Air pre-heater anti-blocking method and system based on sulfur trioxide monitoring
Through the optimization of sulfur trioxide monitoring technical route and flue gas treatment parameters, the problem of air preloader blockage is solved, effective anti-blocking effect is achieved, and equipment maintenance costs and operating costs are reduced.
Patent Information
- Application Number
- CN202510475739.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-15
- Publication Date
- 2025-07-08
AI Technical Summary
The prior art hollow preloader has poor anti-blocking effect, especially the blockage problem caused by sulfur trioxide emissions is difficult to effectively solve.
Through a sulfur trioxide monitoring method, combined with coal quality analysis, equipment parameters and on-site testing, a technical route for sulfur trioxide concentration monitoring is established, the parameters of flue gas treatment facilities are optimized, and anti-blocking measures are generated, including controlling coal-fired sulfur content, adjusting SNCR operating parameters and optimizing soot blowing methods.
Effectively prevent air preload blockage, reduce the generation of ammonia bisulfate, reduce equipment maintenance costs, and improve equipment operation efficiency.
Smart Images
Figure CN120274284A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of sulfur trioxide monitoring, and in particular to a method and system for preventing air preheater blockage based on sulfur trioxide monitoring. Background Art
[0002] Coal has long dominated the energy consumption structure. During the combustion process of coal, a large amount of toxic and harmful air pollutants such as fine particulate matter (PM), sulfur dioxide (SO2), and nitrogen oxides (NOx) are generated, which is one of the main causes of smog weather. In order to meet strict emission standards, coal-fired power units have successively carried out upgrades and transformations of environmental protection facilities. While significantly reducing emissions of the three major pollutants PM, SO2, and NOx, new problems have emerged. Sulfur trioxide (SO3) is one of the most prominent problems. The emission of SO3 has caused environmental problems such as colored plumes and flue gas trailing, and has led to operational problems such as air preheater blockage and equipment corrosion.
[0003] Therefore, how to prevent the blockage of the air preheater by monitoring the emission of SO3 has become a technical problem that needs to be solved urgently by those skilled in the art. Summary of the Invention
[0004] The present invention provides a method and system for preventing air preheater blockage based on sulfur trioxide monitoring to solve the defect of poor air preheater blockage prevention effect in the prior art.
[0005] In a first aspect, the present invention provides a method for preventing air preheater blockage based on sulfur trioxide monitoring, including: Estimating the original value of sulfur trioxide concentration based on coal quality analysis, equipment description, and on-site testing; Using a combination of a sulfur trioxide sampling device and instrumental analysis, and respectively testing the sulfur trioxide concentration sampling values at the inlet and outlet of the dust collector, the inlet and outlet of desulfurization, and the chimney inlet by the representative point sampling method; Based on the original value of sulfur trioxide concentration and the sulfur trioxide concentration sampling values, determining the generation and transformation law and emission characteristics of sulfur trioxide, and establishing a sulfur trioxide monitoring technical route; Based on the sulfur trioxide monitoring technical route and the operating parameters of the flue gas treatment facility, determining a sulfur trioxide emission reduction plan; Combining the operating parameters of the air preheater and the sulfur trioxide emission reduction plan to generate air preheater blockage prevention measures.
[0006] According to the method for preventing air preheater blockage based on sulfur trioxide monitoring provided by the present invention, the estimating the original value of sulfur trioxide concentration based on coal quality analysis, equipment description, and on-site testing includes: Determining coal quality parameters, equipment parameters, and test parameters, and determining sampling points based on the coal quality parameters, equipment parameters, and test parameters; Estimate the original value of sulfur trioxide concentration based on the total sulfur content of the coal and the sulfur dioxide concentration at the sampling point.
[0007] According to an air preheater anti-clogging method based on sulfur trioxide monitoring provided by the present invention, the determination of the generation and transformation law of sulfur trioxide includes: Monitor the combustion process of the coal in the furnace; Determine the four sulfur trioxide generation reactions during the combustion process; Through the four sulfur trioxide generation reactions, determine the influence of the furnace temperature and the concentration of free radical oxygen atoms on the generation amount of sulfur trioxide.
[0008] According to an air preheater anti-clogging method based on sulfur trioxide monitoring provided by the present invention, it further includes: Determine the catalytic effect of fly ash in the furnace flue gas on the generation of sulfur trioxide; Based on the catalytic effect, determine the adsorption effect of the surface area of the fly-back conveying structure and the active metal oxides in the fly ash on sulfur dioxide and oxygen, and promote the conversion of sulfur trioxide.
[0009] According to an air preheater anti-clogging method based on sulfur trioxide monitoring provided by the present invention, the determination of the generation and transformation law and emission characteristics of sulfur trioxide, and the establishment of a sulfur trioxide monitoring technical route include: Determine the influence of the SNCR denitration system on the generation amount of sulfur trioxide, the influence of the air preheater on the sulfur trioxide removal rate, the influence of the electrostatic bag filter on the sulfur trioxide removal rate, the influence of the wet desulfurization on the sulfur trioxide removal rate, and the analysis of ammonium bisulfate in the fly ash, so as to obtain the sulfur trioxide emission characteristics; Combined with the sulfur trioxide emission characteristics, determine the circulating fluidized bed unit using SNCR, electrostatic bag filter and wet desulfurization as the sulfur trioxide monitoring technical route.
[0010] According to an air preheater anti-clogging method based on sulfur trioxide monitoring provided by the present invention, when establishing the sulfur trioxide monitoring technical route, it further includes; Determine the points convenient for examining the sulfur trioxide removal rate of a single device during the adjustment of operating parameters as the monitoring points before and after the device; Determine the points for monitoring the sulfur trioxide concentration before entering the atmosphere as the desulfurization outlet monitoring points.
[0011] According to an air preheater anti-clogging method based on sulfur trioxide monitoring provided by the present invention, the determination of the sulfur trioxide emission reduction plan includes: For the same type of units, adopt the method of adjusting the ammonia-nitrogen molar ratio and the pH value of the wet desulfurization slurry to reduce the sulfur trioxide emission.
[0012] A method for preventing air preheater blockage based on sulfur trioxide monitoring provided by the present invention, the generation of air preheater anti-blockage measures includes: By controlling the sulfur content of coal, the generation of sulfur trioxide in the furnace is reduced to prevent air preheater blockage; By adjusting the operating parameters of SNCR, the ammonia escape amount and sulfur trioxide amount entering the air preheater system are reduced to prevent air preheater blockage; By optimizing the soot blowing method, the average thickness of ash accumulation on the convective heating surface is reduced, and the catalytic oxidation of sulfur dioxide by fly ash is reduced to prevent air preheater blockage.
[0013] A method for preventing air preheater blockage based on sulfur trioxide monitoring provided by the present invention, the optimization of the soot blowing method to reduce the average thickness of ash accumulation on the convective heating surface and reduce the catalytic oxidation of sulfur dioxide by fly ash includes: Conduct air preheater soot blowing according to the operating regulations. When the differential pressure of the air preheater shows an upward trend, increase the number of soot blowing times; Prevent the soot blowing steam from carrying water. Before the steam soot blowing of the air preheater, sufficient drainage is required to make the steam temperature reach the requirements of the soot blower and then conduct the purge; Through experiments, raise the air preheater soot blowing steam to the preset range to ensure the soot blowing effect at the cold end of the air preheater; Modify the forward and backward program so that the forward and backward pause points are not in the same area to ensure that the soot blowing range covers the entire air preheater area; Control the differential pressure. When the differential pressure at the inlet and outlet of the air preheater exceeds the design value, the cold end soot blowing is changed to continuous soot blowing until the differential pressure drops below the design value.
[0014] In the second aspect, the present invention also provides an air preheater anti-blockage system based on sulfur trioxide monitoring, including: A monitoring route establishment module, used to estimate the original value of sulfur trioxide concentration based on coal quality analysis, equipment description and on-site tests; combine the sulfur trioxide sampling device and instrumental analysis, and use the representative point sampling method to test the sulfur trioxide concentration sampling values at the inlet and outlet of the dust collector, the inlet and outlet of desulfurization, and the chimney inlet respectively; based on the original value of sulfur trioxide concentration and the sulfur trioxide concentration sampling value, determine the generation and transformation law and emission characteristics of sulfur trioxide, and establish a sulfur trioxide monitoring technical route; An air preheater anti-blockage module, used to determine a sulfur trioxide emission reduction plan based on the sulfur trioxide monitoring technical route and the operating parameters of the flue gas treatment facility; combine the operating parameters of the air preheater and the sulfur trioxide emission reduction plan to generate air preheater anti-blockage measures.
[0015] In a third aspect, the present invention further provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, the method for preventing air preheater blockage based on sulfur trioxide monitoring as described in any one of the above is implemented.
[0016] In a fourth aspect, the present invention further provides a non-transitory computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the method for preventing air preheater blockage based on sulfur trioxide monitoring as described in any one of the above is implemented.
[0017] In a fifth aspect, the present invention further provides a computer program product, including a computer program. When the computer program is executed by a processor, the method for preventing air preheater blockage based on sulfur trioxide monitoring as described in any one of the above is implemented.
[0018] A method and system for preventing air preheater blockage based on sulfur trioxide monitoring provided by the present invention. The method estimates the original value of sulfur trioxide concentration based on coal quality analysis, equipment description, and on-site testing; combines a sulfur trioxide sampling device and instrumental analysis, and uses the representative point sampling method to respectively test the sulfur trioxide concentration sampling values at the inlet and outlet of the dust collector, the inlet and outlet of desulfurization, and the inlet of the chimney; determines the generation and transformation law and emission characteristics of sulfur trioxide based on the original value of sulfur trioxide concentration and the sulfur trioxide concentration sampling value, and establishes a sulfur trioxide monitoring technical route; determines a sulfur trioxide emission reduction plan based on the sulfur trioxide monitoring technical route and the operating parameters of the flue gas treatment facility; combines the operating parameters of the air preheater and the sulfur trioxide emission reduction plan to generate air preheater blockage prevention measures. Since the facility parameters are optimized through the monitoring and emission characteristics of sulfur trioxide, and thus the air preheater blockage is prevented. The method of preventing air preheater blockage starting from sulfur trioxide effectively improves the effect of preventing air preheater blockage. Description of the Drawings
[0019] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.
[0020] Figure 1 is a schematic flow chart of the method for preventing air preheater blockage based on sulfur trioxide monitoring provided in this embodiment; Figure 2 is a schematic diagram of the distribution of sulfur trioxide test sampling points provided in this embodiment; Figure 3 is a schematic structural diagram of the system for preventing air preheater blockage based on sulfur trioxide monitoring provided in this embodiment; Figure 4It is a schematic structural diagram of the electronic device provided in this embodiment. Detailed implementation manners
[0021] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below with reference to the accompanying drawings in the present invention. Obviously, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without any creative efforts shall fall within the protection scope of the present invention.
[0022] Figure 1 It is a schematic flowchart of the air preheater anti-clogging method based on sulfur trioxide monitoring provided in this embodiment.
[0023] As Figure 1 shown, the air preheater anti-clogging method based on sulfur trioxide monitoring provided in the embodiment of the present invention mainly includes the following steps: 101. Estimate the original value of sulfur trioxide concentration based on coal quality analysis, equipment description and on-site test.
[0024] In a specific implementation process, a supercritical parameter variable pressure operating circulating fluidized bed boiler is taken as an example for illustration. First, determine the coal quality parameters, equipment parameters and test parameters, and determine the sampling points based on the coal quality parameters, equipment parameters and test parameters; estimate the original value of sulfur trioxide concentration according to the total sulfur content of the coal and the sulfur dioxide concentration at the sampling points. The equipment parameters include boiler parameters, denitration system parameters, air preheater parameters, dust collector parameters, etc.
[0025] Among them, the boiler parameters include: maximum continuous evaporation rate (BMCR), rated evaporation rate (BRL), rated steam pressure (outlet of superheater), rated steam temperature (outlet of superheater), steam flow rate (BMCR / BRL), inlet / outlet steam pressure (BMCR), inlet / outlet steam pressure (BRL), inlet / outlet steam temperature (BMCR), inlet / outlet steam temperature (BRL), feed water temperature (BMCR) and feed water temperature (BRL), etc.
[0026] The denitration system parameters include: wet flue gas volume at the SNCR inlet (standard condition), flue gas composition at the inlet, water, oxygen, nitrogen, carbon dioxide, pollutant concentration (6% O2, standard condition, dry basis), nitrogen oxides at the SNCR inlet, nitrogen oxides at the SNCR outlet and ammonia slip at the denitration outlet, etc.
[0027] The air preheater parameters include: the primary air temperature at the inlet of the air preheater, the secondary air temperature at the inlet of the air preheater, the hot primary air temperature at the outlet of the air preheater, the hot secondary air temperature at the outlet of the air preheater, the primary air rate (only the bottom furnace fluidizing air), the secondary air rate, the average bed temperature, the flue gas temperature at the furnace outlet, the slag temperature at the outlet of the slag cooler, the excess air coefficient at the furnace outlet, the furnace air leakage coefficient, the excess air coefficient at the economizer outlet, the excess air coefficient at the air preheater outlet, the flue gas temperature at the economizer outlet, the flue gas temperature at the air preheater outlet (before / after correction), the air temperature at the inlet of the air preheater, the fluidization velocity of the empty bed, the resistance of the empty bed, the volumetric heat load of the furnace, and the fly ash concentration at the outlet of the boiler air preheater, etc.
[0028] The dust collector parameters include: the inlet flue gas temperature, the actual wet flue gas volume at the inlet of the dust collector (considering a 10% margin and a 10°C margin for flue gas temperature), the excess air coefficient at the inlet of the dust collector, the dust amount at the inlet of the dust collector, performance guarantee, the dust removal efficiency of the electric field and bag area under normal conditions, the emission value of the dust removal efficiency of the second electric field after the first electric field is out of service, the body resistance, the body air leakage rate, and the noise.
[0029] As Figure 2 Shown is the schematic diagram of the distribution of sulfur trioxide test sampling points. Five sampling points A - E are arranged for the test sampling points, and the ash sample sampling position is point B, and the SCR is reserved. After determining the sampling points, according to the total sulfur in the coal and the measured value at point A, the original value of sulfur trioxide can be estimated, as shown in Table 1:
[0030] Table 1 It is known that sulfur trioxide after the air preheater combines with water vapor in the flue gas and mainly exists in the form of sulfuric acid aerosol. The sulfuric acid aerosol particles are PM1.0 submicron ultra-fine particles, and the particle size is mainly between 0.1 µm - 0.6 µm, which is the main reason for the "blue smoke" formed in the chimney. When the sulfuric acid aerosol concentration exceeds 21.88 mg / m3, obvious "blue smoke" will appear in the chimney. Therefore, it can be seen from the above estimations that if no emission reduction treatment is carried out, "blue smoke" will occur in the chimney exhaust.
[0031] 102. Combine the sulfur trioxide sampling device and instrumental analysis, and use the representative point sampling method to respectively test the sampling values of sulfur trioxide concentration at the inlet and outlet of the dust collector, the inlet and outlet of desulfurization, and the inlet of the chimney.
[0032] Among them, the sulfur trioxide sampling device and instruments mainly include: an isokinetic sampling console and a supporting SO3 sampling device, a thermometer, an ultra-low concentration dust sampler, a single-point thermometer, an automatic smoke and dust tester, a portable infrared multi-group gas analyzer, an infrared flue gas analyzer, a multi-functional flue gas moisture meter, an elemental analyzer, an ion chromatography analyzer, an electronic balance, a flue gas fly ash sampling gun, and a pH meter, etc.
[0033] The sampling process is as follows: (1)Preparation before sampling: Clean the sampling pipeline such as the sampling tube, serpentine condenser, and impinger with acetone and dry them in the air; (2)Connect the sampling equipment, turn on the circuit, set the pump for constant-speed sampling and set the sampling rate to less than 12 L / min. Plug the sampling nozzle, start the sampling pump for pressure test to check airtightness. If the flow rate is less than 4% of the sampling flow rate, it means good airtightness. If it fails, check the leakage location and re-perform the airtightness test; (3)Preheat the sampling gun to 260 °C and adjust the electric heating tape of the condenser to control the water bath temperature of the condenser according to the preset value; (4)The absorbent liquid in the absorption bottle is a 3% (by volume) hydrogen peroxide solution; (5)Insert the sampling gun into the measuring hole, turn on the sampling pump for sampling. The extracted flue gas volume is controlled by the extraction time and meets the analysis requirements. Generally, sample for 45 min; (6)After sampling, rinse the serpentine condenser with 80% isopropanol solution, mix the washing liquid and make up the volume to a 250 ml volumetric flask; (7)Collect 4 groups of samples for each measurement and seal and properly store the samples.
[0034] During the test, the unit's electric load was 350 MW, the load fluctuation <5%. Take 3 groups of parallel samples at each sampling point and use the arithmetic mean as the final test result. The test was divided into 4 working conditions according to the different pH values of the wet flue gas desulfurization absorption tower slurry, so as to complete the sampling of sulfur trioxide concentration at the inlet and outlet of the dust collector, the inlet and outlet of desulfurization, and the inlet of the chimney.
[0035] 103. Based on the original value of sulfur trioxide concentration and the sampled value of sulfur trioxide concentration, determine the generation and transformation law and emission characteristics of sulfur trioxide, and establish a sulfur trioxide monitoring technical route.
[0036] Specifically, monitor the combustion process of coal in the furnace. During the combustion process of coal, the combustible sulfur contained will be oxidized to SO2, and a part of SO2 will be further oxidized to SO3. Determine the four sulfur trioxide generation reactions during the combustion process, such as (1)(2)(3)(4); (1) (2) (3) (4) Let M be any molecule such as N2, CO2, H2O, O2, etc. Through four sulfur trioxide formation reactions, the effects of furnace temperature and free radical oxygen atom concentration on the amount of sulfur trioxide formed are determined. Reaction (1) is the main pathway for SO2 to transform into SO3 under high-temperature conditions (1100 - 1400 °C), that is, when an SO2 molecule encounters free oxygen, it reacts to form SO3, and SO2 collides with free radical oxygen atoms and M to form SO3. At 400 - 1100 °C, the main reactions affecting SO3 formation are (2), (3), and (4). The higher the combustion temperature, the more free radical oxygen atoms, and the equilibrium shifts towards the formation of SO3, and the concentration of SO3 will also increase. The larger the excess air coefficient, that is, the higher the oxygen concentration and the higher the free radical oxygen atom concentration, the higher the oxidation rate of SO2 in the furnace. However, due to the very small concentration of free oxygen atoms and insufficient residence time under actual furnace combustion conditions, the general proportion of SO2 oxidized to SO3 is 0.5% - 1.5%. In addition, the amount of SO3 formed in the furnace also depends on conditions such as the sulfur content of the coal, boiler type, and combustion conditions. Burning high-sulfur coal can make SO3 reach 30 ppm - 40 ppm or even higher.
[0037] In addition to temperature and oxygen concentration, the sulfur trioxide formation reactions in the furnace include homogeneous gas-phase reactions, suspension fly ash catalysis, tube wall ash deposition catalysis, and closed metal oxide catalysis reactions. The promotion of SO3 catalytic formation by fly ash in the flue gas mainly includes two aspects: one is that the transport structure of fly ash results in a relatively large specific surface area, and the adsorption rates of SO2 and O2 on its surface are relatively high, so the oxidation reaction is promoted; the other is that active metal oxides such as Fe2O3 contained in fly ash will also enhance the adsorption of SO2 on the fly ash surface. And the injection of ammonia in SNCR changes the formation mechanism and main path of SO3, significantly promoting the conversion of SO2 to SO3 in the flue gas.
[0038] Specifically, establish a sulfur trioxide monitoring technical route, including: determining the impact of the SNCR denitration system on the amount of sulfur trioxide generated, the impact of the air preheater on the sulfur trioxide removal rate, the impact of the electrostatic bag filter on the sulfur trioxide removal rate, the impact of wet flue gas desulfurization on the sulfur trioxide removal rate, and the analysis of ammonium bisulfate in fly ash, to obtain the sulfur trioxide emission characteristics; combined with the sulfur trioxide emission characteristics, determine the circulating fluidized bed unit using SNCR, electrostatic bag filter, and wet flue gas desulfurization as the sulfur trioxide monitoring technical route.
[0039] Among them, the influence of the SNCR denitration system on the SO3 generation amount: With the increase of the ammonia-nitrogen molar ratio, the SO3 concentration shows a trend of first increasing and then decreasing, reaching the peak at the ammonia-nitrogen molar ratio of 1.5. Research shows that SNCR promotes the oxidation of SO2 to SO3. The main generation path of SO3 is the reaction of SO2 and O2, followed by the reaction of SO2 and NO2. When SCNR is input, the O2 concentration and NO2 concentration increase, which is the main mechanism for promoting the generation of SO3. In addition, with the increase of the ammonia-nitrogen molar ratio, the ammonia slip at the air preheater outlet shows a jump after the ammonia-nitrogen molar ratio of 1.2. Therefore, considering the ammonia slip and the reductant consumption comprehensively, it is considered that the ammonia-nitrogen molar ratio is reasonably set between 0.8 and 1.2.
[0040] The influence of the air preheater on the SO3 removal rate: The SO3 removal rate of the air preheater is basically between 25% and 40%. Since a small part of the SO3 entering the air preheater is deposited inside the air preheater, and most of the rest enters the dust collector with fly ash and flue gas, for the air preheater, the SO3 removal rate is the SO3 deposition rate. The higher the SO3 concentration at the air preheater inlet, the more SO3 is deposited inside it, and the higher the risk of generating ammonium bisulfate. About 30% of the ammonium bisulfate will be deposited in the air preheater, and the rest will leave the air preheater in the form of aerosol.
[0041] The influence of the electrostatic bag filter on the SO3 removal rate: In the working temperature range of the dust collector, SO3 mainly exists in the forms of gaseous SO3 and H2SO4 aerosol. It can be seen from the test data that the SO3 removal rate of the electrostatic bag filter is above 40%. The removal of SO3 by the dust collector may be because there are both physical adsorption and chemical adsorption in the dust collector. Gaseous SO3 and H2SO4 aerosol are adsorbed in the cake layer on the surface of the dust collector filter bag due to physical adsorption. In addition, it also reacts with metal oxides in fly ash to form relatively stable sulfates.
[0042] Influence of wet desulfurization on the SO3 removal rate: The SO3 removal rate of wet desulfurization is affected by various factors such as the inlet flue gas temperature, liquid-gas ratio, flue gas flow rate, spray layer coverage area, and slurry pH value. Considering the actual on-site situation, the experiment relies on adjusting the slurry pH to change the SO3 removal rate. The liquid-gas ratio is one of the important parameters affecting gas-liquid mass transfer performance. The liquid-gas ratio of the first-stage tower is slightly higher than that of the second-stage tower (1.08 times that of the second-stage tower). The higher the liquid-gas ratio, the higher the relative velocity of the gas-liquid two-phase, the stronger the gas's fragmentation effect on the liquid droplets, the more desulfurization slurry droplets are discharged from the system with the evaporation effect, and the more droplets are entrained by the flue gas. As a result, the SO3 removal rate of the second-stage tower is higher than that of the first-stage tower. The number of demister stages and the residence time of the flue gas in the absorption tower of the second-stage tower are both higher than those of the first-stage tower, which prolongs the contact time between the sulfuric acid aerosol and the slurry and provides favorable conditions for gas-liquid mass transfer in the tower. The slurry pH of the second-stage tower is higher than that of the first-stage tower, which is more conducive to the absorption of acidic gases by the slurry. Therefore, it can be considered feasible to increase the SO3 removal rate by appropriately increasing the slurry pH value.
[0043] Analysis of ammonium bisulfate in fly ash: Usually, the dew point of ammonium bisulfate is 147°C. When the ambient temperature reaches this temperature, ammonium bisulfate accumulates on the surface of objects in liquid form or is dispersed in the flue gas in the form of liquid droplets. Ammonium bisulfate is a very sticky substance that is extremely difficult to remove from objects and has strong hygroscopicity. When the temperature continues to rise above 250°C, ammonium bisulfate sublimes from liquid to gas. The operating temperature gradient of the boiler air preheater is generally between 120 - 300°C. The physical properties of ammonium bisulfate determine that it deposits in the low-temperature area of the air preheater as the flue gas temperature drops significantly in the air preheater. The un-deposited ammonium bisulfate adsorbs on the soot in the flue gas and converts to solid state, which is removed in the electrostatic precipitator. The fly ash also contains SO4 2- 、NH4 + and the pH value of the leachate is between 2 - 4. Based on this, it can be determined that the fly ash contains ammonium bisulfate.
[0044] Furthermore, when determining the monitoring route, two monitoring points need to be set at the inlet and outlet of the desulfurization system. Specifically, a point that is convenient for examining the SO3 removal rate of a single device during the adjustment of operating parameters is determined as the monitoring point before and after the device; a point for monitoring the SO3 concentration before entering the atmosphere is determined as the desulfurization outlet monitoring point. Taking timely control measures when the concentration is too high helps prevent the occurrence of the "blue smoke" phenomenon.
[0045] 104. Based on the SO3 monitoring technical route and the operating parameters of the flue gas treatment facilities, determine the SO3 emission reduction plan.
[0046] Specifically, the SO3 co-removal rates of the system under different test conditions show that when the SNCR ammonia-nitrogen molar ratio is 1.2 and the pH of the desulfurization system slurry is 5.45 (in the first tower) and 6.28 (in the second tower), the SO3 removal rate of the system is relatively high. During the test, the differential pressure of the air preheater basically fluctuated between 1.245 kPa and 1.326 kPa. Therefore, for the same type of units, the SO3 emissions can be reduced by adjusting the ammonia-nitrogen molar ratio and the pH value of the wet desulfurization slurry.
[0047] 105. Combine the operating parameters of the air preheater and the sulfur trioxide emission reduction plan to generate anti-blocking measures for the air preheater.
[0048] According to the equilibrium theory of the SO3-H2O-H2SO4 coexisting gaseous mixture system, during the process of flue gas cooling, the proportion of SO3 transformed into H2SO4 continuously increases. When the flue gas temperature drops below 110 °C, all the SO3 in the flue gas will be transformed into H2SO4 vapor, and this temperature point happens to be basically the same as the outlet flue gas temperature of the air preheater, resulting in the condensation of H2SO4 in the flue gas and its adhesion on the surface of fly ash and the heat exchange elements of the air preheater. In addition, according to the different outlet temperatures of the air preheater, the deposition rate of SO3 in the air preheater ranges from 0% to 40%, specifically depending on flue gas temperature, fuel type, fly ash characteristics, the cold-end temperature of the air preheater, etc. And reducing the flue gas temperature by 22 °C can increase the SO3 deposition rate by 25%, and the faster the flue gas cools down, the lower the outlet temperature of the air preheater, and the higher the deposition rate of SO3.
[0049] Therefore, generate anti-blocking measures for the air preheater, including: preventing the blockage of the air preheater by controlling the sulfur content of the coal to reduce the generation of sulfur trioxide in the furnace. The sulfur content of the coal is directly related to the generation of SO3. Therefore, the most direct and effective control measure is to adopt the source control method to control the sulfur content of the coal, thereby reducing the amount of SO3 generated in the furnace. On the premise of reasonably controlling the combustion efficiency of the boiler, reducing the combustion temperature and the excess air coefficient is also beneficial to inhibiting the generation of SO3. Low-nitrogen combustion technologies such as low-excess-air coefficient combustion or rich-lean combustion method adopted can form a reducing atmosphere of fuel-rich combustion in the furnace, which also helps to reduce the generation of SO3 in the furnace.
[0050] It is also possible to prevent the blockage of the air preheater by adjusting the operating parameters of SNCR to reduce the ammonia slip and the amount of sulfur trioxide entering the air preheater system. When the boiler is at 350 MW, when the ammonia-nitrogen molar ratio of SNCR is 0.8 - 1.2, the amount of SO3 entering the air preheater is less.
[0051] It is also possible to prevent the blockage of the air preheater by optimizing the soot blowing method to reduce the average thickness of the ash deposit on the convective heating surface, lower the surface temperature of the fly ash layer, and reduce the catalytic oxidation of sulfur dioxide by fly ash. Specifically as follows: Perform air preheater soot blowing according to the operating procedures. When the differential pressure of the air preheater shows an upward trend, increase the number of soot blowing times. When necessary, high-pressure water flushing is required.
[0052] Prevent the soot blowing steam from carrying water. Before the steam soot blowing of the air preheater, sufficient drainage is required to make the steam temperature reach the requirements of the soot blower and then perform the blowing; the soot blowing pressure of the air preheater should be within the design range, generally maintained between 0.8 MPa and 1.5 MPa. If the soot blowing pressure is too low, the soot blowing effect is poor; if the soot blowing pressure is too high, it is easy to damage the air preheater body.
[0053] Through tests, increase the soot blowing steam of the air preheater to the preset range to ensure the soot blowing effect at the cold end of the air preheater.
[0054] Modify the forward and backward procedures so that the forward and backward pause points are not in the same area to ensure that the soot blowing range covers the entire air preheater area.
[0055] Control the differential pressure. When the differential pressure at the inlet and outlet of the air preheater exceeds the design value, the cold end soot blowing is changed to continuous soot blowing until the differential pressure drops below the design value.
[0056] The method of the present invention reduces the generation amount of sulfur trioxide, reduces the generation of ammonium bisulfate, thereby reducing the risk of blockage of the air preheater caused by ammonium bisulfate, can reduce the power consumption of the induced draft fan, directly save the electricity cost, and in addition, can also reduce the labor and maintenance costs, and the indirect economic benefits are relatively considerable.
[0057] Based on the same general inventive concept, the present invention also protects an air preheater anti-blocking system based on sulfur trioxide monitoring. The air preheater anti-blocking system based on sulfur trioxide monitoring described below can be mutually corresponded and referred to the air preheater anti-blocking method based on sulfur trioxide monitoring described above.
[0058] Figure 3 It is a schematic structural diagram of the air preheater anti-blocking system based on sulfur trioxide monitoring provided in this embodiment.
[0059] As Figure 3 shown, an air preheater anti-blocking system based on sulfur trioxide monitoring provided in this embodiment includes: A monitoring route establishment module 301, which is used to estimate the original value of sulfur trioxide concentration based on coal quality analysis, equipment description and on-site tests; combine the sulfur trioxide sampling device and instrumental analysis, and use the representative point sampling method to respectively test the sulfur trioxide concentration sampling values at the inlet and outlet of the dust collector, the inlet and outlet of desulfurization, and the inlet of the chimney; based on the original value of sulfur trioxide concentration and the sulfur trioxide concentration sampling values, determine the generation and transformation law and emission characteristics of sulfur trioxide, and establish a sulfur trioxide monitoring technical route; The air preheater anti-blocking module 302 is used to determine the sulfur trioxide emission reduction plan based on the sulfur trioxide monitoring technical route and the operating parameters of the flue gas treatment facility; and generate the air preheater anti-blocking measures by combining the air preheater operating parameters and the sulfur trioxide emission reduction plan.
[0060] Figure 4 It is a schematic structural diagram of the electronic device provided in this embodiment.
[0061] As Figure 4 shown, the electronic device may include: a processor 410, a communications interface 420, a memory 430, and a communication bus 440. Among them, the processor 410, the communications interface 420, and the memory 430 complete mutual communication through the communication bus 440. The processor 410 can call the logical instructions in the memory 430 to execute the air preheater anti-blocking method based on sulfur trioxide monitoring. The method includes: estimating the original value of sulfur trioxide concentration based on coal quality analysis, equipment description, and on-site tests; using a combination of sulfur trioxide sampling devices and instrumental analysis, and using the representative point sampling method to separately test the sulfur trioxide concentration sampling values at the inlet and outlet of the dust collector, the inlet and outlet of desulfurization, and the chimney inlet; determining the generation and conversion law and emission characteristics of sulfur trioxide based on the original value of sulfur trioxide concentration and the sulfur trioxide concentration sampling value, and establishing a sulfur trioxide monitoring technical route; determining the sulfur trioxide emission reduction plan based on the sulfur trioxide monitoring technical route and the operating parameters of the flue gas treatment facility; and generating the air preheater anti-blocking measures by combining the air preheater operating parameters and the sulfur trioxide emission reduction plan.
[0062] In addition, when the logical instructions in the above-mentioned memory 430 are implemented in the form of software functional units and sold or used as an independent product, they can be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or a part of this technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in various embodiments of the present invention. The foregoing storage medium includes: USB flash drives, mobile hard disks, read-only memories (ROM, Read-Only Memory), random access memories (RAM, Random Access Memory), magnetic disks, or optical discs, and other various media that can store program codes.
[0063] On the other hand, the present invention also provides a computer program product, which includes a computer program that can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute the air preheater anti-clogging method based on sulfur trioxide monitoring provided by the above-mentioned various methods. The method includes: estimating the original value of sulfur trioxide concentration based on coal quality analysis, equipment description, and on-site tests; using a combination of a sulfur trioxide sampling device and instrumental analysis, and respectively testing the sulfur trioxide concentration sampling values at the inlet and outlet of the dust collector, the inlet and outlet of the desulfurization unit, and the inlet of the chimney by the representative point sampling method; determining the generation and transformation law and emission characteristics of sulfur trioxide based on the original value of sulfur trioxide concentration and the sulfur trioxide concentration sampling values, and establishing a sulfur trioxide monitoring technical route; determining a sulfur trioxide emission reduction plan based on the sulfur trioxide monitoring technical route and the operating parameters of the flue gas treatment facility; and generating air preheater anti-clogging measures by combining the operating parameters of the air preheater and the sulfur trioxide emission reduction plan.
[0064] In another aspect, the present invention also provides a non-transitory computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, it implements the air preheater anti-clogging method based on sulfur trioxide monitoring provided by the above-mentioned various methods. The method includes: estimating the original value of sulfur trioxide concentration based on coal quality analysis, equipment description, and on-site tests; using a combination of a sulfur trioxide sampling device and instrumental analysis, and respectively testing the sulfur trioxide concentration sampling values at the inlet and outlet of the dust collector, the inlet and outlet of the desulfurization unit, and the inlet of the chimney by the representative point sampling method; determining the generation and transformation law and emission characteristics of sulfur trioxide based on the original value of sulfur trioxide concentration and the sulfur trioxide concentration sampling values, and establishing a sulfur trioxide monitoring technical route; determining a sulfur trioxide emission reduction plan based on the sulfur trioxide monitoring technical route and the operating parameters of the flue gas treatment facility; and generating air preheater anti-clogging measures by combining the operating parameters of the air preheater and the sulfur trioxide emission reduction plan.
[0065] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art can understand and implement it without creative efforts.
[0066] Through the description of the above embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on this understanding, the essence of the above technical solution, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to enable a computer device (which can be a personal computer, server, or network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.
[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. These modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims
1. A method for preventing blockage of an air preheater based on sulfur trioxide monitoring, characterized in that, Including: Estimate the original value of sulfur trioxide concentration based on coal quality analysis, equipment description and on-site testing; Use a combination of sulfur trioxide sampling devices and instrumental analysis, and use the representative point sampling method to test the sulfur trioxide concentration sampling values at the inlet and outlet of the dust collector, the inlet and outlet of desulfurization, and the inlet of the chimney respectively; Based on the original value of sulfur trioxide concentration and the sulfur trioxide concentration sampling value, determine the generation and transformation law and emission characteristics of sulfur trioxide, and establish a sulfur trioxide monitoring technical route; Based on the sulfur trioxide monitoring technical route and the operating parameters of the flue gas treatment facility, determine the sulfur trioxide emission reduction plan; Combine the operating parameters of the air preheater and the sulfur trioxide emission reduction plan to generate anti-blocking measures for the air preheater.
2. The method for preventing blockage of the air preheater based on sulfur trioxide monitoring according to claim 1, wherein The estimating the original value of sulfur trioxide concentration based on coal quality analysis, equipment description and on-site testing includes: Determine the coal quality parameters, equipment parameters and test parameters, and determine the sampling points based on the coal quality parameters, equipment parameters and test parameters; Estimate the original value of sulfur trioxide concentration according to the total sulfur in coal and the sulfur dioxide concentration at the sampling point.
3. The method for preventing blockage of the air preheater based on sulfur trioxide monitoring according to claim 1, characterized in that, The determining the generation and transformation law of sulfur trioxide includes: Monitor the combustion process of coal in the furnace; Determine the four sulfur trioxide generation reactions during the combustion process; Through the four sulfur trioxide generation reactions, determine the influence of furnace temperature and free radical oxygen atom concentration on the generation amount of sulfur trioxide.
4. The method for preventing blockage of an air preheater based on sulfur trioxide monitoring according to claim 3, characterized in that, It also includes: Determine the catalytic effect of fly ash in the furnace flue gas on the generation of sulfur trioxide; Based on the catalytic effect, determine the adsorption effect of the surface area of the fly-back conveying structure and the active metal oxides in the fly ash on sulfur dioxide and oxygen, and promote the conversion of sulfur trioxide.
5. The method for preventing blockage of an air preheater based on sulfur trioxide monitoring according to claim 4, wherein The determining the generation and transformation law and emission characteristics of sulfur trioxide, and establishing a sulfur trioxide monitoring technical route includes: Determine the influence of the SNCR denitration system on the generation amount of sulfur trioxide, the influence of the air preheater on the sulfur trioxide removal rate, the influence of the electrostatic bag filter on the sulfur trioxide removal rate, the influence of wet desulfurization on the sulfur trioxide removal rate, and the analysis of ammonium bisulfate in fly ash to obtain the sulfur trioxide emission characteristics; Combine the sulfur trioxide emission characteristics to determine the circulating fluidized bed unit using SNCR, electrostatic bag filter and wet desulfurization as the sulfur trioxide monitoring technical route.
6. The method for preventing blockage of an air preheater based on sulfur trioxide monitoring according to claim 1, wherein When establishing the sulfur trioxide monitoring technical route, it also includes; Determine the points for examining the sulfur trioxide removal rate of a single device when adjusting the operating parameters, and use them as the monitoring points before and after the device; Determine the point for monitoring the sulfur trioxide concentration before entering the atmosphere, and use it as the desulfurization outlet monitoring point.
7. The method for preventing blockage of an air preheater based on sulfur trioxide monitoring according to claim 1, wherein The determining the sulfur trioxide emission reduction plan includes: For the same type of units, adjust the ammonia-nitrogen molar ratio and the pH value of the wet desulfurization slurry to reduce the sulfur trioxide emissions.
8. The method for preventing air preheater blockage based on sulfur trioxide monitoring according to claim 1, wherein The generating the anti-blocking measures for the air preheater includes: Prevent the air preheater from being blocked by controlling the sulfur content of the coal to reduce the generation of sulfur trioxide in the furnace; Prevent the air preheater from being blocked by adjusting the operating parameters of SNCR to reduce the ammonia escape amount and sulfur trioxide amount entering the air preheater system; Prevent the air preheater from being blocked by optimizing the soot blowing method to reduce the average thickness of the ash deposit on the convective heating surface and reduce the catalytic oxidation effect of fly ash on sulfur dioxide.
9. The method for preventing blockage of an air preheater based on sulfur trioxide monitoring according to claim 8, characterized in that, By optimizing the soot blowing method, reducing the average thickness of ash deposition on the convective heating surface, and reducing the catalytic oxidation of sulfur dioxide by fly ash, it includes: Carry out air preheater soot blowing according to the operation regulations. When the differential pressure of the air preheater shows an upward trend, increase the number of soot blowing times; Prevent the soot blowing steam from carrying water. Before the steam soot blowing of the air preheater, sufficient drainage is required to make the steam temperature reach the requirements of the soot blower and then carry out the purging; Through tests, increase the air preheater soot blowing steam to the preset range to ensure the soot blowing effect at the cold end of the air preheater; Modify the advance and retreat procedures so that the advance and retreat pause points are not in the same area to ensure that the soot blowing range covers the entire air preheater area; Control the differential pressure. When the differential pressure at the inlet and outlet of the air preheater exceeds the design value, the cold end soot blowing is changed to continuous soot blowing until the differential pressure drops below the design value.
10. An air preheater anti-blocking system based on sulfur trioxide monitoring, characterized in that, It includes: A monitoring route establishment module for estimating the original value of sulfur trioxide concentration based on coal quality analysis, equipment description, and on-site tests; Combining the sulfur trioxide sampling device and instrumental analysis, using the representative point sampling method to respectively test the sulfur trioxide concentration sampling values at the inlet and outlet of the dust collector, the inlet and outlet of desulfurization, and the inlet of the chimney; Based on the original value of the sulfur trioxide concentration and the sulfur trioxide concentration sampling value, determine the generation and transformation law and emission characteristics of sulfur trioxide, and establish a sulfur trioxide monitoring technical route; An air preheater anti-blocking module for determining a sulfur trioxide emission reduction plan based on the sulfur trioxide monitoring technical route and the operating parameters of the flue gas treatment facility; Combining the operating parameters of the air preheater and the sulfur trioxide emission reduction plan, generate anti-blocking measures for the air preheater.