A method for preventing slagging in a tangentially fired boiler

Abstract

The application discloses a kind of adjustment methods for preventing falling coke of opposed firing boiler, comprising the following steps: checking total air volume, furnace outlet oxygen content, CO content in flue gas of furnace outlet, whether total air volume is increased according to CO content in flue gas of furnace outlet, the change of furnace outlet oxygen content and CO content in flue gas of furnace outlet is observed;Test the primary air velocity of coal mill outlet, coal fineness and coal powder distribution;Master the overall distribution of wind powder in the furnace through coal powder distribution and air volume distribution analysis;Under rated load condition, under the condition that total air volume into the furnace is basically unchanged, the air door of burn-out air layer on both sides of boiler is adjusted differently;Adjust the opening of burn-out air layer air door, observe the change of denitration inlet oxygen content and chimney inlet CO content through historical trend and make corresponding response, etc.The application provides strong technical guidance for preventing falling coke of opposed firing boiler, and is beneficial to improve the safety and reliability of boiler operation.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of coal-fired thermal power generating units, and particularly relates to a method for preventing coking of a opposed firing boiler. BACKGROUND

[0002] Due to high furnace temperature of the opposed firing boiler and large width-depth ratio of the furnace, local oxygen deficiency combustion is prone to occur, which accelerates coking of the furnace, and when the coking is serious, the boiler will be extinguished. The coking of the boiler indicates that a large amount of coking has occurred in the furnace, and as the coking becomes more and more, the furnace wall will finally be unable to bear the weight of the coking block and will fall off. How to prevent the opposed firing boiler from coking is an important issue related to the safety of power plant production. SUMMARY

[0003] To solve the technical problems in the prior art, the purpose of the present application is to provide a method for preventing coking of an opposed firing boiler.

[0004] To achieve the above purposes and achieve the above technical effects, the technical solution adopted by the present application is as follows.

[0005] A method for preventing coking of an opposed firing boiler, comprising the following steps:

[0006] 1) On-site observation of the amount of slag in the slag extractor, if the amount of slag overflows the scraper of the slag extractor and the working oil pressure of the slag extractor abnormally rises, through historical trend review, if the oil pressure exceeds a certain threshold, it indicates that the amount of coking in the furnace is large, and close attention needs to be paid and timely boiler combustion adjustment needs to be performed;

[0007] 2) Check whether the coal fed into the furnace is a coking-prone coal, and for the coking-prone coal, the total air volume fed into the furnace and the oxygen deviation on both sides need to be strictly controlled;

[0008] 3) Check the total air volume fed into the furnace, the oxygen content at the outlet of the furnace, and the CO content in the flue gas at the outlet of the furnace, determine whether to increase the total air volume fed into the furnace according to the CO content in the flue gas at the outlet of the furnace, and observe the changes of the oxygen content at the outlet of the furnace and the CO content in the flue gas at the outlet of the furnace after adjusting the total air volume fed into the furnace;

[0009] 4) If the oxygen deviation on both sides exceeds 0.5 percentage points or more, grid measurement needs to be performed on the denitration inlet oxygen content, inlet CO content, inlet NOx content, and inlet flue gas temperature to understand the actual distribution on site and compare with the dial data;

[0010] 5) Under the rated output condition of the coal mill, test the primary air speed at the outlet of the coal mill, the fineness of the coal powder, and the distribution of the coal powder;

[0011] 6) On-site measurement of the front and back wall overfire air volume and the burner layer secondary air volume, understanding of the balanced distribution of the air volume on both sides, comparison with the dial data, and calculation of the overfire air volume proportion of the secondary air volume, control within the design value;

[0012] 7) Through the analysis of the coal powder volume distribution and the air volume distribution, the overall distribution of the air and powder in the furnace is mastered, and the left and right side deviations are calculated to provide direction for subsequent adjustment;

[0013] 8) Under the rated load condition, while ensuring that the total air volume entering the furnace remains basically unchanged, the overfire air layer dampers on both sides of the boiler are adjusted differently, the changes in the denitration inlet oxygen content and the chimney inlet CO content are observed, and the denitration inlet oxygen content, inlet CO, inlet NOx, and inlet flue gas temperature are measured by grid, to understand the changes in the flue gas parameters after the differential adjustment of the layer dampers, and to indicate the direction for subsequent adjustment;

[0014] 9) Adjusting the overfire air layer damper opening, observing the changes in the denitration inlet oxygen content and the chimney inlet CO content through historical trends, and making corresponding responses;

[0015] 10) Continuously observing the boiler slagging condition under high load operation for several days, and regularly blowing ash according to the regulations, and understanding the boiler slagging amount by observing the working oil pressure trend of the slag extractor.

[0016] Further, in step 1), if the oil pressure exceeds 30-50% of the normal value or more, it indicates that the amount of coke falling in the furnace is large, which needs to be closely monitored and timely adjusted.

[0017] Further, in step 3), if the CO concentration exceeds 500 uL / L, the total air volume entering the furnace should be appropriately increased.

[0018] Further, in step 3), the furnace outlet oxygen content is based on the denitration inlet oxygen, and the CO content in the flue gas at the furnace outlet is based on the chimney inlet CO content. If the total air volume entering the furnace is increased, and the average value of the denitration inlet oxygen on both sides is above 3.0%, but the chimney inlet CO content does not decrease significantly, attention should be paid to whether the left and right side deviations of the denitration inlet oxygen are large.

[0019] Further, in step 5), the primary air speed is controlled not to be less than 26 m / s, and the deviation of each air speed is not more than 5%; the coal powder fineness is controlled not to be higher than the calculated value, and the calculation formula of the coal powder fineness is R 90 = 0.5 x n x V daf ; the left and right side deviations of the coal powder volume distribution are not more than 10%.

[0020] Further, in step 6), the left and right side deviations of the air volume distribution are not more than 10%.

[0021] Furthermore, in step 9), adjusting the opening of the burnout air layer damper, observing changes in the oxygen content at the denitrification inlet and the CO content at the chimney inlet through historical trends, and making corresponding responses include:

[0022] Each time, the opening of the burnout air layer damper is adjusted by 5%, and gradually increased. The changes in oxygen content at the denitrification inlet and CO content at the chimney inlet are observed by historical trends. When the CO content at the chimney inlet decreases significantly and drops below 500 μL / L, and the deviation of oxygen content at the denitrification inlet on both sides is within 0.5%, the opening of the burnout air layer damper is kept unchanged. The chimney inlet CO content and denitrification inlet oxygen content are observed to be basically stable for 1-2 hours. If they are basically stable, it indicates that this operating condition is a steady state condition.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] This invention discloses an adjustment method for preventing coke shedding in a counter-firing boiler, providing strong technical guidance for preventing large coke shedding in counter-firing boilers and improving the safety and reliability of boiler operation. Attached Figure Description

[0025] Figure 1 This is a historical trend chart of the offset combustion boiler in Embodiment 1 of the present invention;

[0026] Figure 2 This is a bar chart showing the CO content distribution at the denitrification inlet of a 640MW unit in Embodiment 1 of the present invention;

[0027] Figure 3 This is a bar chart showing the oxygen distribution at the denitrification inlet of a 640MW unit according to Embodiment 1 of the present invention;

[0028] Figure 4 This is a bar chart showing the flue gas temperature distribution at the denitrification inlet of a 640MW unit according to Embodiment 1 of the present invention;

[0029] Figure 5 This is a bar chart showing the NOx content distribution at the denitrification inlet of a 640MW unit in Embodiment 1 of the present invention. Detailed Implementation

[0030] The present invention will now be described in detail so that its advantages and features can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0031] The following provides a brief overview of one or more aspects to offer a basic understanding of them. This overview is not an exhaustive summary of all conceived aspects, nor is it intended to identify key or decisive elements of all aspects, nor to define the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form to prepare for the more detailed descriptions that follow.

[0032] like Figures 1-5 As shown, an adjustment method for preventing coke shedding in a counter-fired boiler includes the following steps:

[0033] 1) Observe the slag volume of the slag remover on site. If the slag volume overflows the scraper of the slag remover and the working oil pressure of the slag remover rises abnormally, check the historical trend. If the oil pressure exceeds the normal value by 30% to 50%, it indicates that the amount of coke falling in the furnace is large. Close attention should be paid and the boiler combustion should be adjusted in time.

[0034] 2) Inspect the type of coal entering the furnace, test its ash fusion point temperature, and check whether it is a type of coal prone to coking. For types of coal prone to coking, it is necessary to strictly control the total air volume entering the furnace and the deviation of oxygen content on both sides;

[0035] 3) Check the total air volume entering the furnace, the oxygen content at the furnace outlet, and the CO content in the flue gas at the furnace outlet. If the CO concentration exceeds 500 uL / L, the total air volume entering the furnace should be increased appropriately. Observe the changes in the oxygen content at the furnace outlet (generally based on the oxygen content at the denitrification inlet) and the CO content at the furnace outlet (generally based on the CO content at the chimney inlet). If, after increasing the total air volume entering the furnace, the average oxygen content at the denitrification inlet on both sides is above 3.0%, but the CO content at the chimney inlet still does not decrease significantly, it is necessary to pay attention to whether the deviation between the oxygen content at the denitrification inlet on both sides is large.

[0036] 4) If the oxygen content deviation between the left and right sides exceeds 0.5 percentage points, it is necessary to perform grid measurements on the oxygen content, CO content, NOx content, and flue gas temperature at the denitrification inlet to understand the actual distribution on site and compare it with the data on the dial.

[0037] 5) Under the rated output condition of the coal mill, test the primary air velocity at the mill outlet, controlling it to be no less than 26 m / s, and assess the uniformity of the primary air velocity distribution, with each velocity deviation not exceeding 5%. Simultaneously, perform isokinetic coal powder sampling at the mill outlet to understand the coal powder quantity distribution and fineness, controlling the coal powder fineness to be no higher than the calculated value (the coal powder fineness calculation formula is R...). 90 =0.5×n×V daf Where n represents the uniformity index of pulverized coal, and V daf This indicates that the coal powder distribution is dry and free of ash and volatile matter, and the deviation between the left and right sides does not exceed 10% (the deviation value of the coal powder taking out at the same speed by the coal powder pipelines distributed on the left and right sides, with the center line of the furnace width as the boundary).

[0038] 6) On-site measurement of the burnout air volume on the front and rear walls and the secondary air volume of the burner layer to understand the balanced distribution of air volume on both sides. The deviation of the air volume distribution on the left and right sides should not exceed 10%. At the same time, compare it with the data on the dial and calculate the proportion of burnout air volume to secondary air volume, and control it near the design value.

[0039] 7) By analyzing the distribution of pulverized coal and air volume, we can understand the overall distribution of pulverized coal and air in the furnace, and by calculating the deviation on the left and right sides, we can provide direction for subsequent adjustments;

[0040] 8) Under rated load conditions, while ensuring that the total air volume entering the furnace remains basically unchanged, the dampers of the burnout air layer on both sides of the boiler are adjusted differently. The changes in oxygen content at the denitrification inlet and CO content at the chimney inlet are observed. At the same time, grid measurements are performed on oxygen content at the denitrification inlet, CO at the inlet, NOx at the inlet, and flue gas temperature at the inlet to understand the characteristics of flue gas parameter changes after the differential adjustment of the dampers, so as to indicate the direction for subsequent adjustments.

[0041] 9) Each time, adjust the opening of the burnout air layer damper on different sides by 5% (that is, close the burnout air damper on the side with higher oxygen content by 5%, or open the burnout air damper on the side with lower oxygen content by 5%), and gradually increase it. Observe the changes in the oxygen content at the denitrification inlet and the CO content at the chimney inlet by historical trends. When the CO content at the chimney inlet decreases significantly and drops to below 500 μL / L, and the deviation of the oxygen content at the denitrification inlet on both sides is within 0.5%, keep the opening of the burnout air layer damper unchanged, and observe whether the CO content at the chimney inlet and the oxygen content at the denitrification inlet can be basically stabilized for 1-2 hours. If they are basically stable, it means that this operating condition is a steady state condition.

[0042] 10) Observe the boiler ash discharge under high load operation for 4-5 consecutive days. The boiler should be blown with soot regularly as required. The ash discharge should be understood by observing the working oil pressure trend of the ash removal machine. If the working oil pressure is basically stable at around the normal value (±10%), it indicates that the boiler ash discharge is normal. If the boiler can maintain high load operation for a long time and does not drop large amounts of coke, it indicates that this operating condition has been effectively verified.

[0043] Example 1

[0044] A 660MW unit at a certain plant, using a front and rear wall opposed-fired boiler, recently experienced coking and large ash shedding, severely impacting the unit's safe operation. Therefore, the adjustment method for preventing coking in opposed-fired boilers provided in this invention was used. Results show that the coking and ash shedding situation has been greatly alleviated, and the unit can now operate stably at 660MW load for several consecutive days.

[0045] The adjustment method for preventing coke shedding in a counter-firing boiler provided by this invention includes the following steps:

[0046] 1) Historical trend analysis shows that the boiler is experiencing severe coke shedding. Historical trend analysis is as follows: Figure 1 As shown, Figure 1 The red line represents the working oil pressure of the slag remover. The normal value is around 7-8 MPa. It then rises significantly to over 10 MPa, causing the boiler to drop large amounts of coke and the slag output to be abnormal. It is necessary to adjust the combustion in time.

[0047] 2) The coal type fed into the furnace was Shenhua coal, with an ash softening temperature of 1220℃, which is a coal type that is prone to coking; it is necessary to strictly control the total air volume fed into the furnace and the deviation of oxygen content on both sides.

[0048] 3) When the unit is 640MW, the total air volume entering the furnace is approximately 2150t / h, the average oxygen content at the denitrification inlet is 3.2%, and the CO concentration at the chimney inlet has exceeded the limit (greater than 1124uL / L). This indicates that although the total air volume entering the furnace has met the requirements, there may be uneven distribution of air and pulverized coal in the furnace, resulting in localized oxygen deficiency during combustion, causing the limit to exceed the limit. The reducing atmosphere in the furnace can easily lead to increased coking in the boiler and the occurrence of large amounts of coke shedding.

[0049] 4) The oxygen content deviation on both sides of the denitrification inlet is checked and found to be 0.9%. The flue gas parameters at the denitrification inlet need to be measured using a grid method to understand the actual distribution of flue gas parameters on site. Simultaneously, the data should be compared with the meter readings to verify the accuracy of the meter data. The test results of the denitrification inlet flue gas parameters under a 640MW load are shown in Table 1 below:

[0050] Table 1

[0051]

[0052] The comparison between the on-site measured data and the values ​​on the denitrification inlet dial gauge is shown in Table 2 below:

[0053] Table 2

[0054]

[0055] The distribution diagram of inlet flue gas parameters for denitrification at a load of 640MW is shown below. Figures 2-5 As shown;

[0056] From Table 1-2 and Figures 2-5 The distribution of flue gas parameters along the width of the furnace can be seen as follows:

[0057] Along the width of the boiler, the oxygen distribution on both sides is uneven, with the oxygen content on side B being lower than that on side A. Correspondingly, the CO concentration in the flue gas is significantly higher on side B than on side A. The NOx distribution and flue gas temperature distribution are generally acceptable.

[0058] The meter readings for oxygen, NOx, and flue gas temperature at the denitrification inlet were close to the measured values, indicating that the meter readings reflect the actual situation and can be used as a basis for adjustment. The denitrification inlet meter did not have a CO meter, and the CO meter reading at the chimney inlet showed an off-limits reading (greater than 1124 mg / m³). 3 This is consistent with the measured value (619 / 2 + 1860 / 2 = 1240 mg / m³). 3 The results are quite consistent, indicating that the CO content at the chimney inlet can reflect the actual situation and can serve as a basis for adjustment.

[0059] The oxygen concentration at the denitrification inlet on side A is 0.7% higher than that on side B, corresponding to a CO concentration 1241 mg / m³ lower on side A than on side B. 3 CO and oxygen levels show a negative correlation.

[0060] 5) Under the rated output of the coal mill, the primary air velocity at the coal mill outlet, the fineness of the pulverized coal, and the distribution of the pulverized coal quantity were tested. The actual test results are shown in Table 3-5.

[0061] Table 3 shows the primary air velocity at the coal mill outlet:

[0062] Table 3

[0063]

[0064] As shown in Table 3, the average primary air velocity at the outlet of each coal mill is between 27 and 30 m / s, and the average air velocity is greater than 26 m / s, which is reasonable. The deviation of the air velocity in the single pipe of each mill is basically within 5%. The air velocity distribution among the powder pipes at the outlet of each coal mill is relatively uniform, which meets the requirements for the deviation of the air velocity in each powder pipe during the hot operation of the unit.

[0065] Table 4 shows the analysis of pulverized coal fineness at the coal mill outlet:

[0066] Table 4

[0067]

[0068] The coal fed into the boiler is Shenhua coal, and its dry ash-free volatile matter content is 38%. Table 4 shows the coal powder uniformity coefficient as 1.4. According to the formula (R... 90 =0.5×n×V daf ), calculate the fineness R of pulverized coal. 90 The percentage was 26.6%, and the fineness R of the coal powder from each coal mill in Table 4 was... 90 The content of pulverized coal is between 19.4% and 25.1%, all less than 26.6%, indicating that the fineness of the pulverized coal is appropriately controlled and meets the combustion requirements of the boiler.

[0069] Table 5 shows the distribution of pulverized coal quantity:

[0070] Table 5

[0071]

[0072] As shown in Table 4-5, the pulverized coal content on boiler side B is 9.8% higher than that on side A, which is basically within the deviation range.

[0073] 6) On-site measurements of the burnout air volume on the front and rear walls and the secondary air volume on the burner layer were conducted to understand the balanced distribution of air volume on both sides. The results are shown in Tables 6-7.

[0074] Table 6 shows the test results of the air volume in the burnout air layer;

[0075] Table 6

[0076]

[0077] Under different load conditions, the measured total burnout air volume on side A is greater than the total burnout air volume on side B. Under the 660MW condition, the burnout air volume on side A should be appropriately reduced during subsequent adjustments, while the burnout air volume on side B should be appropriately increased. During the adjustment process, pay attention to observing that the oxygen content on both sides of the SCR inlet is basically balanced, and try to control the CO concentration at the chimney outlet to within 500uL / L.

[0078] Table 7 shows the test results of the burner layer airflow:

[0079] Table 7

[0080]

[0081] As shown in Table 7, the secondary air volume distribution in the burner layer area is basically balanced, with side B being slightly lower than side A by 2.1%. No further deviation adjustment is needed for the burner layer damper.

[0082] Taking the 660MW operating condition in Table 6 as an example, calculate the proportion of burnout air in the secondary air, as shown in Table 8, to understand whether the air distribution ratio is appropriate. The burnout air volume is taken from the bolded data in Table 6, and the secondary air volume of the burner layer is calculated based on the dial air volume and flow coefficient, as shown in Table 9.

[0083] Table 8

[0084]

[0085] Table 9

[0086]

[0087]

[0088] As shown in Table 8, the proportion of burnout air to secondary air volume is 44%, which is very close to the design value of 43%. This indicates that the ratio of burnout air volume in the furnace to secondary air volume in the burner area is appropriate and no special adjustment is required.

[0089] 7) Based on the distribution of pulverized coal and the distribution of air volume in the furnace, the pulverized coal distribution on the B side of the boiler is 9.8% higher than that on the A side; the air volume distribution on both sides of the burner area is basically balanced, but in the burnout air area, the air volume on the B side is less than that on the A side; the oxygen content at the denitrification inlet on the B side is about 0.7% lower than that on the A side; the characteristics of the pulverized coal and air distribution in the furnace are consistent with the characteristics of the oxygen content distribution at the denitrification inlet, and subsequent adjustments will mainly focus on adjusting the deviation of the burnout air volume on both sides.

[0090] 8) Under the rated load condition of the unit, gradually adjust the opening of the burnout damper in a differentiated manner, that is, gradually close the burnout damper on side A, observe the changes in oxygen content at the denitrification inlet and CO at the chimney inlet, and at the same time perform grid measurements on oxygen content at the denitrification inlet, CO at the inlet, NOx at the inlet, and flue gas temperature at the inlet to understand the characteristics of flue gas parameter changes after the differentiated adjustment of the dampers, so as to indicate the direction for subsequent adjustments.

[0091] The distribution of inlet flue gas parameters for a 660MW load denitrification system is shown in Table 10.

[0092] Table 10

[0093]

[0094] The average values ​​of the inlet flue gas parameters for a 660MW load denitrification system are shown in Table 11:

[0095] Table 11

[0096]

[0097] The opening degree of the burnout air damper for 660MW is shown in Table 12:

[0098] Table 12

[0099]

[0100] As shown in Table 10-12, by adjusting the deviation on both sides of the burnout damper, the oxygen content on both sides can be leveled. As the distribution of oxygen content changes, the CO concentration also changes synchronously with the oxygen content. That is, as the oxygen content on side A decreases relatively, its CO concentration will increase, and as the oxygen content on side B increases relatively, its corresponding CO concentration will decrease significantly. This provides direction for adjusting the burnout damper deviation.

[0101] 9) Table 10 shows that the oxygen levels on both sides of the boiler are basically balanced. However, considering that the CO concentration at the chimney inlet is around 800-1000 mg / m³, which is still too high, further adjustment of the burnout damper deviation is needed. By gradually adjusting the deviation of the burnout dampers on both sides, the CO concentration at the chimney inlet can be ultimately controlled at 400 mg / m³. 3 Within a certain range, and able to maintain stable operation. The adjusted damper opening and average values ​​of the denitrification inlet flue gas parameters are shown in Tables 13-14;

[0102] Table 13

[0103]

[0104] Table 14

[0105]

[0106] 10) Through the above-mentioned precise adjustment of the burnout air differential, at the unit's rated load, the CO at the chimney inlet decreased from the pre-adjustment peak level to 400 mg / m³. 3 Within this range, the concentration of reducing atmosphere in the furnace was reduced, alleviating the coking situation. After five consecutive days of high-load operation, the boiler slag output was normal, the working oil pressure of the slag remover was normal, and no large amount of coke fell from the boiler, verifying the effectiveness of the above adjustment method.

[0107] Any parts or structures not specifically described in this invention can be made using existing technologies or products, and will not be elaborated upon here.

[0108] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for adjusting a counter-firing boiler to prevent coke shedding, characterized in that, Includes the following steps: 1) Observe the slag volume of the slag remover on site. If the slag volume overflows the scraper of the slag remover and the working oil pressure of the slag remover rises abnormally, check the historical trend. If the oil pressure exceeds a certain threshold, it indicates that the amount of coke falling in the furnace is large. Close attention should be paid and the boiler combustion should be adjusted in time. 2) Check whether the coal type fed into the furnace is a type that is prone to coking; for types of coal that are prone to coking, it is necessary to strictly control the total air volume fed into the furnace and the deviation of oxygen content on both sides; 3) Check the total air volume entering the furnace, the oxygen content at the furnace outlet, and the CO content in the flue gas at the furnace outlet. Based on the CO content in the flue gas at the furnace outlet, determine whether to increase the total air volume entering the furnace. After adjusting the total air volume entering the furnace, observe the changes in the oxygen content at the furnace outlet and the CO content in the flue gas at the furnace outlet. 4) If the oxygen content deviation between the left and right sides exceeds 0.5 percentage points, it is necessary to perform grid measurements on the oxygen content, CO content, NOx content, and flue gas temperature at the denitrification inlet to understand the actual distribution on site and compare it with the data on the dial. 5) Under the rated output condition of the coal mill, test the primary air velocity, coal powder fineness, and coal powder quantity distribution at the coal mill outlet; 6) On-site measurement of the burnout air volume on the front and rear walls and the secondary air volume of the burner layer to understand the balanced distribution of air volume on both sides. At the same time, compare it with the data on the dial and calculate the proportion of burnout air volume to secondary air volume, and control it near the design value. 7) By analyzing the distribution of pulverized coal and air volume, we can understand the overall distribution of pulverized coal and air in the furnace, and by calculating the deviation on the left and right sides, we can provide direction for subsequent adjustments; 8) Under rated load conditions, while ensuring that the total air volume entering the furnace remains basically unchanged, the dampers of the burnout air layer on both sides of the boiler are adjusted differently. The changes in oxygen content at the denitrification inlet and CO content at the chimney inlet are observed. At the same time, grid measurements are performed on oxygen content at the denitrification inlet, CO at the inlet, NOx at the inlet, and flue gas temperature at the inlet to understand the characteristics of flue gas parameter changes after the differential adjustment of the dampers, so as to indicate the direction for subsequent adjustments. 9) Adjust the opening of the burnout air layer damper, observe the changes in oxygen content at the denitrification inlet and CO content at the chimney inlet through historical trends, and make corresponding responses; 10) Observe the boiler slag discharge under high load operation for several consecutive days. The boiler is regularly blown with soot as required. The boiler slag discharge is understood by observing the working oil pressure trend of the slag remover. In step 3), the oxygen content at the furnace outlet is based on the oxygen content at the denitrification inlet, and the CO content in the flue gas at the furnace outlet is based on the CO content at the chimney inlet. If the average value of the oxygen content at the denitrification inlet on both sides is above 3.0% after the total air volume entering the furnace is increased, and the CO content at the chimney inlet still does not decrease significantly, it is necessary to pay attention to whether the deviation of the oxygen content at the denitrification inlet on both sides is large.

2. The adjustment method for preventing coke shedding in a counter-firing boiler according to claim 1, characterized in that, In step 1), if the oil pressure exceeds 30-50% of the normal value, it indicates that the amount of coke loss in the furnace is large, and close attention and timely adjustment of boiler combustion are required.

3. The adjustment method for preventing coke shedding in a counter-firing boiler according to claim 1, characterized in that, In step 3), if the CO concentration exceeds 500 μL / L, the total air volume entering the furnace should be increased appropriately.

4. The adjustment method for preventing coke shedding in a counter-firing boiler according to claim 1, characterized in that, In step 5), the primary air velocity is controlled to be no less than 26 m / s, and the deviation of each air velocity is no more than 5%; the fineness of the pulverized coal is controlled to be no higher than the calculated value, and the formula for calculating the fineness of the pulverized coal is as follows: The left-right deviation of the coal powder distribution should not exceed 10%.

5. The adjustment method for preventing coke shedding in a counter-firing boiler according to claim 1, characterized in that, In step 6), the deviation of the air volume distribution on the left and right sides shall not exceed 10%.

6. The adjustment method for preventing coke shedding in a counter-firing boiler according to claim 1, characterized in that, Step 9), which involves adjusting the opening of the burnout air layer damper, observing changes in the oxygen content at the denitrification inlet and the CO content at the chimney inlet through historical trends, and making corresponding responses, includes the following steps: Each time, the opening of the burnout air layer damper is adjusted by 5%, and gradually increased. The changes in oxygen content at the denitrification inlet and CO content at the chimney inlet are observed by historical trends. When the CO content at the chimney inlet decreases significantly and drops below 500 μL / L, and the deviation of oxygen content at the denitrification inlet on both sides is within 0.5%, the opening of the burnout air layer damper is kept unchanged. The chimney inlet CO content and denitrification inlet oxygen content are observed to be basically stable for 1-2 hours. If they are basically stable, it indicates that this operating condition is a steady state condition.

Images