CN110864325A - Flue gas NO controlled by adjusting boiler combustionxMethod of discharging amount - Google Patents
Flue gas NO controlled by adjusting boiler combustionxMethod of discharging amount Download PDFInfo
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- CN110864325A CN110864325A CN201911202429.8A CN201911202429A CN110864325A CN 110864325 A CN110864325 A CN 110864325A CN 201911202429 A CN201911202429 A CN 201911202429A CN 110864325 A CN110864325 A CN 110864325A
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- outlet
- hearth
- boiler
- combustion
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N3/00—Regulating air supply or draught
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N2900/00—Special features of, or arrangements for controlling combustion
- F23N2900/05003—Measuring NOx content in flue gas
Abstract
The invention provides a method for controlling the emission of NOx in flue gas by adjusting boiler combustion, when the nitrogen content of fuel is less than 0.5%, the combustion of a generator set boiler controls the temperature of flue gas at a hearth outlet to be 810-850 ℃, and the oxygen content at the hearth outlet to be 3-6%; when the nitrogen content of the fuel is 0.5-2%, controlling the smoke temperature of a hearth outlet to be 780-810 ℃ and controlling the oxygen content of the hearth outlet to be 2-3% by combustion of a boiler of the generator set; when the nitrogen content of the fuel is 2-3%, the combustion of the boiler of the generator set controls the temperature of smoke at the outlet of the hearth to be less than 780 ℃, and the oxygen content at the outlet of the hearth is 1-2%. According to the invention, the combustion mode of the boiler is changed according to the difference of the nitrogen content in the fuel, and the NOx emission of the boiler flue gas is effectively controlled by controlling the temperature of the outlet of the hearth and the oxygen content of the outlet of the hearth, so that the emission reaching the standard is ensured.
Description
Technical Field
The invention belongs to the technical field of biomass power generation, and particularly relates to a method for controlling the emission of NOx in flue gas by adjusting boiler combustion.
Background
The human society is continuously developing and the demand for energy is increasing, and coal, oil and natural gas, which are currently main energy sources of human beings, are rapidly decreasing, so that human beings face a series of significant problems such as energy shortage, resource shortage, environmental deterioration, and the like, and biomass energy gradually draws attention as a novel energy source.
China has rich biomass energy sources and wide prospects for developing the biomass power generation industry, but the standard emission of NOx in the biomass power generation industry is an industry problem, and no especially mature denitration treatment technology exists at present. According to NOXBy the generation mechanism of, NOXMainly divided into thermal type NOXAnd fuel type NOXThe method for regulating boiler combustion is mainly to control thermal NOXTo fuel type NOXThe amount of generated fuel is generally controlled by a denitration device to ensure the emission to reach the standard, but when the nitrogen content in the fuel is less than 3 percent, the denitration device is adopted to control NOXAnd the system has low running economy due to the generated amount.
Disclosure of Invention
The invention aims to solve the problem that the nitrogen content of the existing fuel influences the NOx emission of a biomass boiler.
Therefore, the invention provides a method for controlling the emission of NOx in flue gas by adjusting the combustion of a boiler, when the nitrogen content of fuel is less than 0.5%, the combustion of a boiler of a generator set controls the temperature of flue gas at the outlet of a hearth to be 810-850 ℃, and the oxygen content at the outlet of the hearth to be 3-6%;
when the nitrogen content of the fuel is 0.5-2%, controlling the smoke temperature of a hearth outlet to be 780-810 ℃ and controlling the oxygen content of the hearth outlet to be 2-3% by combustion of a boiler of the generator set;
when the nitrogen content of the fuel is 2-3%, the combustion of the boiler of the generator set controls the temperature of smoke at the outlet of the hearth to be less than 780 ℃, and the oxygen content at the outlet of the hearth is 1-2%.
Furthermore, the control method of the temperature of the smoke at the outlet of the hearth is to adjust the proportion of the primary air and the secondary air and assist in controlling the temperature of the smoke at the outlet of the hearth by manually adding or reducing circulating ash.
Furthermore, the control method of the oxygen content at the outlet of the hearth is to control the total air volume entering the boiler and adjust the secondary air volume to control the oxygen content at the outlet of the hearth.
Compared with the prior art, the invention has the beneficial effects that:
the method for controlling the discharge amount of the NOx in the flue gas by adjusting the boiler combustion changes the combustion mode of the boiler according to different nitrogen contents in the fuel, effectively controls the discharge amount of the NOx in the flue gas of the boiler by controlling the temperature of the outlet of the hearth and the oxygen content of the outlet of the hearth, and ensures the discharge reaching the standard.
Detailed Description
The technical solutions in the embodiments of the present invention are clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention provides a method for controlling the discharge amount of NOx in flue gas by adjusting boiler combustion, which comprises the following steps:
(1) when the nitrogen content of the fuel is less than 0.5%, the combustion of the boiler of the generator set controls the temperature of smoke at the outlet of the hearth to be 810-850 ℃, and the oxygen content at the outlet of the hearth is 3-6%.
(2) When the nitrogen content of the fuel is 0.5-2%, the combustion of the boiler of the generator set controls the smoke temperature at the outlet of the hearth to be 780-810 ℃, and the oxygen content at the outlet of the hearth to be 2-3%.
(3) When the nitrogen content of the fuel is 2-3%, the combustion of the boiler of the generator set controls the temperature of smoke at the outlet of the hearth to be less than 780 ℃, and the oxygen content at the outlet of the hearth is 1-2%.
Specifically, the control method of the hearth outlet smoke temperature is to adjust the proportion of primary air and secondary air, and assist in manually adding or reducing circulating ash to control the hearth differential pressure, so that the aim of controlling the hearth outlet smoke temperature is fulfilled while the primary burnout rate is improved.
For example, when the nitrogen content of the fuel is less than 0.5%, the primary air volume is controlled to be about 50%, partial circulating ash is manually discharged, the differential pressure of the hearth is controlled to be about 250Pa, the primary burnout rate is improved, and the purpose of controlling the smoke temperature at the outlet of the hearth to be 810-850 ℃ is achieved. When the nitrogen content of the fuel is 0.5-2%, controlling the primary air quantity to be about 55%, and manually increasing part of circulating ash to control the differential pressure of the hearth to be about 300Pa so as to improve the primary burnout rate, thereby realizing the purpose of controlling the smoke temperature at the outlet of the hearth to be 780-810 ℃. When the nitrogen content of the fuel is 2-3%, the primary air quantity is controlled to be about 60%, partial circulating ash is artificially increased, the differential pressure of the hearth is controlled to be about 350Pa, the primary burnout rate is improved, and the aim of controlling the smoke temperature at the outlet of the hearth to be less than 780 ℃ is fulfilled.
The control method of the oxygen content of the hearth outlet is to control the proportion of primary air and secondary air entering the furnace and control the total air intake of the boiler to control the oxygen content of the hearth outlet.
For example, when the nitrogen content of the fuel is less than 0.5%, the proportion of the primary air and the secondary air is controlled to be 50%: 50 percent, the total air intake is controlled to be about 95 percent of the rated air distribution amount, and the oxygen content of the outlet of the hearth is controlled to be 3-6 percent on the premise of ensuring the stable combustion working condition. When the nitrogen content of the fuel is 0.5-2%, controlling the proportion of the primary air and the secondary air to be 55%: 45 percent, the total air intake is controlled to be about 90 percent of the rated air distribution amount, and the oxygen content of the outlet of the hearth is controlled to be 2-3 percent on the premise of ensuring the stable combustion working condition. When the nitrogen content of the fuel is 2-3%, controlling the proportion of primary air and secondary air to be 60%: 40 percent, the total air intake is controlled to be about 85 percent of the rated air distribution amount, and the oxygen content of the outlet of the hearth is controlled to be 1-2 percent on the premise of ensuring the stable combustion working condition.
The influence of different nitrogen contents of fuel, different furnace outlet flue gas temperatures and different furnace outlet oxygen contents on the emission of NOx in the flue gas of a biomass boiler is researched through a specific embodiment.
Example 1:
in this example, the effect of different furnace outlet flue gas temperatures and furnace outlet oxygen contents on the emission of NOx from biomass boilers when the nitrogen content of the fuel is less than 0.5% was studied, and the results are shown in Table 1.
Table 1: influence of different furnace outlet flue gas temperature and oxygen content on NOx emission
As can be seen from Table 1, when the nitrogen content of the fuel is less than 0.5%, the emission of the fuel gas NOx reaching the standard can be ensured by controlling the temperature of the flue gas at the outlet of the combustion furnace of the boiler of the generator set to be 810-850 ℃ and the oxygen content at the outlet of the combustion furnace to be 3-6%. Meanwhile, through detection, when the temperature of smoke at the outlet of the hearth is 810-850 ℃ and the oxygen content at the outlet of the hearth is 3-6%, the boiler is still in an efficient combustion zone, so that the emission reaching the standard can be met, the combustion efficiency of the boiler is considered, and the combustion efficiency of the boiler is higher than 89% and is close to the design working condition; and when the temperature of the smoke at the outlet of the furnace hearth is less than 810 ℃ and the oxygen content at the outlet of the furnace hearth is less than 3%, the efficiency of the boiler is 70-85%, and the running economy of the boiler is obviously reduced.
Example 2:
in the embodiment, the influence of different furnace outlet flue gas temperatures and furnace outlet oxygen contents on the emission of NOx in the flue gas of the biomass boiler when the nitrogen content of the fuel is 0.5-2% is studied, and the results are shown in Table 2.
Table 2: influence of different furnace outlet flue gas temperature and oxygen content on NOx emission
As can be seen from Table 2, when the nitrogen content of the fuel is 0.5-2%, the emission of the fuel gas NOx reaching the standard can be ensured by controlling the temperature of the flue gas at the outlet of the combustion furnace of the boiler of the generator set to be 780-810 ℃ and the oxygen content at the outlet of the combustion furnace to be 2-3%. Meanwhile, through detection, when the temperature of smoke at the outlet of the hearth is 780-810 ℃ and the oxygen content at the outlet of the hearth is 2-3%, the boiler is still in an efficient combustion zone, the combustion efficiency of the boiler is more than 85%, the emission standard can be met, and the combustion efficiency of the boiler is also taken into consideration; and when the temperature of the smoke at the outlet of the hearth is less than 780 ℃ and the oxygen content at the outlet of the hearth is less than 2%, the combustion efficiency of the boiler is only 70-82%, and the running economy of the boiler is obviously reduced.
Example 3:
in the embodiment, the influence of different furnace outlet flue gas temperatures and furnace outlet oxygen contents on the emission of NOx in the flue gas of the biomass boiler when the nitrogen content of the fuel is 2-3% is studied, and the result is shown in Table 3.
Table 3: influence of different furnace outlet flue gas temperature and oxygen content on NOx emission
As can be seen from Table 3, when the nitrogen content of the fuel is 2-3%, the smoke temperature of the furnace outlet of the boiler combustion of the generator set is controlled to be less than or equal to 780 ℃, the oxygen content of the furnace outlet is controlled to be 1-2%, the NOx emission of the boiler smoke is reduced, and the emission reaching the standard is ensured. Meanwhile, through detection, if the temperature and the oxygen content of the smoke at the outlet of the hearth are further reduced, the combustion efficiency of the boiler is rapidly reduced to about 70%, and the economical efficiency is obviously reduced.
In conclusion, the method for controlling the discharge amount of the flue gas NOx by adjusting the boiler combustion changes the combustion mode of the boiler according to different nitrogen contents in the fuel, effectively controls the discharge amount of the flue gas NOx of the boiler by controlling the temperature of the outlet of the hearth and the oxygen content of the outlet of the hearth, and ensures the discharge reaching the standard.
The above examples are merely illustrative of the present invention and should not be construed as limiting the scope of the invention, which is intended to be covered by the claims and any design similar or equivalent to the scope of the invention.
Claims (3)
1. A method for controlling the discharge amount of NOx in flue gas by adjusting the combustion of a boiler is characterized in that:
when the nitrogen content of the fuel is less than 0.5%, the combustion of the boiler of the generator set controls the temperature of smoke at the outlet of the hearth to be 810-850 ℃, and the oxygen content at the outlet of the hearth is 3-6%;
when the nitrogen content of the fuel is 0.5-2%, controlling the smoke temperature of a hearth outlet to be 780-810 ℃ and controlling the oxygen content of the hearth outlet to be 2-3% by combustion of a boiler of the generator set;
when the nitrogen content of the fuel is 2-3%, the combustion of the boiler of the generator set controls the temperature of smoke at the outlet of the hearth to be less than 780 ℃, and the oxygen content at the outlet of the hearth is 1-2%.
2. A method of controlling the amount of flue gas NOx emissions by modulating boiler combustion as claimed in claim 1, wherein: the control method of the furnace outlet smoke temperature is to adjust the proportion of the primary air and the secondary air and assist in manually adding or reducing circulating ash to control the furnace outlet smoke temperature.
3. A method of controlling the amount of flue gas NOx emissions by modulating boiler combustion as claimed in claim 1, wherein: the control method of the oxygen content at the outlet of the hearth is to control the total air quantity entering the boiler and adjust the secondary air quantity to control the oxygen content at the outlet of the hearth.
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| CN201911202429.8A CN110864325A (en) | 2019-11-29 | 2019-11-29 | Flue gas NO controlled by adjusting boiler combustionxMethod of discharging amount |
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| CN103225819A (en) * | 2013-04-24 | 2013-07-31 | 广东电网公司电力科学研究院 | Oxygen volume adjusting method and system for pulverized coal boiler after change of coal type |
| CN103267303A (en) * | 2013-05-15 | 2013-08-28 | 大唐林州热电有限责任公司 | NOx generation reducing method for four-corner tangential boiler of thermal power plant |
| CN104061589A (en) * | 2014-07-17 | 2014-09-24 | 烟台龙源电力技术股份有限公司 | Low-nitrogen combustion control method and device adaptive to coal quality change |
| CN104061588A (en) * | 2014-07-17 | 2014-09-24 | 烟台龙源电力技术股份有限公司 | Low-nitrogen combustion control method and system based on secondary air door air regulation control |
| CN105605609A (en) * | 2015-05-05 | 2016-05-25 | 大唐贵州野马寨发电有限公司 | Thermal power plant boiler combustion oxygen amount optimizing method |
| CN106224948A (en) * | 2016-09-23 | 2016-12-14 | 凤阳海泰科能源环境管理服务有限公司 | A kind of self adaptation CFBB control method |
| CN109519960A (en) * | 2018-10-25 | 2019-03-26 | 东北电力大学 | A kind of coal-powder boiler combustion control method monitored on-line based on oxygen content and unburned carbon in flue dust |
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2019
- 2019-11-29 CN CN201911202429.8A patent/CN110864325A/en active Pending
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103225819A (en) * | 2013-04-24 | 2013-07-31 | 广东电网公司电力科学研究院 | Oxygen volume adjusting method and system for pulverized coal boiler after change of coal type |
| CN103267303A (en) * | 2013-05-15 | 2013-08-28 | 大唐林州热电有限责任公司 | NOx generation reducing method for four-corner tangential boiler of thermal power plant |
| CN104061589A (en) * | 2014-07-17 | 2014-09-24 | 烟台龙源电力技术股份有限公司 | Low-nitrogen combustion control method and device adaptive to coal quality change |
| CN104061588A (en) * | 2014-07-17 | 2014-09-24 | 烟台龙源电力技术股份有限公司 | Low-nitrogen combustion control method and system based on secondary air door air regulation control |
| CN105605609A (en) * | 2015-05-05 | 2016-05-25 | 大唐贵州野马寨发电有限公司 | Thermal power plant boiler combustion oxygen amount optimizing method |
| CN106224948A (en) * | 2016-09-23 | 2016-12-14 | 凤阳海泰科能源环境管理服务有限公司 | A kind of self adaptation CFBB control method |
| CN109519960A (en) * | 2018-10-25 | 2019-03-26 | 东北电力大学 | A kind of coal-powder boiler combustion control method monitored on-line based on oxygen content and unburned carbon in flue dust |
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