Entrained flow gasification apparatus

Abstract

The present disclosure relates to an entrained flow gasification device, comprising: a first reaction chamber; a second reaction chamber; and a connecting channel connected to an outlet end of the first reaction chamber and an inlet end of the second reaction chamber, so that the gas flow in the first reaction chamber is ejected into the second reaction chamber and forms an entrainment zone at the inlet end of the second reaction chamber. The present disclosure provides a multi-stage reaction structure of the first reaction chamber, the connecting channel and the second reaction chamber, so that the unreacted carbon particles in the first reaction chamber can continue to participate in the gasification reaction in the connecting channel and the second reaction chamber, and the connecting channel forms an entrainment zone at the inlet end of the second reaction chamber, in which the high-speed jet flow from the first reaction chamber produces strong entrainment and backflow of the surrounding gas, significantly enhancing the mixing, collision and mass transfer between the unreacted carbon particles and the gasification agent, creating excellent conditions for the secondary gasification reaction, thereby improving the gasification reaction rate.

Description

Technical Field

[0001] This disclosure generally relates to the field of fluidized bed gasification technology, and more specifically, to a fluidized bed gasification apparatus. Background Technology

[0002] In recent years, gasification technology has developed rapidly, with gasification feedstocks covering a wide range of carbonaceous materials such as coal, biomass, organic wastewater, organic solvents, and municipal sludge. Gasification technologies include fixed-bed, fluidized-bed, and entrained-flow gasification. Among these, entrained-flow gasification technology, due to its outstanding environmental and economic performance, has been widely used in methanol production, ammonia synthesis, and hydrogen production. Currently, entrained-flow gasification technology using pulverized coal as feedstock typically has an effective gas content of around 92%. Entrained-flow gasification technology using coal-water slurry as feedstock typically has an effective gas content of around 80%, which can be increased to around 84% using coal slurry enrichment technology, but the residual carbon in the fine slag remains as high as 25%–35%. Entrained-flow gasification uses a liquid slag discharge method. This process requires controlling the gasification temperature in the reaction chamber at 50–100°C above the ash melting point of the feedstock. This temperature requirement also constitutes an upper limit factor restricting the length of the combustion chamber, significantly inhibiting this part of the reaction and affecting further improvements in effective gas yield. Summary of the Invention

[0003] In view of this, the present disclosure provides a fluidized bed gasification apparatus that can solve the above-mentioned technical problems.

[0004] This disclosure provides a fluidized bed gasification device, including: a first reaction chamber; a second reaction chamber; and a connecting channel connected to the outlet end of the first reaction chamber and the inlet end of the second reaction chamber, such that the airflow in the first reaction chamber is injected into the second reaction chamber and forms an entrainment zone at the inlet end of the second reaction chamber.

[0005] Optionally, the connection channel includes a first section connected to the first reaction chamber and a second section connected to the second reaction chamber. The first section is configured as a first tapering structure with a gradually decreasing diameter towards the first reaction chamber, and the second section is configured as a straight cylindrical structure.

[0006] Optionally, the maximum diameter of the connecting channel is smaller than the diameter of the first reaction chamber and the second reaction chamber.

[0007] Optionally, the outlet end of the first reaction chamber is constructed as a second constriction structure with a gradually decreasing diameter, and the inlet end of the connecting channel is connected to the outlet end of the second constriction structure.

[0008] Optionally, the second reaction chamber is provided with a gasifying agent inlet for injecting carbonaceous material and / or gasifying agent into the second reaction chamber to undergo an endothermic reaction with the material from the first reaction chamber.

[0009] Optionally, the fluidized bed gasification device further includes a heat recovery chamber, the inlet of which is connected to the outlet of the second reaction chamber.

[0010] Optionally, the second reaction chamber is constructed as an independent space with a refractory lining, and is separately arranged from the heat recovery chamber; or The second reaction chamber and the heat recovery chamber are an integrated membrane wall structure, and they share a cooling system.

[0011] Optionally, the heat recovery chamber is provided with a coolant inlet.

[0012] Optionally, the fluidized bed gasification device further includes a quench chamber, the inlet of which is connected to the outlet of the heat recovery chamber.

[0013] Optionally, the fluidized bed gasification device further includes a housing, in which the first reaction chamber, the connecting channel, the second reaction chamber, the heat recovery chamber, and the quench chamber are arranged sequentially from top to bottom along the height direction within the housing.

[0014] The technical solutions provided by the embodiments of this application may include the following beneficial effects: by setting up a multi-stage reaction structure consisting of a first reaction chamber, a connecting channel, and a second reaction chamber, unreacted carbon particles in the first reaction chamber can continue to participate in the gasification reaction in the connecting channel and the second reaction chamber. Furthermore, the connecting channel forms an entrainment zone at the inlet end of the second reaction chamber. Within this entrainment zone, the high-speed jet from the first reaction chamber generates strong entrainment and backflow on the surrounding gas, significantly enhancing the mixing, collision, and mass transfer between the unreacted carbon particles and the gasifying agent, creating excellent conditions for the secondary gasification reaction, thereby improving the gasification reaction rate. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of the fluidized bed gasification device described in this disclosure; Figure 2 This is a schematic diagram of the connection channel described in this disclosure.

[0016] Explanation of reference numerals in the attached drawings: 1. Top burner; 2. First reaction chamber; 3. Connecting channel; 31. First section; 32. Second section; 4. Gasifying agent inlet; 5. Second reaction chamber; 6. Coolant inlet; 7. Heat recovery chamber; 8. Quenching chamber; 9. Shell. Detailed Implementation

[0017] Some embodiments of this application will now be described in detail, examples of which are illustrated in the accompanying drawings. While exemplary embodiments of this application are shown in the drawings, it should be understood that this application may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of this application and to fully convey the scope of this application to those skilled in the art.

[0018] like Figure 1-2 As shown, this disclosure provides a fluidized bed gasification device, including: a first reaction chamber 2; a second reaction chamber 5; and a connecting channel 3, which is connected to the outlet end of the first reaction chamber 2 and the inlet end of the second reaction chamber 5, so that the airflow in the first reaction chamber 2 is injected into the second reaction chamber 5 and forms an entrainment zone at the inlet end of the second reaction chamber 5.

[0019] Through the above technical solution, in the fluidized bed gasification device provided in this disclosure, a top burner 1 is provided at the inlet end of the first reaction chamber 2 for injecting carbonaceous materials (such as coal-water slurry, pulverized coal, biomass powder, etc.) and gasifying agents (such as oxygen, steam, etc.) into the first reaction chamber 2. The first reaction chamber 2 is the main gasification reaction zone. The length of the first reaction chamber 2 is limited by the liquid slag discharge process. For coal-water slurry gasification, it is usually controlled within 10 meters to ensure that the reaction chamber temperature is within the safe slag discharge range of 50-100°C above the ash melting point of the raw materials. The outlet end of reaction chamber 2 is provided with a connecting channel 3 and a second reaction chamber 5 to form a multi-stage reaction structure. This allows unreacted carbon particles in the first reaction chamber 2 to continue participating in the gasification reaction in the connecting channel 3 and the second reaction chamber 5. The connecting channel 3 forms an entrainment zone at the inlet end of the second reaction chamber 5. In this entrainment zone, the high-speed jet from the first reaction chamber 2 generates strong entrainment and backflow of the surrounding gas, which significantly enhances the mixing, collision and mass transfer between unreacted carbon particles and the gasifying agent, creating excellent conditions for the secondary gasification reaction and thus improving the gasification reaction rate.

[0020] As an alternative implementation method, such as Figure 1 As shown, the outlet end of the first reaction chamber 2 is constructed with a second constriction structure whose diameter gradually decreases, meaning the flow cross-section gradually narrows along the airflow direction. This second constriction structure prevents reactants from directly escaping from the first reaction chamber 2 via short-flow, enhances backmixing in the bottom region, and thus prolongs the residence time of the material in the first reaction chamber 2, allowing most of the gasification reaction to be completed here. Backmixing refers to the reverse mixing that occurs between material particles (clusters) with different residence times in a continuous flow reactor (such as a tubular reactor or a tower reactor).

[0021] As an alternative implementation method, such as Figure 2As shown, the connecting channel 3 includes a first section 31 connected to the first reaction chamber 2 and a second section 32 connected to the second reaction chamber 5. The first section 31 is constructed with a first tapering structure whose diameter gradually decreases towards the first reaction chamber 2. The first tapering structure is the inlet end of the connecting channel 3, which is connected to the outlet end of the second tapering structure. It is used to introduce the high-temperature synthesis gas, liquid slag, and unreacted carbon particles generated in the first reaction chamber 2 into the second reaction chamber 5. The first tapering structure can further improve the backmixing and residence time in the first reaction chamber 2. The first section 31 is a first constriction structure, and the second section 32 is a straight cylinder structure. When the high-temperature synthesis gas, slag and unburned carbon particles from the first reaction chamber 2 pass through the first constriction structure, the flow velocity increases sharply. Then it enters the straight cylinder structure of the second section 32. Since the diameter remains unchanged, this high-speed jet can remain stable and does not diverge. It is ejected downward with high kinetic energy to form a jet. The high-speed jet from the first reaction chamber 2 generates strong entrainment and backflow on the surrounding gas, which significantly enhances the mixing, collision and mass transfer between unreacted carbon particles and gasifying agent, creating excellent conditions for the secondary gasification reaction.

[0022] Furthermore, such as Figure 1 As shown, the maximum diameter of the connecting channel 3 is smaller than the diameters of the first reaction chamber 2 and the second reaction chamber 5. For example, the end of the second reaction chamber 5 closest to the first reaction chamber 2 is constructed with a third constriction structure to facilitate smooth connection with the connecting channel 3. The maximum diameter of the connecting channel 3 is smaller than the diameter of the first reaction chamber 2 to increase the residence time of the reactants in the first reaction chamber 2. The maximum diameter of the connecting channel 3 is smaller than the diameter of the second reaction chamber 5 to enhance the entrainment effect in the entrainment zone. When the high-speed jet rushes from the narrow straight cylinder structure into the upper part of the much larger second reaction chamber 5, a huge velocity difference is generated between the jet boundary layer and the surrounding relatively stationary or slowly moving gas-solid medium. According to Bernoulli's principle, the pressure of the high-speed flowing fluid is low. Therefore, a local negative pressure zone will be formed on both sides of the jet core area. The negative pressure zone will suck in the original gas in the upper part of the second reaction chamber 5 and the reactants from the first reaction chamber 2. To fully utilize this effect, the diameter of the connecting channel 3 should be as small as possible while meeting the requirements for maintenance and anti-clogging, while its length needs to be determined according to the viscosity-temperature characteristics of the raw material ash and slag, and should be as long as possible while ensuring smooth slag discharge. This is because the gas-solid two-phase flow velocity is high and the collisions are intense in the connecting channel 3. Extending the channel length can effectively increase the gasification reaction time and improve the carbon conversion rate.

[0023] As an optional implementation, the second reaction chamber 5 is provided with a gasifying agent inlet 4 for injecting carbonaceous material and / or a gasifying agent into the second reaction chamber 5 to undergo an endothermic reaction with the material from the first reaction chamber 2. The gasifying agent inlet 4 is typically arranged horizontally or tangentially in the upper part of the second reaction chamber 5. The injected carbonaceous material may be, for example, difficult-to-treat carbonaceous waste such as coking dust or gasification slag. The gasifying agent can be oxygen, carbon dioxide, water vapor, or a mixture thereof. The high-temperature synthesis gas from the first reaction chamber 2, entering the second reaction chamber 5 through the connecting channel 3, carries unreacted carbon particles, which are then violently mixed with the carbonaceous material and gasifying agent injected through the gasifying agent inlet 4 in the entrainment zone. The main reactions in the second reaction chamber 5 are strongly endothermic reactions involving carbon particles, such as C + CO₂ → 2CO and C + H₂O → CO + H₂. These endothermic reactions fully utilize the sensible heat of the high-temperature syngas, further gasifying unreacted carbon and additional injected carbon-containing materials, increasing the content of effective gas (CO+H2) in the syngas, and reducing residual carbon in the final ash. On the other hand, by absorbing a large amount of heat through endothermic reactions, the temperature of the syngas is directly reduced, thereby playing an active temperature regulation function for the syngas.

[0024] As an alternative implementation method, such as Figure 1 As shown, the fluidized bed gasification device also includes a heat recovery chamber 7. The inlet of the heat recovery chamber 7 is connected to the outlet of the second reaction chamber 5. The heat recovery chamber 7 is equipped with a water-cooled wall heating surface to recover the sensible heat of the high-temperature syngas from the second reaction chamber 5 and produce steam as a byproduct. By controlling the feed rate of the gasifying agent inlet 4, the temperature of the syngas leaving the second reaction chamber 5 and entering the heat recovery chamber 7 can be adjusted to 50–100°C or even lower below the ash melting point, fundamentally solving the problem of high-temperature molten slag condensation and slag adhesion on the membrane wall surface of the heat recovery chamber 7, and maintaining a stable steam output. Simultaneously, the addition of carbonaceous materials and the secondary conversion of residual carbon further increase the effective gas component content and reduce the residual carbon in the final discharged ash.

[0025] Optionally, the second reaction chamber 5 is constructed as an independent space with a refractory lining, and is set separately from the heat recovery chamber 7. In this case, the second reaction chamber 5 is an independent structure, and can be connected to the heat recovery chamber 7 through a channel; or the second reaction chamber 5 and the heat recovery chamber 7 are an integrated membrane wall structure, and the two share a cooling system. The reaction heat is absorbed by the water medium in the membrane wall tube, and the structure is more compact.

[0026] Optionally, such as Figure 1As shown, the heat recovery chamber 7 is equipped with a coolant inlet 6, which is located on the side of the heat recovery chamber 7 close to the second reaction chamber 5. When the heat absorption and temperature regulation of the second reaction chamber 5 cannot reduce the temperature of the syngas to a safe range due to fluctuations in operating conditions, a cooling medium such as cold syngas is injected into the syngas in the heat recovery chamber 7 through the coolant inlet 6 to assist in cooling the syngas and ensure that the temperature of the airflow entering the heat exchange surface of the heat recovery chamber 7 is always below the critical temperature for slag adhesion.

[0027] Optionally, such as Figure 1 As shown, the fluidized bed gasification device also includes a quench chamber 8. The inlet end of the quench chamber 8 is connected to the outlet end of the heat recovery chamber 7. The quench chamber 8 is equipped with quench water. The syngas coming out of the heat recovery chamber 7 carries fly ash into the quench chamber 8 and is directly quenched by the quench water. The slag and ash particles are separated after cooling. The syngas is washed at the same time. The washed syngas is drawn out from the side of the quench chamber 8, and the ash is discharged from the bottom through the slag discharge system.

[0028] In addition, such as Figure 1 As shown, the fluidized bed gasification device also includes a shell 9. The first reaction chamber 2, the connecting channel 3, the second reaction chamber 5, the heat recovery chamber 7, and the quench chamber 8 are arranged sequentially from top to bottom along the height direction inside the shell 9. For example, they can be fixedly connected to the shell by a bracket. The shell 9 forms a pressure-resistant outer shell to provide the high-pressure environment required for gasification. The first reaction chamber 2, the connecting channel 3, the second reaction chamber 5, the heat recovery chamber 7, and the quench chamber 8 are arranged along the flow direction of carbonaceous materials and syngas to make the reaction smoother. At the same time, they fall freely by gravity, eliminating the need for a power unit.

[0029] A fluidized bed gasification method applied to the aforementioned equipment includes the following process: Carbonaceous material and a gasifying agent are fed into a first reaction chamber 2 through a top burner 1, where a partial oxidation reaction occurs under high temperature and high pressure conditions, generating a mixture of high-temperature syngas, liquid molten slag, and unreacted carbon particles. Because the bottom of the first reaction chamber 2 has a second constriction structure, the material undergoes strong back-mixing here, effectively increasing the reaction residence time, allowing more than 90% of the gasification reaction to be completed within the first reaction chamber 2. The high-temperature reacted material enters a connecting channel 3 through the second constriction structure at the bottom of the first reaction chamber 2. The connecting channel 3 has a first constriction structure at the top and a straight cylindrical structure at the bottom. This extends the reaction time of the material in the high-temperature environment and increases the gas velocity within the straight section, resulting in violent collisions between the molten slag and carbon particles. Some residual carbon continues to react with the gas here, effectively improving the gasification reaction rate. After passing through connecting channel 3, high-temperature syngas and molten slag enter the second reaction chamber 5 in a jet manner. Relying on the outlet jet of the straight section of connecting channel 3, an entrainment zone is formed in the upper part of the second reaction chamber 5, entraining the gas inside the second reaction chamber 5 and the carbonaceous material injected from the gasifying agent inlet 4 into the high-temperature jet, achieving rapid mixing. Inside the second reaction chamber 5, endothermic gasification reactions, mainly involving carbon reacting with water vapor and carbon dioxide, occur in large quantities, consuming unreacted carbon and replenishing the carbonaceous material. This increases the effective gas content in the syngas and correspondingly lowers the syngas temperature. By adjusting the feed load and ratio at the gasifying agent inlet 4, the temperature of the syngas entering the heat recovery chamber 7 can be controlled below the critical slag-forming temperature, ensuring stable operation of subsequent heat recovery. The cooled syngas flows downwards into the heat recovery chamber 7, where its sensible heat is absorbed by the membrane water-cooled wall, producing steam. If the outlet temperature of the second reaction chamber 5 exceeds the control range due to changing operating conditions, cold syngas or hot water is promptly injected through the coolant inlet 6 at the top of the heat recovery chamber 7 for auxiliary cooling, ensuring that the heat recovery chamber 7 does not accumulate slag for an extended period and maintaining steam production. Finally, the syngas enters the quench chamber 8 to complete quenching, washing, and ash separation. Clean syngas is drawn out from the quench chamber 8, and the ash is continuously discharged. The entire process, through multiple relay reactions in the first reaction chamber 2, connecting channel 3, and second reaction chamber 5, significantly reduces the residual carbon content in the ash, improves the effective gas yield, and solves the problem of steam production decline caused by slag accumulation in the waste boiler by utilizing the endothermic reaction characteristics of the second reaction chamber 5 itself and auxiliary cooling methods.

[0030] Numerous specific examples are provided in the embodiments provided herein, and it should be understood that these examples are for the purpose of elaborating on the embodiments of this disclosure in detail and are not intended to limit the disclosure. Embodiments in this disclosure may be practiced without these specific examples. In some embodiments, structures and / or techniques well known to those skilled in the art are not shown in detail so as not to obscure the understanding of this disclosure. Although preferred embodiments of this disclosure have been shown and described herein, it will be readily understood by those skilled in the art that these embodiments are provided by way of example only. Various variations, modifications, and substitutions will now occur to those skilled in the art without departing from this disclosure. It should be understood that various alternatives to the embodiments of this disclosure described herein are optionally used to implement this disclosure. The scope of this disclosure is intended to be defined by the claims, and thereby to cover structures within the scope of these claims and their equivalents.

Claims

1. A fluidized bed gasification device, characterized in that, include: First reaction chamber (2); Second reaction chamber (5); as well as The connecting channel (3) is connected to the outlet end of the first reaction chamber (2) and the inlet end of the second reaction chamber (5), so that the airflow in the first reaction chamber (2) is injected into the second reaction chamber (5) and a suction zone is formed at the inlet end of the second reaction chamber (5).

2. The fluidized bed gasification device according to claim 1, characterized in that, The connecting channel (3) includes a first section (31) connected to the first reaction chamber (2) and a second section (32) connected to the second reaction chamber (5). The first section (31) is constructed as a first narrowing structure with the diameter gradually decreasing towards the first reaction chamber (2), and the second section (32) is constructed as a straight cylinder structure.

3. The fluidized bed gasification apparatus according to claim 1 or 2, characterized in that, The maximum diameter of the connecting channel (3) is smaller than the diameter of the first reaction chamber (2) and the second reaction chamber (5).

4. The fluidized bed gasification apparatus according to claim 1 or 2, characterized in that, The outlet end of the first reaction chamber (2) is constructed as a second constriction structure with a gradually decreasing diameter, and the inlet end of the connecting channel (3) is connected to the outlet end of the second constriction structure.

5. The fluidized bed gasification apparatus according to claim 1, characterized in that, The second reaction chamber (5) is provided with a gasifying agent inlet (4) for injecting carbonaceous material and / or gasifying agent into the second reaction chamber (5) to undergo an endothermic reaction with the material from the first reaction chamber (2).

6. The fluidized bed gasification apparatus according to claim 1, characterized in that, The fluidized bed gasification device also includes a heat recovery chamber (7), the inlet of which is connected to the outlet of the second reaction chamber (5).

7. The fluidized bed gasification apparatus according to claim 6, characterized in that, The second reaction chamber (5) is constructed as an independent space with a refractory lining, and is separately located from the heat recovery chamber (7); or The second reaction chamber (5) and the heat recovery chamber (7) are an integrated membrane wall structure, and they share a cooling system.

8. The fluidized bed gasification apparatus according to claim 6, characterized in that, The heat recovery chamber (7) is provided with a coolant inlet (6).

9. The fluidized bed gasification apparatus according to claim 6, characterized in that, The fluidized bed gasification device also includes a quench chamber (8), the inlet of which is connected to the outlet of the heat recovery chamber (7).

10. The fluidized bed gasification apparatus according to claim 9, characterized in that, The gasification device further includes a housing (9), in which the first reaction chamber (2), the connecting channel (3), the second reaction chamber (5), the heat recovery chamber (7), and the quench chamber (8) are arranged sequentially from top to bottom along the height direction inside the housing (9).

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