CN108397766B - Boiler and air distribution method thereof - Google Patents

Abstract

The invention discloses a boiler and an air distribution method of the boiler. The boiler includes: the furnace body is internally provided with a hearth; the first burners are arranged on the furnace body at intervals along the circumferential direction of the furnace body, each first burner is provided with a primary air nozzle, and the central line of jet flow of the primary air nozzles is tangent to a first circumference along one of the clockwise direction and the anticlockwise direction; and the second burners are arranged on the furnace body at intervals along the circumferential direction of the furnace body, each second burner is provided with a secondary air nozzle, and the jet flow central line of the secondary air nozzles is tangent to a second circumference along the other one of the clockwise direction and the anticlockwise direction. The boiler provided by the embodiment of the invention has the advantages of high heat transfer efficiency, low operation cost, high safety and the like.

Description

Boiler and air distribution method thereof

Technical Field

The invention relates to the technical field of energy, in particular to a boiler and an air distribution method of the boiler.

Background

Carbon dioxide emitted from coal-fired power generation is a major source of greenhouse gases. The oxygen-enriched combustion technology adopts a flue gas recirculation mode, and uses a mixed gas formed by pure oxygen obtained by air separation and a part of boiler exhaust gas to replace air as an oxidant during combustion, so that high-concentration carbon dioxide is enriched in the combustion exhaust gas, and the carbon dioxide is collected at low cost.

However, the horizontal flue of the existing boiler operated in the oxygen-enriched combustion mode has smoke speed deviation and smoke temperature deviation, so that the operation cost of the boiler is high, and the safe operation of the boiler is seriously influenced.

Disclosure of Invention

The present application is based on the discovery and recognition by the inventors of the following facts and problems: the height of the furnace of the known boiler is not sufficient to eliminate the tangential rotational velocity of the updraft, so the air flow in the upper part of the furnace has a residual rotation. Under the oxygen-enriched combustion condition, because the volume of gas entering the hearth is reduced, enough secondary air is not used as over-fire air, and the residual rotation of the airflow at the upper part of the hearth cannot be eliminated. Since the air flow in the upper part of the furnace has a residual rotation, a smoke velocity deviation and a smoke temperature deviation are formed in the horizontal flue of the boiler.

The invention aims to overcome the problems in the prior art and provides a boiler and an air distribution method of the boiler, wherein the air flow at the outlet of a hearth of the boiler does not have residual rotation under the oxygen-enriched combustion working condition.

In order to achieve the above object, a first aspect of the present invention provides a boiler comprising: the furnace body is internally provided with a hearth; the first burners are arranged on the furnace body at intervals along the circumferential direction of the furnace body, each first burner is provided with a primary air nozzle, and the central line of jet flow of the primary air nozzles is tangent to a first circumference along one of the clockwise direction and the anticlockwise direction; and the second burners are arranged on the furnace body at intervals along the circumferential direction of the furnace body, each second burner is provided with a secondary air nozzle, and the jet flow central line of the secondary air nozzles is tangent to a second circumference along the other one of the clockwise direction and the anticlockwise direction.

The boiler provided by the embodiment of the invention has the advantages of low operation cost and high safety.

Preferably, the boiler further comprises at least one third burner, the third burner is arranged on the furnace body, the third burner is provided with an over-fire air nozzle, each first burner is movably arranged on the furnace body between a tangent position and an anti-tangent position, the other of the jet flow central lines of the primary air nozzles of the plurality of first burners at the tangent position is tangent to a third circumference along the clockwise direction and the anticlockwise direction, the one of the jet flow central lines of the primary air nozzles of the plurality of first burners at the anti-tangent position is tangent to the first circumference along the clockwise direction and the anticlockwise direction, and the one of the jet flow central lines of the over-fire air nozzles at the clockwise direction and the anticlockwise direction is tangent to a fourth circumference.

Preferably, the center of the first circle and the center of the second circle are located on the same vertical line, the radius of the first circle is smaller than the radius of the second circle, and preferably, the center of the first circle and the center of the second circle are located on the vertical central line of the furnace.

Preferably, the plurality of first burners and the plurality of second burners are opposite to each other in the vertical direction, an included angle α between the jet flow center line of the second burner opposite in the vertical direction and the projection of the jet flow center line of the first burner located at the undercut position on the horizontal plane is greater than or equal to 5 degrees and less than or equal to 20 degrees, and preferably, an included angle α between the jet flow center line of the second burner opposite in the vertical direction and the jet flow center line of the first burner located at the undercut position is greater than or equal to 7 degrees and less than or equal to 15 degrees.

Preferably, the plurality of first burners constitute a plurality of first burner groups, the plurality of first burner groups are arranged at intervals in the vertical direction, each first burner group comprises a plurality of first burners, and the plurality of first burners of each first burner group are arranged on the furnace body at intervals in the circumferential direction of the furnace body; the plurality of second burners constitute a plurality of second burner groups, the plurality of second burner groups are arranged at intervals in the vertical direction, each second burner group comprises a plurality of second burners, and the plurality of second burners of each second burner group are arranged on the furnace body at intervals in the circumferential direction of the furnace body; preferably, a plurality of the first burners of a plurality of the first burner groups and a plurality of the second burners of a plurality of the second burner groups are opposed to each other in an up-down direction so as to form a plurality of rows of burners; preferably, a plurality of the first burner groups and a plurality of the second burner groups are alternately arranged in an up-down direction, and more preferably, a lowermost one of the plurality of the first burner groups and the plurality of the second burner groups is the second burner group, and an uppermost one of the plurality of the first burner groups and the plurality of the second burner groups is the second burner group; preferably, the number of the third burners is a plurality of third burners provided on the furnace body at intervals in the circumferential direction of the furnace body, and more preferably, the third burners, the first burners of the first burner groups, and the second burners of the second burner groups are opposite to each other in the up-down direction so as to form a plurality of rows of burners; preferably, each first burner group comprises four first burners, four first burners of each first burner group are arranged at four corners of the furnace body in a one-to-one correspondence manner, each second burner group comprises four second burners, and four second burners of each second burner group are arranged at four corners of the furnace body in a one-to-one correspondence manner.

The second aspect of the present invention provides a method for distributing air to a boiler, comprising the steps of: under the oxygen-enriched combustion working condition, primary air and secondary air are provided for a hearth of the boiler, the primary air rotates in one of a clockwise direction and a counterclockwise direction in the hearth, and the secondary air rotates in the other of the clockwise direction and the counterclockwise direction in the hearth.

By utilizing the air distribution method of the boiler, the operation cost of the boiler can be greatly reduced, and the boiler can be safely operated.

Preferably, the air distribution method of the boiler further comprises the following steps: under an air combustion condition, primary air and secondary air are provided to a furnace of the boiler, the primary air rotates in the furnace in the other one of the clockwise direction and the counterclockwise direction, and the secondary air rotates in the furnace in the other one of the clockwise direction and the counterclockwise direction.

Preferably, the momentum of the primary air under the oxygen-enriched combustion condition is equal to the momentum of the primary air under the air combustion condition, and the ratio of the wind speed of the primary air under the oxygen-enriched combustion condition to the wind speed of the primary air under the air combustion condition is (0.8-0.9): preferably, in the oxycombustion condition, the air distribution method further comprises stopping providing over-fire air into the furnace, more preferably, the primary air is a plurality of strands, the secondary air is a plurality of strands, and the momentum of the lowermost strand of the plurality of strands of secondary air in the oxycombustion condition is greater than or equal to the momentum of the lowermost strand of the plurality of strands of secondary air in the air combustion condition.

Preferably, under the oxygen-enriched combustion working condition, the primary air is in a plurality of strands, the secondary air is in a plurality of strands, an included angle α between a jet center line of the primary air and a jet center line of the secondary air, which are opposite in the vertical direction, is greater than or equal to 5 degrees and less than or equal to 20 degrees, preferably, an included angle α between a jet center line of the primary air and a jet center line of the secondary air, which are opposite in the vertical direction, is greater than or equal to 7 degrees and less than or equal to 15 degrees, and preferably, under the oxygen-enriched combustion working condition, the ratio of the momentum moment of the primary air to the momentum moment of the secondary air is (0.6-0.9): 1.

Preferably, under the oxygen-enriched combustion working condition, the primary air is tangent to a first circumference, the secondary air is tangent to a second circumference, the circle center of the first circumference and the circle center of the second circumference are located on the same vertical line, the included angle α is calculated according to a formula (I),

wherein l is the width of the hearth, d is the depth of the hearth, and R₂Is the radius of the second circle, m₁Is the mass flow of the primary air, m₂Is the mass flow of the secondary air, v₁Is the velocity of the primary wind, v₂And the MR is the ratio of the momentum moment of the primary air to the momentum moment of the secondary air under the oxygen-enriched combustion working condition.

Drawings

FIG. 1 is a schematic view of a partial structure of a boiler according to an embodiment of the present invention;

FIG. 2 is a schematic view of a partial structure of a boiler according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of a boiler according to an embodiment of the present invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.

The invention provides an air distribution method of a boiler. The air distribution method of the boiler comprises the following steps: under the oxygen-enriched combustion working condition, primary air and secondary air are provided to a hearth of the boiler, the primary air rotates in one of a clockwise direction and a counterclockwise direction in the hearth, and the secondary air rotates in the other of the clockwise direction and the counterclockwise direction in the hearth. That is, under the condition of oxygen-enriched combustion, the rotation direction of the primary air is opposite to that of the secondary air.

According to the air distribution method of the boiler, the rotating direction of the primary air is opposite to the rotating direction of the secondary air under the oxygen-enriched combustion working condition, so that the rotating strength of airflow (main airflow) in a hearth of the boiler can be reduced, and further, the residual rotation of the airflow at an outlet of the hearth can be eliminated. Therefore, the smoke speed deviation and the smoke temperature deviation existing in the horizontal flue of the boiler can be eliminated, so that the heat transfer efficiency can be ensured, the operation cost of the boiler is greatly reduced, and the boiler can be safely operated.

Moreover, the primary air and the secondary air can be oppositely collided by enabling the rotating direction of the primary air to be opposite to that of the secondary air, and then the fuel flow can be more intensively mixed in the middle of the hearth, so that the combustion and the burnout of the fuel are facilitated. Thereby, the fuel can be utilized more sufficiently and more effectively, so that the operating cost of the boiler can be further reduced.

Therefore, by using the air distribution method of the boiler according to the embodiment of the invention, the heat transfer efficiency can be ensured, the operation cost of the boiler can be greatly reduced, and the boiler can be safely operated.

Preferably, in the oxycombustion condition, the air distribution method may further include stopping the supply of the over-fire air into the furnace. This ensures a volumetric flow of gas into the burner, which is advantageous for the organization of the flow field in the furnace chamber.

In one embodiment of the present invention, the air distribution method may further include the steps of: under an air combustion condition, primary air and secondary air are provided to a furnace of the boiler, the primary air rotates in the other one of the clockwise direction and the counterclockwise direction within the furnace, and the secondary air rotates in the other one of the clockwise direction and the counterclockwise direction within the furnace. In other words, the primary air rotates in the same direction as the secondary air during air combustion conditions.

Under the air combustion working condition, because the air quantity is sufficient, a part of the secondary air can be sprayed into the hearth in an over-fire air mode, the over-fire air can be reversely cut with the airflow in the hearth, namely, the rotation direction of the over-fire air is opposite to that of the airflow in the hearth, and therefore the residual rotation of the airflow at the outlet of the hearth can be eliminated.

Wherein, under the oxycombustion condition, the primary air may be tangent to the first circumference C1 in the one of the clockwise and counterclockwise directions, and the secondary air may be tangent to the second circumference C2 in the other of the clockwise and counterclockwise directions. The secondary air may be tangential to the second circumference C2 in the other of the clockwise and counterclockwise directions under air combustion conditions.

Oxygen-enriched gas (oxygen volume percent is more than or equal to 95%) separated from the air separation device is divided into two portions of VO1 and VO2, the recirculated flue gas is also divided into two portions of VRFG1 and VRFG2, VO1 is mixed with VRFG1 as the primary air, and VO2 is mixed with VRFG2 as the secondary air. The flue gas circulation rate can be adjusted to ensure that the partial pressure of oxygen entering the furnace and VO/(VO + VRFG) are between 0.23 and 0.30. An amount of oxygen may be premixed in the primary air by an oxygen injector so that VO1/(VO1+ VRFG1) is between 0.10-0.30. The recycling flue gas refers to flue gas recycled from a dust remover or a flue gas condenser, the flue gas recycling ratio refers to the ratio of the total volume flow of the recycling flue gas to the total volume flow of wet flue gas at the outlet of the hearth, and the partial pressure of oxygen entering the hearth refers to the sum of the volume of the recycling flue gas and the total volume of the oxygen.

The center of the first circle C1, the center of the second circle C2, and the center of the third circle may be located on the same vertical line. Preferably, the center of the first circumference C1, the center of the second circumference C2, and the center of the third circumference may be located on a vertical center line of the furnace of the boiler.

The momentum of the primary air under the oxycombustion condition may be equal to the momentum of the primary air under the air combustion condition, i.e., the momentum of the primary air may remain unchanged before and after the switching condition.

The ratio of the wind speed of the primary wind under the oxycombustion condition to the wind speed of the primary wind under the air combustion condition may be (0.8-0.9): 1. in other words, the velocity of the primary air at the oxycombustion condition may be reduced by 10% -20% compared to the velocity of the primary air at the air combustion condition.

Preferably, the primary air may be a plurality of strands, and the secondary air may be a plurality of strands, and a momentum of a lowermost one of the plurality of strands of the secondary air in the oxycombustion condition is equal to or greater than a momentum of the lowermost one of the plurality of strands of the secondary air in the air combustion condition. Therefore, the lifting effect of the secondary air positioned at the lowest part under the oxygen-enriched combustion working condition can be enhanced.

Specifically, a plurality of the primary winds may constitute a plurality of the primary winds, each of the primary winds may include a plurality of the primary winds, a plurality of the secondary winds may constitute a plurality of the secondary winds, and each of the secondary winds may include a plurality of the secondary winds. Wherein, the momentum of each secondary air of the layer which is positioned at the lowest in the plurality of layers of secondary air under the oxygen-enriched combustion working condition is more than or equal to the momentum of each secondary air of the layer which is positioned at the lowest in the plurality of layers of secondary air under the air combustion working condition.

Under the oxygen-enriched combustion working condition, the ratio of the momentum of the secondary air except the secondary air positioned at the lowest part to the momentum of the primary air is (1-5): 1, under the air combustion condition, the ratio of the momentum of the secondary air except the secondary air positioned at the lowest part to the momentum of the primary air is (1-5): 1. preferably, in the oxycombustion condition, the ratio of the momentum of the secondary air to the momentum of the primary air, except for the secondary air located lowermost, is (1.5-4.2): 1, under the air combustion condition, the ratio of the momentum of the secondary air except the secondary air positioned at the lowest part to the momentum of the primary air is (1.5-4.2): 1.

for example, when the fuel is anthracite or lean coal, under the oxygen-rich combustion condition and the air combustion condition, the ratio of the momentum of the secondary air to the momentum of the primary air, except for the secondary air positioned at the lowest part, is (3-4.2): 1; when the fuel is bituminous coal, under the oxygen-enriched combustion working condition and the air combustion working condition, the ratio of the momentum of the secondary air except the secondary air positioned at the lowest part to the momentum of the primary air is (1.5-3.5): 1; when the fuel is lignite, under the oxygen-enriched combustion working condition and the air combustion working condition, the ratio of the momentum of the secondary air except for the secondary air positioned at the lowest part to the momentum of the primary air is (2-3): 1.

preferably, the momentum of each of the primary winds is equal to each other in the oxycombustion condition and the air combustion condition.

Preferably, under the oxygen-enriched combustion condition, the ratio of the momentum moment of the primary air to the momentum moment of the secondary air is (0.6-0.9): 1. more preferably, the ratio of the moment of momentum of each of the primary winds to the moment of momentum of each of the secondary winds is (0.6-0.9): 1.

because the momentum moment of the primary air is smaller than the momentum moment of the secondary air, the rotation direction of the airflow in the hearth is dominated by the secondary air, namely the rotation direction of the airflow in the hearth is the same as the rotation direction of the secondary air. Moreover, the radius of the second circumference C2 is larger than that of the first circumference C1, namely, the secondary air is positioned between the primary air and the wall surface of the hearth, so that the effect of air-wrapped powder can be formed, and the ash and slag accumulation on the wall surface of the hearth can be greatly avoided, thereby being beneficial to combustion.

As shown in fig. 3, the included angle α between the jet center line of the primary wind and the jet center line of the secondary wind in the up-down direction may be greater than or equal to 5 degrees and less than or equal to 20 degrees, preferably, the included angle α between the jet center line of the primary wind and the jet center line of the secondary wind in the up-down direction is greater than or equal to 7 degrees and less than or equal to 15 degrees.

Specifically, the multiple strands of the primary air of the multiple layers of the primary air can be opposite to each other in the up-down direction, the multiple strands of the secondary air of the multiple layers of the secondary air can be opposite to each other in the up-down direction, and the multiple strands of the primary air of each layer of the primary air and the multiple strands of the secondary air of each layer of the secondary air can be opposite to each other in the up-down direction.

Under the oxygen-enriched combustion condition, the primary air can be tangent to a first circumference, the secondary air can be tangent to a second circumference, the circle center of the first circumference and the circle center of the second circumference can be located on the same vertical line, the included angle α can be calculated according to the formula (I),

wherein l is the width (meter) of the hearth, d is the depth (meter) of the hearth, and R₂Is the radius (m) of the second circumference₁For the mass flow (please provide unit) of the primary air, m₂For the mass flow (please provide unit) of the secondary air, v₁Is the velocity (m/s), v, of the primary wind₂The velocity (m/s) of the secondary air, and the MR is the ratio of the momentum moment of the primary air to the momentum moment of the secondary air under the oxygen-enriched combustion condition.

The included angle α may thus be calculated from the MR, specifically, each of the primary winds may be tangent to the first circumference and each of the secondary winds may be tangent to the second circumference.

Under the oxygen-enriched combustion condition, the peroxide coefficient of each of the primary air and the secondary air is greater than or equal to 1.05 and less than or equal to 1.5. Preferably, the peroxide coefficient of each of the primary air and the secondary air is greater than or equal to 1.1 and less than or equal to 1.3. Wherein the peroxide coefficient is a ratio of the amount of oxygen supplied converted to coal powder per unit weight to the amount of oxygen required for complete combustion of coal powder per unit weight.

The boiler 10 according to an embodiment of the present invention is described below with reference to the accompanying drawings. As shown in fig. 1 to 3, the boiler 10 according to the embodiment of the present invention includes a furnace body 110, a plurality of first burners 120, and a plurality of second burners 130.

The furnace body 110 has a furnace 111 therein. A plurality of first burners 120 are provided on the furnace body 110 at intervals in the circumferential direction of the furnace body 110 (i.e., the circumferential direction of the furnace 111), each first burner 120 has a primary air jet, and a jet center line L1 of the plurality of primary air jets is tangent to the first circumference C1 in one of the clockwise direction and the counterclockwise direction. A plurality of second burners 130 are provided on the furnace body 110 at intervals in the circumferential direction of the furnace body 110, each second burner 130 having a secondary air jet, a jet center line L2 of the plurality of secondary air jets being tangent to the second circumference C2 in the other of the clockwise direction and the counterclockwise direction.

The boiler 10 according to the embodiment of the present invention can make the rotation direction of the primary air injected from the first burner 120 opposite to the rotation direction of the secondary air injected from the second burner 130 under the oxygen-enriched combustion condition by making the jet center line L1 of the plurality of primary air jets tangent to the first circumference C1 in one of the clockwise direction and the counterclockwise direction and making the jet center line L2 of the plurality of secondary air jets tangent to the second circumference C2 in the other of the clockwise direction and the counterclockwise direction, so that the rotation intensity of the air flow (body air flow) inside the furnace 111 can be reduced, and thus the residual rotation of the air flow at the outlet of the furnace 111 can be eliminated. Thereby, the deviation of the smoke velocity and the deviation of the smoke temperature existing in the horizontal flue of the boiler 10 can be eliminated, so that not only the heat transfer efficiency can be ensured, the operation cost of the boiler 10 can be greatly reduced, but also the boiler 10 can be safely operated.

Moreover, by making the rotation direction of the primary air opposite to that of the secondary air, the primary air and the secondary air can be collided, and the fuel flow can be mixed more intensively in the middle of the furnace 111, so as to facilitate the combustion and the burnout of the fuel. Whereby the fuel can be utilized more fully and more efficiently, so that the operating costs of the boiler 10 can be further reduced.

Therefore, the boiler 10 according to the embodiment of the present invention has the advantages of high heat transfer efficiency, low operation cost, high safety, etc.

As shown in fig. 1 to 3, a boiler 10 according to an embodiment of the present invention may include a furnace body 110, a plurality of first burners 120, and a plurality of second burners 130.

The furnace body 110 may have a furnace 111 therein. A plurality of first burners 120 may be provided on the furnace body 110 at intervals in the circumferential direction of the furnace body 110, each first burner 120 may have a primary air port, a plurality of second burners 130 may be provided on the furnace body 110 at intervals in the circumferential direction of the furnace body 110, and each second burner 130 may have a secondary air port. Whereby the boiler 10 may have a plurality of the primary air jets and a plurality of the secondary air jets.

The jet centerlines L1 of the primary air jets may be tangent to the first circumference C1 in one of a clockwise direction and a counter-clockwise direction, and the jet centerlines L2 of the secondary air jets may be tangent to the second circumference C2 in the other of the clockwise direction and the counter-clockwise direction.

As shown in FIG. 1, in one embodiment of the present invention, the boiler 10 may further include at least one third burner 140, the third burner 140 may be provided on the furnace body 110, and the third burner 140 may have an over-fire air nozzle. Each of the first burners 120 may be movably provided on the furnace body 110 between a tangential position and a reverse tangential position.

Wherein the jet center line L1 of the primary air jets of the first plurality of burners 120 located at the tangential position may be tangent to the third circumference in the other of the clockwise direction and the counterclockwise direction, the jet center line L1 of the primary air jets of the first plurality burners 120 located at the anti-tangential position may be tangent to the first circumference C1 in the one of the clockwise direction and the counterclockwise direction, and the jet center line of the over-fired air jets may be tangent to the fourth circumference in the one of the clockwise direction and the counterclockwise direction.

Therefore, the oxygen-enriched combustion working condition can be implemented by using the boiler 10, and the air combustion working condition can be implemented by using the boiler 10, so that the application range of the boiler 10 can be expanded, the operation cost can be further reduced, and part of carbon dioxide can be trapped more easily.

Specifically, when the boiler 10 is in the oxycombustion condition, the third burners 140 are in the closed state, each first burner 120 is located at the reversal position, the first burner 120 injects the primary air into the furnace 111, and the second burner 130 injects the secondary air into the furnace 111, the rotation direction of the primary air is opposite to that of the secondary air, so as to eliminate the residual rotation of the air flow at the outlet of the furnace 111.

When the boiler 10 is in the air combustion condition, each first burner 120 is located at the tangential position, the first burner 120 injects the primary air into the furnace 111, and the second burner 130 injects the secondary air into the furnace 111, and the rotation direction of the primary air is the same as the rotation direction of the secondary air. The third burner 140 is in an open state to inject over-fired air, which rotates in a direction opposite to the direction of rotation of the primary air and the direction of rotation of the secondary air, so as to eliminate the residual rotation of the airflow at the outlet of the furnace 111.

As shown in fig. 1, the third burner 140 may be located above the first and second burners 120 and 130. The third burners 140 may be plural, the plural third burners 140 may be provided on the furnace body 110 at intervals in the circumferential direction of the furnace body 110, and the jet center line of the over-fire air jets of the plural third burners 140 may be tangent to the fourth circumference in the one of the clockwise direction and the counterclockwise direction.

Preferably, the third burner 140 may be located above the second burner 130 (the uppermost second burner 130), and the third burner 140 may be located below the flare angle of the boiler 10. In other words, the third burner 140 may be located between the second burner 130 (the uppermost second burner 130) and the flare angle of the boiler 10 in the up-down direction. More preferably, the distance between the third burner 140 and the second burner 130 positioned uppermost may be substantially equal to the distance between the third burner 140 and the flare angle of the boiler 10.

As shown in fig. 2 and 3, in one example of the present invention, the center of the first circumference C1 and the center of the second circumference C2 may be located on the same vertical line. Preferably, the center of the first circumference C1 and the center of the second circumference C2 may be located on the vertical center line of the furnace 111. The radius of the first circumference C1 may be less than the radius of the second circumference C2.

In some examples of the present invention, as shown in fig. 1 to 3, the plurality of first burners 120 and the plurality of second burners 130 may be opposed to each other in the up-down direction, and the angle α between the projection of the jet center line L2 of the second burners 130 opposed to each other in the up-down direction and the jet center line L1 of the first burners 120 located at the position of the tangency on the horizontal plane may be 5 degrees or more and 20 degrees or less, whereby the structure of the boiler 10 may be made more reasonable.

As shown in FIG. 3, for example, the first burner 120 is opposite to the first second burner 130 in the up-down direction, and the first burner 120 is located at the position of the tangency, wherein the projection of the jet center line L1 of the first burner 120 on the horizontal plane is a first straight line L3, the projection of the jet center line L2 of the second first burner 130 on the horizontal plane is a first straight line L4, and the included angle α between L3 and L4 may be greater than or equal to 5 degrees and less than or equal to 20 degrees.

Preferably, the included angle α between the jet center line L2 of the second burner 130 and the projection of the jet center line L1 of the first burner 120 located at the undercut position on the horizontal plane may be greater than or equal to 7 degrees and less than or equal to 15 degrees, thereby making the structure of the boiler 10 more reasonable.

As shown in fig. 1, the plurality of first burners 120 may constitute a plurality of first burner groups, and the plurality of first burner groups may be arranged to be spaced apart in the up-down direction. Each of the first burner groups may include a plurality of first burners 120, and the plurality of first burners 120 of each of the first burner groups may be provided on the furnace body 110 at intervals in a circumferential direction of the furnace body 110. The plurality of second burners 130 may constitute a plurality of second burner groups, and the plurality of second burner groups may be spaced apart in the up-down direction. Each of the second burner groups may include a plurality of second burners 130, and the plurality of second burners 130 of each of the second burner groups may be provided on the furnace body 110 at intervals in a circumferential direction of the furnace body 110.

Preferably, as shown in fig. 1, a plurality of first burners 120 of a plurality of the first burner groups and a plurality of second burners 130 of a plurality of the second burner groups may be opposite to each other in an up-down direction to form a multi-row burner. Whereby each column of burners may comprise a plurality of first burners 120 and a plurality of third burners 140.

More preferably, a plurality of the first burner groups and a plurality of the second burner groups are alternately arranged in the vertical direction, as shown in fig. 1. The lowermost one of the plurality of first burner groups and the plurality of second burner groups may be the second burner group, and the uppermost one of the plurality of first burner groups and the plurality of second burner groups may be the second burner group. In other words, the plurality of first burners 120 and the plurality of third burners 140 of each burner may be alternately arranged, the lowermost burner of each burner may be the second burner 130, and the uppermost burner of each burner may be the second burner 130.

The third burner 140 may be plural, and a plurality of the third burners 140 may be provided on the furnace body 110 at intervals in the circumferential direction of the furnace body 110. Preferably, a plurality of the third burners 140, a plurality of the first burners 120 of the first burner group, and a plurality of the second burners 130 of the second burner group may be opposite to each other in an up-down direction to form a multi-row burner. Whereby each column of burners may comprise one third burner 140, a plurality of first burners 120 and a plurality of second burners 130.

As shown in fig. 2, in a specific example of the present invention, each of the first burner groups may include four first burners 120, the four first burners 120 of each of the first burner groups may be disposed at four corners of the furnace body 110 in a one-to-one correspondence, each of the second burner groups may include four second burners 130, and the four second burners 130 of each of the second burner groups may be disposed at four corners of the furnace body 110 in a one-to-one correspondence.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be considered limiting of the invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; may be mechanically coupled, may be electrically coupled or may be in communication with each other; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.

Claims (16)

1. A boiler, characterized in that it comprises:

the furnace body is internally provided with a hearth;

a plurality of first burners provided on the furnace body at intervals in a circumferential direction of the furnace body, each of the first burners having a primary air port, each of the first burners being provided on the furnace body movably between a tangential position and a reverse tangential position, wherein in the reverse tangential position, a jet center line of the plurality of primary air ports is tangent to a first circumference in one of a clockwise direction and a counterclockwise direction;

the second burners are arranged on the furnace body at intervals along the circumferential direction of the furnace body, each second burner is provided with a secondary air nozzle, and the jet flow central line of the secondary air nozzles is tangent to a second circumference along the other one of the clockwise direction and the anticlockwise direction; and

at least one third burner, the third burner is arranged on the furnace body, the third burner is provided with an over-fire air nozzle, the boiler can selectively implement oxygen-enriched combustion working condition and air combustion working condition, wherein,

under the air combustion condition, the first burners are moved to the tangential position, and the jet flow center line of the primary air nozzle of each first burner is tangent to a third circumference along the other one of the clockwise direction and the anticlockwise direction;

under the oxygen-enriched combustion working condition, the first combustor moves to the reverse cutting position, and the supply of over-fire air to the hearth through the over-fire air nozzle is stopped;

a jet centerline of the over-fired air jets is tangent to a fourth circumference in the one of the clockwise and counter-clockwise directions.

2. The boiler according to claim 1, wherein a center of the first circumference and a center of the second circumference are located on a same vertical line, and a radius of the first circumference is smaller than a radius of the second circumference.

3. The boiler according to claim 2, wherein the center of the first circumference and the center of the second circumference are located on a vertical center line of the furnace.

4. The boiler according to claim 1, wherein the plurality of first burners are opposed to the plurality of second burners in one-to-one manner in the up-down direction, and an angle α between a jet centerline of the second burners opposed in the up-down direction and a projection of the jet centerline of the first burners located at the anti-tangential position on a horizontal plane is equal to or greater than 5 degrees and equal to or less than 20 degrees.

5. The boiler according to claim 4, wherein an angle α between a jet centerline of the second burner and a jet centerline of the first burner at the undercut position, which are opposite in the up-down direction, is 7 degrees or more and 15 degrees or less.

6. The boiler according to claim 1,

the first burners form a plurality of first burner groups, the first burner groups are arranged at intervals in the vertical direction, each first burner group comprises a plurality of first burners, and the first burners of each first burner group are arranged on the furnace body at intervals in the circumferential direction of the furnace body;

the plurality of second burners constitute a plurality of second burner groups, the plurality of second burner groups are arranged at intervals in the vertical direction, each of the second burner groups includes a plurality of second burners, and the plurality of second burners of each of the second burner groups are arranged on the furnace body at intervals in the circumferential direction of the furnace body.

7. The boiler according to claim 6, wherein a plurality of the first burners of a plurality of the first burner groups and a plurality of the second burners of a plurality of the second burner groups are opposed to each other in an up-down direction to form a plurality of rows of burners.

8. The boiler according to claim 6, wherein a plurality of the first burner groups and a plurality of the second burner groups are alternately arranged in an up-down direction, and a lowermost one of the plurality of the first burner groups and the plurality of the second burner groups is the second burner group, and an uppermost one of the plurality of the first burner groups and the plurality of the second burner groups is the second burner group.

9. The boiler according to claim 6, wherein the third burners are plural, a plurality of the third burners are provided on the furnace body at intervals in a circumferential direction of the furnace body, and the plural third burners, the plural first burners of the plural first burner groups, and the plural second burners of the plural second burner groups are opposed to each other in an up-down direction so as to form plural rows of burners.

10. The boiler according to claim 6, wherein each of the first burner groups includes four of the first burners, the four of the first burners of each of the first burner groups are disposed at four corners of the furnace body in a one-to-one correspondence, each of the second burner groups includes four of the second burners, and the four of the second burners of each of the second burner groups are disposed at four corners of the furnace body in a one-to-one correspondence.

11. A method of air distribution for a boiler according to any one of claims 1 to 10, characterized by comprising the steps of:

under the working condition of oxygen-enriched combustion, providing primary air and secondary air to a hearth of the boiler, and stopping providing over-fire air to the hearth, wherein the primary air rotates in one of a clockwise direction and an anticlockwise direction in the hearth, and the secondary air rotates in the other of the clockwise direction and the anticlockwise direction in the hearth;

under the air combustion working condition, over-fire air, primary air and secondary air are provided for a hearth of the boiler, the primary air rotates along the other one of the clockwise direction and the anticlockwise direction in the hearth, the secondary air rotates along the other one of the clockwise direction and the anticlockwise direction in the hearth, and the over-fire air rotates along the one of the clockwise direction and the anticlockwise direction in the hearth.

12. A method according to claim 11, wherein the momentum of the primary air under the oxycombustion conditions is equal to the momentum of the primary air under the air combustion conditions, and the ratio of the wind speed of the primary air under the oxycombustion conditions to the wind speed of the primary air under the air combustion conditions is (0.8-0.9): 1.

13. the air distribution method according to claim 12, wherein the primary air is a plurality of strands, the secondary air is a plurality of strands, and a momentum of a lowermost one of the plurality of strands of the secondary air under the oxycombustion condition is equal to or greater than a momentum of a lowermost one of the plurality of strands of the secondary air under the air combustion condition.

14. The air distribution method according to claim 11, wherein under the oxygen-enriched combustion condition, the primary air is in a plurality of strands, the secondary air is in a plurality of strands, and an included angle α between a jet center line of the primary air and a jet center line of the secondary air, which are opposite in the up-down direction, is greater than or equal to 5 degrees and less than or equal to 20 degrees.

15. A method according to claim 14, wherein, in the oxycombustion condition, the ratio of the moment of momentum of the primary air to the moment of momentum of the secondary air is (0.6-0.9): 1.

16. the air distribution method of claim 14, wherein in the oxycombustion condition, the primary air is tangential to a first circumference, the secondary air is tangential to a second circumference, the center of the first circumference and the center of the second circumference are on the same vertical line, the included angle α is calculated according to formula (I),

wherein l is the width of the hearth, d is the depth of the hearth, and R₂Is the radius of the second circle, m₁Is the mass flow of the primary air, m₂Is the mass flow of the secondary air, v₁Is the velocity of the primary wind, v₂And the MR is the ratio of the momentum moment of the primary air to the momentum moment of the secondary air under the oxygen-enriched combustion working condition.

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