CN113251411A - Multi-pollutant cooperative control system and method for coal-fired industrial boiler - Google Patents
Multi-pollutant cooperative control system and method for coal-fired industrial boiler Download PDFInfo
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- CN113251411A CN113251411A CN202110603591.1A CN202110603591A CN113251411A CN 113251411 A CN113251411 A CN 113251411A CN 202110603591 A CN202110603591 A CN 202110603591A CN 113251411 A CN113251411 A CN 113251411A
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN A CARRIER GAS OR AIR
- F23C5/00—Disposition of burners with respect to the combustion chamber or to one another; Mounting of burners in combustion apparatus
- F23C5/08—Disposition of burners
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J15/00—Arrangements of devices for treating smoke or fumes
- F23J15/003—Arrangements of devices for treating smoke or fumes for supplying chemicals to fumes, e.g. using injection devices
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J15/00—Arrangements of devices for treating smoke or fumes
- F23J15/006—Layout of treatment plant
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J7/00—Arrangement of devices for supplying chemicals to fire
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J2215/00—Preventing emissions
- F23J2215/10—Nitrogen; Compounds thereof
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J2215/00—Preventing emissions
- F23J2215/20—Sulfur; Compounds thereof
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Abstract
The invention discloses a system and a method for the multi-pollutant cooperative control of a coal-fired industrial boiler, wherein the system comprises: the low-nitrogen coal-fired industrial boiler is internally provided with a low-nitrogen burner for burning coal powder; the boilers are respectively connected and used for removing SO in the flue gas outside the furnace2The desulfurization and dust removal device of (1) is used for a denitration device for denitration of flue gas in the furnace and a nitric oxide oxidation device for oxidizing NOx into acid oxides outside the furnace. The invention is provided with a boiler tail flue pollutant measuring device and a desulfurization and dust removal device tail flue pollutant measuring device, and can monitor NOx and SO in flue gas in real time2And concentration, and linkage among the pollutant control devices is realized through a plurality of control loops. The invention comprehensively ensures various pollutants by adopting modes of low-nitrogen combustion, in-furnace SNCR, out-furnace oxidation denitration, semi-dry desulfurization and the likeThe ultra-low discharge of the pollutants is realized, and meanwhile, a multi-loop automatic control mode is adopted, so that the system solves the problems of poor level of cooperative control of the pollutants of the pulverized coal industrial boiler, unstable system operation and the like.
Description
Technical Field
The invention relates to the technical field of coal-fired industrial boiler control, in particular to a system and a method for controlling multiple pollutants of a coal-fired industrial boiler in a coordinated mode.
Background
Industrial boilers currently include three broad categories, the stoker, the circulating fluidized bed boiler and the pulverized coal boiler. Chain furnace generally adopts the mode of spraying calcium in the furnace to control SO2The emission concentration, but the desulfurization efficiency of the calcium spraying technology in the furnace is low, the requirement on the range of the flue gas temperature is high, and the SO can not be met when the load is low2And (5) discharging requirements. The circulating fluidized bed boiler generally adopts the modes of calcium spraying in the boiler, wet or semidry desulphurization outside the boiler and the like to control SO2And the concentration is controlled, and simultaneously, the NOx is controlled by controlling the combustion temperature in the furnace and an SNCR method.
However, most of the above three industrial boiler forms of pollutant control methods adopt a manual control method, and the automation level of the operation system is low, so that the operation of the whole system is stableThe quality is not controllable, the pollutant of the pollutant often exceeds the standard, and the pollutant is easier to exceed the standard when the higher pollutant emission standard is executed. For example, CN201921372237.7 is an integrated multi-pollutant removal system of a circulating fluidized bed boiler, and a desulfurizer injection system and an ammonia water storage and metering system are arranged on a coal economizer leading-out flue, SO that dust and SO in a high-concentration dust environment can be realized2Ultra low emissions of NOx. And a CN201810032019.2 circulating fluidized bed boiler ultralow emission cooperative control method and a system integration device, wherein a boiler smoke outlet is hermetically communicated with a bag-type dust collector through a denitration SCR reactor, the bag-type dust collector is hermetically communicated with a high-efficiency desulfurization, demisting and dedusting integrated device, a wet electrostatic dust collector is added at an outlet of the high-efficiency desulfurization, demisting and dedusting integrated device, and a flue is hermetically communicated with a chimney through the wet electrostatic dust collector and a flue gas heat exchanger. However, the above patents all relate to local technical transformation of a single device, and the automation level is low by using a mode of 'synergistic removal' of a plurality of pollutants by using a plurality of devices.
Along with the improvement of the admission condition of the coal-fired pollutant emission, the emission standard of the industrial boiler pollutant gradually approaches the ultralow emission standard of the coal-fired power plant, namely the emission concentration of the nitrogen oxide is less than or equal to 50mg/Nm3The sulfur dioxide emission concentration is less than or equal to 35mg/Nm3Dust emission concentration is less than or equal to 5mg/Nm3. Different from a power station boiler, the industrial boiler has small capacity, large load change and large flue gas temperature fluctuation, and causes the change fluctuation of pollutants generated in the combustion process of the industrial boiler to have no regularity, so that the difficulty of the multi-pollutant cooperative control is increased.
Disclosure of Invention
In order to make up for the defects in the prior art, the invention provides a system and a method for the multi-pollutant cooperative control of a coal-fired industrial boiler.
In order to achieve the above object, the present invention adopts the following technical solutions:
the invention provides a coal-fired industrial boiler multi-pollutant cooperative control system in a first aspect, which comprises: the coal-fired industrial boiler is characterized in that a low-nitrogen burner is arranged in the boiler and used for burning coal powder to form coal powder with concentration less than or equal to300mg/Nm3Raw flue gas of NOx; the boilers are respectively connected and used for removing SO in the flue gas outside the furnace2The desulfurization and dust removal device is used for a denitration device for denitration of flue gas in the furnace and a nitric oxide oxidation device for oxidizing NOx outside the furnace into acid oxides which are easily removed by a desulfurizer;
wherein, first flue gas pollutant measuring device is connected to the afterbody flue department of boiler, second flue gas pollutant measuring device is connected to desulfurization dust collector's afterbody flue department, first flue gas pollutant measuring device or second flue gas pollutant measuring device are arranged in NOx and SO in the real-time supervision flue gas2And the concentration of the flue gas is respectively controlled by the low-nitrogen combustor, the desulfurization and dust removal device, the denitration device and the nitrogen oxide oxidation device to form a control loop, so that feedback signals generated by the first flue gas pollutant measuring device or the second flue gas pollutant measuring device are respectively transmitted to the low-nitrogen combustor, the desulfurization and dust removal device, the denitration device and the nitrogen oxide oxidation device to regulate and control the NOx amount generated by the low-nitrogen combustor and the input amount of flue gas treatment agents in the desulfurization and dust removal device, the denitration device and the nitrogen oxide oxidation device.
According to the system, the denitration device is communicated with a plurality of spray heads arranged in the boiler so as to spray denitration liquid to the smoke in the boiler, and the spray heads are arranged in the range of the smoke temperature of 800-950 ℃; the denitration liquid adopts ammonia water, urea solution, biological calcium-based denitration agent or other denitration agents, and preferably adopts an SNCR denitration device.
According to the system, the nitrogen oxide oxidation device is used for oxidation and denitration outside the furnace and comprises an oxidant injection mechanism, so that an oxidant is uniformly injected into flue gas, NOx is oxidized into an acidic oxide which is easily removed by a desulfurizer, and ultralow emission is realized; the oxidant includes, but is not limited to, ozone, sodium hypochlorite, and the like.
According to the system, the desulfurization and dust removal device adopts a semi-dry desulfurization and dust removal device of the external circulating fluidized bed, and can also adopt wet desulfurization and high-efficiency demister/wet electrostatic dust collector.
According to the inventionIn the system, the desulfurization and dust removal device is also connected with a desulfurizer charging device, and preferably, the desulfurizer comprises but is not limited to slaked lime, modified slaked lime, carbide slag, other desulfurizers and the like. SO generation by partial combustion of pulverized coal in boiler2(SO2The concentration is less than or equal to 2000mg/Nm3) The SO is realized by a desulfurizing and dust-removing device outside the furnace2The removal of (A) meets the requirement of ultra-low emission, such as SO2The discharge can be controlled to be less than or equal to 35mg/Nm3Dust is controlled to be less than or equal to 10mg/Nm3。
According to the system of the invention, the control circuit comprises a NOx control circuit, in particular: a combustion control loop of the NOx-low nitrogen burner in the furnace, a NOx-denitration liquid injection amount control loop, a first control loop for feeding the NOx-oxidizing agent and a second control loop for feeding the NOx-oxidizing agent outside the furnace. The first control loop for adding the NOx to the oxidant is a signal transmission and regulation loop between the first smoke pollutant measuring device and the nitrogen oxide oxidation device; and the second control loop for adding the NOx-oxidant is a signal transmission and regulation loop between the second flue gas pollutant measuring device and the nitrogen oxide oxidation device.
In a specific embodiment, in the boiler, the exhaust concentration of NOx at the outlet of the boiler is obtained in real time by monitoring a first flue gas pollutant measuring device at the tail flue of the boiler, NOx generated by combustion of a low-nitrogen burner is controlled and regulated by a combustion control loop of the NOx-low-nitrogen burner through PID (proportion integration differentiation), if the NOx is continuously increased, the liquid injection amount of the denitration device is controlled and regulated by the combustion control loop of the NOx-denitration liquid injection amount through PID, for example, the ammonia injection amount is increased, the first flue gas at the tail flue of the boiler is ensured to measure the NOx and maintain a relatively low level, and the ammonia injection amount can be accurately predicted through the means, so that the invention can ensure that the use amount of the denitration solution is not wasted; and/or the presence of a gas in the gas,
the method is characterized in that NOx emission concentration at the outlet of a boiler, which is obtained in real time by a first flue gas pollutant measuring device for monitoring a tail flue of the boiler, is used as the input quantity of control outside the boiler, NOx emission concentration is obtained in real time by a second flue gas pollutant measuring device for monitoring the tail flue of a desulfurization and dust removal device outside the boiler, the amount of an oxidant to be added to a nitrogen oxide oxidation device is obtained through rough calculation, and the amount of the oxidant to be added to the nitrogen oxide oxidation device is finely adjusted by a PID (proportion integration differentiation) by using a second control loop for adding the NOx to the oxidant.
In a specific embodiment, the rough calculation is: δ NOx is the monitored NOx concentration — the control NOx concentration, and the ammonia injection amount is calculated linearly from the molar ratio of NOx to urea or ammonia water in the chemical reaction equation. However, in order to accurately calculate the ammonia injection amount and reduce material consumption, the actual ammonia injection amount also has correlation with the flue gas temperature and the like, and the better ammonia injection amount is obtained after the influence factors are comprehensively considered and calculated in the PID controller.
According to the system of the invention, the control loop further comprises an SO2Control loop, including SO2First control loop of desulfurizer input and SO2-a second control loop for the devulcanizing agent input. The SO2A first control loop for the desulfurizer input is a signal transmission and regulation loop between a first flue gas pollutant measuring device and a desulfurization and dust removal device; the SO2And the desulfurizer input second control loop is a signal transmission and regulation loop between the second flue gas pollutant measuring device and the desulfurization dust removal device.
In a specific embodiment, the boiler outlet SO obtained by the boiler tail flue first smoke pollutant measuring device in real time is monitored by the boiler tail flue first smoke pollutant measuring device2The emission concentration is used as the input quantity of control, and SO is obtained in real time by a second flue gas pollutant measuring device at the tail flue of the desulfurization and dust removal device outside the furnace2Discharging concentration, roughly calculating to obtain the desulfurization agent amount to be added by a desulfurizer adding device, and then utilizing SO2And the second control loop of the desulfurizer input amount finely adjusts the desulfurizer input amount through PID control.
The coarse calculation is delta SO2Monitored SO2Concentration-control of SO2Concentration, by SO in chemical reaction equation2And linearly calculating the new addition of the desulfurizer according to the molar ratio of the desulfurizer to the calcium hydroxide. However, in order to accurately calculate the new adding amount of the desulfurizer and reduce material consumption, the actual desulfurizer amount also has correlation with the flue gas temperature and the water spraying amount, and after the influence factors are comprehensively considered and calculated in the PID controller, a better new desulfurizer is obtainedAnd (4) adding.
In the invention, the first flue gas pollutant measuring device or the second flue gas pollutant measuring device is a gas concentration detecting device for detecting NOx and SO2And the emission content of pollutants. "raw flue gas" is untreated flue gas.
The second aspect of the invention provides a control method of the coal-fired industrial boiler multi-pollutant cooperative control system, which comprises the following steps:
1) the coal-fired industrial boiler burns pulverized coal through a low-nitrogen burner arranged in the coal-fired industrial boiler to form coal powder with the concentration less than or equal to 300mg/Nm3Raw flue gas of NOx;
2) the denitration device sprays denitration liquid into the flue gas in the boiler, the nitrogen oxide oxidation device sprays oxidant into the flue gas in the tail flue of the boiler, and the flue gas discharged from the flue enters the desulfurization and dust removal device outside the boiler to remove SO2；
3) Monitoring the concentration of NOx in the flue gas at the outlet of the boiler, which is obtained by a first flue gas pollutant measuring device at the tail flue of the boiler in real time, and monitoring the concentration of NOx and SO which are obtained by a second flue gas pollutant measuring device at the tail flue of the desulfurization and dust removal device in real time2Concentration;
4) respectively transmitting feedback signals generated by the first flue gas pollutant measuring device or the second flue gas pollutant measuring device to the low-nitrogen combustor, the desulfurization and dust removal device, the denitration device and the nitric oxide oxidation device; and regulating the amount of NOx generated by the low-nitrogen combustor and the input amount of flue gas treatment agents in the desulfurization and dust removal device, the denitration device and the nitrogen oxide oxidation device according to the feedback signal.
According to the method of the invention, the agent for treating smoke comprises: the denitration liquid in the denitration device, the oxidant in the nitrogen oxide oxidation device and the desulfurizer in the desulfurization and dust removal device.
According to the method of the invention, the regulating comprises: the method comprises the steps of combustion control of an NOx-low nitrogen burner in a furnace, control of NOx-denitration spray liquid, first control of input of NOx-oxidizing agent outside the furnace and second control of input of NOx-oxidizing agent.
In a specific embodiment, in a boiler, monitoring the NOx emission concentration in the boiler outlet flue gas obtained by a first flue gas pollutant measuring device of a tail flue of the boiler in real time, firstly regulating and controlling NOx generated by combustion of a low-nitrogen burner through a PID (proportion integration differentiation) by utilizing a NOx-low-nitrogen burner combustion control loop, and if the NOx is continuously increased, continuously regulating and controlling the liquid injection amount of a denitration device through a PID control by utilizing a NOx-denitration liquid injection amount control loop to ensure that the NOx concentration measured by the first flue gas pollutant measuring device is maintained at a relatively low level; and/or the presence of a gas in the gas,
the method comprises the steps of monitoring the NOx emission concentration at the outlet of a boiler, which is obtained in real time by a first flue gas pollutant measuring device at the tail flue of the boiler, outside the boiler, and obtaining the NOx emission concentration in real time by a second flue gas pollutant measuring device at the tail flue of a desulfurization and dust removal device outside the boiler, calculating to obtain the amount of an oxidant to be added to a nitrogen oxide oxidation device, and then utilizing a second control loop of the input amount of NOx-oxidant to finely adjust the adding amount of the oxidant to the nitrogen oxide oxidation device through PID control.
In order to meet the ultra-low emission level, the NOx control cannot be too low, so that the ammonia injection amount is too large, and meanwhile, the NOx cannot be instantaneously increased too fast due to too high NOx, and the ammonia injection amount cannot keep up with the emission standard exceeding. Therefore, the NOx emission of the invention is generally controlled to be 40-45 mg/Nm3。
According to the method of the invention, the regulation further comprises SO2Control, in a specific embodiment, the boiler outlet SO obtained in real time by the boiler tail flue first smoke pollutant measuring device is monitored2The emission concentration is used as the input quantity of control, and SO is obtained in real time by a second flue gas pollutant measuring device at the tail flue of the desulfurization and dust removal device outside the furnace2Discharging concentration, calculating to obtain the desulfurization agent amount to be added by a desulfurizer adding device, and then utilizing SO2And the second control loop of the desulfurizer input amount finely adjusts the desulfurizer input amount through PID control.
PID as described in the present invention is a well established control method, e.g. NOx content over 300mg/Nm3The PID can automatically control its input parameters (proportional, integral, differential, etc.), and the operation thereof is well known in the art and will not be described further.
By adopting the technical scheme, the method has the following technical effects:
aiming at the pulverized coal industrial boiler, the invention comprehensively ensures that various pollutants realize ultralow emission by adopting modes of low-nitrogen combustion, in-furnace SNCR, out-furnace oxidation denitration, semi-dry desulfurization and the like, and simultaneously adopts a multi-loop automatic control mode, thereby solving the problems of poor coordinated control level of the pollutants, unstable system operation, multiple manual operation factors and the like of the pulverized coal industrial boiler.
The pulverized coal industrial boiler has small hearth size and a proper temperature range, is suitable for denitration in the boiler by adopting an SNCR (selective non catalytic reduction) method, can realize ultralow emission of NOx by combining a low-nitrogen burner and oxidation denitration outside the boiler, and can realize SO (sulfur oxide) by combining semi-dry desulfurization of a circulating fluidized bed outside the boiler2And ultra-low emission of dust.
The invention arranges a first flue gas pollutant measuring device in the tail flue of the boiler and a second flue gas pollutant measuring device in the tail flue of the desulfurizing and dedusting device outside the boiler, which can generate real-time signals and feed back the signals to a plurality of NOx control loops and SO2The control loop can realize the automatic cooperative control of low-nitrogen combustion in the furnace, SNCR denitration and oxide denitration outside the furnace, and can also improve the automatic control level of the desulfurizer of the desulfurization system outside the furnace.
The invention can realize the automatic control of the desulfurizer, improve the use efficiency of the desulfurizer and the denitration solution and reduce the consumption cost of the medicament.
In conclusion, the invention automatically combines various NOx control means according to the emission concentration of NOx to obtain the effective method for the cooperative removal and automatic control of pollutants inside and outside the pulverized coal industrial boiler and the furnace, thereby realizing the economical and stable operation of the pulverized coal industrial boiler system.
Drawings
FIG. 1 is a schematic structural diagram of a multi-pollutant cooperative control system of a coal-fired industrial boiler according to an example of the present invention.
Some of the reference numbers in the figures are explained below: 1-industrial boiler, 2-desulfurization dust removal device, 3-denitration device, 4-first flue gas pollutant measuring device, 5-nitrogen oxide oxidation device, 6-desulfurizer feeding device, and 7-second flue gas pollutantMeasuring device, 8-NOx-low-nitrogen burner combustion control loop, 9-NOx-SNCR liquid injection amount control loop, 10-NOx-oxidant input first control loop, 11-SO2First control Loop of desulfurizer input, 12-SO2The desulfurizer is added into the second control loop, and the 13-NOx-oxidant is added into the second control loop.
Detailed Description
In order to better understand the technical solution of the present invention, the following examples are further provided to illustrate the present invention, but the present invention is not limited to the following examples.
In the description of the present invention, the terms "first" and "second" are used for convenience of description and distinction only, and are not intended to limit the number or order. Each device or element used in the system of the present invention may employ corresponding devices or elements that are conventional in the art, unless otherwise specified.
As shown in fig. 1, a system for controlling multiple pollutants in a coal-fired industrial boiler in a coordinated manner according to an embodiment of the present invention includes: the coal-fired industrial boiler 1 is internally provided with a low-nitrogen burner for burning coal powder to form coal powder with concentration less than or equal to 300mg/Nm3Raw flue gas of NOx; the boilers are respectively connected and used for removing SO in the flue gas outside the furnace2The desulfurization and dust removal device 2, a denitration device 3 for denitration of flue gas in the furnace, and a nitrogen oxide oxidation device 4 for oxidizing NOx outside the furnace into acid oxides which are easily removed by the desulfurizer;
wherein, first flue gas pollutant measuring device 4 is connected to the afterbody flue department of boiler, second flue gas pollutant measuring device 7 is connected to desulfurization dust collector's afterbody flue department, first flue gas pollutant measuring device 4 or second flue gas pollutant measuring device 7 are arranged in NOx and SO in the real-time supervision flue gas2Concentration, and respectively forms a control loop with the low-nitrogen combustor, the desulfurization dust removal device, the denitration device and the nitrogen oxide oxidation device, namely the loop shown by the marks 8-13 in the figure, and specifically comprises the following steps: a NOx-low nitrogen burner combustion control circuit 8, a NOx-SNCR liquid injection amount control circuit 9, a NOx-oxidant input first control circuit 10, and SO2First control of desulfurizer inputLoop 11, SO2The desulfurizer charge second control circuit 12 and the NOx-oxidizer charge second control circuit 13.
For the convenience of understanding, the following examples illustrate the application operation of the cooperative control system of the present invention in the production process, and it should not be understood that the technical solution of the present invention is limited thereto:
the denitration device 3 is arranged in the range of the flue gas temperature of 800-950 ℃, a plurality of spray heads are arranged in the furnace, the SNCR denitration device is preferably selected in the embodiment to realize high-efficiency denitration, the denitration efficiency is 40-70%, and the denitration liquid is preferably 8% urea solution.
The nitrogen oxide oxidation device 5 uniformly sprays the oxidant into the flue gas, NOx is oxidized into acid oxide which is easily removed by the desulfurizer, and then ultralow emission is realized; the oxidizing agent is preferably ozone.
The desulfurization and dust removal device 2 is also connected with a desulfurizer input device 6, and the desulfurizer is preferably slaked lime. SO generation by partial combustion of pulverized coal in boiler2(SO2Concentration 1000mg/Nm3) The SO is realized by a desulfurizing and dust-removing device outside the furnace2The removal of the catalyst meets the requirement of ultra-low emission. The desulfurization and dust removal device 2 of the embodiment adopts a semi-dry desulfurization and dust removal device of a circulating fluidized bed outside the furnace.
The following describes the application of the cooperative control system and method of the present invention by some specific production examples, which are only for the understanding of the scheme of the present invention and should not be construed as limiting the invention thereto:
comparative example 1
1) The coal-fired industrial boiler 1 is provided with a non-low-nitrogen burner to burn coal powder to form a fuel containing NOx with the concentration of 350 +/-50 mg/Nm3Containing SO2The concentration is 1000mg/Nm3The temperature of raw flue gas in an ammonia spraying area in the furnace is 870 +/-20 ℃, and the temperature of flue gas at a desulfurization inlet outside the furnace is 120 +/-10 ℃;
2) 8 percent urea solution is sprayed into the furnace and is 3.0 plus or minus 0.62g (8 percent urea solution)/mg (NOx), and the NOx at the outlet of the boiler is reduced to about 245 plus or minus 30mg/Nm3；
3) Nitrogen oxide oxidation device 5 is to in boiler tail flue gas1.3 plus or minus 0.1mg (ozone)/mg (NOx) of oxidant is sprayed, and the concentration of NOx is reduced to about 30 plus or minus 15mg/Nm after passing through a desulfurization system3；
4) The amount of the slaked lime put into the desulfurization system is 5 +/-0.5 g (slaked lime)/mg (SO)2) Post-desulfurization system SO2The concentration is reduced to 20 +/-10 mg/Nm3。
The above operation conditions are data before the control method related to the embodiment of the present invention is applied.
Example 1
The control method of the coal-fired industrial boiler multi-pollutant cooperative control system comprises the following steps:
only putting the low-nitrogen combustor into the system and not putting the low-nitrogen combustor into the cooperative control system:
1) the coal-fired industrial boiler 1 burns pulverized coal through a low-nitrogen burner arranged in the coal-fired industrial boiler to form coal with the concentration of 260 +/-40 mg/Nm3NOx, 1000mg/Nm3SO of (A)2The temperature of the flue gas in an ammonia spraying area in the furnace is 860 +/-20 ℃, and the temperature of the flue gas at a desulfurization inlet outside the furnace is 115 +/-10 ℃;
2) the denitration device 3 sprays denitration liquid 1.23 plus or minus 0.41g (8 percent urea solution)/mg (NOx) into the smoke in the furnace, the nitric oxide oxidation device 5 sprays oxidant 1.25 plus or minus 0.1mg (ozone)/mg (NOx) into the smoke in the tail flue of the boiler, and the smoke discharged from the flue enters the desulfurization and dust removal device 2 outside the furnace to remove SO2(consumption of slaked lime is 5 + -0.5 g (slaked lime)/mg (SO)2))；
3) The concentration of NOx in the flue gas at the outlet of the boiler, which is obtained in real time by the measuring device 4 for monitoring the pollutants in the first flue gas in the tail flue of the boiler and is obtained by the measuring device 4, is 160 +/-30 mg/Nm3And the NOx concentration obtained in real time by the measuring device 7 for monitoring the second flue gas pollutants in the tail flue of the desulfurization and dust removal device is 38 +/-10 mg/Nm3And SO2Concentration 20 + -10 mg/Nm3；
After a low-nitrogen combustor is put into the system and a multi-pollutant cooperative control system is put into the system:
4) transmitting the feedback signals generated by the first flue gas pollutant measuring device 4 or the second flue gas pollutant measuring device 7 to the low-nitrogen combustor, the desulfurization and dust removal device 2, the denitration device 3 and the nitrogen oxide oxygen respectivelyA chemical conversion device 5; and regulating the amount of NOx generated by the low-nitrogen combustor to 220 +/-20 mg/Nm according to a feedback signal3And the input amount of flue gas treatment agent in the desulfurization dust-removing device 2, the denitration device 3 and the nitrogen oxide oxidation device 5, and the chimney discharge port SO2The concentration is controlled to be 25 +/-5 mg/Nm3The range and the NOx concentration are controlled to be 40 +/-5 mg/Nm3Within the range.
The smoke treatment agent in the step 4) comprises the following steps: the input amount of the denitration liquid in the denitration device 3 is 0.99 plus or minus 0.33g (8% urea solution)/mg (NOx), the input amount of the oxidant in the nitrogen oxide oxidation device 5 is 1.1 plus or minus 0.05mg (ozone)/mg (NOx), and the input amount of the desulfurizer in the desulfurization and dust removal device 2 is 4 plus or minus 0.3g (slaked lime)/mg (SO)2). On the whole, due to the improvement of the control precision, the system discharges NOx and SO on the premise of meeting the requirement of ultralow emission2The upper limit of the amount of the denitration agent, the denitration oxidant and the desulfurizer is improved, and the unit consumption of pollutants with the same amount in treatment is obviously reduced.
The regulation and control in the step 4) comprises the following steps: the method comprises the steps of combustion control of an NOx-low nitrogen burner in a furnace, control of NOx-denitration spray liquid, first control of input of NOx-oxidizing agent outside the furnace and second control of input of NOx-oxidizing agent.
In the embodiment, the NOx emission concentration in the flue gas at the outlet of the boiler, which is obtained in real time by a first flue gas pollutant measuring device at the tail flue of the boiler, is monitored in the boiler, the NOx generated by combustion of a low-nitrogen burner is regulated and controlled by a PID (proportion integration differentiation) by utilizing a NOx-low-nitrogen burner combustion control loop, if the NOx is continuously increased, the liquid injection amount of a denitration device is continuously regulated and controlled by a NOx-denitration liquid injection amount control loop by PID control, the concentration of the NOx measured by the first flue gas pollutant measuring device is ensured to be maintained at a high-precision control level and can be controlled to be 40 +/-5 mg/Nm3Within the range; and the number of the first and second groups,
the method comprises the steps of monitoring the NOx emission concentration at the outlet of a boiler, which is obtained in real time by a first flue gas pollutant measuring device at the tail flue of the boiler, outside the boiler, and obtaining the NOx emission concentration in real time by a second flue gas pollutant measuring device at the tail flue of a desulfurization and dust removal device outside the boiler, calculating to obtain the amount of an oxidant to be added to a nitrogen oxide oxidation device, and then utilizing a second control loop of the input amount of NOx-oxidant to finely adjust the adding amount of the oxidant to the nitrogen oxide oxidation device through PID control.
The regulation in the step 4) also comprises SO2Control, in this embodiment, boiler outlet SO obtained in real time by a boiler tail flue first flue gas pollutant measuring device is monitored2The emission concentration is used as the input quantity of control, and SO is obtained in real time by a second flue gas pollutant measuring device at the tail flue of the desulfurization and dust removal device outside the furnace2Discharging concentration, calculating to obtain the desulfurization agent amount to be added by a desulfurizer adding device, and then utilizing SO2The second control loop of the desulfurizer input amount finely adjusts the desulfurizer input amount and SO through PID control2The discharge concentration can be controlled to be 25 +/-5 mg/Nm3Within the range.
5) The temperature of the flue gas in an ammonia injection area in the furnace rises to 950 +/-20 ℃, firstly, the low-nitrogen burner is adjusted to reduce the temperature of the flue gas to 870 +/-20 ℃, and meanwhile, PID control fine adjustment is carried out to reduce or improve the injection amount of the urea solution according to the feedback of the increase and the reduction of the concentration of NOx; the temperature of the flue gas in the ammonia spraying area in the furnace rises, the temperature of the flue gas at the inlet of the desulfurizing tower outside the furnace rises by 10-20 ℃, the water spraying quantity is increased, the temperature of the flue gas is reduced, and meanwhile PID (proportion integration differentiation) reduces the temperature of the flue gas according to the SO at the outlet of the desulfurizing tower2When the concentration is increased, the sprayed amount of the slaked lime is properly reduced, and the process is automatically completed by PID.
The devices or elements related to the system of the present invention, such as a desulfurization dust removal device, an SNCR denitration device, a nitrogen oxide oxidation device, a desulfurizing agent charging device, a low-nitrogen combustor (for example, low-nitrogen combustion technology including SOFA (separation over-fire air), flue gas recirculation, etc.), etc., can all adopt the existing processing facilities, devices or elements with corresponding functions in the art, and are not described in detail. Those skilled in the art will understand or know what is not described herein, and will not be described in detail.
It will be appreciated by those skilled in the art that modifications or adaptations to the invention may be made in light of the teachings of the present specification. Such modifications or adaptations are intended to be within the scope of the present invention as defined in the claims.
Claims (10)
1. A coal-fired industrial boiler multi-pollutant cooperative control system is characterized in that: the method comprises the following steps: the coal-fired industrial boiler is characterized in that a low-nitrogen burner is arranged in the boiler and is used for burning coal powder to form coal powder with the concentration of less than or equal to 300mg/Nm3Raw flue gas of NOx; the boilers are respectively connected and used for removing SO in the flue gas outside the furnace2The desulfurization and dust removal device is used for a denitration device for denitration of flue gas in the furnace and a nitric oxide oxidation device for oxidizing NOx outside the furnace into acid oxides which are easily removed by a desulfurizer;
wherein, first flue gas pollutant measuring device is connected to the afterbody flue department of boiler, second flue gas pollutant measuring device is connected to desulfurization dust collector's afterbody flue department, first flue gas pollutant measuring device or second flue gas pollutant measuring device are arranged in NOx and SO in the real-time supervision flue gas2And the concentration of the flue gas is respectively controlled by the low-nitrogen combustor, the desulfurization and dust removal device, the denitration device and the nitrogen oxide oxidation device to form a control loop, so that feedback signals generated by the first flue gas pollutant measuring device or the second flue gas pollutant measuring device are respectively transmitted to the low-nitrogen combustor, the desulfurization and dust removal device, the denitration device and the nitrogen oxide oxidation device to regulate and control the NOx amount generated by the low-nitrogen combustor and the input amount of flue gas treatment agents in the desulfurization and dust removal device, the denitration device and the nitrogen oxide oxidation device.
2. The system of claim 1, wherein: the denitration device is communicated with a plurality of spray heads arranged in the boiler so as to spray denitration liquid to the smoke in the boiler, and the spray heads are arranged in the range of the smoke temperature of 800-950 ℃; the denitration liquid adopts ammonia water, urea solution or biological calcium-based denitration agent, and preferably adopts an SNCR denitration device.
3. The system according to claim 1 or 2, characterized in that: the nitrogen oxide oxidation device comprises an oxidant injection mechanism; the oxidizing agent includes, but is not limited to, ozone and/or sodium hypochlorite; the desulfurization and dust removal device is also connected with a desulfurizer input device, and preferably, the desulfurizer comprises one or more of slaked lime, modified slaked lime and carbide slag.
4. The system according to any one of claims 1-3, wherein: the control loop comprises a NOx control loop, and specifically comprises: a combustion control loop of the NOx-low nitrogen burner in the furnace, a NOx-denitration liquid injection amount control loop, a first control loop for feeding the NOx-oxidizing agent and a second control loop for feeding the NOx-oxidizing agent outside the furnace.
5. The system according to any one of claims 1-4, wherein: the control loop further comprises an SO2Control loop, including SO2First control loop of desulfurizer input and SO2-a second control loop for the devulcanizing agent input.
6. The control method of the coal-fired industrial boiler multi-pollutant cooperative control system according to any one of claims 1 to 5, characterized by comprising the steps of: the method comprises the following steps:
1) the coal-fired industrial boiler burns pulverized coal through a low-nitrogen burner arranged in the coal-fired industrial boiler to form coal powder with the concentration less than or equal to 300mg/Nm3Raw flue gas of NOx;
2) the denitration device sprays denitration liquid into the flue gas in the boiler, the nitrogen oxide oxidation device sprays oxidant into the flue gas in the tail flue of the boiler, and the flue gas discharged from the flue enters the desulfurization and dust removal device outside the boiler to remove SO2；
3) Monitoring the concentration of NOx in the flue gas at the outlet of the boiler, which is obtained by a first flue gas pollutant measuring device at the tail flue of the boiler in real time, and monitoring the concentration of NOx and SO which are obtained by a second flue gas pollutant measuring device at the tail flue of the desulfurization and dust removal device in real time2Concentration;
4) respectively transmitting feedback signals generated by the first flue gas pollutant measuring device or the second flue gas pollutant measuring device to the low-nitrogen combustor, the desulfurization and dust removal device, the denitration device and the nitric oxide oxidation device; and regulating the amount of NOx generated by the low-nitrogen combustor and the input amount of flue gas treatment agents in the desulfurization and dust removal device, the denitration device and the nitrogen oxide oxidation device according to the feedback signal.
7. The method of claim 6, wherein: the smoke treatment agent comprises: the denitration liquid in the denitration device, the oxidant in the nitrogen oxide oxidation device and the desulfurizer in the desulfurization and dust removal device.
8. The method according to claim 6 or 7, characterized in that: the regulation and control in the step 4) comprises the following steps: the method comprises the steps of combustion control of an NOx-low nitrogen burner in a furnace, control of NOx-denitration spray liquid, first control of input of NOx-oxidizing agent outside the furnace and second control of input of NOx-oxidizing agent.
9. The method of claim 8, wherein: the regulation and control method in the step 4) comprises the following steps: in a boiler, monitoring the NOx emission concentration in the flue gas at the outlet of the boiler, which is obtained in real time by a first flue gas pollutant measuring device at the tail flue of the boiler, firstly regulating and controlling the NOx generated by the combustion of a low-nitrogen burner through a PID (proportion integration differentiation) by using a NOx-low-nitrogen burner combustion control loop, and if the NOx is continuously increased, continuously regulating and controlling the liquid injection amount of a denitration device through the PID by using a NOx-denitration liquid injection amount control loop to ensure that the NOx concentration measured by the first flue gas pollutant measuring device is maintained at a lower level; and/or the presence of a gas in the gas,
outside the furnace, monitoring the NOx emission concentration at the outlet of the boiler obtained by a first flue gas pollutant measuring device at the tail flue of the boiler in real time as the input quantity of control, obtaining the NOx emission concentration in real time by a second flue gas pollutant measuring device at the tail flue of a desulfurization and dust removal device outside the furnace, calculating to obtain the oxidant dosage to be added by a nitrogen oxide oxidation device, and then utilizing a second control loop of the input of NOx-oxidant to finely adjust the oxidant dosage of the nitrogen oxide oxidation device through PID control.
10. The method according to claim 6 or 7, characterized in that: the tone isControlling also includes SO2The control method comprises the following steps: boiler outlet SO obtained in real time by monitoring boiler tail flue first flue gas pollutant measuring device2The emission concentration is used as the input quantity of control, and SO is obtained in real time by a second flue gas pollutant measuring device at the tail flue of the desulfurization and dust removal device outside the furnace2Discharging concentration, calculating to obtain the desulfurization agent amount to be added by a desulfurizer adding device, and then utilizing SO2And the second control loop of the desulfurizer input amount finely adjusts the desulfurizer input amount through PID control.
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