Device and method for preparing briquette fuel from lignite by coupling flue gas of coal-fired power plant

Abstract

The invention provides a device and a method for preparing briquette fuel from lignite by coupling flue gas of a coal-fired power plant, the device comprises a fluidized bed upgrading reactor, a coal mill, a mixer and a dust remover, a heat source of the fluidized bed upgrading reactor comes from the flue gas of a coal-fired boiler, the coal mill is arranged at a discharge port of an air chamber, and the mixer is arranged in the air chamber. The dust remover is used for separating gas and water discharged by the fluidized bed upgrading reactor from the pulverized coal, the dust remover is respectively connected with the mixer and the coal-fired boiler, and the mixer is used for preparing finished coal from the pulverized coal. According to the invention, flue gas from a coal-fired power plant is fully utilized, carbon emission of unit calorific value fuel is reduced, and low-carbon emission reduction is realized. The smoke is used for heating and drying the lignite, the moisture content of the lignite can be reduced, the heat value is increased, and higher efficiency is achieved when a coal-fired power plant burns the lignite in a blending mode. Lignite is ground into powder through the coal mill and conveyed into the mixer to prepare finished coal suitable for outward transportation, and the transportation cost of the lignite can be reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of lignite preparation and low-carbon emission reduction, and in particular to a device and method for preparing shaped fuel from lignite by coupling with flue gas from a coal-fired power plant. Background Art

[0002] Lignite is one of the four major types of coal in my country. In the lignite producing areas in northern my country and the southeastern coastal areas, lignite has become one of the main coals used for power generation due to its cost advantage. Although lignite has the advantage of low cost, it is expensive to transport inland due to its high moisture content, low calorific value, and flammability. In addition, the flue gas discharged from coal-fired power plants has a high heat content and is usually not effectively utilized. If it is discharged directly into the atmosphere, it will cause air pollution on the one hand and energy loss on the other. Therefore, how to use the flue gas discharged from coal-fired power plants to prepare finished coal with low moisture content, high calorific value, and suitable for external transportation is a topic that urgently needs to be studied. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems in the related art to a certain extent. To this end, the embodiment of the present invention provides a device and method for preparing shaped fuel from lignite by coupling the flue gas of a coal-fired power plant, which can not only achieve higher efficiency when the coal-fired power plant is mixed with lignite, but also prepare finished coal with low moisture content, high calorific value and suitable for external transportation, thereby reducing the carbon emission of fuel per unit calorific value.

[0004] In one aspect, an embodiment of the present invention proposes a device for preparing shaped fuel from lignite by coupling the flue gas of a coal-fired power plant, comprising: a fluidized bed upgrading reactor, a coal pulverizer, a mixer and a dust collector, wherein the fluidized bed upgrading reactor has a drying chamber and a wind chamber connected to each other, the drying chamber has a feed port and an exhaust port, the wind chamber is located at the bottom of the drying chamber, the wind chamber has an air inlet and an outlet, the air inlet of the wind chamber is connected to the air outlet of a fan, the fan transports the flue gas of the coal-fired boiler to the wind chamber, the outlet of the wind chamber is located at the bottom of the wind chamber and is provided with an openable and closable gate.

[0005] The coal mill is installed at the discharge port of the wind chamber to grind the lump lignite dried by the fluidized bed upgrading reactor into coal powder. The coal outlet of the coal mill is connected to the coal-fired boiler to feed the coal powder into the coal-fired boiler for combustion.

[0006] The mixer has a first feed port, a second feed port and a discharge port. The first feed port is used to feed raw materials for preparing finished coal into the mixer. The second feed port is connected to the coal discharge port of the coal mill and is used to feed coal powder into the mixer. The discharge port of the mixer is provided with an extruder to extrude the raw materials and coal powder into shape.

[0007] The dust collector separates the gas, water and coal powder discharged from the fluidized bed upgrading reactor. The dust collector has an air inlet, a dust outlet and an exhaust port. The air inlet of the dust collector is connected to the exhaust port of the fluidized bed upgrading reactor, the dust outlet of the dust collector is respectively connected to the second feed port of the mixer and the coal-fired boiler, and the exhaust port of the dust collector is connected to the air inlet of the fan.

[0008] In some embodiments, the feed inlet of the drying chamber is located near the wind chamber.

[0009] In some embodiments, the first feed port of the mixer is connected to a stirrer, and the stirrer is suitable for stirring the raw materials evenly.

[0010] In some embodiments, the device for preparing shaped fuel from lignite by coupling the flue gas of a coal-fired power plant also includes a raw coal crusher, which has a feed port and a discharge port. The feed port of the raw coal crusher is connected to the raw coal bin, and the discharge port of the raw coal crusher is connected to the feed port of the fluidized bed quality upgrading reactor.

[0011] In some embodiments, the device for coupling the flue gas of a coal-fired power plant to prepare shaped fuel from lignite also includes an air-to-air heat exchanger and an air-water separator. The air-to-air heat exchanger has a heat exchange inlet, a heat exchange outlet, a medium inlet and a medium outlet. The air-water separator has a liquid inlet, a drain outlet and an exhaust outlet. The heat exchange inlet is connected to the exhaust outlet of the dust collector, the heat exchange outlet is connected to the liquid inlet of the air-water separator, the medium inlet is connected to the exhaust outlet of the air-water separator, and the medium outlet is connected to the coal-fired boiler so that the separated gas can be heated by the air-to-air heat exchanger and then sent to the coal-fired boiler for combustion.

[0012] In some embodiments, the device for preparing shaped fuel from lignite by coupling the flue gas of a coal-fired power plant also includes a condensing heat exchanger, which is connected between the heat exchange outlet of the gas-to-gas heat exchanger and the liquid inlet of the gas-water separator through a pipeline.

[0013] In some embodiments, the dust collector is a cyclone dust collector.

[0014] In some embodiments, the gas-to-gas heat exchanger is a rotary heat exchanger.

[0015] Another embodiment of the present invention provides a method for preparing briquette fuel from lignite by coupling the flue gas of a coal-fired power plant, using the above-mentioned device, including the following steps:

[0016] The lignite in the raw coal bin is crushed by the raw coal crusher and then enters the fluidized bed upgrading reactor. The high-temperature flue gas of 300-500℃ is extracted from the tail flue of the coal-fired boiler, pressurized by the fan, and then sent into the fluidized bed upgrading reactor through the wind chamber to heat and dry the lignite.

[0017] The dried lignite is ground into coal powder in a coal mill. A portion of the coal powder is passed into a coal-fired boiler for combustion, and the rest of the coal powder is passed into a mixer to be fully mixed with the raw materials, and then extruded into granular finished coal through an extruder.

[0018] The gas, water and coal powder discharged from the fluidized bed upgrading reactor enter the dust collector for separation, a part of the separated coal powder is passed into the coal-fired boiler for combustion, the rest of the coal powder is passed into the mixer to prepare finished coal, a part of the separated gas and water is passed into the gas-to-gas heat exchanger to utilize the heat of the gas and water, and the rest of the gas and water is sent into the fluidized bed upgrading reactor through the fan for gas-water circulation.

[0019] The gas and water after heat exchange in the gas-to-gas heat exchanger are passed into the gas-water separator to separate the dry gas and water. The separated dry gas is returned to the gas-to-gas heat exchanger for heating. The heated dry gas is passed into the coal-fired boiler for combustion, and the separated water is recovered.

[0020] In some embodiments, the raw materials include any one of asphalt and tar, any one of water and organic wastewater, and an emulsifier, and the mass ratio between any one of asphalt and tar, any one of water or organic wastewater, emulsifier and coal powder is 0.5~2.5:0.4~2:0.004~0.02:10. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings.

[0022] in:

[0023] Figure 1 It is a schematic diagram of the structure of the device for preparing briquette fuel from lignite by coupling with the flue gas of a coal-fired power plant in an embodiment of the present invention;

[0024] Reference numerals:

[0025] 1. Coal-fired boiler; 2. Gas-water separator; 3. Condensing heat exchanger; 4. Gas-gas heat exchanger; 5. Raw coal bin; 6. Raw coal crusher; 7. Fluidized bed upgrading reactor; 71. Wind chamber; 8. Coal pulverizer; 9. Fan; 10. Dust collector; 11. Agitator; 12. Mixer; 13. Extruder. DETAILED DESCRIPTION

[0026] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0027] The following describes, with reference to the accompanying drawings, an apparatus and method for preparing shaped fuel from lignite by coupling with flue gas from a coal-fired power plant according to an embodiment of the present invention.

[0028] like Figure 1 As shown, an embodiment of the present invention proposes a device for preparing shaped fuel from lignite by coupling the flue gas of a coal-fired power plant, comprising: a fluidized bed upgrading reactor 7, a coal pulverizer 8, a mixer 12 and a dust collector 10, the fluidized bed upgrading reactor 7 has a drying chamber and a wind chamber 71 connected to each other, the drying chamber has a feed inlet and an exhaust port, the wind chamber 71 is located at the bottom of the drying chamber, the wind chamber 71 has an air inlet and a discharge port, the air inlet of the wind chamber 71 is connected to the air outlet of the fan 9, the fan 9 transports the flue gas of the coal-fired boiler 1 to the wind chamber 71, the discharge port of the wind chamber 71 is located at the bottom of the wind chamber 71 and is provided with an openable and closable gate.

[0029] The coal mill 8 is arranged at the discharge port of the wind chamber 71 to grind the lump lignite dried by the fluidized bed upgrading reactor 7 into coal powder. The coal outlet of the coal mill 8 is connected to the coal-fired boiler 1 to feed the coal powder into the coal-fired boiler 1 for combustion.

[0030] The mixer 12 has a first feed port, a second feed port and a discharge port. The first feed port is used to introduce raw materials for preparing finished coal into the mixer 12. The second feed port is connected to the coal discharge port of the pulverizer 8 and is used to introduce coal powder into the mixer 12. The discharge port of the mixer 12 is provided with an extruder 13 to extrude the raw materials and coal powder into shape.

[0031] The dust collector 10 separates the gas, water and coal powder discharged from the fluidized bed upgrading reactor 7. The dust collector 10 has an air inlet, a dust outlet and an exhaust port. The air inlet of the dust collector 10 is connected to the exhaust port of the fluidized bed upgrading reactor 7, the dust outlet of the dust collector 10 is respectively connected to the second feed port of the mixer 12 and the coal-fired boiler 1, and the exhaust port of the dust collector 10 is connected to the air inlet of the fan 9.

[0032] The embodiment of the present invention makes full use of the flue gas from the coal-fired power plant by setting a fluidized bed upgrading reactor 7, a coal mill 8 and a mixer 12, reduces the carbon emission of the fuel per unit calorific value, and achieves low-carbon emission reduction. The flue gas is used to heat and dry the lignite, which can reduce the moisture content of the lignite, increase the calorific value, and achieve higher efficiency when the coal-fired power plant mixes the lignite. The lignite is ground into powder by the coal mill 8 and transported to the mixer 12 to prepare finished coal suitable for external transportation, which can reduce the transportation cost of the lignite.

[0033] By setting a wind chamber 71 at the bottom of the drying chamber, on the one hand, a hot air flow from bottom to top is formed in the drying chamber to heat the lignite, providing power for the coal powder in the lignite to be discharged to the dust collector 10 through the exhaust port; on the other hand, the heat distribution in the fluidized bed upgrading reactor 7 can be uniform, so that the lignite can be dried faster and more evenly.

[0034] By setting up the dust collector 10, the gas-water discharged from the fluidized bed upgrading reactor 7 can be separated from the coal powder and used separately, wherein the high-temperature gas-water can be used for heat exchange and to provide power for pneumatic conveying, and the water obtained by further separation of the gas-water can be recycled. The high-temperature gas-water separated by the dust collector 10 can also be pressurized by the fan 9 and returned to the fluidized bed upgrading reactor 7 for circulation, so as to realize the fluidization of the lignite inside the fluidized bed upgrading reactor 7. The coal powder separated by the dust collector 10 can be introduced into the coal-fired boiler 1 as fuel for combustion, and can also be introduced into the mixer 12 to prepare finished coal.

[0035] Furthermore, a humidity monitoring device may be provided at the exhaust port of the fluidized bed upgrading reactor 7 to monitor the humidity of the exhaust gas. When the humidity reaches the required level, it indicates that the lignite in the fluidized bed upgrading reactor 7 has been dried. At this time, the gate of the wind chamber 71 is opened to discharge the lignite into the coal mill 8.

[0036] In some embodiments, the feed port of the drying chamber is located near the wind chamber 71. Since the exhaust port is located at the top of the fluidized bed upgrading reactor 7, the feed port is located away from the exhaust port, which can extend the movement distance of the coal powder, thereby extending the drying time and making the coal powder fully dry.

[0037] In some embodiments, the first feed port of the mixer 12 is connected to the stirrer 11, and the stirrer 11 is suitable for stirring the raw materials uniformly. A variety of raw materials are put into the stirrer 11, stirred uniformly, and then introduced into the mixer 12 to be mixed with coal powder.

[0038] In some embodiments, the device for preparing shaped fuel from lignite by coupling the flue gas of a coal-fired power plant also includes a raw coal crusher 6, which has a feed port and a discharge port. The feed port of the raw coal crusher 6 is connected to the raw coal bin 5, and the discharge port of the raw coal crusher 6 is connected to the feed port of the fluidized bed quality upgrading reactor 7.

[0039] The raw coal is broken into small pieces to facilitate full drying and subsequent grinding into powder and sent to the coal-fired boiler 1 for combustion, thereby improving combustion efficiency and facilitating the preparation of finished coal.

[0040] In some embodiments, the device for coupling the flue gas of a coal-fired power plant to prepare shaped fuel from lignite also includes an air-to-air heat exchanger 4 and an air-water separator 2. The air-to-air heat exchanger 4 has a heat exchange inlet, a heat exchange outlet, a medium inlet and a medium outlet. The air-water separator 2 has a liquid inlet, a drain outlet and an exhaust outlet. The heat exchange inlet is connected to the exhaust outlet of the dust collector 10, the heat exchange outlet is connected to the liquid inlet of the air-water separator 2, the medium inlet is connected to the exhaust outlet of the air-water separator 2, and the medium outlet is connected to the coal-fired boiler 1, so that the separated gas is heated by the air-to-air heat exchanger 4 and then sent to the coal-fired boiler 1 for combustion.

[0041] In some embodiments, the device for preparing shaped fuel from lignite by coupling the flue gas of a coal-fired power plant also includes a condensing heat exchanger 3, which is connected between the heat exchange outlet of the gas-to-gas heat exchanger 4 and the liquid inlet of the gas-water separator 2 through a pipeline.

[0042] In some embodiments, the dust collector 10 is a cyclone dust collector or an electric dust collector. Preferably, the cyclone dust collector has higher dust removal and separation efficiency.

[0043] In some embodiments, the gas-to-gas heat exchanger 4 is a rotary heat exchanger, which can meet the needs of heat exchange of a larger amount of flue gas.

[0044] Another embodiment of the present invention provides a method for preparing briquette fuel from lignite by coupling the flue gas of a coal-fired power plant, using the above-mentioned device, such as Figure 1 As shown, the following steps are included:

[0045] The lignite in the raw coal bin 5 is crushed by the raw coal crusher 6 and then enters the fluidized bed upgrading reactor 7. The high-temperature flue gas of 300-500°C is extracted from the tail flue of the coal-fired boiler 1, pressurized by the fan 9, and then sent to the fluidized bed upgrading reactor 7 through the wind chamber 71. Under the action of the high-temperature flue gas, the lignite is fluidized and dried and upgraded at the same time, releasing most of the water and a small amount of volatiles. The released volatiles react with a small amount of oxygen in the flue gas at high temperature to release heat, further providing the heat required for water vaporization and maintaining the temperature of the fluidized bed upgrading reactor 7.

[0046] The fully dried lump of lignite enters the coal mill 8 and is ground into coal powder. A portion of the coal powder is passed into the coal-fired boiler 1 for combustion, and the rest of the coal powder is passed into the mixer 12 and fully mixed with the raw materials. It is then extruded into a granular finished coal by the extruder 13.

[0047] The gas-water and coal powder discharged from the fluidized bed upgrading reactor 7 enter the dust collector 10 to separate the coal powder and the gas-water. A part of the separated coal powder is introduced into the coal-fired boiler 1 for combustion, and the rest of the coal powder is introduced into the mixer 12 to prepare finished coal. A part of the separated gas-water is introduced into the gas-to-gas heat exchanger 4 to utilize the heat of the gas-water, and the rest of the gas-water is mixed with the high-temperature flue gas discharged from the coal-fired boiler 1 and sent into the fluidized bed upgrading reactor 7 through the fan 9 for gas-water circulation, so as to enhance the fluidization of the lignite and adjust the oxygen content of the mixed gas.

[0048] The gas and water after heat exchange in the gas-to-gas heat exchanger 4 are passed into the gas-water separator 2 to separate the dry gas and water. The separated dry gas (temperature is 30-100°C) is returned to the gas-to-gas heat exchanger 4 for heating, i.e., heat exchange with the high-temperature gas and water separated by the dust collector 10. The temperature of the gas and water after heat exchange drops to 100-150°C. The heated dry gas (temperature is 200-300°C) is mixed with the pulverized coal and carried into the coal-fired boiler 1 for combustion, and the separated water is recovered.

[0049] Through the above method, lignite is fully dried and upgraded by fluidization and high-temperature flue gas in the fluidized bed upgrading reactor 7 at a temperature of 300-400°C. After drying and upgrading, the lignite is broken, most of which is formed into coal powder and collected by the dust collector 10, and a small amount of large-particle lignite is discharged from the bottom of the fluidized bed upgrading reactor 7. The moisture content of lignite can be reduced from 30-60% of the original raw coal to below 5%, while releasing some volatile matter and reacting with oxygen. A part of the lignite after drying and upgrading is directly put into the furnace for combustion, and the NOx concentration of the coal-fired boiler 1 is reduced by flue gas recirculation; the other part is used to prepare finished coal, which can greatly increase the density of the finished coal, reduce the risk of pulverization and spontaneous combustion during transportation, and facilitate external sales. Its characteristics can reach the level of bituminous coal.

[0050] Furthermore, the gas-water cooled by the gas-gas heat exchanger 4 enters the condensation heat exchanger 3, and is further cooled by the low-temperature condensed water of the unit to condense all the water, and then passes through the gas-water separator 2 to realize the recovery of water in the coal. The low-temperature condensed water in the condensation heat exchanger 3 is heated and returned to the unit for use to realize heat recovery.

[0051] Furthermore, the lignite is crushed by the raw coal crusher 6 to form lump coal with a particle size of less than 10 mm.

[0052] Furthermore, the coal powder ground by the coal mill 8 and the coal powder separated by the dust collector 10 are transported to the coal-fired boiler 1 by pneumatic conveying for combustion.

[0053] Furthermore, the coal powder ground by the coal mill 8 and the coal powder separated by the dust collector 10 enter the mixer 12 by means of a spiral feeder.

[0054] In some embodiments, the raw materials include any one of asphalt and tar, any one of water and organic wastewater, and an emulsifier, and the mass ratio between any one of asphalt and tar, any one of water or organic wastewater, emulsifier and coal powder is 0.5~2.5:0.4~2:0.004~0.02:10.

[0055] After the coal powder separated by the mill and dust collector 10 is evenly mixed with asphalt / tar, water / organic wastewater, and emulsifier in this proportion, the micropores and active surfaces formed after the lignite is dried and upgraded are blocked and passivated, and extruded under the bonding effect of asphalt / tar, which can greatly increase the density of the finished coal, reduce the risk of pulverization and spontaneous combustion during transportation, and facilitate external sales. Its characteristics can reach the level of bituminous coal. At the same time, it can also achieve coupled treatment of organic wastewater.

[0056] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0057] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0058] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0059] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0060] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0061] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A device for preparing briquette fuel from lignite by coupling the flue gas from a coal-fired power plant, characterized in that: include: A fluidized bed upgrading reactor, wherein the fluidized bed upgrading reactor has a drying chamber and a wind chamber connected to each other, the drying chamber has a feed port and an exhaust port, the wind chamber is located at the bottom of the drying chamber, the wind chamber has an air inlet and an outlet, the air inlet of the wind chamber is connected to the air outlet of a fan, the fan transports the flue gas of a coal-fired boiler to the wind chamber, the outlet of the wind chamber is located at the bottom of the wind chamber and is provided with an openable and closable gate; A coal mill, which is arranged at the discharge port of the wind chamber to grind the lump lignite dried by the fluidized bed upgrading reactor into coal powder, and the coal discharge port of the coal mill is connected to the coal-fired boiler to feed the coal powder into the coal-fired boiler for combustion; A dust collector, wherein the dust collector separates gas, water and coal powder discharged from the fluidized bed upgrading reactor, the dust collector has an air inlet, a dust outlet and an exhaust outlet, the air inlet of the dust collector is connected to the exhaust outlet of the fluidized bed upgrading reactor, and the exhaust outlet of the dust collector is connected to the air inlet of the fan; A mixer, the mixer having a first feed port, a second feed port and a discharge port, the first feed port being used to introduce raw materials for preparing finished coal into the mixer, the second feed port being connected to the coal discharge port of the coal mill and being used to introduce pulverized coal into the mixer, the discharge port of the mixer being provided with an extruder to extrude the raw materials and pulverized coal into shape, and the dust exhaust port of the dust collector being respectively connected to the second feed port of the mixer and the coal-fired boiler.

2. The device for preparing briquette fuel from lignite by coupling the flue gas of a coal-fired power plant according to claim 1 is characterized in that: The feed inlet of the drying chamber is located close to the wind chamber.

3. The device for preparing briquette fuel from lignite by coupling smoke from a coal-fired power plant according to claim 1 is characterized in that: The first feed inlet of the mixer is connected to a stirrer, and the stirrer is suitable for stirring the raw materials uniformly.

4. The device for preparing briquette fuel from lignite by coupling the flue gas of a coal-fired power plant according to claim 1 is characterized in that: It also includes a raw coal crusher, which has a feed port and a discharge port. The feed port of the raw coal crusher is connected to a raw coal bin, and the discharge port of the raw coal crusher is connected to the feed port of the fluidized bed upgrading reactor.

5. The device for preparing briquette fuel from lignite by coupling the flue gas of a coal-fired power plant according to claim 2 is characterized in that: It also includes an air-to-air heat exchanger and an air-water separator, the air-to-air heat exchanger has a heat exchange inlet, a heat exchange outlet, a medium inlet and a medium outlet, the air-water separator has a liquid inlet, a drain outlet and an exhaust outlet, the heat exchange inlet is connected to the exhaust outlet of the dust collector, the heat exchange outlet is connected to the liquid inlet of the air-to-water separator, the medium inlet is connected to the exhaust outlet of the air-to-water separator, and the medium outlet is connected to the coal-fired boiler so as to heat the separated gas through the air-to-air heat exchanger and then send it into the coal-fired boiler for combustion.

6. The device for preparing briquette fuel from lignite by coupling smoke from a coal-fired power plant according to claim 5 is characterized in that: It also includes a condensing heat exchanger, which is connected between the heat exchange outlet of the gas-to-gas heat exchanger and the liquid inlet of the gas-water separator through a pipeline.

7. The device for preparing briquette fuel from lignite by coupling smoke from a coal-fired power plant according to claim 2 is characterized in that: The dust collector is a cyclone dust collector.

8. The device for preparing briquette fuel from lignite by coupling smoke from a coal-fired power plant according to claim 5 is characterized in that: The gas-to-gas heat exchanger is a rotary heat exchanger.

9. A method for preparing briquette fuel from lignite by coupling the flue gas from a coal-fired power plant, characterized in that: Using the device according to any one of claims 1 to 8, comprising the following steps: The lignite in the raw coal bin is crushed by the raw coal crusher and then enters the fluidized bed upgrading reactor. The high-temperature flue gas of 300-500°C is extracted from the tail flue of the coal-fired boiler, pressurized by the fan, and then sent into the fluidized bed upgrading reactor through the wind chamber to heat and dry the lignite. The dried lump lignite enters the coal mill and is ground into coal powder. A portion of the coal powder is passed into the coal-fired boiler for combustion, and the rest of the coal powder is passed into the mixer and fully mixed with the raw materials, and then extruded into granular finished coal by an extruder. The gas, water and coal powder discharged from the fluidized bed upgrading reactor enter into a dust collector for separation, a portion of the separated coal powder is introduced into the coal-fired boiler for combustion, the rest of the coal powder is introduced into a mixer for preparing finished coal, a portion of the separated gas and water is introduced into an air-to-air heat exchanger to utilize the heat of the gas and water, and the rest of the gas and water is sent into the fluidized bed upgrading reactor through a fan for gas-water circulation; The gas and water after heat exchange in the gas-to-gas heat exchanger are passed into the gas-water separator to separate dry gas and water, the separated dry gas is returned to the gas-to-gas heat exchanger for heating, the heated dry gas is passed into the coal-fired boiler for combustion, and the separated water is recovered.

10. The method according to claim 9, characterized in that The raw materials include any one of asphalt and tar, any one of water and organic wastewater, and an emulsifier. The mass ratio of any one of asphalt and tar, any one of water or organic wastewater, emulsifier and coal powder is 0.5-2.5:0.4-2:0.004-0.02:10.

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