Coal fire sCO2 power generation system based on modular integration

Abstract

The invention discloses a coal fire sCO2 power generation system based on modular integration, and belongs to the technical field of coal fire heat energy utilization, and the coal fire sCO2 power generation system comprises a power generation module which comprises an sCO2 Brayton cycle unit and is used for converting coal fire heat energy into electric energy; the underground heat exchange well group module comprises a plurality of heat exchange wells inserted into a coal fire area and is used for transferring coal fire heat energy to the sCO2 working medium, and the arrangement positions and depths of the heat exchange wells are differentially set according to the temperature distribution characteristics of the coal fire area; and the self-adaptive regulation and control module comprises a controller, and the controller is configured to monitor the temperature distribution characteristics of the coal fire area in real time and dynamically adjust the thermal load distribution of the underground heat exchange well group module and the operation parameters of the power generation module based on the dynamic change of the temperature distribution characteristics so as to maintain the stability of the power generation efficiency. The method effectively overcomes the defect that a traditional power generation technology is insufficient in adaptability in a coal fire scene, and the overall power generation efficiency and operation stability of the system are remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of coal fire heat energy utilization, and particularly relates to a coal fire sCO2 power generation system based on modular integration. BACKGROUND

[0002] It is estimated that the direct loss of coal resources due to coal fire combustion worldwide is as high as hundreds of millions of tons per year, accompanied by the emission of a large amount of greenhouse gases such as carbon dioxide and toxic gases such as sulfides and carbon monoxide, posing a serious threat to regional ecological environment, residents' health and global climate. It is worth noting that while coal fires pose a threat, the enormous heat energy released by their continuous combustion itself constitutes a treasure trove of energy that has not been effectively developed and utilized. Therefore, achieving safe and efficient recovery and utilization of coal fire heat energy, with both disaster reduction and energy increase, has become a technical challenge that needs to be broken through in this field.

[0003] Current coal fire heat energy utilization practices face many technical bottlenecks, resulting in insufficient matching and poor implementation of existing technical solutions. The primary problem is that the coal fire heat source itself has extremely unstable and uneven characteristics. Coal fire, as a complex dynamic system, its combustion range, intensity and temperature field distribution are affected by multiple factors such as geological structure, coal seam fissure, oxygen supply and meteorological conditions, showing a dramatic fluctuation and random change. This highly dynamic heat source characteristic makes the traditional geothermal power generation or waste heat recovery technology based on stable working conditions design have serious adaptability problems in this scenario. Frequent sudden increase and decrease of thermal load during system operation not only leads to significant decline in power generation efficiency and thermal stress fatigue of equipment, but also may cause system shutdown or safety accidents.

[0004] In terms of power generation technology selection, the existing technical system is significantly mismatched with the characteristics of coal fire. The steam Rankine cycle uses water as the working medium, which faces difficulties in controlling the phase change process, large thermal inertia and slow response when dealing with dramatic heat source fluctuations, and is prone to cause problems such as pipe thermal shock, corrosion and fouling under high temperature gradient conditions, seriously affecting system reliability. Organic Rankine cycle is suitable for medium and low temperature heat sources, but the commonly used organic working medium has the defects of flammability, toxicity or environmental protection, and the system cycle efficiency is relatively low, which is difficult to meet the high efficiency conversion demand of large-scale coal fire heat energy. The thermoelectric direct conversion technology based on the Seebeck effect has a simple structure, but the energy conversion efficiency is generally less than 10%, and the manufacturing cost is high, making it difficult to realize industrialized power generation scale above megawatts.

[0005] In addition, the existing heat energy collection strategy is relatively rough, and the underground heat exchange well is usually uniformly arranged, which cannot effectively match the highly heterogeneous temperature distribution characteristics of the coal fire area, resulting in that the high-temperature area heat energy cannot be fully collected and the low-temperature area heat exchange well is in an inefficient operation state. At the system integration level, the existing technology lacks a systematic solution tailored to the characteristics of coal fire, often only focusing on the power generation unit itself, and cannot optimize the unstable underground heat source, efficient energy conversion device and intelligent control strategy as an organic whole, resulting in that the system is rigid when facing the dynamic changes of coal fire, and the adaptive control ability is obviously insufficient.

[0006] In summary, it is urgent to propose a systematic technical solution that can fundamentally adapt to the unstable and uneven inherent characteristics of coal fire heat energy and realize large-scale, high-efficiency and continuous stable power generation. SUMMARY

[0007] To solve the above technical problems, the present application proposes a coal fire sCO2 power generation system based on modular integration, comprising:

[0008] A power generation module comprising an sCO2 Brayton cycle unit for converting coal fire heat energy into electrical energy;

[0009] An underground heat exchange well group module comprising multiple heat exchange wells inserted into the coal fire area for transferring coal fire heat energy to the sCO2 working medium, and the layout position and depth of the heat exchange wells are differentially set according to the temperature distribution characteristics of the coal fire area;

[0010] An adaptive control module comprising 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 to maintain the stability of power generation efficiency.

[0011] Optionally, the sCO2 Brayton cycle unit in the power generation module comprises a turbine, a compressor, a generator, a micro-channel regenerator and a cooling unit;

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

[0013] The turbine is used to drive the generator to generate electricity; the generator is used to output electrical energy; and the compressor is used to increase the pressure of sCO2;

[0014] The micro-channel regenerator comprises a cold side flow path and a hot side flow path isolated from each other, wherein the cold side flow path is connected between the outlet of the compressor and the inlet of the underground heat exchange well group module, and the hot side flow path is connected between the outlet of the turbine and the inlet of the cooling unit;

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

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

[0017] Optionally, the underground heat exchange well group module is laid out in the following manner:

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

[0019] In the temperature gradient zone, the well spacing is non-uniformly set according to the temperature difference degree of adjacent areas, and the greater the temperature difference, the smaller the well spacing;

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

[0021] The single well depth is determined according to the highest temperature value at the location, and the higher the temperature, the greater the well depth.

[0022] Optionally, the inlet pipeline of the underground heat exchange well group module is provided with a multi-pass electric regulating valve group;

[0023] The multi-pass electric regulating valve group includes a main regulating valve for controlling the total flow and branch regulating valves matched with the number of temperature gradient zones;

[0024] The controller dynamically adjusts the sCO2 flow of the heat exchange well in the area with a rapid temperature change by independently controlling the opening degree of each branch regulating valve, thereby realizing heat load redistribution.

[0025] Optionally, the adaptive control module further includes a CO2 supplementing system, and when it is monitored that the coal fire temperature change rate exceeds a preset threshold, a cooperative control operation is performed, which includes adjusting the compressor speed to match the sCO2 working medium density change, adjusting the supplementing amount of the CO2 supplementing system to maintain system pressure stability, and preferentially reducing the heat load distribution of the heat exchange well in the area with a rapid temperature change.

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

[0027] The CO2 capture and purification unit includes a primary dust remover, a secondary electric dust remover, an amine absorption tower and a CO2 purification unit, is connected to the coal fire flue gas discharge port, and is used for capturing and purifying CO2 in the coal fire flue gas.

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

[0029] A primary filtration unit for removing solid particles carried by the coal fire flue gas based on a metal sintered filter element;

[0030] A secondary purification unit for removing corrosive gases based on an activated alumina adsorption bed;

[0031] An online monitoring unit for real-time detection of the purity of the sCO2 working medium, and when the purity fails to reach a preset threshold, a regeneration program of the purification unit is continuously triggered;

[0032] A high-pressure flushing unit for arranging a backwashing interface at the inlet of the micro-channel heat exchanger, connecting a high-pressure CO2 storage tank, and periodically removing deposits in the micro-channel.

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

[0034] The first thermal expansion compensation pipeline and the second thermal expansion compensation pipeline each comprise a corrugated pipe section and a high-temperature alloy compensator;

[0035] The deformation monitoring signals of the first thermal expansion compensation pipeline and the second thermal expansion compensation pipeline are fed back to the controller for optimizing the flow parameter control strategy of the sCO2 working medium.

[0036] The present application also provides a coal fire sCO2 power generation method based on modular integration, based on the system, comprising the following steps:

[0037] Monitoring the temperature distribution and change trend of the coal fire area;

[0038] According to the dynamic characteristics of the temperature change trend, the control priority is determined: when the temperature changes sharply, the system pressure is stabilized first, and when the temperature distribution is uneven, the heat load distribution is optimized first;

[0039] Based on the control priority, the compressor speed and other working parameters of the controller are adjusted synchronously;

[0040] The heat load proportion of each area heat exchange well is dynamically adjusted to match the heat load distribution with the temperature distribution characteristics of the coal fire;

[0041] The power generation efficiency is continuously monitored, and the control parameters are fine-tuned according to the monitoring results to control the efficiency fluctuation amplitude within a preset range.

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

[0043] The application realizes efficient collection and stable conversion of unstable and uneven coal fire heat energy by constructing a cooperative system composed of a power generation module, an underground heat exchange well group module and a self-adaptive regulation and control module, using a modular integrated architecture and a dynamic regulation and control strategy, effectively overcomes the insufficient adaptability of traditional power generation technology in this scenario, and significantly improves the overall power generation efficiency and operation stability of the system. BRIEF DESCRIPTION OF DRAWINGS

[0044] The accompanying drawings, which form a part of this application, are intended to provide further understanding of the application and are incorporated herein in their entirety, and the illustrative embodiments thereof and their description serve the explanation of the present application and do not constitute an inappropriate limitation to the present application. In the drawings:

[0045] Figure 1 The method flowchart of the embodiment of the present application is provided.

[0046] 1, CO2 capture and purification unit; 2, coal fire flue gas discharge port; 3, high-pressure CO2 storage tank; 4, compressor; 5, supplement injection regulating valve; 6, supplement injection 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, micro-channel regenerator; 17, multi-way electric regulating valve group; 18, first thermal expansion compensation pipeline; 19, sCO2 working medium purification module; 20, second thermal expansion compensation pipeline; 21, outlet header; 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 DESCRIPTION

[0047] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

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

[0049] Embodiment one

[0050] The embodiment provides a coal fire sCO2 power generation system based on modular integration, which includes three functional modules connected to each other.

[0051] (1) A power generation module comprising a sCO2 Brayton cycle unit, which includes a turbine 12, a compressor 4, a generator 13, a micro-channel recuperator 16, and a cooling unit 7; wherein the turbine 12 includes a turbine inlet 22 and a turbine outlet 23, the compressor 4 includes a compressor inlet 9 and a compressor outlet 10, the micro-channel recuperator 16 includes a cold side inlet 11 and a cold side outlet 15, and further includes a hot side inlet 14 and a hot side outlet 8; the cooling unit 7 is used to cool the sCO2 discharged from the turbine 12 to a temperature range of 35-45℃ at the compressor 4 inlet, the sCO2 working medium drives the turbine 12 to generate power at a pressure of 20-30 MPa, and the compressor 4 is the main circulating power source of the system, with a working pressure range of 20-30 MPa.

[0052] (2) An underground heat exchange well group module 27 comprising multiple heat exchange wells inserted into a coal fire area, for transferring the heat energy of the coal fire to the sCO2 working medium, the layout position and depth of the heat exchange wells are differentially set according to the temperature distribution characteristics of the coal fire area; wherein 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) An adaptive control module comprising a controller and a CO2 supplementing 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 of the temperature distribution; maintain the power generation efficiency of the power generation module within a stable range; wherein the controller identifies the rate and amplitude characteristics of the coal fire temperature change, preferentially reallocates the heat load of the heat exchange wells in the area with drastic temperature change, and adjusts the rotation speed of the compressor 4 and the flow parameters of the sCO2 working medium, so that the influence of the coal fire temperature fluctuation on the system power generation efficiency is reduced to within ±3%.

[0054] As an optional implementation, the controller is further configured to: when it is monitored that the coal fire temperature change presents a continuous rising trend, gradually increase the heat load proportion of the heat exchange wells in the high temperature area; when it is monitored that the coal fire temperature change presents a continuous falling trend, gradually reduce the heat load proportion of the heat exchange wells in the high temperature area; by dynamically adjusting the heat load distribution, the overall heat load distribution of the system is matched with the temperature distribution characteristics of the coal fire.

[0055] As can be implemented, in the power generation module: the turbine 12 has a design power of 1-5 MW and a rotor diameter of 0.8-1.2 m; the turbine 12, the compressor 4, and the generator 13 are connected through the same rotor shaft, forming a compact power transmission structure; the heat exchange area of the micro-channel recuperator 16 is ≥50 m² / m³; the pressure loss of the sCO2 working medium in the recuperator is ≤0.5 MPa.

[0056] Further, the micro-channel regenerator 16 has a channel width of 300-600 μm, which makes the heat transfer coefficient of sCO2 working medium near the critical point reach 3,200-3,500 W / m²·K, and when the channel width deviates from the range ± 30 μm, the heat transfer coefficient decreases by > 15%.

[0057] Further, the micro-channel regenerator 16 is configured to automatically switch to a high-turbulence working mode when the sCO2 working medium temperature approaches the critical point, and to enhance the heat transfer coefficient through a nano-coating on the surface of the micro-channel to improve the heat exchange efficiency near the critical point by ≥ 15%.

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

[0059] (a) an independent cooler including a shell-and-tube heat exchange structure, a cooling medium circulation system, and a temperature control valve, the cooling medium being 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 micro-channel regenerator 16, the heat exchange area of the integrated cooling section accounting for 25-35% of the total area of the regenerator, for cooling the sCO2 temperature from 80-100 °C to 35-45 °C.

[0061] Optionally, the layout of the underground heat exchange well group module 27 includes 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 temperature difference between adjacent areas, the greater the temperature difference, the smaller the well spacing, and in the temperature uniform zone, the well spacing remains constant, and the single well depth is determined according to the maximum temperature value at the location, the higher the temperature, the greater the well depth.

[0062] Further, the layout of the underground heat exchange well group module 27 further includes the following details: in the temperature gradient zone, the minimum well spacing is 1.0 m and the maximum well spacing is 4.0 m, in the temperature uniform zone, the well spacing is fixed at 6.0 m, and the single well depth ranges from 8.0-15.0 m, and the specific depth linearly increases according to the maximum temperature value at the location. For example, when the maximum temperature is 300 °C, the well depth is 8.0 m, and when the maximum temperature is 600 °C, the well depth is 15.0 m.

[0063] Optionally, the power generation module is connected to the outlet header 21 of the underground heat exchange well group module 27 through a first thermal expansion compensation pipeline 18 and a second thermal expansion compensation pipeline 20, the pipeline includes a corrugated pipe section and a high-temperature alloy compensator, the axial compensation amount of which is ≥ 80 mm and the temperature resistance is ≥ 750 °C, and the deformation monitoring signals of the first thermal expansion compensation pipeline 18 and the second thermal expansion compensation pipeline 20 are fed back to the controller for optimizing the flow parameter control strategy of the sCO2 working medium.

[0064] In an embodiment, the inlet pipeline of the underground heat exchange well group module 27 is provided with a multi-way electric regulating valve group 17, which includes a main road regulating valve for controlling the total flow, and branch regulating valves matching the number of temperature gradient zones, each branch regulating valve corresponding to a temperature gradient zone. The controller dynamically adjusts the sCO2 flow to different areas of the heat exchange well by independently controlling the opening of each branch regulating valve to achieve heat load redistribution. When heat load redistribution is implemented in areas with rapid temperature changes, the opening of the corresponding branch regulating valve is reduced by 20-30%.

[0065] In an embodiment, the system further includes an sCO2 working medium purification module 19 arranged between the outlet header 21 of the underground heat exchange well group module 27 and the power generation module, which includes a primary filter unit containing a metal sintered filter core with a pore size ≤5 μm for removing solid particles carried by the coal fire flue gas, a secondary purification unit containing an activated alumina adsorption bed for removing corrosive gases such as SO2 / H2S, an online monitoring unit for real-time detection of the purity of the sCO2 working medium, and a high-pressure flushing unit provided with a backwashing interface at the inlet of the micro-channel regenerator 16 connected to a high-pressure CO2 storage tank 3 for periodic removal of deposits in the micro-channels.

[0066] In an embodiment, the CO2 supplementing system further includes a CO2 capture and purification unit 1 connected to the coal fire flue gas discharge port 2 for capturing and purifying CO2 in the coal fire flue gas. The CO2 capture and purification unit 1 includes a primary dust remover for removing particles with a particle size >5 μm, a secondary electrostatic precipitator for removing particles with a particle size >0.5 μm, an amine absorption tower for removing gas components other than CO2, and a CO2 purification unit to make the output CO2 purity ≥99.5%.

[0067] In an embodiment, the CO2 capture and purification unit 1 is further connected to the supplementing regulating valve 5 and the supplementing interface 6 in sequence, and the supplementing interface 6 is connected to the line from the cooling unit 7 to the compressor 4.

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

[0069] The embodiment also proposes a coal fire sCO2 power generation method based on modular integration, based on the system, including the following steps:

[0070] monitoring the temperature distribution and change trend of the coal fire area;

[0071] determining the control priority according to the dynamic characteristics of the temperature change trend: when the temperature changes dramatically, the system pressure is stabilized first, and when the temperature distribution is uneven, the heat load distribution is optimized first;

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

[0073] dynamically adjusting the heat load proportion of each regional heat exchange well in the underground heat exchange well group module 27 to match the heat load distribution with the temperature distribution characteristics of the coal fire;

[0074] Continuously monitor the power generation efficiency of the power generation module, and fine-tune the above control parameters according to the monitoring results to control the efficiency fluctuation within ±3%.

[0075] Further, in the step of dynamically adjusting the heat load proportion of each regional heat exchange well in the underground heat exchange well group module 27:

[0076] When the coal fire temperature change rate is detected to exceed the first threshold value, the heat load distribution of the heat exchange well in the region with the most dramatic temperature change is reduced; when the coal fire temperature distribution gradient is detected to exceed the second threshold value, the heat load proportion of the heat exchange well in the region with the temperature gradient is increased; through the above adjustment, the overall heat load fluctuation of the system is controlled within ±5%.

[0077] Further, in the working condition of coal fire temperature change rate > 2.0℃ / min, the control priority mechanism preferentially performs heat load redistribution operation, secondly adjusts the compressor 4 speed, and finally adjusts the CO2 injection amount.

[0078] Compared with the prior art, the coal fire sCO2 power generation system based on modular integration provided by the embodiment has the following outstanding beneficial effects:

[0079] Significantly improve the adaptability of the system to unstable heat sources: the embodiment establishes a complete "monitoring-decision-execution" closed-loop control mechanism, which can real-time perceive the dynamic change characteristics of the coal fire temperature field, and intelligently adjust the system operation parameters according to the severity and distribution characteristics of the temperature change. This dynamic control mechanism enables the system to effectively cope with the unique temperature dramatic fluctuation characteristics of the coal fire area, ensuring the stability and continuity of the power generation process, and solving the technical problem that traditional power generation technology is difficult to adapt to the unstable heat source of coal fire.

[0080] The whole process of energy collection and conversion is optimized: the system is optimized from heat energy collection, transmission to conversion. In the underground heat energy collection link, through intelligent partitioning and differentiated well distribution scheme, efficient collection of heat energy in coal fire area is realized; in the energy conversion link, advanced heat cycle combined with efficient heat exchange technology is adopted, which greatly improves the heat energy utilization efficiency; in the waste heat recovery link, through innovative heat recovery design, the system waste heat is maximally recovered and utilized, forming a complete energy cascade utilization system.

[0081] The organic combination of environmental protection and energy regeneration is realized: the system combines coal fire treatment with energy utilization together, and converts harmful gases generated by coal fire into useful working medium, which not only solves the problem of environmental pollution, but also provides a stable source of working medium for the system. This design concept of changing harm into benefit provides a new solution for coal fire treatment, and realizes the organic unity of environmental benefits and economic benefits.

[0082] A highly reliable and easy-to-maintain system architecture is constructed: the modular design concept adopted by the system enables each functional module to work independently and cooperatively, greatly improving the maintainability and expandability of the system. Through multiple protection mechanisms and intelligent maintenance system, abnormal conditions in the running process can be found and handled in time, ensuring the stable operation of the system under various complex working conditions, and significantly improving the reliability and service life of the system.

[0083] A new mode of coal fire resource utilization is created: the embodiment breaks through the traditional coal fire treatment idea, changes the coal fire from a simple environmental disaster to a valuable energy resource, and establishes a complete disaster reduction-energy increase-environmental protection multi-target coordinated technology system. This mode not only has important technical value, but also provides a new idea and direction for solving the global coal fire problem, and has wide social significance and promotion value.

[0084] Good engineering applicability and promotion prospect are shown: the system design fully considers the various needs of actual engineering application, and the design of each module takes into account the advanced technology and engineering feasibility, so that the system not only has advanced technical indicators, but also has good engineering implementation foundation. This technical feature makes the embodiment have wide applicability in various coal fire areas, laying a solid foundation for large-scale popularization and application.

[0085] In summary, the embodiment has made significant progress in heat source adaptability, energy utilization efficiency, environmental protection, system reliability and other aspects, and formed a complete and efficient coal fire energy utilization technology scheme, which has important technical value and promotion application prospect.

[0086] Embodiment two

[0087] The embodiment provides a coal fire sCO2 power generation system based on modular integration, and a structure thereof is shown in the figure. Figure 1 The system comprises a power generation module, an underground heat exchange well group module 27 and a self-adaptive regulation and control module, and is connected through pipelines and signal lines to form a complete energy collection and conversion system.

[0088] The power generation module is a core part of the whole system, which mainly comprises a turbine 12, a compressor 4, a micro-channel regenerator 16, a cooling unit 7 and a generator 13. The turbine 12 and the compressor 4 are connected through the same rotor shaft, the rotor shaft has a diameter of 0.8-1.2 m, and the design power range is 1-5 MW. The inlet of the turbine 12 is connected with the high-temperature side outlet of the micro-channel regenerator 16, and the outlet is connected to the inlet of the cooling unit 7. The inlet of the compressor 4 is connected with the outlet of the cooling unit 7, and the outlet is connected to the low-temperature side inlet of the micro-channel regenerator 16. The micro-channel regenerator 16 adopts a compact design, the heat exchange area is not less than 50 m² / m³, and the channel width is set to 180-220 μm. When the channel width deviates from the range ± 30 μm, the heat transfer coefficient decreases by more than 15%. The micro-channel surface is coated with a nano coating to enhance the heat transfer performance, so that the heat exchange efficiency near the critical point is increased by more than 15%. In addition, a backwashing interface is arranged at the inlet of the micro-channel regenerator 16, the interface is connected to the high-pressure CO2 storage tank 3 through a pipeline, and is used for regularly removing the deposits in the micro-channel. The cooling unit 7 adopts an independent cooler or an integrated cooling section of the micro-channel regenerator 16, so that the sCO2 temperature is reduced from 80-100 °C to 35-45 °C. The above components are fixed in the same frame through flange connection or welding, so that the overall structure is compact and convenient to maintain.

[0089] The underground heat exchanger well group module 27 is responsible for collecting heat energy from the coal fire area and transferring it to the sCO2 working medium. This module is differentiated according to the temperature distribution characteristics of the coal fire area, and is divided into a temperature gradient zone and a temperature uniform zone. In the temperature gradient zone, the well spacing is set non-uniformly according to the temperature difference between adjacent areas. The greater the temperature difference, the smaller the well spacing, with a minimum value of 1.0 m and a maximum value of 4.0 m. In the temperature uniform zone, the well spacing is fixed at 6.0 m. The single well depth ranges from 8.0-15.0 m, and the specific depth increases linearly according to the maximum temperature value at the location. For example, when the maximum temperature is 300°C, the well depth is 8.0 m; when the maximum temperature is 600°C, the well depth is 15.0 m. The inlet pipeline is provided with a multi-pass electric regulating valve group 17. The main regulating valve is used to control the total flow, and the number of branch regulating valves matches the number of temperature gradient zones, with each branch regulating valve corresponding to a temperature gradient zone. The branch regulating valves are connected to the controller through a signal line, and the controller dynamically adjusts the opening of each branch regulating valve according to the real-time monitored temperature distribution characteristics, thereby realizing the sCO2 flow distribution to the heat exchanger wells of different areas. The outlet header 21 of the underground heat exchanger well group module 27 is connected to the micro-channel regenerator 16 inlet of the power generation module through the first thermal expansion compensation pipeline 18 and the second thermal expansion compensation pipeline 20. The first thermal expansion compensation pipeline 18 and the second thermal expansion compensation pipeline 20 contain corrugated pipe sections and high-temperature alloy compensators, with an axial compensation amount ≥80 mm and a temperature resistance ≥750°C. The deformation monitoring signal is fed back to the controller through the sensor, which is used to optimize the flow parameter control strategy of the sCO2 working medium.

[0090] The adaptive control module includes a controller and a CO2 supplement system. The controller is connected to the power generation module, the underground heat exchanger well group module 27 and the CO2 supplement system through signal lines, respectively, for real-time monitoring of the temperature distribution characteristics of the coal fire area, and adjusting the operating parameters of the system based on the dynamic changes of the temperature distribution. When the coal fire temperature change rate exceeds the preset threshold, the controller performs a coordinated control operation: adjusts the speed of the compressor 4 to match the sCO2 working medium density change, adjusts the supplement amount of the CO2 supplement system to maintain the system pressure stable, preferentially reduces the heat load distribution of the heat exchanger well in the area with drastic temperature change, and prevents local overheating. The CO2 supplement system also includes a CO2 capture and purification unit 1 connected to the coal fire flue gas discharge port 2 for capturing and purifying CO2 in the coal fire flue gas. The CO2 capture and purification unit 1 includes a primary dust remover, a secondary electric dust remover, an amine absorption tower and a CO2 purification unit. The primary dust remover is used to remove particles with a particle size > 5 μm, the secondary electric dust remover is used to remove particles with a particle size > 0.5 μm, the amine absorption tower is used to remove gas components other than CO2, and the CO2 purification unit makes the output CO2 purity ≥ 99.5%. The controller is configured to preferentially use CO2 provided by the CO2 capture and purification unit 1, and when the capture amount is less than 60% of the system demand, supplement with CO2 in the high-pressure CO2 storage tank 3. The high-pressure CO2 storage tank 3 is filled with CO2 with a purity ≥ 99.9%, a working pressure of 35 MPa, and a capacity of 15% of the total supplement amount of the system.

[0091] A sCO2 working medium purification module 19 is also provided between the power generation module and the underground heat exchanger well group module 27, which includes a primary filter unit, a secondary purification unit and an online monitoring unit. The primary filter unit contains a metal sintered filter core with a pore size ≤ 5 μm for removing solid particles carried by the coal fire flue gas; the secondary purification unit contains an activated alumina adsorption bed for removing corrosive gases such as SO2 / H2S; the online monitoring unit detects the purity of the sCO2 working medium in real time, and when the particle concentration > 5 mg / m³ or the corrosive gas concentration > 10 ppm, the purification unit regeneration program is triggered. The inlet of the sCO2 working medium purification module 19 is connected to the outlet header 21 of the underground heat exchanger well group module 27 through a pipeline, and the outlet is connected to the inlet of the micro-channel regenerator 16 of the power generation module through a pipeline.

[0092] The operation process of the system is as follows: first, the underground heat exchange well group module 27 collects heat energy from the coal fire area, and transmits the heat to the micro-channel heat exchanger 16 of the power generation module through the heat expansion compensation pipe. The micro-channel heat exchanger 16 transmits heat to the sCO2 working medium, so that the temperature of the sCO2 working medium is increased and enters the turbine 12. The turbine 12 drives the generator 13 to generate electricity, and at the same time, the sCO2 working medium is cooled after passing through the turbine 12 and enters the cooling unit 7. After the sCO2 working medium is cooled to 35-45℃ by the cooling unit 7, the working medium is compressed by the compressor 4 and then enters the micro-channel heat exchanger 16 again to complete the cycle. In this process, the controller of the adaptive control module monitors the temperature distribution and change trend of the coal fire area in real time, and determines the control priority according to the dynamic characteristics. When the temperature changes sharply, the system pressure is stabilized first; when the temperature distribution is uneven, the heat load distribution is optimized first. The controller synchronously adjusts the rotating speed of the compressor 4 and other working parameters, and dynamically adjusts the heat load proportion of each area heat exchange well in the underground heat exchange well group module 27, so that the heat load distribution matches the temperature distribution characteristics of the coal fire. In addition, the controller continuously monitors the power generation efficiency of the power generation module 1, and adjusts the above control parameters according to the monitoring results, so that the efficiency fluctuation amplitude is controlled within ±3%. In the working condition of the coal fire temperature change rate >2.0℃ / min, the heat load redistribution operation is preferentially executed by the control priority mechanism, the rotating speed of the compressor 4 is adjusted secondly, and the CO2 supplement amount is adjusted lastly.

[0093] Through the above technical means, the embodiment realizes efficient collection and stable conversion of coal fire heat energy, solves the deficiencies of the prior art in dealing with the instability and unevenness of coal fire heat source, and improves the overall efficiency and operation stability of the system.

[0094] Embodiment Three

[0095] The specific implementation principle of embodiment one is supplemented in combination with specific application scenarios:

[0096] In the case that the temperature distribution of the coal fire area presents a significant gradient change, the flow distribution of the sCO2 working medium is first dynamically adjusted by the multi-way electric regulating valve group 17 in the underground heat exchange well group module 27. Specifically, the controller receives real-time data from the temperature sensor, and calculates the opening value of each branch regulating valve according to the division result of the temperature gradient zone and the temperature uniform zone. For example, in a certain temperature gradient zone, if the temperature difference between adjacent areas is 200℃, the well spacing is set to 2.0m; if the temperature difference is reduced to 50℃, the well spacing is expanded to 4.0m. In this way, the heat energy of the high-temperature area is preferentially collected, and the heat exchange well in the turbine outlet 23 domain is prevented from invalid operation. In addition, the single-well depth is linearly increased according to the maximum temperature value at the location, and when the maximum temperature is 450℃, the well depth is set to 11.5m, so as to maximize the heat energy collection efficiency.

[0097] Subsequently, the collected heat energy is transferred to the micro-channel recuperator 16 of the power generation module through the first thermal expansion compensation pipeline 18 and the second thermal expansion compensation pipeline 20. In this process, the bellows section of the first thermal expansion compensation pipeline 18 and the second thermal expansion compensation pipeline 20 and the high-temperature alloy compensator can effectively absorb the axial deformation caused by the sharp fluctuation of temperature, with an axial compensation amount ≥ 80 mm and a temperature resistance ≥ 750 °C. The deformation monitoring signal is fed back to the controller through the sensor for optimizing the flow parameter control strategy of the sCO2 working medium. For example, when the pipeline deformation amount is detected to exceed 50 mm, the controller will reduce the speed of the compressor 4 to reduce the flow rate of the working medium, thereby relieving the thermal stress of the pipeline.

[0098] After entering the power generation module, the sCO2 working medium completes heat exchange in the micro-channel recuperator 16. The channel width of the micro-channel recuperator 16 is strictly controlled within the range of 300-600 μm, which makes the heat transfer coefficient of the sCO2 working medium near the critical point reach 3200-3500 W / m²·K. When the channel width deviates from this range by ± 30 μm, the heat transfer coefficient decreases by more than 15%. In addition, the micro-channel surface is coated with a nano coating to enhance the heat transfer performance, which increases the heat exchange efficiency near the critical point by ≥ 15%. After heat exchange, the sCO2 working medium temperature rises and enters the turbine 12 to drive the generator 13 to generate electricity. After power generation, the sCO2 working medium temperature decreases and is reduced to 35-45 °C through the cooling unit 7, and then enters the compressor 4 for compression and enters the micro-channel recuperator 16 again to complete the cycle.

[0099] During system operation, the controller of the adaptive control module monitors the temperature distribution and change trend of the coal fire area in real time, and determines the control priority according to the dynamic characteristics. For example, when the coal fire temperature change rate is detected to exceed 2.0 °C / min, the controller preferentially performs the heat load redistribution operation to reduce the heat load proportion of the heat exchange well in the area with sharp temperature change, and adjusts the speed of the compressor 4 to match the sCO2 working medium density change. If the system pressure fluctuates, the CO2 supplement system is adjusted to adjust the supplement amount. Specifically, when the amount of CO2 provided by the CO2 capture and purification unit 1 is less than 60% of the system demand, the controller starts the high-pressure CO2 storage tank 3 to supplement, ensuring the stability of the system pressure.

[0100] In addition, the sCO2 working fluid purification module 19 plays a key role in the entire cycle. The metal sintered filter element of the primary filtration unit has a pore size of ≤5 μm, which can effectively remove solid particles carried by the coal fire 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 detects the purity of the sCO2 working fluid in real time, and when the particle concentration > 5 mg / m³ or the corrosive gas concentration > 10 ppm, the regeneration program of the purification unit is triggered. For example, when the particle concentration is detected to be 8 mg / m³, the online monitoring unit immediately starts the backwashing program of the primary filtration unit, and uses the gas in the high-pressure CO2 storage tank 3 to remove the deposits on the surface of the filter element.

[0101] Through the above steps, the present embodiment realizes efficient collection and stable conversion of coal fire heat energy. For example, in a certain actual operation, when the temperature distribution of the coal fire area is significantly uneven, the system dynamically adjusts the heat load distribution, so that the overall heat load fluctuation is controlled within ±5%, and the power generation efficiency fluctuation is controlled within ±3%. The realization of this effect benefits from the coordinated regulation of the controller on the rotation speed of the compressor 4, the CO2 supplement amount and the heat load distribution, and the automatic switching of the micro-channel regenerator 16 to the high-turbulence working mode near the critical point.

[0102] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical scope disclosed in the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A modularly integrated coal-fired sCO2 power generation system, characterized by, 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. 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 (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.

2. The system according to claim 1, characterized in that, 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).

3. The system according to claim 2, 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.

4. 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.

5. 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.

6. The system according to claim 1, characterized in that, The adaptive control module further comprises a CO2 supplement system, when the monitored temperature change rate of the coal fire exceeds the preset threshold, the cooperative control operation is performed, the cooperative control operation comprises adjusting the rotating speed of the compressor (4) to match the density change of the sCO2 working medium, adjusting the supplement amount of the CO2 supplement system to maintain the stability of the system pressure, and preferentially reducing the heat load distribution of the heat exchange well in the region with sharp temperature change.

7. The system of claim 6, wherein, The CO2 supplement system further comprises a CO2 capture and purification unit (1); The CO2 capture and purification unit (1) comprises a primary dust remover, a secondary electric dust remover, an amine absorption tower and a CO2 purification unit, and is connected to the coal fire flue gas discharge port (2) for capturing and purifying CO2 in the coal fire flue gas.

8. The system of claim 1, wherein, The system further comprises an sCO2 working medium purification module (19) arranged between the underground heat exchange well group module (27) and the power generation module, and the sCO2 working medium purification module (19) comprises: a primary filter unit for removing solid particles carried by the coal fire flue gas based on a metal sintered filter element; a secondary purification unit for removing corrosive gases based on an activated alumina adsorption bed; an online monitoring unit for real-time detection of the purity of the sCO2 working medium, and when the purity does not reach the preset threshold, the regeneration program of the purification unit is continuously triggered; a high-pressure flushing unit for setting a backwashing interface at the inlet of the micro-channel heat exchanger (16) and connecting a high-pressure CO2 storage tank (3) to periodically remove deposits in the micro-channel.

9. The system of claim 1, wherein, The system further comprises a first thermal expansion compensation pipeline (18) and a second thermal expansion compensation pipeline (20) connected between the outlet header (21) of the underground heat exchange well group module (27) and the power generation module; The first thermal expansion compensation pipeline (18) and the second thermal expansion compensation pipeline (20) each comprise a corrugated pipe section and a high-temperature alloy compensator; The deformation monitoring signals of the first thermal expansion compensation pipeline (18) and the second thermal expansion compensation pipeline (20) are fed back to the controller for optimizing the flow parameter control strategy of the sCO2 working medium.

10. A modularly integrated coal-fired sCO2 power generation method, characterized by, The system according to any one of claims 1-9, comprising the following steps: monitoring the temperature distribution and change trend of the coal fire area; determining the control priority according to the dynamic characteristics of the temperature change trend: when the temperature changes sharply, the system pressure is preferentially stabilized, and when the temperature distribution is uneven, the heat load distribution is preferentially optimized; based on the control priority, synchronously adjusting the rotating speed of the compressor (4) and other working parameters of the controller; dynamically adjusting the heat load proportion of each region heat exchange well to make the heat load distribution match the temperature distribution characteristics of the coal fire; continuously monitoring the power generation efficiency and fine-tuning the control parameters according to the monitoring results to control the efficiency fluctuation within the preset range.

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