A system and method for producing a bio-oil

Abstract

This invention discloses a bio-oil preparation system and method, relating to the field of biomass conversion technology. The core design of the system involves feeding biomass into an inclined plate reactor, applying high-temperature hot sand above the biomass, and simultaneously heating the inclined plate with a heater. This combined operation significantly improves the rapid pyrolysis performance of biomass, effectively increasing the bio-oil yield. The combustion gases generated by the heater can be directly introduced into the reactor, allowing the reactor to create an oxidation-free environment without complex configuration, greatly simplifying the device structure. Furthermore, the system includes cyclone separation, staged condensation, waste gas post-treatment, and intelligent control components, achieving efficient, low-cost, and high-quality bio-oil preparation while reducing energy consumption and environmental pollution.

Description

Technical Field

[0001] This invention relates to the field of biomass conversion technology, and more specifically, to a bio-oil preparation system and method that achieves efficient conversion of biomass into bio-oil based on a rapid pyrolysis process. Background Technology

[0002] Fossil fuels not only cause severe environmental pollution during use, but their reserves are also difficult to estimate accurately. With the continuous growth of global energy demand, the supply and demand imbalance of fossil fuels is becoming increasingly prominent. Therefore, countries are actively developing renewable energy sources to replace fossil fuels. Renewable energy encompasses new energy sources such as hydrogen energy and fuel cells, as well as geothermal energy categories such as solar, wind, and biomass energy.

[0003] Among numerous renewable energy utilization technologies, the production of bio-oil from lignocellulosic biomass has been extensively studied in recent years due to its advantages such as wide availability of raw materials and good environmental performance. In particular, rapid pyrolysis technology has become a focus of attention in this field because it can achieve the highest yield of bio-oil.

[0004] However, rapid pyrolysis technology demands extremely high operational precision: due to the extremely short reaction time and narrow suitable temperature range, the entire process requires strict control of various key parameters. Specifically, to improve the yield of bio-oil, the reaction interface needs to achieve high heat transfer efficiency, which requires reducing the particle size of the materials and precisely controlling the reaction temperature (maintaining it at around 500℃) and the vapor temperature (maintaining it in the range of 400-450℃). At the same time, the time the product is in the vapor state needs to be controlled within about 2 seconds, and the vapor needs to be cooled rapidly to avoid excessive decomposition of the vapor products. In addition, the carbon residue will catalyze the decomposition of the vapor products, so the carbon residue must be separated and removed quickly.

[0005] Despite extensive research on rapid pyrolysis technology, no rapid pyrolysis technology that meets all the above conditions has yet been put into practical application. Developing a rapid pyrolysis system that can achieve high yield of bio-oil remains an urgent need in the industry. Summary of the Invention

[0006] To address the problems of existing rapid pyrolysis technologies, such as difficulty in achieving high bio-oil yields, complex equipment structures, high preparation costs, high energy consumption, and unstable bio-oil quality, this invention provides a bio-oil preparation system.

[0007] The specific technical solution is as follows: A bio-oil preparation system includes a reaction unit, a heating unit, a condensation unit, and an exhaust gas purification unit; The reaction unit includes a reactor with an inclined plate inside, which divides the reactor into a pyrolysis zone and a heating zone. The upper part of the pyrolysis zone is connected to a biomass feeder and a hot sand feeder. A heat conduction component is installed in the heating zone on the back of the inclined plate. The heating unit is a heater, which is connected to the hot gas inlet at the bottom of the reactor heating zone; The condensation unit includes a cyclone separator and a condenser connected in sequence; the cyclone separator is connected to the pyrolysis gas port at the top of the pyrolysis zone of the reactor; the cyclone separator removes impurities such as carbon slag from the gas by utilizing the cyclone effect.

[0008] The exhaust gas purification unit includes an exhaust gas treatment device and a gas analyzer; the exhaust gas treatment device is connected to the exhaust port at the top of the reactor heating zone. The exhaust gas treatment device can purify the exhaust gas, and the gas analyzer can monitor the composition of the exhaust gas to ensure environmentally friendly emissions.

[0009] A heat exchanger is also installed between the waste gas treatment device and the exhaust port at the top of the reactor heating zone, and is connected to the air inlet of the heater. The waste gas discharged from the reactor exhaust port carries waste heat into the heat exchanger, which can preheat the air entering the heater.

[0010] The bottom outlet of the reactor pyrolysis zone is connected to a conveying mechanism, which is then connected in sequence to a heater and a hot sand feeder.

[0011] According to the bio-oil preparation system of claim 1, the condenser comprises a medium-temperature condenser, an electrostatic collector, and a low-temperature condenser arranged in sequence, and is ultimately connected to a heater. The medium-temperature condenser performs room-temperature condensation and can extract high-molecular-weight bio-oil; the electrostatic collector can capture droplet-like bio-oil in uncondensed gas; the low-temperature condenser can extract low-molecular-weight bio-oil; and finally, the gas is transported to the heater for combustion.

[0012] The reactor heating zone is also equipped with multiple auxiliary heating ports, and the reactor pyrolysis zone is equipped with a temperature sensor. When the temperature sensor detects that the temperature is lower than the set value, hot air can be input into the auxiliary heating ports to increase the temperature.

[0013] A method for preparing bio-oil includes the following steps: S1. Biomass and hot sand supply: Biomass is transported to the inclined plate of the reactor through a biomass feeder; at the same time, high-temperature hot sand is supplied to the top of the biomass on the inclined plate through a hot sand feeder. S2. Pyrolysis of biomass and recycling of solid waste: The heating zone of the reactor is heated by a heater, and the inclined plate is heated evenly by heat conduction components. As the biomass and hot sand slide down, the biomass is rapidly pyrolyzed, producing gas containing bio-oil, which is discharged from the pyrolysis gas port at the top of the reactor pyrolysis zone. The resulting solid carbon residue and hot sand are discharged from the bottom outlet of the reactor and sent to the heater by a conveying mechanism. The solid carbon residue is burned for heating, and the hot sand is heated and then sent to the hot sand feeder. S3. Cyclone Separation: The cyclone separation unit receives pyrolysis gas and removes carbon residue impurities from it; S4. Three-stage condensation extraction of bio-oil and tail gas recycling: medium-temperature condensation extraction of high molecular weight bio-oil, electrostatic collector to capture droplet bio-oil, low-temperature condensation extraction of low molecular weight bio-oil; uncondensed gas is sent to a heater for combustion. S5. Exhaust gas treatment: The remaining gas after the uncondensed gas is burned by the heater is sent to the reactor heating zone with the heater's heating gas, and finally discharged from the exhaust port. After heat exchange by the heat exchanger, it enters the waste gas treatment device for treatment and is discharged in compliance with standards.

[0014] This invention employs a dual heating design of "inclined plate heating + high-temperature hot sand support," which ensures uniform heating of biomass, increases the pyrolysis reaction rate, and improves the yield of bio-oil. Furthermore, it achieves comprehensive resource utilization through waste gas preheating and utilization, hot sand recycling, and waste residue combustion. Attached Figure Description

[0015] Figure 1 This is a structural diagram of a bio-oil preparation system according to an embodiment of the present invention. Detailed Implementation

[0016] like Figure 1 As shown, a bio-oil preparation system includes a reaction unit, a heating unit, a condensation unit, and an exhaust gas purification unit. The reaction unit includes a reactor 1. Inside the reactor 1, there is an inclined plate 2 at an angle of 30°-70° to the horizontal plane, which divides the reactor 1 into a pyrolysis zone 1-1 and a heating zone 1-2. The upper part of the pyrolysis zone 1-1 of the reactor 1 is connected to a biomass feeder 3 and a hot sand feeder 4. The heating zone 1-2 on the back of the inclined plate 2 is equipped with a heat conduction component 5, which has an embedded serpentine hot air channel to achieve uniform heating. The heating unit is a combustion furnace heater 6, which is connected to the hot gas inlet 1-3 at the bottom of the reactor heating zone 1-2 for heating.

[0017] The condensation unit includes a cyclone separator 7 and a condenser 8 connected in sequence. The cyclone separator 7 is connected to the pyrolysis gas inlet 1-4 at the top of the pyrolysis zone 1-1 of the reactor. The cyclone separator 7 removes carbon residue particles from the pyrolysis gas, preventing blockage of the subsequent condenser. The cyclone separator 7 adopts a 2-3 stage series design. The first stage separator has a processing capacity of 1000-3000 m³ / h and a separation efficiency ≥95% (for particles ≥10μm). The second stage separator uses a high-efficiency guide vane structure with a separation efficiency ≥99% (for particles ≥5μm). The separator is made of high-temperature resistant carbon steel with a wear-resistant ceramic coating on the inner wall to extend its service life. It also has two insulation layers: an inner layer of 50mm thick aluminum silicate insulation cotton and an outer layer of 0.5mm thick stainless steel protective plate to prevent the bio-oil in the pyrolysis gas from condensing inside the separator, thus avoiding yield loss.

[0018] The condenser 8 comprises a medium-temperature condenser 8-1, an electrostatic collector 8-2, and a low-temperature condenser 8-3 arranged in sequence, and is ultimately connected to the heater 6. The medium-temperature condenser 8-1 is a room-temperature condenser, employing a shell-and-tube heat exchanger. Room-temperature cooling water flows through the shell side, while pyrolysis gas (350-400℃) separated by cyclone separation flows through the tube side. High-molecular-weight bio-oils in the pyrolysis gas, such as tar-like components with a boiling point >250℃, condense on the inner wall of the tube side, forming liquid bio-oil, which is collected through a bottom oil collection tank. The condensation efficiency is ≥80%. The electrostatic collector 8-2 adopts a plate-type electrostatic precipitator structure with an electrode spacing of 100-150mm, and is subjected to high-voltage direct current (30-50kV). After medium-temperature condensation, the gas still contains tiny droplet-like bio-oil (particle size 1-10μm). Under the action of a high-voltage electric field, the droplets are polarized and adsorbed onto the surface of the electrode plate, and are scraped off by a scraper into the oil collection tank, with a recovery rate ≥90%. The low-temperature condenser 8-3 adopts a shell-and-tube heat exchanger. The shell side is circulated with a low-temperature coolant, such as an aqueous solution of ethylene glycol, at a temperature of -10 to -20℃. The tube side is circulated with gas (100-150℃) that has been electrically collected. The low molecular weight bio-oil (boiling point 50-250℃) in the gas condenses in the tube side and is collected through the bottom oil collection tank, with a condensation efficiency ≥75%.

[0019] The exhaust gas purification unit includes an exhaust gas treatment device 9 and a gas analyzer 10. The exhaust gas treatment device 9 is connected to the exhaust port 1-5 at the top of the heating zone 1-2 of the reactor 1. The exhaust gas treatment device 9 purifies the exhaust gas, and the gas analyzer 10 monitors the exhaust gas composition to ensure environmentally friendly emissions. The exhaust gas treatment device 9 is used to purify the combustion exhaust gas and uncondensed gas emitted by the system to ensure compliance with emission standards. It includes a particulate matter filtration module, an organic pollutant degradation module, and a harmful gas adsorption module: The particulate matter filtration module uses a bag filter with polytetrafluoroethylene (PTFE) filter bags, achieving a filtration accuracy of ≥99.9% (for particles ≥0.1μm in diameter) and a processing air volume of 500-1500 m³ / h. The organic pollutant degradation module uses a catalytic combustion reactor with a platinum-palladium honeycomb ceramic catalyst (active ingredient content 0.1%-0.3%), a reaction temperature of 300-400℃, and can degrade volatile organic compounds (VOCs) and tar residues in the exhaust gas into CO2 and H2O with a degradation efficiency of ≥95%. Hazardous gas adsorption module: Employs a double-layer adsorption tower. The first layer is filled with activated carbon (iodine value ≥1000mg / g) to adsorb residual organic pollutants; the second layer is filled with calcium hydroxide particles (particle size 3-5mm) to adsorb acidic gases such as SOx and NOx in the waste gas, with an adsorption efficiency ≥90%. Gas analyzer: Utilizes an online gas chromatography-mass spectrometry (GC-MS) system. The monitoring point is located at the outlet of the waste gas treatment unit, enabling real-time analysis of the O2, CO, VOCs, and SOx content in the waste gas.

[0020] A heat exchanger 11 is also installed between the waste gas treatment device 9 and the exhaust ports 1-5 at the top of the reactor heating zone, and is connected to the air inlet of the heater. The waste gas discharged from the reactor exhaust ports 1-5 carries waste heat into the heat exchanger 11, which can preheat the air entering the heater 6.

[0021] The bottom outlet 1-3 of the pyrolysis zone 1-2 of the reactor is connected to the conveying mechanism 12, and is sequentially connected to the heater 6 and the hot sand feeder 4. The hot sand and char slag discharged from the bottom outlet 1-3 of the pyrolysis zone are fed into the heater 6 by a screw conveyor or belt conveyor. The char slag is directly used for combustion, and the hot sand is then fed into the hot sand feeder 4.

[0022] The reactor heating zone 1-2 is also provided with multiple auxiliary heating ports 1-6. The reactor pyrolysis zone is provided with a temperature sensor 13. When the temperature sensor 13 detects that the temperature is lower than the set value, the auxiliary heating ports 16 can input hot gas through the auxiliary burner to increase the temperature.

[0023] A method for preparing bio-oil includes the following steps: S1. Biomass and hot sand supply: Biomass is transported to the inclined plate 2 of reactor 1 through biomass feeder 4; at the same time, high-temperature hot sand is transported above the biomass on the inclined plate 2 through hot sand feeder 3. S2. Pyrolysis of biomass and recycling of solid waste: Heater 6 supplies heat to the heating zone 1-2 of the reactor, and heat conduction component 5 ensures that the inclined plate 2 is heated evenly. As biomass and hot sand slide down, biomass is rapidly pyrolyzed, producing gas containing bio-oil, which is discharged from the pyrolysis gas port 1-4 at the top of the pyrolysis zone 1-1 of the reactor. The resulting solid carbon residue and hot sand are discharged from the bottom outlet of the reactor 1 and sent to heater 6 by conveying mechanism 12. The solid carbon residue is burned for heating, and the hot sand is heated and then sent to hot sand feeder 4. S3. Cyclone Separation: Cyclone separation unit 7 receives pyrolysis gas and removes carbon residue impurities from it; S4. Three-stage condensation extraction of bio-oil and tail gas recycling: medium-temperature condensation extraction of high molecular weight bio-oil, electrostatic collector to capture droplet bio-oil, low-temperature condensation extraction of low molecular weight bio-oil; uncondensed gas is sent to a heater for combustion. S5. Exhaust gas treatment: The uncondensed gas is burned by the heater 6 and the remaining gas is sent to the reactor heating zone 1-2 with the heater. Finally, it is discharged from the exhaust port 1-5. After heat exchange by the heat exchanger 11, it enters the waste gas treatment device 9 for treatment and is discharged in compliance with standards.

[0024] Specific embodiment: Preparation of bio-oil from sawdust.

[0025] The bio-oil preparation system of this invention uses sawdust (particle size 1-3 mm) with a moisture content of 20% as biomass raw material to prepare bio-oil.

[0026] The reactor has a 55° inclined plate angle, with the pyrolysis temperature controlled between 480-520℃. The biomass feed rate is 100 kg / h, the hot sand supply rate is 200 kg / h, and the hot sand temperature is maintained at 550-580℃. The multi-stage cyclone separator has a processing capacity of 2000 m³ / h, with its internal temperature maintained at 380℃, achieving a carbon-slag separation efficiency of 98%. The medium-temperature condenser has a cooling water temperature of 25℃ and a high molecular weight bio-oil recovery rate of 82%. The electrostatic precipitator has a voltage of 40 kV and a droplet bio-oil recovery rate of 91%. The low-temperature condenser has a cooling liquid temperature of -15℃ and a low molecular weight bio-oil recovery rate of 78%. The heat exchanger utilizes waste heat from the exhaust gas for preheating and combustion aid, reducing fuel consumption by 15%. The hot sand recycling rate is 92%, and the carbon slag is used as auxiliary fuel, further reducing fuel consumption by 8%. Ultimately, the bio-oil yield was 81% (based on the oven-dry weight of wood chips), of which low molecular weight bio-oil accounted for 45%; the system energy consumption (converted to natural gas) was 5.2 m³ / t wood chips, a 35% reduction compared to traditional systems; and the exhaust emission indicators were: VOCs 18 mg / m³, particulate matter 4 mg / m³, and SOx 8 mg / m³, all meeting the standards.

Claims

1. A bio-oil preparation system, characterized in that, It includes a reaction unit, a heating unit, a condensation unit, and an exhaust gas purification unit; The reaction unit includes a reactor with an inclined plate inside, which divides the reactor into a pyrolysis zone and a heating zone. The upper part of the pyrolysis zone is connected to a biomass feeder and a hot sand feeder. A heat conduction component is installed in the heating zone on the back of the inclined plate. The heating unit is a heater, which is connected to the hot gas inlet at the bottom of the reactor heating zone; The condensation unit includes a cyclone separator and a condenser connected in sequence; The cyclone separator is connected to the pyrolysis gas inlet at the top of the reactor's pyrolysis zone; The exhaust gas purification unit includes an exhaust gas treatment device and a gas analyzer; the exhaust gas treatment device is connected to the exhaust port at the top of the reactor heating zone.

2. The bio-oil preparation system according to claim 1, characterized in that, A heat exchanger is also installed between the waste gas treatment device and the exhaust port at the top of the reactor heating zone, and is connected to the air inlet of the heater.

3. The bio-oil preparation system according to claim 1, characterized in that, The bottom outlet of the reactor pyrolysis zone is connected to a conveying mechanism, which is then connected in sequence to a heater and a hot sand feeder.

4. The bio-oil preparation system according to claim 1, characterized in that, The condenser comprises a medium-temperature condenser, an electrostatic collector, and a low-temperature condenser arranged in sequence, and is ultimately connected to a heater.

5. The bio-oil preparation system according to claim 1, characterized in that, The reactor heating zone is also equipped with multiple auxiliary heating ports.

6. The bio-oil preparation system according to claim 1, characterized in that, Temperature sensors are also installed in the pyrolysis zone of the reactor.

7. A method for preparing bio-oil, characterized in that, Includes the following steps: S1. Biomass and hot sand supply: Biomass is transported to the inclined plate of the reactor through a biomass feeder; at the same time, high-temperature hot sand is supplied to the top of the biomass on the inclined plate through a hot sand feeder. S2. Pyrolysis of biomass and recycling of solid waste: The heating zone of the reactor is heated by a heater, and the inclined plate is heated evenly by heat conduction components. As the biomass and hot sand slide down, the biomass is rapidly pyrolyzed, producing gas containing bio-oil, which is discharged from the pyrolysis gas port at the top of the reactor pyrolysis zone. The resulting solid carbon residue and hot sand are discharged from the bottom outlet of the reactor and sent to the heater by a conveying mechanism. The solid carbon residue is burned for heating, and the hot sand is heated and then sent to the hot sand feeder. S3. Cyclone Separation: The cyclone separation unit receives pyrolysis gas and removes carbon residue impurities from it; S4. Three-stage condensation extraction of bio-oil and tail gas recycling: medium-temperature condensation extraction of high molecular weight bio-oil, electrostatic collector to capture droplet bio-oil, low-temperature condensation extraction of low molecular weight bio-oil; uncondensed gas is sent to a heater for combustion. S5. Exhaust gas treatment: The remaining gas after the uncondensed gas is burned by the heater is sent to the reactor heating zone with the heater's heating gas, and finally discharged from the exhaust port. After heat exchange by the heat exchanger, it enters the waste gas treatment device for treatment and is discharged in compliance with standards.

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