An scr system spent catalyst treatment and application recovery system and control method

Abstract

This invention relates to the field of environmental protection and resource recycling technology in coal-fired power plants, and discloses a waste catalyst treatment and recycling system and control method for SCR systems. The waste catalyst treatment and recycling system includes a waste catalyst collection and conveying unit, a pretreatment unit, an air preheater online heating and co-treatment unit, and a recycling unit. The waste catalyst collection and conveying unit sequentially includes a waste catalyst collection port, a collection bin, and a conveying device, with the collection port located at the outlet of the SCR system. The pretreatment unit is arranged in conjunction with the outlet of the conveying device, and sequentially includes a crushing device, a screening device, and a preliminary cleaning device. The air preheater online heating and co-treatment unit is arranged in conjunction with the outlet of the preliminary cleaning device, and includes a waste catalyst spraying device, a hot air introduction device, and the air preheater body. This invention aims to reduce processing costs, minimize waste, and prevent air preheater blockage.

Description

Technical Field

[0001] This invention relates to the field of environmental protection and resource recycling technology in coal-fired power plants, specifically to a waste catalyst treatment and recycling system and control method for SCR systems. Background Technology

[0002] In coal-fired power plants, selective catalytic reduction (SCR) systems are widely used in denitrification processes. After prolonged use, the catalysts in these systems become deactivated due to poisoning, ash accumulation, and other reasons, becoming spent catalysts. These spent catalysts contain large amounts of heavy metals and catalytically active substances; if not properly treated, they not only pollute the environment but also waste valuable resources. Meanwhile, the air preheater, as a crucial piece of equipment in coal-fired power plants, is prone to blockage during operation due to ash accumulation and scaling, affecting its heat exchange efficiency and the overall economic efficiency of the power plant.

[0003] Currently, online heating is a commonly used method for dealing with air preheater blockage. However, this method is often used alone and not effectively combined with the treatment of spent catalyst. Traditional methods for treating spent catalyst typically involve centralized collection and transportation to specialized treatment plants. This process is complex and costly, and it cannot alleviate air preheater blockage in real time during power plant operation. Summary of the Invention

[0004] To address existing problems, this invention aims to provide a waste catalyst treatment and recycling system and control method for SCR systems, solving the problems of high waste catalyst treatment costs, resource waste, and easy clogging of air preheaters in existing technologies. This system provides a resource-optimized path, which can effectively pre-treat and recycle waste catalysts while achieving online anti-clogging of air preheaters, thereby improving the environmental and economic benefits of power plants.

[0005] To achieve the above objectives, the present invention provides the following technical solution.

[0006] This invention provides a waste catalyst treatment and recycling system for an SCR system, comprising a waste catalyst collection and conveying unit, a pretreatment unit, an air preheater online heating and co-treatment unit, and a recycling unit. The waste catalyst collection and conveying unit sequentially includes a waste catalyst collection port, a collection bin, and a conveying device, with the collection port located at the outlet of the SCR system. The pretreatment unit is arranged in conjunction with the outlet of the conveying device, and sequentially includes a crushing device, a screening device, and a preliminary cleaning device. The air preheater online heating and co-treatment unit is arranged in conjunction with the outlet of the preliminary cleaning device, and includes a waste catalyst spraying device, a hot air introduction device, and an air preheater body. The outlet of the air preheater body is connected to the SCR system. Both the outlet of the air preheater body and the outlet of the preliminary cleaning device are connected to the recycling unit.

[0007] As a further improvement of the present invention, the air preheater online heating and collaborative processing unit further includes a temperature sensor, a pressure sensor and a PLC; the temperature sensor and the pressure sensor are respectively installed at the flue gas inlet section and the hot air outlet section inside the air preheater; the temperature sensor and the pressure sensor are respectively electrically connected to the PLC.

[0008] As a further improvement of the present invention, the temperature sensor is externally wrapped with a protective sleeve; the pressure sensor is selected as a differential pressure sensor, which includes an anti-clogging diaphragm, and the surface of the anti-clogging diaphragm is coated with Teflon.

[0009] As a further improvement of the present invention, the pretreatment unit is arranged vertically in sequence with a crushing device, a screening device and a preliminary cleaning device; the preliminary cleaning device employs ultrasonic cleaning and chemical cleaning.

[0010] As a further improvement of the present invention, the chemical cleaning uses 5% nitric acid.

[0011] As a further improvement of the present invention, the pretreatment unit further includes an activity detection device; the activity detection device is connected to the outlet of the preliminary cleaning device.

[0012] As a further improvement of the present invention, the waste catalyst collection port is connected to a collection chamber; the collection chamber includes a vibration device.

[0013] As a further improvement of the present invention, the recovery unit includes a metal extraction device and a catalyst regeneration device; the metal extraction device is filled with a 10% sulfuric acid solution; the catalyst regeneration device includes a combustion furnace and a reactor, the reactor being provided with a sodium hydroxide solution.

[0014] This invention also provides a control method for the treatment and recycling of spent catalysts in an SCR system, comprising the following steps:

[0015] When the amount of waste catalyst accumulated in the collection chamber reaches 80%, increase the conveying speed of the conveying device;

[0016] The spent catalyst, after being conveyed to the crushing unit, is divided into two parts: the portion with a particle size of less than 10 mm is conveyed to the screening unit; the portion with a particle size of more than 10 mm is conveyed to the recycling unit.

[0017] The spent catalyst, after being conveyed to the screening device, is sent to the preliminary cleaning device for particles smaller than 5 mm, and to the recycling unit for particles larger than 5 mm.

[0018] The spent catalyst at the outlet of the preliminary cleaning unit, with the portion having an activity exceeding 30%, is sent to the air preheater; the portion with an activity below 30% is sent to the recovery unit.

[0019] When the pressure difference between the pressure sensors exceeds the set threshold, the control system activates the hot air introduction device.

[0020] When the maximum value obtained by the temperature sensor of the air preheater exceeds the set upper limit, the fuel supply of the hot air introduction device is reduced.

[0021] The present invention also provides a control system for the treatment and recycling of spent catalysts in an SCR system, including a main control module, an auxiliary control module and a safety monitoring module;

[0022] The main control module includes a control unit; the control unit is electrically connected to the weighing device, activity detection device, pressure sensor, temperature sensor and hot air introduction device of the collection bin;

[0023] The auxiliary control module includes a high-pressure flushing water submodule and a sealing control submodule;

[0024] The safety monitoring module includes an air preheater surface temperature detection submodule and an air preheater inlet and outlet CO concentration detection submodule.

[0025] The present invention has the following beneficial effects:

[0026] This system achieves one-stop processing from collection to resource recovery through a series design of waste catalyst collection, pretreatment, air preheater co-processing, and recycling units, reducing the transportation costs and environmental pollution risks of waste catalysts. The air preheater is used as a high-temperature treatment unit, utilizing its existing heat source to spray the waste catalyst, reducing energy consumption and improving the anti-clogging effect and system efficiency of the air preheater. At the same time, the outlet of the air preheater is connected to the recycling unit, ensuring that the treated waste catalyst can directly enter the regeneration or metal extraction process, avoiding secondary pollution.

[0027] Preferably, the internal operating conditions of the air preheater are monitored in real time by temperature and pressure sensors, and the PLC automatically adjusts the hot air introduction volume to ensure that the processing temperature is stable within the optimal range (such as 300-500℃), preventing catalyst sintering or insufficient processing; pressure differences can often trigger the hot air introduction device to start, preventing blockage or local overheating and improving system safety.

[0028] Preferably, the protective sleeve and Teflon coating can resist corrosion from high-temperature flue gas (such as SO2, NO). X To prevent particle wear and ensure long-term stable operation and extend service life; the anti-clogging diaphragm reduces dust adhesion and avoids malfunctions caused by pressure sensor failure.

[0029] Preferably, the vertical layout of the pretreatment device can save space, and the material can be directly screened after crushing to avoid material backflow; the combination of ultrasonic and chemical cleaning can thoroughly remove ash and heavy metals from the catalyst surface and improve the subsequent regeneration efficiency; the gentle cleaning method reduces the loss of catalyst active components (such as V2O5).

[0030] Preferably, low-concentration nitric acid dissolves only a portion of the binder (such as Al2O3), retaining the active ingredients and avoiding excessive dissolution that could damage the catalyst structure. Compared to strong acids such as concentrated hydrochloric acid, nitric acid is less corrosive to equipment and has lower wastewater treatment costs.

[0031] Preferably, based on the activity test results, highly active spent catalysts (>30%) are returned to the air preheater for reuse, while those with low activity are sent to the recycling unit to maximize resource utilization; the activity test device provides data support for the performance evaluation of the regenerated catalyst.

[0032] Preferably, the vibration device prevents waste catalyst from bridging or clumping in the collection bin, ensuring continuous and stable conveying; it is linked with the conveying device to automatically accelerate conveying when the material level reaches 80%, avoiding overflow.

[0033] Preferably, 10% sulfuric acid can dissolve metals such as aluminum and vanadium in the waste catalyst, producing a reaction such as V₂O₅→VO₂O₃. 2+ The reaction; sodium hydroxide solution neutralizes acidic substances such as SO3 in the reactor, inhibits the formation of by-products, and improves the sulfur resistance of the regenerated catalyst.

[0034] The control method of this invention achieves intelligent regulation of the entire process through particle size classification, activity screening (>30%), and pressure / temperature threshold control, reducing manual intervention; when the air preheater temperature exceeds the standard, it automatically reduces the fuel supply to avoid energy waste.

[0035] The control system of this invention provides multi-level safety protection. The main control module is used to integrate key parameters (material level, activity, temperature) and work with the actuator to achieve global control. The safety monitoring module detects CO concentration to prevent explosions caused by unburned catalyst. The air preheater surface temperature monitoring avoids damage to refractory materials. The high-pressure flushing water submodule can be remotely started to quickly clear pipe blockages. Attached Figure Description

[0036] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of the invention in any way. Furthermore, the shapes and proportions of the components in the drawings are merely schematic to aid in understanding the invention and are not intended to specifically limit the shapes and proportions of the components. In the drawings:

[0037] Figure 1 This is a schematic diagram of a waste catalyst treatment and recycling system for an SCR system, as shown in the embodiment.

[0038] Figure 2 This is a diagram illustrating the working steps of the preprocessing unit in the embodiment;

[0039] Figure 3 This is a schematic diagram of the preliminary cleaning device structure in the embodiment;

[0040] Figure 4 This is a schematic diagram showing the arrangement of the temperature and pressure sensors in the embodiment.

[0041] The components include: 1. Waste catalyst collection port; 2. Collection bin; 3. Vibration device; 4. Screw conveyor; 5. Crushing device; 6. Screening device; 7. Preliminary cleaning device; 8. Air preheater body; 9. Temperature sensor; 10. Pressure sensor; 11. Hot air introduction device; 12. Waste catalyst spraying device; 13. Metal extraction device; 14. Catalyst regeneration device; 71. Cleaning tank; 72. Ultrasonic transducer; 73. Chemical spray head; 74. Circulating filter pump; 91. Inlet temperature sensor; 92. Heat exchange surface temperature sensor; 93. Outlet temperature sensor; 94. Protective sleeve; 95. Temperature control box; 101. Inlet pressure measuring point; 102. Outlet pressure measuring point; 103. Differential pressure calculation module; 121. Waste catalyst spray head. Detailed Implementation

[0042] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0043] It should be noted that when an element is referred to as being "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only embodiments.

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0045] like Figure 1 As shown, an SCR system waste catalyst treatment and recycling system includes a waste catalyst collection and conveying unit, a pretreatment unit, an air preheater online heating and co-treatment unit, and a recycling unit; the waste catalyst collection and conveying unit includes a waste catalyst collection port 1, a collection chamber 2, and a conveying device in sequence, with the waste catalyst collection port 1 located at the outlet of the SCR system.

[0046] The pretreatment units are arranged in conjunction with the outlets of the conveying devices. The pretreatment units consist of a crushing device 5, a screening device 6, a preliminary cleaning device 7, and an activity detection device arranged vertically in sequence. The preliminary cleaning device 7 employs ultrasonic cleaning and chemical cleaning. The activity detection device is connected to the outlet of the preliminary cleaning device 7. During operation, if... Figure 2 As shown, the spent catalyst first enters the crushing device 5, where large pieces of catalyst are broken into smaller particles for easier subsequent processing. The crushed particles then pass through the screening device 6 to separate particles of different sizes. Smaller particles (<5mm) with fewer impurities directly enter the preliminary cleaning device 7, where ultrasonic cleaning combined with chemical cleaning solution removes surface dust and some impurities. Larger particles or particles with more impurities (5-10mm) enter the grinding device for further refinement before cleaning. The cleaned spent catalyst is divided into two parts: one part, with relatively high activity (not less than 30%), enters the air preheater online heating and co-processing unit, while the other part, with lower activity, enters the recovery unit.

[0047] Specifically, such as Figure 3As shown, the preliminary cleaning device 7 is a box-like structure, containing a cleaning tank 71, an ultrasonic transducer 72, a chemical spray head 73, and a circulating filter pump 74. The cleaning tank 71 and ultrasonic transducer 72 are located at the bottom of the box; the chemical spray head 73 is located at the top; and the circulating filter pump 74 is located outside the box, connected to both the chemical spray head 73 and the cleaning tank 71 via pipelines. During operation, the circulating filter pump 74 drives the cleaning fluid to circulate and filter impurities, maintaining system cleanliness. The chemical spray head 73 receives the driving pressure from the circulating filter pump 74 and sprays the chemical cleaning agent directionally onto the dispersed waste catalyst within the box. Simultaneously, the ultrasonic waves generated by the high-frequency vibration of the ultrasonic transducer 72 transfer energy through the liquid, removing dirt from the workpiece surface. Optionally, ultrasonic cleaning at a frequency of 40kHz is used for 15 minutes. The synergistic effect of ultrasonic and chemical cleaning helps to concentrate the action on the waste catalyst, improving cleaning efficiency, preventing dirt deposition, and extending the service life of the cleaning agents.

[0048] Preferably, the chemical cleaning uses 5% nitric acid. Low-concentration nitric acid only dissolves a portion of the binder (such as Al2O3), retaining the active ingredients and avoiding excessive dissolution that could damage the catalyst structure. Compared to strong acids such as concentrated hydrochloric acid, nitric acid is less corrosive to equipment and has lower wastewater treatment costs.

[0049] The air preheater online heating and co-processing unit is arranged in conjunction with the outlet of the preliminary cleaning device 7. The air preheater online heating and co-processing unit includes a waste catalyst spraying device 12, a hot air introduction device 11, and an air preheater body 8. The outlet of the air preheater body 8 is connected to the SCR system. The outlet of the air preheater body 8 and the outlet of the preliminary cleaning device 7 are both connected to the recycling unit.

[0050] Specifically, the waste catalyst spraying device 12 includes a waste catalyst spray head 121 and a pressure pump. The waste catalyst spray head 121 sprays pretreated waste catalyst with suitable active particle size and activity into the air preheater body 8; the pressure pump can increase the spray pressure of the spray head.

[0051] Specifically, hot air introduction devices 11 are installed at the air inlet and air outlet of the air preheater body 8, respectively. A feed valve is installed at the air inlet end of the hot air introduction device 11 to introduce auxiliary fuel. Hot air is generated by burning the auxiliary fuel, achieving online heating of the air preheater. A waste catalyst spraying device 12 is installed in a specific area inside the air preheater body 8. This device is connected to the outlet of the highly active waste catalyst in the pretreatment unit. During the air preheater heating process, the pretreated waste catalyst is evenly sprayed onto the heat exchange surface of the air preheater body 8. Under the heating environment, on the one hand, some active sites on the surface of the waste catalyst are activated, which has a certain catalytic decomposition effect on the ash and some harmful substances in the air preheater, helping to prevent air preheater blockage; on the other hand, the waste catalyst is further cleaned and activated during the interaction with the airflow and heat exchange surface in the air preheater, and its activity is improved. The treated waste catalyst can be collected, with some returned to the SCR system for continued use and some entering the recycling unit.

[0052] The air preheater online heating and coordinated processing unit also includes a temperature sensor 9, a pressure sensor 10, a temperature control box 95, and a PLC; the temperature sensor 9 and the pressure sensor 10 are respectively installed at the flue gas inlet section and the hot air outlet section inside the air preheater. Specifically, as shown... Figure 4 As shown, the air preheater body 8 is a cylindrical sealed cavity. The air preheater body 8 is equipped with an inlet temperature sensor 91, a heat exchange surface temperature sensor 92, and an outlet temperature sensor 93. All three temperature sensors 93 are high-temperature resistant armored thermocouple sensors, and the collected temperature data is transmitted to a temperature control box 95 located next to the air preheater body 8. The temperature control box 95 is connected to a PLC.

[0053] Specifically, the pressure sensor 10 is a differential pressure sensor, which includes an anti-clogging diaphragm with a Teflon coating on its surface. Differential pressure sensors are installed at the inlet pressure measuring point 101 in the flue gas inlet section and the outlet pressure measuring point 102 in the hot air outlet section of the air preheater body 8. The pressure data from both are transmitted to the PLC via the differential pressure calculation module 103. The differential pressure sensor features an anti-clogging diaphragm design (Teflon coating on the surface) to prevent dust adhesion from affecting measurement accuracy. During operation, when the air preheater pressure difference exceeds a set threshold, the control system activates the hot air introduction device 11 to begin heating at a set rate. Simultaneously, the waste catalyst spraying device 12 evenly sprays pretreated, highly active waste catalyst into the air preheater. During the heating process, the ash accumulation in the air preheater significantly decreases, and the pressure difference gradually decreases. After a period of operation, the treated waste catalyst in the air preheater is collected. Waste catalyst with improved activity can be returned to the SCR system for continued use, while the remainder enters the recycling unit.

[0054] The waste catalyst collection port 1 is connected to the collection chamber 2; the collection chamber 2 includes a vibration device 3. The collection chamber 2 is equipped with the vibration device 3 to prevent the waste catalyst from accumulating and clogging. A screw conveyor 4 is connected to the bottom of the collection chamber 2 to quantitatively transport the collected waste catalyst to the pretreatment unit.

[0055] The recovery unit includes a metal extraction device 13 and a catalyst regeneration device 14. For spent catalysts with low activity collected from the pretreatment unit and the air preheater online heating and co-processing unit, heavy metals such as vanadium, tungsten, and molybdenum are first extracted using the metal extraction device 13 via chemical leaching. The remaining catalyst support after metal extraction enters the catalyst regeneration device 14, where a series of processes, including acid-base treatment, are used to restore some of the catalyst's activity. The regenerated catalyst can be used as a raw material to prepare new catalysts or returned to the SCR system for reuse.

[0056] Preferably, the metal extraction device 13 contains a 10% sulfuric acid solution; the catalyst regeneration device 14 includes a combustion furnace and a reactor, the reactor being provided with a sodium hydroxide solution.

[0057] Preferably, the spent catalyst entering the recycling unit is first leached in the metal extraction device 13 using a 10% sulfuric acid solution for 2 hours to extract heavy metals such as vanadium, tungsten, and molybdenum. The catalyst support after metal extraction enters the combustion furnace of the catalyst regeneration device 14 and is calcined at 800°C for 2 hours. Then, it is treated in a reactor with a 5% sodium hydroxide solution. The regenerated catalyst has its activity partially restored and can be used as a raw material to prepare new catalysts.

[0058] The workflow of the above-mentioned SCR system waste catalyst treatment and recycling system is summarized as follows:

[0059] 1. Collection and transportation of spent catalyst: The spent catalyst from the SCR system outlet enters the collection bin 2 through the collection port, and after being prevented from accumulating by the vibration device 3, it is transported to the pretreatment unit by the screw conveyor 4.

[0060] 2. Pretreatment: The spent catalyst is successively crushed, screened, and washed, and is divided into different parts according to its activity and particle characteristics. These parts then enter the air preheater online heating and co-processing unit and the recovery unit, respectively.

[0061] 3. Online heating and co-processing of air preheater: The air preheater is heated by the hot air introduction device 11. At the same time, the pre-treated high-activity waste catalyst is sprayed into the air preheater, which synergistically plays the role of preventing blockage and further activating the waste catalyst. Part of the treated waste catalyst is put into the waste catalyst collection port for reuse, and part enters the recycling unit.

[0062] 4. Recycling: Low-activity spent catalysts undergo metal extraction and catalyst regeneration in the recycling unit to achieve resource recycling.

[0063] In addition, the control system based on the above-mentioned SCR system waste catalyst treatment and application recycling system includes a main control module, an auxiliary control module and a safety monitoring module;

[0064] The main control module includes a control unit; the control unit is electrically connected to the weighing device, activity detection device, pressure sensor 10, temperature sensor 9 and hot air introduction device 11 of the collection bin 2.

[0065] The auxiliary control module includes a high-pressure flushing water submodule and a sealing control submodule;

[0066] The safety monitoring module includes an air preheater surface temperature detection submodule and an air preheater inlet and outlet CO concentration detection submodule.

[0067] Specifically, the control unit can be a PLC or a DCS. This control system can use a PLC or DCS to process the temperatures of the air preheater's inlet and outlet, the heat exchange surface temperature, and the pressure difference between the inlet and outlet measured by sensors, and control the fuel supply and combustion time of the hot air introduction device 11 to control the activity level of the reaction inside the air preheater, optimize combustion, and improve thermal efficiency. By automatically controlling the timing and amount of waste catalyst spraying in the air preheater based on the conveying speed of the waste catalyst collection and conveying unit and the operating parameters of each device in the pretreatment unit, the spraying rate into the air preheater can be adjusted in real time according to the supply of waste catalyst and the pretreatment speed.

[0068] Specifically, this control system can control the valve opening of the chemical spray head 73 for chemical cleaning through the high-pressure flushing water submodule, and dynamically compensate for the thermal expansion and deformation of the air preheater through the sealing control submodule to reduce air leakage losses.

[0069] Specifically, the air preheater surface temperature detection submodule can detect the surface temperature of the heat exchange surface, issue an alarm when the temperature exceeds the limit, and reduce the spraying of waste catalyst; the air preheater inlet and outlet CO concentration detection submodule can use CO concentration detection or infrared detection to issue early warnings for suspicious gases or suspicious infrared imaging points.

[0070] This control system adjusts the operating parameters of each unit device in real time based on sensor data to ensure stable system operation. Through the automated control of the system, the system parameters can be adjusted in real time according to the actual operating conditions of the power plant, ensuring efficient and stable operation of the system and improving the overall economic and environmental performance of the power plant.

[0071] Example 2

[0072] The main difference between this embodiment and Embodiment 1 is:

[0073] 1) Temperature sensor 9 has a built-in signal amplification module;

[0074] 2) The temperature sensor 9 and the pressure sensor 10 are both directly electrically connected to the PLC.

[0075] 3) The temperature sensor 9 is externally wrapped with a protective sleeve 94;

[0076] The temperature sensor 9 has a built-in signal amplification module that converts the temperature signal into a 4-20mA standard current signal, which is then transmitted to the control system in real time. The temperature sensor 9 is encased in a stainless steel protective sleeve 94 to prevent corrosion from high-temperature flue gas.

[0077] In addition, a control method for the treatment and recycling of spent catalysts in an SCR system includes the following steps:

[0078] When the amount of waste catalyst accumulated in collection chamber 2 reaches 80%, increase the conveying speed of the conveying device;

[0079] The waste catalyst conveyed to the crushing device 5 is sent to the screening device 6 for particles smaller than 10 mm, and to the recycling unit for particles larger than 10 mm.

[0080] The waste catalyst conveyed to the screening device 6 is sent to the preliminary cleaning device 7 for particles smaller than 5 mm, and to the recycling unit for particles larger than 5 mm.

[0081] The spent catalyst at the outlet of the preliminary cleaning unit 7, wherein the portion with an activity exceeding 30% is sent to the air preheater; and the portion with an activity below 30% is sent to the recovery unit.

[0082] When the pressure difference between the pressure sensors 10 exceeds the set threshold, the control system activates the hot air introduction device 11.

[0083] When the maximum value obtained by the temperature sensor 9 of the air preheater exceeds the set upper limit, the fuel supply of the hot air introduction device 11 is reduced.

[0084] The above control method achieves intelligent regulation of the entire process through particle size classification, activity screening (>30%), and pressure / temperature threshold control, reducing manual intervention; when the air preheater temperature exceeds the standard, the fuel supply is automatically reduced to avoid energy waste.

[0085] The above embodiments are merely one of the implementation methods for achieving the technical solution of the present invention. The scope of protection claimed by the present invention is not limited to this embodiment, but also includes any variations, substitutions and other implementation methods that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention.

Claims

1. A system for treating and recycling spent catalysts from an SCR system, characterized in that, The system includes a waste catalyst collection and conveying unit, a pretreatment unit, an air preheater online heating and co-processing unit, and a recovery unit. The waste catalyst collection and conveying unit sequentially includes a waste catalyst collection port, a collection bin, and a conveying device, with the collection port located at the outlet of the SCR system. The pretreatment unit is arranged in conjunction with the outlet of the conveying device and sequentially includes a crushing device, a screening device, and a preliminary cleaning device. The air preheater online heating and co-processing unit is arranged in conjunction with the outlet of the preliminary cleaning device and includes a waste catalyst spraying device, a hot air introduction device, and the air preheater body. The outlet of the air preheater body is connected to the SCR system. Both the outlet of the air preheater body and the outlet of the preliminary cleaning device are connected to the recovery unit. Hot air introduction devices are installed at the air inlet and outlet of the air preheater body. A waste catalyst spraying device is installed in a specific area inside the air preheater body, and during the air preheater heating process, the pretreated waste catalyst is evenly sprayed onto the heat exchange surface of the air preheater body. The air preheater online heating and collaborative processing unit also includes a temperature sensor, a pressure sensor, and a PLC; the temperature sensor and the pressure sensor are respectively installed at the flue gas inlet section and the hot air outlet section inside the air preheater; the temperature sensor and the pressure sensor are respectively electrically connected to the PLC. The pretreatment unit also includes an activity detection device; the activity detection device is connected to the outlet of the preliminary cleaning device. The recovery unit includes a metal extraction device and a catalyst regeneration device; the metal extraction device is filled with a 10% sulfuric acid solution; the catalyst regeneration device includes a combustion furnace and a reactor, the reactor being equipped with a sodium hydroxide solution. The control method for the treatment and recycling of spent catalysts in an SCR system includes the following steps: When the amount of waste catalyst accumulated in the collection chamber reaches 80%, increase the conveying speed of the conveying device; The spent catalyst, after being conveyed to the crushing unit, is divided into two parts: the portion with a particle size of less than 10 mm is conveyed to the screening unit; the portion with a particle size of more than 10 mm is conveyed to the recycling unit. The spent catalyst, after being conveyed to the screening device, is sent to the preliminary cleaning device for particles smaller than 5 mm, and to the recycling unit for particles larger than 5 mm. The spent catalyst at the outlet of the preliminary cleaning unit, with the portion having an activity exceeding 30%, is sent to the air preheater; the portion with an activity below 30% is sent to the recovery unit. When the pressure difference between the pressure sensors exceeds the set threshold, the control system activates the hot air introduction device. When the maximum value obtained by the temperature sensor of the air preheater exceeds the set upper limit, the fuel supply of the hot air introduction device is reduced.

2. The SCR system waste catalyst treatment and recycling system according to claim 1, characterized in that, The temperature sensor is encased in a protective sleeve; the pressure sensor is a differential pressure sensor, which includes an anti-clogging diaphragm with a Teflon coating on its surface.

3. The SCR system waste catalyst treatment and recycling system according to claim 1, characterized in that, The pretreatment unit consists of a crushing device, a screening device, and a preliminary cleaning device arranged vertically in sequence; the preliminary cleaning device employs ultrasonic cleaning and chemical cleaning.

4. The SCR system waste catalyst treatment and recycling system according to claim 3, characterized in that, The chemical cleaning process uses 5% nitric acid.

5. The SCR system waste catalyst treatment and recycling system according to claim 1, characterized in that, The waste catalyst collection port is connected to the collection chamber; the collection chamber includes a vibration device.

6. The control system for the SCR system waste catalyst treatment and application recovery system as described in any one of claims 1-5, characterized in that, It includes a main control module, an auxiliary control module, and a security monitoring module; The main control module includes a control unit; the control unit is electrically connected to the weighing device, activity detection device, pressure sensor, temperature sensor and hot air introduction device of the collection bin; The auxiliary control module includes a high-pressure flushing water submodule and a sealing control submodule; The safety monitoring module includes an air preheater surface temperature detection submodule and an air preheater inlet and outlet CO concentration detection submodule.

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