CN214536147U - Circulating fluidized bed boiler low-nitrogen combustion air distribution system - Google Patents
Circulating fluidized bed boiler low-nitrogen combustion air distribution system Download PDFInfo
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- CN214536147U CN214536147U CN202120090414.3U CN202120090414U CN214536147U CN 214536147 U CN214536147 U CN 214536147U CN 202120090414 U CN202120090414 U CN 202120090414U CN 214536147 U CN214536147 U CN 214536147U
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Abstract
The utility model relates to a circulating fluidized bed boiler equipment field, in particular to circulating fluidized bed boiler low-nitrogen combustion air distribution system contains air separation device, nitrogen gas storage tank, primary air fan and soot blower, air separation device connects the nitrogen gas storage tank, the nitrogen gas storage tank is connected respectively the primary air fan with the soot blower, the primary air chamber of boiler is connected to the primary air fan, the soot blower is connected in the afterbody heating surface of boiler. The system prepares nitrogen through an air separation device, one part of the nitrogen is sent into a primary air system, low-nitrogen combustion regulation of the boiler is carried out by adjusting the mixing proportion of the nitrogen and air in the primary air, the other part of the air nitrogen is sent into the tail heating surface of the boiler through a soot blower for soot blowing, the influence of soot on heat transfer caused by the tail heating surface is eliminated, and meanwhile, the soot blowing mode can not cause the rise of oxygen content in flue gas, so that the CEMS environmental protection data can be prevented from failing to reach the standard due to high converted oxygen content.
Description
Technical Field
The utility model relates to a circulating fluidized bed boiler equipment field, in particular to circulating fluidized bed boiler low-nitrogen combustion air distribution system.
Background
The circulating fluidized bed boiler adopts fluidized combustion, and the main structure comprises a hearth, a circulating furnace returning structure and a tail heating surface. The hearth is a main structure of boiler combustion and is divided into a dense-phase area and a dilute-phase area, primary air is sent into the dense-phase area to perform anoxic combustion, and secondary air is sent into the dilute-phase area to perform oxygen-enriched combustion. In the prior art, the oxygen-poor combustion in a dense-phase region is realized by reducing the primary air volume or by adopting flue gas to be sent into a primary air system in a recycling manner, and when a boiler runs at a low load, in order to ensure the safe operation of the boiler, the primary air volume cannot be lower than the lowest fluidized air volume, so that the oxygen content in a hearth is too high, the requirement of low-nitrogen combustion cannot be met, and the emission of nitrogen oxides in the boiler exceeds the standard; the flue gas is more complicated to be sent into a primary air system in a recycling way, and the flue gas is corroded, so that extra energy is consumed for operation.
Meanwhile, ash is continuously deposited on the surface of the heating surface at the tail part of the boiler in the operation process of the boiler, when the ash is deposited to a certain degree, the heat transfer of the heating surface is influenced, the temperature of the exhaust smoke is increased, the thermal efficiency of the boiler is reduced, and the oxygen content in the exhaust smoke is easily increased by the existing ash blowing mode, so that the CEMS environmental protection data cannot reach the standard due to the fact that the converted oxygen content is high.
Disclosure of Invention
In view of the above problem, the utility model provides a circulating fluidized bed boiler low-nitrogen combustion air distribution system, this system prepares nitrogen gas through air separator, a part nitrogen gas is sent into primary air system, through the mixing proportion of nitrogen gas and air in the adjustment primary air, carry out boiler low-nitrogen combustion and adjust, another portion wind nitrogen gas is sent into the afterbody of boiler through the soot blower and is received the hot side and blow the ash, the influence of afterbody received hot side deposition to heat transfer has been eliminated, this soot blowing mode can not arouse the rising of oxygen content in the flue gas simultaneously, thereby avoid CEMS environmental protection data not up to standard because of the conversion oxygen volume height.
The technical scheme of the utility model is that: the utility model provides a circulating fluidized bed boiler low-nitrogen combustion air distribution system, contains air separation set, nitrogen gas storage tank, primary air fan and soot blower, air separation set connects the nitrogen gas storage tank, the nitrogen gas storage tank is connected respectively the primary air fan with the soot blower, the primary air chamber of boiler is connected to the primary air fan, the soot blower is connected in the afterbody heating surface of boiler.
Preferably, the circulating fluidized bed boiler further comprises an oxygen-enriched air storage tank and an overfire air fan, wherein the oxygen-enriched air storage tank is respectively connected with the air separation device and the overfire air fan, and the overfire air fan is connected with a hearth of the circulating fluidized bed boiler.
Preferably, the circulating fluidized bed boiler further comprises a material returning fan, and the material returning fan is respectively connected with the oxygen-enriched storage tank and a material returning device of the circulating fluidized bed boiler.
Preferably, the air separation device further comprises an air compression device which is connected with the air separation device through a pressure stabilizing air tank.
Preferably, the air separation unit is a membrane process air separation unit.
Preferably, a compressor and an air storage tank are connected between the nitrogen storage tank and the soot blower in sequence.
Preferably, the primary air fan is connected with an air supply pipeline of the primary air chamber and passes through the tail heating surface of the boiler.
Preferably, the secondary air fan is connected with an air supply pipeline of the hearth and passes through the tail heating surface of the boiler.
After the technical scheme is adopted, the beneficial effects of the utility model are that: the circulating fluidized bed boiler low-nitrogen combustion air distribution system separates air into oxygen-enriched air and nitrogen through an air separation device, the separated nitrogen is stored in a nitrogen storage tank, a part of nitrogen is conveyed into a primary air chamber of a boiler through a primary fan, anoxic combustion in a dense-phase region of the boiler is created by adjusting the content of the nitrogen in primary air, a reducing atmosphere is formed, generation of nitrogen oxides is inhibited, the low-nitrogen emission purpose is achieved, and especially when the boiler is in low-load operation, on the premise of meeting the lowest fluidization air quantity, the oxygen content of a hearth is reduced, and the low-nitrogen combustion effect is realized; and the other part of nitrogen is blown into the tail heating surface of the boiler through a soot blower to perform soot blowing, so that the influence of soot on the heat transfer caused by the tail heating surface is eliminated, and meanwhile, the soot blowing mode cannot cause the oxygen content in the flue gas to be increased, thereby avoiding the situation that the CEMS environmental protection data cannot reach the standard due to high converted oxygen content.
Drawings
FIG. 1 is a schematic view of a circulating fluidized bed boiler low nitrogen combustion air distribution system disclosed in an embodiment of the present invention;
in the drawings:
the device comprises an air compression device 1, a pressure stabilizing air tank 2, an air separation device 3, an oxygen-enriched air storage tank 4, a nitrogen storage tank 5, a primary fan 6, a secondary fan 7, a material returning fan 8, a compressor 9, a soot blower 10, a primary air chamber 11, a hearth 12, a tail heating surface 13, a material returning device 14, a cyclone separator 15 and an air storage tank 16
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The utility model provides a circulating fluidized bed boiler low-nitrogen combustion air distribution system, the system separates out nitrogen gas through air separator, and a part of nitrogen gas is sent into the primary air system, through adjusting the mixing proportion of nitrogen gas and air in the primary air, carries out boiler low-nitrogen combustion regulation, especially when the boiler low-load operation, under the prerequisite that satisfies minimum fluidization air volume, reduces the oxygen content of furnace, realizes the effect of low-nitrogen combustion; and the other part of nitrogen is sent to the tail heating surface of the boiler through a soot blower for soot blowing, so that the influence of soot deposition on the tail heating surface on heat transfer is eliminated, and meanwhile, the soot blowing mode cannot cause the increase of the oxygen content in the flue gas, thereby avoiding the situation that the CEMS environmental protection data cannot reach the standard due to high converted oxygen content.
As shown in fig. 1, a schematic diagram of a circulating fluidized bed boiler low-nitrogen combustion air distribution system is provided in an embodiment of the present invention, the system includes an air separation device 3, an oxygen-enriched air storage tank 4, a nitrogen storage tank 5, a primary air fan 6 and a soot blower 10, the air separation device 3 is connected to the nitrogen storage tank 5, the nitrogen storage tank 5 is used as a buffer tank when nitrogen is generated and used in an unbalanced manner, the nitrogen storage tank 5 is respectively connected to the primary air fan 6 and the soot blower 10, the primary air fan 6 is connected to a primary air chamber 11 of the boiler, and the soot blower 10 is connected to a tail heating surface 13 of the boiler. The air is separated into oxygen-enriched air and nitrogen by an air separation device 3, the separated nitrogen is stored in a nitrogen storage tank 5, one part of the nitrogen is sent into a primary air chamber 11 of the boiler by a primary fan 6, and the other part of the nitrogen is sent into a tail heating surface 13 of the boiler by a soot blower 10. The nitrogen gas sent into the primary air chamber 11 is used as a supplementary air source of the primary air, the proportion of the mixed nitrogen gas in the primary air is adjusted through the emission concentration of nitrogen oxide at the outlet of the boiler, the oxygen content in the primary air entering the circulating fluidized bed boiler is adjusted, and the requirement of low-nitrogen combustion is met.
Further, an air supply pipeline of the primary air chamber 11 connected with the primary air fan 6 passes through the tail heating surface 13 of the boiler. The primary fan 6 may be a centrifugal fan.
In some preferred embodiments, the system further comprises an oxygen-enriched air storage tank 4 and an overfire air blower 7, wherein the oxygen-enriched air storage tank 4 is used as a buffer tank when the oxygen-enriched air is generated and used in an unbalanced manner, the oxygen-enriched air storage tank 4 is respectively connected with the air separation device 3 and the overfire air blower 7, and the overfire air blower 7 is connected with a hearth 12 of the circulating fluidized bed boiler. The oxygen-enriched air separated by the air separation device 3 is stored in an oxygen-enriched air storage tank 4 and is sent into a hearth 12 of the circulating fluidized bed boiler through a secondary fan 7. The secondary fan 7 sends the oxygen-enriched air into the dilute phase region of the hearth 12 for oxygen-enriched combustion, so that an excess air system is reduced, and the burnout rate is improved.
Further, an air supply pipeline of the secondary fan 7 connected with the hearth 12 passes through a tail heating surface 13 of the boiler. The secondary fan 7 may be a centrifugal fan.
In some preferred embodiments, the system further comprises a return air blower 8, and the return air blower 8 is connected to the oxygen-enriched air storage tank 4 and the return feeder 14 of the circulating fluidized bed boiler, respectively. The material returning fan 8 can be a roots fan. The material returning fan 8 sends the oxygen-enriched air in the oxygen-enriched air storage tank 4 into the material returning device 14 of the circulating fluidized bed boiler as the material returning air, and after the material returning air is sent into the material returning device 14, unburnt fuel particles and ash in the flue gas separated by the cyclone separator 15 of the boiler can be loosened, so that the fuel particles and the ash are returned to the hearth 12 of the boiler, meanwhile, the further combustion of the fuel particles is promoted, the combustion efficiency is improved, and the carbon content of fly ash is reduced.
In some preferred embodiments, the air compression device 1 is further included, and the air compression device 1 is connected with the air separation device 3 through the pressure stabilizing air tank 2. Air is compressed by the air compression device 1 and filtered to remove impurities, enters the pressure stabilizing air tank 2, and is separated into oxygen-enriched air and nitrogen by the air separation device 3.
Further, the air separation apparatus 3 is a membrane method air separation apparatus. Oxygen-enriched air and nitrogen are prepared by utilizing a membrane method air separation device, the oxygen content of the oxygen-enriched air is 30-45%, and the purity of the separated nitrogen is more than 95%.
In some preferred embodiments, a compressor 9 and an air storage tank 16 are connected between the nitrogen storage tank 5 and the soot blower 10 in sequence. The compressor 9 may be a screw compressor. The nitrogen stored in the nitrogen storage tank 5 is compressed by the compressor 9 and enters the gas storage tank 16. The nitrogen in the air storage tank 16 is used for blowing dust on the tail heating surface 13 of the boiler through the soot blower 10.
And a pressure gauge and an exhaust valve are respectively arranged on the oxygen-enriched air storage tank 4 and the nitrogen storage tank 5, when the pressure exceeds the upper limit of a set value, the exhaust valve is opened to exhaust, and when the pressure is lower than the set value, the exhaust valve is closed to keep the pressure of the system stable.
As shown in the attached figure 1, part of nitrogen separated from the air separation device is sent into a primary air system to be used as a supplementary air source of primary air, a low-nitrogen combustion atmosphere is created by adjusting the oxygen content in a hearth, and the other part of nitrogen is used as an air source of a soot blower; one part of the oxygen-enriched air separated in the air separation device is used as an air source of secondary air and sent into the hearth, and the other part of the oxygen-enriched air is used as an air source of return air and sent into the material returning device. The two gases separated in the air separation device are effectively utilized, and the device has the advantages of playing a positive role, reducing the investment cost and improving the economy of oxygen-enriched low-nitrogen combustion.
The above description is only exemplary of the present invention and should not be construed as limiting the present invention, and any modifications, equivalents and improvements made within the spirit and principles of the present invention are intended to be included within the scope of the present invention.
Claims (8)
1. The utility model provides a circulating fluidized bed boiler low-nitrogen combustion air distribution system, contains air separation set, nitrogen gas storage tank, primary air fan and soot blower, air separation set connects the nitrogen gas storage tank, the nitrogen gas storage tank is connected respectively the primary air fan with the soot blower, the primary air chamber of boiler is connected to the primary air fan, the soot blower is connected in the afterbody heating surface of boiler.
2. The circulating fluidized bed boiler low-nitrogen combustion air distribution system of claim 1, further comprising an oxygen-enriched air storage tank and an overfire air fan, wherein the oxygen-enriched air storage tank is respectively connected with the air separation device and the overfire air fan, and the overfire air fan is connected with a hearth of the circulating fluidized bed boiler.
3. The circulating fluidized bed boiler low-nitrogen combustion air distribution system of claim 2, further comprising a material return fan, wherein the material return fan is respectively connected with the oxygen-enriched air storage tank and the material return device of the circulating fluidized bed boiler.
4. The circulating fluidized bed boiler low nitrogen combustion air distribution system of claim 1, further comprising an air compression device, wherein the air compression device is connected to the air separation device through a surge tank.
5. The circulating fluidized bed boiler low-nitrogen combustion air distribution system of claim 1, wherein the air separation unit is a membrane process air separation unit.
6. The circulating fluidized bed boiler low-nitrogen combustion air distribution system of claim 1, wherein a compressor and an air storage tank are connected between the nitrogen storage tank and the soot blower in sequence.
7. The circulating fluidized bed boiler low-nitrogen combustion air distribution system of any one of claims 1 to 6, wherein a supply duct of the primary air blower connected to the primary air chamber passes through the tail heating surface of the boiler.
8. The circulating fluidized bed boiler low-nitrogen combustion air distribution system as claimed in claim 2 or 3, wherein the secondary fan is connected with the air supply pipeline of the hearth to pass through the tail heating surface of the boiler.
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| CN202120090414.3U CN214536147U (en) | 2021-01-14 | 2021-01-14 | Circulating fluidized bed boiler low-nitrogen combustion air distribution system |
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| CN202120090414.3U CN214536147U (en) | 2021-01-14 | 2021-01-14 | Circulating fluidized bed boiler low-nitrogen combustion air distribution system |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114686270A (en) * | 2022-03-16 | 2022-07-01 | 沈阳铝镁设计研究院有限公司 | Method for increasing oxygen concentration of gasifying agent of normal-pressure circulating fluidized bed gasification furnace |
| CN114923170A (en) * | 2022-06-17 | 2022-08-19 | 神华准格尔能源有限责任公司 | Method for adjusting bed temperature of circulating fluidized bed boiler |
-
2021
- 2021-01-14 CN CN202120090414.3U patent/CN214536147U/en active Active
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114686270A (en) * | 2022-03-16 | 2022-07-01 | 沈阳铝镁设计研究院有限公司 | Method for increasing oxygen concentration of gasifying agent of normal-pressure circulating fluidized bed gasification furnace |
| CN114923170A (en) * | 2022-06-17 | 2022-08-19 | 神华准格尔能源有限责任公司 | Method for adjusting bed temperature of circulating fluidized bed boiler |
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