An in-situ regeneration method for deactivated SCR denitration catalyst

Abstract

This invention discloses an in-situ regeneration method for deactivated SCR denitrification catalysts, belonging to the field of regenerated denitrification catalysts. The regeneration process is carried out by introducing hot air into the SCR denitrification catalyst through a flue gas duct. The main steps include low-frequency acoustic cleaning, cleaning fluid spraying, steam rinsing, and drying. This regeneration method effectively regenerates poisoned SCR denitrification catalysts in situ without disassembling the catalyst, avoiding damage to the denitrification system caused by disassembly. The cleaning process does not cause a large amount of dissolution of the catalyst's active components, leaves no harmful residues on the catalyst surface, and does not reduce the catalyst's mechanical strength or selectivity. The regenerated catalyst activity can be restored to more than 95% of that of a new catalyst, with high removal rates of alkaline earth metals, ammonium sulfate, ammonium hydrogen sulfate, and arsenic on the surface, possessing significant industrial application value.

Description

Technical Field

[0001] This invention discloses an in-situ regeneration method for deactivated SCR denitration catalysts, belonging to the field of regenerated denitration catalysts. Background Technology

[0002] As a major industrial producer, China generates substantial nitrogen oxide (NOx) emissions during the production processes of various industries, including thermal power, cement, and steel. In recent years, NOx emission requirements have become increasingly stringent. Selective Catalytic Reduction (SCR) technology is widely considered an effective strategy for achieving ultra-low NOx emissions. Among various technologies for reducing NOx emissions, SCR has been widely accepted globally as the dominant NOx emission control method (accounting for 96%) due to its highly efficient denitrification capacity (over 90%), technological maturity, and the absence of harmful byproducts. In the entire SCR system, the catalyst is a crucial component, typically accounting for 30% to 50% of the initial investment, while its lifespan is usually 2-3 years. During this period, salts and oxides of alkaline earth metals, ammonium sulfate, ammonium hydrogen sulfate, arsenic, and fly ash can easily poison and clog the catalyst, leading to its loss of activity during use.

[0003] Alkaline earth metal ions (such as K, Na, and Ca) have a strong thermodynamic affinity for the pore structure of catalysts. They may form stable deposits within the micropores of the catalyst, leading to a reduction in the catalyst surface area and thus affecting the adsorption and reaction of nitrogen oxides. The active sites of the catalyst are primarily responsible for the reduction of nitrogen oxides. However, alkaline earth metal ions may adsorb onto these active sites, hindering the adsorption and reaction of nitrogen oxides. In the presence of alkaline earth metal ions, the electronic structure of the active components in the catalyst (such as vanadium and titanium) may change, further affecting its catalytic activity. For example, alkaline earth metal ions may reduce catalytic activity by forming stable compounds with the active components, altering their oxidation state or electron density.

[0004] Ammonium sulfate and ammonium bisulfate can form deposits in the catalyst channels during cooling. This can block the effective pores of the catalyst, reducing the effective surface area and affecting its activity. These deposits may also shield active sites, preventing nitrogen oxides from reaching them and participating in the reaction, thus reducing catalyst activity. Furthermore, ammonium sulfate and ammonium bisulfate can form compounds with active components in the catalyst, altering the electronic environment of the active sites and leading to decreased catalytic activity. For example, they can form stable sulfates with active elements such as iron and vanadium, reducing their activity.

[0005] my country's coal contains a relatively high amount of arsenic, and arsenic poisoning significantly impacts catalyst activity. Under high-temperature conditions, arsenic forms arsenate, which reacts with active sites on the catalyst surface to form stable complexes. These complexes inhibit the reaction of NH3 and NO. x Arsenate formation can reach the active sites, thus preventing the reaction from proceeding. Simultaneously, arsenate formation may alter the catalyst's crystal structure, potentially affecting its surface properties and gas diffusion, thereby reducing its catalytic efficiency.

[0006] Reducing the accumulation of alkaline earth metals, ammonium sulfate, and ammonium bisulfate is crucial for maintaining the activity and extending the lifespan of SCR denitrification catalysts. In-situ cleaning to remove blockages, alkaline earth metal poisons, ammonium sulfate, ammonium bisulfate, and fly ash is widely used in industry. Researching efficient and environmentally friendly in-situ regeneration methods is of great significance for extending catalyst lifespan, reducing the operating costs of SCR systems, and minimizing environmental impact.

[0007] Although in-situ regeneration technology for SCR systems has been widely adopted, existing in-situ regeneration technologies mainly address physical blockages and blockages that can be removed by thermal decomposition. These technologies suffer from long regeneration times, require heating the flue gas to high temperatures, and cannot effectively remove poisoning substances such as alkali metal oxides. Furthermore, they lack an active component replenishment step, failing to restore and increase the surface active sites of the catalyst through in-situ regeneration. Therefore, there is an urgent need to develop an efficient, low-cost, and minimally disruptive in-situ regeneration method for SCR systems.

[0008] Patent CN106492887A discloses a method for in-situ restoration of the activity of an SCR denitrification catalyst. This method can clean the SCR denitrification catalyst without affecting the operation of the SCR system, and without disassembling the SCR system, it can effectively restore the activity of the SCR denitrification catalyst after a period of operation. However, this method involves introducing steam at high pressure for an extended period, resulting in high operating costs; furthermore, the lack of drying steam can easily lead to substances such as ammonium sulfate re-clogging the micropores on the surface of the denitrification catalyst.

[0009] Patent US8524179B2 discloses a method to control mercury emissions by mixing iodine and bromine compounds into an amine spraying system, thereby regenerating mercury-poisoned SCR denitration catalysts in situ and extending their lifespan. However, this method incorporates large amounts of iodine and bromine compounds, increasing the cost of in-situ regeneration. Furthermore, this method only addresses mercury poisoning and does not solve the problem of chemical poisoning caused by alkaline earth metals.

[0010] Patent CN107376930A discloses a method and apparatus for in-situ regeneration of sulfur-poisoned SCR denitrification catalysts. The method and apparatus can decompose ammonium sulfate deposited on the catalyst surface at temperatures ranging from 200℃ to 380℃, thereby improving the activity of sulfur-poisoned catalysts. The method achieves in-situ decomposition of ammonium sulfate by installing an ozone generator into the SCR denitrification system; however, this modification increases the cost of the SCR denitrification system, the ozone generator increases power consumption, and the oxidation capacity of ozone is only slightly different from that of oxygen at the operating temperature of the SCR denitrification catalyst; furthermore, it does not effectively eliminate the influence of alkaline earth metal blockages on the denitrification system. Summary of the Invention

[0011] To address the shortcomings of the above-mentioned processes and improve the efficiency and effectiveness of in-situ regeneration, the present invention proposes the following solution.

[0012] This invention discloses a method for in-situ regeneration of alkaline earth metal poisoned SCR denitration catalysts. This method can efficiently regenerate alkaline earth metal poisons on the surface of poisoned SCR denitration catalysts. The purpose of this invention is to solve the problems existing in related technologies: long regeneration time, limited ability to restore chemically poisoned surfaces, inability to replenish active components, and inability to restore surface structure.

[0013] To achieve the above objectives, the present invention is implemented through the following scheme:

[0014] An in-situ regeneration method for deactivated SCR denitrification catalysts, wherein the regeneration process is carried out with hot air introduced into the SCR denitrification catalyst through a flue gas duct, and the denitrification catalyst unit for in-situ regeneration is as follows: Figure 1 As shown, it includes the following steps, the process is as follows: Figure 2 As shown:

[0015] (1) The catalyst was subjected to low-frequency acoustic cleaning treatment for 5-60 minutes;

[0016] (2) Mix and spray the cleaning solution using an ammonia sprayer for 5-30 minutes;

[0017] (3) Cleaning is performed using saturated steam from an ammonia injector for 5-30 minutes;

[0018] (4) Spray the active replenishing solution through the ammonia sprayer for 1-10 minutes;

[0019] (5) Dry the SCR denitrification catalyst.

[0020] Furthermore, the temperature of the hot air introduced through the flue gas duct is 100-170℃, and the air pressure at the inlet is adjusted to 0.1MPa-1.0MPa.

[0021] Furthermore, in step (1), the energy density of the low-frequency sound wave is 10-100h. 3.

[0022] Further, the cleaning solution in step (2) consists of citric acid and hydrogen peroxide solution, wherein the concentration of citric acid is 0.1-10.0 wt.%, the concentration of hydrogen peroxide is 0.1-10.0 wt.%, and the remainder is water. The added citric acid has a decomposition temperature of 175℃ and can remain stable under conditions of passing hot air at 100-170℃, reacting with alkali metals on the surface of the denitrification catalyst to effectively remove surface alkali metals. Adding H2O2 can lower the decomposition temperature of ammonium sulfate and ammonium hydrogen sulfate.

[0023] Furthermore, the spray flow rate of the cleaning fluid in step (2) is 0.5-10.0 L / min.

[0024] Furthermore, the saturated water vapor volume flow rate in step (3) is 10% of the hot air volume.

[0025] Furthermore, the active supplement solution in step (4) contains 0.1-2.0 wt.% vanadium trinitrate (VO(NO3)3) in total, with the remainder being water.

[0026] Further, the drying process in step (5) involves adjusting the hot air temperature to 175-400℃, adjusting the hot air flow rate to make the air pressure at the inlet of the SCR denitrification system 0.1MPa-1.0MPa, and the drying time to 10-120min.

[0027] The principle of this invention

[0028] The principle of removing alkaline earth metals from the surface of SCR denitrification catalysts with citric acid: Alkaline earth metals such as Na, K, Ca, and P exist in various flue gases and easily form oxides that accumulate on the surface of SCR denitrification catalysts. These oxides are difficult to remove using conventional mechanical vibration cleaning equipment, greatly affecting the activity of the SCR denitrification catalyst. By spraying a weakly acidic citric acid solution through an ammonia injector, the solution reacts with the alkaline earth metal oxides on the surface of the SCR denitrification catalyst (1) and (2), respectively, effectively removing alkaline earth metal poisons and restoring the surface morphology of the denitrification catalyst. At the same time, citric acid is weakly acidic and will not corrode the denitrification system.

[0029] C6H8O7+MO x → M 2x / 3 (C6H5O7) + H2O (1)

[0030] The mechanism by which H2O2 lowers the decomposition temperature of ammonium sulfate and ammonium bisulfate: The active oxygen species in hydrogen peroxide (such as hydroxyl radicals OH·) can participate in the decomposition process of ammonium sulfate and ammonium bisulfate, changing the reaction pathway of the decomposition of ammonium sulfate and ammonium bisulfate, and significantly reducing the decomposition temperature of ammonium sulfate and ammonium bisulfate from 280-338℃ to 130-190℃. The reactions of hydrogen peroxide-assisted decomposition of ammonium sulfate and ammonium bisulfate are (2) and (3).

[0031] H2O2 + NO + NO2 + (NH4)2SO4 → N2 + H2O (2)

[0032] H2O2 + NO + NO2 + NH4HSO4 → N2 + H2O (3)

[0033] H2O2 is easily decomposed at high temperatures, and an environment with sufficient oxygen also helps to lower the decomposition temperature of ammonium sulfate and ammonium bisulfate, thus accelerating the regeneration process.

[0034] The principle of in-situ regeneration for As removal: As is one of the important causes of poisoning of SCR denitrification catalysts. As generally exists in the form of As2O3 and H3AsO3. As2O3 and H3AsO3 are difficult to dissolve in water and weakly acidic environments, thus hindering the removal of As by in-situ regeneration.

[0035] Under the conditions of citric acid spraying, citric acid forms a stable, water-soluble complex with the heavy metal arsenic (As) through its three carboxyl groups (-COOH), which is beneficial for removing As elements from the catalyst surface by water vapor.

[0036] Under the conditions of spraying H2O2, As2O3, H3AsO3 and H2O2 react (4) to be oxidized into H3AsO4, which is more soluble in acidic environment, which is conducive to the removal of As.

[0037] H3AsO3 + H2O2 → H3AsO4 + H2O (4)

[0038] The principle of in-situ regeneration and replenishment of active components: V is a major component of SCR denitrification catalysts. One of the main reasons for the decline in denitrification performance is the covering and loss of V acidic sites on the surface of the SCR denitrification catalyst. Spraying a solution of vanadium trinitrate oxynitrate (VO(NO3)3) can effectively replenish V. During spraying, vanadium trinitrate oxynitrate decomposes slowly; during drying, residual nitrate ions rapidly pyrolyze at temperatures of 180℃ and above to produce V2O5, replenishing the surface active components. Simultaneously, during drying, the water absorbed by the micropores on the surface of the SCR denitrification catalyst evaporates, reconstructing the microporous structure of the SCR denitrification catalyst surface, thus improving the denitrification efficiency and anti-poisoning performance of the regenerated SCR denitrification catalyst. In-situ replenishment of active components can effectively solve problems such as active component consumption and catalyst surface structure damage during the use of SCR denitrification catalysts.

[0039] Compared with the prior art, the present invention has the following advantages:

[0040] (1) No large-scale modification of the SCR denitrification catalyst unit is required. The method of the present invention utilizes the common ultrasonic dust collector and amine sprayer in the SCR denitrification catalyst unit for in-situ regeneration, which is simple to operate and easy to use in industrial applications.

[0041] (2) Deep removal of alkaline earth metal elements. By adding a weakly acidic citric acid solution through an ammonia injector, alkaline earth metal oxides are converted into easily soluble alkaline earth metal salts. The in-situ regeneration method provided by this invention can remove most of the stubborn alkaline earth metal poisons that have accumulated on the surface and invaded the surface micropores.

[0042] (3) Thermal regeneration decomposition of ammonium sulfate and ammonium bisulfate requires low temperatures. The method provided by this invention lowers the decomposition temperature of ammonium sulfate and ammonium bisulfate by adding H2O2, thereby improving the decomposition efficiency of ammonium sulfate and ammonium bisulfate.

[0043] (4) It can remove heavy metal element As. The method provided by the present invention oxidizes heavy metal element As by adding citric acid and H2O2, so as to generate As(V) compounds and complexes with good solubility, which are easily removed by water vapor washing.

[0044] (5) The active components were replenished and the surface microstructure was restored. The method provided by the present invention replenishes the surface active components by spraying a mixed solution of vanadium trinitrate and titanium citrate, restores the microstructure of the surface of the denitration catalyst, improves the denitration performance and anti-poisoning performance of the denitration catalyst, and extends the life of the denitration catalyst.

[0045] (6) It can effectively solve the problems of active component consumption and catalyst surface structure damage during the use of SCR denitrification catalyst. Attached Figure Description

[0046] Figure 1 This is a schematic diagram of an SCR denitrification catalyst unit after the addition of an in-situ regeneration device; where: 1-flue gas, 2-outlet gas flow, 3-ammonia, 4-cleaning liquid, 5-active replenishment liquid, 6-hot air pump, 7-low frequency acoustic wave generator, 8-SCR denitrification catalyst.

[0047] Figure 2 This is a flowchart of the in-situ regeneration method. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention. Those skilled in the art will fully understand the invention even without these detailed descriptions. This invention covers any substitutions, modifications, equivalent methods, and solutions made within the spirit and scope of the invention as defined in the claims.

[0049] Example 1

[0050] Hot air at 100℃ is introduced into the SCR denitrification catalyst through the flue, and the inlet air pressure is adjusted to 0.1MPa. The catalyst is then subjected to low-frequency acoustic cleaning for 60 minutes, with a low-frequency acoustic energy density of 10mW / cm². 3 Then, a cleaning solution containing 0.1 wt% citric acid and 0.1 wt% hydrogen peroxide was sprayed for 5 minutes via an ammonia injector at a flow rate of 10.0 L / min, with the remainder being water. Next, saturated steam was introduced via the ammonia injector for 30 minutes at a flow rate of 5% of the introduced hot air. Then, an activation replenishment solution containing 0.1 wt% vanadium trinitrate and the remainder being water was sprayed via the ammonia injector for 1 minute at a flow rate of 10.0 L / min. Finally, the temperature of the hot air introduced into the flue gas duct was adjusted to 175℃, and the mixture was dried for 120 minutes. Finally, the activity of the regenerated SCR denitrification catalyst was tested and found to be 95% of that of the fresh denitrification catalyst.

[0051] Example 2

[0052] Hot air at 170℃ was introduced into the SCR denitrification catalyst through the flue, and the inlet air pressure was adjusted to 1MPa. First, the catalyst underwent low-frequency acoustic cleaning for 30 minutes, with a low-frequency acoustic energy density of 15mW / cm³. 3Then, a cleaning solution containing 10.0 wt% citric acid and 4.0 wt% hydrogen peroxide was sprayed for 10 minutes via an ammonia injector at a flow rate of 5.0 L / min, with the remainder being water. Next, saturated steam was introduced via the ammonia injector for 20 minutes at a flow rate of 10% of the introduced hot air. Following this, an activation replenishment solution containing 1.0 wt% vanadium trinitrate and the remainder being water was sprayed via the ammonia injector for 7 minutes at a flow rate of 0.5 L / min. The temperature of the hot air introduced into the flue gas duct was then adjusted to 400℃, and the mixture was dried for 20 minutes. Finally, the activity of the regenerated SCR denitrification catalyst was tested and found to be 97% of that of the fresh denitrification catalyst.

[0053] Example 3

[0054] Hot air at 150℃ is introduced into the SCR denitrification catalyst through the flue, and the inlet air pressure is adjusted to 0.4MPa. The catalyst is then subjected to low-frequency acoustic cleaning for 5 minutes, with a low-frequency acoustic energy density of 100mW / cm². 3 Then, a cleaning solution containing 8.5 wt% citric acid and 8 wt% hydrogen peroxide was sprayed for 10 minutes via an ammonia injector at a flow rate of 2.0 L / min, with the remainder being water. Next, saturated steam was introduced via the ammonia injector for 25 minutes at a flow rate of 10% of the hot air flow rate. Then, an activation replenishment solution containing 2.0 wt% vanadium trinitrate and the remainder being water was sprayed via the ammonia injector for 3 minutes at a flow rate of 1.0 L / min. Finally, the temperature of the hot air introduced into the flue gas duct was adjusted to 300℃, and the gas was dried for 60 minutes. Finally, the activity of the regenerated SCR denitrification catalyst was tested and found to be 100% of that of the fresh denitrification catalyst.

[0055] Example 4

[0056] Hot air at 135℃ was introduced into the SCR denitrification catalyst through the flue, and the inlet air pressure was adjusted to 0.3MPa. The catalyst was first subjected to low-frequency acoustic cleaning for 20 minutes, with a low-frequency acoustic energy density of 50mW / cm². 3 Then, a cleaning solution containing 2.0 wt% citric acid and 2.0 wt% hydrogen peroxide was sprayed for 30 minutes via an ammonia injector at a flow rate of 0.5 L / min, with the remainder being water. Next, saturated steam was introduced via the ammonia injector for 20 minutes at a flow rate of 10% of the hot air flow rate. Then, an activation replenishment solution containing 1.5 wt% vanadium trinitrate and the remainder being water was sprayed via the ammonia injector for 2 minutes at a flow rate of 5.0 L / min. Finally, the temperature of the hot air introduced into the flue gas duct was adjusted to 200℃, and the gas was dried for 100 minutes. Finally, the activity of the regenerated SCR denitrification catalyst was tested and found to be 96% of that of the fresh denitrification catalyst.

[0057] Example 5

[0058] Hot air at 140℃ is introduced into the SCR denitrification catalyst through the flue, and the inlet air pressure is adjusted to 0.2MPa. The catalyst is then subjected to low-frequency acoustic cleaning for 15 minutes, with a low-frequency acoustic energy density of 80mW / cm². 3 Then, a cleaning solution containing 1.0 wt% citric acid and 8.0 wt% hydrogen peroxide was sprayed for 20 minutes via an ammonia injector at a flow rate of 3.0 L / min, with the remainder being water. Next, saturated steam was introduced via the ammonia injector for 10 minutes at a flow rate of 5% of the introduced hot air. Following this, an activation replenishment solution containing 1.5 wt% vanadium trinitrate and the remainder being water was sprayed for 4 minutes via an ammonia injector at a flow rate of 2.0 L / min. The temperature of the hot air introduced into the flue gas duct was then adjusted to 350℃, and the mixture was dried for 30 minutes. Finally, the activity of the regenerated SCR denitrification catalyst was tested and found to be 98% of that of the fresh denitrification catalyst.

[0059] Example 6

[0060] Hot air at 160℃ was introduced into the SCR denitrification catalyst through the flue, and the inlet air pressure was adjusted to 0.8MPa. The catalyst was first subjected to low-frequency acoustic cleaning for 40 minutes, with a low-frequency acoustic energy density of 40mW / cm². 3 Then, a cleaning solution containing 0.8 wt% citric acid and 5.0 wt% hydrogen peroxide was sprayed for 10 minutes via an ammonia injector at a flow rate of 6.0 L / min, with the remainder being water. Next, saturated steam was introduced via the ammonia injector for 10 minutes at a flow rate of 7% of the introduced hot air. Then, an activation replenishment solution containing 0.5 wt% vanadium trinitrate and the remainder being water was sprayed via the ammonia injector for 5 minutes at a flow rate of 1.5 L / min. Finally, the temperature of the hot air introduced into the flue gas duct was adjusted to 275℃, and the mixture was dried for 40 minutes. Finally, the activity of the regenerated SCR denitrification catalyst was tested and found to be 97% of that of the fresh denitrification catalyst.

[0061] Example 7

[0062] Hot air at 155℃ was introduced into the SCR denitrification catalyst through the flue, and the inlet air pressure was adjusted to 0.7MPa. The catalyst was first subjected to low-frequency acoustic cleaning for 45 minutes, with a low-frequency acoustic energy density of 20mW / cm². 3Then, a cleaning solution containing 9.0 wt% citric acid and 2.0 wt% hydrogen peroxide was sprayed for 15 minutes via an ammonia injector at a flow rate of 2.0 L / min, with the remainder being water. Next, saturated steam was introduced via an ammonia injector for 30 minutes at a flow rate of 8% of the introduced hot air. Following this, an activation replenishment solution containing 1.8 wt% vanadium trinitrate and the remainder being water was sprayed for 10 minutes via an ammonia injector at a flow rate of 2.3 L / min. The temperature of the hot air introduced into the flue gas duct was then adjusted to 250℃, and the mixture was dried for 120 minutes. Finally, the activity of the regenerated SCR denitrification catalyst was tested and found to be 99% of that of the fresh denitrification catalyst.

[0063] Example 8

[0064] Hot air at 140℃ is introduced into the SCR denitrification catalyst through the flue, and the inlet air pressure is adjusted to 0.5MPa. The catalyst is then subjected to low-frequency acoustic cleaning for 50 minutes, with a low-frequency acoustic energy density of 30mW / cm². 3 Then, a cleaning solution containing 6.5 wt% citric acid and 0.1 wt% hydrogen peroxide was sprayed for 20 minutes via an ammonia injector at a flow rate of 1.5 L / min, with the remainder being water. Next, saturated steam was introduced via the ammonia injector for 20 minutes at a flow rate of 9% of the introduced hot air. Following this, an activation replenishment solution containing 0.9 wt% vanadium trinitrate and the remainder being water was sprayed via the ammonia injector for 8 minutes at a flow rate of 3.0 L / min. The temperature of the hot air introduced into the flue gas duct was then adjusted to 325℃, and the mixture was dried for 90 minutes. Finally, the activity of the regenerated SCR denitrification catalyst was tested and found to be 100% of that of the fresh denitrification catalyst.

[0065] Example 9

[0066] Hot air at 135℃ was introduced into the SCR denitrification catalyst through the flue, and the inlet air pressure was adjusted to 0.2MPa. The catalyst was first subjected to low-frequency acoustic cleaning for 5 minutes, with a low-frequency acoustic energy density of 100mW / cm². 3 Next, a cleaning solution containing 0.1 wt% citric acid and 7.0 wt% hydrogen peroxide was sprayed for 10 minutes via an ammonia injector at a flow rate of 4.0 L / min, with the remainder being water. Then, saturated steam was introduced via the ammonia injector for 15 minutes at a flow rate of 6% of the introduced hot air. Next, an activation replenishment solution containing 0.3 wt% vanadium trinitrate and the remainder being water was sprayed via the ammonia injector for 2 minutes at a flow rate of 5.0 L / min. Finally, the temperature of the hot air introduced into the flue gas duct was adjusted to 390℃, and the gas was dried for 25 minutes. Finally, the activity of the regenerated SCR denitrification catalyst was tested and found to be 98% of that of the fresh denitrification catalyst.

[0067] Example 10

[0068] Hot air at 145℃ was introduced into the SCR denitrification catalyst through the flue, and the inlet air pressure was adjusted to 0.4MPa. The catalyst was first subjected to low-frequency acoustic cleaning for 10 minutes, with a low-frequency acoustic energy density of 70mW / cm². 3 Then, a cleaning solution containing 0.5 wt% citric acid and 6.0 wt% hydrogen peroxide was sprayed for 30 minutes via an ammonia injector at a flow rate of 0.8 L / min, with the remainder being water. Next, saturated steam was introduced via the ammonia injector for 15 minutes at a flow rate of 8% of the introduced hot air. Then, an activation replenishment solution containing 0.5 wt% vanadium trinitrate and the remainder being water was sprayed via the ammonia injector for 2 minutes at a flow rate of 7.0 L / min. Finally, the temperature of the hot air introduced into the flue gas duct was adjusted to 350℃, and the mixture was dried for 35 minutes. Finally, the activity of the regenerated SCR denitrification catalyst was tested and found to be 100% of that of the fresh denitrification catalyst.

[0069] Example 11

[0070] Hot air at 165℃ was introduced into the SCR denitrification catalyst through the flue, and the inlet air pressure was adjusted to 1.0 MPa. The catalyst was first subjected to low-frequency acoustic cleaning for 30 minutes, with a low-frequency acoustic energy density of 20 mW / cm². 3 Then, a cleaning solution containing 10.0 wt% citric acid and 0.1 wt% hydrogen peroxide was sprayed for 20 minutes via an ammonia injector at a flow rate of 1.0 L / min, with the remainder being water. Next, saturated steam was introduced via an ammonia injector for 30 minutes at a flow rate of 7% of the introduced hot air. Following this, an activation replenishment solution containing 2.0 wt% vanadium trinitrate and the remainder being water was sprayed for 10 minutes via an ammonia injector at a flow rate of 5.0 L / min. The temperature of the hot air introduced into the flue gas duct was then adjusted to 350℃, and the mixture was dried for 60 minutes. Finally, the activity of the regenerated SCR denitrification catalyst was tested and found to be 101% of that of the fresh denitrification catalyst.

Claims

1. An in-situ regeneration method for deactivated SCR denitration catalyst, characterized in that, The regeneration process is carried out with the deactivated SCR denitrification catalyst being introduced into the flue gas pipeline with hot air at 100–170°C, and includes the following steps: (1) The catalyst is subjected to low-frequency acoustic cleaning treatment for 5-60 min; the energy density of the low-frequency acoustic wave is 10-100 mW / cm³. 3 ; (2) The cleaning solution is mixed and sprayed through an ammonia sprayer. The cleaning solution consists of citric acid and hydrogen peroxide solution. The spraying time is 5 to 30 minutes. (3) Cleaning is performed using saturated steam from an ammonia injector for 5 to 30 minutes; (4) Spray the active replenishing solution through an ammonia sprayer. The active replenishing solution contains 0.1 to 2.0 wt.% of vanadium trinitrate oxygenate VO(NO3)3, with the remainder being water. The spraying time is 1 to 10 minutes. (5) Dry the SCR denitrification catalyst at 175~400℃.

2. The in-situ regeneration method for a deactivated SCR denitration catalyst according to claim 1, characterized in that, Adjust the gas pressure at the flue gas inlet to 0.1–1.0 MPa.

3. The in-situ regeneration method for a deactivated SCR denitration catalyst according to claim 1, characterized in that, In step (2), the concentration of citric acid is 0.1-25.0 wt.%, the concentration of hydrogen peroxide is 0.1-8.0 wt.%, and the remainder is water.

4. The in-situ regeneration method for a deactivated SCR denitration catalyst according to claim 1, characterized in that, The spray flow rate of the cleaning fluid in step (2) is 0.5 to 10.0 L / min.

5. The in-situ regeneration method for a deactivated SCR denitration catalyst according to claim 1, characterized in that, The saturated water vapor volume flow rate in step (3) is 5-10% of the hot air introduced.

6. The in-situ regeneration method for a deactivated SCR denitration catalyst according to claim 1, characterized in that, The spray flow rate of the active supplement solution in step (4) is 0.5 to 10.0 L / min.

7. The in-situ regeneration method for a deactivated SCR denitration catalyst according to claim 1, characterized in that, The drying process in step (5) involves adjusting the hot air temperature to 175–400°C and the drying time to 20–120 min.

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