High-temperature biogas temperature control cooling process and device

Abstract

The application discloses a high-temperature bio-gas temperature control cooling process and device, and belongs to the technical field of high-efficiency utilization of biomass energy. The device comprises a gas heat absorption unit, a steam heating unit, a heat utilization unit and a gas conveying unit. The process steps comprise the following steps: high-temperature gas is cooled and exchanged heat in a superheater and an evaporation heating surface in a gas cooling flue, then is dedusted and output; saturated water in a waste heat boiler steam drum is introduced into the evaporation heating surface through a downcomer to generate a steam-water mixture by heat absorption, and the separated saturated steam is introduced into the superheater through a pressure regulating valve to be heated into superheated steam; the superheated steam is divided into two routes, one route is used for external heat supply through a temperature and pressure reducer, and the other route is introduced into an air preheater to heat and gasify air; condensed water is sent back to the steam drum through a steam-water heat exchanger, a buffer tank and a circulating water pump to form a cycle. The application controls the steam drum pressure to be not lower than 6.0 MPa, so that the temperature of the heat exchange surface is not lower than 275 DEG C, tar condensation is effectively avoided, and waste heat is utilized in stages.

Description

Technical Field

[0001] This invention relates to the field of biomass energy high-efficiency utilization technology, specifically to a high-temperature biogas temperature control and cooling process and device. Background Technology

[0002] With the increasing demand for renewable energy development in my country, biomass energy, with its zero-carbon fuel characteristics, is playing an increasingly crucial and important role in the energy structure transformation process. Biomass gasification technology, as an important means of biomass energy utilization, converts agricultural and forestry waste into syngas through high-temperature pyrolysis. This syngas contains components such as CO, H2, CH4, and tar. However, due to the limitations of biomass' calorific value and ash melting point, the high-temperature gas produced in this process (temperature between 700℃ and 800℃) contains a large amount of superheated tar, which brings many challenges to subsequent gas transportation and utilization. In the biomass gas transportation stage, because the gas turbine blades have extremely strict temperature requirements, the temperature of the high-temperature gas must be reduced from 700-800℃ to around 400℃ to ensure the safe and stable operation of the equipment.

[0003] Traditional cooling methods for biomass gas transportation present numerous challenges. Traditional high-temperature heat transfer oil cooling systems are complex, involving numerous devices and processes, resulting in high operation and maintenance costs. Furthermore, organic heat transfer oils are flammable and explosive; leaks or other accidents during high-temperature gas cooling can easily lead to safety incidents, making biomass gas transportation both complex and dangerous. Low-temperature cooling media (such as atmospheric pressure water) suffer from significant tar condensation problems. When used to cool high-temperature gas, the low-temperature environment causes tar to rapidly deposit on the heat exchange surface. As tar accumulates, the thermal resistance of the heat exchange surface increases, heat exchange efficiency decreases sharply, and heat exchange gradually fails, severely impacting system stability. More seriously, this can lead to equipment failure, production interruptions, and substantial economic losses for enterprises. Regarding waste heat utilization, traditional cooling systems have significant shortcomings. Conventional cooling methods cannot directly produce high-temperature steam, yet subsequent processes have high steam requirements. To meet the demand, air needs to be heated and vaporized to produce steam, which not only increases the system's energy consumption but also reduces the overall energy utilization efficiency, which contradicts the original intention of efficient utilization of biomass energy and is not conducive to its sustainable development.

[0004] In summary, traditional cooling methods have serious problems in terms of safety, efficiency, waste heat utilization, and economy during biomass gas transportation, and there is an urgent need to find more efficient, safe, and economical cooling solutions. Summary of the Invention

[0005] To address the problems of tar condensation clogging heat exchange surfaces, low waste heat recovery efficiency, and poor system stability in existing biomass gas cooling technologies, this invention provides a high-temperature biomass gas temperature-controlled cooling process and device. This invention effectively prevents tar condensation on the heat exchange surface through pressure-temperature coordinated control of high-pressure water and steam circulation, while simultaneously achieving efficient, tiered utilization of waste gas heat.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a high-temperature biogas temperature control and cooling device, comprising: The gas-fired heat energy absorption unit includes a waste heat boiler drum 1, a downcomer 2, an evaporation heating surface 4, and a pressure regulating valve 10, which is used to directly absorb the heat of high-temperature gas through the evaporation heating surface to generate saturated steam. A steam heating unit, including a superheater 3, is arranged in the gas cooling flue 12 to heat saturated steam into superheated steam using the heat of high-temperature gas. The thermal energy utilization unit includes an air preheater 5, a steam-water heat exchanger 6, a buffer tank 7, a circulating water pump 8, and a desuperheating and pressure reducing device 9. The gas transmission unit includes a gas cooling flue 12, a dust collector 11, and a high-temperature gas fan 13; The waste heat boiler steam drum 1, downcomer 2, and evaporation heating surface 4 are sequentially connected to form a steam-water circulation loop. The steam outlet of the waste heat boiler steam drum 1 is connected to the superheater 3 via the pressure regulating valve 10. The steam outlet of the superheater 3 is divided into two pipelines, which are respectively connected to the desuperheater 9 and the air preheater 5.

[0007] Preferably, the gas cooling flue 12 is a vertical tower structure with a flue gas inlet at the top and a flue gas outlet at the bottom; the superheater 3 and the evaporation heating surface 4 are arranged sequentially from top to bottom in the gas cooling flue 12 along the gas flow direction; the waste heat boiler drum 1 is arranged at the top of the gas cooling flue 12.

[0008] Preferably, the superheater 3 is divided into a high-temperature section 3-1 located at the top and a low-temperature section 3-2 located at the bottom.

[0009] Furthermore, the high-temperature section 3-1 is made of 310s material, and the low-temperature section 3-2 is made of 316 or 1Cr12MoV high-temperature resistant material; Furthermore, the evaporation heating surface 4 is made of 20G material.

[0010] Preferably, the condensate outlet of the air preheater 5 is sequentially connected to the steam-water heat exchanger 6, the buffer tank 7, the circulating water pump 8, and the waste heat boiler drum 1 to form a closed-loop circulation loop for steam condensate.

[0011] The buffer tank 7 is located after the steam-water heat exchanger and before the circulating water pump to reduce condensate flow fluctuations, reduce the amount of gas carried into the high-pressure feedwater pump, maintain stable pump inlet pressure, and prevent feedwater flash vaporization.

[0012] The present invention also provides a high-temperature biogas temperature control and cooling process based on the above-mentioned device, comprising the following steps: S1 Gas Cooling and Dust Removal: The high-temperature biogas from the gasification device outlet enters the gas cooling flue 12, and is indirectly cooled by heat exchange through the superheater 3 and the evaporation heating surface 4. After cooling, the gas is removed by the dust collector 11 and then extracted by the high-temperature gas fan 13. S2 High-pressure water and steam circulation heat absorption: Saturated water in the waste heat boiler drum 1 enters the evaporation heating surface 4 through the downcomer 2 to absorb heat and evaporate to produce a steam-water mixture. The steam-water mixture returns to the waste heat boiler drum 1 for separation. The separated saturated steam enters the superheater 3 through the pressure regulating valve 10 and is heated into high-temperature and high-pressure superheated steam. S3 Steam Cascade Utilization: The high-temperature and high-pressure superheated steam at the outlet of the superheater 3 is divided into two paths. The first path enters the desuperheater and pressure reducer 9 to cool and depressurize it for external heating. The second path enters the air preheater 5 to release heat and heat the vaporized cold air into high-temperature air. The condensate after the steam is released and condensed in the air preheater 5 is cooled by the steam-water heat exchanger 6, stabilized by the buffer tank 7, and pressurized by the circulating water pump 8 before being sent back to the waste heat boiler drum 1.

[0013] The present invention arranges the dust collector 11 before the high-temperature gas fan 13, so that the gas entering the fan is pre-treated by dust removal, which effectively reduces the wear and corrosion of the fan blades by tar and dust and extends the service life of the equipment.

[0014] Preferably, in step S2, by adjusting the pressure regulating valve 10, the operating pressure of the waste heat boiler drum 1 is controlled at ≥6.0MPa, so that the temperature of the steam-water mixture in the evaporation heating surface 4 is not lower than 275℃; and the temperature of the metal outer surface of the superheater 3 and the evaporation heating surface 4 is kept at not lower than 310℃, so as to prevent the tar in the high-temperature biogas from condensing on the heat exchange surface.

[0015] Preferably, in step S1, the inlet temperature of the high-temperature biogas is 700°C to 800°C, and the temperature of the cooled biogas is 380°C to 420°C.

[0016] Preferably, in step S3, the pressure of the high-temperature and high-pressure superheated steam at the outlet of the superheater 3 is 6.0 MPa to 9.8 MPa and the temperature is 450°C to 550°C.

[0017] More preferably, in step S3, the temperature of the high-temperature and high-pressure superheated steam at the outlet of the superheater 3 is 450°C to 500°C.

[0018] Compared with the prior art, the beneficial technical effects of this invention are reflected in: Firstly, it effectively prevents tar condensation. By controlling the operating pressure of the waste heat boiler drum 1 at ≥6.0MPa, the metal outer surface temperature of the superheater 3 and the evaporation heating surface 4 is maintained at no less than 310℃. Through the above-mentioned pressure-temperature coordinated control, the surface temperature of the heat exchange metal in contact with the high-temperature gas is always higher than the condensation temperature of light, medium, and most heavy tar, effectively inhibiting the condensation and adhesion of tar on the heat exchange surface. Combined with the scouring effect of the high-speed airflow in the flue, even if a small amount of liquid tar is released, it can be stripped and carried away in time, thereby avoiding tar blockage of the heat exchange channel and ensuring the long-term stable operation of the system. In contrast, the inlet temperature of the heat transfer oil in the traditional heat transfer oil cooling system is about 200℃ and the outlet temperature is about 260℃, and the heat exchange wall temperature is significantly lower than that of this invention, which cannot effectively inhibit tar condensation.

[0019] Secondly, waste heat is utilized in stages. High-temperature steam is generated by using the waste heat of the gas itself to directly heat the gasified air, thereby improving the efficiency of gasification of cold gas and the calorific value of the gas. This fully recovers waste heat and reduces additional energy consumption. Third, economic optimization: using power plant boiler water as the cooling medium reduces operating costs. Compared with heat transfer oil systems, it reduces equipment investment, simplifies system structure, and makes maintenance more convenient. Fourth, it has a flexible operating mode, supporting both internal circulation (all steam is used for heating) and external heating (part of the steam is de-heated and depressurized for heating) modes, which can be flexibly switched according to different working conditions, thus improving the system's adaptability.

[0020] This invention effectively suppresses tar condensation on the heat exchange surface through pressure-temperature coordinated control and realizes the cascade utilization of waste heat from gas combustion. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structural connection of a high-temperature biogas temperature control and cooling device according to the present invention.

[0022] Figure 2 This is a side view of a high-temperature biogas temperature control and cooling device according to the present invention.

[0023] Figure 3 This is a front view of the internal cross-sectional view of a high-temperature biogas temperature control and cooling device according to the present invention. The component names represented by the numbers in the accompanying drawing are as follows: 1- Waste heat boiler drum, 2- Downcomer, 3- Superheater, 3-1- High temperature section, 3-2- Low temperature section, 4- Evaporation heating surface, 5- Air preheater, 6- Steam-water heat exchanger, 7- Buffer tank, 8- Circulating water pump, 9- Desuperheater and pressure reducer, 10- Pressure regulating valve, 11- Dust collector, 12- Gas-fired cooling flue, 13- High temperature gas-fired fan. Detailed Implementation

[0024] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0025] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0026] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0027] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0028] This invention provides a high-temperature biogas temperature control and cooling process and apparatus, which mainly consists of the following functional units: The gas-fired heat energy absorption unit includes a waste heat boiler drum 1, a downcomer 2, an evaporation heating surface 4, and a pressure regulating valve 10, which is used to directly absorb the heat of high-temperature gas through the evaporation heating surface to generate saturated steam. The steam heating unit, including the superheater 3, is arranged in the gas cooling flue 12. It uses the heat of the high-temperature gas to further heat the saturated steam generated by the waste heat boiler drum 1 into superheated steam, thereby improving the steam quality. The thermal energy utilization unit includes an air preheater 5, a steam-water heat exchanger 6, a buffer tank 7, a circulating water pump 8, and a desuperheating and pressure reducing device 9, which are used to utilize superheated steam in stages. The gas transmission unit includes a gas cooling flue 12, a dust collector 11, and a high-temperature gas fan 13, which are used to guide the high-temperature gas through each heat exchange device in sequence and to remove dust and transmit it.

[0029] I. Spatial Layout and Structural Features of the Device like Figure 1 As shown, the specific connection relationships between the components of the device of the present invention are as follows: The gas outlet of the gasification device is connected to the hot gas inlet at the top of the gas cooling flue 12. The saturated water outlet at the bottom of the waste heat boiler drum 1 is connected to the inlet of the evaporation heating surface 4 through the downcomer 2, and the steam-water mixture outlet of the evaporation heating surface 4 is connected to the return water inlet of the waste heat boiler drum 1 through a pipe, forming a high-temperature and high-pressure saturated water natural circulation loop.

[0030] The steam outlet at the top of the waste heat boiler drum 1 is connected to the inlet of the superheater 3 via a steam pipeline and the pressure regulating valve 10. The superheated steam outlet of the superheater 3 is divided into two branches: the first branch is connected to the steam inlet of the air preheater 5, and the second branch is connected to the inlet of the desuperheater and pressure reducer 9. The cold air inlet of the air preheater 5 is used to supply cold air for gasification, and its hot air outlet is used to supply gas to the gasification unit. The condensate outlet of the air preheater 5 is connected in sequence to the steam-water heat exchanger 6, the buffer tank 7, and the circulating water pump 8 via pipelines. The outlet of the circulating water pump 8 is connected to the waste heat boiler drum 1 via a return water pipeline, forming a closed-loop recovery and circulation loop for steam condensate.

[0031] The low-temperature gas outlet at the bottom or side of the gas cooling flue 12 is connected to the inlet of the dust collector 11 via a pipeline. The outlet of the dust collector 11 is connected to the high-temperature gas fan 13. The fan outlet is used to deliver cooled and dust-removed biomass gas to downstream gas-using equipment.

[0032] like Figure 2 and Figure 3 As shown, this device adopts a vertical tower-like frame structure, and the overall layout is vertical from top to bottom.

[0033] Combination Figure 2 (Side view of the device) As can be seen, high-temperature gas enters the gas cooling flue 12 from the top flue gas inlet, flows from top to bottom, and exits from the bottom flue gas outlet. To ensure the safe operation of the system, the gas cooling flue 12 and all connections are sealed to prevent gas leakage from the outside air. Figure 2 It visually demonstrates the external spatial orientation of the gas-fired cooling flue, the structure of the ash hopper, and the overall distribution of the inlet and outlet of hot and cold fluids.

[0034] Combination Figure 3(Internal sectional view of the device) It can be seen that the heat exchange components inside the device are arranged in a vertically layered stacked manner. Specifically, the waste heat boiler drum 1 is located at the top of the entire device, so that the water in the drum can flow naturally to the evaporation heating surface 4 under the action of gravity through the downcomer 2. In the gas cooling flue below the waste heat boiler drum 1, superheaters 3 and multiple sets of evaporation heating surfaces 4 are arranged sequentially from top to bottom along the direction of flue gas flow, that is, the evaporation heating surfaces 4 are located directly below the superheaters 3. Among them, the superheaters 3 are further subdivided into a high-temperature section 3-1 located at the top and a low-temperature section 3-2 located at the bottom. In addition, the air preheater 5 and the steam-water heat exchanger 6 are concentrated in the bottom area of ​​the device's steel frame, with the bottom of the air preheater 5 having a cold air inlet and a hot air outlet.

[0035] The buffer tank 7 is located after the steam-water heat exchanger and before the circulating water pump to reduce condensate flow fluctuations, reduce the amount of gas carried into the high-pressure feedwater pump, maintain stable pump inlet pressure, and prevent feedwater flash vaporization.

[0036] II. Process Flow and System Operation Mode 1. Gas cooling and dust removal The high-temperature biogas (700℃~800℃) from the gasification unit outlet enters the gas cooling flue 12, and passes sequentially through the superheater 3 and the evaporation heating surface 4, transferring the heat energy of the gas to the high-temperature water and superheated steam through indirect heat transfer. The cooled gas (cooled to 400℃) enters the dust collector 11 for cyclone dust removal, and the dust-removed gas is extracted by the high-temperature gas fan 13.

[0037] 2. High-pressure saturated water and steam circulation for heat absorption During the initial system startup, deoxygenated water can be added to the waste heat boiler drum 1 to establish the initial liquid level. Then, the circulating water pump 8 is started to circulate the system. In the initial direct combustion stage (i.e., the system is heated by direct combustion of auxiliary fuel), the water in the system is heated to saturation (pressure ≥ 6.0 MPa, corresponding to a saturation temperature of approximately 275℃). After the system enters stable operation, due to the closed-loop internal circulation, the working fluid loss is extremely low, with only a small loss occurring during periodic blowdown. If water replenishment is required at this time, the feedwater temperature should be controlled between 225℃ and 283℃, and the pressure should not be lower than 6.0 MPa to ensure compatibility with the high-pressure saturated water system.

[0038] Once the system reaches a stable operating state, it switches to biomass gasification mode (i.e., "direct combustion to gasification"). Saturated water in the waste heat boiler drum 1 is sent to the evaporation heating surface 4 through the downcomer 2. Under a constant saturation temperature, it absorbs heat and evaporates to produce a steam-water mixture. This steam-water mixture is then sent back to the waste heat boiler drum 1 for steam-water separation. The produced saturated steam is drawn from the waste heat boiler drum 1 and enters the superheater 3 through the pressure regulating valve 10 for heating, generating high-temperature, high-pressure steam.

[0039] 3. Steam cascade utilization and heating The high-temperature, high-pressure steam (pressure: 6.0MPa~9.8MPa, temperature: 450℃~550℃) at the outlet of superheater 3 is divided into two streams: First route (external heating): Superheated steam preferentially enters the air preheater 5, serving as the heating medium to heat the vaporized cold air from 35°C to 350°C. This high-temperature air then enters the vaporization device to participate in the vaporization reaction. After meeting the heating requirements of the vaporized air, if there is any remaining superheated steam, the steam pressure is reduced to the heating pressure of 1.5MPa~1.8MPa by the desuperheater 9, and then the superheated steam temperature is reduced to the heating temperature of 320°C by the main heating system booster pump using demineralized water (1.8MPa, 35°C) before being supplied to the outside for heating.

[0040] The second route (internal circulation): Superheated steam enters the air preheater 5 through the flow regulating valve to release heat, heating the vaporized cold air from 35°C to 350°C. This high-temperature air then enters the vaporization device for vaporization reaction. The temperature of the condensate after heat release and condensation depends on the steam volume: When the steam volume entering the air preheater 5 is small, the condensate can cool down to about 250°C on its own. At this time, the steam-water heat exchanger 6 is not in operation, and the condensate flows out of the steam-water heat exchanger 6, is pressurized by the buffer tank 7, and then pressurized by the circulating water pump 8 before being sent back to the waste heat boiler drum 1; When the steam volume is large, the condensate temperature at the outlet of the air preheater 5 is still high (e.g., about 310°C), and cannot be reduced to the target temperature. At this time, the steam-water heat exchanger 6 is started to further cool the condensate, reducing it to 250°C, and then it is pressurized by the buffer tank 7 and pressurized by the circulating water pump 8 before being sent back to the waste heat boiler drum 1, forming a closed water circulation.

[0041] When heat exchange is not required, the cooling water inlet valve of the heat exchanger 6 is closed, and the water flows to the buffer tank 7. III. Specific Implementation Examples Taking a biomass gasification unit as an example, the high-temperature biogas flow rate at the gasifier outlet is 54,000 Nm³ / h, and the temperature is 750℃. This biogas enters the gas cooling flue 12, and flows sequentially through the superheater 3 and the evaporation heating surface 4 for indirect heat exchange. The operating pressure of the waste heat boiler drum 1 is controlled at 6.0 MPa. Saturated water in the drum enters the evaporation heating surface 4 through the downcomer 2. The generated saturated steam enters the superheater 3 through the pressure regulating valve 10 and is heated to superheated steam at a pressure of 6.0 MPa and a temperature of 450℃.

[0043] Superheated steam enters the air preheater 5, heating the vaporized cold air (flow rate 26000 Nm³ / h) from 35℃ to 350℃. The condensate is cooled to 250℃ by the steam-water heat exchanger 6, then pressurized by the buffer tank 7 and the circulating water pump 8 before being sent back to the waste heat boiler drum 1, forming a closed loop (circulating water flow rate ~12t / h). The cooled gas temperature is approximately 400℃, and after dust removal by the dust collector 11, it is extracted by the high-temperature gas fan 13 and sent to downstream users.

[0044] The above detailed description is a specific description of one of the feasible embodiments of the present invention. This embodiment is not intended to limit the patent scope of the present invention. All equivalent implementations or modifications that do not depart from the present invention should be included within the scope of the technical solution of the present invention.

[0045] It should be particularly noted that the various embodiments listed in this specification and accompanying drawings are intended to illustrate the technical solutions and advantages of the present invention, and not to limit the scope of protection of the present invention. Without departing from the core ideas and technical effects of the present invention, those skilled in the art can make any form of improvement, substitution, combination, or modification to the structural arrangement, process parameters, material selection, control logic, etc., of the described embodiments; any obvious changes based on the same concept should be considered equivalent solutions of the present invention and should be included within the scope of protection defined by the claims of the present invention. The actual scope of protection of the present invention is determined by the appended claims and should be correctly understood in conjunction with the specification and accompanying drawings.

Claims

1. A high-temperature biogas temperature control and cooling device, characterized in that, include: The gas heat energy absorption unit includes a waste heat boiler drum (1), a downcomer (2), an evaporation heating surface (4), and a pressure regulating valve (10), which is used to directly absorb the heat of high-temperature gas through the evaporation heating surface to generate saturated steam. A steam heating unit, including a superheater (3), is arranged in the gas cooling flue (12) to heat saturated steam into superheated steam using the heat of high-temperature gas. The thermal energy utilization unit includes an air preheater (5), a steam-water heat exchanger (6), a buffer tank (7), a circulating water pump (8), and a desuperheating and pressure reducing device (9). The gas delivery unit includes a gas cooling flue (12), a dust collector (11), and a high-temperature gas fan (13). The waste heat boiler steam drum (1), downcomer (2), and evaporation heating surface (4) are connected in sequence to form a steam-water circulation loop. The steam outlet of the waste heat boiler steam drum (1) is connected to the superheater (3) via the pressure regulating valve (10). The steam outlet of the superheater (3) is divided into two pipelines, which are connected to the desuperheater (9) and the air preheater (5) respectively.

2. The high-temperature biogas temperature control and cooling device according to claim 1, characterized in that: The gas cooling flue (12) is a vertical tower structure with a flue gas inlet at the top and a flue gas outlet at the bottom; the superheater (3) and the evaporation heating surface (4) are arranged sequentially from top to bottom in the gas cooling flue (12) along the gas flow direction; the waste heat boiler drum (1) is arranged at the top of the gas cooling flue (12).

3. The high-temperature biogas temperature control and cooling device according to claim 2, characterized in that: The superheater (3) is divided into a high-temperature section (3-1) located at the top and a low-temperature section (3-2) located at the bottom.

4. The high-temperature biogas temperature control and cooling device according to claim 3, characterized in that: The high-temperature section (3-1) is made of 310s high-temperature resistant material, and the low-temperature section (3-2) is made of 316 or 1Cr12MoV high-temperature resistant material.

5. The high-temperature biogas temperature control and cooling device according to claim 1, characterized in that: The evaporative heating surface (4) is made of 20G material.

6. The high-temperature biogas temperature control and cooling device according to claim 1, characterized in that: The condensate outlet of the air preheater (5) is sequentially connected to the steam-water heat exchanger (6), the buffer tank (7), the circulating water pump (8), and the waste heat boiler drum (1) to form a closed-loop circulation loop of steam condensate.

7. A high-temperature biogas temperature-controlled cooling process, characterized in that, Based on the apparatus according to any one of claims 1 to 6, the method includes the following steps: S1 Gas Cooling and Dust Removal: The high-temperature biogas from the gasification device outlet enters the gas cooling flue (12), and is indirectly cooled by heat exchange through the superheater (3) and the evaporation heating surface (4). After cooling, the gas is removed by the dust collector (11) and then extracted by the high-temperature gas fan (13). S2 High-pressure water and steam circulation heat absorption: Saturated water in the waste heat boiler drum (1) enters the evaporation heating surface (4) through the downcomer (2) to absorb heat and evaporate to produce a steam-water mixture. The steam-water mixture returns to the waste heat boiler drum (1) for separation. The separated saturated steam enters the superheater (3) through the pressure regulating valve (10) and is heated into high-temperature and high-pressure superheated steam. S3 Steam cascade utilization: The high-temperature and high-pressure superheated steam at the outlet of the superheater (3) is divided into two paths. The first path enters the desuperheater (9) to cool and depressurize it for external heating. The second path enters the air preheater (5) to release heat and heat the vaporized cold air into high-temperature air. The condensate after the steam is released and condensed in the air preheater (5) is cooled by the steam-water heat exchanger (6), stabilized by the buffer tank (7), and pressurized by the circulating water pump (8) before being sent back to the waste heat boiler steam drum (1).

8. The high-temperature biogas temperature control and cooling process according to claim 7, characterized in that: In step S2, by adjusting the pressure regulating valve (10), the operating pressure of the waste heat boiler drum (1) is controlled at ≥6.0MPa, so that the temperature of the steam-water mixture in the evaporation heating surface (4) is not lower than 275℃; and the temperature of the metal outer surface of the superheater (3) and the evaporation heating surface (4) is kept at not lower than 310℃.

9. The high-temperature biogas temperature control and cooling process according to claim 7, characterized in that: In step S1, the inlet temperature of the high-temperature biogas is 700°C to 800°C, and the temperature of the cooled biogas is 380°C to 420°C.

10. The high-temperature biogas temperature control and cooling process according to claim 7, characterized in that: In step S3, the high-temperature and high-pressure superheated steam at the outlet of the superheater (3) has a pressure of 6.0 MPa to 9.8 MPa and a temperature of 450°C to 550°C.

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