Circulating fluidized bed boiler based on air chamber ammonia doping and circulating fluidized bed combustion method

Abstract

The invention provides a circulating fluidized bed boiler based on air chamber ammonia doping and a circulating fluidized bed combustion method, and belongs to the field of fluidized bed combustion. In the boiler, an air distribution device and an air chamber are both arranged at the bottom of a hearth, the air distribution device is located on the upper side of the air chamber, and a primary air channel and an ammonia gas channel are arranged on the side wall of the air chamber; the negative pressure chamber surrounds the air chamber, the air distribution device and the lower part of the hearth, the upper edge of the negative pressure chamber is higher than the upper interface of the static lower bed layer of the fluidized bed, a pressure measuring point b serving as a pressure balance point is arranged at any point in the hearth on the same plane as the upper edge, negative pressure is formed above the balance point, positive pressure is formed below the balance point, and micro negative pressure is formed in the negative pressure chamber; the first induced draft fan at the negative pressure cavity end is arranged outside the hearth, the air inlet is communicated with the negative pressure cavity, and the air outlet is communicated with the hearth negative pressure area. According to the invention, the leakage of ammonia gas during ammonia-doped combustion of the boiler air chamber is effectively prevented, the safety and the stability of combustion are guaranteed, the energy utilization rate is improved, and meanwhile, the emission of nitrogen oxides is reduced.

Description

Technical Field

[0001] The invention belongs to the field of fluidized bed combustion, and in particular relates to a circulating fluidized bed boiler based on wind chamber ammonia mixing and a circulating fluidized bed combustion method. Background Art

[0002] As a clean coal combustion method, circulating fluidized bed combustion technology has the advantages of wide fuel adaptability, high combustion efficiency, and low nitrogen oxide emissions. However, the large-scale use of coal in circulating fluidized bed boilers will increase the concentration of carbon dioxide emissions. In order to reduce carbon emissions, low-carbon fuels and corresponding combustion technologies are generally used to replace coal. Ammonia, as a zero-carbon fuel and a good hydrogen storage medium, can be used as an alternative fuel to replace part of the coal combustion to reduce the carbon emissions of coal-fired units. The ammonia-blended combustion of circulating fluidized bed boilers can be achieved by secondary air or wind chamber method. Among them, the wind chamber ammonia-blended combustion method can not only promote the uniform mixing of ammonia and air, reduce carbon dioxide emissions, but also further reduce the concentration of nitrogen oxides and carbon monoxide, achieving a higher combustion efficiency.

[0003] In the prior art, when ammonia fuel is introduced into the combustion process of a circulating fluidized bed by means of a wind chamber, ammonia leakage is prone to occur, which may cause flammable and explosive safety hazards, fuel waste, incomplete combustion and other problems. For example, the Chinese utility model patent with publication number CN 220554642 U discloses a denitrification device installed in the primary air chamber of a circulating fluidized bed boiler, in which ammonia is delivered to the primary air chamber through an ammonia distributor to fully mix with the flue gas to produce a denitrification reaction, and ammonia is concentrated in the low-oxygen area in the center of the furnace through the air distribution plate to produce a reduction reaction with nitrogen oxides in the flue gas, thereby reducing the emission of nitrogen oxides. However, the above method does not take into account the problem of ammonia leakage in the wind chamber due to factors such as insufficient system sealing, improper operation or equipment aging. Summary of the invention

[0004] In view of the above-mentioned defects or deficiencies in the prior art, the present invention aims to provide a circulating fluidized bed boiler based on ammonia blending in a wind chamber and a circulating fluidized bed combustion method. By arranging a negative pressure chamber outside the wind chamber, ammonia that may leak from the wind chamber is returned to the furnace for continued combustion, thereby effectively preventing the leakage of ammonia during ammonia blending combustion in the wind chamber; at the same time, ammonia and primary air are mixed through the wind chamber before entering the fluidized bed layer for combustion, thereby improving the combustion efficiency and effectively reducing the emission of nitrogen oxides.

[0005] In order to achieve the above purpose, the embodiment of the present invention adopts the following technical solution:

[0006] In the first aspect, an embodiment of the present invention provides a circulating fluidized bed boiler based on ammonia doping in a wind chamber, wherein the circulating fluidized bed boiler comprises: a furnace 1, a first induced draft fan 2, a negative pressure chamber 3, an air distribution device 4, a wind chamber 5, a primary air channel 7, an ammonia channel 8, a return device 9, a cyclone separator 10, a second induced draft fan 11, a flue gas exhaust channel 12 and a thermocouple 13; wherein,

[0007] The air distribution device 4 and the wind chamber are both arranged at the bottom of the furnace 1, and the air distribution device 4 is located on the upper side of the wind chamber 5, and the primary air channel 7 and the ammonia channel 8 are arranged on the side wall of the wind chamber 5;

[0008] The negative pressure chamber 3 surrounds the air distribution device 4, the wind chamber 5 and the lower part of the furnace 1, and is sealed to the outer wall of the furnace 5. The upper edge of the negative pressure chamber 3 and the seal of the outer wall of the furnace are higher than the upper interface of the static lower bed layer of the fluidized bed. At the same time, a pressure measuring point b is set at any point in the furnace that is located at the same horizontal plane as the upper edge of the negative pressure chamber 3. At this time, the pressure measuring point b is the pressure balance point. The pressure above the pressure balance point in the furnace is negative pressure, and the pressure below the pressure balance point is positive pressure; the thermocouple 13 is set in the central area of ​​the furnace 1; the inside of the negative pressure chamber 3 is a slight negative pressure greater than the negative pressure of the ammonia gas returning to the furnace;

[0009] The first induced draft fan 2 is arranged outside the negative pressure chamber 3, the air inlet is connected and sealed with the negative pressure chamber 3, and the air outlet is connected and sealed with the negative pressure area of ​​the furnace 1;

[0010] The upper side wall of the furnace 1 is connected to the flue gas exhaust channel 12, the flue gas exhaust channel 12 is connected to the cyclone separator 10, the lower side of the cyclone separator 10 is connected to the return device 9, and the return device 9 is connected to the fluidized bed area at the bottom of the furnace 1; the second induced draft fan 11 is arranged at the tail end outlet of the central tube of the cyclone separator 10.

[0011] As a preferred embodiment of the present invention, a pressure measuring point a is set at the upper part of the negative pressure zone of the furnace 1 to monitor the negative pressure in the negative pressure zone of the furnace; a pressure measuring point c is set in the wind chamber 5 to monitor the pressure in the wind chamber 5; a pressure measuring point d is set in the negative pressure chamber 3 to monitor the slight negative pressure in the negative pressure chamber 3; and a pressure measuring point e is set at the tail end of the air outlet of the central tube of the cyclone separator 10 to monitor the pressure at the outlet of the central tube of the cyclone separator 10.

[0012] As a preferred embodiment of the present invention, the internal pressure of the wind chamber 5 is 8kPa to 12kPa; the pressure in the negative pressure zone at the upper part of the furnace 1 is -120Pa to -250Pa; the slight negative pressure inside the negative pressure chamber 3 is -5Pa to -10Pa; and the outlet pressure of the central tube of the cyclone separator 10 is -1950Pa to -2100Pa.

[0013] As a preferred embodiment of the present invention, the boiler also includes an air preheater 6; the air preheater 6 is arranged on the primary air channel 7 and connected to the wind chamber 5, and is used to preheat the incoming primary air while ensuring that the preheated primary air gas temperature does not exceed 200°C.

[0014] As a preferred embodiment of the present invention, the air distribution device 4 includes a steel plate, a plurality of air distribution pipes and an air distribution hood, the steel plate includes an upper flat plate and a lower flat plate, and the upper flat plate and the lower flat plate are both provided with pipe holes, a plurality of air distribution pipes extending out of the upper flat plate and extending upward are provided in the pipe holes, and a wind hood is provided at the upper end of the air distribution pipe, and the side surfaces of the upper flat plate and the lower flat plate are both fixed on the inner wall of the furnace 1, the air distribution pipe and the wind hood are arranged between the upper and lower flat plates at predetermined intervals, and the wind hood is evenly provided with small holes around it.

[0015] As a preferred embodiment of the present invention, the primary air channel 7 and the ammonia channel 8 are arranged on the right side of the air chamber 5 .

[0016] As a preferred embodiment of the present invention, the pipeline from the negative pressure chamber 3 to the upper part of the pressure balance point b of the furnace 1 contains a seal, and the seal is made of high temperature resistant material.

[0017] In a second aspect, an embodiment of the present invention further provides a circulating fluidized bed combustion method based on wind chamber ammonia mixing, and the combustion method is implemented by the circulating fluidized bed boiler as described above.

[0018] As a preferred embodiment of the present invention, the method comprises:

[0019] Ammonia and primary air are supplied to the air chamber through the primary air channel and the ammonia channel. The ammonia is not preheated, and the primary air is preheated through the air preheater, and the preheating temperature is below 200°C;

[0020] After ammonia and primary air are evenly mixed in the wind chamber, they are sent to the furnace bottom through the air distribution device for reaction and combustion. The temperature in the furnace is maintained at 800℃-900℃ through the thermocouples installed in the furnace.

[0021] After ammonia and primary air are burned in the furnace, the generated flue gas enters the cyclone separator through the flue gas exhaust channel, and the gas enters the tail convection flue from the central tube outlet of the cyclone separator, and the bed material particles are returned to the furnace through the return device to continue to participate in the circulation; through the adjustment of the second induced draft fan connected to the central tube outlet of the cyclone separator, the pressure measuring point b set at any point in the furnace on the same horizontal plane as the upper edge of the negative pressure chamber is the pressure balance point, and the pressure above the pressure balance point in the furnace is negative pressure, and the pressure below the pressure balance point is positive pressure;

[0022] The first induced draft fan draws the gas in the negative pressure chamber into the negative pressure zone above the pressure balance point of the furnace, maintaining a slightly negative pressure state in the negative pressure chamber; at this time, the ammonia leaked from the wind chamber enters the negative pressure chamber, enters the first induced draft fan through the connecting port between the negative pressure chamber and the first induced draft fan, and then returns to the furnace through the connecting port between the first induced draft fan and the negative pressure zone on the upper part of the furnace to continue to participate in combustion.

[0023] As a preferred embodiment of the present invention, a pressure measuring point c is provided in the air chamber, and the pressure in the air chamber is controlled to be between 8 kPa and 12 kPa by adjusting the ammonia gas and the primary air volume;

[0024] A pressure measuring point e is provided at the tail end of the central tube air outlet of the cyclone separator. The pressure value of the pressure measuring point e is controlled within a range of -1950Pa to -2100Pa by adjusting the second induced draft fan, and the pressure of the negative pressure zone where the pressure measuring point a on the upper part of the furnace is located is further controlled within a range of -120Pa to -250Pa to ensure that the pressure at the pressure balance point b is 0;

[0025] A pressure measuring point d is provided in the negative pressure chamber, and the slight negative pressure inside the negative pressure chamber is controlled to be -5Pa to -10Pa by adjusting the first induced draft fan connected to the negative pressure chamber.

[0026] The technical solution provided by the embodiment of the present invention has the following beneficial effects:

[0027] The circulating fluidized bed boiler and circulating fluidized bed combustion method based on ammonia mixing in the wind chamber provided by the embodiment of the present invention return the leaked ammonia to the furnace for further combustion by setting a negative pressure chamber; at the same time, the ammonia and the primary air are mixed through the wind chamber before entering the fluidized bed layer for combustion, rather than being sent into the fluidized bed layer for mixed combustion, thereby promoting uniform mixing of the ammonia and the primary air, thereby reducing the formation of nitrogen oxide concentration, and the ammonia is not preheated, and the temperature of the air preheater is controlled below 200°C, effectively avoiding safety hazards such as flashback and explosion caused by premixing; by adjusting the power of the second induced draft fan at the cyclone separator end, the furnace is maintained at a constant temperature. The negative pressure state of the lower part is maintained, thereby maintaining the pressure balance point position in the furnace; at the same time, by adjusting the power of the first induced draft fan at the negative pressure chamber end, the slight negative pressure state of the negative pressure chamber is maintained, so that the ammonia gas returned from the negative pressure chamber by the first induced draft fan is located in the negative pressure area above the pressure balance point position, ensuring that the ammonia gas smoothly enters the furnace and continues to burn, wherein the slight negative pressure in the negative pressure chamber is greater than the negative pressure above the pressure balance point of the furnace; through the negative pressure chamber, the leakage of ammonia fuel during the combustion of ammonia in the wind chamber is effectively reduced, the energy utilization rate is improved, the risk of safety accidents such as flammable and explosive caused by leakage is further reduced, and the safety and stability of combustion are guaranteed.

[0028] Of course, it is not necessary to achieve all of the advantages described above at the same time to implement any product or method of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0030] Figure 1 It is a schematic structural diagram of a circulating fluidized bed boiler based on wind chamber ammonia doping according to an embodiment of the present invention.

[0031] Description of reference numerals:

[0032] 1-furnace; 2-first induced draft fan; 3-negative pressure chamber; 4-air distribution device; 5-wind chamber; 6-air preheater; 7-primary air channel; 8-ammonia channel; 9-return device; 10-cyclone separator; 11-second induced draft fan; 12-smoke exhaust channel; 13-thermocouple. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. The components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations. It should be noted that the embodiments of the present invention and the features in the embodiments can also be combined with each other without conflict.

[0034] It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. In the description of the present invention, the terms "first", "second", "third", "fourth", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0035] In view of the existing wind chamber ammonia-doped fluidized bed, an embodiment of the present invention provides a circulating fluidized bed boiler and a circulating fluidized bed combustion method based on wind chamber ammonia-doped, wherein ammonia is doped into the furnace through the wind chamber, a negative pressure chamber is added outside the fluidized bed layer in the furnace and the wind chamber, and then the power of the second induced draft fan at the cyclone separator end is adjusted to maintain the pressure balance point position in the furnace and the negative pressure state in the upper part of the furnace, and at the same time, a slight negative pressure is maintained in the negative pressure chamber through the first induced draft fan, so that the position of the ammonia returned from the negative pressure chamber by the first induced draft fan is in the negative pressure area above the pressure balance point position, so that the ammonia leaked from the wind chamber is smoothly returned to the furnace through the negative pressure chamber and the first induced draft fan for continued combustion, effectively reducing the leakage of ammonia during wind chamber ammonia-doped combustion, solving the flammable and explosive safety hazards that may be caused by the leaked ammonia when ammonia is burned in the wind chamber, avoiding serious waste of fuel, and improving the combustion efficiency and safety of the combustion process.

[0036] like Figure 1 As shown, the circulating fluidized bed boiler based on wind chamber ammonia doping provided in an embodiment of the present invention includes: a furnace 1, a first induced draft fan 2, a negative pressure chamber 3, an air distribution device 4, a wind chamber 5, an air preheater 6, a primary air channel 7, an ammonia channel 8 and a return device 9, a cyclone separator 10, a second induced draft fan 11, a flue gas exhaust channel 12 and a thermocouple 13.

[0037] Among them, the air distribution device 4 and the wind chamber 5 are both arranged at the bottom of the furnace, and the air distribution device 4 is located on the upper side of the wind chamber 5, and the primary air channel 7 and the ammonia channel 8 are arranged on the side wall of the wind chamber 5, preferably on the right side; the negative pressure chamber 3 surrounds the air distribution device 4, the wind chamber 5 and the lower part of the furnace 1, and is sealed to the outer wall of the furnace 5, thereby forming a closed space, and the upper edge of the negative pressure chamber 3 and the outer wall of the furnace are sealed at a position higher than the upper interface of the static lower bed layer of the fluidized bed, and at the same time, a pressure measuring point b is set at any point in the furnace that is located at the same horizontal plane as the upper edge of the negative pressure chamber 3. At this time, the pressure measuring point b is the pressure balance point, and the pressure above the balance point in the furnace is negative pressure, and the pressure below the balance point is positive pressure. The thermocouple 13 is set in the central area of ​​the furnace 1; and the inside of the negative pressure chamber 3 is a slight negative pressure greater than the negative pressure of the ammonia gas returning to the furnace 1. At this time, the furnace 1 is divided into a positive pressure area at the bottom and a negative pressure area at the top through the pressure balance point.

[0038] The first induced draft fan 2 is arranged outside the negative pressure chamber 3, the air inlet is connected to and sealed with the negative pressure chamber 3, and the air outlet is connected to and sealed with the negative pressure area of ​​the furnace 1. Through the joint regulation of the first induced draft fan 2 and the second induced draft fan 11, the pressure in the negative pressure chamber 3 is higher than the upper pressure of the pressure balance point of the furnace 1, so as to ensure that the ammonia leaked from the wind chamber 5 can be returned to the furnace 1 for continued combustion.

[0039] The upper side wall of the furnace 1 is connected to the flue gas exhaust channel 12, which is in turn connected to the cyclone separator 10, and the lower side of the cyclone separator 10 is connected to the return device 9, which is in turn connected to the fluidized bed area at the lower part of the furnace 1; the second induced draft fan 11 is arranged at the outlet of the rear end of the central tube of the cyclone separator 10, and the pressure measuring point b is always kept as the pressure balance point and the pressure is 0 through the adjustment of the second induced draft fan 11. In this embodiment, all the parts involved in the connection are sealed to realize the internal circulation of the fluidized bed.

[0040] A pressure measuring point a is set at the upper part of the negative pressure zone of the furnace 1 to monitor the negative pressure in the negative pressure zone of the furnace; a pressure measuring point c is set in the wind chamber 5 to monitor the pressure in the wind chamber 5; a pressure measuring point d is set in the negative pressure chamber 3 to monitor the slight negative pressure in the negative pressure chamber; a pressure measuring point e is set at the tail end of the air outlet of the central tube of the cyclone separator 10 to monitor the pressure at the outlet of the central tube of the cyclone separator 10. Preferably, the internal pressure of the wind chamber 5 is 8kPa to 12kPa; the pressure of the negative pressure zone at the upper part of the furnace 1 is -120Pa to -250Pa; the slight negative pressure inside the negative pressure chamber 3 is -5Pa to -10Pa; the pressure at the outlet of the central tube of the cyclone separator 10 is -1950Pa to -2100Pa.

[0041] In a specific application example, the fluidized bed is filled with solid bed material particles, and the bed material particles are in a fluidized state under the action of ammonia gas and primary air flow.

[0042] Preferably, the air distribution device 4 includes a steel plate, a plurality of air distribution pipes and an air distribution hood, the steel plate includes an upper flat plate and a lower flat plate, and the upper flat plate and the lower flat plate are both provided with pipe holes, a plurality of air distribution pipes extending out of the upper flat plate and extending upward are provided in the pipe holes, and a wind hood is provided at the upper end of the air distribution pipe, and the sides of the upper flat plate and the lower flat plate are fixed on the inner wall of the furnace 1, the air distribution pipe and the wind hood are arranged between the upper and lower flat plates at predetermined intervals, and the wind hood is evenly provided with small holes around it.

[0043] Preferably, the primary air channel 7 and the ammonia channel 8 are arranged on the right side of the wind chamber 5. After the ammonia and the primary air are introduced into the wind chamber 5, they are mixed in the wind chamber 5 and then enter the furnace 1 through the hood of the air distribution device 4 for combustion. The air preheater 6 is arranged on the primary air channel 7 and connected to the wind chamber 5 to preheat the primary air introduced, while ensuring that the preheated gas temperature does not exceed 200°C. At this time, the primary air temperature is ensured to be below 200°C. When the primary air is mixed with ammonia, the ammonia is prevented from reacting or even exploding, thereby ensuring the safety of the device.

[0044] Preferably, the pipeline from the negative pressure chamber 3 to the upper part of the pressure balance point b of the furnace 1 contains seals, and the seals are made of high-temperature resistant materials to reduce the impact of temperature and sealing problems.

[0045] Preferably, the first induced draft fan 2 and the second induced draft fan 11 contain blades. The blades of the first induced draft fan 2 rotate to generate negative pressure, so that the negative pressure chamber 3 maintains a slightly negative pressure state; the blades of the second induced draft fan 11 rotate to generate negative pressure, so that the upper part of the furnace 1 maintains a negative pressure, and the negative pressure is less than the slightly negative pressure in the negative pressure chamber 3.

[0046] Based on the above-mentioned circulating fluidized bed boiler, the embodiment of the present invention further provides a circulating fluidized bed combustion method based on wind chamber ammonia mixing, and the combustion method process is as follows:

[0047] Ammonia and primary air are supplied from the right side of the air chamber 5 through the primary air channel 7 and the ammonia channel 8. The ammonia is not preheated, and the primary air is preheated by the air preheater 6, and the preheating temperature is below 200°C. A pressure measuring point c is provided in the air chamber 5, and the pressure in the air chamber 5 is controlled to be between 8kPa and 12kPa by adjusting the ammonia and primary air volumes.

[0048] After the ammonia gas and the primary air are uniformly mixed in the wind chamber 5, they are sent to the bottom of the furnace 1 through the air distribution device 4 for reaction and combustion. The temperature in the furnace 1 is maintained in the range of 800°C-900°C by the thermocouple 13 provided in the furnace 1.

[0049] After the ammonia and the primary air are burned in the furnace 1, the generated flue gas enters the cyclone separator 10 through the flue gas exhaust channel 12, and the gas enters the tail convection flue from the gas outlet of the cyclone separator 10, and the bed material particles are returned to the furnace through the return device 9 to continue to participate in the circulation; through the adjustment of the second induced draft fan connected to the gas outlet of the central tube of the cyclone separator, the pressure measuring point b set at any point in the furnace on the same horizontal plane as the upper edge of the negative pressure chamber is the pressure balance point, and the pressure above the pressure balance point in the furnace is negative pressure, and the pressure below the pressure balance point is positive pressure;

[0050] A pressure measuring point e is provided at the tail end of the central tube outlet of the cyclone separator 10. The pressure value of the measuring point e is controlled within a range of -1950Pa to -2100Pa by adjusting the second induced draft fan 11, and the pressure of the negative pressure zone at the upper part of the furnace 1 is further controlled within a range of -120 to -250Pa to ensure that the pressure at the pressure balance point b is 0.

[0051] The first induced draft fan 2 draws away the gas in the negative pressure chamber 3 and sends it into the negative pressure area above the pressure balance point of the furnace, maintaining a slightly negative pressure state in the negative pressure chamber 3; at this time, the ammonia leaked from the wind chamber 5 enters the negative pressure chamber 3, enters the first induced draft fan 2 through the connecting port between the negative pressure chamber 3 and the first induced draft fan 2, and then returns to the furnace 1 through the connecting port between the first induced draft fan 2 and the negative pressure area on the upper part of the furnace 1 to continue to participate in the combustion, thereby effectively reducing the leakage of ammonia fuel during ammonia combustion in the wind chamber, solving the flammable and explosive safety hazards and serious waste of fuel that may be caused by the leakage of ammonia when ammonia is mixed and burned in the wind chamber, and improving the combustion efficiency and safety of the combustion process.

[0052] It can be seen from the above technical solutions that the circulating fluidized bed boiler and circulating fluidized bed combustion method based on ammonia mixing in the wind chamber provided by the embodiment of the present invention, by setting a negative pressure chamber and a first induced draft fan, the leaked ammonia is returned to the furnace for further combustion; at the same time, the ammonia and the primary air are first mixed through the wind chamber and then enter the fluidized bed layer for combustion, rather than being sent into the fluidized bed layer for mixed combustion, thereby promoting uniform mixing of the ammonia and the primary air, thereby reducing the concentration of nitrogen oxides generated, and the ammonia is not preheated, and the air preheater temperature is controlled below 200°C, which is effective Avoid the safety hazards such as flashback and explosion caused by premixing; maintain the negative pressure state of the upper part of the furnace by adjusting the power of the second induced draft fan at the end of the cyclone separator, and at the same time, maintain the slight negative pressure state of the negative pressure chamber by adjusting the power of the first induced draft fan at the end of the negative pressure chamber. The pressure in the negative pressure chamber is higher than the pressure of the negative pressure zone above the pressure balance point of the furnace, ensuring that the position of the ammonia returned from the negative pressure chamber is above the pressure balance point, so that the ammonia leaked in the wind chamber is returned to the negative pressure zone above the pressure balance point of the furnace through the first induced draft fan and the negative pressure chamber to continue burning. Through the negative pressure chamber, the leakage of ammonia fuel during the combustion of ammonia in the wind chamber is effectively reduced, the energy utilization rate is improved, and the risk of safety accidents such as flammable and explosive caused by leakage is further reduced, ensuring the safety and stability of the working process.

[0053] The above description is only a preferred embodiment of the present invention and an explanation of the technical principles used. It is not intended to limit the scope of the invention claimed for protection, but only represents the preferred embodiment of the present invention. Those skilled in the art should understand that the scope of the invention involved in the present invention is not limited to the technical solution formed by a specific combination of the above-mentioned technical features, but should also cover other technical solutions formed by any combination of the above-mentioned technical features or their equivalent features without departing from the inventive concept. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present invention.

Claims

1. A circulating fluidized bed boiler based on wind chamber ammonia mixing, characterized in that: The circulating fluidized bed boiler comprises: a furnace (1), a first induced draft fan (2), a negative pressure chamber (3), an air distribution device (4), a wind chamber (5), a primary air channel (7), an ammonia channel (8), a material return device (9), a cyclone separator (10), a second induced draft fan (11), a flue gas exhaust channel (12) and a thermocouple (13); wherein: The air distribution device (4) and the wind chamber are both arranged at the bottom of the furnace (1), and the air distribution device (4) is located on the upper side of the wind chamber (5), and the primary air channel (7) and the ammonia channel (8) are arranged on the side wall of the wind chamber (5); The negative pressure chamber (3) surrounds the air distribution device (4), the wind chamber (5) and the lower part of the furnace (1), and is sealed to the outer wall of the furnace (5). The upper edge of the negative pressure chamber (3) and the seal with the outer wall of the furnace are higher than the upper interface of the static lower bed layer of the fluidized bed. At the same time, a pressure measuring point b is set at any point in the furnace that is located at the same horizontal plane as the upper edge of the negative pressure chamber (3). At this time, the pressure measuring point b is the pressure balance point. The pressure above the pressure balance point in the furnace is negative pressure, and the pressure below the pressure balance point is positive pressure. The thermocouple (13) is set in the central area of ​​the furnace (1). The interior of the negative pressure chamber (3) is a slight negative pressure greater than the negative pressure of the ammonia gas returning to the furnace. The first induced draft fan (2) is arranged outside the negative pressure chamber (3), the air inlet is connected to and sealed with the negative pressure chamber (3), and the air outlet is connected to and sealed with the negative pressure area of ​​the furnace (1); The upper side wall of the furnace (1) is connected to the smoke exhaust channel (12), the smoke exhaust channel (12) is further connected to the cyclone separator (10), the lower side of the cyclone separator (10) is connected to the return material device (9), and the return material device (9) is further connected to the fluidized bed area at the bottom of the furnace (1); the second induced draft fan (11) is arranged at the tail end outlet of the central tube of the cyclone separator (10).

2. The circulating fluidized bed boiler based on wind chamber ammonia mixing according to claim 1 is characterized in that: A pressure measuring point a is provided at the upper part of the negative pressure zone of the furnace (1) to monitor the negative pressure in the negative pressure zone of the furnace; a pressure measuring point c is provided in the wind chamber (5) to monitor the pressure in the wind chamber (5); a pressure measuring point d is provided in the negative pressure chamber (3) to monitor the slight negative pressure in the negative pressure chamber (3); and a pressure measuring point e is provided at the tail end of the air outlet of the central tube of the cyclone separator (10) to monitor the pressure at the outlet of the central tube of the cyclone separator (10).

3. The circulating fluidized bed boiler based on wind chamber ammonia mixing according to claim 2 is characterized in that: The internal pressure of the wind chamber (5) is 8 kPa to 12 kPa; the pressure of the negative pressure zone at the upper part of the furnace (1) is -120 Pa to -250 Pa; the slight negative pressure inside the negative pressure chamber (3) is -5 Pa to -10 Pa; the pressure at the outlet of the central tube of the cyclone separator (10) is -1950 Pa to -2100 Pa.

4. The circulating fluidized bed boiler based on wind chamber ammonia mixing according to claim 1 is characterized in that: The boiler further comprises an air preheater (6); the air preheater (6) is arranged on the primary air channel (7) and connected to the wind chamber (5), and is used to preheat the primary air introduced, while ensuring that the temperature of the preheated primary air gas does not exceed 200°C.

5. The circulating fluidized bed boiler based on wind chamber ammonia mixing according to claim 1 is characterized in that: The air distribution device (4) comprises a steel plate, a plurality of air distribution pipes and an air distribution hood. The steel plate comprises an upper flat plate and a lower flat plate. The upper flat plate and the lower flat plate are both provided with pipe holes. A plurality of air distribution pipes extending out of the upper flat plate and upward are provided in the pipe holes. A hood is provided at the upper end of the air distribution pipe. The sides of the upper flat plate and the lower flat plate are both fixed on the inner wall of the furnace (1). The air distribution pipe and the hood are arranged between the upper and lower flat plates at predetermined intervals. The hood is evenly provided with small holes around it.

6. The circulating fluidized bed boiler based on wind chamber ammonia mixing according to claim 1, characterized in that: The primary air channel (7) and the ammonia channel (8) are arranged on the right side of the air chamber (5).

7. The circulating fluidized bed boiler based on wind chamber ammonia mixing according to claim 1 is characterized in that: The pipeline from the negative pressure chamber (3) to the upper part of the pressure balance point b of the furnace (1) contains a sealing member, and the sealing member is made of a high temperature resistant material.

8. A circulating fluidized bed combustion method based on wind chamber ammonia mixing, characterized in that: The combustion method is realized by the circulating fluidized bed boiler according to any one of claims 1 to 7.

9. The circulating fluidized bed combustion method based on wind chamber ammonia mixing according to claim 8, characterized in that: The method comprises: Ammonia and primary air are supplied to the air chamber through the primary air channel and the ammonia channel. The ammonia is not preheated, and the primary air is preheated through the air preheater, and the preheating temperature is below 200°C; After ammonia and primary air are evenly mixed in the wind chamber, they are sent to the furnace bottom through the air distribution device for reaction and combustion. The temperature in the furnace is maintained at 800℃-900℃ through the thermocouples installed in the furnace. After ammonia and primary air are burned in the furnace, the generated flue gas enters the cyclone separator through the flue gas exhaust channel, and the gas enters the tail convection flue from the central tube outlet of the cyclone separator, and the bed material particles are returned to the furnace through the return device to continue to participate in the circulation; through the adjustment of the second induced draft fan connected to the central tube outlet of the cyclone separator, the pressure measuring point b set at any point in the furnace on the same horizontal plane as the upper edge of the negative pressure chamber is the pressure balance point, and the pressure above the pressure balance point in the furnace is negative pressure, and the pressure below the pressure balance point is positive pressure; The first induced draft fan draws the gas in the negative pressure chamber into the negative pressure zone above the pressure balance point of the furnace, maintaining a slightly negative pressure state in the negative pressure chamber; at this time, the ammonia leaked from the wind chamber enters the negative pressure chamber, enters the first induced draft fan through the connecting port between the negative pressure chamber and the first induced draft fan, and then returns to the furnace through the connecting port between the first induced draft fan and the negative pressure zone on the upper part of the furnace to continue to participate in combustion.

10. The circulating fluidized bed combustion method based on wind chamber ammonia mixing according to claim 8, characterized in that: A pressure measuring point c is set in the air chamber, and the pressure in the air chamber is controlled between 8kPa and 12kPa by adjusting the ammonia gas and the primary air volume; A pressure measuring point e is provided at the tail end of the central tube air outlet of the cyclone separator. The pressure value of the pressure measuring point e is controlled within a range of -1950Pa to -2100Pa by adjusting the second induced draft fan, and the pressure of the negative pressure zone where the pressure measuring point a on the upper part of the furnace is located is further controlled within a range of -120Pa to -250Pa to ensure that the pressure at the pressure balance point b is 0; A pressure measuring point d is provided in the negative pressure chamber, and the slight negative pressure inside the negative pressure chamber is controlled to be -5Pa to -10Pa by adjusting the first induced draft fan connected to the negative pressure chamber.

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