CN110375300A - A kind of burner of low-nitrogen oxide discharging - Google Patents

Abstract

A burner with low nitrogen oxide emissions, comprising a central fuel passage, a first combustion-supporting air passage is arranged around the outer circumference of the central fuel passage, a first circulating flue gas passage is arranged around the outer circumference of the first combustion-supporting air passage, and A second combustion-supporting air channel is provided in the outer circumferential direction of the first circulating flue gas channel, a second circulating flue gas channel is provided around the outer circumferential direction of the second combustion-supporting air channel, and a third circulation is provided around the outer circumferential direction of the second circulating flue gas channel Flue gas channel; on the one hand, the circulating flue gas is actively mixed with the fuel, and on the other hand, the circulating flue gas is actively mixed with the combustion-supporting air, and the fuel concentration and the oxygen concentration of the combustion-supporting air are diluted to inhibit the combustion speed of the fuel in the boiler and the concentrated emission. heat, thereby lowering the combustion temperature and reducing the amount of NO _x produced.

Description

A burner with low nitrogen oxide emission

technical field

The invention belongs to the technical field of environment-friendly combustion, and in particular relates to a combustion engine with low nitrogen oxide emission.

burner.

Background technique

In recent years, the emissions of nitrogen oxides from energy-related sectors in my country have risen rapidly. In 2000, the national nitrogen oxide emissions were 12.1X106t, and by 2005 it had increased to 19.1X106t, with an average annual growth rate of 10%. If no further emission reduction measures are taken, with the economic development of the United States, population growth and the acceleration of urbanization, my country's nitrogen oxide emissions will continue to grow in the future. According to the current development trend, the emissions will reach 35.4X106t, will inevitably cause serious environmental impact, therefore, must effectively strengthen the control of nitrogen oxide emissions.

Natural gas is a well-known clean fuel, but the emission of NO _x produced by the combustion of natural gas is large, and NO _x is the most important pollutant of natural gas boilers. At present, my country's environmental protection department has higher and higher requirements on the discharge of pollutants produced by coal pulverized combustion. For this reason, reducing the emission of nitrogen oxides is one of the main goals in the design of the combustion system of pulverized coal boilers.

For gas-fired boilers without any low-nitrogen measures, NOx emissions are as high as 600~800mg/Nm ³ , and existing low-nitrogen gas burners can achieve _NOx <200mg/Nm ³ . With the flue gas recirculation measures outside the furnace, the existing gas-fired boilers can generally achieve _NOx emissions <80mg. However, there is still room for further reduction of this value.

In order to reduce the emission of nitrogen oxides, on the one hand, in the boiler design, try to reduce the temperature in the furnace and reduce the possible high temperature areas, especially the local high temperature areas caused by changes in the flow field. It is necessary to have a relatively uniform combustion area to ensure the combustion of the fuel and reduce the maximum temperature of the flame. On the other hand, fuel-type NO _X decreases with the reduction of the excess air ratio. Fuel-type NO _X is closely related to the pyrolysis products of the fuel and the oxygen concentration in the flame. If there is a lack of oxygen in the combustion center of the main combustion zone, most of the Volatile nitrogen and part of coke N are converted into N ₂ , thereby reducing NO _x in the flue gas.

There are following deficiencies in the combustion system in the prior art:

At present, the flue gas recirculation method that has been widely used in boiler combustion systems mostly uses external or internal fans to pump low-temperature circulating flue gas into the combustion chamber flame to participate in combustion. However, due to burner design problems, the recirculation of flue gas and combustion The air flow is unevenly mixed, which cannot effectively reduce the temperature in the furnace, and the flue gas stays in the furnace for a short time.

Contents of the invention

The present invention designs the layout of the fuel channel, circulating smoke channel and combustion-supporting air channel inside the burner. On the one hand, the combustion-supporting air channel is surrounded by circulating smoke, and the circulating smoke is mixed with the combustion-supporting air to reduce the oxygen content of the combustion-supporting air. Reducing the excess air ratio and burning the fuel in a reducing atmosphere of α<1 can greatly reduce the NO _x in the flue gas. On the other hand _{, the} fuel channel is surrounded by circulating flue gas, and the circulating flue gas is mixed with fuel to reduce the ignition temperature. As the temperature decreases, the generation of thermal _NOx also decreases.

For realizing above object, the technical scheme that the present invention adopts is as follows:

A burner with low nitrogen oxide emissions, comprising a central fuel passage, a first combustion-supporting air passage is arranged around the outer circumference of the central fuel passage, a first circulating flue gas passage is arranged around the outer circumference of the first combustion-supporting air passage, and A second combustion-supporting air channel is provided in the outer circumferential direction of the first circulating flue gas channel, a second circulating flue gas channel is provided around the outer circumferential direction of the second combustion-supporting air channel, and a third circulation is provided around the outer circumferential direction of the second circulating flue gas channel flue gas channel;

A first series of fuel spray guns is arranged in the first circulating flue gas passage, and a second series of fuel spray guns is arranged in the third circulating flue gas passage.

Further, the central fuel passage, the first combustion-supporting air passage, the first circulating flue gas passage, the second combustion-supporting air passage, the second circulating flue gas passage, the third circulating flue gas passage, the first series of fuel spray guns, the second series of fuel The outlets of the spray guns are on the same plane.

Further, the central fuel channel is a metal pipe, and an electric regulating valve is installed at the entrance of the central fuel channel, and the fuel at the outlet can be kept burning as an ever-burning lamp to ensure that the furnace flame is not extinguished.

Further, the cross-section of the first combustion-supporting air channel is a circle centered on the central fuel channel, the inlet of the first combustion-supporting air channel is connected to the combustion-supporting air source, and the outlet is provided with a mixing wind wheel.

The cross-section of the first circulating flue gas channel is a ring with the central fuel channel as the center, and the first series of fuel spray guns are arranged equidistantly along the direction of the ring in the first circulating flue gas channel, and the inlet of the first circulating flue gas channel Connect the flue gas recirculation.

Further, the cross-section of the second combustion-supporting air passage is a circle centered on the central fuel passage, the inlet of the second combustion-supporting air passage is connected to the combustion-supporting air source, and the outlet is provided with a mixing wind wheel.

Further, the cross-section of the second circulating flue gas channel is a circle centered on the central fuel channel, and the inlet of the second circulating flue gas channel is connected to the circulating flue gas.

Further, the cross-section of the third circulating flue gas channel is a ring centered on the central fuel channel, and a second series of fuel spray guns are arranged equidistantly along the direction of the ring in the third circulating flue gas channel, and the third circulating flue gas The inlet of the channel is connected to the circulating flue gas.

Preferably, the first series of fuel spray guns are composed of circular tubes with equal cross-sections, and the inlets of each spray gun are connected to fuel sources.

Preferably, the second series of fuel spray guns are composed of circular pipes with equal cross-sections, and the inlets of each spray gun are connected to fuel sources.

The beneficial effects of the present invention are as follows:

The interior of the burner is designed with multiple diversion channels for circulating flue gas. On the one hand, the circulating flue gas actively mixes with the fuel; The combustion speed and concentrated heat release of fuel in the boiler can reduce the combustion temperature and reduce the amount of NOx generated.

The circulating flue gas is an independent channel, which does not affect the combustion-supporting air channel. The resistance of the burner is small, and the energy consumption of the required combustion-supporting air supply fan is small.

Description of drawings

Fig. 1 is a schematic cross-sectional view of a burner with low nitrogen oxide emissions;

In the figure,

1. Central fuel channel, 2. First combustion-supporting air channel, 3. First circulating flue gas channel, 4. Second combustion-supporting air channel, 5. Second circulating flue gas channel, 6. Third circulating flue gas channel, 7 . The first series of fuel spray guns, 8. The second series of fuel spray guns.

Detailed ways

Embodiments of the present invention will be further described below in conjunction with the accompanying drawings.

Example 1

Referring to Fig. 1, a burner with low nitrogen oxide emission includes a central fuel channel 1, and a first combustion-supporting air channel 2 is arranged around the outer circumference of the central fuel channel, and the first combustion-supporting air channel 2 is centered on the central fuel channel The inlet is connected to the combustion-supporting air source, and the outlet is provided with a mixing wind wheel; the first circulating flue gas channel 3 is arranged around the outer circumference of the first combustion-supporting air channel 2, and the cross section of the first circulating flue gas channel 3 is centered The fuel channel is a ring at the center of the circle, and a first series of fuel spray guns 7 are equidistantly arranged along the direction of the ring in the first circulating flue gas channel 3 , and the inlet of the first circulating flue gas channel 3 is connected to the circulating flue gas. A second combustion-supporting air channel 4 is provided around the outer circumference of the first circulating flue gas 3 channel. The cross-section of the second combustion-supporting air channel 4 is a ring centered on the central fuel channel. The inlet of the second combustion-supporting air channel 4 is connected to the combustion-supporting air channel. The wind source and the outlet are provided with a mixing wind wheel. A second circulating flue gas passage 5 is provided around the outer circumference of the second combustion air passage 4. The cross section of the second circulating flue gas passage 5 is a ring with the central fuel passage as the center of the circle. The entrance of the second circulating flue gas passage 5 Connect the flue gas recirculation. A third circulating flue gas passage 6 is provided around the outer circumference of the second circulating flue gas passage 5, and the cross section of the third circulating flue gas passage 6 is a ring with the central fuel passage as the center; the third circulating flue gas passage is provided with There is a second series of 8 fuel spray guns.

Central fuel channel 1, first combustion-supporting air channel 2, first circulating flue gas channel 3, second combustion-supporting air channel 4, second circulating flue gas channel 5, third circulating flue gas channel 6, first series of fuel spray guns 7, The outlets of the second series of fuel spray guns 8 are on the same plane.

The central fuel passage 1 is a metal pipe with a diameter of 20 cm. An electric regulating valve is installed at the entrance of the central fuel passage, and the fuel at its outlet can be used as an ever-burning lamp to burn all the time to ensure that the furnace flame does not go out.

The first series of fuel spray guns 7 is composed of 4 to 10 circular pipes with equal cross-sections, the diameter of each spray gun is 0.5 to 5.0 cm, and the inlet of each spray gun is connected to a fuel source.

The second series of fuel spray guns 8 is composed of 8 to 20 circular pipes with equal cross-sections, each spray gun has a diameter of 1.0 to 3.0 cm, and the inlet of each spray gun is connected to a fuel source.

The usage method of the burner with low nitrogen oxide emission will be further illustrated by the following examples.

Example 2

A burner with low nitrogen oxide emission. The combustion-supporting air is introduced to ignite the outlet of the central fuel channel 1 and the outlets of the first and second series of fuel spray guns. By adjusting the electric control valve of the central fuel channel 1, the fuel at the outlet can Always burns as a permanent lamp to ensure that the hearth flame does not go out. The circulation fan absorbs the flue gas in the furnace, and adjusts the flow rate of the circulating flue gas by adjusting the electric control valve on the main flue pipe. The first combustion-supporting air channel 2 is surrounded by the first circulating flue gas channel 3, and the second combustion-supporting air channel 4 is surrounded by the second circulating flue gas channel 5, so that the circulating flue gas is fully mixed with the combustion-supporting air, and the oxygen content of the combustion-supporting air is reduced. The first series of fuel spray guns are set in the first circulating flue, and the second series of fuel spray guns are set in the third circulating flue, so that the circulating flue gas and fuel are fully mixed, and the combustion speed of the fuel is reduced, thereby reducing the temperature.

The application of this technology can save energy consumption, reduce _NOx emission, and achieve _NOx <30mg/Nm ³ under the working condition of hot air temperature ≤250°C. Calculated on the basis of a 25T boiler, the flue gas emission per hour is about 22000Nm ³ ; the existing burner technology can only achieve NO _x emission <80mg Nm ³ when the hot air temperature is ≤ 250°C; the ultra-low nitrogen burner is adopted After that, the NO _x emission is less than 30mgNm ³ ; the NO _x emission is reduced by about 1.1Kg/h, and the annual NO _x emission of a single 25T boiler is reduced by nearly 10 tons.

Claims (10)

1. a kind of burner of low-nitrogen oxide discharging, which is characterized in that including center fuel passage, surround center fuel passage Outer circle circumferential direction is provided with the first combustion air channel, and the first combustion air channel outer circle circumferential direction is provided with first circulation flue gas Channel is provided with the second combustion air channel around first circulation exhaust gases passes outer circle circumferential direction, outside the second combustion air channel Circumferencial direction is provided with second circulation exhaust gases passes, and second circulation exhaust gases passes outer circle circumferential direction is provided with third circulation cigarette Gas channel；

First Series Fuel lance is provided in the first circulation exhaust gases passes, the third circulating flue gas is provided in channel Second series Fuel lance.

2. a kind of burner of low-nitrogen oxide discharging according to claim 1, which is characterized in that the center fuel is logical Road, the first combustion air channel, first circulation exhaust gases passes, the second combustion air channel, second circulation exhaust gases passes, third recycle cigarette Gas channel, First Series Fuel lance, second series Fuel lance outlet in the same plane.

3. a kind of burner of low-nitrogen oxide discharging according to claim 1, which is characterized in that the center fuel is logical Road is a metal tube, and in center fuel passage entrance installation and adjustment valve, outlet fuel can burn always as altar lamp, really Furnace flame is protected not extinguish.

4. a kind of burner of low-nitrogen oxide discharging according to claim 1, which is characterized in that first combustion air The cross section in channel is using center fuel passage as the annulus in the center of circle, and the import in the first combustion air channel connects combustion-supporting wind regime, out Mouth is provided with mixing wind wheel.

5. a kind of burner of low-nitrogen oxide discharging according to claim 1, which is characterized in that first circulation flue gas is logical The cross section in road is to set in first circulation exhaust gases passes along annular direction is equidistant using center fuel passage as the annulus in the center of circle It is equipped with First Series Fuel lance, the import of first circulation exhaust gases passes connects circulating flue gas.

6. a kind of burner of low-nitrogen oxide discharging according to claim 1, which is characterized in that second combustion air The cross section in channel is using center fuel passage as the annulus in the center of circle, and the import in the second combustion air channel connects combustion-supporting wind regime, out Mouth is provided with mixing wind wheel.

7. a kind of burner of low-nitrogen oxide discharging according to claim 1, which is characterized in that the second circulation cigarette The cross section in gas channel is the import connection circulation cigarette of second circulation exhaust gases passes using center fuel passage as the annulus in the center of circle Gas.

8. a kind of burner of low-nitrogen oxide discharging according to claim 1, which is characterized in that the third recycles cigarette The cross section in gas channel be using center fuel passage as the annulus in the center of circle, it is equidistant along annular direction in third circulating flue gas channel From second series Fuel lance is provided with, the import in third circulating flue gas channel connects circulating flue gas.

9. a kind of burner of low-nitrogen oxide discharging according to claim 1, which is characterized in that the First Series combustion Material spray gun is made of the equal-sized round tube in cross section, and each spray gun import connects fuels sources.

10. a kind of burner of low-nitrogen oxide discharging according to claim 1, which is characterized in that the second series The equal-sized round tube composition in Fuel lance cross section, each spray gun import connect fuels sources.