Fluidized bed gasification parameter optimization method and system based on fluid dynamics

Abstract

The invention belongs to the field of biomass utilization, and particularly discloses a fluidized bed gasification parameter optimization method and system based on hydrodynamics, and the method comprises the following steps: carrying out electrocatalytic pretreatment on to-be-treated sludge to obtain a liquid phase-organic phase-inorganic phase gradient separated three-phase chromatographic substance; carrying out solid-liquid separation on the three-phase chromatography substance to obtain a mixed mud cake, and measuring physical and chemical parameters of the mixed mud cake; and constructing a biomass fluidized bed gasification model, and substituting the obtained physical and chemical parameters into the biomass fluidized bed gasification model for simulation so as to obtain optimized parameters of fluidized bed gasification. The to-be-treated sludge is subjected to electro-catalysis pretreatment before gasification, gradient separation of a liquid phase, an organic phase and an inorganic phase of the sludge can be achieved, separation of the organic phase and the inorganic phase in the follow-up gasification process is facilitated, meanwhile, the biomass fluidized bed gasification model is established, physical and chemical parameters of a mixed sludge cake are substituted for simulation, and the biomass fluidized bed gasification model is established. Parameters can be quickly and accurately optimized, and the gasification efficiency can be further improved.

Description

Technical Field

[0001] The present application relates to the field of biomass utilization, and more specifically, to a fluid dynamics-based fluidized bed gasification parameter optimization method and system. Background Art

[0002] Sludge treatment and disposal is a critical issue in today's environmental protection industry. With the acceleration of urbanization and the continued expansion of sewage treatment, the amount of sludge generated is increasing. Sludge contains large amounts of organic and inorganic matter. If improperly handled, it not only consumes significant land resources but also causes serious pollution to the soil, water, and atmosphere. Sludge gasification technology is currently gaining widespread attention as an efficient and environmentally friendly treatment method. It converts organic components in sludge into combustible gas, achieving energy recovery while reducing sludge volume and weight. However, in practical applications, ash agglomeration in fluidized beds can lead to problems such as bed material caking, reduced fluidization quality, equipment wear and blockage, and reduced gasification efficiency during the gasification process in fluidized bed boilers. Ash melts at high temperatures, forming agglomerates that can cause localized sintering of the bed and uneven fluidization, which can, in severe cases, cause system failure. Furthermore, ash agglomerates can encapsulate unreacted fuel, reducing reaction efficiency and altering bed expansion characteristics, affecting boiler stability. Furthermore, ash agglomerates disrupt the uniform fluidization and heat transfer paths of the bed, forming thermal resistance layers or localized dead zones, significantly reducing heat transfer efficiency. Therefore, further optimization of the gasification process and parameters is necessary. Summary of the Invention

[0003] In response to the defects of the existing technology, the present application provides a fluid dynamics-based fluidized bed gasification parameter optimization method and system, which aims to solve the problems of ash agglomeration in the existing fluidized bed gasifier leading to slagging, excessive carbon residue and low gasification efficiency.

[0004] According to one aspect of the present application, a method for optimizing fluidized bed gasification parameters based on fluid dynamics is provided, and the method is specifically as follows: S1 electrocatalytically pre-treats the sludge to be treated to obtain a three-phase chromatographic product with liquid phase-organic phase-inorganic phase gradient separation; S2: performing solid-liquid separation on the three-phase chromatographic product to obtain a mixed mud cake, and measuring physical and chemical parameters of the mixed mud cake, wherein the physical and chemical parameters include one or more of ash composition and content, elemental analysis, moisture content, and density; S3 constructs a biomass fluidized bed gasification model, and substitutes the physical and chemical parameters obtained in step S2 into the biomass fluidized bed gasification model for simulation to obtain optimized parameters for fluidized bed gasification.

[0005] The present application performs electrocatalytic pretreatment on the sludge to be treated before gasification, which can achieve gradient separation of the sludge liquid phase, organic phase and inorganic phase, so that the organic matter and inorganic phase ash can be easily separated during the fluidization process in the subsequent gasification process, the heavy ash is deposited as bottom ash, and the light organic matter is quickly gasified to generate combustible gases such as CO, CH4, and H2. At the same time, by establishing a biomass fluidized bed gasification model and substituting the physical and chemical parameters of the mixed mud cake for simulation, the parameters can be optimized quickly and accurately, thereby further improving the gasification efficiency.

[0006] As a further preference, in step S1, when performing electrocatalytic pretreatment, a BDD electrode or an IrO2-based electrode is used as the anode, and a graphene carbon felt or a Ti / Pt electrode is used as the cathode.

[0007] As further preferred, in step S1, the voltage of the pulse electric field in the electrocatalytic pretreatment is 10V to 30V, and the current density is 50A / m² to 200A / m².

[0008] As a further preferred embodiment, in step S2, solid-liquid separation is performed by filter pressing or centrifugation, and the moisture content of the mixed mud cake is ensured to be 20% to 45%.

[0009] As a further preferred embodiment, in step S2, when solid-liquid separation is performed by centrifugation, the rotation speed is 2000 rpm to 4000 rpm, the differential speed ratio is 1:20 to 1:50, and the processing time is 10 min to 30 min.

[0010] According to another aspect of the present application, a fluidized bed gasification parameter optimization system based on fluid dynamics is provided, comprising an electrocatalytic unit, a solid-liquid separation unit, a detection unit and a simulation unit, wherein the electrocatalytic unit is used to perform electrocatalytic pretreatment on the sludge to be treated to obtain a three-phase chromatogram with liquid phase-organic phase-inorganic phase gradient separation; the solid-liquid separation unit is used to perform solid-liquid separation on the three-phase chromatogram to obtain a mixed mud cake; the detection unit is used to detect the physical and chemical parameters of the mixed mud cake, wherein the physical and chemical parameters include one or more of ash composition and content, elemental analysis, moisture content, and density; the simulation unit is used to construct a biomass fluidized bed gasification model, and substitute the physical and chemical parameters of the mixed mud cake for simulation to obtain the optimization parameters of the fluidized bed gasification.

[0011] As a further preference, the electrocatalytic unit uses a BDD electrode or an IrO2-based electrode as the anode, and uses a graphene carbon felt or a Ti / Pt electrode as the cathode.

[0012] As a further preference, the voltage of the pulse electric field in the electrocatalytic unit is 10V to 30V, and the current density is 50A / m² to 200A / m².

[0013] As a further preference, the solid-liquid separation unit performs solid-liquid separation by filter pressing or centrifugation.

[0014] As a further preference, when the solid-liquid separation unit performs solid-liquid separation in a centrifugal manner, the rotation speed is 2000 rpm to 4000 rpm, and the differential speed ratio is 1:20 to 1:50.

[0015] In general, the above technical solutions conceived by this application have the following technical advantages compared with the existing technologies: 1. This application performs electrocatalytic pretreatment on the sludge to be treated before gasification, which can achieve gradient separation of the sludge liquid phase, organic phase, and inorganic phase, facilitating the separation of the organic and inorganic phases during the subsequent gasification process. At the same time, by establishing a biomass fluidized bed gasification model and substituting the physical and chemical parameters of the mixed sludge cake into the simulation, the parameters can be quickly and accurately optimized, which is conducive to further improving the gasification efficiency.

[0016] 2. This application also optimizes the parameters of the pulsed electric field during electrocatalytic pretreatment. This, on the one hand, avoids insufficient EPS destruction, limited electrophoretic migration, and insufficient hydroxyl radical (·OH) generation, which can lead to decreased organic-inorganic separation efficiency. It also avoids increased energy consumption and processing costs, as well as excessive oxidation of organic matter during electrochemical treatment, resulting in its mineralization into carbon dioxide and water. This reduces the amount of organic matter that is subsequently gasified and reduces syngas yield.

[0017] 3. In addition, this application optimizes the centrifugal separation parameters to avoid incomplete solid-liquid separation, which results in the solid phase cake retaining a large amount of water and hindering subsequent gasification. It also prevents high centrifugal forces from causing a decrease in the cake porosity, resulting in a dense filter cake that impairs mass transfer during gasification and reduces gasification efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a flow chart of fluidized bed gasification parameter optimization based on fluid dynamics provided in an embodiment of the present application. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0020] like Figure 1 As shown, according to one aspect of the present application, a fluidized bed gasification parameter optimization method based on fluid dynamics is provided, and the method is specifically as follows: S1 electrocatalytically pre-treats the sludge to be treated to obtain a three-phase chromatographic product with liquid phase-organic phase-inorganic phase gradient separation; S2 performs solid-liquid separation on the three-phase chromatographic product to obtain a mixed mud cake, and measures the physical and chemical parameters of the mixed mud cake, the physical and chemical parameters including one or more of ash composition and content, elemental analysis, moisture content, and density; S3 constructs a biomass fluidized bed gasification model, and substitutes the physical and chemical parameters obtained in step S2 into the biomass fluidized bed gasification model for simulation to obtain optimized parameters for fluidized bed gasification.

[0021] This application utilizes electrocatalytic pretreatment of the sludge prior to gasification. Electrocatalysis utilizes multiple synergistic mechanisms to efficiently break down extracellular polymeric substances (EPS) in the sludge, achieving deep organic-inorganic separation. At the anode interface, high potential directly oxidizes and severs the β-glycosidic bonds between EPS polysaccharides and protein peptide chains, disrupting the three-dimensional gel network. Hydroxyl radicals (·OH) further attack the CH bonds of EPS, initiating a free radical chain reaction that degrades macromolecular organic matter and exposes encapsulated inorganic particles (such as SiO2 and Al2O3). Simultaneous electrophoretic migration drives negatively charged EPS to aggregate at the anode, causing flocs to migrate and aggregate near the anode, weakening their electrostatic adsorption to inorganic particles. The alkaline environment at the cathode promotes the formation of Ca²⁺ / Mg²⁺ precipitates (such as CaCO3), disrupting the cationic bridges between EPS and inorganic particles. After EPS is destroyed, the inorganic ions (such as K⁺, Na⁺) dissolved in the liquid phase and the degradation products of large molecular organic matter (small molecular organic acids, monosaccharides, etc.) form a homogeneous solution. Due to the difference in density gradient (organic phase 0.9~1.2 g / cm³, inorganic phase 2.6~3.5g / cm³), they form a three-phase stratified structure through gravity differentiation: the upper layer is a liquid phase enriched with soluble substances, the middle layer is a light and insoluble organic matter aggregation phase, and the bottom layer is a high-density inorganic particle deposition phase, which facilitates the separation of the organic phase and the inorganic phase in the subsequent gasification process. In the fluidized bed, high-purity organic matter (organic matter content of more than 85%) in the mixed mud cake undergoes devolatilization and gasification reaction to generate combustible gas (mainly including CO, H2, CH4). At the same time, the high-melting point ash in the mixed mud cake (SiO2+Al2O3>70%, ash cone softening temperature ST>1200℃) is classified into particle size during the turbulent fluidization process. Large-particle ash (particle size of 0.5 mm to 5 mm) is enriched in the air distribution plate area and forms a bottom ash layer due to gravity sedimentation. A very small amount of fine fly ash (particle size <100μm) enters the subsequent cyclone wind system along with the synthesis gas and is quickly discharged from the furnace. Compared with the prior art that directly gasifies the dehydrated sludge, the present application performs electrocatalytic pretreatment on the sludge to be treated, so that the organic phase and the inorganic phase are pre-separated, which are easy to separate during the fluidized bed gasification process. The collision frequency of ash particles in the turbulent fluidized bed is reduced by 40%-60%, and the probability of surface melting and bonding is reduced to <10% (the traditional process in the prior art is 30%-50%), so that the slagging rate of the heated surface is reduced from 15 g / (m²·h) to 25 g / (m²·h) in the traditional process to 3-8 g / (m²·h). At the same time, the synthesis gas generated by the gasification of organic matter in this process can be used for combined power generation and methanol synthesis, and the inorganic phase bottom slag can be used as concrete aggregate or ceramsite raw material, which meets the goals of sludge reduction, resource utilization and harmless disposal.

[0022] At the same time, taking into account the huge changes in the physical and chemical parameters of the mixed mud cake obtained by solid-liquid separation after electrocatalytic pretreatment, the physical and chemical parameters include one or more of ash composition and content, elemental analysis, moisture content, and density. In actual applications, they can be selected according to the situation. The existing gasification parameters cannot achieve a good gasification effect. This application proposes to establish a biomass fluidized bed gasification model and substitute the physical and chemical parameters of the mixed mud cake for simulation, so as to quickly and accurately optimize the gasification parameters based on fluid dynamics to further improve the gasification efficiency.

[0023] Furthermore, in step S1, electrocatalytic pretreatment is performed using a BDD electrode or an IrO2-based electrode as the anode, and a graphene carbon felt or Ti / Pt electrode as the cathode. During electrocatalytic pretreatment, the electrolysis reaction proceeds under the influence of a pulsed electric field with a voltage of 10V to 30V and a current density of 50A / m² to 200A / m². This process induces electrochemical phase separation in the treated sludge, forming a three-phase chromatogram with distinct interfacial stratification: from top to bottom, a liquid phase enriched in soluble matter, an organic phase primarily composed of degraded organic matter, and an inorganic phase rich in aluminosilicates. The combined action of voltage and current can, on the one hand, prevent insufficient EPS destruction, limited electrophoretic migration, and insufficient hydroxyl radical (·OH) generation, which can lead to reduced organic-inorganic separation efficiency. On the other hand, it can also avoid increased energy consumption and treatment costs, as well as excessive oxidation of organic matter during electrochemical treatment, resulting in its mineralization into carbon dioxide and water, which reduces the amount of organic matter that is subsequently gasified and reduces syngas yield.

[0024] Furthermore, in step S2, mechanical dehydration is performed by filter pressing or centrifugation to achieve solid-liquid separation, and the filtrate is discharged to obtain a mixed mud cake with a moisture content of 20% to 45%.

[0025] Preferably, when using a centrifugal method for solid-liquid separation, the rotation speed is 2000 rpm to 4000 rpm, and the differential speed ratio is 1:20 to 1:50. This prevents incomplete solid-liquid separation, which can lead to the solid phase cake retaining a large amount of water, which is not conducive to subsequent gasification. It also prevents high centrifugal forces from reducing the porosity of the cake, forming a dense filter cake, impairing mass transfer during gasification, and reducing gasification efficiency.

[0026] According to another aspect of the present application, a fluidized bed gasification parameter optimization system based on fluid dynamics is provided, comprising an electrocatalytic unit, a solid-liquid separation unit, a detection unit and a simulation unit, wherein the electrocatalytic unit is used to perform electrocatalytic pretreatment on the sludge to be treated to obtain a three-phase chromatogram with liquid phase-organic phase-inorganic phase gradient separation; the solid-liquid separation unit is used to perform solid-liquid separation on the three-phase chromatogram to obtain a mixed mud cake; the detection unit is used to detect the physical and chemical parameters of the mixed mud cake; the simulation unit is used to construct a biomass fluidized bed gasification model based on the Euler-Euler framework, and substitute the physical and chemical parameters of the mixed mud cake for simulation to obtain the optimization parameters of the fluidized bed gasification.

[0027] Furthermore, the electrocatalytic unit uses a BDD electrode or an IrO2-based electrode as an anode and a graphene carbon felt or a Ti / Pt electrode as a cathode. The voltage of the pulsed electric field in the electrocatalytic unit is 10V to 30V, and the current density is 50A / m² to 200A / m².

[0028] Furthermore, the solid-liquid separation unit uses filter pressing or centrifugation to separate the liquid phase in the three-phase chromatographic product, retaining a mixed cake of organic and inorganic phases for subsequent gasification. More preferably, the solid-liquid separation unit uses centrifugation for solid-liquid separation. In a preferred embodiment of the present application, a decanter centrifuge (LW series) is used for solid-liquid separation, with a rotation speed of 2000 rpm to 4000 rpm, a differential speed ratio of 1:20 to 1:50, and a processing time of 10 to 30 minutes.

[0029] This application adopts the Euler two-fluid model in the prior art to construct a biomass fluidized bed gasification model. In practical applications, a suitable model can be selected to construct a biomass fluidized bed gasification model according to actual conditions. It only needs to meet the fluid mechanics requirements, which will not be elaborated here.

[0030] 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 understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0031] Additionally, references throughout this specification to "one embodiment," "one embodiment," "an example," or similar language indicate that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present application. Thus, appearances of the phrase "in one embodiment," "in one embodiment," and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment.

[0032] It is easy for those skilled in the art to understand that the above is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A fluidized bed gasification parameter optimization method based on fluid dynamics, characterized in that: Specifically: S1 electrocatalytically pre-treats the sludge to be treated to obtain a three-phase chromatographic product with liquid phase-organic phase-inorganic phase gradient separation; S2: performing solid-liquid separation on the three-phase chromatographic product to obtain a mixed mud cake, and measuring physical and chemical parameters of the mixed mud cake, wherein the physical and chemical parameters include one or more of ash composition and content, elemental analysis, moisture content, and density; S3 constructs a biomass fluidized bed gasification model, and substitutes the physical and chemical parameters obtained in step S2 into the biomass fluidized bed gasification model for simulation to obtain optimized parameters for fluidized bed gasification.

2. The fluidized bed gasification parameter optimization method according to claim 1, characterized in that: In step S1, when performing electrocatalytic pretreatment, a BDD electrode or an IrO2-based electrode is used as the anode, and a graphene carbon felt or a Ti / Pt electrode is used as the cathode.

3. The fluidized bed gasification parameter optimization method according to claim 1, wherein: In step S1, the voltage of the pulse electric field in the electrocatalytic pretreatment is 10V to 30V, and the current density is 50A / m² to 200A / m².

4. The fluidized bed gasification parameter optimization method according to claim 1, wherein: In step S2, solid-liquid separation is performed by filter pressing or centrifugation, and the moisture content of the mixed mud cake is ensured to be 20% to 45%.

5. The fluidized bed gasification parameter optimization method according to claim 4, characterized in that: In step S2, when solid-liquid separation is performed by centrifugation, the rotation speed is 2000 rpm to 4000 rpm, the differential speed ratio is 1:20 to 1:50, and the processing time is 10 min to 30 min.

6. A fluidized bed gasification parameter optimization system based on fluid dynamics, characterized in that: It includes an electrocatalytic unit, a solid-liquid separation unit, a detection unit and a simulation unit, wherein the electrocatalytic unit is used to perform electrocatalytic pretreatment on the sludge to be treated to obtain a three-phase chromatogram of liquid phase-organic phase-inorganic phase gradient separation; the solid-liquid separation unit is used to perform solid-liquid separation on the three-phase chromatogram to obtain a mixed mud cake; the detection unit is used to detect the physical and chemical parameters of the mixed mud cake, and the physical and chemical parameters include one or more of ash composition and content, elemental analysis, moisture content, and density; the simulation unit is used to construct a biomass fluidized bed gasification model, and substitute the physical and chemical parameters of the mixed mud cake for simulation to obtain the optimization parameters of fluidized bed gasification.

7. The fluidized bed gasification parameter optimization system according to claim 6, characterized in that: The electrocatalytic unit adopts a BDD electrode or an IrO2-based electrode as an anode and a graphene carbon felt or a Ti / Pt electrode as a cathode.

8. The fluidized bed gasification parameter optimization system according to claim 6, characterized in that: The voltage of the pulse electric field in the electrocatalytic unit is 10V to 30V, and the current density is 50A / m² to 200A / m².

9. The fluidized bed gasification parameter optimization system according to claim 6, characterized in that: The solid-liquid separation unit performs solid-liquid separation by filter pressing or centrifugation.

10. The fluidized bed gasification parameter optimization system according to claim 9, characterized in that: When the solid-liquid separation unit performs solid-liquid separation in a centrifugal manner, the rotation speed is 2000 rpm to 4000 rpm, and the differential speed ratio is 1:20 to 1:50.

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