System for preparing SAF by microwave heating of biomass

Abstract

The invention discloses a system for preparing sustainable aviation fuel (SAF) by microwave heating of biomass. The system comprises a microwave pretreatment unit, a microwave conversion unit and a microwave hydrogenation fractionation unit which are sequentially connected, and an energy recovery unit and an intelligent alarm unit which are respectively connected with the three units. The microwave pretreatment unit is used for drying, degreasing and structure loosening of biomass raw materials; the microwave conversion unit is used for pyrolyzing, hydrolyzing and gasifying the pretreated biomass to generate an intermediate product; the microwave hydrogenation fractionation unit is used for hydrodeoxygenation and fractionation of the intermediate product to generate SAF; the energy recovery unit is used for recovering waste heat of each unit and assisting in heating; the intelligent alarm unit is used for regulating and controlling operation parameters of each unit. According to the system, the problems of uneven heating and the like in the prior art are solved through the multi-feed-port microwave cavity, the dielectric additive adding device and the microwave drying and loosening integrated device, and efficient, stable and low-energy-consumption conversion preparation of SAF from biomass is achieved.

Description

Technical Field

[0001] This invention relates to the field of biomass conversion technology, and in particular to a microwave-heated biomass-to-SAF system. Background Technology

[0002] With the increasing demand for decarbonization in the global aviation industry, biomass-based SAF (Self-Produced Oil) has become a research hotspot due to its renewable raw materials and low carbon emissions. Microwave heating technology, with its characteristics of "uniform heating and precise temperature control," demonstrates advantages in biomass pretreatment and conversion. However, existing technologies have the following drawbacks: 1. Large-scale heating blind spots: Laboratory-scale microwave equipment (kilogram level) can achieve uniform heating, but when scaled up to industrial production, a single microwave feed port leads to a large temperature gradient inside the cavity (temperature difference > 20℃), resulting in localized carbonization or incomplete conversion of materials, with a bio-oil yield of only 50-55%; 2. Low energy efficiency: Industrial-grade microwave equipment has an energy conversion rate of only 60-70%, and waste heat is not recovered in each stage, resulting in energy consumption of over 800 kWh / ton per unit of SAF; 3. Insufficient material processing adaptability: Biomass raw materials are classified into categories such as lignocellulose and waste oil. Single-frequency or single-cavity pretreatment equipment cannot simultaneously cover the above ranges in terms of drying depth and loose specific surface area. Material changes require shutdown and modification or the addition of auxiliary units, resulting in insufficient system adaptability. Summary of the Invention

[0003] To address the aforementioned problems, this invention provides a microwave-heated biomass-to-SAF system, aiming to solve the issues of uneven heating within the cavity and insufficient raw material compatibility caused by large-scale heating in existing technologies. The specific solution of this invention is as follows:

[0004] A microwave-heated biomass SAF production system includes a microwave pretreatment unit, a microwave conversion unit, and a microwave hydrogenation fractionation unit connected in sequence, as well as an energy recovery unit and an intelligent alarm unit connected to the microwave pretreatment unit, microwave conversion unit, and microwave hydrogenation fractionation unit, respectively.

[0005] The microwave pretreatment unit is used for drying, degreasing, and loosening the structure of biomass raw materials;

[0006] The microwave conversion unit is used for the pyrolysis, hydrolysis, and gasification of pretreated biomass to generate intermediate products; the intermediate products are bio-oil vapor and syngas.

[0007] The microwave hydrogenation fractionation unit is used for the hydrogenation, deoxygenation, and fractionation of intermediate products to generate SAF;

[0008] The energy recovery unit is used to recover waste heat from each unit and provide auxiliary heating.

[0009] The intelligent alarm unit is used to collect data from each unit and automatically trigger an alarm.

[0010] Furthermore, the microwave conversion unit includes:

[0011] A spiral material conveying device; a modular multi-feed microwave cavity; a dielectric additive adding mechanism; an inert gas introducing mechanism; the modular multi-feed microwave cavity is composed of multiple rectangular waveguide cavity modules connected in series by flanges, each module has a microwave feed port on its top, and at least 4 microwave feed ports are evenly arranged along the material conveying direction; the microwave feed port includes a magnetron, a waveguide tuner, and a power detector.

[0012] Furthermore, the microwave pretreatment unit includes an integrated microwave drying and loosening device. The device includes an inner cavity and an outer cavity. The inner cavity uses 915MHz low-frequency microwaves for drying, and the outer cavity is equipped with a 2450MHz microwave radiator and a frequency conversion airflow disturbance mechanism.

[0013] Furthermore, the microwave hydrogenation fractionation unit includes: a microwave-assisted hydrogenation reactor and a microwave-assisted fractionation tower; the microwave-assisted hydrogenation reactor has a built-in high-frequency microwave generator and a catalyst fixed bed; the microwave-assisted fractionation tower has a built-in microwave heating module.

[0014] Furthermore, the energy recovery unit includes:

[0015] Waste heat exchanger, infrared auxiliary heating module, energy storage device.

[0016] Furthermore, the intelligent alarm unit includes:

[0017] The parameter acquisition module is used to acquire temperature, pressure, microwave power and material flow data of each unit in real time;

[0018] The fault early warning module is communicatively connected to the parameter acquisition module and is used to trigger an alarm; the conditions for triggering the alarm are either a temperature deviation > 5℃ or a pressure fluctuation > 0.1MPa.

[0019] Furthermore, the system also includes a raw material crushing unit and a product storage unit; the raw material crushing unit is used to crush biomass raw materials to supply the microwave pretreatment unit; the product storage unit is used to store SAF products to prevent them from oxidizing and deteriorating.

[0020] Furthermore, the spiral material conveying device has built-in temperature and pressure sensors, and the surface of the conveying spiral is coated with a dielectric-enhancing coating with a dielectric constant of 3.0-3.5.

[0021] Furthermore, the inert gas inlet mechanism is used to introduce inert gas into the multi-feed oral cavity. The inert gas is either N2 or Ar, and the gas flow rate is 0.5-1 m³ / min. 3 / h.

[0022] Furthermore, the dielectric additive mechanism is used to add a dielectric additive; the dielectric additive is one of nano Fe3O4 and activated carbon; the amount of dielectric additive added is 1%-3% of the mass of the biomass raw material.

[0023] The present invention has the following beneficial effects:

[0024] 1. Improve heating uniformity

[0025] The multi-feed microwave cavity design solves the problem of uneven temperature caused by a single microwave feed in traditional microwave heating. Furthermore, the dielectric enhancement coating on the spiral conveyor, along with the addition of dielectric additives, ensures that the material receives uniform heat distribution during heating, thereby improving conversion efficiency and bio-oil yield.

[0026] 2. Optimize the adaptability of raw materials for processing

[0027] The microwave pretreatment unit of this invention combines a dual-layer heating method of low-frequency microwaves and high-frequency microwaves, which can effectively solve the pretreatment problems of different types of biomass raw materials, improve the reactivity of the subsequent pyrolysis process, and reduce the dependence on traditional drying and loosening equipment.

[0028] 3. Improve energy conversion efficiency and reduce production energy consumption.

[0029] By integrating a waste heat recovery unit and an infrared auxiliary heating module into the system, waste heat generated by each processing unit is recovered and reused. This design effectively reduces external energy consumption, lowers the energy consumption per unit of SAF production, and improves the overall system energy efficiency. Attached Figure Description

[0030] Figure 1 This is a flowchart of the present invention;

[0031] Figure 2 This is a schematic diagram of the microwave conversion unit of the present invention;

[0032] Figure 3 This is a schematic diagram of the microwave hydrogenation fractionation unit of the present invention;

[0033] Figure 4 This is a schematic diagram of the energy recovery unit of the present invention;

[0034] Figure 5 This is a schematic diagram of the microwave preprocessing unit of the present invention;

[0035] Figure 6 This is a schematic diagram of the intelligent alarm unit of the present invention. Detailed Implementation

[0036] The following will refer to the appendix of this invention. Figures 1-6 The technical solutions in the embodiments of the present invention will be clearly and completely described together. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0037] Partial interpretation:

[0038] Structural loosening: refers to making the structure of biomass more loose, increasing its specific surface area; Pyrolysis: heating biomass to high temperatures to decompose it into liquid and gaseous products; Hydrolysis: decomposing biomass into simpler chemical substances through water or steam treatment; Gasification: converting biomass into syngas, the main components of which include hydrogen, carbon monoxide, and a small amount of carbon dioxide; Hydrodeoxygenation: removing oxygen from intermediate products using hydrogen under high temperature and high pressure conditions; Fractionation tower: classifying fractions according to different temperature ranges during the fractionation process to ensure that different types of hydrocarbon components can be accurately separated.

[0039] The spiral material conveying device, modular microwave cavity, dielectric additive addition mechanism, inert gas introduction mechanism, microwave-assisted hydrogenation reactor, microwave-assisted fractionation tower, raw material crushing unit, waste heat converter, infrared auxiliary heating module, energy storage device, parameter acquisition module, fault early warning module, microwave radiator, frequency conversion airflow disturbance mechanism, pressure sensor and temperature sensor mentioned in this technical solution are all existing devices.

[0040] Example 1

[0041] This embodiment provides a microwave-heated biomass SAF production system, including:

[0042] A microwave-heated biomass-to-SAF (Synthesis Oil Fusion) system includes a microwave pretreatment unit, a microwave conversion unit, and a microwave hydrogenation fractionation unit connected in sequence, as well as an energy recovery unit and an intelligent alarm unit connected to the microwave pretreatment unit, microwave conversion unit, and microwave hydrogenation fractionation unit, respectively. The microwave pretreatment unit is used for drying, degreasing, and loosening the structure of the biomass raw material. The microwave conversion unit is used for the pyrolysis, hydrolysis, and gasification of the pretreated biomass to generate intermediate products, namely bio-oil vapor and syngas. The microwave hydrogenation fractionation unit is used for the hydrogenation, deoxygenation, and fractionation of the intermediate products to generate SAF. The energy recovery unit is used to recover waste heat from each unit and provide auxiliary heating. The intelligent alarm unit is used to collect data from each unit and automatically trigger an alarm.

[0043] To better understand this invention, the details are as follows:

[0044] First, the microwave conversion unit includes: a spiral material conveying device; a modular multi-feed microwave cavity; a dielectric additive adding mechanism; and an inert gas introduction mechanism. The modular multi-feed microwave cavity is composed of multiple rectangular waveguide cavity modules connected in series via flanges. Each module has a microwave feed port on its top, and at least four microwave feed ports are evenly arranged along the material conveying direction. The microwave feed port includes a magnetron, a waveguide tuner, and a power detector.

[0045] Specifically, a spiral material conveyor is used to transport biomass raw materials from the inlet to the heating area of ​​the microwave cavity, ensuring uniform distribution of the material within the cavity. The conveyor's structural design includes a spiral conveyor belt or propeller-like structure, propelling the material forward during microwave heating and ensuring sufficient contact between the material and microwaves. The spiral conveyor belt design ensures uniform material distribution within the microwave cavity, preventing uneven heating or carbonization caused by uneven material flow. The conveyor belt surface is coated with a dielectric-enhancing coating with a dielectric constant of 3.0-3.5, which improves the material's microwave absorption capacity, ensuring uniform distribution of microwave energy and improving heating efficiency. The modular multi-feed microwave cavity provides a uniform microwave heating area through the series combination of rectangular waveguide cavity modules. Key features of this cavity design include: the microwave cavity consists of multiple rectangular waveguide cavity modules connected by flanges, with a microwave feed port on the top of each module. This modular design not only improves the flexibility of the microwave cavity but also allows for easy adjustment of the number and size of cavities to meet different production scales. Along the material conveying direction, the microwave cavity is uniformly equipped with at least four microwave feed ports. This multiple feed port design ensures that microwave energy is evenly distributed to every area of ​​the material, avoiding the problem of excessive temperature gradients caused by a single microwave feed port, thus greatly improving the uniformity of the heating process. Each microwave feed port works in concert with a magnetron, waveguide tuner, and power detector to ensure precise control and transmission of microwave energy. Each microwave cavity module has a microwave feed port at its top, which consists of the following components: a magnetron, used to generate microwave energy and transmit it into the cavity, precisely adjusting the output microwave power to ensure the stability and uniformity of microwave energy; a waveguide tuner, used to adjust the propagation mode and frequency of microwaves in the cavity to ensure efficient microwave energy transmission, enabling microwaves to be effectively delivered to the material; and a power detector, used to monitor the microwave power within the cavity and feed it back to the control system to ensure that the microwave power is always at its optimal level, avoiding uneven heating caused by excessively high or low power output. In the microwave conversion unit, a dielectric additive addition mechanism is used to add dielectric additives (such as nano-Fe3O4 or activated carbon) to the biomass raw materials. The role of dielectric additives is to increase the dielectric constant of biomass raw materials, enabling them to absorb microwave energy more effectively and enhancing microwave heating efficiency. Nano-Fe3O4 or activated carbon, as commonly used dielectric additives, have high dielectric constants and can significantly improve the microwave absorption capacity of the materials. The amount of dielectric additive added is typically 1%-3% of the biomass raw material mass. By precisely controlling the addition amount, optimal heating effect is ensured during microwave heating. An inert gas introduction mechanism is used to introduce inert gas (such as nitrogen (N2) or argon (Ar)) into the cavity of the microwave conversion unit. During high-temperature pyrolysis, the inert gas effectively inhibits oxidation reactions, preventing oxygen from participating in the reaction, thereby reducing the formation of tar and other harmful byproducts.By controlling the gas flow rate, inert gas helps improve the yield and quality of bio-oil and reduces unnecessary byproducts, especially tar formation. Based on experimental results, the inert gas flow rate was set to 0.5 m. 3 / h to 1m 3 At a rate of [value missing] / h, microwave heating can effectively suppress oxidation reactions and improve bio-oil yield and syngas quality. Experiments show that within this range, microwave heating exhibits the best uniformity and energy absorption, ensuring efficient biomass conversion.

[0046] Further explanation is needed regarding the specific reasons for choosing a coating with a dielectric constant in the range of 3.0-3.5: Firstly, it improves microwave energy absorption efficiency. Biomass raw materials typically have low dielectric constants, especially lignocellulosic materials and certain waste oils, which have poor microwave absorption. If the dielectric constant is too high, it may lead to excessively high surface temperatures, causing overheating or localized over-scorching, thus reducing heating efficiency and effectiveness. A range of 3.0-3.5 is relatively moderate, effectively enhancing microwave absorption while avoiding excessive heat absorption, ensuring a more uniform temperature distribution during heating. Materials such as nano-Fe3O4 (nano-ferrite) and activated carbon typically have dielectric constants between 3.0 and 4.0. Choosing a range of 3.0-3.5 ensures sufficient microwave absorption capacity while avoiding localized overheating caused by excessively high dielectric constants. Secondly, it adapts to various raw materials. This dielectric constant range can accommodate the heating needs of different types of biomass raw materials, including lignocellulosic materials and waste oils. Since different raw materials have significantly different dielectric properties, selecting a coating with a dielectric constant in the range of 3.0-3.5 can maximize the heating effect of the raw materials.

[0047] It should be further explained that the addition amount of dielectric additive is set at 1%-3%, which is determined by comprehensively considering the following factors: In terms of heating efficiency, at lower addition amounts, the dielectric additive can significantly increase the microwave absorption efficiency of biomass raw materials and improve heating uniformity. For many biomass raw materials, 1% dielectric additive is sufficient to provide adequate microwave energy absorption and enhance the heating effect. While adding 1% dielectric additive improves microwave absorption capacity, the small amount prevents excessive heat absorption, thus avoiding the risk of localized overheating and material charring due to excessive heat absorption. Therefore, 1% is a moderate increase that effectively improves microwave heating efficiency without causing negative effects. Increasing the addition amount of dielectric additive to 3% can further significantly improve microwave heating efficiency. This can greatly enhance the microwave heating absorption capacity and reactivity of some biomass raw materials that are difficult to pyrolyze (such as lignocellulosic materials), accelerating the conversion process and reducing heating time. However, 3% is the upper limit for the amount added. Exceeding this percentage may lead to excessive microwave absorption, increasing the risk of localized overheating and charring, potentially affecting product quality or causing uneven heating. From an economic cost perspective, a 1% addition is a more economical option, meeting basic microwave heating requirements and suitable for biomass feedstocks with low energy absorption requirements. A 3% addition is suitable for biomass feedstocks requiring higher conversion efficiency. Although the cost increases slightly, the improved heating efficiency reduces energy consumption during the conversion process, thus maintaining high economic viability.

[0048] Secondly, the microwave pretreatment unit includes an integrated microwave drying and loosening device. The microwave pretreatment unit includes an integrated microwave drying and loosening device, which includes an inner cavity and an outer cavity. The inner cavity uses 915MHz low-frequency microwaves for drying, and the outer cavity is equipped with a 2450MHz microwave radiator and a frequency conversion airflow disturbance mechanism.

[0049] Specifically, the integrated microwave drying and loosening device in the microwave pretreatment unit includes an inner cavity and an outer cavity. The inner cavity contains uniformly distributed 915MHz low-frequency microwave radiators, which are connected to an external microwave source via waveguides, providing uniform microwave energy to the entire cavity. The 915MHz low-frequency microwaves are used to dry the biomass raw materials. The biomass raw materials first enter the inner cavity, where the low-frequency microwave energy penetrates the material, heating it from the inside out, causing water molecules to vibrate and evaporate rapidly. For dense lignocellulosic biomass, the strong penetrating power of the low-frequency microwaves ensures rapid evaporation of internal moisture, solving the problem of traditional drying methods' inability to reach deep into the material. The microwave power range of the inner cavity is set between 500W and 1000W, with the specific power adjusted according to the moisture content of the material to ensure high efficiency and uniformity in the drying process. The outer cavity is equipped with a 2450MHz high-frequency microwave radiator and a variable-frequency airflow disturbance mechanism. High-frequency microwaves primarily act on the surface of materials, heating the fibrous structure of biomass to make it more porous, increasing the specific surface area and thus enhancing its reactivity. A variable-frequency airflow disturbance mechanism further promotes the uniformity of microwave heating by adjusting the airflow rate, while simultaneously loosening and dispersing the material's fibrous structure. The inner and outer cavities are connected by a material transition channel, and the two cavities are isolated by microwave shielding materials and structures to ensure efficient utilization of microwave energy within their respective cavities. Temperature sensors and control devices are installed in the connection area between the inner and outer cavities to monitor and regulate the temperature in real time, ensuring a smooth temperature transition when the material moves from the inner to the outer cavity. After drying in the inner cavity, the biomass raw material enters the outer cavity through the transition channel. The high-frequency microwave radiator heats the material surface, while the variable-frequency airflow disturbance mechanism further promotes the uniformity of microwave heating by adjusting the airflow rate (typically 1 to 2 m / s). An airflow rate of 1 to 2 m / s provides appropriate airflow disturbance during microwave heating while increasing the specific surface area of ​​the biomass feedstock. The power of the microwave radiator in the outer cavity is set between 800W and 1200W. Compared to traditional single-cavity equipment, which lacks additional parameters for adjustment when changing feedstocks and requires shutdown for auxiliary drying or loosening equipment, the power adjustment of the dual-cavity system allows for flexible control of the heating process based on the type and characteristics of the material. Low-frequency microwave energy evaporates internal water, while high-frequency energy expands the specific surface area of ​​the remaining material. For any type of feedstock, only parameters (such as the power of the inner and outer cavities, residence time, and airflow rate) need to be changed, while the cavity structure remains unchanged. The power distribution between the inner and outer cavities determines the heating ratio between the deep and surface layers. After pretreatment, the biomass feedstock undergoes subsequent pyrolysis, hydrolysis, and gasification processes under microwave heating.Specifically, during pyrolysis, biomass undergoes cracking at high temperatures, generating bio-oil vapor, syngas, and biochar; during hydrolysis, cellulose and hemicellulose are converted into soluble sugars; and during gasification, biomass is converted into syngas, primarily consisting of gases such as carbon monoxide (CO) and hydrogen (H2). These processes utilize microwave heating technology to improve conversion efficiency and generate intermediate products for energy production or chemical synthesis.

[0050] It should be noted that the inner cavity uses 915MHz low-frequency microwaves because 915MHz microwaves have strong penetrating power, effectively penetrating thick biomass materials and deeply heating the material. Low-frequency microwaves are particularly sensitive to water molecules, making them very effective in moisture evaporation and material drying. The 915MHz frequency ensures that water molecules in the material efficiently absorb microwave energy, rapidly evaporating moisture and achieving fast drying. The outer cavity uses a 2450MHz high-frequency microwave radiator because 2450MHz high-frequency microwaves have strong surface heating capabilities, more effectively heating the surface of materials and making them suitable for the loosening of biomass. Furthermore, 2450MHz is a commonly used frequency in commercial microwave heating equipment, widely used in household appliances and industrial equipment (such as microwave ovens, food heating, etc.), thus offering good equipment stability, controllability, and economy.

[0051] Furthermore, the microwave hydrogenation fractionation unit includes: a microwave-assisted hydrogenation reactor; and a microwave-assisted fractionation tower.

[0052] The microwave-assisted hydrogenation reactor has a built-in high-frequency microwave generator and a catalyst fixed bed; the microwave-assisted fractionation tower has a built-in microwave heating module.

[0053] Specifically, the microwave-assisted hydrogenation fractionation unit includes a microwave-assisted hydrogenation reactor and a microwave-assisted fractionation tower. The microwave-assisted hydrogenation reactor is mainly used for the hydrodeoxygenation treatment of intermediate products (such as bio-oil vapor and syngas). The reactor incorporates a high-frequency microwave generator, typically operating in the 2450MHz band. This frequency effectively penetrates the reactants and heats the catalyst and reactants inside the reactor. The energy of the microwave generator can be precisely adjusted to ensure the hydrogenation reaction proceeds at the optimal temperature. A catalyst fixed bed is also provided within the reactor to support the efficient operation of the catalyst during the reaction. The choice of catalyst depends on the type of reaction; nickel-based catalysts or other metal catalysts suitable for deoxygenation and hydrogenation reactions are typically used. The catalyst fixed bed ensures sufficient contact between the reactants and the catalyst, maximizing catalytic efficiency. Through interaction with the catalyst and reactants, microwaves not only raise the temperature of the reactants but also rapidly bring the catalyst surface to the required reaction temperature, thereby increasing the reaction rate and reducing the reaction time and energy consumption. The microwave-assisted fractionation tower is mainly used for the fractionation treatment of the hydrogenated intermediate products (such as syngas and bio-oil vapor). The microwave-assisted fractionation column incorporates a microwave heating module, which directly heats the materials within the column through microwave radiation. This module precisely controls the intensity and distribution of heating, ensuring that the temperature in each zone of the column can be accurately adjusted according to fractionation requirements. Microwave heating allows for flexible temperature control within the fractionation column, with different temperature ranges promoting the volatilization of different components, thus achieving effective fractionation. During hydrodeoxygenation, hydrogen (H2) reacts with oxides (such as phenols, alcohols, aldehydes, and acids) in bio-oil to produce water vapor (H2O). The removal of these oxides improves the stability of the bio-oil and significantly increases its calorific value. Microwaves rapidly bring the reactants to the required temperature on the catalyst surface, accelerating the reaction rate. The temperature is typically controlled between 250°C and 350°C. Below 250°C, the reaction rate is too slow, resulting in poor oxygen removal. Above 350°C, the catalyst may deactivate or undergo incomplete reactions, especially as the catalyst's high-temperature stability deteriorates, potentially leading to the cracking of hydrocarbons or other side reactions. Hydrogen pressure is typically maintained between 5-20 MPa. Lower pressures (e.g., 1-5 MPa) may lead to incomplete reactions, while excessively high pressures (above 20 MPa) not only increase system energy consumption but may also cause catalyst coking or degradation. Ensuring efficient hydrogenation is crucial. After the bio-oil enters the fractionation tower, the temperature gradually increases. Lower-boiling-point light components (such as solvents and hydrocarbons) evaporate first, rising to the top of the tower and being collected by a condenser. Higher-boiling-point heavy components are gradually separated within the tower, remaining at the bottom to obtain different product components. Microwave heating, through precise temperature and heating rate control, ensures accurate separation of components with different boiling points. The introduction of microwave heating reduces heat loss in traditional heating processes and increases the speed of the fractionation process.

[0054] Next, the energy recovery unit includes:

[0055] Waste heat exchanger, infrared auxiliary heating module, energy storage device.

[0056] Specifically, the energy recovery unit is a key component used to recover waste heat from the system and optimize overall energy efficiency through auxiliary heating and energy storage. This unit comprises three main modules: a waste heat exchanger, an infrared auxiliary heating module, and an energy storage device. The waste heat exchanger transfers heat from a high-temperature gas or fluid to a low-temperature fluid through a heat exchange process. Typically, the waste heat exchanger has heat exchange pipes with two different media; hot gas flows through the heat exchange pipes, transferring heat to the liquid or gas flowing on the other side. The heat in the waste heat recovery unit comes from the energy consumed in the waste heat recovered from the exhaust port of the microwave conversion unit and the heat recovered from the fractionation tower condenser. This waste heat is transferred through media such as heat transfer oil or steam, which receives and removes the waste heat in the waste heat exchanger. Heat exchange efficiency is closely related to factors such as fluid flow rate, heat exchange area, and temperature difference; therefore, the design of the waste heat exchanger ensures maximum heat recovery. The high-temperature waste gas and waste heat generated during microwave heating and conversion are effectively recovered, reducing dependence on external energy sources and lowering operating costs. The infrared heating module utilizes infrared radiation to convert electrical energy into heat energy. Infrared radiation can directly heat the surface of an object, rapidly increasing its temperature without relying on gas heat conduction, thus providing a faster heating speed. In this system, the infrared auxiliary heating module utilizes recovered waste heat (e.g., from the microwave conversion unit or fractionation tower condenser) for heating. Infrared radiation directly transfers heat to the area requiring heating, enhancing the effectiveness of the microwave heating process. Infrared heating is primarily used as an auxiliary heating method; when microwave heating or other heating methods cannot cover certain areas, infrared radiation can supplement the insufficient heat, improving thermal efficiency. Energy storage devices can use thermal energy storage materials (such as molten salts, phase change materials, etc.) to store excess thermal energy. Preferably, in this embodiment, the energy storage device uses an inorganic salt solution to store excess thermal energy from the recovered waste heat exchanger or infrared heating module. When the system requires additional heat, this stored energy is released to maintain a stable system temperature. When the system requires more heat, this stored thermal energy can be released to help maintain a stable temperature. If the system uses electrically driven equipment, excess electrical energy can be stored through a battery energy storage system or a superconducting energy storage system and released when energy demand increases. The energy recovery unit significantly improves the system's energy efficiency by combining a waste heat exchanger, an infrared auxiliary heating module, and an energy storage device. The energy cycle path of this scheme is as follows: First, the microwave heating system converts electrical energy into microwave energy through a microwave radiator. This microwave energy heats the biomass feedstock for drying, degreasing, and loosening its structure (microwave pretreatment unit), as well as pyrolysis, hydrolysis, and gasification (microwave conversion unit). Next, the microwave energy causes chemical reactions in the biomass, generating intermediate products (such as bio-oil vapor and syngas). These products then enter the microwave hydrogenation and fractionation unit for hydrogenation, deoxygenation, and fractionation, ultimately producing sustainable aviation fuel (SAF).Then, the waste heat from the microwave conversion unit and the microwave hydrogenation fractionation unit is recovered through a waste heat exchanger, and the recovered heat is used to preheat the raw materials or for auxiliary heating. Next, the infrared auxiliary heating module utilizes the recovered waste heat for heating, improving the heating effect and ensuring the uniformity and efficiency of the heating process. Finally, an energy storage device (such as a phase change material) stores excess heat and releases it when the system needs it, helping to maintain temperature stability and thus ensuring the continuous and stable operation of the entire system. Through this complete energy cycle path, the system can efficiently recover and utilize energy, reduce external energy consumption, and improve overall energy efficiency.

[0057] Next, the intelligent alarm unit includes:

[0058] The parameter acquisition module is used to acquire temperature, pressure, microwave power and material flow data of each unit in real time;

[0059] The fault early warning module is communicatively connected to the parameter acquisition module and is used to trigger an alarm; the alarm triggering condition is one of the following: the temperature sensor detects a temperature deviation > 5℃ and the pressure sensor detects a pressure fluctuation > 0.1MPa.

[0060] Specifically, the parameter acquisition module is responsible for acquiring real-time operating parameters of each unit in the entire system, including temperature, pressure, microwave power, and material flow rate data. This module collects data through sensors and measuring devices installed in various subsystems. Temperature sensors are installed in the microwave pretreatment unit, microwave hydrogenation reactor, microwave-assisted fractionation tower, and at the reactor's inlet and outlet. These sensors monitor temperature changes in critical areas to ensure temperature uniformity during the system's heating process. Pressure sensors are installed in pressure-sensitive areas of the microwave hydrogenation reactor and microwave-assisted fractionation tower to monitor pressure fluctuations within the reactor and ensure pressure is controlled within a safe range. The fault early warning module is responsible for real-time monitoring of various key parameters in the system (such as temperature, pressure, and power). When an abnormality is detected, an alarm mechanism is triggered. When a fault alarm is triggered, the system will not only issue audible and visual alarms or remote notifications but also automatically initiate adjustment measures to protect equipment and ensure stable system operation. This module connects to the parameter acquisition module, acquires data in real-time, analyzes the system status, promptly detects potential faults, and ensures timely handling of abnormal system conditions to prevent serious system failures. The fault early warning module is installed in the central control room or remote monitoring system. This module interacts with operators through a display screen or alarm device. Alarm information is sent to operators via audible and visual alarms, remote notifications, etc., reminding them to handle the fault. The fault early warning module communicates with devices such as temperature sensors and pressure sensors, enabling real-time monitoring of various important system parameters. Temperature sensors monitor the temperature of each unit in the system; when the temperature deviation exceeds 5°C, the fault early warning module will issue an alarm. Abnormal temperatures may lead to uneven material processing or equipment damage; the alarm mechanism ensures timely detection and action. Pressure sensors monitor pressure fluctuations in the system; if the pressure fluctuation exceeds 0.1 MPa, the system will trigger an alarm. Excessive pressure fluctuations can affect the stability of the reaction process and even lead to equipment damage; therefore, timely monitoring and alarms are crucial. Alarms are issued via audible and visual alarms, remote notifications, and automatic shutdown protection. Depending on the severity of the fault, the system will automatically implement protective measures, such as shutting down or closing the faulty area.

[0061] Finally, the system also includes a raw material crushing unit and a product storage unit;

[0062] The raw material crushing unit is used to crush biomass raw materials to supply the microwave pretreatment unit; the product storage unit is a low-temperature sealed storage tank used to store SAF products and prevent them from oxidizing and deteriorating.

[0063] Specifically, the raw material crushing unit is used for preliminary crushing of biomass raw materials to ensure the uniformity of the raw materials and suitability for the feeding requirements of the microwave pretreatment unit. This unit uses mechanical crushing equipment, such as hammer crushers, roller crushers, or blade crushers, to break the raw materials (such as sawdust, straw, and agricultural residues) into smaller particles, facilitating subsequent microwave heating treatment. By rationally setting the crusher's operating parameters (such as speed, pressure, and screen aperture), the particle size of the raw materials can be precisely controlled to meet the requirements of the microwave pretreatment unit for material morphology and particle size, ensuring that microwave energy can act uniformly and effectively on the material, improving the efficiency of drying and loosening processes. The product storage unit is used to store the SAF products generated in the microwave pretreatment unit and subsequent conversion processes. This unit adopts a low-temperature sealed storage tank design to ensure the stability and safety of the products during storage. The storage tank has an internal temperature control system that can regulate the temperature, maintaining the products in a low-temperature environment to prevent oxidation reactions and prevent the SAF products from deteriorating or losing quality during storage. At the same time, the sealed design effectively reduces contact with outside air, further reducing the impact of oxygen on SAF and maintaining its fuel performance and chemical stability.

[0064] Preferably, the system's workflow begins with the raw material crushing unit, where the biomass raw materials are initially crushed. This embodiment uses a heavy-duty blade crusher, which generates high-intensity shearing force through rotating blades at 480 rpm. A hydraulic system dynamically adjusts the gap (5-30 mm) between the impact plate and the rotor to precisely control the output particle size. The crushed material particles (5-10 mm in diameter) are conveyed to the microwave pretreatment unit via a closed conveyor belt (800 mm wide, 0.3 m / s speed, 304 stainless steel, with a 50 mm thick rock wool insulation layer). This conveyor belt has dustproof and heat dissipation protection functions, ensuring stable material temperature and preventing leakage during transport. In the microwave pretreatment unit, the material undergoes drying and structural loosening treatment to increase its specific surface area, facilitating subsequent pyrolysis, hydrolysis, and gasification. Next, the loosened material enters the microwave conversion unit. A high-temperature resistant shaftless screw conveyor is used in this embodiment to transport the biomass raw materials to the microwave conversion reaction chamber. This unit replaces the oxygen content in the chamber with an inert gas (such as N2) to below 0.1%, and uses four microwave feed ports (each with a power of 1200W) to uniformly heat the material, causing it to undergo pyrolysis, hydrolysis, and gasification reactions under microwave heating and high temperature conditions, generating gaseous products mainly composed of bio-oil vapor and syngas. After a 15-minute reaction, the generated gas is discharged through the top outlet and enters a subsequent condensation system for recovery, yielding liquid bio-oil intermediates. Subsequently, the generated bio-oil enters the microwave hydrorefining unit through a high-temperature resistant sealed pipeline. In this unit, the bio-oil is mixed with preheated hydrogen and then enters the microwave-assisted hydrorefining reactor. The microwave energy in this reactor heats the catalyst bed, reducing the oxygen content in the bio-oil to below 1.5%, completing the hydrodeoxygenation process. The deoxygenated product enters the microwave-assisted fractionation tower, where, with the aid of microwave heating and precise fractionation technology, sustainable aviation fuel (SAF) is generated. This product is transported to the product storage unit via cryogenic stainless steel pipelines. The product storage unit uses a 100m³ vertical cryogenic tank to store the final SAF. The storage tank features a three-walled structure: an inner liner of SUS304 stainless steel, a middle vacuum insulation layer, and an outer carbon steel protective shell. An integrated ethylene glycol cooling system maintains the temperature at -8°C. A nitrogen-sealing system ensures a slight positive pressure inside the tank, preventing oxygen ingress and ensuring the oxygen content remains below 100 ppm, effectively preventing the oxidation and deterioration of SAF. A high-precision level and pressure monitoring system monitors the tank's status in real time and connects to the SIS safety interlock system, ensuring automatic pressure relief in case of overpressure and guaranteeing safety during storage. The intelligent alarm unit serves as the control center of the entire system, connecting wirelessly to all sensors and actuators. A parameter acquisition module collects real-time data on temperature, pressure, power, and material flow from each unit and transmits this data to the central control system via a wireless network.The fault early warning module monitors key process parameters in real time, ensuring that the system can trigger alarms and take safety protection measures when anomalies occur. The intelligent alarm unit ensures the efficient, stable, and safe operation of the entire system, can adjust the working status of each unit in real time, and provides data support for continuous system optimization. In addition, the energy recovery unit is responsible for recovering waste heat from the system. Connected to the exhaust port of the microwave pretreatment unit, the tail gas port of the microwave conversion unit, and the fraction cooling port of the microwave hydrogenation fractionation unit via heat transfer oil pipelines, the recovered heat is used to preheat biomass feedstock, improving the system's energy efficiency. Simultaneously, the waste heat also provides necessary heating support for equipment such as the microwave generator and infrared auxiliary heating module in the system, further improving the system's energy utilization efficiency.

[0065] The embodiments described above are merely illustrative of specific implementations of the present invention, and while the descriptions are detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A system for microwave heating of biomass for SAF, characterized in that, It includes a microwave pretreatment unit, a microwave conversion unit, and a microwave hydrogenation fractionation unit connected in sequence, as well as an energy recovery unit and an intelligent alarm unit connected to the microwave pretreatment unit, microwave conversion unit, and microwave hydrogenation fractionation unit, respectively. The microwave pretreatment unit is used for drying, degreasing, and loosening the structure of biomass raw materials; The microwave conversion unit is used for the pyrolysis, hydrolysis, and gasification of pretreated biomass to generate intermediate products. The intermediate products are bio-oil vapor and syngas; The microwave hydrogenation fractionation unit is used for the hydrogenation, deoxygenation, and fractionation of intermediate products to generate SAF; The energy recovery unit is used to recover waste heat from each unit and provide auxiliary heating. The intelligent alarm unit is used to collect data from each unit and automatically trigger an alarm.

2. The system of claim 1, wherein, The microwave conversion unit includes: The device includes a spiral material conveying device, a modular multi-feed microwave cavity, a dielectric additive adding mechanism, and an inert gas introduction mechanism. The modular multi-feed microwave cavity is composed of multiple rectangular waveguide cavity modules connected in series via flanges. Each module has a microwave feed port on its top, and at least four microwave feed ports are evenly arranged along the material conveying direction. The microwave feed port includes a magnetron, a waveguide tuner, and a power detector.

3. The system of claim 1, wherein, The microwave pretreatment unit includes an integrated microwave drying and loosening device; the device includes an inner cavity and an outer cavity, the inner cavity uses 915MHz low-frequency microwaves for drying, and the outer cavity is equipped with a 2450MHz microwave radiator and a frequency conversion airflow disturbance mechanism.

4. The system of claim 1, wherein, The microwave hydrogenation fractionation unit includes: a microwave-assisted hydrogenation reactor and a microwave-assisted fractionation tower; the microwave-assisted hydrogenation reactor has a built-in high-frequency microwave generator and a catalyst fixed bed; the microwave-assisted fractionation tower has a built-in microwave heating module.

5. The system of claim 1, wherein, The energy recovery unit includes: Waste heat exchanger; infrared auxiliary heating module; energy storage device.

6. The system of claim 1, wherein, The intelligent alarm unit includes: The parameter acquisition module is used to acquire temperature, pressure, microwave power and material flow data of each unit in real time; The fault early warning module is communicatively connected to the parameter acquisition module and is used to trigger an alarm; the alarm triggering condition is one of the following: the temperature sensor detects a temperature deviation > 5℃ and the pressure sensor detects a pressure fluctuation > 0.1MPa.

7. The system according to any one of claims 1-6, characterized in that, The system also includes a raw material crushing unit and a product storage unit; the raw material crushing unit is used to crush biomass raw materials to supply the microwave pretreatment unit; the product storage unit is a low-temperature sealed storage tank used to store SAF products and prevent them from oxidizing and deteriorating.

8. The system according to claim 2, characterized in that, The spiral material conveying device has built-in temperature and pressure sensors, and the surface of the conveying spiral is coated with a dielectric-enhancing coating with a dielectric constant of 3.0-3.

5.

9. The system according to claim 2, characterized in that, The inert gas feeding mechanism is used for feeding inert gas into the multi-feeding oral cavity, the inert gas is one of N2 and Ar, and the gas flow is 0.5-1 m 3 / h.

10. The system according to claim 2, characterized in that, The dielectric additive mechanism is used to add dielectric additives; the dielectric additive is one of nano Fe3O4 and activated carbon; the amount of dielectric additive added is 1%-3% of the mass of the biomass raw material.

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