Process for converting biomass particles into synthesis gas using pressurized bubbling fluidized bed equipment

Abstract

The present invention discloses a process for converting biomass particles into synthesis gas using a pressurized bubbling fluidized bed device, comprising: delivering biomass particles and fluidizing agent particles as raw materials to a gasifier; the gasifier comprises a fluidized bed area, a secondary gasification area and a post-gasification area; a multi-layer gasification nozzle is designed in the gasifier, so that the tar produced by the biomass gasification can be fully reacted in the high-temperature area of ​​the gasifier, the synthesis gas produced by the pressurized bubbling fluidized bed gasifier enters a cyclone separator, and the synthesis gas after separation enters a synthesis gas cooler for cooling; the cooled synthesis gas enters a synthesis gas filter, and the filtered synthesis gas enters a quenching system; the synthesis gas filtered by the synthesis gas filter enters a quenching system's quenching system, is fully contacted with water for cooling, and then enters a washing tower for water washing, and the synthesis gas after cooling and water washing will enter a downstream area; the present invention reduces biomass ash melting and reduces and eliminates tar.

Description

Technical Field

[0001] The present invention relates to the technical field of synthesis gas preparation, and in particular to a process for converting biomass particles into synthesis gas using a pressurized bubbling fluidized bed device. Background Art

[0002] Synthesis gas, primarily composed of carbon monoxide and hydrogen, is used as a raw material in chemical production. Synthesis gas can be produced from a wide range of sources, including the gasification of solid fuels such as coal or coke, light hydrocarbons such as natural gas and naphtha, and partial oxidation of heavy oil.

[0003] The technical background of syngas production involves a variety of raw materials and process methods, mainly including: solid fuels: coal, coke, biomass, etc. are produced through gasification processes to produce syngas; light hydrocarbons: natural gas, naphtha, etc. are produced through reforming or partial oxidation methods; heavy oil: produced through partial oxidation methods; other: agricultural and forestry waste, municipal waste, etc. can also be used to produce syngas. The main process flows for producing syngas include gasification: solid fuel reacts with a gasifying agent (usually oxygen and steam) at high temperatures to produce syngas; common gasification methods include fixed bed, fluidized bed, and entrained flow gasification; reforming: light hydrocarbons (such as natural gas and naphtha) are produced through reforming reactions. Reforming reactions can be carried out in the presence of catalysts to improve yield and purity; partial oxidation: heavy oil is produced through partial oxidation methods. This method is usually carried out at high temperatures and produces a large amount of heat energy and syngas.

[0004] However, the ash of biomass raw materials has a low melting point and is easily melted and agglomerated at the bottom of the fluidized bed gasifier, clogging the equipment and affecting the gasification effect. Other biomass gasification technologies produce a large amount of tar after gasifying the biomass.

[0005] Therefore, the present invention provides a process for converting biomass particles into synthesis gas using a pressurized bubbling fluidized bed device; it is a pressurized bubbling fluidized bed gasification technology, in which multiple layers of gasification nozzles are designed in the gasifier, distributed at the bottom and middle of the pressurized gasifier, so that the tar produced by biomass gasification can be fully reacted in the high-temperature zone in the middle of the gasifier, thereby reducing and eliminating the tar. Summary of the Invention

[0006] The purpose of the present invention is to provide a process for converting biomass particles into synthesis gas using a pressurized bubbling fluidized bed device, thereby filling the gap in the current technology.

[0007] The purpose of the present invention is achieved through the following technical solutions:

[0008] A process for converting biomass particles into synthesis gas using a pressurized bubbling fluidized bed apparatus comprises the following steps:

[0009] S1. Feed supply:

[0010] Biomass particles and fluidizing agent particles are transported as raw materials to the gasifier through a lock hopper feeding system and a multi-stage screw;

[0011] S2. Preparation of synthesis gas in a pressurized bubbling fluidized bed gasifier:

[0012] The gasifier includes a fluidized bed area, a secondary gasification area, and a post-gasification area; the fluidized bed area is a bubbling fluidized bed area located at the bottom of the gasifier; the secondary gasification area is located in the middle and lower part of the gasifier; the post-gasification area is located in the middle and upper part of the gasifier; the fluidizing gas nozzles are arranged in a multi-layer annular arrangement in the fluidized bed area, and the gasifying agent nozzles are arranged in a multi-layer annular arrangement in the fluidized bed area and the secondary gasification area;

[0013] In the fluidized bed, biomass particles and fluidizing agent particles are driven up and down by the fluidizing gas and come into contact with the gasifying agent. Under the action of the gasifying agent, the biomass particles are partially oxidized and gasified and enter the secondary gasification zone, where they continue to come into contact with the gasifying agent. The tar produced during the gasification process decomposes in this zone. Subsequently, the gas and ungasified particles enter the post-gasification zone, where syngas is produced.

[0014] S3, cyclone separator separation:

[0015] The syngas produced by the gasifier carries ungasified particles into the cyclone separator for separation, and some of the particulate matter is returned to the fluidized bed area of ​​the gasifier;

[0016] S4. Syngas cooler cooling:

[0017] The syngas separated by the cyclone separator carries ungasified particles into the syngas cooler for cooling;

[0018] S5, Syngas Filter Filtration:

[0019] The cooled syngas carries ungasified particles into the syngas filter, and the filtered syngas enters the quenching system;

[0020] S6, slag lock bucket conveying system conveys slag:

[0021] The slag discharged from the bottom of the gasifier enters the slag lock hopper conveying system and is collected and transported to other areas;

[0022] S7, ash lock hopper conveying system ash transport:

[0023] The ungasified particles separated from the syngas filter enter the ash lock hopper conveying system and are collected and transported to other areas;

[0024] S8, quenching system:

[0025] The synthesis gas filtered by the synthesis gas filter enters the quencher of the quenching system and is fully contacted with water to cool it down, and then enters the washing tower for water washing. The synthesis gas after cooling and washing will enter the downstream area.

[0026] Preferably, in step S1, the biomass particles include particles made from agricultural and forestry waste.

[0027] Preferably, in step S1, the fluidizing agent particles include a mixture of silicon dioxide (SiO2), aluminum oxide (Al2O3), iron oxide (Fe2O3), and calcium oxide (CaO) particles.

[0028] Preferably, in step S2, the fluidizing gas in the fluidized bed region is steam and carbon dioxide, the gasifying agent is steam and oxygen, and the operating pressure of the gasifier is 0.0 MPag to 6.0 MPag.

[0029] Preferably, in step S2, the biomass particles and fluidizing agent particles in the fluidized bed area are agitated up and down by the fluidizing gas and contact the gasifying agent, and the temperature is controlled at 250-350°C below the melting point of the raw ash; the contact with the gasifying agent in the secondary gasification area is controlled at 1000-1300°C; the gas and ungasified particles then enter the post-gasification area, and the temperature of the post-gasification area is controlled at 150-250°C below the melting point of the raw ash.

[0030] Preferably, in step S4, the syngas separated by the cyclone separator carries ungasified particles into a syngas cooler and is cooled to 350-450° C.; at the same time, the heat of the syngas removed by the syngas cooler can be used as a heat source to generate steam.

[0031] Working mechanism of the present invention:

[0032] Biomass pellet raw materials are used and a certain proportion of fluidizing agent is added. The fluidizing agent enhances the heat transfer effect in the fluidized bed area of ​​the gasifier to make the temperature of the fluidized bed area uniform, avoid local excessive temperature in the fluidized bed area, and cause biomass ash melting and agglomeration. The Ca additive added to the fluidizing agent can change the ash melting characteristics and reduce biomass ash melting; a multi-layer gasification nozzle is designed in the gasifier, distributed at the bottom and middle and lower parts of the pressurized gasifier, so that the tar produced by biomass gasification can be fully reacted in the high-temperature area in the middle and lower part of the gasifier, which can reduce and eliminate tar.

[0033] Due to the application of the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0034] The present invention can enhance the heat transfer effect in the fluidized bed area of ​​the gasifier to make the temperature of the fluidized bed area uniform, avoid local excessive temperature in the fluidized bed area causing biomass ash melting and agglomeration, and can reduce biomass ash melting; the present invention can fully react the tar produced by biomass gasification in the high-temperature area in the lower middle part of the gasifier, and can reduce and eliminate the tar. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the specific embodiments or the description of the prior art. Obviously, some of the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be made based on these drawings without paying any creative work.

[0036] Figure 1 This is a process flow chart of Example 1 of the present invention;

[0037] Among them, 1. Gasifier; 2. Cyclone separator; 3. Syngas cooler; 4. Syngas filter; 5. Quench cooler; 6. Scrubber; 7. Bucket feeding system; 8. Biomass pellet storage tank; 9. Fluidizing agent pellet storage tank; 10. Slag bucket conveying system; 11. Ash bucket conveying system. DETAILED DESCRIPTION

[0038] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, a specific implementation scheme is now described in detail.

[0039] The present invention is further described below with reference to the following examples, but the present invention is not limited to the following examples. The implementation conditions used in the examples can be further adjusted according to the specific requirements of the application. The implementation conditions not specified are conventional conditions in the industry. The technical features involved in the various embodiments of the present invention may be combined with each other as long as they do not conflict with each other.

[0040] Example 1

[0041] See attached Figure 1 This embodiment provides a process for converting biomass particles into synthesis gas using a pressurized bubbling fluidized bed apparatus, comprising the following steps:

[0042] S1. Feed supply:

[0043] The biomass particles in the biomass particle storage tank (8) and the fluidizing agent particles in the fluidizing agent particle storage tank (9) are transported as raw materials to the gasifier (1) through a lock hopper feeding system (7) and a multi-stage screw, wherein the biomass particles include particles made from agricultural and forestry waste; and the fluidizing agent particles include a mixture of silicon dioxide (SiO2), aluminum oxide (Al2O3), iron oxide (Fe2O3), and calcium oxide (CaO) particles;

[0044] S2. Preparation of synthesis gas in a pressurized bubbling fluidized bed gasifier:

[0045] The gasifier comprises a fluidized bed region, a secondary gasification region and a post-gasification region; the fluidized bed region is a bubbling fluidized bed region, located at the bottom of the gasifier (1); the secondary gasification region is located in the middle and lower part of the gasifier (1); the post-gasification region is located in the middle and upper part of the gasifier (1); fluidizing gas nozzles are arranged in a multi-layer annular manner in the fluidized bed region, and gasifying agent nozzles are arranged in a multi-layer annular manner in the fluidized bed region and the secondary gasification region; the fluidizing gas in the fluidized bed region uses steam and carbon dioxide, and the gasifying agent uses steam and oxygen, and the operating pressure of the gasifier is 3.0 MPa.

[0046] In the fluidized bed, biomass particles and fluidizing agent particles are driven up and down by the fluidizing gas and come into contact with the gasifying agent. The temperature is controlled at 300°C below the melting point of the raw ash. The biomass particles are partially oxidized and gasified by the gasifying agent and enter the secondary gasification zone. In this zone, they continue to come into contact with the gasifying agent and the temperature is controlled at 1200°C. The tar produced during the gasification process decomposes in this zone. The gas and ungasified particles then enter the post-gasification zone. The temperature of the post-gasification zone is controlled at 200°C below the melting point of the raw ash, and synthesis gas is produced in this zone.

[0047] S3, cyclone separator separation:

[0048] The synthesis gas produced by the gasifier (1) carries ungasified particles into the cyclone separator (2) for separation, and returns part of the particulate matter to the fluidized bed area of ​​the gasifier (1);

[0049] S4. Syngas cooler cooling:

[0050] The syngas separated by the cyclone separator (2) carries the ungasified particles and enters the syngas cooler (3) to be cooled to 400°C. At the same time, the heat of the syngas removed by the syngas cooler (3) can be used as a heat source to generate steam.

[0051] S5, Syngas Filter Filtration:

[0052] The cooled syngas carries ungasified particles into the syngas filter (4), and the filtered syngas enters the quenching system;

[0053] S6, slag lock bucket conveying system conveys slag:

[0054] The slag discharged from the bottom of the gasifier enters the slag lock bucket conveying system (10) and is collected and transported to other areas;

[0055] S7, ash lock hopper conveying system ash transport:

[0056] The ungasified particles separated from the syngas filter (4) after filtration enter the ash lock hopper conveying system (11) and are collected and transported to other areas;

[0057] S8, quenching system:

[0058] The synthesis gas filtered by the synthesis gas filter (4) enters the quenching system's quencher (5) and is fully contacted with water to cool it down, and then enters the washing tower (6) for water washing. The synthesis gas after cooling and washing will enter the downstream area.

[0059] Example 2

[0060] This embodiment provides a process for converting biomass particles into synthesis gas using a pressurized bubbling fluidized bed apparatus, comprising the following steps:

[0061] S1. Feed supply:

[0062] The biomass particles in the biomass particle storage tank and the fluidizing agent particles in the fluidizing agent particle storage tank are transported as raw materials to the gasifier through a lock hopper feeding system and a multi-stage screw, wherein the biomass particles include particles made from agricultural and forestry wastes; and the fluidizing agent particles include a mixture of silicon dioxide (SiO2), aluminum oxide (Al2O3), iron oxide (Fe2O3), and calcium oxide (CaO) particles;

[0063] S2. Preparation of synthesis gas in a pressurized bubbling fluidized bed gasifier:

[0064] The gasifier includes a fluidized bed area, a secondary gasification area, and a post-gasification area. The fluidized bed area is a bubbling fluidized bed area located at the bottom of the gasifier; the secondary gasification area is located in the lower middle part of the gasifier; and the post-gasification area is located in the middle and upper parts of the gasifier. Fluidizing gas nozzles are arranged in a multi-layer annular pattern within the fluidized bed area, and gasifying agent nozzles are arranged in a multi-layer annular pattern within the fluidized bed area and the secondary gasification area. The fluidizing gas in the fluidized bed area uses steam and carbon dioxide, and the gasifying agent uses steam and oxygen. The operating pressure of the gasifier is 4.0 MPa.

[0065] In the fluidized bed, biomass particles and fluidizing agent particles are driven up and down by the fluidizing gas and come into contact with the gasifying agent. The temperature is controlled at 280°C, below the melting point of the raw ash. The biomass particles are partially oxidized and gasified by the gasifying agent and enter the secondary gasification zone. In this zone, they continue to come into contact with the gasifying agent and the temperature is controlled at 1300°C. The tar produced during the gasification process decomposes in this zone. The gas and ungasified particles then enter the post-gasification zone. The temperature of the post-gasification zone is controlled at 250°C, below the melting point of the raw ash, and synthesis gas is produced in this zone.

[0066] S3, cyclone separator separation:

[0067] The syngas produced by the gasifier carries ungasified particles into the cyclone separator for separation, and some of the particulate matter is returned to the fluidized bed area of ​​the gasifier;

[0068] S4. Syngas cooler cooling:

[0069] After separation in the cyclone separator, the syngas carrying ungasified particles enters the syngas cooler for cooling to 450°C. At the same time, the heat removed from the syngas in the syngas cooler can be used as a heat source to generate steam.

[0070] S5, Syngas Filter Filtration:

[0071] The cooled syngas carries ungasified particles into the syngas filter, and the filtered syngas enters the quenching system;

[0072] S6, slag lock bucket conveying system conveys slag:

[0073] The slag discharged from the bottom of the gasifier enters the slag lock hopper conveying system and is collected and transported to other areas;

[0074] S7, ash lock hopper conveying system ash transport:

[0075] The ungasified particles separated from the syngas filter enter the ash lock hopper conveying system and are collected and transported to other areas;

[0076] S8, quenching system:

[0077] The synthesis gas filtered by the synthesis gas filter enters the quencher of the quenching system and is fully contacted with water to cool it down, and then enters the washing tower for water washing. The synthesis gas after cooling and washing will enter the downstream area.

[0078] The present invention adopts biomass particle raw material and adds a certain proportion of fluidizing agent. The fluidizing agent enhances the heat transfer effect in the fluidized bed area of ​​the gasifier, makes the temperature of the fluidized bed area uniform, avoids the local excessive temperature in the fluidized bed area and causes biomass ash melting and agglomeration, and the Ca additive added to the fluidizing agent can change the ash melting characteristics and reduce biomass ash melting; a multi-layer gasification nozzle is designed in the gasifier, distributed at the bottom and middle and lower parts of the pressurized gasifier, so that the tar generated by biomass gasification can be fully reacted in the high-temperature area in the middle and lower part of the gasifier, thereby reducing and eliminating the tar.

[0079] The above-described embodiments merely represent two implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the spirit of the present invention, and these modifications and improvements fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A process for converting biomass particles into synthesis gas using a pressurized bubbling fluidized bed apparatus, characterized in that: The steps include: S1. Feed supply: Biomass particles and fluidizing agent particles are transported as raw materials to the gasifier through a lock hopper feeding system and a multi-stage screw; S2. Preparation of synthesis gas in a pressurized bubbling fluidized bed gasifier: The gasifier comprises a fluidized bed region, a secondary gasification region, and a post-gasification region; the fluidized bed region is a bubbling fluidized bed region located at the bottom of the gasifier; the secondary gasification region is located in the middle and lower part of the gasifier; the post-gasification region is located in the middle and upper part of the gasifier; the fluidizing gas nozzles are arranged in a multi-layer annular arrangement in the fluidized bed region, and the gasifying agent nozzles are arranged in a multi-layer annular arrangement in the fluidized bed region and the secondary gasification region; In the fluidized bed, biomass particles and fluidizing agent particles are driven up and down by the fluidizing gas and come into contact with the gasifying agent. Under the action of the gasifying agent, the biomass particles are partially oxidized and gasified and enter the secondary gasification zone, where they continue to come into contact with the gasifying agent. The tar produced during the gasification process decomposes in this zone. Subsequently, the gas and ungasified particles enter the post-gasification zone, where syngas is produced. S3, cyclone separator separation: The syngas produced by the gasifier carries ungasified particles into the cyclone separator for separation, and some of the particulate matter is returned to the fluidized bed area of ​​the gasifier; S4. Syngas cooler cooling: The syngas separated by the cyclone separator carries ungasified particles into the syngas cooler for cooling; S5, Syngas Filter Filtration: The cooled syngas carries ungasified particles into the syngas filter, and the filtered syngas enters the quenching system; S6, slag lock bucket conveying system conveys slag: The slag discharged from the bottom of the gasifier enters the slag lock hopper conveying system and is collected and transported to other areas; S7, ash lock hopper conveying system ash transport: The ungasified particles separated from the syngas filter enter the ash lock hopper conveying system and are collected and transported to other areas; S8, quenching system: The syngas filtered by the syngas filter enters the quencher of the quenching system and is fully contacted with water to cool it down before entering the scrubber for water washing. The cooled and washed syngas will enter the downstream area. In step S1, the fluidizing agent particles include a mixture of silicon dioxide, aluminum oxide, iron oxide and calcium oxide particles; In step S2, the fluidizing gas in the fluidized bed region is steam and carbon dioxide, the gasifying agent is steam and oxygen, and the operating pressure of the gasifier is 0.0 MPag to 6.0 MPag; In step S2, the biomass particles and fluidizing agent particles in the fluidized bed area are agitated up and down by the fluidizing gas and contact the gasifying agent, and the temperature is controlled at 250-350°C below the melting point of the raw ash; the biomass particles continue to contact the gasifying agent in the secondary gasification area, and the temperature is controlled at 1000-1300°C; the gas and ungasified particles then enter the post-gasification area, and the temperature of the post-gasification area is controlled at 150-250°C below the melting point of the raw ash.

2. The process for converting biomass particles into synthesis gas using a pressurized bubbling fluidized bed apparatus according to claim 1, wherein: In step S1, the biomass particles include particles made from agricultural and forestry waste.

3. The process for converting biomass particles into synthesis gas using a pressurized bubbling fluidized bed apparatus according to claim 1, wherein: In step S4, the syngas separated by the cyclone separator carries the ungasified particles into the syngas cooler and is cooled to 350-450°C.

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