A system and method for prolonging the service life of an iron oxide desulfurizer for fine desulfurization of coke oven gas

Abstract

The application discloses a system and method for prolonging the service life of a coke oven gas fine desulfurization iron oxide desulfurizer, which comprises, in sequence along the gas flow direction, a source purification and steady-state pre-control module, a process active defense and safety guarantee module, and an intelligent impact avoidance and efficient reaction module; the source purification and steady-state pre-control module creates a precondition for the process active defense and safety guarantee module, and effective operation of the process active defense and safety guarantee module provides stable and clean inlet working conditions for a fine desulfurization reaction unit in the intelligent impact avoidance and efficient reaction module, and the three modules cooperatively constitute systematic whole-process protection for the iron oxide desulfurizer. The whole-process protection chain of'source control-process interception-intelligent protection-efficient utilization' is systematic and active protection for multiple failure risks (impurity blockage and H2S impact) faced by the iron oxide desulfurizer.

Description

Technical Field

[0001] This invention belongs to the field of coke oven gas purification technology, specifically relating to a system and method for extending the service life of coke oven gas fine desulfurization iron oxide desulfurizing agent. Background Technology

[0002] With the continuous tightening of national environmental protection policies, extremely stringent requirements have been placed on the emission of hydrogen sulfide (H2S) from coke oven gas in the steel industry, necessitating the stable control of the H2S concentration at the desulfurization outlet at 15 mg / Nm³. 3 The following are ultra-low emission levels. Among numerous treatment technologies, dry desulfurization technology, which uses iron oxide as the main active component, is widely used in the deep purification (fine desulfurization) stage of coke oven gas due to its mature process, high desulfurization accuracy, and relatively low initial investment.

[0003] However, in actual industrial operation, the service life of iron oxide desulfurizer is far shorter than designed, becoming a key bottleneck restricting the economic viability of this technology. The shortened service life stems mainly from two aspects: First, the quality of the inlet gas. Impurities such as residual gaseous naphthalene, trace amounts of tar, washing liquid, and alkali metal salts in the preceding gas can cause crystallization blockage, caking, and pulverization on the surface of the desulfurizer, covering active sites and leading to increased bed resistance, flow deviation, or even collapse. Second, insufficient system shock resistance. When fluctuations in the upstream coarse desulfurization unit cause an order-of-magnitude jump in the outlet H2S concentration, the high shock load will rapidly consume the limited sulfur capacity of the desulfurizer, causing it to quickly penetrate and fail.

[0004] Existing technologies lack systematic and proactive protection for iron oxide desulfurizers. For example, Chinese patent application (publication number CN117050790A) discloses a method to improve the utilization rate of dry desulfurizers, focusing on improving the utilization rate through multi-tower combinations. However, it does not propose targeted preventive measures for physical blockage and deactivation of desulfurizers caused by impurities (such as naphthalene and tar) in the inlet gas. Chinese patent application (publication number CN118526962A) discloses an anti-caking iron oxide desulfurization system and its application, which uses spraying to prevent agglomeration. Its methods mainly target the operating conditions already entering the desulfurization system, lacking effective monitoring and emergency avoidance mechanisms for the impact load caused by fluctuations in upstream H2S concentration. Therefore, existing technical solutions are mostly local optimizations targeting single problems, failing to construct a collaborative protection system covering source pre-control, process defense, and impact avoidance from the perspective of the entire gas purification process, in order to simultaneously address the two key factors that shorten the lifespan of desulfurizers: impurity blockage and H2S impact. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a system and method for extending the service life of the desulfurizing agent for coke oven gas desulfurization with iron oxide. This solves the problems of desulfurizing agent blockage and deactivation caused by inlet impurities and H2S impact load consumption caused by upstream fluctuations, thereby significantly extending the service life of the desulfurizing agent and ensuring long-term stable compliance with emission standards.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A system for extending the service life of iron oxide desulfurizing agent in coke oven gas fine desulfurization comprises, sequentially along the gas flow direction, a source purification and steady-state pre-control module, a process active defense and safety assurance module, and an intelligent impact avoidance and high-efficiency reaction module. The source purification and steady-state pre-control module creates the preconditions for the process active defense and safety assurance module. The effective operation of the process active defense and safety assurance module provides a stable and clean inlet condition for the fine desulfurization reaction unit in the intelligent impact avoidance and high-efficiency reaction module. These three modules work together to form a systematic, full-process protection for the iron oxide desulfurizing agent. The three modules are not simply stacked together, but rather form a full-process protection chain of "source control - process interception - intelligent protection - high-efficiency utilization." "Source purification" creates the conditions for "process defense"; the effective operation of "process defense" provides a stable and clean inlet condition for the core fine desulfurization reaction unit in "intelligent avoidance and high-efficiency reaction"; and "intelligent avoidance" protects the fine desulfurization reaction unit so that it can operate efficiently and for a long time under ideal conditions. This full-process protection chain of "source control - process interception - intelligent protection - efficient utilization" provides systematic and proactive protection against the multiple failure risks (impurity blockage, H2S impact) faced by iron oxide desulfurizers.

[0007] The source purification and steady-state pre-control module is used to perform closed-loop control of the operating parameters of the preceding purification unit, so as to control the total amount of harmful substances and H2S load in the pretreated coal gas entering the fine desulfurization reaction unit within a preset range from the source; and the preceding purification unit includes a primary cooler, an intermediate cooling naphthalene washing tower, and a final cooling benzene washing tower. The process active defense and safety assurance module intercepts and eliminates residual and potential risks during operation. It includes an electrostatic tar collector installed at the outlet of the final cooling benzene washing tower, a wire mesh demister installed before the inlet of the fine desulfurization reaction unit, and a full-process insulation layer. The full-process insulation layer forms a temperature protection system to ensure that the temperature of the gas does not drop but rises during transportation, fundamentally preventing naphthalene from crystallizing and precipitating due to temperature drop. The source purification and steady-state pre-control module controls the naphthalene content, while the process active defense and safety assurance module forms a characteristic coupling with the full-process insulation layer: the source control reduces the absolute content of naphthalene, while the full-process insulation layer ensures that the process temperature is higher than the naphthalene dew point at that content. The two work together to completely eliminate the risk of naphthalene crystallization.

[0008] The intelligent impact avoidance and high-efficiency response module is designed to cope with sudden H2S load impacts from upstream and maximize the utilization of desulfurizing agent capacity. It includes an intelligent bypass system for H2S impact loads and a fine desulfurization reaction unit. The intelligent bypass system for H2S impact loads includes an online H2S concentration monitor installed on the inlet pipe of the fine desulfurization reaction unit, a bypass pipeline and bypass valve connected in parallel with the fine desulfurization reaction unit, and a decision unit with built-in hierarchical response interlocking logic.

[0009] Furthermore, the source purification and steady-state pre-control module performs closed-loop control of the operating parameters of the preceding purification unit as follows: the outlet gas temperature of the primary cooler is stabilized at 15~25℃; the mass fraction of naphthalene in the circulating wash oil of the intermediate cooling naphthalene washing tower is controlled to be ≤15%; and the outlet gas temperature of the final cooling benzene washing tower is controlled at 20~35℃. These three factors work synergistically to ensure that the partial pressure of naphthalene in the gas is lower than the saturated vapor pressure of naphthalene at the subsequent process temperatures, and to stabilize the H2S concentration at the inlet of the fine desulfurization reaction unit at 30~100 mg / m³. 3 This precise range creates an ideal reaction starting point for subsequent deep desulfurization, preventing the desulfurizing agent from being consumed too quickly due to drastic fluctuations in inlet operating conditions. It also creates stable and clean gas inlet conditions for subsequent treatment, which is a fundamental prerequisite for extending the desulfurizing agent's lifespan.

[0010] Furthermore, in the process active defense and safety assurance module, the electrostatic tar precipitator has a tar removal efficiency of no less than 95%, used to remove trace amounts of tar mist from the coal gas; the wire mesh demister has a demisting efficiency of greater than 99%, used to capture tar droplets and other impurities entrained in the coal gas; the wire mesh demister is equipped with a flushing system, which monitors the demister resistance through a resistance sensor. When the demister resistance exceeds 0.3 kPa, the flushing system is activated to flush the wire mesh demister to prevent blockage; the flushing waste liquid discharged from the wire mesh demister (i.e., the flushing waste liquid discharged from the flushing system) is returned to the preceding tar-ammonia-water circulation system. The waste liquid after flushing by the flushing system is returned to the preceding tar-ammonia-water circulation system.

[0011] Furthermore, the full-process insulation layer includes an insulation layer fitted on the gas pipeline in the preceding purification unit that connects the intermediate cooling naphthalene washing tower and the final cooling benzene washing tower, an insulation layer fitted on the gas pipeline that connects the final cooling benzene washing tower and the electrostatic tar precipitator, an insulation layer fitted on the gas pipeline that connects the electrostatic tar precipitator and the coarse desulfurization tower, an insulation layer fitted on the gas pipeline that connects the coarse desulfurization tower and the wire mesh demister, an insulation layer fitted on the gas pipeline that connects the wire mesh demister and the fine desulfurization reaction unit, and an insulation layer wrapped around the outer wall of the fine desulfurization reaction tower.

[0012] Based on source control, the process active defense and safety assurance module arranges "end interception" devices (electrostatic tar precipitator, wire mesh demister) and a "whole-process heat preservation" strategy. The electrostatic tar precipitator efficiently removes micron-scale tar mists, the wire mesh demister captures entrained droplets, and is equipped with automatic flushing to prevent blockage.尤为关键的是,全流程保温层确保了煤气在输送过程中温度不降反升,这从热力学上杜绝了萘因温度降至露点以下而结晶析出。有效去除了残余的微量焦油和液滴,彻底解决了因萘结晶、焦油板结导致的脱硫剂孔道堵塞、床层偏流、阻力升高等运行难题,保护了脱硫剂的物理结构和活性位点。

[0013] Further, the hierarchical response interlock logic of the H2S shock load intelligent bypass system is as follows: First-level response: When the reading of the H2S concentration online monitor ≤ 1 g / m 3 ³, the bypass valve of the bypass pipeline closes, and all the gas enters the fine desulfurization reaction unit; Second-level response: When 1 g / m 3 ³ < H2S concentration ≤ 2 g / m 3 ³, the system issues a high-level alarm; Third-level response: When the H2S concentration continuously > 2 g / m 3 ³, the system determines it as a shock load and automatically opens the bypass valve of the bypass pipeline to divert part or all of the exceeding-standard gas to the bypass pipeline.

[0014] Further, the fine desulfurization reaction unit consists of multiple fine desulfurization towers filled with iron oxide desulfurizer, and the fine desulfurization towers are connected by pipelines and valves, and are switched to series, parallel or series-parallel combined operation modes according to operation requirements.

[0015] The protective effect of the H2S shock load intelligent bypass system and the coordinated operation mode of the fine desulfurization reaction unit composed of multiple towers form another characteristic coupling: the bypass system avoids sudden high-intensity shocks and provides a stable and low-shock inlet environment for the fine desulfurization reaction unit; while the multi-tower coordinated mode (such as initial parallel uniform consumption and later series to explore marginal sulfur capacity) can fully exert its operation flexibility under this protected ideal working condition, deeply and evenly utilize the sulfur capacity of the desulfurizer, and thus systematically improve the overall utilization rate and service life.

[0016] The present invention also provides a method for extending the service life of the iron oxide desulfurizer for fine desulfurization of coke oven gas by using the system as described above, including the following steps: S1. By regulating the operation parameters of the primary cooler, intermediate cooling and naphthalene washing tower, and final cooling and benzene washing tower in the previous purification unit, produce pre-treated gas with stable H2S concentration, low naphthalene and tar impurity content from the source; S2. The pre-treated coal gas produced in step S1 flows through an electrostatic tar precipitator and a wire mesh demister to remove residual tar mist and droplets. Meanwhile, the temperature of the coal gas is maintained through full-process heat preservation to prevent the precipitation of naphthalene crystals. S3. The H2S concentration in the coal gas after being treated in step S2 is monitored in real time, and hierarchical interlock control is executed according to a preset threshold. Before the formation of an impact load, a bypass pipeline is started for shunt protection. S4. The protected coal gas enters the fine desulfurization reaction unit and reacts fully with iron oxide desulfurizer in a series, parallel or series-parallel combination mode according to the actual load and the state of the iron oxide desulfurizer, ensuring that the final outlet H2S concentration is stably lower than the preset standard.

[0017] Further, in step S3, the preset threshold includes an alarm threshold for the H2S concentration and a bypass pipeline start threshold for the H2S concentration. Among them, the alarm threshold for the H2S concentration is: 1 g / m 3 <H2S concentration ≤ 2 g / m 3 , and the bypass pipeline start threshold for the H2S concentration is: H2S concentration continuously > 2 g / m 3 .

[0018] Further, in step S4, the preset standard for the H2S concentration is 15 mg / Nm 3 .

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Significantly extend the service life of the desulfurizer: Through systematic protection, the service life of the iron oxide desulfurizer is stably extended from less than 6 months to more than 12 months, and the replacement frequency is reduced by more than 50%, greatly saving the material and hazardous waste treatment costs.

[0020] 2. Ensure stable ultra-low emissions: The outlet H2S concentration can be stably lower than the ultra-low emission standard of 15 mg / Nm 3 for a long time, and the system has strong anti-interference ability.

[0021] 3. Solve multiple operation problems: The design of the electrostatic tar precipitator and the full-process heat preservation layer fundamentally eliminates the problems of tar caking and naphthalene crystal blockage, and solves the problems of bed layer deviation and resistance increase caused thereby. The unplanned shutdown rate is greatly reduced.

[0022] 4. Achieve intelligent and economical operation: The combination of intelligent bypass protection and multi-tower collaborative mode can not only actively avoid impacts to preserve sulfur capacity, but also deeply explore the utilization potential of the desulfurizer, realizing the optimization of the whole-life cycle operation and maintenance cost, with remarkable environmental protection and economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a schematic diagram of the coke oven gas purification process of the present invention; Figure 2 This is a block diagram of the hierarchical response interlocking logic of the H2S impact load intelligent bypass system of the present invention; Figure 3 This is a schematic diagram of the operation mode of the three fine desulfurization towers working in concert in this invention. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0025] Example 1 System startup and routine operation based on multi-tower collaborative operation mode like Figure 1 As shown, the system is operating according to the process flow, including three desulfurization towers (T1, T2, T3), inlet valves for the desulfurization towers (V1, V2, V3), outlet valves for the desulfurization towers (V4, V5, V6), a series valve between T1 and T2 (V7), and a series valve between T2 and T3 (V8). The inlet H2S concentration is 50 mg / m³. 3 Furthermore, the wire mesh demister removed most of the tar droplets, and the entire process insulation layer was put into use, ensuring the gas temperature.

[0026] The specific implementation process is as follows: Step 1: Confirm all instruments and valves are functioning correctly. Based on the production plan and gas load, operate in parallel mode, such as... Figure 3 The diagram shows how to maximize processing capacity and evenly utilize the three desulfurization towers. According to the valve status table in Table 1, valves V1, V2, V3, V4, V5, and V6 are opened, while V7 and V8 are closed. This valve combination ensures that the gas is divided into three streams and simultaneously enters the three desulfurization towers T1, T2, and T3.

[0027] Step 2: The coal gas passes through the desulfurizing agent beds of the three fine desulfurization towers in parallel. Monitor the pressure difference of each fine desulfurization tower (confirming no abnormal increase: indicating no blockage) and the total outlet H2S concentration (stabilizing at 10 mg / Nm³). 3 the following).

[0028] Operating in parallel mode, the system initially achieved high processing efficiency and extremely high desulfurization accuracy. The uniform consumption of desulfurizing agent across the three towers laid the foundation for switching to series mode to fully utilize the "marginal sulfur capacity" of the desulfurizing agent. Under the protection of this invention's system, the service life of the iron oxide desulfurizing agent is significantly extended from "less than six months" (approximately six months) in existing technologies. Through optimized operation in a multi-tower synergistic mode, the overall service life of the desulfurizing agent is expected to stably reach over 12 months, achieving a doubling of its lifespan.

[0029] Table 1. Status of Control Valves in the Operation Mode of the Fine Desulfurization Tower Example 2 Intelligent bypass protection against H2S impact loads The system operates in parallel mode as described in Example 1, with the intelligent impact avoidance and high-efficiency response module in use, including an inlet H2S online monitoring instrument, bypass pipelines and bypass valves, and built-in hierarchical response interlocking logic (decision unit).

[0030] The specific process is as follows: Step 1: Upstream fluctuations caused the inlet H2S concentration to rise to 1.2 g / m³. 3 The system triggered a level-two warning, issuing an audible and visual alarm, while the bypass valve on the bypass pipeline remained closed.

[0031] Step 2: Fluctuations intensify, H2S concentration consistently exceeds 2 g / m³ 3 Up to 2.5g / m 3 The system determines that it is under impact load, triggering a level three response. The bypass valve on the bypass pipeline connected in parallel with the fine desulfurization reaction unit opens, and part or all of the ultra-high concentration coal gas is diverted to the bypass, directly bypassing the fine desulfurization reaction unit.

[0032] The H2S load entering the fine desulfurization reaction unit is significantly reduced, preventing the desulfurizer's sulfur capacity from being rapidly consumed. This protection avoids the risk that a single shock could shorten the desulfurizer's lifespan by 1-2 months, ensuring its long-term stable operation. After the shock ends, the concentration returns to normal, and the bypass valve on the bypass pipeline is closed.

[0033] Specifically: When the inlet gas flow rate of the desulfurization reaction unit is 50000 Nm 3 / h, the total loading capacity of iron oxide desulfurizing agent is 100m³. 3 Its effective sulfur capacity (based on elemental sulfur) is 20 kgS / m³. 3 Therefore, the total effective sulfur capacity is 2000 kgS.

[0034] ① No bypass system: When the H2S concentration increases from the normal value of 0.1 g / m³ 3 It surged to 2.5g / m³ 3 If the impact continues for 8 hours, the total amount of H2S entering will be: 50000 × 8 × 2.5 = 1,000 kg, which is equivalent to approximately 940 kg of sulfur (the mass fraction of S in H2S is 94.1%). This impact will consume 47% (940 / 2000) of the total sulfur capacity of the desulfurizing agent, which is equivalent to consuming the effective sulfur capacity that would have been sufficient for 4 months of stable operation.

[0035] ② When using this embodiment with a bypass system: when the H2S concentration is consistently >2 g / m³ 3When the bypass system is automatically activated, 70% of the gas is diverted to the bypass, and only 30% enters the desulfurization unit. The total amount of H2S entering the desulfurization unit is 50000×8×2.5×30%=300kg, which is equivalent to about 282kgS of sulfur, accounting for only 14% of the total sulfur capacity, equivalent to 1.2 months of normal consumption.

[0036] With the intervention of the bypass system, the consumption of desulfurizer sulfur capacity by a single impact load was reduced from 47% to 14%, effectively avoiding approximately 2.8 months of sulfur capacity loss due to a single fluctuation. Considering the several fluctuations that may occur throughout the year, the protective effect of the bypass system can extend the service life of the desulfurizer by 1-2 months, verifying its significant protective effect in actual operation.

[0037] Example 3 The entire process operates collaboratively to achieve long-term stability and extended lifespan. This embodiment demonstrates the collaborative operation of the entire system.

[0038] The specific process is as follows: Step 1: Control the operating parameters of the preceding purification unit: primary cooler outlet gas temperature 20℃, intermediate cooler naphthalene washing oil naphthalene content 10% (mass fraction), final cooler benzene washing tower outlet gas temperature 25℃. This coordinated control ensures that the naphthalene content in the gas entering the fine desulfurization reaction unit is below its saturation precipitation point, and pre-stabilizes the inlet H2S concentration at 50 mg / m³. 3 By controlling the temperature and the naphthalene content in the wash oil, the partial pressure of naphthalene in the gas is kept below the saturated vapor pressure of naphthalene at the current temperature, thus thermodynamically preventing crystallization.

[0039] Step 2: The gas first enters the electrostatic tar precipitator. Under the action of a high-voltage electrostatic field, the residual trace amounts of tar mist are efficiently captured (efficiency ≥ 95%), ensuring that the tar content at the outlet is less than 5 mg / Nm³. 3 The gas then enters a wire mesh demister to capture any remaining trace amounts of tar and droplets (demister efficiency >99%). When the resistance sensor reading in the wire mesh demister rises to 0.35 kPa (>0.3 kPa setpoint) due to impurity accumulation, its flushing system activates to prevent clogging. The flushing wastewater is returned to the preceding tar-ammonia water system. A full-process insulation layer ensures that the temperature rises during gas transportation, preventing naphthalene crystallization.

[0040] Step 3: The pretreated clean and stable coal gas enters the multi-tower fine desulfurization reaction unit for reaction. Depending on the requirements, parallel, series, or series-parallel connection modes are adopted to fully react with the iron oxide desulfurizing agent. By eliminating the risk of naphthalene crystallization and impurity blockage at the source, preventing residual impurities during the process, and providing a stable reaction environment, the iron oxide desulfurizer no longer fails prematurely due to caking, pulverization, or impact consumption. The system achieves continuous and stable operation, significantly extending the service life of the iron oxide desulfurizer from "less than six months" in the original technology to "more than 12 months," and the H2S concentration at the fine desulfurization outlet remains consistently below 15 mg / Nm³. 3 The invention fully achieved its objective of "significantly extending the service life of iron oxide desulfurizer from less than six months to more than one year".

[0041] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A system for extending the service life of iron oxide desulfurizing agent in coke oven gas desulfurization, characterized in that, Along the direction of coal flow, the modules include, in sequence, a source purification and steady-state pre-control module, a process active defense and safety assurance module, and an intelligent impact avoidance and high-efficiency response module. The source purification and steady-state pre-control module is used to perform closed-loop control of the operating parameters of the preceding purification unit, so as to control the total amount of harmful substances and H2S load in the pretreated coal gas entering the fine desulfurization reaction unit within a preset range from the source. The process active defense and safety assurance module is designed to intercept and eliminate residual and potential risks during operation. It includes an electrostatic tar collector located at the outlet of the final cooling benzene washing tower, a wire mesh demister located before the inlet of the fine desulfurization reaction unit, and a full-process insulation layer. The intelligent impact avoidance and high-efficiency response module is designed to cope with sudden H2S load impacts from upstream and maximize the utilization of desulfurizing agent capacity. It includes an intelligent bypass system for H2S impact loads and a fine desulfurization reaction unit. The intelligent bypass system for H2S impact loads includes an online H2S concentration monitor installed on the inlet pipe of the fine desulfurization reaction unit, a bypass pipeline and bypass valve connected in parallel with the fine desulfurization reaction unit, and a decision unit with built-in hierarchical response interlocking logic.

2. The system according to claim 1, characterized in that, The source purification and steady-state pre-control module performs closed-loop control of the operating parameters of the preceding purification unit as follows: stabilizing the outlet gas temperature of the primary cooler at 15~25℃, controlling the naphthalene mass fraction in the circulating wash oil of the intermediate cooling naphthalene washing tower to ≤15%, and controlling the outlet gas temperature of the final cooling benzene washing tower at 20~35℃, ensuring that the partial pressure of naphthalene in the gas is lower than the saturated vapor pressure of naphthalene at the subsequent process temperatures, and stabilizing the H2S concentration at the inlet of the fine desulfurization reaction unit at 30~100 mg / m³. 3 The range.

3. The system according to claim 1, characterized in that, In the process active defense and safety assurance module, the electrostatic tar collector has a tar removal efficiency of not less than 95% and is used to remove trace amounts of tar mist from the coal gas; the wire mesh demister has a demisting efficiency of greater than 99% and is used to capture tar droplets and other impurities entrained in the coal gas.

4. The system according to claim 3, characterized in that, The wire mesh demister is equipped with a rinsing system. The rinsing system monitors the resistance of the demister through a resistance sensor. When the resistance of the demister is greater than 0.3 kPa, the rinsing system is activated to rinse the wire mesh demister. The rinsing waste liquid discharged from the wire mesh demister is returned to the preceding tar ammonia water circulation system.

5. The system according to claim 1, characterized in that, The entire process insulation layer includes an insulation layer fitted on the gas pipeline connecting the intermediate cooling naphthalene washing tower and the final cooling benzene washing tower in the preceding purification unit, an insulation layer fitted on the gas pipeline connecting the final cooling benzene washing tower and the electrostatic tar precipitator, an insulation layer fitted on the gas pipeline connecting the electrostatic tar precipitator and the coarse desulfurization tower, an insulation layer fitted on the gas pipeline connecting the coarse desulfurization tower and the wire mesh demister, an insulation layer fitted on the gas pipeline connecting the wire mesh demister and the fine desulfurization reaction unit, and an insulation layer wrapped around the outer wall of the fine desulfurization reaction tower.

6. The system according to claim 1, characterized in that, The hierarchical response interlocking logic of the H2S impact load intelligent bypass system is as follows: Level 1 Response: When the online H2S concentration monitoring instrument reading is ≤1 g / m³ 3 At that time, the bypass valve of the bypass pipeline is closed, and all the coal gas enters the fine desulfurization reaction unit; Secondary response: When 1 g / m 3 <H2S concentration ≤ 2 g / m 3 , the system issues a high-level alarm; Level 3 response: When the H2S concentration remains >2 g / m³ 3 When the system detects an impact load, it automatically opens the bypass valve of the bypass pipeline, diverting part or all of the excess gas to the bypass pipeline.

7. The system according to claim 1, characterized in that, The fine desulfurization reaction unit consists of multiple fine desulfurization towers filled with iron oxide desulfurizing agent. The fine desulfurization towers are connected by pipes and valves, and can be switched to series, parallel or series-parallel combination operation modes according to operating requirements.

8. A method for extending the service life of the iron oxide desulfurizing agent in coke oven gas desulfurization using the system described in any one of claims 1-7, characterized in that, Includes the following steps: S1. By adjusting the operating parameters of the primary cooler, intermediate cooler naphthalene washing tower, and final cooler benzene washing tower in the preceding purification unit; S2. The pretreated gas produced in step S1 passes through an electrostatic tar precipitator and a wire mesh demister to remove residual tar mist and droplets; at the same time, the gas temperature is maintained through full-process heat preservation to prevent naphthalene crystallization. S3. Monitor the H2S concentration in the gas after step S2 in real time, and perform graded interlocking control according to the preset threshold. Start the bypass pipeline for diversion protection before the impact load is formed. S4. The protected coal gas enters the fine desulfurization reaction unit. Based on the actual load and the status of the iron oxide desulfurizer, the gas is selected to react fully with the iron oxide desulfurizer in series, parallel or series-parallel combination mode to ensure that the final outlet H2S concentration is stably lower than the preset standard.

9. The method according to claim 8, characterized in that, In the step S3, the preset thresholds include the alarm threshold of H2S concentration and the bypass pipeline start threshold of H2S concentration. Among them, the alarm threshold of H2S concentration is: 1 g / m 3 <When 1 g / m 3 ≤ H2S concentration ≤ 2 g / m 3 . The bypass pipeline start threshold of H2S concentration is: when H2S concentration continuously > 2 g / m 10. The method according to claim 8, characterized in that, In step S4, the preset standard for H2S concentration is 15 mg / Nm³. 3 .

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