CN118582734A - A boiler combustion system - Google Patents

Abstract

The present invention relates to a boiler combustion system, comprising: boiler, combustor and fan subassembly, be equipped with furnace in the boiler, the boiler have with the flue gas outlet of furnace intercommunication, the combustor includes swirler and prechamber, the swirler has primary air intake and secondary air intake, primary air intake is used for letting in buggy, secondary air intake is used for letting in the mixed wind that mixes the flue gas, the export of swirler with the import intercommunication of prechamber, the export of prechamber with furnace intercommunication, the swirl number of swirler is A, wherein, 0.8 is less than or equal to A is less than or equal to 1.0, the fan subassembly includes the overgrate air machine, the import of overgrate air machine with flue gas import and air delivery pipeline intercommunication, the overgrate air machine export with the secondary air intake intercommunication. The boiler combustion system is not easy to vibrate during operation, and is beneficial to improving the operation reliability of the boiler combustion system.

Description

A boiler combustion system

Technical Field

The invention relates to the technical field of boiler combustion, and in particular to a boiler combustion system.

Background Art

In recent years, high-efficiency pulverized coal industrial boilers have rapidly occupied most of the pulverized coal boiler market in my country due to their high combustion efficiency and low pollutant emissions. In order to meet market demand, pulverized coal industrial boiler systems have developed towards large-scale development. After the above-mentioned boiler combustion system was put into operation, due to the unreasonable design structure of the burner and boiler of the boiler combustion system, the combustion system will produce large vibrations during operation, which will easily cause the rivets on the furnace wall to loosen and fall off, the welds to crack, the insulation coating to peel off, and the boiler to leak, resulting in major safety hazards during the operation of the boiler combustion system.

Summary of the invention

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, which is less likely to generate vibration during operation, thereby helping to improve the reliability of the operation of the boiler combustion system.

The boiler combustion system of an embodiment of the present invention includes: a boiler, wherein a furnace is provided in the boiler, and the boiler has a flue gas outlet connected to the furnace; a burner, wherein the burner includes a swirler and a pre-combustion chamber, the swirler has a primary air inlet and a secondary air inlet, the primary air inlet is used to introduce pulverized coal, and the secondary air inlet is used to introduce mixed air mixed with flue gas, the outlet of the swirler is connected to the inlet of the pre-combustion chamber, and the outlet of the pre-combustion chamber is connected to the furnace, and the swirl number of the swirler is A, wherein 0.8≤A≤1.0; a fan assembly, wherein the fan assembly includes a secondary fan, the inlet of the secondary fan is connected to the flue gas inlet and the air delivery channel, and the outlet of the secondary fan is connected to the secondary air inlet.

According to the boiler combustion system of an embodiment of the present invention, by adjusting the swirl number of the swirler, it is possible to reduce the swirl intensity, improve the smooth organization, and reduce the vortex frequency at the outlet of the pre-combustion chamber while ensuring the stable combustion effect of the burner, thereby preventing the flame swing from exciting the low-frequency vibration of the flue gas, thereby reducing the resonance problem during boiler operation.

In some embodiments, the flame injection speed at the outlet of the pre-combustion chamber is K, wherein 90m/s≤K≤110m/s.

In some embodiments, the outlet of the pre-combustion chamber extends into the furnace to a preset distance.

In some embodiments, the preset distance is L, where 25cm≤L≤35cm.

In some embodiments, the boiler is provided with a tertiary air inlet, and the tertiary air inlet is connected to the furnace and the inlet of the secondary fan.

In some embodiments, the mixed air introduced into the secondary air inlet per unit time is P1, the mixed air introduced into the tertiary air inlet per unit time is P2, and 1.4≤P1/P2≤1.6.

In some embodiments, the feed rate of the primary air inlet is 4 t/h, the air volume at the secondary air inlet is between 28000m ³ /h and 30000m ³ /h, and the temperature at the pre-combustion chamber outlet is between 900°C and 1100°C.

In some embodiments, the boiler combustion system further includes an oxygen content detection meter, which is connected to the outlet of the secondary air fan, and the oxygen content of the mixed air is Q, where 17%≤Q≤19%.

In some embodiments, the burner is installed at the upper end of the boiler, and the center line of the pre-combustion chamber is on the same straight line as the center line of the boiler.

In some embodiments, the burner is a double cone reverse jet burner.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a boiler combustion system according to an embodiment of the present invention.

Reference numerals:

1. Boiler; 11. Furnace; 12. Smoke outlet; 13. Tertiary air inlet;

2. Burner; 21. Swirl; 211. Primary air inlet; 212. Secondary air inlet; 22. Pre-combustion chamber;

3. Mixed air regulating valve;

4. Fan assembly; 41. Secondary fan; 42. Induced draft fan; 43. Flue gas circulation fan;

5. Oxygen content test table;

6. Flue gas regulating valve;

7. Air delivery duct.

DETAILED DESCRIPTION

The 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.

The boiler combustion system according to an embodiment of the present invention will be described below with reference to FIG. 1 .

As shown in FIG1 , the boiler combustion system according to the embodiment of the present invention includes: a boiler 1, a burner 2 and a fan assembly 4, wherein the fan assembly 4 includes a secondary fan 41. A furnace 11 is provided in the boiler 1, and the boiler 1 has a flue gas outlet 12 connected to the furnace 11. The burner 2 includes a cyclone 21 and a pre-combustion chamber 22. The cyclone 21 has a primary air inlet 211 and a secondary air inlet 212. The primary air inlet 211 is used to introduce pulverized coal, and the secondary air inlet 212 is used to introduce mixed air mixed with flue gas. The outlet of the cyclone 21 is connected to the inlet of the pre-combustion chamber 22, and the outlet of the pre-combustion chamber 22 is connected to the furnace 11. The swirl number of the cyclone 21 is A, wherein 0.8≤A≤1.0. The inlet of the secondary fan 41 is connected to the flue gas inlet and the air delivery duct 7, and the outlet of the secondary fan 41 is connected to the secondary air inlet 212.

It is well known to those skilled in the art that the swirl intensity of the swirl blades of the swirler 21 is generally defined by the “swirl number”.

The boiler combustion system in the related art usually designs the swirl number A between 1.1 and 1.2. The inventor of the present application found through experimental research that when the swirl number A is designed with the above parameters, the strong swing of the outlet flame of the pre-combustion chamber 22 will excite the low-frequency vibration of the flue gas, thereby causing the resonance of the boiler 1. When the inventor of the present application reduces the swirl number A to between 0.8 and 1.0, the turbulence of the flame in the pre-combustion chamber 22 can be reduced, and the vortex frequency of the outlet flame of the pre-combustion chamber 22 caused by the excessive swirl intensity is reduced, thereby reducing the resonance of the boiler 1.

For example, technicians can adjust the swirl number of the swirler 21 by adjusting the inclination angle of the swirl blades.

Optionally, the swirl number A can be 0.8, 0.85, 0.9, 0.95, or 1.0. The inventors of the present application have found through experimental research that when the swirl number A is greater than 1.0, the strong swing of the outlet flame of the pre-combustion chamber 22 will excite the low-frequency vibration of the flue gas, resulting in a greater resonance problem of the boiler 1. When the swirl number A is less than 0.8, the pre-combustion chamber 22 is insufficient to generate a recirculation zone, or the range of the generated recirculation zone is small, which is not conducive to the stable combustion of the fuel in the pre-combustion chamber 22, resulting in poor stable combustion effect and combustion efficiency.

Therefore, the inventor of the present application designed the swirl number A to be between 0.8 and 1.0, which can reduce the turbulence of the flame in the pre-combustion chamber 22, and at the same time reduce the vortex frequency of the flame at the outlet of the pre-combustion chamber 22 caused by the excessive swirl intensity, thereby reducing the resonance of the boiler 1 and ensuring the stable combustion effect and combustion efficiency of the combustion chamber.

In summary, the boiler combustion system of the embodiment of the present invention can reduce the swirl intensity, improve the smooth organization, and reduce the vortex frequency at the outlet of the pre-combustion chamber 22 by adjusting the swirl number of the swirler 21, while ensuring the stable combustion effect of the burner 2, and prevent the flame swing from exciting the low-frequency vibration of the flue gas, thereby reducing the resonance problem during the operation of the boiler 1, and has a better stable combustion effect and a higher combustion efficiency, which is beneficial to improving the reliability of the operation of the boiler combustion system.

It is understandable that the boiler combustion system of the embodiment of the present invention mixes the return flue gas and oxygen in a certain proportion, and then introduces the mixture into the pre-combustion chamber 22 through the secondary air inlet 212 to perform low-oxygen combustion with the pulverized coal.

Optionally, the flame injection velocity at the outlet of the pre-combustion chamber is K, wherein 90m/s≤K≤110m/s. When the flame injection velocity at the outlet of the pre-combustion chamber adopts the above numerical range, the formation of acoustic standing waves can be weakened to avoid resonance.

Preferably, the flame injection speed at the outlet of the pre-combustion chamber is between 90 m/s and 100 m/s, thereby further improving the vibration reduction effect of the boiler combustion system.

In an optional example, the cross-sectional area of the outlet of the pre-combustion chamber 22 is S, wherein 0.44m ² ≤S≤0.46m ² . The inventors of the present application have found through experimental research that by setting the cross-sectional area of the outlet of the pre-combustion chamber 22 to S and adopting the above parameter design, the flame injection speed can be limited to between 90-100m/s, so as to weaken the formation of acoustic standing waves and avoid resonance.

For example, the cross-sectional area S of the outlet of the pre-combustion chamber 22 may be 0.44 m ² , 0.45 m ² , or 0.46 m ² . The inventors of the present application have found through experimental research that when the cross-sectional area S of the outlet of the pre-combustion chamber 22 exceeds 0.46 m ² , the combustion efficiency of the boiler 1 will be reduced, and there will be a problem of insufficient premixing. When the cross-sectional area S of the outlet of the pre-combustion chamber 22 is less than 0.44 m ² , the flame injection speed will be relatively large (greater than 110 m/s), which will cause the boiler 1 to resonate.

Optionally, the outlet of the pre-combustion chamber 22 extends into the furnace 11 by a preset distance. This can greatly avoid the problem of coking at the outlet of the pre-combustion chamber 22 due to the adhesion of molten ash particles of the flash to the refractory mud wall of the furnace 11. It is understandable that coking at the outlet of the pre-combustion chamber 22 will gradually block the outlet of the pre-combustion chamber 22, thereby affecting the combustion power field, thereby causing the furnace pressure to fluctuate violently and causing the boiler 1 to resonate.

In one example, the preset distance is L, wherein 25 cm ≤ L ≤ 35 cm. It can be understood that the preset distance L is the distance from the outlet of the pre-combustion chamber 22 to the furnace 11 .

For example, L can be 25 cm, 28 cm, 30 cm, 33 cm, or 35 cm. The inventors of the present application have found through experimental research that when the distance from the outlet of the pre-combustion chamber 22 to the furnace 11 is within the above numerical range, the problem of coking at the outlet of the pre-combustion chamber 22 caused by the adhesion of molten ash particles of the flash to the refractory mud wall of the furnace 11 can be greatly avoided, thereby greatly reducing the probability of resonance of the boiler 1.

In some embodiments, a tertiary air inlet 13 is provided on the boiler 1, and the tertiary air inlet 13 is connected to the furnace 11 and the inlet of the secondary fan 41, thereby allowing the pulverized coal to burn more fully.

Optionally, the mixed air introduced into the secondary air inlet 212 per unit time is P1, and the mixed air introduced into the tertiary air inlet 13 per unit time is P2, and 1.4≤P1/P2≤1.6. For example, the ratio of P1/P2 can be 1.4, 1.5, or 1.6. In one example, the ratio of P1:P2 is 3:2. That is, 60% of the mixed air is introduced into the burner 2, and 40% is introduced into the furnace 11.

For example, the secondary air intake and the tertiary air intake can be controlled by the mixed air regulating valve 3. As shown in FIG1 , the mixed air regulating valve 3 is provided on the pipeline between the outlet of the secondary fan 41 and the secondary air inlet 212, and on the pipeline between the outlet of the secondary fan 41 and the tertiary air inlet 13, so as to adjust the ratio of air entering the secondary air inlet 212 and the tertiary air inlet 13.

It is understandable that the boiler 1 adopts a suitable method and mixing ratio of combustion-supporting air and reflux flue gas, and achieves the required oxygen content, CO2, etc. through premixing. When the boiler 1 is running at low load, the flue gas (oxygen content 9%) and the combustion-supporting air are introduced into the precombustion chamber 22 in the form of mixed air for low-oxygen combustion. Under the action of the reflux flue gas, the combustion intensity in the precombustion chamber 22 is greatly suppressed. This is because the oxygen content of the combustion-supporting air is low, which is not conducive to full combustion. In addition, the flue gas contains a certain amount of carbon dioxide. The isobaric specific heat capacity of CO2 is higher than that of the corresponding N2, which can significantly absorb heat and is not conducive to the increase of combustion intensity, so as to reduce the resonance of the boiler 1.

Specifically, the feed rate is 4 t/h, that is, the feed rate of the primary air inlet 211 is 4 t/h. The air volume at the secondary air inlet 212 is between 28000m ³ /h and 30000m ³ /h, and the temperature at the outlet of the pre-combustion chamber 22 is between 900℃ and 1100℃. Due to the increase in the total air volume, the residence time of the coal powder particles in the pre-combustion chamber 22 is shortened, weakening the combustion process in the burner 2. The maximum temperature at the outlet of the burner 2 is reduced from the original 1200-1300℃ to about 900℃-1100℃, thereby effectively avoiding the burner 2 from generating violent thermoacoustic vibrations, thereby eliminating the resonance problem of the boiler 1.

As shown in FIG1 , the boiler combustion system further includes an oxygen content detection meter 5, which is connected to the outlet of the secondary fan 41, and the oxygen content of the mixed air is Q, wherein 17%≤Q≤19%. For example, the oxygen content Q of the mixed air is 17%, 18%, or 19%. The inventor of the present application has found through experimental research that when the oxygen content Q of the mixed air adopts the above-mentioned value, the pulverized coal can be burned with low oxygen in the pre-combustion chamber 22, and under the action of the reflux flue gas, the combustion intensity in the pre-combustion chamber 22 is greatly suppressed, thereby reducing the resonance of the boiler 1.

As shown in FIG. 1 , the fan assembly 4 further includes an induced draft fan 42 and a flue gas circulation fan 43. The inlet of the induced draft fan 42 is connected to the flue gas outlet 12 of the boiler 1. A portion of the outlet of the induced draft fan 42 is led to the chimney, and another portion of the outlet of the induced draft fan 42 is led to the inlet of the flue gas circulation fan 43. The outlet of the flue gas circulation fan 43 is connected to the inlet of the secondary fan 41. In other examples, it is not necessary to separately provide the flue gas circulation fan 43 to reduce equipment investment and operating costs.

Specifically, a flue gas regulating valve 6 may be provided on the pipeline between the outlet of the flue gas circulation fan 43 and the inlet of the secondary fan 41 to adjust the flow rate of flue gas entering the secondary fan 41 .

For example, the burner 2 is a double-conical reverse-injection burner 2 to improve the combustion effect of the burner 2 .

In some embodiments, the burner 2 is installed at the upper end of the boiler 1, and the center line of the pre-combustion chamber 22 is on the same straight line as the center line of the boiler 1. It can be understood that the boiler combustion system is a vertical boiler combustion system. When the center line of the pre-combustion chamber 22 is on the same straight line as the center line of the boiler 1, the resonance generated when the boiler 1 is running can be effectively reduced.

Alternatively, the burner 2 may also be installed on one side of the boiler 1 in the horizontal direction, that is, the boiler combustion system is a horizontal boiler combustion system. The present application does not specifically limit the type of the boiler combustion system.

To sum up, the boiler combustion system of the embodiment of the present invention improves the combustion organization by optimizing the tangential swirl blade structure of the double-cone reverse jet burner, the outlet cross-sectional area 22 of the pre-combustion chamber and the position 22 of the pre-combustion chamber; at the same time, the combustion technology of the combustion air mixed with the hot flue gas is utilized to shorten the combustion process of the coal powder in the burner 2, reduce the combustion intensity, and avoid the vibration of the burner 2, thereby eliminating the resonance problem of the boiler 1, and providing a suitable solution for solving the vibration problem of the boiler 1 for large vertical steam pulverized coal industrial boilers.

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 device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

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.

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.

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.

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.

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 (10)

1. A boiler combustion system, comprising:

A boiler, wherein a hearth is arranged in the boiler, and the boiler is provided with a flue gas outlet communicated with the hearth;

The burner comprises a cyclone and a precombustor, wherein the cyclone is provided with a primary air inlet and a secondary air inlet, the primary air inlet is used for introducing pulverized coal, the secondary air inlet is used for introducing mixed wind mixed with flue gas, an outlet of the cyclone is communicated with an inlet of the precombustor, an outlet of the precombustor is communicated with the hearth, and the swirl number of the cyclone is A, wherein A is more than or equal to 0.8 and less than or equal to 1.0;

The fan assembly comprises a secondary fan, an inlet of the secondary fan is communicated with the flue gas inlet and the air conveying channel, and an outlet of the secondary fan is communicated with the secondary air inlet.

2. A boiler combustion system as claimed in claim 1, characterized in that the flame injection speed at the outlet of the prechamber is K, wherein K is 90 m/s.ltoreq.110 m/s.

3. The boiler combustion system of claim 1, wherein the outlet of the prechamber extends a predetermined distance into the furnace.

4. A boiler combustion system as claimed in claim 3, wherein the predetermined distance is L, wherein 25cm +.l+.35 cm.

5. The boiler combustion system of claim 1, wherein the boiler is provided with a tertiary air intake, the tertiary air intake being in communication with the furnace and the inlet of the secondary air fan.

6. The boiler combustion system of claim 5, wherein the mixed air introduced into the secondary air inlet in unit time is P1, and the mixed air introduced into the tertiary air inlet in unit time is P2, and P1/P2 is 1.4 or less and 1.6 or less.

7. The boiler combustion system as set forth in claim 6 wherein said primary air intake is fed at a rate of 4t/h, said secondary air intake is fed at a rate of 28000m ³/h～30000m³/h, and said prechamber outlet is at a temperature of 900 ℃ to 1100 ℃.

8. The boiler combustion system of claim 1, further comprising an oxygen content detection gauge in communication with the outlet of the secondary fan, the oxygen content of the mixed wind being Q, wherein 17% Q is less than or equal to 19%.

9. The boiler combustion system of claim 1, wherein the burner is mounted at an upper end of the boiler and a centerline of the prechamber is collinear with a centerline of the boiler.

10. The boiler combustion system of any of claims 1-9, wherein the burner is a biconical reverse jet burner.