Device and method for NOX reduction using reburning of active gas-conditioned pulverized coal

Abstract

Disclosed in the present invention is a method for NOx reduction using reburning of active gas-conditioned pulverized coal, comprising the following steps: medium-to-high volatile coal fuel is carried by primary air and injected into a main burner on one side of a pulverized coal combustion chamber, and hot air sequentially passes through the main burner to enter a main combustion zone; the medium-to-high volatile coal fuel is carried by recirculated flue gas to pass through a reburning pulverized coal pipe and a reburning pulverized coal nozzle and enter a reburning burner above the main burner, a conditioning gas sequentially passes through a conditioning gas pipe, a conditioning gas nozzle and the reburning pulverized coal nozzle and enters the reburning burner, and the medium-to-high volatile coal fuel and the conditioning gas are mixed inside the reburning burner and then enter a reburning zone; and the hot air sequentially passes through a separated overfire air pipe, a separated overfire air nozzle and a burnout burner above the reburning burner and enters a burnout zone, so as to achieve burnout of a combustion product. The present invention uses the described steps where a conditioning gas is used for conditioning solid fuel, thus ensuring the effect of reducing NOx emissions while ameliorating the problem of poor burnout performance caused by using a high proportion of reburning pulverized coal.

Description

A device and method for reducing NOx by reburning pulverized coal using active gas conditioning Technical Field

[0001] The present invention relates to the field of boiler combustion technology, in particular to a method for reducing NO by using active gas to condition pulverized coal and then burning it. x device and method. Background Art

[0002] Thermal power is the main source of electricity in my country. The country has continuously strengthened its efforts to control air pollution. All coal-fired power plants in the country that are eligible for transformation have achieved ultra-low emissions, with nitrogen oxide emission concentrations no higher than 50 mg / m 3 (Base oxygen content 6%).

[0003] Currently, controlling boiler NO x Emission measures include post-combustion flue gas purification and low NO x Combustion and other technologies. Post-combustion flue gas purification technology (SCR technology) can significantly reduce NO x Emissions, but the initial investment is huge and the operating costs are expensive. x The combustion technology is low NO x The furnace combustion technology with burners, fuel staging, air staging and other measures is widely used because of its small initial investment and zero or very low operating costs.

[0004] Using low NO x Combustion technology NO x Emission levels are 130~400 mg / m 3 , achieving the goal of controlling NO at the source x The traditional pulverized coal reburning technology uses air to transport the reburned coal powder to the reburning zone. The reburned coal powder burns to produce nitrogen-based active substances, which react with NO generated by the combustion of coal powder in the main combustion zone. x Reduction reaction is carried out to reduce NO x Purpose of emission.

[0005] However, traditional coal-fired power plants use air to transport pulverized coal for reburning. The oxygen contained in the transported air consumes a large amount of pulverized coal in the early stage of reburning. In order to ensure that the air can participate in the reduction of NO after it is basically exhausted, x To increase the amount of pulverized coal, the proportion of reburned coal needs to be increased to around 30%. Due to the short burnout time of reburned coal, a high proportion of reburned coal will lead to a series of problems such as poor burnout and limited operation and adjustment methods. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for reducing NO by reburning pulverized coal tempered with active gas. x Device and method to ensure the reduction of NO xIt can not only reduce the emission effect, but also alleviate the problems such as poor burnout caused by using a high proportion of reburned coal powder.

[0007] To achieve the above-mentioned purpose, the present invention provides a method for reducing NO by reburning pulverized coal tempered with active gas. x The method comprises the following steps,

[0008] S1. The 75-90% medium-high volatile coal fuel is carried by the primary air through the primary air duct, primary air nozzle and the main burner on one side of the pulverized coal combustion chamber. The hot air enters the main combustion zone through the secondary air duct, secondary air nozzle and main burner in turn;

[0009] The primary air rate accounts for 10-50%, and the secondary air rate accounts for 50-90%.

[0010] S2, 10-25% of medium and high volatile coal fuel is carried by the recycled flue gas through the reburning coal pulverized pipe and the recycled flue gas nozzle into the reburning burner above the main burner. At the same time, 0-6% of the tempered gas enters the reburning burner through the tempered gas pipe, the tempered gas nozzle and the recycled flue gas nozzle in sequence. The medium and high volatile coal fuel and the tempered gas are mixed in the reburning burner and then enter the reburning zone. Once the medium and high volatile coal fuel is injected into the reburning zone, it is quickly activated by the tempered gas into gaseous CH i , CO, OH and H and highly reactive coke;

[0011] S3. The hot air passes through the separation burnout air duct, the separation burnout air nozzle and the burnout burner above the reburning burner in sequence and enters the burnout zone to burn out the combustion products.

[0012] Preferably, the excess air coefficient in the main combustion zone is controlled at 0.65~1.05, and the residence time of the flue gas is controlled at about 0.2~1.4 s.

[0013] Preferably, the excess air coefficient in the reburning zone is 0.6-0.95, and the flue gas residence time is controlled at 0.2-1.3 s.

[0014] Preferably, the excess air coefficient in the burnout zone is 1.05-1.4, and the flue gas residence time is controlled at 0.2-1.8 s.

[0015] Preferably, the recycled flue gas includes CO2=10-18%, O2=4-10%, N2=66-80%, and H2O=0-16%.

[0016] Preferably, the conditioning gas includes one or more of natural gas, carbon monoxide, hydrogen, methane, coal gas and unsaturated hydrocarbon gas.

[0017] The above method uses active gas to condition pulverized coal and then burn to reduce NO xThe method and device include a pulverized coal combustion chamber which is sequentially provided with a main combustion zone, a reburning zone and a burnout zone from bottom to top, a main burner connected to the main combustion zone is provided with a primary air nozzle and a secondary air nozzle, a reburning burner connected to the reburning zone is provided with a reburning pulverized coal nozzle, the reburning pulverized coal nozzle is connected with a tempering gas nozzle, and a burnout burner connected to the burnout zone is provided with a separation burnout air nozzle.

[0018] Preferably, one end of the primary air nozzle away from the main burner is connected to the primary air duct, and one end of the secondary air nozzle away from the main burner is connected to the secondary air duct.

[0019] Preferably, the end of the reburning pulverized coal nozzle away from the reburning burner is connected to the reburning pulverized coal pipeline and the tempering gas nozzle respectively, and the end of the tempering gas nozzle away from the reburning burner is connected to the tempering gas pipeline.

[0020] Preferably, one end of the separation overburn air nozzle away from the overburn burner is communicated with the separation overburn air duct.

[0021] Therefore, the beneficial effects of the present invention using the above technical solution are:

[0022] 1. The present invention sets the tempering gas nozzle at the reburning burner, and uses the principle of enhanced combustion to make the tempering gas fully react with oxygen, and consume the excess oxygen in the recycled flue gas through the combustion reaction. That is, with a small amount of combustible gas, a stable tempering zone with strong reducing properties and suitable temperature can be obtained, thereby tempering the fuel, which not only ensures the reduction of NO x The effect of emission and the proportion of reburned coal powder are reduced;

[0023] 2. The present invention cleverly uses active gas as conditioning gas to condition the reburned coal powder, which can ensure the reduction of NO x The emission effect is improved, and the use of expensive tempering gas is reduced to the greatest extent, ensuring the economic efficiency of device investment and operation;

[0024] 3. The present invention uses tempering gas to temper the reburned coal powder. The tempering gas reacts rapidly with the oxygen in the circulating flue gas, releasing a large number of reducing free radicals, protecting the active sites on the surface of the coal coke, and enhancing the ability of the coke to reduce NO. x The removal efficiency is improved, and the specific surface area of ​​the coke after activation by the tempering gas is increased;

[0025] 4. The device provided by the present invention is easy to arrange and has strong adaptability to coal types.

[0026] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] FIG1 is a method of reducing NO by reburning pulverized coal tempered with active gas according to the present invention. x A schematic diagram of the device;

[0028] FIG2 is a combined diagram of the NO reduction capabilities of Examples 3, 6, 7, 9, and Comparative Example 1 of the present invention.

[0029] 2 (a) is a trend diagram of the change in NO concentration when reducing NO in Example 3, Example 6, Example 7, Example 9 and Comparative Example 1.

[0030] FIG2( b ) is a comparison chart of the NO reduction capabilities of Example 3, Example 6, Example 7, Example 9 and Comparative Example 1;

[0031] FIG3 is a combined graph of the specific surface area of ​​coal char in Examples 3, 6, 7, 9 and Comparative Example 1 of the present invention,

[0032] 3 (a) is a comparison of the specific surface areas of activated coal char in Example 3, Example 6, Example 7, Example 9 and Comparative Example 1.

[0033] Figure 3 (b) is a comparison of the pore volumes of different activated coal cokes in Example 3, Example 6, Example 7, Example 9 and Comparative Example 1;

[0034] FIG4 is a graph showing the NO in Example 8 of the present invention and Comparative Example 1 and Comparative Example 2. x Removal efficiency curve.

[0035] Reference numerals

[0036] 1. Main burner; 2. Afterburner; 3. Tempering gas nozzle; 4. Burnout burner; 5. Pulverized coal combustion chamber. DETAILED DESCRIPTION

[0037] The technical solution of the present invention is further described below with reference to the accompanying drawings and embodiments.

[0038] Unless otherwise defined, the technical or scientific terms used in the present invention shall have the usual meanings understood by persons of ordinary skill in the field to which the present invention belongs. The words "first", "second" and similar terms used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "include" or "comprise" mean that the elements or objects preceding the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0039] Example 1

[0040] A method for reducing NO by using activated gas to condition pulverized coal and then burning it x The method and device include a pulverized coal combustion chamber 5 having a main combustion zone, a reburning zone, and a burnout zone arranged in sequence from bottom to top. The main combustion zone is connected to a main burner 1 provided with a primary air nozzle and a secondary air nozzle, the reburning zone is connected to a reburning burner 2 provided with a reburning pulverized coal nozzle, the reburning pulverized coal nozzle is connected to a tempering gas nozzle 3, and the burnout zone is connected to a burnout burner 4 provided with a separation burnout air nozzle.

[0041] The end of the primary air nozzle remote from the main burner 1 is connected to the primary air duct, and the end of the secondary air nozzle remote from the main burner 1 is connected to the secondary air duct. Hot air A passes through the secondary air duct and the secondary air nozzle of the main burner 1 in sequence and enters the main combustion zone. The mixed airflow B of the primary air and pulverized coal passes through the primary air duct and the primary air nozzle of the main burner 1 in sequence and enters the main combustion zone.

[0042] The end of the reburn pulverized coal nozzle remote from the reburn burner 2 is connected to the reburn pulverized coal pipeline and the tempered gas nozzle, respectively. The end of the tempered gas nozzle 3 remote from the reburn burner is connected to the tempered gas pipeline. A mixed flow C of recycled flue gas, hot air, and reburn pulverized coal flows sequentially through the reburn pulverized coal pipeline and reburn burner 2 into the reburn zone. Tempered gas D flows sequentially through the tempered gas pipeline, tempered gas nozzle 3, and reburn burner 2 into the reburn zone.

[0043] The tempering gas nozzle 3 is set at the outlet of the reburning pulverized coal nozzle. The principle of enhanced combustion is used to make the tempering gas fully react with oxygen. The tempering gas can react quickly with the oxygen in the carrier gas to form a tempering zone at the front end of the nozzle of the reburning burner 2. The excess oxygen in the recycled flue gas is consumed by the combustion reaction. That is, a stable tempering zone with strong reducing properties and suitable temperature can be obtained with a small amount of combustible gas, thereby tempering the fuel. The gaseous reducing molecules (CH i , CO, OH and H, etc.) and NO x A homogeneous reduction reaction occurs. This ensures the reduction of NO x The emission effect is improved and the proportion of reburned coal powder is reduced.

[0044] One end of the separation overburnt air nozzle away from the overburnt burner 4 is connected to the separation overburnt air duct, and the hot air A enters the burnt-out zone through the separation overburnt air duct and the separation overburnt air nozzle in sequence.

[0045] Example 2

[0046] A method for reducing NO by using activated gas to condition pulverized coal and then burning it xThe combustion method of the device, as shown in Figure 1, includes the following steps: S1. 75% high-volatile coal fuel is carried by primary air through the primary air duct, primary air nozzle, and main burner on one side of the pulverized coal combustion chamber, entering the main combustion zone, with the primary air ratio accounting for 35%. Hot air then enters the main combustion zone through the secondary air duct, secondary air nozzle, and main burner, with the secondary air ratio accounting for 65%. The excess air coefficient in the main combustion zone is controlled at 0.65, and the residence time in the main combustion zone is controlled at approximately 1.2 seconds.

[0047] S2, a 25% medium- and high-volatile coal fuel, is carried by the recirculated flue gas through the reburn coal duct and into the reburn burner above the main burner. The recirculated flue gas composition is N2:CO2:O2 = 80:16:4. Simultaneously, 2% tempered gas (methane, CH4) enters the reburn burner via the tempered gas duct, the tempered gas nozzle, and the recirculated flue gas nozzle. The medium- and high-volatile coal fuel and tempered gas mix within the reburn burner before entering the reburn zone. The excess air coefficient in the reburn zone is 0.6, and the residence time in the reburn zone is controlled at 1.1 s.

[0048] S3: Hot air enters the burnout zone through the separate burnout air duct, the separate burnout air nozzle, and the burnout burner above the reburner, burning off the combustion products. The burnout zone has an excess air coefficient of 1.4 and a residence time of 1.0 s to completely burn off the residual char.

[0049] Example 3

[0050] A method for reducing NO by using activated gas to condition pulverized coal and then burning it x The combustion method of the device includes the following steps: S1. 80% high-volatile coal fuel is carried by primary air and injected into the main combustion zone through the primary air duct and primary air nozzles, with the primary air ratio accounting for 30%. Hot air enters the main combustion zone through the secondary air duct and secondary air nozzles, with the secondary air ratio accounting for 70%. The excess air coefficient in the main combustion zone is controlled at 0.75, and the residence time in the main combustion zone is controlled at approximately 1.0 s.

[0051] S2, 20% high-volatile coal fuel, is carried by the recirculated flue gas through the reburn coal duct and enters the reburn burner. The recirculated flue gas composition is N2:CO2:O2 = 80:16:4. Simultaneously, 3% tempered gas (methane, CH4) enters the reburn burner via the tempered gas duct, the tempered gas nozzle, and the recirculated flue gas nozzle. The high-volatile coal fuel and tempered gas mix within the reburn burner before entering the reburn zone. The excess air coefficient in the reburn zone is 0.7, and the residence time in the reburn zone is controlled at 1.0 s.

[0052] S3: Hot air passes through the separate burnout air duct and separate burnout air nozzles and enters the burnout burner, burning the combustion products. The excess air coefficient in the burnout zone is 1.3, and the residence time is controlled at 1.1 seconds, completely burning the residual char.

[0053] Example 4

[0054] A method for reducing NO by using activated gas to condition pulverized coal and then burning it x The combustion method of the device includes the following steps: S1. When the coal type is Shenhua bituminous coal, 85% of the fuel is carried by primary air and injected into the main combustion zone through the primary air duct and primary air nozzle in sequence, with the primary air ratio accounting for 20%. Hot air enters the main combustion zone through the secondary air duct and secondary air nozzle in sequence, with the secondary air ratio accounting for 80%. The excess air coefficient in the main combustion zone is controlled at 0.9, and the residence time in the main combustion zone is controlled at approximately 0.8 seconds.

[0055] S2 and 15% high-volatile coal fuel are carried by the recirculated flue gas through the reburn coal duct and enter the reburn burner. The recirculated flue gas composition is N2:CO2:O2 = 80:12:8. Simultaneously, 4% tempered gas CH4 enters the reburn burner through the tempered gas duct, the tempered gas nozzle, and the recirculated flue gas nozzle. The high-volatile coal fuel and tempered gas mix within the reburn burner before entering the reburn zone. The excess air coefficient in the reburn zone is 0.8, and the residence time in the reburn zone is controlled at 0.8 s.

[0056] S3: Hot air passes through the separate burnout air duct and separate burnout air nozzles and enters the burnout burner, burning the combustion products. The excess air coefficient in the burnout zone is 1.2, and the residence time is controlled at 1.2 seconds to burn the residual char.

[0057] Example 5

[0058] A method for reducing NO by using activated gas to condition pulverized coal and then burning it x The combustion method of the device includes the following steps: S1. 90% of the high-volatile coal fuel is carried by primary air and injected into the main combustion zone through the primary air duct and primary air nozzles, with the primary air ratio accounting for 10%. Hot air enters the main combustion zone through the secondary air duct and secondary air nozzles, with the secondary air ratio accounting for 90%. The excess air coefficient in the main combustion zone is controlled at 1.05, and the residence time in the main combustion zone is controlled at approximately 0.6 seconds.

[0059] S2 and 15% high-volatile coal fuel are carried by the recirculated flue gas through the reburn pulverized coal duct and enter the reburn burner. The recirculated flue gas composition is N2:CO2:O2 = 80:10:10. Simultaneously, 5% tempered gas CH4 enters the reburn burner through the tempered gas duct, the tempered gas nozzle, and the recirculated flue gas nozzle. The high-volatile coal fuel and tempered gas mix within the reburn burner before entering the reburn zone. The excess air coefficient in the reburn zone is 0.9, and the residence time in the reburn zone is controlled at 0.6 s.

[0060] S3: Hot air passes through the separate burnout air duct and separate burnout air nozzles and enters the burnout burner, burning the combustion products. The excess air coefficient in the burnout zone is 1.1, and the residence time is controlled at 1.3 seconds, completely burning the residual char.

[0061] Example 6

[0062] A method for reducing NO by using activated gas to condition pulverized coal and then burning it x The combustion method of the device includes the following steps: S1. 80% of the high-volatile coal fuel is carried by primary air and injected into the main combustion zone through the primary air duct and primary air nozzles, with the primary air ratio accounting for 30%. Hot air enters the main combustion zone through the secondary air duct and secondary air nozzles, with the secondary air ratio accounting for 70%. The excess air coefficient in the main combustion zone is controlled at 0.75, and the residence time in the main combustion zone is controlled at approximately 1.0 s.

[0063] S2: 20% of the high-volatile coal fuel is carried by the recirculated flue gas through the reburned coal duct and enters the reburn burner. The recirculated flue gas composition is N2:CO2:O2 = 80:14:6. Simultaneously, 3% of the coal-based gas enters the reburn burner through the tempered gas duct, the tempered gas nozzle, and the recirculated flue gas nozzle. The high-volatile coal fuel and tempered gas mix within the reburn burner before entering the reburn zone. The excess air coefficient in the reburn zone is 0.7, and the residence time in the reburn zone is controlled at 1.0 s.

[0064] The composition of coal-to-gas is CH4=10%, CO=60%, and H2=30%.

[0065] S3: Hot air passes through the separate burnout air duct and separate burnout air nozzles and enters the burnout burner, burning the combustion products. The excess air coefficient in the burnout zone is 1.3, and the residence time is controlled at 1.1 seconds, completely burning the residual char.

[0066] Example 7

[0067] A method for reducing NO by using activated gas to condition pulverized coal and then burning it x The combustion method of the device includes the following steps: S1. 80% of the high-volatile coal fuel is carried by primary air and injected into the main combustion zone through the primary air duct and primary air nozzles, with the primary air ratio accounting for 30%. Hot air enters the main combustion zone through the secondary air duct and secondary air nozzles, with the secondary air ratio accounting for 70%. The excess air coefficient in the main combustion zone is controlled at 0.75, and the residence time in the main combustion zone is controlled at approximately 1.0 s.

[0068] S2: 20% high-volatile coal fuel is carried by the recirculated flue gas through the reburning pulverized coal pipeline and enters the reburning burner. The recirculated flue gas composition is N2:CO2:O2 = 80:14:6. Simultaneously, 3% hydrogen (H2) enters the reburning burner through the tempering gas pipeline, the tempering gas nozzle, and the recirculated flue gas nozzle. The high-volatile coal fuel and tempering gas mix within the reburning burner and enter the reburning zone. The excess air coefficient in the reburning zone is 0.7, and the residence time in the reburning zone is controlled at 1.0 s.

[0069] S3: Hot air passes through the separate burnout air duct and separate burnout air nozzles and enters the burnout burner, burning the combustion products. The excess air coefficient in the burnout zone is 1.3, and the residence time is controlled at 1.1 seconds, completely burning the residual char.

[0070] Example 8

[0071] A method for reducing NO by using activated gas to condition pulverized coal and then burning it x The combustion method of the device includes the following steps: S1. 90% of the high-volatile coal fuel is carried by primary air and injected into the main combustion zone through the primary air duct and primary air nozzles, with the primary air rate being 30%. Hot air is then injected into the main combustion zone through the secondary air duct and secondary air nozzles, with the secondary air rate being 70%. The excess air coefficient in the main combustion zone is controlled at 0.8, and the residence time in the main combustion zone is controlled at approximately 1.0 s.

[0072] S2 and 15% high-volatile coal fuel are carried by the recirculated flue gas through the reburn coal duct and enter the reburn burner. The recirculated flue gas composition is N2:CO2:O2 = 80:10:10. Simultaneously, 5% tempered gas CH4 enters the reburn burner through the tempered gas duct, the tempered gas nozzle, and the recirculated flue gas nozzle. The high-volatile coal fuel and tempered gas mix within the reburn burner before entering the reburn zone. The excess air coefficient in the reburn zone is 0.85, and the residence time in the reburn zone is controlled at 0.8 s.

[0073] S3: Hot air passes through the separate burnout air duct and separate burnout air nozzles and enters the burnout burner, burning the combustion products. The excess air coefficient in the burnout zone is 1.15, and the residence time is controlled at 1.0 s to burn the residual char.

[0074] Example 9

[0075] A method for reducing NO by using activated gas to condition pulverized coal and then burning it x The combustion method of the device includes the following steps: S1. 80% high-volatile coal fuel is carried by primary air and injected into the main combustion zone through the primary air duct and primary air nozzles, with the primary air ratio accounting for 30%. Hot air enters the main combustion zone through the secondary air duct and secondary air nozzles, with the secondary air ratio accounting for 70%. The excess air coefficient in the main combustion zone is controlled at 0.75, and the residence time in the main combustion zone is controlled at approximately 1.0 s.

[0076] S2, 20% high-volatile coal fuel, is carried by the recirculated flue gas through the reburn coal duct and enters the reburn burner. The recirculated flue gas composition is N2:CO2:O2 = 80:16:4. Simultaneously, 3% conditioned gas (CO) enters the reburn burner via the conditioned gas duct, the conditioned gas nozzle, and the recirculated flue gas nozzle. The high-volatile coal fuel and conditioned gas mix within the reburn burner before entering the reburn zone. The excess air coefficient in the reburn zone is 0.7, and the residence time in the reburn zone is controlled at 1.0 s.

[0077] S3: Hot air passes through the separate burnout air duct and separate burnout air nozzles and enters the burnout burner, burning the combustion products. The excess air coefficient in the burnout zone is 1.3, and the residence time is controlled at 1.1 seconds, completely burning the residual char.

[0078] Comparative Example 1

[0079] S1. 80% of the high-volatile coal fuel is carried by primary air and injected into the main combustion zone through primary air ducts and primary air nozzles, with the primary air ratio accounting for 30%. Hot air enters the main combustion zone through secondary air ducts and secondary air nozzles, with the secondary air ratio accounting for 70%. The excess air coefficient in the main combustion zone is controlled at 0.75, and the residence time in the main combustion zone is controlled at approximately 1.0 s.

[0080] S2: 20% of the high-volatile coal fuel is carried by the circulating flue gas through the reburning pulverized coal pipeline into the reburning burner and then into the reburning zone. The circulating flue gas composition is N2:CO2:O2 = 80:14:6. The excess air coefficient in the reburning zone is 0.7, and the residence time in the reburning zone is controlled at 1.0 s.

[0081] S3: Hot air passes through the separate burnout air duct and separate burnout air nozzles and enters the burnout burner, burning the combustion products. The excess air coefficient in the burnout zone is 1.3, and the residence time is controlled at 1.1 seconds, completely burning the residual char.

[0082] Comparative Example 2

[0083] S1. 80% of the high-volatile coal fuel is carried by primary air and injected into the main combustion zone through primary air ducts and primary air nozzles, with the primary air ratio accounting for 30%. Hot air enters the main combustion zone through secondary air ducts and secondary air nozzles, with the secondary air ratio accounting for 70%. The excess air coefficient in the main combustion zone is controlled at 0.75, and the residence time in the main combustion zone is controlled at approximately 1.0 s.

[0084] S2. 20% of high-volatile coal fuel is carried by hot air through the reburning pulverized coal pipeline into the reburning burner and then into the reburning zone. The excess air coefficient of the reburning zone is 0.7, and the residence time in the reburning zone is controlled at 1.0 s.

[0085] S3: Hot air passes through the separate burnout air duct and separate burnout air nozzles and enters the burnout burner, burning the combustion products. The excess air coefficient in the burnout zone is 1.3, and the residence time is controlled at 1.1 seconds, completely burning the residual char.

[0086] Test Example 1

[0087] a. Test NO reduction capacity using microfluidized bed reactor analyzer (MFBRA)

[0088] The MFBRA system rapidly heats the sample and monitors the post-combustion gaseous products with a mass spectrometer, thereby capturing the actual char conversion process. The test temperature was 1073 K in an atmosphere that simulated the reburning zone of pulverized coal (4% O₂, 20% CO₂, 500 ppm NO, and the remainder Ar). Each experiment used 3 ± 0.01 mg of sample.

[0089] During data processing, to facilitate comparison of the NO reduction capacities of Example 3 (methane), Example 6 (coal-to-gas), Example 7 (hydrogen), Example 9 (carbon monoxide), and Comparative Example 1 (recycled flue gas), all NO reduction capacity data were normalized to 1 mg. Preliminary experiments demonstrated that all samples completed the reaction within 10 seconds. For trace samples, the NO reduction capacity was assumed to be proportional to the mass of the sample in the reactor. The instantaneous NO concentration was integrated over the reaction time, and the absolute value of the area below the line at a NO concentration of 500 ppm was A1. The absolute value of the area below the line at a NO concentration of 500 ppm was A2. The difference between A1 and A2 represents the NO reduction capacity of the coke.

[0090] As shown in Figure 2, (a) shows the NO concentration trends during NO reduction in Examples 3, 6, 7, 9, and Comparative Example 1; (b) shows a comparison of the NO reduction capabilities of Examples 3, 6, 7, 9, and Comparative Example 1. As shown in Figure 2, compared with the use of flue gas alone to transport pulverized coal, the NO reduction capability of the coke increased by nearly 75% after CH4 activation in Example 3, by nearly 5% after CO activation in Example 9, and by nearly 19% after H2 activation in Example 7.

[0091] b. Specific surface area test

[0092] As shown in Figure 3, (a) compares the specific surface areas of activated char in Examples 3, 6, 7, and 9, and Comparative Example 1, while (b) compares the pore volumes of activated char in Examples 3, 6, 7, and 9, and Comparative Example 1. Compared to Comparative Example 1, where pulverized coal was conveyed using recycled flue gas alone, the specific surface area of ​​the char in Example 3 (methane), Example 6 (coal-to-gas), Example 7 (hydrogen), Example 9 (carbon monoxide), and Comparative Example 1 (recycled flue gas) increased by nearly 54.2% after CH4 activation, by nearly 3% after CO activation, and by nearly 12.3% after H2 activation. This indicates that the combustion method of the present invention utilizes the heat released by the instantaneous combustion of the conditioning gas and oxygen to promote the release of volatiles, thereby enriching the pore structure of the char.

[0093] c. NO x Removal efficiency

[0094] As shown in FIG4 , compared with Comparative Example 2, Example 8 has a NO x The removal efficiency of NO was increased by 36.9%. Compared with Comparative Example 1, Example 8 x The removal efficiency was increased by 22.2% (the oxygen content in the flue gas was converted to 6%).

[0095] Therefore, the present invention adopts a method of reducing NO by using active gas to condition pulverized coal and then burning it. x The device and method use the tempering gas to temper the solid fuel, which can reduce NO x It can not only reduce the emission effect, but also alleviate the problems such as poor burnout caused by using a high proportion of reburned coal powder.

[0096] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for reducing NO by reburning pulverized coal tempered with active gas x is characterized in that: It includes the following steps: S1. 75-90% of medium and high volatile coal fuel is carried by primary air and sprayed into the main burner on one side of the pulverized coal combustion chamber successively through the primary air duct and the primary air nozzle. Hot air enters the main combustion zone through the secondary air duct, the secondary air nozzle and the main burner successively. S2. 10 - 25% of the medium- and high-volatile coal fuel is carried by the recirculated flue gas through the reclaimed pulverized coal pipeline and the reclaimed pulverized coal nozzle into the reburning burner above the main burner. At the same time, 0 - 6% of the conditioning gas sequentially passes through the conditioning gas pipeline, the conditioning gas nozzle, and the reclaimed pulverized coal nozzle into the reburning burner. The medium- and high-volatile coal fuel and the conditioning gas are mixed in the reburning burner and then enter the reburning zone. As soon as the medium- and high-volatile coal fuel is injected into the reburning zone, it is quickly activated by the conditioning gas into gaseous CH i , CO, OH, and H, as well as highly reactive coke; S3. Hot air enters the burnout zone through the separated overfire air duct, the separated overfire air nozzle and the burnout burner above the reburning burner successively to burn out the combustion products.

2. A method for reducing NO by reburning pulverized coal tempered with active gas according to claim 1 x , characterized in that: The excess air coefficient in the main combustion zone is controlled at 0.65-1.05, and the residence time of the flue gas is controlled at about 0.2-1.4 s.

3. A method for reducing NO by reburning pulverized coal conditioned with active gas according to claim 1 x , characterized in that: The excess air coefficient in the reburning zone is 0.6-0.95, and the residence time of the flue gas is controlled at 0.2-1.3 s.

4. A method for reducing NO by reburning pulverized coal tempered with active gas according to claim 1 x , characterized in that: The excess air coefficient in the burnout zone is 1.05-1.4, and the residence time of the flue gas is controlled at 0.2-1.8 s.

5. A method for reducing NO by reburning pulverized coal conditioned with active gas according to claim 1 x , characterized in that: The recycled flue gas includes CO2 = 10-18%, O2 = 4-10%, N2 = 66-80%, H2O = 0-16%.

6. A method for reburning and reducing NO by tempering pulverized coal with active gas according to claim 1 x , characterized in that: The conditioning gas includes one or more of natural gas, carbon monoxide, hydrogen, methane, coal gas and unsaturated hydrocarbon gases.

7. A device for the method of using activated gas to temper pulverized coal for reburning to reduce NO according to any one of claims 1-6, characterized in that: x It includes a pulverized coal combustion chamber with a main combustion zone, a reburning zone and a burnout zone arranged successively from bottom to top. The main burner connected to the main combustion zone is provided with a primary air nozzle and a secondary air nozzle. The reburning burner connected to the reburning zone is provided with a reburning pulverized coal nozzle. The reburning pulverized coal nozzle is connected to a conditioning gas nozzle. The burnout burner connected to the burnout zone is provided with a separated overfire air nozzle.

8. A device for the method of using active gas to temper pulverized coal for reburning to reduce NO x is characterized in that: One end of the primary air nozzle far from the main burner is connected to the primary air duct, and one end of the secondary air nozzle far from the main burner is connected to the secondary air duct.

9. A device for the method of using active gas to temper pulverized coal for reburning to reduce NO x is characterized in that: One end of the reburning pulverized coal nozzle far from the reburning burner is respectively connected to the reburning pulverized coal duct and the conditioning gas nozzle, and one end of the conditioning gas nozzle far from the reburning burner is connected to the conditioning gas duct.

10. A device for the method of using active gas to temper pulverized coal for reburning to reduce NO x is characterized in that: One end of the separated overfire air nozzle far from the burnout burner is connected to the separated overfire air duct.

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