CN203036634U - Fractional combustion low-nitrogen oxide rotational flow burner - Google Patents

Abstract

The utility model relates to a low-nitrogen oxide swirl burner with graded combustion, which comprises a central air duct, and a primary air duct, an inner secondary air duct, and an outer secondary air duct are sequentially and concentrically arranged on the outer circumference of the central air duct. Secondary air pipe, a reburning fuel pipe is also provided between the inner secondary air pipe and the outer secondary air pipe, and the reburning fuel pipe includes a front straight section, a middle curved section and a rear straight section, wherein , the front straight section is arranged concentrically with the primary air duct, the inner secondary air duct and the outer secondary air duct, and the middle curved section and the rear straight section are away from the inner secondary air duct Extending in the direction; the inside of the reburning fuel pipe is fed with reburning fuel or tail flue gas, so that the swirl burner forms staged combustion. The utility model can deeply reduce _NOx emissions on the basis of ensuring high efficiency and stable combustion, so as to achieve the optimal combination of benefit and environmental protection. At the same time, the utility model can also be applied to coal-fired power plant boilers in a large scale industry.

Description

A low nitrogen oxide swirl burner with staged combustion

technical field

The utility model relates to a swirl burner for controlling nitrogen oxides (NO _x ) in the combustion process, in particular to a low-nitrogen oxide swirl burner for graded combustion.

Background technique

The acid pollutant gases discharged from coal-fired power plant boilers mainly include SO _x , NO _x and CO ₂ . With the development of China's economy and technology and the improvement of environmental protection requirements, effective control of _NOx emissions from coal-fired power plant boilers not only has significant environmental benefits, but also has significant economic and social benefits, and is currently an urgent problem to be solved One of the environmental problems.

From the perspective of technology and economy, low _NOx combustion technology has always been the most widely used measure to control _NOx emissions from coal-fired boilers. It is still necessary to use low NO _x combustion technology to reduce the NO _x concentration at the inlet of the flue gas purification device, so as to achieve the purpose of saving operating costs.

Existing low NO _x combustion technologies mainly include: low excess air combustion technology, air staged combustion technology, fuel staged combustion technology, flue gas recirculation technology, low NO _x burner technology, etc. In the above-mentioned low-nitrogen combustion technology, the effect of fuel reburning to reduce NO _x is more obvious. The reburning fuel in the reburning process can be gas (natural gas, coal gas), liquid (coal water slurry, oil) or solid (coal powder, biomass fuel) and other fuels. Where conditions permit, different fuels can be used as the reburning fuel, which can greatly reduce the operation and transformation costs of the reburning technology. However, setting the reburning nozzle on the boiler will undoubtedly increase a lot of related equipment, and the operating cost will also increase thereupon.

Flue gas recirculation, mainly extracts part of the flue gas from the air preheater, directly sends it into the furnace or mixes it with primary and secondary air and then enters the furnace through the burner to reduce the oxygen concentration of the furnace and lower the temperature of the furnace, thereby reducing the emission of NO _x and effectively To prevent slagging, but the circulation rate of flue gas recirculation has a great influence on the stability of combustion, and the adjustment is also very difficult.

Because the low NO _x burner has the advantages of mature technology, simple application, low investment cost and no increase in operating costs, it has the advantages of being able to combine the above-mentioned low NO _x technical principles, so it is generally used as a method for reducing NO _x emissions from coal-fired boilers. The technology of choice is also widely used in coal-fired utility boilers. Many literatures show that low _NOx burner technology has great advantages compared with other independent _NOx control technologies in terms of denitrification efficiency, investment cost, operating cost, and technology maturity.

At present, with the strict control of NO _x in China, the application of low NO _x burners is becoming more and more extensive, but the existing low nitrogen burners have limited control of NO _x , which is far inferior to boiler fuel reburning and air three-dimensional classification or flue gas recirculation, but there are still many problems in the application of the existing boiler fuel reburning and air stereo classification or flue gas recirculation, and now many power plants are eager to have a boiler fuel reburning, air stereo classification or flue gas recirculation It is a low NO _x pulverized coal burner with gas recirculation function, simple system, easy operation, flexible adjustment, and can reduce NO _x emissions.

Utility model content

The purpose of the utility model is to propose a practical, efficient, economical low-nitrogen oxide swirl burner that can adapt to different reburning fuels or smoke.

In order to achieve the above purpose, the utility model provides a low-nitrogen oxide swirl burner with staged combustion, which includes a central air pipe, and a primary air pipe, an inner secondary The secondary air duct and the outer secondary air duct are provided with a reburning fuel pipe between the inner secondary air duct and the outer secondary air duct. The reburning fuel pipe includes a front straight section, a middle curved section and a rear straight section, wherein, the front straight section is concentrically arranged with the primary air duct, the inner secondary air duct and the outer secondary air duct, and the middle curved section and the rear straight section are away from the The inner secondary air pipe extends in the direction; the reburning fuel pipe is fed with reburning fuel or tail flue gas to make the swirl burner form staged combustion.

Preferably, an inner secondary air wind box is provided outside the inner secondary air pipe, and the inner secondary air wind box is installed inside the middle bending section of the reburning fuel pipe.

Preferably, the reburning fuel pipe is also provided with a Y-shaped three-way pipe at least partially, the first end of the three-way pipe communicates with the reburning fuel pipe, and the second end of the three-way pipe is connected to the reburning fuel pipe through secondary air. The air pipe communicates with the secondary air wind box of the burner, and the third end of the three-way pipe communicates with the reburning fuel supply source, and valves are provided at the second end and the third end.

Preferably, the valves at the second end and the third end are alternately opened and closed to realize switching between reburning combustion and staged combustion.

Preferably, the reburning fuel pipe is fed with reburning fuel or smoke, and the carrier gas carrying the reburning fuel is air or smoke.

Preferably, the reburning fuel includes natural gas, fine coal powder or biomass, or a mixture of any of them.

Based on the above-mentioned technical scheme, the utility model has the advantages of:

The low-nitrogen oxide swirl burner of the utility model can adapt to different reburning fuels or flue gas, and can control the air volume of the secondary air box entering the air duct where the reburning fuel is located according to different reburning materials or flue gas ratios, so that Combustion is stable. The utility model can deeply reduce _NOx emissions on the basis of ensuring high efficiency and stable combustion, so as to achieve the optimal combination of benefits and environmental protection, and provide a good foundation for flue gas denitrification technology. At the same time, the utility model can also be used in large-scale industries Coal-fired power station boiler.

Description of drawings

The drawings described here are used to provide a further understanding of the utility model and constitute a part of the application. The schematic embodiments of the utility model and their descriptions are used to explain the utility model and do not constitute improper limitations to the utility model. In the attached picture:

Fig. 1 is the side sectional schematic diagram of the swirl burner of the present utility model;

Fig. 2 is the partial rear view schematic diagram of swirl burner of the present utility model;

Fig. 3 is a cross-sectional view of the adjustment mechanism of the bellows baffle of the utility model.

Detailed ways

The technical solutions of the present utility model will be further described in detail through the drawings and embodiments below.

Referring to Fig. 1～Fig. 3, wherein show the preferred embodiment of a kind of low nitrogen oxide swirl burner of staged combustion of the present utility model, the low nitrogen oxide swirl burner of the present utility model comprises central air pipe 13, in A primary air duct 3, an inner secondary air duct 4, and an outer secondary air duct 7 are concentrically arranged on the outer circumference of the central air duct 13 from the inside to the outside. There is also a reburning fuel pipe 5 between them, and the reburning fuel pipe 5 includes a front straight section, a middle curved section and a rear straight section, wherein the front straight section is connected to the primary air duct 3, The inner secondary air duct 4 and the outer secondary air duct 7 are arranged concentrically, as shown in Figure 1 and Figure 2; the middle curved section and the rear straight section extend away from the inner secondary air duct 4 , an installation space is formed between the middle curved section, the rear straight section and the inner secondary air duct 4, preferably, the inner secondary air bellows 11 on the outside of the inner secondary air duct 4 are at least partially arranged in the installation space ; The inside of the reburning fuel pipe 5 is fed with reburning fuel or tail gas, so that the swirl burner forms staged combustion.

Preferably, the reburning fuel pipe 5 is also provided with at least a partially Y-shaped three-way pipe, the first end of the three-way pipe communicates with the reburning fuel pipe 5 and directly leads to the combustion area, and the three-way pipe The second end 1 is connected to the secondary air wind box of the burner through the secondary air connecting air pipe 2. The secondary air wind box of the burner can be the large wind box on the left and right sides of the boiler; the third end of the three-way pipe 15 communicates with the reburning fuel supply source, and a valve 14 is provided at both the second end 1 and the third end 15 .

In the process of actual work, the valves 14 at the second end 1 and the third end 15 are alternately opened and closed to realize switching between reburning combustion and staged combustion. The valve 14 of the present utility model must be a valve that can be closed. , especially when feeding natural gas, the natural gas cannot be allowed to run into the secondary air connecting air pipe 2, of course, a single valve 14 can also adjust the air volume.

When the inside of the reburning fuel pipe 5 passes through the third end 15 to pass the reburning fuel or exhaust gas, the swirl burner can form staged combustion.

And when the inside of the reburning fuel pipe 5 passes through the second end 1 into the secondary air to connect to the secondary air in the air pipe 2 and there is no reburning fuel, a layer of straight air is introduced to isolate the pulverized coal from the external secondary air. The effect of the rapid mixing of the wind. This enables switching between reburning and staging techniques.

As shown in FIG. 1 , the internal secondary air box 11 usually provided by the burner is installed inside the middle curved section of the reburning fuel pipe 5 . Further, the inner secondary air bellows 11 is provided with an air inlet, and the air inlet is provided with a bellows baffle adjustment mechanism.

The above bellows baffle adjustment mechanism includes a bellows baffle 12 , a pull rod 13 and a gland nut 14 , the bellows baffle 12 and the pull rod 13 are connected by a nut, and the gland nut 14 is sleeved on the pull rod 13 .

When the utility model works, the reburning fuel or flue gas is passed into the reburning fuel pipe 5 to realize staged combustion. Wherein, the reburning fuel includes natural gas, fine coal powder or biomass, or a mixture of any of them.

The central air in the central air duct 13 of the utility model can be direct current, and the central air sent by the central air duct 13 is not used when the burner is in normal load operation, but is mainly used to provide the air required for oil combustion when the burner is ignited, Cool the oil gun and burner when the oil gun is withdrawn and the furnace is shut down, and supplement the required oxygen amount at low load. The arrangement of the central air duct 13 is conducive to the formation of the central recirculation zone, and increases the contact heating of the air powder airflow and the high-temperature flue gas around the periphery, which is beneficial to the ignition and combustion stability of the coal powder.

In addition, swirl blades 6 are preferably installed in the primary air duct 3 of the utility model, which can improve the uneven distribution of pulverized coal in the circumferential direction. The primary air outlet of the burner is also provided with a flame stabilizer 10, as shown in Figure 1, which can improve the distribution of pulverized coal at the primary air outlet, and is conducive to the stability of pulverized coal ignition.

Further, in this embodiment, the rear part of the primary air duct 3 is provided with an air inlet elbow, as shown in Figure 1, and combined with the swirl vanes 6, it can effectively improve or avoid the problem of uneven distribution of pulverized coal in the circumferential direction. At the same time, it can also increase the disturbance and mixing of pulverized coal particles and high-temperature flue gas, which is conducive to rapid combustion. The wind rate of the primary air is generally 16%~24%; the outlet of the primary air duct 3 of the burner is equipped with a flame stabilizer 10. It can improve the distribution of pulverized coal at the primary air outlet, which is conducive to the stability of pulverized coal ignition.

The air inlets of the inner secondary air duct 4 and the outer secondary air duct 7 described in the utility model are all provided with swirl blades. The selection can be adjusted by adjusting the swirl blades, so that the outer secondary air pipe 7 and the inner secondary air pipe 4 can generate direct current or secondary air with variable swirl intensity.

The reburning fuel pipe 5 described in the utility model can be direct current or swirling flow, and can also be used to feed reburning fuel or flue gas according to the actual situation of the power plant, so as to realize the staged combustion of fuel or air well, and the reburning flow The fuel can be various fuels such as gas (natural gas, coal gas), liquid (coal water slurry, oil) or solid (powdered coal, biomass fuel); the flue gas introduced can also be the flue gas drawn from the tail of the boiler, Or it could be a gas with a higher CO ₂ /O ₂ ratio obtained from other external sources.

In addition, the outlet ends of the inner secondary air pipe 4, the reburning fuel pipe 5, and the outer secondary air pipe 7 are all provided with a conical expansion angle 9, as shown in Figure 1, the above-mentioned conical expansion angle 9 at the outlet end has a certain effect on the airflow. The degree of diversion, increasing the flaring angle can widen the recirculation zone and increase the contact area between the recirculation zone and the high-temperature flue gas. The expansion angle of the conical expansion angle 9 is 5-45°

The air inlets of the inner secondary air duct 4 and the outer secondary air duct 7 are equipped with swirl blades, the number of blades with swirl strength is 0-40, and the angle between the swirl blades and the axis of the burner is 5-85° .

The inner secondary air pipe 4 is externally connected with an inner secondary air bellows 11, and the middle part of the inner secondary air bellows 11 is provided with a plurality of air inlets (the air inlets are preferably rectangular, but of course other shapes are also possible). The secondary air bellows 11 are evenly distributed, and the number is 4 to 10. The inner secondary air bellows 11 and the reburning fuel pipe 5 are provided with a bellows baffle adjustment mechanism. It is composed of a gland nut 14, as shown in Figure 3; the bellows baffle 12 is connected to the pull rod 13 through a nut, and the gland nut 14 is sleeved on the pull rod. The bellows baffle 12 is adjusted in position by a pull rod 13, and finally locked in its position with a gland nut 14. The bellows baffle 12 is a sleeve around the outer diameter of the bellows, the sleeve is equipped with a runner, and the position of the sleeve is regulated by a pull rod 13 . The axial length of the sleeve is 4/3 of the length of the rectangular hole on the bellows. The air volume entering the inner secondary air pipe 4 , the reburning fuel pipe 5 and the outer secondary air pipe 7 is adjusted by adjusting the air box baffle adjusting mechanism 12 .

When the bellows baffle 12 fully covers the rectangular air inlet, the air intake is the least, and the air intake is the largest when the bellows baffle 12 leaves the rectangular air inlet completely. After bellows baffle plate 12 positions are set, lock on its position with gland nut 14 at last. While adjusting the air volume of each air duct, the swirl intensity of the secondary air entering the air duct can not be affected by adjusting the swirl adjustment mechanism. The wind rate of the inner secondary air is generally 12-13%; the wind rate of the middle secondary air is 15-27%; the wind rate of the outer secondary air is 30-45%.

The utility model provides a set of practical, efficient and economical low _NOx swirl burner, the denitrification efficiency of which can reach more than 50%. The utility model also has the following characteristics:

1) A reburning fuel pipe for feeding reburning fuel or tail flue gas is set between the inner secondary air and the outer secondary air in the secondary air box, which can achieve a combustion effect similar to boiler fuel reburning or flue gas recirculation.

2) According to the coal quality of the utility model, when the coal quality is good and the _NOx is low, the fuel-burning pipe may not pass into the reburning fuel, but pass into air to realize staged combustion.

3) The staged combustion formed by the swirl burner of the utility model is obviously strengthened, so that the fuel-type NO _x is greatly reduced.

4) By adjusting the adjustment mechanism of the bellows baffle, the air volume of the inner secondary air pipe, the reburning fuel pipe and the outer secondary air pipe can be adjusted, so as to adapt to the change of coal type and load. The adjustment of the air volume of each air duct may not affect the swirl strength of the air duct.

5) The reburning fuel of the present utility model has a wide range of applications, including various fuels such as gas (natural gas, coal gas), liquid (coal water slurry, oil) or solid (coal powder, biomass fuel), and the flue gas introduced can be The flue gas drawn from the tail of the boiler can also be a gas with a higher ratio of CO ₂ /O ₂ obtained from other places.

6) The carrier gas carrying the reburning fuel can be air, flue gas, or other gases.

7) Fuel reburning or flue gas recirculation can be realized only by the burner, which is different from boiler reburning and requires additional equipment. Therefore, the utility model reduces a lot of costs.

The structure of the utility model better realizes the fuel classification technology and the air classification technology of the low _NOx swirl burner, so as to meet the needs of stabilizing different coal types and reduce the generation of _NOx to the greatest extent.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present utility model and not limit it; although the utility model has been described in detail with reference to the preferred embodiment, those of ordinary skill in the art should understand that: still The specific implementation of the utility model can be modified or some technical features can be equivalently replaced; without departing from the spirit of the technical solution of the utility model, all of them should be included in the scope of the technical solution claimed by the utility model.

Claims (5)

1. the low nox swirling burner of a fractional combustion, comprise central air hose (13), periphery at described central air hose (13) is provided with an airduct (3) from inside to outside successively with one heart, interior secondary air channel (4), outer secondary air channel (7), it is characterized in that: secondary air channel in described (4) and outside also be provided with reburning fuel pipe (5) between the secondary air channel (7), described reburning fuel pipe (5) comprises anterior flat segments, middle bent section and rear portion flat segments, wherein, described anterior flat segments and a described airduct (3), interior secondary air channel (4) and outer secondary air channel (7) are concentric setting, and described middle bent section and rear portion flat segments are extended to the direction away from secondary air channel (4) in described; Inner reburning fuel or the tail flue gas of feeding of described reburning fuel pipe (5) makes turbulent burner form fractional combustion.

2. low nox swirling burner according to claim 1, it is characterized in that: secondary wind bellows (11) in secondary air channel (4) outside is provided with in described, described interior secondary wind bellows (11) are installed in the middle bent section inboard of described reburning fuel pipe (5).

3. low nox swirling burner according to claim 1, it is characterized in that: also be provided with the local at least three-way pipeline that is the Y type on the described reburning fuel pipe (5), first end of described three-way pipeline is connected with reburning fuel pipe (5), second end (1) of three-way pipeline connects airduct (2) by secondary wind and is connected with the big bellows of secondary wind of burner, the 3rd end (15) of three-way pipeline is connected with the reburning fuel supply source, and locates to be equipped with valve (14) at described second end (1) and the 3rd end (15).

4. low nox swirling burner according to claim 3 is characterized in that: the valve (14) that described second end (1) and the 3rd end (15) are located alternately opens and closes, and realizes the switching between reburning and the fractional combustion.

5. low nox swirling burner according to claim 1 is characterized in that: feed reburning fuel or flue gas in the described reburning fuel pipe (5), the carrier gas of carrying described reburning fuel is air or flue gas.

Images