Apparatus and method for co-production of syngas and bio-oil from biomass chemical looping deoxythermal pyrolysis

Abstract

The application provides a device and method for producing bio-oil and co-producing synthesis gas by biomass chemical looping deoxidation pyrolysis, which utilizes the redox reaction characteristics of an oxygen carrier to realize high-quality and high-yield bio-oil production and co-production of synthesis gas, and comprises the following steps: in a gasification reactor, an oxidized oxygen carrier and a carbon-containing fuel generate synthesis gas and are reduced; in a pyrolysis deoxidation reactor, the reduced oxygen carrier from the gasification reactor participates in the biomass pyrolysis and the deoxidation process of pyrolysis volatiles, so that high-quality and high-yield bio-oil is obtained; in a combustion regeneration reactor, the partially oxidized oxygen carrier from the pyrolysis deoxidation reactor is oxidized and heated, and then returns to the gasification reactor and the pyrolysis deoxidation reactor in turn, and the cycle is repeated.

Description

Technical Field

[0001] This invention belongs to the field of energy and chemical technology, and relates to an apparatus and method for biomass chemical chain deoxygenation pyrolysis to produce oil and syngas. Background Technology

[0002] Biomass energy is the world's fourth largest energy source after coal, oil, and natural gas. Biomass is characterized by its wide distribution, low pollution, high reserves, and carbon neutrality. Developing and utilizing biomass is one of the important means to address the environmental crisis caused by the depletion and over-exploitation of fossil fuels and to achieve dual-carbon goals. Biomass utilization methods include biochemical conversion methods such as fermentation and thermochemical conversion methods such as pyrolysis, gasification, and combustion. Among these, pyrolysis is the most suitable technology for converting biomass into liquid fuels. The main product of biomass pyrolysis, pyrolysis oil, is an important source for replacing fossil fuels and extracting high-value-added chemicals.

[0003] Biomass pyrolysis oil has application limitations due to its high oxygen content, high water content, instability, high acidity, and low calorific value, thus requiring quality improvement. Patent CN201910773843.8 proposes an apparatus and method for producing oil and gas from biomass through chemical chain pyrolysis, including the mixed pyrolysis of a high-temperature oxidized oxygen carrier and biomass, with the pyrolysis char and oxidized oxygen carrier undergoing chemical chain gasification to achieve co-production of syngas from pyrolysis oil. However, this patented method has the following problems: 1) The lattice oxygen of the oxidized oxygen carrier is transferred to the biomass pyrolysis oil and gas during pyrolysis, reducing tar quality; 2) The high-temperature oxygen carrier from the air reactor first participates in the biomass pyrolysis process and then gasifies, resulting in an unreasonable temperature gradient and low bio-oil yield. Summary of the Invention

[0004] To address the problem of low biomass tar yield and poor quality caused by unreasonable oxygen carrier valence state distribution and temperature gradient distribution in existing chemical chain pyrolysis technologies, this invention provides an apparatus and method for deoxygenating and co-producing syngas from biomass pyrolysis oil based on chemical chain pyrolysis.

[0005] The technical method of the present invention is as follows:

[0006] A biomass chemical loop deoxygenation pyrolysis oil production and syngas co-production device mainly consists of a gasification reactor, a pyrolysis deoxygenation reactor and a combustion regeneration reactor, which are connected in sequence to form a loop.

[0007] The gasification reactor, pyrolysis deoxygenation reactor, and combustion regeneration reactor are each equipped with two inlets and two outlets. One inlet of the gasification reactor is used to add carbon-containing fuel, and the other inlet is connected to one outlet of the combustion regeneration reactor. One outlet of the gasification reactor is used for syngas extraction, and the other outlet is connected to one inlet of the pyrolysis deoxygenation reactor to send the generated solid product carbon and reduced oxygen carrier to the pyrolysis deoxygenation reactor. One outlet of the pyrolysis deoxygenation reactor is used for the extraction of volatiles, where oxygen-containing hydrocarbons are deoxygenated, condensed, and then used to obtain low-oxygen bio-oil, as well as pyrolysis gas. The other outlet of the pyrolysis deoxygenation reactor is connected to one inlet of the combustion regeneration reactor to send the pyrolysis carbon and low-temperature oxidized oxygen carrier produced in the pyrolysis deoxygenation reactor, as well as the remaining reduced oxygen carrier, to the combustion regeneration reactor. The other inlet of the combustion regeneration reactor is used for air intake. The high-temperature oxidized oxygen carrier, a product of the combustion regeneration reactor, enters the gasification reactor through the outlet, and the product flue gas is extracted from the other outlet.

[0008] The gasification reactor may be a cross-flow moving bed reactor, but is not limited to this.

[0009] The thermal deoxygenation reactor may be a moving bed reactor, but is not limited to this.

[0010] The combustion regeneration reactor may be a fast fluidized bed reactor, but is not limited to this.

[0011] A method for biomass chemical chain deoxygenation pyrolysis to produce oil and co-generate syngas includes the following steps:

[0012] Step 1) The high-temperature oxidized oxygen carrier formed in the combustion regeneration reactor enters the gasification reactor, which heats the carbon-containing fuel and partially oxidizes the carbon-containing fuel or its pyrolysis volatiles to generate syngas, which is then extracted. Meanwhile, the high-temperature oxidized oxygen carrier is reduced, and at the same time, the medium-temperature solid product carbon from the decomposition of the carbon-containing fuel is also obtained.

[0013] Step 2) The biomass and solid products such as the medium-temperature reduced oxygen carrier and solid product char generated in the gasification reactor are transported to the pyrolysis deoxygenation reactor; the biomass is heated and decomposed to produce volatiles and pyrolysis char; under the action of the reduced oxygen carrier, the oxygen-containing hydrocarbons in the biomass pyrolysis volatiles are deoxygenated, and after condensation, low-oxygen bio-oil is obtained, while pyrolysis gas is obtained, and the reduced oxygen carrier is oxidized or partially oxidized.

[0014] Step 3) The solid products generated in the pyrolysis deoxidation reactor (including pyrolytic carbon, low-temperature oxidized oxygen carrier, and the remaining reduced oxygen carrier) are transported to the combustion regeneration reactor. Under the action of hot air, the pyrolytic carbon and the carbon deposits on the surface of the oxygen carrier are burned, the reduced oxygen carrier is completely oxidized, and the oxygen carrier is heated. After the obtained high-temperature oxidized oxygen carrier is separated from the hot flue gas, the high-temperature oxidized oxygen carrier is transported to the gasification reactor for recycling reaction.

[0015] In step 1), the carbon-containing fuel includes, but is not limited to, one or a mixture of two or more of the following: solid carbon-containing fuels (biomass, organic solid waste, low-rank coal, etc.), liquid carbon-containing fuels (waste tar, etc.) and gaseous carbon-containing fuels (petroleum gas, etc.).

[0016] In step 2), the biomass is one or more of the following: wood waste, agricultural straw, sludge, urban waste, etc.

[0017] In step 1), the oxygen carrier is a single metal or a composite metal oxide, including but not limited to one or more of Fe2O3, Fe3O4, Cr2O3, MnO2, Ca2Fe2O5, CaFe2O4, Cu2Fe2O5, and CuFe2O4.

[0018] The reaction temperature of the gasification reactor is controlled by adjusting the temperature of the oxidized oxygen carrier entering the gasification reactor and its ratio with the carbon-containing fuel. The temperature of the oxidized oxygen carrier is 800-900℃, and the mass ratio of the oxidized oxygen carrier to the carbon-containing fuel is 5-50.

[0019] The reaction temperature of the pyrolysis reactor is controlled by adjusting the temperature of the reduced oxygen carrier entering the pyrolysis reactor. The temperature of the reduced oxygen carrier is 500-700℃.

[0020] Specifically, this invention utilizes an oxidized oxygen carrier for chemical looping gasification to generate a reduced oxygen carrier; then, the reduced oxygen carrier is used to deoxygenate bio-oil to obtain high-quality bio-oil. In the gasification reactor, the high-temperature oxidized oxygen carrier heats the carbon-containing fuel and partially oxidizes the carbon-containing fuel or its pyrolysis volatiles to generate syngas, while the oxygen carrier is reduced, and solid char products from the decomposition of the carbon-containing fuel are also obtained. High temperature is beneficial to this process, but excessively high temperatures can lead to ash melting, resulting in bed agglomeration. Therefore, the preferred temperature of the oxidized oxygen carrier entering the gasification reactor is 800-900℃. Meanwhile, since chemical looping gasification is an endothermic reaction, the temperature of the reduced oxygen carrier is lowered to 500-700℃. Excessively high temperatures in the biomass pyrolysis and pyrolysis oil deoxygenation processes result in low pyrolysis oil yields, while excessively low temperatures result in poor pyrolysis oil quality; the temperature of the reduced oxygen carrier obtained from the gasification reactor is favorable for this process. In a pyrolysis deoxygenation reactor, biomass is heated and decomposed by a reduced oxygen carrier to produce volatiles and charcoal. The reduced oxygen carrier has deoxygenation capabilities, and the biomass pyrolysis volatiles contain a high content of oxygenated hydrocarbons. Under the action of the reduced oxygen carrier, the oxygenated hydrocarbons in the biomass pyrolysis volatiles are deoxygenated, and after condensation, low-oxygen bio-oil is obtained, along with pyrolysis gas, while the oxygen carrier is oxidized or partially oxidized. Since biomass pyrolysis is an endothermic reaction, the temperature of the oxygen carrier decreases by 50-100°C. Therefore, high-quality, high-yield biomass pyrolysis oil can be obtained in a pyrolysis deoxygenation reactor.

[0021] The beneficial effects of this invention are as follows: 1) It utilizes the redox reaction characteristics of oxygen carriers to produce high-quality biomass pyrolysis oil and co-produce syngas. During this process, the changes in oxygen carriers meet the needs of each unit and avoid the adverse effects of oxidized oxygen carriers on the pyrolysis units in general chemical looping pyrolysis; 2) The high-temperature oxygen carrier is cooled down after chemical looping gasification and then used for biomass pyrolysis. The temperature gradient of the oxygen carrier meets the temperature requirements of each unit, resulting in a higher yield of biomass pyrolysis oil; 3) The oxygen carrier can be recycled and reused; 4) The oxygen carrier also serves as a heat carrier, and this system can achieve self-heating balance without requiring additional energy input; 5) It has good raw material adaptability, high product quality, and is environmentally friendly. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the apparatus and method for biomass chemical chain deoxygenation pyrolysis to produce oil and syngas according to the present invention. Detailed Implementation

[0023] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and technical solutions.

[0024] The apparatus and method for biomass chemical chain deoxygenation pyrolysis to produce oil and co-generate syngas according to the present invention are as follows: Figure 1 As shown, the specific implementation is as follows:

[0025] Example 1

[0026] Start-up procedure: Add calcium ferrite and fuel at room temperature to the combustion regeneration reactor. Under the action of hot air, the fuel is burned, the calcium ferrite is heated and separated from the hot flue gas, and then passes through the gasification reactor and the thermal deoxygenation reactor. No carbon-containing fuel or biomass is added to the gasification reactor and the thermal deoxygenation reactor. The calcium ferrite is recycled back to the combustion regeneration reactor to continue heating until the target temperature is reached.

[0027] 1) Add calcium ferrite and white pine sawdust at 900℃ in a mass ratio of 50:1 to the gasification reactor. The white pine sawdust decomposes upon heating to produce volatiles. The volatiles reduce the oxygen carrier to produce syngas, reduced calcium ferrite (Fe-CaO) and charcoal.

[0028] The 700℃ reduced calcium ferrite, charcoal and white pine sawdust generated in step 1) are fed into the pyrolysis deoxygenation reactor. The white pine sawdust is decomposed by heat to produce volatiles and charcoal. Under the action of reduced calcium ferrite, the oxygen-containing hydrocarbons in the volatiles are deoxygenated to obtain low-oxygen bio-oil, pyrolysis gas, calcium ferrite. The component analysis of the obtained bio-oil is shown in Table 2.

[0029] The solid mixture generated in step 2) is fed into the combustion regeneration reactor. Under the action of hot air, the carbon on the surface of the charcoal and oxygen carrier is burned. The reduced oxygen carrier is completely oxidized and heated to 900°C. After being separated from the hot flue gas, it is recycled to the gasification reactor.

[0030] Example 2

[0031] Start-up steps: Replace calcium ferrite with hematite, and perform the other operations as in Example 1.

[0032] Hematite and petroleum gas at 850℃ with a mass ratio of 15:1 are added to a gasification reactor. After the petroleum gas is heated, it reduces the oxygen carrier to produce syngas and reduced hematite (FeO).

[0033] The 585℃ ferrous oxide and wheat straw generated in step 1) are fed into a pyrolysis deoxygenation reactor. The wheat straw is decomposed by heat to produce volatiles and charcoal. Under the action of reduced hematite, the oxygen-containing hydrocarbons in the volatiles are deoxygenated to obtain low-oxygen bio-oil, pyrolysis gas, and iron tetroxide. The component analysis of the obtained bio-oil is shown in Table 2.

[0034] The solid mixture generated in step 2) is fed into the combustion regeneration reactor. Under the action of hot air, the carbon on the surface of the charcoal and oxygen carrier is burned, and the iron oxide is completely oxidized and heated to 850°C. After being separated from the hot flue gas, it is recycled to the gasification reactor.

[0035] Example 3

[0036] Start-up steps: Same as in Example 1.

[0037] Calcium ferrite at 800℃ and waste tar in a mass ratio of 5:1 are added to a gasification reactor. The waste tar is heated to produce gaseous products, and then the oxygen carrier is reduced to produce syngas, reduced calcium ferrite (Fe-CaO) and charcoal.

[0038] The 500℃ reduced calcium ferrite and white pine sawdust generated in step 1) are fed into a pyrolysis deoxygenation reactor. The white pine sawdust is decomposed by heat to produce volatiles and charcoal. Under the action of reduced calcium ferrite, the oxygen-containing hydrocarbons in the volatiles are deoxygenated to obtain low-oxygen bio-oil, pyrolysis gas, and calcium ferrite. The component analysis of the obtained bio-oil is shown in Table 2.

[0039] The solid mixture generated in step 2) is fed into the combustion regeneration reactor. Under the action of hot air, the carbon on the surface of the charcoal and oxygen carrier is burned. The reduced oxygen carrier is completely oxidized and heated to 800°C. After being separated from the hot flue gas, it is recycled to the gasification reactor.

[0040] Comparative Example 1

[0041] Replace calcium ferrite with quartz sand, and follow the same procedures as in Example 1.

[0042] Table 1: Industrial and elemental analysis of white pine sawdust and wheat straw

[0043]

[0044] ① Difference reduction, ad.: air-dried basis, daf.: dry ash-free basis

[0045] Table 2: Relative Composition of Pyrolysis Oil Products

[0046]

[0047] The light tar in the examples and comparative examples was analyzed using a Shimadzu GCMS-QP2020 gas chromatography-mass spectrometry (GC-MS) system. The results in Table 2 show that in the bio-oil obtained in the comparative example, the relative content of anaerobic components was only 6.36%, the relative content of low-oxygen components was only 9.76%, while the relative contents of medium- and high-oxygen components were as high as 64.26% and 16.43%, respectively. The results from the examples show that the relative content of anaerobic components in the bio-oil increased, the relative content of low-oxygen components increased significantly to over 70%, the relative content of medium-oxygen components decreased significantly to below 5%, and the relative content of high-oxygen compounds decreased to below 1%. Therefore, this invention can effectively deoxygenate bio-oil by reducing the relative content of medium- and high-oxygen components and increasing the relative content of anaerobic and low-oxygen components.

Claims

1. A device for biomass chemical loop deoxygenation pyrolysis to produce oil and co-generate syngas, characterized in that, The device mainly consists of a gasification reactor, a thermal deoxygenation reactor, and a combustion regeneration reactor, which are connected in sequence to form a loop; The gasification reactor, pyrolysis deoxygenation reactor, and combustion regeneration reactor are each equipped with two inlets and two outlets. One inlet of the gasification reactor is used to add carbon-containing fuel, and the other inlet is connected to one outlet of the combustion regeneration reactor. One outlet of the gasification reactor is used for syngas extraction, and the other outlet is connected to one inlet of the pyrolysis deoxygenation reactor to send the generated solid product carbon and reduced oxygen carrier to the pyrolysis deoxygenation reactor. One outlet of the pyrolysis deoxygenation reactor is used for the extraction of volatiles, where oxygen-containing hydrocarbons are deoxygenated, condensed, and then used to obtain low-oxygen bio-oil, as well as pyrolysis gas. The other outlet of the pyrolysis deoxygenation reactor is connected to one inlet of the combustion regeneration reactor to send the pyrolysis carbon and low-temperature oxidized oxygen carrier produced in the pyrolysis deoxygenation reactor, as well as the remaining reduced oxygen carrier, to the combustion regeneration reactor. The other inlet of the combustion regeneration reactor is used for air intake. The high-temperature oxidized oxygen carrier, a product of the combustion regeneration reactor, enters the gasification reactor through the outlet, and the product flue gas is extracted from the other outlet.

2. The apparatus for biomass chemical chain deoxygenation pyrolysis to produce oil and co-generate syngas according to claim 1, characterized in that, The gasification reactor is a cross-flow moving bed reactor, the thermal deoxygenation reactor is a moving bed reactor, and the combustion regeneration reactor is a fast fluidized bed reactor.

3. A method for biomass chemical chain deoxygenation pyrolysis to produce oil and co-generate syngas, using the apparatus described in claim 1 or 2, characterized in that, The steps are as follows: Step 1) The high-temperature oxidized oxygen carrier formed in the combustion regeneration reactor enters the gasification reactor, which heats the carbon-containing fuel and causes partial oxidation of the carbon-containing fuel or its pyrolysis volatiles to generate syngas and extract it, while the high-temperature oxidized oxygen carrier is reduced, and at the same time, the medium-temperature solid product carbon from the decomposition of carbon-containing fuel is obtained. Step 2) The biomass and the intermediate-temperature reduced oxygen carrier and solid product char generated in the gasification reactor are transported to the pyrolysis deoxygenation reactor; the biomass is heated and decomposed to produce volatiles and pyrolysis char; under the action of the reduced oxygen carrier, the oxygen-containing hydrocarbons in the pyrolysis volatiles of the biomass are deoxygenated, and after condensation, low-oxygen bio-oil is obtained, and pyrolysis gas is obtained at the same time, while the reduced oxygen carrier is oxidized or partially oxidized. Step 3) The solid products generated in the pyrolytic deoxidation reactor, including pyrolytic carbon, low-temperature oxidized oxygen carrier, and the remaining reduced oxygen carrier, are transported to the combustion regeneration reactor. Under the action of hot air, the pyrolytic carbon and the carbon deposits on the surface of the oxygen carrier are burned, the reduced oxygen carrier is completely oxidized, and the oxygen carrier is heated. After the obtained high-temperature oxidized oxygen carrier is separated from the hot flue gas, it is transported to the gasification reactor for recycling.

4. The method for biomass chemical chain deoxygenation pyrolysis to produce oil and co-generate syngas according to claim 3, characterized in that, In step 1), the carbon-containing fuel is one or a mixture of two or more of the following: solid carbon-containing fuel, liquid carbon-containing fuel, and gaseous carbon-containing fuel.

5. A method for biomass chemical chain deoxygenation pyrolysis to produce oil and co-generate syngas according to claim 4, characterized in that, In step 1), the solid carbon fuel is one or more of biomass, organic solid waste, and low-rank coal; the liquid carbon fuel is waste tar; and the gaseous carbon fuel is petroleum gas.

6. A method for biomass chemical chain deoxygenation pyrolysis to produce oil and co-generate syngas according to claim 3, 4, or 5, characterized in that, In step 2), the biomass is one or a mixture of two or more of the following: wood waste, agricultural straw, sludge, and urban waste.

7. A method for biomass chemical chain deoxygenation pyrolysis to produce oil and co-generate syngas according to claim 3, 4, or 5, characterized in that, In step 1), the oxygen carrier is one or more of a single metal or a mixture of two or more composite metal oxides.

8. A method for biomass chemical chain deoxygenation pyrolysis to produce oil and co-generate syngas according to claim 7, characterized in that, In step 1), the oxygen carrier is one or a mixture of two or more of Fe2O3, Fe3O4, Cr2O3, MnO2, Ca2Fe2O5, CaFe2O4, Cu2Fe2O5, and CuFe2O4.

9. A method for biomass chemical chain deoxygenation pyrolysis to produce oil and co-generate syngas according to claim 3, 4, 5, or 8, characterized in that, The reaction temperature of the gasification reactor is controlled by adjusting the temperature of the oxidized oxygen carrier entering the gasification reactor and its ratio with the carbon-containing fuel. The temperature of the oxidized oxygen carrier is 800-900℃, and the mass ratio of the oxidized oxygen carrier to the carbon-containing fuel is 5-50.

10. A method for biomass chemical chain deoxygenation pyrolysis to produce oil and co-produce syngas according to claim 3, 4, 5, or 8, characterized in that, The reaction temperature of the pyrolysis reactor is controlled by adjusting the temperature of the reduced oxygen carrier entering the pyrolysis reactor. The temperature of the reduced oxygen carrier is 500-700℃.

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