Reactor and biomass gasification and tar conversion method

Abstract

The invention relates to the field of biomass gasification, and discloses a reactor and a biomass gasification and tar conversion method.The reactor comprises a first-section lifting pipe, a settling chamber and a second-section lifting pipe which are sequentially arranged, the first-section lifting pipe is provided with a raw material inlet and a first gasified gas inlet, and an exhaust port of the first-section lifting pipe is connected with the settling chamber; an exhaust port of the settling chamber is connected with a gas inlet in the second-section lifting pipe, the second-section lifting pipe is provided with a second gasified gas inlet, a material storage area is arranged in the settling chamber, the material storage area is connected with a first fluidization gas pipe, and the material storage area is connected with a circulating material inlet of the first-section lifting pipe through a dipleg; according to the reactor disclosed by the invention, biomass gasification and tar conversion in subsequent gas are arranged in different reaction spaces of mutual relay of the same reactor, so that the possibility of mutual influence between two reactions is avoided, the slag-bonding risk is reduced, and converted gas without tar can be obtained at one time.

Description

Technical Field

[0001] This invention relates to the field of biomass gasification, and more specifically to a reactor and a method for biomass gasification and tar conversion. Background Technology

[0002] Biomass is less dependent on location and climate, has relatively abundant and sustainable resources, and is easy to store and convert into liquid, gaseous fuels, as well as other energy forms such as electricity and heat. Furthermore, the CO2 released during the conversion process can be absorbed through photosynthesis during biomass growth, thus achieving CO2 recycling. Its application process results in almost zero carbon emissions. Biomass energy is considered the most promising of all renewable energy sources, including solar energy, and is poised to become the fourth largest energy source after coal, oil, and natural gas.

[0003] Biomass gasification is a process under specific thermodynamic conditions, utilizing air (or oxygen) and water vapor to cause pyrolysis, oxidation, and reduction reforming reactions in biomass polymers, ultimately converting them into combustible gases such as carbon monoxide, hydrogen, and low-molecular-weight hydrocarbons. However, biomass feedstocks have a high content of volatile components, and the gasification products from fluidized bed gasification reactors contain a large amount of tar components. This not only affects the calorific value of the gas and reduces its quality, making it unsuitable for chemical production, but also causes blockages and pollution to downstream pipelines and equipment, affecting the subsequent utilization of the gasification products. Summary of the Invention

[0004] The purpose of this invention is to overcome the problem that the biomass fluidized bed gasification products contain a large amount of tar components in the existing technology, and to provide a reactor and a method for biomass gasification and tar conversion. The reactor sets up biomass gasification and tar conversion in the subsequent gas in different reaction spaces in the same reactor, eliminating the possibility of mutual influence between the two reactions, reducing the risk of slagging, and obtaining tar-free conversion gas in one step.

[0005] To achieve the above objectives, the first aspect of the present invention provides a reactor, comprising a first riser pipe, a settling chamber, and a second riser pipe arranged sequentially, wherein the first riser pipe has a raw material inlet and a first gasification gas inlet, the exhaust port of the first riser pipe is connected to the settling chamber, the exhaust port of the settling chamber is connected to the air inlet of the second riser pipe, and the second riser pipe has a second gasification gas inlet.

[0006] The settling chamber has a material storage area, which is connected to a first fluidizing gas pipe. The material storage area is connected to the circulating material inlet of the section of the riser pipe via a material leg.

[0007] Using the above technical solution, a first-stage riser is used for the gasification reaction of biomass raw materials and gasification gas. The gasified gas undergoes preliminary gas-solid separation in a settling chamber. Solid particles mixed in the gas settle in the settling chamber. The solid particles are kept in a fluidized state under the action of fluidizing gas continuously introduced at the bottom of the settling chamber and are then fed back into the first-stage riser through the feed leg to continue gasification. The gas containing a small amount of solid particles and tar then enters the second-stage riser and mixes with the incoming gasification gas for a secondary reaction. The tar in the gas is converted into syngas, the main effective components of which are hydrogen and carbon monoxide.

[0008] Preferably, a first gas-solid separator is provided in the settling chamber, and a portion of the riser pipe extends into the settling chamber, with its exhaust port connected to the gas inlet of the first gas-solid separator. The exhaust port of the first gas-solid separator is in communication with the settling chamber. This structure, through the built-in first gas-solid separator, can accelerate the separation of solid substances in the gas after the initial gasification, shortening the overall conversion time.

[0009] Preferably, the bottom of the settling chamber forms the storage area, and the bottom of the first gas-solid separator has a discharge pipe that extends into the storage area. The material leg is connected to a second fluidizing gas pipe. With this structure, the solid material separated by the first gas-solid separator is discharged into the storage area of ​​the settling chamber, where it is transformed into a fluid state under the action of fluidizing gas. It is then further returned to a first-stage riser via the material leg for continued circulation and conversion. The first-stage riser, the settling chamber, and the material leg form a circulating fluidized bed reaction system, which is beneficial for improving the gasification efficiency of biomass feedstock and enhancing the quality of the produced gas.

[0010] Preferably, the raw material inlet of the riser section is connected to a feed pipe, which is inclined downwards. The angle between the feed pipe and the riser section is α, where 30°≤α≤45°. In this design, "inclined downwards" means that the feed pipe slopes downwards from the inlet direction to the outlet direction. This structure, employing an inclined feeding method, improves the smoothness of the feeding process.

[0011] Preferably, the diameter of the second-stage riser is larger than that of the first-stage riser. With this structure, the larger diameter of the second-stage riser results in a relatively lower gas velocity within it, which is beneficial for improving the tar conversion rate.

[0012] Preferably, one end of the riser section forms the first gasification gas inlet, a gas distributor is installed inside the riser section between the raw material inlet and the first gasification gas inlet, and the other end of the riser section forms its exhaust port. With this structure, the gas for gasification enters the riser section through the gas distributor, which improves the uniformity of gas distribution, allows for more thorough contact between the biomass raw material and the gas, results in a more stable fluidization state, and higher gasification efficiency.

[0013] Preferably, the exhaust port of the two-stage riser is connected to a second gas-solid separator. With this structure, the solid particles carried in the product gas discharged from the two-stage riser are further separated, meeting the product gas's solid content requirements before it enters the subsequent processing unit.

[0014] Preferably, the settling chamber is provided with a material storage area, a gas-solid separation area, and a gas phase area from bottom to top. The gas-solid separation area is equipped with a first gas-solid separator. A section of the riser extends into the gas-solid separation area, and its exhaust port is connected to the gas inlet of the first gas-solid separator. The exhaust port at the top of the first gas-solid separator is connected to the gas phase area of ​​the settling chamber. With this structure, the first gas-solid separator is generally a built-in cyclone separator, which can be one or more sets. The cyclone separator can effectively accelerate the separation speed and efficiency of gas and solids.

[0015] Preferably, the height of the gas phase zone is 0.5-1.2 times the inner diameter of the settling chamber. This structure helps to reduce the solid content entering the second-stage riser.

[0016] Preferably, a slag discharge pipe is connected to the section of the riser pipe above the gas distributor and below the feed pipe. With this structure, after a period of continuous circulating gasification, a small amount of large particles or lumps of slag will form in the section of the riser pipe. This slag cannot be carried away by the gas, and the slag discharge pipe can be opened periodically to discharge the slag.

[0017] The second aspect of the present invention provides a method for biomass gasification and tar conversion, wherein, in a riser section, biomass feedstock and a first gasification gas are mixed to carry out a first reaction to obtain a first mixed gas, wherein the residence time of the first reaction is 2-4 seconds;

[0018] The first mixed gas is introduced into the settling chamber for the first gas-solid separation to obtain the second mixed gas;

[0019] The second mixed gas is introduced into the second riser and mixed with the second gasified gas to carry out the second reaction to obtain syngas. The solid material obtained after the first gas-solid separation is returned to the first riser. The residence time of the second reaction is 3-7s, the fluidization carry-out velocity of the biomass raw material and the returned solid material is V0, and the gas velocity of the first mixed gas is ≥2V0.

[0020] The residence time of the first and second reactions refers to the residence time of the material in the tube, that is, the time it takes for the material to react.

[0021] Using the above technical solution, the first reaction and the second reaction are carried out independently in different spaces within the same reactor, eliminating mutual influence between the two reactions and reducing the risk of slagging. Furthermore, the material in the first riser is in a high-speed circulating fluidized state. After the first reaction, the obtained gas undergoes preliminary gas-solid separation before the second reaction. The separated solids are fed back to the first riser for regasification, which helps to improve the gasification effect. The gas containing a small amount of solid particles and tar then undergoes tar conversion, where the tar in the gas is converted into high-quality syngas, whose main components are combustible gases such as hydrogen and carbon monoxide.

[0022] Based on the total amount of the biomass raw materials, the amount of oxygen contained in the first gasification gas is 0.2-0.4 times the theoretical amount of oxygen required for the complete combustion of the biomass raw materials, and the amount of oxygen contained in the second gasification gas is the theoretical amount of oxygen required for the complete conversion of the tar contained in the second mixture.

[0023] Preferably, the ratio between the amount of biomass raw material fed in and the amount of returned solid material is 5-80, more preferably 20-50;

[0024] And / or, the V0 is 0.5-2 m / s, and the gas velocity of the first mixed gas is 3-12 m / s.

[0025] The recycling ratio, which is the ratio between the amount of biomass raw material fed in and the amount of the returned solid material, can be any value within the range of any two values ​​from 5, 10, 20, 30, 40, 50, 60, 70, to 80.

[0026] Gas velocity, or apparent gas velocity, refers to the empty pipe gas velocity of the first mixed gas produced. Carry-out velocity refers to the critical gas velocity at which material can be carried away by the gas. In this application, the fluidized bed carry-out velocity is specifically related to the properties of the biomass feedstock.

[0027] The gas velocity of the first mixed gas in this application is much greater than the carry-out velocity of the biomass feedstock and the returned solid material. The gas carries the biomass feedstock and the returned solid material upward. There is no solid material bed in one section of the riser pipe. The entire process is in the conveying bed stage. Compared with the traditional circulating fluidized bed with a solid material bed, the method provided in this application can be adapted to a variety of biomass feedstocks and has a significant advantage in anti-coking performance.

[0028] Through the above technical solution, the two-stage reaction in this application are carried out in corresponding reaction tubes. A first gas-solid separator is installed in the settling chamber between the two reaction tubes for primary dust removal, mainly used to separate unreacted materials and ash. The separated solid material is circulated back to the first-stage riser through the material leg connected to the settling chamber. The first-stage riser + settling chamber + material leg constitute a high-speed circulating fluidized bed, and the second-stage riser constitutes a tar conversion furnace. The two constitute a high-speed circulating fluidized bed coupled with the tar conversion furnace as an integrated unit. The solid content of the gas entering the second-stage riser is greatly reduced. At this time, the second-stage riser is a relatively pure gas phase reactor, which is conducive to improving the tar conversion rate. A second gas-solid separator is installed at the top of the second-stage riser for secondary dust removal.

[0029] This application does not require additional configuration of a tar conversion furnace or other tar removal facilities, and can achieve a biomass gasification reaction outlet that is basically free of tar, with high-quality syngas, ensuring that the unit can operate stably for a long period of time. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the reactor structure.

[0031] Explanation of reference numerals in the attached figures

[0032] 1-First stage riser; 2-Second stage riser; 2a-Second gasification gas inlet; 3-Second gas-solid separator; 4-Settling chamber; 4a-Material storage area; 4b-Gas-solid separation area; 4c-Gas phase area; 5-First gas-solid separator; 6-Material leg; 7-Slag discharge pipe; 8-Gas distributor; 9-Discharge pipe; 10-Feed pipe; 11-First fluidizing gas pipe; 12-Second fluidizing gas pipe; Q1-First gasification gas; Q2-Second gasification gas; Q3-First fluidizing gas; Q4-Second fluidizing gas. Detailed Implementation

[0033] In the description of this application, it should be understood that the terms "upper", "lower", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0034] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0035] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between components; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0036] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0037] Carry-out velocity: refers to the critical gas velocity at which biomass raw materials and returned solid materials can be carried away by gas. This gas velocity is related to particle size, density, etc.

[0038] Gas velocity, or apparent gas velocity, refers to the empty pipe gas velocity of the first mixture produced.

[0039] like Figure 1 As shown in Example 1, a reactor includes a first riser pipe 1, a settling chamber 4, and a second riser pipe 2 arranged sequentially. The first riser pipe 1 has a raw material inlet and a first gasification gas inlet. The exhaust port of the first riser pipe 1 is connected to the settling chamber 4. The exhaust port of the settling chamber 4 is connected to the air inlet of the second riser pipe 2. The second riser pipe 2 has a second gasification gas inlet 2a.

[0040] The settling chamber 4 has a material storage area 4a, which is connected to a first fluidizing gas pipe 11. The material storage area 4a is connected to the circulating material inlet of the section of the lifting pipe 1 through a material leg 6.

[0041] The first riser 1, the settling chamber 4, and the second riser 2 are all vertically arranged. The first riser 1 is used for biomass gasification, and the second riser 2 is used for tar conversion. One end of the first riser 1 forms the first gasification gas inlet, and the side of the first riser 1 near the bottom is provided with the raw material inlet. A gas distributor 8 is installed in the first riser 1 between the raw material inlet and the first gasification gas inlet, and the other end of the first riser 1 forms its exhaust port.

[0042] The raw material inlet of the first-section riser 1 is connected to a feed pipe 10, which is inclined downwards. The angle between the feed pipe 10 and the first-section riser 1 is α, where 30°≤α≤45°. The center line of the feed pipe 10 falls on the center of the gas distributor 8. The raw material inlet is close to the bottom of the first-section riser 1, which makes full use of the first-section riser 1 and helps to improve the gasification effect.

[0043] To facilitate slag discharge, a slag discharge pipe 7 is connected to the section of the riser pipe 1 above the gas distributor 8 and below the feed pipe 10.

[0044] The settling chamber 4 is equipped with a first gas-solid separator 5. The upper end of the first section of the lifting pipe 1 extends into the settling chamber 4, and its exhaust port is connected to the gas inlet of the first gas-solid separator 5. The exhaust port of the first gas-solid separator 5 is connected to the settling chamber 4. Further, the settling chamber 4 has a material storage area 4a at the bottom, a gas-solid separation area 4b in the middle, and a gas phase area 4c at the top. The first gas-solid separator 5 is installed in the gas-solid separation area 4b. After the top of the first section of the lifting pipe 1 extends into the gas-solid separation area 4b, its exhaust port is connected to the inlet of the first gas-solid separator 5. The exhaust port at the top of the first gas-solid separator 5 is connected to the gas phase area 4c of the settling chamber 4. The gas phase area 4c of the settling chamber 4 is also connected to the air inlet at the lower end of the second section of the lifting pipe 2. The height of the gas phase area 4c is 0.5-1.2 times the inner diameter of the settling chamber 4.

[0045] The bottom of the first gas-solid separator 5 has a discharge pipe 9, which extends into the storage area 4a. The storage area 4a is connected to the circulating material inlet of the first section of the riser 1 via a material leg 6. The material leg 6 is connected to a second fluidizing gas pipe 12, which is used to supplement the material in the material leg 6 with gas, so that the material is always in a fluid state for easy transportation. The circulating material inlet of the first section of the riser 1 is close to the lower section of the first section of the riser 1 and is located above the raw material inlet. In this way, the raw material comes into contact with the first gasification gas first, and the mixture is sufficient, which is conducive to gasification.

[0046] The diameter of the second-stage riser 2 is larger than that of the first-stage riser 1. The exhaust port of the second-stage riser 2 is connected to a second gas-solid separator 3. Both the first gas-solid separator 5 and the second gas-solid separator 3 are cyclone separators.

[0047] In operation, first gasification gas Q1 is introduced into the first riser pipe 1 through the first gasification gas inlet, and second gasification gas Q2 is introduced into the second riser pipe 2 through the second gasification gas inlet. First fluidizing gas Q3 is supplied to the storage area 4a through the first fluidizing gas pipe 11, and second fluidizing gas Q4 is supplied to the feed leg 6 through the second fluidizing gas pipe 12. The first fluidizing gas Q3 mainly uses nitrogen, carbon dioxide, steam, or a mixture thereof, or recycled synthesis gas. The second fluidizing gas Q4 is usually steam or air. Furthermore, the residence time of solid material in the storage area 4a can be controlled to 3-5 minutes. The residence time is used to determine the buffer volume of the corresponding storage section, and then the buffer height is calculated. The second gasification gas inlet 2a is about 0.5-1m from the bottom of the second riser pipe 2. This makes full use of the space in the second riser pipe 2 and ensures that the tar conversion is complete and thorough.

[0048] The reactor provided in this example can operate continuously and stably for more than 2400 hours.

[0049] The reactor described in this application can use various biomass raw materials, including one or more of agricultural and forestry waste, domestic waste, and industrial solid waste. The moisture content of the biomass raw materials is 8-15%, and the theoretical oxygen consumption for complete combustion is 500-1000 Nm³. 3 / t, the first gasification gas Q1 and the second gasification gas Q2 used can be one or more of air, oxygen, oxygen-enriched air, water vapor, and hydrogen. Generally, a mixture of oxygen and water vapor is more commonly used. The water vapor mainly serves to dilute the oxygen concentration and act as a fluidizing air control. In this application, the oxygen concentration in the first gasification gas Q1 is controlled at 20-50 v / v%, and the second gasification gas Q2 uses pure oxygen.

[0050] The following describes the biomass gasification and tar conversion based on the reactor of Example 1, taking a biomass feedstock processing capacity of 150 t / d as an example. The first gasification gas Q1 used is a mixture of oxygen and water vapor, and the second gasification gas Q2 is pure oxygen. The biomass feedstock used is compressed corn stalk pellets, and the theoretical oxygen consumption for complete combustion is 3500 Nm³. 3 / h, the oxygen content in the first gasification gas is 0.3 times the amount of oxygen theoretically required for the complete combustion of the input biomass raw material, and the fluidization carry-out velocity of the biomass raw material and the returned solid material is V0, which is 1.2 m / s, as detailed below:

[0051] Example 2

[0052] Biomass raw materials are fed into the section of riser 1 through the feed pipe 10. The first gasification gas enters through the bottom of the section of riser 1. The feed pipe 10 is 0.3m away from the gas distributor 8, and the angle between the feed pipe 10 and the section of riser 1 is 45°.

[0053] The biomass feedstock and the first gasification gas are mixed to carry out a first reaction to obtain a first mixed gas with a flow rate of 8300 m³ / s. 3 / h, select a section of riser 1 with an inner diameter of φ600mm, a gas velocity of 8m / s, a height of 25m, a residence time of 3.1s, and a reaction temperature of 700-850℃.

[0054] The first mixed gas is introduced into the first gas-solid separator 5 in the settling chamber 4 for the first gas-solid separation to obtain the second mixed gas. The first gas-solid separator 5 is selected from multiple small cyclone separators with a gas-solid separation efficiency of ≥90%. The inner diameter of the settling chamber 4 is calculated by controlling the cross-sectional gas velocity in the gas phase zone 4c to not exceed the settling velocity of most of the unreacted particles in the particle size distribution. In this project, the settling velocity of most unreacted particles is above 0.5 m / s, so the inner diameter of the settling chamber 4 is calculated and selected to be 2.5 m. The actual gas velocity in the settling chamber 4 is calculated to be 0.47 m / s. The material in the storage zone 4a is returned to the first section of the riser pipe 1 through the material leg 6. The circulation ratio between the biomass raw material feed rate and the amount of returned solid material is controlled to be 30. The biomass raw material feed rate is: 150 / 24 = 6.25 t / h, and the amount of returned solid material is 6.25 × 30 = 187.5 t / h. The bulk density is 500 kg / m³. 3 The storage zone 4a has a height of 2m. Solid materials are stored between the outer shell of the settling chamber 4 and the outer wall of the section of the riser pipe 1 that extends into the settling chamber 4, where they remain for approximately 3 minutes. The gas-solid separation zone 4b has a height of 4m, depending on the height of the multiple cyclone separators. The gas phase zone 4c has a height of 2m, which is 0.8 times the diameter. The total height of the settling chamber 4 cylindrical section is the sum of the storage zone 4a, the gas-solid separation zone 4b, and the gas phase zone 4c. The total dimensions of the settling chamber 4 cylindrical section are φ2.5 x 8m.

[0055] The second mixed gas discharged from the gas phase zone 4c is introduced into the second-stage riser 2 and mixed with the second gasified gas to carry out a second reaction to obtain syngas. The second-stage riser 2 has multiple second gasified gas inlets 2a at the bottom 0.5-1.0m to inject the second gasified gas for tar conversion. The gas velocity of the second gasified gas in the second-stage riser 2 is 3m / s, the second reaction time is 5s, the diameter of the second-stage riser 2 is φ1000mm, the height is 15m, and the reaction temperature exceeds 900℃.

[0056] The total height of the reactor in this example is 48m.

[0057] 7125 Nm³ based on total syngas volume 3 The resulting synthesis gas consists of 48 v / v% CO, 32 v / v% H2, and 20% inert gases per hour, and is free of tar.

[0058] Example 3

[0059] The process is carried out in accordance with Example 2, with the only difference being that: the gas velocity of the first mixed gas is 12 m / s and the residence time is 2 s; the gas velocity of the second gasified gas in the second-stage riser 2 is 5 m / s; the second reaction time is 3 s; and the circulation ratio between the amount of biomass raw material fed and the amount of returned solid material is 20.

[0060] 6580 Nm³ based on total syngas volume 3 / h, the obtained synthesis gas includes 46v / v% CO, 30v / v% H2, and 24v / v% inert gas, and is free of tar.

[0061] Example 4

[0062] The process is carried out in accordance with Example 2, with the only difference being that: the gas velocity of the first mixed gas is 3 m / s and the residence time is 4 s; the gas velocity of the second gasified gas in the second-stage riser 2 is 4 m / s; the second reaction time is 7 s; and the circulation ratio between the amount of biomass raw material fed and the amount of returned solid material is 50.

[0063] 7200 Nm³ based on total syngas volume 3 The resulting synthesis gas consists of 49 v / v% CO, 33 v / v% H2, and 18 v / v% inert gases per hour, and is free of tar.

[0064] Example 5

[0065] The procedure is carried out in accordance with Example 2, except that the recycling ratio between the amount of biomass raw material fed in and the amount of solid material returned is 5.

[0066] 5300 Nm³ based on total syngas volume 3 The resulting synthesis gas consists of 51 v / v% CO, 34 v / v% H2, and 15 v / v% inert gases per hour, and contains no tar.

[0067] Example 6

[0068] The procedure is carried out in accordance with Example 2, except that the recycling ratio between the amount of biomass raw material fed in and the amount of solid material returned is 80.

[0069] 9670 Nm³ based on total syngas volume 3 The resulting synthesis gas consists of 36 v / v% CO, 24 v / v% H2, and 40 v / v% inert gases per hour, and is free of tar.

[0070] Example 7

[0071] The process is carried out in accordance with Example 2, except that the first mixed gas does not enter the first gas-solid separator 5 in the settling chamber 4, but instead enters the second-stage riser 2 directly after natural settling and separation in the settling chamber 4.

[0072] 6875 Nm³ based on total syngas volume 3 The resulting synthesis gas contains 48 v / v% CO, 32 v / v% H2, and 20% inert gas, and is free of tar. Although the gas production rate has decreased compared to Example 2, it remains at a high level, except that the amount of solids entrained in the gas has increased.

[0073] Considering the overall gas volume and the content of combustible gases in the syngas, the preferred recycle ratio is 20-50.

[0074] Comparative Example 1

[0075] The process is carried out in accordance with Example 2, except that: after the first mixed gas passes through the settling chamber 4 and the first gas-solid separator 5 therein for gas-solid separation, it does not undergo a second-stage reaction and is directly used as the product gas.

[0076] 7070 Nm³ based on total syngas volume 3 / h, the obtained synthesis gas includes 49 v / v% CO, 33 v / v% H2, 18% inert gas, and 10 g / Nm³ tar content. 3 .

[0077] Comparative Example 2

[0078] The procedure is the same as in Example 2, except that the residence time of the second-stage riser is 2 seconds.

[0079] 7070 Nm³ based on total syngas volume 3 / h, the obtained synthesis gas includes 49 v / v% CO, 32 v / v% H2, 19% inert gas, and 5 g / Nm³ tar content. 3 .

[0080] Comparative Example 3

[0081] The process is carried out in accordance with Example 1, with the only difference being that the gas velocity of the first mixed gas is 2 m / s, the residence time in the first riser 1 is 1 s, and the residence time in the second riser 2 is 5 s.

[0082] 7200 Nm³ based on total syngas volume 3The obtained synthesis gas consists of 48 v / v% CO, 32 v / v% H2, and 20% inert gas, and contains no tar. The gas production rate does not change much, but the reactor diameter increases significantly due to the low gas velocity, and coking easily occurs in a section of the riser, which makes it impossible for the reactor to operate continuously for a long time.

[0083] Comparative Example 4

[0084] The process is carried out in accordance with Example 2, with the only difference being that the gas velocity of the first mixed gas is 15 m / s, the residence time in the first riser 1 is 1.6 s, and the residence time in the second riser 2 is 5 s.

[0085] 6800 Nm³ based on total syngas volume 3 The obtained synthesis gas consists of 45 v / v% CO, 30 v / v% H2, and 25% inert gas, and is free of tar. However, the reactor wear is severe due to the high gas velocity, resulting in a short reactor lifespan.

[0086] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A reactor characterized by, The riser comprises a first riser, a settling chamber and a second riser arranged in sequence, wherein the first riser is provided with a raw material inlet and a first gasification gas inlet, the exhaust port of the first riser is connected with the settling chamber, the exhaust port of the settling chamber is connected with the gas inlet of the second riser, and the second riser is provided with a second gasification gas inlet; The settling chamber is provided with a storage area connected with a first fluidizing gas pipe, and the storage area is connected with the circulating material inlet of the first riser through a material leg.

2. The reactor of claim 1, wherein, The settling chamber is provided with a first gas-solid separator, and a part of the first riser extends into the settling chamber, and the exhaust port of the first riser is connected with the gas inlet of the first gas-solid separator, and the exhaust port of the first gas-solid separator is communicated with the settling chamber.

3. The reactor of claim 2, wherein, The bottom of the settling chamber forms the storage area, the bottom of the first gas-solid separator is provided with a discharge pipe extending into the storage area, and the material leg is connected with a second fluidizing gas pipe.

4. The reactor according to any one of claims 1 to 3, characterized in that The raw material inlet of the first riser is connected with a feeding pipe, the feeding pipe is arranged in a downward inclined manner, the included angle between the feeding pipe and the first riser is α, and 30°≤α≤45°.

5. The reactor of claim 4, wherein, The diameter of the second riser is larger than that of the first riser.

6. The reactor of claim 5, wherein, One end of the first riser forms the first gasification gas inlet, a gas distributor is arranged in the first riser between the raw material inlet and the first gasification gas inlet, and the other end of the first riser forms the exhaust port thereof.

7. The reactor of claim 6, wherein, The exhaust port of the second riser is connected with a second gas-solid separator.

8. The reactor of claim 3, wherein, The settling chamber is provided with the storage area and a gas-solid separation area, and a gas phase area arranged in sequence from bottom to top, the gas-solid separation area is provided with the first gas-solid separator, the first riser extends into the gas-solid separation area, the exhaust port of the first riser is connected with the gas inlet of the first gas-solid separator, and the exhaust port at the top of the first gas-solid separator is communicated with the gas phase area of the settling chamber. Preferably, the height of the gas phase area is 0.5-1.2 times the inner diameter of the settling chamber.

9. A method of biomass gasification and tar conversion, characterized by, The biomass raw material and the first gasification gas are mixed in the first riser to perform a first reaction to obtain a first mixed gas, wherein the residence time of the first reaction is 2-4s; The first mixed gas is introduced into the settling chamber to perform a first gas-solid separation to obtain a second mixed gas; The second mixed gas is introduced into the second riser and mixed with the second gasification gas to perform a second reaction to obtain a synthesis gas, and the solid material obtained after the first gas-solid separation is returned to the first riser, wherein the residence time of the second reaction is 3-7s, the fluidization entrainment velocity of the biomass raw material and the returned solid material is V0, and the gas velocity of the first mixed gas is ≥2V0.

10. The method of claim 9, wherein, The ratio between the feeding amount of the biomass raw material and the amount of the returned solid material is 5-80, preferably 20-50. And / or, the gas velocity of the first mixed gas is 3-12m / s.

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