CN119548974B - Ammonia injection grid with injection and mixing functions - Google Patents

Abstract

The present invention relates to an ammonia injection grid with injection and mixing functions, which is installed in a flue. The ammonia injection grid is composed of a plurality of partitions arranged at equal intervals along the cross section of the flue, and a plurality of injection units arranged at equal intervals along the cross section of the flue are provided between adjacent partitions. A venturi channel is formed between adjacent injection units, and the venturi channel has a convergent section, a throat, and a divergent section. Each injection unit includes an upper cone section and a lower cone section that are relatively arranged, and the upper cone section and the lower cone section are connected by a straight section located at the throat of the venturi channel, and an ammonia injection port is provided on the straight section. The ammonia injection grid with injection and mixing functions provided in this embodiment realizes the integration of ammonia injection and mixing by constructing a venturi channel between adjacent injection units and providing a straight section and an ammonia injection port at the throat, which greatly shortens the mixing distance, saves equipment space, and reduces system costs.

Description

Ammonia injection grille with injection and mixing functions

Technical Field

The invention relates to the technical field of flue gas denitration, in particular to an ammonia injection grid with injection and mixing functions.

Background

With the increasing environmental awareness of the world, emissions control of nitrogen oxides (NOx) is becoming increasingly stringent. The flue gas generated by industrial enterprises such as coal-fired power plants, cement plants, steel plants and the like contains a large amount of nitrogen oxides, and is one of the main causes of air pollution. Selective Catalytic Reduction (SCR) and selective non-catalytic reduction (SNCR) are the most widely used flue gas denitration techniques at present. These techniques typically require spraying a reducing agent (e.g., ammonia) into the flue and reacting with nitrogen oxides in the flue gas to reduce them to harmless nitrogen and water.

In the flue gas denitration system, an ammonia spraying grid is one of key equipment, and the main function of the ammonia spraying grid is to uniformly spray reducing agents such as ammonia into a flue and fully mix the reducing agents with flue gas, so that denitration efficiency is improved. Conventional ammonia injection grids typically inject ammonia gas by providing perforated pipes or nozzles within the flue. However, this approach has some problems:

The mixing efficiency is low, the ammonia gas sprayed by the traditional ammonia spraying grid has limited diffusion range, the mixing with the flue gas mainly depends on the turbulent flow effect of the flue gas, the mixing efficiency is low, and a good mixing effect can be achieved only by a long mixing distance. This results in insufficient denitration reaction and limited denitration efficiency.

The uneven distribution of ammonia gas can cause uneven distribution of ammonia gas on the section of the flue due to the factors of uneven distribution of flue gas flow velocity in the flue, different injection pressure of each nozzle of the ammonia injection grid and the like, and the phenomenon of overhigh or overlow local ammonia gas concentration occurs. This not only reduces the denitration efficiency, but also may cause ammonia escape, causing secondary pollution.

The equipment is large in size, in order to improve the mixing efficiency, the traditional ammonia spraying grille generally needs to increase the length of a flue or is provided with an additional static mixer, which can lead to huge size, increased occupied area and increased construction cost of the denitration system.

In order to solve the above problems, some improvements have been proposed in the prior art, such as multi-stage injection, optimizing nozzle arrangement, and the like. However, these improvements still have certain limitations that make it difficult to achieve efficient mixing, uniform distribution and miniaturization at the same time.

Disclosure of Invention

In order to solve the problems, the invention provides the ammonia injection grid with the spraying and mixing functions, which realizes efficient mixing, uniform distribution, space saving and cost reduction.

In order to achieve the aim, the ammonia spraying grid with spraying and mixing functions is arranged in a flue, the ammonia spraying grid is composed of a plurality of partition boards which are transversely and equidistantly arranged along the section of the flue, a plurality of spraying units which are longitudinally and equidistantly arranged along the section of the flue are arranged between every two adjacent partition boards, a venturi channel is formed between every two adjacent spraying units, each venturi channel is provided with a converging section, a throat and a diverging section, each spraying unit comprises an upper cone section and a lower cone section which are oppositely arranged, the upper cone section and the lower cone section are connected through a straight section positioned at the throat of the venturi channel, an ammonia spraying opening is formed in the straight section, the cross section of the converging section is gradually reduced along the flow direction of flue gas, the cross section of the diverging section is gradually increased along the flow direction of the flue gas, the included angle alpha between the side wall of the converging section and the central axis of the throat is 17-21 DEG, and the included angle beta between the side wall of the diverging section and the central axis of the throat is 22-26 deg.

Preferably, the ammonia spraying port is an oblong hole extending longitudinally along the section of the flue, and the aperture of the oblong hole tends to increase from the air inlet end to the spraying end of the oblong hole towards the position where the throat part is located.

Preferably, the cross sections of the upper cone section and the lower cone section, which are parallel to the flow direction of the flue gas in the flue, are isosceles triangles.

Preferably, a mixing space is formed between any two adjacent baffles, and the jet units in the mixing spaces longitudinally adjacent along the section of the flue are arranged in a staggered mode, wherein the staggered distance is equal to the width of the throat.

Preferably, an ammonia main pipe connected with an external ammonia source is arranged in part of the partition plates, each straight section is internally provided with an air inlet branch pipe connected with an ammonia spraying port, each air inlet branch pipe is connected with the ammonia main pipe in the corresponding partition plate, and every other partition plate without the ammonia main pipe in the partition plates is provided with a partition plate with the ammonia main pipe.

Preferably, tenons are arranged on the connection surfaces of the upper cone section, the lower cone section and the straight section, mortises matched with the tenons are arranged on the straight section, screw holes penetrating through the lower cone section are formed in the conical surface of the upper cone section, and the upper cone section, the straight section and the lower cone section are fixedly connected with bolts into a whole through screw holes in a locking mode.

Preferably, a positioning counter bore matched with the upper cone section, the straight section and the lower cone section of the injection unit is formed in the plate surface of the partition plate, and the straight section is connected with the partition plate through bolts.

Preferably, the partition plate, the upper cone section, the straight section and the lower cone section are all made of high-temperature-resistant and corrosion-resistant alloy materials.

Preferably, the ammonia injection grid further comprises a fixed frame, and the separation plates are fixedly connected through the fixed frame.

The ammonia spraying grille with spraying and mixing functions, which is designed by the invention, realizes the integration of ammonia spraying and mixing by constructing a venturi channel between adjacent spraying units and arranging a straight section and an ammonia spraying port at the throat, greatly shortens the mixing distance, saves the equipment space and reduces the system cost, meanwhile, the special structure of the venturi channel obviously improves the mixing efficiency, reduces or even eliminates the dependence on a static mixer, further simplifies the system structure and reduces the operation cost. In addition, the design of the uniform distribution of the plurality of injection units and the ammonia injection ports at the throat parts of the venturi channels realizes the uniform distribution of ammonia gas, and overcomes the problem of uneven ammonia gas distribution in the prior art, thereby improving the denitration efficiency, reducing the ammonia gas waste and further optimizing the injection effect. Finally, it is worth mentioning that the method is not only suitable for flue gas denitration of coal-fired power plants, but also suitable for flue gas denitration scenes in other industrial fields, and has wide application prospects.

Drawings

Fig. 1 is a schematic view of an ammonia injection grid structure according to an embodiment of the present application.

Fig. 2 is a schematic view of a single spray unit mounting structure provided by an embodiment of the present application.

Fig. 3 is an exploded perspective view of fig. 2.

Fig. 4 is a top view of fig. 2.

FIG. 5 is a cross-sectional view taken at A-A in FIG. 4.

Fig. 6 is a cross-sectional view at B-B in fig. 4.

FIG. 7 is a schematic view of a portion of an ammonia injection grid according to an embodiment of the present application installed in a flue.

Wherein, the baffle plate 10, the ammonia main pipe 11, the positioning counter bore 12, the injection unit 20, the upper cone section 21, the lower cone section 22, the straight section 23, the mortise 24, the screw hole 25, the Venturi passage 30, the convergence section 31, the throat 32, the divergence section 33, the ammonia injection port 40 and the air inlet branch pipe 41.

Detailed Description

The preferred embodiments of the present invention will be described below with reference to the accompanying drawings, it being understood that the preferred embodiments described herein are for illustration and explanation of the present invention only, and are not intended to limit the present invention.

The ammonia spraying grille with the spraying and mixing functions is mainly used for a flue gas denitration system of industrial enterprises such as coal-fired power plants and the like, so that the mixing efficiency of ammonia gas and flue gas is improved, and the denitration effect is improved.

As shown in fig. 1 to 7, the ammonia injection grille with injection and mixing functions described in this embodiment is installed in a flue, the ammonia injection grille is composed of a plurality of partition boards 10 which are transversely and equidistantly arranged along the section of the flue, a plurality of injection units 20 which are longitudinally and equidistantly arranged along the section of the flue are arranged between adjacent partition boards 10, a venturi channel 30 is formed between adjacent injection units 20, the venturi channel 30 is provided with a converging section 31, a throat section 32 and a diverging section 33, each injection unit 20 comprises an upper cone section 21 and a lower cone section 22 which are oppositely arranged, the upper cone section 21 and the lower cone section 22 are connected through a straight section 23 positioned at the throat section 32 of the venturi channel 30, and ammonia injection ports 40 are arranged on the straight section 23, wherein the cross-sectional area of the converging section 31 is gradually reduced along the flow direction of flue gas, and the cross-sectional area of the diverging section 33 is gradually increased along the flow direction of flue gas.

In particular operation, as shown in fig. 7, the ammonia injection grille is installed in the flue, the flue gas flows in from the converging section 31 of the venturi passage 30, the flow rate of the flue gas is accelerated due to the gradual decrease of the cross-sectional area of the converging section 31, and reaches the maximum value at the throat 32, and at the same time, ammonia gas is injected into the throat 32 of the venturi passage 30 through the ammonia injection port 40 provided on the straight section 23, so as to be rapidly mixed with the flue gas flowing at high speed, and finally, the mixture of ammonia gas and flue gas enters the subsequent flue through the diverging section 33, and in the diverging section 33, the flow rate of the flue gas is slowed down due to the gradual increase of the cross-sectional area, and is further mixed. In this structure, venturi channel 30 not only can guarantee that the flue gas passes through throat 32 with faster velocity of flow through the reasonable design of convergence section 31, throat 32 and divergent section 33, can also form the negative pressure district in throat 32 department, is favorable to the intensive mixing of ammonia and flue gas. In addition, the uniform distribution of the spraying units 20 ensures the distribution uniformity of the sprayed ammonia on the section of the whole flue, and effectively improves the mixing efficiency of the ammonia and the flue gas.

In this embodiment, the included angle α between the side wall of the convergent section 31 and the central axis of the throat 32 is 17 ° -21 °, and the included angle β between the side wall of the divergent section 33 and the central axis of the throat 32 is 22 ° -26 °, so that the ammonia gas and the flue gas are sufficiently mixed in the throat, and no excessive flow resistance is generated. In a specific embodiment, the included angle α is 19 ° and the included angle β is 24 °, so that a good mixing effect can be ensured without causing excessive flow resistance under the combination of the angles.

In this embodiment, the partition board 10, the upper cone section 21, the flat section 23 and the lower cone section 22 are made of high temperature resistant and corrosion resistant alloy materials. In some embodiments, stainless steel, nickel-based alloys, superalloys, and the like may be employed.

In some embodiments, as shown in fig. 2 and 6, the ammonia injection port 40 is an oblong hole extending longitudinally along the cross section of the flue, and the aperture of the oblong hole tends to increase from the air inlet end to the injection end thereof toward the position of the throat 32. Specifically, on the straight section 23, the shape of the ammonia spraying port 40 approximates to an elongated ellipse, the aperture of the ammonia spraying port near the connection part (i.e. the air inlet end) of the ammonia pipe is smaller, the aperture gradually increases along with the gradual approach to the throat part 32 along the spraying direction, the design increases the coverage area of the ammonia on the section of the flue, namely the traditional dot-shaped or columnar spraying mode, the ammonia is often intensively sprayed to a small area, and the spraying mode of the oblong hole enables the ammonia to be sprayed in a lamellar mode, so that the contact area of the ammonia and the flue gas is greatly increased, the accelerating mixing effect of the venturi channel 30 is more effectively utilized, the uneven phenomenon of the ammonia in the mixing process is further greatly avoided, and the possibility of ammonia escape is greatly reduced.

In some embodiments, the cross section of the upper cone section 21 and the lower cone section 22 parallel to the flow direction of the flue gas in the flue is isosceles triangle. By means of the structural design, two adjacent partition boards 10 can be tightly connected with two opposite sides of the upper cone section 21 and the lower cone section 22 respectively, so that the converging section 31 and the diverging section 33 are formed by surrounding more effectively, structural integrity and air tightness of the Venturi passage 30 are ensured, meanwhile, the isosceles triangle section structure is relatively simple, processing and manufacturing are easy, production cost can be effectively reduced, long-term stable and reliable operation of the injection unit 20 under severe working environments such as high temperature and high pressure is ensured, and maintenance requirements and downtime caused by component damage are reduced.

In some embodiments, as shown in fig. 7, a mixing space is formed between any two adjacent baffles 10, and the injection units 20 in the mixing spaces longitudinally adjacent along the flue cross section are arranged in a staggered manner, and the staggered distance is equal to the width of the throat portion 32.

In specific implementation, as shown in fig. 2, a positioning counter bore 12 matched with the upper cone section 21, the flat section 23 and the lower cone section 22 of the injection unit 20 is provided on the surface of the partition board 10, and the flat section 23 is connected with the partition board 10 through bolts.

Like this, the straight section 23 that is located same baffle 10 both sides is designed to fix in the different positions of baffle 10 longitudinal direction to effectively avoided the too concentrated structural weak point that leads to of fixed point, ensured the overall stability and the reliability of ammonia injection grid, simultaneously, dislocation arrangement makes the ammonia more even in the distribution on the flue cross-section, has avoided the phenomenon that ammonia concentrated or lacks in certain region, has further improved the miscibility.

In some embodiments, as shown in fig. 5, 6 and 7, a part of the partition boards 10 are provided with an ammonia main pipe 11 connected with an external ammonia source, each of the straight sections 23 is provided with an air inlet branch pipe 41 connected with one ammonia spraying port 40, and each air inlet branch pipe 41 is connected with the ammonia main pipe 11 in the corresponding partition board 10, wherein every other partition board 10 without the ammonia main pipe 11 in the partition boards 10 is provided with a partition board 10 with the ammonia main pipe 11.

In particular operation, ammonia gas flows into the main ammonia pipe 11 through the external ammonia gas source, and is then delivered to the ammonia injection ports 40 on each straight section 23 through the air inlet branch pipe 41 for injection and mixing, and since the ammonia injection ports 40 are in one-to-one correspondence with the straight sections 23 and the straight sections 23 are in one-to-one correspondence with the injection units 20, independent ammonia gas supply to each injection unit 20 is realized in this way. In addition, due to the design that the partition board 10 with the ammonia main pipe 11 is arranged every other partition board 10 without the ammonia main pipe 11, the spraying units 20 on two sides of the partition board 10 with the ammonia main pipe 11 can supply air through the same ammonia main pipe 11, and the structural layout can ensure that ammonia is uniformly sprayed to the section of the whole flue, greatly simplify the whole structure, reduce the number of unnecessary pipelines, remarkably reduce the installation and maintenance difficulty and reduce the manufacturing cost.

In some embodiments, as shown in fig. 3, tenons are disposed on the connection surfaces of the upper cone section 21 and the lower cone section 22 with the straight section 23, mortises 24 adapted to the tenons are disposed on the straight section 23, screw holes 25 penetrating through the lower cone section 22 are disposed on the conical surface of the upper cone section 21, and the upper cone section 21, the straight section 23 and the lower cone section 22 are fixedly connected with bolts through screw holes. In the actual assembly process, the tenons on the upper cone section 21 and the lower cone section 22 are first aligned with the mortises 24 on the flat sections 23, respectively, and then the upper cone section 21, the flat sections 23 and the lower cone section 22 are assembled together. At this point, the cooperation of the mortise and tenon 24 allows for quick and accurate positioning of the three components. Then, the bolt passes through the screw hole 25 on the conical surface of the upper conical section 21 and extends to the lower conical section 22, so that the upper conical section 21, the flat section 23 and the lower conical section 22 are firmly connected into a whole.

In some embodiments, the ammonia injection grid further comprises a fixed frame (not shown) by which each of the partitions 10 is fixedly connected. In particular, the fixed frame is typically composed of a plurality of interconnected beams or plates, which may be made of steel, stainless steel or other materials of sufficient strength and rigidity, and the diaphragm 10 may be fixedly secured to the fixed frame by bolts, welding or other means of attachment, thereby forming a unitary structure. The structural design ensures that the ammonia injection grid is not a plurality of independent partition boards, but an integral structure with high strength, and can effectively resist the impact and vibration caused by the flow of the flue gas. In addition, the fixed frame not only can provide integral support, but also can be used as a standard for installation, so that the ammonia spraying grille is installed in the flue more conveniently and rapidly, namely, an installer only needs to fix the fixed frame at a preset position in the flue and then fix each partition board 10 on the fixed frame, and independent measurement and positioning of each partition board 10 are not needed.

According to the ammonia spraying grille with spraying and mixing functions, the venturi channel is constructed between the adjacent spraying units, and the straight section and the ammonia spraying port are arranged at the throat, so that the integration of ammonia spraying and mixing is realized, the mixing distance is greatly shortened, the equipment space is saved, and the system cost is reduced. In addition, the design of the uniform distribution of the plurality of injection units and the ammonia injection ports at the throat parts of the venturi channels realizes the uniform distribution of ammonia gas, and overcomes the problem of uneven ammonia gas distribution in the prior art, thereby improving the denitration efficiency, reducing the ammonia gas waste and further optimizing the injection effect. Finally, it is worth mentioning that the method is not only suitable for flue gas denitration of coal-fired power plants, but also suitable for flue gas denitration scenes in other industrial fields, and has wide application prospects.

In the description of the present invention, it should be noted that the azimuth or positional relationship indicated by the terms "vertical", "upper", "lower", "horizontal", etc. are based on the azimuth or positional relationship shown in the drawings, and are merely for convenience of describing the present invention and simplifying the description, and do not indicate or imply that the apparatus or element referred to must have a specific azimuth, be constructed and operated in a specific azimuth, and thus should not be construed as limiting the present invention.

In the description of the present invention, it should also be noted that, unless explicitly specified and limited otherwise, the terms "disposed," "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, integrally connected, mechanically connected, electrically connected, directly connected, indirectly connected through an intermediary, or in communication between two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.

It should be noted that the above-mentioned embodiments are merely preferred embodiments of the present invention, and the present invention is not limited thereto, but may be modified or substituted for some of the technical features thereof by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (8)

1. The ammonia spraying grille with the spraying and mixing functions is arranged in a flue and is characterized by comprising a plurality of partition boards which are transversely and equidistantly arranged along the section of the flue, a plurality of spraying units which are longitudinally and equidistantly arranged along the section of the flue are arranged between every two adjacent partition boards, a venturi channel is formed between every two adjacent spraying units, the venturi channel is provided with a converging section, a throat and a diverging section, each spraying unit comprises an upper cone section and a lower cone section which are oppositely arranged, the upper cone section and the lower cone section are connected through a straight section positioned at the throat of the venturi channel, ammonia spraying ports are formed in the straight sections, the cross section area of each converging section is gradually reduced along the flow direction of flue gas, the cross section area of each diverging section is gradually increased along the flow direction of flue gas, the included angle alpha between the side wall of each converging section and the central axis of the throat is 17-21 DEG, the included angle beta between the side wall of each diverging section and the central axis of the throat is 22-26 DEG, ammonia gas connected with an external ammonia source is formed in each partition board, every other ammonia pipe is formed in each straight section and is connected with every other main pipe, and every other ammonia pipe is provided with every other partition board, and every other ammonia pipe is provided with a partition board.

2. The ammonia injection grille with injection and mixing functions according to claim 1, wherein the ammonia injection port is an oblong hole extending longitudinally along the section of the flue, and the aperture of the oblong hole increases from the air inlet end to the injection end thereof toward the position of the throat.

3. The ammonia injection grid with spraying and mixing functions according to claim 1, wherein the cross section of the upper cone section and the lower cone section parallel to the flow direction of the flue gas in the flue is isosceles triangle.

4. The ammonia injection grid with injection and mixing functions according to claim 1, wherein a mixing space is formed between any two adjacent partition boards, injection units in the mixing spaces longitudinally adjacent along the section of the flue are arranged in a staggered manner, and the staggered distance is equal to the width of the throat.

5. The ammonia spraying grille with the spraying and mixing functions according to claim 1, wherein tenons are arranged on connection surfaces of the upper cone section, the lower cone section and the straight section, mortises matched with the tenons are arranged on the straight section, screw holes penetrating through the lower cone section are formed in the conical surface of the upper cone section, and the upper cone section, the straight section and the lower cone section are fixedly connected with bolts through the screw holes in a locking mode.

6. The ammonia spraying grille with spraying and mixing functions according to claim 1 or 5, wherein a positioning counter bore matched with an upper cone section, a straight section and a lower cone section of the spraying unit is formed in the surface of the partition board, and the straight section is connected with the partition board through bolts.

7. The ammonia injection grid with spraying and mixing functions according to claim 1, wherein the partition plate, the upper cone section, the straight section and the lower cone section are all made of high-temperature-resistant corrosion-resistant alloy materials.

8. The ammonia injection grid with spraying and mixing functions according to claim 1, further comprising a fixed frame through which each of the separators is fixedly connected.