Dimethyl ether gas boiler burner flue gas internal circulation nitrogen reduction device and use method thereof

Abstract

The present invention proposes a device for reducing nitrogen in the flue gas internal circulation of a dimethyl ether gas boiler burner, comprising a primary air duct, a secondary air duct is arranged outside the primary air duct, a fuel outlet pipe of a fuel pipe is arranged inside the primary air duct, the fuel outlet pipe is connected to a graded outlet pipe, a primary fuel outlet and a secondary fuel outlet are arranged on the graded outlet pipe, the primary fuel outlet corresponds to the primary air duct, and the secondary fuel outlet corresponds to the secondary air duct; a smoke return port is arranged on the secondary air duct. The present invention achieves the purpose of dispersing the temperature of the high-temperature zone by inputting fuel in stages and premixing with the air input in stages, thereby reducing the high temperature and the generation of nitrogen oxides; by providing a smoke return port on the secondary air duct, the burned flue gas is swirled into the secondary air duct for re-combustion, thereby further reducing the generation of nitrogen oxides; and the flue gas is recycled, and the heat capacity of the burned flue gas is large, thereby further reducing the combustion temperature and further reducing the generation of nitrogen oxides.

Description

Technical Field

[0001] The invention relates to the technical field of burners, and in particular to a device for reducing nitrogen in the internal circulation of flue gas from a burner of a dimethyl ether gas boiler and a method for using the device. Background Art

[0002] Nitrogen oxides produced during fuel combustion are mainly NO and NO 2， These two nitrogen oxides are generally referred to as nitrogen oxides NO X , accounting for an average of about 95%, of which NO2 accounts for only about 5%. X ) Through a series of physical and chemical reactions in the atmosphere, NO2 reacts with sunlight, hydrocarbons, ozone, etc. to generate photochemical smog, which is harmful to human health. X It is also an important cause of acid rain and a major culprit in the production of ultrafine particles in the atmosphere (PM2.5).

[0003] Low nitrogen burner is a burner that generates NO during fuel combustion. X Burners with low emissions. How do burners reduce NO X Emissions of nitrogen oxides (NO X The mechanism of production of NO is that during the combustion of fuel, the nitrogen in nitrogen-containing compounds generally exists in an atomic state, and its bond energy is small. During the combustion process, the nitrogen atoms are easily decomposed and oxidized into NO. X It is produced by oxidation of N2 in the air at high temperature. The higher the reaction temperature, the higher the NO X The faster the generation rate, the lower the flame temperature is, the more NO X Very little; when the temperature exceeds 1500℃, NO X will increase exponentially; the higher the oxidation concentration, the NO X The longer the stay time in the high temperature zone, the greater the NO X The more it produces.

[0004] When improving low-nitrogen combustion technology, the main thing to be controlled is temperature, lowering the flame temperature, especially the flame peak temperature, reducing the range of the flame high temperature zone, staged combustion of fuel and air, and full premixed combustion with flue gas recirculation, internal circulation, and external circulation. Summary of the invention

[0005] In view of the above technical problems, the present invention proposes a dimethyl ether gas boiler burner flue gas internal circulation nitrogen reduction device and a use method thereof, so as to solve the problem of high NOX emissions during fuel combustion in the prior art.

[0006] In order to achieve the above object, the technical solution of the present invention is achieved as follows:

[0007] A device for reducing nitrogen in the flue gas internal circulation of a dimethyl ether gas boiler burner and a method for using the device include a primary air duct, a secondary air duct and a fuel pipe, wherein the secondary air duct is arranged outside the primary air duct, and the fuel pipe includes a fuel inlet pipe and a fuel outlet pipe that are connected, and the fuel outlet pipe is arranged inside the primary air duct, and the fuel inlet pipe passes through the primary air duct and the secondary air duct in sequence, and the outlet end of the fuel outlet pipe is connected to a graded outlet pipe, and the graded outlet pipe is provided with a primary fuel outlet and a secondary fuel outlet, the primary fuel outlet corresponds to the primary air duct, and the secondary fuel outlet corresponds to the secondary air duct; a smoke return port is provided at one end of the secondary air duct close to the outlet.

[0008] Furthermore, the graded outlet pipe comprises an outer pipe coaxially connected to the fuel outlet pipe, and at least three primary fuel outlets are provided, and the three primary fuel outlets are evenly distributed on the side wall of the outer pipe.

[0009] Furthermore, an inner tube is arranged inside the outer tube, and the inner tube is extended out of the outer tube to form a plurality of branch tubes, and the secondary fuel outlet is arranged at the outlet end of the branch tube.

[0010] Furthermore, a spoiler is provided at one end of the outer tube close to the primary fuel outlet, and the spoiler corresponds to the outlet end of the primary air duct.

[0011] Furthermore, the spoiler is rotatably connected to the outer tube via a bearing, and the spoiler is located between the first-level fuel outlet and the outlet end of the first-level air duct.

[0012] Furthermore, a spoiler is provided between the secondary air duct and the primary air duct.

[0013] Furthermore, six smoke return ports are provided, and the six smoke return ports are evenly distributed on the side wall of the secondary air duct close to one end of the outlet.

[0014] The method for using the internal circulation nitrogen reduction device for flue gas of a dimethyl ether gas boiler burner comprises the following steps:

[0015] S1. The primary air is introduced into the primary air duct, and the fuel is input into the fuel pipe. The fuel is divided when passing through the graded outlet pipe on the fuel pipe. A part of the fuel is discharged from the primary fuel outlet and premixed with the primary air introduced into the primary air duct and burned;

[0016] S2, while step S1 is being performed, the spoiler rotates under the action of the primary air flow to mix the primary air and the fuel discharged from the primary fuel outlet and stabilize the combustion;

[0017] S3, while step S2 is being performed, the secondary air duct is introduced into the secondary air duct, and the secondary air is dispersed by swirl through the spoiler;

[0018] S4, another part of the fuel input from the fuel pipe in step S1 is discharged from the secondary fuel outlet to be premixed with the secondary air in step S3 and burned;

[0019] S5. While step S1 and step S4 are being performed, the smoke discharged out of the secondary air duct after combustion flows back from the smoke return port and mixes with the secondary air and the fuel discharged from the secondary fuel outlet and burns again.

[0020] The beneficial effects of the present invention are as follows: the present invention achieves the purpose of dispersing the temperature of the high-temperature zone by inputting the fuel in stages and premixing it with the air input in stages, thereby lowering the high temperature and reducing the generation of nitrogen oxides; by providing a smoke return port on the secondary air duct, the burned flue gas is swirled into the secondary air duct for re-combustion, further reducing the generation of nitrogen oxides; and the flue gas is recycled, and the heat capacity of the burned flue gas is large, which can further reduce the combustion temperature and further reduce the generation of nitrogen oxides. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 It is a schematic diagram of the structure of the present invention from a top view;

[0023] Figure 2 for Figure 1 Schematic diagram of the cross-section structure. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] like Figure 1 and Figure 2As shown, the dimethyl ether gas boiler burner flue gas internal circulation nitrogen reduction device and the use method thereof of the present invention include a primary air duct 1, a secondary air duct 2 and a fuel pipe 3, the inlet end of the primary air duct 1 is connected to a primary fan 5 for introducing primary air into the burner, a secondary air duct 2 is arranged outside the primary air duct 1, the primary air duct 1 and the secondary air duct 2 and the fuel pipe 3 are all coaxially arranged, a secondary air inlet pipe is arranged on one side of the secondary air duct 2 and a secondary fan 6 is connected through the secondary air inlet pipe for introducing secondary air into the burner, the fuel pipe 3 includes a fuel inlet pipe 31 and a fuel outlet pipe 32 connected to each other, and the fuel outlet The pipe 32 is arranged inside the primary air duct 1, the fuel inlet pipe 31 passes through the primary air duct 1 and the secondary air duct 2 in sequence, the inlet end of the fuel inlet pipe 31 is connected to the dimethyl ether gas source for inputting fuel to the burner, the outlet end of the fuel outlet pipe 32 is connected to the graded outlet pipe 33, and the graded outlet pipe 33 is provided with a fuel primary outlet 331 and a fuel secondary outlet 332; the fuel primary outlet 331 corresponds to the outlet end of the primary air duct 1, and the dimethyl ether gas outputted from the fuel primary outlet 331 is premixed with the air outputted from the primary air duct 1 at the outlet of the primary air duct 1, which can reduce the temperature of the flame, thereby reducing nitrogen oxides. The secondary fuel outlet 332 corresponds to the secondary air duct 2. Specifically, in this embodiment, the outlet end of the secondary air duct 2 is longer than the primary air duct 1. The fuel is dimethyl ether. The secondary fuel outlet 332 of the graded outlet pipe 33 extends to the secondary air duct 2, which is convenient for the fuel output from the secondary fuel outlet 332 to be premixed with the secondary air input from the secondary air duct 2, so as to further reduce the temperature of the flame, especially reduce the peak temperature of the flame, and reduce the range of the high temperature zone of the flame, thereby reducing the generation of nitrogen oxides; the secondary fuel outlet 332 is located at the outer circle of the primary fuel outlet 331, so that the fuel is input in stages and mixed with the air input in stages. The air is premixed to achieve the purpose of dispersing the temperature in the high-temperature zone; a smoke return port 22 is provided on the end of the secondary air duct 2 near the outlet. After the fuel-mixed air inside the outlet end of the secondary air duct 2 is burned, the air pressure inside the secondary air duct 2 will be slightly lower than that outside the secondary air duct 2. The burned flue gas on the outside of the secondary air duct 2 will swirl back from the smoke return port 22 into the inside of the secondary air duct 2 and burn again with the secondary air and fuel discharged from the secondary outlet 332, further reducing the generation of nitrogen oxides. In addition, the flue gas is recycled, and the heat capacity of the burned flue gas is large, which can further reduce the combustion temperature and further reduce the generation of nitrogen oxides.

[0026] Furthermore, if Figure 1 and Figure 2As shown, the graded outlet pipe 33 includes an outer pipe 333 coaxially connected to the fuel outlet pipe 32, and at least three primary fuel outlets 331 are provided, and the three primary fuel outlets 331 are evenly distributed on the side wall of the outer pipe 333, and the primary fuel outlet 331 is communicated with the inside of the fuel pipe 3. In this embodiment, the outlet end of the fuel pipe 3 is set to three, because the temperature of a single flame is as high as 1500°C or more, and the combustion temperature of a three-hole flame does not exceed 1300°C, which can reduce the high temperature and reduce the generation of nitrogen oxides, while the efficiency in the furnace is not reduced.

[0027] Furthermore, if Figure 2 As shown, an inner tube 334 is arranged inside the outer tube 333, and the inner tube 334 is divided into a plurality of branch tubes after extending out of the outer tube 333, and the secondary fuel outlet 332 is arranged at the outlet end of the branch tube. Specifically, a part of the inner tube 334 is located inside the outer tube 333 and is coaxially arranged with the outer tube 333, and another part of the inner tube 334 is divided into a plurality of branch tubes after extending out of the outer tube 333, and the branch tubes and the inner tube 334 are in an arc transition, and the ends of the inner tube 334 and the outer tube 333 are fixed, and the branch tube part extends in the radial direction of the combustion tube 3, and the secondary fuel outlet 332 is arranged at the outlet end of the branch tube, and the inner tube 334 is the airflow channel of the secondary fuel outlet 332, and the airflow channel of the primary fuel outlet 331 is between the inner tube 334 and the outer tube 333. In this embodiment, the portion of the inner tube 334 extending out of the fuel pipe 3 is divided into six branch pipes. Accordingly, there are six secondary fuel outlets 332. Preferably, the above-mentioned primary fuel outlets 331 are also provided with six. The six primary fuel outlets 331 and the six branch pipes are cross-arranged in the top projection of the fuel pipe 3 so that the branch pipes do not hinder the combustion of the fuel discharged from the primary fuel outlet 331.

[0028] Furthermore, if Figure 2 As shown, a spoiler 4 is provided on one end of the outer tube 333 close to the primary fuel outlet 331, and the spoiler 4 corresponds to the outlet end of the primary air duct 1. At the outlet end of the primary air duct 1, the fuel is mixed with the primary air, and the spoiler 4 provides a swirling airflow, which effectively promotes gas mixing and promotes stable combustion of the flame.

[0029] Furthermore, if Figure 1 and Figure 2 As shown, the spoiler 4 is rotatably connected to the outer tube 333 via a bearing 41, and the spoiler 4 is located between the first-level fuel outlet 331 and the outlet end of the first-level air duct 1, so that the spoiler 4 rotates under the action of the air flow to improve the swirl effect and the stable combustion effect.

[0030] Furthermore, if Figure 1 and Figure 2As shown, a spoiler plate 21 is provided between the secondary air duct 2 and the primary air duct 1. If the spoiler plate 21 is evenly arranged on the outer wall of the primary air duct 1 in a spiral shape, the secondary air enters the combustion zone through the spoiler plate 21, and a better staged combustion effect can be obtained, thereby reducing the temperature of the flame center. During installation, the spoiler plate 21 is first fixed on the outer wall of the primary air duct 1, and then inserted into the secondary air duct 2.

[0031] Furthermore, if Figure 1 As shown, there are six smoke return ports 22, and the six smoke return ports 22 are evenly distributed on the side wall of the secondary air duct 2 close to the outlet end, so as to facilitate the ash outside the secondary air duct 2 to swirl into the secondary air duct 2 for combustion. In this embodiment, the six smoke return ports 22 are arranged on the portion of the secondary air duct 2 that is longer than the primary air duct 1, and the portion of the secondary air duct 2 that is longer than the primary air duct 1 forms a mixing zone for fuel and air.

[0032] The workflow of the present invention comprises the following steps:

[0033] First, the primary fan 5, the secondary fan 6 and the dimethyl ether fuel source are turned on. S1, the primary air is introduced into the primary air duct 1, and the fuel is input into the fuel pipe 3 at the same time. The fuel is diverted when passing through the graded outlet pipe 33 on the fuel pipe 3, and a part of the fuel is discharged from the primary fuel outlet 331 to be premixed with the primary air introduced into the primary air duct 1 and burned; S2, while step S1 is being performed, the spoiler rotates under the action of the primary air flow, and the primary air and the fuel discharged from the primary fuel outlet 331 are mixed and burned stably; S3, in step S2 While the process is being carried out, secondary air is introduced into the secondary air duct 2, and the secondary air is dispersed by swirl after passing through the spoiler 21, so as to obtain a better staged combustion effect; S4, another part of the fuel input by the fuel pipe 3 in step S1 is discharged from the fuel secondary outlet 332, and is premixed with the secondary air in step S3 and burned; S5, while step S1 and step S4 are being carried out, the smoke discharged out of the secondary air duct 2 after combustion is refluxed from the smoke return port 22, and is mixed with the secondary air and the fuel discharged from the fuel secondary outlet 332, and is burned again.

[0034] In this embodiment, the diameter of the secondary air duct 2 is 220 mm, the inner diameter of the primary air duct 1 is 120 mm, the inner diameter of the fuel pipe 3 is 60 mm, the inner diameter of the outer pipe 333 is 60 mm, the aperture of the primary fuel outlet 331 is 25 mm, the inner diameter of the branch pipe is 25 mm, and the inner diameter of the secondary fuel outlet 332 is 25 mm; Beijing and Shanghai nitrogen oxides (NO X ) Emission standard: less than 30 mg per cubic meter. The burner developed by our company has been tested for half a month, and the nitrogen oxides (NO X ) is 25 mg, and the thermal efficiency is not reduced.

[0035] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A dimethyl ether gas boiler burner flue gas internal circulation nitrogen reduction device, characterized in that: The invention comprises a primary air duct (1), a secondary air duct (2) and a fuel pipe (3), wherein the secondary air duct (2) is arranged outside the primary air duct (1), the outlet end of the secondary air duct (2) is longer than the primary air duct (1), the fuel pipe (3) comprises a fuel inlet pipe (31) and a fuel outlet pipe (32) which are connected to each other, the fuel outlet pipe (32) is arranged inside the primary air duct (1), the fuel inlet pipe (31) passes through the primary air duct (1) and the secondary air duct (2) in sequence, the outlet end of the fuel outlet pipe (32) is connected to a graded outlet pipe (33), the graded outlet pipe (33) is provided with a primary fuel outlet (331) and a secondary fuel outlet (332), the primary fuel outlet (331) corresponds to the primary air duct (1), The secondary fuel outlet (332) corresponds to the secondary air duct (2), and the secondary fuel outlet (332) extends toward the secondary air duct (2); a smoke return port (22) is provided at one end of the secondary air duct (2) close to the outlet; the graded outlet pipe (33) comprises an outer pipe (333) coaxially connected to the fuel outlet pipe (32), and the primary fuel outlets (331) are evenly distributed on the side wall of the outer pipe (333); a spoiler (4) is provided at one end of the outer pipe (333) close to the primary fuel outlet (331); an inner pipe (334) is provided inside the outer pipe (333), and the inner pipe (334) extends out of the outer pipe (333) and is divided into a plurality of branch pipes, and the secondary fuel outlet (332) is provided at the outlet end of the branch pipe.

2. The dimethyl ether gas boiler burner flue gas internal circulation nitrogen reduction device according to claim 1, characterized in that: At least three primary fuel outlets (331) are provided, and the three primary fuel outlets (331) are evenly distributed on the side wall of the outer tube (333).

3. The dimethyl ether gas boiler burner flue gas internal circulation nitrogen reduction device according to claim 1 or 2, characterized in that: The spoiler (4) corresponds to the outlet end of the first-level air duct (1).

4. The device for reducing nitrogen in the flue gas internal circulation of a dimethyl ether gas boiler burner according to claim 3, characterized in that: The spoiler (4) is rotatably connected to the outer tube (333) via a bearing (41), and the spoiler (4) is located between the first-level fuel outlet (331) and the outlet end of the first-level air duct (1).

5. The dimethyl ether gas boiler burner flue gas internal circulation nitrogen reduction device according to claim 1, 2 or 4, characterized in that: A spoiler (21) is provided between the secondary air duct (2) and the primary air duct (1).

6. The device for reducing nitrogen in the flue gas internal circulation of a dimethyl ether gas boiler burner according to claim 5, characterized in that: There are six smoke return ports (22), and the six smoke return ports (22) are evenly distributed on the side wall of the secondary air duct (2) close to one end of the outlet.

7. The method for using the dimethyl ether gas boiler burner flue gas internal circulation nitrogen reduction device as claimed in claim 6, characterized in that: The steps include: S1, the primary air is introduced into the primary air duct (1), and fuel is input into the fuel pipe (3). The fuel is divided when passing through the graded outlet pipe (33) on the fuel pipe (3), and a part of the fuel is discharged from the primary fuel outlet (331) to be premixed with the primary air introduced into the primary air duct (1) and then burned; S2, while step S1 is being performed, the spoiler rotates under the action of the primary air flow to mix the primary air and the fuel discharged from the primary fuel outlet (331) and stabilize the combustion; S3, while step S2 is being performed, the secondary air duct (2) is introduced with secondary air, and the secondary air is dispersed by swirl through the spoiler (21); S4, another part of the fuel inputted from the fuel pipe (3) in step S1 is discharged from the secondary fuel outlet (332) to be premixed with the secondary air in step S3 and then burned; S5. While step S1 and step S4 are being performed, the smoke discharged from the secondary air duct (2) after combustion flows back through the smoke return port (22) and mixes with the secondary air and the fuel discharged from the secondary fuel outlet (332) and burns again.

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