Numerical simulation method of circulating type flue gas decarburization system

Abstract

The invention provides a numerical simulation method of a circulating type flue gas decarburization system, and belongs to the technical field of chemical energy. Based on gridding modeling and division and setting of multiple reaction areas, a reaction model between gas and solid phases in circulation is established and solved, by setting an absorption area assembly and a regeneration area assembly, the working conditions of a carbon dioxide absorption area and an absorbent regeneration area are adjusted, and then the gas-solid reaction form of the carbon dioxide absorption area and the absorbent regeneration area is adjusted. Therefore, the absorption-removal circulation of carbon dioxide in the system is realized. The device comprises an absorption area assembly and a regeneration area assembly, and further comprises a communicating pipe assembly, one side of the absorption area assembly is provided with an absorbent particle inlet, the other side of the absorption area assembly is provided with a communicating pipe assembly, the other end of the communicating pipe assembly is communicated with a regeneration area assembly, the other side of the regeneration area assembly is provided with a regeneration particle inlet, and the communicating pipe assembly is arranged between the absorption area assembly and the regeneration area assembly.

Description

Technical Field

[0001] The present invention relates to a numerical simulation method for a cyclic flue gas decarbonization system, and specifically belongs to the technical field of chemical energy. Background Art

[0002] Flue gas decarbonization is an important part of CCS. Carbon dioxide capture and storage technology (CCS) separates carbon dioxide gas generated in industrial processes or energy utilization and permanently reduces emissions by storing it in underground rock formations through certain means to mitigate the greenhouse effect; flue gas decarbonization technologies can be divided into physical methods, biological methods, chemical methods, etc.;

[0003] Among them, the chemical method relies on compounds to chemically react with carbon dioxide in flue gas to remove carbon dioxide. The use of ethanolamine solution for flue gas decarbonization has been relatively mature in commercial applications, but the waste liquid generated after decarbonization is difficult to be treated with low energy consumption, and at the same time, the purification of the fixed carbon dioxide is difficult, and it is difficult to achieve low-cost storage;

[0004] Therefore, it is necessary to find new compounds for flue gas decarbonization. Potassium-based carbon dioxide absorbents have come into the view of relevant scholars. According to the characteristics of potassium-based carbon dioxide absorbents in flue gas decarbonization, it is of certain value to design a new flue gas decarbonization system to achieve the "absorption - removal" cycle of carbon dioxide in the system. Summary of the Invention

[0005] The purpose of the present invention is to provide a numerical simulation method for a cyclic flue gas decarbonization system to ensure the efficient absorption of carbon dioxide during the flue gas decarbonization process and the effective removal of carbon dioxide during the absorbent regeneration stage, and at the same time couple the chemical reactions in the above two stages to smoothly carry out the "absorption - removal" cycle of carbon dioxide in the system.

[0006] To solve the above technical problems, the technical solution adopted by the present invention is: the invention includes an absorption area component and a regeneration area component, and also includes a connecting pipe component;

[0007] An absorbent particle outlet is provided on one side of the absorption area component, a connecting pipe component is provided on the other side of the absorption area component, the other end of the connecting pipe component is connected to the regeneration area component, a regenerated particle inlet is provided on the other side of the regeneration area component, and the connecting pipe component is arranged between the absorption area component and the regeneration area component.

[0008] Furthermore, use modeling software to create an overall three-dimensional geometric model, divide the interior of the three-dimensional geometric model into an absorption area and a regeneration area, and connect the absorption area component and the regeneration area component through the connecting pipe component.

[0009] The upper end of the absorption zone assembly is set as the flue gas outlet, the lower end of the absorption zone assembly is set as the flue gas inlet, the absorption zone assembly is integrally arranged in a rectangular structure, and the four corners of the flue gas inlet and the flue gas outlet are both arranged in a tangential circle pattern;

[0010] The connecting pipe assembly includes an upper connecting pipe and a lower connecting pipe; both the upper connecting pipe and the lower connecting pipe are fixedly installed between the absorption zone assembly and the regeneration zone assembly, and the upper connecting pipe is located above the lower connecting pipe;

[0011] Furthermore, the flue gas enters the absorption zone assembly through the flue gas inlet. Initially, the potassium-based carbon dioxide particles enter the absorption zone assembly from the absorbent particle inlet arranged on one side of the absorption zone assembly and react with carbon dioxide and water vapor in the flue gas. After operating for a period of time, the absorbent particles enter the regeneration zone assembly through the lower connecting pipe.

[0012] Even further, adjust the relevant operating conditions of the fluidizing gas to ensure that the absorbent particles can reach the upper connecting pipe under the action of the fluidizing gas. In this process, the absorbent particles enter the regeneration stage, releasing carbon dioxide and water vapor. The regenerated absorbent particles enter the absorption zone assembly from the upper connecting pipe and enter the next cycle.

[0013] A numerical simulation method for a circulating flue gas decarbonization system, the specific steps include:

[0014] Step 1: Create a geometric model of the carbon dioxide "absorption-regeneration" process reactor in the boiler tail gas, and establish a carbon dioxide capture reaction model in the flue gas;

[0015] Create the geometric model in ANSYS, and use fluent for mesh generation. Based on the convective heat transfer between the particles and the flue gas to be treated, the chemical reaction between the gas and solid phases, and the internal fluid flow characteristics of the downflow bed reactor, establish a carbon dioxide capture reaction model in the flue gas;

[0016] Step 2: Establish a carbon dioxide release and solid absorbent regeneration reaction model;

[0017] Based on the convective heat transfer between the particles and the fluidizing gas, the chemical reaction between the gas and solid phases, and the internal fluid flow characteristics of the fluidized bed reactor, establish a carbon dioxide release and solid absorbent regeneration reaction model;

[0018] Step 3: Integrate the reaction models to obtain a unified numerical simulation method for the carbon dioxide "absorption-regeneration" process in the boiler tail gas;

[0019] By integrating the carbon dioxide capture reaction model in the downflow bed with the solid absorbent regeneration and carbon dioxide release reaction model inside the fluidized bed reactor, a unified numerical simulation method for the carbon dioxide "absorption-regeneration" process in the boiler tail gas is obtained;

[0020] The beneficial effects of the present invention are as follows:

[0021] 1. By setting up the absorption zone component and the regeneration zone component, the operating conditions of the carbon dioxide absorption zone and the absorbent regeneration zone are adjusted, and then the gas-solid reaction form in the carbon dioxide absorption zone and the absorbent regeneration zone is adjusted to achieve the "absorption - removal" cycle of carbon dioxide in the system;

[0022] 2. Based on the grid-based modeling and the division and setting of multiple reaction zones, a reaction model between gas and solid phases in the cycle is established and solved; thus, the operating conditions of the potassium-based carbon dioxide absorbent in the decarbonization cycle and various data inside the reactor can be simulated more accurately. Brief Description of the Drawings

[0023] Figure 1 is a schematic diagram of the overall structure of the present invention;

[0024] Figure 2 is a front view schematic diagram of the overall structure of the present invention;

[0025] Figure 3 is a schematic diagram of the absorbent particle concentration of the present invention;

[0026] Figure 4 is a schematic diagram of the carbon dioxide concentration distribution of the present invention;

[0027] Figure 5 is a schematic diagram of the nitrogen concentration distribution of the present invention;

[0028] Figure 6 is a schematic diagram of the water vapor concentration distribution of the present invention;

[0029] Figure 7 is a schematic diagram of the process of the present invention.

[0030] 1. Absorption zone component; 2. Regeneration zone component; 3. Flue gas inlet; 4. Flue gas outlet; 5. Absorbent particle outlet; 6. Fluidizing gas inlet; 7. Regenerated gas outlet; 8. Regenerated particle inlet; 9. Connecting pipe component; 10. Upper connecting pipe; 11. Lower connecting pipe. Detailed Embodiments

[0031] Next, the technical solutions in the embodiments will be described clearly and completely in conjunction with the attached Figures 1-7 ,...

[0032] Detailed Embodiment 1: As Figures 1-2As shown in the figure, the overall structure includes an absorption zone component 1 and a regeneration zone component 2. A connecting pipe component 9 is arranged between the absorption zone component 1 and the regeneration zone component 2. The absorption zone component 1 includes a flue gas inlet 3, a flue gas outlet 4, and an absorbent particle inlet 5. The upper end of the absorption zone component 1 is set as the flue gas outlet 4, the lower end of the absorption zone component 1 is set as the flue gas inlet 3, and an absorbent particle inlet 5 is arranged on one side of the absorption zone component 1. The regeneration zone component 2 includes a fluidizing gas inlet 6, a regeneration gas outlet 7, and a regenerated particle inlet 8. The upper end of the regeneration zone component 2 is set as the regeneration gas outlet 7, the lower end of the regeneration zone component 2 is set as the fluidizing gas inlet 6, and a regenerated particle inlet 8 is arranged on one side of the regeneration zone component 2. The connecting pipe component 9 includes an upper connecting pipe 10 and a lower connecting pipe 11;

[0033] The flue gas enters the absorption zone component 1 through the flue gas inlet 3. Initially, potassium-based carbon dioxide particles enter the absorption zone component 1 from the absorbent particle inlet 5 arranged on one side of the absorption zone component 1 and react with carbon dioxide and water vapor in the flue gas. After running for a period of time, the absorbent particles enter the regeneration zone component 2 through the lower connecting pipe 11;

[0034] By adjusting the relevant conditions of the fluidizing gas, the fluidizing gas enters the regeneration zone component 2 through the fluidizing gas inlet 6 to ensure that the absorbent particles can reach the upper connecting pipe 11 under the action of the fluidizing gas. In this process, the absorbent particles enter the regeneration stage, releasing carbon dioxide and water vapor. The regenerated absorbent particles enter the absorption zone component 1 from the upper connecting pipe 10 and enter the next cycle;

[0035] Both the four corners of the flue gas inlet 3 and the flue gas outlet 4 are arranged in a tangential circle pattern. In the numerical simulation of the continuous decarbonization treatment of boiler flue gas using potassium-based carbon dioxide absorbent in the downcomer bed, under the same conditions, the effect of flue gas decarbonization in the downcomer bed with tangential circle gas supply at the four corners is significantly better than that of the downcomer bed with symmetric gas supply;

[0036] Selecting potassium-based carbon dioxide absorbent as a new chemical absorbent for flue gas decarbonization has the following advantages: potassium carbonate is easily available and the cost is low; the decarbonization process has a single reaction and does not produce harmful by-products; the reaction process has low corrosiveness and can be recycled; and the energy consumption in the absorbent regeneration process is relatively low;

[0037] Based on the characteristics of potassium-based carbon dioxide absorbent, its decarbonization product can be regenerated at a temperature above 100 °C, releasing the absorbed and fixed carbon dioxide and water vapor. The numerical simulation of the absorbent regeneration process is carried out, and a fluidized bed is selected as the absorbent regeneration reactor. At the same time, in order to facilitate the purification of the tail gas, water vapor is selected as the fluidizing gas. The simulation results show that the regeneration effect of the absorbent particles inside the fluidized bed is good;

[0038] The above two simulations are based on relatively ideal conditions. To more closely approximate the actual flue gas decarbonization conditions, a combined model of the "absorption - regeneration" two - stage process is established, with the "absorption - regeneration" processes respectively established in two different reaction zones of the model. Inside the reactor, potassium - based carbon dioxide absorbent particles are fed into the reactor from the absorbent inlet and accumulate below the absorption zone under the influence of their own gravity and the flue gas. At the same time, part of the absorbent and absorption products enter the regeneration zone of the particles from below, undergo pyrolysis under the action of the fluidizing gas and move upward, and enter the upper part of the absorption reaction zone above the reactor. Thus, a complete cycle is completed.

[0039] Specific implementation method two: As Figures 3-7 shown, a numerical simulation method for a cyclic flue gas decarbonization system specifically includes the following steps:

[0040] Step 1: Create a geometric model of the reactor for the "absorption - regeneration" process of carbon dioxide in boiler tail gas, and establish a reaction model for carbon dioxide capture in flue gas;

[0041] Create the geometric model in ANSYS and perform mesh generation using fluent. Based on the convective heat transfer between particles and the flue gas to be treated, the chemical reactions between gas and solid phases, and the fluid flow characteristics inside the down - flow bed reactor, establish a reaction model for carbon dioxide capture in flue gas;

[0042] Step 2: Then establish a reaction model for carbon dioxide release and solid absorbent regeneration;

[0043] Based on the convective heat transfer between particles and the fluidizing gas, the chemical reactions between gas and solid phases, and the fluid flow characteristics inside the fluidized bed reactor, establish a reaction model for carbon dioxide release and solid absorbent regeneration

[0044] Step 3: Integrate the reaction models to obtain a unified numerical simulation method for the "absorption - regeneration" process of carbon dioxide in boiler tail gas;

[0045] By integrating the reaction model for carbon dioxide capture in flue gas inside the down - flow bed with the reaction model for solid absorbent regeneration and carbon dioxide release inside the fluidized bed reactor, a unified numerical simulation method for the "absorption - regeneration" process of carbon dioxide in boiler tail gas is obtained;

[0046] By setting the absorption zone component 1 and the regeneration zone component 2, the operating conditions of the carbon dioxide absorption zone and the absorbent regeneration zone are adjusted, and then the gas-solid reaction form of the carbon dioxide absorption zone and the absorbent regeneration zone is adjusted to achieve the "absorption-removal" cycle of carbon dioxide in the system. Based on the grid modeling and the division and setting of multiple reaction zones, a reaction model between gas and solid phases in the cycle is established and solved; thus, the operating conditions of the potassium-based carbon dioxide absorbent in the decarbonization cycle and various data inside the reactor can be simulated more accurately, where the various data include the absorbent particle concentration, the carbon dioxide concentration distribution, the nitrogen concentration distribution, and the water vapor concentration distribution.

[0047] The above are only the preferred embodiments of the present invention, and there is no any form of limitation to the present invention. Although the present invention has been disclosed above with the preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to equivalent embodiments with equivalent changes by using the disclosed technical content within the scope of the technical solution of the present invention. However, as long as it does not depart from the technical solution content of the present invention, any simple modification, equivalent replacement, and improvement made to the above embodiments within the spirit and principle of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A numerical simulation device for a cyclic flue gas decarbonization system, comprising an absorption zone assembly (1) and a regeneration zone assembly (2), characterized in that, It further includes a connecting pipe assembly (9); One side of the absorption zone assembly (1) is provided with an absorbent particle inlet (5), the other side of the absorption zone assembly (1) is provided with a connecting pipe assembly (9), the other end of the connecting pipe assembly (9) is communicated with a regeneration zone assembly (2), the other side of the regeneration zone assembly (2) is provided with a regenerated particle inlet (8), and the connecting pipe assembly (9) is arranged between the absorption zone assembly (1) and the regeneration zone assembly (2).

2. The numerical simulation device of a cyclic flue gas decarbonization system according to claim 1, characterized in that, The upper end of the absorption zone assembly (1) is set as a flue gas outlet (4), the lower end of the absorption zone assembly (1) is set as a flue gas inlet (3), the absorption zone assembly (1) is integrally arranged in a rectangular structure, and the four corners of the flue gas inlet (3) and the flue gas outlet (4) are both arranged in a tangential circle manner.

3. The numerical simulation device of a cyclic flue gas decarbonization system according to claim 1, characterized in that, The upper end of the regeneration zone assembly (2) is set as a regeneration gas outlet (7), the lower end of the regeneration zone assembly (2) is set as a fluidizing gas inlet (6), and the regeneration zone assembly (2) is integrally arranged in a circular tube structure.

4. A numerical simulation device for a cyclic flue gas decarbonization system according to claim 1, characterized in that, The connecting pipe assembly (9) includes an upper connecting pipe (10) and a lower connecting pipe (11); Both the upper connecting pipe (10) and the lower connecting pipe (11) are fixedly installed between the absorption zone assembly (1) and the regeneration zone assembly (2), and the upper connecting pipe (10) is located above the lower connecting pipe (11).

5. A numerical simulation method for a circulating flue gas decarbonization system, and the specific steps include: Step 1: Create a geometric model of a reactor for the "absorption-regeneration" process of carbon dioxide in boiler tail gas, and establish a reaction model for carbon dioxide capture in flue gas; Step 2: Then establish a reaction model for carbon dioxide release and solid absorbent regeneration; Step 3: Integrate the reaction models to obtain a unified numerical simulation method for the "absorption-regeneration" process of carbon dioxide in boiler tail gas.

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