A modularly integrated coal-fired CO2 power generation system

Abstract

This invention discloses a modularly integrated coal-fired sCO2 power generation system, belonging to the field of coal-fired thermal energy utilization technology. It includes: a power generation module comprising an sCO2 Brayton cycle unit for converting coal-fired thermal energy into electrical energy; an underground heat exchange well group module comprising multiple heat exchange wells inserted into the coal-fired area for transferring coal-fired thermal energy to the sCO2 working fluid, wherein the location and depth of the heat exchange wells are differentiated according to the temperature distribution characteristics of the coal-fired area; and an adaptive control module comprising a controller configured to monitor the temperature distribution characteristics of the coal-fired area in real time and dynamically adjust the heat load distribution of the underground heat exchange well group module and the operating parameters of the power generation module based on the dynamic changes in the temperature distribution characteristics to maintain stable power generation efficiency. This invention effectively overcomes the insufficient adaptability of traditional power generation technologies in coal-fired scenarios, significantly improving the overall power generation efficiency and operational stability of the system.

Description

Technical Field

[0001] This invention belongs to the field of coal-fired thermal energy utilization technology, and particularly relates to a coal-fired CO2 power generation system based on modular integration. Background Technology

[0002] It is estimated that hundreds of millions of tons of coal resources are lost globally each year due to direct coal combustion. Simultaneously, massive amounts of greenhouse gases such as carbon dioxide, as well as toxic gases like sulfides and carbon monoxide, are emitted, posing a serious threat to regional ecosystems, public health, and the global climate. It is noteworthy that while coal fires cause harm, the enormous heat energy released during their continuous combustion constitutes a vast, yet untapped, energy resource. Therefore, achieving the safe and efficient recovery and utilization of coal fire heat energy, with both disaster mitigation and energy enhancement benefits, has become a pressing technological challenge in this field.

[0003] Current practices in utilizing coal-fired thermal energy face numerous technical bottlenecks, resulting in insufficient compatibility and unsatisfactory implementation effects of existing technological solutions. The primary problem lies in the extreme instability and non-uniformity of the coal-fired heat source itself. As a complex, dynamically evolving system, the combustion range, intensity, and temperature field distribution of a coal fire are influenced by multiple factors, including geological structure, coal seam fissures, oxygen supply, and meteorological conditions, exhibiting characteristics of dramatic fluctuations and random changes. This highly dynamic heat source characteristic renders traditional geothermal power generation or waste heat recovery technologies, designed based on stable operating conditions, severely inadequate for this scenario. Frequent sudden increases and decreases in heat load during system operation not only lead to a significant decline in power generation efficiency and equipment thermal stress fatigue but may also trigger system shutdowns or safety accidents.

[0004] In terms of power generation technology selection, existing technologies are significantly mismatched with the characteristics of coal-fired power plants. Steam Rankine cycles, using water as the working fluid, face inherent challenges such as difficulty in controlling phase change processes, high system thermal inertia, and slow response when dealing with drastic heat source fluctuations. Furthermore, under high temperature gradient conditions, they are prone to pipe thermal shock, corrosion, and scaling, severely impacting system reliability. While organic Rankine cycles are suitable for medium- and low-temperature heat sources, their commonly used organic working fluids suffer from flammability, toxicity, or environmental defects, and their relatively low cycle efficiency makes them unsuitable for the high-efficiency conversion of large-scale coal-fired heat energy. Although direct thermoelectric conversion technology based on the Seebeck effect has a simple structure, its energy conversion efficiency is generally below 10%, and its high manufacturing cost makes it difficult to achieve megawatt-level or larger industrial-scale power generation.

[0005] Furthermore, existing heat harvesting strategies are relatively crude, with underground heat exchange wells often deployed uniformly, failing to effectively match the highly heterogeneous temperature distribution characteristics of coal-fired areas. This results in insufficient heat harvesting in high-temperature areas and inefficient operation of heat exchange wells in low-temperature areas. At the system integration level, existing technologies lack systematic solutions tailored to the characteristics of coal-fired areas, often focusing only on the power generation unit itself. They fail to integrate unstable underground heat sources, high-efficiency energy conversion devices, and intelligent control strategies as an organic whole for synergistic optimization, causing the system to become rigid in the face of dynamic changes in coal-fired conditions and exhibiting significantly insufficient adaptive control capabilities.

[0006] In conclusion, there is an urgent need to propose a systematic technical solution that can fundamentally adapt to the inherent characteristics of unstable and uneven coal-fired thermal energy and achieve large-scale, high-efficiency, continuous and stable power generation. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention proposes a modularly integrated coal-fired CO2 power generation system, comprising:

[0008] The power generation module, including the sCO2 Brayton cycle unit, is used to convert the thermal energy of coal into electrical energy;

[0009] The underground heat exchange well module includes multiple heat exchange wells inserted into the coal fire area to transfer the thermal energy of the coal fire to the sCO2 working fluid. The location and depth of the heat exchange wells are set differently according to the temperature distribution characteristics of the coal fire area.

[0010] The adaptive control module includes a controller configured to monitor the temperature distribution characteristics of the coal fire area in real time, and dynamically adjust the heat load distribution of the underground heat exchange well group module and the operating parameters of the power generation module based on the dynamic changes of the temperature distribution characteristics, so as to maintain stable power generation efficiency.

[0011] Optionally, the sCO2 Brayton cycle unit in the power generation module includes a turbine, a compressor, a generator, a microchannel regenerator, and a cooling unit;

[0012] The turbine, compressor, and generator are connected via the same rotor shaft;

[0013] A turbine is used to drive a generator to generate electricity; a generator is used to output electrical energy; a compressor is used to increase the pressure of CO2.

[0014] The microchannel regenerator includes a cold-side flow path and a hot-side flow path that are isolated from each other. The cold-side flow path is connected between the compressor outlet and the inlet of the underground heat exchange well module, and the hot-side flow path is connected between the turbine outlet and the inlet of the cooling unit.

[0015] The cooling unit is connected between the hot-side flow path outlet of the microchannel regenerator and the compressor inlet.

[0016] Optionally, the surface of the microchannel regenerator is provided with a nano-coating, the channel width is preset to allow the sCO2 working fluid to reach a preset heat transfer coefficient near the critical point, and the heat transfer coefficient is adjusted when the channel width deviates from the preset range to a preset threshold.

[0017] Optionally, the underground heat exchange well group modules are arranged as follows:

[0018] The coal fire zone is divided into a temperature gradient zone and a temperature uniform zone.

[0019] In the temperature gradient region, the well spacing is set non-uniformly according to the degree of temperature difference between adjacent regions; the greater the temperature difference, the smaller the well spacing.

[0020] In the temperature uniformity zone, a constant well spacing is maintained;

[0021] The depth of a single well is determined based on the highest temperature value at its location; the higher the temperature, the greater the well depth.

[0022] Optionally, the inlet pipe of the underground heat exchange well group module is equipped with a multi-way electric regulating valve group;

[0023] The multi-way electric regulating valve group includes a main regulating valve that controls the total flow and branch regulating valves that match the number of temperature gradient zones;

[0024] The controller dynamically adjusts the CO2 flow rate of the heat exchange well in the area of ​​drastic temperature change by independently controlling the opening of the regulating valves of each branch, thereby realizing the redistribution of heat load.

[0025] Optionally, the adaptive control module also includes a CO2 replenishment system. When the rate of change of coal fire temperature exceeds a preset threshold, a coordinated control operation is performed. The coordinated control operation includes adjusting the compressor speed to match the change of CO2 working fluid density, adjusting the replenishment amount of the CO2 replenishment system to maintain system pressure stability, and prioritizing the reduction of heat load distribution to heat exchange wells in areas with drastic temperature changes.

[0026] Optionally, the CO2 replenishment system further includes a CO2 capture and purification unit;

[0027] The CO2 capture and purification unit includes a primary dust collector, a secondary electrostatic precipitator, an amine absorption tower, and a CO2 purification unit, which is connected to the coal fire flue gas emission outlet and is used to capture and purify CO2 in the coal fire flue gas.

[0028] Optionally, the system further includes an sCO2 working fluid purification module disposed between the underground heat exchange well group module and the power generation module, the sCO2 working fluid purification module comprising:

[0029] The primary filtration unit is used to remove solid particles carried by coal fire flue gas based on a sintered metal filter element.

[0030] The secondary purification unit is used to remove corrosive gases based on an activated alumina adsorption bed;

[0031] The online monitoring unit is used to detect the purity of the sCO2 working fluid in real time. When the purity does not reach the preset threshold, the purification unit regeneration program is triggered again.

[0032] The high-pressure flushing unit is used to set up a backflushing interface at the inlet of the microchannel regenerator, connect to a high-pressure CO2 storage tank, and periodically remove deposits in the microchannel.

[0033] Optionally, the system further includes a first thermal expansion compensation pipe and a second thermal expansion compensation pipe connected between the outlet manifold of the underground heat exchange well group module and the power generation module;

[0034] Both the first thermal expansion compensation pipeline and the second thermal expansion compensation pipeline include a corrugated pipe section and a high-temperature alloy compensator.

[0035] The deformation monitoring signals of the first and second thermal expansion compensation pipes are fed back to the controller to optimize the flow parameter control strategy of the sCO2 working fluid.

[0036] This invention also provides a modularly integrated coal-fired CO2 power generation method, which, based on the aforementioned system, includes the following steps:

[0037] Monitor the temperature distribution and trends in the coal fire area;

[0038] Based on the dynamic characteristics of temperature change trends, the control priority is determined: when the temperature changes drastically, the system pressure is stabilized first; when the temperature distribution is uneven, the heat load distribution is optimized first.

[0039] Based on the aforementioned control priority, the compressor speed and other operating parameters of the controller are adjusted synchronously.

[0040] The heat load ratio of heat exchange wells in each area is dynamically adjusted to match the heat load distribution with the temperature distribution characteristics of coal and fire.

[0041] Continuously monitor power generation efficiency and fine-tune control parameters based on monitoring results to keep efficiency fluctuations within a preset range.

[0042] Compared with the prior art, the present invention has the following advantages and technical effects:

[0043] This invention constructs a collaborative system consisting of a power generation module, an underground heat exchange well group module, and an adaptive control module. By adopting a modular integrated architecture and dynamic control strategy, it achieves efficient collection and stable conversion of unstable and uneven coal-fired thermal energy, effectively overcoming the insufficient adaptability of traditional power generation technologies in this scenario and significantly improving the overall power generation efficiency and operational stability of the system. Attached Figure Description

[0044] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0045] Figure 1 This is a schematic diagram of the method flow according to an embodiment of the present invention;

[0046] The components include: 1. CO2 capture and purification unit; 2. Coal fire flue gas emission outlet; 3. High-pressure CO2 storage tank; 4. Compressor; 5. Refill regulating valve; 6. Refill interface; 7. Cooling unit; 8. Hot side outlet; 9. Compressor inlet; 10. Compressor outlet; 11. Cold side inlet; 12. Turbine; 13. Generator; 14. Hot side inlet; 15. Cold side outlet; 16. Microchannel regenerator; 17. Multi-port electric regulating valve group; 18. First thermal expansion compensation pipeline; 19. CO2 working fluid purification module; 20. Second thermal expansion compensation pipeline; 21. Outlet manifold; 22. Turbine inlet; 23. Turbine outlet; 24. Low temperature zone; 25. Medium temperature zone; 26. High temperature zone; 27. Underground heat exchange well group module. Detailed Implementation

[0047] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0048] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0049] Example 1

[0050] This embodiment provides a modularly integrated coal-fired CO2 power generation system, comprising three interconnected functional modules:

[0051] (1) A power generation module comprising an sCO2 Brayton cycle unit, the unit comprising a turbine 12, a compressor 4, a generator 13, a microchannel regenerator 16 and a cooling unit 7; wherein the turbine 12 comprises a turbine inlet 22 and a turbine outlet 23, wherein the compressor 4 comprises a compressor inlet 9 and a compressor outlet 10; the microchannel regenerator 16 comprises a cold side inlet 11 and a cold side outlet 15, and also comprises a hot side inlet 14 and a hot side outlet 8; wherein the cooling unit 7 is used to cool the sCO2 discharged from the turbine 12 to the compressor 4 inlet temperature range of 35–45°C, the sCO2 working fluid drives the turbine 12 to generate electricity at a pressure of 20–30 MPa, and the compressor 4 is the main cycle power source of the system, with a working pressure range of 20–30 MPa;

[0052] (2) The underground heat exchange well group module 27 includes multiple heat exchange wells inserted into the coal fire area for transferring the thermal energy of the coal fire to the sCO2 working medium. The location and depth of the heat exchange wells are set differently according to the temperature distribution characteristics of the coal fire area. The underground heat exchange well group module 27 includes a low temperature zone 24, a medium temperature zone 25 and a high temperature zone 26.

[0053] (3) Adaptive control module, which includes a controller and a CO2 replenishment system. The controller is configured to: monitor the temperature distribution characteristics of the coal fire area in real time; dynamically adjust the heat load distribution of the underground heat exchange well group module 27 and the operating parameters of the power generation module based on the dynamic changes in temperature distribution; and maintain the power generation efficiency of the power generation module within a stable range. The controller identifies the rate and amplitude characteristics of coal fire temperature changes, prioritizes the redistribution of heat load to the heat exchange wells in areas with drastic temperature changes, and adjusts the compressor speed 4 and the flow parameters of the CO2 working fluid to reduce the impact of coal fire temperature fluctuations on the system power generation efficiency to within ±3%.

[0054] As an optional implementation, the controller is further configured to: gradually increase the heat load ratio of the heat exchange wells in the high-temperature area when the coal fire temperature shows a continuous upward trend; gradually decrease the heat load ratio of the heat exchange wells in the high-temperature area when the coal fire temperature shows a continuous downward trend; and dynamically adjust the heat load distribution to match the overall heat load distribution of the system with the coal fire temperature distribution characteristics.

[0055] In the feasible power generation module: the turbine 12 has a design power of 1–5MW and a rotor diameter of 0.8–1.2m; the turbine 12, compressor 4 and generator 13 are connected through the same rotor shaft to form a compact power transmission structure; the heat exchange area of ​​the microchannel regenerator 16 is ≥50m² / m³; and the pressure loss of the CO2 working fluid in the regenerator is ≤0.5MPa.

[0056] Furthermore, the channel width of the microchannel regenerator 16 is 300–600 μm. This width range enables the heat transfer coefficient of the sCO2 working fluid to reach 3,200–3,500 W / m²·K near the critical point. When the channel width deviates from this range by ±30 μm, the heat transfer coefficient decreases by >15%.

[0057] Furthermore, the microchannel regenerator 16 is configured to automatically switch to a high-turbulence operating mode when the temperature of the CO2 working fluid approaches the critical point; and to enhance the heat transfer coefficient through a nano-coating on the surface of the microchannel, thereby increasing the heat exchange efficiency near the critical point by ≥15%.

[0058] Implementably, the cooling unit 7 of the power generation module is configured as any of the following:

[0059] (a) An independent cooler, comprising a shell-and-tube heat exchange structure, a cooling medium circulation system, and a temperature control valve, wherein the cooling medium is water or air, for cooling the sCO2 temperature from 80–100°C to 35–45°C; or

[0060] (b) An integrated cooling section of the microchannel regenerator 16, wherein the heat exchange area of ​​the integrated cooling section accounts for 25–35% of the total area of ​​the regenerator, and is used to cool the sCO2 temperature from 80–100°C to 35–45°C.

[0061] The layout of the underground heat exchange well group module 27 is feasible, including: dividing the coal fire area into a temperature gradient zone and a temperature uniform zone; in the temperature gradient zone, the well spacing is non-uniformly set according to the degree of temperature difference between adjacent areas, and the greater the temperature difference, the smaller the well spacing; in the temperature uniform zone, the well spacing is kept constant; the depth of a single well is determined according to the highest temperature value at its location, and the higher the temperature, the greater the well depth.

[0062] Furthermore, the layout of the underground heat exchange well group module 27 includes the following details: in the temperature gradient zone, the minimum well spacing is 1.0m, and the maximum is 4.0m; in the temperature uniform zone, the well spacing is fixed at 6.0m. The depth of a single well ranges from 8.0 to 15.0m, with the specific depth increasing linearly according to the highest temperature value at its location. For example, when the highest temperature is 300℃, the well depth is 8.0m; when the highest temperature is 600℃, the well depth is 15.0m.

[0063] In practice, the power generation module and the outlet manifold 21 of the underground heat exchange well group module 27 are connected by a first thermal expansion compensation pipe 18 and a second thermal expansion compensation pipe 20. The pipe includes a corrugated pipe section and a high-temperature alloy compensator, with an axial compensation of ≥80mm and a temperature resistance of ≥750℃. The deformation monitoring signals of the first thermal expansion compensation pipe 18 and the second thermal expansion compensation pipe 20 are fed back to the controller to optimize the flow parameter control strategy of the sCO2 working fluid.

[0064] Implementably, the inlet pipe of the underground heat exchange well group module 27 is equipped with a multi-way electric regulating valve group 17, which includes: a main regulating valve for controlling the total flow rate; and branch regulating valves, the number of which matches the number of temperature gradient zones, with each branch regulating valve corresponding to a temperature gradient zone. The controller dynamically adjusts the sCO2 flow rate to the heat exchange wells in different areas by independently controlling the opening of each branch regulating valve, thereby achieving heat load redistribution. When heat load redistribution is implemented in areas with drastic temperature changes, the opening of the corresponding branch regulating valve is reduced by 20-30%.

[0065] Implementably, the system also includes an sCO2 working fluid purification module 19, which is located between the outlet manifold 21 of the underground heat exchange well group module 27 and the power generation module. This module includes: a primary filtration unit containing a sintered metal filter element with a pore size ≤ 5 μm, used to remove solid particles carried by coal-fired flue gas; a secondary purification unit containing an activated alumina adsorption bed, used to remove corrosive gases such as SO2 / H2S; an online monitoring unit that monitors the purity of the sCO2 working fluid in real time, triggering a purification unit regeneration program when the particle concentration > 5 mg / m³ or the corrosive gas concentration > 10 ppm; and a high-pressure flushing unit, with a backflushing interface at the inlet of the microchannel regenerator 16 connected to a high-pressure CO2 storage tank 3, used to periodically remove deposits within the microchannels.

[0066] Implementably, the CO2 replenishment system further includes a CO2 capture and purification unit 1, which is connected to the coal fire flue gas emission port 2 and is used to capture and purify CO2 in the coal fire flue gas. The CO2 capture and purification unit 1 includes: a primary dust collector for removing particles with a diameter >5μm; a secondary electrostatic precipitator for removing particles with a diameter >0.5μm; an amine absorption tower for removing gaseous components other than CO2; and a CO2 purification unit to ensure that the output CO2 purity is ≥99.5%.

[0067] In practice, the CO2 capture and purification unit 1 is also connected in sequence to the replenishment regulating valve 5 and the replenishment interface 6, which is connected to the line from the cooling unit 7 to the compressor 4.

[0068] Furthermore, the controller is configured to prioritize the use of CO2 provided by the CO2 capture and purification unit 1, and when the capture amount is less than 60% of the system requirement, supplement the CO2 in the high-pressure CO2 storage tank 3; the high-pressure CO2 storage tank 3 is filled with CO2 with a purity of ≥99.9%, the working pressure is 35MPa, and the capacity is 15% of the total system charge.

[0069] This embodiment also proposes a coal-fired CO2 power generation method based on modular integration, which includes the following steps based on the aforementioned system:

[0070] Monitor the temperature distribution and trends in the coal fire area;

[0071] Based on the dynamic characteristics of temperature change trends, the control priority is determined: when the temperature changes drastically, the system pressure is stabilized first; when the temperature distribution is uneven, the heat load distribution is optimized first.

[0072] Based on the determined control priority, the compressor speed 4 and other operating parameters of the controller are adjusted synchronously.

[0073] The heat load ratio of each area heat exchange well in the underground heat exchange well group module 27 is dynamically adjusted to match the heat load distribution with the coal fire temperature distribution characteristics.

[0074] The power generation efficiency of the power generation module is continuously monitored, and the above-mentioned control parameters are fine-tuned based on the monitoring results to keep the efficiency fluctuation within ±3%.

[0075] Furthermore, in the step of dynamically adjusting the heat load ratio of each area heat exchange well in the underground heat exchange well group module 27:

[0076] When the rate of change of coal fire temperature is detected to exceed the first threshold, the heat load allocation of heat exchange wells in the area with the most drastic temperature change is reduced; when the temperature distribution gradient of coal fire is detected to exceed the second threshold, the heat load ratio of heat exchange wells in the temperature gradient boundary area is increased; through the above adjustments, the overall heat load fluctuation of the system is controlled within ±5%.

[0077] Furthermore, under the condition that the coal fire temperature change rate is >2.0℃ / min, the control priority mechanism first performs the heat load redistribution operation, then adjusts the compressor speed, and finally adjusts the CO2 replenishment amount.

[0078] Compared with existing technologies, the modularly integrated coal-fired CO2 power generation system provided in this embodiment has the following outstanding advantages:

[0079] This significantly improves the system's adaptability to unstable heat sources: This embodiment establishes a complete "monitoring-decision-execution" closed-loop control mechanism, capable of sensing the dynamic changes in the coal fire temperature field in real time and intelligently adjusting system operating parameters based on the severity and distribution of temperature changes. This dynamic control mechanism enables the system to effectively cope with the drastic temperature fluctuations unique to coal fire areas, ensuring the stability and continuity of the power generation process and solving the technical challenge of traditional power generation technologies being unable to adapt to unstable heat sources like coal fires.

[0080] The entire process of energy harvesting and conversion has been optimized: each stage of the system, from heat energy harvesting and transfer to conversion, has been specifically optimized. In the underground heat energy harvesting stage, intelligent zoning and differentiated well placement schemes have enabled efficient harvesting of heat energy from coal-fired areas; in the energy conversion stage, advanced thermodynamic circulation combined with efficient heat exchange technology has significantly improved heat energy utilization efficiency; in the waste heat recovery stage, innovative regenerative design has maximized the recovery and utilization of system waste heat, forming a complete energy cascade utilization system.

[0081] This system achieves an organic integration of environmental protection and energy regeneration: it combines coal fire control with energy utilization, converting harmful gases produced by coal fires into useful working fluids. This not only solves environmental pollution problems but also provides a stable source of working fluids for the system. This design concept of turning harm into benefit provides a completely new solution for coal fire control, achieving an organic unity of environmental and economic benefits.

[0082] A highly reliable and easy-to-maintain system architecture has been constructed: the modular design concept adopted by the system allows each functional module to work relatively independently yet collaboratively, greatly improving the system's maintainability and scalability. Through multiple protection mechanisms and an intelligent maintenance system, abnormal situations during operation can be detected and handled in a timely manner, ensuring that the system can maintain stable operation under various complex working conditions, significantly improving the system's reliability and service life.

[0083] This invention pioneers a new model for the resource utilization of coal fires: Breaking away from traditional approaches to coal fire management, this embodiment transforms coal fires from a simple environmental disaster into a valuable energy resource, establishing a complete multi-objective synergistic technical system encompassing disaster reduction, energy enhancement, and environmental protection. This model not only possesses significant technical value but also provides new ideas and directions for solving the global coal fire problem, exhibiting broad social significance and widespread applicability.

[0084] The system demonstrates excellent engineering applicability and promising prospects for widespread application: The system design fully considers the various needs of practical engineering applications, and the design of each module balances technological advancement with engineering feasibility. This results in a system with not only advanced technical specifications but also a solid foundation for engineering implementation. These technical characteristics make this embodiment widely applicable in various coal-fired areas, laying a solid foundation for large-scale promotion and application.

[0085] In summary, this embodiment has made significant progress in many aspects, including heat source adaptability, energy utilization efficiency, environmental protection, and system reliability, forming a complete and efficient coal-fired energy utilization technology solution with important technical value and promising prospects for promotion and application.

[0086] Example 2

[0087] This embodiment provides a modularly integrated coal-fired CO2 power generation system, the structure of which is as follows: Figure 1 As shown. The system includes a power generation module, an underground heat exchange well group module 27, and an adaptive control module. The modules are connected by pipelines and signal lines to form a complete energy harvesting and conversion system.

[0088] The power generation module is the core of the entire system, mainly composed of a turbine 12, a compressor 4, a microchannel regenerator 16, a cooling unit 7, and a generator 13. The turbine 12 and compressor 4 are connected via the same rotor shaft, with a diameter of 0.8–1.2 m and a designed power range of 1–5 MW. The inlet of the turbine 12 is connected to the high-temperature outlet of the microchannel regenerator 16, and the outlet is connected to the inlet of the cooling unit 7. The inlet of the compressor 4 is connected to the outlet of the cooling unit 7, and the outlet is connected to the low-temperature inlet of the microchannel regenerator 16. The microchannel regenerator 16 adopts a compact design with a heat exchange area of ​​not less than 50 m² / m³ and a channel width of 180–220 μm. When the channel width deviates from this range by ±30 μm, the heat transfer coefficient decreases by more than 15%. The microchannel surface is coated with a nano-coating to enhance heat transfer performance, improving the heat exchange efficiency near the critical point by ≥15%. In addition, a backflushing port is provided at the inlet of the microchannel regenerator 16, which is connected to the high-pressure CO2 storage tank 3 via a pipeline for periodically removing deposits within the microchannels. The cooling unit 7 employs either an independent cooler or an integrated cooling section of the microchannel regenerator 16 to reduce the sCO2 temperature from 80–100°C to 35–45°C. All components are fixed within the same frame via flange connections or welding, ensuring a compact overall structure and ease of maintenance.

[0089] The underground heat exchange well module 27 is responsible for collecting heat energy from the coal fire area and transferring it to the sCO2 working fluid. This module is strategically positioned based on the temperature distribution characteristics of the coal fire area, divided into temperature gradient zones and temperature uniform zones. In the temperature gradient zone, the well spacing is non-uniformly set according to the degree of temperature difference between adjacent areas; the greater the temperature difference, the smaller the well spacing, with a minimum of 1.0m and a maximum of 4.0m. In the temperature uniform zone, the well spacing is fixed at 6.0m. The depth of a single well ranges from 8.0 to 15.0m, with the specific depth increasing linearly according to the highest temperature value at its location. For example, when the highest temperature is 300℃, the well depth is 8.0m; when the highest temperature is 600℃, the well depth is 15.0m. A multi-way electric regulating valve group 17 is installed on the inlet pipeline. The main regulating valve controls the total flow rate, and the number of branch regulating valves matches the number of temperature gradient zones, with each branch regulating valve corresponding to one temperature gradient zone. Branch regulating valves are connected to the controller via signal lines. The controller dynamically adjusts the opening degree of each branch regulating valve based on real-time monitored temperature distribution characteristics, thereby achieving sCO2 flow distribution to heat exchange wells in different areas. The outlet manifold 21 of the underground heat exchange well group module 27 is connected to the inlet of the microchannel regenerator 16 of the power generation module via a first thermal expansion compensation pipe 18 and a second thermal expansion compensation pipe 20. The first thermal expansion compensation pipe 18 and the second thermal expansion compensation pipe 20 include corrugated pipe sections and high-temperature alloy compensators, with an axial compensation of ≥80mm and a temperature resistance of ≥750°C. Deformation monitoring signals are fed back to the controller via sensors to optimize the flow parameter control strategy of the sCO2 working fluid.

[0090] The adaptive control module includes a controller and a CO2 replenishment system. The controller is connected to the power generation module, the underground heat exchange well group module 27, and the CO2 replenishment system via signal lines. It monitors the temperature distribution characteristics of the coal fire area in real time and adjusts the system's operating parameters based on dynamic changes in temperature distribution. When the rate of change in coal fire temperature exceeds a preset threshold, the controller performs coordinated control operations: adjusting the speed of compressor 4 to match the change in CO2 working fluid density, adjusting the replenishment amount of the CO2 replenishment system to maintain stable system pressure, and prioritizing reducing heat load distribution to heat exchange wells in areas with drastic temperature changes to prevent localized overheating. The CO2 replenishment system also includes a CO2 capture and purification unit 1, connected to the coal fire flue gas emission outlet 2, for capturing and purifying CO2 in the coal fire flue gas. The CO2 capture and purification unit 1 includes a primary dust collector, a secondary electrostatic precipitator, an amine absorption tower, and a CO2 purification unit. The primary dust collector removes particles larger than 5 μm, the secondary electrostatic precipitator removes particles larger than 0.5 μm, the amine absorption tower removes gaseous components other than CO2, and the CO2 purification unit ensures the output CO2 purity is ≥99.5%. The controller is configured to prioritize the use of CO2 supplied by the CO2 capture and purification unit 1. When the captured amount is less than 60% of the system's requirement, CO2 is supplemented from the high-pressure CO2 storage tank 3. The high-pressure CO2 storage tank 3 is filled with CO2 with a purity ≥99.9%, operates at a pressure of 35 MPa, and has a capacity of 15% of the total system charge.

[0091] A CO2 working fluid purification module 19 is also installed between the power generation module and the underground heat exchange well group module 27. This module includes a primary filtration unit, a secondary purification unit, and an online monitoring unit. The primary filtration unit contains a sintered metal filter element with a pore size ≤5μm to remove solid particles carried by coal-fired flue gas. The secondary purification unit contains an activated alumina adsorption bed to remove corrosive gases such as SO2 / H2S. The online monitoring unit monitors the purity of the CO2 working fluid in real time, triggering a regeneration process when the particle concentration >5mg / m³ or the corrosive gas concentration >10ppm. The inlet of the CO2 working fluid purification module 19 is connected via a pipe to the outlet manifold 21 of the underground heat exchange well group module 27, and the outlet is connected via a pipe to the inlet of the microchannel regenerator 16 of the power generation module.

[0092] The system operates as follows: First, the underground heat exchange well module 27 collects heat energy from the coal fire area and transfers it to the microchannel regenerator 16 of the power generation module through thermal expansion compensation pipes. The microchannel regenerator 16 transfers heat to the sCO2 working fluid, raising its temperature and sending it to the turbine 12. The turbine 12 drives the generator 13 to generate electricity, while the sCO2 working fluid, after passing through the turbine 12, cools down and enters the cooling unit 7. The cooling unit 7 lowers the temperature of the sCO2 working fluid to 35–45°C, after which the working fluid enters the compressor 4 for compression, and then re-enters the microchannel regenerator 16 to complete the cycle. During this process, the controller of the adaptive control module monitors the temperature distribution and changing trend of the coal fire area in real time and determines the control priority based on dynamic characteristics. When the temperature changes drastically, the system pressure is stabilized first; when the temperature distribution is uneven, the heat load distribution is optimized first. The controller synchronously adjusts the speed and other operating parameters of the compressor 4 and dynamically adjusts the heat load ratio of each area of ​​the underground heat exchange well module 27 to match the heat load distribution with the temperature distribution characteristics of the coal fire. In addition, the controller continuously monitors the power generation efficiency of power generation module 1 and fine-tunes the above-mentioned control parameters based on the monitoring results, so that the efficiency fluctuation range is controlled within ±3%. Under the condition that the coal fire temperature change rate is >2.0℃ / min, the control priority mechanism first performs the heat load redistribution operation, then adjusts the speed of compressor 4, and finally adjusts the CO2 injection amount.

[0093] Through the above-mentioned technical means, this embodiment achieves efficient collection and stable conversion of coal-fired heat energy, solves the shortcomings of existing technologies in dealing with the instability and unevenness of coal-fired heat sources, and improves the overall efficiency and operational stability of the system.

[0094] Example 3

[0095] The specific implementation principle of Example 1 will be further explained in conjunction with specific application scenarios:

[0096] When the temperature distribution in the coal-fired area exhibits a significant gradient, the flow distribution of the sCO2 working fluid is first dynamically adjusted via the multi-port electric regulating valve group 17 in the underground heat exchange well group module 27. Specifically, the controller receives real-time data from temperature sensors and calculates the opening value of each branch regulating valve based on the division of temperature gradient zones and temperature uniform zones. For example, within a certain temperature gradient zone, if the temperature difference between adjacent zones is 200℃, the well spacing is set to 2.0m; if the temperature difference decreases to 50℃, the well spacing is increased to 4.0m. In this way, it is ensured that thermal energy in high-temperature zones is preferentially collected, while the heat exchange wells in the turbine outlet 23 area avoid ineffective operation. Furthermore, the depth of a single well increases linearly according to the highest temperature value at its location; when the highest temperature is 450℃, the well depth is set to 11.5m, thereby maximizing the efficiency of thermal energy collection.

[0097] Subsequently, the underground heat exchange well cluster module 27 transfers the collected heat energy to the microchannel regenerator 16 of the power generation module through the first thermal expansion compensation pipe 18 and the second thermal expansion compensation pipe 20. During this process, the corrugated pipe sections and high-temperature alloy compensators of the first thermal expansion compensation pipe 18 and the second thermal expansion compensation pipe 20 effectively absorb axial deformation caused by drastic temperature fluctuations, with an axial compensation amount ≥80mm and a temperature resistance ≥750°C. Deformation monitoring signals are fed back to the controller via sensors to optimize the flow parameter control strategy for the sCO2 working fluid. For example, when a pipe deformation exceeding 50mm is detected, the controller reduces the speed of the compressor 4 to decrease the working fluid flow rate, thereby alleviating the thermal stress on the pipe.

[0098] After entering the power generation module, the sCO2 working fluid undergoes heat exchange in the microchannel regenerator 16. The channel width of the microchannel regenerator 16 is strictly controlled within the range of 300–600 μm. This design enables the heat transfer coefficient of the sCO2 working fluid to reach 3200–3500 W / m²·K near the critical point. When the channel width deviates from this range by ±30 μm, the heat transfer coefficient decreases by more than 15%. In addition, the microchannel surface is coated with a nano-coating to enhance heat transfer performance, improving the heat exchange efficiency near the critical point by ≥15%. After heat exchange, the temperature of the sCO2 working fluid increases and it enters the turbine 12, driving the generator 13 to generate electricity. After power generation, the temperature of the sCO2 working fluid decreases and is cooled to 35–45°C by the cooling unit 7. It then enters the compressor 4 for compression and re-enters the microchannel regenerator 16 to complete the cycle.

[0099] During system operation, the adaptive control module's controller monitors the temperature distribution and trends in the coal fire area in real time and determines control priorities based on dynamic characteristics. For example, when the coal fire temperature change rate exceeds 2.0℃ / min, the controller prioritizes heat load redistribution, reducing the proportion of heat load in the heat exchange wells in areas with drastic temperature changes, while simultaneously adjusting the speed of compressor 4 to match the changes in sCO2 working fluid density. If system pressure fluctuates, the CO2 replenishment system adjusts the replenishment amount. Specifically, when the CO2 provided by CO2 capture and purification unit 1 is less than 60% of the system's requirement, the controller activates high-pressure CO2 storage tank 3 to replenish the system, ensuring stable system pressure.

[0100] Furthermore, the sCO2 working fluid purification module 19 plays a crucial role in the entire circulation process. The sintered metal filter element of the primary filtration unit has a pore size ≤5μm, effectively removing solid particles carried by coal-fired flue gas; the activated alumina adsorption bed of the secondary purification unit is used to remove corrosive gases such as SO2 / H2S. The online monitoring unit monitors the purity of the sCO2 working fluid in real time, triggering the purification unit regeneration program when the particle concentration >5mg / m³ or the corrosive gas concentration >10ppm. For example, when the detected particle concentration reaches 8mg / m³, the online monitoring unit immediately initiates the backwashing program of the primary filtration unit, using gas from the high-pressure CO2 storage tank 3 to remove deposits from the filter element surface.

[0101] Through the above steps, this embodiment achieves efficient collection and stable conversion of coal-fired thermal energy. For example, in a certain actual operation, when the temperature distribution in the coal-fired area exhibits significant non-uniformity, the system dynamically adjusts the heat load distribution to control the overall heat load fluctuation within ±5%, while simultaneously controlling the power generation efficiency fluctuation within ±3%. This effect is achieved through the controller's coordinated regulation of the compressor 4 speed, CO2 injection amount, and heat load distribution, as well as the automatic switching of the microchannel regenerator 16 to a high-turbulence operating mode near the critical point.

[0102] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A coal-fired CO2 power generation system based on modular integration, characterized in that, include: The power generation module, including the sCO2 Brayton cycle unit, is used to convert the thermal energy of coal into electrical energy; The underground heat exchange well group module (27) includes multiple heat exchange wells inserted into the coal fire area to transfer the thermal energy of the coal fire to the sCO2 working medium. The location and depth of the heat exchange wells are set differently according to the temperature distribution characteristics of the coal fire area. An adaptive control module includes a controller configured to monitor the temperature distribution characteristics of the coal fire area in real time, and dynamically adjust the heat load distribution of the underground heat exchange well group module (27) and the operating parameters of the power generation module based on the dynamic changes of the temperature distribution characteristics, so as to maintain the stability of power generation efficiency. The sCO2 Brayton cycle unit in the power generation module includes a turbine (12), a compressor (4), a generator (13), a microchannel regenerator 16, and a cooling unit (7). The turbine (12), compressor (4) and generator (13) are connected by the same rotor shaft; A turbine (12) is used to drive a generator (13) to generate electricity; the generator (13) is used to output electrical energy. Compressor (4), used to increase sCO2 pressure; The microchannel regenerator (16) includes a cold-side flow path and a hot-side flow path that are isolated from each other. The cold-side flow path is connected between the outlet of the compressor (4) and the inlet of the underground heat exchange well module (27), and the hot-side flow path is connected between the outlet of the turbine (12) and the inlet of the cooling unit (7). The cooling unit (7) is connected between the hot side flow path outlet of the microchannel regenerator 16 and the inlet of the compressor (4); The adaptive control module also includes a CO2 replenishment system. When the coal fire temperature change rate is detected to exceed the preset threshold, a coordinated control operation is performed. The coordinated control operation includes adjusting the compressor (4) speed to match the CO2 working fluid density change, adjusting the CO2 replenishment amount to maintain system pressure stability, and prioritizing the reduction of heat load distribution to heat exchange wells in areas with drastic temperature changes. The system also includes a first thermal expansion compensation pipe (18) and a second thermal expansion compensation pipe (20) connecting the outlet manifold (21) of the underground heat exchange well group module (27) and the power generation module. Both the first thermal expansion compensation pipe (18) and the second thermal expansion compensation pipe (20) include a corrugated pipe section and a high-temperature alloy compensator; The deformation monitoring signals of the first thermal expansion compensation pipe (18) and the second thermal expansion compensation pipe (20) are fed back to the controller to optimize the flow parameter control strategy of the sCO2 working fluid.

2. The system according to claim 1, characterized in that, The surface of the microchannel regenerator (16) is provided with a nano-coating. The channel width is preset to allow the sCO2 working fluid to reach a preset heat transfer coefficient near the critical point. When the channel width deviates from the preset range to a preset threshold, the heat transfer coefficient is adjusted.

3. The system according to claim 1, characterized in that, The underground heat exchange well group module (27) is arranged as follows: The coal fire zone is divided into a temperature gradient zone and a temperature uniform zone. In the temperature gradient region, the well spacing is set non-uniformly according to the degree of temperature difference between adjacent regions; the greater the temperature difference, the smaller the well spacing. In the temperature uniformity zone, a constant well spacing is maintained; The depth of a single well is determined based on the highest temperature value at its location; the higher the temperature, the greater the well depth.

4. The system according to claim 1, characterized in that, The inlet pipe of the underground heat exchange well group module (27) is equipped with a multi-way electric regulating valve group (17). The multi-way electric regulating valve group (17) includes a main regulating valve that controls the total flow and branch regulating valves that match the number of temperature gradient zones; The controller dynamically adjusts the CO2 flow rate of the heat exchange well in the area of ​​drastic temperature change by independently controlling the opening of the regulating valves of each branch, thereby realizing the redistribution of heat load.

5. The system according to claim 1, characterized in that, The CO2 replenishment system also includes a CO2 capture and purification unit (1); The CO2 capture and purification unit (1) includes a primary dust collector, a secondary electrostatic precipitator, an amine absorption tower, and a CO2 purification unit, which is connected to the coal fire flue gas outlet (2) for capturing and purifying CO2 in the coal fire flue gas.

6. The system according to claim 1, characterized in that, The system also includes an sCO2 working fluid purification module (19) disposed between the underground heat exchange well group module (27) and the power generation module, the sCO2 working fluid purification module (19) comprising: The primary filtration unit is used to remove solid particles carried by coal fire flue gas based on a sintered metal filter element. The secondary purification unit is used to remove corrosive gases based on an activated alumina adsorption bed; The online monitoring unit is used to detect the purity of the sCO2 working fluid in real time. When the purity does not reach the preset threshold, the purification unit regeneration program is triggered again. A high-pressure flushing unit is used to set a backflushing interface at the inlet of the microchannel regenerator (16), connect to a high-pressure CO2 storage tank (3), and periodically remove deposits in the microchannel.

7. A method for generating CO2 from coal-fired power plants based on modular integration, characterized in that, The system based on any one of claims 1-6 includes the following steps: Monitor the temperature distribution and trends in the coal fire area; Based on the dynamic characteristics of temperature change trends, the control priority is determined: when the temperature changes drastically, the system pressure is stabilized first; when the temperature distribution is uneven, the heat load distribution is optimized first. Based on the aforementioned control priority, the compressor (4) speed and other operating parameters of the controller are adjusted synchronously; The heat load ratio of heat exchange wells in each area is dynamically adjusted to match the heat load distribution with the temperature distribution characteristics of coal and fire. Continuously monitor power generation efficiency and fine-tune control parameters based on monitoring results to keep efficiency fluctuations within a preset range.

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