An in-situ regeneration system and method for an scr catalyst

Abstract

This invention discloses an in-situ regeneration system and method for SCR catalysts, relating to the field of flue gas purification technology. The invention modifies an existing denitrification tower by incorporating a back-blowing system, a cleaning system, a flue gas heating system, and a cleaning fluid recovery system. The back-blowing system removes accumulated ash from the catalyst module surface and pores using high-pressure purging. The regeneration fluid cleaning system cleans the catalyst of contaminants using different cleaning fluids. The flue gas heating system promotes the evaporation of moisture from the cleaned catalyst and the decomposition of precursors of active components on the catalyst surface, thus achieving catalyst regeneration. This invention is time-efficient and cost-effective, allowing catalyst regeneration to be completed during routine system maintenance. It provides excellent regeneration results, thoroughly removing fly ash, alkali metals, alkaline earth metals, and heavy metals from the catalyst, thus solving the catalyst poisoning problem.

Description

Technical Field

[0001] This invention relates to the field of flue gas purification technology, and in particular to an in-situ regeneration system and method for SCR catalysts. Background Technology

[0002] Selective catalytic reduction (SCR) denitrification technology boasts advantages such as high denitrification efficiency, mature technology, and reliable performance, making it the mainstream technology for NOx removal from industrial flue gas. Currently, catalyst deactivation is the main problem in the operation of SCR denitrification technology. Catalyst costs typically account for about 50% of the total project cost, and the theoretical service life of commonly used vanadium-titanium catalysts is generally less than 3 years. Therefore, tens of thousands of tons of waste denitrification catalysts are generated annually nationwide.

[0003] Therefore, regenerating and recycling deactivated denitration catalysts is the primary solution. The main causes of catalyst deactivation include: blockage deactivation, high-temperature sintering deactivation, poisoning deactivation, and loss of active components. Commonly used catalyst regeneration methods include negative pressure dust removal, compressed air purging, high-pressure water washing, ultrasonic cleaning, chemical cleaning, and active component impregnation. Regeneration processes are divided into in-situ regeneration and ex-situ regeneration. Ex-situ regeneration requires removing the deactivated catalyst from the system and sending it to a professional regeneration company for processing; this method is time-consuming, costly, and disrupts the continuous operation of the SCR system. In-situ regeneration technology effectively avoids these drawbacks and represents the development direction of SCR catalyst regeneration technology.

[0004] Several in-situ regeneration technologies have been published, such as patent (CN112169581A) on an online SCR catalyst flue gas treatment method and system, which enables simultaneous thermal regeneration and denitrification of the SCR catalyst, and the system can operate normally without shutdown. Patent (CN216630873U) on an online regeneration device for SCR catalysts in coal-fired power plants includes an SCR catalyst mounting rack, a dry ice preparation system, an air injection system, a regeneration liquid injection device, a heating device, and an ultrasonic device, which can achieve online catalyst regeneration with only on-site flue gas duct modifications.

[0005] The aforementioned existing technologies either employ thermal regeneration or involve retrofitting existing SCR flues, both of which suffer from poor regeneration performance and affect the continuous operation of the SCR system. Summary of the Invention

[0006] This application provides an in-situ regeneration system and method for SCR catalysts to solve the technical problem that the existing in-situ regeneration of SCR catalysts has poor effect and affects the continuous operation of SCR systems.

[0007] In a first aspect, this application provides an in-situ regeneration system for SCR catalysts, disposed between the inlet and outlet of a denitrification tower. The system includes a backflushing system, a cleaning system, a flue gas heating system, and a cleaning liquid recycling system. The backflushing system is used to remove accumulated ash from the surface and interior of the catalyst. The cleaning system is used to clean the catalyst. The flue gas heating system promotes the evaporation of moisture from the cleaned catalyst and the decomposition of precursors of active components on the catalyst surface, thereby achieving catalyst regeneration. The cleaning liquid recycling system is connected to the cleaning system and is used to recover the cleaning liquid.

[0008] Optionally, the flue gas heating system includes a heater disposed at the end of the catalyst.

[0009] Optionally, the catalyst includes n denitrification units, and the backflush system includes a high-pressure blower and n backflush nozzles connected to the high-pressure blower, with the backflush nozzles facing the denitrification units;

[0010] The cleaning system includes multiple parallel cleaning units, as well as a regeneration pump and a cleaning nozzle. The cleaning units, the regeneration pump, and the cleaning nozzle are all connected by cleaning pipes, and the cleaning nozzle is directly facing the catalyst.

[0011] Optionally, the back-blowing nozzle is 10cm to 20cm away from the catalyst; the cleaning nozzle is 5cm to 15cm away from the catalyst.

[0012] Optionally, the plurality of parallel cleaning units include a water washing unit, an acid washing unit, an alkaline washing unit, and an activity restoration unit connected in parallel. The water washing unit is used to remove ash and water-soluble contaminants from the catalyst. The acid washing unit and the alkaline washing unit are used to remove water-insoluble dirt from the catalyst, including but not limited to alkali metals, sulfates, and silica. The activity restoration unit is used to restore the content of active components in the catalyst.

[0013] Optionally, the water washing unit includes a water washing tank containing deionized water and a surfactant; the acid washing unit includes an acid washing tank containing a sulfuric acid solution; the alkaline washing unit includes an alkaline washing tank containing an ammonia solution and solid ammonium carbonate; and the active repair unit includes a repair tank containing ammonium metavanadate and ammonium paratungstate.

[0014] Optionally, the surfactant concentration in the water washing tank is 1% to 3%; the sulfuric acid solution concentration in the acid washing tank is 0.2% to 0.5%; the ammonia solution concentration in the alkaline washing tank is 20%, and the liquid-solid ratio of the ammonia solution to the ammonium carbonate solid is 6:1; the active repair tank includes an ammonium metavanadate solution with a mass concentration of 0.8 wt% and an ammonium paratungstate solution with a mass concentration of 6 wt%.

[0015] Optionally, the recycling system includes an inclined plate and a discharge port. The discharge port is located at the bottom of the denitrification tower. One end of the inclined plate is located at the bottom of the catalyst, and the other end is close to the discharge port and located 1cm to 3cm below the discharge port.

[0016] Optionally, the water washing tank, the acid washing tank, the alkaline washing tank, and the repair tank are each equipped with an inlet valve and an outlet valve. The inlet valve is connected to the outlet of the cleaning fluid circulation and recovery system through a pipeline, and the outlet valve is connected to the regeneration pump.

[0017] Optionally, the cleaning nozzle is an atomizing nozzle.

[0018] Optionally, the regeneration system further includes an ultrasonic generator disposed at the end of the catalyst.

[0019] Secondly, the present invention also provides an in-situ regeneration method for SCR catalysts, implemented using the in-situ SCR catalyst regeneration system described in the first aspect, comprising the following steps:

[0020] Close the inlet and outlet dampers of the denitrification tower and use a back-blowing system to purge the catalyst;

[0021] The catalyst is cleaned using a cleaning system, and the cleaning fluid is recovered using a cleaning fluid recycling system.

[0022] Turn on the flue gas heating system, dry the catalyst, and activate the catalyst.

[0023] To complete the in-situ regeneration process of the SCR catalyst, open the inlet and outlet dampers of the denitrification tower.

[0024] Optionally, a back-blowing system can be used to purge the catalyst, specifically including: turning on the back-blowing high-pressure blower, adjusting the blowing pressure, using the back-blowing nozzle to purge the catalyst for a preset time, and then turning off the back-blowing blower;

[0025] The process of using a cleaning system to clean the catalyst and using a cleaning solution recycling system to recover the cleaning solution specifically includes: opening the inclined plate and the outlet, and sequentially using a water washing unit, an acid washing unit, an alkaline washing unit, and an activity repair unit to clean and repair the catalyst.

[0026] The process of opening the flue gas heating system, drying the catalyst, and activating the catalyst specifically includes: turning on the heater, first controlling the temperature to the drying temperature to dry the moisture in the catalyst, and then controlling the temperature to the activation temperature to activate the catalyst.

[0027] Optionally, the high-pressure blower can be used to purge the catalyst at a pressure of 0.8 MPa, and a reverse-blowing nozzle can be used to purge the catalyst for 30 minutes.

[0028] Optionally, the catalyst is cleaned and repaired by sequentially using a water washing unit, an acid washing unit, an alkaline washing unit, and an activity repair unit. Specifically, during water washing, the regeneration pump, the inlet valve and the outlet valve of the water washing tank are turned on. The cleaning liquid is transmitted to the cleaning nozzle through the outlet valve and the regeneration pump. The cleaning nozzle sprays the cleaning liquid to clean the catalyst. The cleaned liquid enters the inlet valve through the inclined plate and the outlet, and finally returns to the water washing tank for precipitation and recovery.

[0029] After the water washing process is completed for 30 to 60 minutes, the valve of the water washing tank is closed, and the inlet and outlet valves of the acid washing tank are opened. The 0.2 to 0.5 mol / L sulfuric acid solution in the acid washing tank is transferred to the cleaning nozzle through the outlet valve and the regeneration pump. The cleaning nozzle sprays sulfuric acid solution to clean the alkali metal in the catalyst. The cleaned liquid enters the inlet valve through the inclined plate and the outlet, and finally returns to the acid washing tank for precipitation and recovery.

[0030] After pickling for 30 to 60 minutes, close the valve of the pickling tank and open the inlet and outlet valves of the alkaline washing tank. The 20% ammonia water with a liquid-to-solid ratio of 6:1 and the ammonium carbonate solid in the alkaline washing tank are transferred to the cleaning nozzle through the outlet valve and the regeneration pump. The cleaning nozzle sprays out the ammonia water solution to clean the heavy metals in the catalyst. The cleaned liquid enters the inlet valve through the inclined plate and the outlet, and finally returns to the alkaline washing tank for precipitation and recovery.

[0031] After 1-2 hours of alkaline washing, the valve of the alkaline washing tank is closed, and the inlet and outlet valves of the active remediation tank are opened. The ammonium metavanadate solution with a mass concentration of 0.8 wt% and the ammonium paratungstate solution with a mass concentration of 6 wt% in the active remediation tank are transferred to the cleaning nozzle through the outlet valve and the regeneration pump. The cleaning nozzle sprays out the ammonium metavanadate solution and the ammonium paratungstate solution to activate the catalyst. The excess ammonium metavanadate solution and ammonium paratungstate solution enter the inlet valve through the inclined plate and the outlet, and finally return to the active remediation tank for precipitation and recovery.

[0032] Optionally, the drying temperature of the heater is set to 100℃~105℃, and the activation temperature is set to 450℃~550℃.

[0033] Optionally, before cleaning and repairing the catalyst using the water washing unit, acid washing unit, alkali washing unit, and active repair unit in sequence, the ultrasonic generator is turned on. The ultrasonic generator uses sound energy to convert into mechanical vibration, generating shock waves to enhance the cleaning effect.

[0034] The technical solution provided by this invention has the following advantages compared with the prior art:

[0035] This invention provides an in-situ regeneration system and method for SCR catalysts. The system incorporates a back-blowing system, a cleaning system, a flue gas heating system, and a cleaning solution circulation and recovery system within the existing denitrification tower. The back-blowing system removes accumulated ash from the surface and pores of the catalyst module through high-pressure purging. The cleaning system uses different cleaning solutions to remove dirt from the catalyst. The flue gas heating system promotes the evaporation of moisture from the cleaned catalyst and the decomposition of precursors of active components on the catalyst surface, thus achieving catalyst regeneration. This invention is time-efficient and low-cost, allowing catalyst regeneration to be completed during routine system maintenance. It provides excellent regeneration results, thoroughly removing fly ash, alkali metals, alkaline earth metals, and heavy metals from the catalyst, thus solving the catalyst poisoning problem caused by these substances. Attached Figure Description

[0036] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0037] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 A schematic diagram of an in-situ SCR catalyst regeneration system provided in this application embodiment;

[0039] 1-Inlet damper; 2-Catalyst; 3-Heating device; 4-Atomizing nozzle; 5-Backflush nozzle; 6-High-pressure blower; 7-Regeneration pump; 8-Water washing tank; a1-Water washing tank inlet valve; a2-Water washing tank outlet valve; 9-Acid washing tank; b1-Acid washing tank inlet valve; b2-Acid washing tank outlet valve; 10-Alkali washing tank; c1-Alkali washing tank inlet valve; c2-Alkali washing tank outlet valve; 11-Activated repair tank; d1-Repair tank inlet valve; d2-Repair tank outlet valve; 12-Ultrasonic generator; 13-Inclined plate; 14-Exhaust port; 15-Outlet damper.

[0040] Figure 2 This is a flowchart of an in-situ regeneration method for an SCR catalyst provided in Example 1 of this application. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0042] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0043] In this application, unless otherwise stated, directional terms such as "upper" and "lower" specifically refer to the drawing directions in the accompanying drawings. Furthermore, in the description of this application, terms such as "comprising" and "including" mean "including but not limited to." In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this document, "and / or" describes the relationship between related objects, indicating that three relationships can exist; for example, A and / or B can represent: A alone, A and B simultaneously, or B alone. A and B can be singular or plural. In this document, "at least one" means one or more, and "more than one" means two or more. "At least one," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c" or "at least one of a, b, and c" can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be a single or multiple.

[0044] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0045] In a first aspect, this application provides an in-situ regeneration system for SCR catalysts, disposed between the inlet and outlet of a denitrification tower. The system includes a backflushing system, a cleaning system, a flue gas heating system, and a cleaning liquid recycling system. The backflushing system is used to remove accumulated ash from the surface and interior of the catalyst. The cleaning system is used to clean the catalyst. The flue gas heating system promotes the evaporation of moisture from the cleaned catalyst and the decomposition of precursors of active components on the catalyst surface, thereby achieving catalyst regeneration. The cleaning liquid recycling system is connected to the cleaning system and is used to recover the cleaning liquid.

[0046] In the above embodiments, the regeneration system is modified on the original denitrification tower. The modification cost is low, no additional catalyst replacement is required, and the time consumption is short. The catalyst regeneration can be completed during the routine maintenance of the system.

[0047] In an optional embodiment, the catalyst includes n denitrification units, and the backflush system includes a high-pressure blower and n backflush nozzles connected to the high-pressure blower, the backflush nozzles being directly facing the denitrification units; here n is an integer greater than or equal to 1, such as 1, 2, 3, ...

[0048] The cleaning system includes multiple parallel cleaning units, as well as a regeneration pump and a cleaning nozzle. The cleaning units, the regeneration pump, and the cleaning nozzle are all connected by cleaning pipes, and the cleaning nozzle is directly facing the catalyst.

[0049] In an optional embodiment, the flue gas heating system includes a heater disposed at an end of the catalyst.

[0050] In an optional embodiment, the number of heaters is the same as the number of denitrification units, and they are disposed at the end of each denitrification unit.

[0051] In an optional embodiment, the back-blowing nozzle is 10cm to 20cm away from the catalyst, for example, it can be set to 10cm, 12cm, 14cm, 16cm, 18cm, or 20cm; the cleaning nozzle is 5cm to 15cm away from the catalyst, for example, it can be set to 5cm, 8cm, 10cm, 12cm, or 15cm.

[0052] In an optional embodiment, the plurality of parallel cleaning units include a water washing unit, an acid washing unit, an alkaline washing unit, and an activity restoration unit connected in parallel. The water washing unit is used to remove ash and water-soluble contaminants from the catalyst. The acid washing unit and the alkaline washing unit are used to remove water-insoluble dirt from the catalyst, including but not limited to alkali metals, sulfates, and silica. The activity restoration unit is used to restore the content of active components in the catalyst.

[0053] In the above embodiments, multiple parallel cleaning units are used, allowing for individual cleaning by a specific unit without mutual contamination or interference. After water washing, acid washing, and alkali washing, fly ash, alkali metals, alkaline earth metals, and heavy metals on the catalyst can be thoroughly removed. An active remediation unit sprays active remediation substances into the catalyst, accelerating the in-situ regeneration process.

[0054] In an optional embodiment, the water washing unit includes a water washing tank containing deionized water and a surfactant; the acid washing unit includes an acid washing tank containing a sulfuric acid solution; the alkaline washing unit includes an alkaline washing tank containing an ammonia solution and solid ammonium carbonate; and the active repair unit includes an active repair tank containing an ammonium metavanadate solution and an ammonium paratungstate solution.

[0055] In an optional embodiment, the surfactant concentration in the water washing tank is 1% to 3%, and the surfactant concentration can be selected as 1%, 2%, or 3%; the sulfuric acid solution concentration in the acid washing tank is 0.2% to 0.5%, and the concentration can be selected as 0.2%, 0.3%, 0.4%, or 0.5%; the ammonia solution concentration in the alkaline washing tank is 20%, and the liquid-solid ratio of the ammonia solution to the ammonium carbonate solid is 6:1; the active repair tank includes an ammonium metavanadate solution with a mass concentration of 0.8 wt% and an ammonium paratungstate solution with a mass concentration of 6 wt%.

[0056] In the above embodiments, specific cleaning agents are selected to better remove fly ash, alkali metals, alkaline earth metals, and heavy metals from the catalyst.

[0057] In an optional embodiment, the recycling system includes an inclined plate and a discharge port. The discharge port is located at the bottom of the denitrification tower. One end of the inclined plate is located at the bottom of the catalyst, and the other end is close to the discharge port and located 1cm to 3cm below the discharge port.

[0058] In an optional embodiment, the water washing tank, the acid washing tank, the alkali washing tank, and the repair tank are all equipped with inlet valves and outlet valves before and after them. The inlet valves are connected to the outlet of the circulation and recycling system through pipelines, and the outlet valves are connected to the regeneration pump.

[0059] In an optional embodiment, the cleaning nozzle is an atomizing nozzle.

[0060] In the above embodiments, the atomizing nozzle can spray a finer mist of liquid, thereby achieving better cleaning results with less cleaning fluid, generating less wastewater, and reducing pollution.

[0061] In an optional embodiment, the regeneration system further includes an ultrasonic generator disposed at the end of the catalyst.

[0062] In the above embodiments, an ultrasonic generator is used to convert sound energy into mechanical vibration, generating shock waves to enhance the cleaning effect.

[0063] Secondly, based on the same inventive concept, the present invention also provides an in-situ regeneration method for SCR catalysts, implemented using the in-situ SCR catalyst regeneration system described in the first aspect, comprising the following steps:

[0064] Close the inlet and outlet dampers of the denitrification tower and use a back-blowing system to purge the catalyst;

[0065] The catalyst is cleaned using a cleaning system, and the cleaning solution is recovered using a cleaning solution recycling system.

[0066] Turn on the flue gas heating system, dry the catalyst, and activate the catalyst.

[0067] To complete the in-situ regeneration of the SCR catalyst, open the inlet and outlet dampers of the denitrification tower and restart the denitrification process.

[0068] In an optional implementation, a back-blowing system is used to purge the catalyst, specifically including: turning on the back-blowing high-pressure blower, adjusting the blowing pressure, using the back-blowing nozzle to purge the catalyst for a preset time, and then turning off the back-blowing blower.

[0069] The process of using a cleaning system to clean the catalyst and using a cleaning solution recycling system to recover the cleaning solution specifically includes: opening the inclined plate and the outlet, and sequentially using a water washing unit, an acid washing unit, an alkaline washing unit, and an activity repair unit to clean and repair the catalyst.

[0070] The process of opening the flue gas heating system, drying the catalyst, and activating the catalyst specifically includes: turning on the heater, first controlling the temperature to the drying temperature to dry the moisture in the catalyst, and then controlling the temperature to the activation temperature to activate the catalyst.

[0071] In an optional embodiment, the blowing pressure of the high-pressure blower is 0.8 MPa to 1 MPa, and the catalyst is purged with a reverse blowing nozzle for 20 min to 40 min.

[0072] In the above embodiments, a certain pressure and time are used to ensure that the dust on the catalyst surface can be blown off.

[0073] In an optional implementation, the catalyst is cleaned and repaired sequentially using a water washing unit, an acid washing unit, an alkaline washing unit, and an activity repair unit. Specifically, during water washing, the regeneration pump, the inlet valve and the outlet valve of the water washing tank are turned on. The cleaning liquid is transmitted to the cleaning nozzle through the outlet valve and the regeneration pump. The cleaning nozzle sprays the cleaning liquid to clean the catalyst. The cleaned liquid enters the inlet valve through the inclined plate and the outlet, and finally returns to the water washing tank for precipitation and recovery.

[0074] After the water washing process is completed for 30 to 60 minutes, the valve of the water washing tank is closed, and the inlet and outlet valves of the acid washing tank are opened. The 0.2 to 0.5 mol / L sulfuric acid solution in the acid washing tank is transferred to the cleaning nozzle through the outlet valve and the regeneration pump. The cleaning nozzle sprays sulfuric acid solution to clean the alkali metal in the catalyst. The cleaned liquid enters the inlet valve through the inclined plate and the outlet, and finally returns to the acid washing tank for precipitation and recovery.

[0075] After pickling for 30 to 60 minutes, close the inlet valve of the pickling tank and open the inlet and outlet valves of the alkaline washing tank. The 20% ammonia water with a liquid-to-solid ratio of 6:1 and the ammonium carbonate solid in the alkaline washing tank are transferred to the cleaning nozzle through the outlet valve and the regeneration pump. The cleaning nozzle sprays out the ammonia water solution to clean the heavy metals in the catalyst. The cleaned liquid enters the inlet valve through the inclined plate and the outlet, and finally returns to the alkaline washing tank for precipitation and recovery.

[0076] After 1-2 hours of alkaline washing, the valve of the alkaline washing tank is closed, and the inlet and outlet valves of the active remediation tank are opened. The ammonium metavanadate solution with a mass concentration of 0.8 wt% and the ammonium paratungstate solution with a mass concentration of 6 wt% in the remediation tank are transferred to the cleaning nozzle through the outlet valve and the regeneration pump. The cleaning nozzle sprays out ammonium metavanadate and ammonium paratungstate to activate the catalyst. The excess ammonium metavanadate and ammonium paratungstate enter the inlet valve through the inclined plate and the outlet, and finally return to the remediation tank for precipitation and recovery.

[0077] In an optional embodiment, the drying temperature of the heater is set to 100℃~105℃, for example, 100℃, 101℃, 102℃, 103℃, 104℃, 105℃; and the activation temperature is set to 450℃~550℃, for example, 450℃, 470℃, 500℃, 520℃, 540℃, 550℃.

[0078] In the above embodiments, the drying temperature is used to dry the moisture on the catalyst surface more quickly; the activation temperature is used to decompose the active component precursor on the catalyst surface to form a substance with denitrification activity.

[0079] In an optional implementation, before cleaning and repairing the catalyst using the water washing unit, acid washing unit, alkali washing unit, and active repair unit in sequence, the ultrasonic generator is turned on. The ultrasonic generator uses sound energy to convert into mechanical vibration, generating shock waves to enhance the cleaning effect.

[0080] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national standards. If there is no corresponding national standard, then general international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0081] The SRC catalyst in-situ regeneration system provided by this invention was used to regenerate the degraded catalyst in-situ. The degraded catalyst had been used for 24,000 hours. Analysis showed that the catalyst blockage rate was 20%, K2O content was 0.22%, Na2O content was 0.13%, CaO content was 3.2%, V2O5 content was 1.24%, WO3 content was 4.59%, and the denitrification efficiency had decreased to 82%.

[0082] In Examples 1-3, the backflush nozzle in the SRC catalyst in-situ regeneration system was 10 cm from the catalyst surface, the cleaning liquid atomizing nozzle was 5 cm from the catalyst surface, and the outlet was 1 cm above the inclined plate. The specific experimental process is as follows:

[0083] Example 1:

[0084] Close the inlet damper 1 and outlet damper 15 of the denitrification tower, and open the inclined plate 13 and the outlet 14. Turn on the back-blowing high-pressure blower 6, adjust the blowing pressure to 0.8 MPa, and blow with the back-blowing nozzle 5 for 30 minutes, then turn off the back-blowing blower 6; turn on the regeneration pump 7, ultrasonic generator 12, water washing tank 8 outlet valve a2, and inlet valve a1, and use the atomizing nozzle 4 to spray atomized cleaning liquid to clean the catalyst. The cleaning agent content is 3% surfactant, and the rest is deionized water. The cleaning time is 40 minutes, then close the outlet valve.

[0085] Open outlet valve b2 and inlet valve b1 of pickling tank 9 to clean the catalyst. The sulfuric acid concentration is 0.2 mol / L, and the cleaning time is 30 minutes. After completion, close outlet valve b2 and inlet valve b1.

[0086] Open outlet valve C2 and inlet valve C1 of alkaline washing tank 10 to clean the catalyst. The cleaning agent is 20% ammonia water in ammonium carbonate solid, with a liquid-to-solid ratio of 6:1. The alkaline washing time is 1 hour. After completion, close outlet valve C2 and inlet valve C1.

[0087] Open the outlet valve d2 and inlet valve d1 of the activation repair tank 11 to activate and repair the catalyst. The activator is a 0.8wt% ammonium metavanadate solution and a 6wt% ammonium paratungstate solution. The activation time is 20 minutes. After completion, close the outlet valve d2 and inlet valve d1, and turn off the ultrasonic generator 12.

[0088] Turn on heater 3, control the temperature at 102℃ to dry the moisture, and then control the temperature at 450℃ to activate the catalyst, thus completing the activation process.

[0089] After activation, retract the inclined plate 13, close the outlet 14, and open the outlet damper 15 and the inlet damper 1. The catalyst can then undergo normal denitrification.

[0090] Example 2:

[0091] Close the inlet damper 1 and outlet damper 15 of the denitrification tower, and open the inclined plate 13 and the outlet 14. Turn on the back-blowing high-pressure blower 6, adjust the blowing pressure to 0.9 MPa, and blow with the back-blowing nozzle 5 for 20 minutes, then turn off the back-blowing blower 6; turn on the regeneration pump 7, ultrasonic generator 12, water washing tank 8 outlet valve a2, and inlet valve a1, and use the atomizing nozzle 4 to spray atomized cleaning liquid to clean the catalyst. The cleaning agent content is 2% surfactant, and the rest is deionized water. The cleaning time is 50 minutes, then close the outlet valve.

[0092] Open outlet valve b2 and inlet valve b1 of pickling tank 9 to clean the catalyst. The sulfuric acid concentration is 0.3 mol / L, and the cleaning time is 40 minutes. After completion, close outlet valve b2 and inlet valve b1.

[0093] Open outlet valve C2 and inlet valve C1 of alkaline washing tank 10 to clean the catalyst. The cleaning agent is 20% ammonia water in ammonium carbonate solid, with a liquid-to-solid ratio of 6:1. The alkaline washing time is 1.5 hours. After completion, close outlet valve C2 and inlet valve C1.

[0094] Open the outlet valve d2 and inlet valve d1 of the activation repair tank 11 to activate and repair the catalyst. The activator is 0.8wt% ammonium metavanadate and 6wt% ammonium paratungstate. The activation time is 25min. After completion, close the outlet valve d2 and inlet valve d1, and turn off the ultrasonic generator 12.

[0095] Turn on heater 3, control the temperature at 105℃ to dry the moisture, and then control the temperature at 550℃ to activate the catalyst, thus completing the activation process.

[0096] After activation, retract the inclined plate 13, close the outlet 14, and open the outlet damper 15 and the inlet damper 1. The catalyst can then undergo normal denitrification.

[0097] Example 3:

[0098] Close the inlet damper 1 and outlet damper 15 of the denitrification tower, and open the inclined plate 13 and the outlet 14. Turn on the back-blowing high-pressure blower 6, adjust the blowing pressure to 0.9 MPa, and blow with the back-blowing nozzle 5 for 25 minutes, then turn off the back-blowing blower 6; turn on the regeneration pump 7, ultrasonic generator 12, water washing tank 8 outlet valve a2, and inlet valve a1, and use the atomizing nozzle 4 to spray atomized cleaning liquid to clean the catalyst. The cleaning agent content is 1% surfactant, and the rest is deionized water. The cleaning time is 60 minutes, and then the outlet valve is closed.

[0099] Open outlet valve b2 and inlet valve b1 of pickling tank 9 to clean the catalyst. The sulfuric acid concentration is 0.5 mol / L, and the cleaning time is 60 minutes. After completion, close outlet valve b2 and inlet valve b1.

[0100] Open outlet valve C2 and inlet valve C1 of alkaline washing tank 10 to clean the catalyst. The cleaning agent is 20% ammonia water in ammonium carbonate solid, with a liquid-to-solid ratio of 6:1. The alkaline washing time is 2 hours. After completion, close outlet valve C2 and inlet valve C1.

[0101] Open the outlet valve d2 and inlet valve d1 of the activation repair tank 11 to activate and repair the catalyst. The activator is 0.8wt% ammonium metavanadate and 6wt% ammonium paratungstate. The activation time is 30min. After completion, close the outlet valve d2 and inlet valve d1, and turn off the ultrasonic generator 12.

[0102] Turn on heater 3, control the temperature at 105℃ to dry the moisture, and then control the temperature at 550℃ to activate the catalyst, thus completing the activation process.

[0103] After activation, retract the inclined plate 13, close the outlet 14, and open the outlet damper 15 and the inlet damper 1. The catalyst can then undergo normal denitrification.

[0104] Comparative Example 1

[0105] Close the inlet damper 1 and outlet damper 15 of the denitrification tower, and open the inclined plate 13 and outlet 14. Turn on the regeneration pump 7, ultrasonic generator 12, water washing tank 8 outlet valve a2, and inlet valve a1. Use atomizing nozzle 4 to spray atomized cleaning liquid to clean the catalyst. The cleaning agent content is 3% surfactant and the rest is deionized water. The cleaning time is 40 minutes. Then close the outlet valve.

[0106] Open outlet valve b2 and inlet valve b1 of pickling tank 9 to clean the catalyst. The sulfuric acid concentration is 0.2 mol / L, and the cleaning time is 30 minutes. After completion, close outlet valve b2 and inlet valve b1.

[0107] Open outlet valve C2 and inlet valve C1 of alkaline washing tank 10 to clean the catalyst. The cleaning agent is 20% ammonia water in ammonium carbonate solid, with a liquid-to-solid ratio of 6:1. The alkaline washing time is 1 hour. After completion, close outlet valve C2 and inlet valve C1.

[0108] Open the outlet valve d2 and inlet valve d1 of the activation repair tank 11 to activate and repair the catalyst. The activator is a 0.8wt% ammonium metavanadate solution and a 6wt% ammonium paratungstate solution. The activation time is 20 minutes. After completion, close the outlet valve d2 and inlet valve d1, and turn off the ultrasonic generator 12.

[0109] Turn on heater 3, control the temperature at 102℃ to dry the moisture, and then control the temperature at 450℃ to activate the catalyst, thus completing the activation process.

[0110] After activation, retract the inclined plate 13, close the outlet 14, and open the outlet damper 15 and the inlet damper 1. The catalyst can then undergo normal denitrification.

[0111] Comparative Example 2:

[0112] Close the inlet damper 1 and outlet damper 15 of the denitrification tower, and open the inclined plate 13 and the outlet 14. Turn on the back-blowing high-pressure blower 6, adjust the blowing pressure to 0.8 MPa, and blow with the back-blowing nozzle 5 for 30 minutes, then turn off the back-blowing blower 6; turn on the regeneration pump 7, ultrasonic generator 12, water washing tank 8 outlet valve a2, and inlet valve a1, and use the atomizing nozzle 4 to spray atomized cleaning liquid to clean the catalyst. The cleaning agent content is 3% surfactant, and the rest is deionized water. The cleaning time is 40 minutes, then close the outlet valve.

[0113] Open outlet valve C2 and inlet valve C1 of alkaline washing tank 10 to clean the catalyst. The cleaning agent is 20% ammonia water in ammonium carbonate solid, with a liquid-to-solid ratio of 6:1. The alkaline washing time is 1 hour. After completion, close outlet valve C2 and inlet valve C1.

[0114] Open the outlet valve d2 and inlet valve d1 of the activation repair tank 11 to activate and repair the catalyst. The activator is 0.8wt% ammonium metavanadate and 6wt% ammonium paratungstate. The activation time is 20min. After completion, close the outlet valve d2 and inlet valve d1, and turn off the ultrasonic generator 12.

[0115] Turn on heater 3, control the temperature at 102℃ to dry the moisture, and then control the temperature at 450℃ to activate the catalyst, thus completing the activation process.

[0116] After activation, retract the inclined plate 13, close the outlet 14, and open the outlet damper 15 and the inlet damper 1. The catalyst can then undergo normal denitrification.

[0117] Comparative Example 3

[0118] Close the inlet damper 1 and outlet damper 15 of the denitrification tower, and open the inclined plate 13 and the outlet 14. Turn on the back-blowing high-pressure blower 6, adjust the blowing pressure to 0.8 MPa, and blow with the back-blowing nozzle 5 for 30 minutes, then turn off the back-blowing blower 6; turn on the regeneration pump 7, ultrasonic generator 12, water washing tank 8 outlet valve a2, and inlet valve a1, and use the atomizing nozzle 4 to spray atomized cleaning liquid to clean the catalyst. The cleaning agent content is 3% surfactant, and the rest is deionized water. The cleaning time is 40 minutes, then close the outlet valve.

[0119] Open outlet valve b2 and inlet valve b1 of pickling tank 9 to clean the catalyst. The sulfuric acid concentration is 0.2 mol / L, and the cleaning time is 30 minutes. After completion, close outlet valve b2 and inlet valve b1.

[0120] Open the outlet valve d2 and inlet valve d1 of the activation repair tank 11 to activate and repair the catalyst. The activator is 0.8wt% ammonium metavanadate and 6wt% ammonium paratungstate. The activation time is 20min. After completion, close the outlet valve d2 and inlet valve d1, and turn off the ultrasonic generator 12.

[0121] Turn on heater 3, control the temperature at 102℃ to dry the moisture, and then control the temperature at 450℃ to activate the catalyst, thus completing the activation process.

[0122] After activation, retract the inclined plate 13, close the outlet 14, and open the outlet damper 15 and the inlet damper 1. The catalyst can then undergo normal denitrification.

[0123] The regeneration effects described in Examples 1-3 and Comparative Examples 1-3 were compared, and the experimental results are shown in Table 1 below:

[0124] Table 1. Comparison of catalyst regeneration effects between Examples 1-3 and Comparative Examples 1-3

[0125] Na removal rate % K removal rate % Ca removal rate % Denitrification efficiency % Example 1 72 54 39 94 Example 2 77 62 44 96 Example 3 79 63 45 97 Comparative Example 1 70 52 38 88 Comparative Example 2 62 44 37 85 Comparative Example 3 71 53 32 82

[0126] The data in the table above shows that the in-situ regeneration system provided in this invention has a better effect on the cleaning and regeneration process of the catalyst. When the catalyst is cleaned using the catalyst regeneration methods in Examples 1-3, the removal rates of Na, K, and Ca in the catalyst are all higher than those in the catalyst regeneration methods in Comparative Examples 1-3. The denitrification efficiency of the regenerated catalysts in Examples 1-3 can reach over 90%, saving time and cost, while the denitrification efficiency of the regenerated catalysts in the comparative examples is less than 90%. Therefore, the in-situ SCR catalyst regeneration system and method provided in this invention have a good catalyst regeneration effect, can thoroughly remove fly ash, alkali metals, alkaline earth metals, and heavy metals from the catalyst, and solve the catalyst poisoning problem caused by these substances.

[0127] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. An in-situ regeneration system for SCR catalysts, characterized in that, Located between the inlet and outlet of the denitrification tower, the system includes a back-blowing system, a cleaning system, a flue gas heating system, and a cleaning liquid recycling system. The back-blowing system is used to remove accumulated dust from the surface and interior of the catalyst; the cleaning system is used to clean the catalyst; the flue gas heating system promotes the evaporation of moisture from the cleaned catalyst and the decomposition of precursors of active components on the catalyst surface, thereby achieving catalyst regeneration; the cleaning liquid recycling system is connected to the cleaning system and is used to recover the cleaning liquid. The cleaning system includes multiple parallel cleaning units, as well as a regeneration pump and a cleaning nozzle. The cleaning units, the regeneration pump, and the cleaning nozzle are all connected by cleaning pipes, and the cleaning nozzle is directly facing the catalyst. The multiple parallel cleaning units include a water washing unit, an acid washing unit, an alkaline washing unit, and an activity restoration unit connected in parallel. The water washing unit is used to remove ash and water-soluble contaminants from the catalyst. The acid washing unit and the alkaline washing unit are used to remove water-insoluble dirt from the catalyst, including alkali metals, sulfates, and silica. The activity restoration unit is used to restore the content of active components in the catalyst. The water washing unit includes a water washing tank containing deionized water and a surfactant; the acid washing unit includes an acid washing tank containing a sulfuric acid solution; the alkaline washing unit includes an alkaline washing tank containing an ammonia solution and ammonium carbonate; the active repair unit includes an active repair tank containing ammonium metavanadate and ammonium paratungstate. The water washing tank, the acid washing tank, the alkali washing tank, and the active repair tank are all equipped with inlet valves and outlet valves at the front and back. The inlet valves are connected to the outlet of the cleaning solution circulation and recovery system through pipelines, and the outlet valves are connected to the regeneration pump. The recycling system includes an inclined plate and a discharge port. The discharge port is located at the bottom of the denitrification tower. One end of the inclined plate is located at the bottom of the catalyst, and the other end is close to the discharge port and located 1cm to 3cm below the discharge port. The regeneration system also includes an ultrasonic generator disposed at the end of the catalyst.

2. The SCR catalyst in-situ regeneration system according to claim 1, characterized in that, The catalyst includes n denitrification units, and the backflush system includes a high-pressure blower and n backflush nozzles connected to the high-pressure blower, with the backflush nozzles facing the denitrification units.

3. The SCR catalyst in-situ regeneration system according to claim 1, characterized in that, The cleaning nozzle is an atomizing nozzle.

4. A method for in-situ regeneration of an SCR catalyst, characterized in that, The in-situ regeneration system for the SCR catalyst described in any one of claims 1-3 is used, comprising the following steps: Close the inlet and outlet dampers of the denitrification tower and use a back-blowing system to purge the catalyst; The catalyst is cleaned using a cleaning system, and the cleaning fluid is recovered using a cleaning fluid recycling system. Turn on the flue gas heating system, dry the catalyst, and activate the catalyst. To complete the in-situ regeneration process of the SCR catalyst, open the inlet and outlet dampers of the denitrification tower.

5. The in-situ regeneration method for SCR catalyst according to claim 4, characterized in that, The catalyst is purged using a back-blowing system, which includes: turning on the back-blowing high-pressure blower, adjusting the blowing pressure, purging the catalyst with the back-blowing nozzle for a preset time, and then turning off the back-blowing blower. The process of using a cleaning system to clean the catalyst and using a cleaning solution recycling system to recover the cleaning solution specifically includes: opening the inclined plate and the outlet, and sequentially using a water washing unit, an acid washing unit, an alkaline washing unit, and an activity repair unit to clean and repair the catalyst. The process of opening the flue gas heating system, drying the catalyst, and activating the catalyst specifically includes: turning on the heater, first controlling the temperature to the drying temperature to dry the moisture in the catalyst, and then controlling the temperature to the activation temperature to activate the catalyst.

6. The in-situ regeneration method for SCR catalyst according to claim 5, characterized in that, Before cleaning and repairing the catalyst using the water washing unit, acid washing unit, alkali washing unit, and activity repair unit in sequence, turn on the ultrasonic generator.

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