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

Abstract

The invention discloses a process for converting biomass particles into synthesis gas by using pressurized bubbling fluidized bed equipment. The process comprises the following steps: feeding the biomass particles and fluidizing agent particles as raw materials into a gasification furnace; the gasification furnace comprises a fluidized bed area, a secondary gasification area and a post gasification area; a plurality of layers of gasification nozzles are designed in the gasification furnace, tar generated by biomass gasification can fully react in a high-temperature area of the gasification furnace, and synthesis gas generated by the pressurized bubbling fluidized bed gasification furnace enters a cyclone separator to be separated and then enters a synthesis gas cooler to be cooled; the cooled synthesis gas enters a synthesis gas filter, and the filtered synthesis gas enters a shock cooling system; the synthesis gas filtered by the synthesis gas filter enters a quench cooler of the quench system to be fully contacted with water for cooling and then enters a washing tower for washing, and the cooled and washed synthesis gas enters a downstream area; according to the invention, biomass ash fusion is reduced; and tar is reduced and eliminated.

Description

Technical Field

[0001] The 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 is a raw gas with carbon monoxide and hydrogen as its main components and is used as a chemical raw material. The raw materials of synthesis gas range very wide, which can be produced by gasification of solid fuels such as coal or coke, or by light hydrocarbons such as natural gas and naphtha, or by partial oxidation of heavy oil.

[0003] The technical background of syngas preparation involves a variety of raw materials and process methods, mainly including: solid fuel: coal, coke, biomass, etc. produce syngas through gasification process; light hydrocarbons: natural gas, naphtha, etc. are produced through reforming or partial oxidation; heavy oil: produced through partial oxidation; others: agricultural and forestry waste, urban garbage, etc. can also be used for syngas preparation. The main process flow for preparing syngas includes gasification: solid fuel reacts with gasifying agent (usually oxygen and steam) at high temperature to produce syngas; common gasification methods include fixed bed, fluidized bed and fluidized bed gasification; reforming: light hydrocarbons (such as natural gas, naphtha) produce syngas through reforming reaction, and the reforming reaction can be carried out in the presence of a catalyst to improve the yield and purity; partial oxidation: heavy oil produces syngas through partial oxidation, which is usually carried out at high temperature 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 easy to melt and agglomerate at the bottom of the fluidized bed gasifier, blocking the equipment and affecting the gasification effect. Other biomass gasification technologies produce a large amount of tar after gasifying 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 a plurality of gasification nozzles are designed in the gasifier and distributed at the bottom and the 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] The biomass particles and the 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 comprises 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 manner in the fluidized bed area, and the gasifying agent nozzles are arranged in a multi-layer annular manner in the fluidized bed area and the secondary gasification area;

[0013] In the fluidized bed area, the biomass particles and the fluidizing agent particles are agitated up and down by the fluidizing gas and contact the gasifying agent; the biomass particles are partially oxidized and gasified by the gasifying agent and enter the secondary gasification area, where they continue to contact the gasifying agent. The tar produced during the gasification process will decompose in this area; then the gas and the ungasified particles enter the post-gasification area, where synthesis gas 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 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 bucket conveying system for collection and transportation 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 quench cooler of the quench 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 silicon dioxide (SiO 2 ), aluminum oxide (Al 2 O 3 ), iron oxide (Fe 2 O 3 ), a mixture of 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 subsequent gas and ungasified particles 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 the ungasified particles into the 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 granular 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, thereby reducing and eliminating the 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 to cause 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 middle and lower high-temperature area of ​​the gasifier, and can reduce and eliminate the tar. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, some of the drawings described below are some implementation methods 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 is a process flow chart of Example 1 of the present invention;

[0037] Among them, 1. gasification furnace; 2. cyclone separator; 3. synthesis gas cooler; 4. synthesis gas filter; 5. quench cooler; 6. washing tower; 7. lock hopper feeding system; 8. biomass particle storage tank; 9. fluidizing agent particle storage tank; 10. slag lock hopper conveying system; 11. ash lock hopper 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 in conjunction with the embodiments, but the present invention is not limited to the following embodiments. The implementation conditions used in the embodiments can be further adjusted according to the different requirements of specific use, and the implementation conditions not indicated are conventional conditions in the industry. The technical features involved in each embodiment of the present invention can 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 device, comprising the following steps:

[0042] S1. Feed supply:

[0043] Biomass particles in a biomass particle storage tank (8) and fluidizing agent particles in a fluidizing agent particle storage tank (9) are transported as raw materials to a gasifier (1) through a lock hopper feeding system (7) and a multi-stage screw, wherein the biomass particles include particles made of agricultural and forestry wastes; the fluidizing agent particles include silicon dioxide (SiO 2 ), aluminum oxide (Al2 O 3 ), iron oxide (Fe 2 O 3 ), a mixture of 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 MPag;

[0046] In the fluidized bed area, the biomass particles and the fluidizing agent particles are agitated up and down by the fluidizing gas and contact the gasifying agent, and 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 area, where they continue to contact the gasifying agent and the temperature is controlled at 1200°C. The tar produced during the gasification process in this area will decompose; then the gas and the ungasified particles enter the post-gasification area, where the temperature is controlled at 200°C below the melting point of the raw ash, and synthesis gas is produced in this area;

[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 part of the particulate matter is returned 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 into 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 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) to be collected and transported to other areas;

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

[0056] The ungasified particles separated from the synthesis gas filter (4) after filtering enter the ash lock hopper conveying system (11) to be collected and conveyed 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) for full contact with water to reduce the temperature, and then enters the washing tower (6) for water washing. The synthesis gas after cooling and water 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 device, 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. The biomass particles include particles made of agricultural and forestry wastes; the fluidizing agent particles include silicon dioxide (SiO 2 ), aluminum oxide (Al 2 O 3 ), iron oxide (Fe 2 O 3 ), a mixture of calcium oxide (CaO) particles;

[0063] S2. Preparation of Synthesis Gas in a Pressurized Bubbling Fluidized Bed Gasifier:

[0064] The gasifier comprises 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 ring in the fluidized bed area, and the gasifying agent nozzles are arranged in a multi-layer ring in 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 4.0MPag;

[0065] In the fluidized bed area, the biomass particles and the fluidizing agent particles are agitated up and down by the fluidizing gas and contact the gasifying agent, and 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 area, where they continue to contact the gasifying agent and the temperature is controlled at 1300°C. The tar produced during the gasification process in this area will decompose; then the gas and the ungasified particles enter the post-gasification area, where the temperature is controlled at 250°C below the melting point of the raw ash, and synthesis gas is produced in this area;

[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] The syngas separated by the cyclone separator carries the ungasified particles into the syngas cooler to be cooled to 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.

[0070] S5, Syngas 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 bucket conveying system for collection and transportation 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 quench cooler of the quench 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 to make the temperature of the fluidized bed area uniform, avoid local excessive temperature in the fluidized bed area to avoid biomass ash melting and agglomeration, and the Ca additive added in 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 the 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-mentioned embodiments only express two implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached 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: The biomass particles and the 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 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 manner in the fluidized bed area, and the gasifying agent nozzles are arranged in a multi-layer annular manner in the fluidized bed area and the secondary gasification area; In the fluidized bed area, the biomass particles and the fluidizing agent particles are agitated up and down by the fluidizing gas and contact the gasifying agent; the biomass particles are partially oxidized and gasified by the gasifying agent and enter the secondary gasification area, where they continue to contact the gasifying agent. The tar produced during the gasification process will decompose in this area; then the gas and the ungasified particles enter the post-gasification area, where synthesis gas 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 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 bucket conveying system for collection and transportation 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 synthesis gas filtered by the synthesis gas filter enters the quench cooler of the quench 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.

2. A process for converting biomass particles into synthesis gas using a pressurized bubbling fluidized bed apparatus as claimed in claim 1, characterized in that: In step S1, the biomass particles include particles made from agricultural and forestry waste.

3. A process for converting biomass particles into synthesis gas using a pressurized bubbling fluidized bed apparatus as claimed in claim 1, characterized in that: In step S1, the fluidizing agent particles include a mixture of silicon dioxide, aluminum oxide, iron oxide, and calcium oxide particles.

4. A process for converting biomass particles into synthesis gas using a pressurized bubbling fluidized bed apparatus as claimed in claim 1, characterized in that: 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.

5. A process for converting biomass particles into synthesis gas using a pressurized bubbling fluidized bed apparatus as claimed in claim 1, characterized in that: 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 and fluidizing agent particles in the secondary gasification area continue to contact the gasifying agent, and the temperature is controlled at 1000-1300°C; the subsequent gas and ungasified particles 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.

6. A process for converting biomass particles into synthesis gas using a pressurized bubbling fluidized bed apparatus as claimed in claim 1, characterized in that: In step S4, the synthesis gas separated by the cyclone separator carries the ungasified particles into the synthesis gas cooler and is cooled to 350-450°C.

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