Hardening liquid and hardening method for denitration catalyst unit end

Abstract

The invention discloses a hardening liquid and a hardening method for a denitration catalyst unit end, the hardening liquid comprises a component A solution and a component B solution, the component A solution is a calcium salt-containing solution, the component B is a sulfate-containing solution, and both the calcium salt and the sulfate are soluble salts. According to the invention, the hardening operation can be completed by drying at a relatively low temperature, and the end hardening effect of the denitration catalyst can be ensured.

Description

Technical Field

[0001] This invention relates to the technical field of denitrification catalysts, and more specifically to a hardening liquid and hardening method for the end of a denitrification catalyst unit. Background Technology

[0002] With the promulgation of the "Emission Standard of Air Pollutants for Thermal Power Plants" (GB13223-2011), denitrification catalysts have been widely used in denitrification retrofit projects of coal-fired power plants in my country. According to the performance characteristics of denitrification catalysts, denitrification devices are generally arranged before electrostatic precipitators. The dust content of flue gas from coal-fired power plants generally reaches 30-60 g / Nm3. Therefore, denitrification catalysts need to undergo end hardening treatment to reduce catalyst wear caused by fly ash particles in the flue gas impacting the catalyst ends.

[0003] Existing end-hardening methods involve immersing one end of the denitrification catalyst in a specially prepared hardening solution. The catalyst end absorbs the hardening solution, thus achieving end-hardening. For example, Chinese invention patent application No. 201410351756.0 discloses a hardening solution for a honeycomb SCR denitrification catalyst unit and its application method. The hardening solution is a mixed solution of aluminum sulfate and organic acid. Through heating, soaking, drying, and calcination, an alumina layer is formed on the catalyst surface to improve its wear resistance. However, aluminum sulfate cannot form an alumina layer unless subjected to high-temperature calcination. The temperature required for aluminum sulfate to decompose into alumina is around 770℃. However, if this temperature is used for calcination, it will cause partial sintering and deactivation of the denitrification catalyst. In Chinese invention patent application No. 201810310923.5, a hardening liquid for the end of a honeycomb denitrification catalyst unit and its application method are disclosed. The hardening liquid uses a sodium hydroxide and aluminum sulfate formula. By soaking, drying, heating soaking, drying, and calcining, an alumina layer is generated on the catalyst surface to improve the catalyst's wear resistance. However, it requires calcination at 140-300℃, which consumes a lot of energy.

[0004] Therefore, developing a novel hardening liquid for the end of a denitrification catalyst unit that can complete the hardening operation at a lower temperature has become a pressing technical problem to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to provide a hardening liquid and a hardening method for the end of a denitrification catalyst unit, which can complete the hardening operation by drying at a lower temperature and ensure the hardening effect of the end of the denitrification catalyst.

[0006] To achieve one aspect of the above-mentioned objectives, the present invention adopts the following technical solution: A hardening solution for the end of a denitrification catalyst unit, the hardening solution comprising a component A solution and a component B solution, wherein the component A solution is a calcium salt solution and the component B solution is a sulfate solution, wherein both the calcium salt and the sulfate are soluble salts.

[0007] Preferably, the calcium salt is one or more of calcium chloride, calcium nitrate, calcium dihydrogen phosphate, calcium bicarbonate, calcium bisulfate, calcium hypochlorite, calcium chlorate, and calcium perchlorate.

[0008] Preferably, the sulfate is one or more selected from potassium sulfate, sodium sulfate, magnesium sulfate, aluminum sulfate, manganese sulfate, zinc sulfate, ferric sulfate, ferrous sulfate, and copper sulfate.

[0009] Preferably, in the A component solution, the weight ratio of calcium salt to water is (5-100):100, more preferably (50-75):100; in the B component solution, the weight ratio of sulfate to water is (5-60):100, more preferably (30-50):100.

[0010] Preferably, the calcium salt is calcium chloride, and the sulfate is sodium sulfate.

[0011] To achieve another aspect of the above-mentioned objectives, the present invention adopts the following technical solution: A method for hardening the end of a denitrification catalyst unit, the hardening method comprising: (1) Prepare the hardening solution as described above; (2) Immerse the end of the denitrification catalyst unit in the A component solution of the hardening liquid, remove it and air dry it to obtain a first-time solution; (3) Then the end of the denitrification catalyst unit is immersed in the B component solution of the hardening liquid, taken out and dried to obtain the catalyst unit with hardened end.

[0012] Preferably, in step (3), during drying, the end of the impregnated denitrification catalyst unit is first dried, and then placed in a drying oven at 60-120℃, preferably 80-120℃, for 3-8 hours.

[0013] Preferably, in step (2), the soaking time is 10s-60s, more preferably 20s-30s.

[0014] Preferably, in step (3), the soaking time is 10s-60s, more preferably 20s-30s.

[0015] Preferably, the immersion temperature of the A component solution is 5-60°C, more preferably 10-30°C.

[0016] Preferably, the immersion temperature of the component B solution is 40-60°C, more preferably 45-55°C.

[0017] Preferably, the denitrification catalyst unit end is a honeycomb denitrification catalyst unit end.

[0018] Compared with the prior art, the present invention has the following advantages: This invention involves first immersing the end of the denitrification catalyst unit in a mixed solution of component A of the hardening liquid. After a period of time, it is removed and dried, forming a calcium chloride precipitate that is evenly distributed on the immersed portion of the denitrification catalyst unit end. Then, it is immersed in a mixed solution of component B of the hardening liquid, and again removed and dried after a period of time. Finally, it is dried in a drying oven at 60-120℃ (without using the existing high calcination decomposition temperature), which forms a dense layer of calcium sulfate on the end of the catalyst unit. This improves the wear resistance of the catalyst and ensures the end hardening effect of the denitrification catalyst.

[0019] This invention provides a novel hardening liquid for the end of a honeycomb denitrification catalyst unit and its application method. The hardening operation can be completed by drying at a relatively low temperature, and the hardening effect of the denitrification catalyst end can be guaranteed. Detailed Implementation

[0020] To enable those skilled in the art to better understand the present invention, the technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0021] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and should be understood to include values ​​close to these ranges or values, such as values ​​±10% of the endpoint values. For numerical ranges, endpoint values ​​of various ranges, endpoint values ​​of various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. Without conflict, the embodiments and features described in this application can be combined with each other.

[0022] It should be noted that the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, for example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or device.

[0023] The present invention provides a hardening solution for hardening the end of a denitrification catalyst unit, comprising a component A solution and a component B solution. The component A solution is a calcium salt solution, and the component B solution is a sulfate solution. Both the calcium salt and sulfate mentioned are soluble salts, for example, with a solubility in water greater than 10 g / 100 mL at 20 °C. It is understood in the art that the calcium salt solution is an aqueous solution containing dissolved calcium salt, and the sulfate solution is an aqueous solution containing dissolved sulfate. The two solutions are stored separately for subsequent impregnation.

[0024] In some embodiments, the calcium salt is one or more of calcium chloride, calcium nitrate, calcium dihydrogen phosphate, calcium bicarbonate, calcium bisulfate, calcium hypochlorite, calcium chlorate, and calcium perchlorate, preferably calcium chloride.

[0025] In some embodiments, the weight ratio of calcium salt to water in the A component solution is (5-100):100, such as 10:100, 20:100, 30:100, 40:100, 50:100, 60:100, 70:100, 80:100 or 90:100; preferably, the weight ratio of calcium salt to water in the A component solution is (50-75):100.

[0026] In some embodiments, the sulfate is one or more of potassium sulfate, sodium sulfate, magnesium sulfate, aluminum sulfate, manganese sulfate, zinc sulfate, ferric sulfate, ferrous sulfate, and copper sulfate, preferably sodium sulfate.

[0027] In some embodiments, the weight ratio of sulfate to water in the component B solution is (5-60):100, such as 10:100, 20:100, 30:100, 40:100, 50:100 or 60:100; preferably, the weight ratio of sulfate to water in the component B solution is (30-50):100.

[0028] In the hardening method for the end of the denitrification catalyst unit provided by the present invention, the hardening method includes: (1) Prepare the hardening solution as described above; (2) Immerse the end of the denitrification catalyst unit in the A component solution of the hardening liquid, remove it and air dry it to obtain a first-time solution; (3) Then the end of the denitrification catalyst unit is immersed in the B component solution of the hardening liquid, taken out and dried to obtain the catalyst unit with hardened end.

[0029] In step (1) of the present invention, the A component solution and the B component solution of the hardening liquid as described above are prepared respectively for subsequent impregnation.

[0030] In step (2) of the present invention, the end of the denitrification catalyst unit is immersed in the solution of component A. The immersion time can be 10s-60s, preferably 20-30s. It is understood in the art that if the time is too short, it will not be conducive to the loading of component A onto the catalyst, and the loading amount will be too small, which will affect the hardening effect. If the time is too long, a thicker cover will be formed, which will affect the uniform reaction with component B and affect the hardening effect.

[0031] In step (2) of the present invention, the immersion temperature of the A component solution is not particularly limited during immersion, as long as the immersion can be completed smoothly. For example, the immersion temperature can be 5-60°C, preferably 20-30°C.

[0032] In step (2) of the present invention, the end of the impregnated denitrification catalyst unit is taken out and dried, for example, naturally dried until the water content is not higher than 20%.

[0033] In step (3) of the present invention, the dried denitrification catalyst unit end is immersed in the B component solution for a time of 10s-60s, preferably 20-30s. It is understood in the art that if the time is too short, it will not be conducive to the effective reaction with the A component. If the hardened layer is not deep enough, or if it is too long, multiple layers of B component will be formed, which will not have a hardening effect.

[0034] In step (3) of the present invention, the immersion temperature of the B component solution is preferably 40-60°C, more preferably 45-55°C. Studies have found that moderately increasing the immersion temperature is beneficial to reducing the shielding effect of surface reaction and precipitation. The B component can quickly diffuse and fully react with the already impregnated A component, resulting in good end strengthening effect. However, it is difficult to achieve the above effect if the temperature is too low or too high.

[0035] In step (3) of the present invention, during drying, preferably, the end of the impregnated denitrification catalyst unit is first dried, and then placed in a drying oven at 60-120°C, preferably 80-120°C, such as 90, 100 or 110°C, for 3-8 hours, so that the hardened layer maintains a good curing effect while the moisture evaporates.

[0036] In this invention, preferably, the denitrification catalyst unit end is a honeycomb denitrification catalyst unit end.

[0037] The present invention will be further illustrated below with reference to embodiments / comparative examples. Where specific experimental steps or conditions are not specified in the following embodiments, they can be performed according to the corresponding conventional experimental procedures or conditions in this technical field. Reagents or instruments whose manufacturers are not specified are all commercially available analytical grade products. Example 1 First, the end of the honeycomb denitrification catalyst unit was immersed in a solution of component A (60 parts calcium chloride and 100 parts water) at room temperature. After 25 seconds, it was removed and air-dried. Then, it was immersed in a solution of component B (40 parts sodium sulfate and 100 parts water) of the hardening liquid, and the temperature of component B solution was maintained at 45°C. After 30 seconds, it was removed and air-dried. Then, it was placed in a drying oven at 100°C for 5 hours to obtain catalyst unit #1 with hardened end.

[0038] Example 2 First, the end of the honeycomb denitrification catalyst unit was immersed in a solution of component A (5 parts calcium chloride and 100 parts water) at room temperature. After 60 seconds, it was removed and air-dried. Then, it was immersed in a solution of component B (5 parts sodium sulfate and 100 parts water) of the hardening liquid, and the temperature of component B solution was maintained at 50°C. After 60 seconds, it was removed and air-dried. Then, it was placed in a drying oven at 90°C for 8 hours to obtain catalyst unit #2 with hardened end.

[0039] Example 3 First, the end of the honeycomb denitrification catalyst unit was immersed in a solution of component A (100 parts calcium chloride and 100 parts water) at room temperature. After 15 seconds, it was removed and air-dried. Then, it was immersed in a solution of component B (60 parts sodium sulfate and 100 parts water) of the hardening liquid, and the temperature of component B solution was maintained at 55°C. After 15 seconds, it was removed and air-dried. Then, it was placed in a drying oven at 120°C for 3 hours to obtain catalyst unit #3 with hardened end.

[0040] Example 4 First, the end of the honeycomb denitrification catalyst unit was immersed in a solution of component A (65 parts calcium bicarbonate and 100 parts water) at room temperature for 25 seconds, then removed and air-dried. Next, it was immersed in a solution of component B (45 parts potassium sulfate and 100 parts water) of the hardening liquid, while maintaining the temperature of component B solution at 30°C. After 30 seconds, it was removed and air-dried, and then placed in a drying oven at 90°C for 5 hours to obtain catalyst unit #4 with hardened end.

[0041] Example 5 First, the end of the honeycomb denitrification catalyst unit was immersed in a solution of component A (50 parts calcium dihydrogen phosphate and 100 parts water) at room temperature for 25 seconds, then removed and air-dried. Next, it was immersed in a solution of component B (30 parts magnesium sulfate and 100 parts water) of the hardening liquid, while maintaining the temperature of component B solution at 25°C. After 30 seconds, it was removed and air-dried, and then placed in a drying oven at 90°C for 5 hours to obtain catalyst unit #5 with hardened end.

[0042] Example 6 Compared to Example 1, the difference is that the temperature of the B component solution is 30°C. Everything else is the same as in Example 1, resulting in a hardened catalyst unit #6.

[0043] Example 7 Compared with Example 3, the difference is that the temperature of component B solution is 30°C and the impregnation time is 30 seconds. The rest is the same as in Example 3, resulting in catalyst unit #7 with hardened ends.

[0044] Example 8 Compared to Example 2, the difference is that the drying temperature is 200°C. Otherwise, the process is the same as in Example 2, resulting in a catalyst unit #8 with a hardened end.

[0045] Comparative Example 1 The end of the honeycomb denitrification catalyst unit was immersed in a saturated aluminum sulfate solution at room temperature. After 25 seconds, it was removed, dried, and calcined at 500°C for 3 hours to obtain the catalyst unit #9 with hardened end.

[0046] The catalyst units #1-#9 with hardened ends were tested according to the following method: Following the wear rate test method in the national standard GB / T31587-2015 "Cellular Flue Gas Denitrification Catalyst", two test samples were taken, each 60-70 mm in length and width and 100 mm ± 2 mm in height (the pore shape should be intact; for 22 pores, a 10×10 pore size should be used). The test samples were placed in an oven and dried at 105℃ ± 2℃ for 2 hours, then removed and weighed. The test samples were then cleaned with a sponge or high-strength material. After wrapping with lingxin, place it in the sample chamber, ensuring a complete seal between the outer wall of the sample and the chamber wall, allowing air and abrasive to flow completely through the sample's channels. Control and adjust the air velocity in the catalyst channel to 14.5 m / s ± 0.5 m / s (standard conditions), and the concentration of abrasive (dry high-hardness quartz sand with a particle size of 0.300 mm-0.425 mm) to 50 g / m³ ± 5 g / m³. Stop rinsing after 2 hours. Remove the test sample, place it in an oven, dry it at 105℃ ± 2℃ for 2 hours, then weigh it and calculate the wear rate.

[0047] The test results are as follows:

[0048] As can be seen from the above examples / comparative examples, the wear rate of the honeycomb denitrification catalyst unit ends obtained by hardening liquid treatment in the embodiments of the present invention all meet the national standard requirements. They can also reach or even exceed the wear resistance of the honeycomb denitrification catalyst unit ends treated by high temperature calcination of existing hardening liquid. This indicates that the calcium sulfate layer formed at the catalyst unit ends can also greatly improve the wear resistance of the catalyst, thereby avoiding the influence of high dust in the denitrification catalyst operating environment, reducing or avoiding wear, extending the service life of the denitrification catalyst, and improving the cost performance of the product.

[0049] Furthermore, as can be seen from Examples 1 and 6, appropriately increasing the impregnation temperature of component B is beneficial to improving the anti-wear effect; similarly, as can be seen from Examples 3 and 7, appropriately increasing the impregnation temperature of component B is beneficial to anti-wear, and even extending the impregnation time is not enough to completely compensate for it; as can be seen from Examples 2 and 8, the method of the present invention does not require high-temperature drying, and even if high-temperature drying is used, the improvement is not significant and it is easy to affect the catalyst activity.

Claims

1. A hardening liquid for the end of a denitration catalyst unit, characterized by, The hardening solution comprises an A component solution and a B component solution, the A component solution is a calcium salt solution, and the B component is a sulfate salt solution, wherein the calcium salt and the sulfate salt are both soluble salts.

2. The method of claim 1, wherein, The calcium salt is one or more of calcium chloride, calcium nitrate, calcium dihydrogen phosphate, calcium hydrogen carbonate, calcium bisulfite, calcium hypochlorite, calcium chlorate, and calcium perchlorate.

3. The method according to claim 1 or 2, characterized in that, The sulfate salt is one or more of potassium sulfate, sodium sulfate, magnesium sulfate, aluminum sulfate, manganese sulfate, zinc sulfate, iron sulfate, ferrous sulfate, and copper sulfate.

4. The method according to any one of claims 1-3, characterized in that, In the A component solution, the weight ratio of the calcium salt to water is (5-100):100, preferably 60:100; and in the B component solution, the weight ratio of the sulfate salt to water is (5-60):100, preferably 40:

100.

5. The method according to any one of claims 1-4, characterized in that, The calcium salt is calcium chloride, and the sulfate salt is sodium sulfate.

6. A method of hardening the end of a denitration catalyst unit, characterized by, The hardening method comprises: (1) preparing the hardening solution according to any one of claims 1-5; (2) immersing the end of the denitration catalyst unit in the A component solution of the hardening solution, taking it out and drying to obtain a first; (3) then immersing the end of the denitration catalyst unit in the B component solution of the hardening solution, taking it out and drying to obtain a hardening catalyst unit.

7. The hardening method according to claim 6, characterized by In step (3), when drying, first dry the immersed end of the denitration catalyst unit, and then place it in a drying oven at 60-120°C, preferably 80-120°C, and heat it for 3-8 hours.

8. The hardening method according to claim 6 or 7, characterized in that, In step (2), the immersion time is 10s-60s, preferably 20s-30s; In step (3), the immersion time is 10s-60s, preferably 20s-30s.

9. The hardening method according to any one of claims 6 to 8, characterized in that, The immersion temperature of the A component solution is 5-60°C, preferably 20-30°C; The immersion temperature of the B component solution is 40-60°C, preferably 45-55°C.

10. The hardening method according to any one of claims 6 to 9, characterized in that, The end of the denitration catalyst unit is a honeycomb denitration catalyst unit.

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