CN112791568A - Device and method for reducing nitrogen oxides in flue gas - Google Patents
Device and method for reducing nitrogen oxides in flue gas Download PDFInfo
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- CN112791568A CN112791568A CN202110128026.4A CN202110128026A CN112791568A CN 112791568 A CN112791568 A CN 112791568A CN 202110128026 A CN202110128026 A CN 202110128026A CN 112791568 A CN112791568 A CN 112791568A
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Abstract
The invention discloses a device and a method for reducing nitrogen oxides in flue gas, which comprises a combustion boiler, an SNCR (selective non-catalytic reduction) denitration device, a controller, an output pipe, an online NOX detector and four branch pipes, wherein the SNCR denitration device comprises a denitration furnace, an ammonia water storage chamber and a soft water storage chamber, the device is characterized in that a one-way valve is arranged on a smoke exhaust channel, an injection spray gun and an NOx detector are arranged in the upper, middle and lower three areas of the pin removal furnace, the output of an ammonia water storage chamber is sequentially connected with a circulating pump, a metering detector and a mixer, the output of a soft water storage chamber is connected with the mixer through a delivery pump, the output of the mixer is connected with a first automatic control switching valve, the main input end of the first automatic control switching valve is connected with the output end of the mixer, one output end of the first automatic control switching valve is connected with the injection spray gun in the upper area, the other output end of the first automatic control switching valve is connected with a third automatic control switching valve. The invention reduces nitrogen oxides in the flue gas.
Description
Technical Field
The invention relates to the technical field of removing nitric oxide in smoke, in particular to a device and a method for reducing nitric oxide in smoke.
Background
Currently, three environmental issues facing the world include: 1. the greenhouse effect, the root of which is mainly from CO2, CH4 and N2O; 2. acid precipitation (acid rain), the source of which is mainly from SO2, NOX; 3. ozone layer depletion: the root cause of the NOx is mainly from CCIF and NOx. Among the pollutants causing the above-mentioned atmospheric environmental problems, NOX occupies three items, which is sufficient to have a large influence on the natural world. NOX is the basis of nitric acid rain, is one of main substances for forming photochemical smog and destroying the ozone layer, has strong toxicity, and has great harm to human bodies, environment and ecology and great damage to social economy. It is described by the related data that NO paralyzes the central nerve of a human and causes asphyxia, and NO2 causes asthma and emphysema, destroys the function of heart, liver, lung, kidney and hematopoietic tissues of the human and has stronger toxicity than NO.
The highest allowable concentration in air was 5mg/m3 (calculated as NO 2) whether NO, NO2 or N2O4 or N2O. At present, the annual emission of NOx in China is second to that in the United states, and the annual emission is kept above the level of 1000 ten thousand tons. In 2000, the discharge amount of nitrogen oxides in China is 1880 ten thousand tons, and in 2005, 2200 thousand tons. Particularly, as the installed capacity of the thermal power generating unit increases, 2668 million tons can be reached by 2020. Therefore, the country will increase the control strength of nitrogen oxide emission from the emission standard, because the content of nitrogen oxide in the discharged smoke is controlled within the national allowable emission standard, not only can acid rain and photochemical smog be prevented, but also the ozone layer can be damaged, and the method has long-term influence on the sustainable development of human bodies, ecology and socioeconomic performance. However, the removal of nitrogen oxides in flue gas is not ideal at present, and nitrogen oxides in flue gas cannot be alternately treated during exhaust, so that the treatment effect is poor, and improvement is needed.
Disclosure of Invention
The invention aims to provide a device and a method for reducing nitrogen oxides in flue gas, and aims to solve the problems that in the prior art, the desulfurization effect is poor, the effective production period of a hydrodesulfurization system is relatively long, and the treatment capacity of the hydrodesulfurization system is reduced.
In order to achieve the purpose, the invention provides the following technical scheme: a device for reducing nitrogen oxides in flue gas comprises a combustion boiler, an SNCR (selective non-catalytic reduction) denitration device and a controller, wherein an output pipe is connected to the output of the combustion boiler, an online NOX detector is arranged in the output pipe, four branch pipes are branched on the output pipe, the SNCR denitration device comprises a denitration furnace, an ammonia water storage chamber and a soft water storage chamber, a third partition plate which is vertically arranged is arranged in the denitration furnace, the upper part and the lower part of the third partition plate are respectively connected with the upper part and the lower part of the denitration furnace through an arc-shaped connecting plate, the denitration furnace is separated into a left area and a right area by the cooperation of the arc-shaped connecting plates and the third partition plate, a first smoke outlet is arranged on the third partition plate, a first partition plate and a second partition plate are arranged in the left area of the denitration furnace from top to bottom at intervals, and the left area of the denitration furnace is separated into an upper area, a middle area and, the three branch pipes are respectively connected with an upper area, a middle area and a lower area, the other branch pipe is used as a smoke exhaust channel, a one-way valve is arranged on the smoke exhaust channel, an injection spray gun and an NOX detector are arranged in the upper area, the middle area and the lower area, symmetrical guide plates are arranged on one sides of a first partition plate and a second partition plate, two guide plates form a second smoke exhaust port, the first smoke exhaust port is aligned with the second smoke exhaust port, a fan for discharging smoke into the second smoke exhaust port is arranged in the middle area, the output of the ammonia water storage chamber is connected with a circulating pump, the other end of the circulating pump is connected with a metering detector, the output of the metering detector is connected with a mixer, the output of the soft water storage chamber is connected with a delivery pump, the other end of the delivery pump is connected with a mixer, the output of the mixer is connected with a first automatic control switching valve of a three-way pipe, and the main input end of, one output end of the first automatic control switching valve is connected with an injection spray gun in an upper area, the other output end of the first automatic control switching valve is connected with a third automatic control switching valve of the three-way pipe, the main input end of the third automatic control switching valve is connected with the output end of the first automatic control switching valve, two output ends of the third automatic control switching valve are connected with injection spray guns in a middle-lower area in a sub-connection mode, a first main control valve is connected between the first automatic control switching valve and the mixer, two output ends of the first automatic control switching valve are connected with first auxiliary control valves in a sub-connection mode, the main input end of the third automatic control switching valve is connected with a second main control valve, two output ends of the third automatic control switching valve are connected with second auxiliary control valves, an air outlet is arranged on the side of the denitration furnace, and the controller, the online NOX detector and the first main control valve, The second main control valve, the first auxiliary control valve, the one-way valve, the metering detector, the circulating pump, the NOX detector, the output pump and the second auxiliary control valve are electrically connected.
Furthermore, a second automatic control switching valve of the three-way pipe is connected to the mixer, the main input end of the second automatic control switching valve is connected to the mixer, two output ends of the second automatic control switching valve are connected to a concentration detector, the main input end of the second automatic control switching valve is connected to a third main control valve, and two output ends of the second automatic control switching valve are connected to a third auxiliary control valve.
Furthermore, a detection pipeline is arranged in the right area, a nitrogen oxide detector and a suction device for detecting the content of nitrogen oxide in gas are arranged in the detection pipeline, the other end of the detection pipeline is connected with a three-way valve, one output end of the three-way valve is connected with the upper area through a return pipe, and the other output end of the three-way valve is communicated with a gas outlet.
Further, the bottom of the left side of the pin removal furnace is connected with a waste water collecting chamber.
Furthermore, a heat exchanger is arranged outside the smoke exhaust channel and connected with the inside of the combustion boiler.
The invention also discloses a method for reducing nitrogen oxides in flue gas, which specifically comprises the following steps:
s1, firstly, monitoring the NOx content of the output smoke in real time through an online NOx detector, and driving a one-way valve to open and directly discharge the smoke from a smoke discharge channel when the NOx content is lower than a preset threshold value; when the NOx content is larger than a preset threshold value, the step S1 is carried out;
s2, closing the one-way valve, enabling the combusted gas to enter a corresponding upper, middle and lower area from the other three branches, monitoring the NOX content of the corresponding area in real time by the internal NOX detector at the moment, then calculating the content value of all required ammonia water mixtures to obtain the content value of ammonia water required by the metering detector, controlling the circulating pump to obtain the final required ammonia water with the% concentration, enabling the obtained ammonia water to enter the mixer, and quantitatively mixing and proportioning the obtained ammonia water with softened water sent from the soft water storage chamber;
s3, at the moment, the first automatic control switching valve works, the opening degree of the corresponding first auxiliary control valve and the second auxiliary control valve is controlled according to the real-time content of the NOX obtained from the upper, middle and lower regions, and finally the NOX is injected into a hearth through an injection spray gun to realize the denitration reaction;
and S4, the three reacted gases enter the second smoke outlet and then are discharged from the gas outlet through the first smoke outlet under the action of the guide plate and the fan.
Further, in step S4, the gas enters the right area of the denitration furnace through the first smoke outlet, then enters the detection pipeline through the aspirator, is detected by the nitrogen oxide detector in the detection pipeline, the content of nitrogen oxide in the gas is directly discharged from the gas outlet when being smaller than a preset threshold value, and enters the upper area through the return pipe when being larger than the preset threshold value, and the opening degree of the first auxiliary control valve connected with the spray gun in the upper area is controlled to be larger than the opening degree of the first auxiliary control valve on the other path.
Further, when the smoke exhaust channel is opened, the heat exchanger is driven to work, heat is recycled and sent into the combustion boiler, and heating and combustion time of the combustion boiler is shortened.
The invention has the beneficial effects that: 1. can reduce NOx emission concentration in flue gas to be lower than 50mg/Nm3(ii) a Meanwhile, the availability ratio of the denitration device is not lower than 90%; 3. simultaneously this structure increases SNCR denitrification facility in the boiler flue gas, and the flue gas is with the ammonia liquid contact reaction after the spray gun atomizing, reduces the nitrogen oxide in the flue gas into N2, and whole injection system is from taking feedback and automatically regulated function, and through on-line monitoring chimney export NOX emission value, utilizes feedback system to adjust control aqueous ammonia jet mass, reduces the jet mass of aqueous ammonia under the prerequisite of guaranteeing denitrogenation efficiency, at the flow change width of clothAnd when the degree is larger, the excellent atomization effect can be kept, so that the desulfurization effect is improved, the effective production period of the hydrodesulfurization system is shortened, and the treatment capacity of the hydrodesulfurization system is improved.
Drawings
FIG. 1 is a schematic connection diagram of an apparatus for reducing nitrogen oxides in flue gas according to example 1;
FIG. 2 is a schematic connection diagram of an apparatus for reducing nitrogen oxides in flue gas according to this embodiment 2;
FIG. 3 is a schematic connection diagram of an apparatus for reducing nitrogen oxides in flue gas according to this embodiment 3;
FIG. 4 is a schematic connection diagram of an apparatus for reducing nitrogen oxides in flue gas according to this embodiment 4;
fig. 5 is a schematic connection diagram of an apparatus for reducing nitrogen oxides in flue gas in this embodiment 5.
In the figure: the system comprises a combustion boiler 1, an SNCR denitration device 2, a controller 3, an output pipe 4, an NOx detector 5, a branch pipe 6, a denitration furnace 7, an ammonia water storage chamber 8, a soft water storage chamber 9, a third partition plate 10, an arc-shaped connecting plate 11, a first smoke outlet 12, a first partition plate 13, a second partition plate 14, a smoke exhaust channel 16, a check valve 17, an injection spray gun 18, an NOx detector 19, a guide plate 20, a second smoke outlet 21, a fan 22, a circulating pump 23, a metering detector 24, a mixer 25, a delivery pump 26, a first automatic switching valve 27, a third automatic switching valve 28, a first main control valve 29, a first auxiliary control valve 3, a second main control valve 31, a second auxiliary control valve 32, an air outlet 33, a second automatic switching valve 3, a concentration detector 35, a third main control valve 36, a third auxiliary control valve 37, a detection pipeline 38, a nitrogen oxide detector 39, an aspirator 40, a denitration equipment, Three-way valve 41, return pipe 42, waste water collecting chamber 43, heat exchanger 44.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments.
Example 1:
as shown in fig. 1, the apparatus for reducing nitrogen oxides in flue gas disclosed in this embodiment comprises a combustion boiler 1, an SNCR denitration apparatus 2 and a controller 3, wherein an output pipe 4 is connected to an output of the combustion boiler 1, an on-line NOX detector 5 is disposed in the output pipe 4, four branch pipes 6 are branched from the output pipe 4, the SNCR denitration apparatus 2 comprises a denitration furnace 7, an ammonia water storage chamber 8 and a soft water storage chamber 9, a third partition plate 10 is disposed in the denitration furnace 7, a vertical upper portion and a lower portion of the third partition plate 10 are connected to the denitration furnace 7 through an arc-shaped connecting plate 11, the arc-shaped connecting plate 11 and the third partition plate 10 cooperate to separate the denitration furnace 7 into a left region and a right region, a first smoke outlet 12 is disposed on the third partition plate 10, a first partition plate 13 and a second partition plate 14 are disposed in the left region of the denitration furnace 7 from top to bottom, the first partition plate 13 and the second partition plate 14 separate the left area of the pin removal furnace 7 into an upper area, a middle area and a lower area, three branch pipes 6 are respectively connected with the upper area, the middle area and the lower area, the other branch pipe 6 is used as a smoke exhaust channel 16, a one-way valve 17 is arranged on the smoke exhaust channel 16, an injection spray gun 18 and an NOx detector 19 are arranged in the upper area, the middle area and the lower area, symmetrical guide plates 20 are arranged on one sides of the first partition plate 13 and the second partition plate 14, two guide plates 20 form a second smoke exhaust port 21, the first smoke exhaust port 12 is aligned with the second smoke exhaust port 21, a fan 22 for discharging smoke into the second smoke exhaust port 21 is arranged in the middle area, the output of the ammonia storage chamber 8 is connected with a circulating pump 23, the other end of the circulating pump 23 is connected with a metering detector 24, the output of the metering detector 24 is connected with a mixer 25, the output of the soft water storage chamber 9, the other end of the delivery pump 26 is connected with a mixer 25, the output of the mixer 25 is connected with a first automatic control switching valve 27 of a three-way pipe, the main input end of the first automatic control switching valve 27 is connected with the output end of the mixer 25, one output end of the first automatic control switching valve 27 is connected with the injection spray gun 18 in the upper area, the other output end of the first automatic control switching valve 27 is connected with a third automatic control switching valve 28 of the three-way pipe, the main input end of the third automatic control switching valve 28 is connected with the output end of the first automatic control switching valve 27, two output ends of the third automatic control switching valve 28 are connected with the injection spray guns 18 in the middle-lower area in a subsection connection mode, a first main control valve 29 is connected between the first automatic control switching valve 27 and the mixer 25, and two output ends of the first automatic control switching valve 27 are connected with a first auxiliary control valve 30 in a subsection mode, the main input end of the third automatic control switching valve 28 is connected with a second main control valve 31, two output ends of the third automatic control switching valve 28 are respectively connected with a second auxiliary control valve 32, the side edge of the pin removal furnace 7 is provided with an air outlet 33, and the controller 3 is electrically connected with the online NOX detector 5, the first main control valve 29, the second main control valve 31, the first auxiliary control valve 30, the check valve 17, the metering detector 24, the circulating pump 23, the NOX detector 19, the output pump and the second auxiliary control valve 32.
The embodiment also discloses a method for reducing nitrogen oxides in flue gas, which specifically comprises the following steps:
s1, firstly, monitoring the NOx content of the output smoke in real time through the online NOx detector 5, and driving the one-way valve 17 to be opened when the NOx content is lower than a preset threshold value, so that the smoke is directly discharged from the smoke discharge channel 16; when the NOx content is larger than a preset threshold value, the step S2 is carried out;
s2, closing the one-way valve 17, enabling the combusted gas to enter the corresponding upper, middle and lower areas from the other three branches, monitoring the NOx content of the corresponding area in real time by the internal NOx detector 19 at the moment, then calculating the content values of all required ammonia water mixtures to obtain the content value of the ammonia water required by the metering detector 24, controlling the circulating pump 23 to obtain the finally required 20% concentration ammonia water, enabling the obtained ammonia water to enter the mixer 25, and carrying out quantitative mixing proportioning on the obtained ammonia water and the softened water sent from the soft water storage chamber 9;
s3, at the moment, the first automatic control switching valve 27 works, the opening degree of the corresponding first auxiliary control valve 30 and the second auxiliary control valve 32 is controlled according to the real-time content of the NOX obtained from the upper, middle and lower areas, and finally the NOX is injected into the hearth through the injection spray gun 18 to realize the denitration reaction;
and S4, guiding the three reacted gases by the guide plate 20 and under the action of the fan 22, entering the second smoke outlet 21, passing through the first smoke outlet 12 and finally being discharged from the gas outlet 33.
The structure works byThe online NOX detector 5 monitors the NOX content of the output flue gas in real time, and when the NOX content is lower than a preset threshold value, the one-way valve 17 is driven to be opened and directly discharged from the smoke discharge channel 16; when the content of the NOx is larger than a preset threshold value, closing the one-way valve 17, enabling the combusted gas to enter the corresponding upper, middle and lower regions from the other three branches, monitoring the content of the NOx in the corresponding regions in real time by the internal NOx detector 19 at the moment, then calculating the content value of all required ammonia water mixtures to obtain the content value of the ammonia water required by the metering detector 24, controlling the circulating pump 23 to obtain the finally required ammonia water with the concentration of 20%, enabling the obtained ammonia water to enter the mixer 25, and carrying out quantitative mixing proportioning on the obtained ammonia water and the softened water sent from the soft water storage chamber 9; at this time, the first automatic control switching valve 27 works, the opening degree of the corresponding first auxiliary control valve 30 and the second auxiliary control valve 32 is controlled according to the real-time content of the NOX obtained from the upper, middle and lower regions, and finally the NOX is injected into the hearth through the injection spray gun 18 to realize the denitration reaction; the three reacted gases are guided by the guide plate 20 and acted by the fan 22, enter the second smoke outlet 21, pass through the first smoke outlet 12 and are finally discharged from the gas outlet 33, so that the following technical effects are realized by the method: 1. can reduce NOx emission concentration in flue gas to be lower than 50mg/Nm3(ii) a Meanwhile, the availability ratio of the denitration device is not lower than 90%; 3. simultaneously this structure increases SNCR denitrification facility in the boiler flue gas, the flue gas and the ammonia liquid contact reaction after the spray gun atomizing, reduce nitrogen oxide in the flue gas into N2, whole injection system is from taking feedback and automatically regulated function, through on-line monitoring chimney outlet NOX discharge value, utilize feedback system regulation control aqueous ammonia jet mass, reduce the jet mass of aqueous ammonia under the prerequisite of guaranteeing denitrification efficiency, also can keep good atomization effect when the flow variation range is great, thereby improve desulfurization effect, shorten hydrodesulfurization system's effective production cycle simultaneously, improve hydrodesulfurization system's processing ability, in addition this structure is not more than 0.3% to boiler combustion efficiency influence, the reduction product is N2 is the principal ingredients of atmosphere constitution, the non-staining environment, whole device is advanced, safety, reliability, be convenient for operation maintenance.
Experimental data:
| NOx emission concentration in output flue gas | |
| Example 1 | 45mg/Nm3 |
Example 2:
as shown in fig. 2, in the device for reducing nitrogen oxides in flue gas disclosed in this embodiment, a second automatic control switching valve 34 of a three-way pipe is further connected to the mixer 25, a main input end of the second automatic control switching valve 34 is connected to the mixer 25, two output ends of the second automatic control switching valve 34 are connected to a concentration detector 35, a main input end of the second automatic control switching valve 34 is connected to a third main control valve 36, and two output ends of the second automatic control switching valve 34 are connected to a third auxiliary control valve 37, so that ammonia content detection is performed on a mixed ammonia mixture by the above-mentioned structure, it is further ensured that the ammonia mixture delivered to the denitration furnace 7 meets requirements, and nitrogen oxides in flue gas are finally further reduced.
Example 3:
as shown in fig. 3, in the device for reducing nitrogen oxides in flue gas disclosed in this embodiment, a detection pipeline 38 is disposed in the right region, a nitrogen oxide detector (39) and an aspirator 40 for detecting the content of nitrogen oxides in the gas are disposed in the detection pipeline 38, the other end of the detection pipeline 38 is connected to a three-way valve 41, one output end of the three-way valve 41 is connected to the upper region through a return pipe 42, and the other output end of the three-way valve 41 is communicated with the gas outlet 33.
Further, the embodiment also discloses a method for reducing nitrogen oxides in flue gas, in step S4, gas enters the right area of the denitration furnace 7 through the first smoke outlet 12, then enters the detection pipeline 38 through the suction device 40, the content of nitrogen oxides in the gas is detected by the nitrogen oxide detector 39 in the detection pipeline 38, when the content of nitrogen oxides in the gas is smaller than a preset threshold value, the nitrogen oxides are directly discharged from the gas outlet 33, when the content of nitrogen oxides in the gas is larger than the preset threshold value, the nitrogen oxides enter the upper area through the return pipe 42, and the opening degree of the first auxiliary control valve 30 connected with the spray gun in the upper area is controlled to be larger than the opening degree of the first auxiliary control valve 30 on the other path.
By the method, the effect of removing the nitric oxide in the flue gas is improved, and the nitric oxide in the flue gas is finally further reduced.
Example 4:
as shown in fig. 4, in the device for reducing nitrogen oxides in flue gas disclosed in this embodiment, further, the left bottom of the denitration furnace 7 is connected to a waste water collection chamber 43, so that waste water is conveniently collected through the above structure.
Example 5:
as shown in fig. 5, in the apparatus for reducing nitrogen oxides in flue gas according to the present embodiment, a heat exchanger 44 is disposed outside the flue gas duct 16, and the heat exchanger 44 is connected to the inside of the combustion boiler 1, so that the heating and combustion time of the combustion boiler 1 can be shortened by the recovered heat.
Further, the present embodiment also discloses a method for reducing nitrogen oxides in flue gas, when the flue gas channel 16 is opened, the heat exchanger 44 is driven to work, and heat is recycled and sent into the combustion boiler 1, so as to shorten the heating and combustion time of the combustion boiler 1.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.
Claims (8)
1. The utility model provides a reduce device of nitrogen oxide in flue gas, includes combustion boiler (1), SNCR denitrification facility (2) and controller (3), its characterized in that: an output pipe (4) is connected with the output of the combustion boiler (1), an online NOX detector (5) is arranged in the output pipe (4), four branch pipes (6) are branched on the output pipe (4), the SNCR denitration device (2) comprises a denitration furnace (7), an ammonia water storage chamber (8) and a soft water storage chamber (9), a third partition plate (10) which is vertically arranged is arranged in the denitration furnace (7), the upper part and the lower part of the third partition plate (10) are connected with the denitration furnace (7) through an arc-shaped connecting plate (11), the arc-shaped connecting plate (11) and the third partition plate (10) are matched to separate the denitration furnace (7) into a left area and a right area, a first smoke outlet (12) is arranged on the third partition plate (10), and a first partition plate (13) and a second partition plate (14) are arranged in the left area of the denitration furnace (7) at intervals from top to bottom, the device is characterized in that the left area of the denitration furnace (7) is divided into an upper area, a middle area and a lower area by the first partition plate (13) and the second partition plate (14), three branch pipes (6) are respectively connected with the upper area, the middle area and the lower area, the other branch pipe (6) is used as a smoke exhaust channel (16), a one-way valve (17) is arranged on the smoke exhaust channel (16), an injection spray gun (18) and an NOx detector (19) are arranged in the upper area, the first partition plate (13) and the second partition plate (14) are respectively provided with symmetrical guide plates (20) on one side, the two guide plates (20) form a second smoke exhaust port (21), the first smoke exhaust port (12) is aligned with the second smoke exhaust port (21), a fan (22) for discharging smoke into the second smoke exhaust port (21) is arranged in the middle area, the output of the ammonia water storage chamber (8) is connected with a circulating pump (23), and the other end of the circulating pump (23) is connected with a, the output of the metering detector (24) is connected with a mixer (25), the output of the soft water storage chamber (9) is connected with a delivery pump (26), the other end of the delivery pump (26) is connected with the mixer (25), the output of the mixer (25) is connected with a first automatic control switching valve (27) of a three-way pipe, the main input end of the first automatic control switching valve (27) is connected with the output end of the mixer (25), one output end of the first automatic control switching valve (27) is connected with an injection spray gun (18) in an upper area, the other output end of the first automatic control switching valve (27) is connected with a third automatic control switching valve (28) of the three-way pipe, the main input end of the third automatic control switching valve (28) is connected with the output end of the first automatic control switching valve (27), and two output ends of the third automatic control switching valve (28) are connected with the injection spray gun (18) in a lower area in a branch connection, be connected with first main control valve (29) between first automatic control switch valve (27) and blender (25), be connected with first auxiliary control valve (30) at two output branches of first automatic control switch valve (27), be connected with second main control valve (31) at the main input of third automatic control switch valve (28), be connected with second auxiliary control valve (32) at two output branches of third automatic control switch valve (28), be provided with gas outlet (33) at denitration stove (7) side, controller (3) and online NOX detector (5), first main control valve (29), second main control valve (31), first auxiliary control valve (30), check valve (17), measurement detector (24), circulating pump (23), NOX detector (19), output pump and second auxiliary control valve (32) electricity be connected.
2. The apparatus for reducing nitrogen oxides in flue gas according to claim 1, wherein: the mixer (25) is also connected with a second self-control switching valve (34) of the three-way pipe, the main input end of the second self-control switching valve (34) is connected with the mixer (25), two output ends of the second self-control switching valve (34) are connected to a concentration detector (35), the main input end of the second self-control switching valve (34) is connected with a third main control valve (36), and two output ends of the second self-control switching valve (34) are connected with a third auxiliary control valve (37).
3. The apparatus for reducing nitrogen oxides in flue gas according to claim 2, wherein: a detection pipeline (38) is arranged in the right area, a nitrogen oxide detector (39) and a suction device (40) for detecting the content of nitrogen oxide in gas are arranged in the detection pipeline (38), the other end of the detection pipeline (38) is connected with a three-way valve (41), one output end of the three-way valve (41) is connected with the upper area through a return pipe (42), and the other output end of the three-way valve (41) is communicated with a gas outlet (33).
4. The apparatus for reducing nitrogen oxides in flue gas according to claim 3, wherein: the bottom of the left side of the pin removal furnace (7) is connected with a waste water collecting chamber (43).
5. The device for reducing nitrogen oxides in flue gas according to claim 4, wherein: a heat exchanger (44) is arranged outside the smoke exhaust channel (16), and the heat exchanger (44) is connected with the inside of the combustion boiler (1).
6. A method for reducing nitrogen oxides in flue gas, which comprises the following steps of adopting the device for reducing nitrogen oxides in flue gas according to any one of claims 1-5, and is characterized by comprising the following steps:
s1, firstly, monitoring the NOx content of output smoke in real time through an online NOx detector (5), and when the NOx content is lower than a preset threshold value, driving a one-way valve (17) to be opened and directly discharging the smoke from a smoke discharging channel (16); when the NOx content is larger than a preset threshold value, the step S2 is carried out;
s2, closing the one-way valve (17), enabling the combusted gas to enter a corresponding upper, middle and lower area from the other three branches, monitoring the NOx content of the corresponding area in real time by the internal NOx detector (19), then calculating the content value of all required ammonia water mixtures, obtaining the content value of the ammonia water required by the metering detector (24), controlling the circulating pump (23) to obtain the final required ammonia water with 20% concentration, enabling the obtained ammonia water to enter the mixer (25), and carrying out quantitative mixing and proportioning on the obtained ammonia water and the softened water sent from the soft water storage chamber (9);
s3, at the moment, the first automatic control switching valve (27) works, the opening degree of the corresponding first auxiliary control valve (30) and the second auxiliary control valve (32) is controlled according to the real-time content of the NOX obtained from the upper, middle and lower areas, and finally the NOX is injected into a hearth through an injection spray gun (18) to realize the denitration reaction;
s4, the three reacted gases are guided by a guide plate (20) and acted by a fan (22), enter a second smoke outlet (21), pass through a first smoke outlet (12) and are finally discharged from a gas outlet (33).
7. The method for reducing nitrogen oxides in flue gas according to claim 6, wherein the method comprises the following steps: in step S4, gas enters the right area of the denitration furnace (7) through the first smoke outlet (12), then enters the detection pipeline (38) through the suction device (40), the content of nitrogen oxide in the gas is detected by the nitrogen oxide detector (39) in the detection pipeline (38), the gas is directly discharged from the gas outlet (33) when the content of nitrogen oxide in the gas is smaller than a preset threshold value, the gas enters the upper area through the return pipe (42) when the content of nitrogen oxide in the gas is larger than the preset threshold value, and the opening degree of the first auxiliary control valve (30) connected with the spray gun in the upper area is controlled to be larger than the opening degree of the first auxiliary control valve (30) on the other path.
8. The method for reducing nitrogen oxides in flue gas according to claim 6, wherein: when the smoke exhaust channel (16) is opened, the heat exchanger (44) is driven to work, heat is recycled and sent into the combustion boiler (1), and the heating and combustion time of the combustion boiler (1) is shortened.
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| CN109999630A (en) * | 2019-05-08 | 2019-07-12 | 武汉立为工程技术有限公司 | A kind of SNCR denitration system |
| CN211936357U (en) * | 2020-03-30 | 2020-11-17 | 中国华能集团清洁能源技术研究院有限公司 | Efficient matrix type SNCR (selective non-catalytic reduction) denitration system suitable for pulverized coal furnace |
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