Complex iron desulfurizer intelligent regeneration and iron ion circulation stable control system

Abstract

This invention discloses an intelligent regeneration and iron ion circulation stabilization control system for complexed iron desulfurizer, comprising a desulfurization tower, a regeneration unit, a monitoring unit, a control unit, and an auxiliary unit. The desulfurization tower is used to contact biogas containing hydrogen sulfide with the complexed iron desulfurizer to undergo a desulfurization reaction to remove hydrogen sulfide from the biogas. Through an intelligent control strategy that integrates a multi-module online monitoring unit and ORP-pH dual-parameter coupling, real-time monitoring and precise control of the iron ion valence state are achieved. Combined with the variable frequency aeration regeneration unit, the operating parameters are dynamically adjusted to improve the regeneration efficiency and stability of the desulfurizer, ensuring that the Fe²⁺ / Fe³⁺ ratio is always maintained within the optimal range, thus guaranteeing stable desulfurization efficiency. By establishing an automatic compensation mathematical model for the complexing agent and a multi-parameter aging assessment system for the desulfurizer, the system enables precise replenishment of the complexing agent as needed and scientific early warning of desulfurizer aging. This avoids cost waste caused by excessive addition of the agent and timely avoids safety risks caused by desulfurizer failure.

Description

Technical Field

[0001] This invention belongs to the field of biogas purification and treatment technology, specifically relating to a smart regeneration and iron ion circulation stabilization control system for complexed iron desulfurizer. Background Technology

[0002] Biogas, as a renewable energy source, contains hydrogen sulfide, which is toxic and corrosive, posing a threat to human health and corroding biogas utilization equipment. Furthermore, the sulfur dioxide produced during combustion causes pollution. Therefore, desulfurization treatment is essential before biogas utilization. Complex iron desulfurization has become the mainstream desulfurization technology for large and medium-sized biogas projects due to its advantages such as high desulfurization efficiency, fast reaction speed, and low operating costs. It achieves desulfurization by oxidizing hydrogen sulfide with Fe³⁺, followed by aeration to oxidize the reduced Fe²⁺ back to Fe³⁺, completing the iron ion cycle.

[0003] However, traditional complexed iron desulfurization technology has many problems in practical applications: the desulfurizing agent regeneration efficiency is greatly affected by the operating conditions and is unstable; the valence state of iron ions depends on manual sampling and monitoring, and cannot be controlled in real time; the loss of complexing agent lacks online monitoring and automatic compensation mechanism, which can easily lead to waste of reagents or desulfurization failure; there is no scientific assessment method for the aging degree of desulfurizing agent, and the regeneration process relies on a single parameter control, which is difficult to adapt to fluctuations in operating conditions and seriously affects the operational stability and economy of the desulfurization system. Therefore, we need to provide a smart regeneration and iron ion circulation stable control system for complexed iron desulfurizing agent. Summary of the Invention

[0004] The purpose of this invention is to provide an intelligent regeneration and iron ion circulation stability control system for complexed iron desulfurizers. By integrating online monitoring, intelligent regulation, automatic compensation, and aging assessment technologies, it achieves efficient desulfurizer regeneration, precise control of iron ion valence state, on-demand replenishment of complexing agents, and scientific early warning of desulfurizer aging. This addresses the problems mentioned in the background art, such as unstable desulfurizer regeneration efficiency, difficulty in monitoring and controlling iron ion valence state, difficulty in effectively managing complexing agent loss, lack of assessment methods for desulfurizer aging, and single control parameters in the regeneration process.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a smart regeneration and iron ion circulation stabilization control system for complexed iron desulfurizer, comprising a desulfurization tower, a regeneration unit, a monitoring unit, a control unit, and an auxiliary unit; The desulfurization tower is used to bring biogas containing hydrogen sulfide into contact with complexed iron desulfurizing agent to produce a desulfurization reaction and remove hydrogen sulfide from the biogas. The desulfurization liquid outlet of the desulfurization tower is connected to the liquid inlet of the regeneration unit. The outlet of the regeneration unit is connected to the desulfurization liquid inlet of the desulfurization tower to realize the circulation and transportation of the desulfurization liquid. Each monitoring probe of the monitoring unit is arranged on the desulfurization liquid flow path of the desulfurization tower and the regeneration unit, and the signal output terminal of the monitoring unit is electrically connected to the signal input terminal of the control unit. The control signal output terminal of the control unit is electrically connected to the controlled terminals of the regeneration unit and the auxiliary unit, respectively. The auxiliary unit's medium output end is connected to the medium replenishment port of the desulfurization tower and / or regeneration unit, and the auxiliary unit's discharge end is connected to the aging desulfurization liquid discharge port of the regeneration unit. Preferably, the regeneration unit is an aeration regeneration module, which includes an aeration blower, a gas distributor, a gas-liquid separator, and a tail gas treatment device. The outlet of the aeration blower is connected to the gas distributor, which is located at the bottom of the desulfurization liquid tank of the regeneration unit. The gas-liquid separator is connected to the gas phase outlet of the regeneration unit, and the tail gas treatment device is connected to the tail gas discharge end of the gas-liquid separator.

[0006] Preferably, the gas distributor is a microporous aeration disc or a swirl aerator with an aeration aperture of 10-200 micrometers; the aeration blower is a variable frequency blower, and its air volume can be adjusted according to the feedback signal from the control unit.

[0007] Preferably, the monitoring unit includes an online iron ion valence state monitoring module, an ORP monitoring module, a pH monitoring module, a complexing agent concentration monitoring module, and a desulfurizing agent performance evaluation module. The probe end of each monitoring module extends into the desulfurization liquid of the desulfurization tower and / or regeneration unit, and the signal output end of each monitoring module is electrically connected to the control unit.

[0008] Preferably, the online monitoring module for iron ion valence state is designed based on the potentiometric principle, and the control unit has a built-in Nernst equation calculation model. After the ORP monitoring module and pH monitoring module transmit the detected ORP value and pH value to the control unit, the control unit calculates the ratio of Fe²⁺ / Fe³⁺ in the desulfurization liquid through the Nernst equation.

[0009] Preferably, the complexing agent concentration monitoring module uses spectrophotometry or ion chromatography to achieve online monitoring of the complexing agent concentration; the monitoring unit also includes a temperature monitoring module, the probe of which is arranged on the flow path of the desulfurization liquid, and the signal output of which is electrically connected to the control unit. The temperature monitoring module is used to monitor the temperature of the desulfurization liquid and maintain the temperature within the range of 25-45℃.

[0010] Preferably, the auxiliary unit includes an iron ion complexing agent storage tank, a complexing agent storage tank, a metering pump, a replenishment pipeline, an aging desulfurizing agent discharge system, and a cooling / heating device; the outlet of the complexing agent storage tank is connected to the inlet of the metering pump through the replenishment pipeline, and the outlet of the metering pump is connected to the medium replenishment port of the desulfurization tower and / or regeneration unit; the heat exchange end of the cooling / heating device extends into the desulfurization liquid tank of the desulfurization tower and / or regeneration unit, and the controlled end of the cooling / heating device is electrically connected to the control unit.

[0011] Preferably, the desulfurization tower is a packed tower, a spray tower, a bubbling tower, or a combined bubbling-spraying desulfurization tower. The combined bubbling-spraying desulfurization tower includes a primary submerged bubbling section and a secondary above-liquid double-layer spraying section. The desulfurization tower is filled with bulk packing material, which is polypropylene or stainless steel.

[0012] Preferably, the control unit incorporates an ORP-pH-Fe²⁺ / Fe³⁺ relationship model, an automatic compensation calculation model for complexing agents, and an aging index calculation model for desulfurizers. Based on an intelligent control strategy that couples ORP and pH parameters, the control unit calculates the required ORP setpoint according to the target Fe²⁺ / Fe³⁺ ratio and adjusts the aeration rate or electrolysis current of the regeneration unit according to the deviation between the actual ORP and the setpoint.

[0013] Preferably, the control unit is a PLC control system, equipped with an operator station, an engineer station, and a field control station; the auxiliary unit also includes a sulfur separation system, the feed end of which is connected to the sulfur discharge outlet of the regeneration unit.

[0014] Technical effects and advantages of the present invention: The intelligent regeneration and iron ion circulation stabilization control system for complexed iron desulfurizer proposed in this invention has the following advantages compared with the prior art: 1. This invention achieves real-time monitoring and precise control of the valence state of iron ions by integrating a multi-module online monitoring unit with an intelligent control strategy that couples ORP and pH dual parameters. Combined with the regeneration unit of variable frequency aeration, the operating parameters are dynamically adjusted to improve the regeneration efficiency and stability of the desulfurizing agent, so that the Fe²⁺ / Fe³⁺ ratio is always maintained in the optimal range, ensuring the stability of desulfurization efficiency. 2. This invention establishes an automatic compensation mathematical model for complexing agents and a multi-parameter aging assessment system for desulfurizers, enabling precise on-demand replenishment of complexing agents and scientific early warning of desulfurizer aging. This avoids cost waste caused by excessive addition of agents and timely avoids safety risks caused by desulfurizer failure, thereby comprehensively reducing system operating costs, improving system automation, reducing manual operation, and enhancing adaptability to biogas load fluctuations.

[0015] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description and the drawings. Attached Figure Description

[0016] Figure 1 This is a system flowchart of the present invention. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The specific embodiments described herein are merely used to explain the present invention and are not intended to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] This invention provides, for example Figure 1 The intelligent regeneration and iron ion circulation stabilization control system for complexed iron desulfurizer shown includes a desulfurization tower, a regeneration unit, a monitoring unit, a control unit, and an auxiliary unit. The desulfurization tower is used to bring biogas containing hydrogen sulfide into contact with complexed iron desulfurizing agent to produce a desulfurization reaction and remove hydrogen sulfide from the biogas. The desulfurization liquid outlet of the desulfurization tower is connected to the liquid inlet of the regeneration unit. The outlet of the regeneration unit is connected to the desulfurization liquid inlet of the desulfurization tower to realize the circulation and transportation of the desulfurization liquid. Each monitoring probe of the monitoring unit is arranged on the desulfurization liquid flow path of the desulfurization tower and the regeneration unit, and the signal output terminal of the monitoring unit is electrically connected to the signal input terminal of the control unit. The control signal output terminal of the control unit is electrically connected to the controlled terminals of the regeneration unit and the auxiliary unit, respectively. The auxiliary unit's media output end is connected to the media replenishment port of the desulfurization tower and / or regeneration unit, and the auxiliary unit's discharge end is connected to the aging desulfurization liquid discharge port of the regeneration unit. Through an intelligent control strategy that integrates a multi-module online monitoring unit and ORP-pH dual-parameter coupling, real-time monitoring and precise control of the iron ion valence state are achieved. Combined with the dynamic adjustment of operating parameters by the frequency conversion aeration regeneration unit, the desulfurizing agent regeneration efficiency and stability are greatly improved, ensuring that the Fe²⁺ / Fe³⁺ ratio is always maintained within the optimal range, thus guaranteeing stable desulfurization efficiency.

[0019] The regeneration unit is an aeration regeneration module, which includes an aeration blower, a gas distributor, a gas-liquid separator, and a tail gas treatment device. The outlet of the aeration blower is connected to the gas distributor, which is located at the bottom of the desulfurization liquid tank of the regeneration unit. The gas-liquid separator is connected to the gas phase outlet of the regeneration unit, and the tail gas treatment device is connected to the tail gas discharge end of the gas-liquid separator. Specifically, the aeration and regeneration module provides the core site for the regeneration reaction of the desulfurization liquid and is the key unit for realizing the oxidation of Fe²⁺ to Fe³⁺. Its components work together to complete the entire regeneration process of aeration, reaction, gas-liquid separation and tail gas treatment. The aeration blower serves as the aeration power source and continuously outputs oxygen-containing gas. Its outlet is connected to the gas distributor through a pipeline to ensure stable delivery of oxygen-containing gas. The gas distributor is fixedly installed at the bottom of the desulfurization liquid tank of the regeneration unit. It can disperse the oxygen-containing gas into tiny bubbles, increase the contact area between the gas and the desulfurization liquid, improve the gas-liquid mass transfer efficiency, thereby accelerating the oxidation and regeneration reaction of Fe²⁺ in the desulfurization liquid and ensuring the iron ion circulation efficiency. The mixed gas phase generated during the regeneration reaction is discharged from the gas phase outlet of the regeneration unit and enters the gas-liquid separator. The gas-liquid separator separates the desulfurization liquid droplets entrained in the mixed gas phase through gravity separation or cyclone separation and returns them to the desulfurization liquid tank of the regeneration unit, preventing desulfurizing agent loss. The tail gas discharge end of the gas-liquid separator is connected to a tail gas treatment device, which purifies the separated tail gas, removing residual trace amounts of hydrogen sulfide, elemental sulfur particles, and other impurities, ensuring the tail gas meets emission standards and preventing secondary pollution. All components are connected via sealed pipelines or flanges to ensure the sealing and operational stability of the aeration regeneration module, providing a reliable guarantee for the efficient regeneration of the desulfurization liquid.

[0020] The gas distributor is a microporous aeration disc or a swirl aerator with an aeration orifice diameter of 10-200 micrometers; the aeration blower is a variable frequency blower, and its air volume can be adjusted according to the feedback signal from the control unit. Specifically, the gas distributor uses a microporous aeration disc or a cyclone aerator, with its aeration pore size precisely controlled within the range of 10-200 micrometers. This pore size specification can cut oxygen-containing gas into micron-sized microbubbles, significantly increasing the contact area and contact time between the gas and the desulfurization liquid, effectively improving the gas-liquid mass transfer efficiency, and thus accelerating the regeneration reaction rate of Fe²⁺ being oxidized to Fe³⁺, ensuring the regeneration effect of the desulfurization liquid in the regeneration unit. The structural design of the microporous aeration disc or cyclone aerator is adapted to the bottom arrangement requirements of the desulfurization liquid tank in the regeneration unit, ensuring good gas distribution uniformity and allowing the desulfurization liquid and oxygen-containing gas to mix thoroughly, avoiding the problem of insufficient local regeneration. The aeration blower is a variable frequency blower, electrically linked to the control unit. It can receive feedback signals such as ORP, pH value, and Fe²⁺ / Fe³⁺ ratio from the control unit in real time, and adjust the air volume precisely according to signal changes: when the Fe²⁺ concentration in the desulfurization liquid is high and the regeneration demand is large, the control unit issues a command to increase the blower's frequency conversion frequency, increasing the aeration volume; when the Fe²⁺ concentration drops to a reasonable range and the regeneration demand decreases, the frequency conversion frequency is simultaneously reduced, decreasing the aeration volume. Through this variable frequency adjustment method, the regeneration efficiency of the desulfurization liquid is matched with the desulfurization load, while avoiding energy waste caused by excessive aeration, achieving energy-saving and efficient operation of the regeneration unit.

[0021] The monitoring unit includes an online monitoring module for iron ion valence state, an ORP monitoring module, a pH monitoring module, a complexing agent concentration monitoring module, and a desulfurizing agent performance evaluation module. The probe end of each monitoring module extends into the desulfurization liquid of the desulfurization tower and / or regeneration unit, and the signal output end of each monitoring module is electrically connected to the control unit. Specifically, the monitoring unit serves as the core of the entire system's perception. Each monitoring module, based on the monitoring requirements of the desulfurization process, is deployed at key flow points of the desulfurized liquid in the desulfurization tower and regeneration unit. The probes of each module extend directly into the desulfurized liquid, ensuring the real-time nature and accuracy of the detection data. Furthermore, the signal outputs of all monitoring modules are electrically connected to the control unit via communication lines, enabling real-time transmission of collected desulfurized liquid parameters to the control unit, providing precise and comprehensive data source support for the control unit's intelligent regulation. Specifically, the online iron ion valence state monitoring module is dedicated to real-time monitoring of iron ion valence state changes in the desulfurized liquid and is the core monitoring module for stable iron ion circulation control. The ORP monitoring module and pH monitoring module are basic parameter monitoring modules, accurately detecting the redox potential and pH of the desulfurized liquid, providing fundamental data for iron ion valence state calculation and regeneration process regulation. The complexing agent concentration monitoring module captures real-time changes in the effective concentration of the complexing agent in the desulfurized liquid, ensuring the accuracy of automatic complexing agent compensation. The desulfurizing agent performance evaluation module comprehensively collects multi-dimensional parameters of the desulfurized liquid, providing data for assessing the aging degree of the desulfurizing agent. Each monitoring module works independently yet cooperates with each other to form a comprehensive, multi-dimensional desulfurization liquid parameter monitoring system. This enables real-time sensing of parameters throughout the entire desulfurization and regeneration process, ensuring that the control unit can adjust system operating parameters promptly and accurately based on the monitoring data.

[0022] The online monitoring module for iron ion valence state is designed based on the principle of potentiometric method. The control unit has a built-in Nernst equation calculation model. After the ORP monitoring module and pH monitoring module transmit the detected ORP value and pH value to the control unit, the control unit calculates the ratio of Fe²⁺ / Fe³⁺ in the desulfurization liquid through the Nernst equation. Specifically, the online iron ion valence state monitoring module uses potentiometry as its core detection principle. This principle is suitable for the complex operating conditions of desulfurization liquid, enabling continuous and accurate detection of iron ion valence state-related parameters without the need for manual sampling and analysis, thus significantly improving monitoring efficiency. The ORP monitoring module and pH monitoring module transmit the real-time measured values ​​of the desulfurization liquid's oxidation-reduction potential and pH value to the control unit via an electrically connected communication link, providing accurate basic data support for the calculation of the Fe²⁺ / Fe³⁺ ratio. The control unit has a pre-installed Nernst equation calculation model, which has completed the solidification settings of key parameters such as the gas constant, Faraday constant, and electron transfer number. It can automatically substitute the received measured ORP value and pH value into the Nernst equation E=E°+(RT / nF)×ln([Fe³⁺] / [Fe²⁺])-0.059×pH for calculation.

[0023] During the calculation process, the control unit automatically calculates and derives the actual Fe²⁺ / Fe³⁺ ratio in the desulfurization liquid based on the equation. The entire calculation process is automated, with a fast response speed, and can output the iron ion valence state ratio in real time. This method overcomes the lag problem of traditional manual sampling and monitoring, accurately capturing the dynamic changes in the iron ion valence state in the desulfurization liquid. This provides a core basis for the intelligent control of subsequent regeneration unit operating parameters, ensuring that the Fe²⁺ / Fe³⁺ ratio is always maintained within the optimal range for the desulfurization reaction.

[0024] The complexing agent concentration monitoring module uses spectrophotometry or ion chromatography to achieve online monitoring of the complexing agent concentration; the monitoring unit also includes a temperature monitoring module, the probe of which is arranged on the flow path of the desulfurization liquid, and the signal output of which is electrically connected to the control unit. The temperature monitoring module is used to monitor the temperature of the desulfurization liquid and maintain the temperature within the range of 25-45℃. Specifically, the detection data is transmitted to the control unit in real time via the signal output terminal, providing direct data support for the automatic and accurate replenishment of the complexing agent, effectively avoiding over- or under-replenishment problems caused by lag in complexing agent concentration monitoring. Spectrophotometry calculates the concentration by detecting changes in absorbance of the complexing agent's characteristic absorption spectrum, while ion chromatography achieves quantitative concentration by separating and detecting complexing agent ions. Both detection methods meet the accuracy and real-time requirements of online monitoring and are adaptable to the detection needs of different projects.

[0025] The monitoring unit is equipped with a temperature monitoring module. Its probes are precisely positioned along the key flow paths of the desulfurized liquid in the desulfurization tower and regeneration unit, enabling comprehensive capture of the actual temperature of the desulfurized liquid. The module's signal output is electrically connected to the control unit, synchronously transmitting real-time temperature data to the control unit, forming a closed-loop temperature monitoring system. The core monitoring range of the temperature monitoring module is precisely locked within the optimal reaction temperature range of 25-45℃ for the desulfurized liquid. When the temperature of the desulfurized liquid exceeds this range, the control unit can immediately trigger a linkage control command to regulate the start and stop of the cooling / heating devices in the auxiliary unit, promptly restoring the desulfurized liquid temperature back to the 25-45℃ range, ensuring the rate and efficiency of the desulfurization and regeneration reactions.

[0026] The auxiliary unit includes an iron ion complexing agent storage tank, a complexing agent storage tank, a metering pump, a replenishment pipeline, an aging desulfurizing agent discharge system, and a cooling / heating device. The outlet of the complexing agent storage tank is connected to the inlet of the metering pump through the replenishment pipeline, and the outlet of the metering pump is connected to the medium replenishment port of the desulfurization tower and / or regeneration unit. The heat exchange end of the cooling / heating device extends into the desulfurization liquid tank of the desulfurization tower and / or regeneration unit, and the controlled end of the cooling / heating device is electrically connected to the control unit. Specifically, the auxiliary unit serves as the core unit for the system's medium replenishment, temperature control, and waste liquid discharge. Each component works in a coordinated manner to provide comprehensive protection for the stable operation of the desulfurization and regeneration processes. Among them, the iron ion complexing agent storage tank and the complexing agent storage tank are independent storage structures, used to store iron ion complexing agent solution and complexing agent stock solution respectively, to achieve classified and sealed storage of different agents, avoid agent mixing and failure, and ensure agent storage stability. The desulfurizing agent discharge system is connected to the aging desulfurized liquid discharge outlet of the regeneration unit. Based on instructions from the control unit according to the desulfurizing agent aging index, it automatically initiates the discharge process to promptly discharge aged, deactivated, and excessively impurity-laden desulfurized liquid from the system, preventing it from affecting overall desulfurization efficiency and providing a channel for agent renewal. The cooling / heating device is an integrated heat exchange structure, with its heat exchange end directly extending into the desulfurization tower and / or the desulfurized liquid tank of the regeneration unit, ensuring full contact with the desulfurized liquid and high heat exchange efficiency. The controlled end of this device is electrically connected to the control unit, allowing it to receive real-time temperature monitoring data from the control unit. When the desulfurized liquid temperature exceeds 45℃, the control unit triggers the cooling device's start / stop command, achieving rapid cooling of the desulfurized liquid through the heat exchange end. When the desulfurized liquid temperature falls below 25℃, the control unit simultaneously triggers the heating device's start / stop command, precisely heating the desulfurized liquid through the heat exchange end. This achieves automatic and precise temperature control within the optimal reaction range of 25-45℃, ensuring the rate and stability of the desulfurization and regeneration reactions. All pipe connections use sealed flanges or quick-connect structures.

[0027] The desulfurization tower is a packed tower, a spray tower, a bubbling tower, or a combined bubbling-spraying desulfurization tower. The combined bubbling-spraying desulfurization tower includes a primary submerged bubbling section and a secondary above-liquid double-layer spraying section. The desulfurization tower is filled with bulk packing material, which is polypropylene or stainless steel. Specifically, the desulfurization tower, as the core reaction unit for biogas desulfurization, is adapted to engineering requirements with different biogas treatment loads and hydrogen sulfide concentrations. It is available in various structural forms, including packed towers, spray towers, bubbling towers, and combined bubbling-spray desulfurization towers. The desulfurization towers are all filled with bulk packing material, made of polypropylene or stainless steel, suitable for the alkaline conditions of biogas desulfurization. This packing material is corrosion-resistant, wear-resistant, and does not easily scale, effectively increasing the contact area and contact time between the gas and liquid phases, enhancing the mass transfer reaction, and avoiding the problem of reduced desulfurization efficiency due to insufficient contact between biogas and desulfurization liquid. Polypropylene packing is lightweight and low-cost, suitable for medium- and low-load desulfurization conditions, while stainless steel packing is high-strength and has good temperature resistance, suitable for high-load, high-temperature industrial-grade biogas desulfurization conditions. The choice of either packing material can be flexibly made according to actual engineering requirements.

[0028] The control unit incorporates an ORP-pH-Fe²⁺ / Fe³⁺ relationship model, an automatic compensation calculation model for complexing agents, and an aging index calculation model for desulfurizers. Based on an intelligent control strategy that couples ORP and pH parameters, the control unit calculates the required ORP setpoint according to the target Fe²⁺ / Fe³⁺ ratio and adjusts the aeration rate or electrolysis current of the regeneration unit according to the deviation between the actual ORP and the setpoint. Specifically, the control unit adopts an intelligent control strategy that couples ORP and pH parameters, overcoming the limitations of traditional single-parameter control. First, based on the target Fe²⁺ / Fe³⁺ ratio set in the process, it is substituted into the ORP-pH-Fe²⁺ / Fe³⁺ relationship model. Combined with the real-time monitored pH value, the required ORP setpoint under the current operating conditions is automatically calculated, forming a precise control benchmark. Then, the actual ORP value transmitted by the monitoring unit is compared with this setpoint in real time. Based on the magnitude and trend of the deviation, precise control commands are issued to the regeneration unit: when the actual ORP value is lower than the setpoint, it indicates that the Fe²⁺ concentration in the desulfurization liquid is too high and the regeneration demand is increased. The control unit will gradually increase the aeration rate of the regeneration unit, and if necessary, adjust the electrolysis current to accelerate the Fe²⁺ oxidation and regeneration rate. When the actual ORP value is higher than the setpoint, it indicates that the Fe³⁺ concentration has reached the optimal range and the regeneration demand is reduced. The control unit will gradually decrease the aeration rate or reduce the electrolysis current to avoid energy waste and side reactions caused by excessive regeneration. The entire control process is a closed-loop intelligent control system with fast response speed and high control accuracy. It can match the load changes of the desulfurization process in real time and ensure that the Fe²⁺ / Fe³⁺ ratio in the desulfurization liquid is always maintained within the optimal reaction range.

[0029] The control unit is a PLC control system, equipped with an operator station, an engineer station, and a field control station; the auxiliary unit also includes a sulfur separation system, the feed end of which is connected to the sulfur discharge outlet of the regeneration unit; Specifically, the control unit adopts an industrial-grade PLC control system, which serves as the intelligent control center of the entire desulfurization system. It forms a three-level control architecture by configuring operator stations, engineer stations, and field control stations. Each station has its own division of labor and cooperation, and data communication, so as to achieve hierarchical and precise control of the system. The sulfur separation system added to the auxiliary unit is a core component for byproduct recovery in the desulfurization process. Its feed end is seamlessly connected to the sulfur discharge outlet of the regeneration unit via a sealed pipeline. The elemental sulfur suspension generated by the desulfurization reaction in the regeneration unit can be directly transported to the sulfur separation system. This system performs solid-liquid separation of the sulfur suspension through physical separation, efficiently separating the elemental sulfur and achieving sulfur recovery and reuse. This reduces solid waste emissions and allows the recovered sulfur to generate additional benefits as an industrial raw material. Simultaneously, the separated clarified liquid can be returned to the regeneration unit to continue participating in the desulfurization reaction, effectively reducing the loss of desulfurization liquid and further improving the system's resource utilization rate and operational economy. The sulfur separation system is adapted to the sulfur discharge rhythm of the regeneration unit, enabling continuous or intermittent sulfur separation to meet the byproduct recovery needs under different desulfurization loads.

[0030] Example: Complexed iron desulfurization system for a large-scale biogas project with a daily biogas processing capacity of 20,000 m³ This embodiment is applied to the biogas project of a comprehensive organic waste treatment plant in a city. The project produces about 20,000 m³ of biogas per day, and the hydrogen sulfide content in the biogas is 8,000-10,000 ppm. It is required that the hydrogen sulfide content after desulfurization is less than 20 ppm to meet the standards for natural gas for vehicles.

[0031] The intelligent regeneration and iron ion circulation stabilization control system for complexed iron desulfurizer in this embodiment includes the following main components: Desulfurization tower system Specifications: Tower diameter 2.0m, tower height 7m, designed gas processing capacity 20000m³ / d, inlet hydrogen sulfide concentration 10000ppm, outlet hydrogen sulfide concentration 20ppm. Process structure: Bubble-spray combined desulfurization tower Primary desulfurization (subsurface bubbling section): Employing subsurface bubbling technology, this section handles the main desulfurization load, reducing the inlet hydrogen sulfide concentration from 8000-10000 ppm to below 800 ppm, with a removal rate ≥90%. Secondary desulfurization (liquid-based double-layer spray section): Equipped with a double-layer spray device to precisely remove residual hydrogen sulfide, ensuring that the hydrogen sulfide concentration in the effluent is stably controlled below 20 ppm. Aeration Regeneration Unit The aeration blower is a Roots blower with an air volume of 400 m³ / h and an air pressure of 50 kPa, equipped with a frequency converter. The gas distributor uses a microporous aerator, which is arranged at the bottom of the regeneration tank to improve the gas-liquid mass transfer efficiency.

[0032] Monitoring Unit Online monitoring module for iron ion valence state ORP and pH electrodes are installed on the regeneration tank to achieve comprehensive monitoring of the desulfurization solution's condition. The ORP electrode is an industrial-grade composite electrode equipped with automatic temperature compensation and automatic cleaning functions. The pH electrode is a fouling-resistant electrode equipped with an automatic cleaning device.

[0033] Complexing agent concentration monitoring module The concentration of iron ions in the desulfurization liquid was monitored using a portable spectrophotometer with a detection accuracy of ±1% and a detection cycle of 24 hours.

[0034] Desulfurizer performance evaluation module Establish a comprehensive evaluation system, monitoring parameters including: -Desulfurization efficiency: Hydrogen sulfide concentration before and after desulfurization is monitored using an H2S analyzer. - Iron ion concentration: Weekly sampling and analysis of total iron concentration and Fe²⁺ / Fe³⁺ ratio - Complexing agent concentration: Monitor EDTA concentration daily. - Impurity content: Monthly analysis of suspended solids, heavy metal ions, and other impurities in the desulfurization solution. -Color change: Monitoring the color change of the desulfurization liquid using a color sensor. Control Unit The control unit employs a PLC control system, configured with operator stations, engineer stations, and field control stations. The main control strategies include: Regeneration control strategy The aeration regeneration air volume is controlled according to the desulfurization load and the Fe²⁺ / Fe³⁺ ratio.

[0035] ORP-pH dual-parameter coupling control Establish an ORP-pH-Fe²⁺ / Fe³⁺ relationship database. By querying the database using real-time monitored ORP and pH values, obtain the current Fe²⁺ / Fe³⁺ ratio. Based on the target Fe²⁺ / Fe³⁺ ratio (set to 0.4), calculate the required ORP setting value: E_set=E°-(RT / nF)×ln(0.4)-0.059×pH The control system uses a PID algorithm to adjust the aeration rate and electrolysis current based on the deviation between the measured ORP value and the set value.

[0036] Intelligent complexing agent compensation control A desulfurization load prediction model was established to predict the desulfurization load for the next two hours based on historical data and current operating conditions. The formula for calculating the complexing agent replenishment amount is as follows: V_add=k1×Q_pred×C_H2S_pred×2+k2×V_total×(C_target-C_actual)+k3×V_total×AI Where Q_pred is the predicted biogas flow rate, C_H2S_pred is the predicted hydrogen sulfide concentration, and AI is the aging index.

[0037] Calculation of the aging index AI: AI=0.3×(1-η / η0)+0.25×(1-A_Fe / A_Fe0)+0.25×(1-C_L / C_L0)+0.15×(I_impurity / I_impurity0)+0.05×ΔColor When AI > 0.3, a yellow alert is issued, and the amount of complexing agent replenished is increased by 20%; when AI > 0.5, an orange alert is issued, and the amount of complexing agent replenished is increased by 50% and the system is inspected; when AI > 0.7, a red alert is issued, and the desulfurizer is replaced.

[0038] Temperature control strategy The temperature of the desulfurization liquid is controlled within the range of 30-40℃. When the temperature is below 30℃, the heating device is activated; when the temperature is above 40℃, the cooling device is activated. Temperature control and regeneration control are linked; if the temperature is too low, the regeneration intensity is appropriately reduced to avoid an increase in side reactions.

[0039] Auxiliary Unit Iron ion complexing agent storage tank: 1m³ volume, storing 3% iron ion solution.

[0040] Metering pump system: 3 metering pumps are used (2 in use and 1 on standby), with a flow rate of 0-20L / h per pump.

[0041] Sulfur separation system: gas diaphragm plate and frame filter press, which realizes continuous separation and recovery of sulfur.

[0042] Cooling / Heating System: The system uses stainless steel coils for heat exchange inside the regeneration tank. The cooling medium is circulating cooling water, and the heating medium is hot water recovered from waste heat in the refrigeration system or low-pressure steam from the plant area.

[0043] Running result: After the system in this embodiment was put into operation, the following effects were achieved: The desulfurization efficiency is consistently above 99.8%, and the hydrogen sulfide content in the purified biogas is consistently 10-15 ppm, meeting the vehicle natural gas standard (GB18047-2017).

[0044] The system is highly adaptable to load fluctuations. When the biogas flow rate fluctuates within the range of 10,000-15,000 m³ / d, the desulfurization efficiency remains above 99.6%.

[0045] The proportion of Fe³⁺ in the total iron concentration remained stable at 70%-80%, and the Fe²⁺ / Fe³⁺ ratio was controlled within the range of 0.25-0.4, indicating stable iron ion cycling.

[0046] Iron ion consumption has been reduced from approximately 1,500 kg per month to 1,000 kg, saving 33% in drug costs.

[0047] The sulfur recovery rate reaches over 95%, and the purity of the recovered sulfur reaches over 85%, making it suitable for sale as an industrial raw material.

[0048] The system is highly automated, requiring only one operator per shift.

[0049] The desulfurizer aging early warning system successfully prevented two accidents that could have resulted in excessive hydrogen sulfide emissions due to deterioration of desulfurizer performance.

[0050] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A complex iron desulfurizer intelligent regeneration and iron ion circulation stable control system, characterized in that, It includes a desulfurization tower, regeneration unit, monitoring unit, control unit, and auxiliary unit; The desulfurization tower is used to bring biogas containing hydrogen sulfide into contact with complexed iron desulfurizing agent to produce a desulfurization reaction and remove hydrogen sulfide from the biogas. The desulfurization liquid outlet of the desulfurization tower is connected to the liquid inlet of the regeneration unit. The outlet of the regeneration unit is connected to the desulfurization liquid inlet of the desulfurization tower to realize the circulation and transportation of the desulfurization liquid. Each monitoring probe of the monitoring unit is arranged on the desulfurization liquid flow path of the desulfurization tower and the regeneration unit, and the signal output terminal of the monitoring unit is electrically connected to the signal input terminal of the control unit. The control signal output terminal of the control unit is electrically connected to the controlled terminals of the regeneration unit and the auxiliary unit, respectively. The auxiliary unit's media output end is connected to the media replenishment port of the desulfurization tower and / or regeneration unit, and the auxiliary unit's discharge end is connected to the aging desulfurization liquid discharge port of the regeneration unit.

2. The complex iron desulfurizer intelligent regeneration and iron ion circulation stability control system according to claim 1, characterized in that, The regeneration unit is an aeration regeneration module, which includes an aeration blower, a gas distributor, a gas-liquid separator, and a tail gas treatment device. The outlet of the aeration blower is connected to the gas distributor, which is located at the bottom of the desulfurization liquid tank of the regeneration unit. The gas-liquid separator is connected to the gas phase outlet of the regeneration unit, and the tail gas treatment device is connected to the tail gas discharge end of the gas-liquid separator.

3. The complex iron desulfurizer intelligent regeneration and iron ion circulation stability control system according to claim 2, characterized in that, The gas distributor is a microporous aeration disc or a swirl aerator with an aeration aperture of 10-200 micrometers; the aeration blower is a variable frequency blower, and its air volume can be adjusted according to the feedback signal from the control unit.

4. The complex iron desulfurizer intelligent regeneration and iron ion circulation stability control system according to claim 1, characterized in that, The monitoring unit includes an online monitoring module for iron ion valence state, an ORP monitoring module, a pH monitoring module, a complexing agent concentration monitoring module, and a desulfurizing agent performance evaluation module. The probe end of each monitoring module extends into the desulfurization liquid of the desulfurization tower and / or regeneration unit, and the signal output end of each monitoring module is electrically connected to the control unit.

5. The intelligent regeneration and iron ion circulation stabilization control system for complexed iron desulfurizer according to claim 4, characterized in that, The online monitoring module for iron ion valence state is designed based on the potentiometric principle. The control unit has a built-in Nernst equation calculation model. After the ORP monitoring module and pH monitoring module transmit the detected ORP value and pH value to the control unit, the control unit calculates the ratio of Fe²⁺ / Fe³⁺ in the desulfurization liquid using the Nernst equation.

6. The intelligent regeneration and iron ion circulation stabilization control system for complexed iron desulfurizer according to claim 4, characterized in that, The complexing agent concentration monitoring module uses spectrophotometry or ion chromatography to achieve online monitoring of the complexing agent concentration; the monitoring unit also includes a temperature monitoring module, the probe of which is arranged on the flow path of the desulfurization liquid, and the signal output of which is electrically connected to the control unit. The temperature monitoring module is used to monitor the temperature of the desulfurization liquid and maintain it within the range of 25-45℃.

7. The complex iron desulfurizer intelligent regeneration and iron ion circulation stability control system according to claim 1, characterized in that, The auxiliary unit includes an iron ion complexing agent storage tank, a complexing agent storage tank, a metering pump, a replenishment pipeline, an aging desulfurizing agent discharge system, and a cooling / heating device. The outlet of the complexing agent storage tank is connected to the inlet of the metering pump through the replenishment pipeline, and the outlet of the metering pump is connected to the medium replenishment port of the desulfurization tower and / or regeneration unit. The heat exchange end of the cooling / heating device extends into the desulfurization liquid tank of the desulfurization tower and / or regeneration unit, and the controlled end of the cooling / heating device is electrically connected to the control unit.

8. The complex iron desulfurizer intelligent regeneration and iron ion circulation stability control system according to claim 1, characterized in that, The desulfurization tower is a packed tower, a spray tower, a bubbling tower, or a combined bubbling-spraying desulfurization tower. The combined bubbling-spraying desulfurization tower includes a primary submerged bubbling section and a secondary above-liquid double-layer spraying section. The desulfurization tower is filled with bulk packing material, which is polypropylene or stainless steel.

9. The complex iron desulfurizer intelligent regeneration and iron ion circulation stability control system according to claim 1, characterized in that, The control unit incorporates an ORP-pH-Fe²⁺ / Fe³⁺ relationship model, an automatic compensation calculation model for complexing agents, and an aging index calculation model for desulfurizers. Based on an intelligent control strategy that couples ORP and pH parameters, the control unit calculates the required ORP setpoint according to the target Fe²⁺ / Fe³⁺ ratio and adjusts the aeration rate or electrolysis current of the regeneration unit according to the deviation between the actual ORP and the setpoint.

10. The complex iron desulfurizer intelligent regeneration and iron ion circulation stability control system according to claim 9, characterized in that, The control unit is a PLC control system, equipped with an operator station, an engineer station, and a field control station; the auxiliary unit also includes a sulfur separation system, the feed end of which is connected to the sulfur discharge outlet of the regeneration unit.

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