction at 310℃~320℃. The lower isothermal catalytic reaction zone is controlled to extract heat through an embedded heat extraction device, so that the reaction temperature is lower than that of the upper adiabatic catalytic reaction zone and maintained at 240℃~260℃, and is always higher than the real-time sulfur dew point temperature by 8℃~15℃.

[0028] Step S2 involves introducing the process gas flowing out of the primary reactor into the secondary sulfur condenser and cooling it to about 130°C to separate elemental sulfur. After that, the gas is heated by the secondary reheater and kept at 185°C~195°C before being introduced into the secondary reactor. The gas then undergoes a low-temperature Claus reaction maintained at 200°C~220°C and a hydrogenation reduction reaction maintained at 200°C~210°C to convert the sulfides in the process gas into elemental sulfur.

[0029] Step S3: The process gas flowing out of the secondary reactor is introduced into the tertiary sulfur condenser and cooled to about 130°C to separate elemental sulfur. After being heated by the tertiary reheater, it is introduced into the tertiary reactor. An oxidant is added to cause the residual H2S to undergo an oxidation reaction at an inlet temperature of about 200°C, which oxidizes the residual sulfide into elemental sulfur. The outlet tail gas temperature is controlled at about 220°C.

[0030] Step S4 introduces the process gas flowing out of the three-stage reactor into the four-stage sulfur condenser for cooling and separation of elemental sulfur, and controls the outlet gas phase temperature at 125°C through deep cooling.

[0031] Step S5 is based on the thermodynamic equilibrium nonlinear model of sulfur vapor partial pressure and sulfur dew point temperature. The sulfur vapor partial pressure at the outlet of the lower isothermal catalytic reaction zone is monitored online, the sulfur dew point temperature is calculated in real time, and the heat output of the embedded heat extraction device is dynamically adjusted so that the temperature of the lower isothermal catalytic reaction zone is always higher than the real-time sulfur dew point temperature.

[0032] In a possible preferred embodiment, the method further includes an exhaust gas treatment step:

[0033] Step S6 involves introducing the tail gas from the outlet of the final-stage sulfur condenser into a tail gas trap for treatment. After sequential processing through a thermal incinerator and a waste heat recovery unit, the gas is then fed into a quench tower. The tail gas temperature is reduced from approximately 240°C to approximately 70°C, and about two-thirds of the moisture is removed. The gas is then fed into a dry adsorption tower, where residual SO2 is adsorbed and removed by activated carbon-based and metal oxide-based desulfurizing agents until the SO2 emission concentration is <50-100 mg / m³. 3 The emissions will be discharged later (this can be adjusted according to the local SO2 emission concentration requirements).

[0034] The sulfur recovery system and method with core gradient temperature control provided by this invention, at the structural level, proposes a "dual-zone coupled structure" of a single-stage combined reactor. The upper section meets the requirements of high-temperature hydrolysis and reaction kinetics of COS / CS2, while the lower section supports precise heat transfer control through an embedded heat extraction device, enabling the reaction to proceed at low temperatures to push the Claus equilibrium towards the positive direction. This achieves both high-temperature hydrolysis and high-conversion rate at low temperatures, resolving the contradiction between "high-temperature organic sulfur hydrolysis" and "high-equilibrium conversion rate at low temperatures" in traditional single-stage reactors (e.g., traditional single-stage reactors need to operate at 310~320℃ to ensure hydrolysis rate and reaction rate, but high temperatures are not conducive to thermodynamic equilibrium). This results in a total sulfur recovery rate of up to 99.8%, second only to the Scott (SCOT) process's 99.96%, and far exceeding the traditional three-stage Claus process (≤97%) and sub-dew point process (approximately 99~99.5%), achieving an ultra-high sulfur recovery rate.

[0035] Meanwhile, regarding the control aspect of the corresponding structural scheme: This project establishes for the first time a nonlinear thermodynamic equilibrium model based on sulfur vapor partial pressure and sulfur dew point temperature. This model supports dynamic adjustment of the heat extraction device embedded in the first-stage reactor by monitoring sulfur vapor concentration and iteratively calculating the real-time sulfur dew point. This ensures that the lower-stage bed temperature is consistently and precisely maintained within the subcritical range above the real-time sulfur dew point temperature, thereby solving the problems of sulfur blockage, catalyst deactivation, and frequent switching and regeneration caused by operating below the sulfur dew point in sub-dew point processes. This approach abandons the traditional sub-dew point approach, maintaining the bed temperature above the sulfur dew point through dynamic temperature control to avoid sulfur condensation and blockage. Therefore, the design eliminates the switching losses of three-way / four-way valves, eliminates the need for periodic regeneration, and significantly extends catalyst life, enabling long-term continuous and stable operation. Attached Figure Description

[0036] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0037] Figure 1 This is a schematic diagram of the core gradient temperature control sulfur recovery system of the present invention;

[0038] Figure 2 This is a partially enlarged structural diagram of the primary reactor section in the sulfur recovery system of the present invention;

[0039] Figure 3 This is a schematic diagram of a half-section of the primary reactor in the sulfur recovery system of the present invention;

[0040] Figure 4 This is a top-view cross-sectional view of the primary reactor in the sulfur recovery system of the present invention.

[0041] Figure 5 This is a schematic diagram of the unfolded structure of the inner and outer cylinders in the primary reactor of the sulfur recovery system of the present invention;

[0042] Figure 6 This is a schematic diagram of the disassembled structure of the heat recovery coil group in the primary reactor of the sulfur recovery system of the present invention, wherein the three heat recovery coil groups A, B and C can be added or removed in combination according to process requirements;

[0043] Figure 7 This is a schematic diagram of the steps of the sulfur recovery method with core gradient temperature control of the present invention.

[0044] Explanation of reference numerals in the attached figures

[0045] 1. Sulfur production furnace and waste heat boiler skid-mounted; 2. Primary sulfur condenser; 3. Primary reheater; 4. Primary reactor; 5. Sulfur vapor concentration analyzer; 6. Liquid pump; 7. Steam air cooler; 8. Reflux tank; 9. Secondary reactor; 101. Secondary sulfur condenser; 102. Tertiary sulfur condenser; 103. Quaternary sulfur condenser; 11. Secondary reheater; 12. Tertiary reheater; 13. Tertiary reactor; 14. Tail gas trap; 15. Liquid sulfur pool; 16. Thermal incinerator; 17. Waste heat recovery unit; 18. Flue gas desulfurization device; 19. Fan; 401. Adiabatic catalytic reaction zone; 402. Isothermal catalytic reaction zone; 403. Heat extraction coil assembly; 404. Outer cylinder; 405. Inner cylinder; 406. Outer shell; 407. External insulation layer; 408. Process gas inlet; 409. Process gas outlet; 410. Manhole; 411. Conical baffle; 412. 413 Three-way heat absorber outlet, 414 Three-way heat absorber inlet, 415 Lower support for heat exchange coil, 416 Nitrogen purging inlet, 417 Limiting plate, 418 Discharge hole, 419 Liquid sulfur outlet, 410 Ceramic ball packing, 420 Upper support for heat exchange coil, 421 Packing platform, 422 Packing seal, 423 Baffle plate, 424 Maintenance flange, 425 High-temperature nitrogen purging outlet, 426 Catalyst filling port, 427 Catalyst, 428 Inlet channel, 4031 First heat exchange coil, 4121 First heat absorber outlet, 4131 First heat absorber inlet, 4032 Second heat exchange coil, 4122 Second heat absorber outlet, 4132 Second heat absorber inlet, 4033 Third heat exchange coil, 4123 Third heat absorber outlet, 4133 Third heat absorber inlet. Detailed Implementation

[0046] To enable those skilled in the art to better understand the technical solutions of the present invention, the specific technical solutions of the present invention will be clearly and completely described below in conjunction with embodiments, so as to help those skilled in the art further understand the present invention. Obviously, the embodiments described in this application are merely some embodiments of the present invention, and not all embodiments. It should be noted that, for those skilled in the art, the embodiments and features in the embodiments of this application can be combined with each other without departing from the concept of the present invention and without conflict. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the disclosure and protection scope of the present invention.

[0047] Furthermore, the terms "first," "second," "S1," "S2," etc., used in the specification, claims, and drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such features can be interchanged where appropriate so that embodiments of the invention described herein can be implemented in orders other than those described herein. At the same time, the stages described in each step are not necessarily to be implemented in the same step; it should be understood that the implementation order of the contents of each step stage can be adjusted and interchanged without violating the inventive concept, so that embodiments of the invention described herein can be implemented in orders other than those described herein. Additionally, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. Unless otherwise expressly specified and limited, the terms "set," "arrange," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; a mechanical connection or an electrical connection; a direct connection or an indirect connection through an intermediate medium; or a connection within two elements. Those skilled in the art can understand the specific meaning of the above terms in this case based on the specific circumstances and in conjunction with existing technology.

[0048] To achieve a balance between high sulfur recovery rates and long-term stable operation, such as Figures 1 to 3 As shown, this invention provides a sulfur recovery system with core gradient temperature control, wherein the overall structure and corresponding process flow of the system are illustrated below:

[0049] like Figure 1 As shown, the incoming acidic gas first enters the sulfur-making furnace and waste heat boiler skid 1. Through partial combustion in the sulfur-making furnace, about 1 / 3 of the H2S is converted into SO2, generating a high-temperature process gas containing H2S, SO2, H2O and a small amount of organic sulfur.

[0050] The high-temperature process gas recovers high-grade heat energy through a waste heat boiler, producing medium-pressure steam as a byproduct. After cooling, it enters the first-stage sulfur condenser 2, where the process gas is further cooled by a shell-and-tube sulfur cooler, causing some of the elemental sulfur in the gas phase to condense and liquefy. The separated liquid sulfur flows by gravity through the liquid sulfur seal and finally flows into the liquid sulfur pool 15, reducing the sulfur load of subsequent reactors.

[0051] The process gas flowing out of the first-stage sulfur condenser 2 enters the first-stage reheater 3, and after being heated by steam or other heat sources, it is introduced into the first-stage reactor 4.

[0052] Among them, such as Figure 3As shown, the primary reactor 4 in this example is a single vertical combined reactor. Its outer shell 406 is provided with an external insulation layer 407. Inside the outer shell 406, an inner cylinder 405 and an outer cylinder 404 are arranged in an axial ring at intervals, defining an upper adiabatic catalytic reaction zone 401 and a lower isothermal catalytic reaction zone 402 sequentially from top to bottom within the space between them. A conical baffle 411 is provided at the junction of the upper and lower sections. The top of the catalytic reaction zone is connected to the catalyst filling port 426 for catalyst loading. The bottom of the isothermal catalytic reaction zone 402 is connected to the discharge port 417. In the operating state, the bottom is sealed with ceramic ball packing 419. The inner cylinder 405 and outer cylinder 404 are as follows... Figure 5 The cylinder wall shown is densely covered with vent holes except for the baffle plate 423 and the ceramic ball area, so that the gas can enter the catalyst evenly. The bottom of the inner cylinder 405 is connected to the liquid sulfur outlet 418. The outer cylinder 404 and the inner wall of the outer shell 406 are arranged at intervals to define the gas outlet. The shell is provided with a process gas inlet 408 and a process gas outlet 409 that are connected to the gas outlet.

[0053] Among them, such as Figures 2 to 4 As shown, an embedded heat exchange device is provided in the lower isothermal catalytic reaction zone 402. This embedded heat exchange device employs a non-uniform gap heat exchange tube structure and a water-circulating feedwater evaporator to achieve uniform temperature distribution across the reactor cross-section. In this example, the embedded heat exchange device includes: a heat exchange coil assembly 403, a liquid pump 6, a steam air cooler 7, and a reflux tank 8. The heat exchange coil assembly 403 is fixedly embedded in the isothermal catalytic reaction zone 402 by heat exchange coil upper / lower supports 414 and 420 located on the inner wall of the outer cylinder 404. Figure 4 , Figure 6 As shown, in a preferred embodiment, the heat exchange coil assembly 403 consists of a first heat exchange coil 4031, a second heat exchange coil 4032, and a third heat exchange coil 4033 of different diameters, which are nested together at intervals to uniformly distribute them within the isothermal catalytic reaction zone 402 and contact the catalyst 427 packing for heat exchange, ensuring temperature control accuracy and speed. Figure 4 Each heat exchange coil shown can be connected in series with the liquid pump 6, steam air cooler 7, and reflux tank 8 through the combined three heat absorption medium inlets / outlets 412 and 413 to form a temperature control loop; alternatively, each heat exchange coil can be equipped with corresponding first, second, and third heat absorption medium inlets / outlets 4121, 4131, 4122, 4132, 4123, and 4133, which can be connected in series with the liquid pump 6, steam air cooler 7, and reflux tank 8 to form a temperature control loop, so as to support individual or group control of each heat exchange coil to meet the actual temperature fluctuation requirements.

[0054] Furthermore, in alternative implementations, such as Figure 6As shown in A / B / C, individual heat exchange coils of different diameters can also be designed according to the temperature control requirements of the actual project. These coils can be arranged separately in the isothermal catalytic reaction zone 402 and connected in series with the return water pump 6, steam air cooler 7, and reflux tank 8 to form a temperature control loop. It can be seen that the present invention does not limit the number or diameter of the heat exchange coils. Those skilled in the art can design the diameter of each heat exchange coil according to the actual project requirements and implement them in a single or multiple nested manner.

[0055] Furthermore, the upper adiabatic catalytic reaction zone 401 is, for example, filled with a TiO2-based hydrolysis catalyst, and the bed operating temperature is maintained at 310℃~320℃. In this zone, COS and CS2 in the acidic gas undergo hydrolysis to convert into H2S, while H2S reacts with SO2 in a Claus main reaction to generate elemental sulfur. Experiments show that the COS / CS2 hydrolysis rate in this zone is >95%.

[0056] The process gas continues its downward flow into the next isothermal catalytic reaction zone 402. This zone is typically filled with an Al2O3-based Claus catalyst. The bed utilizes a non-uniformly spaced heat exchanger coil structure, based on a water-circulating feedwater evaporator principle, controlling heat extraction by adjusting the circulating water flow. Under dynamic temperature control, the temperature in this zone is precisely maintained at 240℃~260℃, consistently 8℃~15℃ higher than the real-time sulfur dew point. Because the reaction temperature is approximately 60℃~70℃ lower than the conventional first-stage reactor 4's 310℃~320℃, the Claus reaction equilibrium shifts significantly towards the formation of elemental sulfur. This stage reactor achieves an overall sulfur conversion rate approximately 1% higher than the conventional process, with an H2S conversion rate >75%.

[0057] The process gas exiting the primary reactor 4 enters the secondary sulfur condenser 101. The secondary sulfur condenser 101 adopts a shell-and-tube structure, with process gas flowing through the shell side and cooling water flowing through the tube side. A 0.1 MPaG low-pressure steam is produced as a byproduct, cooled by air, and then recycled. The condenser outlet gas phase temperature is controlled at approximately 130°C by adjusting the air-cooled frequency converter. This is about 30°C lower than the conventional process's 160°C outlet temperature at the same location, allowing more gaseous sulfur in the process gas to liquefy and separate. The liquid sulfur flows into the liquid sulfur pool 15, further reducing the sulfur partial pressure in the outlet gas phase.

[0058] The process gas, cooled by the secondary sulfur condenser 101, is heated by the secondary reheater 11 and then enters the secondary reactor 9. The secondary reactor 9 is a single vertical composite reactor, internally divided axially from top to bottom into an upper Claus reaction zone and a lower hydrogenation reaction zone. The upper Claus reaction zone is, for example, filled with a Ti-based Claus catalyst. The inlet process gas temperature is controlled at 185~195℃, 15~25℃ lower than the conventional inlet reaction temperature, and the bed temperature is controlled at 200℃~210℃. Due to the increased overall conversion rate of the preceding primary reactor 4, more elemental sulfur has been separated in the secondary sulfur condenser 101, resulting in a lower partial pressure of elemental sulfur in the gas phase entering the secondary reactor 9 and a corresponding decrease in the sulfur dew point temperature. Therefore, this stage can operate safely at a lower temperature without sulfur condensation blockage. Low-temperature operation further shifts the chemical equilibrium towards sulfur formation, increasing the overall sulfur conversion rate of this stage reactor by approximately 0.5% compared to the conventional process.

[0059] In the lower hydrogenation reaction zone, a Co-Mo based hydrogenation catalyst is loaded, and the reaction temperature is controlled at 200℃~210℃. Under the action of the catalyst, SO2 in the process gas that has not participated in the Claus reaction undergoes a selective hydrogenation reduction reaction with H2 in the process gas: SO2 + 2H2 → S + 2H2O, directly reducing SO2 to elemental sulfur and further reducing the SO2 content in the process gas.

[0060] The process gas exiting the secondary reactor 9 enters the tertiary sulfur condenser 102. The tertiary sulfur condenser 102 produces 0.1 MPaG steam as a byproduct, and the outlet gas phase temperature is controlled at 130°C.

[0061] The process gas, cooled by the three-stage sulfur condenser 102, is heated by the three-stage reheater 12 and then enters the three-stage reactor 13. The three-stage reactor 13 is an adiabatic oxidation reactor, typically packed with an Fe-Si-Ti oxidation catalyst. A suitable amount of air is introduced into the process gas to cause the residual H2S to undergo an oxidation reaction at an inlet temperature of approximately 200°C: 2H2S + O2 → 2S + 2H2O. The bed temperature rises by approximately 10°C to 20°C due to the exothermic reaction, and the outlet temperature is approximately 220°C. The H2S conversion rate in this stage is >95%.

[0062] The process gas flowing out of the tertiary reactor 13 enters the quaternary sulfur condenser 103 for cooling, and produces 0.1 MPaG steam as a byproduct. After being cooled by air, it is recycled. By adjusting the air-cooled frequency converter, i.e., deep cooling, the outlet gas phase temperature is controlled at 125°C to minimize the sulfur partial pressure in the gas phase, so that more elemental sulfur is liquefied and separated, and the liquid sulfur flows into the liquid sulfur pool 15.

[0063] In a preferred embodiment, the secondary sulfur condenser 101, tertiary sulfur condenser 102, and quaternary sulfur condenser 103 preferably adopt an integrated structure with the same shell, combining the three condensers into a single horizontal combined unit. A partition plate is installed inside the shell to form independent chambers. The outlet gas phase temperature of each condenser decreases progressively (130℃→130℃→125℃), achieving progressive deep cooling.

[0064] The exhaust gas after being treated by the four-stage sulfur condenser 103 enters the exhaust gas treatment unit for further treatment. In this example, the exhaust gas treatment unit includes: exhaust gas collector 14, thermal incinerator 16, waste heat recovery unit 17, and flue gas desulfurization device 18. Specifically, the exhaust gas after being treated by the four-stage sulfur condenser 103 first enters the exhaust gas collector 14 to capture sulfur mist and trace amounts of liquid sulfur droplets entrained in the gas phase, preventing them from entering the downstream incinerator and causing unstable combustion or sulfur accumulation and blockage.

[0065] The captured exhaust gas enters the thermal incinerator 16, where excess air is introduced. At a high temperature of approximately 650℃~800℃, the remaining sulfur-containing compounds such as H2S, COS, and CS2 are completely oxidized into SO2, ensuring that sulfur elements enter the downstream flue gas system in the form of SO2, thus eliminating odor and toxic gas emissions.

[0066] The high-temperature flue gas after incineration (approximately 700°C) enters the waste heat recovery unit 17 (such as a waste heat boiler for tail gas incinerators) to recover the sensible heat of the flue gas and produce medium / low-pressure steam as a byproduct, while the flue gas temperature drops to approximately 240°C.

[0067] The cooled flue gas enters the flue gas desulfurization unit 18. In this example, the flue gas desulfurization unit 18 adopts an integrated design of a quench tower and a dry adsorption tower: the flue gas first passes through the quench tower, where it undergoes direct heat exchange with circulating water, reducing its temperature from approximately 240℃ to approximately 70℃ and removing approximately 2 / 3 of the moisture, providing dry conditions for dry adsorption; the cooled and dehydrated flue gas then enters the dry adsorption tower, where residual SO2 is adsorbed and removed by activated carbon-based desulfurizing agents and metal oxide-based desulfurizing agents (sulfur capacity ≥ 25wt%), ensuring that the SO2 emission concentration is < 50-100 mg / m³. 3 The flue gas is then discharged externally (the amount can be adjusted according to the regional SO2 emission concentration requirements). Finally, the purified flue gas is discharged through a chimney after meeting emission standards. In other optional embodiments, the flue gas desulfurization device 18 can also employ a traditional wet desulfurization scheme, which will not be elaborated upon in this embodiment; those skilled in the art can implement it based on existing schemes.

[0068] Through the above process, the total sulfur recovery rate of the system in this embodiment can actually reach 99.8%, thereby reducing the SO2 concentration entering the tail gas treatment unit to a low level, so that the SO2 concentration in the flue gas exiting the terminal tail furnace (thermal incinerator 16) reaches approximately 300 mg / m³. 3 ~800mg / m 3This significantly reduces the processing load of the dry adsorption tower, greatly extending the desulfurizer replacement cycle. After passing through the dry adsorption tower, the concentration can be reduced to <100 mg / m³. 3 (In special areas, SO2 emission concentration should be <50mg / m³ according to local standards) 3 It meets the emission standards of GB31570 / GB31571-2015, and the entire exhaust gas treatment process uses dry desulfurization, which can achieve zero wastewater and zero alkali consumption, thus achieving zero waste liquid discharge.

[0069] In addition, the liquid sulfur collected in the liquid sulfur pool 15 and separated by the condensers at each stage can be degassed and filtered before being formed into commercial sulfur by the sulfur forming device.

[0070] Furthermore, in order to achieve dynamic temperature control of the isothermal catalytic reaction zone 402 in the lower section of the first-stage reactor 4 by controlling the embedded heat exchanger through the dynamic temperature control unit, this invention designs a nonlinear thermodynamic equilibrium model based on sulfur vapor partial pressure and sulfur dew point temperature to monitor the sulfur vapor partial pressure at the outlet of the lower section of the first-stage reactor 4 online, calculate the sulfur dew point temperature in real time, and dynamically adjust the heat exchanger of the embedded heat exchanger so that the temperature of the lower section isothermal catalytic reaction zone 402 is always higher than the real-time sulfur dew point temperature.

[0071] Specifically, in a preferred embodiment, an online sulfur vapor concentration analyzer 5 (such as an ultraviolet spectrophotometer or gas chromatograph) and a pressure transmitter can be installed on the outlet pipeline of the lower isothermal catalytic reaction zone 402 of the first-stage reactor 4 to monitor the sulfur vapor concentration in the process gas in real time. (vol%) and gauge pressure (kPaG).

[0072] Step 1: Calculate the partial pressure of sulfur

[0073] Total absolute pressure:

[0074]

[0075] Sulfur partial pressure:

[0076]

[0077] Step 2: Establish a model for calculating sulfur dew point temperature

[0078] Based on the thermodynamic equilibrium relationship between sulfur vapor pressure and temperature, the following nonlinear equation is used.

[0079] Formula①

[0080] in This is the sulfur vapor pressure (Pa). For temperature;

[0081] Step 3: Iteratively solve for the sulfur dew point temperature

[0082] Define the iteration function:

[0083]

[0084] Let f(T) = 0, then ,in

[0085] Given P (Pa) and an initial temperature T0, substitute into the above equation to obtain T1. Substitute again until the error between Tn and Tn+1 is within 0.1K. The convergent solution is the sulfur dew point temperature. Converted to Celsius .

[0086] Step 4: Set the target bed temperature

[0087] The target bed temperature is set to ,in (In conventional techniques, Δt is directly set to above 30°C, which leads to a significant decrease in reaction efficiency.)

[0088] Example calculation:

[0089] Assuming that the following has been measured using a remote analysis instrument in the field:

[0090] gauge pressure sulfur vapor concentration .

[0091] Set a safety margin:

[0092] but:

[0093] Total absolute pressure:

[0094] Sulfur partial pressure: ;

[0095] Will Substitute into formula ①:

[0096]

[0097] Iterative solution for temperature T:

[0098]

[0099] Through iterative solutions, the solution eventually converges to:

[0100]

[0101] The sulfur dew point temperature is:

[0102]

[0103] Target bed temperature:

[0104]

[0105] Step 5: Nonlinear heat extraction regulation logic

[0106]

[0107]

[0108]

[0109] The dynamic temperature control unit will use the above calculations. As the temperature setpoint for the lower isothermal catalytic reaction zone 402, and the actual bed temperature The PID comparison calculation is performed, and the output signal adjusts the circulating water flow rate or pressure of the embedded heat exchanger, thereby changing the total heat output Q.

[0110] When sulfur partial pressure is detected online When the temperature rises, the sulfur dew point temperature The temperature rises accordingly, at which point the heat extraction Q is automatically reduced (e.g., by reducing the circulating water flow rate) to lower the bed temperature. Elevate the temperature to ensure it remains above the new sulfur dew point and prevent sulfur vapor condensation.

[0111] When sulfur partial pressure When the temperature decreases, the sulfur dew point temperature When the temperature drops, the heat extraction Q is automatically increased to raise the bed temperature. To reduce and maximize the equilibrium conversion rate of the Claus reaction.

[0112] Through the above closed-loop control, the temperature of the isothermal catalytic reaction zone 402 in the lower section of the first-stage reactor 4 can be stably controlled at around 250℃, with a temperature control accuracy of ±2℃, which is always more than 10℃ higher than the real-time sulfur dew point temperature, effectively avoiding sulfur condensation blockage and catalyst deactivation.

[0113] On the other hand, corresponding to the above example of a sulfur recovery system, such as Figure 7 As shown, the present invention also provides a sulfur recovery method with core gradient temperature control, the steps of which include:

[0114] Step S1 introduces the process gas into the primary reactor 4, which then passes sequentially through the upper adiabatic catalytic reaction zone 401 and the lower isothermal catalytic reaction zone 402. The upper adiabatic catalytic reaction zone 401 is controlled to carry out organic sulfur hydrolysis and Claus reaction at 310℃~320℃, while the lower isothermal catalytic reaction zone 402 is controlled to extract heat through an embedded heat extraction device, so that the reaction temperature is lower than that of the upper adiabatic catalytic reaction zone 401 and maintained at 240℃~260℃, and is always 8℃~15℃ higher than the real-time sulfur dew point temperature.

[0115] Step S2 introduces the process gas flowing out of the primary reactor 4 into the secondary sulfur condenser 101 to cool it to about 130°C and separate elemental sulfur. Then, it is heated by the secondary reheater 11 and kept at 185°C~195°C before being introduced into the secondary reactor 9. The gas undergoes a low-temperature Claus reaction maintained at 200°C~220°C and a hydrogenation reduction reaction maintained at 200°C~210°C to convert the sulfides in the process gas into elemental sulfur.

[0116] Step S3 introduces the process gas flowing out of the secondary reactor 9 into the tertiary sulfur condenser 102 to cool it to about 130°C and separate elemental sulfur. After being heated by the tertiary reheater 12, it is introduced into the tertiary reactor 13, where an oxidant is added to cause the residual H2S to undergo an oxidation reaction at an inlet temperature of about 200°C, oxidizing the residual sulfide hydrogen into elemental sulfur, and controlling the outlet tail gas temperature to about 220°C.

[0117] Step S4 introduces the process gas flowing out of the third-stage reactor 13 into the fourth-stage sulfur condenser 103 to cool and separate elemental sulfur, and controls the outlet gas phase temperature at 125°C through deep cooling.

[0118] Step S5 is based on the thermodynamic equilibrium nonlinear model of sulfur vapor partial pressure and sulfur dew point temperature. The sulfur vapor partial pressure at the outlet of the lower isothermal catalytic reaction zone 402 is monitored online, the sulfur dew point temperature is calculated in real time, and the heat output of the embedded heat extraction device is dynamically adjusted so that the temperature of the lower isothermal catalytic reaction zone 402 is always higher than the real-time sulfur dew point temperature.

[0119] Furthermore, in an optional embodiment, the sulfur recovery method further includes a tail gas treatment step:

[0120] Step S6 involves introducing the tail gas from the outlet of the final-stage sulfur condenser into the tail gas collector 14 for treatment. After sequential processing through the thermal incinerator 16 and the waste heat recovery unit 17, the gas is then fed into a quench tower. The tail gas temperature is reduced from approximately 240°C to approximately 70°C, and approximately two-thirds of the moisture is removed. The gas is then fed into a dry adsorption tower, where residual SO2 is adsorbed and removed by activated carbon-based and metal oxide-based desulfurizing agents until the SO2 emission concentration is <100 mg / m³. 3 After discharge (in special areas, SO2 emission concentration should be <50mg / m³ according to local standards). 3 ).

[0121] In summary, as can be seen from the above examples, the core gradient temperature control sulfur recovery system and method of the present invention generally solves the following technical problems:

[0122] 1. Resolving the inherent contradiction between "high-temperature hydrolysis" and "low-temperature high conversion rate" in traditional Claus reactors.

[0123] Traditional single-stage Claus reactors require operation at high temperatures of 310℃~320℃ to meet the requirements of organic sulfur hydrolysis and reaction kinetics. However, high temperatures are detrimental to the thermodynamic equilibrium conversion rate of the Claus reaction. This invention utilizes a dual-zone structure within the same reactor, combining an upper adiabatic section with a lower isothermal heat extraction section. This allows a single reactor to achieve the functionality of a traditional two-stage Claus reactor. The upper section ensures efficient hydrolysis of organic sulfur, while the lower section maintains a low-temperature isothermal reaction through precise heat extraction. This results in an overall sulfur conversion rate increase of approximately 1% compared to traditional reactors.

[0124] Ultimately, an ultra-high sulfur recovery rate is achieved: the total sulfur recovery rate can reach 99.8%, second only to the Scott (SCOT) process of 99.96%, and far exceeding the traditional three-stage Claus process (≤97%) and sub-dew point process (approximately 99~99.5%).

[0125] 2. Resolve issues related to sulfur blockage, catalyst deactivation, and frequent switching caused by low-temperature operation in sub-dew point processes.

[0126] This invention abandons the idea of ​​operating below the sulfur dew point in sub-dew point processes and proposes a "core gradient temperature control sulfur recovery technology (GradSulf)". By constructing a precise temperature gradient reaction chain of 310℃→250℃→200℃, corresponding to the gradient temperature control of "high temperature adiabatic → medium temperature isothermal → low temperature Claus / hydrogenation → adiabatic oxidation", the bed temperature of each reactor is always 8℃~15℃ higher than the sulfur dew point temperature under the corresponding operating conditions. This completely avoids the risk of sulfur vapor condensing and clogging on the catalyst surface, and achieves long-term continuous and stable operation without the need to switch reactors every 24 hours as in sub-dew point processes.

[0127] 3. Resolve the conflict between high sulfur recovery rate and environmental compliance, achieving zero waste liquid discharge from exhaust gas treatment.

[0128] This invention utilizes a gradient temperature-controlled reaction chain consisting of a "primary combined reactor + secondary composite reactor + tertiary oxidation reactor," coupled with multi-path synergistic conversion using four types of dedicated catalysts for oxygen removal, hydrolysis, hydrogenation, and oxidation. This increases the total sulfur recovery rate to 99.8% and significantly reduces SO2 emissions, lowering the SO2 concentration in the flue gas at the end-of-line furnace outlet to 300-800 mg / m³. 3At this point, only simple semi-dry or dry desulfurization methods are needed to meet environmental emission standards such as GB31570 / GB31571-2015. There is no need to use traditional alkaline washing wet desulfurization facilities, which fundamentally eliminates the generation of desulfurization wastewater and achieves zero waste liquid discharge in the closed-loop recycling process of sulfur resources.

[0129] 4. Solves the problems of long process flow, numerous equipment, and high investment associated with traditional multi-stage reactors.

[0130] This invention integrates the functions of a traditional two-stage Claus reactor into a single-stage combined reactor through reactor structure innovation, integrates the traditional independent two-stage Claus reactor and hydrogenation reactor into a single two-stage combined reactor, and integrates the second, third and fourth stage sulfur condensers 103 into a single shell structure, which significantly reduces the number of equipment, reduces the floor space, and lowers the investment in the equipment.

[0131] 5. Solves the problem of coarse temperature control and inability to dynamically adapt to changes in operating conditions in traditional processes.

[0132] This invention establishes for the first time a synergistic optimization algorithm for sulfur partial pressure and dew point temperature based on thermodynamic equilibrium. By monitoring sulfur vapor concentration online, iteratively calculating real-time sulfur dew point temperature, and dynamically adjusting the heat extraction, the synergistic optimization control of bed temperature and sulfur partial pressure is achieved, enabling temperature control accuracy to reach ±2℃. This avoids sulfur condensation and blockage while maximizing the reaction conversion rate.

[0133] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The present invention is limited only by the claims and their full scope and equivalents. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the protection scope of the invention.

[0134] Furthermore, all or part of the steps in the methods of the above embodiments can be implemented by a program instructing related hardware. This program is stored in a storage medium and includes several instructions to cause a microcontroller, chip, or processor to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as a USB flash drive, a portable hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0135] Furthermore, various different implementations of the present invention can be combined arbitrarily, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed in the present invention.

Claims

1. A sulfur recovery system with core gradient temperature control, comprising: The primary reactor, secondary reactor, tertiary reactor, and sulfur condenser are characterized in that, The primary reactor is a combined reactor, with an upper adiabatic catalytic reaction zone and a lower isothermal catalytic reaction zone arranged sequentially along the process gas flow direction. The upper adiabatic catalytic reaction zone is used for organic sulfur hydrolysis and Claus reaction, while the lower isothermal catalytic reaction zone has its reaction temperature controlled by an embedded heat extraction device to be lower than that of the upper zone and always higher than the real-time sulfur dew point temperature. The secondary reactor is a composite reactor, in which a Claus reaction zone and a hydrogenation reaction zone are arranged sequentially along the flow direction of the process gas. The Claus reaction zone controls the reaction temperature to be lower than that of the isothermal catalytic reaction zone in the lower section of the primary reactor and higher than the sulfur dew point temperature. The hydrogenation reaction zone is used to reduce the residual SO2 in the process gas to elemental sulfur under the action of a catalyst. The third-stage reactor is an adiabatic oxidation reactor, used to oxidize residual H2S into elemental sulfur; The system also includes a dynamic temperature control unit, which monitors the sulfur vapor partial pressure at the outlet of the lower section of the first-stage reactor online based on a nonlinear thermodynamic equilibrium model of sulfur vapor partial pressure and sulfur dew point temperature, calculates the sulfur dew point temperature in real time, and dynamically adjusts the heat output of the embedded heat extraction device so that the temperature of the lower isothermal catalytic reaction zone is always higher than the real-time sulfur dew point temperature.

2. The sulfur recovery system according to claim 1, characterized in that, The upper adiabatic catalytic reaction zone of the primary reactor is controlled at a reaction temperature of 310℃~320℃, and the lower isothermal catalytic reaction zone is controlled at a reaction temperature of 240℃~260℃, always 8℃~15℃ higher than the sulfur dew point temperature; the upper Claus reaction zone of the secondary reactor is controlled at an inlet temperature of 185℃~195℃, the bed temperature is controlled at 200℃~220℃, and the lower hydrogenation reaction zone is controlled at 200℃~210℃.

3. The sulfur recovery system according to claim 1, characterized in that, The thermodynamic equilibrium nonlinear model is as follows: ； in This is the vapor pressure of sulfur. For temperature; The sulfur dew point temperature is determined using the following iterative method: Calculate the partial pressure of sulfur ,in The absolute total pressure of the bed in the isothermal section. This refers to the concentration of sulfur vapor. Define a function: Given an initial temperature Iterate through the values ​​until the error between two consecutive iterations is less than 0.1K. The converged solution is the sulfur dew point temperature. Converted to Celsius The target bed temperature is set to ,in .

4. The sulfur recovery system according to any one of claims 1 or 3, characterized in that, The embedded heat extraction device adopts a heat exchange tube structure with uneven gaps and a water-circulating feedwater evaporator to achieve uniform temperature distribution across the reactor cross-section.

5. The sulfur recovery system according to claim 1, characterized in that, The sulfur condenser includes: a secondary sulfur condenser installed on the outlet pipe of the primary reactor, a tertiary sulfur condenser installed on the outlet pipe of the secondary reactor, and a quaternary sulfur condenser installed on the outlet pipe of the tertiary reactor; the secondary, tertiary, and quaternary sulfur condensers adopt an integrated structure with the same shell, and the outlet gas phase temperatures are controlled by cryogenic control at approximately 130°C, approximately 130°C, and approximately 125°C, respectively.

6. The sulfur recovery system according to claim 1, characterized in that, It also includes a tail gas treatment unit, which comprises: a tail gas collector, a thermal incinerator, a waste heat recovery unit, and a flue gas desulfurization device arranged in sequence. The tail gas collector is connected to the final stage sulfur condenser and receives tail gas for sequential processing and transmission. The flue gas desulfurization device includes a packed quench tower and a dry adsorption tower. The quench tower receives the sulfur-producing tail gas, reduces its temperature from about 240°C to about 70°C and removes about 2 / 3 of the moisture, and then inputs it into the dry adsorption tower. The dry adsorption tower is filled with a desulfurizing agent with a sulfur capacity ≥25wt%.

7. The sulfur recovery system according to claim 1, characterized in that, The upper adiabatic catalytic reaction zone of the primary reactor is filled with a hydrolysis catalyst to hydrolyze COS and CS2 in the raw acid gas into H2S, and the lower isothermal catalytic reaction zone is filled with a Claus catalyst.

8. The sulfur recovery system according to claim 1, characterized in that, The upper Claus reaction zone of the secondary reactor is filled with an Al-based or Ti-based Claus catalyst, and the lower hydrogenation reaction zone is filled with a Co-Mo-based hydrogenation catalyst.

9. A sulfur recovery method with core gradient temperature control, used to control the sulfur recovery system as described in any one of claims 1 to 8, characterized in that the steps include... include: Step S1 introduces the process gas into the primary reactor, which then passes through the upper adiabatic catalytic reaction zone and the lower isothermal catalytic reaction zone in sequence. The upper adiabatic catalytic reaction zone is controlled to carry out organic sulfur hydrolysis and Claus reaction at 310℃~320℃. The lower isothermal catalytic reaction zone is controlled to extract heat through an embedded heat extraction device, so that the reaction temperature is lower than that of the upper adiabatic catalytic reaction zone and maintained at 240℃~260℃, and is always higher than the real-time sulfur dew point temperature by 8℃~15℃. Step S2 involves introducing the process gas flowing out of the primary reactor into the secondary sulfur condenser and cooling it to about 130°C to separate elemental sulfur. After that, the gas is heated by the secondary reheater and kept at 185°C~195°C before being introduced into the secondary reactor. The gas then undergoes a low-temperature Claus reaction maintained at 200°C~220°C and a hydrogenation reduction reaction maintained at 200°C~210°C to convert the sulfides in the process gas into elemental sulfur. Step S3: The process gas flowing out of the secondary reactor is introduced into the tertiary sulfur condenser and cooled to about 130°C to separate elemental sulfur. After being heated by the tertiary reheater, it is introduced into the tertiary reactor. An oxidant is added to cause the residual H2S to undergo an oxidation reaction at an inlet temperature of about 200°C, which oxidizes the residual sulfide into elemental sulfur. The outlet tail gas temperature is controlled at about 220°C. Step S4 introduces the process gas flowing out of the three-stage reactor into the four-stage sulfur condenser for cooling and separation of elemental sulfur, and controls the outlet gas phase temperature at 125°C through deep cooling. Step S5 is based on the thermodynamic equilibrium nonlinear model of sulfur vapor partial pressure and sulfur dew point temperature. The sulfur vapor partial pressure at the outlet of the lower isothermal catalytic reaction zone is monitored online, the sulfur dew point temperature is calculated in real time, and the heat output of the embedded heat extraction device is dynamically adjusted so that the temperature of the lower isothermal catalytic reaction zone is always higher than the real-time sulfur dew point temperature.

10. The method according to claim 9, characterized in that, It also includes exhaust gas treatment steps: Step S6 introduces the tail gas from the outlet of the final stage sulfur condenser into the tail gas collector for treatment. After being processed sequentially through a thermal incinerator and a waste heat recovery unit, the tail gas is fed into a quench tower, where the temperature is reduced from about 240°C to about 70°C and about 2 / 3 of the moisture is removed. Then, the tail gas is fed into a dry adsorption tower, where residual SO2 is removed by adsorption of activated carbon-based desulfurizing agent and metal oxide-based desulfurizing agent before being discharged.

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