Regulation and control method for dynamic blending combustion of coal gas of coal-fired boiler

Abstract

The invention belongs to the technical field of combustion control of coal-fired boilers of self-contained power plants of iron and steel enterprises, and relates to a regulation and control method for dynamic blending combustion of coal-fired boilers, which comprises the following steps: (1) determining the maximum flow of blast furnace gas blending combustion quantity Q according to a load-blending combustion quantity four-dimensional dynamic model; (2) performing graded dynamic control according to the blending combustion amount of blast furnace gas; (3) regulating and controlling the oxygen content of the boiler; (4) determining a secondary air distribution mode; (5) adjusting the coal feeding amount; (6) adjusting heat exchange equipment behind the flue; (7) creating a safety interlocking mechanism, and performing close monitoring; the step (2) to the step (7) are synchronously carried out without any order. According to the method, a load-blending combustion amount four-dimensional dynamic model is constructed, the technical means of graded dynamic control, staged oxygen amount control, intelligent air distribution adjustment, a safety interlocking mechanism and the like are adopted, abundant coal gas is subjected to blending combustion to the maximum extent, energy waste is reduced, boiler combustion is stabilized, it is ensured that environmental protection reaches the standard, and coal used for power generation and the comprehensive cost are reduced; the system is suitable for comprehensive energy utilization of self-contained power plants of iron and steel enterprises.

Description

Technical Field

[0001] The present invention belongs to the technical field of combustion control of coal-fired boilers in self-provided power plants of iron and steel enterprises, and particularly relates to a regulation method for dynamically co-firing gas in a coal-fired boiler. Background Art

[0002] With the continuous improvement of the production capacity of iron and steel enterprises, the output of blast furnace gas is also increasing. To improve energy utilization efficiency, reduce gas emission, lower production costs, and achieve the goal of low-carbon environmental protection, technologies for co-firing gas in coal-fired boilers have emerged in the market, which not only save energy but also reduce environmental pollution, having good economic and social benefits. However, after co-firing gas, a series of impacts have occurred, such as high flue gas temperature, air preheater jamming, and excessive particulate matter in environmental protection indicators. The stability of the original boiler is disrupted, and the original control method cannot well adapt to the new working conditions. Moreover, the gas volume in iron and steel enterprises fluctuates greatly, with problems such as instantaneous gas excess and instantaneous gas shortage. Therefore, how to dynamically adjust to maximize the co-firing of gas while ensuring the stable operation of the boiler and meeting environmental protection indicators and reducing emissions has become the main problem to be solved at present.

[0003] Chinese Patent Application for Invention CN117128533A discloses a method for determining the blending ratio of blast furnace gas in a coal-fired power plant boiler. By performing iterative calculations of CO2 balance, the mass ratio z value of the actual blast furnace gas entering the furnace to the actually burned coal is obtained, and then combined with the mass ratio l of unburned combustibles to supplied fuel u , the final blending ratio of blast furnace gas is determined. The data required for this method cannot be accurately measured, and the algorithm is rather cumbersome, making it impossible to perform dynamic regulation, with great implementation difficulty and unable to guide actual production. Summary of the Invention

[0004] To solve the problems in the prior art such as the inability to maximize the co-firing of blast furnace gas, poor combustion stability, environmental protection exceeding standards, and low energy utilization efficiency, the purpose of the present invention is to provide a regulation method for dynamically co-firing gas in a coal-fired boiler.

[0005] The technical solution adopted by the present invention to solve its technical problems is: a regulation method for dynamically co-firing gas in a coal-fired boiler, comprising the following steps:

[0006] (1) Determine the blast furnace gas co-firing amount Q according to the load - co-firing amount four-dimensional dynamic model 最大流量 ;

[0007] (2) Perform hierarchical dynamic control according to the blast furnace gas co-firing amount;

[0008] (3) Regulate the oxygen content in the boiler;

[0009] (4) Determine the secondary air distribution method;

[0010] (5) Adjust the coal feeding volume;

[0011] (6) Adjust the heat exchange equipment behind the flue;

[0012] (7) Create a safety interlock mechanism and closely monitor;

[0013] Among them, steps (2) - (7) are carried out synchronously without priority.

[0014] Specifically, in the said step (1), the blending volume Q of blast furnace gas 最大流量 is determined as follows:

[0015] A. Determine the initial load L 初始 , unit: MW, according to the blending volume benchmark model of blast furnace gas and the current actual operation conditions;

[0016] B. Jointly determine the maximum blending volume benchmark value Q 焦炉 , unit: 10,000 Nm 3 / h, of blast furnace gas with the current blending volume Q of coke oven gas 基准 , unit: 10,000 Nm 3 / h;

[0017] C. Determine the time correction coefficient α according to the allowable blending time of surplus blast furnace gas. Finally, determine the target load L (t) , unit: MW, according to the actual production needs; 目标 , unit: MW;

[0018] D. Form a four-dimensional dynamic model of load - blending volume: Q 最大流量 = Q 基准 ×α (t) ×Max{0.95, 1 - 0.001×(L 目标 - L 初始 )},

[0019] where: α (t) is the time correction coefficient. When the surplus time of blast furnace gas ≤ 8 h, α (t) takes 1.0. When the surplus time of blast furnace gas > 8 h, α (t) takes 0.95.

[0020] Specifically, the specific method of hierarchical dynamic control in the said step (2) is as follows: The blending of blast furnace gas is controlled in three stages: the initial commissioning stage, the stable stage, and the high-load stage. The blending rates in the three stages are in the order from slow to fast. Blast furnace gas is fed into the blast furnace gas burner, and the change rate ΔP of the outlet pressure of the steam separator is monitored in real time. If ΔP > 0.2 MPa / min, the feeding rate is reduced to 80% of the original value; if ΔP < 0.05 MPa / min, the feeding rate is increased to 120% of the original value.

[0021] Specifically, the material of the blast furnace gas burner is 310S stainless steel, and the inner wall is coated with an aluminized layer of 1.0 ± 0.2 mm.

[0022] Specifically, in step (3), the control of the boiler oxygen content is carried out according to different target loads L 目标 and the calculation method is as follows:

[0023] O2% = 3.0% + K L × (350 - L 目标 ) / 100,

[0024] where K L is the oxygen content correction coefficient, 3.0% is the basic oxygen content. When L 目标 > 210 MW, K L takes 0; when 160 MW ≤ L 目标 < 210 MW, K L takes 0.5; when L 目标 < 160 MW, K L takes 1.

[0025] Specifically, in step (4), the secondary air distribution is carried out according to the conventional distribution method: when the NO X concentration at the boiler outlet ≥ 350 mg / m 3 , the top overfire air is increased to more than 80%; when the NO X concentration at the boiler outlet ≤ 300 mg / m 3 , the top overfire air maintains an opening of 65%.

[0026] Specifically, in step (5), the specific control method of the coal feeding amount is as follows: under normal operation, when the coal feeding amount of each coal mill ≥ 18 t / h and the blast furnace gas co-firing amount > 150,000 Nm 3 / h, the output of the lower coal mill must ≥ 20 t / h to ensure stable combustion, reduce the coal feeding amount of the upper coal mill, and the coal feeding amount of the upper coal mill shall not be lower than the limit value of 15 t / h; if the duration of a large amount of blast furnace gas co-firing ≥ 8 h, the uppermost coal mill needs to be shut down, the separator speed of each coal mill is controlled at 50%, and the separator outlet temperature of the coal mill is controlled at 73 ± 2 °C.

[0027] Specifically, in step (6), the adjustment of the heat exchange equipment behind the flue includes the adjustment of the air preheater and the low-low temperature economizer; among them, when the flue gas temperature at the air preheater inlet ≥ 345 °C, the steam soot blowing system is preferentially started, and then the acoustic soot blowing system is started, and the opening of the medium-temperature economizer baffle is adjusted to control the differential pressure of the air preheater below 3 kPa; adjust the inlet water temperature of the low-low temperature economizer

[0028] ≮ 70 °C and the outlet water temperature ≯ 100 °C.

[0029] Specifically, the safety interlock mechanism in step (7) is to automatically trigger the rapid reduction of the blending amount when any of the following situations occurs:

[0030] A. The furnace negative pressure fluctuation is greater than ±500Pa and exceeds 15 seconds;

[0031] B. Main steam temperature deviation>15℃;

[0032] C. Air preheater differential pressure > 3kPa.

[0033] The present invention has the following beneficial effects:

[0034] (1) Increase boiler operation stability. The load-blending amount four-dimensional dynamic model formulated by the present invention quantifies the maximum blending value of each operating condition, avoids blind blending for maximization, and eliminates non-stop accidents such as excessive particulate matter and air preheater jamming caused by blind blending. The dynamic adjustment operation method adopted by the present invention can ensure that the boiler combustion is stable when blast furnace gas is blended to the maximum extent, all parameters are within the specified range, the main steam pressure fluctuates little, and the blending efficiency is high, which is conducive to the safe and stable operation of the boiler.

[0035] (2) Improve resource utilization. The by-product gas of the steel plant is reused. After blending with blast furnace gas to the maximum extent, the gas that was originally discharged or inefficiently used is converted into thermal energy, which improves the comprehensive utilization rate of energy. In 2024, the gas emission rate hit a historical record, which is in line with the concept of circular economy.

[0036] (3) Reduce costs. Blast furnace gas is a byproduct of the ironmaking process and has a low cost. Using it to replace part of the coal can reduce the amount of coal purchased and reduce fuel costs. By mixing blast furnace gas with coal, the coal cost is saved by tens of millions of yuan each year.

[0037] (4) Significant environmental benefits. Compared with coal, blast furnace gas has a low sulfur content and produces less pollutants such as sulfur dioxide after combustion, which can reduce the risk of environmental problems such as acid rain. At the same time, carbon dioxide emissions are also relatively low, which helps companies achieve carbon reduction goals and mitigate the greenhouse effect. The present invention increases the amount of blast furnace gas blending, and the gas blending rate will reach more than 10% in 2024, achieving the goal of carbon reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is the reference model of blast furnace gas blending amount in the present invention.

[0039] Figure 2 It is the layout diagram of the blast furnace gas burner of the present invention.

[0040] Figure 3 It is a statistical diagram of blast furnace gas emission rates over the years in Example 1 of the present invention. DETAILED DESCRIPTION

[0041] The following are specific embodiments of the present invention, which further describe the technical solutions of the present invention. However, the protection scope of the present invention is not limited to these embodiments. Any changes or equivalent substitutions that do not deviate from the concept of the present invention are included in the protection scope of the present invention.

[0042] A regulation method for dynamically co-firing coal gas in a coal-fired boiler includes the following steps: Among them, steps (2) - (7) are carried out synchronously without priority.

[0043] (1) Determine the blast furnace gas co-firing amount Q according to the load - co-firing amount four-dimensional dynamic model 最大流量 。

[0044] The blast furnace gas co-firing amount Q 最大流量 (unit: 10,000 Nm 3 / h) is determined as follows:

[0045] A. Determine the initial load L Figure 1 (unit: MW) according to the blast furnace gas co-firing amount reference model (as 初始 shown) and the current actual operation conditions;

[0046] B. Determine the maximum blast furnace gas co-firing amount reference value Q 焦炉 (unit: 10,000 Nm 3 / h) together with the current coke oven gas co-firing amount Q 基准 (unit: 10,000 Nm 3 / h);

[0047] C. Determine the time correction coefficient α according to the allowable co-firing time of the surplus blast furnace gas. Finally, determine the target load L (t) (unit: MW) according to the actual production needs; 目标 (unit: MW);

[0048] D. Form a load - co-firing amount four-dimensional dynamic model: Q 最大流量 = Q 基准 × α (t) × Max{0.95, 1 - 0.001 × (L 目标 - L 初始 )},

[0049] In the formula: α (t) is the time correction coefficient. When the surplus time of blast furnace gas ≤ 8h, α (t) takes 1.0. When the surplus time of blast furnace gas > 8h, α (t) takes 0.95.

[0050] (2) Control according to the blast furnace gas co-firing amount grading dynamics.

[0051] The specific method of hierarchical dynamic control is as follows: The co-firing of blast furnace gas is controlled in three stages: the initial commissioning stage, the stable stage, and the high-load stage. As shown in Table 1, the co-firing rate of blast furnace gas in the three stages is in the order from slow to fast. Blast furnace gas is fed into the blast furnace gas burner, and the change rate of the outlet pressure of the steam separator, ΔP (unit: MPa / min), is monitored in real time. If ΔP > 0.2 MPa / min, the feeding rate is reduced to 80% of the original value; if ΔP < 0.05 MPa / min, the feeding rate can be appropriately increased to 120% of the original value.

[0052] Table 1 Co-firing rate of blast furnace gas

[0053] Serial number Stage Input quantity of blast furnace gas Acceleration and deceleration rate Priority burner for input 1 Initial operation stage <![CDATA[≤50,000 Nm 3 / h]]> <![CDATA[≤20,000 Nm 3 / 5 min]]> G layer 2 Stable stage <![CDATA[5 - 15 million Nm 3 / h]]> <![CDATA[≤20,000 Nm 3 / 3 min]]> F layer + G layer 3 High load stage <![CDATA[>150,000 Nm 3 / h]]> <![CDATA[≤20,000 Nm 3 / 2 min]]> /

[0054] The material of the blast furnace gas burner is 310S stainless steel, and the inner wall is coated with an aluminized layer of 1.0 ± 0.2 mm to improve the corrosion resistance and high-temperature resistance of the burner. As Figure 2 shown, the layout method is that the F layer is at the bottom, and the F layer is 2.8 m below the G layer.

[0055] (3) Regulate the boiler oxygen content.

[0056] The control of the boiler oxygen content is carried out according to different target loads L 目标 and the calculation method is as follows:

[0057] O2% = 3.0% + K L × (350 - L 目标 ) / 100,

[0058] where K L is the oxygen content correction coefficient, 3.0% is the basic oxygen content. When L 目标 > 210 MW, K L is taken as 0; when 160 MW ≤ L 目标 < 210 MW, K L is taken as 0.5; when L 目标 < 160 MW, K L is taken as 1.

[0059] (4) Determine the secondary air distribution method.

[0060] The secondary air distribution is in the conventional distribution method: when the NO X concentration at the boiler outlet ≥ 350 mg / m 3 , the top overfire air is increased to more than 80%; when the NO X concentration at the boiler outlet ≤ 300 mg / m 3 , the top overfire air maintains an opening of 65%.

[0061] (5) Adjust the coal feeding amount.

[0062] The specific control method of the coal feeding amount is as follows: Under normal operation, the coal feeding amount of each coal mill ≥ 18 t / h, and when the blending amount of blast furnace gas is relatively large (> 150,000 Nm 3 / h), the output of the lower-layer coal mill must ≥ 20 t / h to ensure stable combustion and reduce the coal feeding amount of the upper-layer coal mill (not less than the limit value of 15 t / h). If a large amount of blast furnace gas is blended for a long time (≥ 8 h), the topmost coal mill needs to be shut down. The rotation speed of the separator of each coal mill is controlled at 50%, and the outlet temperature of the coal mill separator is controlled at 73 ± 2 °C.

[0063] (6) Adjust the heat exchange equipment behind the flue.

[0064] Adjusting the heat exchange equipment behind the flue includes the adjustment of the air preheater and the low-low temperature economizer. Among them, when the flue gas temperature at the inlet of the air preheater ≥ 345 °C, the steam soot blowing system is preferentially started, and then the acoustic soot blowing system is started. Adjust the opening of the baffle of the medium-temperature economizer to control the differential pressure of the air preheater below 3 kPa; adjust the inlet water temperature of the low-low temperature economizer ≮ 70 °C and the outlet water temperature ≯ 100 °C.

[0065] (7) Create a safety interlock mechanism and closely monitor.

[0066] The safety interlock mechanism is automatically triggered to rapidly reduce the blending amount when any of the following situations occurs:

[0067] A. The furnace negative pressure fluctuates by more than ± 500 Pa and exceeds 15 seconds;

[0068] B. The main steam temperature deviation > 15 °C;

[0069] C. The differential pressure of the air preheater > 3 kPa.

[0070] Example 1

[0071] In October 2024, the 2# unit of the self-provided power plant of Shandong Iron and Steel Group was under maintenance, and the 1# unit was operating alone. At this time, the single-unit load was 330 MW. Due to the rolling line waiting for materials for 8 hours, the consumption of blast furnace gas decreased, and the surplus gas reached 220,000 Nm 3 / h. The small gas-fired power generation unit can consume 45,000 Nm 3 / h of blast furnace gas, and the remaining 175,000 Nm 3 / h of blast furnace gas is supplied for blending in the 1# coal-fired unit of the self-provided power plant of Shandong Iron and Steel Group. The specific method is as follows:

[0072] (1) Determine the blending amount Q of blast furnace gas according to the load-blending amount four-dimensional dynamic model 最大流量 .

[0073] According to the blast furnace gas blending amount reference model (see Figure 1 ) and the current actual operation situation, determine the initial load of 330 MW; the current blending amount of coke oven gas is 5,000 Nm 3 / h, jointly determine the benchmark value Q of the maximum blending amount of blast furnace gas 基准 is 180,000 Nm 3 / h;

[0074] The allowable blending time of the surplus blast furnace gas is 8 h, and the surplus time ≤ 8 h. Therefore, the time correction coefficient α (t) is 1. Determine the target load L 目标 as 340 MW according to the actual production needs. Calculate according to the load-blending amount four-dimensional dynamic model:

[0075] Q 最大流量 = Q 基准 ×α (t) ×Max{0.95, 1 - 0.001×(L 目标 - L 初始 )} = 180,000 Nm 3 / h×1×0.99 = 178,200 Nm 3 / h.

[0076] After calculation, Q 最大流量 is 178,200 Nm 3 / h at this load, and the surplus gas is 175,000 Nm 3 / h at this moment. Therefore, the surplus gas can be fully blended and burned.

[0077] (2) According to the gas blending amount, conduct hierarchical dynamic control.

[0078] Open the blast furnace gas burner on the G floor and blend in the blast furnace gas. In the initial commissioning stage, add the blast furnace gas at a rate of ≤ 20,000 Nm 3 / 5 min, and at the same time monitor the change rate ΔP of the outlet pressure of the steam-water separator; when the blending amount of the blast furnace gas reaches 50,000 Nm 3 / h, increase the blending rate to ≤ 20,000 Nm 3 / 3 min, and at the same time open the blast furnace gas burner on the F floor; when the blending amount of the blast furnace gas reaches more than 150,000 Nm 3 / h, carry out at a rate of ≤ 20,000 Nm 3 / 2 min until the input amount of the blast furnace gas into the furnace reaches 175,000 Nm 3 / h. During the whole period, the change rate ΔP of the outlet pressure of the steam-water separator is between 0.1 MPa / min - 0.15 MPa / min, and the adjustment rate is carried out according to the original rate.

[0079] (3) Regulate the boiler oxygen content.

[0080] The control of the boiler oxygen content is carried out according to different target loads L 目标 , and L 目标 is 340 MW. The calculation method is as follows:

[0081] O2% = 3.0% + K L ×(350 - L 目标 ) / 100 = 3.0%

[0082] Since L 目标 > 210 MW, K L is taken as 0; thus, the boiler oxygen content is controlled at 3.0%.

[0083] (4) Determine the secondary air distribution mode.

[0084] The overall secondary air distribution is carried out according to the conventional distribution mode. At this time, the NO concentration at the boiler outlet is 360 mg / m X , and the top overfire air is increased to 80%. 3

[0085] (5) Adjust the coal feeding amount.

[0086] Before the injection of blast furnace gas, the total coal feeding amount is about 140 t / h, and there are 4 coal mills in operation. The coal feeding amount of each coal mill is ≥ 18 t / h. When the blast furnace gas injection amount reaches 175,000 Nm 3 / h, the lower coal mill operates at full load, the topmost coal mill reduces its output to 18 t / h, the separator speed of each coal mill is controlled at 50%, and the temperature at the outlet of the coal mill separator is controlled at 73 ± 2 °C.

[0087] (6) Adjust the heat exchange equipment behind the flue.

[0088] Adjust the air preheater and low-low temperature economizer. Among them, when the flue gas temperature at the inlet of the air preheater is 350 °C, the cold-end steam soot blowing is started once every 9 hours, the opening degree of the medium-temperature economizer baffle is adjusted to 80%, and the differential pressure of the air preheater is 1.8 kPa, meeting the requirements; the inlet water temperature of the low-low temperature economizer is adjusted to 72 °C, and the outlet water temperature is 97 °C.

[0089] (7) Create a safety interlock mechanism and closely monitor.

[0090] Closely monitor the changes in the parameters on the main control screen. The furnace negative pressure fluctuation is less than ±500 Pa, the main steam temperature deviation < 15 °C, and the differential pressure of the air preheater < 3 kPa, all within the specified range, and the safety interlock is not triggered.

[0091] Through the above adjustments, the blast furnace gas emission rate reached 0.08% in 2024, and there has been 0 emission since 2025 (as Figure 3 shown); the gas injection amount reached 11% in 2024, achieving the goal of carbon emission reduction; and tens of millions of yuan in electricity coal costs were saved in 2024.

[0092] Comparative example

[0093] ​In May 2024, the 1# unit of Shandong Iron and Steel's self-provided power plant was under maintenance, and the 2# unit was operating alone. At this time, the single-unit load was 330 MW, and the surplus gas reached 200,000 Nm 3 / h. The small gas-fired power generation units could not co-fire blast furnace gas due to failures. To avoid gas flaring, all the 1# coal-fired units of Shandong Iron and Steel's self-provided power plant had to co-fire. The co-firing volume had exceeded the limit value of 180,000 Nm 3 / h. After operation, problems such as too high flue gas temperature, air preheater differential pressure > 3 kPa, and air preheater jamming occurred, making it unable to work normally; moreover, the hourly value of the environmental protection index particulate matter > 5 mg / m 3 .

[0094] The present invention innovatively creates a blast furnace gas co-firing model, constructs a four-dimensional dynamic model of load - co-firing volume based on the model, and adopts technical means such as hierarchical dynamic control, staged oxygen control, intelligent air distribution regulation, and safety interlock mechanism, which can co-fire surplus gas to the greatest extent, reduce energy waste, stabilize boiler combustion, ensure environmental protection compliance, reduce coal consumption for power generation and comprehensive costs, and is applicable to the efficient energy comprehensive utilization of self-provided power plants in iron and steel enterprises.

[0095] The present invention is not limited to the above embodiments. Anyone should know that structural changes made under the inspiration of the present invention, as long as they have the same or similar technical solutions as the present invention, fall within the protection scope of the present invention.

[0096] The technologies, shapes, and structures not described in detail in the present invention are all well-known technologies.

Claims

1. A method for controlling the dynamic blending of coal gas in a coal-fired boiler, characterized in that: The following steps are involved: (1) Determine the blast furnace gas blending amount Q based on the load-blending amount four-dimensional dynamic model 最大流量 ; (2) Dynamic control based on the amount of blast furnace gas blended; (3) Regulating the oxygen content of the boiler; (4) Determine the secondary air distribution method; (5) Adjust the coal supply; (6) Adjust the heat exchange equipment after the flue; (7) Create a safety interlock mechanism and monitor closely; Among them, steps (2) to (7) are performed simultaneously without any particular order.

2. The method for controlling the dynamic blending of coal gas in a coal-fired boiler according to claim 1, characterized in that: In the step (1), the amount of blast furnace gas blended is Q 最大流量 The determination method is as follows: A. Determine the initial load L according to the blast furnace gas blending amount benchmark model and the current actual operation situation. 初始 , unit: MW; B. With the current coke oven gas blending amount Q 焦炉 , unit: ten thousand Nm 3 / h, jointly determine the maximum blending amount of blast furnace gas Q 基准 , unit: ten thousand Nm 3 / h; C. Determine the time correction coefficient α based on the allowable blending time of rich blast furnace gas (t) Finally, determine the target load L according to actual production needs. 目标 , unit: MW; D. Formation of load-combustion amount four-dimensional dynamic model: Q 最大流量 =Q 基准 ×α (t) ×Max{0.95,1-0.001×(L 目标 -L 初始 )}, Where: α (t) is the time correction coefficient. When the blast furnace gas abundance time is ≤8h, α (t) Take 1.0, when the blast furnace gas abundance time> 8h α (t) Take 0.

95.

3. The method for controlling the dynamic blending of coal gas in a coal-fired boiler according to claim 1, characterized in that: The specific method of hierarchical dynamic control in step (2) is as follows: the blast furnace gas blending is controlled according to the three stages of initial operation stage, stable stage and high load stage, and the blending rates in the three stages are carried out in order from slow to fast, blast furnace gas is fed into the blast furnace gas burner, and the pressure change rate ΔP of the steam-water separator outlet is monitored in real time. If ΔP>0.2MPa / min, the operation rate is reduced to 80% of the original value; If ΔP<0.05MPa / min, the operation rate is increased to 120% of the original value.

4. The method for controlling the dynamic blending of coal gas in a coal-fired boiler according to claim 3, characterized in that: The blast furnace gas burner is made of 310S stainless steel, and the inner wall is coated with a 1.0±0.2 mm aluminized layer.

5. The method for controlling the dynamic blending of coal gas in a coal-fired boiler according to claim 1, characterized in that: The control of the boiler oxygen content in step (3) is based on different target loads L 目标 To control, the calculation method is: O2%=3.0%+K L ×(350-L 目标 ) / 100, Where K L is the oxygen correction factor, 3.0% is the basic oxygen content, when L 目标 >210MW, K L Take 0; when 160MW≤L 目标 <210MW, K L Take 0.5; when L 目标 <160MW, K L Take 1.

6. The method for controlling the dynamic blending of coal gas in a coal-fired boiler according to claim 1, characterized in that: In step (4), the secondary air distribution is carried out in a conventional manner: when the boiler outlet NO X Concentration ≥ 350 mg / m 3 When the top combustion air is increased to more than 80%; the boiler outlet NO X Concentration ≤300mg / m 3 The top overburning air is kept open at 65%.

7. The method for controlling the dynamic blending of coal gas in a coal-fired boiler according to claim 1, characterized in that: The specific control method of the coal feeding amount in step (5) is: under normal operation, the coal feeding amount of each coal mill is ≥18t / h, and the blast furnace gas blending amount is >150,000Nm 3 / h, the output of the lower coal mill must be ≥20t / h to ensure stable combustion and reduce the coal feed to the upper coal mill. The coal feed to the upper coal mill must not be lower than the limit value of 15t / h. If a large amount of blast furnace gas is blended and burned for ≥8h, the uppermost coal mill must be shut down, the speed of each coal mill separator must be controlled at 50%, and the outlet temperature of the coal mill separator must be controlled at 73±2℃.

8. The method for controlling the dynamic blending of coal gas in a coal-fired boiler according to claim 1, characterized in that: In the step (6), the post-flue heat exchange equipment is adjusted, including the air preheater and the low-temperature economizer. When the flue gas temperature at the air preheater inlet is ≥345°C, the steam soot blowing system is started first, and the sonic soot blowing system is started secondly. The damper opening of the medium-temperature economizer is adjusted to control the air preheater differential pressure to below 3 kPa. The low-temperature economizer inlet water temperature is adjusted to ≮70°C and the outlet water temperature is adjusted to ≯100°C.

9. The method for controlling the dynamic blending of coal gas in a coal-fired boiler according to claim 1, characterized in that: The safety interlock mechanism in step (7) is to automatically trigger the rapid reduction of the blending amount when any of the following situations occurs: A. The furnace negative pressure fluctuation is greater than ±500Pa and exceeds 15 seconds; B. Main steam temperature deviation>15℃; C. Air preheater differential pressure > 3kPa.

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