An SCR denitrification ammonia water evaporator

Abstract

This invention relates to the field of flue gas denitrification technology, and in particular to an SCR denitrification ammonia evaporator, comprising an ammonia evaporator body and a first set of gas distributors and a second set of gas distributors installed at both ends of the ammonia evaporator body. Both the first and second sets of gas distributors include two spiral gas distributors rotating in opposite directions. The first set of gas distributors increases the turbulence of the flue gas entering the ammonia evaporator body, thereby improving the mixing effect of the flue gas and ammonia vapor. The second set of gas distributors reduces the velocity of the mixed gas, further making the gas mixture more uniform and changing the flow state of the mixed gas, ensuring that the Reynolds number of the mixed gas is less than 2000. This ensures that the mixed gas flows into the SCR reactor in a uniform and stable laminar flow state. The laminar flow of the mixed gas mixes more uniformly with the catalyst in the SCR reactor, further improving the reaction efficiency.

Description

Technical Field

[0001] This invention relates to the field of flue gas denitrification technology, and in particular to an SCR denitrification ammonia water evaporator. Background Technology

[0002] SCR (Selective Catalytic Reduction) is a technology that uses a catalyst to react a reducing agent (ammonia) with nitrogen oxides in flue gas to produce harmless nitrogen and water, thereby removing NOx from the flue gas.

[0003] SCR (Selective Catalytic Reduction) denitrification technology is currently the main method for denitrification of flue gas in steel plants. The uniformity of the mixture between the flue gas and the newly added gas is a crucial prerequisite for SCR denitrification. The ammonia evaporator uses saturated steam at a certain pressure to evaporate 20% ammonia water into a mixture of ammonia gas and water vapor. This mixture is then diluted to below 5% (v%) before entering the SCR reactor through an ammonia injection grid for the denitrification reaction. During this process, if the flue gas and ammonia vapor cannot form a stable and uniform fluid, the efficiency of subsequent SCR NOx removal is significantly reduced, affecting the catalyst's service life.

[0004] As a crucial component for promoting gas mixing, gas mixing devices can influence the flow field within the flue gas duct, ensuring a uniform velocity distribution of the flue gas. Currently, commonly used gas mixing devices include guide vanes and gas distributors. Guide vanes offer simple structure and uniform gas distribution, but suffer from high resistance and energy consumption. Traditional tubular distributors provide uniform gas distribution, but their orifices are prone to clogging, affecting the stable and uniform flow of flue gas and thus impacting denitrification efficiency.

[0005] In view of this, the present invention proposes a novel SCR denitrification ammonia water evaporator to make the flue gas and ammonia vapor mix more evenly, and to ensure denitrification efficiency while consuming less energy. Summary of the Invention

[0006] The first objective of this invention is to provide an SCR denitrification ammonia water evaporator, which increases the turbulent flow of flue gas entering the ammonia water evaporator, significantly improving the mixing effect of flue gas and ammonia vapor. At the same time, it allows the mixture of flue gas and ammonia vapor to enter the SCR reactor in a laminar flow state, increasing the mixing effect of the mixture with the catalyst and improving the denitrification efficiency.

[0007] The present invention provides an SCR denitrification ammonia water evaporator, comprising an ammonia water evaporator body and a first group of gas distributors and a second group of gas distributors installed at both ends of the ammonia water evaporator body, wherein the first group of gas distributors and the second group of gas distributors each include two spiral gas distributors rotating in opposite directions.

[0008] As a preferred embodiment of this technical solution, the first group of gas distributors includes a forward spiral gas distributor and a reverse spiral gas distributor, and the forward spiral gas distributor and the reverse spiral gas distributor are sequentially arranged at the inlet end of the ammonia water evaporator body along the direction of flue gas flow.

[0009] As a preferred embodiment of this technical solution, the second group of gas distributors includes a forward spiral gas distributor and a reverse spiral gas distributor, and the forward spiral gas distributor and the reverse spiral gas distributor are sequentially arranged at the outlet end of the ammonia water evaporator body along the direction of flue gas flow.

[0010] In a preferred embodiment of this technical solution, both the forward spiral gas distributor and the reverse spiral gas distributor include a shaft and multiple blades, wherein the blades are arranged in a forward or reverse spiral pattern on the outer periphery of the shaft.

[0011] In a preferred embodiment of this technical solution, in the forward spiral gas distributor, the included angle between the blade and the shaft wheel is α, and 65°≤α≤85°.

[0012] In a preferred embodiment of this technical solution, in the reverse spiral gas distributor, the included angle between the blade and the shaft wheel is β, and 45°≤β≤65°.

[0013] As a preferred embodiment of this technical solution, the inlet end of the ammonia evaporator body is provided with a first reducing pipe, the forward spiral gas distributor in the first group of gas distributors is fixed at the small end of the first reducing pipe, and the reverse spiral gas distributor in the first group of gas distributors is fixed at one end of the ammonia evaporator body near the first reducing pipe.

[0014] As a preferred embodiment of this technical solution, the outlet end of the ammonia evaporator body is provided with a second reducing pipe, the forward spiral gas distributor in the second group of gas distributors is fixed at one end of the ammonia evaporator body near the second reducing pipe, and the reverse spiral gas distributor in the second group of gas distributors is fixed at the small end of the second reducing pipe.

[0015] In a preferred embodiment of this technical solution, in the first group of gas distributors, the forward spiral gas distributor is in clearance fit with the small end of the first variable diameter pipe, and the reverse spiral gas distributor is in clearance fit with the ammonia evaporator body; in the second group of gas distributors, the forward spiral gas distributor is in clearance fit with the ammonia evaporator body, and the reverse spiral gas distributor is in clearance fit with the small end of the second variable diameter pipe.

[0016] As a preferred embodiment of this technical solution, the diameter ratio of the small end to the large end of the first reducing pipe and the second reducing pipe is (1-3):4.

[0017] The SCR denitrification ammonia water evaporator of the present invention has at least the following technical advantages compared with the prior art:

[0018] 1. The SCR denitrification ammonia evaporator of the present invention has a first set of gas distributors and a second set of gas distributors installed at both ends of the ammonia evaporator body, wherein both the first set of gas distributors and the second set of gas distributors include two spiral gas distributors rotating in opposite directions. The first set of gas distributors can increase the turbulence of the flue gas entering the ammonia evaporator body, thereby improving the mixing effect of flue gas and ammonia vapor; the second set of gas distributors can reduce the movement speed of the mixed gas, further making the gas mixing more uniform, and changing the flow state of the mixed gas, so that the Reynolds number of the mixed gas is less than 2000, ensuring that the mixed gas flows into the SCR reactor in a uniform and stable laminar flow state. The laminar flow state of the mixed gas mixes more uniformly with the catalyst in the SCR reactor, which can further improve the reaction efficiency.

[0019] 2. The present invention, by installing a first set of gas distributors and a second set of gas distributors at both ends of the ammonia evaporator body, significantly reduces pressure drop and energy consumption compared to traditional gas distributors, and has significant advantages in industrial applications. Attached Figure Description

[0020] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the SCR denitrification ammonia water evaporator of the present invention;

[0022] Figure 2 This is the positive spiral gas distributor in the first group of gas distributors of the present invention;

[0023] Figure 3 This is the reverse spiral gas distributor in the first group of gas distributors of the present invention;

[0024] Figure 4 This is the positive spiral gas distributor in the second group of gas distributors of the present invention;

[0025] Figure 5 This is the reverse spiral gas distributor in the second group of gas distributors of the present invention.

[0026] Figure Labels

[0027] 1: Ammonia evaporator body; 2: Forward spiral gas distributor; 3: Reverse spiral gas distributor; 4: Shaft wheel; 5: Blade; 6: First diameter reducer; 7: Second diameter reducer; 8: Ammonia injection device. Detailed Implementation

[0028] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0029] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations according to this application. As used herein, the singular form includes the plural form unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this description, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0030] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. 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 are within the scope of protection of the present invention.

[0031] like Figure 1-5 As shown, this embodiment provides an SCR denitrification ammonia water evaporator, including an ammonia water evaporator body 1 and a first set of gas distributors and a second set of gas distributors installed at both ends of the ammonia water evaporator body 1. Both the first set of gas distributors and the second set of gas distributors include two spiral gas distributors rotating in opposite directions. The first set of gas distributors increases the turbulence of the flue gas entering the ammonia water evaporator body 1, thereby improving the mixing effect of the flue gas and ammonia vapor. The second set of gas distributors reduces the velocity of the mixed gas, further making the gas mixture more uniform and changing the flow state of the mixed gas, ensuring that the Reynolds number of the mixed gas is less than 2000. This ensures that the mixed gas flows into the SCR reactor in a uniform and stable laminar flow state. The laminar flow of the mixed gas mixes more uniformly with the catalyst in the SCR reactor, further improving the reaction efficiency.

[0032] In a specific embodiment of the present invention, the first set of gas distributors includes a forward spiral gas distributor 2 and a reverse spiral gas distributor 3, and the forward spiral gas distributor 2 and the reverse spiral gas distributor 3 are sequentially arranged at the inlet end of the ammonia evaporator body 1 along the direction of flue gas flow. That is, the forward spiral gas distributor 2 and the reverse spiral gas distributor 3 are sequentially installed at the inlet end of the ammonia evaporator. After the flue gas enters the ammonia evaporator, under the action of the forward rotating forward spiral gas distributor 2 and the reverse rotating reverse spiral gas distributor 3, the flue gas will undergo turbulent flow inside the ammonia evaporator body 1, thereby increasing the degree of gas disorder and ensuring uniform mixing of flue gas and ammonia vapor.

[0033] The second group of gas distributors includes a forward spiral gas distributor 2 and a reverse spiral gas distributor 3, which are sequentially arranged at the outlet end of the ammonia evaporator body 1 along the direction of flue gas flow. In the ammonia evaporator, as the velocity of the mixed gas continuously decreases, the uniformly mixed gas passes sequentially through the forward-rotating forward spiral gas distributor 2 and the reverse-rotating reverse spiral gas distributor 3, which can transform the turbulent mixed gas into a laminar flow. The uniformly laminar and stable mixed gas enters the SCR reactor, which significantly increases the interaction between the mixed gas and the SCR denitrification catalyst, thereby improving the denitrification efficiency.

[0034] In this embodiment, one or more ammonia injection devices 8 are provided on the side wall of the ammonia water evaporator body 1, and the ammonia injection device 8 is located near the flue gas inlet. The ammonia water evaporator evaporates the ammonia water injected by the ammonia injection device 8 into ammonia vapor through a certain pressure and saturated steam. After the flue gas enters the ammonia water evaporator, it is fully mixed with the ammonia vapor to form a stable and uniform fluid.

[0035] Based on the above technical solution, furthermore, both the forward spiral gas distributor 2 and the reverse spiral gas distributor 3 include a shaft wheel 4 and multiple blades 5, wherein the blades 5 are arranged in a forward or reverse spiral pattern on the outer periphery of the shaft wheel 4. Specifically, according to the dilution fan flow rate and NO... x The ammonia spray flow rate is determined by the angle between the blade 5 and the shaft wheel 4 in the forward spiral gas distributor 2 to ensure turbulent flue gas flow. Studies show that in the forward spiral gas distributor 2 of the first set of gas distributors, the angle between the blade 5 and the shaft wheel 4 is α. When 65°≤α≤85°, and preferably 75°, the turbulent flow of the flue gas can be ensured to the greatest extent.

[0036] Similarly, based on the dilution fan flow rate and NO... xThe ammonia spray flow rate is designed, and the angle between the blade 5 and the shaft wheel 4 in the reverse spiral gas distributor 3 is designed to ensure uniform mixing of flue gas and ammonia vapor. In the reverse spiral gas distributor 3 of the first set of gas distributors, the included angle between the blade 5 and the shaft wheel 4 is β, and when 45°≤β≤65°, and preferably 54°, the mixing effect of flue gas and ammonia vapor can be ensured to the greatest extent.

[0037] Based on the dilution fan flow rate and NO x To determine the concentration, a second set of gas distributors is designed, consisting of a forward spiral gas distributor 2 and a reverse spiral gas distributor 3. In the forward spiral gas distributor 2 of the second set of gas distributors, the angle between the blade 5 and the shaft wheel 4 is α, and 65°≤α≤85°. In the reverse spiral gas distributor 3 of the first set of gas distributors, the angle between the blade 5 and the shaft wheel 4 is β, and 45°≤β≤65°.

[0038] Based on the above technical solution, and further preferably, in order to reduce the flue gas pipe resistance, a first variable diameter pipe 6 is provided at the inlet end of the ammonia evaporator body 1. Furthermore, the forward spiral gas distributor 2 in the first group of gas distributors is fixed at the small end of the first variable diameter pipe 6, and the reverse spiral gas distributor 3 in the first group of gas distributors is fixed at one end of the ammonia evaporator body 1 near the first variable diameter pipe 6. After the flue gas enters the first variable diameter pipe 6, it passes through the forward spiral gas distributor 2 and the reverse spiral gas distributor 3 in succession, making the flue gas flow in a turbulent state and increasing the flue gas disorder. Meanwhile, a second reducing pipe 7 is provided at the outlet end of the ammonia evaporator body 1. Furthermore, the forward spiral gas distributor 2 of the second group of gas distributors is fixed at one end of the ammonia evaporator body 1 near the second reducing pipe 7, and the reverse spiral gas distributor 3 of the second group of gas distributors is fixed at the small end of the second reducing pipe 7. The turbulent flue gas is fully mixed with the ammonia vapor inside the ammonia evaporator body 1. After being mixed evenly, the flue gas and ammonia vapor pass through the forward spiral gas distributor 2 and the reverse gas distributor at the second reducing pipe 7 in turn. The movement speed of the mixed gas is reduced, making the gas mixture more uniform and reducing the Reynolds number of the mixed gas to less than 2000. This transforms the turbulent mixed gas into a laminar mixed gas. The laminar mixed gas flows into the SCR reactor in a uniform and stable state, thereby ensuring that the mixed gas and the SCR catalyst are mixed more uniformly to improve the denitrification efficiency.

[0039] To further ensure gas mixing at the pipe wall, improve the turbulence effect of the first set of gas distributors on the flue gas, and increase the flue gas turbulence, in the first set of gas distributors, the forward spiral gas distributor 2 is in clearance fit with the small end of the first reducing pipe 6, and the reverse spiral gas distributor 3 is in clearance fit with the ammonia evaporator body 1. Similarly, to ensure that all gases in the ammonia evaporator body 1 can change from turbulent flow to laminar flow, in the second set of gas distributors, the forward spiral gas distributor 2 is in clearance fit with the ammonia evaporator body 1, and the reverse spiral gas distributor 3 is in clearance fit with the small end of the second reducing pipe 7.

[0040] In one specific embodiment, the inner diameter of the small-diameter ends of the first reducing pipe 6 and the second reducing pipe 7 is 300 mm, and the inner diameter of the ammonia evaporator body 1 is 600 mm. In the first group of gas distributors, the blade 5 of the forward spiral gas distributor 2 has a length of 150 mm and an outer diameter of 294 mm, and is clearance-fitted with the first reducing pipe 6. The outer diameter of the reverse spiral gas distributor 3 is 594 mm, and is clearance-fitted with the ammonia evaporator body 1. Similarly, in the second group of gas distributors, the blade 5 of the forward spiral gas distributor 2 has a length of 150 mm and an outer diameter of 594 mm, and is clearance-fitted with the ammonia evaporator body 1. The outer diameter of the reverse spiral gas distributor 3 is 294 mm, and is clearance-fitted with the second reducing pipe 7.

[0041] Based on the above technical solution, in order to further reduce the pressure drop and energy consumption of the first group of gas distributors and the second group of gas distributors, preferably, the diameter ratio of the small end to the large end of the first variable diameter pipe 6 and the second variable diameter pipe 7 is (1-3):4.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An SCR denitrification ammonia water evaporator, characterized in that, It includes an ammonia evaporator body (1) and a first set of gas distributors and a second set of gas distributors installed at both ends of the ammonia evaporator body (1). Both the first group of gas distributors and the second group of gas distributors include two spiral gas distributors rotating in opposite directions; The first set of gas distributors is used to increase the turbulence of the flue gas entering the ammonia evaporator body, thereby improving the mixing effect of flue gas and ammonia vapor; The second set of gas distributors is used to reduce the speed of the mixed gas, further making the gas mixture more uniform, and changing the flow state of the mixed gas to make the Reynolds number of the mixed gas less than 2000, ensuring that the mixed gas flows into the SCR reactor in a uniform and stable laminar flow state. The first group of gas distributors includes a forward spiral gas distributor (2) and a reverse spiral gas distributor (3), and the forward spiral gas distributor (2) and the reverse spiral gas distributor (3) are arranged sequentially at the inlet end of the ammonia water evaporator body (1) along the direction of flue gas flow. The second group of gas distributors includes a forward spiral gas distributor (2) and a reverse spiral gas distributor (3), and the forward spiral gas distributor (2) and the reverse spiral gas distributor (3) are arranged sequentially at the outlet end of the ammonia water evaporator body (1) along the direction of flue gas flow.

2. The SCR denitrification ammonia water evaporator according to claim 1, characterized in that, Both the forward spiral gas distributor (2) and the reverse spiral gas distributor (3) include a shaft wheel (4) and multiple blades (5), with the blades (5) arranged in a forward or reverse spiral pattern on the outer periphery of the shaft wheel (4).

3. The SCR denitrification ammonia water evaporator according to claim 2, characterized in that, In the forward spiral gas distributor (2), the included angle between the blade (5) and the shaft wheel (4) is α, and 65°. o ≤α≤85 o .

4. The SCR denitrification ammonia water evaporator according to claim 2, characterized in that, In the reverse spiral gas distributor (3), the included angle between the blade (5) and the shaft wheel (4) is β, and 45°. o ≤β≤65 o .

5. The SCR denitrification ammonia water evaporator according to claim 1, characterized in that, The inlet end of the ammonia evaporator body (1) is provided with a first reducing pipe (6), the forward spiral gas distributor (2) in the first group of gas distributors is fixed at the small end of the first reducing pipe (6), and the reverse spiral gas distributor (3) in the first group of gas distributors is fixed at one end of the ammonia evaporator body (1) near the first reducing pipe (6).

6. The SCR denitrification ammonia water evaporator according to claim 5, characterized in that, The outlet end of the ammonia evaporator body (1) is provided with a second reducing pipe (7). The forward spiral gas distributor (2) in the second group of gas distributors is fixed at one end of the ammonia evaporator body (1) near the second reducing pipe (7). The reverse spiral gas distributor (3) in the second group of gas distributors is fixed at the small end of the second reducing pipe (7).

7. The SCR denitrification ammonia water evaporator according to claim 6, characterized in that, In the first group of gas distributors, the forward spiral gas distributor (2) is in clearance fit with the small end of the first variable diameter pipe (6), and the reverse spiral gas distributor (3) is in clearance fit with the ammonia evaporator body (1). In the second group of gas distributors, the forward spiral gas distributor (2) is in clearance fit with the ammonia evaporator body (1), and the reverse spiral gas distributor (3) is in clearance fit with the small end of the second reducing pipe (7).

8. The SCR denitrification ammonia water evaporator according to claim 7, characterized in that, The diameter ratio of the small end to the large end of the first reducing pipe (6) and the second reducing pipe (7) is (1-3):4.

Images