CN204601997U - A kind of boiler smoke and ammonia mixing arrangement - Google Patents

Abstract

The utility model discloses a mixing device for boiler flue gas and ammonia gas, which comprises a vortex mixing plate for generating eddy currents in the ascending flue gas, an ammonia injection pipe arranged above the vortex mixing plate, and a Venturi rod arranged downstream of the vortex mixing plate mechanism, the Venturi rod mechanism includes one or more layers of Venturi rods, the Venturi rods in each layer of Venturi rods are circular tubes or elliptical tubes, and the ammonia gas injection pipe ejects ammonia gas The direction is opposite to the flue gas flow direction, and the distance between the Venturi rod mechanism and the vortex mixing plate is 2-4m. The utility model has the advantages that: before the flue gas reaches the catalyst in the denitrification reactor, the uniform deviation of NO _x and NH ₃ in the flue gas at each point in the mixed flue gas is within ±5%, and the NH ₃ / The purpose of fully mixing NO _x , and simple equipment, low cost, strong adaptability, simple maintenance and good effect.

Description

A boiler flue gas and ammonia gas mixing device

technical field

The utility model relates to a mixing device for boiler flue gas and ammonia gas.

Background technique

The emission of NO _x in boiler tail gas using coal as energy has become an important cause of environmental pollution. The current mainstream technology for denitrification is selective catalyst reduction technology (SCR), which has achieved good results. The uniform mixing of flue gas and reducing agent ammonia, and After mixing, the flue gas is rectified and enters the reactor in a smooth flow state, which is one of the core technologies. There are two kinds of schemes at present, one, the grid type ammonia mixer, its working principle is: the ammonia injection grid is installed inside the flue leading to the SCR reactor. Set as many ammonia gas nozzles as possible to distribute evenly on the flue cross section, and install an adjustment device on the pipe so that the injected ammonia can mix evenly with the flue gas, and set a straight flue after mixing to make the flue gas After the natural rectification is stable, it enters the reactor. 2. The vortex mixer, its working principle is: a vortex mixing plate is set on the inlet flue section of the reactor, so that the flue gas generates a vortex, and the ammonia gas pipeline is aimed at the vortex mixing plate, and diffuses and generates a vortex on the vortex mixing plate The flue gas is mixed, and after mixing, a long straight flue (more than 12 meters) is set up to make the flue gas naturally rectify and stabilize before entering the reactor.

The technical defects of the above two schemes are: 1. Grilled ammonia mixer: During operation, it is found that to achieve the purpose of uniform mixing of ammonia gas and flue gas, the number of nozzles and their pipes is large, and it is complicated to adjust the opening of each valve. At the same time, due to the large number of nozzles and the small aperture of the nozzles, nozzle blockages often occur in high dust environments, seriously affecting the uniform mixing effect of ammonia gas and flue gas, resulting in low denitrification efficiency and increased ammonia escape, resulting in secondary pollution. 2. The simple mixing effect of the vortex mixer equipment is not good, and it cannot mix very uniformly to meet the requirements of denitrification uniformity, and this technology must provide a straight flue of more than 12 meters behind the vortex mixing plate to allow the flue gas in the flue After natural rectification, the flue gas forms a stable flow state before entering the reactor, which restricts the implementation of the project, increases the cost and engineering difficulty, and greatly reduces the scope of application.

Utility model content

The purpose of the utility model is to provide a boiler flue gas and ammonia gas mixing device, which can effectively solve the problem of uneven mixing of existing boiler flue gas and ammonia gas mixing devices.

In order to solve the above-mentioned technical problems, the utility model is realized through the following technical solutions: a boiler flue gas and ammonia gas mixing device, including a vortex mixing plate for generating eddy currents in the ascending flue gas, and an ammonia gas injection device arranged above the vortex mixing plate Tube and a Venturi rod mechanism arranged downstream of the vortex mixing plate, the Venturi rod mechanism includes one or more layers of Venturi rods, and the Venturi rods in each layer of Venturi rods are circular tubes or oval tubes , the direction in which ammonia gas is ejected from the ammonia gas injection pipe is opposite to the flow direction of flue gas, and the distance between the Venturi rod mechanism and the vortex mixing plate is 2-4m.

Preferably, the uppermost layer of Venturi rods is perpendicular to the flue gas outlet of the upper elbow of the flue, the distance between each layer of Venturi rods is 1-2m, and the flowable area of each layer of Venturi rods is the cross-sectional area of the flue 60% to 80% of turbulence; leave an appropriate distance to generate turbulent flow to mix the gas. Too small flow area will hinder the passage of flue gas, so that too much smoke in the pipe will affect turbulence generation. Too large flow area will also cause the flow rate to be too low. Affects turbulence generation.

Preferably, the Venturi rod mechanism includes a multi-layer Venturi rod layer, two adjacent Venturi rod layers are parallel to each other, and the adjacent Venturi rod layers are perpendicular to each other; gas mixing effect.

Preferably, the surface of the vortex mixing plate opposite to the ammonia gas injection pipe is a plane and forms an acute angle with the horizontal plane, and the surface of the vortex mixing plate opposite to the flue gas is an arc-shaped surface protruding toward the flue gas; After vortexing the mixing plate, create a vortex around it.

Compared with the prior art, the utility model has the advantages that before the flue gas reaches the catalyst in the denitrification reactor, the uniform deviation of _NOx and _NH3 in the flue gas at each point in the mixed flue gas is within ±5%. , can completely achieve the purpose of fully mixing NH ₃ /NO _x , and can shorten the length of the straight section of the flue after mixed flow, simple equipment, low cost, strong adaptability, simple maintenance, and good effect.

Description of drawings

Fig. 1 is the structural representation of a kind of boiler flue gas and ammonia mixing device of the present utility model;

Fig. 2 is a schematic diagram of a vortex formed by flue gas flowing through a vortex mixing plate at point A in Fig. 1 .

Detailed ways

Referring to Fig. 1, it is an embodiment of a boiler flue gas and ammonia gas mixing device of the present invention, a boiler flue gas and ammonia gas mixing device, comprising a vortex mixing plate 2 that causes the rising flue gas to generate a vortex, and is arranged on the vortex mixing plate 2 above the ammonia gas injection pipe 3 and the Venturi rod mechanism arranged downstream of the vortex mixing plate 2, the direction in which the ammonia gas injection pipe 3 ejects ammonia gas is opposite to the flow direction of the flue gas, and the Venturi rod mechanism is far from the vortex The distance between the mixing plates 2 is 2-4m, and the Venturi rod mechanism includes at least two layers of Venturi rod layers 4, and the distance between each layer of Venturi rod layers 4 is 1-2m. The flowable area is 60% to 80% of the cross-sectional area of the flue 1. The two adjacent Venturi rod layers 4 are parallel to each other, and the adjacent Venturi rod layers 4 and the rods between the layers are perpendicular to each other. The Venturi rods in the inner rod layer 4 are circular tubes or oval tubes, and the uppermost Venturi rods are perpendicular to the flue gas outlet direction of the upper elbow of the flue.

The surface of the vortex mixing plate 2 opposite to the ammonia injection pipe 3 is a plane and forms an acute angle with the horizontal plane, and the surface of the vortex mixing plate 2 opposite to the flue gas is an arc-shaped surface protruding toward the flue gas.

As shown in Figure 2, the ammonia gas is introduced into the flue 1 through the pipeline, and is sprayed from the ammonia gas injection pipe 3 to the center of the vortex mixer, and the ammonia gas injection direction is against the flue gas direction. Ammonia injection pipe 3 keeps a certain distance with vortex mixing plate 2. After the flue gas 5 is blown to the vortex mixing plate 2, a vortex is formed around it. After the ammonia gas 6 is sprayed onto the leeward side of the vortex mixing plate 2, it spreads to the plane of the vortex mixing plate 2 and vortex mixes with the flue gas to complete the preliminary mixing. After the flue gas and ammonia gas are mixed, the mixed flue gas enters the Venturi rod layer 4 after short-distance rectification, and the flue gas is divided into several parts. Due to the reduction of the flow area of the Venturi layer, the flue gas velocity increases rapidly. , forming a turbulent flow that causes vigorous mixing inside each part of the product. After the flue gas leaves the Venturi, it turns quickly and forms a vortex on the back of the Venturi rod, which makes the fine and uniform mixing between the various parts of the flue gas, so as to achieve the goal of complete mixing.

The above is only a specific embodiment of the utility model, but the technical characteristics of the utility model are not limited thereto, and any changes or modifications made by those skilled in the art within the scope of the utility model are all covered by the utility model. In the scope of the new patent.

Claims (4)

1. A boiler flue gas and ammonia mixing device is characterized in that: comprise the vortex mixing plate (2) that rises the flue gas to generate eddy current, the ammonia injection pipe (3) that is arranged on the vortex mixing plate (2) top and The Venturi rod mechanism that is arranged on the downstream of the vortex mixing plate (2), the Venturi rod mechanism includes one or more layers of Venturi rod layers (4), and the Venturi rods in each layer of Venturi rod layers (4) are A circular pipe or an elliptical pipe, the direction in which the ammonia gas injection pipe (3) ejects ammonia gas is opposite to the flow direction of the flue gas, and the distance between the Venturi rod mechanism and the vortex mixing plate (2) is 2-4m. 2. A kind of boiler flue gas and ammonia mixing device as claimed in claim 1, characterized in that: the uppermost Venturi rod is perpendicular to the flue gas outlet direction of the upper elbow of the flue, and each Venturi rod layer (4) The distance between them is 1-2m, and the flowable area of each Venturi rod layer (4) is 60%-80% of the cross-sectional area of the flue (1). 3. A kind of boiler flue gas and ammonia mixing device as claimed in claim 1 or 2, it is characterized in that: said Venturi rod mechanism comprises multi-layer Venturi rod layer (4), adjacent two layers of Venturi rods The rod layers (4) are parallel to each other, and the rods between adjacent Venturi rod layers (4) layers are perpendicular to each other. 4. A boiler flue gas and ammonia mixing device as claimed in claim 1, characterized in that: the surface of the vortex mixing plate (2) opposite to the ammonia injection pipe (3) is a plane and forms an acute angle with the horizontal plane , the surface of the vortex mixing plate (2) opposite to the flue gas is an arc-shaped surface protruding toward the flue gas.