Nitrogen reduction device for burner of dimethyl ether gas boiler

Abstract

The present invention discloses a nitrogen reduction device for a dimethyl ether gas boiler burner, which solves the technical problem in the prior art that the thermal efficiency of the boiler will be reduced when the flame temperature is reduced in order to reduce the nitrogen oxides generated by combustion. The present invention comprises an outer shell, a cyclone mechanism is arranged in the inner cavity of the outer shell, an air suction hole opposite to the cyclone mechanism is arranged at one end of the outer shell, a fire outlet hole is opened at the other end of the outer shell, a first central fuel nozzle opposite to the fire outlet hole is arranged in the outer shell, and an outer ring flame unit is arranged around the outer shell. The present invention adopts a structural mode of combining a small-aperture flame nozzle with a flame outlet hole to construct a multi-nozzle small-hole flame spraying, and adopts a method of premixing the center fire to reduce the flame temperature without changing the thermal efficiency. The nitrogen oxide emission standards in Beijing and Shanghai are: less than 30 mg per cubic meter. After ten days of combustion test using the burner of the present invention, the emission of nitrogen oxides is less than 30 mg per cubic meter, only 26 mg.

Description

Technical Field

[0001] The invention belongs to the technical field of burners, and in particular relates to a nitrogen reduction device for a burner of a dimethyl ether gas boiler. Background Art

[0002] Compared with other fuels, dimethyl ether fuel gas is cleaner. Its main pollutants are nitrogen oxides (NO X ), NO X In addition to harming human health, NO also generates photochemical smog through a series of physical and chemical reactions in the atmosphere, under sunlight, and with hydrocarbons, ozone, etc. X It is also an important cause of acid rain and the main culprit of producing ultrafine particulate matter (PM2.5) in the atmosphere. X ) and the NO generated during gas combustion X There are three main types of NO: fuel type, thermal type, and rapid type. X During the combustion process, carbon oxides decompose at high temperature to produce CH free radicals, which react with N2 molecules in the air to produce HCN and N, which are further oxidized and the reaction time is only 60ms. Fast NO X The amount of fuel NO is relatively small, usually less than 5%. X Refers to the nitrogen compounds in the fuel produced during the combustion process. The nitrogen in the nitrogen compounds in the fuel usually exists in the atomic state, and its bond energy is small. It is easy to decompose and oxidize into NO during the combustion process. X .

[0003] The thermal 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 of thermal NO X The influencing factors are as follows:

[0004] 1. When the temperature is lower than 1300℃, the NO generated X Rarely, when the temperature exceeds 1500℃, NO X will multiply;

[0005] 2. The higher the oxygen concentration, the higher the NO X The greater the amount produced;

[0006] 3. The longer you stay in the high temperature zone, the more NO X The more it produces.

[0007] In the existing technology, when improving low-nitrogen combustion technology, the main control is thermal NO XAccording to its generation mechanism, the direction of control is to reduce the flame temperature, especially the peak flame temperature, and reduce the range of the flame high temperature zone. Specific measures include: fuel / air staged combustion technology, flue gas recirculation technology (internal circulation, external circulation), full premixed surface combustion technology, water-cooled combustion technology, and low excess air coefficient method. The second category is flue gas denitrification technology, which refers to the removal of NO already generated in the flue gas. X For treatment, the main related technologies are: precious metal exclusive catalytic denitrification method, selective catalytic reduction method, selective non-catalytic reduction method, alkaline solution absorption method, etc.

[0008] Gas boilers, which are widely used in the boiler industry, mostly adopt combustion control methods, which mainly reduce nitrogen oxides by optimizing the combustion process in the furnace, reasonably optimizing the mixture of fuel and air, controlling the flame distribution, and reducing the temperature in the furnace. Common methods include the following:

[0009] Air staged combustion

[0010] The air required for combustion is mixed with the fuel in stages to reduce the flame intensity and flame temperature. The secondary air outlet has a high wind speed, which rolls the surrounding smoke and recirculates the smoke in the furnace to achieve the effect of graded air distribution. On the one hand, it reduces the center flame temperature, and on the other hand, it dilutes the oxygen concentration on the flame surface, thereby inhibiting NO X Generation of.

[0011] Fuel staged combustion

[0012] Fuel staged combustion means that the fuel is fed into the furnace from different areas so that the fuel is burned in stages and areas. The space of the combustion chamber is fully utilized to disperse the fuel, reduce the concentration of flames, and reduce the temperature of the high-temperature area.

[0013] Staged combustion

[0014] Staged combustion is a combination of air staged combustion and fuel staged combustion. Air and fuel are supplied to the combustion device in stages to control the ratio of fuel and air in the combustion zone. The principle of staged combustion technology is essentially to disperse the flame, reduce the flame temperature, promote local circulation of flue gas in the furnace, form a reducing atmosphere, and reduce part of the NO that has been produced to N2, thereby controlling the total amount of NO. X emission concentration.

[0015] Although staged combustion technology can reduce the generation of nitrogen oxides with a certain degree of difficulty, many burners do not fully achieve the full mixing of combustion air and gas in actual use. There are local high-temperature areas in the furnace, and their temperatures are higher than those of the production of thermal NO X The temperature causes NO XOn the other hand, the existing staged combustion technology is prone to poor mixing fluidity of fuel and air, resulting in incomplete combustion such as excessive carbon monoxide and local carbon deposition. In order to reduce the reaction temperature, it is necessary to disperse the flame as much as possible and expand the shape of the hot pot. In other words, the volume of the furnace is limited. In order to avoid the flame being too large relative to the furnace, the output power of the burner is usually reduced, which can reduce NO X concentration and ensure complete combustion, but the boiler power is reduced and there is a risk of flue gas condensation. Summary of the invention

[0016] In view of the deficiencies in the above-mentioned background technology, the present invention proposes a dimethyl ether gas boiler burner nitrogen reduction device, which solves the technical problem in the prior art that lowering the flame temperature in order to reduce nitrogen oxides generated by combustion will lead to a decrease in boiler thermal efficiency.

[0017] The technical solution of the present invention is implemented as follows: a dimethyl ether gas boiler burner nitrogen reduction device comprises an outer shell, a cyclone mechanism is arranged in the inner cavity of the outer shell, an air suction hole opposite to the cyclone mechanism is arranged at one end of the outer shell, a fire outlet hole is opened at the other end of the outer shell, a first central fuel nozzle opposite to the fire outlet hole is arranged in the outer shell, and an outer ring flame spraying unit is arranged around the outer shell.

[0018] Furthermore, the outer ring flame spraying unit comprises an outer ring flame spraying nozzle and a central flame spraying nozzle, and the outer ring flame spraying nozzle surrounds the outer circumference of the central flame spraying nozzle.

[0019] Furthermore, the central flame spray nozzle is correspondingly provided with a second central fuel nozzle and is communicated with the inner cavity of the outer shell, and the outer ring flame spray nozzle is connected with an outer ring fuel nozzle.

[0020] Furthermore, the outer shell is cylindrical, and the fire outlet holes are arranged at equal intervals on the outer edge of the end surface of the outer shell.

[0021] Furthermore, a plurality of outer ring flame spraying units are provided, and the plurality of outer ring flame spraying units are arranged at equal intervals on the outer circumference of the outer shell.

[0022] Furthermore, the outer ring flame spraying unit comprises an outer ring cylinder connected to the outer shell, the top projection of the outer ring cylinder is approximately circular, the central flame spraying nozzle is arranged at the center of the outer ring cylinder, and the outer ring flame spraying nozzles are arranged at equal intervals on the periphery of the central flame spraying nozzle.

[0023] Furthermore, four central flame spray nozzles are arranged in each outer ring tube, and six outer ring flame spray nozzles are arranged around the four central flame spray nozzles.

[0024] Furthermore, the inner diameters of the outer ring flame nozzle and the central flame nozzle are 1.5 mm.

[0025] Furthermore, the inner diameter of the outer shell is 260 mm, and the cyclone mechanism includes cyclone blades with a length of 100 mm.

[0026] Furthermore, the diameter of the air suction hole is 3 mm, the inner diameters of the first central fuel nozzle and the second central fuel nozzle are 12 mm, the inner diameter of the outer ring fuel nozzle is 8 mm, and the diameter of the fire outlet hole is 10 mm.

[0027] The present invention not only adopts a structural mode of combining a small-aperture flame nozzle with a flame hole to construct a multi-nozzle small-hole flame spray, but also adopts a central fire premixing method to reduce the flame temperature without changing the thermal efficiency. Since dimethyl ether fuel gas contains 35% oxygen, it will not absorb more oxygen in the air during combustion. The air-fuel ratio is reasonably matched by the premixing method, and the generation of nitrogen oxides is also reduced. The nitrogen oxide emission standards in Beijing and Shanghai are: less than 30 mg per cubic meter. After ten days of combustion testing using the burner of the present invention, the nitrogen oxide emissions were less than 30 mg per cubic meter, only 26 mg, and the thermal efficiency was not reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying any creative work.

[0029] Figure 1 It is a schematic diagram of the top view of the structure of the present invention;

[0030] Figure 2 for Figure 1 A schematic cross-sectional structure diagram of ;

[0031] In the figure: 1-outer shell, 2-cyclone mechanism, 21-cyclone blades, 22-rotating shaft, 23-bracket, 3-air suction hole, 4-fire outlet hole, 5-first central fuel nozzle, 6-outer ring flame unit, 61-outer ring flame nozzle, 62-central flame nozzle, 63-outer ring cylinder, 7-outer ring fuel nozzle, 8-second central fuel nozzle. DETAILED DESCRIPTION

[0032] 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.

[0033] A nitrogen reduction device for a dimethyl ether gas boiler burner, such as Figure 2 As shown, it includes a cylindrical outer shell 1, and the inner diameter of the outer shell 1 is 260mm. A cyclone mechanism 2 is arranged in the inner cavity of the outer shell 1, and the cyclone mechanism 2 includes a cyclone blade 21 with a length of 100mm. The cyclone blade 21 is arranged on a rotating shaft 22, and the rotating shaft 22 is rotatably arranged between the end of the outer shell 1 and the bracket 23 of the inner cavity. The rotating shaft 22 is driven by a motor, and the installation position of the motor is not shown in the figure. An air suction hole 3 opposite to the cyclone mechanism 2 is arranged at one end of the outer shell 1, and the aperture of the air suction hole 3 is 3mm. External air enters the inner cavity of the outer shell 1 through the air suction hole 3, and under the action of the cyclone blade 21, the external air is blown to the other end of the inner cavity.

[0034] The outer shell 1 has a fire outlet hole 4 at one end toward which the external air is blown, and a first central fuel nozzle 5 opposite to the fire outlet hole 4 is arranged inside the outer shell 1. The dimethyl ether fuel gas delivered by the first central fuel nozzle 5 is premixed with the air sucked by the cyclone mechanism 2 in the inner cavity, and then the flame is discharged through the fire outlet hole 4.

[0035] like Figure 1 As shown, there are a plurality of fire holes 4, which are evenly spaced at the outer edge of the end surface of the outer shell 1, and the diameter of the fire holes 4 is 10 mm.

[0036] Furthermore, an outer ring flame spraying unit 6 is arranged around the outer shell 1. The outer ring flame spraying unit 6 includes an outer ring cylinder 63 connected to the outer shell 1, and the air sucked in by the cyclone mechanism 2 can enter the outer ring cylinder 63. A second central fuel nozzle 8 is arranged in the outer ring cylinder 63, and the air sucked in by the cyclone mechanism 2 can enter the front port of the second central fuel nozzle 8, and the dimethyl ether fuel gas output by the second central fuel nozzle 8 can be pre-mixed with the air sucked in by the cyclone mechanism 2 in the outer ring.

[0037] The combustion end of the outer ring tube 63 is provided with an outer ring flame nozzle 61 and a central flame nozzle 62. A plurality of outer ring flame units 6 are provided, and the plurality of outer ring flame units 6 are arranged at intervals on the outer periphery of the outer shell 1. The central flame nozzle 62 corresponds to the second central fuel nozzle 8 and is connected to the inner cavity of the outer shell 1. The outer ring flame nozzle 61 is connected to the outer ring fuel nozzle 7. The dimethyl ether gas output by the outer ring fuel nozzle 7 is directly burned through the outer ring flame nozzle 61, and the dimethyl ether gas output by the second central fuel nozzle 8 is premixed in the outer ring tube 63 and then burned through the central flame nozzle 62. The inner diameters of the first central fuel nozzle 5 and the second central fuel nozzle 8 are 12 mm.

[0038] Furthermore, the top projection of the outer ring tube 63 is approximately circular, the central flame nozzle 62 is arranged at the center of the outer ring tube 63, and the outer ring flame nozzles 61 are arranged at equal intervals on the outer periphery of the central flame nozzle 62.

[0039] Furthermore, four central flame spray nozzles 62 are arranged in each outer ring tube 63, and six outer ring flame spray nozzles 61 are arranged on the periphery of the four central flame spray nozzles 62. The inner diameters of the outer ring flame spray nozzles 61 and the central flame spray nozzles 62 are 1.5 mm.

[0040] The details not described in detail in the present invention are all conventional technical means known to those skilled in the art.

[0041] 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 nitrogen reduction device for a dimethyl ether gas boiler burner, comprising an outer shell (1), characterized in that: A cyclone mechanism (2) is arranged in the inner cavity of the outer shell (1); an air suction hole (3) opposite to the cyclone mechanism (2) is arranged at one end of the outer shell (1); a fire outlet hole (4) is opened at the other end of the outer shell (1); a first central fuel nozzle (5) opposite to the fire outlet hole (4) is arranged in the outer shell (1); and an outer ring flame spraying unit (6) is arranged around the outer shell (1); The outer ring flame spray unit (6) comprises an outer ring flame spray nozzle (61) and a central flame spray nozzle (62), wherein the outer ring flame spray nozzle (61) surrounds the outer circumference of the central flame spray nozzle (62); The central flame spray nozzle (62) is provided with a corresponding fuel second central nozzle (8) and is in communication with the inner cavity of the outer shell (1), and the outer ring flame spray nozzle (61) is connected to the fuel outer ring nozzle (7); The inner diameters of the first central fuel nozzle (5) and the second central fuel nozzle (8) are 12 mm, the inner diameter of the outer fuel nozzle (7) is 8 mm, and the diameter of the ignition hole (4) is 10 mm.

2. The nitrogen reduction device for a dimethyl ether gas boiler burner according to claim 1, characterized in that: The outer shell (1) is cylindrical, and the fire outlet holes (4) are arranged at equal intervals on the outer edge of the end surface of the outer shell (1).

3. The nitrogen reduction device for a dimethyl ether gas boiler burner according to claim 1, characterized in that: A plurality of outer ring flame spraying units (6) are provided, and the plurality of outer ring flame spraying units (6) are arranged at equal intervals on the outer circumference of the outer shell (1).

4. The nitrogen reduction device for a dimethyl ether gas boiler burner according to claim 3, characterized in that: The outer ring flame spraying unit (6) comprises an outer ring cylinder (63) connected to the outer shell (1), the outer ring cylinder (63) is approximately circular in top view, the central flame spraying nozzle (62) is arranged at the center of the outer ring cylinder (63), and the outer ring flame spraying nozzles (61) are arranged at equal intervals on the periphery of the central flame spraying nozzle (62).

5. The nitrogen reduction device for a dimethyl ether gas boiler burner according to claim 4, characterized in that: Four central flame spray nozzles (62) are arranged in each outer ring cylinder (63), and six outer ring flame spray nozzles (61) are arranged on the outer periphery of the four central flame spray nozzles (62).

6. The nitrogen reduction device for a dimethyl ether gas boiler burner according to any one of claims 1 to 5, characterized in that: The inner diameters of the outer ring flame spray nozzle (61) and the central flame spray nozzle (62) are 1.5 mm.

7. The nitrogen reduction device for a dimethyl ether gas boiler burner according to claim 6, characterized in that: The inner diameter of the outer shell (1) is 260 mm, and the cyclone mechanism (2) comprises a cyclone blade (21) with a length of 100 mm.

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