A method of performance analysis of an adsorptive carbon capture system
By establishing a dynamic model and analytical methods for the adsorption-based carbon capture system, the process flow was optimized, solving the problems of the adsorbent's affinity for water and the influence of gas flow resistance, reducing energy consumption, and improving the efficiency and economy of the carbon capture system.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HARBIN INST OF TECH
- Filing Date
- 2026-02-13
- Publication Date
- 2026-06-05
AI Technical Summary
Existing physical adsorption carbon capture technologies suffer from problems such as the high affinity of adsorbents for water, resistance to gas flow, and high energy consumption, resulting in significant energy loss and making it difficult to achieve large-scale application.
By employing a dynamic model and analytical method for an adsorption-type carbon capture system, and establishing a mathematical model of the adsorption tower, as well as mass conservation equations, energy conservation equations, and momentum conservation equations, the energy loss of the system is calculated and the process flow is optimized to reduce the loss of useless energy.
This has reduced system energy loss, improved the efficiency and economy of carbon capture systems, and promoted the large-scale application of carbon capture technology.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of carbon capture technology, specifically relating to an analytical method for an adsorption-type carbon capture system. Background Technology
[0002] Currently, carbon capture technology captures CO2 from air or flue gas through physical adsorption or chemical absorption. When the capture amount reaches its maximum, the adsorbent is regenerated by electrical or thermal energy. The released CO2 is then pressurized and cooled by a multi-stage compressor and intercooler, and finally converted into room-temperature liquid CO2 for storage.
[0003] Compared with chemical absorption, physical adsorption has three advantages: First, because water has a high specific heat capacity, the solvent regeneration process in chemical absorption requires a large amount of heat and must overcome the latent heat of vaporization of water, while physical adsorption only requires heating the adsorbent, which has a lower specific heat capacity. Second, the absorbent in chemical absorption is corrosive, requiring high-quality equipment materials, which not only increases investment and maintenance costs but also may interrupt the collection process due to leakage or damage, while the adsorbent in physical adsorption is more stable. Finally, chemical absorbents degrade and volatilize over time, while a reasonable physical adsorbent structure can reduce adsorbent breakage and pulverization, eliminating the need for frequent replenishment.
[0004] Nevertheless, physical adsorption still has some problems. Due to the high affinity of the adsorbent for water, it may even preferentially adsorb water molecules rather than CO2, so the inlet gas needs to be deeply dehydrated before capture. In addition, due to the dense adsorbent particles in the physical adsorption tower, the gas flow is affected by resistance, and a blower is required to overcome the pressure drop. Among them, the pressure swing adsorption process also requires a vacuum pump to achieve adsorbent regeneration and CO2 desorption.
[0005] To reduce system energy consumption, the key lies in minimizing wasted energy. Energy analysis focuses on the "quantity" of energy, while carbon capture analysis focuses on the "quality" of energy, calculating the irreversible losses during the conversion of high-grade energy to low-grade energy. Therefore, using carbon capture analysis to guide the optimization of process flows or equipment structures, and systematically reducing carbon capture losses in the process, is a crucial path to fundamentally reducing operating costs and promoting the large-scale application of carbon capture technology. Summary of the Invention
[0006] This invention aims to guide the optimization of carbon capture systems and reduce unnecessary energy loss. It proposes a dynamic model and analysis method for adsorption-type carbon capture systems.
[0007] The technical solution adopted in this invention is:
[0008] An analytical method for an adsorption-type carbon capture system includes the following steps:
[0009] S1. Establish a dynamic model of the adsorption carbon capture system, calculate the temperature, pressure, concentration, and flow rate at each time and location, and provide input parameters for S2;
[0010] S2. Perform actual energy consumption calculation;
[0011] S3. Calculate the minimum separation work and evaluate the efficiency.
[0012] Furthermore, the dynamic model in S1 includes
[0013] The mathematical model of the adsorption tower is used to calculate the adsorption of each component gas affected by partial pressure by the adsorbent under isothermal conditions.
[0014] The mass conservation equation is used to describe how the mass of component i changes over time in any infinitesimal element of the adsorption tower under the influence of concentration gradient and gas flow.
[0015] Energy conservation equations, including the gas phase energy conservation equation, the solid phase energy conservation equation, and the metal wall energy conservation equation;
[0016] The momentum conservation equation is used to describe the pressure change as gas passes through the bed.
[0017] Furthermore, the mathematical model of the adsorption tower is as follows:
[0018] (1)
[0019] in: To balance the adsorption capacity; The adsorption temperature; = , It is the mole fraction of gaseous component i. It is the total pressure. This is the saturated adsorption capacity parameter; These are parameters related to the heat of adsorption. As an adsorption affinity prefactor, These are parameters related to the competitive heat of adsorption.
[0020] Furthermore, the mass conservation equation is:
[0021] (2)
[0022] in, Indicates the porosity of the bed; It is the axial diffusion coefficient; It is the concentration of component i; Represents the overall gas flow rate; This represents the porosity inside the adsorbent particles; Represents the bulk density of the adsorbent; Represents the amount of adsorption;
[0023] Furthermore, the gas-phase energy conservation equation describes the change of gas energy within a micro-element over time under the influence of a temperature gradient:
[0024] (3)
[0025] in, Thermal conductivity; This refers to the gas phase temperature. This refers to the specific heat capacity of the gas phase at constant pressure. The convective heat transfer coefficient between the gas and the adsorbent; The convective heat transfer coefficient between the gas and the metal wall; The diameter of the bed layer; This refers to the specific surface area of the adsorbent particles; This refers to the gas phase density.
[0026] The solid-state energy conservation equation describes how the energy of the adsorbent within a micro-element changes over time under the influence of temperature gradient and heat of adsorption:
[0027] (4)
[0028] in, The solid phase thermal conductivity; This refers to the specific heat capacity of a solid phase at constant pressure. Let i be the specific heat capacity at constant pressure. The heat of adsorption of component i; It is the solid-state temperature;
[0029] The energy conservation equation for the metal wall describes the change of the metal wall surface of the adsorption tower over time under the influence of the temperature gradient:
[0030] (5)
[0031] in, The thermal conductivity of the metal wall; This refers to the specific heat capacity of a solid phase at constant pressure. For wall thickness, This refers to the temperature of the metal wall. This represents the density of the metal wall.
[0032] Furthermore, the momentum conservation equation is:
[0033] (6)
[0034] in, It is the viscosity of the gas; It refers to particle size; It is the particle regularity coefficient; It is the velocity squared term with its sign preserved.
[0035] Furthermore, the actual energy consumption calculation in S2 includes:
[0036] During the adsorption process, the adsorption bed releases heat to the outside world. This heat is carried away by the coolant, which in turn heats the coolant to a certain temperature. The output of each node is as follows:
[0037] (7)
[0038] During the desorption process, the adsorption bed absorbs heat from the outside environment; this heat is generated at a temperature of... The heat source is provided, and the heat consumption of each node is:
[0039] (8)
[0040] in, It is the final desorption temperature of node j; It is the initial adsorption temperature of node j; It is the wall volume of node j; , , is the specific heat capacity, volume, and density of the adsorbent at node j; It is the desorption capacity of node j for component i; It is the heat of adsorption of component i, therefore desorption requires input. Calories,
[0041] Total specific heat consumption is the heat consumed to capture 1 mol of CO2:
[0042] (9)
[0043] The specific work of a blower is expressed by the following formula:
[0044] (10)
[0045] in, It refers to compressor efficiency; It is the CO2 concentration; It is the adsorption temperature.
[0046] The specific work of a vacuum pump is expressed by the following formula:
[0047] (11)
[0048] in, It refers to the efficiency of the vacuum pump;
[0049] The physical properties of CO2 change drastically in the supercritical region. The specific work of the compressor is calculated using the isentropic method and expressed by the following formula:
[0050] (12)
[0051] (13)
[0052] in, It is the isentropic efficiency of the compressor; It refers to the compressor's mechanical efficiency;
[0053] The heat exchange products after compression are:
[0054] (14)
[0055] Total consumption is:
[0056] (15)
[0057] Furthermore, the minimum separation work in S3 represents the minimum work required to capture CO2 under ideal conditions.
[0058] (16)
[0059] in: It is the recovery rate; and These are the enthalpy and entropy values of liquid CO2 at normal pressure.
[0060] The total minimum separation work is:
[0061] (17)
[0062] The carbon capture system's adsorption-regeneration cycle can avoid the following losses:
[0063] (18)
[0064] The overall efficiency is:
[0065] (19).
[0066] Compared with the prior art, the present invention has the following advantages:
[0067] Based on a one-dimensional discrete dynamic model of the adsorption tower, this invention calculates the useful work that the system must consume and the unavoidable useless work during the adsorption-regeneration process, and the high-grade electrical energy consumed by each pressure device to meet the operating parameters of the adsorption bed, ultimately achieving a comprehensive evaluation of the efficiency of the carbon capture system. Detailed Implementation
[0068] To better understand the purpose, structure, and function of this invention, a more detailed description of the invention is provided below.
[0069] ΔE is the maximum energy available for doing useful work in a system. ΔE analysis, based on the second law of thermodynamics, quantifies irreversible energy loss that occurs during system operation. In the adsorption-desorption cycle, the adsorption tower experiences energy and mass transfer, but also irreversible losses, or ΔE losses. The main sources of these losses include:
[0070] Heat loss caused by temperature gradient during heat transfer: Adsorption is an exothermic process, while desorption is an endothermic process. Heat loss occurs when heat is transferred from a high temperature to a low temperature.
[0071] Losses caused by concentration gradient during mass transfer: When the adsorbate diffuses within the adsorbent due to concentration and flows in the bed, it is affected by resistance, resulting in pressure reduction and mass loss.
[0072] Losses caused by fluid friction and mixing: Friction of the fluid in the adsorption tower and mixing of the component gases also result in fluid losses.
[0073] This invention provides an analytical method for an adsorption-type carbon capture system, comprising the following steps:
[0074] S1. Establish a dynamic model of the adsorption carbon capture system, calculate the temperature, pressure, concentration, and flow rate at each time and location, and provide input parameters for S2;
[0075] (1) Mathematical model of adsorption tower
[0076] When the inlet gas of the adsorption tower is a multi-component gas, the components compete for adsorption, and the adsorption model is as follows:
[0077] (1)
[0078] This equation is used to calculate the adsorption of each component gas by the adsorbent under isothermal conditions, which is affected by partial pressure.
[0079]
[0080] (2) The mass conservation equation describes how the mass of component i changes over time in any infinitesimal element of the adsorption tower under the influence of the concentration gradient and gas flow:
[0081] (2)
[0082] in, Indicates the porosity of the bed; It is the axial diffusion coefficient; It is the concentration of component i; Represents the overall gas flow rate; This represents the porosity inside the adsorbent particles; Represents the bulk density of the adsorbent; This represents the amount of adsorption.
[0083] (3) The energy conservation equations include the gas phase energy conservation equation, the solid phase (adsorbent) energy conservation equation and the metal wall energy conservation equation.
[0084] The gas phase energy conservation equation describes how the gas energy within a micro-element changes over time under the influence of a temperature gradient:
[0085] (3)
[0086] in, Thermal conductivity; This refers to the gas phase temperature. This refers to the specific heat capacity of the gas phase at constant pressure. The convective heat transfer coefficient between the gas and the adsorbent; The convective heat transfer coefficient between the gas and the metal wall; The diameter of the bed layer; This refers to the specific surface area of the adsorbent particles; This represents the gas phase density.
[0087] The solid-state energy conservation equation describes how the energy of the adsorbent within a micro-element changes over time under the influence of temperature gradient and heat of adsorption:
[0088] (4)
[0089] in, The solid phase thermal conductivity; This refers to the specific heat capacity of a solid phase at constant pressure. Let i be the specific heat capacity at constant pressure. The heat of adsorption of component i; It is the solid-state temperature.
[0090] The energy conservation equation for the metal wall describes the change of the metal wall surface of the adsorption tower over time under the influence of the temperature gradient:
[0091] (5)
[0092] in, The thermal conductivity of the metal wall; This refers to the specific heat capacity of a solid phase at constant pressure. For wall thickness, This refers to the temperature of the metal wall. This represents the density of the metal wall.
[0093] (4) The momentum conservation equation describes the pressure change as the gas passes through the bed:
[0094] (6)
[0095] in, It is the viscosity of the gas; It refers to particle size; It is the particle regularity coefficient; It is the velocity squared term with its sign preserved.
[0096] (2) Calculation Model
[0097] S2. Actual energy consumption during the cycle process
[0098] During the adsorption process, the adsorption bed releases heat to the outside world. This heat is carried away by the coolant, which in turn heats the coolant to a certain temperature. The output of each node is as follows:
[0099] (7)
[0100] During the desorption process, the adsorption bed absorbs heat from the outside environment; this heat is generated at a temperature of... The heat source is provided, and the heat consumption of each node is:
[0101] (8)
[0102] in, It is the final desorption temperature of node j; It is the initial adsorption temperature of node j; It is the wall volume of node j; , , is the specific heat capacity, volume, and density of the adsorbent at node j; It is the desorption capacity of node j for component i; This is the heat of adsorption of component i (negative value), therefore desorption requires input. The calories.
[0103] Total specific heat consumption is the heat consumed to capture 1 mol of CO2:
[0104] (9)
[0105] Other equipment analysis is as follows:
[0106] The specific work of a blower is expressed by the following formula:
[0107] (10)
[0108] in, It refers to compressor efficiency; It is the CO2 concentration; It is the adsorption temperature.
[0109] The specific work of a vacuum pump is expressed by the following formula:
[0110] (11)
[0111] in, It refers to the efficiency of the vacuum pump.
[0112] The physical properties of CO2 change drastically in the supercritical region. The specific work of the compressor is calculated using the isentropic method and expressed by the following formula:
[0113] (12)
[0114] (13)
[0115] in, It is the isentropic efficiency of the compressor; It refers to the compressor's mechanical efficiency.
[0116] The heat exchange products after compression are:
[0117] (14)
[0118] Total consumption is:
[0119] (15)
[0120] S3. Minimum Separation Work and Evaluation
[0121] Minimum separation work represents the minimum work required to capture CO2 under ideal conditions, and is an important reference standard for evaluating the thermodynamic perfection of a carbon capture system.
[0122] (16)
[0123] in: It is the recovery rate; and These are the enthalpy and entropy values of liquid CO2 at normal pressure.
[0124] The total minimum separation work is:
[0125] (17)
[0126] The carbon capture system's adsorption-regeneration cycle can avoid the following losses:
[0127] (18)
[0128] The overall efficiency is:
[0129] (19)
[0130] This invention provides a one-dimensional discrete dynamic mathematical model of a CO2 adsorption tower, a carbon capture system analysis of the adsorption process, a carbon capture system analysis of the regeneration and carbon sequestration processes, and a carbon capture system adsorption-regeneration cycle that can avoid losses.
[0131] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.
Claims
1. A method for analyzing the carbon capture system of an adsorption type, characterized in that: Includes the following steps: S1. Establish a dynamic model of the adsorption carbon capture system, calculate the temperature, pressure, concentration, and flow rate at each time and location, and provide input parameters for S2; S2. Perform actual energy consumption calculation; S3. Calculate the minimum separation work and evaluate the efficiency.
2. The analytical method for an adsorption-type carbon capture system according to claim 1, characterized in that: The dynamic model in S1 includes The mathematical model of the adsorption tower is used to calculate the adsorption of each component gas affected by partial pressure by the adsorbent under isothermal conditions. The mass conservation equation is used to describe how the mass of component i changes over time in any infinitesimal element of the adsorption tower under the influence of concentration gradient and gas flow. Energy conservation equations, including the gas phase energy conservation equation, the solid phase energy conservation equation, and the metal wall energy conservation equation; The momentum conservation equation is used to describe the pressure change as gas passes through the bed.
3. The analytical method for an adsorption-type carbon capture system according to claim 2, characterized in that: The mathematical model of the adsorption tower is as follows: (1) in: To balance the adsorption capacity; The adsorption temperature; = , It is the mole fraction of gaseous component i. It is the total pressure. This is the saturated adsorption capacity parameter; These are parameters related to the heat of adsorption. As an adsorption affinity prefactor, These are parameters related to the competitive heat of adsorption.
4. The analytical method for an adsorption-type carbon capture system according to claim 2, characterized in that: The mass conservation equation is: (2) in, Indicates the porosity of the bed; It is the axial diffusion coefficient; It is the concentration of component i; Represents the overall gas flow rate; This represents the porosity inside the adsorbent particles; Represents the bulk density of the adsorbent; This represents the amount of adsorption.
5. The analytical method for an adsorption-type carbon capture system according to claim 2, characterized in that: The gas phase energy conservation equation describes the change of gas energy within a micro-element over time under the influence of a temperature gradient: (3) in, Thermal conductivity; This refers to the gas phase temperature. This refers to the specific heat capacity of the gas phase at constant pressure. The convective heat transfer coefficient between the gas and the adsorbent; The convective heat transfer coefficient between the gas and the metal wall; The diameter of the bed layer; This refers to the specific surface area of the adsorbent particles; This refers to the gas phase density. The solid-state energy conservation equation describes how the energy of the adsorbent within a micro-element changes over time under the influence of temperature gradient and heat of adsorption: (4) in, The solid phase thermal conductivity; This refers to the specific heat capacity of a solid phase at constant pressure. Let i be the specific heat capacity at constant pressure. The heat of adsorption of component i; It is the solid-state temperature; The energy conservation equation for the metal wall describes the change of the metal wall surface of the adsorption tower over time under the influence of the temperature gradient: (5) in, The thermal conductivity of the metal wall; This refers to the specific heat capacity of a solid phase at constant pressure. For wall thickness, This refers to the temperature of the metal wall. This represents the density of the metal wall.
6. The analytical method for an adsorption-type carbon capture system according to claim 2, characterized in that: The momentum conservation equation is: (6) in, It is the viscosity of the gas; It refers to particle size; It is the particle regularity coefficient; It is the velocity squared term with its sign preserved.
7. The analytical method for an adsorption-type carbon capture system according to claim 1, characterized in that: The actual energy consumption calculation in S2 includes: During adsorption, the adsorption bed releases heat to the outside world. This heat is carried away by the coolant, which in turn heats the coolant to a certain temperature. The output of each node is as follows: (7) During the desorption process, the adsorption bed absorbs heat from the outside environment; this heat is generated at a temperature of... The heat source is provided, and the heat consumption of each node is: (8) in, It is the final desorption temperature of node j; It is the initial adsorption temperature of node j; It is the wall volume of node j; , , is the specific heat capacity, volume, and density of the adsorbent at node j; It is the desorption capacity of node j for component i; It is the heat of adsorption of component i, therefore desorption requires input. Calories, Total specific heat consumption is the heat consumed per mol of CO2 captured: (9) The specific work of a blower is expressed by the following formula: (10) in, It refers to compressor efficiency; It is the CO2 concentration; It is the adsorption temperature. The specific work of a vacuum pump is expressed by the following formula: (11) in, It refers to the efficiency of the vacuum pump; The physical properties of CO2 change drastically in the supercritical region. The specific work of the compressor is calculated using the isentropic method and expressed by the following formula: (12) (13) in, It is the isentropic efficiency of the compressor; It refers to the compressor's mechanical efficiency; The heat exchange products after compression are: (14) Total consumption is: (15)。 8. The analytical method for an adsorption-type carbon capture system according to claim 1, characterized in that: In S3 The minimum separation work represents the minimum work required to capture CO2 under ideal conditions. (16) in: It is the recovery rate; and These are the enthalpy and entropy values of liquid CO2 at normal pressure. The total minimum separation work is: (17) The carbon capture system's adsorption-regeneration cycle can avoid the following losses: (18) The overall efficiency is: (19)。