Biomass gasification system and method thereof

Abstract

This invention relates to the field of clean energy and waste heat recovery technology, and discloses a biomass gasification system and method. The system includes a biomass gasification module, a power generation and heating module, and an absorption refrigeration module. The biomass gasification module includes a gasifier, a first heat exchanger, and a quench tower connected in sequence. The power generation and heating module includes a compressor, a second heat exchanger, a combustion chamber, a turbine, and a third heat exchanger. The absorption refrigeration module includes a generator, a second condenser, and an evaporator. One inlet of the first heat exchanger and one inlet of the third heat exchanger are respectively connected to the outlet of a cold storage tank. One outlet of the first heat exchanger and one inlet of the third heat exchanger are respectively connected to the inlet of the cold storage tank. The outlet of the cold storage tank is respectively connected to one inlet of the second heat exchanger and one inlet of the generator. One outlet of the second heat exchanger and one inlet of the generator are connected to the inlet of a fourth heat exchanger. One outlet of the fourth heat exchanger is connected to the inlet of the cold storage tank. This completely solves the problems of single energy utilization form and low overall energy efficiency in traditional systems.

Description

Technical Field

[0001] This invention relates to the field of clean energy and waste heat recovery technology, and in particular to a biomass gasification system and method thereof. Background Technology

[0002] Biomass gasification technology, as a green and clean energy technology, is widely used in the production of low-calorific-value fuel gas and the efficient utilization of energy. In recent years, with the increasing demands for environmental protection and energy efficiency, biomass gasification technology has been widely used for various purposes such as power generation, heating, and cooling.

[0003] In related technologies, common biomass gasification power generation systems typically include: a biomass gasifier, a water-cooled tower, a purification unit, and a gas turbine generator set. The typical operating process is as follows: biomass is gasified in the biomass gasifier to produce high-temperature crude gas, which directly enters the water-cooled tower for cooling, dust removal, and coking removal. Finally, the purified cold gas enters the gas turbine generator set for combustion and power generation. However, this traditional biomass gasification power generation system has the following significant problems in actual operation:

[0004] Insufficient utilization of high-temperature gas: The high-temperature gas produced by biomass gasification furnaces contains a large amount of recoverable heat. Traditional heat recovery methods typically use a single heat exchanger, which does not fully utilize the high-temperature heat in the gas, resulting in wasted thermal energy.

[0005] Tar control is challenging: the gas produced by gasifiers typically contains a significant amount of tar. At high temperatures, this tar easily condenses on the heat exchanger tube walls, causing scaling and blockage, reducing heat exchanger efficiency, and increasing the difficulty of maintenance and cleaning. Traditional gasification gas purification processes mainly employ water washing or simple filtration methods, which are ineffective in addressing the problem of tar condensation on heat exchanger surfaces at high temperatures. Especially during the process of high-temperature gas entering the heat exchanger, tar is often not effectively removed.

[0006] Low efficiency in waste heat recovery and energy utilization: Existing technologies mainly focus on the recovery and utilization of single energy sources, resulting in low energy utilization efficiency. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a biomass gasification system and method that can fully utilize the high-temperature waste heat generated during biomass gasification and the waste heat emitted by the gas turbine, achieving multi-stage waste heat recovery while ensuring efficient and continuous system operation. It exhibits significant energy-saving effects and a high energy efficiency ratio, effectively reducing energy consumption. Furthermore, through refined energy recovery and distribution, it improves the overall utilization efficiency of the system, demonstrating good economic and environmental benefits.

[0008] The first aspect of this invention provides a biomass gasification system, comprising: a biomass gasification module, a power generation and heating module, and an absorption refrigeration module; the biomass gasification module includes a gasifier, a first heat exchanger, and a quench tower connected in sequence; the power generation and heating module includes a compressor, a second heat exchanger, a combustion chamber, a turbine, and a third heat exchanger; the absorption refrigeration module includes a generator, a second condenser, and an evaporator; one inlet of the first heat exchanger and one inlet of the third heat exchanger are respectively connected to the outlet of a cold storage tank, one outlet of the first heat exchanger and one outlet of the third heat exchanger are respectively connected to the inlet of the cold storage tank, the outlet of the cold storage tank is respectively connected to one inlet of the second heat exchanger and one inlet of the generator, one outlet of the second heat exchanger and one outlet of the generator are connected to the inlet of a fourth heat exchanger, and one outlet of the fourth heat exchanger is connected to the inlet of the cold storage tank; wherein, the first heat exchanger, the second heat exchanger, the third heat exchanger, the fourth heat exchanger, the cold storage tank, and the cold storage tank constitute a multi-stage waste heat recovery loop, the fourth heat exchanger transfers heat to water for heating, and the evaporator supplies cooling energy to external users.

[0009] Optionally, the quench tower is also connected in sequence to a scrubbing device and a first condenser. The first condenser reduces the gas temperature and lowers the gas dew point by condensing and removing water.

[0010] Optionally, the biomass gasification module also includes a dryer connected to the gasifier. The dryer is connected to one outlet of a third heat exchanger, and the exhaust gas discharged from the third heat exchanger is provided to the dryer as a heat source.

[0011] Optionally, one outlet of the first heat exchanger and one outlet of the third heat exchanger are connected to the inlet of the heat storage tank via a first mixing valve, and one outlet of the second heat exchanger and one outlet of the generator are connected to the inlet of the fourth heat exchanger via a second mixing valve.

[0012] Optionally, the absorption refrigeration module also includes: a heat exchanger and an absorber, an evaporator connected to the absorber, a circulation loop between the generator and the heat exchanger, and a circulation loop between the heat exchanger and the absorber.

[0013] Optionally, a control module is also included. The control module includes a tar dew point monitoring unit installed at the first heat exchanger and a controller connected thereto. The tar dew point monitoring unit is used to collect temperature, pressure and composition data of the gas. The controller obtains the tar dew point temperature based on the temperature, pressure and composition data of the gas. When the temperature difference between the tar dew point temperature and the temperature of the tube wall of the first heat exchanger exceeds a preset threshold, the controller controls the cooling medium flow regulating valve of the first heat exchanger.

[0014] Optionally, the control module also includes a gas dew point monitoring unit located at the outlet of the quench tower. The gas dew point monitoring unit is used to monitor the actual temperature and relative humidity of the gas. The controller obtains the water dew point temperature in the gas based on the actual temperature and relative humidity of the gas. When the temperature difference between the actual temperature of the gas and the water dew point temperature is less than the safety margin, the controller adjusts the cooling medium flow regulating valve of the first heat exchanger to control the temperature entering the quench tower, thereby preventing condensation from occurring near the gasifier outlet or in the gas pipeline.

[0015] Optionally, the control module also includes differential pressure sensors respectively installed at the first heat exchanger, the quench tower and the first condenser. When the pressure drop detected by any differential pressure sensor exceeds a preset threshold, the controller issues an online cleaning or maintenance alarm.

[0016] A second aspect of the present invention provides a biomass gasification method as described above, comprising the following steps: After being dried and pulverized, biomass is gasified in a gasifier to produce crude coal gas. After dust removal, the crude coal gas enters the first heat exchanger for high-temperature waste heat recovery. The cooled gas enters a rapid cooling tower for quick cooling. The cooled coal gas and the air preheated by the second heat exchanger are burned in the combustion chamber to drive the turbine to generate electricity; Turbine exhaust enters the third heat exchanger to recover waste heat, which is then stored together with the heat recovered by the first heat exchanger in a heat storage tank. Part of the heat storage medium is used to preheat the air, and the other part drives the absorption refrigeration module to cool. The waste heat from the cooling process is further processed into domestic hot water or heating water through a fourth heat exchanger.

[0017] Optional, also includes: Real-time monitoring of the temperature, pressure and composition data of the gas at the first heat exchanger, the actual temperature and relative humidity of the gas at the outlet of the quench tower, and the pressure difference at the first heat exchanger, the quench tower and the first condenser. Based on monitoring data, tar dew point temperature, water dew point temperature and pressure difference are obtained to predict scaling, blockage risk and condensation corrosion risk, and feedforward control is carried out by adjusting the cooling medium flow rate of the first heat exchanger or the heat exchanger operation mode. When abnormal parameters are detected, the protection mechanism is automatically triggered to perform feedback adjustments.

[0018] The technical solution provided by the embodiments of the present invention has the following advantages compared with the prior art: This invention provides a biomass gasification system and method that, through a structural design of a first heat exchanger connected in series with a quench tower, recovers high-temperature sensible heat from the gas before it enters the quench tower. This process of recovering heat first and then quenching not only maximizes the extraction of high-grade heat energy from the gasification process but also effectively reduces the temperature of the gas entering the quench tower, thereby reducing the load on subsequent quenching and purification equipment and lowering the risk of tar condensation while improving energy recovery rate. A closed-loop circuit consisting of a heat storage tank, a cold storage tank, and multiple heat exchangers is constructed to uniformly allocate and utilize the recovered gasification waste heat and the exhaust waste heat from the gas turbine. High-grade heat energy is fed back to the compressor outlet via a second heat exchanger to improve power generation efficiency or to drive an absorption refrigeration module to generate cooling; low-grade waste heat is used to prepare hot water via a fourth heat exchanger. This cascade utilization method expands single biomass power generation into combined cooling, heating, and power (CCHP), completely solving the problems of single energy utilization and low overall energy efficiency in traditional systems. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a biomass gasification system provided in an embodiment of the present invention.

[0020] Explanation of reference numerals in the attached figures: 1. Biomass silo; 2. Dryer; 3. Crushing and screening device; 4. Gasifier; 5. Cyclone separator; 6. First heat exchanger; 7. Quenching tower; 8. Washing device; 9. First condenser; 10. Buffer chamber; 11. Compressor; 12. Second heat exchanger; 13. Combustion chamber; 14. Turbine; 15. Third heat exchanger; 16. Cold storage tank; 17. Heat storage tank; 18. Fourth heat exchanger; 19. Generator; 20. Heat exchanger; 21. Booster pump; 22. First expansion valve; 23. Absorber; 24. Evaporator; 25. Second expansion valve; 26. Second condenser; 27. First mixing valve; 28. Second mixing valve. Detailed Implementation

[0021] The following detailed description of a specific embodiment of the present invention is provided in conjunction with the accompanying drawings. However, it should be understood that the scope of protection of the present invention is not limited to the specific embodiment.

[0022] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the technical solution of this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0023] The present invention will be described below through several specific embodiments. To keep the following description of the embodiments clear and concise, detailed descriptions of known functions and components may be omitted. When any component of an embodiment of the present invention appears in more than one drawing, the component may be represented by the same reference numerals in each drawing.

[0024] like Figure 1 As shown in the first embodiment of the present invention, a biomass gasification system is provided, comprising: a biomass gasification module, a power generation and heating module, and an absorption refrigeration module. The working fluid used in the absorption refrigeration module is an ammonia solution or a lithium bromide solution. The biomass gasification module includes a gasifier 4, a first heat exchanger 6, and a quench tower 7 connected in sequence. The power generation and heating module includes a compressor 11, a second heat exchanger 12, a combustion chamber 13, a turbine 14, and a third heat exchanger 15. The absorption refrigeration module includes a generator 19, a second condenser 26, and an evaporator 24. One inlet of the first heat exchanger 6 and the third heat exchanger 15 are respectively connected to the outlet of a cold storage tank 16. One outlet of the first heat exchanger 6 and the third heat exchanger 15 are respectively connected to the inlet of the heat storage tank 17. The outlet of the heat storage tank 17 is respectively connected to one inlet of the second heat exchanger 12 and the generator 19. One outlet of the second heat exchanger 12 and the generator 19 is connected to the inlet of the fourth heat exchanger 18. One outlet of the fourth heat exchanger 18 is connected to the inlet of the cold storage tank 16. The first heat exchanger 6, the second heat exchanger 12, the third heat exchanger 15, the fourth heat exchanger 18, the cold storage tank 16 and the heat storage tank 17 constitute a multi-stage waste heat recovery loop. The fourth heat exchanger 18 transfers heat to water for heating, and the evaporator 24 supplies cooling to external users.

[0025] The high-temperature crude gas produced by the gasifier first enters the first heat exchanger 6, where most of the high-temperature sensible heat is transferred to the circulating working fluid and stored in the heat storage tank 17. Afterward, the cooled gas enters the quench tower 7 for further processing. Simultaneously, the high-temperature exhaust gas discharged from the turbine 14 in the power generation and heating module also undergoes waste heat recovery through the third heat exchanger 15. The heat from these two key heat sources is centrally stored in the heat storage tank 17. This achieves cascaded and deep recovery of the high-temperature gas from the gasifier and the high-temperature exhaust gas from the gas turbine, significantly improving the heat recovery rate and utilization rate of the high-temperature gas and avoiding heat energy waste. After exiting the gasifier 4, the high-temperature crude gas first enters the first heat exchanger 6, where the gas temperature is at its highest, and the tar is still in a gaseous state and not easily condensed. After rapid heat exchange and cooling in the first heat exchanger 6, it immediately enters the quench tower 7. The quench tower 7 can quickly reduce the gas temperature below the tar condensation point and effectively remove impurities such as tar and dust. This design ensures that the main heat exchange process (first heat exchanger 6) occurs before tar condensation, fundamentally preventing tar condensation, scaling, and blockage on the walls of key heat exchangers. This reduces equipment maintenance difficulty and guarantees long-term stable system operation. The heat in the heat storage tank 17 heats air through the second heat exchanger 12, providing a high-temperature working fluid for the Brayton cycle (compressor 11, combustion chamber 13, turbine 14) to drive turbine power generation. Another portion of the heat in the heat storage tank 17 drives the generator 19 of the absorption refrigeration module, providing cooling capacity to the evaporator 24 and achieving the refrigeration function. The low-temperature waste heat after power generation and refrigeration is ultimately used to heat water in the fourth heat exchanger 18, providing heating for external users.

[0026] This invention provides a biomass gasification system that utilizes a first heat exchanger connected in series with a quench tower. This design recovers high-temperature sensible heat from the gas before it enters the quench tower. This pre-recovery, post-quenching process maximizes the extraction of high-grade heat energy from the gasification process and effectively reduces the temperature of the gas entering the quench tower, thereby lessening the load on subsequent quenching and purification equipment. This improves energy recovery rates while reducing the risk of tar condensation. A closed-loop system consisting of a heat storage tank, a cold storage tank, and multiple heat exchangers is constructed to uniformly allocate and utilize the recovered gasification waste heat and gas turbine exhaust waste heat. High-grade heat energy is fed back to the compressor outlet via a second heat exchanger to improve power generation efficiency or to drive an absorption refrigeration module to generate cooling; low-grade waste heat is used to produce hot water via a fourth heat exchanger. This cascaded utilization method expands single-function biomass power generation into combined cooling, heating, and power (CCHP), completely solving the problems of single-function energy utilization and low overall energy efficiency in traditional systems.

[0027] Optionally, the quench tower 7 is also connected in sequence to a scrubbing device 8 and a first condenser 9. The first condenser 9 lowers the gas temperature and reduces the gas dew point through condensation and water removal. Although most of the tar and dust have been removed from the gas exiting the quench tower 7, a small amount of impurities and water vapor may still remain. The scrubbing device 8 (such as a spray scrubbing tower) can further remove fine particles, water-soluble impurities (such as ammonia and chlorine), and residual tar mist, thus deeply purifying the gas. The purified gas enters the first condenser 9, whose main function is to lower the gas temperature through cooling, causing the water vapor in the gas to condense and precipitate, thereby effectively lowering the gas dew point. This ensures that the gas ultimately entering the subsequent systems is clean and has a low water content. This prevents water vapor from condensing and corroding equipment in subsequent pipelines or equipment, and avoids water vapor from adversely affecting the combustion process or thermodynamic cycle, fundamentally guaranteeing the long-term stable operation and efficiency of the core power generation equipment.

[0028] Biomass feedstocks (such as straw and sawdust) typically contain high moisture content. In traditional processes, drying these feedstocks requires additional fossil fuels or electricity, increasing operating costs and carbon emissions.

[0029] To address the aforementioned issues, in this embodiment of the invention, the biomass gasification module further includes a dryer 2 connected to the gasifier 4. The dryer 2 is connected to one outlet of a third heat exchanger 15, and the exhaust gas discharged from the third heat exchanger 15 serves as a heat source for the dryer 2. Using dried biomass feedstock into the gasifier 4 reduces the heat consumed in evaporating moisture from the feedstock. This allows more heat from the gasifier to be used for effective pyrolysis and gasification reactions, helping to improve the gasification efficiency, stabilize the fuel composition and calorific value, and provide a more stable and high-quality fuel input for downstream power generation and waste heat recovery modules, thus forming a positive virtuous cycle from feedstock to energy products.

[0030] After the exhaust gas from turbine 14 recovers most of its medium-to-high temperature heat (used to heat the working fluid in storage tank 16) through the third heat exchanger 15, the discharged low-temperature exhaust gas still contains usable waste heat. This heat is at a moderate temperature, making it ideal for low-temperature drying of biomass feedstocks with high moisture content. The exhaust gas discharged from the third heat exchanger 15 serves as a heat source for dryer 2, achieving a perfect matching of energy utilization from "power generation waste heat (low-temperature section)" to "feedstock pretreatment," completing the final link in the energy utilization chain. It maximizes the exploitation and utilization of thermal energy at each stage within the system, converting low-grade waste heat that might otherwise be directly emitted into valuable pretreatment energy consumption, thereby significantly improving the overall energy utilization efficiency of the entire system. While improving energy efficiency, it directly reduces the system's operating energy consumption and carbon footprint, enhancing the economic competitiveness and environmental friendliness of the entire project.

[0031] The outlet of silo 1, which stores biomass raw materials, is connected to the inlet of dryer 2. The outlet of dryer 2 is connected to the inlet of crushing and screening device 3. The outlet of crushing and screening device 3 is connected to the inlet of gasifier 4. The outlet of gasifier 4 is connected to the inlet of cyclone separator 5. The outlet of cyclone separator 5 is connected to the first inlet of first heat exchanger 6. The first outlet of first heat exchanger 6 is connected to the inlet of quench tower 7. The outlet of quench tower 7 is connected to the inlet of scrubbing device 8. The outlet of scrubbing device 8 is connected to the first inlet of first condenser 9. The first outlet of first condenser 9 is connected to the inlet of buffer chamber 10. These components constitute the biomass gasification module of the system. Scrubbing device 8 includes a venturi scrubber, a packed scrubbing tower, and a demister, used to remove dust, fine tar particles, acidic gases, and moisture from the coal gas.

[0032] When the biomass gasification module starts working, the biomass (such as sawdust, straw, etc.) stored in the biomass silo 1 enters the dryer 2 to dry the wet biomass. The biomass raw material after moisture removal then enters the crushing and screening device 3 to control the dried biomass within a particle size range suitable for use in the gasifier 4. The biomass particles of suitable size after screening enter the gasifier 4, where they undergo drying, pyrolysis, partial combustion, and gasification reactions with the gasifying agent (air, oxygen-enriched gas, or steam, etc.) to generate low-calorific-value combustible gas containing CO, H2, CH4, CO2, H2O, and N2. The combustible gas produced by the gasification reaction then enters the cyclone separator 5, where coarse ash particles are separated under high temperature and high pressure conditions. The crude gas enters the cyclone shell tangentially, forming a high-speed rotating flow field. The particles are thrown against the wall under centrifugal force and fall along the cone to the ash collection hopper. The purified crude gas is discharged from the central upper outlet. The purified crude gas then enters the first heat exchanger 6, transferring heat to the cooling medium from the cold storage tank 16. The cooled crude gas then enters the quench tower 7, rapidly reducing the temperature of the medium- and high-temperature gas to a suitable range for wet purification and causing the tar to quickly condense into droplets. The low-temperature gas then enters the scrubbing unit 8 for further purification. The purified gas then enters the first condenser 9, where its temperature is further reduced and its dew point is lowered through condensation and water removal, preventing secondary condensation during subsequent compression and transportation. It then enters the buffer chamber 10 to balance flow and pressure fluctuations between the preceding and following stages, ensuring the stability of the gas entering the next stage. This completes the workflow of the biomass gasification module.

[0033] Optionally, one outlet of the first heat exchanger 6 and the third heat exchanger 15 are connected to the inlet of the heat storage tank 17 via the first mixing valve 27, and one outlet of the second heat exchanger 12 and the generator 19 are connected to the inlet of the fourth heat exchanger 18 via the second mixing valve 28.

[0034] The first mixing valve 27 is required to mix heat transfer fluids from two different heat sources with different temperatures and flow rates (from the first heat exchanger 6 recovering waste heat from the gasifier and the third heat exchanger 15 recovering waste heat from the turbine tail gas, respectively). By adjusting the first mixing valve 27, the system can dynamically control the total flow rate and mixing temperature of the working fluid entering the thermal storage tank 17. This ensures a stable supply of heat in the thermal storage tank, avoiding drastic temperature changes in the entire thermal storage due to fluctuations in a single heat source (such as gasifier start-up / shutdown or changes in power generation load), and ensuring the stability of the input heat source for subsequent heat-using units (second heat exchanger 12 and generator 19). The heat in the thermal storage tank 17 needs to be supplied to two downstream users simultaneously: the second heat exchanger 12 for power generation and the generator 19 for refrigeration. These two have different temperature requirements for the heat source (power generation requires a higher temperature, while absorption refrigeration has a relatively lower but stable temperature requirement). The second mixing valve 28 is located before the inlet of the fourth heat exchanger 18 (heating heat exchanger). It mixes the utilized low-temperature working fluid from the second heat exchanger 12 (after power generation) and the generator 19 (after cooling). By adjusting the second mixing valve 28, the temperature and flow rate of the working fluid entering the heating system can be precisely controlled. This ensures that the low-temperature waste heat is used for heating to the maximum extent possible, rather than being prematurely or excessively returned to the cold storage tank 16, thereby maximizing the heat exchange temperature difference and utilization efficiency of the entire loop. By stabilizing the return water parameters (temperature) on the heating side, a stable cold-end condition is indirectly provided for the upstream power generation and cooling modules, which is beneficial to their efficient operation.

[0035] At ambient temperature and pressure, the air is connected to the inlet of compressor 11. The outlet of compressor 11 is connected to the second inlet of the second heat exchanger 12. The second outlet of the second heat exchanger 12 is connected to the first inlet of combustion chamber 13. Simultaneously, the outlet of buffer chamber 10 is connected to the second inlet of combustion chamber 13. The outlet of combustion chamber 13 is connected to the inlet of turbine 14. The outlet of turbine 14 is connected to the first inlet of third heat exchanger 15. The first outlet of third heat exchanger 15 is connected to the atmosphere. Meanwhile, the outlet of cold storage tank 16 is connected to the second inlets of both first heat exchanger 6 and third heat exchanger 15. The second outlets of first heat exchanger 6 and third heat exchanger 15 are connected to the inlet of heat storage tank 17 via first mixing valve 27. The outlet of heat storage tank 17 is connected to the first inlet of second heat exchanger 12 and generator 19. The first outlets of second heat exchanger 12 and generator 19 are connected to the first inlet of fourth heat exchanger 18 via second mixing valve 28. The first outlet of fourth heat exchanger 18 is connected to the inlet of cold storage tank 16. The above components constitute the power generation and heating module of the system.

[0036] When the power generation and heating module starts working, the gas stabilized in buffer chamber 10 enters combustion chamber 13, where it mixes and burns with air that has been pressurized by compressor 11 and heated by second heat exchanger 12. The resulting high-temperature gas then enters turbine 14 to expand and generate electricity. The exhaust gas from turbine 14 still has a high temperature and enters third heat exchanger 15 to transfer heat to the cold storage medium from cold storage tank 16. This portion of the cold storage medium is heated and then mixed with the cold storage medium that absorbed heat in first heat exchanger 6 through first mixing valve 27 before being stored in heat storage tank 17. The heat storage medium in heat storage tank 17 is divided into two streams. One stream enters second heat exchanger 12 to transfer heat to compressed air, improving combustion efficiency in the combustion chamber, thereby increasing the inlet temperature of turbine 14 and increasing the system's power generation. The other stream enters generator 19 as the start-up heat source for the absorption refrigeration cycle generator. The two heat storage media, after cooling, still retain a certain temperature. After being mixed through the second mixing valve 28, they enter the fourth heat exchanger 18, where the remaining heat is transferred to the water, generating heating water to supply the users in need. This completes the workflow of the system's power generation and heating module.

[0037] Optionally, the absorption refrigeration module also includes: a heat exchanger 20 and an absorber 23, an evaporator 24 connected to the absorber 23, a circulation loop formed between the generator 19 and the heat exchanger 20, and a circulation loop formed between the heat exchanger 20 and the absorber 23.

[0038] The third outlet of generator 19 is connected to the first inlet of the second condenser 26. The first outlet of the second condenser 26 is connected to the inlet of the second expansion valve 25. The outlet of the second expansion valve 25 is connected to the first inlet of the evaporator 24. The first outlet of the evaporator 24 is connected to the first inlet of the absorber 23. The first outlet of the absorber 23 is connected to the inlet of the booster pump 21. The outlet of the booster pump 21 is connected to the first inlet of the heat exchanger 20. The first outlet of the heat exchanger 20 is connected to the second inlet of generator 19. Simultaneously, the second outlet of generator 19 is connected to the second inlet of heat exchanger 20. The second outlet of heat exchanger 20 is connected to the inlet of the first expansion valve 22. The outlet of the first expansion valve 22 is connected to the second inlet of absorber 23. These components constitute the absorption refrigeration module of the system.

[0039] When the absorption refrigeration module operates, generator 19 absorbs heat and begins to work, evaporating part of the refrigerant in the concentrated refrigerant absorbent solution. The refrigerant vapor enters the second condenser 26 and condenses into a liquid state. It then passes through the second expansion valve 25 into the evaporator 24 to supply cooling to external users, and subsequently enters the absorber 23. After generator 19 absorbs heat and precipitates some refrigerant, the dilute refrigerant absorbent solution enters the heat exchanger 20, absorbs heat again, and then passes through the first expansion valve 22 into the absorber 23, where it mixes with the refrigerant returning from the evaporator 24 to revert to a concentrated refrigerant absorbent solution. The concentrated refrigerant absorbent solution is then pumped by booster pump 21 into the heat exchanger 20 to provide heat before returning to generator 19 to continue the absorption refrigeration cycle. This completes the workflow of the system's absorption refrigeration module.

[0040] Optionally, a control module is also included. The control module includes a tar dew point monitoring unit installed at the first heat exchanger 6 and a controller connected thereto. The tar dew point monitoring unit is used to collect temperature, pressure and composition data of the gas. The controller obtains the tar dew point temperature based on the temperature, pressure and composition data of the gas. When the temperature difference between the tar dew point temperature and the tube wall of the first heat exchanger 6 exceeds a preset threshold (10℃~30℃), the controller controls the cooling medium flow regulating valve of the first heat exchanger 6 (for example, reducing the cooling flow to increase the tube wall temperature) to ensure that the tube wall temperature is always higher than the tar dew point and to avoid tar condensation and scaling.

[0041] Optionally, the control module also includes a gas dew point monitoring unit located at the outlet of the quench tower 7. This unit monitors the actual temperature and relative humidity of the gas. The controller obtains the water dew point temperature in the gas based on these parameters. When the temperature difference between the actual gas temperature and the water dew point temperature is less than the safety margin, the controller adjusts the cooling medium flow regulating valve of the first heat exchanger 6 to control the temperature entering the quench tower 7, ensuring that the gas temperature is always higher than the water dew point temperature in the gas, thus preventing condensation near the gasifier 4 outlet or in the gas pipeline. The specific formula is as follows:

[0042] In the formula: T represents the gas temperature, P sat ( T () represents the saturated water vapor pressure at temperature T. P w Represents the partial pressure of water vapor, in kPa; RH T represents relative humidity. dp_water This represents the water dew point temperature in the gas.

[0043] Optionally, the control module also includes differential pressure sensors respectively installed at the first heat exchanger 6, the quench tower 7 and the first condenser 9. When the pressure drop detected by any differential pressure sensor exceeds a preset threshold, the controller issues an online cleaning or maintenance alarm.

[0044] The biomass gasification system provided by this invention employs feedforward control to predict changes in system state before they occur through real-time monitoring of key parameters, and adjusts system operation accordingly. The feedback mechanism involves setting control rules and logic to link multiple parameters, ensuring the safety and stability of the system during actual operation. Specifically, the system collects various data such as temperature, pressure, and flow rate in real time using installed sensors. This data is analyzed to predict potential problems such as scaling and blockage. Based on the predictions, relevant parameters are adjusted, and proactive measures are taken, such as changing the gas flow rate or adjusting the heat exchanger's operating mode. When potential risks arise (e.g., excessively high tar dew point or excessive pressure drop), the system automatically controls the corresponding equipment to prevent further deterioration. Furthermore, during system operation, all key parameters are continuously monitored to ensure the entire system operates at its optimal state.

[0045] Anti-tar condensation control strategy based on tube wall temperature difference (feedforward control): To prevent tar from condensing on the heat exchanger surface and forming a difficult-to-remove scale layer, the system executes the following logic: The system calculates the heat exchanger tube wall temperature in real time. Tw With tar dew point Tdp The difference.

[0046] When detected Tw - Tdp When the temperature drops to a preset safety threshold (15℃~30℃ in this embodiment), the system is determined to have entered the tar precipitation risk zone. The controller automatically outputs an adjustment signal to the cooling medium flow regulating valve of the first heat exchanger 6, thereby increasing the pipe wall temperature by reducing the cooling medium flow or increasing the cooling medium inlet temperature, forcing it to be at least 15℃ higher than the tar dew point, thus physically preventing tar from condensing on the pipe wall.

[0047] The reheat feedback control strategy based on superheat (feedback control) implements the following logic to prevent condensation from forming in the pipeline after rapid cooling and washing of the gas: Real-time temperature of gas collected after the outlet of quench tower 7 and scrubbing unit 8 Tgas and the calculated water dew point temperature Tdp_water And calculate the superheat. Delta T = Tgas - Tdp_water .

[0048] When the heat Delta TWhen the flow rate is below the set lower limit, it indicates that the gas is close to saturation and there is a risk of condensation and corrosion. By adjusting the flow rate of the cooling medium in the first condenser 9, it is ensured that the gas is always in an unsaturated superheated state when entering the buffer chamber 10 and subsequent pipelines.

[0049] Resistance interlock control strategy based on differential pressure monitoring (safety protection): Continuously monitor the pressure drop of the first heat exchanger 6, quench tower 7, scrubbing unit 8, and first condenser 9—that is, all equipment located along the biomass crude gas flow path. Delta P。

[0050] when Delta P If the system's alarm threshold is exceeded, or the pressure drop rate is too rapid, it indicates that there may be ash or tar buildup inside the equipment. The system will issue an online cleaning or maintenance alarm to prevent safety accidents caused by excessive back pressure in the gasifier due to blockage.

[0051] The second part of this invention provides a biomass gasification method as described above, comprising the following steps: After being dried and pulverized, the biomass is gasified in gasifier 4 to produce crude coal gas. After dust removal, the crude coal gas enters the first heat exchanger 6 for high-temperature waste heat recovery. The cooled gas enters the quench tower 7 for rapid cooling; The cooled gas and the air preheated by the second heat exchanger 12 are burned in the combustion chamber 13 to drive the turbine 14 to generate electricity. The exhaust gas from turbine 14 enters the third heat exchanger 15 to recover waste heat, which is then stored together with the heat recovered by the first heat exchanger 6 in the heat storage tank 17. Part of the heat storage medium is used to preheat the air, and the other part drives the absorption refrigeration module to cool. The waste heat after cooling is further processed into domestic hot water or heating water through the fourth heat exchanger 18.

[0052] Optional, also includes: Real-time monitoring of the temperature, pressure and composition data of the gas at the first heat exchanger 6, the actual temperature and relative humidity of the gas at the outlet of the quench tower 7, and the pressure difference at the first heat exchanger 6, the quench tower 7 and the first condenser 9. Based on the monitoring data, the tar dew point temperature, water dew point temperature and pressure difference are obtained to predict the risks of scaling, blockage and condensation corrosion, and feedforward control is carried out by adjusting the cooling medium flow rate or the heat exchanger operation mode of the first heat exchanger 6. When abnormal parameters are detected, the protection mechanism is automatically triggered to perform feedback adjustments.

[0053] Heat exchanger pressure drop and rate of pressure drop increase: Pressure loss occurs when airflow passes through the pipes inside the heat exchanger. The system measures the pressure drop in the heat exchanger section and monitors the rate of pressure drop change by installing differential pressure sensors. Pressure drop sensors are typically installed at the inlet and outlet of the heat exchanger, while the rate of pressure drop sensor is usually installed at the outlet. These sensors are primarily used to monitor changes in the heat exchanger's condition and prevent the risks of scaling, blockage, and decreased heat exchange efficiency.

[0054] Oxygen concentration: Installed in the pipelines before and after the gasifier outlet, heat exchanger inlet and outlet, and quench tower outlet. Used to monitor the oxygen concentration in the gas to prevent the gasifier from producing excessive oxygen and to prevent incomplete combustion or the generation of hazardous gases.

[0055] Temperature and flow sensors: installed at the inlet and outlet of various components, mainly used to monitor the system temperature and flow in real time, judge the system operating status in real time, and prevent system safety accidents.

[0056] Preferably, the working fluid used in the absorption refrigeration cycle of the present invention can be an ammonia solution or a lithium bromide solution.

[0057] In summary, this invention provides a biomass gasification system that enables efficient waste heat recovery and multi-stage utilization. By connecting the first heat exchanger 6 in series with the quench tower, it effectively recovers high-temperature heat from the gasification process and gas turbine exhaust, and utilizes it in multiple stages, significantly improving the system's thermal efficiency. The high-temperature waste heat is first used to heat the low-temperature coal gas, and then supplied to loads such as absorption chillers, achieving multi-stage energy distribution and maximizing energy utilization, thus avoiding energy waste. Specific advantages include:

[0058] (1) By combining high-temperature waste heat recovery with combined cooling and heating functions, the system can not only effectively recover heat during the gasification process, but also provide energy for cooling and heating, thereby improving the overall energy efficiency of the system. By recycling waste heat to generate cooling and heating energy, the external energy consumption can be significantly reduced, operating costs can be lowered, and the system can achieve energy-saving effects.

[0059] (2) This invention can efficiently utilize the waste heat and waste gas emissions generated during biomass gasification, while reducing dependence on fossil fuels and emissions of carbon dioxide and other greenhouse gases by improving energy conversion efficiency. The system has good environmental performance and helps to mitigate climate change and related environmental problems.

[0060] (3) The system of the present invention adopts a precise temperature and pressure control strategy, especially in the high-temperature waste heat recovery and rapid cooling process, using feedforward control technology to effectively prevent problems such as tar accumulation and system scaling, and ensure the long-term stable operation of the equipment. The efficient energy conversion and recovery mechanism enables the system to have a longer operating cycle and lower maintenance costs.

[0061] (4) The design structure of this invention is simple and the pressure level is low. Therefore, the system does not depend on specific geographical conditions and can be widely used in industrial waste heat recovery, distributed energy systems and other scenarios in different regions, with strong adaptability. It is particularly suitable for energy-intensive industries such as chemical and power, and can effectively improve the energy utilization efficiency of these industries.

[0062] The above inventions are merely a few specific embodiments of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A biomass gasification system, characterized by, include: Biomass gasification module, power generation and heating module, and absorption refrigeration module; The biomass gasification module includes a gasifier, a first heat exchanger, and a quench tower connected in sequence; the power generation and heating module includes a compressor, a second heat exchanger, a combustion chamber, a turbine, and a third heat exchanger; and the absorption refrigeration module includes a generator, a second condenser, and an evaporator. One inlet of the first heat exchanger and one outlet of the third heat exchanger are respectively connected to the outlet of the cold storage tank. One outlet of the first heat exchanger and one outlet of the third heat exchanger are respectively connected to the inlet of the cold storage tank. The outlet of the cold storage tank is respectively connected to one inlet of the second heat exchanger and one outlet of the generator. One outlet of the second heat exchanger and one outlet of the generator are connected to the inlet of the fourth heat exchanger. One outlet of the fourth heat exchanger is connected to the inlet of the cold storage tank. The first heat exchanger, the second heat exchanger, the third heat exchanger, the fourth heat exchanger, the cold storage tank, and the hot storage tank constitute a multi-stage waste heat recovery loop. The fourth heat exchanger transfers heat to water for heating, and the evaporator supplies cold energy to external users. It also includes a control module, which includes a tar dew point monitoring unit installed at the first heat exchanger and a controller connected thereto. The tar dew point monitoring unit is used to collect the temperature, pressure and composition data of the gas. The controller obtains the tar dew point temperature based on the temperature, pressure and composition data of the gas. When the temperature difference between the tar dew point temperature and the temperature of the tube wall of the first heat exchanger exceeds a preset threshold, the controller controls the cooling medium flow regulating valve of the first heat exchanger. The control module also includes a gas dew point monitoring unit installed at the outlet of the quench tower. The gas dew point monitoring unit is used to monitor the actual temperature and relative humidity of the gas. The controller obtains the water dew point temperature in the gas based on the actual temperature and relative humidity of the gas. When the temperature difference between the actual temperature of the gas and the water dew point temperature is less than the safety margin, the controller adjusts the cooling medium flow regulating valve of the first heat exchanger to control the temperature entering the quench tower, so as to prevent condensation from occurring near the gasifier outlet or in the gas pipeline.

2. The biomass gasification system of claim 1, wherein, The quench tower is also connected in sequence to a washing device and a first condenser. The first condenser reduces the gas temperature and lowers the gas dew point by condensing and removing water.

3. The biomass gasification system of claim 1, wherein, The biomass gasification module also includes a dryer connected to the gasifier. The dryer is connected to one outlet of a third heat exchanger, and the exhaust gas discharged from the third heat exchanger is provided to the dryer as a heat source.

4. The biomass gasification system of claim 1, wherein, One outlet of the first heat exchanger and one outlet of the third heat exchanger are respectively connected to the inlet of the heat storage tank through a first mixing valve, and one outlet of the second heat exchanger and one outlet of the generator are connected to the inlet of the fourth heat exchanger through a second mixing valve.

5. The biomass gasification system of claim 1, wherein, The absorption refrigeration module further includes a heat exchanger and an absorber, the evaporator is connected to the absorber, a circulation loop is formed between the generator and the heat exchanger, and a circulation loop is formed between the heat exchanger and the absorber.

6. The biomass gasification system of claim 1, wherein, The control module also includes differential pressure sensors respectively installed at the first heat exchanger, the quench tower and the first condenser. When the pressure drop detected by any differential pressure sensor exceeds a preset threshold, the controller issues an online cleaning or maintenance alarm.

7. A gasification method using the biomass gasification system according to any one of claims 1 to 6, characterized by, Includes the following steps: After being dried and pulverized, biomass is gasified in a gasifier to produce crude coal gas. After dust removal, the crude coal gas enters the first heat exchanger for high-temperature waste heat recovery. The cooled gas enters a rapid cooling tower for quick cooling. The cooled coal gas and the air preheated by the second heat exchanger are burned in the combustion chamber to drive the turbine to generate electricity; Turbine exhaust enters the third heat exchanger to recover waste heat, which is then stored together with the heat recovered by the first heat exchanger in a heat storage tank. Part of the heat storage medium is used to preheat the air, and the other part drives the absorption refrigeration module to cool. The waste heat from the cooling process is further processed into domestic hot water or heating water through a fourth heat exchanger.

8. The method of gasifying biomass according to claim 7, wherein, Also includes: Real-time monitoring of the temperature, pressure and composition data of the gas at the first heat exchanger, the actual temperature and relative humidity of the gas at the outlet of the quench tower, and the pressure difference at the first heat exchanger, the quench tower and the first condenser. Based on monitoring data, tar dew point temperature, water dew point temperature and pressure difference are obtained to predict the risks of scaling, blockage and condensation corrosion, and feedforward control is carried out by adjusting the cooling medium flow rate of the first heat exchanger or the heat exchanger operation mode. When abnormal parameters are detected, the protection mechanism is automatically triggered to perform feedback adjustments.

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