Air volume control method for coal-fired boiler system and coal-fired boiler system

Abstract

The present invention provides an air volume control method for a coal-fired boiler system and a coal-fired boiler system. The air volume control method comprises: when a CO concentration detection value is greater than a first preset concentration value, reducing the secondary air intake of the burnout area of the furnace and increasing the secondary air intake of the main combustion area; when the secondary air intake of the burnout area is reduced to a first preset air volume value, and when the CO concentration detection value is greater than the first preset concentration value, increasing the total amount of secondary air intake; when the CO concentration detection value is less than a second preset concentration value, increasing the secondary air intake of the burnout area and reducing the secondary air intake of the main combustion area; controlling the O2 concentration detection value within the first preset concentration range, and reducing the NO x The concentration detection value is controlled within a second preset concentration range. The air volume control method of the present application is used to solve the technical problem of inaccurate regulation and control of the burnout air volume of coal-fired boilers in the prior art.

Description

Technical Field

[0001] The present invention relates to the technical field of coal-fired boilers, and in particular to an air volume control method for a coal-fired boiler system and a coal-fired boiler system. Background Art

[0002] In order to control NO x The combustion system generally adopts staged combustion technology, which divides the air required in the combustion process into two parts. An overburn air burner is set above the main burner at a certain distance to provide supplementary combustion air for the pulverized coal after it is burned in the furnace, so as to realize the oxygen-deficient and over-oxygen combustion of the pulverized coal in the furnace, and provide oxygen for the unburned gas and carbon particles in the main burner area to realize re-combustion, thereby improving the combustion efficiency of the boiler and achieving the goal of controlling NO x While discharging, the combustion efficiency in the boiler will not be too low.

[0003] At present, the main method is to divert the flow from the large secondary air box to the small separate burnout air box, and set an air volume measuring device, a pressure sensor and an adjusting damper on the air duct between the small air box and the burnout air burner. During operation, the air volume fed into the burnout air burner is mainly adjusted by adjusting the opening of the adjusting damper. Since the large secondary air box and the small separate burnout air box corresponding to the main burner are connected together, the total air supply volume of the boiler is controlled by adjusting the boiler blower. When the air volume of the main burner is adjusted, the air volume and air pressure of the separate burnout air will be affected. Therefore, the flow rate of the separate combustion air cannot be accurately adjusted and controlled during operation, and the accurate amount of supplementary oxygen cannot be provided to the products after staged combustion. The combustion air flow organization in the furnace cannot meet the expected design conditions, affecting the combustion efficiency, pollutant emissions and boiler efficiency.

[0004] In addition, the air volume measuring device installed on the small wind box of the overburnt air is difficult to meet the installation requirements due to the limited on-site layout space, which greatly reduces the measurement accuracy of the air volume measuring device and cannot meet the requirements for separate combustion air regulation and control during boiler operation. Operators usually use it as a monitoring reference value and cannot use it as a basis for controlling overburnt air regulation. Or, based on experimental experience data, the overburnt air regulation damper is basically not adjusted during operation.

[0005] In order to further strictly control NO xEmissions, generally operate with a lower oxygen content, resulting in a low overall oxygen content in the furnace. When the air volume coordination and organization of the main burner area and the separate burnout air burner area are unreasonable, a large amount of reducing atmosphere is generated in the furnace. For example, in the upper area of the separate air burner, a high concentration of reducing gas contacts the water-cooled wall for a long time, which will cause high-temperature corrosion of the water-cooled wall, metal corrosion and peeling of the outer wall of the water-cooled wall, and a decrease in mechanical strength, endangering the safe operation of the heating surface.

[0006] After the pulverized coal boiler was modified for ultra-low emission, a large area of high-temperature corrosion of the water-cooled wall appeared. This problem is quite common, especially in the pulverized coal boiler with front and rear wall facing each other. Due to the location of the burner, the side wall water-cooled wall is more prone to hypoxia, and the high-temperature corrosion problem is more serious. An important reason for the high-temperature corrosion is that the boiler cannot accurately control the flow rate of the separated burnout air, and does not adjust the air supply volume at each level according to the designed graded air distribution method. The reducing gas generated does not react with oxygen in time. Another reason is that there is a lack of judgment parameters for the size of the burnout air volume during boiler operation. Currently, the NO at the inlet of the SCR reactor is mainly used to determine the size of the burnout air volume. x The flow between this position and the furnace is long, and the flue gas is mixed during the heat exchange process of the tail convection heating surface, which cannot timely and accurately feedback the combustion situation inside the boiler, or NO x The concentration feedback is a relatively macroscopic furnace combustion condition, and cannot feedback the local combustion condition. Summary of the Invention

[0007] The main purpose of the present invention is to provide an air volume control method for a coal-fired boiler system and a coal-fired boiler system, so as to solve the technical problem of inaccurate adjustment and control of the burnout air volume of coal-fired boilers in the prior art.

[0008] In order to achieve the above object, according to one aspect of the present invention, a method for controlling the air volume of a coal-fired boiler system is provided, which comprises: detecting the O2 concentration value and NO2 concentration value of the flue gas in the tail flue; x Concentration value to obtain O2 concentration detection value and NO xConcentration detection value; detecting the concentration value of CO generated in the furnace during the combustion process to obtain the CO concentration detection value; judging whether the CO concentration detection value is greater than a first preset concentration value, and judging whether the CO concentration detection value is less than a second preset concentration value, the second preset concentration value is less than the first preset concentration value; when the CO concentration detection value is greater than the first preset concentration value, reducing the secondary air intake of the overburnt air burner in the burnout area of the furnace, and increasing the secondary air intake of the main burner in the main combustion area; when the secondary air intake of the overburnt air burner in the burnout area is reduced to the first preset air intake value, and when CO When the concentration detection value is still greater than the first preset concentration value, the total amount of secondary air intake is increased, and the total amount of secondary air intake is the sum of the secondary air intake of the main combustion area and the secondary air intake of the burnout area; when the CO concentration detection value is less than the second preset concentration value, the secondary air intake of the burnout air burner in the burnout area is increased, and the secondary air intake of the main burner in the main combustion area is reduced; wherein, in the process of adjusting the secondary air intake of the burnout area of the furnace, the secondary air intake of the main combustion area, and the total amount of secondary air intake, the O2 concentration detection value is controlled within the first preset concentration range, and NO x The concentration detection value is controlled within a second preset concentration range.

[0009] Furthermore, the main combustion area includes a plurality of first sub-areas sequentially arranged along the horizontal circumference of the furnace, and each first sub-area is provided with a main burner; the burnout area includes a plurality of second sub-areas sequentially arranged along the horizontal circumference of the furnace, and each second sub-area is provided with an overburnt air burner, and the plurality of second sub-areas are arranged in a one-to-one correspondence with the plurality of first sub-areas, and each second sub-area is located above the corresponding first sub-area in the vertical direction; the air volume control method includes: detecting the concentration value of CO generated in each first sub-area during the combustion process to obtain a corresponding zoned CO concentration detection value; judging whether the CO concentration detection value of each zone is greater than a first preset concentration value, and judging whether the CO concentration detection value of each zone is less than a second preset concentration value; when each zoned CO When the concentration detection value is greater than the first preset concentration value, the secondary air intake of the overburnt air burner of the corresponding second sub-area is reduced, and the secondary air intake of the main burner of the corresponding first sub-area is increased; when the secondary air intake of the main burner of the first sub-area is reduced to the first preset air volume value, and when the CO concentration detection value of the first sub-area is still greater than the first preset concentration value, the total secondary air intake of the corresponding partition is increased, and the sum of the secondary air intake of each first sub-area and the secondary air intake of the corresponding second sub-area is the total secondary air intake of the corresponding partition; when the CO concentration detection value of each partition is less than the second preset concentration value, the secondary air intake of the overburnt air burner of the corresponding second sub-area is increased, and the secondary air intake of the main burner of the corresponding first sub-area is reduced.

[0010] Furthermore, the air volume control method further includes: when NO x The concentration value is greater than the upper limit of the second preset concentration range, and when the secondary air intake volume of the burnout area is its maximum intake volume, the total secondary air intake volume is reduced.

[0011] According to another aspect of the present invention, a coal-fired boiler system is provided, which includes a furnace, a tail flue, a main burner air volume adjustment device and an overburner air volume adjustment device, the furnace including a main combustion area and a burnout area located vertically above the main combustion area, a main burner is provided in the main combustion area, and an overburner air burner is provided in the burnout area; the main burner air volume adjustment device is used to control the secondary air intake volume of the main burner in the main combustion area, and the overburner air volume adjustment device is used to control the secondary air intake volume of the overburner air burner in the burnout area; the tail flue is connected to the smoke exhaust port of the furnace to discharge the smoke generated by the combustion in the furnace through the tail flue; the coal-fired boiler system also includes: a CO measuring device, the CO measuring device is arranged between the main combustion area and the burnout area in the vertical direction, at least part of the CO measuring device is arranged in the furnace to detect the CO concentration value generated in the furnace during the combustion process; an O2 measuring device, at least part of the O2 measuring device is arranged in the tail flue to detect the O2 concentration value of the flue gas in the tail flue; NO x Measuring device, NO x At least part of the measuring device is arranged in the tail flue to detect the NO x Concentration value.

[0012] Furthermore, the coal-fired boiler system also includes: a secondary air inlet main pipeline; a first branch pipeline and a second branch pipeline, the first pipe opening of the first branch pipeline and the first pipe opening of the second branch pipeline are both connected and communicated with the second pipe opening of the secondary air inlet main pipeline; the air inlet of the main burner in the main combustion area is communicated with the second pipe opening of the first branch pipeline, and the air volume regulating device of the main burner is arranged on the first branch pipeline; the air inlet of the burnout air burner in the burnout area is communicated with the second pipe opening of the second branch pipeline, and the air volume regulating device of the burnout air burner is arranged on the second branch pipeline.

[0013] Furthermore, there are multiple CO measuring devices, which are arranged in a one-to-one correspondence with the multiple first sub-regions, and each CO measuring device is used to detect the concentration value of CO generated by the combustion of the main burner in the corresponding first sub-region.

[0014] Furthermore, the furnace has four side walls and four corners, and there are four main burners and four CO measuring devices. The four main burners are arranged one-to-one at the four corners of the furnace, and the four CO measuring devices are arranged one-to-one on the four side walls of the furnace.

[0015] Furthermore, the furnace has four side walls, and there are four main burners and four CO measuring devices. The four main burners are arranged one by one on the four side walls of the furnace, and the four CO measuring devices are arranged one by one on the four side walls of the furnace. The main burners and CO measuring devices on each side wall of the furnace are arranged at intervals in the horizontal direction.

[0016] Furthermore, the furnace has four side walls, and the four side walls of the furnace include two first designated side walls arranged opposite to each other and two second designated side walls arranged opposite to each other; the multiple main burners are divided into two groups, and each group of main burners includes multiple main burners; the two groups of main burners are arranged in a one-to-one correspondence with the two first designated side walls, and the multiple main burners in each group are all arranged on the corresponding first designated side walls; the multiple CO measuring devices are divided into two groups, and each group of CO measuring devices includes two CO measuring devices; the two groups of CO measuring devices are arranged in a one-to-one correspondence with the two second designated side walls, and the two CO measuring devices in each group are all arranged on the corresponding second designated side walls.

[0017] Furthermore, a burnt air volume measuring device is provided on the second branch pipeline.

[0018] Applying the technical solution of the present invention, the air volume control method includes: detecting the O2 concentration value and NO x Concentration value to obtain O2 concentration detection value and NO x Concentration detection value, that is, the O2 concentration value of the flue gas in the tail flue is the O2 concentration detection value, the NO x The concentration value is NO xConcentration detection value: Detecting the CO concentration generated in the furnace during combustion to obtain a CO concentration detection value, i.e., the detected CO concentration generated in the furnace during combustion is the CO concentration detection value. Determining whether the CO concentration detection value is greater than a first preset concentration value, and determining whether the CO concentration detection value is less than a second preset concentration value, wherein the second preset concentration value is less than the first preset concentration value. When the CO concentration detection value is greater than the first preset concentration value, the CO concentration in the main combustion zone is high, and the secondary air intake of the overburned air burner in the burnout zone of the furnace is reduced, while the secondary air intake of the main burner in the main combustion zone is increased. When the secondary air intake of the overburned air burner in the burnout zone decreases to the first preset air intake value, and the CO concentration detection value is still greater than the first preset concentration value, the total secondary air intake is increased; wherein the total secondary air intake is the sum of the secondary air intake of the main combustion zone and the secondary air intake of the burnout zone. When the CO concentration detection value is less than the second preset concentration value, the CO concentration in the main combustion zone is low, and the secondary air intake of the overburned air burner in the burnout zone is increased, while the secondary air intake of the main burner in the main combustion zone is reduced. In the process of adjusting the secondary air inlet volume of the burnout area of the furnace, the secondary air inlet volume of the main combustion area, and the total secondary air inlet volume, the O2 concentration detection value is controlled within the first preset concentration range, and the NO x The concentration detection value is controlled within the second preset concentration range to achieve NO x Concentration control: The air volume control method of the present application is used to solve the technical problem of inaccurate adjustment and control of the burnout air volume of coal-fired boilers in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0020] Figure 1 It shows a schematic structural diagram of a coal-fired boiler system according to the present invention;

[0021] Figure 2 A schematic structural diagram of a tail flue of a coal-fired boiler system according to the present invention is shown;

[0022] Figure 3 A schematic diagram showing a first arrangement of multiple CO measuring devices in a coal-fired boiler system according to the present invention;

[0023] Figure 4 A schematic diagram showing a second arrangement of multiple CO measuring devices of a coal-fired boiler system according to the present invention;

[0024] Figure 5A schematic diagram showing a third arrangement of multiple CO measuring devices in a coal-fired boiler system according to the present invention.

[0025] The above drawings include the following reference numerals:

[0026] 10. Main burner; 11. Main burner air volume adjustment device; 20. Overburn air burner; 21. Overburn air volume measurement device; 22. Overburn air burner air volume adjustment device; 31. Blower; 32. Air preheater; 33. Secondary air volume measurement device; 40. CO measurement device; 50. Tail flue; 501. Horizontal flue section; 51. O2 measurement device; 52. NO x Measuring device; 53. Economizer; 54. SCR reactor; 60. Furnace; 71. Secondary air inlet main pipeline; 72. First branch pipeline; 73. Second branch pipeline. DETAILED DESCRIPTION

[0027] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0028] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0029] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0030] The present invention provides a method for controlling the air volume of a coal-fired boiler system. Figures 1 to 5 The air volume control method includes: detecting the O2 concentration value and NO x Concentration value to obtain O2 concentration detection value and NO x Concentration detection value, that is, the O2 concentration value of the flue gas in the tail flue 50 is detected, the NO concentration of the flue gas in the tail flue 50 is detected. x The concentration value is NO xConcentration detection value: Detect the concentration of CO generated in the furnace 60 during the combustion process to obtain a CO concentration detection value, that is, the concentration of CO generated in the furnace 60 during the combustion process is the CO concentration detection value. Determine whether the CO concentration detection value is greater than a first preset concentration value, and determine whether the CO concentration detection value is less than a second preset concentration value, where the second preset concentration value is less than the first preset concentration value. When the CO concentration detection value is greater than the first preset concentration value, the CO concentration in the main combustion area is high, and the secondary air intake of the overburnt air burner 20 in the burnout area of the furnace 60 is reduced, and the secondary air intake of the main burner 10 in the main combustion area is increased. When the secondary air intake of the overburnt air burner 20 in the burnout area is reduced to the first preset air intake value, and when the CO concentration detection value is still greater than the first preset concentration value, increase the total secondary air intake; wherein the total secondary air intake is the sum of the secondary air intake of the main combustion area and the secondary air intake of the burnout area. When the CO concentration detection value is less than the second preset concentration value, the CO concentration in the main combustion area is low, and the secondary air intake of the burnout air burner 20 in the burnout area is increased, and the secondary air intake of the main burner 10 in the main combustion area is reduced. In the process of adjusting the secondary air intake of the burnout area of the furnace 60, the secondary air intake of the main combustion area, and the total secondary air intake, the O2 concentration detection value is controlled within the first preset concentration range, and NO x The concentration detection value is controlled within the second preset concentration range to achieve NO x Concentration control: The air volume control method of the present application is used to solve the technical problem of inaccurate adjustment and control of the burnout air volume of coal-fired boilers in the prior art.

[0031] Specifically, the nozzles of the main burner 10 and the nozzles of the over-combustion air burner 20 are both arranged toward the interior of the furnace 60 .

[0032] It should be noted that NO x For nitrogen oxides.

[0033] The air volume control method of the coal-fired boiler system of the present application uses the CO concentration detection value as the main reference variable for controlling the secondary air inlet volume of the overburnt air burner 20 in the burnt area, and combines the reference O2 concentration detection value and NO x The concentration detection value is used to accurately adjust and control the secondary air inlet volume of the burnout area, and then optimize the secondary air distribution of the boiler under different operating conditions and loads to optimize the combustion in the furnace 60, thereby achieving NO while achieving economical combustion of the boiler. x Effective emission control achieves economical, safe, and environmentally friendly combustion. In addition, it can prevent high-temperature corrosion in the furnace 60. The CO concentration detection value can indirectly reflect whether the distribution of secondary air volume is reasonable.

[0034] It should be noted that increasing the total amount of secondary air intake will inevitably increase the O2 concentration detection value. In the specific implementation, an O2 set value is set and used as a reference value to determine the total amount of secondary air intake. During the control process, the O2 set value is corrected based on the O2 concentration detection value.

[0035] It should be noted that the CO concentration after coal combustion is used to reflect the combustion efficiency of the coal powder in the furnace 60, especially the CO content in the water-cooled wall area above the burnout area is relatively high, and the real-time change of the CO content is rapid and the change amount is large. The CO concentration is an important parameter reflecting whether the staged combustion air distribution in the furnace 60 is reasonable. It can be directly used as a reference value to adjust and control the secondary air volume sent to the burnout area, thereby realizing the distribution ratio of the secondary air volume sent to the burnout area and the secondary air volume sent to the main combustion area, as well as the total amount of secondary air intake, so as to effectively solve the high-temperature corrosion problem of the water-cooled wall.

[0036] Specifically, when the main combustion area is provided with one main burner 10, the CO concentration detection value refers to the concentration value of CO generated by the combustion of the main burner 10, and the secondary air intake volume of the main combustion area refers to the secondary air intake volume provided to the main burner 10; when the main combustion area is provided with multiple main burners 10, the CO concentration detection value refers to the concentration value of CO generated by the combustion of multiple main burners 10, and the secondary air intake volume of the main combustion area refers to the secondary air intake volume provided to multiple main burners 10.

[0037] Specifically, each main burner 10 is configured to correspond to one overburned air burner 20, i.e., each overburned air burner 20 is vertically disposed above the corresponding main burner 10. When the main combustion area is provided with one main burner 10, the overburned air burner 20 is also disposed in the overburned air area. In this case, the secondary air intake of the overburned air area refers to the secondary air intake provided to the overburned air burner 20. When the main combustion area is provided with multiple main burners 10, the overburned air burner 20 is also disposed in the overburned air area. In this case, the secondary air intake of the overburned air area refers to the secondary air intake provided to the multiple overburned air burners 20.

[0038] Optionally, when the main combustion area is provided with multiple main burners 10, the multiple main burners 10 in the main combustion area are arranged at intervals along the horizontal circumference of the furnace 60; at this time, the burnout area must be provided with multiple burnout air burners 20, and the multiple burnout air burners 20 in the burnout area are arranged at intervals along the horizontal circumference of the furnace 60.

[0039] In this embodiment, the air volume control method further includes: when NO xThe concentration value is greater than the upper limit of the second preset concentration range, and when the secondary air intake volume of the burnout area is its maximum intake volume, the total secondary air intake volume is reduced.

[0040] The present invention also provides a coal-fired boiler system, such as Figures 1 to 5 As shown, the coal-fired boiler system is applicable to the air volume control method of the present application. The coal-fired boiler system includes a furnace 60, a tail flue 50, a main burner air volume regulating device 11 and a burnout air burner air volume regulating device 22. The furnace 60 includes a main combustion area and a burnout area located vertically above the main combustion area. A main burner 10 is arranged in the main combustion area, and a burnout air burner 20 is arranged in the burnout area; the main burner air volume regulating device 11 is used to control the secondary air intake volume of the main burner 10 in the main combustion area, and the burnout air burner air volume regulating device 22 is used to control the secondary air intake volume of the burnout air burner 20 in the burnout area; the tail flue 50 is connected to the smoke exhaust port of the furnace 60 to discharge the smoke generated by the combustion in the furnace 60 through the tail flue 50.

[0041] Specifically, the secondary air intake volume of the main burner 10 in the main combustion area is controlled by adjusting the opening size of the main burner air volume regulating device 11; the secondary air intake volume of the burnt-out air burner 20 in the burnt-out area is controlled by adjusting the opening size of the burnt-out air volume regulating device 22.

[0042] In this embodiment, the coal-fired boiler system further includes a CO measuring device 40, an O2 measuring device 51 and a NO x The CO measuring device 52 and the CO measuring device 40 are arranged vertically between the main combustion area and the burnout area. At least a portion of the CO measuring device 40 is arranged in the furnace 60 to detect the CO concentration value generated in the furnace 60 during the combustion process through the CO measuring device 40; at least a portion of the O2 measuring device 51 is arranged in the tail flue 50 to detect the O2 concentration value of the flue gas in the tail flue 50 through the O2 measuring device 51; NO x At least part of the measuring device 52 is arranged in the tail flue 50 to measure the NO x The measuring device 52 detects the NO in the flue gas in the tail flue 50. x Concentration value.

[0043] Specifically, the CO measuring device 40 is installed on the water-cooled wall of the furnace 60 .

[0044] Specifically, along the exhaust direction of the flue gas in the tail flue 50, the O2 measuring device 51 is located at the NO x Upstream of the measuring device 52 .

[0045] Specifically, the tail flue 50 includes a horizontal flue section 501 , and the O 2 measuring device 51 is located on the horizontal flue section 501 .

[0046] It should be noted that the CO measuring device 40 is kept at a certain distance from the main burner 10 to prevent the CO measuring device 40 from detecting the CO existing before combustion. That is, the CO measuring device 40 is mainly used to detect the CO generated by the main burner 10 when the secondary air distribution or the total secondary air volume control is unreasonable. x The concentration detection value is negatively correlated with the CO concentration detection value. In order to control the NO x Regarding emissions, the existing technology often uses a low excess air coefficient, that is, the total air volume of the boiler is controlled too low, which will cause the combustion in the furnace to produce a large amount of CO. The generated CO causes high-temperature corrosion to the water-cooled wall, resulting in a decrease in strength after the water-cooled wall is thinned, and leakage accidents occur.

[0047] It should be noted that, by setting up a CO measuring device 40, the concentration of CO generated in the furnace 60 during the combustion process is detected in real time. This is used as the main reference value to adjust and accurately control the distribution ratio of the secondary air volume sent to the burnout area and the secondary air volume sent to the main combustion area, as well as the total amount of secondary air intake in real time. Therefore, while ensuring the combustion efficiency in the furnace 60, high-temperature corrosion of the water-cooled wall is avoided and NOx emissions are kept within a reasonable range.

[0048] In this embodiment, the coal-fired boiler system also includes a secondary air inlet main pipeline 71, a first branch pipeline 72 and a second branch pipeline 73, and the first pipe opening of the secondary air inlet main pipeline 71 is its air inlet; the first branch pipeline 72 and the second branch pipeline 73 are arranged in parallel, and the first pipe opening of the first branch pipeline 72 and the first pipe opening of the second branch pipeline 73 are both connected and communicated with the second pipe opening of the secondary air inlet main pipeline 71; the air inlet of the main burner 10 in the main combustion area is communicated with the second pipe opening of the first branch pipeline 72, and the main burner air volume regulating device 11 is arranged on the first branch pipeline 72; the air inlet of the burnout air burner 20 in the burnout area is communicated with the second pipe opening of the second branch pipeline 73, and the burnout air burner air volume regulating device 22 is arranged on the second branch pipeline 73. That is, a part of the secondary air in the secondary air inlet main pipeline 71 is provided to the main burner 10 in the main combustion area through the first branch pipeline 72, and the other part is provided to the burnout air burner 20 in the burnout area through the second branch pipeline 73. The main burner air volume regulating device 11 is used to control the secondary air inlet volume of the main combustion area, and the burnout air burner air volume regulating device 22 is used to control the secondary air inlet volume of the burnout area.

[0049] Specifically, a burnt air volume measuring device 21 is provided on the second branch pipeline 73 , and the burnt air volume measuring device 21 is used to detect the secondary air volume of the burnt air burner 20 sent into the burnt area.

[0050] In this embodiment, the main combustion area includes a plurality of first sub-areas arranged in sequence along the horizontal circumference of the furnace 60, and each first sub-area is provided with a main burner 10; the burnout area includes a plurality of second sub-areas arranged in sequence along the horizontal circumference of the furnace 60, and each second sub-area is provided with a burnout air burner 20. The plurality of second sub-areas are arranged in one-to-one correspondence with the plurality of first sub-areas, and each second sub-area is located above the corresponding first sub-area in the vertical direction.

[0051] Specifically, the air volume control method includes: detecting the CO concentration value generated in each first sub-region during the combustion process to obtain a corresponding sub-region CO concentration detection value, that is, the detected CO concentration value generated in each first sub-region is the corresponding sub-region CO concentration detection value. Determining whether each sub-region CO concentration detection value is greater than a first preset concentration value, and determining whether the sub-region CO concentration detection value is less than a second preset concentration value. When each sub-region CO concentration detection value is greater than the first preset concentration value, reducing the secondary air intake of the overfire air burner 20 in the corresponding second sub-region, and increasing the secondary air intake of the main burner 10 in the corresponding first sub-region. When the secondary air intake of the main burner 10 in the first sub-region is reduced to the first preset air intake value, and when the CO concentration detection value of the first sub-region is still greater than the first preset concentration value, increasing the total secondary air intake of the corresponding sub-region, and the sum of the secondary air intake of each first sub-region and the secondary air intake of the corresponding second sub-region is the total secondary air intake of the corresponding sub-region. When the CO concentration detection value of each zone is less than the second preset concentration value, the secondary air intake of the overburned air burner 20 of the corresponding second zone is increased, and the secondary air intake of the main burner 10 of the corresponding first zone is reduced. In the process of adjusting the secondary air intake of each second zone, the secondary air intake of each first zone, and the total secondary air intake of each zone, the O2 concentration detection value is controlled within the first preset concentration range, and the NO x The concentration detection value is controlled within the second preset concentration range, which can achieve further precise control of the secondary air distribution.

[0052] Specifically, when each first sub-area is provided with a main burner 10, the corresponding partitioned CO concentration detection value refers to the concentration value of CO produced by the combustion of a main burner 10 in the first sub-area, and the secondary air intake volume of the first sub-area refers to the secondary air intake volume provided to this main burner 10; at this time, the corresponding second sub-area must be provided with a burnout air burner 20, and the secondary air intake volume of the second sub-area refers to the secondary air intake volume provided to this burnout air burner 20.

[0053] When each first sub-area is provided with a plurality of main burners 10, the corresponding partitioned CO concentration detection value refers to the concentration value of CO produced by the combustion of the plurality of main burners 10 in the first sub-area, and the secondary air intake volume of the first sub-area refers to the secondary air intake volume provided to the plurality of main burners 10 in the first sub-area; at this time, the second sub-area must be provided with a plurality of overburnt air burners 20, and the secondary air intake volume of the second sub-area refers to the secondary air intake volume provided to the plurality of overburnt air burners 20 in the second sub-area.

[0054] Specifically, there are multiple CO measuring devices 40, and the multiple CO measuring devices 40 are arranged at horizontal circumferential intervals along the furnace 60; the multiple CO measuring devices 40 are arranged one-to-one corresponding to the multiple first sub-regions, and each CO measuring device 40 is used to detect the concentration value of CO generated by the combustion of the main burner 10 in the corresponding first sub-region.

[0055] For example, the furnace 60 has four side walls and four corners, and the first arrangement of the multiple CO measuring devices 40 is as follows: Figure 3 As shown, there are four main burners 10 and four CO measuring devices 40. The four main burners 10 are arranged one by one at the four corners of the furnace 60 to form four-corner tangential combustion; the four CO measuring devices 40 are arranged one by one on the four side walls of the furnace 60.

[0056] The second arrangement of the plurality of CO measuring devices 40 is as follows: Figure 4 As shown, there are four main burners 10 and four CO measuring devices 40. The four main burners 10 are arranged one-to-one on the four side walls of the furnace 60, and the four CO measuring devices 40 are arranged one-to-one on the four side walls of the furnace 60 to form four-wall tangential circular combustion; the main burners 10 and CO measuring devices 40 on each side wall of the furnace 60 are arranged at intervals in the horizontal direction.

[0057] The third arrangement of the plurality of CO measuring devices 40 is as follows: Figure 5 As shown, the four side walls of the furnace include two first designated side walls arranged opposite to each other and two second designated side walls arranged opposite to each other; a plurality of main burners 10 are divided into two groups, and each group of main burners includes a plurality of main burners 10; the two groups of main burners are arranged in a one-to-one correspondence with the two first designated side walls, and the plurality of main burners 10 in each group are all arranged on the corresponding first designated side walls to form front and rear wall counter-combustion; a plurality of CO measuring devices 40 are divided into two groups, and each group of CO measuring devices includes two CO measuring devices 40; the two groups of CO measuring devices are arranged in a one-to-one correspondence with the two second designated side walls, and the two CO measuring devices 40 in each group are all arranged on the corresponding second designated side walls.

[0058] Furthermore, the plurality of main burners 10 on each first designated side wall are arranged at intervals in the horizontal direction, and the two CO measuring devices 40 on each second designated side wall are arranged at intervals in the horizontal direction.

[0059] In this embodiment, the coal-fired boiler system further includes an economizer 53 , at least a portion of which is located in the tail flue 50 .

[0060] Specifically, there are a plurality of economizers 53 , and the plurality of economizers 53 are distributed at intervals along the extending direction of the tail flue 50 .

[0061] Specifically, along the flue gas discharge direction in the tail flue 50 , the plurality of economizers 53 are all located upstream of the O 2 measuring device 51 .

[0062] In this embodiment, the coal-fired boiler system also includes a blower 31 and an air preheater 32. The air outlet of the blower 31 is connected to the air inlet of the air preheater 32. The air outlet of the air preheater 32 is connected to and communicated with the first pipe opening of the secondary air inlet main pipeline 71. The cold secondary air flowing out of the blower 31 enters the air preheater 32 for preheating, and the hot secondary air flowing out of the air preheater 32 enters the secondary air inlet main pipeline 71. The secondary air flowing out of the secondary air inlet main pipeline 71 is divided into two branches. One branch passes through the first branch pipeline 72 and enters the main burner 10 in the main combustion area, serving as auxiliary air and peripheral air during coal powder combustion, providing oxygen for the ignition and combustion of coal powder in the furnace 60. The air volume of this branch cannot achieve complete combustion of combustibles and is in an oxygen-deficient state; the other branch passes through the second branch pipeline 73 and enters the burnout air burner 20 in the burnout area, providing oxygen for the unburned combustibles in the main combustion area to achieve re-combustion, thereby realizing staged combustion and low-nitrogen controlled combustion of coal powder in the furnace 60.

[0063] Specifically, the smoke exhaust port of the tail flue 50 is connected to the smoke inlet of the air preheater 32, so that the smoke flowing out of the tail flue 50 enters the air preheater 32, and the waste heat of the smoke is used to heat the secondary air entering the air preheater 32.

[0064] Specifically, a secondary air volume measuring device 33 is provided on the secondary air main inlet pipe 71 to detect the secondary air volume within the secondary air main inlet pipe 71, that is, to detect the total amount of secondary air delivered to the furnace 60. The secondary air volume delivered to the overburnt air burners 20 in the burnout area, as detected by the overburnt air volume measuring device 21, is subtracted from the total amount of secondary air delivered to the furnace 60 as measured by the secondary air volume measuring device 33 to obtain the secondary air volume delivered to the main burners 10 in the main combustion area. Furthermore, the distribution ratio of the secondary air volume delivered to the burnout area to the secondary air volume delivered to the main combustion area is determined, thereby facilitating air distribution and adjustment control for the staged combustion of pulverized coal in the furnace 60.

[0065] In this embodiment, the coal-fired boiler system further includes an SCR reactor 54 , at least a portion of which is located in the tail flue 50 .

[0066] Specifically, along the exhaust direction of the flue gas in the tail flue 50, the SCR reactor 54 is located at the NO x Downstream of the measuring device 52.

[0067] Optionally, there are multiple SCR reactors 54, and the multiple SCR reactors 54 are spaced apart along the extension direction of the tail flue 50; further, along the exhaust direction of the flue gas in the tail flue 50, the multiple SCR reactors 54 are located at the NO x Downstream of the measuring device 52.

[0068] Optionally, the coal-fired boiler system is an environmentally friendly ultra-low emission modified coal-fired boiler system.

[0069] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0070] In the air volume control method of the coal-fired boiler system provided by the present invention, the air volume control method includes: detecting the O2 concentration value and NO x Concentration value to obtain O2 concentration detection value and NO x Concentration detection value, that is, the O2 concentration value of the flue gas in the tail flue 50 is detected, the NO concentration of the flue gas in the tail flue 50 is detected. x The concentration value is NO xConcentration detection value: Detect the concentration of CO generated in the furnace 60 during the combustion process to obtain a CO concentration detection value, that is, the concentration of CO generated in the furnace 60 during the combustion process is the CO concentration detection value. Determine whether the CO concentration detection value is greater than a first preset concentration value, and determine whether the CO concentration detection value is less than a second preset concentration value, where the second preset concentration value is less than the first preset concentration value. When the CO concentration detection value is greater than the first preset concentration value, the CO concentration in the main combustion area is high, and the secondary air intake of the overburnt air burner 20 in the burnout area of the furnace 60 is reduced, and the secondary air intake of the main burner 10 in the main combustion area is increased. When the secondary air intake of the overburnt air burner 20 in the burnout area is reduced to the first preset air intake value, and when the CO concentration detection value is still greater than the first preset concentration value, the total secondary air intake is increased; wherein the total secondary air intake is the sum of the secondary air intake of the main combustion area and the secondary air intake of the burnout area. When the CO concentration detection value is less than the second preset concentration value, the CO concentration in the main combustion area is low, and the secondary air intake of the burnout air burner 20 in the burnout area is increased, and the secondary air intake of the main burner 10 in the main combustion area is reduced. In the process of adjusting the secondary air intake of the burnout area of the furnace 60, the secondary air intake of the main combustion area, and the total secondary air intake, the O2 concentration detection value is controlled within the first preset concentration range, and NO x The concentration detection value is controlled within the second preset concentration range to achieve NO x Concentration control: The air volume control method of the present application is used to solve the technical problem of inaccurate adjustment and control of the burnout air volume of coal-fired boilers in the prior art.

[0071] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can, for example, be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0072] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used herein to describe the spatial positional relationship of a device or feature to other devices or features as shown in the figures. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figures. For example, if the device in the drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0073] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for controlling the air volume of a coal-fired boiler system, characterized in that: include: Detect the O2 concentration and NO in the flue gas in the tail flue (50) x Concentration value to obtain O2 concentration detection value and NO x Concentration detection value; detecting the concentration value of CO generated in the furnace (60) during the combustion process to obtain a CO concentration detection value; Determining whether the CO concentration detection value is greater than a first preset concentration value, and determining whether the CO concentration detection value is less than a second preset concentration value, the second preset concentration value being less than the first preset concentration value; When the CO concentration detection value is greater than the first preset concentration value, the secondary air intake of the overburnt air burner (20) in the overburnt area of the furnace (60) is reduced, and the secondary air intake of the main burner (10) in the main combustion area is increased; When the secondary air intake volume of the overburn air burner (20) in the burnout area is reduced to a first preset air intake volume value, and when the CO concentration detection value is greater than the first preset concentration value, the total secondary air intake volume is increased, and the total secondary air intake volume is the sum of the secondary air intake volume of the main combustion area and the secondary air intake volume of the burnout area; When the CO concentration detection value is less than the second preset concentration value, the secondary air intake of the overburnt air burner (20) in the overburnt area is increased, and the secondary air intake of the main burner (10) in the main combustion area is reduced; In the process of adjusting the secondary air intake volume of the burnout area of the furnace (60), the secondary air intake volume of the main combustion area, and the total secondary air intake volume, the O2 concentration detection value is controlled within a first preset concentration range, and the NO x The concentration detection value is controlled within the second preset concentration range.

2. The air volume control method of a coal-fired boiler system according to claim 1, characterized in that: The main combustion area includes a plurality of first sub-areas sequentially arranged along the horizontal circumference of the furnace (60), each of which is provided with the main burner (10); the burnout area includes a plurality of second sub-areas sequentially arranged along the horizontal circumference of the furnace (60), each of which is provided with the overburnt air burner (20), the plurality of second sub-areas being arranged in one-to-one correspondence with the plurality of first sub-areas, and each of the second sub-areas is located above the corresponding first sub-area in the vertical direction; The air volume control method includes: Detecting the concentration of CO generated in each of the first sub-regions during the combustion process to obtain a corresponding sub-region CO concentration detection value; Determine whether the CO concentration detection value of each partition is greater than the first preset concentration value, and determine whether the CO concentration detection value of each partition is less than the second preset concentration value; When the CO concentration detection value of each sub-area is greater than the first preset concentration value, the secondary air intake of the corresponding overburnt air burner (20) of the second sub-area is reduced, and the secondary air intake of the corresponding main burner (10) of the first sub-area is increased; When the secondary air intake volume of the main burner (10) of the first sub-region is reduced to a first preset air intake volume value, and when the CO concentration detection value of the first sub-region is greater than the first preset concentration value, the total secondary air intake volume of the corresponding sub-region is increased, and the sum of the secondary air intake volume of each first sub-region and the secondary air intake volume of the corresponding second sub-region is the total secondary air intake volume of the corresponding sub-region; When the CO concentration detection value of each sub-area is less than the second preset concentration value, the secondary air intake volume of the corresponding overburnt air burner (20) of the second sub-area is increased, and the secondary air intake volume of the corresponding main burner (10) of the first sub-area is reduced.

3. The air volume control method of a coal-fired boiler system according to claim 1, characterized in that: The air volume control method further comprises: when the NO x The concentration value is greater than the upper limit of the second preset concentration range, and when the secondary air intake volume of the burnout area is its maximum intake volume, the total secondary air intake volume is reduced.

4. A coal-fired boiler system, comprising a furnace (60), a tail flue (50), a main burner air volume regulating device (11) and an overburning air burner air volume regulating device (22), wherein the furnace (60) comprises a main combustion area and a burnout area located vertically above the main combustion area, a main burner (10) is provided in the main combustion area, and an overburning air burner (20) is provided in the burnout area; the main burner air volume regulating device (11) is used to control the secondary air intake volume of the main burner (10) in the main combustion area, and the overburning air burner air volume regulating device (22) is used to control the secondary air intake volume of the overburning air burner (20) in the burnout area; the tail flue (50) is connected to the smoke exhaust port of the furnace (60) to discharge the smoke generated by combustion in the furnace (60) through the tail flue (50); characterized in that The coal-fired boiler system is applicable to the air volume control method according to any one of claims 1 to 3, and the coal-fired boiler system further comprises: a CO measuring device (40), the CO measuring device (40) being arranged vertically between the main combustion area and the burnout area, and at least a portion of the CO measuring device (40) being disposed within the furnace (60) to detect a concentration of CO generated within the furnace (60) during combustion; an O2 measuring device (51), at least a portion of which is disposed in the tail flue (50) to detect an O2 concentration value of the flue gas in the tail flue (50); NO x Measuring device (52), the NO x At least part of the measuring device (52) is arranged in the tail flue (50) to detect the NO in the flue gas in the tail flue (50). x Concentration value.

5. The coal-fired boiler system according to claim 4, characterized in that: The coal-fired boiler system further comprises: Secondary air inlet main pipeline (71); A first branch pipeline (72) and a second branch pipeline (73), wherein the first pipe opening of the first branch pipeline (72) and the first pipe opening of the second branch pipeline (73) are both connected to and communicated with the second pipe opening of the secondary air inlet main pipeline (71); the air inlet of the main burner (10) in the main combustion area is communicated with the second pipe opening of the first branch pipeline (72), and the main burner air volume regulating device (11) is arranged on the first branch pipeline (72); the air inlet of the burnout air burner (20) in the burnout area is communicated with the second pipe opening of the second branch pipeline (73), and the burnout air burner air volume regulating device (22) is arranged on the second branch pipeline (73).

6. The coal-fired boiler system according to claim 4 or 5, characterized in that: The coal-fired boiler system is applicable to the air volume control method according to claim 2, and there are multiple CO measuring devices (40), and the multiple CO measuring devices (40) are arranged in a one-to-one correspondence with the multiple first sub-areas, and each CO measuring device (40) is used to detect the concentration value of CO generated by the combustion of the main burner (10) in the corresponding first sub-area.

7. The coal-fired boiler system according to claim 6, characterized in that: The furnace (60) has four side walls and four wall corners. There are four main burners (10) and four CO measuring devices (40). The four main burners (10) are arranged in a one-to-one correspondence at the four wall corners of the furnace (60), and the four CO measuring devices (40) are arranged in a one-to-one correspondence on the four side walls of the furnace (60).

8. The coal-fired boiler system according to claim 6, characterized in that: The furnace (60) has four side walls, and there are four main burners (10) and four CO measuring devices (40). The four main burners (10) are arranged one-to-one on the four side walls of the furnace (60), and the four CO measuring devices (40) are arranged one-to-one on the four side walls of the furnace (60). The main burners (10) and CO measuring devices (40) on each side wall of the furnace (60) are arranged at intervals in the horizontal direction.

9. The coal-fired boiler system according to claim 6, characterized in that: The furnace (60) has four side walls, and the four side walls of the furnace (60) include two first designated side walls arranged opposite to each other and two second designated side walls arranged opposite to each other; the plurality of main burners (10) are divided into two groups, and each group of main burners includes a plurality of main burners (10); the two groups of main burners are arranged in a one-to-one correspondence with the two first designated side walls, and the plurality of main burners (10) in each group are arranged on the corresponding first designated side walls; the plurality of CO measuring devices (40) are divided into two groups, and each group of CO measuring devices includes two CO measuring devices (40); the two groups of CO measuring devices are arranged in a one-to-one correspondence with the two second designated side walls, and the two CO measuring devices (40) in each group are arranged on the corresponding second designated side walls.

10. The coal-fired boiler system according to claim 5, characterized in that: The second branch pipeline (73) is provided with a burnout air volume measuring device (21).

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