System and method for producing fuel oil from biomass through methanol

Abstract

The invention belongs to the technical field of fuel oil production systems, and particularly relates to a system and a method for producing fuel oil from biomass through methanol. Biomass pyrolysis or gasification is adopted for power generation, obtained green electricity is used for electrolyzing water to prepare green hydrogen and green oxygen, green hydrogen and carbon monoxide and carbon dioxide obtained after biomass pyrolysis or gasification are synthesized into green methanol, and green oxygen can assist in biomass power generation; the synthesized methanol is further used for synthesizing propylene, and then propylene oligomerization is continued to obtain a long-carbon-chain hydrocarbon product; by-product water generated in the process of preparing methanol through carbon dioxide hydrogenation and preparing propylene through methanol passes through a water treatment system and is used as a raw material to return to the electrolyzed water unit, carbon dioxide generated in each process is used as a raw material to return to the unit of preparing methanol through carbon dioxide hydrogenation, and excessive carbon dioxide can obtain carbon monoxide through water gas reverse transformation; carbon monoxide can be used as a raw material for preparing methanol through hydrogenation, and can also be used as heat energy or used for power generation, so that a full-green process fuel oil fuel product synthesis technology is realized. Methanol preparation through carbon dioxide hydrogenation, propylene preparation through methanol and propylene oligomerization are all exothermic reactions, and reaction waste heat can be used for power generation. In the whole system, waste heat recovery and byproduct separation, collection and reutilization are adopted, and energy conservation and cost reduction are achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of fuel oil production systems, and particularly relates to a system and method for producing fuel oil from biomass via methanol. Background Art

[0002] Traditional coal chemical industry and natural gas chemical industry produce carbon dioxide. Coal and natural gas are non-renewable energy sources. Optimizing chemical processes and applying carbon dioxide emission reduction technologies have practical significance.

[0003] At the same time, traditional fuel oil is mainly obtained through coal chemical industry and crude oil refining. However, traditional coal chemical industry and refinery processes have disadvantages such as high carbon dioxide emission intensity, low carbon atom utilization efficiency, and high energy consumption. Moreover, since the carbon dioxide emitted into the air has a low concentration, the cost of capturing and purifying carbon dioxide in flue gas is relatively high. Summary of the Invention

[0004] The purpose of the present invention is to overcome the disadvantages of traditional fuel oil production processes, such as high energy consumption, high carbon dioxide emission intensity, and high carbon reduction cost, and to provide a system and method for producing fuel oil from biomass via methanol, realizing a negative carbon new technology for the resource utilization of biomass that is cheap and easily available. This technology has the remarkable advantages of high energy utilization efficiency and high carbon atom utilization efficiency.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A system for producing fuel oil from biomass via methanol includes a biomass power generation unit, a water electrolysis unit, a water gas shift reverse unit, a carbon dioxide hydrogenation to methanol unit, a methanol to propylene unit, a fuel oil synthesis unit, and a wastewater treatment unit;

[0007] The biomass power generation unit inputs biomass. The biomass power generation unit supplies power to the water electrolysis unit, and the carbon dioxide generated by the biomass power generation unit is respectively supplied to the water gas shift reverse unit and the carbon dioxide hydrogenation to methanol unit; the oxygen generated by the water electrolysis unit is supplied to the biomass power generation unit; the hydrogen generated by the water electrolysis unit is respectively supplied to the carbon dioxide hydrogenation to methanol unit and the water gas shift reverse unit; the carbon monoxide generated by the water gas shift reverse unit is respectively supplied to the biomass power generation unit and the carbon dioxide hydrogenation to methanol unit; the methanol generated by the carbon dioxide hydrogenation to methanol unit is respectively supplied to the methanol to propylene unit and the fuel oil synthesis unit; the propylene generated by the methanol to propylene unit is supplied to the fuel oil synthesis unit, and the fuel oil synthesis unit synthesizes fuel oil; the preheating generated by the carbon dioxide hydrogenation to methanol unit, the methanol to propylene unit, and the fuel oil synthesis unit is all supplied to the biomass power generation unit; the wastewater generated by the carbon dioxide hydrogenation to methanol unit and the methanol to propylene unit is sent to the wastewater treatment unit, and the pure water generated by the wastewater treatment unit is respectively supplied to the water electrolysis unit and the water gas shift reverse unit.

[0008] The present invention adopts biomass pyrolysis or gasification power generation technology. Biomass is inexpensive and widely sourced, belonging to green electricity with low power generation costs and environmental friendliness. The electricity is stored in a green electricity energy storage unit to avoid power supply imbalance problems caused by seasonal biomass shortages. Carbon monoxide and carbon dioxide generated by biomass power generation can be synthesized into green methanol through carbon dioxide hydrogenation technology, and carbon dioxide (or carbon monoxide) generated in the processes of methanol to propylene and propylene oligomerization can be separated and purified and then returned to the carbon dioxide hydrogenation to methanol unit to synthesize green methanol. There is no carbon dioxide emission throughout the process, which belongs to a negative carbon process technology. The reactions of carbon dioxide hydrogenation to methanol, methanol to propylene, and propylene oligomerization are all exothermic reactions, and the reaction waste heat can be used for power generation. The carbon monoxide obtained from the water gas shift reverse unit can also be used as heat energy or for power generation, or sold as a by-product.

[0009] In summary, the integrated utilization technology of waste heat recovery and wastewater treatment is adopted in the whole system, reducing the emissions of three wastes and production costs. The invention technology belongs to a new technology with full-process green, low energy consumption, and zero emissions, and has great potential for process application.

[0010] As a preferred embodiment of the present invention, the present invention further includes a green electricity energy storage unit, a green oxygen collection unit, and a green hydrogen collection unit. The electric energy obtained by the biomass power generation unit is sent to the green electricity energy storage unit for storage, and the electric energy of the green electricity energy storage unit is supplied to the electrolyzed water unit. The green oxygen collection unit is connected between the electrolyzed water unit and the biomass power generation unit, and the green hydrogen collection unit is connected between the electrolyzed water unit and the carbon dioxide hydrogenation to methanol unit.

[0011] As a preferred embodiment of the present invention, part of the carbon monoxide generated by the water gas shift reverse unit is sold externally.

[0012] A method for producing fuel oil from biomass via methanol, comprising the following steps:

[0013] S1: Biomass raw materials, green oxygen from the oxygen collection unit, and carbon monoxide from the water gas shift reverse unit enter the biomass power generation unit for gasification reaction. The gasified gas drives an internal combustion engine or a steam turbine to generate electricity. The obtained green electricity is supplied to the electrolyzed water unit or sent to the green electricity energy storage unit for storage. The tail gas including carbon dioxide generated after gasification and generated by the internal combustion engine and the steam turbine is sent to the carbon dioxide collection unit for treatment.

[0014] S2: The electrolyzed water unit electrolyzes pure water. The generated oxygen is sent to the biomass power generation unit, and the generated hydrogen is sent to the green hydrogen collection unit and the water gas shift reverse unit respectively.

[0015] S3: In the carbon dioxide collection unit, the gasified product and the tail gas containing carbon dioxide generated by the internal combustion engine and steam turbine pass through a desulfurization tower to remove impurities including H2S; the carbon dioxide after impurity removal and the carbon monoxide from the outlet of the water gas reverse shift unit enter the carbon dioxide hydrogenation to methanol unit together;

[0016] S4: In the water gas reverse shift unit, hydrogen from the green hydrogen collection unit and carbon dioxide from the biomass power generation unit react under the action of a nickel-based catalyst to generate carbon monoxide and water; after the reaction mixture is separated, a part of the carbon monoxide is sent to the biomass power generation unit, and the remaining carbon monoxide is sent to the carbon dioxide hydrogenation to methanol unit;

[0017] S5: In the carbon dioxide hydrogenation to methanol unit, carbon dioxide from the carbon dioxide collection unit and carbon monoxide from the water gas reverse shift unit undergo a catalytic reaction under the action of a carbon dioxide hydrogenation catalyst to generate a mixed material mainly composed of methanol and water; the heat of the high-temperature methanol gas in the carbon dioxide hydrogenation to methanol unit is supplied to the biomass power generation unit through heat exchange, the methanol product is sent to the methanol to propylene unit, and the wastewater is discharged to the wastewater treatment unit;

[0018] S6: In the methanol to propylene unit, the refined methanol from the carbon dioxide hydrogenation to methanol unit enters the dimethyl ether reactor and generates dimethyl ether and water under the action of an alumina or molecular sieve catalyst; the mixed gas of dimethyl ether, water and unreacted methanol generated by the reaction and the steam from the outside, ethylene, ethane, butene and C5+ olefins, butane and C5+ alkanes separated from the methanol to propylene reaction products enter the methanol to propylene reactor in proportion, and the reaction raw materials generate hydrocarbons mainly composed of ethylene, propylene and isobutene in the methanol to propylene reactor; after heat exchange with the raw material gas and low-temperature steam of the methanol to propylene reactor, the heat is sent to the biomass power generation unit, the heavy component product including propylene at the bottom of the distillation column is pressurized and sent to the tank farm for storage or to the downstream fuel oil synthesis unit, and the wastewater is sent to the wastewater treatment unit;

[0019] S7: In the fuel oil synthesis unit, propylene from the methanol to propylene unit generates C5-C mixed hydrocarbon products mainly composed of nonene and dodecene under the action of a strong acid catalyst, and then undergoes hydrorefining to remove unsaturated hydrocarbons to obtain the required fuel oil product. The waste heat of the fuel oil synthesis unit is supplied to the biomass power generation unit; 22 S8: In the wastewater treatment unit, the wastewater is first stripped by steam to remove volatile organic components, then passed through an adjustment tank and coagulation sedimentation to remove large particles, suspended solids and part of the organic matter, and finally the residual pollutants in the wastewater are removed and the water quality is improved by microbial metabolism or adsorbent filtration. The purified water after treatment is sent to the electrolysis water unit as the raw water for electrolysis water.

[0020] S8: In the wastewater treatment unit, the wastewater is first stripped by steam to remove volatile organic components, then passed through an adjustment tank and coagulation sedimentation to remove large particles, suspended solids and part of the organic matter, and finally the residual pollutants in the wastewater are removed and the water quality is improved by microbial metabolism or adsorbent filtration. The purified water after treatment is sent to the electrolysis water unit as the raw water for electrolysis water.

[0021] As a preferred embodiment of the present invention, in step S1, the equivalent ratio of oxygen to biomass raw material fed into the gasifier of the biomass power generation unit is 0.1 - 0.4:1, the temperature of the gasifier is controlled at 300 - 800 °C, and the pressure inside the gasifier is controlled at 0.1 - 0.8 Mpa for gasification reaction; the combustible gas including H2, CO, CO2 and CH4 after gasification is purified and then drives an internal combustion engine or a steam turbine to generate electricity, and part of the green electricity obtained is sent to the green electricity energy storage unit for storage, and the green electricity energy storage unit is converted into battery power or used for water energy storage in the reservoir for standby power generation.

[0022] As a preferred embodiment of the present invention, in step S3, the desulfurizer in the desulfurization tower is saturated sodium bicarbonate solution or solid sodium bicarbonate, and the temperature of the desulfurization tower is controlled at 150 - 450 °C; the carbon dioxide after desulfurization, the carbon monoxide from the outlet of the water gas shift unit and the hydrogen from the green hydrogen collection unit enter the carbon dioxide hydrogenation to methanol unit together, and the gas ratio fed into the carbon dioxide hydrogenation to methanol unit is controlled, CO:H2 = 1:2 - 2.1, CO2:H2 = 1:3 - 3.1.

[0023] As a preferred embodiment of the present invention, in step S5, CO2, CO, and H2 are preheated to 220 - 350 °C and pressurized to 1 - 8 MPa, and then undergo a catalytic reaction under the action of a carbon dioxide hydrogenation catalyst to generate a mixed material mainly composed of methanol and water; the high-temperature gas containing methanol at the outlet of the reactor is used as the heating source of the gas-gas heat exchanger, and then the methanol-containing mixed gas is cooled to 40 °C by a water cooler and enters a gas-liquid separator. The gas phase returns to the recycle gas compressor as recycle gas for boosting; the liquid phase enters a flash tank. The flow rate of the crude methanol from the flash tank is 85 kg / h, the temperature is 40 °C, and the pressure is 0.4 MPa, which is sent to the middle part of the methanol pre-distillation column. The components at the top of the methanol pre-distillation column are condensed by a condenser, and the condensate returns to the methanol pre-distillation column; the non-condensable gas at the top of the methanol pre-distillation column is sent to the carbon dioxide collection unit for unified treatment; the methanol coming out from the bottom of the methanol pre-distillation column enters the middle part of the methanol distillation column. The components at the top of the column are condensed by a condenser, and part of the condensate returns to the distillation column, and part of the methanol is sent as a product to the methanol to propylene unit; the bottom of the column is water, which is discharged from the bottom to the wastewater treatment unit.

[0024] As a preferred embodiment of the present invention, in step S6, the refined methanol from the carbon dioxide hydrogenation to methanol unit first undergoes vaporization and is preheated to 240 - 350 °C, and then enters the dimethyl ether reactor under the condition of controlling the pressure below 0.5 Mpa at normal pressure, and dimethyl ether and water are generated under the action of an alumina or molecular sieve catalyst.

[0025] As a preferred embodiment of the present invention, in step S6, the mixed gas of dimethyl ether, water and unreacted methanol generated by the reaction, the water vapor from the outside, ethylene, ethane, butene, olefins with five or more carbon atoms, butane and alkanes with five or more carbon atoms separated from the methanol-to-propylene reaction products enter the methanol-to-propylene reactor in proportion; the catalyst used in the methanol-to-propylene reaction is a ZSM-5 or SAPO-34 molecular sieve catalyst, and the reaction conditions for the methanol-to-propylene reaction are controlled at 370-490 °C and below 0.5 Mpa at normal pressure. The reaction raw materials generate various hydrocarbons mainly composed of ethylene, propylene and isobutene in the methanol-to-propylene reactor; after heat exchange with the raw material gas and low-temperature steam of the methanol-to-propylene reactor.

[0026] As a preferred embodiment of the present invention, in step S6, after recovering heat, through flash gas-liquid separation, the gaseous mixed hydrocarbons are sent to the separation unit, compressed to 1.2 MPa and then sent to the water washing process to remove unreacted methanol and ethanol. After separation, they are sent to the stripping tower for steam stripping and returned to the MTP reaction system for recycling. The material after water washing is sent to the dehydration and decarbonization tower, and an adsorbent is used to adsorb and remove CO2 and H2O in the gas phase. Then the remaining gaseous mixed hydrocarbons are compressed to 2.1 MPa and sent to the distillation tower to remove non-condensable gases including CO and methane. The non-condensable gases are sent to the carbon dioxide collection unit for unified treatment. The heavy component products including propylene at the bottom of the distillation tower are pressurized and sent to the tank farm for storage or sent to the downstream fuel oil synthesis unit; the liquid phase obtained by flash gas-liquid separation is wastewater containing organic matter. After steam stripping and vaporization, part of it is sent to the electrolyzed water unit, and part of it is vaporized and sent to the methanol-to-propylene reaction unit for its own use.

[0027] The beneficial effects of the present invention are as follows:

[0028] The present invention adopts biomass pyrolysis or gasification power generation technology. Biomass is inexpensive and widely sourced, belongs to green electricity, has low power generation costs and is environmentally friendly; the electricity is stored in the green electricity energy storage unit to avoid power supply imbalance problems caused by seasonal biomass shortages; carbon monoxide and carbon dioxide generated by biomass power generation, and then carbon dioxide (or carbon monoxide) generated by the synthesis of green methanol by carbon dioxide hydrogenation technology, methanol-to-propylene, and propylene oligomerization can all be separated and purified and then returned to the carbon dioxide hydrogenation to methanol unit to synthesize green methanol. There is no carbon dioxide emission throughout the process, which belongs to a negative carbon process technology; the reactions of carbon dioxide hydrogenation to methanol, methanol-to-propylene, and propylene oligomerization are all exothermic reactions, and the reaction waste heat can all be used for power generation; carbon monoxide obtained in the water gas shift reverse unit can also be used as heat energy or for power generation, or sold as a by-product. The waste heat recovery and comprehensive utilization technology of wastewater treatment are adopted in the whole system, reducing the emissions of three wastes and production costs. The invention technology belongs to a new technology with full-process green, low energy consumption and zero emissions, and has great potential for process application. Description of the Drawings

[0029] Figure 1It is a structural schematic diagram of the present invention.

[0030] In the figure: 1 - Biomass power generation unit; 2 - Green power energy storage unit; 3 - Water electrolysis unit; 4 - Green oxygen collection unit; 5 - Green hydrogen collection unit; 6 - Water gas reverse shift unit; 7 - Carbon dioxide collection unit; 8 - Carbon dioxide hydrogenation to methanol unit; 9 - Methanol to propylene unit; 10 - Fuel oil synthesis unit; 11 - Wastewater treatment unit. Specific embodiments

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and illustrated herein can be arranged and designed in various different configurations.

[0032] Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed present invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention. It should be noted that, without conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

[0033] As Figure 1 shown, the system for producing fuel oil from biomass in this embodiment includes a biomass power generation unit 1, a green power energy storage unit 2, a water electrolysis unit 3, a green oxygen collection unit 4, a green hydrogen collection unit 5, a water gas reverse shift unit 6, a carbon dioxide collection unit 7, a carbon dioxide hydrogenation to methanol unit 8, a methanol to propylene unit 9, a fuel oil synthesis unit 10, and a wastewater treatment unit 11.

[0034] The biomass power generation unit 1 inputs biomass. The biomass power generation unit 1 supplies power to the water electrolysis unit 3. The carbon dioxide generated by the biomass power generation unit 1 is respectively supplied to the water gas shift reverse unit 6 and the carbon dioxide collection unit 7. The electric energy obtained by the biomass power generation unit 1 is sent to the green power energy storage unit 2 for storage, and the electric energy of the green power energy storage unit 2 is supplied to the water electrolysis unit 3. The oxygen generated by the water electrolysis unit 3 is supplied to the green oxygen collection unit 4, and the oxygen of the green oxygen collection unit 4 is supplied to the biomass power generation unit 1. The hydrogen generated by the water electrolysis unit 3 is respectively supplied to the green hydrogen collection unit 5 and the water gas shift reverse unit 6, and the hydrogen of the green hydrogen collection unit 5 is supplied to the carbon dioxide hydrogenation to methanol unit 8. The carbon monoxide generated by the water gas shift reverse unit 6 is respectively supplied to the biomass power generation unit 1 and the carbon dioxide hydrogenation to methanol unit 8, and the remaining part of the carbon monoxide is sold externally. The carbon dioxide of the carbon dioxide collection unit 7 is supplied to the carbon dioxide hydrogenation to methanol unit 8. The methanol generated by the carbon dioxide hydrogenation to methanol unit 8 is respectively supplied to the methanol to propylene unit 9 and the fuel oil synthesis unit 10. The propylene generated by the methanol to propylene unit 9 is supplied to the fuel oil synthesis unit 10, and the fuel oil synthesis unit 10 synthesizes fuel oil. The preheat generated by the carbon dioxide hydrogenation to methanol unit 8, the methanol to propylene unit 9 and the fuel oil synthesis unit 10 is all supplied to the biomass power generation unit 1. The wastewater generated by the carbon dioxide hydrogenation to methanol unit 8 and the methanol to propylene unit 9 is sent to the wastewater treatment unit 11, and the pure water generated by the wastewater treatment unit 11 is supplied to the water electrolysis unit 3.

[0035] The described biomass power generation unit 1 is provided with a first green power outlet connected to the green power energy storage unit 2, a second green power outlet connected to the water electrolysis unit 3, a first carbon dioxide outlet connected to the carbon dioxide collection unit 7, a second carbon dioxide outlet connected to the water gas shift reverse unit 6, a biomass inlet, a green oxygen inlet connected to the green oxygen collection unit 4, and a carbon monoxide inlet connected to the water gas shift reverse unit 6.

[0036] The described water electrolysis unit 3 is provided with a green oxygen outlet and a green hydrogen outlet. The green oxygen outlet is connected to the green oxygen collection unit 4, and the green hydrogen outlet is connected to the green hydrogen collection unit 5. The power it requires comes from the biomass power generation unit 1.

[0037] The described carbon dioxide hydrogenation to methanol unit 8 is provided with a first green methanol outlet connected to the methanol to propylene unit 9, a second green methanol outlet connected to the fuel oil synthesis unit 10, a green hydrogen inlet connected to the green hydrogen collection unit 5, a carbon dioxide inlet connected to the carbon dioxide collection unit 7, a carbon monoxide inlet connected to the water gas shift reverse unit 6, and a first wastewater outlet connected to the wastewater treatment unit 11.

[0038] The described methanol-to-propylene unit 9 is provided with a first green methanol inlet connected to the carbon dioxide hydrogenation-to-methanol unit 8 and a propylene outlet connected to the fuel oil synthesis unit 10; the described fuel oil synthesis unit 10 is provided with a second green methanol inlet connected to the carbon dioxide hydrogenation-to-methanol unit 8 and a propylene inlet connected to the methanol-to-propylene unit 9, and the generated fuel oil is used as the main product of this system.

[0039] The described water gas reverse shift unit 6 is provided with a carbon dioxide inlet connected to the biomass power generation unit 1, a green hydrogen inlet connected to the green hydrogen collection unit 5, a first carbon monoxide outlet connected to the carbon dioxide hydrogenation-to-methanol unit 8, and a second carbon monoxide outlet connected to the biomass power generation unit 1.

[0040] The described wastewater treatment unit 11 is provided with a first wastewater inlet connected to the carbon dioxide hydrogenation-to-methanol unit 8 and a second wastewater inlet connected to the methanol-to-propylene unit 9; the treated pure water is respectively sent to the electrolyzed water unit 3 and the water gas reverse shift unit 6.

[0041] The method for producing fuel oil from biomass via methanol in this embodiment specifically includes the following steps:

[0042] Biomass raw materials (selected from raw materials such as wood chips, rice husks, and straw), green oxygen from the oxygen collection unit, and carbon monoxide from the water gas reverse shift unit 6 enter the power generation unit for gasification reaction. The equivalent ratio of oxygen to biomass raw materials = 0.1 - 0.4:1, preferably 0.2 - 0.4:0.3; the gasification furnace temperature is controlled at 300 - 800 °C, preferably 550 - 650 °C; the pressure inside the gasification furnace is controlled at 0.1 - 0.8 MPa, preferably 0.2 - 0.4 MPa. After gasification, combustible gases such as H2, CO, CO2, and CH4 are purified and then drive an internal combustion engine or a steam turbine to generate electricity. The obtained green electricity is sent to the green electricity energy storage unit 2 for storage. The green electricity energy storage unit 2 can be converted into battery power or used for water energy storage in a reservoir for standby power generation; the carbon dioxide and other tail gases generated after gasification and those generated by the internal combustion engine and the steam turbine are sent to the carbon dioxide collection unit 7 for treatment.

[0043] In the carbon dioxide collection unit 7, tail gases such as those generated after gasification and those generated by internal combustion engines and steam turbines, including carbon dioxide, are passed through a desulfurization tower to remove impurities such as H2S. The gas mixture is mainly separated by pressure swing adsorption to obtain relatively pure carbon dioxide, hydrogen, carbon monoxide, and their mixed gases. The desulfurizer in the desulfurization tower is saturated sodium bicarbonate solution or solid sodium bicarbonate, and the temperature of the desulfurization tower is controlled at 150 - 450 °C, preferably 250 - 350 °C. The desulfurized gas and the gas from the outlet of the water gas reverse shift unit 6 enter the carbon dioxide hydrogenation to methanol unit 8 together. The gas ratios of the carbon dioxide collection unit 7, the water gas reverse shift unit 6, and the green hydrogen collection unit 5 fed into the carbon dioxide hydrogenation to methanol unit 8 are controlled as follows: CO:H2 = 1:2 - 2.1, CO2:H2 = 1:3 - 3.1.

[0044] In the water gas reverse shift unit 6, hydrogen from the green hydrogen collection unit 5 and carbon dioxide from the biomass power generation unit 1 react under the action of a nickel-based catalyst at reaction conditions of 350 - 650 °C, normal pressure below 2 Mpa, and a hydrogen-carbon molar ratio of 1 - 2 to generate carbon monoxide and water. The preferred reaction conditions are 550 - 600 °C, normal pressure below 0.5 Mpa, and a hydrogen-carbon molar ratio of 1 - 1.3. After the reaction mixture is separated, a part of the carbon monoxide is sent to the biomass power generation unit 1, and the remaining carbon monoxide is sent to the carbon dioxide hydrogenation to methanol unit 8.

[0045] In the carbon dioxide hydrogenation to methanol unit 8, CO2, CO, and H2 from the carbon dioxide collection unit 7 and the water gas reverse shift unit 6 are preheated (220 - 350 °C), pressurized (1 - 8 MPa), and then undergo a catalytic reaction under the action of a carbon dioxide hydrogenation catalyst (the main component is Cu / Zn / Al / metal X, and metal X is a rare earth metal) to generate a mixed material mainly composed of methanol and water. To fully recover heat energy, the high-temperature methanol-containing gas at the reactor outlet is used as the heating source of the gas-gas heat exchanger, and then the methanol-containing mixed gas is cooled to 40 °C by a water cooler and enters a gas-liquid separator. The gas phase is returned as recycle gas to the recycle gas compressor for boosting pressure. The liquid phase enters a flash tank. The flow rate of the crude methanol out of the flash tank is about 85 kg / h, the temperature is 40 °C, and the pressure is 0.4 MPa, which is sent to the middle part of the methanol pre-distillation tower (referred to as the pre-tower). The components at the top of the pre-tower are condensed by a condenser, and the condensate is returned to the pre-tower; the non-condensable gas at the top of the pre-tower is sent to the carbon dioxide collection unit 7 for unified treatment; the methanol coming out from the bottom of the pre-tower enters the middle part of the methanol distillation tower. The components at the top of the tower are condensed by a condenser, and a part of the condensate is returned to the distillation tower, and a part of the methanol is sent as a product to the methanol to propylene unit 9; the bottom of the tower is water, which is discharged from the bottom to the wastewater treatment unit 11.

[0046] In the methanol - to - propylene unit 9, the refined methanol from the carbon dioxide hydrogenation to methanol unit 8 is first vaporized and preheated to 240 - 350°C. Then, under the condition of controlling the pressure below 0.5 Mpa at atmospheric pressure, it enters the dimethyl ether reactor. Under the action of an alumina or molecular sieve - type catalyst, dimethyl ether and water are generated. The methanol conversion rate of this reaction is about 75 - 88%. The mixed gas of dimethyl ether, water, and unreacted methanol generated by the reaction, together with water vapor from the outside, ethylene, ethane, butene, olefins with more than 5 carbon atoms, butane, and alkanes with more than 5 carbon atoms separated from the methanol - to - propylene reaction products, enter the methanol - to - propylene reactor in proportion. The catalyst used in the methanol - to - propylene reaction is a ZSM - 5 or SAPO - 34 molecular sieve catalyst. The reaction conditions of methanol - to - propylene are controlled at 370 - 490°C and below 0.5 Mpa at atmospheric pressure, preferably 440 - 480°C and 0.1 - 0.3 Mpa. The reaction raw materials generate various hydrocarbons mainly composed of ethylene, propylene, and isobutene in the methanol - to - propylene reactor. After heat exchange with the raw material gas of the methanol - to - propylene reactor, low - temperature steam, etc., and recovering heat as much as possible, it undergoes flash vapor - liquid separation. The gas - phase mixed hydrocarbons are sent to the separation unit, compressed to about 1.2 MPa, and then sent to the water - washing process to remove unreacted methanol and ethanol. After separation, they are sent to the stripping tower and stripped with steam and returned to the MTP reaction system for recycling. The material after water - washing is sent to the dehydration and decarbonization tower, and an adsorbent is used to adsorb and remove CO2 and H2O in the gas phase. Then the remaining gas - phase mixed hydrocarbons are compressed to about 2.1 MPa and sent to the distillation tower to remove non - condensable gases such as CO and methane. The non - condensable gases are sent to the carbon dioxide collection unit 7 for unified treatment. The heavy - component products such as propylene at the bottom of the distillation tower are pressurized and sent to the storage tank area for storage or sent to the downstream fuel oil synthesis unit 10. The liquid phase obtained from the flash vapor - liquid separation is wastewater containing organic matter. After steam stripping and vaporization, part of it is sent to the electrolyzed water unit 3, and part of it is vaporized and sent to the methanol - to - propylene reaction unit for its own use.

[0047] In the fuel oil synthesis unit 10, the propylene from the methanol - to - propylene unit 9, under the action of strong acid catalysts such as fixed phosphates, generates C5 - C 22 mixed hydrocarbon products mainly composed of nonene and dodecene. Then, through hydrorefining to remove unsaturated hydrocarbons such as olefins and alkynes in the mixed hydrocarbons, the required fuel oil products are obtained.

[0048] In the wastewater treatment unit 11, the wastewater is first stripped with steam to remove volatile organic components, then passed through an adjustment tank, coagulation and sedimentation to remove large particles, suspended solids, and part of the organic matter. Finally, the residual pollutants in the wastewater are removed and the water quality is improved by microbial metabolism or adsorbent filtration. The purified water after treatment is sent to the electrolyzed water unit 3 as the raw water for electrolyzed water.

[0049] The carbon dioxide emission data obtained by the above - mentioned invention method are specifically shown in Table 1.

[0050] Table 1 shows the carbon dioxide emission data of the fuel oil synthesis system and the traditional path of fuel oil synthesis.

[0051]

[0052] Note: The above table is calculated based on the scale of 100,000 tons / year of propylene production, requiring 300,000 tons of methanol per year and consuming 420,000 tons of methanol; since biomass raw materials absorb carbon dioxide in the atmosphere during the growth process, the carbon emissions of biomass fuels are almost zero throughout the life cycle.

[0053] It can be seen from Table 1 that the carbon dioxide emission data obtained by the technology of the present invention is -420,000 tons, which belongs to the negative carbon process technology. Compared with the traditional path of generating fuel oil, the annual carbon dioxide emission is reduced by 1,057,100 tons, and the effect of carbon reduction and emission reduction is remarkable.

[0054] In the present invention, the hydrogenation of carbon dioxide to methanol, methanol to propylene, and propylene oligomerization are all exothermic reactions, and the reaction waste heat can be used for power generation; the water gas shift reverse unit 6 obtains carbon monoxide, which can also be used as heat energy or for power generation, or can be sold as a by-product.

[0055] Using the green oxygen generated by electrolyzing water for biomass pyrolysis or gasification can, on the one hand, precisely inhibit the complete combustion degree of biomass, and on the other hand, greatly reduce the impurity content in the gasified gas, thereby improving the efficiency of biomass power generation.

[0056] In the present invention, compared with the traditional methanol-to-propylene process flow, the mixed hydrocarbon products generated by the methanol-to-propylene unit 9 only need to remove non-condensable gas, C2 components, and C5 or C6 and above components (C5 to C6 and above components can also be directly used as fuel oil products after hydrorefining), and there is no need to separate olefins and alkanes, saving equipment investment and the operating cost of the separation tower, with a simple process flow and low cost.

[0057] The above settings of the system structure are for balancing the energy utilization of the system, the comprehensive utilization of waste gas and waste water, improving the energy utilization rate of the system, reducing carbon dioxide and waste water emissions, and finally improving problems such as low atomic utilization rate of each logistics in the system, high energy consumption of carbon dioxide capture in the air, and low added value of downstream biomass products. At the same time, compared with traditional fuel oil technologies, it has the advantages of flexible and controllable production capacity scale and low operating cost. Methanol, propylene, and fuel oil can also be used as raw materials to produce other bulk chemicals, such as ethylene glycol, polypropylene, and higher carbon acids, ultimately improving the technical economy of large-scale and wide-range application of biomass in the production of bulk chemicals and the feasibility of industrial promotion of this technology.

[0058] In summary, compared with the prior art, the present invention has the following beneficial technical effects: The system and method for producing fuel oil from biomass via methanol provided by the present invention use renewable biomass as a raw material to obtain green electricity, and at the same time, the green electricity is used for electrolyzing water to obtain rich green hydrogen and green oxygen resources. The green hydrogen is used to adjust the proportion of the feed gas for the reaction of hydrogenating carbon dioxide produced by biomass gasification to methanol, reducing the carbon dioxide generated in the conversion unit of the traditional coal gasification process, and having a significant carbon reduction and emission reduction effect. At the same time, the waste heat generated by the units of carbon dioxide to methanol, methanol to propylene, and fuel oil synthesis unit 10 is recovered and used for the biomass power generation system. Compared with the traditional methanol to propylene process flow, for the mixed hydrocarbon product generated by the methanol to propylene unit 9 in the present invention, there is no need to separate olefins and paraffins, greatly reducing the investment cost and production cost. The technical, economic, social benefits and promotion application potential of the present invention are more significant.

[0059] The present invention is not limited to the above optional embodiments. Any person can obtain other various forms of products under the inspiration of the present invention. However, no matter what changes are made in its shape or structure, as long as the technical solutions fall within the scope defined by the claims of the present invention, they are all within the protection scope of the present invention.

Claims

1. A system for producing fuel oil from biomass via methanol, characterized in that: It includes a biomass power generation unit (1), a water electrolysis unit (3), a water gas shift reverse unit (6), a carbon dioxide hydrogenation to methanol unit (8), a methanol to propylene unit (9), a fuel oil synthesis unit (10), and a wastewater treatment unit (11); The biomass power generation unit (1) inputs biomass. The biomass power generation unit (1) supplies power to the water electrolysis unit (3). The carbon dioxide generated by the biomass power generation unit (1) is respectively supplied to the water gas shift reverse unit (6) and the carbon dioxide hydrogenation to methanol unit (8); the oxygen generated by the water electrolysis unit (3) is supplied to the biomass power generation unit (1); the hydrogen generated by the water electrolysis unit (3) is respectively supplied to the carbon dioxide hydrogenation to methanol unit (8) and the water gas shift reverse unit (6); the carbon monoxide generated by the water gas shift reverse unit (6) is respectively supplied to the biomass power generation unit (1) and the carbon dioxide hydrogenation to methanol unit (8); the methanol generated by the carbon dioxide hydrogenation to methanol unit (8) is respectively supplied to the methanol to propylene unit (9) and the fuel oil synthesis unit (10); the propylene generated by the methanol to propylene unit (9) is supplied to the fuel oil synthesis unit (10), and the fuel oil synthesis unit (10) synthesizes fuel oil; the preheating generated by the carbon dioxide hydrogenation to methanol unit (8), the methanol to propylene unit (9), and the fuel oil synthesis unit (10) is all supplied to the biomass power generation unit (1); the wastewater generated by the carbon dioxide hydrogenation to methanol unit (8) and the methanol to propylene unit (9) is sent to the wastewater treatment unit (11), and the pure water generated by the wastewater treatment unit (11) is respectively supplied to the water electrolysis unit (3) and the water gas shift reverse unit (6).

2. The system for producing fuel oil from biomass via methanol according to claim 1, characterized in that: It also includes a green power energy storage unit (2), a green oxygen collection unit (4), and a green hydrogen collection unit (5); the electric energy obtained by the biomass power generation unit (1) is sent to the green power energy storage unit (2) for storage, and the electric energy of the green power energy storage unit (2) is supplied to the water electrolysis unit (3); the green oxygen collection unit (4) is connected between the water electrolysis unit (3) and the biomass power generation unit (1), and the green hydrogen collection unit (5) is connected between the water electrolysis unit (3) and the carbon dioxide hydrogenation to methanol unit (8).

3. The system for producing fuel oil from biomass via methanol according to claim 1, characterized in that: Part of the carbon monoxide generated by the water gas shift reverse unit (6) is sold externally.

4. A method for producing fuel oil from biomass via methanol, using a system for producing fuel oil from biomass via methanol as described in claim 2, characterized in that: It includes the following steps: S1: Biomass raw materials, green oxygen from the oxygen collection unit, and carbon monoxide from the water gas shift reverse unit (6) enter the biomass power generation unit (1) for gasification reaction. The gasified gas drives an internal combustion engine or a steam turbine to generate electricity; the obtained green power is supplied to the water electrolysis unit (3) or sent to the green power energy storage unit (2) for storage; the tail gas including carbon dioxide generated after gasification and generated by the internal combustion engine and the steam turbine is sent to the carbon dioxide collection unit (7) for treatment; S2: The water electrolysis unit (3) electrolyzes pure water. The generated oxygen is sent to the biomass power generation unit (1), and the generated hydrogen is respectively sent to the green hydrogen collection unit (5) and the water gas shift reverse unit (6); S3: In the carbon dioxide collection unit (7), the tail gas including carbon dioxide generated after gasification and from the internal combustion engine and steam turbine is passed through a desulfurization tower to remove impurities including H2S; the carbon dioxide after impurity removal and the carbon monoxide from the outlet of the water gas reverse shift unit (6) enter the carbon dioxide hydrogenation to methanol unit (8) together; S4: In the water gas reverse shift unit (6), hydrogen from the green hydrogen collection unit (5) and carbon dioxide from the biomass power generation unit (1) react under the action of a nickel-based catalyst to generate carbon monoxide and water; after the reaction mixture is separated, a part of the carbon monoxide is sent to the biomass power generation unit (1), and the remaining carbon monoxide is sent to the carbon dioxide hydrogenation to methanol unit (8); S5: In the carbon dioxide hydrogenation to methanol unit (8), carbon dioxide from the carbon dioxide collection unit (7) and carbon monoxide from the water gas reverse shift unit (6) undergo a catalytic reaction under the action of a carbon dioxide hydrogenation catalyst to generate a mixed material mainly composed of methanol and water; the heat of the high-temperature methanol gas in the carbon dioxide hydrogenation to methanol unit (8) is supplied to the biomass power generation unit (1) through heat exchange, the methanol product is sent to the methanol to propylene unit (9), and the wastewater is discharged to the wastewater treatment unit (11); S6: In the methanol to propylene unit (9), the refined methanol from the carbon dioxide hydrogenation to methanol unit (8) enters the dimethyl ether reactor and generates dimethyl ether and water under the action of an alumina or molecular sieve catalyst; the mixed gas of dimethyl ether, water and unreacted methanol generated by the reaction and the water vapor from the outside, ethylene, ethane, butene and C5+ olefins, butane and C5+ alkanes separated from the methanol to propylene reaction product enter the methanol to propylene reactor in proportion, and the reaction raw materials generate hydrocarbons mainly composed of ethylene, propylene and isobutene in the methanol to propylene reactor; after heat exchange with the raw material gas of the methanol to propylene reactor and low-temperature steam, the heat is sent to the biomass power generation unit (1), the heavy component product including propylene at the bottom of the distillation column is pressurized and sent to the tank farm for storage or sent to the downstream fuel oil synthesis unit (10), and the wastewater is sent to the wastewater treatment unit (11); S7: In the fuel oil synthesis unit (10), propylene from the methanol-to-propylene unit (9) reacts under the action of a strong acid catalyst to produce a C5-C mixed hydrocarbon product mainly composed of nonene and dodecene. After hydrorefining to remove unsaturated hydrocarbons, the required fuel oil product is obtained. The waste heat of the fuel oil synthesis unit (10) is supplied to the biomass power generation unit (1); 22 The waste heat of the fuel oil synthesis unit (10) is supplied to the biomass power generation unit (1); S8: In the wastewater treatment unit (11), the wastewater is first stripped by steam to remove volatile organic components, then passed through an adjustment tank and coagulation sedimentation to remove large particles, suspended solids and part of the organic matter, and finally the residual pollutants in the wastewater are removed and the water quality is improved by microbial metabolism or adsorbent filtration. The purified water after treatment is sent to the electrolytic water unit (3) as the raw water for electrolytic water.

5. A method for producing fuel oil from biomass via methanol according to claim 4, characterized in that: In step S1, the equivalent ratio of oxygen to biomass raw material fed into the gasifier of the biomass power generation unit (1) is 0.1 - 0.4:1, the gasifier temperature is controlled at 300 - 800 °C, and the pressure in the gasifier is controlled at 0.1 - 0.8 Mpa for gasification reaction; the combustible gas including H2, CO, CO2 and CH4 after gasification is purified and then drives an internal combustion engine or steam turbine to generate electricity, and part of the green electricity obtained is sent to the green electricity energy storage unit (2) for storage. The green electricity energy storage unit (2) is converted into battery power or used for water energy storage in the reservoir for standby power generation.

6. A method for producing fuel oil from biomass via methanol according to claim 4, characterized in that: In step S3, the desulfurizer in the desulfurization tower is saturated sodium bicarbonate solution or solid sodium bicarbonate, and the temperature of the desulfurization tower is controlled at 150 - 450 °C; the desulfurized carbon dioxide, the carbon monoxide from the outlet of the water gas reverse shift unit (6), and the hydrogen from the green hydrogen collection unit (5) enter the carbon dioxide hydrogenation to methanol unit (8) together, and the gas ratio fed into the carbon dioxide hydrogenation to methanol unit (8) is controlled, CO:H2 = 1:2 - 2.1, CO2:H2 = 1:3 - 3.

1.

7. A method for producing fuel oil from biomass via methanol according to claim 4, characterized in that: In step S5, after CO2, CO, and H2 are preheated to 220 - 350 °C and pressurized to 1 - 8 MPa, a catalytic reaction occurs under the action of a carbon dioxide hydrogenation catalyst to generate a mixed material mainly composed of methanol and water; the high-temperature gas containing methanol at the reactor outlet is used as the heating source of the gas-gas heat exchanger, and then the methanol-containing mixed gas is cooled to 40 °C by a water cooler and enters a gas-liquid separator. The gas phase is returned to the recycle gas compressor to be pressurized as recycle gas; The liquid phase enters a flash tank. The flow rate of the crude methanol out of the flash tank is 85 kg / h, the temperature is 40 °C, and the pressure is 0.4 MPa, which is sent to the middle part of the methanol pre-distillation column. The components at the top of the methanol pre-distillation column are condensed by a condenser, and the condensate is returned to the methanol pre-distillation column; The non-condensable gas at the top of the methanol pre-distillation column is sent to the carbon dioxide collection unit (7) for unified treatment; the methanol coming out from the bottom of the methanol pre-distillation column enters the middle part of the methanol distillation column. The components at the top of the column are condensed by a condenser. Part of the condensate is returned to the distillation column, and part of the methanol is sent as a product to the methanol to propylene unit (9); the bottom of the column is water, which is discharged from the bottom to the wastewater treatment unit (11).

8. A method for producing fuel oil from biomass via methanol according to claim 4, characterized in that: In step S6, the refined methanol from the carbon dioxide hydrogenation to methanol unit (8) first undergoes vaporization and is preheated to 240 - 350 °C, and then enters a dimethyl ether reactor under the condition of controlling the pressure below 0.5 Mpa at normal pressure. Under the action of an alumina or molecular sieve catalyst, dimethyl ether and water are generated.

9. A method for producing fuel oil from biomass via methanol according to claim 8, characterized in that: In step S6, the mixed gas of dimethyl ether and water generated by the reaction and the unreacted methanol, together with the steam from the outside, the ethylene, ethane, butene, C5+ olefins, butane, and C5+ alkanes separated from the methanol to propylene reaction products, enter the methanol to propylene reactor in proportion; the catalyst used for the methanol to propylene reaction is a ZSM-5 or SAPO-34 molecular sieve catalyst. The reaction conditions for the methanol to propylene reaction are controlled at 370 - 490 °C and below 0.5 Mpa at normal pressure. The reaction raw materials generate various hydrocarbons mainly composed of ethylene, propylene, and isobutene in the methanol to propylene reactor; after heat exchange with the raw material gas of the methanol to propylene reactor and low-temperature steam.

10. A method for producing fuel oil from biomass via methanol according to claim 9, characterized in that: In step S6, after heat recovery, the flashed vapor-liquid separation is carried out. The gaseous mixed hydrocarbons are sent to the separation unit, compressed to 1.2 MPa and then sent to the water washing process to remove unreacted methanol and ethanol. After separation, they are sent to the stripping column and stripped with steam and then returned to the MTP reaction system for recycling. The material after water washing is sent to the dehydration and decarbonization column, and an adsorbent is used to adsorb and remove CO2 and H2O in the gas phase. Then the remaining gaseous mixed hydrocarbons are compressed to 2.1 MPa and sent to the distillation column to remove the non-condensable gas including CO and methane. The non-condensable gas is sent to the carbon dioxide collection unit (7) for unified treatment. The heavy component product including propylene at the bottom of the distillation column is pressurized and sent to the tank farm for storage or sent to the downstream fuel oil synthesis unit (10); the liquid phase obtained from the flashed vapor-liquid separation is wastewater containing organic matter. After steam stripping and vaporization, part of it is sent to the electrolyzed water unit (3), and part of it is vaporized and sent to the methanol-to-propylene reaction unit for its own use.

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