A coal gasification plant heat recovery system and method

Abstract

The embodiment of the present application discloses a coal gasification device heat recovery system and method, which comprises a coal mill, a pulverized coal filter, a circulating fan, a heat exchanger and a hot blast stove; a flue gas heat exchange channel, an air preheating channel and an inert gas preheating channel are arranged separately in the heat exchanger, heat recovery of the vent air is realized through the flue gas heat exchange channel, and the air and the inert gas are heated through the air preheating channel and the inert gas preheating channel, so that efficient heat exchange is realized, heat is reasonably distributed, energy utilization is significantly improved, equipment maintenance cost is reduced, equipment service life is prolonged, and good economic and environmental benefits are obtained.

Description

Technical Field

[0001] This invention relates to the field of coal gasification technology, and in particular to a heat recovery system and method for a coal gasification device. Background Technology

[0002] Coal gasification is one of the core technologies of modern coal chemical industry and clean energy utilization. Its coal grinding system is responsible for grinding raw coal into pulverized coal that meets the requirements for gasification, and maintaining the airflow and drying process through circulating fans, inert gas generators, etc. For the fluidized bed gasification method with dry powder feed, the stable control of the moisture content of pulverized coal is a key technical point. Too high, too low, or excessively fluctuating moisture content of pulverized coal will adversely affect the gasification reaction. Too high moisture content will reduce the fluidity of pulverized coal, affecting its transportation and distribution in the gasifier, thereby reducing gasification efficiency and increasing energy consumption; too low moisture content may cause static electricity and dust to be generated during storage and transportation, posing safety hazards. At the same time, the drying process requires more energy, and too low moisture content will reduce the output of the coal mill and increase the operating load of the equipment; excessively large fluctuations in moisture content can easily cause pipeline bridging, and in severe cases, lead to pipeline coal interruption and trigger interlock shutdown. Therefore, controlling the moisture content of the pulverized coal discharged from the coal grinding system is crucial.

[0003] A common method for controlling the moisture content in coal pulverizing systems is to split the inert gas separated by a pulverized coal bag filter into two streams after passing through a circulating fan. One stream is vented, while the other is heated in an inert gas generator and recycled. Simultaneously, nitrogen is added to ensure the inert gas dew point remains within the required range. While this method reduces the moisture content in the system by releasing the moisture-containing circulating gas (approximately 20%) into the atmosphere, it also wastes a significant amount of low-grade heat energy (approximately 105°C), reducing overall energy efficiency and increasing the energy consumption required for heating and replenishing nitrogen. Given the current emphasis on energy conservation, emission reduction, and improved energy efficiency, this heat loss urgently needs to be addressed. Developing a system capable of effectively recovering heat from the vented gas is crucial for reducing the overall energy consumption of coal pulverizing systems in coal gasification plants.

[0004] Currently, energy recovery technologies in the coal gasification field mainly focus on the sensible heat recovery of high-temperature syngas (such as waste heat boilers) and the utilization of waste heat from water circulation systems. However, efficient, reliable, and economical heat recovery technologies for the vent gas generated by coal milling and drying systems, which has a relatively low temperature and contains high humidity and a small amount of dust, are relatively lacking. This portion of heat is often considered "low-value heat" or difficult to recover (easily corroded or clogged), and is usually directly emitted without effective recovery, resulting in energy waste. Summary of the Invention

[0005] The purpose of this invention is to provide a heat recovery system and method for a coal gasification device, so as to at least partially solve the above-mentioned problems of the prior art.

[0006] To achieve the above objectives, one aspect of the present invention provides a heat recovery system for a coal gasification device, comprising: a coal mill, a pulverized coal filter, a circulating fan, a heat exchanger, and a hot air furnace; wherein... The coal mill is connected to the pulverized coal filter and outputs a mixture of pulverized coal and gas to the pulverized coal filter; The pulverized coal filter is connected to the circulating fan to perform gas-solid separation on the mixture, output the filtered pulverized coal, and output the filtered gas to the circulating fan; The circulating fan is connected to the heat exchanger and the hot air furnace, outputting a first portion of filtered gas to the heat exchanger and a second portion of filtered gas to the hot air furnace; The heat exchanger is connected to the hot air furnace, vents the first portion of filtered gas, and outputs inert gas and air after heat exchange to the hot air furnace; the heat exchanger includes a flue gas heat exchange channel, an air preheating channel, and an inert gas preheating channel arranged separately; the flue gas heat exchange channel is used to perform heat exchange and cooling treatment on the first portion of filtered gas, the air preheating channel is used to perform heat exchange and heating treatment on the input air, and the inert gas preheating channel is used to perform heat exchange and heating treatment on the input inert gas. The hot air furnace is connected to the coal mill and the external fuel gas pipeline, and outputs hot air to the coal mill.

[0007] Preferably, the heat exchanger includes a heat pipe heat exchanger, and the channels of the heat pipe heat exchanger are isolated to form the flue gas heat exchange channel, the air preheating channel, and the inert gas preheating channel.

[0008] Preferably, the heat pipe heat exchanger includes a base tube, fins, a purge pipe, a first air inlet, a second air inlet, a third air inlet, a first exhaust port, a second exhaust port, a third exhaust port, and a water collection tank, wherein... The base tube is a heat exchange tube body, and the direction of the pipe is orthogonal to the direction of the flue gas heat exchange channel, the air preheating channel, and the inert gas preheating channel; The fins are fixedly disposed on the outer wall of the base tube; The purging pipe is installed in the dust removal area of ​​the heat exchanger to remove dust adhering to the surface of the fins and between the tube bundles of the base tube; The first air inlet is connected to the circulating fan, and the first exhaust port is used to release the gas to the atmosphere; The second air inlet is used to input the inert gas, and the second exhaust port is connected to the hot air furnace; The third air inlet is used to input the air, and the third exhaust outlet is connected to the hot air furnace; The water collection tank is located at the bottom of the heat pipe heat exchanger.

[0009] Preferably, the heat pipe heat exchanger further includes a cold-side access door and a hot-side access door.

[0010] Preferably, the heat pipe heat exchanger includes multiple sets of heat pipes, with odd-numbered sets of heat pipes and even-numbered sets of heat pipes arranged sequentially along the channel direction; wherein, the odd-numbered sets of heat pipes are concentrated in the center of the channel and spaced apart from the channel sidewall by a first distance; each even-numbered set of heat pipes is divided into two sub-groups, which are respectively arranged close to the two sides of the channel and spaced apart from each other by a second distance.

[0011] Preferably, each group of heat exchange tubes is connected to a pulse vibration pump, which triggers automatic vibration and dust removal through differential pressure.

[0012] Preferably, the second air inlet is connected to a dilution fan.

[0013] Preferably, the third air inlet is connected to a blower.

[0014] Another aspect of the present invention provides a method for heat recovery in a coal gasification unit, applied to the heat recovery system of a coal gasification unit provided in the above aspects and any preferred embodiments thereof, comprising: The pulverized coal filter filters the mixture of pulverized coal and gas output from the coal mill, outputting filtered pulverized coal and outputting filtered gas to the circulating fan. The circulating fan outputs the first part of the filtered gas to the heat exchanger and the second part of the filtered gas to the hot blast furnace. The first part of filtered gas is cooled by heat exchange through the flue gas heat exchange channel of the heat exchanger, and the treated gas is released into the atmosphere. The inert gas is heated by heat exchange through the inert gas preheating channel of the heat exchanger, and the treated inert gas is then transported to the hot air furnace. The input air is heated by heat exchange through the air preheating channel of the heat exchanger, and the heated air is then delivered to the hot air furnace. The hot blast furnace receives the inert gas, the atmosphere, and the fuel gas, and generates and outputs hot air to the coal mill.

[0015] Preferably, the temperature of the gas after filtration in the first part is about 105°C, which is reduced to 65°C after heat exchange treatment.

[0016] Compared with the prior art, the present invention has at least the following advantages: The heat exchanger is equipped with separate flue gas heat exchange channels, air preheating channels, and inert gas preheating channels. The flue gas heat exchange channels recover heat from the released air, while the air and inert gas preheating channels raise the temperature of the air and inert gas. This achieves efficient heat exchange, rational heat distribution, significantly improves energy utilization, reduces equipment maintenance costs, and extends equipment lifespan, resulting in good economic and environmental benefits. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of a heat recovery system for a coal gasification device provided in an embodiment of the present invention.

[0018] Figure 2 This diagram shows a side view of the heat pipe heat exchanger provided in an embodiment of the present invention.

[0019] Figure 3 The diagram shows a top view of the heat pipe heat exchanger provided in an embodiment of the present invention.

[0020] Figure 4 This is a schematic flowchart of a heat recovery method for a coal gasification device provided in an embodiment of the present invention. Detailed Implementation

[0021] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0022] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be used interchangeably where appropriate to understand the embodiments of the invention described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a product or device comprising a series of units is not necessarily limited to those explicitly listed, but may include other units not explicitly listed or inherent to such product or device.

[0023] In this invention, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing the invention and its embodiments, and are not intended to limit the indicated devices, elements, or components to having a specific orientation, or to be constructed and operated in a specific orientation.

[0024] Furthermore, in addition to indicating direction or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in certain situations to indicate a dependency or connection. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0025] Furthermore, the terms "installation," "setup," "equipped with," "connection," "joint," and "socket" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this invention according to the specific circumstances.

[0026] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0027] Example 1 This invention provides a heat recovery system for a coal gasification device. Figure 1 A schematic diagram of the system structure is shown, such as... Figure 1 As shown, the system includes: a coal mill 10, a pulverized coal filter 20, a circulating fan 30, a heat exchanger 40, and a hot air furnace 50; wherein... The coal mill 10 is connected to the pulverized coal filter 20 and outputs a mixture including pulverized coal and gas to the pulverized coal filter 20; The pulverized coal filter 20 is connected to the circulating fan 30 to perform gas-solid separation on the mixture, output the filtered pulverized coal, and output the filtered gas to the circulating fan 30; The circulating fan 30 is connected to the heat exchanger 40 and the hot air furnace 50, outputting a first portion of filtered gas to the heat exchanger 40 and a second portion of filtered gas to the hot air furnace 50; The heat exchanger 40 is connected to the hot air furnace 50, vents the first part of filtered gas, and outputs inert gas and air after heat exchange to the hot air furnace 50; the heat exchanger 40 includes a flue gas heat exchange channel, an air preheating channel, and an inert gas preheating channel arranged separately; the flue gas heat exchange channel is used to perform heat exchange and cooling treatment on the first part of filtered gas, the air preheating channel is used to perform heat exchange and heating treatment on the input air, and the inert gas preheating channel is used to perform heat exchange and heating treatment on the input inert gas. The hot air furnace 50 is connected to the coal mill 10 and the external fuel gas pipeline, and outputs hot air to the coal mill.

[0028] Among them, heat exchangers include heat pipe heat exchangers, plate heat exchangers, and other types of heat exchangers.

[0029] Figure 2 A side view of the heat pipe heat exchanger is shown. Figure 3 This is a top view schematic diagram of a heat pipe heat exchanger. (Reference) Figure 2 and Figure 3 As shown, the heat pipe heat exchanger is divided into a flue gas heat exchange channel, an air preheating channel, and an inert gas preheating channel.

[0030] The heat pipe heat exchanger includes a base tube 11, fins 12, a purge pipe 13, a first air inlet 21, a second air inlet 22, a third air inlet 23, a first exhaust port 31, a second exhaust port 32, a third exhaust port 33, and a water collection tank (not shown in the figure). The base tube 11 is a heat exchange tube body, and the direction of the tube is orthogonal to the direction of the flue gas heat exchange channel, the air preheating channel, and the inert gas preheating channel.

[0031] The fins 12 are fixedly disposed on the outer wall of the base tube; The purge pipe 13 is located in the dust removal area of ​​the heat exchanger and is used to remove dust adhering to the surface of the fins and between the tube bundles of the base tube. The first air inlet 21 is connected to the circulating fan 30, and the first exhaust port 31 is used to release the gas to the atmosphere; The second air inlet 22 is used to input the inert gas, and the second exhaust port 32 is connected to the hot air furnace; The third air inlet 23 is used to input the air, and the third exhaust outlet 33 is connected to the hot air furnace; The water collection tank is located at the bottom of the heat pipe heat exchanger.

[0032] In a preferred embodiment, the heat pipe heat exchanger further includes a cold-side access door and a hot-side access door.

[0033] The heat pipe heat exchanger may include multiple sets of heat pipes, with odd-numbered sets of heat pipes and even-numbered sets of heat pipes arranged sequentially along the channel direction; wherein, the odd-numbered sets of heat pipes are concentrated in the center of the channel and spaced apart from the channel sidewall by a first distance; each even-numbered set of heat pipes is divided into two sub-groups, which are respectively arranged close to the two sides of the channel and spaced apart from each other by a second distance.

[0034] Each heat exchange tube can also be connected to a pulse vibration pump, which can automatically vibrate and clean dust by pressure differential triggering.

[0035] In a preferred embodiment, the second air inlet is connected to a dilution fan.

[0036] In a preferred embodiment, the third air inlet is connected to a blower.

[0037] The following specific example illustrates the heat recovery system of the coal gasification device provided in the embodiments of the present invention.

[0038] In this example: The base tube 11 is the main heat exchange tube of the heat pipe heat exchanger. It is made of Q235B steel and has an anti-corrosion coating on its outer surface. It is connected to the fins 12 by welding. The base tube 11 is used to carry the heat transfer between the evaporation section and the condensation section of the working fluid in the heat pipe and to realize the heat exchange between the hot side air and the cold side preheating medium.

[0039] Fins 12 are disposed on the outer wall of the base tube 11 and are made of aluminum. They are preferably fixedly connected to the base tube 11 by high-frequency welding to expand the heat exchange area and improve the heat exchange efficiency.

[0040] The purge pipe 13 is located in the cleaning area of ​​the heat exchanger, preferably corresponding to each group of heat exchange tubes, and is connected to a pulse vibration pump, pulse air source, or cleaning pipeline. The purge pipe 13 can be connected to the heat exchanger shell by flange or welding, and is used to apply cleaning airflow or vibration to the heat exchange tube bundle when the pressure difference increases or during timed control, so as to remove dust deposits adhering to the fin surface and between the tube bundles.

[0041] The air inlet 21 is connected to the air vent pipe of the coal mill unit. The preferred connection method is flange connection. It is used to introduce the humid and dusty vent air with a temperature of about 105℃ into the hot side of the heat pipe heat exchanger and distribute it evenly into the heat exchange area under the action of the guide plate.

[0042] The air inlet 22 is connected to the outlet pipe of the combustion air blower, preferably by a flange connection, to introduce the air to be preheated into the cold side of the heat pipe heat exchanger so that it absorbs heat and is then sent to the subsequent process unit.

[0043] The air inlet 23 is connected to the outlet pipe of the dilution fan, preferably by a flange connection, to introduce atmospheric pressure nitrogen or diluted nitrogen into the cold side of the heat exchanger, where it exchanges heat with the heat pipe and is then heated and returned to the system, reducing subsequent heating energy consumption.

[0044] The exhaust port 31 is connected to the vent pipe, preferably by a flange connection, and is used to discharge the vent air, which has been cooled to about 65°C after heat recovery, to the atmosphere or a subsequent vent system.

[0045] The exhaust port 32 is connected to the downstream pipeline after the air is preheated. The connection method is preferably flange connection. It is used to output the heated air for use in the inert gas generator to preheat the combustion air or other process steps that require preheated air.

[0046] The exhaust port 33 is connected to the downstream pipeline of diluted nitrogen, preferably by a flange connection, and is used to output the nitrogen after heat exchange and heating, and send it back to the coal pulverizing system or the inert gas circulation system.

[0047] The water collection tank is located at the bottom of the heat exchanger. It is preferably a receiving type water collection tank, which is welded to the drain port below. It is used to collect condensate and clean water formed by air condensation. The drain port below is welded to the bottom to periodically or continuously discharge condensate and some deposited dirt, so as to avoid the accumulation of dirt inside the heat exchanger and cause corrosion, blockage or heat exchange attenuation.

[0048] The heat recovery process of the coal gasification device heat recovery system provided in this embodiment of the invention includes: The vented air at approximately 105°C enters the heat exchanger evenly under the action of the baffles. During the flue gas flow, heat is absorbed by the evaporation section of the heat pipe, and the temperature drops to approximately 65°C before being discharged from the side and then into the vent pipe for atmospheric venting. Simultaneously, moisture in the flue gas condenses on the surface of the heat pipe, flows along the pipe wall into the bottom water collection tank, and is discharged into the sewage pipe through the drain outlet. The entire process is continuous, handling an air volume of up to 40,000 Nm³ / h, with a heat recovery rate consistently above 65%. Air from the combustion air blower and dilution fan outlets, along with atmospheric pressure nitrogen, enters the heat pipe heat exchanger. After being evenly distributed by the baffles, it comes into contact with the heat pipes, absorbs heat, and then re-enters the system. The entire process is continuous, reducing the energy consumption required for heating the hot blast furnace.

[0049] In this embodiment of the invention, a flue gas heat exchange channel, an air preheating channel, and an inert gas preheating channel are separately arranged inside the heat exchanger. The flue gas heat exchange channel recovers heat from the released air, and the air and inert gas are heated by the air and inert gas preheating channels, thereby achieving efficient heat exchange, rationally distributing heat, significantly improving energy utilization, reducing equipment maintenance costs, and extending equipment service life, resulting in good economic and environmental benefits.

[0050] Example 2 Embodiment 2 of the present invention provides a method for heat recovery in a coal gasification unit, applicable to the heat recovery system of the coal gasification unit provided in Embodiment 1 and any of its optional embodiments. Figure 4 A flowchart illustrating this method is shown below. (Refer to...) Figure 4 As shown, the method includes: Step 401: The mixture of pulverized coal and gas output from the coal mill is filtered through the pulverized coal filter, and the filtered pulverized coal is output, and the filtered gas is output to the circulating fan; Step 402: The first part of the filtered gas is output to the heat exchanger through the circulating fan, and the second part of the filtered gas is output to the hot air furnace. Step 403: The first part of filtered gas is cooled by heat exchange through the flue gas heat exchange channel of the heat exchanger, and the treated gas is released into the atmosphere. Step 404: The input inert gas is heated by heat exchange through the inert gas preheating channel of the heat exchanger, and the treated inert gas is then transported to the hot air furnace. Step 405: The input air is heated by heat exchange through the air preheating channel of the heat exchanger, and the treated air is delivered to the hot air furnace. Step 406: The inert gas, the atmosphere, and the fuel gas are received through the hot blast stove to generate and output hot air to the coal mill.

[0051] Preferably, the temperature of the gas after filtration in the first part is about 105°C, which is reduced to 65°C after heat exchange treatment.

[0052] Combination Figure 1-3In this embodiment of the invention, raw coal enters a coal mill, where it is pulverized, dried, and mixed to form a mixture of pulverized coal and inert gas carrying the pulverized coal, meeting gasification requirements. This mixture then enters a pulverized coal bag filter via a pipeline. The pulverized coal bag filter performs gas-solid separation on the gas-solid mixture, outputting qualified pulverized coal product, and sends the separated inert gas to a circulating fan. The circulating fan transports the inert gas separated by the bag filter to the hot side of the heat pipe heat exchanger, where a portion of the gas is treated as venting air, and the other portion is recycled according to system needs. The venting air, at approximately 105°C, enters the hot side of the heat pipe heat exchanger evenly through inlet 21 under the action of a guide plate. After the heat is absorbed by the heat pipe evaporation section, the temperature of the venting air drops to approximately 65°C, and then it is discharged through outlet 31 and enters the vent pipe to be discharged into the atmosphere. During the cooling process... In the heat pipe system, moisture in the released air condenses on the surface of the heat pipe, flows along the pipe wall into the bottom water collection tank, and is discharged into the sewage pipe through the drain outlet. Air from the air blower outlet enters the cold side of the heat pipe heat exchanger through the air inlet 22, absorbs heat and rises in temperature during the heat exchange process, and is then output through the exhaust outlet 32 ​​for preheating of combustion air in the inert gas generator or related process applications. Atmospheric pressure nitrogen from the dilution blower outlet enters the cold side of the heat pipe heat exchanger through the air inlet 23, rises in temperature after contacting the heat pipe surface, is output through the exhaust outlet 33 and re-enters the coal grinding system or dilution gas circuit to reduce the subsequent heating load. When the pressure difference inside the heat pipe heat exchanger reaches a preset threshold, the ash removal system is activated, automatically cleaning the tube bundle through a pulse vibration pump, purge pipe 13, or an equivalent ash removal mechanism. If necessary, manual cleaning and maintenance can be performed through the inspection door to ensure long-term efficient operation.

[0053] Compared with the prior art, the present invention has at least the following advantages: The heat exchanger is equipped with separate flue gas heat exchange channels, air preheating channels, and inert gas preheating channels. The flue gas heat exchange channels recover heat from the released air, while the air and inert gas preheating channels raise the temperature of the air and inert gas. This achieves efficient heat exchange, rational heat distribution, significantly improves energy utilization, reduces equipment maintenance costs, and extends equipment lifespan, resulting in good economic and environmental benefits.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A heat recovery system for a coal gasification unit, characterized in that, include: Coal mill, pulverized coal filter, circulating fan, heat exchanger, and hot air furnace; in The coal mill is connected to the pulverized coal filter and outputs a mixture of pulverized coal and gas to the pulverized coal filter; The pulverized coal filter is connected to the circulating fan to perform gas-solid separation on the mixture, output the filtered pulverized coal, and output the filtered gas to the circulating fan; The circulating fan is connected to the heat exchanger and the hot air furnace, outputting a first portion of filtered gas to the heat exchanger and a second portion of filtered gas to the hot air furnace; The heat exchanger is connected to the hot air furnace, vents the first portion of filtered gas, and outputs inert gas and air after heat exchange to the hot air furnace; the heat exchanger includes a flue gas heat exchange channel, an air preheating channel, and an inert gas preheating channel arranged separately; the flue gas heat exchange channel is used to perform heat exchange and cooling treatment on the first portion of filtered gas, the air preheating channel is used to perform heat exchange and heating treatment on the input air, and the inert gas preheating channel is used to perform heat exchange and heating treatment on the input inert gas. The hot air furnace is connected to the coal mill and the external fuel gas pipeline, and outputs hot air to the coal mill.

2. The heat recovery system for a coal gasification unit according to claim 1, characterized in that, The heat exchanger includes a heat pipe heat exchanger, and the channels of the heat pipe heat exchanger are isolated to form the flue gas heat exchange channel, the air preheating channel, and the inert gas preheating channel.

3. The heat recovery system for a coal gasification unit according to claim 2, characterized in that, The heat pipe heat exchanger includes a base tube, fins, a purge pipe, a first air inlet, a second air inlet, a third air inlet, a first exhaust port, a second exhaust port, a third exhaust port, and a water collection tank. The base tube is a heat exchange tube body, and the direction of the pipe is orthogonal to the direction of the flue gas heat exchange channel, the air preheating channel, and the inert gas preheating channel; The fins are fixedly disposed on the outer wall of the base tube; The purging pipe is installed in the dust removal area of ​​the heat exchanger to remove dust adhering to the surface of the fins and between the tube bundles of the base tube; The first air inlet is connected to the circulating fan, and the first exhaust port is used to release the gas to the atmosphere; The second air inlet is used to input the inert gas, and the second exhaust port is connected to the hot air furnace; The third air inlet is used to input the air, and the second exhaust port is connected to the hot air furnace; The water collection tank is located at the bottom of the heat pipe heat exchanger.

4. The heat recovery system for a coal gasification unit according to claim 3, characterized in that, The heat pipe heat exchanger also includes a cold-side access door and a hot-side access door.

5. The heat recovery system for a coal gasification unit according to any one of claims 1-4, characterized in that, The heat pipe heat exchanger includes multiple sets of heat pipes, with odd-numbered sets of heat pipes and even-numbered sets of heat pipes arranged sequentially along the channel direction; wherein, the odd-numbered sets of heat pipes are concentrated in the center of the channel and spaced apart from the channel sidewall by a first distance; each even-numbered set of heat pipes is divided into two sub-groups, which are respectively arranged close to the two sides of the channel and spaced apart from each other by a second distance.

6. The heat recovery system for a coal gasification unit according to any one of claims 1-4, characterized in that, Each heat exchange tube is connected to a pulse vibration pump, which triggers automatic vibration and dust removal through differential pressure.

7. The heat recovery system for a coal gasification unit according to claim 3, characterized in that, The second air inlet is connected to the dilution fan.

8. The heat recovery system for a coal gasification unit according to claim 3 or 7, characterized in that, The third air inlet is connected to a blower.

9. A method for heat recovery in a coal gasification unit, applied to a heat recovery system for a coal gasification unit according to any one of claims 1-8, characterized in that, include: The pulverized coal filter filters the mixture of pulverized coal and gas output from the coal mill, outputting filtered pulverized coal and outputting filtered gas to the circulating fan. The circulating fan outputs the first part of the filtered gas to the heat exchanger and the second part of the filtered gas to the hot blast furnace. The first part of filtered gas is cooled by heat exchange through the flue gas heat exchange channel of the heat exchanger, and the treated gas is released into the atmosphere. The inert gas is heated by heat exchange through the inert gas preheating channel of the heat exchanger, and the treated inert gas is then transported to the hot air furnace. The input air is heated by heat exchange through the air preheating channel of the heat exchanger, and the heated air is then delivered to the hot air furnace. The hot blast furnace receives the inert gas, the atmosphere, and the fuel gas, and generates and outputs hot air to the coal mill.

10. The heat recovery system for a coal gasification unit according to claim 9, characterized in that, The temperature of the gas after filtration in the first part is about 105°C, which is reduced to 65°C after heat exchange treatment.

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