Stable combustion burner and design control method thereof

Abstract

The invention discloses a stable combustion burner and a design control method thereof. The stable combustion burner comprises a burner sleeve, and a pulverized coal burner is arranged in the burner sleeve; an air supply unit is arranged on the outer side of the combustor sleeve, the air supply unit comprises a cooling air sleeve arranged on the outer side of the combustor in a sleeving mode, a second-stage sleeve is further arranged on the inner side of the cooling air sleeve, and a plurality of stable combustion parts are arranged on a third circulation channel in a non-uniform distribution mode; a plurality of first temperature measuring points for measuring the wall temperature of the combustor sleeve are arranged on the inner side of the combustor sleeve; a plurality of second temperature measuring points used for measuring the wall temperature of the secondary sleeve are arranged on the inner side of the secondary sleeve and located in front of the combustor sleeve. The two stages of combustor sleeves are arranged, it is guaranteed that pulverized coal is fully combusted in the combustor sleeves, and the phenomenon of flameout or excessive combustion is avoided.

Description

Technical Field

[0001] The present application relates to a stable combustion burner and a design and control method thereof. Background Art

[0002] With the continuous growth of new energy installed capacity, the flexibility requirements of coal-fired thermal power units are getting higher and higher. The peak load is getting lower and lower. Under the requirements of unit flexibility transformation, the requirements for boiler low-load combustion stability are also getting higher and higher, requiring the boiler to achieve stable combustion under extremely low load conditions.

[0003] Traditional plasma and oxygen-rich micro-oil burners can no longer meet the current requirements of deep peak regulation and low-load stable combustion of the units. There will always be more or less problems such as burner coking, overheating and burning, inability to remove oil, etc., which will affect the safety and stability of equipment operation.

[0004] Therefore, in view of the existing technologies and related technical routes on the market, combined with the needs of low-load stable combustion of the unit under the actual environment, it has become an urgent problem to study a stable combustion burner with built-in anti-coking function based on the traditional burner. Summary of the invention

[0005] In order to solve the above problems, the present application proposes a stable combustion burner on the one hand, including a burner sleeve, a pulverized coal burner is arranged in the burner sleeve; an air supply unit is arranged on the outer side of the burner sleeve, the air supply unit includes a cooling air sleeve sleeved on the outer side of the burner, and a secondary sleeve is also arranged on the inner side of the cooling air sleeve, and an intermediate spacing sleeve is arranged between the cooling air sleeve and the secondary sleeve so that the air passes through the first circulation channel between the cooling air sleeve and the intermediate spacing sleeve, the second circulation channel between the intermediate spacing sleeve and the secondary sleeve, and the third circulation channel between the secondary sleeve and the burner sleeve in sequence, and then is connected with the space on the side of the burner sleeve away from the pulverized coal burner; a plurality of stable combustion parts are unevenly arranged on the third circulation channel; a plurality of first temperature measuring points for measuring the wall temperature of the burner sleeve are arranged on the inner side of the burner sleeve; a plurality of second temperature measuring points for measuring the wall temperature of the secondary sleeve are arranged on the inner side of the secondary sleeve, and the second temperature measuring points are located in front of the burner sleeve. The present application is provided with a two-stage burner sleeve, and a cooling air sleeve is arranged on the outside of the burner sleeve. According to the coal powder and coal quality of the fuel and the operating conditions of the burner, the burner can adjust the wall temperature of the first-stage burner sleeve and the wall temperature of the second-stage burner sleeve by changing the air volume in the cooling air sleeve, thereby ensuring the full combustion of the coal powder in the burner sleeve without causing flameout or over-combustion. A combustion stabilizing portion is designed at the position where the air is introduced into the front part of the burner sleeve from the second-stage sleeve to enhance the ignition performance of the burner. Since no combustion stabilizing teeth are designed at the lower part, the purging effect of the second-stage sleeve on the lower part can be improved to avoid coking, slagging and other problems at the burner nozzle. Temperature measuring points are respectively arranged at the burner sleeve and the burner sleeve outlet position and the internal position of the second-stage sleeve, and the real-time temperature changes are reflected by specific measuring points, providing a real-time basis for adjusting the fuel amount and air volume.

[0006] Preferably, the end of the cooling air sleeve away from the pulverized coal burner is arranged beyond the burner sleeve, and an outer end baffle is arranged at the end of the cooling air sleeve and the secondary sleeve away from the burner sleeve, the other end of the secondary sleeve extends into the inner side of the burner sleeve, and an annular inflow channel is formed at the end between the outer side of the secondary sleeve and the burner sleeve, the combustion stabilizing portion is arranged in the annular inflow channel, an inner end baffle is arranged between the cooling air sleeve and the burner sleeve, one end of the middle spacing sleeve is connected to the inner end baffle, and the other end of the middle spacing sleeve is spaced from the outer end baffle to form a first deflection channel, and a second deflection channel is formed between the secondary sleeve and the inner end baffle.

[0007] Preferably, there are no less than three combustion stabilizing parts and they are evenly distributed in the upper half of the annular inflow channel.

[0008] Preferably, an inner support plate is arranged inside the burner sleeve, the pulverized coal burner is fixedly arranged on the inner support plate, and a plurality of first auxiliary gas channels communicating with the burner sleeve are arranged on the inner support plate.

[0009] Preferably, a plurality of second auxiliary gas channels communicating with the second baffle channels are arranged at positions of the inner end baffle plates corresponding to the second baffle channels.

[0010] Preferably, the combustion stabilizing portion is a combustion stabilizing tooth.

[0011] Preferably, the pulverized coal burner includes an air-powder inlet, a conical tube with a gradually increasing cross-sectional area is arranged on one side of the air-powder inlet, an ignition oil gun extending into the conical tube is arranged in the middle of the air-powder inlet, and a swirler is arranged on the side of the conical tube away from the conical tube.

[0012] On the other hand, the present application also discloses a design and control method for a stable combustion burner, comprising the following steps:

[0013] First, determine the number of stable combustion parts according to the standard operating conditions of the stable combustion burner;

[0014] When the combustion stabilization burner control is performed, the air flow rates of the first auxiliary gas passage and the second auxiliary gas passage are controlled with respect to the first set temperature and the second set temperature.

[0015] Preferably, the number of the combustion stabilizing parts is designed as follows:

[0016] Obtain the standard calorific value H of the pulverized coal for the pulverized coal burner and the set pulverized coal introduction speed V m and the first air setting introduction speed V g1 ;

[0017] Get the second air setting introduction speed V in the cooling air jacket g2 ;

[0018] Obtain a first set temperature T1 of a first temperature measuring point and a second set temperature T2 of a second temperature measuring point;

[0019] The above data is used to perform trial calculations on the combustion stabilizing burner, and the maximum fluctuation Δt1 of the first set temperature within the set time, and the maximum fluctuation Δt2 of the second set temperature within the set time are obtained. The number of combustion stabilizing teeth is first set to 8. If Δt2<(Δt1 / 2), the number of combustion stabilizing teeth is set to 7 and 9 respectively, and the number of combustion stabilizing teeth that minimizes Δt2 is selected as the final number. If Δt2≥(Δt1 / 2), the number of combustion stabilizing teeth is set to [4, 12] in sequence, and the number of combustion stabilizing teeth that minimizes Δt2 is selected as the final number. The present application reduces the temperature fluctuation of the second temperature measuring point as much as possible by adjusting the number of combustion stabilizing teeth, thereby reducing the impact on the overall combustion while avoiding coking; on the other hand, it can play a positive role in promoting mixing.

[0020] Preferably, the combustion stabilizing burner is controlled as follows:

[0021] Obtain a first set temperature T1 and a second set temperature T2; and calculate a change rate LT1 of the first set temperature and a change rate LT2 of the second set temperature;

[0022] Calculate Δt=T1-T2 at the same time and the rate of change of Δt LΔt;

[0023] The V m 、V g1 、V g2 Determined according to combustion control conditions;

[0024] The flow rate V of the first auxiliary gas channel fg1 Determine as follows:

[0025] V fg1 =f(V fg1 )*(LT1 / LΔt)*V g1 ;

[0026] f(V fg1 ) is V determined by coal type experiment fg1 Related parameters:

[0027] The flow rate V of the second auxiliary gas channel fg2 Determine as follows:

[0028] V fg2 =f(V fg2 )*(LT2 / LΔt)*V g1 ;

[0029] f(V fg2 ) is V determined by coal type experiment fg2Related parameters. The present application adjusts the auxiliary gas volume through temperature changes by adjusting the flow rates of the first auxiliary gas channel and the second auxiliary gas channel, thereby ensuring the combustion stability of the stable combustion burner in the burner sleeve and avoiding coking in the secondary sleeve.

[0030] This application can bring the following beneficial effects:

[0031] 1. The present application is provided with a two-stage burner casing, and a cooling air casing is arranged outside the burner casing. According to the coal powder and coal quality of the fuel and the operating conditions of the burner, the burner can adjust the first-stage burner casing wall temperature and the second-stage burner casing wall temperature by changing the air volume in the cooling air casing, thereby ensuring the full combustion of the coal powder in the burner casing without flameout or excessive combustion.

[0032] 2. The present application reduces the temperature fluctuation of the second temperature measuring point as much as possible by adjusting the number of combustion stabilizing teeth, thereby reducing the impact on the overall combustion while avoiding coking; on the other hand, it can play a positive role in promoting mixing.

[0033] 3. The present application adjusts the auxiliary gas volume by adjusting the flow of the first auxiliary gas channel and the second auxiliary gas channel through temperature changes, thereby ensuring the combustion stability of the stable combustion burner in the burner sleeve and avoiding coking in the secondary casing. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0035] Figure 1 This is a schematic diagram of the structure of this application.

[0036] Figure 2 This is a side view of the structure of this application.

[0037] Figure 3 Schematic diagram of the flow chart of the control part designed for this application. DETAILED DESCRIPTION

[0038] In order to clearly illustrate the technical features of the present solution, the present application is described in detail below through specific implementation methods and in conjunction with the accompanying drawings.

[0039] For the structural part, such as Figure 1-2As shown, a stable combustion burner comprises a burner sleeve 1, in which a pulverized coal burner 2 is arranged; an air supply unit is arranged on the outside of the burner sleeve 1, and the air supply unit comprises a cooling air sleeve 3 sleeved on the outside of the burner, and a secondary sleeve 4 is also arranged on the inner side of the cooling air sleeve 3, and an intermediate spacing sleeve 5 is arranged between the cooling air sleeve 3 and the secondary sleeve 4 so that air passes through a first circulation channel 6 between the cooling air sleeve 3 and the intermediate spacing sleeve 5, a second circulation channel 7 between the intermediate spacing sleeve 5 and the secondary sleeve 4, and a third circulation channel 8 between the secondary sleeve 4 and the burner sleeve 1 in sequence, and then is connected with the space on the side of the burner sleeve 1 away from the pulverized coal burner 2.

[0040] The end of the cooling air sleeve 3 away from the pulverized coal burner 2 is arranged beyond the burner sleeve 1, and an outer end baffle 9 is arranged at the end of the cooling air sleeve 3 and the secondary sleeve 4 away from the burner sleeve 1. The other end of the secondary sleeve 4 extends into the inner side of the burner sleeve 1, and an annular inflow channel 10 is formed at the end between the outer side of the secondary sleeve 4 and the burner sleeve 1. A combustion stabilizing portion 11 is arranged in the annular inflow channel 10, and an inner end baffle 12 is arranged between the cooling air sleeve 3 and the burner sleeve 1. One end of the intermediate spacing sleeve 5 is connected to the inner end baffle 12, and the other end of the intermediate spacing sleeve 5 is spaced apart from the outer end baffle 9 to form a first baffle channel 13. A second baffle channel 14 is spaced apart between the secondary sleeve and the inner end baffle 12. The combustion stabilizing portions 11 are arranged unevenly; there are no less than 3 combustion stabilizing portions 11 and they are evenly arranged in the upper half of the annular inflow channel 10. An inner support plate 15 is arranged inside the burner sleeve 1, and the pulverized coal burner 2 is fixedly arranged on the inner support plate 15, and a plurality of first auxiliary gas channels 16 connected with the burner sleeve 1 are arranged on the inner support plate 15. A plurality of second auxiliary gas channels 17 connected with the second baffle channel 14 are arranged at the position of the inner end partition 12 corresponding to the second baffle channel 14. A plurality of first temperature measuring points 18 for measuring the wall temperature of the burner sleeve 1 are arranged inside the burner sleeve 1; a plurality of second temperature measuring points 19 for measuring the wall temperature of the secondary sleeve 4 are arranged inside the secondary sleeve 4, and the second temperature measuring points 19 are located in front of the burner sleeve 1. The stable combustion part 11 is a stable combustion tooth.

[0041] The pulverized coal burner 2 includes an air-powder inlet 20, a tapered tube 21 with a gradually increasing cross-sectional area is arranged on one side of the air-powder inlet 20, an ignition oil gun 22 extending into the tapered tube 21 is arranged in the middle of the air-powder inlet 20, and a swirler 23 is arranged on the side of the tapered tube 21 away from the tapered tube 21.

[0042] When the stable combustion burner is running, pulverized coal and the air carrying the pulverized coal are introduced into the pulverized coal burner 2, burned in the burner sleeve 1, and then flow outward into the secondary sleeve. At this time, air is supplemented, that is, the external air supply enters the front position of the burner sleeve 1 through the first circulation channel 6, the first deflection channel 13, the second circulation channel 7, the second deflection channel 14, and the third circulation channel 8 to mix and continue to burn; the stable combustion of pulverized coal in the burner sleeve 1 is ensured by controlling the flow rate of air in the first auxiliary gas channel, which can be reflected here by the temperature stability of the first temperature measuring point; the temperature at the second temperature measuring point is adjusted by controlling the flow rate of air in the second auxiliary gas channel to avoid coking and slagging in the outlet area.

[0043] For the design control part: Figure 3 As shown, the following steps are included:

[0044] S101 determines the number of stable combustion parts according to the standard operating conditions of the stable combustion burner;

[0045] The number of stable combustion parts is designed as follows:

[0046] Obtain the standard calorific value H of the pulverized coal for the pulverized coal burner and the set pulverized coal introduction speed V m and the first air setting introduction speed V g1 ;

[0047] Get the second air setting introduction speed V in the cooling air jacket g2 ;

[0048] Obtain a first set temperature T1 of a first temperature measuring point and a second set temperature T2 of a second temperature measuring point;

[0049] The above data are used to perform trial calculations on the stable combustion burner, and the maximum fluctuation Δt1 of the first set temperature within the set time, and the maximum fluctuation Δt2 of the second set temperature within the set time are obtained. The number of stable combustion parts is first set to 8. If Δt2<(Δt1 / 2), the number of stable combustion parts is set to 7 and 9 respectively, and the number of stable combustion parts that minimizes Δt2 is selected as the final number. If Δt2≥(Δt1 / 2), the number of stable combustion teeth is set to [4, 12] in sequence, and the number of stable combustion parts that minimizes Δt2 is selected as the final number.

[0050] The reason why the present application considers the influence of the number of stable combustion sections on temperature stability is that during use, temperature fluctuations can easily lead to coking and slagging in the outlet area, and the occurrence of coking and slagging will affect the temperature stability. When conducting the test, the present application selects 30 minutes after 1 hour of stable combustion as the test time, and provides coal powder and air in accordance with the standard requirements of the stable combustion burner, and does not input auxiliary air. The stable combustion sections are evenly distributed on the upper half, which is non-uniform compared to the whole.

[0051] When the combustion stabilization burner control is performed in S102, the air flow rates of the first auxiliary gas channel and the second auxiliary gas channel are controlled according to the first set temperature and the second set temperature.

[0052] The stable combustion burner is controlled as follows:

[0053] Obtain a first set temperature T1 and a second set temperature T2; and calculate a change rate LT1 of the first set temperature and a change rate LT2 of the second set temperature;

[0054] Calculate Δt=T1-T2 at the same time and the rate of change of Δt LΔt;

[0055] The V m 、V g1 、V g2 Determined according to combustion control conditions;

[0056] The flow rate V of the first auxiliary gas channel fg1 Determine as follows:

[0057] V fg1 =f(V fg1 )*(LT1 / LΔt)*V g1 ;

[0058] f(V fg1 ) is V determined by coal type experiment fg1 Related parameters:

[0059] The flow rate V of the second auxiliary gas channel fg2 Determine as follows:

[0060] V fg2 =f(V fg2 )*(LT2 / LΔt)*V g1 ;

[0061] f(V fg2 ) is V determined by coal type experiment fg2 Related parameters.

[0062] For f(V fg1 ) and f(Vfg2 ) is obtained as follows:

[0063] Supply the corresponding pulverized coal and air according to the requirements of the burner itself. After reaching the operating parameters, adjust V fg1 To adjust the first set temperature T1, when LT1 = 0, the initial flow rate V1 is obtained, f(V fg1 )=0.05*V1 / V g1 ;

[0064] Supply the corresponding pulverized coal and air according to the requirements of the burner itself. After reaching the operating parameters, adjust V fg2 To adjust the first set temperature T2, when LT2 = 0, the initial flow rate V2 is obtained, f(V fg2 )=0.1*V2 / V g2 ;

[0065] After obtaining the number of stable combustion parts, the structural part of the present application has been determined. After determining the mechanical structure part, the air flow in the first auxiliary gas channel and the second auxiliary gas channel is controlled by changing the first set temperature and the second set temperature. It should be noted that the flow in the two channels must be positive. If a negative value occurs, it means that the value is invalid, and the auxiliary gas is not introduced into the corresponding channel. After adopting the auxiliary gas flow control of the present application, the coking and slagging phenomena in the outlet area are greatly reduced, which in turn promotes temperature stability. Due to the reduction of coking and slagging time, the stable combustion time of the entire burner is increased from the original 25d to about 40d.

[0066] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included within the scope of the claims of the present application.

Claims

1. A stable combustion burner, characterized in that: It comprises a burner sleeve, in which a pulverized coal burner is arranged; an air supply unit is arranged on the outside of the burner sleeve, the air supply unit comprises a cooling air sleeve sleeved on the outside of the burner, a secondary sleeve is also arranged on the inside of the cooling air sleeve, and an intermediate spacing sleeve is arranged between the cooling air sleeve and the secondary sleeve so that air passes through the first flow channel between the cooling air sleeve and the intermediate spacing sleeve, the second flow channel between the intermediate spacing sleeve and the secondary sleeve, and the third flow channel between the secondary sleeve and the burner sleeve in sequence, and then is connected with the space on the side of the burner sleeve away from the pulverized coal burner; a plurality of combustion stabilizing parts are unevenly arranged on the third flow channel; The inner side of the burner sleeve is provided with a plurality of first temperature measuring points for measuring the wall temperature of the burner sleeve; the inner side of the secondary sleeve is provided with a plurality of second temperature measuring points for measuring the wall temperature of the secondary sleeve, and the second temperature measuring points are located in front of the burner sleeve.

2. A combustion-stabilizing burner according to claim 1, characterized in that: The end of the cooling air sleeve away from the pulverized coal burner is arranged beyond the burner sleeve, and an outer end baffle is arranged at the end of the cooling air sleeve and the secondary sleeve away from the burner sleeve. The other end of the secondary sleeve extends into the inner side of the burner sleeve, and an annular inflow channel is formed at the end between the outer side of the secondary sleeve and the burner sleeve. The stable combustion part is arranged in the annular inflow channel, and an inner end baffle is arranged between the cooling air sleeve and the burner sleeve. One end of the middle spacing sleeve is connected to the inner end baffle, and the other end of the middle spacing sleeve is spaced apart from the outer end baffle to form a first deflection channel. The second deflection channel is formed between the secondary sleeve and the inner end baffle.

3. A stable combustion burner according to claim 2, characterized in that: The number of the combustion stabilizing parts is no less than 3 and they are evenly distributed in the upper half of the annular inflow channel.

4. A stable combustion burner according to claim 3, characterized in that: An inner support plate is arranged inside the burner sleeve, the pulverized coal burner is fixedly arranged on the inner support plate, and a plurality of first auxiliary gas channels communicating with the burner sleeve are arranged on the inner support plate.

5. A stable combustion burner according to claim 4, characterized in that: The inner end partition plate is provided with a plurality of second auxiliary gas channels connected with the second baffle channels at positions corresponding to the second baffle channels.

6. A combustion stabilizing burner as claimed in claim 2, characterized in that: The combustion stabilizing portion is a combustion stabilizing tooth.

7. A stable combustion burner according to claim 1, characterized in that: The pulverized coal burner includes an air-powder inlet, a tapered tube with a gradually increasing cross-sectional area is arranged on one side of the air-powder inlet, an ignition oil gun extending into the tapered tube is arranged in the middle of the air-powder inlet, and a swirler is arranged on the side of the tapered tube away from the tapered tube.

8. A design and control method for an anti-coking low-load stable combustion burner as claimed in claim 5, characterized in that: The steps include: First, determine the number of stable combustion parts according to the standard operating conditions of the stable combustion burner; When the combustion stabilization burner control is performed, the air flow rates of the first auxiliary gas passage and the second auxiliary gas passage are controlled with respect to the first set temperature and the second set temperature.

9. A design and control method for a stable combustion burner according to claim 8, characterized in that: The number of stable combustion parts is designed as follows: Obtain the standard calorific value H of the pulverized coal for the pulverized coal burner and the set pulverized coal introduction speed V m and the first air setting introduction speed V g1 ; Get the second air setting introduction speed V in the cooling air jacket g2 ; Obtain a first set temperature T1 of a first temperature measuring point and a second set temperature T2 of a second temperature measuring point; The above data are used to perform trial calculations on the stable combustion burner, and the maximum fluctuation Δt1 of the first set temperature within the set time, and the maximum fluctuation Δt2 of the second set temperature within the set time are obtained. The number of stable combustion teeth is first set to 8. If Δt2<(Δt1 / 2), the number of stable combustion teeth is set to 7 and 9 respectively, and the number of stable combustion teeth that minimizes Δt2 is selected as the final number. If Δt2≥(Δt1 / 2), the number of stable combustion teeth is set to [4, 12] in sequence, and the number of stable combustion teeth that minimizes Δt2 is selected as the final number.

10. A design and control method for a stable combustion burner according to claim 9, characterized in that: The stable combustion burner is controlled as follows: Obtain a first set temperature T1 and a second set temperature T2; and calculate a change rate LT1 of the first set temperature and a change rate LT2 of the second set temperature; Calculate Δt=T1-T2 at the same time and the rate of change of Δt LΔt; The V m 、V g1 、V g2 Determined according to combustion control conditions; The flow rate V of the first auxiliary gas channel fg1 Determine as follows: V fg1 =f(V fg1 )*(LT1 / LΔt)*V g1 ; f(V fg1 ) is V determined by coal type experiment fg1 Related parameters: The flow rate V of the second auxiliary gas channel fg2 Determine as follows: V fg2 =f(V fg2 )*(LT2 / LΔt)*V g1 ; f(V fg2 ) is V determined by coal type experiment fg2 Related parameters.

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