Method for selecting and designing catalyst for wide temperature denitration project, catalyst and application

Abstract

This paper provides a catalyst selection and design methodology for wide-temperature denitrification projects, including: obtaining flue gas parameters; calculating catalyst surface velocity; and calculating the design efficiency η of the denitrification project. 设计 = (c1-c2) / c1; Calculate the design ammonia-nitrogen molar ratio MR of the denitrification project. 设计 =η 设计 +c3 / c1; Calculate the required activity K after the catalyst has been running for 24000 hours using the formula K=0.5×Av×ln(MR / (MR-η) / (1-η)). L24000 and K H24000 Based on the expression (x)V₂O₅-(y)MoO₃ / TiO₂, a wide-temperature denitration catalyst was selected; its activity value K was tested; based on K… 24000 / K0=b, to obtain the required initial active K H0 and K L0 Select operating temperatures where the activity value is higher than K, respectively. L0 and K H0 The wide-temperature denitration catalyst with the smallest x-value is selected. A suitable wide-temperature catalyst can be chosen.

Description

Technical Field

[0001] This invention belongs to the field of catalysts, specifically relating to the selection and design method of catalysts for wide-temperature denitrification projects, as well as the catalysts and their applications. Background Technology

[0002] Coal-fired power plants are NO x One of the main sources of NO emissions. The best technical approach to meet standards is selective catalytic reduction of ammonia (NH3-SCR). Traditional commercial V2O5 / WO3-TiO2 catalysts are commonly used in flue gas denitrification in coal-fired power plants, with an optimal activity temperature range of 300-420℃. However, during deep peak-shaving and low-load operation, the flue gas temperature is only 250-300℃, lower than the 300-420℃ operating temperature of conventional denitrification catalysts, resulting in higher NO emissions. x Major problems include exceeding standards, high ammonia slip, increased operating costs, and potential safety hazards. By increasing the V2O5 content of the active component in conventional catalysts and adjusting the active additives, denitrification of the catalyst can be achieved over a wider temperature range.

[0003] As the V₂O₅ content in the catalyst increases, both the denitrification performance and SO₂ oxidation rate of the catalyst improve. When the V₂O₅ content is less than 1.2%, the denitrification efficiency increases significantly with increasing V₂O₅ content, while the SO₂ oxidation rate does not increase significantly. When the V₂O₅ content is greater than 1.2%, the SO₂ oxidation rate increases exponentially, while the denitrification efficiency hardly increases. In engineering design, increasing the catalyst volume or increasing the V₂O₅ content is usually used to improve the overall denitrification efficiency of the denitrification system. To ensure the safe operation of the catalyst and air preheater, the catalyst V₂O₅ content is controlled below 1.2%, and the catalyst loading volume is calculated. However, this problem is not addressed in the design of catalyst selection. Summary of the Invention

[0004] The first objective of this invention is to provide a method for selecting and designing catalysts for wide-temperature denitrification projects, which can select catalysts capable of achieving NO reduction. x A wide-temperature denitrification catalyst that meets ultra-low emission standards, has low NH3 escape, and low SO2 oxidation rate;

[0005] A second objective of this invention is to provide a wide-temperature denitrification catalyst obtained according to the aforementioned selection and design method.

[0006] The third objective of this invention is to provide the aforementioned selection and design method and the application of the aforementioned wide-temperature denitrification catalyst in wide-temperature denitrification engineering.

[0007] To achieve the first objective of this invention, the following technical solution is adopted:

[0008] A method for selecting and designing catalysts for wide-temperature denitrification projects includes the following steps:

[0009] (1) Obtain the flue gas flow rate Q, temperature T, and NO under the lowest and highest loads within the deep peak-shaving load range of the power plant. x The concentrations of SO2, SO3, O2, and H2O;

[0010] (2) Based on the parameters of the original n-layer catalyst of the unit, n≥2, including the volume V of the n-layer catalyst from top to bottom. 首 ~V 末 And the geometric specific surface area S of the n catalyst layers from top to bottom 首 ~S 末 The surface area of ​​each catalyst layer is calculated based on V×S, and then the surface velocity of the catalyst is calculated based on Av=Q / (the sum of the surface areas of n catalyst layers);

[0011] (3) Based on the NO inlet of the first-layer catalyst x Concentration c1 and NO at the outlet of the last catalyst layer x Given concentration c2, calculate the design efficiency η of the entire denitrification project. 设计 = (c1-c2) / c1;

[0012] (4) Based on c1 and η in step (3) 设计 And the outlet NH3 concentration c3 of the final catalyst layer that meets emission standards, calculate the design ammonia-nitrogen molar ratio MR of the entire denitrification project. 设计 =η 设计 +c3 / c1;

[0013] (5) Based on the formula K=0.5×Av×ln(MR / (MR-η) / (1-η)), calculate the required activity K of the catalyst under the minimum and maximum load conditions after 24000h of catalyst operation. L24000 and K H24000 ;

[0014] (6) Select a wide-temperature denitration catalyst according to the expression (x)V2O5-(y)MoO3 / TiO2; where TiO2 is the catalyst support, MoO3 accounts for y% of the catalyst, and V2O5 accounts for x% of the catalyst; x = 0.5-3, such as 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8 and 2.9; y = 0.1-8, such as 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7 and 7.5;

[0015] (7) The activity value K of the wide-temperature denitrification catalyst (x)V2O5-(y)MoO3 / TiO2 in step (6) was tested, and its activity value K was tested at different x values, different y values ​​and different operating temperatures.

[0016] (8) Based on the active K obtained in step (5) H24000 and K L24000 According to the attenuation coefficient K 24000 / K0=b, b=0.65-0.85, different values ​​represent the attenuation coefficient of the catalyst in different coal flue gas, such as 0.66, 0.67, 0.68, 0.69, 0.70, 0.71, 0.72, 0.73, 0.74, 0.75, 0.76, 0.77, 0.78, 0.79, 0.80, 0.81, 0.82, 0.83 and 0.84, to obtain the initial activity K of the wide-temperature denitrification catalyst in step (6) at the lowest and highest operating temperatures. L0 and K H0 ;

[0017] (9) Based on the activity value K obtained in step (7), select a temperature range where the activity value is higher than K at the lowest and highest operating temperatures as specified in step (8). L0 and K H0 The wide-temperature denitration catalyst with the smallest x-value.

[0018] Those skilled in the art will understand that the parameters in step (1) can be obtained from the unit's denitrification system design document, ultra-low emission retrofit technology agreement, and low-NOx combustion retrofit technology agreement, etc. The power plant's deep peak-shaving load range can be obtained based on the power plant's deep peak-shaving technology requirements.

[0019] In this invention, in step (1), SO2, SO3, and NO... x The concentrations are calculated based on 6% O2, i.e., SO2 concentration is SO2 / 6%O2, SO3 concentration is SO3 / 6%O2, and NO concentration is... x The concentration of NO x / 6% O2. H2O refers to water vapor.

[0020] Those skilled in the art will understand that the actual oxygen content in the atmosphere is 21%, and the concentration in coal-fired power plants is generally calculated based on 6% O2. For example, NO... x / 6%O2=(NO x (actual concentration) × (21-6) / (21-O2 actual concentration).

[0021] Those skilled in the art will understand that the formula for calculating denitrification efficiency η 设计 In the equation (c1-c2) / c1, the denitrification efficiency is expressed in percent (%).

[0022] Those skilled in the art will understand that in step (7), the test of the catalyst activity value K is actually to first test the catalyst's denitrification efficiency η, and then calculate the activity value based on the denitrification efficiency, surface velocity, and the formula K = -AV × ln(1-η). This is a well-known method in the art for obtaining the activity value K.

[0023] Those skilled in the art will understand that the precursor of the active component V2O5, ammonium metavanadate, is expensive. In step (9), the activity value is higher than K at the minimum and maximum operating temperatures specified in step (8). L0 and K H0 Based on this, selecting the wide-temperature denitration catalyst with the smallest x-value can reduce the SO2 oxidation rate and control costs to the minimum while meeting the required activity. This reduces ammonium bisulfate formation and ensures economic viability while maintaining catalyst activity. If a wide-temperature denitration catalyst with a larger x-value is selected while meeting the required activity, its activity and denitration effect may be slightly improved, but the economic cost increases, resulting in poor economic efficiency. Furthermore, a higher V2O5 content (x-value) indicates a stronger SO2 oxidation capacity of the catalyst, increasing the risk of catalyst failure. Considering all factors, selecting the wide-temperature denitration catalyst with the smallest x-value is preferable. In this invention, MoO3 has little impact on catalyst selection; that is, the value of y has little effect on catalyst selection. MoO3 mainly helps the catalyst resist poisoning and has little impact on the catalyst's operating temperature window.

[0024] Those skilled in the art understand that the chemical lifetime of a catalyst is 24,000 hours, or three years; that is, it must meet the requirements for ultra-low emissions even after 24,000 hours. Therefore, step (5) calculates the required activity K of the catalyst under the minimum and maximum load conditions after 24,000 hours of operation. L24000 and K H24000 .

[0025] Those skilled in the art will understand that the attenuation coefficient b is the ratio of the attenuated activity value to the original activity value, while the attenuation rate is the ratio of the difference in attenuated activity value to the original value. The smaller b is, the smaller the attenuated activity value and the greater the attenuation rate.

[0026] The present invention provides a catalyst selection and design method for wide-temperature denitrification engineering, which can select catalysts capable of achieving NO reduction. x A wide-temperature denitrification catalyst that meets ultra-low emission standards, has low NH3 escape, and low SO2 oxidation rate.

[0027] In one embodiment, in step (7), the operating temperature range is 200-400℃, preferably 250-380℃, such as 250℃, 260℃, 270℃, 280℃, 290℃, 300℃, 310℃, 320℃, 330℃, 340℃, 350℃, 360℃, 370℃, and 380℃.

[0028] In one embodiment, in step (7), the activity value K of the wide-temperature denitration catalyst is tested at x = 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4 and 1.5, y = 3.5, and the operating temperatures are 250℃, 260℃, 270℃, 280℃, 290℃, 300℃, 310℃, 320℃, 330℃, 340℃, 350℃, 360℃, 370℃ and 380℃, respectively.

[0029] In one implementation, in step (3), c2 meets the emission standards.

[0030] In one implementation, in step (8), b = 0.65-0.76, where different values ​​represent the attenuation coefficient of the catalyst in different coal flue gas, such as 0.66, 0.67, 0.68, 0.69, 0.70, 0.71, 0.72, 0.73, 0.74 and 0.75.

[0031] To achieve the second objective of this invention, a wide-temperature denitrification catalyst obtained according to the aforementioned catalyst selection and design method is provided.

[0032] To achieve the third objective of this invention, the aforementioned catalyst selection and design method and the application of the aforementioned wide-temperature denitrification catalyst in wide-temperature denitrification engineering are provided.

[0033] The beneficial effects of this invention are as follows:

[0034] The catalyst selection and design method of the present invention for wide-temperature denitrification engineering can select catalysts that can achieve NO reduction. x A wide-temperature denitrification catalyst that achieves ultra-low emission standards, low NH3 slip, and low SO2 oxidation rate; the method is simple and easy to operate, and the selected wide-temperature denitrification catalyst can be applied to wide-temperature denitrification projects to achieve NO x The goal is to achieve ultra-low emission standards, low NH3 escape, and low SO2 oxidation rate. Detailed Implementation

[0035] The technical solution and its effects of the present invention will be further described below with reference to specific embodiments / examples. The following embodiments / examples are only for illustrating the content of the present invention, and the invention is not limited to the following embodiments or examples. Simple modifications made to the present invention based on the concept of the present invention are all within the scope of protection claimed by the present invention.

[0036] Example 1 (S1)

[0037] The deep peak load range for a 300MW power plant unit is 10-100%, or 30-300MW.

[0038] (1) Based on the unit's denitrification system design document, ultra-low emission retrofit technology agreement, and low-NOx combustion retrofit technology agreement, obtain the flue gas flow rate Q, temperature T, and NOx at the lowest load (30MW) and highest load (300MW) within the power plant's deep peak load range. x The concentrations of SO2, SO3, O2, and H2O are shown in Table 1.

[0039] Table 1 Unit Flue Gas Parameters

[0040] parameter unit Low load condition 1 High-load operating condition 2 load MW 30 300 <![CDATA[Flue gas volume flow rate Q (wet basis, standard condition, actual O2)]]> <![CDATA[10 4 Nm 3 / h]]> 50 115 flue gas temperature T ℃ 260 380 <![CDATA[First floor entrance NO x Concentration (c1) (standard state, dry basis, 6% O2)]]> <![CDATA[mg / Nm 3 ]]> 487 333 <![CDATA[SO2 concentration (standard state, dry basis, 6% O2)]]> <![CDATA[mg / Nm 3 ]]> 500 500 <![CDATA[O2 content (wet basis)]]> ％ 5 3 <![CDATA[H2O content]]> ％ 8.57 8.57 <![CDATA[Final floor outlet NO x Concentration (c2) (standard state, dry basis, 6% O2)]]> <![CDATA[mg / Nm 3 ]]> 50 50 <![CDATA[NH3 concentration at the last - layer outlet (c3)]]> μL / L 3 3

[0041] Note: μL / L and ppm have exactly the same meaning; the ammonia concentration at the final outlet is the ammonia escape concentration.

[0042] In Table 1, the 6% O2 at SO2 refers to the concentration of SO2 after conversion to 6% O2; NO x The 6% O2 at that point refers to the amount of NO. x The concentration is calculated based on 6% O2; in the flue gas volumetric flow rate Q, N represents the standard condition, and wet basis refers to the water vapor content when calculating the flue gas flow rate;

[0043] (2) Based on the parameters of the original upper, middle and lower three layers of catalyst in the unit (as shown in Table 2, where the upper layer is the first layer and the lower layer is the last layer), including the volume V of each layer of catalyst. 上 V 中 and V 下 And the specific surface area S of each catalyst layer 上 S 中 and S 下 As shown in Table 2;

[0044] Table 2 Catalyst Parameters

[0045]

[0046] Then calculate the surface velocity of the catalyst, Av = Q / (V). 上 ×S 上 +V 中 ×S 中 +V 下 ×S 下 The results are shown in Table 3.

[0047] According to Table 3, Av under low load L =4.36m / h, Av under high loadH =10.02 m³ / h;

[0048] (3) Based on the NO inlet of the first-layer catalyst x Concentration c1 and NO at the outlet of the last catalyst layer x Given concentration c2, calculate the design efficiency η of the entire denitrification project. 设计 = (c1-c2) / c1, the results are shown in Table 3;

[0049] According to Table 3, η under low load 设计L =0.897, η under high load 设计H =0.850;

[0050] (4) Based on c1 and η in step (3) 设计 And the outlet NH3 concentration c3 of the final catalyst layer that meets emission standards, calculate the design ammonia-nitrogen molar ratio MR of the entire denitrification project. 设计 =η 设计 +c3 / c1, the results are shown in Table 3;

[0051] According to Table 3, MR under low load 设计L =0.910, MR under high load 设计H =0.868;

[0052] (5) Based on the formula K=0.5×Av×ln(MR / (MR-η) / (1-η)), calculate the required activity K of the catalyst under the minimum and maximum load conditions after 24000h of catalyst operation. L24000 and K H24000 The results are shown in Table 3.

[0053] According to Table 3, K L24000 =14.3m / h, K H24000 =28.8 m³ / h;

[0054] (6) Select a wide-temperature denitration catalyst according to the expression (x)V2O5-(y)MoO3 / TiO2; wherein, TiO2 is the catalyst support, MoO3 accounts for y% of the catalyst and V2O5 accounts for x% of the catalyst; x=0.6-1.5, y=3.5;

[0055] (7) The activity values ​​K of the wide-temperature denitration catalyst in step (6) were tested at x = 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4 and 1.5, y = 3.5, and operating temperatures of 250℃, 260℃, 270℃, 280℃, 290℃, 300℃, 310℃, 320℃, 330℃, 340℃, 350℃, 360℃, 370℃ and 380℃, respectively. The test results are shown in Table 4.

[0056] Table 4 shows the test results of the activity value K at different x and operating temperatures when y = 3.5.

[0057]

[0058]

[0059] (8) Based on the active K obtained in step (5) L24000 and K H24000 According to the attenuation coefficient K 24000 / K0=b,b=0.76(normal operating condition attenuation coefficient),to obtain the initial charge activity K of the wide-temperature denitrification catalyst in step (6) at the lowest and highest operating temperatures. L0 and K H0 The results are shown in Table 3.

[0060] According to Table 3, K L0 =18.8m / h, K H0 = 37.9 m³ / h;

[0061] Table 3 Required Activity of Wide-Temperature Denitration Catalysts (3-Layer Arrangement)

[0062] parameter unit Low load condition 1 High-load operating condition 2 load MW 30 300 temperature ℃ 260 380 Av m / h 4.36 10.02 <![CDATA[MR 设计 ]]> - 0.910 0.868 <![CDATA[η 设计 ]]> - 0.897 0.850 <![CDATA[K 24000 ]]> m / h 14.3 28.8 <![CDATA[K0]]> m / h 18.8 37.9

[0063] (9) Based on the activity value K obtained in step (7), select from Table 3 the values ​​that meet the requirements of the lowest and highest operating temperatures in step (8), respectively, where the activity value is higher than K. L0 and K H0 The wide-temperature denitration catalyst with the smallest x value was found to be x = 0.8, meaning the selected wide-temperature denitration catalyst is 0.8V2O5-3.5MoO3 / TiO2.

[0064] Comparative Example 1

[0065] Based on the flue gas parameters for low-load condition 1 and high-load condition 2 in Example 1, a 0.7V2O5-3.5MoO3 / TiO2 catalyst with a V2O5 percentage of 0.7% and a MoO3 percentage of 3.5% was selected. According to relevant formulas, after the catalyst has been running for 24,000 hours, the outlet NO... x The concentration is still controlled at 50 mg / Nm 3 The ammonia slip (i.e., the outlet ammonia concentration) was calculated to be 3.0 μL / L and 3.4 μL / L, respectively. Under high load conditions, the ammonia slip was greater than 3.0 μL / L, which exceeded the ammonia slip standard. Compared with Example 1, the catalyst activity was reduced, and the catalyst 0.7V2O5-3.5MoO3 / TiO2 used was unqualified.

[0066] Comparative Example 2

[0067] Based on the flue gas parameters for low-load condition 1 and high-load condition 2 in the embodiments, a 0.9V2O5-3.5MoO3 / TiO2 catalyst with a V2O5 content of 0.9% and a MoO3 content of 3.5% was selected. According to relevant formulas, based on the assumption that after 24,000 hours of catalyst operation, the ammonia slip is 3.0 μL / L, the denitrification efficiencies are 96.4% and 88.8%, respectively, and the outlet NO... x The concentrations were 17.6 mg / Nm³. 3 and 37.4 mg / Nm 3 Compared to Example 1, its catalyst activity is better. However, although the 0.9V₂O₅-3.5MoO₃ / TiO₂ catalyst has better activity, its economic cost is higher; at the same time, the higher the V₂O₅ content (x value), the stronger the catalyst's ability to oxidize SO₂, which increases the risk of catalyst failure. Taking all factors into consideration, it is not as good as the 0.8V₂O₅-3.5MoO₃ / TiO₂ catalyst selected in Example 1.

[0068] Example 2 (S2)

[0069] Compared with Example 1, there are only two differences:

[0070] (1) The unit flue gas parameters are shown in Table 5. The NO at the first floor inlet x Concentration (c1) increases;

[0071] Table 5 Unit Flue Gas Parameters

[0072]

[0073] (2) Catalyst attenuation coefficient K 24000 / K0=b,b=0.65(attenuation coefficient under harsh operating conditions)The required activity of the wide-temperature denitration catalyst is calculated as shown in Table 6;

[0074] Table 6. Required Activity for Wide-Temperature Denitration Catalysts (3-Layer Arrangement)

[0075] parameter unit Low load condition 1 High-load operating condition 2 load MW 30 300 temperature ℃ 260 380 Av m / h 4.36 10.02 <![CDATA[MR 设计 ]]> - 0.937 0.903 <![CDATA[η 设计 ]]> - 0.929 0.889 <![CDATA[K 24000 ]]> m / h 15.9 32.0 <![CDATA[K0]]> m / h 24.5 49.3 b - 0.65 0.65

[0076] Based on Tables 4 and 6, x = 1.5 was selected, meaning the selected wide-temperature denitration catalyst is 1.5V2O5-3.5MoO3 / TiO2.

[0077] As can be seen from Examples 1-2, the catalyst selection and design method of the present invention for wide-temperature denitrification engineering can select a suitable wide-temperature denitrification catalyst.

Claims

1. A method for selecting and designing catalysts for wide-temperature denitrification projects, characterized in that, Includes the following steps: (1) Obtain the flue gas flow rate Q, temperature T, and NO under the lowest and highest loads within the deep peak-shaving load range of the power plant. x The concentrations of SO2, SO3, O2, and H2O; (2) Based on the parameters of the original n-layer catalyst of the unit, n≥2, including the volume V of the n-layer catalyst from top to bottom. 首 ~V 末 And the geometric specific surface area S of the n catalyst layers from top to bottom 首 ~S 末 The surface area of ​​each catalyst layer is calculated based on V×S, and then the surface velocity of the catalyst is calculated based on Av=Q / (the sum of the surface areas of n catalyst layers); (3) Based on the NO inlet of the first-layer catalyst x Concentration c1 and NO at the outlet of the last catalyst layer x Given concentration c2, calculate the design efficiency η of the entire denitrification project. 设计 = (c1-c2) / c1; (4) Based on c1 and η in step (3) 设计 And the outlet NH3 concentration c3 of the final catalyst layer that meets emission standards, calculate the design ammonia-nitrogen molar ratio MR of the entire denitrification project. 设计 =η 设计 +c3 / c1; (5) Based on the formula K=0.5×Av×ln(MR / (MR-η) / (1-η)), calculate the required activity K of the catalyst under the minimum and maximum load conditions after 24000h of catalyst operation. L24000 and K H24000 ; (6) Select a wide-temperature denitrification catalyst according to the expression (x)V2O5-(y)MoO3 / TiO2; wherein, TiO2 is the catalyst support, MoO3 accounts for y% of the catalyst and V2O5 accounts for x% of the catalyst; x=0.5-3, y=0.1-8; (7) The activity value K of the wide-temperature denitrification catalyst (x)V2O5-(y)MoO3 / TiO2 in step (6) was tested, and its activity value K was tested at different x values, different y values ​​and different operating temperatures. (8) Based on the active K obtained in step (5) H24000 and K L24000 According to the attenuation coefficient K 24000 / K0=b,b=0.65-0.85,to obtain the initial activity K of the wide-temperature denitrification catalyst in step (6) at the lowest and highest operating temperatures. L0 and K H0 ; (9) Based on the activity value K obtained in step (7), select a temperature range where the activity value is higher than K at the lowest and highest operating temperatures as specified in step (8). L0 and K H0 The wide-temperature denitration catalyst with the smallest x-value.

2. The catalyst selection and design method according to claim 1, characterized in that, y＝3-6。 3. The catalyst selection and design method according to claim 1 or 2, characterized in that, x＝0.6-2。 4. The catalyst selection and design method according to claim 3, characterized in that, x＝0.6-1.5。 5. The method for selecting and designing a catalyst according to any one of claims 1-4, characterized in that, In step (7), the operating temperature range is 200-400℃, preferably 250-380℃.

6. The method for selecting and designing a catalyst according to any one of claims 1-5, characterized in that, In step (7), the activity value K of the wide-temperature denitration catalyst was tested at x = 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4 and 1.5, y = 3.5, and the operating temperatures were 250℃, 260℃, 270℃, 280℃, 290℃, 300℃, 310℃, 320℃, 330℃, 340℃, 350℃, 360℃, 370℃ and 380℃, respectively.

7. The method for selecting and designing a catalyst according to any one of claims 1-6, characterized in that, In step (3), c2 meets the emission standards.

8. The method for selecting and designing a catalyst according to any one of claims 1-7, characterized in that, In step (8), b = 0.65 - 0.

76.

9. A wide-temperature denitrification catalyst obtained by the catalyst selection and design method according to any one of claims 1-8.

10. The catalyst selection and design method according to any one of claims 1-8 and the application of the wide-temperature denitrification catalyst according to claim 9 in wide-temperature denitrification engineering.

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