CN205897117U - Air pulverized coal front and back wall opposed firing ware is joined in marriage to non - equalling - Google Patents

Abstract

The utility model discloses a non-uniform air distribution pulverized coal front and rear wall confrontation burner. The utility model comprises burners on both sides, a middle burner and a secondary middle burner. The burner structure includes a secondary air channel, a secondary air damper, and a primary air channel. The flow area of the secondary air channel and the secondary air door of the burner decreases from both sides to the middle. Under the same opening degree of the secondary air damper, the secondary air flow rate decreases from both sides to the middle. Under unequal flow control, the outlet wind speeds of the corresponding channels of all burners are basically the same. The specific design parameters of the secondary air channel and the secondary air damper are determined according to the burner structure and arrangement of different boilers. In the utility model, under the same opening degree of the secondary air damper of the burner on the same floor, the wind coal is reasonably matched in the combustion process, the oxygen amount is evenly distributed after combustion, and the CO emission concentration is effectively reduced. At the same time, it also has a significant effect on preventing high-temperature corrosion and slagging of the water wall on both sides of the boiler.

Description

Non-equal air distribution pulverized coal front and rear wall opposite burner

technical field

The utility model belongs to the technical field of energy saving and emission reduction, and relates to a burner opposed to the front and rear walls of pulverized coal with non-uniform wind distribution.

Background technique

Hedging combustion of the front and rear walls of pulverized coal is one of the main combustion technologies of large-scale power plant boilers. Theoretically, it has the advantages of uniform flow field in the furnace, relatively uniform heat load distribution on the furnace section, no residual torsion of the flue gas at the furnace outlet, and small flue temperature deviation. . Compared with the four-corner tangential combustion, the opposite combustion of the front and rear walls uses a single burner as a unit to independently organize the combustion of the air powder flow. When the boiler capacity increases, the boiler only needs to increase the furnace width and the number of burners on each layer. The flow field in the furnace, the heat load distribution on the furnace section, and the deviation of the flue gas temperature at the furnace outlet have nothing to do with the size of the boiler capacity. Therefore, the front and rear wall opposing combustion has been widely used in units with a capacity of 600MW and above.

Practice has proved that there are common problems such as high CO emission concentration, serious high-temperature corrosion tendency at the center of the walls on both sides of the furnace, and high combustion NOx concentration in the hedging combustion of the front and rear walls. According to the test, the CO distribution at the tail of the boiler is high on both sides and low in the middle, and the oxygen distribution is low on both sides and high in the middle, indicating that there is oxygen deficiency on both sides of the furnace during the combustion process in the furnace.

In order to reduce the concentration of CO emissions, most units adopt the method of "bowl-type air distribution", that is, the opening of the damper of the middle burner is smaller than that of the burners on both sides, so as to increase the air supply on both sides while the total air volume remains unchanged. But the actual effect is not outstanding. The characteristic test of the burner damper of a Dongguo 600MW boiler shows that when the opening of the burner damper is greater than 50%, there is almost no adjustment effect on the air volume, and the air volume adjustment effect will be obvious when it is less than 30%. The actual operation of the furnace adopts "bowl-type air distribution", and the minimum opening of the middle damper is more than 40%, so the real "bowl-type air distribution" has not been realized in fact. The adjustment test shows that when the damper opening of the intermediate burner reaches 15-20%, the distribution of CO concentration at the tail of the boiler tends to be uniform, and the CO emission concentration is significantly reduced. It brings certain difficulties and potential safety hazards to the operation. For tangential vane swirl burners, the damper is also a swirl vane. Although the opening of the damper is too small, the air volume is reduced, but the swirl intensity is also greatly increased, making it difficult to reasonably match the air volume and swirl intensity.

In addition, after adopting an effective "bowl-type air distribution", under the condition that the structure of the burner remains unchanged, the outlet wind speed of the intermediate burner is obviously reduced, which will have an adverse effect on the reasonable organization of air distribution.

Contents of the invention

In order to solve the problem of high CO emission concentration of boiler combustion involved in the background technology, the utility model provides a non-uniform air distribution pulverized coal front and rear wall opposite burner, which can effectively reduce the fundamental goal of CO emission concentration while achieving The burner air door can be adjusted at the same level without affecting the effective air distribution of the burner.

The technical solution adopted by the utility model to solve its technical problems:

The utility model comprises burners on both sides and a middle burner. The burner structure includes a secondary air channel, a secondary air damper, and a primary air channel.

There may be multiple secondary intermediate burners between the side burners and the intermediate burners (according to different boiler structures, this part has no or more);

The primary air channel flow area of all burners is kept equal.

When there is a sub-intermediate burner, the flow areas of the secondary air passages of the two side burners, the sub-intermediate burner, and the intermediate burner and the secondary air damper decrease successively (from both sides to the middle).

When there are two sub-intermediate burners, the flow areas of the secondary air channels and the secondary air dampers of the two side burners, the sub-intermediate burner I, the sub-intermediate burner II, and the intermediate burner decrease in sequence (by sides to middle).

When there are multiple secondary intermediate burners, the change law of the flow area of the secondary air channel and the secondary air damper can be deduced by analogy.

The circulation area of the secondary air channel: the middle burner is 60% to 80% of the two side burners, and the secondary middle burner is 70% to 90% of the two side burners.

The circulation area of the secondary air damper: the middle burner is 40% to 80% of the burners on both sides, and the secondary middle burner is 40% to 90% of the burners on both sides.

The design principle of the flow area of the secondary air damper is that the adjustment characteristics of the secondary air dampers of all burners are basically the same. That is, under the same opening degree, the secondary air flow control target is realized: the middle burner is 60% to 80% of the burners on both sides, and the secondary middle burner is 70% to 90% of the burners on both sides.

The design principle of the outlet area of the secondary air passage is: under the control target of the secondary air flow, the outlet wind speeds of the corresponding passages of all burners are basically the same. The flow area and outlet area of the secondary air channels can vary.

The specific design parameters of the secondary air channel and the secondary air damper are determined according to the burner structure and arrangement of different boilers.

The beneficial effects of the utility model are:

Under the equal operation of the secondary air dampers of all burners on the same floor, the secondary air volume of the burner decreases from both sides to the middle, and the burner distributes the air unevenly, and does not significantly affect the airflow structure at the burner outlet, realizing the wind in the combustion process The coal is reasonably matched, and the oxygen content and CO concentration after combustion are evenly distributed, so as to effectively reduce the CO emission concentration. At the same time, it also has a significant effect on preventing high-temperature corrosion and slagging of the water wall on both sides of the boiler.

Description of drawings

Fig. 1 is a schematic diagram of arrangement of 6 burners on each floor of the utility model,

Fig. 2 is a schematic diagram of arrangement of 4 burners on each floor of the utility model,

Fig. 3 is a schematic structural view of the burner of the present invention.

In the figure, 1. Burners on both sides; 2. Middle burner; 3. Secondary middle burner; 4. Secondary air channel; 5. Secondary air damper; 6. Primary air channel.

detailed description

Below in conjunction with accompanying drawing, the utility model is further described.

As shown in Fig. 1, Fig. 2 and Fig. 3, a non-uniform air distribution pulverized coal front and rear wall opposite burner includes burners 1 on both sides and a burner 2 in the middle, and each burner is provided with a secondary air channel 4 , Secondary air damper 5, Primary air channel 6.

As shown in Figure 2, there may be multiple secondary intermediate burners 3 between the side burners 1 and the intermediate burner 2 (according to different boiler structures, there may be no or more secondary burners in this part).

The flow areas of the primary air channels 6 of all the burners are kept equal.

When there is a sub-intermediate burner, the flow area of the secondary air channel and the secondary air damper of the two side burners 1, the sub-intermediate burner 3, and the intermediate burner 2 decreases in turn (from both sides to the middle) .

When there are two sub-intermediate burners, the flow areas of the secondary air channels and secondary air dampers of the side burners 1, sub-intermediate burner I3, sub-intermediate burner II3, and intermediate burner 2 decrease sequentially (from both sides to the middle).

When there are multiple secondary intermediate burners, the change law of the flow area of the secondary air channel and the secondary air damper can be deduced by analogy.

The flow area of the secondary air channel 4: the middle burner 2 is 60%-80% of the two-side burner 1, and the secondary middle burner 3 is 70%-90% of the two-side burner 1. When there are multiple sub-intermediate burners 3, the multiple sub-intermediate burners 3 all meet 70%-90%. Only the circulation area of the secondary air channel and the secondary air damper decreases sequentially from both sides to the middle.

The flow area of the secondary air damper 5: the middle burner 2 is 40% to 80% of the two side burners 1, and the secondary middle burner 3 is 40% to 90% of the two side burners 1. When there are multiple sub-intermediate burners 3, the multiple sub-intermediate burners 3 all meet 40%-90%. Only the circulation area of the secondary air channel and the secondary air damper decreases sequentially from both sides to the middle.

The design principle of the flow area of the secondary air damper 5 is that the adjustment characteristics of the secondary air damper 5 of all burners are basically the same. That is, under the same opening degree, the secondary air flow control target is realized: the middle burner 2 is 60% to 80% of the side burners 1, and the secondary middle burner 3 is 70% to 90% of the side burners 1.

The design principle of the outlet area of the secondary air passage 4 is: under the secondary air flow control target, the outlet wind speeds of the corresponding passages of all burners are basically the same. The circulation area and the outlet area of the secondary air channel 4 can be different.

The specific design parameters of the secondary air channel 4 and the secondary air damper 5 are determined according to the burner structure and arrangement of different boilers.

Claims (4)

1. non-uniform air distribution coal dust opposed firing burner, it is characterised in that including both sides burner and intermediate combustion device, fires Burner structure includes secondary air channel, secondary wind air door, First air passage；

The First air channel cross-sectional flow area of all burners keeps equal；

Described both sides burner, the secondary air channel of intermediate combustion device and secondary wind air door circulation area by both sides to middle according to Secondary reduction；

The circulation area of described secondary air channel: intermediate combustion device is the 60%～80% of both sides burner；

The circulation area of described secondary wind air door: intermediate combustion device is the 40%～80% of both sides burner；

The control characteristic of the secondary wind air door of all burners is consistent；I.e. under identical aperture, realize secondary air flow and control mesh Mark: intermediate combustion device is the 60%～80% of both sides burner；

Under secondary air flow control targe, the air outlet velocity of the respective channel of all burners is consistent；The stream of secondary air channel Logical area and discharge area allow difference；

Described secondary air channel, the specific design parameter of secondary wind air door are come with arrangement according to the burner structure of different boilers Determine.

2. non-uniform air distribution coal dust opposed firing burner according to claim 1 is it is characterised in that burn in both sides It is provided with 1 or multiple intermediate combustion devices between device and intermediate combustion device.

3. non-uniform air distribution coal dust opposed firing burner according to claim 2 is it is characterised in that at described time Intermediate combustion device keeps equal with the First air channel cross-sectional flow area of both sides burner, intermediate combustion device.

4. non-uniform air distribution coal dust opposed firing burner according to claim 3 is it is characterised in that when presence one During individual intermediate combustion device, described both sides burner, secondary intermediate combustion device, the secondary air channel of intermediate combustion device and secondary wind Air door circulation area is sequentially reduced to centre by both sides；

The circulation area of described secondary air channel: secondary intermediate combustion device is the 70%～90% of both sides burner；

The circulation area of described secondary wind air door: secondary intermediate combustion device is the 40%～90% of both sides burner；

The design principle of the described circulation area of secondary wind air door is: the control characteristic base of the secondary wind air door of all burners This is consistent；I.e. under identical aperture, realize secondary air flow control targe: secondary intermediate combustion device be both sides burner 70%～ 90%；

The design principle of the discharge area of described secondary air channel is: under secondary air flow control targe, all burners Respective channel air outlet velocity consistent；The circulation area of secondary air channel and discharge area allow difference；

Described secondary air channel, the specific design parameter of secondary wind air door are come with arrangement according to the burner structure of different boilers Determine.