A lignite blending combustion stabilization intelligent control system

Abstract

The embodiment of the present application provides a lignite blending combustion stable intelligent control system, and belongs to the technical field of inferior coal blending combustion in coal-fired power plants. The lignite blending combustion stable intelligent control system comprises a lignite drying and dewatering device, an intelligent analysis device and an economizer. The output end of the economizer is connected with the input end of the lignite drying and dewatering device, and is used for providing superheated flue gas to the lignite drying and dewatering device. The lignite drying and dewatering device dries lignite by using the superheated flue gas. The intelligent analysis device is used for calculating the required amount of superheated flue gas of the lignite drying and dewatering device. The lignite drying and dewatering device realizes low-calorific-value lignite upgrading by recycling the extracted excessive flue gas, improves the combustion efficiency, and protects the boiler body and auxiliary system.

Description

Technical Field

[0001] This invention relates to the field of blending low-quality coal in coal-fired power plants, and specifically to an intelligent control system for stable combustion of lignite. Background Technology

[0002] Traditional coal-fired power plants will continue to bear the significant responsibility of ensuring coal supply and flexibly controlling peak loads. Affected by rising coal supply and prices, many power plants are unable to burn the coal originally designed for them and have begun to blend large proportions of non-designed coal types, including inferior quality coal. Therefore, given that flexible peak load control has become the norm for thermal power units, improving boiler fuel flexibility has become one of the main technical approaches to enhancing unit flexibility. The combined effects of coal quality deviations and flexible peak load control significantly impact the safety and economic efficiency of the units.

[0003] With the rapid development of my country's social economy, the utilization of relatively abundant lignite resources has gradually gained attention, with combustion being one of the main utilization methods. However, due to its high moisture content, low calorific value, and tendency to spontaneously combust, its utilization faces problems such as high transportation costs and low utilization efficiency. Currently, drying and upgrading to reduce the moisture content and increase the calorific value of lignite is the main research direction both domestically and internationally.

[0004] Regarding blending, the use of anthracite, bituminous coal, and lignite is relatively widespread and has been studied in depth. The use of low-quality lignite is less common, especially under current flexible operating conditions. Therefore, conducting research on blending all or part of low-quality coal to improve unit performance has practical value.

[0005] In conclusion, how to solve the problems caused by the co-firing of inferior lignite in coal-fired power plants has become an urgent issue for those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to provide an intelligent control system for stable combustion of lignite blended in coal. This system utilizes a portion of the flue gas from the economizer to dry lignite, thereby improving the quality of inferior lignite.

[0007] To achieve the above objectives, embodiments of the present invention provide an intelligent control system for stable combustion of lignite blending, the system comprising a lignite drying and dehydration device, an intelligent analysis device, and an economizer;

[0008] The intelligent analysis device is used to calculate the amount of superheated flue gas required by the lignite drying and dewatering device, and sends the calculated amount of superheated flue gas to the economizer;

[0009] The economizer is used to supply superheated flue gas to the lignite drying and dewatering device based on the amount of superheated flue gas from the intelligent analysis device. The superheated flue gas is used to dry lignite in the lignite drying and dewatering device.

[0010] Preferably, the intelligent analysis device includes a data acquisition unit and a computing unit;

[0011] The acquisition unit is used to collect the outlet flue gas volume of the economizer, the outlet flue gas temperature of the economizer, and the amount of lignite in the lignite drying and dewatering device.

[0012] The calculation unit is used to calculate the amount of superheated flue gas required by the lignite drying and dewatering device based on the outlet flue gas volume, outlet flue gas temperature, and lignite volume.

[0013] Preferably, the system further includes a first fan, which is electrically connected to the intelligent analysis device and is used to receive the extraction volume command issued by the intelligent analysis device and extract the amount of superheated flue gas in the economizer according to the extraction volume command.

[0014] Preferably, the system further includes a condenser and a liquid collection tank. The input end of the condenser is connected to the lignite drying and dehydration device, and the output end of the condenser is connected to the liquid collection tank. The lignite drying and dehydration device (1) dries lignite to generate water vapor, and the water vapor enters the condenser and the liquid collection tank in sequence.

[0015] Preferably, the system further includes an SCR denitrification device, the first input end of which is connected to the output end of the economizer, and the second input end of which is connected to the flue gas output end of the lignite drying and dewatering device. After the superheated flue gas dries the lignite, it is used as recirculated flue gas and enters the SCR denitrification device through the flue gas output end.

[0016] Preferably, the acquisition unit is further used to acquire the status parameters of the SCR denitrification equipment, the calculation unit is further used to calculate the optimal flue gas consumption of the SCR denitrification equipment based on the status parameters of the SCR denitrification equipment, and the intelligent analysis device calculates the amount of superheated flue gas required by the lignite drying and dewatering device based on the outlet flue gas volume, outlet flue gas temperature, lignite quantity, and the optimal flue gas consumption of the SCR denitrification equipment.

[0017] Preferably, the system further includes a second fan, the input end of which is connected to the lignite drying and dewatering device, and the output end of which is connected to the SCR denitrification device. The second fan is used to extract the recirculated flue gas.

[0018] Preferably, the intelligent analysis device is electrically connected to the second fan and is used to control the flue gas flow rate of the second fan, so that the total amount of flue gas in the SCR denitrification equipment remains stable.

[0019] Preferably, the system further includes a low-quality lignite conveying device, a high-calorific-value bituminous coal conveying device, a mixed coal bunker, a coal mill, and a boiler body;

[0020] The inferior lignite conveying device is connected to the lignite drying and dewatering device and is used to dry the lignite in the lignite drying and dewatering device.

[0021] The mixed coal bunker is connected to the lignite drying and dewatering device and the high-calorific-value bituminous coal conveying device, respectively, and is used to receive lignite from the lignite drying and dewatering device and high-calorific-value bituminous coal conveyed from the high-calorific-value bituminous coal conveying device.

[0022] The coal mill is connected to the coal mixing bin and is used to receive and grind the mixed coal in the coal mixing bin;

[0023] The boiler body is used to receive the mixed coal ground by the coal mill, and the boiler body outputs superheated flue gas to the economizer.

[0024] Preferably, the mixed coal bunker is also used to control the conveying speed of the low-quality lignite conveying device and the high-calorific-value bituminous coal conveying device.

[0025] The lignite co-firing and stable combustion intelligent control system provided in this application makes full use of existing equipment by adding intelligent analysis devices and lignite drying and dehydration devices to achieve energy saving and consumption reduction. On the one hand, the lignite drying and dehydration device utilizes the recirculation of excess flue gas to upgrade low-calorific-value lignite, improve combustion efficiency, and protect the boiler body and auxiliary systems. On the other hand, the recirculation of excess flue gas eliminates the safety and environmental risks of the SCR denitrification equipment, effectively avoiding the impact of large fluctuations in flue gas volume generated by the economizer on the SCR denitrification equipment.

[0026] Other features and advantages of the embodiments of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0027] The accompanying drawings are provided to further illustrate embodiments of the present invention and form part of the specification. They are used together with the following detailed description to explain the embodiments of the present invention, but do not constitute a limitation thereof. In the drawings:

[0028] Figure 1 This is a structural block diagram of a lignite blending and stable combustion intelligent control system provided in Embodiment 2 of the present invention.

[0029] Explanation of reference numerals in the attached figures

[0030] 1-Lignite drying and dewatering device, 2-Intelligent analysis device, 3-Economizer, 4-First fan, 5-Second fan, 6-Condenser, 7-SCR denitrification equipment, 8-Low-quality lignite conveying device, 9-High-calorific-value bituminous coal conveying device, 10-Mixed coal bunker, 11-Coal mill, 12-Boiler body. Detailed Implementation

[0031] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of the present invention.

[0032] In embodiments of the present invention, unless otherwise stated, directional terms such as "up," "down," "left," and "right" generally refer to the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the invention is conventionally placed during use. Terms such as "first," "second," and "third" are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance.

[0033] The terms "parallel" and "perpendicular" do not mean that the components must be absolutely parallel or perpendicular, but rather that they can be slightly tilted. For example, "parallel" simply means that its direction is more parallel than "perpendicular," not that the structure must be completely parallel, but that it can be slightly tilted.

[0034] The terms "horizontal," "vertical," and "sag" do not imply that a component must be absolutely horizontal, vertical, or sagging, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," not that the structure must be completely horizontal, but can be slightly tilted.

[0035] Furthermore, terms like "roughly" and "basically" are used to indicate that the content does not require absolute precision, but rather allows for a certain degree of deviation. For example, "roughly equal" does not simply mean absolute equality; in actual production and operation, achieving absolute "equality" is difficult, and a certain degree of deviation is generally present. Therefore, besides absolute equality, "roughly equal to" also includes the aforementioned situation where a certain degree of deviation exists. Using this as an example, in other cases, unless otherwise specified, terms like "roughly" and "basically" have similar meanings.

[0036] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0037] Example 1

[0038] This embodiment provides an intelligent control system for stable combustion of lignite, including a lignite drying and dehydration device 1, an intelligent analysis device 2, and an economizer 3. The output end of the economizer 3 is connected to the input end of the lignite drying and dehydration device 1 and is used to provide superheated flue gas to the lignite drying and dehydration device 1. The lignite drying and dehydration device 1 uses superheated flue gas to dry lignite. The intelligent analysis device 2 is used to calculate the amount of superheated flue gas required by the lignite drying and dehydration device 1.

[0039] The large volume of flue gas produced by the combustion of low-quality lignite poses a significant noise and safety threat to the denitrification system. By utilizing a portion of the flue gas from economizer 3 to dry the low-quality lignite, the quality of the lignite can be improved and its calorific value increased.

[0040] Research and analysis have shown that the low calorific value and high moisture content of raw lignite mean that the core of its upgrading lies in removing the moisture to increase its calorific value. Generally speaking, for every percentage point reduction in moisture content, the calorific value of lignite can increase by 50 to 70 kcal per kilogram. Theoretically, if 100% of the internal and external moisture is removed from lignite, its calorific value can increase by 2000 to 2800 kcal per kilogram.

[0041] The intelligent analysis device 2 is used to calculate the amount of superheated flue gas required by the lignite drying and dewatering device 1. After the intelligent analysis device 2 calculates the amount of superheated flue gas required by the lignite drying and dewatering device 1, the system delivers the amount of superheated flue gas to the lignite drying and dewatering device 1 to dry the lignite in the lignite drying and dewatering device 1, and then burns the dried lignite.

[0042] Specifically, in this embodiment, the intelligent analysis device 2 includes a data acquisition unit and a computing unit;

[0043] The acquisition unit is used to acquire the outlet flue gas volume of economizer 3, the outlet flue gas temperature of economizer 3, and the amount of lignite in lignite drying and dewatering device 1.

[0044] The calculation unit is used to calculate the amount of superheated flue gas required by the lignite drying and dewatering device 1 based on the outlet flue gas volume, outlet flue gas temperature, and lignite volume.

[0045] In this embodiment, the system further includes a first fan 4, which is electrically connected to the intelligent analysis device 2 and is used to receive the extraction volume command issued by the intelligent analysis device 2 and extract the amount of superheated flue gas in the economizer 3 according to the extraction volume command.

[0046] The first fan 4 is used to extract the superheated flue gas from the economizer 3. The first fan 4 is connected to the intelligent analysis device 2 and receives the extraction volume command from the intelligent analysis device 2. The first fan 4 controls the fan speed and fan working time according to the extraction volume command to complete the extraction work.

[0047] In this embodiment, the system further includes a condenser 6 and a liquid collection tank. The input end of the condenser 6 is connected to the lignite drying and dehydration device 1, and the output end of the condenser 6 is connected to the liquid collection tank. The lignite drying and dehydration device (1) generates water vapor by drying lignite, and the water vapor enters the condenser 6 and the liquid collection tank in sequence. The water vapor generated by drying lignite first enters the air cooler for condensation, and then enters the liquid collection tank for collection.

[0048] In this embodiment, the system also includes a low-quality lignite conveying device 8, a high-calorific-value bituminous coal conveying device 9, a mixed coal bunker 10, a coal mill 11, and a boiler body 12.

[0049] The inferior lignite conveying device 8 is connected to the lignite drying and dewatering device 1;

[0050] The mixed coal bunker 10 is connected to the lignite drying and dewatering device 1 and the high-calorific-value bituminous coal conveying device 9 respectively, and is used to receive lignite from the lignite drying and dewatering device 1 and high-calorific-value bituminous coal conveyed from the high-calorific-value bituminous coal conveying device 9.

[0051] The coal mill 11 is connected to the coal mixing bin 10 and is used to receive and grind the mixed coal in the coal mixing bin 10.

[0052] The boiler body 12 is used to receive the mixed coal ground by the coal mill 11, and the boiler body 12 outputs superheated flue gas to the economizer 3.

[0053] Upgrading low-quality lignite and mixing it with high-calorific-value bituminous coal can solve both the problem of high-calorific-value bituminous coal energy shortage and the safety threat to desulfurization systems caused by the large amount of flue gas generated by the low moisture content and calorific value of lignite.

[0054] In this embodiment, the mixed coal bunker 10 is also used to control the conveying speed of the low-quality lignite conveying device 8 and the high-calorific-value bituminous coal conveying device 9.

[0055] Specifically, the blending ratio of lignite and high-calorific-value bituminous coal is controlled by controlling the conveying speed of the low-quality lignite conveying device 8 and the high-calorific-value bituminous coal conveying device 9.

[0056] In this embodiment, the superheated flue gas after drying lignite still needs to be desulfurized.

[0057] Example 2

[0058] Please refer to Figure 1This embodiment provides an intelligent control system for stable combustion of lignite, including a lignite drying and dehydration device 1, an intelligent analysis device 2, and an economizer 3. The output end of the economizer 3 is connected to the input end of the lignite drying and dehydration device 1 and is used to provide superheated flue gas to the lignite drying and dehydration device 1. The lignite drying and dehydration device 1 uses superheated flue gas to dry lignite. The intelligent analysis device 2 is used to calculate the amount of superheated flue gas required by the lignite drying and dehydration device 1.

[0059] In this embodiment, the core principle of the lignite drying and dehydration device 1 is a plate heat exchanger and a negative pressure flash separator. The negative pressure flash separator is in a vacuum state with a back pressure of 13 kPa.

[0060] The large volume of flue gas produced by the combustion of low-quality lignite poses a significant noise and safety threat to the denitrification system. By utilizing a portion of the flue gas from economizer 3 to dry the low-quality lignite, the quality of the lignite can be improved and its calorific value increased.

[0061] Research and analysis have shown that the low calorific value and high moisture content of raw lignite mean that the core of its upgrading lies in removing the moisture to increase its calorific value. Generally speaking, for every percentage point reduction in moisture content, the calorific value of lignite can increase by 50 to 70 kcal per kilogram. Theoretically, if 100% of the internal and external moisture is removed from lignite, its calorific value can increase by 2000 to 2800 kcal per kilogram.

[0062] The intelligent analysis device 2 is used to calculate the amount of superheated flue gas required by the lignite drying and dewatering device 1. After the intelligent analysis device 2 calculates the amount of superheated flue gas required by the lignite drying and dewatering device 1, the system delivers the amount of superheated flue gas to the lignite drying and dewatering device 1 to dry the lignite in the lignite drying and dewatering device 1, and then burns the dried lignite.

[0063] In this embodiment, the system further includes an SCR denitrification device 7. The first input terminal of the SCR denitrification device 7 is connected to the output terminal of the economizer 3, and the second input terminal of the SCR denitrification device 7 is connected to the flue gas output terminal of the lignite drying and dewatering device 1. The superheated flue gas, after drying the lignite, is used as recirculated flue gas and enters the SCR denitrification device 7 through the flue gas output terminal. The SCR denitrification device 7 is used to denitrify the flue gas.

[0064] Specifically, in this embodiment, the intelligent analysis device 2 includes a data acquisition unit, which is used to acquire the outlet flue gas volume and temperature of the economizer 3, as well as the amount of lignite in the lignite drying and dewatering device 1. In this embodiment, the data acquisition unit is also used to acquire the status parameters of the SCR denitrification equipment 7. The intelligent analysis device 2 calculates the optimal flue gas volume to be absorbed by the SCR denitrification equipment 7 based on the status parameters of the SCR denitrification equipment 7. The intelligent analysis device 2 also calculates the required superheated flue gas volume for the lignite drying and dewatering device 1 based on the outlet flue gas volume, outlet flue gas temperature, amount of lignite, and the optimal flue gas volume to be absorbed by the SCR denitrification equipment 7.

[0065] In this embodiment, the system further includes a first fan 4, which is electrically connected to the intelligent analysis device 2 and is used to receive the extraction volume command issued by the intelligent analysis device 2 and extract the amount of superheated flue gas in the economizer 3 according to the extraction volume command.

[0066] The first fan 4 is used to extract the superheated flue gas from the economizer 3. The first fan 4 is connected to the intelligent analysis device 2 and receives the extraction volume command from the intelligent analysis device 2. The first fan 4 controls the fan speed and fan working time according to the extraction volume command to complete the extraction work.

[0067] In this embodiment, the system further includes a second fan 5, the input end of which is connected to the lignite drying and dewatering device 1, and the output end of which is connected to the SCR denitrification device 7. The second fan 5 is used to extract the recirculated flue gas.

[0068] Specifically, the second fan 5 is used to extract the recirculated flue gas after drying lignite and output it to the SCR desulfurization equipment, which then desulfurizes the recirculated flue gas.

[0069] In this embodiment, the intelligent analysis device 2 is electrically connected to the second fan 5 and is used to control the flue gas flow rate of the second fan 5 so that the total amount of flue gas in the SCR denitrification equipment 7 remains stable.

[0070] Specifically, the total flue gas volume of the economizer 3 is the sum of the flue gas volume that the SCR denitrification equipment 7 can absorb and the flue gas volume extracted by the first fan 4. The total flue gas volume of the SCR denitrification equipment 7 is the sum of the flue gas volume that the SCR denitrification equipment 7 can absorb and the flue gas volume that the second fan 5 recirculates.

[0071] In this embodiment, the system further includes a condenser 6 and a liquid collection tank. The input end of the condenser 6 is connected to the lignite drying and dehydration device 1, and the output end of the condenser 6 is connected to the liquid collection tank. The lignite drying and dehydration device (1) generates water vapor by drying lignite, and the water vapor enters the condenser 6 and the liquid collection tank in sequence. The water vapor generated by drying lignite first enters the air cooler for condensation, and then enters the liquid collection tank for collection.

[0072] In this embodiment, the system also includes a low-quality lignite conveying device 8, a high-calorific-value bituminous coal conveying device 9, a mixed coal bunker 10, a coal mill 11, and a boiler body 12.

[0073] The inferior lignite conveying device 8 is connected to the lignite drying and dewatering device 1;

[0074] The mixed coal bunker 10 is connected to the lignite drying and dewatering device 1 and the high-calorific-value bituminous coal conveying device 9 respectively, and is used to receive lignite from the lignite drying and dewatering device 1 and high-calorific-value bituminous coal conveyed from the high-calorific-value bituminous coal conveying device 9.

[0075] The coal mill 11 is connected to the coal mixing bin 10 and is used to receive and grind the mixed coal in the coal mixing bin 10.

[0076] The boiler body 12 is used to receive the mixed coal ground by the coal mill 11, and the boiler body 12 outputs superheated flue gas to the economizer 3.

[0077] Upgrading low-quality lignite and mixing it with high-calorific-value bituminous coal can solve both the problem of high-calorific-value bituminous coal energy shortage and the safety threat to desulfurization systems caused by the large amount of flue gas generated by the low moisture content and calorific value of lignite.

[0078] In this embodiment, the mixed coal bunker 10 is also used to control the conveying speed of the low-quality lignite conveying device 8 and the high-calorific-value bituminous coal conveying device 9.

[0079] Specifically, the blending ratio of lignite and high-calorific-value bituminous coal is controlled by controlling the conveying speed of the low-quality lignite conveying device 8 and the high-calorific-value bituminous coal conveying device 9.

[0080] The lignite co-firing and stable combustion intelligent control system provided in this application fully utilizes existing equipment by adding an intelligent analysis device 2 and a lignite drying and dehydration device 1, achieving energy saving and consumption reduction. On the one hand, the lignite drying and dehydration device 1 utilizes the recirculation of excess flue gas to upgrade low-calorific-value lignite, improve combustion efficiency, and protect the boiler body 12 and auxiliary systems. On the other hand, the recirculation of excess flue gas eliminates the safety and environmental risks of the SCR denitrification equipment 7, effectively avoiding the impact of large fluctuations in flue gas volume generated by the economizer 3 on the SCR denitrification equipment 7, and bringing benefits to equipment operation and uniform ammonia injection, avoiding the safety hazard of ammonia escape and over-injection leading to blockage of subsequent air preheater equipment. This application fully utilizes the excess flue gas volume generated from burning low-calorific-value lignite, using its heat as a heat source for the lignite drying and dehydration system. Under the premise of not affecting the safe and stable operation of the unit and upgrading the lignite, which is conducive to stable boiler combustion, it ensures the stable operation of the denitrification system and eliminates safety and environmental risks.

[0081] The optional embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the embodiments of the present invention are not limited to the specific details in the above embodiments. Within the scope of the technical concept of the embodiments of the present invention, various simple modifications can be made to the technical solutions of the embodiments of the present invention, and these simple modifications all fall within the protection scope of the embodiments of the present invention.

[0082] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the embodiments of the present invention will not describe the various possible combinations separately.

[0083] Those skilled in the art will understand that all or part of the steps in the methods of the above embodiments can be implemented by a program instructing related hardware. This program is stored in a storage medium and includes several instructions to cause a microcontroller, chip, or processor to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as a USB flash drive, a portable hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0084] Furthermore, various different implementations of the present invention can be combined arbitrarily, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed in the present invention.

Claims

1. A lignite blending combustion stabilization intelligent control system, characterized in that, The system comprises: The lignite drying and dewatering device (1), the intelligent analysis device (2), the coal economizer (3) and the SCR denitration equipment (7); The lignite drying and dewatering device (1) comprises: a plate heat exchanger and a negative pressure flash separation device; The intelligent analysis device (2) is used for calculating the amount of superheated flue gas required by the lignite drying and dewatering device (1) and sending the calculated amount of superheated flue gas to the coal economizer (3); wherein the intelligent analysis device comprises: a collection unit and a calculation unit, the collection unit is used for collecting the flue gas amount and flue gas temperature at the outlet of the coal economizer (3), the lignite amount of the lignite drying and dewatering device (1) and the state parameters of the SCR denitration equipment (7); the calculation unit is used for calculating the optimal flue gas amount of the SCR denitration equipment (7) according to the collected state parameters of the SCR denitration equipment (7) and calculating the amount of superheated flue gas required by the lignite drying and dewatering device (1) according to the flue gas amount and flue gas temperature at the outlet of the coal economizer (3), the lignite amount of the lignite drying and dewatering device (1) and the optimal flue gas amount of the SCR denitration equipment (7); The coal economizer (3) is used for providing superheated flue gas to the lignite drying and dewatering device (1) according to the amount of superheated flue gas from the intelligent analysis device (2), and the superheated flue gas is used for drying lignite in the lignite drying and dewatering device (1); The SCR denitration equipment (7) is used for denitration treatment of the recirculated flue gas from the lignite drying and dewatering device (1), wherein the recirculated flue gas is obtained after the lignite is dried by the superheated flue gas.

2. The intelligent control system for stable combustion of lignite blending according to claim 1, characterized in that, The system further comprises: a first fan (4); The first fan (4) is electrically connected with the intelligent analysis device (2); The intelligent analysis device (2) is further used for issuing a draw amount instruction; The first fan (4) draws the amount of superheated flue gas in the coal economizer (3) according to the draw amount instruction.

3. The intelligent control system for stable combustion of lignite blending according to claim 1, characterized in that, The system further comprises: a condenser (6) and a liquid collection box; The input end of the condenser (6) is connected with the lignite drying and dewatering device (1), and the output end of the condenser (6) is connected with the liquid collection box; The water vapor generated by the lignite drying and dewatering device (1) enters the condenser (6) and the liquid collection box.

4. The intelligent control system for stable combustion of lignite blending according to claim 1, characterized in that, The first input end of the SCR denitration equipment (7) is connected with the output end of the coal economizer (3), and the second input end of the SCR denitration equipment (7) is connected with the flue gas output end of the lignite drying and dewatering device (1), and the superheated flue gas after drying the lignite enters the SCR denitration equipment (7) through the flue gas output end of the lignite drying and dewatering device (1) as the recirculated flue gas.

5. The intelligent control system for stable combustion of lignite blending according to claim 4, characterized in that, The system further comprises: a second fan (5); The input end of the second fan (5) is connected with the lignite drying and dewatering device (1), and the output end of the second fan (5) is connected with the SCR denitration equipment (7), and the second fan (5) is used for drawing the recirculated flue gas.

6. The intelligent control system for stable combustion of lignite blending according to claim 5, characterized in that, The intelligent analysis device (2) is electrically connected with the second fan (5) and is used for controlling the flue gas flow rate of the second fan (5) to keep the total amount of flue gas of the SCR denitration equipment (7) stable.

7. The intelligent control system for stable combustion of lignite blending according to claim 1, characterized in that, The system further comprises a low-grade lignite conveying device (8), a high-calorific-value bituminous coal conveying device (9), a mixed coal bin (10), a coal mill (11) and a boiler body (12); The low-grade lignite conveying device (8) is connected with the lignite drying and dewatering device (1) and used for conveying lignite to the lignite drying and dewatering device; The mixed coal bin (10) is connected with the lignite drying and dewatering device (1) and the high-calorific-value bituminous coal conveying device (9) respectively and used for receiving dried lignite from the lignite drying and dewatering device (1) and high-calorific-value bituminous coal conveyed by the high-calorific-value bituminous coal conveying device (9); The coal mill (11) is connected with the mixed coal bin (10) and used for receiving mixed coal grinded by the mixed coal bin (10); The boiler body (12) is used for receiving mixed coal grinded by the coal mill (11) and outputting superheated flue gas to the economizer (3).

8. The intelligent control system for stable combustion of lignite blending according to claim 7, characterized in that, The mixed coal bin (10) is further used for controlling the lignite conveying speed of the low-grade lignite conveying device (8) and the bituminous coal conveying speed of the high-calorific-value bituminous coal conveying device (9).

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