Inerting nozzle for primary air box and exhaust gas and primary air mixing device

Abstract

The invention discloses an inerting nozzle for a primary air bellow and a mixing device of exhaust gas and primary air, the inerting nozzle divides a strand of inerting gas into six branches, three circular spraying holes are adopted close to an area easy to accumulate powder to play a role in accelerating airflow, and two circular spraying holes adopt a bevel hedging mode to further enhance the airflow; three oblate spray holes are adopted far away from the area prone to powder accumulation to increase the inerting area, inert gas is introduced into two oblate spray holes in the mode that oblique angles are opposite, and the inerting area is further increased. Primary air is introduced into the mixing device from different directions and positions, adjustment can be carried out according to different exhaust gas introduction modes, mixing of the primary air and exhaust gas is enhanced, local high temperature caused by single inlet air is reduced, and the safety of the system is enhanced.

Description

Technical Field

[0001] The present invention relates to a pulverized coal conveying system for thermal power generation, and particularly to an inerting nozzle for a primary air box and a mixing device for exhaust gas and primary air. Background Art

[0002] Flexible adjustment of pulverized coal supply in thermal power plants is beneficial to improving the economy of power generation. However, the combustion characteristics of different pulverized coals vary greatly, which has an important impact on the safe operation of the pulverized coal conveying system. The intermediate storage pulverized coal system can be divided into an exhaust gas powder feeding system and a hot air powder feeding system. According to the different coal qualities, the more easily combustible coal generally uses the exhaust gas powder feeding system, while the difficult-to-combust coal uses the hot air powder feeding system. The exhaust gas transfer system transfers the exhaust gas into the primary air box, aiming to adjust the intake of exhaust gas and primary air to adapt to different qualities of pulverized coal, so as to send the powder into the furnace for combustion. However, the exhaust gas contains a small amount of fine pulverized coal that has not been separated by the fine powder separator. These fine pulverized coals may accumulate and deposit in the primary air box. If hot primary air with a relatively high temperature and oxygen content is introduced, it may cause deflagration of the pulverized coal. Summary of the Invention

[0003] Object of the Invention: The first object of the present invention is to provide an inerting nozzle that can inert an important area where powder may accumulate in the primary air box; the second object of the present invention is to provide a mixing device that can fully mix the exhaust gas and the primary air to reduce the local high-temperature area.

[0004] Technical Solution: The inerting nozzle for the primary air box of the present invention has an air inlet at the bottom of the primary air box; the inerting nozzle includes an inerting gas pipe. One end of the inerting gas pipe has an arc reducer. The arc reducer is divided into upper and lower parts. The upper arc reducer is connected with two bevel flat pipes and one straight flat pipe. The straight flat pipe is located in the middle of the upper arc reducer. The two bevel flat pipes are symmetrically distributed, and the two bevel flat pipes introduce inert gas in a way that the bevels face away from each other; the lower arc reducer is connected with two right-angle round pipes and one straight round pipe. The straight round pipe is located in the middle of the lower arc reducer. The two right-angle round pipes are symmetrically distributed, and the two right-angle round pipes introduce inert gas in a way that the bevels are in a head-on collision.

[0005] Further, the arc reducer as a whole is a frustum of a cone with a hollow conical shape and has a notch with a certain angle, dividing the arc reducer into an upper arc reducer and a lower arc reducer.

[0006] Further, the cross-sections of the right-angle round pipe and the straight round pipe are circular, and the diameters of the right-angle round pipe and the straight round pipe are the same.

[0007] Further, the cross-sections of the bevel flat pipe and the straight flat pipe are waist-shaped, and the cross-sectional areas of the bevel flat pipe and the straight flat pipe are equal.

[0008] Furthermore, the difference in cross-sectional area between the right-angled circular pipe and the beveled flat pipe is less than 5%.

[0009] Furthermore, the incident angles of the two right-angled circular pipes are 45° and 135° respectively.

[0010] Furthermore, the incident angles of the two beveled flat pipes are 135° and 45° respectively.

[0011] The mixture device of the exhaust gas and the primary air of the present invention includes a primary air main pipe, a primary air box and the inerting nozzle described above; the primary air main pipe is located above the primary air box and is connected to the primary air box through a first inclined branch pipe, a second inclined branch pipe, a first straight branch pipe and a second straight branch pipe. The first inclined branch pipe and the second inclined branch pipe are in the same plane and are respectively connected to both sides of the primary air box; the first inclined branch pipe and the second inclined branch pipe are symmetrical about the central axis of the primary air box; the first straight branch pipe and the second straight branch pipe are in the same plane and are respectively connected to the upper side of the primary air box; the first straight branch pipe and the second straight branch pipe are symmetrical about the central axis of the primary air box;

[0012] The primary air box is also connected with a first exhaust gas transfer pipe and a second exhaust gas transfer pipe. The gas inlet directions of the first inclined branch pipe and the first straight branch pipe intersect with the gas inlet direction of the first exhaust gas transfer pipe; the gas inlet directions of the second inclined branch pipe and the second straight branch pipe intersect with the gas inlet direction of the second exhaust gas transfer pipe;

[0013] Valves for flow regulation are respectively arranged on the first inclined branch pipe, the second inclined branch pipe, the first straight branch pipe and the second straight branch pipe.

[0014] Furthermore, the air flow enters the primary air box along the inclined branch pipe at 45°.

[0015] Furthermore, the air flow enters the primary air box vertically along the straight branch pipe, and the air flow direction is perpendicular to the exhaust gas inlet direction.

[0016] Beneficial effects: Compared with the prior art, the present invention has the following remarkable advantages:

[0017] (1) The inerting nozzle designed by the present invention divides an inerting gas into six branches. Three circular nozzles are adopted near the area prone to powder accumulation to play a role in accelerating the air flow. Among them, two circular nozzles adopt the way of beveled head-on impact to further enhance the air flow; three flat circular nozzles are adopted away from the area prone to powder accumulation to play a role in increasing the inerting area. Among them, two flat circular nozzles are used to introduce inert gas in the way of beveled back-to-back, further increasing the inerting area.

[0018] (2) The mixing device designed in the present invention can enhance the mixing of primary air and lean gas from different directions because the gas inlet directions of the first inclined through-branch pipe, the first straight-through branch pipe and the first lean gas transfer pipe intersect, and the gas inlet directions of the second inclined through-branch pipe, the second straight-through branch pipe and the second lean gas transfer pipe intersect. At the same time, each branch pipe can independently control the air inlet ratio of the branch pipe according to different working conditions, making the mixed gas as close as possible to the central axis of the primary air box and making the temperature inside the primary air box more uniform. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 FIG. is a schematic structural diagram of a lean gas and primary air mixing device provided by an embodiment of the present invention;

[0020] Figure 2 is Figure 1 side view of;

[0021] Figure 3 FIG. is a schematic structural diagram of an inerting nozzle for a primary air box provided by an embodiment of the present invention, wherein Figure 3 (a) is a front view, Figure 3 (b) is a top view, Figure 3 (c) is a side view. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] The present invention will be further described below with reference to the drawings.

[0023] Attached Figures 1 to 3 The reference numerals in the drawings are as follows:

[0024] 1, primary air main pipe; 11, through-branch pipe; 111, first through-branch pipe; 112, second through-branch pipe; 12, straight-through branch pipe; 121, first straight-through branch pipe; 122, second straight-through branch pipe; 13, valve; 41, first lean gas transfer pipe; 42, second lean gas transfer pipe; 2, primary air box; 3, inerting nozzle; 31, inerting gas pipe; 32, arc reducer; 321, upper arc reducer; 322, lower arc reducer; 33, right-angle round pipe; 331, first right-angle round pipe; 332, second right-angle round pipe; 34, bevel flat pipe; 341, first bevel flat pipe; 342, second bevel flat pipe; 35, straight flat pipe; 36, straight round pipe.

[0025] Embodiment 1

[0026] As Figure 1 and Figure 3 shown, this Embodiment 1 provides an inerting nozzle for a primary air box, and the air inlet of the inerting nozzle 3 is located at the bottom of the upper half process of the primary air box 2.

[0027] The inerting nozzle 3 includes an inerting gas pipe 31. One end of the inerting gas pipe 31 has an arc reducer 32. The arc reducer 32 expands with the inerting gas pipe 31 as the small end, and its large end is divided into upper and lower parts and extends obliquely towards the small end. The arc reducer 32 as a whole is a frustum of a cone with a hollow conical shape and has a notch with a 10° angle, dividing the arc reducer 32 into an upper arc reducer 321 and a lower arc reducer 322.

[0028] Two angled flat pipes 34 and one straight flat pipe 35 are connected to the upper arc reducer 321. The straight flat pipe 35 is located at the middle position of the upper arc reducer 321. The two angled flat pipes 34 are respectively a first angled flat pipe 341 and a second angled flat pipe 342, and are symmetrically distributed on the upper arc reducer 321. The two angled flat pipes 34 introduce inert gas in a way that the angles are opposite to each other. In this embodiment, the incident angle of the first angled flat pipe 341 is 135°, and the incident angle of the second angled flat pipe 342 is 45°.

[0029] Two right-angled round pipes 33 and one straight round pipe 36 are connected to the lower arc reducer 322. The straight round pipe 36 is located at the middle position of the lower arc reducer 322. The two right-angled round pipes 33 are respectively a first right-angled round pipe 331 and a second right-angled round pipe 332, and are symmetrically distributed on the lower arc reducer 322. The two right-angled round pipes 33 introduce inert gas in a way that the angles are opposite to each other. In this embodiment, the incident angle of the first right-angled round pipe 331 is 45°, and the incident angle of the second right-angled round pipe 332 is 135°.

[0030] The cross-sections of the right-angled round pipes 33 and the straight round pipe 36 are circular, and the diameters of the right-angled round pipes 33 and the straight round pipe 36 are the same. The cross-sections of the angled flat pipes 34 and the straight flat pipe 35 are waist-shaped, and the cross-sectional areas of the angled flat pipes 34 and the straight flat pipe 35 are equal.

[0031] In this embodiment, the diameter of the inerting gas pipe 31 is 150 mm; the small end diameter of the arc reducer 32 is 150 mm, the large end diameter is 400 mm, and the diameter of the internal conical hollow part is 160 mm; the central positions of the six nozzles are located on a concentric circle with a large end face diameter of 275 mm; the cross-section of the angled flat pipe 34 or the straight flat pipe 35 has a straight section length of 40 mm and an arc section radius of 15 mm; the angled flat pipe 34 consists of a section perpendicular to the large and small end face and another section with an angle of 45° with the large and small end face; the straight flat pipe 35 is 1000 mm long; the cross-section of the right-angled round pipe 33 or the straight round pipe 36 is a circle with a diameter of 50 mm; the right-angled round pipe 33 includes two sections of round pipes with an included angle of 90°, and the round pipe section connecting the large and small ends has an angle of 45° with the large and small ends; the straight round pipe 36 is 1000 mm long.

[0032] The inerting nozzle provided in Embodiment 1 divides an inert gas into six branches. Three circular nozzles are used near the area prone to powder accumulation to increase the air flow velocity. Among them, two circular nozzles use the method of diagonal counter-jet to further enhance the air flow. Three oval nozzles are used away from the area prone to powder accumulation to increase the inerting area. Among them, two oval nozzles introduce inert gas in the way of diagonal back-to-back, further increasing the inerting area.

[0033] Embodiment 2

[0034] As Figure 1 and Figure 2 shown, the mixing device of flue gas and primary air provided in Embodiment 2 includes a primary air main pipe 1, a primary air box 2, an inclined branch pipe 11, a straight branch pipe 12, and the inerting nozzle 3 described in Embodiment 1. The inerting nozzle 3 is arranged at the bottom of the primary air box 2.

[0035] There are two inclined branch pipes 11, namely the first inclined branch pipe 111 and the second inclined branch pipe 112 respectively. There are also two straight branch pipes 12, namely the first straight branch pipe 121 and the second straight branch pipe 122 respectively. The primary air main pipe 1 is square and located above the primary air box 2. The primary air main pipe 1 is connected to the primary air box 2 through the first inclined branch pipe 111, the second inclined branch pipe 112, the first straight branch pipe 121 and the second straight branch pipe 122. The first inclined branch pipe 111 and the second inclined branch pipe 112 are in the same plane and are respectively connected to both sides of the primary air box 2; the first inclined branch pipe 111 and the second inclined branch pipe 112 are symmetrical about the central axis of the primary air box 2; the first straight branch pipe 121 and the second straight branch pipe 122 are in the same plane and are respectively connected to the upper side of the primary air box 2; the first straight branch pipe 121 and the second straight branch pipe 122 are symmetrical about the central axis of the primary air box 2. In this embodiment, the interval distance between the first inclined branch pipe 111 and the first straight branch pipe 121 is 1500 mm, the interval distance between the first straight branch pipe 121 and the second straight branch pipe 122 is 1100 mm, and the interval distance between the second straight branch pipe 122 and the second inclined branch pipe 112 is 1500 mm.

[0036] The primary air box 2 is also connected with a first flue gas transfer pipe 41 and a second flue gas transfer pipe 42. The gas inlet directions of the first inclined branch pipe 111 and the first straight branch pipe 121 intersect with the gas inlet direction of the first flue gas transfer pipe 41; the gas inlet directions of the second inclined branch pipe 112 and the second straight branch pipe 122 intersect with the gas inlet direction of the second flue gas transfer pipe 42. In this embodiment, the air flow enters the primary air box 2 along the inclined branch pipe at an angle of 45°. The air flow enters the primary air box 2 vertically along the straight branch pipe, and the air flow direction is perpendicular to the flue gas inlet direction.

[0037] Valves 13 for flow regulation are respectively arranged on the first inclined branch pipe 111, the second inclined branch pipe 112, the first straight branch pipe 121 and the second straight branch pipe 122.

[0038] The mixing device provided in this Embodiment 2 can introduce primary air from different directions and positions, can be adjusted according to different ways of introducing exhaust gas, enhance the mixing of primary air and exhaust gas, reduce the local high temperature caused by single air inlet, and enhance the safety of the system.

Claims

1. An inerting nozzle for a primary wind box, characterized in that: The air inlet of the inerting nozzle (3) is located at the bottom of the primary wind box (2); the inerting nozzle (3) comprises an inerting air pipe (31), one end of the inerting air pipe (31) has an arc reducer (32), the arc reducer (32) is divided into an upper and lower part, the upper arc reducer (321) is connected to two oblique angle flat tubes (34) and a straight flat tube (35), and the straight flat tube (35) is located in the middle of the upper arc reducer (321). The two oblique angle flat tubes (34) are symmetrically distributed, and the two oblique angle flat tubes (34) are fed with inert gas in a manner of oblique angles facing each other; the lower arc size head (322) is connected with two right-angled circular tubes (33) and a straight circular tube (36), and the straight circular tube (36) is located in the middle of the lower arc size head (322); the two right-angled circular tubes (33) are symmetrically distributed, and the two right-angled circular tubes (33) are fed with inert gas in a manner of oblique angles facing each other.

2. The inerting nozzle for a primary air box according to claim 1, characterized in that: The arc reducer (32) is a hollow truncated cone in the shape of a cone as a whole, and has a notch with a certain angle, which divides the arc reducer (32) into an upper arc reducer (321) and a lower arc reducer (322).

3. The inerting nozzle for a primary air box according to claim 1, characterized in that: The cross sections of the right-angled circular tube (33) and the straight circular tube (36) are circular, and the diameters of the right-angled circular tube (33) and the straight circular tube (36) are the same.

4. The inerting nozzle for a primary air box according to claim 3, characterized in that: The cross sections of the oblique angle flat tube (34) and the straight flat tube (35) are waist-shaped, and the cross-sectional areas of the oblique angle flat tube (34) and the straight flat tube (35) are equal.

5. The inerting nozzle for a primary air box according to claim 4, characterized in that: The cross-sectional area difference between the right-angled circular tube (33) and the oblique-angled flat tube (34) is less than 5%.

6. The inerting nozzle for a primary air box according to claim 1, characterized in that: The incident angles of the two right-angle circular tubes (33) are 45° and 135° respectively.

7. The inerting nozzle for a primary air box according to claim 1, characterized in that: The incident angles of the two oblique angle flat tubes (34) are 135° and 45° respectively.

8. A device for mixing exhaust gas and primary air, characterized in that: The invention comprises a primary air main pipe (1), a primary air box (2) and an inerting nozzle according to any one of claims 1 to 7; the primary air main pipe (1) is located above the primary air box (2), and is connected to the primary air box (2) through a first oblique branch pipe (111), a second oblique branch pipe (112), a first straight branch pipe (121) and a second straight branch pipe (122); the first oblique branch pipe (111) and the second oblique branch pipe (112) are located in the same plane and are respectively connected to two sides of the primary air box (2); the first oblique branch pipe (111) and the second oblique branch pipe (112) are symmetrical about the central axis of the primary air box (2); the first straight branch pipe (121) and the second straight branch pipe (122) are located in the same plane and are respectively connected to the upper side of the primary air box (2); the first straight branch pipe (121) and the second straight branch pipe (122) are symmetrical about the central axis of the primary air box (2); The primary wind box (2) is also connected to a first exhaust gas transfer pipe (41) and a second exhaust gas transfer pipe (42); the gas introduction direction of the first oblique branch pipe (111) and the first straight branch pipe (121) intersects with the gas introduction direction of the first exhaust gas transfer pipe (41); the gas introduction direction of the second oblique branch pipe (112) and the second straight branch pipe (122) intersects with the gas introduction direction of the second exhaust gas transfer pipe (42); Valves (13) for flow rate regulation are respectively provided on the first oblique branch pipe (111), the second oblique branch pipe (112), the first straight branch pipe (121) and the second straight branch pipe (122).

9. The exhaust gas and primary air mixing device according to claim 8, characterized in that: The airflow enters the primary wind box (2) along the oblique branch pipe at an angle of 45 degrees.

10. The exhaust gas and primary air mixing device according to claim 9, characterized in that: The airflow vertically enters the primary wind box (2) along the straight branch pipe, and the airflow direction is perpendicular to the exhaust gas introduction direction.

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