Dual-circulation combustion stabilizing system for a boiler with mixed combustion

Abstract

The present application provides a kind of dual-cycle combustion stabilizing system of mixed combustion boiler, belongs to coal mixed combustion technical field.The system, including lignite dryer, condensate device, poor lignite conveying device, intelligent analysis device, heat exchanger, bypass flue air blower, coal mill and SCR denitration device.Intelligent analysis device controls bypass flue air blower and extracts excess flue gas volume and is transported to heat exchanger.And control bypass flue air blower and transport the excess flue gas volume after heat exchange to coal mill, to supplement the air volume output to coal mill, reach the effect of flue gas circulation, improve the air volume transported to coal mill.At the same time, heat exchanger uses condensate heat exchange to obtain high-temperature steam, and transports high-temperature steam to lignite dryer.Lignite dryer uses high-temperature steam to dry poor lignite to obtain low-temperature condensate, and transports low-temperature condensate to condensate device, to achieve the effect of water circulation.Thereby realize lignite upgrading, improve the purpose of combustion efficiency, and have protective effect to boiler and auxiliary machine.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of coal blending combustion, in particular to a double-circulation stable combustion system for a blending combustion boiler. BACKGROUND

[0002] Traditional coal-fired power plants will still bear the major responsibility of power supply and flexible peak regulation for a long time. Influenced by coal supply and price rise, many power plants have been unable to burn the original design coal quality and have begun to blend a large proportion of non-design coal, which includes blending of inferior low-quality coal. Therefore, under the background that flexible peak regulation has become the normal operation of thermal power units, improving the fuel flexibility of the boiler has become one of the main technical routes to improve the flexibility of the unit. Under the influence of coal quality deviation and flexible peak regulation, the safety and economy of the unit are greatly affected.

[0003] With the rapid development of China's social economy, the utilization of relatively abundant lignite resources has gradually attracted attention, and combustion is one of the main utilization ways. However, due to its high moisture content, low calorific value and easy self-ignition characteristics, there are problems such as high transportation cost and low utilization efficiency in the utilization process. At present, drying and upgrading to reduce the moisture content of lignite and improve the calorific value of lignite are the main research directions at home and abroad.

[0004] In terms of blending combustion, the application of anthracite, bituminous coal and lignite is relatively wide, and there has been in-depth research. The application of inferior lignite is less, especially under the current flexible operation mode, to carry out relevant research on blending all or part of inferior coal to improve the performance of the unit has a certain practical value.

[0005] In summary, how to solve the problems caused by blending inferior lignite in coal-fired power plants has become a problem to be solved by those skilled in the art. SUMMARY

[0006] The purpose of the embodiments of the present application is to provide a double-circulation stable combustion system for a blending combustion boiler to at least solve the problem of how to avoid the problem of too high flue gas and low combustion rate in the blending process of inferior lignite due to the characteristics of inferior lignite.

[0007] In order to achieve the above-mentioned purpose, the present application provides a double-circulation stable combustion system for a blending combustion boiler, which comprises a lignite dryer, a condensate device, an inferior lignite conveying device, an intelligent analysis device, a heat exchanger, a bypass flue air supply fan, a coal mill and an SCR denitration device communicated with the blending combustion boiler, the coal outlet of the coal mill is communicated with the coal inlet of the blending combustion boiler;

[0008] The intelligent analysis device is used for:

[0009] According to the rated flue gas amount of the SCR denitration device, the bypass flue air supply fan is controlled to extract the excess flue gas amount exceeding the rated flue gas amount in the flue gas discharged by the blending combustion boiler and convey it to the heat exchanger.

[0010] The control bypass flue gas fan transports the excess flue gas after heat exchange via the heat exchanger to the coal mill;

[0011] According to the rated heat of the lignite dryer, the heat exchange efficiency of the heat exchanger and the condensate water flow rate of the condensate water device are controlled;

[0012] The heat exchanger is used to obtain high-temperature steam by heat exchange with the condensate water, and the high-temperature steam is transported to the lignite dryer;

[0013] The lignite dryer is used to obtain low-temperature condensate water after drying the low-quality lignite transported by the low-quality lignite transportation device, and the low-temperature condensate water is transported to the condensate water device.

[0014] Optionally, the above-mentioned dual-cycle stable combustion system of the blending boiler further comprises a coal mill fan, the coal mill fan is connected with the intelligent analysis device and the coal mill at the same time, and the intelligent analysis device is further used to control the coal mill fan to transport air volume to the coal mill.

[0015] Optionally, the intelligent analysis device is further used to calculate and control the air volume of the coal mill fan according to the excess flue gas after heat exchange.

[0016] Optionally, the intelligent analysis device controls the air volume of the coal mill fan by controlling the power of the coal mill fan.

[0017] Optionally, a condensate water transportation pump is arranged between the heat exchanger and the condensate water device, and the condensate water transportation pump is used to pump the condensate water of the condensate water device to the heat exchanger.

[0018] Optionally, a first valve is arranged between the condensate water transportation pump and the lignite dryer, and the first valve is connected with the intelligent analysis device.

[0019] The first valve is used to guide the low-temperature condensate water discharged by the lignite dryer to the condensate water transportation pump.

[0020] Optionally, a second valve is arranged between the cold end of the condensate water device and the lignite dryer, a low-temperature heater is arranged between the cold end of the condensate water device and the hot end of the condensate water device, and a third valve is arranged between the hot end of the condensate water device and the condensate water transportation pump, and the second valve and the third valve are respectively connected with the intelligent analysis device.

[0021] The intelligent analysis device is used to control the opening degrees of the first valve, the second valve and the third valve according to the excess flue gas.

[0022] Optionally, the above-mentioned dual-cycle stable combustion system of the blending boiler further comprises a designed coal type transportation device and a mixed coal bin connected with the coal mill, and the mixed coal bin is connected with the lignite dryer and the designed coal type transportation device at the same time.

[0023] The mixed coal bin is used for mixing the high-quality coal delivered by the designed coal delivery device with the low-quality lignite dried by the lignite dryer, and then delivering the mixed coal to the coal mill.

[0024] Optionally, the intelligent analysis device controls the power of the bypass flue gas fan to draw the excess flue gas.

[0025] Optionally, the wind speed measuring device and the temperature measuring device are arranged at the flue gas discharge port of the blending boiler and are connected with the intelligent analysis device.

[0026] Through the above technical solution, in the process of delivering the flue gas generated by the blending boiler to the SCR denitration device, the intelligent analysis device controls the bypass flue gas fan to draw the excess flue gas exceeding the rated flue gas amount in the flue gas discharged by the blending boiler and deliver the excess flue gas to the heat exchanger for heat exchange, which not only ensures the safe production and operation of the SCR denitration device and other auxiliary machines, but also reduces the environmental protection risk hidden danger. And the intelligent analysis device controls the bypass flue gas fan to deliver the heat-exchanged excess flue gas to the coal mill to supplement the air volume output to the coal mill, so as to achieve the effect of flue gas circulation and improve the air volume delivered to the coal mill. At the same time, in the process of drying the low-quality lignite by the lignite dryer, the intelligent analysis device controls the condensate water flow delivered by the condensate water device and the heat exchange efficiency of the heat exchanger according to the rated heat of the lignite dryer, so as to ensure that the high-temperature steam flowing into the lignite dryer can reach the rated heat of the lignite dryer. The heat exchanger uses condensate water to exchange heat with the excess flue gas, and the condensate water after heat exchange in the heat exchanger becomes high-temperature steam, which is delivered to the inside of the lignite dryer to improve the temperature inside the lignite dryer, so as to dry the low-quality lignite delivered by the low-quality lignite delivery device in the lignite dryer to remove the moisture of the low-quality lignite, so as to achieve the purpose of upgrading the low-quality lignite. The high-temperature steam of the lignite dryer drying the low-quality lignite is converted into low-temperature condensate water, which returns to the condensate water device again, thereby achieving the effect of water circulation.

[0027] Other features and advantages of the present application will be described in detail in the following detailed description. BRIEF DESCRIPTION OF DRAWINGS

[0028] The accompanying drawings are included to provide a further understanding of the present application and are incorporated in and constitute a part of this specification, illustrate embodiments of the present application and serve to explain the principles of the present application, but are not intended to limit the present application. In the drawings:

[0029] Figure 1 is a structural schematic diagram of a double-circulation stable combustion system of a blending boiler provided by the present application.

[0030] MARKING OF THE DRAWINGS

[0031] 1 - inferior lignite conveying device, 2 - lignite dryer, 3 - designed coal conveying device, 4 - mixed coal bin, 5 - coal mill, 6 - coal mill air blower, 7 - blending boiler, 8 - economizer, 9 - heat exchanger, 10 - SCR denitration device, 11 - intelligent analysis device, 12 - bypass flue air blower, 13 - condensate conveying pump, 14 - low-temperature heater, 15 - first valve, 16 - second valve, 17 - third valve. DETAILED DESCRIPTION

[0032] The specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely intended to illustrate and explain the present application, and are not intended to limit the present application.

[0033] Figure 1 is a structural schematic diagram of a blending boiler double-circulation stable combustion system provided by the present application. As shown in Figure 1 the present embodiment provides a blending boiler double-circulation stable combustion system, which comprises a lignite dryer 2, a condensate device, an inferior lignite conveying device 1, an intelligent analysis device 11, a heat exchanger 9, a bypass flue air blower 12, a coal mill 5 and an SCR denitration device 10 in communication with the blending boiler 7, wherein the coal outlet of the coal mill 5 is in communication with the coal inlet of the blending boiler 7.

[0034] The intelligent analysis device 11 is used for:

[0035] According to the rated flue gas amount of the SCR denitration device 10, the bypass flue air blower 12 is controlled to extract the excess flue gas amount exceeding the rated flue gas amount from the flue gas discharged by the blending boiler 7 and to convey the excess flue gas amount to the heat exchanger 9.

[0036] Specifically, the blending boiler 7 for inferior lignite usually generates excess and unstable flue gas amount, which brings huge environmental protection risks and hidden safety production hazards to the SCR denitration device 10 and other auxiliary machines. The system extracts this part of unstable excess flue gas amount through the bypass flue air blower 12, thereby ensuring the safe production operation of the SCR denitration device 10 and other auxiliary machines and reducing the environmental protection risks and hidden hazards. Moreover, the excess flue gas amount is conveyed to the coal mill 5 after being heat-exchanged by the heat exchanger 9.

[0037] The intelligent analysis device 11 stably controls the rated flue gas amount of the SCR denitration device 10, so as to give the SCR denitration device 10 the best flue gas amount.

[0038] The bypass flue air blower 12 is controlled to convey the excess flue gas amount heat-exchanged by the heat exchanger 9 to the coal mill 5;

[0039] Specifically, the boiler 7 for blending and burning low-quality lignite usually causes the problem of insufficient air output to the coal mill 5. The system delivers the excess flue gas after heat exchange through the heat exchanger 9 to the coal mill 5 through the bypass flue gas fan 12 to supplement the air output to the coal mill 5, thereby achieving the effect of flue gas circulation and improving the air output to the coal mill 5.

[0040] According to the rated heat of the lignite dryer 2, the heat exchange efficiency of the heat exchanger 9 and the condensate water flow delivered by the condensate water device are controlled.

[0041] The heat exchanger 9 is used to exchange heat with the condensate water to obtain high-temperature steam, and the high-temperature steam is delivered to the lignite dryer 2.

[0042] Specifically, the intelligent analysis device 11 controls the condensate water flow delivered by the condensate water device and the heat exchange efficiency of the heat exchanger 9 to ensure that the high-temperature steam flowing into the lignite dryer 2 can reach the rated heat of the lignite dryer 2.

[0043] The lignite dryer 2 is used to dry the low-quality lignite delivered by the low-quality lignite delivery device 1 with high-temperature steam, and then obtain low-temperature condensate water, which is delivered to the condensate water device.

[0044] Specifically, the heat exchanger 9 exchanges heat with the condensate water delivered by the condensate water device, and the condensate water after heat exchange through the heat exchanger 9 becomes high-temperature steam, which is delivered to the inside of the lignite dryer 2 to improve the temperature inside the lignite dryer 2, so that the lignite dryer 2 dries the low-quality lignite delivered by the low-quality lignite delivery device 1 to remove the moisture of the low-quality lignite, thereby achieving the purpose of upgrading the low-quality lignite. The high-temperature steam for drying the low-quality lignite in the lignite dryer 2 is converted into low-temperature condensate water, which is returned to the condensate water device again, thereby achieving the effect of water circulation.

[0045] In the above implementation process, the low-quality lignite dried by the lignite dryer 2 is burned in the blending boiler 7, and the flue gas generated by the burning of the blending boiler 7 is transported to the SCR denitration device 10. In the process of transporting the flue gas to the SCR denitration device 10, the intelligent analysis device 11 controls the bypass flue gas blower 12 to extract the excess flue gas amount exceeding the rated flue gas amount in the flue gas discharged by the blending boiler 7 and transport it to the heat exchanger 9 for heat exchange according to the rated flue gas amount of the SCR denitration device 10, which not only ensures the safe production and operation of the SCR denitration device 10 and other auxiliary machines, but also reduces the environmental protection risk. Then the bypass flue gas blower 12 transports the excess flue gas amount after heat exchange to the coal mill 5 to supplement the air volume output to the coal mill 5, thereby achieving the effect of flue gas circulation and improving the air volume transported to the coal mill 5. At the same time, in the process of drying the low-quality lignite by the lignite dryer 2, the intelligent analysis device 11 controls the condensate water flow rate of the condensate water device and the heat exchange efficiency of the heat exchanger 9 according to the rated heat of the lignite dryer 2 to ensure that the high-temperature steam flowing into the lignite dryer 2 can reach the rated heat of the lignite dryer 2. The heat exchanger 9 uses condensate water to exchange heat with the excess flue gas amount, and the condensate water after heat exchange in the heat exchanger 9 becomes high-temperature steam, which is transported to the inside of the lignite dryer 2 to improve the temperature inside the lignite dryer 2, so that the lignite dryer 2 dries the low-quality lignite transported by the low-quality lignite transporting device 1 to remove the moisture of the low-quality lignite, thereby achieving the purpose of upgrading the low-quality lignite. The high-temperature steam of the lignite dryer 2 drying the low-quality lignite is converted into low-temperature condensate water again and returns to the condensate water device, thereby achieving the effect of water circulation. The system indirectly uses the excess flue gas amount as a heat source through the lignite dryer 2, realizes the upgrading of low-calorific-value low-quality lignite, improves the combustion efficiency, achieves the effect of energy saving and consumption reduction, and protects the boiler body, the SCR denitration device 10 and the auxiliary machine system. At the same time, the extraction of excess flue gas amount for recirculation eliminates the safety risk and environmental protection risk of the SCR denitration device 10, effectively avoids the influence of large flue gas amount change on the SCR denitration device 10, and uses the excess flue gas amount to make up for the insufficient air volume transported to the coal mill 5 due to the large flue gas amount of low-quality lignite blending.

[0046] Among them, the blending boiler 7 is usually provided with an economizer 8, which is equivalent to a heat exchanger 9 attached to the blending boiler 7, and the flue gas discharged by the blending boiler 7 will finally be discharged through the economizer 8.

[0047] It should be noted that low-calorific-value lignite has the characteristics of low raw coal calorific value and high moisture content, and the core of upgrading is to remove the moisture of lignite and increase the corresponding calorific value. Generally, for every one percentage point of reduced moisture, the calorific value of lignite can be increased by 50-70 kilocalories per kilogram. In theory, if the internal and external moisture of lignite is removed by 100%, the calorific value of lignite can be increased by 2000-2800 kilocalories per kilogram.

[0048] Optionally, the dual-circulation stable combustion system of the mixed combustion boiler further comprises a coal mill blower 6, the coal mill blower 6 is connected with the intelligent analysis device 11 and the coal mill 5, and the intelligent analysis device 11 is further configured to control the coal mill blower 6 to deliver air to the coal mill 5.

[0049] Optionally, the intelligent analysis device 11 is further configured to calculate and control the air delivery amount of the coal mill blower 6 according to the amount of the excess flue gas after heat exchange.

[0050] Optionally, the intelligent analysis device 11 controls the air delivery amount of the coal mill blower 6 by controlling the power of the coal mill blower 6.

[0051] Specifically, the intelligent analysis device 11 controls the power of the coal mill blower 6 according to the amount of the excess flue gas after heat exchange, and then controls the air delivery amount of the coal mill blower 6 to the coal mill 5.

[0052] In some embodiments of the present embodiment, the total value of the air delivery amount of the coal mill blower 6 and the flue gas delivery amount of the bypass flue blower 12 needs to reach at least the air amount required by the coal mill 5. Specifically, according to the air amount required by the coal mill 5 and the flue gas delivery amount of the bypass flue blower 12, the intelligent analysis device 11 controls the air delivery amount of the coal mill blower 6 to the coal mill 5. Wherein, the air amount required by the coal mill 5 ≤ the flue gas delivery amount of the bypass flue blower 12 + the air delivery amount of the coal mill blower 6.

[0053] Optionally, a condensate water delivery pump 13 is arranged between the heat exchanger 9 and the condensate water device, and the condensate water delivery pump 13 is configured to pump the condensate water of the condensate water device to the heat exchanger 9.

[0054] Specifically, the condensate water of the condensate water device is delivered to the heat exchanger 9 by the condensate water delivery pump 13 for heat exchange.

[0055] In some embodiments of the present embodiment, the intelligent analysis device 11 controls the condensate water delivery amount of the condensate water delivery pump 13 by controlling the efficiency of the condensate water delivery pump 13, so as to meet the condensate water vapor temperature after heat exchange of the heat exchanger 9.

[0056] Optionally, a first valve 15 is arranged between the condensate water delivery pump 13 and the lignite dryer 2, and the first valve 15 is connected with the intelligent analysis device 11.

[0057] The first valve 15 is configured to guide the low-temperature condensate water discharged from the lignite dryer 2 to the condensate water delivery pump 13.

[0058] Specifically, the low-temperature condensate water generated by drying the low-quality lignite in the lignite dryer 2 can be directly delivered to the condensate water delivery pump 13 through the first valve 15, and then delivered to the heat exchanger 9 by the condensate water delivery pump 13.

[0059] Optionally, a second valve 16 is arranged between the cold end of the condensate device and the lignite dryer 2, a low-temperature heater 14 is arranged between the cold end of the condensate device and the hot end of the condensate device, a third valve 17 is arranged between the hot end of the condensate device and the condensate delivery pump 13, and the second valve 16 and the third valve 17 are connected to the intelligent analysis device 11.

[0060] The intelligent analysis device 11 is configured to control the opening degrees of the first valve 15, the second valve 16 and the third valve 17 according to the excess flue gas amount.

[0061] Specifically, the intelligent analysis device 11 can freely control the opening degrees of the first valve 15, the second valve 16 and the third valve 17. On one hand, the temperature of the condensate water entering the heat exchanger 9 from the hot end of the condensate device is controlled to ensure that high-temperature steam can be generated as a supplementary heat source when the excess flue gas amount is low. On the other hand, the temperature of the condensate water entering the heat exchanger 9 from the cold end of the condensate device or the condensate delivery pump 13 is controlled to ensure that the lignite dryer 2 can meet the demand when the excess flue gas amount is large, thereby further achieving the purpose of energy saving and consumption reduction. The different water temperatures and flow rates of the condensate water input into the heat exchanger 9 are controlled to ensure that the high-temperature steam input into the lignite dryer 2 reaches the rated heat.

[0062] In the embodiment, the intelligent analysis device 11 controls the water temperature of the condensate water by controlling the opening degrees of the first valve 15, the second valve 16 and the third valve 17, and there are two schemes as follows.

[0063] Scheme one: when the excess flue gas amount is large, the second valve 16 and the third valve 17 are closed, and the first valve 15 is opened. The low-temperature condensate water generated during the drying treatment of the lignite dryer 2 is delivered to the heat exchanger 9 by the condensate delivery pump 13 to realize water circulation. If the low-temperature condensate water delivered by the condensate delivery pump 13 is insufficient, the third valve 17 is opened.

[0064] Scheme two: when the excess flue gas amount is small, the first valve 15 is closed, and the low-temperature condensate water generated during the drying treatment of the lignite dryer 2 returns to the cold end of the condensate device. The condensate water is heated by the low-temperature heater 14 after flowing from the cold end of the condensate device to the hot end of the condensate device, and then is delivered to the heat exchanger 9 from the hot end of the condensate device through the condensate delivery pump 13.

[0065] It should be noted that the above scheme one and scheme two are only two schemes in the embodiment, and do not limit the selection of the control schemes of the first valve 15, the second valve 16 and the third valve 17.

[0066] Optionally, the dual-circulation stable combustion system of the mixed combustion boiler further comprises a design coal conveying device 3 and a mixed coal bin 4 connected with the coal mill 5, and the mixed coal bin 4 is connected with the lignite dryer 2 and the design coal conveying device 3.

[0067] The mixed coal bin 4 is used for mixing the high-quality coal conveyed by the design coal conveying device 3 with the poor-quality lignite dried by the lignite dryer 2 and then conveying the mixture to the coal mill 5.

[0068] Specifically, the high-quality coal conveyed by the design coal conveying device 3 is mixed with the poor-quality lignite dried by the lignite dryer 2 and then conveyed to the coal mill 5, and then the mixture is put into the mixed combustion boiler 7 for combustion, so that the combustion efficiency can be improved.

[0069] Optionally, the intelligent analysis device 11 controls the power of the bypass flue gas induced draft fan 12 to make the bypass flue gas induced draft fan 12 extract the excess flue gas.

[0070] Optionally, the mixed combustion boiler 7 is provided with a wind speed measuring device and a temperature measuring device at the flue gas discharge port, and the wind speed measuring device and the temperature measuring device are connected with the intelligent analysis device 11.

[0071] Specifically, the wind speed of the flue gas discharged by the mixed combustion boiler 7 is measured by the wind speed measuring device, and the temperature of the flue gas discharged by the mixed combustion boiler 7 is measured by the temperature measuring device. Then the measured wind speed and temperature are transmitted to the intelligent analysis device 11, so that the intelligent analysis device 11 calculates the flue gas discharge amount of the mixed combustion boiler 7 and then calculates the excess flue gas amount.

[0072] The above describes the optional embodiments of the present application in detail in combination with the drawings, but the embodiments of the present application are not limited to the specific details in the above embodiments. Within the technical concept range of the embodiments of the present application, the technical solutions of the embodiments of the present application can be variously modified, and these simple modifications all belong to the protection range of the embodiments of the present application. In addition, it should be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the embodiments of the present application will not be described again.

[0073] In addition, the various different embodiments of the present application can also be combined in any manner, as long as it does not deviate from the idea of the embodiments of the present application, and it should also be considered as the disclosed content of the embodiments of the present application.

Claims

1. A dual cycle combustion stabilization system for a fired boiler, comprising: The system comprises a lignite dryer, a condensate device, a poor-quality lignite conveying device, an intelligent analysis device, a heat exchanger, a bypass flue air blower, a coal mill, and an SCR denitration device in communication with the blending boiler, wherein the coal outlet of the coal mill is in communication with the coal inlet of the blending boiler; The intelligent analysis device is used for: According to the rated flue gas amount of the SCR denitration device, the bypass flue air blower is controlled to extract the excess flue gas amount exceeding the rated flue gas amount from the flue gas discharged by the blending boiler and convey it to the heat exchanger; The bypass flue air blower is controlled to convey the excess flue gas amount after heat exchange in the heat exchanger to the coal mill; According to the rated heat amount of the lignite dryer, the heat exchange efficiency of the heat exchanger and the condensate flow rate conveyed by the condensate device are controlled; The heat exchanger is used for heat exchange with condensate to obtain high-temperature steam, and the high-temperature steam is conveyed to the lignite dryer; The lignite dryer is used for drying the poor-quality lignite conveyed by the poor-quality lignite conveying device with the high-temperature steam to obtain low-temperature condensate, and the low-temperature condensate is conveyed to the condensate device; The blending boiler double-circulation stable combustion system further comprises a coal mill air blower, the coal mill air blower is connected with the intelligent analysis device and the coal mill, and the intelligent analysis device is further used for controlling the coal mill air blower to convey air volume to the coal mill.

2. The dual circulation flame stabilization system for a tangentially fired boiler of claim 1, wherein The intelligent analysis device is further used for calculating and controlling the air volume conveyed by the coal mill air blower according to the excess flue gas amount after heat exchange.

3. The dual circulation flame stabilization system for a tangentially fired boiler of claim 2, wherein The intelligent analysis device controls the air volume conveyed by the coal mill air blower by controlling the power of the coal mill air blower.

4. The dual circulation flame stabilization system for a tangentially fired boiler of claim 1, wherein A condensate conveying pump is arranged between the heat exchanger and the condensate device, and the condensate conveying pump is used for pumping the condensate from the condensate device to the heat exchanger.

5. The dual circulation flame stabilization system for a tangentially fired boiler of claim 4, wherein A first valve is arranged between the condensate conveying pump and the lignite dryer, and the first valve is connected with the intelligent analysis device. The first valve is used for guiding the low-temperature condensate discharged from the lignite dryer to the condensate conveying pump.

6. The dual circulation flame stabilization system for a tangentially fired boiler of claim 5, wherein A second valve is arranged between the cold end of the condensate device and the lignite dryer, a low-temperature heater is arranged between the cold end of the condensate device and the hot end of the condensate device, a third valve is arranged between the hot end of the condensate device and the condensate conveying pump, and the second valve and the third valve are connected with the intelligent analysis device. The intelligent analysis device is used for controlling the opening degrees of the first valve, the second valve and the third valve according to the excess flue gas amount.

7. The tangentially fired boiler dual circulation flame stabilization system according to claim 1, wherein Further comprising a design coal conveying device and a coal mixing bin connected with the coal mill, wherein the coal mixing bin is connected with the lignite dryer and the design coal conveying device; The coal mixing bin is used for mixing the high-quality coal conveyed by the design coal conveying device with the poor-quality lignite dried by the lignite dryer and then conveying the mixture to the coal mill.

8. The dual circulation flame stabilization system for a tangentially fired furnace as set forth in claim 1, wherein The intelligent analysis device controls the bypass flue air blower to extract the excess flue gas amount by controlling the power of the bypass flue air blower.

9. The dual circulation flame stabilization system for a tangentially fired furnace as set forth in claim 1, wherein The flue gas outlet of the mixed combustion boiler is provided with a wind speed measuring device and a temperature measuring device, and the wind speed measuring device and the temperature measuring device are connected with the intelligent analysis device.

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