Throat pipe spiral-flow type efficient ammonia air mixer

Abstract

The invention discloses a throat pipe spiral-flow type efficient ammonia-air mixer, and relates to the technical field of mixing equipment of an SCR flue gas denitration technology, in particular to a mixer of ammonia gas and air. The high-efficiency and low-resistance ammonia-air mixer is mainly applied to the SCR denitration technology. According to the technical scheme, in the structure of the mixer, a conical baffle, a semicircular baffle, an expanding part, a throat pipe swirler and a reducing part are sequentially arranged in the airflow direction, ammonia gas and air are introduced from an inlet pipe section of the mixer, primary coarse mixing is conducted under the action of the conical baffle and the semicircular baffle, and secondary coarse mixing is conducted under the action of the throat pipe swirler; afterwards, the roughly-mixed air flow is subjected to diameter expansion and then slowly and uniformly enters a first set of throat pipe cyclones arranged in an array mode, secondary fine mixing is carried out under the dual effects of the throat pipes and the cyclones, and then the air flow passes through the first set of throat pipe cyclones to achieve the purpose of thorough and uniform mixing.

Description

Technical Field

[0001] The invention relates to the technical field of mixing equipment of SCR flue gas denitration technology, and in particular to a mixer for ammonia and air. Background Art

[0002] SCR flue gas denitrification technology has become the mainstream denitrification technology for coal-fired boilers in my country's thermal power plants due to its high denitrification efficiency, mature technology, and adaptability to current environmental protection requirements. The SCR system is generally composed of an ammonia storage system, an ammonia and air mixing system, an ammonia injection system, a reactor system, a detection and control system, etc. Among them, the ammonia-air mixer in the ammonia and air mixing system is responsible for evenly mixing the introduced ammonia and air. In this process, the uniformity of the mixing of ammonia and air will have an important impact on the efficiency of the subsequent reduction reaction. The most common ammonia-air mixer is a baffle mixer, which continuously folds and mixes the two airflows under the intervention of multiple baffles. This mixer has a good mixing effect, but there are many baffles, which creates a large resistance to the airflow. Through development, a cyclone ammonia mixer has been produced, which rotates the mixed gas through a cyclone plate to achieve the purpose of mixing during high-speed rotation. The advantage of this mixer is that it reduces the resistance of the airflow and has a small pressure drop, but the disadvantage is that the mixing effect needs to be further improved. There is also a Venturi mixer, which has the advantages of simple device and convenient processing, but the disadvantage is that the medium is not fully mixed and the mixing effect is not very good. Summary of the invention

[0003] The purpose of the present invention is to organically combine and innovate the advantages of existing ammonia-air mixers, and provide a high-efficiency, low-resistance ammonia-air mixer for SCR denitration technology, namely, a throat swirl type high-efficiency ammonia-air mixer. This mixer has low resistance to the fluid and can achieve a good mixing effect.

[0004] The technical solution adopted by the present invention is: a throat cyclone type high-efficiency ammonia-air mixer is used to mix ammonia and air, and it is composed of an oxidation air inlet pipe, an ammonia inlet pipe, a semicircular baffle, a conical baffle, a diameter expansion, a throat cyclone, a diameter reduction and a diluted ammonia outlet pipe, wherein the throat cyclone is composed of a throat pipe and a cyclone. The throat cyclone type high-efficiency ammonia-air mixer is placed horizontally and is a long straight cylinder. The inlet pipe section of the mixer is a round pipe, which becomes a square pipe after the diameter expansion. There are two groups of array-arranged throat cyclones in the square pipe, each of which has 8 throat cyclones, and the square pipe becomes a round pipe after the diameter reduction, that is, the diluted ammonia outlet pipe. When ammonia and air are introduced from the inlet pipe section of the mixer, they are first roughly mixed under the action of the conical baffle and the semicircular baffle. Then, the roughly mixed airflow enters the first group of array-arranged throat cyclones smoothly and evenly after the diameter is expanded. Under the dual action of the throat and the cyclone, a second fine mixing is performed. Since the cross-sectional area of ​​the middle section of the throat suddenly decreases, the mixed gas flow rate increases rapidly and enters the cyclone. Then, under the action of the cyclone, the high-speed moving mixed airflow will produce high-speed rotation and mixing. Therefore, this mixing is more delicate and the effect will be more uniform. Finally, it passes through a group of array-arranged throat cyclones to achieve the purpose of thorough and uniform mixing. The throat cyclone type high-efficiency ammonia-air mixer adopts a composite design, with fewer baffles and the throat and cyclone used are devices with low resistance, so the overall resistance to the fluid is small.

[0005] Compared with the prior art, the present invention has the following beneficial effects: first, the air and ammonia are thoroughly mixed and uniformly mixed through one baffle rough mixing and two throat cyclone fine mixing, thereby obtaining a good mixing effect; second, the dual effects of the throat and cyclone are utilized in the process of diameter expansion and diameter reduction, thereby increasing the gas flow rate of the gas during mixing and thereby improving the mixing efficiency; third, the advantages of the throat and cyclone having small resistance are fully utilized, thereby effectively reducing the resistance of the built-in components of the mixer to the airflow during mixing. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 It is a structural schematic diagram of the present invention Figure 2 yes Figure 1 1-1 Sectional view Figure 3 yes Figure 1 Section 2-2 Figure 1 Middle: 1. Ammonia inlet pipe, 2. Semicircular baffle, 3. Cyclone, 4. Throat cyclone, 5. Oxidation air inlet pipe, 6. Conical baffle, 7. Expanded diameter, 8. Square tube, 9. Reduced diameter, 10. Diluted ammonia outlet pipe Figure 2 Middle: 1. Cyclone, 2. Cyclone blade, 3. Center blind plate DETAILED DESCRIPTION

[0007] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0008] The structure of the throat swirl type high efficiency ammonia air mixer is shown in Figure 1 , oxidation air and ammonia are introduced from oxidation air inlet pipe 5 and ammonia inlet pipe 1 respectively, and the two air flows are separated under the action of conical baffle 6, and then the first rough mixing is carried out under the obstruction of semicircular baffle 2. The roughly mixed air flow is slightly evenly mixed after the expansion 7, and the fluid flow rate slows down and enters the first group of array-arranged throat cyclone groups. Since the cross-sectional area suddenly decreases when the air flow reaches the middle section of the throat, the flow rate of the mixed gas with a relatively slow flow rate increases rapidly and enters the cyclone. The cyclone is arranged at the air flow inlet end of the middle throat of the throat cyclone, providing a swirl torque for the air flow to rotate the air flow. Due to the high-speed rotation generated by the high-speed mixed air flow, the secondary fine mixing is carried out. This time the mixing is finer and the effect will be more uniform. After the air flow comes out of the first group of throat cyclone groups, it passes through a group of the same throat cyclone to achieve thorough and uniform mixing. Finally, the air flow with ammonia and air mixed evenly is discharged from the diluted ammonia outlet pipe through the reduction.

[0009] exist Figure 1 In the figure, the conical baffle 6 is in the shape of a cone, and its apex is directly opposite to the horizontal center line of the ammonia inlet pipe 1. The apex angle of the cone in the figure is 90 o The bottom diameter is 1 / 2 of the diameter of the oxidation air inlet pipe 5, and the two values ​​can be adjusted as needed.

[0010] exist Figure 1 The semicircular baffle 2 is 45 degrees to the plumb line. o The angle can be adjusted according to actual needs.

[0011] The arrangement of the throat cyclone group is shown in Figure 3 , which is composed of 8 throat cyclones 4 arranged in a 4×4 array, and the number of throat cyclones can also be adjusted as needed. The throat cyclone is composed of a throat and a cyclone 3 that is large at both ends and small in the middle.

[0012] The structure of the cyclone 3 is shown in Figure 2 It consists of 12 swirl blades 2 and a circular center blind plate 3. The diameter of the center blind plate is 1 / 3 of the diameter of the swirl blade. The edge of the swirl blade is tangent to the center blind plate circle and is 40 degrees to the plane where the center blind plate is located. o The angle, number of swirl blades and diameter of the center blind plate can be adjusted as needed.

Claims

1. An ammonia-air mixer, placed horizontally, with oxidation air and ammonia introduced from an oxidation air inlet pipe and an ammonia inlet pipe respectively, characterized in that: In the structure of the mixer, conical baffles, semicircular baffles, expansions, throat cyclones and reductions are arranged in sequence along the direction of airflow. Ammonia and air are introduced from the inlet pipe section of the mixer, and are first roughly mixed under the action of the conical baffles and the semicircular baffles. Then, the roughly mixed airflow passes through the expansion and smoothly and evenly enters the first group of array-arranged throat cyclones. Under the dual action of the throat and the cyclone, a second fine mixing is performed. Then, the airflow passes through another group of throat cyclones to achieve thorough and uniform mixing.

2. The ammonia-air mixer according to claim 1, characterized in that: The conical baffle 6 is in the shape of a cone, and its apex is directly opposite to the horizontal center line of the ammonia inlet pipe 1. The apex angle of the cone in the figure is 90 o The bottom diameter is 1 / 2 of the diameter of the oxidation air inlet pipe 5, and the two values ​​can be adjusted as needed.

3. The ammonia-air mixer according to claim 1, characterized in that: The semicircular baffle 2 is at 45 degrees to the plumb line. o The angle can be adjusted according to actual needs.

4. The ammonia-air mixer according to claim 1, characterized in that: The throat cyclone group is arranged in a 4×4 array and consists of 8 throat cyclones 4, and the number of throat cyclones can also be adjusted as needed. The throat cyclone consists of a throat with large ends and a small middle and a cyclone 3.

5. The ammonia-air mixer according to claim 1 is characterized in that: The cyclone 3 is composed of 12 cyclone blades 2 and a circular center blind plate 3. The diameter of the center blind plate is 1 / 3 of the diameter of the cyclone blade. The edge of the cyclone blade is tangent to the circle of the center blind plate and is 40 degrees to the plane where the center blind plate is located. o The angle, number of swirl blades, diameter of the center blind plate and the elevation angle of the swirl blades can be adjusted as needed.

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