Boiler combustion system with low nitrogen oxide emission

Abstract

The boiler combustion system comprises a boiler, an outer barrel, an inner barrel, a first pulverized coal bunker and a second pulverized coal bunker, the outer barrel is provided with a first port and a second port which are opposite, the first port is communicated with a hearth, the second port is provided with a sealing plate, the sealing plate is provided with a through hole, and the through hole is communicated with the inner barrel. The inner barrel is provided with a third port and a fourth port which are opposite to each other, the third port extends into the outer barrel through the through hole, an annular channel is defined between the inner barrel and the outer barrel, a plurality of pulverized coal holes are formed in the side wall of the inner barrel at intervals, and the pulverized coal holes are communicated with the through hole. The second pulverized coal bunker communicates with the annular channel through a second induced draft fan, and the second induced draft fan is used for conveying pulverized coal discharged by the second pulverized coal bunker into the annular channel. Therefore, the boiler combustion system with the low nitrogen oxide emission has the advantages of being sufficient in blending combustion, low in smoke treatment cost and the like.

Description

Technical Field

[0001] The invention relates to the technical field of boiler combustion, and in particular to a boiler combustion system with low nitrogen oxide emissions. Background Art

[0002] Coal-fired flue gas contains a large amount of nitrogen oxides that affect the environment and human health. SCR denitrification process is usually used for flue gas treatment. In the SCR denitrification process, ammonia or urea solution is sprayed into the flue. Under the action of appropriate temperature and catalyst, ammonia reacts with NOx in the flue gas to convert NOx into harmless nitrogen and water, thereby meeting the environmental protection requirements for flue gas emissions. In related technologies, power plants usually blend coal of different qualities because different types of coal have different combustion temperatures and prices. Blending can not only improve combustion efficiency, but also reduce fuel costs and improve economic benefits. However, due to uneven blending, coal powder is prone to incomplete combustion in the boiler, resulting in an increase in the content of nitrogen oxides in the flue gas. In the subsequent SCR denitrification process, it will lead to an increase in the amount of ammonia sprayed, and there is a problem of high flue gas treatment costs. Summary of the invention

[0003] The present invention aims to solve one of the technical problems in the related art at least to a certain extent. To this end, an embodiment of the present invention provides a boiler combustion system with low nitrogen oxide emissions.

[0004] The boiler combustion system with low nitrogen oxide emission in the embodiment of the present invention comprises a boiler, an outer cylinder, an inner cylinder, a first pulverized coal bin and a second pulverized coal bin. The boiler comprises a furnace and a flue; the outer cylinder has a first port and a second port opposite to each other, the first port is connected to the furnace, the second port is provided with a sealing plate, and the sealing plate is provided with a perforation;

[0005] The inner cylinder has a third port and a fourth port opposite to each other, the third port extends into the outer cylinder through the through hole, an annular channel is defined between the inner cylinder and the outer cylinder, and a plurality of pulverized coal holes arranged at intervals are opened on the side wall of the inner cylinder;

[0006] The first pulverized coal bin is in communication with the fourth port of the inner cylinder through a first induced draft fan, and the first induced draft fan is used to transport the pulverized coal discharged from the first pulverized coal bin into the inner cylinder;

[0007] The second pulverized coal bin is in communication with the annular channel via a second induced draft fan, and the second induced draft fan is used for conveying pulverized coal discharged from the second pulverized coal bin into the annular channel.

[0008] In some embodiments, the pulverized coal holes are divided into a plurality of hole groups, the plurality of hole groups are spaced apart along the axial direction of the inner cylinder, and each hole group includes a plurality of pulverized coal holes spaced apart along the circumferential direction of the inner cylinder.

[0009] In some embodiments, the diameter of the inner cylinder is D, and the diameter of the coal powder hole is d, wherein 0.05≤d / D≤0.1.

[0010] In some embodiments, a plurality of first spoiler groups are disposed on the side outer wall of the inner cylinder, the plurality of first spoiler groups are arranged at intervals along the axial direction of the inner cylinder, and the first spoiler groups include a plurality of first protrusions arranged at intervals along the circumferential direction of the inner cylinder.

[0011] In some embodiments, at least one of the first spoiler groups is disposed between two adjacent hole groups.

[0012] In some embodiments, a plurality of second spoiler groups are provided on the inner side wall of the outer cylinder, the plurality of second spoiler groups are arranged at intervals along the axial direction of the outer cylinder, the second spoiler groups include a plurality of second protrusions arranged at intervals along the circumferential direction of the outer cylinder, and at least one first spoiler group is provided between two adjacent second spoiler groups.

[0013] In some embodiments, the outer cylinder includes a connected first straight line segment and a first conical segment, the first port is arranged on the first conical segment, the second port is arranged on the first straight line segment, the cross-sectional area of ​​the first conical segment gradually decreases along the direction from the second port to the first port, the inner cylinder includes a connected second straight line segment and a second conical segment, the third port is arranged on the second conical segment, the fourth port is arranged on the second straight line segment, at least a portion of the second conical segment is located in the first conical segment, and the taper and orientation of the second conical segment are the same as those of the first conical segment.

[0014] In some embodiments, a return cover is provided on the inner cylinder, the return cover is spaced apart from the third port in the axial direction of the inner cylinder, and an opening of the return cover is arranged along the axial direction of the inner cylinder toward the third port.

[0015] In some embodiments, there are multiple second pulverized coal bins, and the multiple second pulverized coal bins are used to store pulverized coal of different qualities.

[0016] In some embodiments, the boiler combustion system with low nitrogen oxide emissions of the embodiments of the present invention also includes an adsorption tower and a regeneration tower. The adsorption tower is connected to the flue to receive part of the flue gas before denitrification in the flue. The adsorption tower is used to adsorb nitrogen oxides in the flue gas and transport the adsorbent saturated with adsorption to the regeneration tower. The regeneration tower is used to heat and decompose the adsorbent saturated with adsorption. The regeneration tower is connected to the furnace to transport at least part of the nitrogen oxides regenerated by decomposition to the furnace.

[0017] When the boiler combustion system with low nitrogen oxide emission of the embodiment of the present invention is in use, the first pulverized coal bin and the second pulverized coal bin are used to store pulverized coal of different qualities, respectively. The pulverized coal in the first pulverized coal bin and the second pulverized coal bin are transported to the inner cylinder and the annular channel through the first induced draft fan and the second induced draft fan, respectively. Since a plurality of pulverized coal holes are provided on the side wall of the inner cylinder, when the pulverized coal in the first pulverized coal bin enters the inner cylinder, it will enter the annular channel through these pulverized coal holes and mix with the pulverized coal from the second pulverized coal bin in the annular channel. In the annular channel, the two pulverized coals will be dynamically mixed in the axial and radial directions of the annular channel, and the mixed pulverized coal will enter the furnace through the first port for combustion, which greatly improves the mixing uniformity of the two pulverized coals of different qualities, thereby improving the combustion sufficiency and stability of the mixed pulverized coal in the boiler. Since the combustion is more complete, the generation of nitrogen oxides can be greatly reduced, thereby reducing the content of nitrogen oxides in the flue gas, so the amount of ammonia spray required in the SCR denitrification process will also be reduced accordingly, and the flue gas treatment cost will also be reduced.

[0018] Therefore, the boiler combustion system with low nitrogen oxide emissions according to the embodiment of the present invention has the advantages of sufficient blending and low flue gas treatment cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of a boiler combustion system with low nitrogen oxide emissions according to an embodiment of the present invention.

[0020] Figure 2 It is a schematic structural diagram of the inner cylinder and the outer cylinder of an embodiment of the present invention.

[0021] Reference numerals:

[0022] 100. Boiler combustion system with low nitrogen oxide emission; 1. Boiler; 101. Furnace; 102. Flue; 2. Outer cylinder; 201. First port; 202. Second port; 203. First straight segment; 204. First conical segment; 3. Closing plate; 4. Inner cylinder; 401. Third port; 402. Fourth port; 403. Coal powder hole; 404. Second straight segment; 405. Second conical segment; 5. Annular channel; 6. First coal powder bin; 7. First induced draft fan; 8. Second coal powder bin; 9. Second induced draft fan; 10. First protrusion; 11. Second protrusion; 12. Reflux hood; 13. Adsorption tower; 14. Regeneration tower. DETAILED DESCRIPTION

[0023] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0024] like Figure 1 and Figure 2As shown, the boiler combustion system 100 with low nitrogen oxide emission of the embodiment of the present invention includes a boiler 1, an outer cylinder 2, an inner cylinder 4, a first pulverized coal bin 6 and a second pulverized coal bin 8. The boiler 1 includes a furnace 101 and a flue 102. The outer cylinder 2 has a first port 201 and a second port 202 opposite to each other. The first port 201 is connected to the furnace 101. A sealing plate 3 is provided on the second port 202, and a perforation is provided on the sealing plate 3. The inner cylinder 4 has a third port 401 and a fourth port 402 opposite to each other. The third port 401 extends into the outer cylinder 2 through the perforation. An annular channel 5 is defined between the inner cylinder 4 and the outer cylinder. A plurality of pulverized coal holes 403 arranged at intervals are provided on the side wall of the inner cylinder 4. The first pulverized coal bin 6 is connected to the fourth port 402 of the inner cylinder 4 through the first induced draft fan 7. The first induced draft fan 7 is used to transport the pulverized coal discharged from the first pulverized coal bin 6 to the inner cylinder 4. The second pulverized coal bin 8 is in communication with the annular channel 5 via a second induced draft fan 9 , and the second induced draft fan 9 is used for conveying the pulverized coal discharged from the second pulverized coal bin 8 into the annular channel 5 .

[0025] When the boiler combustion system 100 with low nitrogen oxide emission of the embodiment of the present invention is in use, the first pulverized coal bin 6 and the second pulverized coal bin 8 are used to store pulverized coal of different qualities, respectively. The pulverized coal in the first pulverized coal bin 6 and the second pulverized coal bin 8 are respectively transported to the inner cylinder 4 and the annular channel 5 through the first induced draft fan 7 and the second induced draft fan 9. Since a plurality of pulverized coal holes 403 are provided on the side wall of the inner cylinder 4, when the pulverized coal in the first pulverized coal bin 6 enters the inner cylinder 4, it will enter the annular channel 5 through these pulverized coal holes 403, and mix with the pulverized coal from the second pulverized coal bin 8 in the annular channel 5. In the annular channel 5, the two pulverized coals will be dynamically mixed in the axial and radial directions of the annular channel 5, and the mixed pulverized coal will enter the furnace 101 through the first port 201 for combustion, which greatly improves the mixing uniformity of the two pulverized coals of different qualities, thereby improving the combustion sufficiency and stability of the mixed pulverized coal in the boiler 1. Since the combustion is more complete, the generation of nitrogen oxides can be greatly reduced, thereby reducing the content of nitrogen oxides in the flue gas. Therefore, the amount of ammonia injection required in the SCR denitrification process will also be reduced accordingly, which also reduces the cost of flue gas treatment.

[0026] Therefore, the boiler combustion system 100 with low nitrogen oxide emissions according to the embodiment of the present invention has the advantages of sufficient blending and low flue gas treatment cost.

[0027] In some embodiments, the pulverized coal holes 403 are divided into a plurality of hole groups, and the plurality of hole groups are arranged at intervals along the axial direction of the inner cylinder 4 , and each hole group includes a plurality of pulverized coal holes 403 arranged at intervals along the circumferential direction of the inner cylinder 4 .

[0028] like Figure 2As shown, the pulverized coal holes 403 are divided into a plurality of hole groups, which are arranged at intervals along the axial direction of the inner cylinder 4. Such an arrangement helps the pulverized coal to be more evenly distributed in the axial direction of the inner cylinder 4, and this arrangement helps the pulverized coal to be better mixed in the axial direction of the inner cylinder 4. Each hole group includes a plurality of pulverized coal holes 403, which are arranged at intervals along the circumference of the inner cylinder 4, and this arrangement helps the pulverized coal to be better mixed in the circumferential direction. Through the axial and circumferential interval arrangement, the pulverized coal can be more fully mixed with the pulverized coal from the second pulverized coal bin 8 when entering the annular channel 5, thereby improving the combustion efficiency and reducing the emission of nitrogen oxides.

[0029] In some embodiments, the diameter of the inner cylinder 4 is D, and the diameter of the coal powder hole 403 is d, wherein 0.05≤d / D≤0.1.

[0030] For example, the value of d / D is 0.05, 0.08 or 0.1. The ratio between the diameter (d) of the pulverized coal hole 403 and the diameter (D) of the inner cylinder 4 is limited to the range of 0.05≤d / D≤0.1, that is, the diameter of the pulverized coal hole 403 is smaller than the diameter of the inner cylinder 4, and the smaller diameter of the pulverized coal hole 403 helps the pulverized coal to flow and mix better when entering the annular channel 5. The size and arrangement of the pulverized coal hole 403 help to improve the injection effect of the pulverized coal in the inner cylinder 5, so that the pulverized coal can enter the annular channel 5 at a suitable angle and speed, thereby achieving better mixing.

[0031] In some embodiments, a plurality of first spoiler groups are disposed on the side outer wall of the inner cylinder 4 , and the plurality of first spoiler groups are arranged at intervals along the axial direction of the inner cylinder 4 . The first spoiler groups include a plurality of first protrusions 10 arranged at intervals along the circumferential direction of the inner cylinder 4 .

[0032] like Figure 2 As shown, the setting of the first turbulence group will produce a turbulence effect during the flow of coal powder in the annular channel 5, which helps to increase the collision frequency and energy exchange between coal powder particles, thereby promoting the mixing of coal powder. By enhancing the mixing of coal powder, the turbulence design helps to improve the combustion efficiency, and the coal powder particles will be more fully in contact with oxygen, making the combustion more complete, thereby reducing the generation of unburned coal powder and nitrogen oxides. During the combustion process, the generation of nitrogen oxides is related to the combustion temperature and the oxygen in the combustion area. By optimizing the turbulence design, the temperature and oxygen concentration during the combustion process can be better controlled, thereby reducing the emission of nitrogen oxides. The circumferential spacing of the first protrusions 10 helps to evenly distribute the coal powder in the circumferential direction, avoiding the problem of insufficient mixing due to uneven injection of coal powder.

[0033] Optionally, at least one first spoiler group is provided between two adjacent hole groups.

[0034] For example, a first flow bypass group is provided between two adjacent hole groups. By providing the first flow disturbance group between adjacent hole groups, the flow path of the coal powder can be controlled so that the coal powder can be more evenly distributed in the annular channel 5 to increase the degree of mixing of the coal powder particles in the axial and circumferential directions. This design helps to improve the combustion efficiency because it ensures that the coal powder can be more fully mixed before entering the combustion area. The presence of the first flow disturbance group helps to adjust the airflow dynamics during the combustion process, thereby optimizing the combustion temperature and oxygen concentration distribution, which helps to reduce the generation of nitrogen oxides and improve thermal efficiency. The first flow disturbance group design also helps to improve the uniformity of coal powder combustion and reduce pollutant emissions caused by excessive or insufficient local combustion.

[0035] In some embodiments, a plurality of second spoiler groups are provided on the inner side wall of the outer cylinder 2, the plurality of second spoiler groups are arranged at intervals along the axial direction of the outer cylinder 2, the second spoiler groups include a plurality of second protrusions 11 arranged at intervals along the circumferential direction of the outer cylinder 2, and at least one first spoiler group is provided between two adjacent second spoiler groups.

[0036] The second spoiler group is arranged on the inner wall of the outer cylinder 2, and works together with the first spoiler group on the inner cylinder 4 to form a double-layer spoiler effect. This design helps to further enhance the mixing effect of the coal powder in the annular channel 5, thereby improving the combustion efficiency and reducing the content of nitrogen oxides. The second spoiler group interacts with the first spoiler group to optimize the airflow distribution, so that the coal powder can be more fully mixed and preheated before entering the combustion area.

[0037] In some embodiments, the outer cylinder 2 includes a first straight segment 203 and a first tapered segment 204 connected to each other, the first port 201 is provided on the first tapered segment 204, the second port 202 is provided on the first straight segment 203, and the cross-sectional area of ​​the first tapered segment 204 gradually decreases along the direction from the second port 202 to the first port 201. The inner cylinder 4 includes a second straight segment 404 and a second tapered segment 405 connected to each other, the third port 401 is provided on the second tapered segment 405, the fourth port 402 is provided on the second straight segment 404, at least a portion of the second tapered segment 405 is located in the first tapered segment 204, and the taper and orientation of the second tapered segment 405 are the same as those of the first tapered segment 204.

[0038] The cross-sectional area of ​​the first tapered section 204 of the outer cylinder 2 gradually decreases from the second port 202 to the first port 201. This tapered design helps to guide the airflow to rotate when entering the boiler 1, thereby increasing the turbulence of the airflow and improving the mixing efficiency of the coal powder. Since the airflow is accelerated when passing through the tapered section, this design helps to quickly introduce the coal powder into the combustion area, reduce the deposition of coal powder near the inlet of the boiler 1, and thus improve the combustion efficiency. The inner cylinder 4 includes a second straight section 404 and a second tapered section 405, and a part of the second tapered section 405 is located in the first tapered section 204. This design helps to form more complex airflow dynamics in the inner cylinder 4, further promoting the mixing and combustion of coal powder. The taper and orientation of the second tapered section 405 are the same as those of the first tapered section 204, which helps to maintain the stability and uniformity of the airflow, reduce the separation of the airflow and the formation of vortices, and thus improve the combustion efficiency. This geometric design helps to optimize the combustion process, reduce the generation of nitrogen oxides, and improve thermal efficiency.

[0039] In some embodiments, a return cover 12 is disposed on the inner cylinder 4 , and the return cover 12 is spaced apart from the third port 401 in the axial direction of the inner cylinder 4 , and an opening of the return cover 12 is disposed along the axial direction of the inner cylinder 4 toward the third port 401 .

[0040] The provision of the backflow hood 12 helps to form a backflow area near the third port 401. The backflow effect refers to the fact that the airflow will flow back to the initial area when passing through certain structures, thereby changing the flow direction and speed of the airflow. This effect helps to improve the mixing degree of the coal powder particles, thereby improving the combustion efficiency. By introducing the backflow effect, the backflow hood 12 helps to increase the contact area between the coal powder particles and oxygen, thereby improving the combustion efficiency. Optimizing the combustion process can reduce the generation of nitrogen oxides, so the design of the backflow hood 12 helps to reduce the content of nitrogen oxides in the flue gas, thereby reducing the cost of flue gas treatment.

[0041] Optionally, the number of the second pulverized coal bins 8 is multiple, and the multiple second pulverized coal bins 8 are used to store pulverized coal of different qualities. By using multiple second pulverized coal bins 8, pulverized coal of multiple different qualities can be stored, thereby providing more fuel options for the boiler 1 to adapt to different combustion requirements and environmental conditions. According to different combustion conditions and emission standards, suitable pulverized coal can be flexibly selected for blending to optimize the combustion process and reduce the emission of nitrogen oxides. Pulverized coal of different qualities has different combustion characteristics. By selecting a suitable combination of pulverized coal, the generation of nitrogen oxides during the combustion process can be controlled to achieve lower emissions. Pulverized coal of different qualities has different combustion efficiencies. By selecting a suitable combination of pulverized coal, the overall combustion efficiency can be improved, fuel consumption can be reduced, and operating costs can be reduced. The design of multiple second pulverized coal bins 8 can increase the stability of the system, because even if a pulverized coal bin fails or needs maintenance, other pulverized coal bins can continue to supply pulverized coal to ensure the stable operation of the boiler 1. By adjusting the pulverized coal ratio and delivery rate of different pulverized coal bins, the combustion parameters can be flexibly adjusted to achieve precise control of the combustion process.

[0042] In some embodiments, the boiler combustion system 100 with low nitrogen oxide emission in the embodiment of the present invention further includes an adsorption tower 13 and a regeneration tower 14. The adsorption tower 13 is connected to the flue 102 to receive part of the flue gas before denitration in the flue 102. The adsorption tower 13 is used to adsorb nitrogen oxides in the flue gas and transport the adsorbent saturated with adsorption to the regeneration tower 14. The regeneration tower 14 is used to heat and desorb the adsorbent saturated with adsorption. The regeneration tower 14 is connected to the furnace 101 to transport at least part of the nitrogen oxides regenerated by desorption to the furnace 101.

[0043] It should be noted that NOx in flue gas is divided into combustion NOx and thermal NOx. Combustion NOx refers to NOx generated by thermal decomposition and oxidation of nitrogen-containing compounds in fuel during combustion, and thermal NOx refers to NOx generated by the reaction of nitrogen and oxygen in air at high temperature. NOx generated by coal-fired boilers during combustion generally consists of 70% combustion NOx and 30% thermal NOx. The inventors recognize that combustion NOx is usually unavoidable because it is generated by nitrogen-containing compounds in fuel during combustion. However, thermal NOx is generated by the reaction of nitrogen and oxygen under high temperature environment of the boiler. The generation of thermal NOx will lead to an increase in the content of nitrogen oxides in boiler flue gas. Since the reaction of nitrogen and oxygen to generate thermal NOx is a reversible reaction, nitrogen oxides can be introduced into the furnace 101 of the boiler 1 to suppress the generation of thermal NOx. Therefore, the inventors have found that by suppressing the generation of thermal NOx in the boiler, the content of NOx in flue gas can be reduced.

[0044] The boiler combustion system 100 with low nitrogen oxide emission of the embodiment of the present invention processes part of the flue gas before denitration produced in the flue 102, removes nitrogen oxides in the flue gas by using the adsorption tower 13 and the regeneration tower 14, and transports at least part of the removed nitrogen oxides to the furnace 101. The nitrogen oxides introduced into the furnace 101 can suppress the additional generation of thermal NOx nitrogen oxides in the furnace 101, thereby not increasing the amount of ammonia injection required in the SCR denitration process, and also reducing the cost of flue gas treatment. It should be noted that a dynamic balance of nitrogen oxides can be formed between the flue 102, the adsorption tower 12 and the regeneration tower 14, that is, the content of nitrogen oxides in the flue gas before denitration discharged from the flue 102 can be the same as the content of nitrogen oxides entering the furnace 102, thereby achieving a dynamic balance, so that while suppressing the generation of thermal NOx nitrogen oxides in coal powder combustion, the overall content of nitrogen oxides in the flue 102 will not be increased.

[0045] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0046] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0047] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0048] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0049] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0050] Although the above embodiments have been shown and described, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. Changes, modifications, substitutions and variations of the above embodiments by those of ordinary skill in the art are all within the scope of protection of the present invention.

Claims

1. A boiler combustion system with low nitrogen oxide emissions, characterized in that: include: A boiler, the boiler comprising a furnace and a flue; An outer cylinder, the outer cylinder having a first port and a second port opposite to each other, the first port being communicated with the furnace, the second port being provided with a sealing plate, and the sealing plate being provided with a through hole; An inner cylinder, wherein the inner cylinder has a third port and a fourth port opposite to each other, the third port extends into the outer cylinder through the through hole, an annular channel is defined between the inner cylinder and the outer cylinder, and a plurality of pulverized coal holes arranged at intervals are opened on the side wall of the inner cylinder; a first pulverized coal bin, the first pulverized coal bin being connected to the fourth port of the inner cylinder through a first induced draft fan, the first induced draft fan being used for conveying pulverized coal discharged from the first pulverized coal bin into the inner cylinder; A second pulverized coal bin is connected to the annular channel via a second induced draft fan, and the second induced draft fan is used for conveying the pulverized coal discharged from the second pulverized coal bin into the annular channel.

2. The boiler combustion system with low nitrogen oxide emissions according to claim 1, characterized in that: The pulverized coal holes are divided into a plurality of hole groups, and the plurality of hole groups are arranged at intervals along the axial direction of the inner cylinder, and each hole group includes a plurality of pulverized coal holes arranged at intervals along the circumferential direction of the inner cylinder.

3. According to the boiler combustion system with low nitrogen oxide emissions as claimed in claim 2, the diameter of the inner cylinder is D, the diameter of the coal powder hole is d, wherein 0.05≤d / D≤0.

1.

4. According to the boiler combustion system with low nitrogen oxide emissions as described in claim 2, a plurality of first spoiler groups are provided on the side outer wall of the inner cylinder, and the plurality of first spoiler groups are arranged at intervals along the axial direction of the inner cylinder, and the first spoiler groups include a plurality of first protrusions arranged at intervals along the circumferential direction of the inner cylinder. 5 . According to the boiler combustion system with low nitrogen oxide emissions as claimed in claim 4 , at least one of the first spoiler groups is provided between two adjacent hole groups.

6. According to the boiler combustion system with low nitrogen oxide emissions as described in claim 4, a plurality of second spoiler groups are provided on the side inner wall of the outer cylinder, and the plurality of second spoiler groups are arranged at intervals along the axial direction of the outer cylinder. The second spoiler groups include a plurality of second protrusions arranged at intervals along the circumferential direction of the outer cylinder, and at least one first spoiler group is provided between two adjacent second spoiler groups.

7. According to claim 1, the boiler combustion system with low nitrogen oxide emissions, the outer cylinder includes a connected first straight section and a first conical section, the first port is arranged on the first conical section, the second port is arranged on the first straight section, the cross-sectional area of ​​the first conical section gradually decreases along the direction from the second port to the first port, the inner cylinder includes a connected second straight section and a second conical section, the third port is arranged on the second conical section, the fourth port is arranged on the second straight section, at least a portion of the second conical section is located in the first conical section, and the taper and orientation of the second conical section are the same as those of the first conical section.

8. According to the boiler combustion system with low nitrogen oxide emissions as described in claim 7, a reflow hood is provided on the inner cylinder, and the reflow hood is spaced apart from the third port in the axial direction of the inner cylinder, and the opening of the reflow hood is arranged along the axial direction of the inner cylinder toward the third port.

9. According to the boiler combustion system with low nitrogen oxide emissions as claimed in claim 1, there are multiple second pulverized coal bins, and the multiple second pulverized coal bins are used to store pulverized coal of different qualities.

10. The boiler combustion system with low nitrogen oxide emissions according to claim 1 further includes an adsorption tower and a regeneration tower, wherein the adsorption tower is connected to the flue to receive part of the flue gas before denitrification in the flue, the adsorption tower is used to adsorb nitrogen oxides in the flue gas and transport the adsorbent saturated with adsorption to the regeneration tower, the regeneration tower is used to heat and decompose the adsorbent saturated with adsorption, and the regeneration tower is connected to the furnace to transport at least part of the nitrogen oxides regenerated by decomposition to the furnace.

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