Front and rear wall opposed firing boiler and thermal generator set
By adjusting the interval of the burner layer in the front and rear wall hedging boilers, the problems of burning loss, coking and NOx emission exceeding the standard of burner nozzles are solved, and more stable furnace operation and lower NOx emissions are achieved.
Patent Information
- Application Number
- CN202411603246.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-11
- Publication Date
- 2025-03-14
AI Technical Summary
In actual operation, front and rear wall hedging boilers are prone to burning the nozzle of the burner, coking the burner nozzle area, and NOx emission exceeding the standard.
A front and rear wall hedging boiler is designed, and its furnace body includes a relatively arranged front wall and a rear wall. Both the front wall and the rear wall are provided with at least three layers of burner layers arranged spaced in the vertical direction, and the distance between the uppermost adjacent two layers of burner layers is greater than the distance between the lowermost adjacent two layers of burner layers.
By adjusting the interval of the burner layer, the continuous increase in the furnace temperature from bottom to top is avoided, the risk of burning and coking of the burner nozzle is reduced, and the generation and emission of NOx are reduced.
Smart Images
Figure CN119617400A_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to the technical field of front and rear wall opposed boilers, and in particular to a front and rear wall opposed boiler and a thermal power generator set. Background Art
[0002] The front and rear wall counter-boiler is a common boiler in thermal power generating units, which includes a front wall, a rear wall and two side walls located between the front wall and the rear wall. The front wall, the rear wall and the two side walls together enclose a furnace. Multiple layers of burners are arranged on the front wall and the rear wall. The nozzles of the burners on the front wall and the nozzles of the burners on the rear wall are both located in the furnace and face each other one by one. Coal powder and air are sprayed into the furnace through the nozzles of the burners on the front wall and the rear wall for counter-combustion.
[0003] However, during the actual operation of the front and rear wall opposed boilers in the related art, problems such as burnout of the burner nozzle, coking in the burner nozzle area, and excessive NOx emissions may occur. Summary of the invention
[0004] The purpose of the present invention is to provide a front and rear wall hedge boiler and a thermal power generator set to solve the above technical problems.
[0005] In order to achieve the above-mentioned object, according to one aspect of the present disclosure, a front and rear wall hedge boiler is provided, comprising a furnace body and a plurality of burners, wherein the furnace body comprises a front wall and a rear wall arranged opposite to each other, and at least three layers of burner layers arranged at intervals in a vertical direction are arranged on the front wall and the rear wall, and each layer of the burner layer comprises at least one burner; Among them, the distance between the two uppermost adjacent burner layers on the front wall is greater than the distance between the two lowermost adjacent burner layers, and the distance between the two uppermost adjacent burner layers on the rear wall is greater than the distance between the two lowermost adjacent burner layers.
[0006] Optionally, along the direction from top to bottom, the distance between every two adjacent layers of the burner layers on the front wall and the rear wall gradually decreases.
[0007] Optionally, the distance between any of the burner layers on the front wall and the rear wall and the adjacent burner layer above it is L1, and the distance between any of the burner layers on the front wall and the rear wall and the adjacent burner layer below it is L2, and the ratio of L1 to L2 is 1.25-2.
[0008] Optionally, the distance between any of the burner layers on the front wall and the rear wall and the adjacent burner layer above it is L1, and the distance between any of the burner layers on the front wall and the rear wall and the adjacent burner layer below it is L2, and the difference between L1 and L2 is 1300 mm to 2700 mm.
[0009] Optionally, the furnace body further includes a first side wall and a second side wall located between the front wall and the rear wall, the front wall, the rear wall, the first side wall and the second side wall together enclose a furnace, and the nozzle of each burner is located in the furnace; Each burner layer includes a plurality of burners spaced apart in a horizontal direction, the axis of the nozzle of the burner closest to the first side wall in each burner layer is deflected toward a direction away from the first side wall, and the axis of the nozzle of the burner closest to the second side wall in each burner layer is deflected toward a direction away from the second side wall.
[0010] Optionally, the angle between the axis of the nozzle of the burner closest to the first side wall in each burner layer and the first side wall is 5°~6°, and the angle between the axis of the nozzle of the burner closest to the second side wall in each burner layer and the second side wall is 5°~6°.
[0011] Optionally, the angle between the axis of the nozzle of the burner closest to the first side wall in each burner layer and the first side wall is 5°17', and the angle between the axis of the nozzle of the burner closest to the second side wall in each burner layer and the second side wall is 5°17'.
[0012] Optionally, the horizontal distance from the center of the nozzle of the burner closest to the first side wall in each burner layer to the first side wall is 4300mm~4800mm, and the horizontal distance from the center of the nozzle of the burner closest to the second side wall in each burner layer to the second side wall is 4300mm~4800mm.
[0013] Optionally, the distance between the uppermost two adjacent burner layers on the front wall and the rear wall is greater than the distance between any other two adjacent burner layers.
[0014] According to another aspect of the present disclosure, there is provided a thermal power generating set, comprising the above-mentioned front and rear wall opposed boiler.
[0015] Through the above technical scheme, the distance between the two uppermost adjacent burner layers is set to be greater than the distance between the two lowermost adjacent burner layers, so that the interval at which the flue gas in the furnace is heated by the two uppermost adjacent burner layers in the furnace during the rising process can be greater than the interval at which the flue gas in the furnace is heated by the two lowermost adjacent burner layers in the furnace, which is beneficial to avoid the temperature in the furnace from rising continuously from bottom to top, thereby helping to avoid the temperature of the upper area in the furnace from being heated to too high, and further helping to avoid the occurrence of burner nozzle burning, coking in the burner nozzle area, etc.
[0016] Moreover, the distance between the two uppermost adjacent burner layers is greater than the distance between the two lowermost adjacent burner layers, which is not only beneficial to avoid excessive temperature in local areas in the furnace (i.e., the upper area in the furnace), but also can increase the residence time of coal powder, improve the burnout degree of coal powder, increase NOx reduction in the furnace, and reduce the generation of NOx in the furnace, thereby helping to reduce the amount of NOx generated during coal powder combustion, and further helping to avoid excessive NOx emissions from front and rear wall hedge boilers.
[0017] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings: Figure 1 It is a front view of the front wall or rear wall of a front and rear wall hedge boiler provided in one embodiment of the present disclosure.
[0019] Figure 2 It is a horizontal cross-sectional view of a front and rear wall opposed boiler provided in one embodiment of the present disclosure.
[0020] Figure 3 It is a longitudinal cross-sectional view of the temperature field of a furnace provided in one embodiment of the present disclosure.
[0021] Figure 4 It is a longitudinal cross-sectional view of the velocity field of a furnace provided in one embodiment of the present disclosure.
[0022] Figure 5 It is a comparison diagram of the horizontal cross-section of the temperature field of the furnace of the front and rear wall opposed boiler provided in one embodiment of the present disclosure and the horizontal cross-section of the temperature field of the furnace of the front and rear wall opposed boiler in the prior art.
[0023] Figure 6 It is a comparison diagram of the horizontal cross-section of the CO concentration field in the furnace of the front and rear wall hedge boiler provided in one embodiment of the present disclosure and the horizontal cross-section of the CO concentration field in the furnace of the front and rear wall hedge boiler in the prior art.
[0024] Figure 7 It is a horizontal cross-sectional view of the screen bottom temperature field of the furnace provided in one embodiment of the present disclosure.
[0025] Description of Reference Numerals 10 - furnace body; 11 - front wall; 12 - rear wall; 13 - first side wall; 14 - second side wall; 15 - furnace; 20 - burner; 21 - axis of the burner nozzle; 30 - burner layer. DETAILED DESCRIPTION
[0026] The specific implementation of the present disclosure is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the present disclosure, and is not used to limit the present disclosure.
[0027] In this disclosure, unless otherwise stated, directional words such as "upper, lower, top, bottom, vertical, and horizontal" are generally defined as the upper, lower, top, bottom, vertical, and horizontal positions of the boiler in normal use when the front and rear walls are facing each other (for details, please refer to Figure 1 ), is only for the convenience of describing the present disclosure and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, a specific orientation structure and operation, and therefore cannot be understood as limiting the present disclosure. "Inside and outside" refer to the inside and outside of the corresponding component outline. In addition, the terms "first", "second", etc. used are to distinguish one element from another, and do not have order and importance.
[0028] In the description of the present disclosure, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "connect", "connected", and "installed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present disclosure can be understood according to specific circumstances.
[0029] After research, it was found that during the actual operation of the front and rear wall opposed boilers in the relevant technology, problems such as burner nozzle burning, coking in the burner nozzle area, and excessive NOx emissions will occur. The main reason is that the multi-layer burners of the front and rear wall opposed boilers are evenly spaced along the vertical direction on the front wall and the rear wall, and the air is sprayed into the furnace through the burner to form flue gas carrying combustion products (such as coal powder combustion products) that flows upward until it leaves the furnace. In the process of flowing upward, the flue gas will pass through the multi-layer burners and be heated multiple times, which causes the temperature in the furnace to continue to increase from bottom to top. In addition, due to the widespread problem of coal supply, the coal used in the actual operation of the front and rear wall opposed boilers often deviates from the designed coal type. When the calorific value of the coal used is high, the temperature of the upper area in the furnace will be heated to too high, resulting in burner nozzle burning, coking in the burner nozzle area, and excessive NOx emissions in this area.
[0030] In view of this, if Figures 1 to 7As shown, according to one aspect of the present disclosure, a front and rear wall opposed boiler is provided, including a furnace body 10 and a plurality of burners 20, the furnace body 10 includes a front wall 11 and a rear wall 12 arranged opposite to each other, the front wall 11 and the rear wall 12 are provided with at least three burner layers 30 arranged at intervals in the vertical direction, each burner layer 30 includes at least one burner 20, wherein the distance between the uppermost two adjacent burner layers 30 on the front wall 11 is greater than the distance between the lowermost two adjacent burner layers 30, and the distance between the uppermost two adjacent burner layers 30 on the rear wall 12 is greater than the distance between the lowermost two adjacent burner layers 30.
[0031] Setting the distance between the two uppermost adjacent burner layers 30 to be greater than the distance between the two lowermost adjacent burner layers 30 can ensure that the interval at which the flue gas in the furnace 15 is heated by the two uppermost adjacent burner layers 30 in the furnace 15 during the rising process is greater than the interval at which the flue gas in the furnace 15 is heated by the two lowermost adjacent burner layers 30 in the furnace 15. This helps to prevent the temperature in the furnace 15 from continuously increasing from bottom to top, thereby helping to prevent the temperature of the upper area in the furnace 15 from being heated to too high, and further helping to avoid the occurrence of burning of the burner nozzle 20, coking of the burner nozzle area 20, etc.
[0032] Moreover, the distance between the two uppermost adjacent burner layers 30 is greater than the distance between the two lowermost adjacent burner layers 30, which is not only beneficial for avoiding excessive temperature in a local area in the furnace 15 (i.e., the upper area in the furnace 15), but also can increase the residence time of the pulverized coal, improve the burnout degree of the pulverized coal, increase NOx reduction in the furnace 15, and reduce the generation of NOx in the furnace 15, thereby helping to reduce the amount of NOx generated during the combustion of pulverized coal, and further helping to avoid excessive NOx emissions from the front and rear wall hedge boilers.
[0033] In addition, the distance between the two uppermost adjacent burner layers 30 is greater than the distance between the two lowermost adjacent burner layers 30, which can reduce the temperature of the burnt air layer in the furnace 15, thereby helping to reduce the overall volumetric heat load of the combustion area in the furnace 15, and further helping to reduce the screen bottom temperature of the front and rear wall hedging boiler, avoiding damage to the screen superheater.
[0034] It should be noted that the platen superheater is an important component of the front and rear wall hedge boiler, which has the functions of reducing the flue gas temperature at the furnace 15 outlet and preventing slagging, and is usually located above multiple burner layers 30. The burnout air layer refers to the air injection layer located above the uppermost burner layer 30 in the boiler furnace 15.
[0035] It should also be noted that the NOx generated during the combustion of pulverized coal includes thermal NOx, rapid NOx and fuel NOx, wherein thermal NOx refers to NOx generated by oxidation of nitrogen in the air at high temperature, rapid NOx refers to NOx generated by the reaction of nitrogen in the air and hydrocarbon ions such as CH in the fuel during combustion, and fuel NOx refers to NOx generated by thermal decomposition of nitrogen-containing compounds in the fuel during combustion. Since the generation of thermal NOx is closely related to temperature, when the temperature is high enough, the generation of thermal NOx can account for 30% of the total NOx, and as the reaction temperature increases, its reaction rate increases exponentially. Therefore, by reducing the maximum value of the local area in the furnace 15, the thermal NOx generated during the combustion of pulverized coal can be reduced, thereby reducing the total amount of NOx generated during the combustion of pulverized coal.
[0036] In the present disclosure, the number of burner layers 30 can be set to a reasonable number of layers according to demand, for example, it can be set to three layers, four layers or five layers, and the present disclosure does not limit this.
[0037] Alternatively, if Figure 1 As shown, the distance between each two adjacent burner layers 30 on the front wall 11 and the rear wall 12 gradually decreases from top to bottom. Such an arrangement can gradually prolong the time for the flue gas in the furnace 15 to flow through different burner layers 30 during the rising process, thereby helping to avoid the temperature of the flue gas to continue to rise during the rising process, further reducing the maximum temperature in the furnace 15, and further helping to avoid the occurrence of burnout of the burner 20 nozzle, coking in the burner 20 nozzle area, etc., and helping to further reduce the NOx generated during the combustion of pulverized coal.
[0038] The present disclosure does not limit the specific value of the interval between any two adjacent combustion layers. As an implementation method, Figure 1 As shown, the distance between any burner layer 30 on the front wall 11 and the rear wall 12 and the adjacent burner layer 30 above is L1, and the distance between the adjacent burner layer 30 below is L2, and the ratio of L1 to L2 is 1.25 to 2. In this way, any burner layer 30 and the adjacent burner layers 30 above and below can be arranged at appropriate intervals, which is not only conducive to reducing the maximum temperature in the furnace 15, but also conducive to preventing the temperature in the furnace 15 from being too low and affecting the combustion of coal powder.
[0039] As an implementation method, Figure 1As shown, the distance between any burner layer 30 on the front wall 11 and the rear wall 12 and the adjacent burner layer 30 above is L1, and the distance between the adjacent burner layer 30 below is L2, and the difference between L1 and L2 is 1300mm~2700mm. In this way, any burner layer 30 and the adjacent burner layers 30 above and below can be arranged at appropriate intervals, which is not only conducive to reducing the maximum temperature in the furnace 15, but also conducive to preventing the temperature in the furnace 15 from being too low and affecting the combustion of coal powder.
[0040] Depend on Figure 3 The longitudinal section of the temperature field of the furnace 15 is shown. Figure 4 It can be seen from the longitudinal cross-section of the velocity field of the furnace 15 shown that when the interval between the burner layers 30 of the front and rear wall hedge boiler of the present invention is set according to the above-mentioned numerical value, a good aerodynamic field can be provided in the furnace 15, the flow field in the entire furnace 15 is better organized, and the flame fullness in the furnace 15 is good.
[0041] Alternatively, if Figure 2 As shown, the furnace body 10 also includes a first side wall 13 and a second side wall 14 located between the front wall 11 and the rear wall 12. The front wall 11, the rear wall 12, the first side wall 13 and the second side wall 14 together enclose a furnace 15. The nozzle of each burner 20 is located in the furnace 15. Each burner layer 30 includes a plurality of burners 20 arranged at intervals in a horizontal direction. The axis 21 of the nozzle of the burner 20 closest to the first side wall 13 in each burner layer 30 is deflected in a direction away from the first side wall 13, and the axis 21 of the nozzle of the burner 20 closest to the second side wall 14 in each burner layer 30 is deflected in a direction away from the second side wall 14.
[0042] By arranging the nozzle of the burner 20 closest to the first side wall 13 in each burner layer 30 to be deflected in a direction away from the first side wall 13, the flame ejected from the burner 20 is advantageously kept away from the first side wall 13, thereby helping to avoid high-temperature corrosion of the first side wall 13 and also helping to avoid severe slagging of the first side wall 13 due to excessive heat load in the local area.
[0043] Similarly, by setting the nozzle of the burner 20 closest to the second side wall 14 in each burner layer 30 to be deflected in the direction away from the second side wall 14, the flame ejected from the burner 20 is beneficially kept away from the second side wall 14, thereby helping to avoid high-temperature corrosion of the second side wall 14 and also helping to avoid severe slagging of the second side wall 14 due to excessive heat load in the local area.
[0044] It should be noted that the first side wall 13 and the second side wall 14 both include a side wall body and a water-cooled wall installed on the side wall body.
[0045] In the present disclosure, the angle between the axis 21 of the nozzle of the burner 20 closest to the first side wall 13 in each burner layer 30 and the first side wall 13, and the angle between the axis 21 of the nozzle of the burner 20 closest to the second side wall 14 in each burner layer 30 and the second side wall 14 can be reasonably set according to actual conditions, and the present disclosure is not limited to this. As an embodiment, the angle between the axis 21 of the nozzle of the burner 20 closest to the first side wall 13 in each burner layer 30 and the first side wall 13 is 5°~6°, and the angle between the axis 21 of the nozzle of the burner 20 closest to the second side wall 14 in each burner layer 30 and the second side wall 14 is 5°~6°. For example, the angle between the axis 21 of the nozzle of the burner 20 closest to the first side wall 13 in each burner layer 30 and the first side wall 13 can be 5°17', and the angle between the axis 21 of the nozzle of the burner 20 closest to the second side wall 14 in each burner layer 30 and the second side wall 14 can be 5°17'.
[0046] Such an arrangement is beneficial to improving the degree of combustion of pulverized coal in the furnace 15, thereby reducing the concentrations of CO, pulverized coal particles and H2S at the first side wall 13 and the second side wall 14, and further helping to prevent the first side wall 13 and the second side wall 14 from being corroded by high temperature, and can reduce the screen bottom temperature of the screen superheater of the front and rear wall opposed boiler near the first side wall 13 and the second side wall 14, thereby helping to avoid overheating of the screen bottom of the screen superheater of the front and rear wall opposed boiler.
[0047] like Figure 5 The horizontal cross-section of the temperature field of the furnace 15 is shown, wherein the three figures in the left column correspond to the front and rear wall opposed boilers in which the axis 21 of the nozzle of the burner 20 provided by the present invention has an angle of 5°17' with the corresponding side wall, and the three figures in the right column correspond to the conventional front and rear wall opposed boilers in the prior art in which the axis of the burner nozzle is not deflected. The first layer of burner temperature field refers to the temperature field of the cross section of the furnace 15 where the lowest burner layer 30 is located, the third layer of burner temperature field refers to the temperature field of the cross section of the furnace 15 where the highest burner layer 30 is located, and the second layer of burner temperature field refers to the temperature field of the cross section of the furnace 15 where the burner layer 30 between the first layer of burners and the third layer of burners is located.
[0048] like Figure 6The horizontal cross-section of the CO concentration field of the furnace 15 is shown, wherein the three figures in the left column correspond to the front and rear wall opposed boilers in which the axis 21 of the nozzle of the burner 20 provided by the present invention has an angle of 5°17' with the corresponding side wall, and the three figures in the right column correspond to the conventional front and rear wall opposed boilers in the prior art in which the axis of the burner nozzle is not deflected, the first-layer burner CO concentration field refers to the CO concentration field diagram of the cross section of the furnace 15 where the lowest burner layer 30 is located, the third-layer burner CO concentration field refers to the CO concentration field diagram of the cross section of the furnace 15 where the highest burner layer 30 is located, and the second-layer burner temperature field refers to the CO concentration field diagram of the cross section of the furnace 15 where the burner layer 30 between the first-layer burner and the third-layer burner is located.
[0049] Depend on Figure 5 and Figure 6 It can be seen that, compared with the prior art in which the axis of the burner nozzle is not deflected, in the front and rear wall opposed boiler in which the axis 21 of the nozzle of the burner 20 provided in the present invention has an angle of 5°17' with the corresponding side wall, the CO concentration near the first side wall 13 and the second side wall 14 is lower, that is, the combustion effect of the coal powder in the furnace 15 is better, and the peak temperature at the first side wall 13 and the second side wall 14 of the present invention is lower. Therefore, the side wall body and the water-cooled wall of the first side wall 13 and the second side wall 14 are less prone to high-temperature corrosion and coking, and are more conducive to avoiding excessive temperature at the bottom of the screen of the screen superheater.
[0050] Depend on Figure 7 It can be seen from the horizontal cross-section of the screen bottom temperature field of the furnace 15 that the peak screen bottom temperature of the front and rear wall opposed boiler in the present invention is 1520K, and the peak temperature of the screen bottom near the wall is 1361K, which are lower than the peak screen bottom temperature of 1550K and the peak temperature of 1370K of the screen bottom near the wall of the conventional front and rear wall opposed boiler.
[0051] The distance between the nozzle of the burner 20 closest to the corresponding side wall in each layer of burners 20 and the corresponding side wall can be set to any appropriate value. As an embodiment, the horizontal distance from the center of the nozzle of the burner 20 closest to the first side wall 13 in each layer of burners 30 to the first side wall 13 can be 4300mm~4800mm, and the horizontal distance from the center of the nozzle of the burner 20 closest to the second side wall 14 in each layer of burners 30 to the second side wall 14 can be 4300mm~4800mm. Such a setting can maintain a reasonable distance between the first side wall 13, the second side wall 14 and the burner 20, which is conducive to maintaining the temperature of the furnace 15 at the first side wall 13 and the second side wall 14 in a suitable range.
[0052] Alternatively, if Figure 1As shown, the distance between the uppermost two adjacent burner layers 30 on the front wall 11 and the rear wall 12 is greater than the distance between any other two adjacent burner layers 30. Since the temperature at the upper position in the furnace 15 is usually the highest, such an arrangement can effectively prevent the local temperature at the upper position in the furnace 15 from overheating.
[0053] According to another aspect of the present disclosure, there is provided a thermal power generating set, comprising the above-mentioned front and rear wall opposed boiler.
[0054] The preferred embodiments of the present disclosure are described in detail above in conjunction with the accompanying drawings; however, the present disclosure is not limited to the specific details in the above embodiments. Within the technical concept of the present disclosure, a variety of simple modifications can be made to the technical solution of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.
[0055] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.
[0056] In addition, various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.
Claims
1. A front and rear wall hedge boiler, characterized in that: The furnace body comprises a furnace body and a plurality of burners, wherein the furnace body comprises a front wall and a rear wall arranged opposite to each other, and the front wall and the rear wall are both provided with at least three layers of burner layers arranged at intervals in a vertical direction, and each layer of the burner layer comprises at least one burner; Among them, the distance between the two uppermost adjacent burner layers on the front wall is greater than the distance between the two lowermost adjacent burner layers, and the distance between the two uppermost adjacent burner layers on the rear wall is greater than the distance between the two lowermost adjacent burner layers.
2. The front and rear wall opposed boiler according to claim 1, characterized in that: Along the direction from top to bottom, the distance between every two adjacent layers of the burner layers on the front wall and the rear wall gradually decreases.
3. The front and rear wall opposed boiler according to claim 2, characterized in that: The distance between any of the burner layers on the front wall and the rear wall and the adjacent burner layer above it is L1, and the distance between any of the burner layers on the front wall and the rear wall and the adjacent burner layer below it is L2, and the ratio of L1 to L2 is 1.25-2.
4. The front and rear wall opposed boiler according to claim 2, characterized in that: The distance between any of the burner layers on the front wall and the rear wall and the adjacent burner layer above it is L1, and the distance between any of the burner layers on the front wall and the rear wall and the adjacent burner layer below it is L2, and the difference between L1 and L2 is 1300 mm to 2700 mm.
5. The front and rear wall opposed boiler according to any one of claims 1 to 4, characterized in that: The furnace body further comprises a first side wall and a second side wall located between the front wall and the rear wall, wherein the front wall, the rear wall, the first side wall and the second side wall together enclose a furnace, and the nozzle of each burner is located in the furnace; Each burner layer includes a plurality of burners spaced apart in a horizontal direction, the axis of the nozzle of the burner closest to the first side wall in each burner layer is deflected toward a direction away from the first side wall, and the axis of the nozzle of the burner closest to the second side wall in each burner layer is deflected toward a direction away from the second side wall.
6. The front and rear wall opposed boiler according to claim 5, characterized in that: The angle between the axis of the nozzle of the burner closest to the first side wall in each burner layer and the first side wall is 5°~6°, and the angle between the axis of the nozzle of the burner closest to the second side wall in each burner layer and the second side wall is 5°~6°.
7. The front and rear wall opposed boiler according to claim 6, characterized in that: The angle between the axis of the nozzle of the burner closest to the first side wall in each burner layer and the first side wall is 5°17', and the angle between the axis of the nozzle of the burner closest to the second side wall in each burner layer and the second side wall is 5°17'.
8. The front and rear wall opposed boiler according to claim 5, characterized in that: The horizontal distance from the center of the nozzle of the burner closest to the first side wall in each burner layer to the first side wall is 4300mm~4800mm, and the horizontal distance from the center of the nozzle of the burner closest to the second side wall in each burner layer to the second side wall is 4300mm~4800mm.
9. The front and rear wall opposed boiler according to any one of claims 1 to 4, characterized in that: The distance between the uppermost two adjacent burner layers on the front wall and the rear wall is greater than the distance between any other two adjacent burner layers.
10. A thermal power generating unit, characterized in that: It comprises the front and rear wall opposed boiler as described in any one of claims 1-9.