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

Abstract

The invention provides a device and method for preparing briquette fuel from lignite by coupling coal-fired power plant steam, the device comprises a fluidized bed type dryer, a coal mill and a mixer, a heat source of the fluidized bed type dryer comes from the coal-fired power plant steam, and the coal mill grinds the dried lignite into pulverized coal; and feeding the pulverized coal into a boiler for combustion or a mixer to prepare finished coal. Heat of steam from a coal-fired power plant is fully utilized, carbon emission of unit calorific value fuel is reduced, and low-carbon emission reduction is achieved. The steam 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 steam 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 steam discharged from coal-fired power plants is usually not effectively utilized, and if it is discharged into the atmosphere, it will cause energy loss. Therefore, how to use the steam 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 with the steam 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] On one hand, an embodiment of the present invention proposes a device for preparing shaped fuel from lignite by coupling steam from a coal-fired power plant, comprising: a fluidized bed dryer, a coal mill and a mixer, wherein the fluidized bed dryer has a drying chamber and a wind chamber that are connected to each other, the top of the drying chamber has a feed inlet and an exhaust outlet, a heating coil is provided inside the drying chamber, steam from the coal-fired power plant is introduced into the heating coil, 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 the fan, 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 arranged at the discharge port of the wind chamber to grind the lignite dried by the fluidized bed dryer into coal powder. The coal discharge port of the coal mill is connected to the boiler to feed the coal powder into the 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 introduce 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 introduce 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] In some embodiments, the device for coupling the steam of a coal-fired power plant to prepare molded fuel from lignite also includes a dust collector, which separates the gas, water and coal powder discharged from the fluidized bed dryer. 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 dryer, the dust outlet of the dust collector is respectively connected to the second feed inlet of the mixer and the boiler, and the exhaust outlet of the dust collector is connected to the air inlet of the fan.

[0008] 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.

[0009] In some embodiments, a rotary feeder is connected to the feed inlet of the fluidized bed dryer, and the rotary feeder is located in the drying chamber.

[0010] In some embodiments, the device for preparing molded fuel from lignite by coupling steam from 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 a raw coal bin, and the discharge port of the raw coal crusher is connected to the feed port of a fluidized bed dryer.

[0011] In some embodiments, the device for coupling the steam of a coal-fired power plant to prepare molded fuel from lignite also includes a heat exchanger, wherein the heat exchanger has a tube side inlet, a tube side outlet, a shell side inlet and a shell side outlet, the tube side inlet is connected to the exhaust port of the dust collector, the tube side outlet is connected to the gas-water separator, the exhaust port of the gas-water separator is connected to the boiler to feed the separated gas into the boiler for combustion, condensate is introduced into the shell side inlet, the shell side outlet is connected to the shell side inlet through a circulation pipeline, and the circulation pipeline is connected to the first low-pressure heater to pass the condensate after heat exchange into the first low-pressure heater for utilization.

[0012] In some embodiments, the device for coupling the steam of a coal-fired power plant to prepare molded fuel from lignite also includes a steam turbine, the steam turbine having an air inlet and an air outlet, steam from the coal-fired power plant is introduced into the steam turbine through the air inlet of the steam turbine, the air outlet of the steam turbine is connected to the air inlet of the heating coil through an air inlet pipe, the air outlet of the heating coil is connected to the deaerator through an air outlet pipe, a branch pipe is connected to the circulation pipeline, the branch pipe is connected to the deaerator, and the branch pipe is connected to a second low-pressure heater so that the condensate after heat exchange can be passed into the second low-pressure heater for utilization.

[0013] In some embodiments, a bypass is connected to the air inlet pipe, and the bypass is connected to the air inlet of the air chamber.

[0014] Another embodiment of the present invention provides a method for preparing briquette fuel from lignite by coupling steam from a coal-fired power plant, using the above-mentioned device, including the following steps:

[0015] The lignite in the raw coal bin is crushed by the raw coal crusher and then enters the fluidized bed dryer. The steam from the coal-fired power plant is passed through the steam turbine to the heating coil in the fluidized bed dryer to heat and dry the crushed lignite. The fan is started to evenly distribute the heat in the fluidized bed dryer.

[0016] The dried lignite enters the coal mill and is ground into coal powder. A part of the coal powder is passed into the boiler for combustion, and the rest of the coal powder is passed into the mixer and fully mixed with the raw materials. It is then extruded into granular finished coal.

[0017] The gas, water and coal powder discharged from the fluidized bed dryer enter the dust collector for separation. Part of the separated coal powder is passed into the boiler for combustion, and the rest of the coal powder is passed into the mixer to participate in the preparation of finished coal. Part of the separated gas and water is passed into the heat exchanger to utilize the heat of the gas and water, and the rest of the gas and water is sent to the fluidized bed dryer through the fan for gas-water circulation.

[0018] The gas and water after heat exchange in the heat exchanger are passed into the gas-water separator, the separated dry gas is passed into the boiler for combustion, and the separated water is recovered.

[0019] In some embodiments, the raw materials include any one of asphalt and tar, any one of water or organic wastewater and an emulsifier, and the mass ratio between any one of asphalt and tar, any one of water and organic wastewater, emulsifier and coal powder is 0.5~2:0.2~1:0.004~0.02:10. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] 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.

[0021] in:

[0022] Figure 1 It is a schematic structural diagram of a device for preparing briquette fuel from lignite by coupling with steam from a coal-fired power plant in an embodiment of the present invention;

[0023] Reference numerals:

[0024] 1. Steam turbine; 2. Raw coal bunker; 3. Raw coal crusher; 4. Fluidized bed dryer; 41. Rotary feeder; 42. Heating coil; 43. Wind chamber; 5. Dust collector; 6. Coal mill; 7. Bypass; 8. Fan; 9. Mixer; 10. Agitator; 11. Extruder; 12. Heat exchanger; 13. Condensate pump; 14. First low-pressure heater; 15. Second low-pressure heater; 16. Gas-water separator. DETAILED DESCRIPTION

[0025] 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.

[0026] The following describes, with reference to the accompanying drawings, an apparatus and method for preparing shaped fuel from lignite by coupling with steam from a coal-fired power plant according to an embodiment of the present invention.

[0027] like Figure 1 As shown, an embodiment of the present invention proposes a device for preparing shaped fuel from lignite by coupling steam from a coal-fired power plant, comprising: a fluidized bed dryer 4, a coal mill 6 and a mixer 9, the fluidized bed dryer 4 having a drying chamber and a wind chamber 43 connected to each other, the top of the drying chamber having a feed inlet and an exhaust port, a heating coil 42 being provided inside the drying chamber, steam from the coal-fired power plant being introduced into the heating coil 42, the wind chamber 43 being located at the bottom of the drying chamber, the wind chamber 43 having an air inlet and an outlet, the air inlet of the wind chamber 43 being connected to the air outlet of the fan 8, the outlet of the wind chamber 43 being located at the bottom of the wind chamber 43 and being provided with an openable and closable gate.

[0028] The coal mill 6 is disposed at the discharge port of the wind chamber 43 to grind the lignite dried by the fluidized bed dryer 4 into coal powder. The coal discharge port of the coal mill 6 is connected to the boiler to feed the coal powder into the boiler for combustion.

[0029] The mixer 9 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 9. The second feed port is connected to the coal discharge port of the pulverizer 6 and is used to introduce coal powder into the mixer 9. The discharge port of the mixer 9 is provided with an extruder 11 to extrude the raw materials and coal powder into shape.

[0030] The embodiment of the present invention provides a fluidized bed dryer 4, a coal mill 6 and a mixer 9, so that the heat of the steam from the coal-fired power plant can be fully utilized, the carbon emission of the fuel per unit calorific value can be reduced, and low-carbon emission reduction can be achieved. The use of steam to heat and dry lignite can reduce the moisture content of lignite, increase the calorific value, and achieve higher efficiency when the coal-fired power plant mixes lignite. The lignite is ground into powder by the coal mill 6 and transported to the mixer 9 to prepare finished coal suitable for external transportation, which can reduce the transportation cost of lignite.

[0031] By providing the wind chamber 43, the heat distribution in the fluidized bed dryer 4 is uniform, so that the lignite can be dried faster and more uniformly.

[0032] Furthermore, a humidity monitoring device may be provided at the exhaust port of the fluidized bed dryer 4 to monitor the humidity of the exhaust gas. When the humidity reaches the required level, it indicates that the lignite in the fluidized bed dryer 4 has been dried. At this time, the gate of the air chamber 43 is opened to discharge the lignite into the coal mill 6.

[0033] In some embodiments, the device for preparing shaped fuel from lignite by coupling the steam of a coal-fired power plant also includes a dust collector 5, which separates the gas, water and coal powder discharged from the fluidized bed dryer 4. The dust collector 5 has an air inlet, a dust outlet and an exhaust port. The air inlet of the dust collector 5 is connected to the exhaust port of the fluidized bed dryer 4, and the dust outlet of the dust collector 5 is respectively connected to the second feed port of the mixer 9 and the boiler, and the exhaust port of the dust collector 5 is connected to the air inlet of the fan 8.

[0034] By setting up the dust collector 5, the gas-water discharged from the fluidized bed dryer 4 can be separated from the coal powder and reused separately, wherein the high-temperature gas-water can be used for heat exchange, and the heat is used for the low-pressure heater. The low-temperature gas-water after heat exchange is separated by the gas-water separator 16, and the obtained dry gas is mixed with the coal powder and carries the coal powder into the boiler for combustion, providing the power of pneumatic conveying, and the separated water is recycled. The high-temperature gas-water separated by the dust collector 5 can also be pressurized by the fan 8 and returned to the fluidized bed dryer 4 for circulation, so as to realize the bubbling fluidization of the lignite inside the fluidized bed dryer 4. The coal powder separated by the dust collector 5 can be passed into the boiler as fuel for combustion, and can also be passed into the mixer 9 to prepare finished coal.

[0035] Furthermore, the dust collector 5 is a cyclone dust collector or an electric dust collector.

[0036] In some embodiments, the first feed port of the mixer 9 is connected to the stirrer 10, and the stirrer 10 is suitable for stirring the raw materials evenly. The raw materials are put into the stirrer 10, stirred evenly, and then passed into the mixer 9 to be mixed with the coal powder.

[0037] In some embodiments, a rotary feeder 41 is connected to the feed inlet of the fluidized bed dryer 4, and the rotary feeder 41 is located in the drying chamber, so that the crushed lump lignite can be evenly dropped in the drying chamber.

[0038] In some embodiments, the device for preparing molded fuel from lignite by coupling the steam of a coal-fired power plant also includes a raw coal crusher 3, which has a feed port and a discharge port. The feed port of the raw coal crusher 3 is connected to the raw coal bin 2, and the discharge port of the raw coal crusher 3 is connected to the feed port of the fluidized bed dryer 4.

[0039] Crushing the raw coal into small pieces makes it easier to dry it thoroughly and grind it into powder before sending it to the boiler for combustion, which improves combustion efficiency and facilitates the preparation of finished coal.

[0040] In some embodiments, the device for coupling the steam of a coal-fired power plant to prepare molded fuel from lignite also includes a heat exchanger 12, which has a tube side inlet, a tube side outlet, a shell side inlet and a shell side outlet. The tube side inlet is connected to the exhaust port of the dust collector 5, and the tube side outlet is connected to the gas-water separator 16. The exhaust port of the gas-water separator 16 is connected to the boiler to send the separated gas into the boiler for combustion. The shell side inlet is introduced with condensate delivered by the condensate pump 13. The shell side outlet is connected to the shell side inlet through a circulation pipeline, and the circulation pipeline is connected to the first low-pressure heater 14 to pass the condensate after heat exchange into the first low-pressure heater 14 for utilization to achieve heat recovery.

[0041] In some embodiments, the device for preparing shaped fuel from lignite by coupling steam from a coal-fired power plant also includes a steam turbine 1, which has an air inlet and an air outlet. Steam from the coal-fired power plant is introduced into the steam turbine 1 through the air inlet of the steam turbine 1, and the air outlet of the steam turbine 1 is connected to the air inlet of the heating coil 42 through an air inlet pipe, and the air outlet of the heating coil 42 is connected to the deaerator through an air outlet pipe. A branch pipe is connected to the circulation pipeline, and the branch pipe is connected to the deaerator. The branch pipe is connected to a second low-pressure heater 15, so that the condensed water after heat exchange can be passed into the second low-pressure heater 15 for utilization, thereby realizing heat recovery.

[0042] In some embodiments, a bypass 7 is connected to the air inlet pipe, and the bypass 7 is connected to the air inlet of the air chamber 43 .

[0043] During the startup phase of the fluidized bed dryer 4, since the air-water circulation cannot be established, the steam delivered by the steam turbine 1 is directly sent to the wind chamber 43 of the fluidized bed dryer 4 by starting the bypass 7 to heat the drying chamber, and the material is gradually added to establish the circulation.

[0044] Furthermore, a valve is provided on the bypass 7 .

[0045] Another embodiment of the present invention provides a method for preparing briquette fuel from lignite by coupling steam from a coal-fired power plant, using the above-mentioned device, such as Figure 1 As shown, the following steps are included:

[0046] The lignite in the raw coal bin 2 is crushed by the raw coal crusher 3 and then enters the fluidized bed dryer 4. The steam of the coal-fired power plant is passed through the steam turbine 1 to the heating coil 42 in the fluidized bed dryer 4 to heat, dry and dehydrate the crushed lignite. The fan 8 is started to evenly distribute the heat in the fluidized bed dryer 4.

[0047] The dried lignite enters the coal mill 6 to be ground into coal powder. A part of the coal powder is passed into the boiler for combustion, and the rest of the coal powder is passed into the mixer 9 to be fully mixed with the raw materials, and then extruded into a granular finished coal by the extruder 11.

[0048] The gas-water and coal powder (gas-powder mixture) discharged from the fluidized bed dryer 4 enter the dust collector 5 for separation, a part of the separated coal powder is passed into the boiler for combustion, and the rest of the coal powder is passed into the mixer 9 to participate in the preparation of finished coal, a part of the separated gas-water is passed into the heat exchanger 12 to utilize the heat of the gas-water, and the rest of the gas-water is pressurized by the fan 8 and returned to the fluidized bed dryer 4 for gas-water circulation, thereby realizing the bubbling fluidization of the lignite inside the fluidized bed dryer 4.

[0049] The gas and water after heat exchange in the heat exchanger 12 are passed into the gas-water separator 16, the separated dry gas is passed into the boiler for combustion, and the separated water is recovered.

[0050] Through the above method, lignite is indirectly heated and dried by steam from top to bottom at a temperature of about 200°C. At the same time, the dried lignite is broken, a small part of which is collected by the dust collector 5 as coal powder, and most of the lignite is discharged from the bottom of the fluidized bed dryer 4. The moisture content of lignite can be reduced from 30-60% of the original raw coal to about 10%, and the volatile matter is almost not lost. The dried lignite is ground, a part of which is directly burned in the furnace, and 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.

[0051] Furthermore, the lignite is crushed by the raw coal crusher 3 to form lump coal with a particle size of less than 5 mm.

[0052] Furthermore, the temperature of the steam from the coal-fired power plant is 200-300°C. After heat exchange with the lignite in the fluidized bed dryer 4, the lignite is heated to 100-200°C, and the steam condenses into high-temperature water at 80-150°C. The high-temperature water is passed into the deaerator for deoxygenation and then recycled.

[0053] Furthermore, the coal powder ground by the coal mill 6 is transported to the boiler for combustion by pneumatic conveying.

[0054] Furthermore, the coal powder ground by the coal mill 6 enters the mixer 9 by means of a spiral feeder.

[0055] In some embodiments, the raw materials include any one of asphalt and tar, any one of water or organic wastewater, and an emulsifier, and the mass ratio between any one of asphalt and tar, any one of water and organic wastewater, and the emulsifier and coal powder is 0.5-2:0.2-1:0.004-0.02:10.

[0056] After being ground and separated by the dust collector 5, the coal powder is mixed evenly with asphalt / tar, water / organic wastewater, and emulsifier in this proportion, so that the micropores and active surfaces formed after the lignite is dried 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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 with steam from a coal-fired power plant, characterized in that: include: A fluidized bed dryer, wherein the fluidized bed dryer has a drying chamber and a wind chamber connected to each other, the top of the drying chamber has a feed inlet and an exhaust port, a heating coil is provided inside the drying chamber, steam from a coal-fired power plant is introduced into the heating coil, 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 the fan, 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 lignite dried by the fluidized bed dryer into coal powder, and the coal discharge port of the coal mill is connected to the boiler to feed the coal powder into the boiler for combustion; 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 coal powder into the mixer, and the discharge port of the mixer being provided with an extruder to extrude the raw materials and coal powder into shape.

2. The device for preparing briquette fuel from lignite by coupling with steam from a coal-fired power plant according to claim 1 is characterized in that: It also includes a dust collector, which separates the gas, water and coal powder discharged from the fluidized bed dryer. 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 dryer, the dust outlet of the dust collector is respectively connected to the second feed inlet of the mixer and the boiler, and the exhaust outlet of the dust collector is connected to the air inlet of the fan.

3. The device for preparing briquette fuel from lignite by coupling with steam 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 with steam from a coal-fired power plant according to claim 1 is characterized in that: The feed inlet of the fluidized bed dryer is connected with a rotary feeder, and the rotary feeder is located in the drying chamber.

5. The device for preparing briquette fuel from lignite by coupling with steam from 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 dryer.

6. The device for preparing briquette fuel from lignite by coupling with steam from a coal-fired power plant according to claim 2, characterized in that: It also includes a heat exchanger, which has a tube side inlet, a tube side outlet, a shell side inlet and a shell side outlet, the tube side inlet is connected to the exhaust port of the dust collector, the tube side outlet is connected to a gas-water separator, the exhaust port of the gas-water separator is connected to a boiler, so that the separated gas is sent to the boiler for combustion, condensate is introduced into the shell side inlet, the shell side outlet is connected to the shell side inlet through a circulation pipeline, and the circulation pipeline is connected to a first low-pressure heater, so that the condensate after heat exchange is introduced into the first low-pressure heater for utilization.

7. The device for preparing briquette fuel from lignite by coupling with steam from a coal-fired power plant according to claim 6 is characterized in that: It also includes a steam turbine, which has an air inlet and an air outlet. Steam from a coal-fired power plant is introduced into the steam turbine through the air inlet of the steam turbine. The air outlet of the steam turbine is connected to the air inlet of the heating coil through an air inlet pipe, and the air outlet of the heating coil is connected to a deaerator through an air outlet pipe. A branch pipe is connected to the circulation pipeline, and the branch pipe is connected to the deaerator. A second low-pressure heater is connected to the branch pipe to pass condensed water after heat exchange into the second low-pressure heater for use.

8. The device for preparing briquette fuel from lignite by coupling with steam from a coal-fired power plant according to claim 7, characterized in that: The air inlet pipe is connected with a bypass, and the bypass is connected to the air inlet of the air chamber.

9. A method for preparing briquette fuel from lignite by coupling steam 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 dryer. The steam from the coal-fired power plant is passed through the steam turbine into the heating coil in the fluidized bed dryer to heat and dry the crushed lignite. The fan is started to evenly distribute the heat in the fluidized bed dryer. The dried lignite is ground into coal powder in a coal mill. A portion of the coal powder is passed into a boiler for combustion, and the rest of the coal powder is passed into a mixer to be fully mixed with the raw materials. It is then extruded into granular finished coal by an extruder. The gas, water and coal powder discharged from the fluidized bed dryer are separated in a dust collector, a part of the separated coal powder is introduced into a boiler for combustion, and the rest of the coal powder is introduced into the mixer to participate in the preparation of finished coal, a part of the separated gas and water is introduced into a 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 dryer through a fan for gas-water circulation; The gas and water after heat exchange in the heat exchanger are passed into the gas-water separator, the separated dry gas is passed into the 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 0.5-2:0.2-1:0.004-0.02:10.

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