Method and system for efficiently preparing oil product by taking biomass as raw material

Abstract

The invention provides the method and the system for efficiently preparing the oil product by taking the biomass as the raw material, and by adopting the scheme of the invention, the problem that the feeding is difficult in the process that the biomass enters a gasification furnace to be gasified can be solved, and the oil product can be produced with relatively high carbon utilization efficiency. The method comprises the following steps: (1) feeding a biomass raw material with the water content of 5-40wt% into a gasification furnace, firstly feeding the biomass raw material into a first gasification section of the gasification furnace for gasification reaction, and then feeding a gasification product obtained in the first gasification section into a second gasification section of the gasification furnace for continuous reaction to obtain crude synthesis gas; (2) purifying the crude synthesis gas; carbon dioxide in the purified synthesis gas is removed; circulating the carbon dioxide to the first gasification section; and (3) carrying out hydrogen-carbon ratio adjustment on the decarburized synthesis gas, feeding the decarburized synthesis gas into a Fischer-Tropsch synthesis unit, carrying out Fischer-Tropsch synthesis reaction to obtain a Fischer-Tropsch synthesis product, and carrying out post-treatment on the Fischer-Tropsch synthesis product to obtain an oil product.

Description

Technical Field

[0001] The present invention relates to the technical field of preparing oil products using biomass as raw materials, and in particular to a method and system for efficiently preparing oil products using biomass as raw materials. Background Art

[0002] Using biomass as a feedstock to couple green hydrogen to produce green fuels such as diesel and jet fuel is a current research hotspot. Patent application CN101845319A gasifies biomass, then processes it through tar reforming, gas purification, and syngas reforming before Fischer-Tropsch synthesis. Product separation and refining yield wax and clean fuel oil. However, this solution fails to fully convert tar and aromatics through tar reforming, requiring further oil elution to remove the tar and aromatics, resulting in low reforming efficiency. Furthermore, the waste gas and wastewater generated by gas purification and Fischer-Tropsch synthesis are not effectively utilized, resulting in low biomass carbon conversion efficiency. Patent application CN107557075A synthesizes oil products through the steps of biomass pressurized gasification, synthesis gas purification, oil product synthesis, exhaust gas decarbonization, exhaust gas oil washing, exhaust gas reforming, exhaust gas hydrogen production, oil product processing and exhaust gas desulfurization; although the biomass carbon conversion efficiency of this scheme is improved, the combustion of exhaust gas will generate a large amount of CO2, which does not meet the goal of green carbon reduction; wastewater also needs to be treated to meet the requirements before it can be discharged, and the cost of wastewater treatment is high; this scheme adjusts the hydrogen-carbon ratio through the water-gas shift reaction, which will face the problem of generating a large amount of CO2 that cannot be used. Patent application CN101848979A first gasifies biomass to obtain crude syngas, then purifies the crude syngas and adjusts the hydrogen-to-carbon ratio through processes such as catalytic reforming and a water-gas shift reaction. The purified syngas undergoes a Fischer-Tropsch synthesis reaction to produce liquid hydrocarbons. This scheme converts tar and methane into hydrogen and carbon monoxide through catalytic reforming. However, since tar contains toxic substances such as sulfur, chlorine, and potassium, the catalyst is easily poisoned. Furthermore, the water-gas shift reaction is used to adjust the hydrogen-to-carbon ratio of the syngas, which generates a large amount of CO2 and does not meet the goal of green carbon reduction. Patent application CN107573962A obtains crude syngas with a hydrogen-to-carbon ratio of 0.5-1.7 through biomass gasification. It then undergoes filtration, tar reforming, and hydrogen adjustment through a Fischer-Tropsch tail gas water-gas shift reaction to obtain clean syngas with a hydrogen-to-carbon ratio of approximately 2. Finally, hydrocarbons are obtained through Fischer-Tropsch synthesis.

[0003] Patent application CN113337317A obtains crude synthesis gas through biomass gasification. The crude synthesis gas is cooled and purified, and the impurities are removed by water-gas shift reaction to obtain Fischer-Tropsch synthesis feed gas. Fischer-Tropsch synthesis is then carried out to obtain Fischer-Tropsch gaseous hydrocarbons (C1-C4), liquid and solid hydrocarbons, and water. The Fischer-Tropsch gaseous hydrocarbons are separated by decarbonization to obtain hydrogen that is returned to the Fischer-Tropsch synthesis reaction unit. The Fischer-Tropsch water is separated to obtain oxygen compounds, and the liquid-based solid hydrocarbons are hydrogenated to obtain biodiesel. This solution adjusts the hydrogen-carbon ratio through the water-gas shift reaction, facing the problem of generating a large amount of CO2 that cannot be utilized; at the same time, water washing is required to purify the synthesis gas, which will produce a large amount of wastewater. This solution treats the wastewater generated by the Fischer-Tropsch synthesis to obtain oxygenated organic compounds, but there is no way to utilize the wastewater after removing the oxygenated organic compounds.

[0004] Overall, the existing biomass-based green fuel technology faces the following problems: the system's carbon utilization rate is low; the post-processing and purification of the generated tar and crude synthesis gas require cumbersome and costly treatment routes, which can easily cause secondary pollution; the large amount of CO2 removed by the purification of the crude synthesis gas, as well as the large amount of CO2 generated when the hydrogen-carbon ratio of the synthesis gas is adjusted by the water-gas shift reaction, are both released into the atmosphere and then absorbed by biomass. This path can only achieve zero CO2 emissions and cannot achieve the carbon reduction target. Summary of the Invention

[0005] The present invention provides a method and system for efficiently preparing oil products using biomass as raw material. The solution of the present invention can not only overcome the difficult problem of feeding biomass into a gasifier for gasification, but also produce oil products with higher carbon utilization efficiency.

[0006] To achieve its purpose, the present invention provides the following technical solutions:

[0007] In one aspect, the present invention provides a method for efficiently preparing oil products using biomass as raw material, the method comprising the following steps:

[0008] (1) A biomass feedstock with a moisture content of 5-40 wt% is fed into a gasifier, first entering the first gasification section of the gasifier for gasification reaction, and then the gasification product obtained in the first gasification section enters the second gasification section of the gasifier for further reaction to obtain a crude synthesis gas; wherein the gasification temperature of the first gasification section is 650-850°C, and the temperature of the second gasification section is 900-1200°C; the pressure of the gasifier is -0.1 MPa to 0.1 MPa, and the gasifier is a fluidized bed gasifier;

[0009] (2) Purifying the crude synthesis gas obtained in step (1) to obtain purified synthesis gas; removing carbon dioxide from the purified synthesis gas to obtain decarbonized synthesis gas and carbon dioxide; and recycling the carbon dioxide to the first gasification section;

[0010] (3) The decarbonized synthesis gas obtained in step (2) is fed into a Fischer-Tropsch synthesis unit after adjusting the hydrogen-carbon ratio, and a Fischer-Tropsch synthesis product is obtained by a Fischer-Tropsch synthesis reaction, and the Fischer-Tropsch synthesis product is post-processed to obtain an oil product.

[0011] Another aspect of the present invention provides a system for efficiently preparing oil products using biomass as raw material, the system comprising:

[0012] A gasifier, wherein the gasification section of the gasifier comprises a first gasification section and a second gasification section, wherein the first gasification section is used to perform a first-stage gasification reaction on biomass, and the second gasification section is used to subject the gasification product obtained in the first gasification section to a second-stage gasification reaction to obtain crude synthesis gas; preferably, the gasifier is a fluidized bed gasifier;

[0013] a syngas purification unit, the syngas purification unit being used to purify the raw syngas obtained from the gasifier to obtain purified syngas;

[0014] a decarbonization unit for removing carbon dioxide from the purified syngas to obtain decarbonized syngas and carbon dioxide; the decarbonization unit is connected to the first gasification section of the gasifier to circulate the carbon dioxide obtained in the decarbonization unit to the first gasification section;

[0015] a hydrogen-to-carbon ratio adjustment unit, configured to receive the decarbonized synthesis gas obtained by the decarbonization unit and mix it with hydrogen to adjust the hydrogen-to-carbon ratio of the decarbonized synthesis gas; preferably, the hydrogen is green hydrogen;

[0016] a Fischer-Tropsch synthesis unit connected to the hydrogen-to-carbon ratio adjustment unit, configured to subject the decarbonized synthesis gas, after hydrogen-to-carbon ratio adjustment, to a Fischer-Tropsch synthesis reaction to obtain a Fischer-Tropsch synthesis product;

[0017] A post-processing unit is used to post-process the Fischer-Tropsch synthesis product to obtain an oil product.

[0018] The technical solution provided by the present invention has the following beneficial effects:

[0019] In the method of the present invention, a fluidized bed gasifier at atmospheric pressure, slightly positive pressure, or slightly negative pressure between -0.1 MPa and 0.1 MPa is used to gasify the biomass feedstock, with the moisture content of the biomass feedstock being between 5 and 40 wt%. Two gasification processes at different temperatures are performed, and carbon dioxide removed from the syngas downstream is returned to the first gasification stage to participate in the reaction. The method of the present invention: 1) the biomass feedstock can be smoothly fed into the fluidized bed gasifier without complicated pretreatment, and biomass drying can be omitted; 2) it is less likely to corrode the gasifier; 3) a crude syngas with a low tar content can be obtained; 4) carbon dioxide is recycled to the gasifier and can undergo a reforming reaction with the methane therein, effectively improving carbon utilization; 5) biomass containing a certain amount of moisture is used for two-stage gasification in the gasifier, which prolongs the residence time of the biomass in the gasifier, facilitates the production of syngas with a low tar content, increases the ratio of H2 to CO in the syngas, and saves the amount of subsequent hydrogen replenishment. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of a system for efficiently preparing oil wax products using biomass as raw material in one embodiment. DETAILED DESCRIPTION

[0021] In order to facilitate the understanding of the present invention, the present invention will be further described below in conjunction with examples. It should be understood that the following examples are only for a better understanding of the present invention and do not mean that the present invention is limited to the following examples.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention pertains. The term "and / or" as may be used herein includes any and all combinations of one or more of the associated listed items.

[0023] Where specific experimental steps or conditions are not specified in the examples, the corresponding conventional experimental steps or conditions in the art can be followed. Reagents or instruments used without specifying the manufacturer are all conventional products that can be purchased commercially or obtained through existing technology.

[0024] The terms "first," "second," "third," etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance.

[0025] The present invention provides a method for efficiently preparing oil products using biomass as raw material, the method mainly comprising the following steps:

[0026] (1) A biomass feedstock with a moisture content of 5-40 wt% (e.g., 5 wt%, 8 wt%, 10 wt%, 20 wt%, 30 wt%, 40 wt%, etc.) is fed into a gasifier, first entering the first gasification section of the gasifier for gasification reaction, and then the gasification product obtained in the first gasification section enters the second gasification section of the gasifier for further reaction to obtain a crude synthesis gas; wherein the gasification temperature of the first gasification section is 650-850°C (e.g., 650°C, 700°C, 750°C, 800°C, 850°C, etc.), and the temperature of the second gasification section is 900-1200°C (e.g., 900°C, 1000°C, 1100°C, 1200°C, etc.); the pressure of the gasifier is -0.1 MPa to 0.1 MPa (e.g., -0.1, 0, 0.1 MPa, etc.), that is, it can be normal pressure, slightly positive pressure, or slightly negative pressure, and the gasifier is a fluidized bed gasifier;

[0027] (2) Purifying the crude synthesis gas obtained in step (1) to obtain purified synthesis gas; removing carbon dioxide from the purified synthesis gas to obtain decarbonized synthesis gas and carbon dioxide; and recycling the carbon dioxide to the first gasification section;

[0028] (3) The decarbonized synthesis gas obtained in step (2) is fed into a Fischer-Tropsch synthesis unit after adjusting the hydrogen-carbon ratio, and a Fischer-Tropsch synthesis product is obtained by a Fischer-Tropsch synthesis reaction, and the Fischer-Tropsch synthesis product is post-treated to obtain the oil product.

[0029] After long-term research, the inventors found that it is difficult to directly apply the gasification technology applicable to coal to the gasification of biomass. The conventional gasifiers are mostly high-pressure fluidized bed or fixed bed gasifiers, and the biomass raw materials have the problem of difficulty in feeding during the feeding process. Using a conventional fixed bed gasifier, although the biomass can contain a certain amount of moisture, the biomass raw materials need to be fed in batches, the feeding efficiency is low, and a large amount of tar and wastewater are produced, and the methane gas content in the generated gas is high. Using conventional high-pressure fluidized bed gasification technology, the biomass must first be dried, pyrolyzed to remove the volatile matter in the biomass raw materials, and then ground into powder before entering the gasifier, resulting in high material production costs. Moreover, when gasifying commonly used biomass such as straw and other low-density biomass raw materials, compared with conventional coal gasification raw material pulverized coal, these biomass raw materials are very easy to be blown out, making it difficult for the process to proceed smoothly. In addition, when using traditional gasification technology for biomass gasification, corrosion of the gasifier outlet furnace body is prone to occur, leading to leakage, etc.

[0030] After extensive research, the inventors have developed a method particularly suitable for efficiently producing oil products from biomass feedstock through processes such as gasification. In this method, the biomass feedstock is gasified using a fluidized bed gasifier operating at atmospheric pressure, slightly positive pressure, or slightly negative pressure. The biomass feedstock is ensured to contain a certain amount of moisture, rather than being dry, with the moisture content controlled between 5-40 wt%. The gasifier also performs two gasification processes at different temperatures in the gasification section: in the first gasification section, gasification is performed at a relatively low temperature, controlled at 650-850°C; in the second gasification section, gasification is performed at a relatively higher temperature, controlled at 900-1200°C. Carbon dioxide removed from the synthesis gas downstream is returned to the first gasification section to participate in the reaction. In the process of the present invention, a fluidized bed gasifier with normal pressure, slight positive pressure or slight negative pressure is used. The biomass raw materials can be smoothly fed into the fluidized bed gasifier without complicated pretreatment, and the raw materials can be directly fed with a moisture content of 5-40wt%. The original moisture content of most biomass is almost within this moisture range, and the drying process of the biomass can be omitted. The process of the present invention can be applied to biomass with relatively low density, such as straw, or biomass with relatively high density, such as sawdust or rice husk, without obstacles such as feeding difficulties. Furthermore, the inventors found that the biomass is first gasified at a temperature of 650-850°C, and the resulting product gas is further reacted at 900-1200°C. On the one hand, the alkali metal has not yet reached a molten state at low temperature, and is less corrosive to the gasifier. The alkali metal in the biomass in the low temperature section is discharged out of the furnace together with the residue, for example, from the slag outlet below the first gasification section, to avoid corrosion to the furnace. On the other hand, the crude synthesis gas containing tar, carbon dioxide, methane and other alkanes obtained in the first gasification section continues to enter the second gasification section to continue reacting at 900-1200°C, and undergoes a non-catalytic partial oxidation reaction (without the use of a catalyst), which can realize the conversion of tar, alkanes, etc. into the effective gases CO and H2 required by the downstream Fischer-Tropsch synthesis unit, and obtain a crude synthesis gas with a low tar content; and through the specific two-stage gasification of the present invention, a crude synthesis gas with a very low tar content is obtained, so there is no need to wash and purify the crude synthesis gas, which greatly reduces the amount of wastewater generated in the entire process. On the other hand, the carbon dioxide removed from the crude synthesis gas is returned to the gasifier, and the carbon dioxide will undergo a reforming reaction with the methane produced in the gasifier, effectively improving the carbon utilization rate. However, in the existing technology, carbon dioxide and methane are rarely removed when gasifying biomass. According to the understanding of traditional processes, removing these gases will reduce the carbon conversion rate of the system. However, if these gases are not removed, the conversion efficiency and catalyst performance of the Fischer-Tropsch synthesis unit will be inhibited in the future. In addition, methane and carbon dioxide do not participate in the reaction in the system, resulting in a lower carbon utilization rate of the system.On the other hand, the inventors have found that by using biomass containing 5-40wt% moisture to carry out two-stage gasification in a gasifier according to the process of the present invention, this water-containing biomass can increase the biomass density and have a longer residence time in the gasifier. The inventors also found that compared with biomass with too low moisture content, the moisture contained therein directly participates in the gasification reaction. Through the two-stage gasification process of the present invention, a synthesis gas with a lower tar content can be obtained, and it is beneficial to increase the ratio of H2 to CO in the synthesis gas, save the amount of subsequent hydrogen replenishment, and improve the economic efficiency of the technology.

[0031] In a preferred embodiment, in step (1), the moisture content of the biomass feedstock is 10-40 wt%, for example, 10-35%, for example, 10-25 wt%. The present inventors have found that using a biomass feedstock with a preferred moisture content in the process of the present invention can, on the one hand, significantly improve the carbon utilization rate of the system and help increase the ratio of H2 to CO in the synthesis gas, and on the other hand, avoid the generation of a large amount of wastewater after gasification due to excessive water content.

[0032] The method of the present invention uses biomass containing a certain amount of moisture as feedstock for gasification in a gasifier. Compared to traditional processes, this method can eliminate the need for drying. Even for biomass feedstock with an initial high moisture content, the required drying process is significantly simplified. Overall, the method of the present invention eliminates the need for complex pretreatment of the biomass feedstock; for example, simple crushing is sufficient for use.

[0033] In a preferred embodiment, the Fischer-Tropsch synthesis tail gas generated in the Fischer-Tropsch synthesis reaction in step (3) is recycled to the first-stage gasifier, which is beneficial to further improve the carbon utilization rate.

[0034] In a preferred embodiment, the wastewater and / or saturated water vapor generated in the Fischer-Tropsch synthesis reaction is recycled into the first gasification section as a gasifying agent and continues to be used as a gasifying agent, thereby achieving "zero discharge" of wastewater and reducing treatment costs.

[0035] In a preferred embodiment, the purge gas generated in the Fischer-Tropsch synthesis unit is recycled to the second gasification section, which helps to further improve the carbon utilization rate.

[0036] Specifically, in the gasification unit, the gasifying agent used is mainly oxygen, and the carrier is water vapor and / or carbon dioxide; in some embodiments, the gasifying agent may be mixed with water vapor and / or carbon dioxide, that is, it is mainly a mixture of oxygen, water vapor and carbon dioxide.

[0037] Preferably, in step (3), the hydrogen (i.e., green hydrogen) obtained by water electrolysis is mixed with the decarbonized synthesis gas to adjust the hydrogen-carbon ratio; the green hydrogen is provided by water electrolysis to adjust the hydrogen-carbon ratio of the synthesis gas, thereby avoiding the problem of a large amount of CO2 as a by-product of the water-gas shift reaction and also avoiding the problem of a cumbersome tail gas reforming hydrogen production route.

[0038] Preferably, in step (3), the hydrogen-carbon ratio of the decarbonized synthesis gas is adjusted to 1.9-2.15, and then the synthesis gas enters the Fischer-Tropsch synthesis unit for Fischer-Tropsch synthesis reaction.

[0039] In the present invention, the Fischer-Tropsch synthesis unit can use a Fischer-Tropsch synthesis catalyst commonly used in the art to carry out the Fischer-Tropsch synthesis reaction. In a preferred embodiment, the catalyst used in the Fischer-Tropsch synthesis unit is a cobalt-based catalyst. Preferably, the cobalt-based catalyst includes a carrier and an active component cobalt supported on the carrier, and the carrier includes one or more of titanium oxide, silicon oxide and zirconium oxide. In some embodiments, the carrier includes at least titanium oxide; in some embodiments, the carrier includes at least titanium oxide and zirconium oxide. In some embodiments, based on the total weight of the cobalt-based catalyst, the content of the active component metal cobalt is 10-50%, and the content of the carrier is 50-90%. The cobalt-based catalyst used is preferably the titanium oxide-supported cobalt-based Fischer-Tropsch synthesis catalyst in Chinese patent CN111905740B, which is incorporated into the present application by reference as a whole. Specifically, the titanium oxide-supported cobalt-based Fischer-Tropsch synthesis catalyst provided in CN111905740B or the titanium oxide-supported cobalt-based Fischer-Tropsch synthesis catalyst prepared based on the preparation method in the patent can be preferably used as the catalyst required in the Fischer-Tropsch synthesis unit of the present invention. For the specific composition and preparation method of the preferred cobalt-based catalyst, please refer to the records in CN111905740B. The inventors have discovered that the use of a cobalt-based catalyst, particularly the cobalt-based Fischer-Tropsch synthesis catalyst provided by CN111905740B, can produce high-value-added wax products (e.g., wax products above C25) in high yields while exhibiting low selectivity for by-products such as methane gas. By using this catalyst for Fischer-Tropsch synthesis, the resulting high-value-added wax products can be sold as high-value-added products after simple separation; while the low-value-added oil-wax products can be used to produce white oil, green diesel, green aviation kerosene, and other oil products in high yields through downstream hydrocracking / isomerization technology.

[0040] Preferably, the Fischer-Tropsch synthesis unit is carried out in a fixed-bed reactor, preferably a shell-and-tube fixed-bed reactor. The reaction temperature for the Fischer-Tropsch synthesis reaction is preferably 200-250°C, and the pressure is preferably 1.5-5 MPa. Using the preferred cobalt-based catalyst in a fixed-bed reactor provides enhanced results, eliminating the need for multiple reactors in series, requiring only a single reactor.

[0041] Specifically, in step (2), the crude synthesis gas obtained in step (1) is purified, specifically including detarring, desulfurization, deoxidation, decarbonylation and dehydration of the crude synthesis gas. These purification treatments can be carried out using conventional process technologies well known in the art, and there are no special restrictions on this. For example, detarring can use activated carbon commonly used in industry, deoxidation can use conventional iron oxide deoxidizers, and desulfurization can use zinc oxide and / or copper oxide deoxidizers.

[0042] Specifically, in step (2), the operation of removing carbon dioxide from the purified synthesis gas can be carried out using conventional carbon dioxide removal technology in the art, such as using MDEA to remove CO2 from the synthesis gas.

[0043] In some embodiments, in step (3), the post-processing of the Fischer-Tropsch synthesis product (including liquid and solid hydrocarbons, etc.) specifically includes: separating the Fischer-Tropsch synthesis product to obtain an oil wax component, water and tail gas, or obtaining solid crude wax, an oil component from which the solid crude wax is separated, water and tail gas, sending the separated oil wax component or the oil component to a hydrogenation unit for hydrocracking and isomerization, and separating the product obtained from the hydrogenation unit to obtain white oil and / or fuel oil products; specifically, the fuel oil products include, for example, one or more of a diesel fraction, an aviation kerosene fraction, and a gasoline fraction. Specifically, in the present invention, when the Fischer-Tropsch synthesis product is separated, all of the oil wax components can be sent to a downstream hydrogenation unit; or the solid crude wax therein can be separated, and the remaining oil component can be sent to a downstream hydrogenation unit, and optionally, part or all of the separated solid crude wax can also be sent to a downstream hydrogenation unit together; in actual applications, those skilled in the art can make a selection as needed. In the hydrogenation unit, those skilled in the art can adjust the yield of various oil products obtained by adjusting the hydrogenation catalyst and process, such as adjusting the yield of green diesel and green aviation kerosene. The hydrocracking and isomerization of the Fischer-Tropsch synthesis product can be carried out using conventional techniques in the art, and there are no particular restrictions on this. In some embodiments, the hydrogenation unit specifically includes a hydrocracking reactor and an isomerization reactor connected in series, and the catalyst loaded can be a catalyst with corresponding catalytic effect known in the art. For example, the hydrocracking reactor is loaded with a nickel-tungsten catalyst, and the carrier is two or three of a molecular sieve, alumina and an amorphous silicon-aluminum composite oxide, and the molecular sieve is preferably a Y molecular sieve or a β molecular sieve; for example, in some embodiments, the nickel-tungsten catalyst used has a total mass content of WO3 and NiO of 20% to 50%, a W / Ni atomic ratio of 0.1 to 0.5, amorphous silicon-aluminum content of 40wt% to 79wt%, and a molecular sieve content of 1wt% to 10wt%. For example, the isomerization reactor is loaded with a platinum-based catalyst, and the carrier is ZSM-48 or ZSM-22.

[0044] In some embodiments, the following steps are optionally included: separating part or all of the solid crude wax separated from the Fischer-Tropsch synthesis product to obtain wax products with different melting points; and after separating the solid crude wax, the rest of the wax except for the high-value wax products (e.g., high melting point wax, such as wax products above C25) is sent to a hydrogenation unit for treatment.

[0045] The method of the present invention, through the gasification process of a two-stage gasifier, performs a two-stage gasification process according to specific pressure and temperature requirements, and can ultimately obtain a crude synthesis gas with a low tar content (for example, as low as ppm level), thereby reducing the cost of tar treatment, eliminating the need for an additional tar reforming process, and avoiding the corrosion of the gasifier that is easily caused by biomass gasification. The use of aqueous biomass feed for gasification and the recycling of carbon dioxide in the gasification stage can significantly improve the carbon utilization rate and help improve the hydrogen-carbon ratio in the synthesis gas. In the method of the present invention, the recycling of waste gas and waste water is conducive to achieving zero emissions. The present invention can greatly improve the biomass carbon conversion rate through the organic combination of reasonable process route settings and the overall process system.

[0046] In the present invention, biomass includes, for example, wood chips, cotton stalks, straw, rice husks, etc. The biomass is crushed into rods or fragments of less than 30 mm.

[0047] The present invention also provides a system for efficiently preparing oil products using biomass as raw material, which can implement the above method. Figure 1 The system mainly includes a gasifier, a synthesis gas purification unit, a decarbonization unit, a hydrogen-carbon ratio adjustment unit, a Fischer-Tropsch synthesis unit and a post-processing unit.

[0048] Among them, the gasification section of the gasifier includes a first gasification section and a second gasification section. The first gasification section is used to perform a first-stage gasification reaction on the biomass, and the second gasification section is used to perform a second-stage gasification reaction on the gasification product obtained in the first gasification section (i.e., the crude synthesis gas obtained by the reaction in the first gasification section) and obtain crude synthesis gas; preferably, the gasifier is a fluidized bed gasifier.

[0049] The synthesis gas purification unit is used to purify the crude synthesis gas obtained from the gasification furnace to obtain purified synthesis gas. Specifically, for example, it is used to detar, desulfurize, deoxygenate, decarbonylate and dehydrate the crude synthesis gas. The crude synthesis gas can be subjected to the above-mentioned detarring, desulfurization, deoxygenation, decarbonylation and dehydration treatments using process methods and equipment known in the art, and there is no particular limitation on this.

[0050] The decarbonization unit is used to remove carbon dioxide from the purified syngas, producing decarbonized syngas and carbon dioxide. The decarbonization unit is connected to the first gasification stage of the gasifier to circulate the carbon dioxide obtained in the decarbonization unit to the first gasification stage to participate in the reaction. The decarbonization unit can specifically remove carbon dioxide from the purified syngas using devices and methods known in the art, such as MDEA, which is well known in the art.

[0051] The hydrogen-carbon ratio adjustment unit is used to receive the decarbonized synthesis gas obtained by the decarbonization unit and mix it with hydrogen, thereby adjusting the hydrogen-carbon ratio in the decarbonized synthesis gas, wherein the hydrogen is preferably green hydrogen;

[0052] The Fischer-Tropsch synthesis unit is connected to the hydrogen-carbon ratio adjustment unit and is used to subject the decarbonized synthesis gas after the hydrogen-carbon ratio is adjusted to a Fischer-Tropsch synthesis reaction to obtain a Fischer-Tropsch synthesis product;

[0053] A post-processing unit is used to post-process the Fischer-Tropsch synthesis product to obtain an oil product.

[0054] Further specifically, the post-processing unit includes a first separation unit for separating the Fischer-Tropsch synthesis product to obtain an oil-wax component, water and tail gas, or to obtain a solid crude wax, an oil component from which the solid crude wax is separated, water and tail gas; for example, the separation of solid wax, oil and water is achieved by a gas-liquid separation tank, and the oil component remaining in the solid wax is cut out by atmospheric and vacuum separation to thereby obtain a solid crude wax (for example, a wax product above C25). Further specifically, the post-processing unit also includes a hydrogenation unit for hydrocracking and isomerizing the oil-wax component or the oil component separated in the first separation unit to obtain a hydrocracked and isomerized product. In some embodiments, the hydrogenation unit is also used to hydroisomerize and crack some or all of the separated solid crude wax. Further specifically, the post-processing unit also includes a second separation unit for separating (for example, by atmospheric and vacuum separation) from the hydrocracking and isomerized product to obtain white oil and / or fuel oil products, such as green diesel, green aviation kerosene, gasoline, etc. In some embodiments, a wax cutting unit is further included for separating part or all of the solid crude wax separated in the first separation unit to obtain wax products with different melting points, such as high melting point wax. The specific separation process of the Fischer-Tropsch synthesis product in the post-processing unit can be carried out using the corresponding separation technology conventional in the art, and there is no particular limitation on this.

[0055] Preferably, the system also includes an electrolysis unit for electrolyzing water to produce green hydrogen. The electrolysis unit is connected to a hydrogen-to-carbon ratio adjustment unit to supply green hydrogen to the unit, which then mixes green hydrogen into the syngas to achieve the desired hydrogen-to-carbon ratio. Preferably, the electrolysis unit is also connected to a hydrogenation unit to supply the hydrogen required for hydrocracking and isomerization.

[0056] Preferably, the Fischer-Tropsch synthesis unit is connected to the second gasification section of the gasifier, so that the purge gas of the Fischer-Tropsch synthesis unit is circulated to the second gasification section for continued utilization.

[0057] Preferably, the Fischer-Tropsch synthesis unit is connected to the first gasification section of the gasifier, so that the saturated steam generated by the Fischer-Tropsch synthesis unit is circulated to the first gasification section of the gasifier for further utilization. Preferably, the first separation unit is connected to the first gasification section of the gasifier, so that the water and tail gas separated by the first separation unit are circulated to the first gasification section.

[0058] As used herein, “hydrogen-to-carbon ratio” refers to the molar ratio of hydrogen to carbon monoxide.

[0059] The specific devices in the system of the present invention can all be corresponding devices with corresponding functions or effects known in the art, and no detailed description is given here. Regarding the process of preparing oil wax products by biomass gasification and the like in the system of the present invention, reference can be made to the description of the method above, and no further description is given here.

[0060] The system and method of the present invention utilize biomass as a raw material to produce oil and wax products, achieving high carbon conversion and utilization rates. Carbon dioxide is recycled within the process system, eliminating the need for external exhaust and treatment. The process and system provided by the present invention comprehensively consider each process unit and related supporting processes, optimizing and rationally configuring the process from a holistic perspective to facilitate industrial application. This achieves efficient utilization of biomass as a new energy source, while shortening the required process flow.

[0061] For ease of understanding of the present invention, the present invention is further illustrated by the following examples, but it should not be understood that the present invention is limited thereto. The reagents (such as catalysts, etc.) used in the following examples and comparative examples are all existing reagents in the art.

[0062] Example 1

[0063] (1) Rice husks are used as biomass raw materials. 10 tons / h of biomass raw materials are mixed and then enter a slightly negative pressure biomass gasifier (a fluidized bed gasifier). The water content of the biomass is 15wt%. The biomass first enters the first gasification section of the gasifier. The gasification temperature of the first gasification section is 750°C. The crude synthesis gas obtained in the first gasification section enters the second gasification section of the gasifier to continue the reaction. The temperature of the second gasification section is 1000°C. The gasifying agents used in the gasifier are oxygen and water vapor. The volume ratio of oxygen to water vapor is 10:1. The carrier gas is carbon dioxide. The gas flow rate of the gasifier outlet gas after dehydration is 11220Nm 3 / h, the pressure is -0.05MPa, and the main components of the raw synthesis gas are (volume percentage): 49% H2, 48% CO, 1.3% CO2, 0.9% CH4, and 0.7% N2.

[0064] (2) The crude synthesis gas obtained by gasification is pressurized to 3.7 MPa by a compressor, and then detarred, desulfurized, deoxygenated, decarbonylated and dehydrated in a synthesis gas purification unit to obtain purified synthesis gas.

[0065] The purified synthesis gas is subjected to the decarbonization unit to remove CO2 to obtain decarbonized synthesis gas; the CO2 removed in the decarbonization unit is returned to the first gasification section of the gasifier.

[0066] (3) The decarbonized synthesis gas is mixed with 5273Nm 3 / h of green hydrogen with a purity of 99.9% (hydrogen produced by electrolyzing water in an electrolysis unit) is mixed in a hydrogen-to-carbon ratio adjustment unit to obtain synthesis gas with a hydrogen-to-carbon ratio of 2.0, which is then compressed to 3.5 MPa and enters the Fischer-Tropsch synthesis unit.

[0067] The Fischer-Tropsch synthesis reaction in the Fischer-Tropsch synthesis unit occurs at 220°C and 3.1 MPa. The catalyst used is Co / TiO2-ZrO2 (wherein the active component is metal Co, the carrier is TiO2 and ZrO2, the TiO2 content is 58wt%, and the ZrO2 content is 2wt%), and the reactor used is a shell-and-tube fixed bed reactor.

[0068] The Fischer-Tropsch synthesis product generated by the Fischer-Tropsch reaction enters the first separation unit for separation, yielding tail gas, water, solid wax, and Fischer-Tropsch oil. The solid wax and Fischer-Tropsch oil are then mixed and fed into a hydrogenation unit, which comprises two reactors in series. The first reactor is loaded with a nickel-tungsten catalyst supported by a Y molecular sieve and an amorphous silica-alumina composite oxide (the combined mass content of WO3 and NiO is 40%, the W / Ni atomic ratio is 0.3, the amorphous silica-alumina content is 55wt%, and the molecular sieve content is 5wt%). The reaction temperature is 330°C and the pressure is 8MPa. The second reactor is loaded with a platinum-based catalyst with a 1wt% platinum content and a ZSM-48 support. The reaction temperature is 280°C and the pressure is 5MPa. The wax oil product from the hydrogenation enters the second separation unit for atmospheric and vacuum separation, yielding 2.15 tons / h of green aviation kerosene components and 0.72 tons / h of green gasoline components.

[0069] During the process, the tail gas and water output from the first separation unit are circulated to the first gasification section of the gasifier in step (1), the purge gas generated in the Fischer-Tropsch synthesis unit is circulated to the second gasification section of the gasifier in step (1), and the saturated water vapor generated in the Fischer-Tropsch synthesis unit is circulated to the first gasification section of the gasifier in step (1).

[0070] In this example, the carbon content of the biomass feedstock is 40 wt%. The biomass feedstock is 10 tons per hour, of which the carbon content is 4 tons. The resulting jet fuel and gasoline product is 2.87 tons per hour, with a carbon content of 85.7 wt% and a carbon content of 2.46 tons. Therefore, the system's carbon utilization efficiency is 61.5%.

[0071] Example 2

[0072] (1) Rice husks are used as biomass raw materials. 10 tons / h of biomass raw materials are mixed and then enter a micro-positive pressure biomass gasifier (a fluidized bed gasifier). The water content of the biomass is 5wt%. The biomass first enters the first gasification section of the gasifier. The gasification temperature of the first gasification section is 800°C. The crude synthesis gas obtained in the first gasification section enters the second gasification section of the gasifier to continue the reaction. The temperature of the second gasification section is 1000°C. The gasifying agents used in the gasifier are pure oxygen and water vapor. The volume ratio of oxygen to water vapor is 10:1. The carrier gas is carbon dioxide. The gas flow rate of the gasifier outlet gas after dehydration is 9240Nm 3 / h, the pressure is 0.01MPa, and the composition of the crude synthesis gas is (volume percentage): 43% H2, 51% CO, 4% CO2, 0.3% CH4, 0.7% N2, and the concentration of other gases (mainly ethane, propane, argon, and a small amount of water vapor) is 1%.

[0073] (2) The crude synthesis gas obtained by gasification is pressurized to 3.7 MPa by a compressor, and then subjected to detarring, desulfurization, deoxygenation, decarbonylation, and dehydration treatment in a synthesis gas purification unit to obtain purified synthesis gas.

[0074] The purified synthesis gas is subjected to the decarbonization unit to remove CO2 to obtain decarbonized synthesis gas; the CO2 removed in the decarbonization unit is returned to the first gasification section of the gasifier.

[0075] (3) The decarbonized synthesis gas is mixed with 5251Nm 3 / h of green hydrogen with a purity of 99.9% (hydrogen produced by electrolyzing water in an electrolysis unit) is mixed in a hydrogen-to-carbon ratio adjustment unit to obtain synthesis gas with a hydrogen-to-carbon ratio of 1.96, which is then compressed to 3.5MPa and enters the Fischer-Tropsch synthesis unit.

[0076] The Fischer-Tropsch synthesis reaction in the Fischer-Tropsch synthesis unit takes place at 220°C and 3.5 MPa. The catalyst used is Co / TiO2-ZrO2 (the catalyst is the same as that in Example 1), and the reactor used is a shell-and-tube fixed bed reactor.

[0077] The Fischer-Tropsch synthesis product generated by the Fischer-Tropsch reaction enters the first separation unit for separation, and the separation obtains tail gas, water, solid wax and Fischer-Tropsch synthesis oil, of which 1.90 tons / h of solid wax and 0.64 tons / h of Fischer-Tropsch synthesis oil are obtained. After the solid wax and Fischer-Tropsch synthesis oil are mixed, they enter the hydrogenation unit. The hydrogenation unit comprises two reactors in series. The first reactor is loaded with a nickel-tungsten catalyst (the catalyst is the same as that in Example 1), the carrier is a Y molecular sieve and an amorphous silicon-aluminum composite oxide, the reaction temperature is 330°C, and the pressure is 8MPa; the second reactor is loaded with a platinum-based catalyst (the catalyst is the same as that in Example 1), the carrier is ZSM-48, the reaction temperature is 330°C, and the pressure is 5MPa. The wax oil product obtained by hydrogenation enters the second separation unit and is separated by atmospheric and vacuum pressure to obtain 1.81 tons / h of green aviation kerosene components and 0.61 tons / h of green gasoline components.

[0078] During the process, the tail gas and water output from the first separation unit are circulated to the first gasification section of the gasifier in step (1), the purge gas generated in the Fischer-Tropsch synthesis unit is circulated to the second gasification section of the gasifier in step (1), and the saturated water vapor generated in the Fischer-Tropsch synthesis unit is circulated to the first gasification section of the gasifier in step (1).

[0079] In this example, the carbon content of the biomass feedstock is 40 wt%. The biomass feedstock is 10 tons per hour, of which the carbon content is 4 tons. The resulting hourly production of 2.42 tons of jet fuel and gasoline products has a carbon content of 85.7 wt%, or 2.07 tons. Therefore, the system's carbon utilization efficiency is 51.8%.

[0080] Example 3

[0081] (1) Rice husks are used as biomass raw materials. 10 tons / h of biomass raw materials are mixed and then enter a slightly negative pressure biomass gasifier (a fluidized bed gasifier). The water content of the biomass is 35wt%. The biomass first enters the first gasification section of the gasifier. The gasification temperature of the first gasification section is 850°C. The crude synthesis gas obtained in the first gasification section enters the second gasification section of the gasifier to continue the reaction. The temperature of the second gasification section is 1000°C. The gasifying agents used in the gasifier are pure oxygen and water vapor. The volume ratio of oxygen to water vapor is 10:1. The carrier gas is carbon dioxide. The gas volume of the gasifier outlet gas after dehydration is 12100Nm 3 / h, the pressure is -0.01MPa, and the composition of the crude synthesis gas is (volume percentage): 51% H2, 45% CO, 3% CO2, 0.2% CH4, 0.7% N2, and the concentration of other gases is 0.1%.

[0082] (2) The crude synthesis gas obtained by gasification is pressurized to 3.7 MPa by a compressor, and then detarred, desulfurized, deoxygenated, decarbonylated and dehydrated in a synthesis gas purification unit to obtain purified synthesis gas.

[0083] The purified synthesis gas is subjected to the decarbonization unit to remove CO2 to obtain decarbonized synthesis gas; the CO2 removed in the decarbonization unit is returned to the first gasification section of the gasifier.

[0084] (3) The decarbonized synthesis gas is mixed with 5150Nm 3 / h of green hydrogen with a purity of 99.9% (hydrogen produced by electrolyzing water in an electrolysis unit) is mixed in a hydrogen-to-carbon ratio adjustment unit to obtain synthesis gas with a hydrogen-to-carbon ratio of 2.1, which is then compressed to 3.5 MPa and enters the Fischer-Tropsch synthesis unit.

[0085] The Fischer-Tropsch synthesis reaction in the Fischer-Tropsch synthesis unit occurs at 220°C and 3.1 MPa. The catalyst used is Co / TiO2-SiO2 (wherein the Co content is 45 wt%, the TiO2 content is 50 wt%, and the ZrO2 content is 5 wt%), and the reactor used is a shell-and-tube fixed bed reactor.

[0086] The Fischer-Tropsch synthesis product generated by the Fischer-Tropsch reaction enters the first separation unit for separation, and the separation yields tail gas, water, solid wax, and Fischer-Tropsch synthesis oil, of which 2.17 tons / h of solid wax and 0.72 tons / h of Fischer-Tropsch synthesis oil are obtained. The solid wax and Fischer-Tropsch synthesis oil are mixed and then enter the hydrogenation unit, which comprises two reactors in series. The first reactor is loaded with a nickel-tungsten catalyst (the catalyst is the same as that in Example 1), with a carrier of Y molecular sieve and amorphous silicon-aluminum composite oxide, a reaction temperature of 330°C, and a pressure of 8MPa; the second reactor is loaded with a platinum-based catalyst (platinum content of 1wt%), with a carrier of ZSM-22, a reaction temperature of 330°C, and a pressure of 5MPa. The wax oil product obtained by hydrogenation enters the second separation unit for atmospheric and vacuum separation, yielding 2.01 tons / h of green aviation kerosene components and 0.68 tons / h of green gasoline components.

[0087] During the process, the tail gas and water output from the first separation unit are circulated to the first gasification section of the gasifier in step (1), the purge gas generated in the Fischer-Tropsch synthesis unit is circulated to the second gasification section of the gasifier in step (1), and the saturated water vapor generated in the Fischer-Tropsch synthesis unit is circulated to the first gasification section of the gasifier in step (1).

[0088] In this example, the carbon content of the biomass feedstock was 40 wt%. The biomass feedstock was 10 tons per hour, of which the carbon content was 4 tons. The resulting jet fuel and gasoline product produced in one hour was 2.69 tons, with a carbon content of 85.7% and a carbon content of 2.31 tons. Therefore, the system's carbon utilization efficiency was 57.8%.

[0089] Example 4

[0090] (1) Straw is used as biomass raw material. 12.5 tons / h of biomass raw material is mixed and then enters a micro-positive pressure biomass gasifier (a fluidized bed gasifier). The water content of the biomass is 25wt%. The biomass first enters the first gasification section of the gasifier. The gasification temperature of the first gasification section is 700°C. The crude synthesis gas obtained in the first gasification section enters the second gasification section of the gasifier to continue the reaction. The temperature of the second gasification section is 1150°C. The gasifying agents used in the gasifier are pure oxygen and water vapor. The volume ratio of oxygen to water vapor is 10:1. The carrier gas is carbon dioxide. The gas volume of the gasifier outlet gas after dehydration is 10020Nm 3 / h, the pressure is 0.08 MPa, and the composition of the raw synthesis gas is (volume percentage): 48% H2, 47% CO, 4% CO2, 0.3% CH4, 0.6% N2, and the concentration of other gases is 0.1%.

[0091] (2) The crude synthesis gas obtained by gasification is pressurized to 3.8 MPa by a compressor, and then subjected to detarring, desulfurization, deoxygenation, decarbonylation and dehydration treatment in a synthesis gas purification unit to obtain purified synthesis gas.

[0092] The purified synthesis gas is subjected to the decarbonization unit to remove CO2 to obtain decarbonized synthesis gas; the CO2 removed in the decarbonization unit is returned to the first gasification section of the gasifier.

[0093] (3) Combine the decarbonized syngas with 4950Nm 3 / h of green hydrogen with a purity of 99.9% (hydrogen produced by electrolyzing water in an electrolysis unit) is mixed in a hydrogen-to-carbon ratio adjustment unit to obtain synthesis gas with a hydrogen-to-carbon ratio of 2.0, which is then compressed to 3.4 MPa and enters the Fischer-Tropsch synthesis unit.

[0094] The Fischer-Tropsch synthesis reaction in the Fischer-Tropsch synthesis unit takes place at 225° C. and 3.2 MPa. The catalyst used is Co / TiO 2 (wherein the Co content is 50 wt%), and the reactor used is a shell-and-tube fixed-bed reactor.

[0095] The Fischer-Tropsch synthesis product generated by the Fischer-Tropsch reaction enters the first separation unit for separation, and the separation yields tail gas, water, solid wax, and Fischer-Tropsch synthesis oil, of which 1.95 tons / h of solid wax and 0.70 tons / h of Fischer-Tropsch synthesis oil are obtained. The solid wax and Fischer-Tropsch synthesis oil are mixed and then enter the hydrogenation unit, which comprises two reactors in series. The first reactor is loaded with a nickel-tungsten catalyst (the catalyst is the same as that in Example 1), with a carrier of Y molecular sieve and amorphous silicon-aluminum composite oxide, a reaction temperature of 330°C, and a pressure of 8MPa; the second reactor is loaded with a platinum-based catalyst (platinum content of 1wt%), with a carrier of ZSM-22, a reaction temperature of 330°C, and a pressure of 5MPa. The wax oil product obtained by the hydrogenation treatment enters the second separation unit for atmospheric and vacuum separation, yielding 2.09 tons / h of green aviation kerosene components and 0.75 tons / h of green gasoline components.

[0096] During the process, the tail gas and water output from the first separation unit are circulated to the first gasification section of the gasifier in step (1), the purge gas generated in the Fischer-Tropsch synthesis unit is circulated to the second gasification section of the gasifier in step (1), and the saturated water vapor generated in the Fischer-Tropsch synthesis unit is circulated to the first gasification section of the gasifier in step (1).

[0097] In this example, the carbon content of the biomass feedstock was 32 wt%. The biomass feedstock was 12.5 tons per hour, of which the carbon content was 4 tons. The resulting jet fuel and gasoline product produced in one hour was 2.84 tons, with a carbon content of 85.7% and a carbon content of 2.43 tons. Therefore, the system's carbon utilization efficiency was 60.8%.

[0098] Example 5 (Compared with Example 2, the biomass water content is different)

[0099] (1) Rice husks are used as biomass raw materials. 10 tons / h of biomass raw materials are mixed and then enter a micro-positive pressure biomass gasifier (a fluidized bed gasifier). The water content of the biomass is 10wt%. The biomass first enters the first gasification section of the gasifier. The gasification temperature of the first gasification section is 800°C. The crude synthesis gas obtained in the first gasification section enters the second gasification section of the gasifier to continue the reaction. The temperature of the second gasification section is 1000°C. The gasifying agents used in the gasifier are pure oxygen and water vapor. The volume ratio of oxygen to water vapor is 10:1. The carrier gas is carbon dioxide. The gas flow rate of the gasifier outlet gas after dehydration is 9990Nm 3 / h, the pressure is 0.01MPa, and the composition of the crude synthesis gas is (volume percentage): 45% H2, 50% CO, 3.5% CO2, 0.4% CH4, 0.6% N2, and the concentration of other gases is 0.5%.

[0100] (2) The crude synthesis gas obtained by gasification is pressurized to 3.7 MPa by a compressor, and then subjected to detarring, desulfurization, deoxygenation, decarbonylation, and dehydration treatment in a synthesis gas purification unit to obtain purified synthesis gas.

[0101] The purified synthesis gas is subjected to the decarbonization unit to remove CO2 to obtain decarbonized synthesis gas; the CO2 removed in the decarbonization unit is returned to the first gasification section of the gasifier.

[0102] (3) Combine the decarbonized syngas with 5300Nm 3 / h of green hydrogen with a purity of 99.9% (hydrogen produced by electrolyzing water in an electrolysis unit) is mixed in a hydrogen-to-carbon ratio adjustment unit to obtain synthesis gas with a hydrogen-to-carbon ratio of 1.96, which is then compressed to 3.5MPa and enters the Fischer-Tropsch synthesis unit.

[0103] The Fischer-Tropsch synthesis reaction in the Fischer-Tropsch synthesis unit takes place at 220°C and 3.5 MPa. The catalyst used is Co / TiO2-ZrO2 (the catalyst is the same as that in Example 1), and the reactor used is a shell-and-tube fixed bed reactor.

[0104] The Fischer-Tropsch synthesis product generated by the Fischer-Tropsch reaction enters the first separation unit for separation, and the separation obtains tail gas, water, solid wax and Fischer-Tropsch synthesis oil, of which 1.93 tons / h of solid wax and 0.65 tons / h of Fischer-Tropsch synthesis oil are obtained. After the solid wax and Fischer-Tropsch synthesis oil are mixed, they enter the hydrogenation unit. The hydrogenation unit comprises two reactors in series. The first reactor is loaded with a nickel-tungsten catalyst (the catalyst is the same as that in Example 1), the carrier is a Y molecular sieve and an amorphous silicon-aluminum composite oxide, the reaction temperature is 330°C, and the pressure is 8MPa; the second reactor is loaded with a platinum-based catalyst (the catalyst is the same as that in Example 1), the carrier is ZSM-48, the reaction temperature is 330°C, and the pressure is 5MPa. The wax oil product obtained by hydrogenation enters the second separation unit and is separated by atmospheric and vacuum pressure to obtain 1.84 tons / h of green aviation kerosene components and 0.62 tons / h of green gasoline components.

[0105] During the process, the tail gas and water output from the first separation unit are circulated to the first gasification section of the gasifier in step (1), the purge gas generated in the Fischer-Tropsch synthesis unit is circulated to the second gasification section of the gasifier in step (1), and the saturated water vapor generated in the Fischer-Tropsch synthesis unit is circulated to the first gasification section of the gasifier in step (1).

[0106] In this example, the carbon content of the biomass feedstock is 40 wt%. The biomass feedstock is 10 tons per hour, of which the carbon content is 4 tons. The resulting hourly production of 2.46 tons of jet fuel and gasoline products has a carbon content of 85.7 wt%, or 2.11 tons. Therefore, the system's carbon utilization efficiency is 52.8%.

[0107] Comparative Example 1

[0108] Rice husks were used as biomass raw materials with a water content of 50 wt%. 10 tons / h of biomass raw materials were mixed and then fed into a normal pressure biomass gasifier (a fluidized bed gasifier) ​​at a gasification temperature of 830°C. The gasifier used pure oxygen and water vapor in a volume ratio of 10:1, and CO2 as the carrier gas. The gas flow rate of the gasifier outlet gas after detarring and dehydration was 7600 Nm 3 / h, the composition of crude synthesis gas is (volume percentage): 32% H2, 31% CO, 17% CO2, 13% CH4, 2.5% of ethane and other C2 or higher alkanes, 1% N2, and 3.5% of other impurities.

[0109] The crude syngas produced by gasification is compressed to 3.2 MPa by a compressor. After detarring, deoxygenation, and decarbonylation, it enters the shift unit. The shift unit uses a molybdenum sulfide catalyst and simultaneously introduces steam at a steam-to-crude syngas volume ratio of 0.1:1. Some of the CO reacts with the steam to produce H2 and CO2. The post-shift gas composition is: 39% H2, 20% CO, 23% CO2, 13% CH4, 2% other hydrocarbons, 1% N2, and 2% other impurities. After desulfurization and CO2 removal, the shift gas enters the Fischer-Tropsch synthesis unit.

[0110] The Fischer-Tropsch synthesis reaction takes place at 220°C and 3.1MPa. The catalyst used is Co / TiO2 (the catalyst is the same as that in Example 4), and the reactor used is a fixed-bed tubular reactor. The Fischer-Tropsch reaction produces 0.45 tons / h of solid wax and 0.29 tons / h of Fischer-Tropsch synthetic oil. After the solid wax and Fischer-Tropsch synthetic oil are mixed, they enter the hydrogenation unit. The hydrogenation unit comprises two reactors in series. The first reactor is loaded with a nickel-tungsten catalyst (the catalyst is the same as that in Example 1), the carrier is a Y molecular sieve and an amorphous silicon-aluminum composite oxide, the reaction temperature is 330°C, and the pressure is 8MPa; the second reactor is loaded with a platinum-based catalyst (the catalyst is the same as that in Example 1), the carrier is ZSM-48, the reaction temperature is 280°C, and the pressure is 5MPa. After the wax oil product obtained by hydrogenation is separated by atmospheric and vacuum pressure, 0.4 tons / h of green aviation kerosene component and 0.32 tons / h of green gasoline component are obtained.

[0111] The carbon content of the biomass feedstock is 40 wt%. The biomass feedstock is 10 tons per hour, of which the carbon content is 4 tons. The production of 0.72 tons of jet fuel and gasoline products per hour is 85.7 wt%, with a carbon content of 0.6 ton. Therefore, the system carbon utilization efficiency is 15 wt%.

[0112] Comparative Example 2 (Compared with Example 1, without carbon dioxide circulation)

[0113] (1) Rice husks are used as biomass raw materials. 10 tons / h of biomass raw materials are mixed and then enter a slightly negative pressure biomass gasifier (a fluidized bed gasifier). The water content of the biomass is 15wt%. The biomass first enters the first gasification section of the gasifier. The gasification temperature of the first gasification section is 750°C. The crude synthesis gas obtained in the first gasification section enters the second gasification section of the gasifier to continue the reaction. The temperature of the second gasification section is 1000°C. The gasifying agents used in the gasifier are oxygen and water vapor. The volume ratio of oxygen to water vapor is 10:1. The carrier gas is CO2. The gas flow rate of the gasifier outlet gas after dehydration is 9020Nm 3 / h, the pressure is -0.05MPa, and the main components of the crude synthesis gas are (volume percentage): 44% H2, 47% CO, 4% CO2, 4.3% CH4, and 0.7% N2.

[0114] (2) The crude synthesis gas obtained by gasification is pressurized to 3.7 MPa by a compressor, and then detarred, desulfurized, deoxygenated, decarbonylated and dehydrated in a synthesis gas purification unit to obtain purified synthesis gas.

[0115] The purified synthesis gas is subjected to the decarbonization unit to remove CO2 to obtain decarbonized synthesis gas.

[0116] (3) The decarbonized synthesis gas is mixed with 4533Nm 3 / h of green hydrogen with a purity of 99.9% (hydrogen produced by electrolyzing water in an electrolysis unit) is mixed to obtain synthesis gas with a hydrogen-to-carbon ratio of 2.0, which is compressed to 3.5MPa and enters the Fischer-Tropsch synthesis unit.

[0117] The Fischer-Tropsch synthesis reaction in the Fischer-Tropsch synthesis unit occurs at 220°C and 3.1 MPa. The catalyst used is Co / TiO2-ZrO2 (the same catalyst as in Example 1), and the reactor used is a shell-and-tube fixed-bed reactor.

[0118] The Fischer-Tropsch synthesis product generated by the Fischer-Tropsch reaction enters the first separation unit for separation, and the separation obtains tail gas, water, solid wax and Fischer-Tropsch synthesis oil, wherein, solid wax is 1.75 tons / h and Fischer-Tropsch synthesis oil is 0.61 tons / h. After the solid wax and Fischer-Tropsch synthesis oil are mixed, they enter the hydrogenation unit. The hydrogenation unit comprises two reactors in series. The first reactor is loaded with a nickel-tungsten catalyst (the same as the catalyst in Example 1), the carrier is a Y molecular sieve and an amorphous silicon-aluminum composite oxide, the reaction temperature is 330 ° C, and the pressure is 8 MPa; the second reactor is loaded with a platinum-based catalyst (the same as the catalyst in Example 1), the carrier is ZSM-48, the reaction temperature is 280 ° C, and the pressure is 5 MPa. After the wax oil product obtained by hydrogenation is separated by atmospheric and vacuum pressure, 1.81 tons / h of green aviation kerosene components and 0.51 tons / h of green gasoline components are obtained.

[0119] During the process, the tail gas and water output from the first separation unit are circulated to the first gasification section of the gasifier in step (1), the purge gas generated in the Fischer-Tropsch synthesis unit is circulated to the second gasification section of the gasifier in step (1), and the saturated water vapor generated in the Fischer-Tropsch synthesis unit is circulated to the first gasification section of the gasifier in step (1).

[0120] In this example, the carbon content of the biomass feedstock is 40 wt%. The biomass feedstock is 10 tons per hour, of which the carbon content is 4 tons. The resulting production of 2.32 tons of jet fuel and gasoline per hour is 85.7 wt%, with a carbon content of 1.99 tons. Therefore, the system's carbon utilization efficiency is 49.8%.

[0121] Comparative Example 3 (Compared with Example 2, the water content of biomass is different)

[0122] The process was carried out with reference to Example 2, except that the water content of the biomass used was 2 wt % and the catalysts used were the same as those in Example 2.

[0123] (1) Rice husks are used as biomass raw materials. 10 tons / h of biomass raw materials are mixed and then enter a micro-positive pressure biomass gasifier (a fluidized bed gasifier). The water content of the biomass is 2wt%. The biomass first enters the first gasification section of the gasifier. The gasification temperature of the first gasification section is 800°C. The crude synthesis gas obtained in the first gasification section enters the second gasification section of the gasifier to continue the reaction. The temperature of the second gasification section is 1000°C. The gasifying agents used in the gasifier are pure oxygen and water vapor. The volume ratio of oxygen to water vapor is 10:1. The carrier gas is carbon dioxide. The gas flow rate of the gasifier outlet gas after dehydration is 8330Nm 3 / h, the pressure is 0.01MPa, and the composition of the crude synthesis gas is (volume percentage): 42% H2, 52% CO, 3.5% CO2, 0.8% CH4, 0.7% N2, and the concentration of other gases is 1%.

[0124] (2) The crude synthesis gas obtained by gasification is pressurized to 3.7 MPa by a compressor, and then subjected to detarring, desulfurization, deoxygenation, decarbonylation, and dehydration treatment in a synthesis gas purification unit to obtain purified synthesis gas.

[0125] The purified synthesis gas is subjected to the decarbonization unit to remove CO2 to obtain decarbonized synthesis gas; the CO2 removed in the decarbonization unit is returned to the first gasification section of the gasifier.

[0126] (3) The decarbonized synthesis gas is mixed with 4499Nm 3 / h of green hydrogen with a purity of 99.9% (hydrogen produced by electrolyzing water in an electrolysis unit) is mixed to obtain synthesis gas with a hydrogen-to-carbon ratio of 1.96, which is compressed to 3.5MPa and enters the Fischer-Tropsch synthesis unit.

[0127] The Fischer-Tropsch synthesis reaction in the Fischer-Tropsch synthesis unit occurs at 220°C and 3.5 MPa. The catalyst used is Co / TiO2-ZrO2, and the reactor used is a shell-and-tube fixed bed reactor.

[0128] The Fischer-Tropsch synthesis product generated by the Fischer-Tropsch reaction enters the first separation unit for separation, yielding tail gas, water, solid wax, and Fischer-Tropsch oil. The solid wax and Fischer-Tropsch oil are mixed and then fed into a hydrogenation unit, which consists of two reactors in series. The first reactor is loaded with a nickel-tungsten catalyst supported by Y molecular sieve and amorphous silica-alumina composite oxide, operating at a temperature of 330°C and a pressure of 8 MPa. The second reactor is loaded with a platinum-based catalyst supported by ZSM-48, operating at a temperature of 330°C and a pressure of 5 MPa. The wax oil product from the hydrogenation process is separated under atmospheric and vacuum conditions to produce 1.48 tons / h of green aviation kerosene components and 0.49 tons / h of green gasoline components.

[0129] During the process, the tail gas and water output from the first separation unit are circulated to the first gasification section of the gasifier in step (1), the purge gas generated in the Fischer-Tropsch synthesis unit is circulated to the second gasification section of the gasifier in step (1), and the saturated water vapor generated in the Fischer-Tropsch synthesis unit is circulated to the first gasification section of the gasifier in step (1).

[0130] In this example, the carbon content of the biomass feedstock was 40 wt%. The biomass feed was 10 tons per hour, of which the carbon content was 4 tons. The resulting production of 1.97 tons of jet fuel and gasoline per hour was 85.7 wt%, with a carbon content of 1.69 tons. Therefore, the system's carbon utilization efficiency was 42.2%.

[0131] Comparative Example 4 (only one stage of gasification)

[0132] Rice husks were used as biomass raw materials. 10 tons / h of biomass raw materials were mixed and then fed into a slightly negative pressure biomass gasifier (a fluidized bed gasifier). The water content of the biomass was 15 wt%. The biomass first entered the first stage gasifier at a gasification temperature of 750°C. The gasifier used oxygen and water vapor in a volume ratio of 10:1. The carrier gas was carbon dioxide. The gas flow rate of the gasifier outlet gas after detarring and dehydration was 6754 Nm 3 / h, the pressure is -0.05MPa, and the main components of crude synthesis gas are (volume percentage): 25% H2, 36% CO, 25% CO2, 9% CH4, 0.8% N2, ethane and other hydrocarbons and other components 4.2%.

[0133] (2) The crude synthesis gas obtained by gasification is pressurized to 3.7 MPa by a compressor, and then detarred, desulfurized, deoxygenated, decarbonylated and dehydrated in a synthesis gas purification unit to obtain purified synthesis gas.

[0134] The purified synthesis gas is subjected to the decarbonization unit to remove CO2 to obtain decarbonized synthesis gas; the CO2 removed in the decarbonization unit is returned to the gasifier.

[0135] (3) The decarbonized synthesis gas is mixed with 3173Nm 3 / h of green hydrogen with a purity of 99.9% (hydrogen produced by electrolyzing water in an electrolysis unit) is mixed in a hydrogen-to-carbon ratio adjustment unit to obtain synthesis gas with a hydrogen-to-carbon ratio of 2.0, which is then compressed to 3.5 MPa and enters the Fischer-Tropsch synthesis unit.

[0136] The Fischer-Tropsch synthesis reaction in the Fischer-Tropsch synthesis unit takes place at 220°C and 3.1 MPa. The catalyst used is Co / TiO2-ZrO2 (the catalyst is the same as that in Example 1), and the reactor used is a shell-and-tube fixed-bed reactor.

[0137] The Fischer-Tropsch synthesis product generated by the Fischer-Tropsch reaction enters the first separation unit for separation, and the separation yields tail gas, water, solid wax, and Fischer-Tropsch synthesis oil, of which 0.98 tons / h of solid wax and 0.32 tons / h of Fischer-Tropsch synthesis oil are obtained. The solid wax and Fischer-Tropsch synthesis oil are mixed and then enter the hydrogenation unit, which comprises two reactors in series. The first reactor is loaded with a nickel-tungsten catalyst (the catalyst is the same as that in Example 1), with a Y molecular sieve and an amorphous silicon-aluminum composite oxide as the carrier, and the reaction temperature is 330°C and the pressure is 8MPa; the second reactor is loaded with a platinum-based catalyst (the catalyst is the same as that in Example 1), with a platinum content of 1wt%, a ZSM-48 as the carrier, and the reaction temperature is 330°C and the pressure is 5MPa. The wax oil product obtained by the hydrogenation treatment enters the second separation unit for atmospheric and vacuum separation, yielding 0.97 tons / h of green aviation kerosene components and 0.32 tons / h of green gasoline components.

[0138] During the process, the tail gas and water output from the first separation unit are circulated to the first gasification section of the gasifier in step (1), the purge gas generated in the Fischer-Tropsch synthesis unit is circulated to the second gasification section of the gasifier in step (1), and the saturated water vapor generated in the Fischer-Tropsch synthesis unit is circulated to the first gasification section of the gasifier in step (1).

[0139] In this example, the carbon content of the biomass feedstock is 40 wt%. The biomass feedstock is 10 tons per hour, of which the carbon content is 4 tons. The resulting production of 1.29 tons of jet fuel and gasoline per hour is 85.7 wt%, or 1.11 tons of carbon. Therefore, the system's carbon utilization efficiency is 27.8%.

[0140] Table 1 Summary of experimental results

[0141]

[0142]

[0143] According to the embodiment of the process of the present invention, water-containing biomass can be directly used to efficiently produce oil products. As can be seen from the above embodiments, directly using biomass with a water content of 5-40wt% to prepare oil products through the process of the present invention has a better carbon utilization rate, and the effective gas content in the obtained crude synthesis gas is high. More preferably, controlling the water content to 10-40% is more effective, which can further improve the carbon utilization rate, facilitate the acquisition of a crude synthesis gas with a relatively high ratio of hydrogen and carbon monoxide, and facilitate the acquisition of a crude synthesis gas with a relatively high hydrogen-carbon ratio. In addition, in the embodiment of the present invention, no corrosion occurs at the outlet of the gasifier during the operation of the gasifier. The crude synthesis gas obtained in the gasifier of each embodiment of the present invention has a low tar content (as low as ppm level) and can enter the downstream process without detarring treatment; the gas flow rate of the crude synthesis gas of Comparative Examples 1 and 4 after detarring and dehydration is significantly lower than that of the embodiments of the present invention. This reflects that the crude synthesis gas obtained from the gasifier in Comparative Examples 1 and 4 has a high tar content; Comparative Examples 1 and 4 need to undergo detarring treatment before being used in subsequent processes.

[0144] It will be readily understood that the above embodiments are merely examples for clarity of description and are not intended to limit the present invention to these examples. Those skilled in the art will readily appreciate that other variations or modifications based on the above description are possible. It is not necessary and impossible to provide an exhaustive list of all possible implementations. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A method for efficiently preparing oil products using biomass as raw material, characterized in that: The method comprises the following steps: (1) A biomass feedstock with a moisture content of 5-40 wt% is fed into a gasifier, first entering the first gasification section of the gasifier for gasification reaction, and then the gasification product obtained in the first gasification section enters the second gasification section of the gasifier for further reaction to obtain a crude synthesis gas; wherein the gasification temperature of the first gasification section is 650-850°C, and the temperature of the second gasification section is 900-1200°C; the pressure of the gasifier is -0.1 MPa to 0.1 MPa, and the gasifier is a fluidized bed gasifier; (2) Purifying the crude synthesis gas obtained in step (1) to obtain purified synthesis gas; removing carbon dioxide from the purified synthesis gas to obtain decarbonized synthesis gas and carbon dioxide; and recycling the carbon dioxide to the first gasification section; (3) The decarbonized synthesis gas obtained in step (2) is fed into a Fischer-Tropsch synthesis unit after adjusting the hydrogen-carbon ratio, and a Fischer-Tropsch synthesis product is obtained by a Fischer-Tropsch synthesis reaction, and the Fischer-Tropsch synthesis product is post-processed to obtain an oil product.

2. The method according to claim 1, characterized in that In step (1), the moisture content of the biomass raw material is 10-40 wt%, for example, 10-25 wt%; and / or, in step (1), the biomass is not dried before being fed into the gasifier; And / or, in step (1), the biomass is crushed before being fed into the gasifier.

3. The method according to claim 1, characterized in that recycling the tail gas generated in the Fischer-Tropsch synthesis reaction in step (3) to the first gasification section; and / or, recycling the wastewater and / or saturated steam generated in the Fischer-Tropsch synthesis reaction into the first gasification section as a gasifying agent; And / or, the purge gas generated in the Fischer-Tropsch synthesis unit is recycled to the second gasification section.

4. The method according to any one of claims 1 to 3, characterized in that In the gasifier, the gasifying agent is mainly oxygen, and the carrier gas is water vapor and / or carbon dioxide.

5. The method according to any one of claims 1 to 3, characterized in that In step (3), the hydrogen-to-carbon ratio is adjusted by mixing green hydrogen obtained by electrolysis of water with the decarbonized synthesis gas; Preferably, the hydrogen-to-carbon ratio is 1.9-2.

15.

6. The method according to any one of claims 1 to 3, characterized in that In step (3), the catalyst used in the Fischer-Tropsch synthesis reaction is a cobalt-based catalyst; and / or the Fischer-Tropsch synthesis reaction is carried out in a fixed bed reactor, preferably a shell-and-tube fixed bed reactor; and / or the reaction temperature of the Fischer-Tropsch synthesis reaction is 200-250° C. and the pressure is 1.5-5 MPa; Preferably, the cobalt-based catalyst comprises a carrier and an active component cobalt supported on the carrier, and the carrier comprises one or more of titanium oxide, silicon oxide and zirconium oxide; Further preferably, the support comprises at least titanium oxide; Further preferably, based on the total weight of the cobalt-based catalyst, the content of the active component metal cobalt is 10-50%; and the content of the carrier is 50-90%.

7. The method according to any one of claims 1 to 3, characterized in that In step (2), the purification of the crude synthesis gas includes detarring, desulfurizing, deoxygenating, decarbonylating and dehydrating the crude synthesis gas.

8. The method according to any one of claims 1 to 3, characterized in that In step (3), the post-treatment comprises the following steps: separating the Fischer-Tropsch synthesis product to obtain oil-wax components, water and tail gas, or obtaining solid crude wax, the oil component of the solid crude wax separated, water and tail gas; The separated oil wax component or the separated oil component is sent to a hydrogenation unit for hydrocracking and isomerization, and the product obtained from the hydrogenation unit is separated to obtain white oil and / or fuel oil products; Optionally, part or all of the solid crude wax is also fed to the hydrogenation unit; Optionally, the method further comprises the steps of: separating part or all of the solid crude wax to obtain wax products with different melting points; Preferably, the fuel oil product includes one or more of a diesel fraction, an aviation kerosene fraction, and a gasoline fraction.

9. A system for efficiently preparing oil products using biomass as raw material, characterized in that: The system comprises: A gasifier, wherein the gasification section of the gasifier comprises a first gasification section and a second gasification section, wherein the first gasification section is used to perform a first-stage gasification reaction on biomass, and the second gasification section is used to subject the gasification product obtained in the first gasification section to a second-stage gasification reaction to obtain crude synthesis gas; preferably, the gasifier is a fluidized bed gasifier; a syngas purification unit, the syngas purification unit being used to purify the raw syngas obtained from the gasifier to obtain purified syngas; a decarbonization unit for removing carbon dioxide from the purified syngas to obtain decarbonized syngas and carbon dioxide; the decarbonization unit is connected to the first gasification section of the gasifier to circulate the carbon dioxide obtained in the decarbonization unit to the first gasification section; a hydrogen-to-carbon ratio adjustment unit, configured to receive the decarbonized synthesis gas obtained by the decarbonization unit and mix it with hydrogen to adjust the hydrogen-to-carbon ratio of the decarbonized synthesis gas; preferably, the hydrogen is green hydrogen; a Fischer-Tropsch synthesis unit connected to the hydrogen-to-carbon ratio adjustment unit, configured to subject the decarbonized synthesis gas, after hydrogen-to-carbon ratio adjustment, to a Fischer-Tropsch synthesis reaction to obtain a Fischer-Tropsch synthesis product; a post-processing unit, configured to post-process the Fischer-Tropsch synthesis product to obtain an oil product; Preferably, the post-processing unit comprises a first separation unit for separating the Fischer-Tropsch synthesis product to obtain oil-wax components, water and tail gas, or to obtain solid crude wax, the oil component from which the solid crude wax is separated, water and tail gas; Further preferably, the post-processing unit further comprises a hydrogenation unit for hydrocracking and isomerizing the oil wax component or the oil component separated in the first separation unit to obtain a hydrocracked and isomerized product; preferably, the hydrogenation unit is also used for hydrocracking and isomerizing part or all of the solid crude wax; Further preferably, the post-processing unit further comprises a wax cutting unit for separating part or all of the solid crude wax separated in the first separation unit to obtain wax products with different drop melting points; Further preferably, the post-processing unit further comprises a second separation unit for separating white oil and / or fuel oil products from the hydrocracking and isomerization products; Preferably, the system is used to implement the method according to any one of claims 1 to 8.

10. The system according to claim 9, characterized in that The system further comprises an electrolysis unit for electrolyzing water to produce the green hydrogen, wherein the electrolysis unit is connected to the hydrogen-to-carbon ratio adjustment unit to supply the green hydrogen to the hydrogen-to-carbon ratio adjustment unit; preferably, the electrolysis unit is also connected to the hydrogenation unit to supply green hydrogen to the hydrogenation unit; and / or, the Fischer-Tropsch synthesis unit is connected to the second gasification section of the gasifier to circulate the purge gas of the Fischer-Tropsch synthesis unit to the second gasification section; and / or, the Fischer-Tropsch synthesis unit is connected to the first gasification section of the gasifier to circulate saturated steam generated by the Fischer-Tropsch synthesis unit to the first gasification section; And / or, the first separation unit is connected to the first gasification section of the gasifier to circulate the water and tail gas separated by the first separation unit to the first gasification section.

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