Hydrogen blending combustion system and method for boiler and control method

Abstract

The invention discloses a boiler hydrogen blending combustion system and method and a control method. According to the scheme, the boiler hydrogen blending combustion system comprises a boiler unit, a flue gas system loop, a primary air system loop, a hydrogen fuel system loop and a hydrogen blending combustion distribution valve set. According to the hydrogen blending combustion system of the boiler, when a boiler unit runs in a 15%-30% low-load mode and runs in a rapid load reduction mode, hot primary air can be heated through high-temperature flue gas emitted by combustion of a hydrogen combustor arranged in a hot primary air flue, specifically, the temperature of the hot primary air is increased to be within 400 DEG C, and the temperature of the hot primary air is increased to be within 400 DEG C; and finally, hot primary air is fed into a hearth to participate in combustion, so that the bed temperature of a boiler unit during 15-30% load deep peak regulation low-load operation is increased, and the stable combustion capacity of the boiler is improved.

Description

Technical Field

[0001] The present application relates to the technical field of power systems, and particularly relates to a boiler hydrogen co-firing system, method, and control method. Background Art

[0002] Currently, large-scale circulating fluidized bed (CFB) boilers face multiple technical challenges such as deep peak shaving and carbon emission reduction. Currently, the peak shaving load is extended to 15%-30% BMCR through flue gas recirculation technology. However, affected by inferior coal types, the bed temperature decreases by 20-30°C under deep peak shaving conditions, resulting in insufficient stable combustion capacity and increased carbon content in fly ash. Moreover, SNCR denitration fails because the flue gas temperature is lower than the reaction window (750-950°C). In addition, problems such as high cost of hydrogen co-firing and insufficient economy of carbon capture technology are prominent during low-carbon transformation.

[0003] Therefore, there is an urgent need to develop an integrated solution that takes into account both deep peak shaving and low-carbon operation: it is necessary to break through the technical bottleneck of stable combustion at low loads, optimize bed temperature control to ensure SNCR efficiency; explore fuel substitution paths that synergize hydrogen co-firing with biomass / green ammonia to reduce carbon emission intensity; study the coordinated regulation of fluidization state and combustion efficiency to achieve ultra-low NOx emissions and economic operation under deep peak shaving conditions. These technological innovations play an important supporting role in building a new power system with new energy as the main body. Summary of the Invention

[0004] The present application proposes a boiler hydrogen co-firing system, method, and control method to improve the stable combustion capacity of the boiler.

[0005] To achieve the above object, the present application discloses the following technical solutions:

[0006] In a first aspect, the present application provides a boiler hydrogen co-firing system, including a boiler unit, a flue gas system circuit, a primary air system circuit, a hydrogen fuel system circuit, and a hydrogen co-firing distribution valve group.

[0007] The flue gas system circuit is connected to the primary air system circuit.

[0008] The primary air system circuit is connected to the hydrogen burner of the boiler unit.

[0009] The hydrogen fuel system circuit is connected to at least two hydrogen burners of the boiler unit through the hydrogen co-firing distribution valve group to regulate the co-firing gas volume entering the hydrogen burners.

[0010] At least two hydrogen burners include a first hydrogen burner arranged at the primary air inlet of the furnace of the boiler unit and a second hydrogen burner arranged at the separator of the boiler unit.

[0011] In some embodiments, the boiler unit includes a furnace, a separator, a economizer, an air preheater, a dust collector, a desulfurization system, an induced draft fan and a chimney which are connected in sequence, and a denitration system is arranged at the top of the furnace.

[0012] In some embodiments, the flue gas system circuit includes a flue gas recirculation pipeline, a flue gas recirculation fan, a first flow measurement device and a first electric valve. The flue gas recirculation fan, the first flow measurement device and the first electric valve are connected in series on the flue gas recirculation pipeline. One end of the flue gas recirculation pipeline is connected to the induced draft fan, and the other end of the flue gas recirculation pipeline is connected to the primary air system circuit. The first flow measurement device is used to measure the flue gas recirculation volume on the flue gas recirculation pipeline, and the first electric valve is used to adjust the flue gas recirculation volume on the flue gas recirculation pipeline.

[0013] In some embodiments, the primary air system circuit includes a primary air pipeline, a primary air fan and a second electric valve. Among them, the primary air fan, the air preheater and the second electric valve are connected in series on the primary air pipeline. The primary air pipeline is connected to the hydrogen burner, and the second electric valve is used to adjust the primary cold air volume on the primary air pipeline.

[0014] In some embodiments, the hydrogen fuel system circuit includes a green hydrogen production system, a hydrogen compressor, a hydrogen storage system, a second flow measurement device and a third electric valve which are connected in sequence. The second flow measurement device is used to measure the hydrogen volume on the hydrogen fuel system circuit, and the third electric valve is connected to the hydrogen co-firing distribution valve group to adjust the hydrogen volume on the hydrogen fuel system circuit.

[0015] In some embodiments, the hydrogen burner further includes a third hydrogen burner, and the third hydrogen burner is arranged at the secondary air outlet of the furnace.

[0016] In some embodiments, the hydrogen co-firing distribution valve group includes a first main valve, a second main valve, a third main valve, a first branch valve group, a second branch valve group and a third branch valve group. The first main valve group is connected to the first branch valve group, the second main valve is connected to the second branch valve group, and the third main valve is connected to the third branch valve group. The first branch valve group is connected to the first hydrogen burner, the second branch valve group is connected to the second hydrogen burner, and the third branch valve group is connected to the third hydrogen burner.

[0017] In some embodiments, the separator is a cyclone separator, and the second hydrogen burner is arranged at the conical section of the separator.

[0018] In some embodiments, it further includes a hydrogen monitoring device and a carbon monoxide monitoring device arranged at the economizer, and when the monitored hydrogen content reaches a preset range or the monitored carbon monoxide content reaches a second preset range, the secondary air volume of the furnace is increased.

[0019] In a second aspect, the present application provides a method for hydrogen co-firing in a boiler, including the following steps:

[0020] The primary hot air temperature t1 (°C) before hydrogen co-firing under deep load regulation conditions, and the hot primary air temperature t2 (°C) after hydrogen co-firing

[0021] According to the empirical model, the hydrogen co-firing amount z (10 4 Nm 3 / h), the primary cold air volume x (10 4 Nm 3 / h), and the recycled flue gas volume y (10 4 Nm 3 / h) under the load condition of 15% - 30% are calculated

[0022] Taking the calculated recycled flue gas volume y as the control set value of the flue gas system loop, making a deviation from the actual flue gas recirculation volume, and forming a control signal through a PID controller to act on the flue gas system loop to achieve automatic control of the flue gas recirculation volume

[0023] Setting the primary air temperature t2 after hydrogen co-firing as the set value, making a deviation from the actual primary air temperature after hydrogen co-firing, and forming a control signal through a PID controller to act on the hydrogen co-firing distribution valve group for automatically controlling the hydrogen co-firing amount in the primary hot air duct

[0024] In some embodiments, the empirical model includes:

[0025] .

[0026] In some embodiments, the primary hot air temperature t1 (°C) before hydrogen co-firing under deep load regulation conditions, and the hot primary air temperature t2 (°C) after hydrogen co-firing, include:

[0027] According to the bed temperature condition when burning the actual coal type under the low load condition of the boiler, extracting the primary hot air temperature t1 before hydrogen co-firing from the historical curve, and setting the target hot primary air temperature t2 after hydrogen co-firing

[0028] Thirdly, the present application provides a method for hydrogen co-firing in a boiler, including the following steps:

[0029] Under the conditions of the boiler unit operating at a low load of 15% - 30% and rapid load reduction, heating the hot primary air temperature to within 400 °C by using the high-temperature flue gas released by the first burner arranged at the primary air outlet

[0030] In some embodiments, the method further includes:

[0031] When the boiler NOx cannot achieve ultra-low emissions under the condition of 20% load or below only through in-furnace combustion adjustment under deep load regulation conditions, using the high-temperature flue gas released by the second hydrogen burner arranged at the separator to increase the temperature in the separator to above 750 °C

[0032] As can be seen from the above technical solutions, in the boiler hydrogen co-firing system of the present application, when the boiler unit operates at a low load of 15% - 30% and during rapid load reduction, the high-temperature flue gas released by the combustion of the hydrogen burner installed in the hot primary air duct can be used to heat the temperature of the hot primary air. Specifically, it includes raising the temperature of the hot primary air to within 400°C, and finally the hot primary air is sent into the furnace to participate in combustion, thereby increasing the bed temperature during the low-load operation of the boiler unit with a deep peak shaving load of 15% - 30% and improving the stable combustion ability of the boiler. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some examples or embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained according to the provided drawings, and the present application can also be applied to other similar scenarios according to the provided drawings. Unless obvious from the language context or otherwise stated, the same reference numerals in the figures represent the same structure or operation.

[0034] Figure 1 Schematic diagram of a boiler hydrogen co-firing system provided by an embodiment of the present application;

[0035] Figure 2 Schematic diagram of a hydrogen co-firing distribution valve group provided by an embodiment of the present application;

[0036] Figure 3 Schematic diagram of a boiler hydrogen co-firing control method provided by an embodiment of the present application;

[0037] Figure 4 Schematic diagram of a boiler hydrogen co-firing method provided by an embodiment of the present application;

[0038] In the figure: 11 - furnace; 12 - separator; 13 - economizer; 14 - air preheater; 15 - dust collector; 16 - desulfurization system; 17 - induced draft fan; 18 - chimney; 19 - denitration system;

[0039] 21 - flue gas recirculation pipeline; 22 - flue gas recirculation fan; 23 - first flow measurement device; 24 - first electric valve;

[0040] 31 - primary air pipeline; 32 - primary air fan; 33 - second electric valve;

[0041] 41 - green hydrogen production system; 42 - hydrogen compressor; 43 - hydrogen storage system; 44 - second flow measurement device; 45 - third electric valve;

[0042] 5 - Hydrogen Blending Combustion Distribution Valve Group; 51 - First Main Valve; 52 - Second Main Valve; 53 - Third Main Valve; 54 - First Branch Valve Group; 55 - Second Branch Valve Group; 56 - Third Branch Valve Group;

[0043] 61 - First Hydrogen Burner; 62 - Second Hydrogen Burner; 63 - Third Hydrogen Burner;

[0044] 71 - Carbon Monoxide Monitoring Device; 72 - Hydrogen Monitoring Device. Detailed Implementation Manner

[0045] The following further elaborates on the present application in conjunction with the accompanying drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the relevant application and do not limit the application. The described embodiments are only a part of the embodiments of the present application, not all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts fall within the scope of protection of the present application.

[0046] See Figures 1 to 2 , in order to achieve the above - mentioned purpose, the present application discloses the following technical solutions:

[0047] A boiler hydrogen blending combustion system includes a boiler unit, a flue gas system loop, a primary air system loop, a hydrogen fuel system loop, and a hydrogen blending combustion distribution valve group 5. The flue gas system loop is connected to the primary air system loop; the primary air system loop is connected to the hydrogen burners of the boiler unit; the hydrogen fuel system loop is connected to at least two hydrogen burners of the boiler unit through the hydrogen blending combustion distribution valve group 5 to regulate the amount of blended combustion gas entering the hydrogen burners; at least two hydrogen burners include a first hydrogen burner 61 arranged at the primary air outlet of the furnace 11 of the boiler unit and a second hydrogen burner 62 arranged at the separator 12 of the boiler unit.

[0048] In the boiler hydrogen blending combustion system of the present application, when the boiler unit operates at a low load of 15% - 30% and during rapid load reduction operation, the high - temperature flue gas released by the combustion of the hydrogen burner arranged in the hot primary air duct can be used to heat the temperature of the hot primary air. Specifically, it includes raising the temperature of the hot primary air to within 400°C, and finally the hot primary air is sent into the furnace 11 to participate in combustion, thereby raising the bed temperature during the low - load operation of the 15% - 30% load deep - peak regulation of the boiler unit and improving the stable combustion ability of the boiler.

[0049] The above - mentioned boiler unit includes a furnace 11, a separator 12, a economizer 13, an air preheater 14, a dust collector 15, a desulfurization system 16, an induced draft fan 17, and a chimney 18 connected in sequence. A denitration system 19 is arranged at the top of the furnace 11.

[0050] The above flue gas system loop is used to heat the air preheater 14 and may include a flue gas recirculation pipeline 21, a flue gas recirculation fan 22, a first flow measurement device 23, and a first electric valve 24. The flue gas recirculation fan 22, the first flow measurement device 23, and the first electric valve 24 are connected in series on the flue gas recirculation pipeline 21. One end of the flue gas recirculation pipeline 21 is connected to the induced draft fan 17, and the other end of the flue gas recirculation pipeline 21 is connected to the primary air system loop. The first flow measurement device 23 is used to measure the flue gas recirculation volume on the flue gas recirculation pipeline 21, and the first electric valve 24 is used to adjust the flue gas recirculation volume on the flue gas recirculation pipeline 21. By adjusting the flue gas recirculation volume, the oxygen content in the primary air can be reduced to reduce the generation of original NOx in the boiler.

[0051] The primary air system loop is used to supply fresh air to the primary air inlet. Exemplarily, the primary air system loop includes a primary air pipeline 31, a primary air fan 32, and a second electric valve 33. Among them, the primary air fan 32, the air preheater 14, and the second electric valve 33 are connected in series on the primary air pipeline 31. The primary air pipeline 31 is connected to the hydrogen burner, and the second electric valve 33 is used to adjust the primary cold air volume on the primary air pipeline 31.

[0052] The hydrogen fuel system loop is used to supply hydrogen fuel. Exemplarily, the hydrogen fuel system loop includes a green hydrogen production system 41, a hydrogen compressor 42, a hydrogen storage system 43, a second flow measurement device 44, and a third electric valve 45 connected in sequence. The second flow measurement device 44 is used to measure the hydrogen volume on the hydrogen fuel system loop, and the third electric valve 45 is connected to the hydrogen co-firing distribution valve group 5 to adjust the hydrogen volume on the hydrogen fuel system loop.

[0053] The first hydrogen burners 61 are evenly distributed at the original ignition air duct position of the boiler unit to ensure sufficient mixing of the hot flue gas and hot primary air after co-firing, and to ensure uniform primary air temperature and O2 content.

[0054] Except for the low-load stable combustion condition, a hydrogen co-firing system is arranged in the hot primary air duct for use in the rapid load increase condition of the boiler to improve the variable load rate of the boiler's deep peak shaving. During the boiler load increase condition, the primary fluidization air volume gradually increases, and the bed temperature shows a downward trend. At this time, the co-firing system proposed by the invention is used to increase the hydrogen co-firing volume in the hot primary air duct, quickly and evenly increase the hot primary air temperature, and increase the bed temperature rising rate, thereby increasing the boiler load increase rate.

[0055] In some embodiments, the hydrogen burner further includes a third hydrogen burner 63 disposed at the secondary air inlet of the furnace 11. During the rapid load increase stage of the boiler from the deep peak shaving operation condition, in addition to the first hydrogen burner 61 at the hot primary air duct being put into use to increase the temperature of the hot primary air, the third hydrogen burner 63 can also be arranged at the secondary air inlet to rapidly increase the combustion temperature level in the furnace and improve the load increase rate of the boiler.

[0056] The hydrogen co-firing distribution valve group 5 is used to adjust the amount of co-firing hydrogen entering the first hydrogen burner 61, the second hydrogen burner 62, and the third hydrogen burner 63, and the number of the first hydrogen burner 61, the second hydrogen burner 62, and the third hydrogen burner 63 is at least one. When the number of the first hydrogen burner 61, the second hydrogen burner 62, and the third hydrogen burner 63 is at least two, the hydrogen co-firing distribution valve group 5 includes a first main valve 51, a second main valve 52, a third main valve 53, a first branch valve group 54, a second branch valve group 55, and a third branch valve group 56. The first main valve 51 is connected to the first branch valve group 54, the second main valve 52 is connected to the second branch valve group 55, the third main valve 53 is connected to the third branch valve group 56, the first branch valve group 54 is communicated with the first hydrogen burner 61, the second branch valve group 55 is communicated with the second hydrogen burner 62, and the third branch valve group 56 is communicated with the third hydrogen burner 63. The three main valve groups are used to adjust the amount of hydrogen entering the first branch valve group 54, the second branch valve group 55, and the third branch valve group 56. The first branch valve group 54 is used to adjust the amount of co-firing hydrogen entering at least two first hydrogen burners 61, the second branch valve group 55 is used to adjust the amount of co-firing hydrogen entering at least two second hydrogen burners 62, and the third branch valve group 56 is used to adjust the amount of co-firing hydrogen entering at least two third hydrogen burners 63.

[0057] According to the actual flue gas temperature in the cyclone separator, the hydrogen co-firing distribution valve group 5 is used to control the amount of co-firing hydrogen entering the first hydrogen burner 61, the second hydrogen burner 62, and the third hydrogen burner 63. Taking the increase of the flue gas temperature in multiple hydrogen burners as the main control index and the increase of the return material temperature as the secondary index, the deep peak shaving and stable combustion capacity of the boiler unit is finally improved and the final ultra-low NOx emission is achieved. In addition to adjusting the bed temperature to improve the stable combustion capacity, the main and reheat steam temperatures of the low-load boiler can also be increased, thereby improving the power generation efficiency and operation safety of the unit under low-load conditions.

[0058] There are three aspects in the principle of arranging the second hydrogen burner 62 at the conical section of the separator 12: First, the conical section of the separator 12 is in a negative pressure state, and the flue gas mixing uniformity after hydrogen combustion is high, which can quickly and evenly increase the temperature of the coal-fired flue gas in the separator 12 to 750°C - 950°C, thereby greatly improving the SNCR denitration efficiency under low-load conditions, which is beneficial to improving the efficiency of the in-furnace SNCR denitration system 19 and achieving ultra-low NOx emission under deep peak shaving conditions.

[0059] Second, the concentration of ash adhering to the wall at the conical section is relatively high. The hydrogen jet co-firing can disturb the fine ash that has been separated by inertia and cause it to re-enter the central upflow of the separator 12 and fly out of the central cylinder, thereby reducing the efficiency of the cyclone separator, decreasing the return material quantity of the separator 12 under low-load conditions (the return material temperature is usually lower than the bed temperature), and further improving the bed temperature and stable combustion capacity of the boiler unit under low-load conditions.

[0060] Third, the co-firing at the conical section of the separator 12 can increase the flue gas temperature at the outlet of the separator 12, and also improve the heat transfer flow rate of the superheater and reheater heating surfaces in the tail flue, optimizing to a certain extent the problem of low main steam and reheated steam temperatures under deep load regulation conditions of large boiler units.

[0061] Therefore, there are two paths for the hydrogen co-firing system under deep load regulation and low-load conditions. After the green hydrogen is produced and stored, it is sent to the primary air duct and the conical section of the cyclone separator through hydrogen boosters for co-firing respectively. In order to adjust the hydrogen co-firing quantity at the two places, regulating valves are respectively arranged on the hydrogen delivery branch pipes, and regulating dampers are arranged on the hot primary air duct. By adjusting the opening degree of the hydrogen electric control valves at the two places, the co-firing gas quantity entering the hydrogen burners at the three places is adjusted.

[0062] Large boiler units above 300MW usually have 3, 4, or 6 cyclone separators. Limited by the differences in the flow field in the furnace, there are also large deviations in the flue gas temperatures between different separators 12 on the same boiler. By controlling the hydrogen gas quantity of the corresponding hydrogen burners / gas guns through the hydrogen valve groups at the conical sections of different separators 12, the temperature in the separators 12 at different temperature levels is increased to within the high-efficiency reaction temperature window of SNCR denitration.

[0063] Specifically, it includes the following steps:

[0064] The primary hot air temperature t1 (°C) before co-firing under deep load regulation conditions and the hot primary air temperature t2 (°C) after co-firing;

[0065] According to the empirical model, the hydrogen co-firing quantity z (10 4 Nm 3 / h), the primary cold air quantity x (10 4 Nm 3 / h), and the recirculating flue gas quantity y (10 4 Nm 3 / h) under 15% - 30% load conditions are calculated;

[0066] The calculated recirculating flue gas quantity y is used as the control set value of the flue gas system loop. The deviation from the actual flue gas recirculation quantity is passed through a PID controller to form a control signal, which acts on the flue gas system loop to achieve automatic control of the flue gas recirculation quantity;

[0067] Set the primary air temperature t2 after co - firing as the set value, and form a control signal through the PID controller by taking the deviation between the actual primary air temperature after co - firing and the set value, which acts on the hydrogen co - firing distribution valve group 5 to automatically control the hydrogen co - firing amount in the primary hot air duct.

[0068] In some embodiments, the empirical model includes:

[0069] 。

[0070] In some embodiments, the primary hot air temperature t1 (°C) before co - firing and the hot primary air temperature t2 (°C) after co - firing under deep - adjustment conditions include:

[0071] According to the bed temperature condition when burning the actual coal type under the low - load condition of the boiler, extract the primary hot air temperature t1 before co - firing from the historical curve, and set the target hot primary air temperature t2 after co - firing.

[0072] In some embodiments, the separator 12 is a cyclone separator, and the second hydrogen burner 62 is arranged at the conical section of the separator 12. Large - scale boiler units usually have multiple cyclone separators, and there are also large deviations in the flue gas temperature between different separators 12 on the same boiler. In this application, the second hydrogen burner 62 can be set at different separators 12 for hydrogen co - firing, and each hydrogen burner has an independent electric valve, which can independently adjust the flue gas temperature levels in multiple different separators 12 respectively, and all can be increased to the efficient reaction temperature window of SNCR denitration, which is 750 °C - 950 °C, avoiding the problem of low efficiency of a certain separator 12 and over - spraying of the reducing agent, and reducing the ammonia slip at the tail.

[0073] When only furnace combustion adjustment is carried out under deep - adjustment conditions and the boiler NOx cannot achieve ultra - low emissions under the condition of less than 20% load, first put into use the second hydrogen burner 62 at the separator 12, raise the temperature in the separator 12 to above 750 °C, and put into the SNCR denitration system 19 to further control NOx to reach the ultra - low emission standard through the SNCR denitration system 19.

[0074] In some embodiments, it also includes a hydrogen monitoring device 72 and a carbon monoxide monitoring device 71 arranged at the economizer 13, and when the monitored hydrogen content reaches a preset range, or when the monitored carbon monoxide content reaches a second preset range, increase the secondary air volume of the furnace 11 to avoid incomplete combustion.

[0075] The first hydrogen fuel burner, the second hydrogen burner 62, and the third hydrogen burner 63 can only be put into use after the necessary nitrogen replacement purge is completed. Among them, for the hydrogen co-firing at the second hydrogen burner 62 and the third hydrogen burner 63, it is only allowed to be put into use when the temperature level in the co-firing area is not lower than 600 °C, so as to ensure the rapid ignition and burnout of hydrogen fuel. The first hydrogen burner 61 arranged at the primary air inlet is ignited by a high-energy ignition device and put into use, and the air temperature during startup is not restricted.

[0076] See Figure 3 , this application also discloses a method for hydrogen co-firing in a boiler, including the following steps:

[0077] Step S1: Deeply adjust the primary hot air temperature t1 (°C) before co-firing under deep adjustment conditions, and the hot primary air temperature t2 (°C) after co-firing. Exemplarily, according to the low-load conditions of the boiler and the bed temperature situation when burning the actual coal type, extract the primary hot air temperature t1 before co-firing from the historical curve, and set the target hot primary air temperature t2 after co-firing.

[0078] Step S2: According to the empirical model, calculate the hydrogen co-firing amount z (10 4 Nm 3 / h), the primary cold air volume x (10 4 Nm 3 / h), and the recycled flue gas volume y (10 4 Nm 3 / h) under the 15% - 30% load condition;

[0079] Step S3: Take the calculated recycled flue gas volume y as the control set value of the flue gas system loop, make a deviation from the actual flue gas recirculation volume, and form a control signal through a PID controller to act on the flue gas system loop to realize the automatic control of the flue gas recirculation volume;

[0080] Step S4: Set the primary air temperature t2 after co-firing as the set value, make a deviation from the actual primary air temperature after co-firing, and form a control signal through a PID controller to act on the hydrogen co-firing distribution valve group 5 to automatically control the hydrogen co-firing amount in the primary hot air duct.

[0081] Aiming at the actual situations such as low bed temperature, insufficient stable combustion ability, low efficiency of the SNCR denitration system 19, and high low-carbon operation cost during the flexible deep peak shaving operation of large boiler units, the above-mentioned method for hydrogen co-firing in a boiler of this application solves the problems that limit the deep peak shaving depth of the boiler, such as low bed temperature and poor bed temperature uniformity, through the dynamic adjustment of the hot primary air temperature, the dynamic adjustment of the primary air oxygen content, and the adjustment of the return material temperature, which are related to the control of the in-furnace combustion bed temperature during the variable load operation of the deep peak shaving boiler unit.

[0082] In addition, by dynamically adjusting the flue gas temperature at the cyclone separator under the deep peak shaving condition, the problem of low efficiency of the SNCR denitration system 19 at the cyclone separator under low load conditions is solved. In this way, the ignition and burnout characteristics of hydrogen fuel are fully utilized. While dynamically adjusting the deep peak shaving combustion operation parameters of the boiler unit, the low-carbon operation of the CFB generator set is realized, and the economy and safety of the low-carbon peak shaving operation of the boiler unit are improved.

[0083] The purpose of setting up the hydrogen co-firing system loop is to reduce the carbon emission index of the unit through hydrogen co-firing, and at the same time, according to the needs of deep peak shaving for load increase and decrease, dynamically adjust the hot primary air temperature entering the furnace 11 and the flue gas temperature in different separators 12, so as to achieve stable combustion under the 15% load deep peak shaving condition of the boiler and ultra-low NOx compliance operation.

[0084] The above empirical model includes:

[0085] 。

[0086] Since the bed temperature of the current boiler unit decreases during low load operation, and the hot primary air temperature at the outlet of the air preheater is even lower (only about 50% - 60% of the hot primary air temperature under full load condition), it is not conducive to the bed temperature control of the boiler during low load operation. In this application, when the boiler needs to operate at 15% - 30% low load and quickly reduce the load, the high-temperature flue gas released by the first hydrogen burner set in the primary air port can be used to heat the hot primary air temperature, increase the hot primary air temperature to within 400°C, and finally the hot primary air is sent into the furnace 11 to participate in combustion, thereby increasing the bed temperature and stable combustion ability of the boiler unit during 15% - 30% deep peak shaving low load operation.

[0087] The hydrogen co-firing in the primary air port of this application can also reduce the oxygen content in the primary air under deep peak shaving conditions, thereby reducing the power of the flue gas recirculation fan 22 and lowering the investment cost of the flue gas recirculation system.

[0088] See Figure 4 This application also discloses a method for hydrogen co-firing in a boiler, including:

[0089] Under the condition that the boiler unit operates at 15% - 30% low load and quickly reduces the load, it includes step S10: heating the hot primary air temperature to within 400°C by using the high-temperature flue gas released by the first burner set at the primary air port. Finally, the hot primary air is sent into the fluidized air chamber to participate in combustion, thereby increasing the bed temperature of the boiler unit during 15% - 30% load deep peak shaving low load operation and improving the stable combustion ability of the boiler.

[0090] When the boiler NOx cannot achieve ultra-low emissions under the condition of adjusting the load below 20% only through in-furnace combustion adjustment in the deep adjustment condition, it includes step S20: using the high-temperature flue gas released by the combustion of the second hydrogen burner 62 arranged at the separator to increase the temperature in the separator 12 to above 750 °C. Put into the SNCR denitration system 19, and further control NOx to reach the ultra-low emission standard through the SNCR denitration system 19.

[0091] In addition, when the boiler unit operates under the low load condition of 15% - 30%, the SNCR denitration system 19 arranged at the separator 12 has been lower than 650 °C. In order to achieve ultra-low NOx emissions in the deep adjustment condition, the present invention proposes to arrange a second hydrogen burner 62 at the conical section of the separator 12. According to the actual flue gas temperature in the separator 12, through the hydrogen blending distribution valve group 5, the amount of hydrogen for blending into the conical section of the separator 12 is regulated to increase the flue gas temperature and the return material temperature in the separator 12, indirectly increasing the bed temperature during operation under the low load condition, and finally improving the stable combustion ability and ultra-low NOx emissions of the boiler unit in the deep adjustment condition.

[0092] Above, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features.

[0093] Among them, in the description of the embodiments of the present application, unless otherwise specified, " / " means "or". For example, A / B may mean A or B; herein, "and / or" is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, and B exists alone.

[0094] It should be noted that for the convenience of description, only the parts related to the relevant application are shown in the drawings. Without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0095] The above description is only a preferred embodiment of the present application and an explanation of the applied technical principles, and is not used to limit the present application. For those skilled in the art, the present application can have various changes and modifications. The scope of the application involved in the present application is not limited to the technical solutions formed by the specific combination of the above technical features, and should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the above application concept. For example, the technical solutions formed by mutually replacing the above features with the (but not limited to) technical features with similar functions disclosed in the present application.

Claims

1. A boiler hydrogen co-firing system, characterized in that, It includes a boiler unit, a flue gas system loop, a primary air system loop, a hydrogen fuel system loop and a hydrogen co-firing distribution valve group. The flue gas system loop is communicated with the primary air system loop. The primary air system loop is communicated with the hydrogen burner of the boiler unit. The hydrogen fuel system loop is communicated with at least two hydrogen burners of the boiler unit through the hydrogen co-firing distribution valve group to regulate the co-firing gas volume entering the hydrogen burners. At least two of the hydrogen burners include a first hydrogen burner arranged at the primary air inlet of the furnace of the boiler unit and a second hydrogen burner arranged at the separator of the boiler unit.

2. The boiler hydrogen co-firing system according to claim 1, wherein, The boiler unit includes a furnace, a separator, a economizer, an air preheater, a dust collector, a desulfurization system, an induced draft fan and a chimney connected in sequence, and a denitration system is arranged at the top of the furnace. and / or The flue gas system loop includes a flue gas recirculation pipeline, a flue gas recirculation fan, a first flow measurement device and a first electric valve. The flue gas recirculation fan, the first flow measurement device and the first electric valve are connected in series on the flue gas recirculation pipeline. One end of the flue gas recirculation pipeline is communicated with the induced draft fan, and the other end of the flue gas recirculation pipeline is communicated with the primary air system loop. The first flow measurement device is used to measure the flue gas recirculation volume on the flue gas recirculation pipeline, and the first electric valve is used to adjust the flue gas recirculation volume on the flue gas recirculation pipeline. and / or The primary air system loop includes a primary air pipeline, a primary air fan and a second electric valve. Among them, the primary air fan, the air preheater and the second electric valve are connected in series on the primary air pipeline. The primary air pipeline is communicated with the hydrogen burner, and the second electric valve is used to adjust the primary cold air volume on the primary air pipeline. and / or The hydrogen fuel system loop includes a green hydrogen production system, a hydrogen compressor, a hydrogen storage system, a second flow measurement device and a third electric valve connected in sequence. The second flow measurement device is used to measure the hydrogen volume on the hydrogen fuel system loop, and the third electric valve is connected to the hydrogen co-firing distribution valve group to adjust the hydrogen volume on the hydrogen fuel system loop.

3. The boiler hydrogen co-firing system according to claim 2, characterized in that, The hydrogen burner further includes a third hydrogen burner arranged at the secondary air inlet of the furnace.

4. The boiler hydrogen co-firing system according to claim 3, characterized in that, The first hydrogen burner, the second hydrogen burner and the third hydrogen burner include at least two hydrogen burners. The hydrogen co-firing distribution valve group includes a first main valve, a second main valve, a third main valve, a first branch valve group, a second branch valve group and a third branch valve group. The first main valve group is connected to the first branch valve group, the second main valve is connected to the second branch valve group, the third main valve is connected to the third branch valve group. The first branch valve group is communicated with the first hydrogen burner, the second branch valve group is communicated with the second hydrogen burner, and the third branch valve group is communicated with the third hydrogen burner.

5. The boiler hydrogen co-firing system according to claim 4, characterized in that, The separator is a cyclone separator, and the second hydrogen burner is arranged at the conical section of the separator.

6. The boiler hydrogen co-firing system according to claim 5, characterized in that, It further includes a hydrogen monitoring device and a carbon monoxide monitoring device disposed at the economizer, and when the monitored hydrogen content reaches a preset range or the monitored carbon monoxide content reaches a second preset range, the secondary air volume of the furnace is increased.

7. A method for controlling hydrogen co-firing in a boiler, characterized in that, It includes the following steps: The primary hot air temperature t1 (°C) before co-firing under deep adjustment conditions and the hot primary air temperature t2 (°C) after co-firing; According to the empirical model, the hydrogen injection amount z (10 4 Nm 3 / h), the primary cold air volume x (10 4 Nm 3 / h) and the recirculating flue gas volume y (10 4 Nm 3 / h) under the load condition of 15% - 30% are calculated; Taking the calculated circulating flue gas volume y as the control set value of the flue gas system loop, making a deviation from the actual flue gas recirculation volume, and forming a control signal through a PID controller to act on the flue gas system loop to achieve automatic control of the flue gas recirculation volume; Setting the primary air temperature t2 after co-firing as the set value, making a deviation from the actual primary air temperature after co-firing, and forming a control signal through a PID controller to act on the hydrogen co-firing distribution valve group for automatically controlling the hydrogen co-firing amount in the primary hot air duct.

8. The control method according to claim 7, wherein The empirical model includes: 。 9. The control method according to claim 8, wherein The primary hot air temperature t1 (°C) before co-firing under deep adjustment conditions and the hot primary air temperature t2 (°C) after co-firing include: According to the bed temperature condition when burning the actual coal type under the low load condition of the boiler, extracting the primary hot air temperature t1 before co-firing from the historical curve and setting the target hot primary air temperature t2 after co-firing.

10. A method for co-firing hydrogen in a boiler, characterized in that, It includes the following steps: Under the conditions of the boiler unit operating at a low load of 15% - 30% and rapid load reduction operation, heating the hot primary air temperature to within 400 °C by the high-temperature flue gas released by the first burner disposed at the primary air outlet; When the ultra-low emission of NOx in the boiler cannot be achieved under the condition of 20% load or below only through in-furnace combustion adjustment in the deep adjustment condition, raising the temperature in the separator to above 750 °C by the high-temperature flue gas released by the second hydrogen burner disposed at the separator.

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