Biomass gasification direct-combustion coupled green hydrogen methanol preparation system and method

Abstract

The invention relates to a system and a method for preparing methanol by coupling biomass gasification direct combustion with green hydrogen, in particular to the crossing field of renewable energy sources and chemical engineering technologies. The system comprises a biomass gasification unit, a direct-combustion power generation unit, a green hydrogen preparation unit and a methanol synthesis unit, wherein a fluidized bed gasification furnace of the biomass gasification unit is connected with a combustion chamber of the direct-combustion power generation unit and a mixer of the methanol synthesis unit in a shunting manner through a high-temperature synthesis gas pipeline; a hydrogen outlet of the green hydrogen preparation unit is connected with the mixer. The method comprises the following steps: carrying out oxygen-enriched gasification on biomass at 750-900 DEG C to generate synthesis gas; 40-60% of synthesis gas is directly combusted to generate power for the system; mixing the residual synthesis gas with electrolyzed water green hydrogen; and pressurizing the mixed gas, and catalytically synthesizing methanol at 220-280 DEG C. All components of the biomass are efficiently utilized, the energy efficiency exceeds 60%, the methanol yield reaches 0.5 ton per ton of biomass, the carbon emission is reduced to 0.1 ton per ton of methanol or below, and the method is obviously superior to a traditional process.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of renewable energy and chemical technology, and particularly relates to a biomass gasification direct combustion coupled green hydrogen methanol production system and method. More particularly, it relates to a biomass energy and green hydrogen collaborative conversion technology, which is particularly suitable for the resource utilization of agricultural and forestry waste and the production of carbon neutral dyes. BACKGROUND

[0002] As a renewable carbon source, the efficient conversion of biomass energy to produce liquid fuels has strategic significance for achieving carbon neutralization. Methanol, as an important chemical raw material and clean fuel carrier, can significantly reduce the carbon emissions of the whole life cycle through the biomass route. Current biomass methanol production technology mainly relies on gasification synthesis process, i.e., after biomass is converted into synthesis gas, methanol is synthesized by catalytic synthesis after conditioning treatment. However, this technical route still faces systematic challenges in the industrialization process.

[0003] Energy efficiency bottleneck is the primary constraint factor. The biomass gasification process needs to be carried out at high temperature, and the traditional process uses air gasification, which leads to low calorific value of synthesis gas due to the dilution effect of nitrogen, usually only 4 to 6 megajoules per standard cubic meter. In order to maintain the reaction temperature, the system needs to burn part of the biomass or supplement fossil fuels, resulting in a decrease in raw material utilization. Some advanced processes use pure oxygen gasification to improve the quality of synthesis gas, but the energy consumption of the oxygen production equipment can account for 15% to 20% of the total energy consumption of the system, and the problem of sensible heat recovery of the gasifier has not been effectively solved. When the existing waste heat boiler recovers the heat of high-temperature synthesis gas, the sensible heat loss caused by the temperature gradient of the pipeline can be more than 20%, and the final system energy conversion efficiency is generally less than 45%.

[0004] Elemental proportion imbalance constitutes the core chemical obstacle. The hydrogen-oxygen element ratio in biomass raw materials is significantly lower than that of fossil fuels, and the hydrogen-carbon molar ratio of synthesis gas produced by gasification is usually only 0.4 to 1.0. The methanol synthesis reaction requires a higher hydrogen-carbon molar ratio, and the ideal value needs to be maintained at 2.0 to 2.2. Existing technologies mainly adjust the ratio through the water-gas shift reaction, but for every 1 mole of hydrogen produced, 1 mole of carbon dioxide is generated. The volume fraction of carbon dioxide in the synthesis gas of typical lignocellulosic raw materials can reach 15% to 25%, far exceeding the tolerance threshold of methanol synthesis catalysts. Excess carbon dioxide not only dilutes the concentration of reaction gas, but also causes catalyst carbon deposition and deactivation. Although physical adsorption or membrane separation technology can be used to remove carbon dioxide, the energy consumption of carbon capture will increase the cost of methanol production by more than 30%.

[0005] The disruption of the carbon cycle causes an environmental burden. In traditional processes, about 40% to 50% of the carbon contained in biomass is emitted in the form of carbon dioxide. The carbon dioxide produced in the gasification process contains impurities such as sulfides, which makes capture economical; the unconverted tail gas from the synthesis reaction is usually directly burned and emitted, resulting in a carbon utilization rate of less than 60%. If the entire life cycle is taken into account, the net carbon emissions per ton of biomass methanol are still 0.8 to 1.2 tons, which is far from achieving true carbon neutrality. Although some studies have attempted to return carbon dioxide to the gasifier, the reduction reaction rate of carbon dioxide and coke is slow under high temperature conditions, the carbon conversion rate is less than 35%, and the processing capacity of the gasifier is significantly reduced.

[0006] Barriers to green hydrogen utilization create a synergy dilemma. Using renewable energy to electrolyze water to produce green hydrogen and feed it into synthesis gas could theoretically address the hydrogen-to-carbon ratio imbalance. However, in engineering practice, a dual contradiction exists: on the one hand, water electrolysis consumes extremely high energy, requiring 4 to 5 kilowatt-hours of electricity per standard cubic meter of hydrogen. Relying entirely on external green electricity would render methanol costs uncompetitive in the market. On the other hand, the biomass gasification system's inherent power generation efficiency is limited, with conventional steam cycles generating only 25% to 30% efficiency, unable to simultaneously meet the energy demands of hydrogen production and system operation. Existing technologies have yet to establish a self-consistent energy coupling mechanism for biomass energy and green hydrogen.

[0007] System integration defects lead to insufficient economic efficiency. Currently, most biomass-to-methanol plants adopt a modular design: the gasification unit, power generation unit, and synthesis unit operate independently of each other. This fragmented architecture causes triple losses: the sensible heat of the high-temperature synthesis gas from gasification is lost during transportation; the low-temperature waste heat from the power generation unit is not effectively utilized; and the heat released by the synthesis reaction is only used to generate low-pressure steam. More importantly, it is difficult to dynamically match the operating parameters of each subsystem. For example, when the gasification load fluctuates, the synthesis unit needs to frequently adjust the catalyst space velocity, resulting in unstable product quality. According to data from industrial projects, the annual operating rate of such systems is usually less than 75%, and insufficient equipment utilization further increases the cost of methanol production.

[0008] In summary, biomass-to-methanol technology urgently needs to break through key technical bottlenecks such as energy conversion efficiency, element balance regulation, carbon cycle closure, green hydrogen synergistic utilization and system integration optimization, so as to achieve the dual goals of environmental and economic benefits. Summary of the Invention

[0009] To address the shortcomings of existing technologies, the present invention aims to provide a biomass gasification and direct combustion coupled green hydrogen to methanol production system and method. This system improves energy efficiency and reduces carbon emissions through cascaded energy utilization, dynamic optimization of the hydrogen-to-carbon ratio, and low-energy separation technology.

[0010] In order to achieve the above object, the present invention provides the following technical solutions: A biomass gasification direct combustion coupled green hydrogen to methanol system, comprising: The biomass gasification unit comprises a fluidized bed gasifier, a feeding device connected with a feeding port of the fluidized bed gasifier, and a gasifying agent inlet arranged at the bottom of the fluidized bed gasifier; The direct combustion power generation unit comprises a combustion chamber, a gas turbine connected with an outlet of the combustion chamber, and a generator coaxially connected with the gas turbine; The green hydrogen preparation unit comprises an electrolytic cell, a purification device connected with a hydrogen outlet of the electrolytic cell, and a renewable energy power supply module connected with a power input end of the electrolytic cell; The methanol synthesis unit comprises a mixer, a booster connected with an outlet of the mixer, a catalytic reactor connected with an outlet of the booster, and a separation tower connected with a product outlet of the catalytic reactor; The high-temperature synthesis gas pipeline has an inlet end connected with a gas outlet of the fluidized bed gasifier and an outlet end divided into two branches: The first branch is connected with an inlet of the combustion chamber of the direct combustion power generation unit; The second branch is connected with a first inlet of the mixer of the methanol synthesis unit; The hydrogen outlet of the purification device is connected with a second inlet of the mixer.

[0011] Through energy coupling of the biomass gasification unit, the direct combustion power generation unit, the green hydrogen preparation unit and the methanol synthesis unit, the cascade utilization of synthesis gas is realized. The oxygen-rich air gasification reduces the cost of oxygen, and the intelligent control unit dynamically adjusts the hydrogen-carbon ratio, thereby improving the efficiency of methanol synthesis. The total energy efficiency of the system is more than 65%, which is 20% higher than that of the traditional process; the oxygen-rich air replaces pure oxygen, and the cost of oxygen preparation is reduced by 40%; H2 / (2CO+3CO2)=1.05-1.25, and the selectivity of methanol is increased to 92%.

[0012] Further, the operating temperature of the fluidized bed gasifier is 750-900℃, and the gasifying agent is oxygen-rich air with a volume concentration of 50-80%; the high-temperature synthesis gas pipeline is lined with a ceramic insulation layer, and the outer wall is coated with Inconel625 alloy. The high-temperature synthesis gas pipeline is lined with Inconel625 alloy and ceramic insulation layer, which can resist H2S corrosion and reduce heat loss. Corrosion resistance: can resist synthesis gas with H2S concentration ≤500ppm, service life extended to 10 years; the ceramic insulation layer reduces heat loss to less than 5%, which improves the thermal efficiency by 15% compared with carbon steel pipeline.

[0013] Further, the direct combustion power generation unit further comprises a waste heat boiler, an air inlet of which is connected with an exhaust port of the gas turbine; and a steam outlet of the waste heat boiler is connected to a gasifying agent preheater of the biomass gasification unit. The waste heat boiler recovers the heat of the exhaust gas of the gas turbine, preheats the gasifying agent to 300-400℃, and improves the efficiency of biomass gasification. The energy consumption of gasifying agent preheating is reduced by 20%, and the net power generation of the system is increased by 8%; the gasification reaction rate is increased by 15% after preheating, and the synthesis gas yield is increased by 12%.

[0014] Further, the renewable energy power supply module includes a wind turbine and a photovoltaic panel array; the power output end of the generator is connected to the electrolytic cell and the system power equipment through the power distribution cabinet respectively. The renewable energy power supply module cooperates with the energy storage system to ensure the stability of the green hydrogen production. 5MW wind power + 3MW photovoltaic + 2MWh energy storage can meet the demand of electrolytic cell load fluctuation, and the power interruption time is less than 1 second; the proportion of green hydrogen reaches 60%, and the carbon emission per unit of methanol is reduced to 0.8kgCO2 / kg.

[0015] Further, the catalytic reactor is filled with Cu-ZnO-Al2O3 catalyst, wherein the content of CuO is 40-60wt%, the content of ZnO is 25-40wt%, and the content of Al2O3 is 10-20wt%; the catalytic reactor is provided with a circulating water cooling jacket. The catalytic reactor adopts a tube type structure and a circulating water cooling jacket to optimize the reaction temperature control. The reaction temperature fluctuation is ±2℃, and the utilization rate of active sites of the catalyst is increased by 30%; the service life is 5000 hours, which is 20% longer than that of the traditional fixed bed.

[0016] Further, it further comprises an integrated control unit, which comprises: a shunt regulating valve arranged in the high-temperature synthesis gas pipeline; an H2 / CO molar ratio sensor arranged at the inlet of the mixer; a PLC controller connected with the shunt regulating valve and the H2 / CO molar ratio sensor signal. The unreacted gas at the top of the separation tower is recycled, and the inert gas content is controlled by the membrane separation. The CO single-pass conversion rate is increased from 22% to 35% by recycling the unreacted gas; the inert gas content is less than or equal to 10vol%, and the compression energy consumption of the circulating gas is reduced by 12% A biomass methanol production method based on a biomass gasification direct combustion coupled green hydrogen methanol production system, comprising the steps of: S1, biomass particles with a particle size of ≤20mm are input into a fluidized bed gasification furnace through a feeding device, and a gasification agent with a volume concentration of 50-80% is introduced to generate synthesis gas containing H2, CO and CO2 at 750-900℃; S2, the synthesis gas is transported and shunted through a high-temperature synthesis gas pipeline: 40-60% of the volume of the synthesis gas enters the combustion chamber for direct combustion power generation; the remaining synthesis gas enters the mixer; S3, the electrolytic cell uses renewable energy power supply module and / or generator power to electrolyze water, and the generated hydrogen gas is input into the mixer after purification.

[0017] Biomass is gasified under oxygen-rich air conditions to generate high-hydrogen synthesis gas, which is directly burned for power generation and coupled with methanol synthesis. H2CO / CO2=2.5-3.5:1:0.5, suitable for methanol synthesis (compared to traditional gasification H2 / CO=1.2); 40-60% of the synthesis gas is directly burned for power generation, which adapts to the fluctuation of power demand.

[0018] Further, in step S3, the ratio of the molar flow of hydrogen input into the mixer to 2 times the molar flow of carbon monoxide in the synthesis gas plus 3 times the molar flow of carbon dioxide is 1.05 to 1.25. The green hydrogen preparation unit is fully loaded when there is a surplus of electricity, and is supplemented by direct combustion power generation when there is a shortage. The energy storage system fills the valley and stabilizes the electrolytic cell load rate at more than 90%; the cost of purchasing electricity from the power grid is reduced by 0.15 yuan / kWh.

[0019] Further, the mixed gas output from the mixer is pressurized to 5.0-10.0MPa by a booster and then enters the catalytic reactor for reaction at 220-280℃; the CO2 volume fraction in the gas at the outlet of the catalytic reactor is controlled at 8-15%. The separation tower uses differential pressure rectification, and the circulating gas at the top is removed after removing the inert gas and returned to the synthesis loop. The purity of the methanol at the bottom is ≥99.5wt%, meeting the premium product standard of GB / T338-2011; the removal of inert gas increases the effective components of the circulating gas by 25%.

[0020] Further, the gas at the outlet of the catalytic reactor is rectified by the separation tower, and 30-50% of the unreacted gas by volume is returned to the mixer for recycling; the purity of the methanol product obtained at the bottom is ≥99.5wt%. Through energy coupling and carbon emission reduction technology, the carbon emission per unit of methanol is reduced. The carbon emission per unit of methanol is ≤0.8kgCO2 / kg, which is reduced by 47% compared to the traditional process; 10,000 tons of biomass processed per year can reduce CO2 emissions by 5,000 tons.

[0021] Advantages of the present application The present application realizes a breakthrough in energy conversion efficiency, element utilization rate, carbon emission reduction, system stability and economy through deep coupling of biomass gasification direct combustion and green hydrogen preparation. Its core advantages are reflected in six mutually reinforcing technical effects: 1. The efficiency of energy cascade utilization has been significantly improved due to the direct energy conversion path of high-temperature synthesis gas. The high-temperature synthesis gas (above 800℃) produced by biomass gasification under oxygen-rich conditions is directly transported to the combustion chamber through special alloy pipes to drive the gas turbine to generate electricity, completely avoiding the sensible heat recovery loss of the traditional waste heat boiler. This process improves the conversion efficiency of high-temperature heat to electricity to more than 35%, and the generated electricity directly powers the electrolytic cell to produce green hydrogen, while covering the energy consumption of auxiliary equipment. Experiments have shown that the power generation per ton of biomass can reach 800-1000 kilowatt-hours, meeting 70%-85% of the energy required for hydrogen production. More importantly, the flue gas from the gas turbine is used to generate medium-pressure steam through a waste heat boiler, which is used for preheating the gasification agent, making the overall energy efficiency of the system exceed 60%, which is 15-20 percentage points higher than the traditional biomass methanol production process.

[0022] 2. Global optimization of carbon and hydrogen elements relies on the precise matching mechanism of green hydrogen and synthesis gas. Zero-carbon hydrogen produced by electrolysis of water is supplemented into the split synthesis gas at a certain ratio, dynamically adjusting the effective hydrogen-carbon molar ratio of the mixed gas to the ideal interval of 2.0-2.2. This ratio not only meets the optimal activity window of the methanol synthesis catalyst, but also consumes excess carbon dioxide through chemical reactions. Specifically, the supplemented hydrogen reacts with excess carbon dioxide in the synthesis gas to produce methanol, converting carbon dioxide from a harmful diluent to an effective carbon source. Industrial pilot data show that 15%-25% of the carbon dioxide in the split synthesis gas is effectively utilized, and the final tail gas carbon dioxide concentration is reduced to less than 8%, with the carbon element utilization rate increasing from less than 60% in the traditional process to more than 90%.

[0023] 3. The magnitude of carbon reduction in the whole life cycle is achieved based on the dual foundation of carbon closed loop and green hydrogen zero carbon properties. Part of the carbon dioxide produced in the gasification process is recirculated to the gasifier after capture, and it reacts with biomass coke to generate carbon monoxide in a high-temperature environment, achieving in-situ carbon chain recycling. At the same time, green hydrogen production relies entirely on system-generated electricity and renewable energy, eliminating the mixing of fossil fuels. This synergistic mechanism reduces the carbon emissions of each ton of methanol product in the whole life cycle to less than 0.1 tons, which is more than 90% lower than the traditional process. More importantly, the flue gas emitted by the direct-fired power generation unit can reach food-grade standards after amine capture, and part of it can be used in the food industry to generate additional income.

[0024] 4. The system stability is fundamentally improved by the self-balancing design of energy-matter flow. The direct-fired power generation unit as the energy hub of the system ensures that the power supply fluctuation of the electrolytic cell does not exceed ±5% by adjusting the proportion of syngas split in real time. When the quality fluctuation of the biomass raw material leads to changes in the composition of the syngas, the integrated control unit dynamically adjusts the green hydrogen supplement based on the online hydrogen sensor data, so that the hydrogen-carbon ratio of the mixed gas is always stable within the range of 2.1±0.1. The catalytic reactor uses circulating cooling water jacket to accurately control the temperature, and the bed temperature gradient is controlled within 3℃. These measures extend the continuous operation cycle of the system to more than 6000 hours, and increase the catalyst life by 30%-40%.

[0025] 5. The raw material adaptability is greatly widened based on the synergistic buffering effect of gasification-combustion-synthesis. The traditional process usually has a water content tolerance of less than 20%, while the high-grade heat energy generated by high-temperature syngas direct-fired can efficiently dry agricultural and forestry waste with a water content of up to 35%. The gasification unit uses an oxygen-enriched fluidized bed design to successfully process high-ash materials such as rice husk and palm shell with ash content exceeding 15%. More significantly, the syngas split mechanism can flexibly adapt to the gasification characteristics of different raw materials: increasing the direct-fired proportion for low-calorific-value raw materials to maintain system energy balance, and reducing the green hydrogen supplement for high-hydrogen-content raw materials. This makes it possible for diversified biomass such as straw, sawdust, and sugarcane residue to achieve stable output of methanol yield of 0.48-0.55 tons per ton of dry basis.

[0026] 6. The economic competitiveness is revolutionarily broken through from the multi-dimensional cost synergistic reduction. The system energy self-sufficiency rate is more than 85%, eliminating the cost of external power purchase; the carbon dioxide capture amount is reduced by more than 70%, and the carbon management cost is reduced by 60%; the catalyst life is extended, reducing the catalyst consumption per unit product by 40%; more importantly, through the precise supplement of green hydrogen, the raw biomass consumption per ton of methanol is reduced from 2.2-2.5 tons in the traditional process to 1.8-2.0 tons. Comprehensive calculation shows that under the same scale device, the cost of methanol production can be controlled in the range of 250-300 US dollars per ton, which has market competitiveness with traditional fossil route methanol.

[0027] The six effects form a tight technical closed loop: energy efficiency improvement ensures green hydrogen economic preparation, green hydrogen supplement optimizes carbon-hydrogen balance, carbon cycle closure reduces environmental cost, stable operation prolongs equipment life, raw material adaptation broadens resource base, and ultimately drives economic breakthrough together. The synergistic gain far exceeds the simple superposition of each unit technology improvement, for example, the carbon emission reduction effect not only comes from the zero-carbon attribute of green hydrogen, but also depends on the efficient energy conversion of direct-fired power generation and the carbon chain closure of carbon dioxide backfeeding; the economic breakthrough is benefited from the threefold effect of raw material consumption reduction, catalyst life extension, and carbon tax cost savings. This system-level innovation provides unprecedented technical and economic for the industrialization of biomass methanol. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 This is a process flow chart of a biomass gasification direct combustion coupled green hydrogen to methanol system.

[0029] In the figure, 101 is a fluidized bed gasifier, 102 is a feeding device, 103 is a gasifying agent inlet, 104 is a high-temperature synthesis gas pipeline, and 105 is a gasifying agent preheater; 201: Combustion chamber, 202: Gas turbine, 203: Generator, 204: Waste heat boiler, 205: Power distribution cabinet; 301, electrolyzer, 302, purification device, 303, renewable energy power supply module, 303a, wind turbine, 303b, photovoltaic panel array; 401. mixer, 402. booster, 403. catalytic reactor, 404. separation tower, 405. circulating water cooling jacket; 501. Diverter control valve, 502. H2 / CO molar ratio sensor, 503. PLC controller.

[0030] Figure 2 It is a cross-sectional view of the structure of the high-temperature synthesis gas pipeline 104.

[0031] Figure 3 This is a diagram of the internal structure of the catalytic reactor 403.

[0032] Figure 4 This is the logic block diagram of the control system. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention; it is obvious that the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0034] Example 1 use Figure 1 The system shown processes rice husk (particle size ≤ 12 mm, moisture content 10 wt%, ash content 12 wt%): 1. Raw material pretreatment Rice husk was crushed by a jaw crusher (model PE-250x400, crushing ratio 1:5) to a particle size of ≤12 mm and classified by a three-layer vibrating screen (model ZS-1224, screen hole sizes of 12 mm, 8 mm, and 5 mm, respectively). The moisture content was determined by oven drying method (GB / T212-2008): 10 g of sample was dried in an oven at 105±2°C for 2 hours, and the moisture content was calculated by weight loss method to be 10wt%. The target moisture content was adjusted to 10wt% by a roller dryer (model YG-10, thermal efficiency ≥85%), and the drying energy consumption was 0.08 kWh / kg. The ash content was determined by muffle furnace calcination method (GB / T212-2008): 5 g of sample was calcined at 815±10°C for 2 hours, and the residual ash content was 12wt%.

[0035] 2. Oxygen-enriched gasification Gasifier preparation: air was enriched to 65vol% by a cryogenic air separation device (model KDON-1000, oxygen extraction rate 95%), and was preheated to 400±5°C by inter-wall heat exchange with 0.8MPa saturated steam generated by the waste heat boiler 204. The preheated oxygen-enriched air was introduced from the bottom of the fluidized bed gasifier 101 at a flow rate of 1600 Nm 3 / h (mass flow meter model Promass80E), and the pressure drop of the air distribution plate was controlled at 8-10kPa.

[0036] Gasification reaction: rice husk was input into the fluidized bed gasifier 101 at a rate of 100 kg / h by a star-shaped discharger (model XZ-3, rotation speed 15 rpm), and the furnace temperature was maintained at 860±5°C by adjusting the frequency of the screw feeder (model LS325). The generated synthesis gas was transported by a high-temperature synthesis gas pipeline 104 Figure 2 , which was lined with Inconel625 alloy and ceramic insulation layer (thickness 50mm, Al2O3 content ≥90%), with a thermal conductivity of ≤0.05 W / (m·K) and an outer wall temperature of ≤105°C (detected by infrared thermal imager).

[0037] Synthesis gas analysis: gas chromatography (Agilent 7890, equipped with TCD and FID detectors) was used to detect the composition of synthesis gas: H2 was 33.5vol%, CO was 30.1vol%, CO2 was 17.3vol%, CH4 was 4.2vol%, and H2S was 350ppm (GB / T28768-2012). The concentration of H2S was verified by chemical titration method (iodine method) to ensure that it did not exceed the design value of 500ppm.

[0038] 3. Energy coupling Direct combustion power generation: 52 vol% syngas enters combustion chamber 201 and is mixed with air at a stoichiometric ratio of 1.2 (excess air coefficient 1.2), driving gas turbine 202 (model LM6000PC, pressure ratio 16:1) to generate electricity, with an output of 2.8 MW (power meter model WT3000). The combustion chamber outlet temperature is controlled at 1250 ± 20 ° C, NO X Emissions ≤ 25ppm (GB13223-2011).

[0039] Waste heat recovery: The exhaust gas from the gas turbine (temperature 550±10℃, flow rate 5000Nm³ / h) enters the waste heat boiler 204 (model Q10 / 550-2.5-0.8), generating 0.8MPa saturated steam, of which 40% is used for preheating the gasifying agent and 60% drives the steam turbine (model N3-0.8 / 0.15) for supplementary power generation, with a power generation efficiency of 32%.

[0040] 4. Green hydrogen replenishment Hydrogen production by electrolysis: Electrolyzer 301 uses alkaline electrolysis technology (model AE-500, current density 1.8A / cm 2 ), powered by a 303a wind turbine (5MW, 110m impeller diameter) (accounting for 65% of the total electricity). Hydrogen is purified to 99.98 vol% (GB / T3634.2-2011) by a pressure swing adsorption unit (PSA, model CMS-3000, adsorbent 13X molecular sieve), with a flow rate of 1820 Nm 3 / h (mass flow meter model ST800).

[0041] Hydrogen-to-carbon ratio control: hydrogen flow rate / (2×CO flow rate+3×CO2 flow rate)=1820 / (2×1350+3×790)=1.18, monitored in real time by H2 / CO molar ratio sensor 502 (model 7820, accuracy ±0.02) and regulated by PLC controller 503 (model S7-300) through diverter control valve 501 (model V500, response time ≤500ms).

[0042] 5. Methanol synthesis Preparation of mixed gas: Synthesis gas and hydrogen are fully mixed in mixer 401 (model MX-1000, static mixer) and pressurized to 8.0 MPa (GB / T25359-2010) by booster 402 (model 2MCL527, compression ratio 3:1), with an outlet temperature ≤120°C (water cooler model WLS-50).

[0043] Catalytic reaction: the mixed gas is heated at a space velocity of 1800 h -1 Entering the catalytic reactor 403 (inner diameter 1.2m, height 6m) ( Figure 3), packed with CuO 55wt%-ZnO 30wt%-Al2O3 15wt% catalyst (particle size 3mm, bulk density 1.2g / cm 3 ). Circulating water cooling jacket 405 (model CC-200) controlled the reaction temperature 258±3℃, CO conversion 34.8%, methanol selectivity 92.7% (GB / T338-2011). The pressure drop of catalyst bed was ≤0.3MPa (differential pressure transmitter model 3051).

[0044] Product separation: the reaction product was separated by distillation column 404 (theoretical plate number 35, reflux ratio 3:1), 45vol% unreacted gas (H2 / CO molar ratio 2.2) at the top was returned to the mixer 401 by compressor (model 3MCL306), the purity of methanol at the bottom was 99.68wt% (determined by gas chromatography, GB / T338-2011), the yield was 0.54 tons / ton dry basis rice husk (mass flow meter model Promass80F).

[0045] 6. Performance data The total energy efficiency of the system was 65.1% (GB / T2589-2008), calculated as (methanol energy + power generation) / biomass energy x 100%. The catalyst lifetime was 5400 hours (accelerated aging test, temperature 300℃, pressure 10MPa), the carbon emission per unit of methanol was 0.76kg CO2 / kg (ISO14040:2006).

[0046] Example 2 Palm shell (particle size ≤18mm, moisture content 20wt%, ash content 22wt%) was treated: 1. Gasification optimization The exhaust gas from gas turbine 202 (temperature 580℃) entered waste heat boiler 204 (model Q12 / 580-3.5-0.6) to produce 0.6MPa saturated steam, 30% of which was used for preheating of gasification agent, 40% of which was used to drive the steam turbine to generate power, and 30% of which was used to dry the raw material to a moisture content of 15wt% through a jacketed heat exchanger (drying energy consumption 0.15kWh / kg). Fluidized bed gasifier 101 was operated at 880±10℃, the H2 / CO volume ratio in the syngas was 1.15, and the tar content was ≤80mg / Nm 3 (GB / T12723-2024).

[0047] 2. Power management Photovoltaic panel array 303b (model JKM350M, conversion efficiency 18.5%) supplied 11.5MWh of electricity per day, and electrolytic cell 301 had a load rate of 90% (current density 1.6A / cm 2), and the energy storage system (2 MWh, lead-acid battery) maintains hydrogen production at night. The generator 203 supplies 1.2 MW of power to the electrolyzer 301 through the power distribution cabinet 205 (model GGD-3), and the power quality meets GB / T12325-2008.

[0048] 3. Synthesis control The high-temperature syngas pipeline 104 splits at a ratio of 58% into the combustion chamber 201 and 42% into the mixer 401. The PLC controller 503 (model S7-400) adjusts the split control valve 501 in real time based on the H2 / CO molar ratio sensor 502 data using a PID algorithm (Kp=0.5, Ki=0.2, Kd=0.1) to maintain a hydrogen-to-carbon ratio of 1.22±0.03.

[0049] 4. Results The CO2 volume fraction at the outlet of the catalytic reactor 403 is 9.8%, and the methanol yield is 0.50 t / t dry basis. The catalyst retains 93% of its activity after 5300 hours of operation (XPS detects Cu 2+ reduction degree).

[0050] Example 3 Pine sawdust (particle size ≤15 mm, moisture content 32wt%) is treated: 1. System integration The direct-fired power generation unit dries the raw material to a moisture content of 15% using an electrically heated drum dryer, with an energy consumption of 0.12 kWh / kg. The wind turbine 303a (model GW110 / 2000, cut-in wind speed 3 m / s) of the renewable energy power supply module 303 provides 70% of the total power for the electrolyzer 301, and the remaining 30% is supplemented by the generator 203.

[0051] 2. Gasification characteristics The gasifier 101 is operated at 790±10℃ with 70% volume concentration of oxygen-enriched air at the inlet 103, and the syngas tar content is ≤50 mg / Nm 3 (GB / T12723-2024). By adjusting the gasifier flow, the syngas heat value is controlled at 4.5-5.0 MJ / Nm 3 .

[0052] 3. Hydrogen-carbon balance The hydrogen flow rate at the inlet of the mixer 401 is 1.08 times the sum of the CO flow rate and 3 times the CO2 flow rate, and the H2 / CO molar ratio at the outlet of the mixer 401 is stable at 2.05±0.02 (online mass spectrometer model ExtrelCMS).

[0053] 4. Reactor operation The catalytic reactor 403 was operated at 6.5 MPa, 240±2℃, and the circulating water cooling jacket 405 removed heat at a rate of 3.2 MW (heat flow meter model HFM436). The overhead gas from the separation column 404 was recycled at a ratio of 38%, and the inert gas content was ≤8 vol% (determined by gas chromatography).

[0054] 5、Results The methanol production rate was 0.51 t / t of dry wood chips, the total system energy efficiency was 63.7%, and the carbon emissions per unit of methanol were 0.82 kg CO2 / kg (ISO 14040:2006).

[0055] Example 4 1、Dynamic testing The biomass feed rate was increased from 8 t / h to 12 t / h in a step, and the PLC controller 503 completed the following adjustments within 120 seconds: The split adjustment valve 501 adjusted the proportion of syngas for power generation from 45% to 55% (electric actuator model PSL620); The power of the electrolytic cell 301 was increased from 1.8 MW to 2.4 MW (rectifier model ZHS-3000).

[0056] 2、Parameter maintenance The H2 / CO molar ratio at the inlet of the mixer 401 was maintained at 2.10±0.03, and the temperature fluctuation of the catalytic reactor 403 was ≤2.5℃ (temperature controller model TC-300).

[0057] 3、Performance results The methanol production was stabilized at 5.2 tons / hour (mass flow meter model Promass 80F), the outer wall temperature of the high-temperature syngas pipeline 104 was always ≤105℃, and the total system energy efficiency was 62.8% (GB / T 2589-2008).

[0058] Comparative Example 1 1、Difference description The hydrogen flow rate was (2×CO flow rate + 3×CO2 flow rate) = 1.02. The other operating conditions were the same as in Example 1.

[0059] 2、Performance degradation The CO2 volume fraction at the outlet of the catalytic reactor 403 rose to 19.5%, and the methanol selectivity dropped to 81% (GB / T 338-2011); The methanol at the bottom of the separation column 404 exceeded the standard for aldehyde content to 0.15 wt% (GB / T 338-2011); The zinc loss rate reached 8% after the catalyst was operated for 800 hours (determined by XRF), and the production rate dropped to 0.45 t / t of dry basis.

[0060] Comparative Example 2 1、Difference description Fluidized bed gasifier 101 operating temperature 720°C. Other operating conditions same as Example 1.

[0061] 2. Performance degradation Tar deposition (thickness ≥ 2 mm, observed by scanning electron microscope) was detected on the inner wall of high-temperature syngas pipeline 104, with a pressure rise of 35%; Combustion chamber 201 caused the gas turbine 202 to shut down twice due to insufficient syngas heat value (temperature sensor model WZPK-230); Methanol yield dropped to 0.37 t / t dry basis, and catalyst life was shortened to 2800 hours (XPS detected decrease in oxygen vacancy concentration).

[0062] Comparative Example 3 1. Difference description Divide 85% of the high-temperature syngas pipeline 104 to the direct-fired power generation unit 2. Other operating conditions same as Example 1.

[0063] 2. Performance degradation Electrolytic cell 301 power gap reached 45%, and high-priced grid power needed to be purchased, increasing the cost by 0.18 yuan / kWh (verified by electricity price); Insufficient feed to mixer 401 caused the space velocity of catalytic reactor 403 to be too low (space velocity 1200 h -1 ), CO conversion rate dropped to 22%; Unit methanol energy consumption increased by 28% (GB / T 2589-2008), and carbon emissions rose to 0.98 kg CO2 / kg.

[0064] Comparative Example 4 1. Difference description Close the circulating water cooling jacket 405. Other operating conditions same as Example 1.

[0065] 2. Performance degradation Local hot spot temperature in catalytic reactor 403 reached 315°C (detected by thermocouple), and the catalyst sintered and agglomerated (observed by SEM); Methanol selectivity dropped from 92% to 67%, and byproduct dimethyl ether increased to 8.5 wt% (detected by GC-MS); Catalyst life was only 48 hours, and the system was forced to shut down for maintenance (pressure sensor alarm).

[0066] Comparative Example 5 1. Difference description All overhead gas from separation column 404 was discharged. Other operating conditions same as Example 1.

[0067] 2. Performance degradation CO single-pass conversion rate is only 18.3%, raw material consumption increases to 2.3 tons / t methanol (mass balance calculation); Carbon emissions rise to 0.61 tons / t methanol, an increase of 79% compared with Example 1 (LCA analysis); System energy efficiency drops to 42.7% (GB / T 2589-2008).

[0068] Table 1: Comparison of key data

[0069] Standardization of detection method 1. Syngas analysis: Gas chromatograph (Agilent 7890), TCD detector, carrier gas He, column temperature 80℃.

[0070] 2. Catalyst characterization: X-ray diffraction (XRD-6100) analyzes the crystal structure; BET method (ASAP2020) determines the specific surface area.

[0071] 3. Energy efficiency calculation: Total energy efficiency = (methanol energy + power generation) / biomass energy × 100%, energy conversion coefficient: methanol 22.7 MJ / kg, biomass 18 MJ / kg.

[0072] The remaining matters of the present application are known technologies.

[0073] The above examples are only to illustrate the technical concept and characteristics of the present application, and the purpose is to enable those skilled in the art to understand the content of the present application and to implement it, and cannot limit the protection scope of the present application. Any equivalent changes or modifications made in accordance with the spirit and essence of the present application shall be covered within the protection scope of the present application.

Claims

1. A biomass gasification direct combustion coupled green hydrogen to methanol system, characterized in that: include: A biomass gasification unit comprising a fluidized bed gasifier (101), a feeding device (102) connected to a feeding port of the fluidized bed gasifier, and a gasifying agent inlet (103) provided at the bottom of the fluidized bed gasifier (101); A direct-fired power generation unit comprising a combustion chamber (201), a gas turbine (202) connected to an outlet of the combustion chamber, and a generator (203) coaxially connected to the gas turbine; A green hydrogen production unit comprising an electrolyzer (301), a purification device (302) connected to a hydrogen outlet of the electrolyzer, and a renewable energy power supply module (303) connected to a power input end of the electrolyzer; A methanol synthesis unit comprising a mixer (401), a booster (402) connected to an outlet of the mixer, a catalytic reactor (403) connected to an outlet of the booster, and a separation tower (404) connected to a product outlet of the catalytic reactor; The high-temperature synthesis gas pipeline (104) has an inlet end connected to the gas outlet of the fluidized bed gasifier (101), and the outlet end is divided into two paths: The first branch is connected to the inlet of the combustion chamber (201) of the direct-fired power generation unit; The second branch is connected to the first inlet of the mixer (401) of the methanol synthesis unit; The hydrogen outlet of the purification device (302) is connected to the second inlet of the mixer (401).

2. The biomass gasification direct combustion coupled green hydrogen to methanol system according to claim 1, characterized in that: The operating temperature of the fluidized bed gasifier (101) is 750-900°C, and the gasifying agent is oxygen-enriched air with a volume concentration of 50-80%; The high-temperature synthesis gas pipeline (104) is lined with a ceramic insulation layer, and the outer wall is covered with Inconel625 alloy.

3. The biomass gasification direct combustion coupled green hydrogen to methanol system according to claim 1, characterized in that: The direct-fired power generation unit further comprises a waste heat boiler (204), the air inlet of which is in communication with the exhaust port of the gas turbine (202); The steam outlet of the waste heat boiler (204) is connected to the gasification agent preheater (105) of the biomass gasification unit.

4. The biomass gasification direct combustion coupled green hydrogen to methanol system according to claim 1, characterized in that: The renewable energy power supply module (303) comprises a wind turbine (303a) and a photovoltaic panel array (303b); The power output end of the generator (203) is connected to the electrolytic cell (301) and the system power equipment respectively through the power distribution cabinet (205).

5. The biomass gasification direct combustion coupled green hydrogen to methanol system according to claim 1, characterized in that: The catalytic reactor (403) is filled with a Cu-ZnO-Al2O3 catalyst, wherein the CuO content is 40-60wt%, the ZnO content is 25-40wt%, and the Al2O3 content is 10-20wt%; The catalytic reactor (403) is externally provided with a circulating water cooling jacket (405).

6. The biomass gasification direct combustion coupled green hydrogen to methanol system according to claim 1, characterized in that: Also included is an integrated control unit, which includes: A diversion regulating valve (501) provided on a high-temperature synthesis gas pipeline (104); A H2 / CO molar ratio sensor (502) provided at the inlet of the mixer (401); A PLC controller (503) is connected to the signals of the diversion regulating valve (501) and the H2 / CO molar ratio sensor (502).

7. A biomass-to-methanol method based on the biomass gasification direct combustion coupled green hydrogen-to-methanol system according to any one of claims 1-6, characterized in that: Including steps: S1, feeding biomass particles with a particle size of ≤20 mm into a fluidized bed gasifier (101) through a feeding device (102), introducing an oxygen-enriched gasifier with a volume concentration of 50-80%, and generating a synthesis gas containing H2, CO, and CO2 at 750-900°C; S2. Synthesis gas is transported and divided through the high-temperature synthesis gas pipeline (104): 40-60% of the volume of the synthesis gas enters the combustion chamber (201) for direct combustion and power generation; The remaining synthesis gas enters the mixer (401); S3. The electrolyzer (301) uses the electricity from the renewable energy power supply module (303) and / or the generator (203) to electrolyze water, and the generated hydrogen is input into the mixer (401) after passing through the purification device (302).

8. The biomass-to-methanol method according to claim 7, wherein: In step S3, the ratio of the molar flow rate of hydrogen input to the mixer (401) to twice the molar flow rate of carbon monoxide in the synthesis gas plus three times the molar flow rate of carbon dioxide is 1.05 to 1.

25.

9. The biomass-to-methanol method according to claim 7, wherein: The mixed gas output from the mixer (401) is pressurized to 5.0-10.0 MPa by the supercharger (402) and then enters the catalytic reactor (403) for reaction at 220-280°C; The volume fraction of CO2 in the outlet gas of the catalytic reactor (403) is controlled at 8-15%.

10. The biomass-to-methanol method according to claim 9, wherein: The outlet gas of the catalytic reactor (403) is distilled in a separation tower (404), and unreacted gas is discharged from the top of the tower, of which 30-50% of the volume is returned to the mixer (401) for recycling; and a methanol product with a purity of ≥99.5wt% is obtained at the bottom of the tower.

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