Supercritical gas-fired boiler based on tower type arrangement and thermal optimization control method

Abstract

The invention discloses a supercritical gas-fired boiler based on tower type arrangement and a thermal optimization control method, and relates to the field of supercritical gas-fired boilers, the supercritical gas-fired boiler comprises a hearth, a burner, a water cooling wall, a heating surface in the boiler, a header outside the boiler, an economizer and a tubular air preheater. The periphery of the hearth is wrapped by an ash bucket water-cooled wall, a spiral tube coil water-cooled wall and a vertical tube coil water-cooled wall, in-furnace heating surfaces are sequentially arranged in the smoke flowing direction and are suspended through in-furnace suspension tubes, and an out-furnace collecting box is suspended through out-furnace suspension tubes; the economizer is divided into an upper stage and a lower stage, is arranged by adopting sequential tube bundles and is provided with a bypass, and a denitration reactor is arranged between the upper stage and the lower stage; the suspension pipe is made of high-strength alloy steel, a working medium flows in the suspension pipe, and a heating surface and related parts are made of alloy materials with adaptive performance. The invention has the technical effects of high safety of the wall temperature of the heated surface, small deviation, small occupied area, low smoke, wind, steam and water resistance, smooth expansion system, adaption to the rapid variable load requirement, excellent environmental protection property, reliable operation and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of supercritical gas-fired boilers, in particular to a supercritical gas-fired boiler based on a tower arrangement and a thermal optimization control method. BACKGROUND

[0002] Under the macro-background of jointly addressing climate change and vigorously promoting the "double carbon" target, the energy industry is undergoing profound changes. As a relatively clean transitional energy form, gas-fired power generation is crucial to efficiency improvement and carbon emission control. To meet increasingly stringent environmental protection requirements and strengthen energy resource utilization efficiency, gas-fired boiler technology continues to iterate and upgrade, with operating parameters (such as steam pressure and temperature) constantly improving, moving from traditional subcritical to efficient supercritical, and even higher parameters.

[0003] However, the traditional "П" type or box type boiler layout faces many bottlenecks when dealing with high temperature and high pressure, especially in pursuit of higher thermal efficiency at supercritical parameters. First, the flexibility of the heating surface arrangement is insufficient, making it difficult to optimally configure according to the thermal requirements under supercritical parameters, resulting in insufficient heat utilization and affecting boiler efficiency. Second, thermal expansion coordination is complex. In a high temperature and high pressure environment, the thermal expansion amounts of various components of the boiler are different. The structural design of the traditional layout results in more constraints between components, which can easily generate a large amount of thermal stress, affecting the service life of the boiler and possibly causing safety hazards. Third, large-scale development is limited. As power demand grows, boilers need to develop towards larger sizes, but the "П" type or box type layout is difficult to achieve larger scale design in terms of structure, limited by space and structural strength. In addition, it is difficult to achieve a better flue gas process. The flue gas flow path of the traditional layout is not reasonable, resulting in high flue gas resistance, increasing the energy consumption of the fan, and also affecting the heat transfer effect, which is not conducive to improving thermal efficiency.

[0004] Therefore, those skilled in the art are committed to developing a gas-fired boiler that can break through the limitations of traditional structures, adapt to supercritical parameters, and have higher efficiency, better environmental performance, and more reliable operation. SUMMARY

[0005] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present application is the rigid heating surface arrangement, complex thermal expansion coordination, large floor area, poor flue gas process, insufficient coal economizer protection, and low denitration integration of the traditional boiler layout under supercritical parameters, as well as the problems of existing tower boilers in fine control, heat transfer enhancement, and combustion optimization.

[0006] To achieve the above-mentioned purpose, the present application provides a supercritical gas-fired boiler based on a tower arrangement, comprising a furnace, a burner, a water wall, an in-furnace heating surface, an out-furnace header, a coal economizer, and an air preheater.

[0007] The furnace is arranged in a single-furnace tower type and is surrounded by water-cooled walls.

[0008] The burner has a staged air distribution structure, including main combustion zone nozzles, transition zone nozzles and burnout zone nozzles arranged in layers along the height of the furnace; the burner has a staged air distribution structure, including main combustion zone nozzles, transition zone nozzles and burnout zone nozzles arranged in layers along the height of the furnace, and works with dual-fluid internal mixing atomizing nozzles to achieve high-efficiency low-NOx combustion.

[0009] The water-cooled wall includes an ash hopper water-cooled wall, a spiral tube coil water-cooled wall, and a vertical tube coil water-cooled wall; the ash hopper water-cooled wall is located at the bottom of the furnace, the spiral tube coil water-cooled wall is located in the lower part of the furnace, and the vertical tube coil water-cooled wall is located in the upper part of the furnace; the spiral tube coil water-cooled wall and the vertical tube coil water-cooled wall adopt a segmented variable flow control structure, each segment is equipped with an independent flow regulating valve and a wall temperature monitoring sensor, and the sensor is connected to the boiler control system signal to realize dynamic and precise control of the wall temperature;

[0010] The furnace heating surfaces, along the flue gas flow direction, sequentially include a screen-type superheater (6), a high-temperature superheater (7), a high-temperature reheater (8), an evaporator (9), a low-temperature reheater (11), and a low-temperature superheater (10); the fins of the furnace heating surfaces are inclined flow guiding structures; this optimizes flue gas flow and reduces ash accumulation.

[0011] The furnace heating surface is suspended by the furnace suspension pipe (12), and the furnace external header is suspended by the furnace external suspension pipe (13);

[0012] The economizer includes an upper economizer (14) and a lower economizer (16), which are arranged in the flue gas duct with the tail outlet pointing downwards along the flue gas direction;

[0013] The air preheater is located inside the steel frame at the rear of the furnace.

[0014] The boiler is designed with supercritical parameters, equipped with a balanced ventilation system and a single reheat process. Its all-steel frame and fully suspended structure are adapted to the thermal expansion requirements under supercritical conditions, making it a high-efficiency gas-fired once-through boiler.

[0015] Preferably, the spiral tube coil water-cooled wall and the ash hopper water-cooled wall are seamlessly connected, with the same pipe diameter at the connection point. This seamless connection and consistent pipe diameter design ensures the sealing performance and structural integrity of the water-cooled wall system, preventing working fluid leakage under high temperature and pressure.

[0016] Preferably, the heating surfaces of the screen-type superheater, high-temperature superheater, high-temperature reheater, evaporator, low-temperature reheater, and low-temperature superheater are all made of alloy steel with good thermal conductivity and high-temperature corrosion resistance. Good thermal conductivity can improve heat transfer efficiency and ensure the stability of boiler heat output; high-temperature corrosion resistance can resist flue gas erosion and corrosion, reducing maintenance costs. The heating surface pipes adopt an internal thread structure with an internal thread depth of 0.8-1.2mm and a thread pitch of 10-15mm, which enhances the heat transfer coefficient by increasing the turbulence of the working fluid.

[0017] Preferably, the in-furnace and external suspension pipes are made of high-strength alloy steel; a working fluid flows inside the in-furnace and external suspension pipes. The high-strength alloy steel meets the load-bearing requirements of the heating surface and header, and the internal working fluid flow provides real-time cooling to the suspension pipes, preventing overheating damage from prolonged exposure to high-temperature flue gas and improving the reliability of the suspension structure. The in-furnace and external suspension pipes are equipped with an adaptive working fluid flow control loop, which adjusts the working fluid flow in real-time based on wall temperature feedback. This adaptive control loop includes a flow sensor, an electric regulating valve, and a wall temperature monitoring probe. The wall temperature monitoring probe is installed in the high-temperature region of the middle section of the suspension pipe and is connected to the boiler control system. When the temperature exceeds 580℃, the valve opening automatically increases to increase the cooling flow; when the temperature is below 450℃, the opening is appropriately reduced to lower energy consumption. The adjustment response time is ≤3s, ensuring that the operating temperature of the suspension pipe remains stable within the 450℃-580℃ range.

[0018] Preferably, the tube bundles of the upper and lower economizers are arranged in a parallel configuration, and the spacing between the tube bundles is designed based on the flue gas flow rate and velocity. The parallel arrangement facilitates ash removal and reduces the risk of ash accumulation and blockage; the spacing designed based on flue gas parameters reduces flue gas flow resistance while ensuring sufficient heat transfer area and improving waste heat recovery efficiency. The surface of the economizer tube bundles is coated with an Al2O3-TiO2 composite porous coating with a thickness of 50-80 μm and a porosity of 30%-40%. This coating improves the tube wall's resistance to high-temperature corrosion, extends its service life, and enhances both radiative and convective heat transfer.

[0019] Preferably, the upper and lower economizers are equipped with economizer bypasses. During boiler startup or low-load operation, the feedwater can be diverted by opening the economizer bypass to prevent overheating of the economizer tube walls due to excessively high flue gas temperature or excessively low water flow velocity. The surface of the economizer tube bundle is coated with a composite porous coating, and the bypass and the denitrification reactor form a closed-loop temperature control system.

[0020] Preferably, the air preheater is a tubular air preheater, and the tubular air preheater is provided with spiral baffles inside the pipe. The height of the baffles is 1 / 5 to 1 / 3 of the inner diameter of the pipe to enhance the turbulence of cold air. The outer surface of the pipe has a corrugated structure with alternating concave and convex surfaces, and the vibration generated by the flue gas flow pressure difference achieves self-cleaning.

[0021] Preferably, a denitrification reactor is arranged between the upper economizer and the lower economizer, using SCR denitrification technology. A reducing agent is injected into the flue gas through an ammonia injection grid, and NOx is converted into nitrogen and water under the action of a catalyst, with a denitrification efficiency of ≥90%.

[0022] Beneficial technical effects of the present invention:

[0023] This invention employs a tower-style arrangement, which offers numerous advantages.

[0024] (1) The tower boiler design has a small deviation and higher wall temperature safety of the heating surface. Because the heating surface is arranged horizontally and in a reasonable manner, the heat absorption uniformity of each heating surface is better, the wall temperature deviation is small, and the risk of damage caused by local overheating is reduced.

[0025] (2) It occupies a small area. The tower layout arranges the boiler components vertically, which greatly saves horizontal space and is suitable for use in situations where space is limited.

[0026] (3) Tower boilers have lower resistance to flue gas, steam and water. The reasonable design of flue gas and steam and water flow paths reduces resistance loss during the flow process and reduces the energy consumption of equipment such as fans.

[0027] (4) The expansion system of the tower boiler is smoother and simpler, and is more suitable for the needs of rapid load change. The thermal expansion of each component can be carried out more freely in the vertical direction, reducing mutual constraints and stress, so that the boiler can respond quickly during load change and operate more stably and reliably.

[0028] The following will further explain the concept, specific structure, and technical effects of the present invention in conjunction with the accompanying drawings, so as to fully understand the purpose, features, and effects of the present invention. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the overall structure of the supercritical gas-fired boiler based on a tower arrangement according to the present invention.

[0030] In the diagram: 1. Furnace; 2. Burner; 3. Ash hopper water-cooled wall; 4. Spiral tube water-cooled wall; 5. Vertical tube water-cooled wall; 6. Screen-type superheater; 7. High-temperature superheater; 8. High-temperature reheater; 9. Evaporator; 10. Low-temperature superheater; 11. Low-temperature reheater; 12. In-furnace suspended tubes; 13. Out-of-furnace suspended tubes; 14. Upper economizer; 15. Denitrification reactor; 16. Lower economizer; 17. Air preheater. Detailed Implementation

[0031] The following description, with reference to the accompanying drawings, illustrates several preferred embodiments of the present invention to make its technical content clearer and easier to understand. The present invention can be embodied in many different forms, and the scope of protection of the present invention is not limited to the embodiments mentioned herein.

[0032] In the accompanying drawings, components with the same structure are indicated by the same numerical designation, and components with similar structures or functions are indicated by similar numerical designations. The dimensions and thicknesses of each component shown in the drawings are arbitrary, and the present invention does not limit the dimensions and thicknesses of each component. To make the illustrations clearer, the thickness of some components has been appropriately exaggerated in the drawings.

[0033] like Figure 1 As shown, the present invention provides a supercritical gas-fired boiler based on a tower arrangement, including a furnace 1, a burner 2, a water-cooled wall, an internal heating surface, an external header, an economizer, and an air preheater.

[0034] The furnace 1 adopts a single-furnace tower arrangement, surrounded by water-cooled walls;

[0035] The burner 2 is located in the lower part of the furnace 1;

[0036] The water-cooled wall includes an ash hopper water-cooled wall 3, a spiral tube coil water-cooled wall 4, and a vertical tube coil water-cooled wall 5. The ash hopper water-cooled wall 3 is located at the bottom of the furnace 1, the spiral tube coil water-cooled wall 4 is located in the lower part of the furnace 1, and the vertical tube coil water-cooled wall 5 is located in the upper part of the furnace. The spiral tube coil water-cooled wall 4 and the vertical tube coil water-cooled wall 5 adopt a segmented variable flow control structure. Each segment is equipped with an independent flow regulating valve and a wall temperature monitoring sensor. The sensor collects the tube wall temperature data in real time and transmits it to the boiler control system. The control system adopts a PID-Smith predictive control algorithm to dynamically adjust the flow rate of the working fluid in the tube, so that the wall temperature deviation of each water-cooled wall segment is controlled within ±10℃, adapting to the heat load distribution differences of furnaces at different heights.

[0037] The furnace heating surfaces, along the flue gas flow direction, include, in sequence, a screen-type superheater 6, a high-temperature superheater 7, a high-temperature reheater 8, an evaporator 9, a low-temperature reheater 11, and a low-temperature superheater 10.

[0038] The furnace heating surface is suspended by the furnace suspension pipe 12, and the furnace external header is suspended by the furnace external suspension pipe 13;

[0039] The economizer includes an upper economizer 14 and a lower economizer 16, which are arranged in the flue with the tail outlet facing downward along the flue gas direction;

[0040] The air preheater is located inside the steel frame at the rear of the furnace.

[0041] The spiral tube water-cooled wall 4 and the ash hopper water-cooled wall 3 are seamlessly connected, with the same pipe diameter at the connection point, and both are made of high-temperature resistant alloy material (such as SA-213TP347H). The seamless connection and consistent pipe diameter design ensure the sealing performance and structural integrity of the water-cooled wall system, preventing working fluid leakage under high temperature and high pressure. The high-temperature resistant alloy material is suitable for the high-temperature environment in the lower part of the furnace, extending its service life.

[0042] The heating surfaces of the screen-type superheater 6, high-temperature superheater 7, high-temperature reheater 8, evaporator 9, low-temperature reheater 11, and low-temperature superheater 10 are all made of alloy steel with good thermal conductivity and high-temperature corrosion resistance (e.g., Super304H for the high-temperature section and SA-213TP304H for the low-temperature section). The heating surface pipes adopt an internal thread structure with a thread depth of 0.8-1.2mm and a pitch of 10-15mm. By enhancing the turbulence of the working fluid inside the pipe, the heat transfer coefficient is improved, resulting in a 20%-25% increase in heat transfer efficiency compared to a bare pipe structure. At the same time, the fins of the heating surface adopt an inclined flow-guiding structure with an angle of 3°-8° between the fins and the axis of the heating surface pipe. They are arranged in a streamlined manner along the flue gas flow direction. On the one hand, this guides the flue gas to flow smoothly, reducing eddy current losses and reducing flue gas resistance. On the other hand, the scouring force of the flue gas can be used to achieve self-cleaning of the fin surface, reducing the ash accumulation thickness and controlling the ash accumulation rate to below 5%. Good thermal conductivity can improve heat transfer efficiency and ensure the stability of boiler heat output; high temperature corrosion resistance can resist flue gas erosion and corrosion, reducing maintenance costs.

[0043] The furnace-in-place suspension pipe 12 and the furnace-outside suspension pipe 13 are made of high-strength alloy steel (such as SA-213T91); working fluid flows inside the furnace-in-place suspension pipe 12 and the furnace-outside suspension pipe 13. The furnace-in-place suspension pipe 12 and the furnace-outside suspension pipe 13 are equipped with a working fluid flow adaptive adjustment loop. The loop includes a flow sensor, an electric regulating valve, and a wall temperature monitoring probe. The wall temperature monitoring probe is installed in the high-temperature region of the middle section of the suspension pipe to monitor the pipe wall temperature in real time and transmit it to the control system. When the temperature exceeds the design threshold (580℃), the control system automatically increases the opening of the electric regulating valve to increase the flow rate of the working fluid in the pipe and achieve rapid cooling. When the temperature is lower than the normal operating range (450℃), the valve opening is appropriately reduced to reduce energy consumption. The adjustment response time is ≤3s to ensure that the long-term working temperature of the suspension pipe is stable between 450℃ and 580℃. High-strength alloy steel can meet the suspension load requirements of the heating surface and the header. The internal working fluid flow can cool the suspension pipe in real time, avoiding overheating damage caused by long-term exposure to high-temperature flue gas environment, and improving the reliability of the suspension structure.

[0044] The tube bundles of the upper-stage economizer 14 and the lower-stage economizer 16 are arranged in a parallel configuration, and the spacing between the tube bundles is designed according to the flue gas flow rate and velocity (e.g., lateral spacing S1 = 100 mm, longitudinal spacing S2 = 80 mm). The surface of the economizer tube bundles is coated with an Al2O3-TiO2 composite porous coating with a thickness of 50-80 μm and a porosity of 30%-40%. This coating not only improves the high-temperature corrosion resistance of the tube wall and extends the service life of the tube bundle by more than 30%, but also enhances the radiative and convective heat transfer between the tube wall and the flue gas, thereby improving the waste heat recovery efficiency. The parallel arrangement facilitates ash removal and reduces the risk of ash accumulation and blockage; the spacing designed based on flue gas parameters reduces flue gas flow resistance while ensuring sufficient heat transfer area, thus improving waste heat recovery efficiency.

[0045] The upper-stage economizer 14 and the lower-stage economizer 16 are equipped with economizer bypasses. Each economizer bypass includes a bypass pipe and a regulating valve. The bypass pipe is connected in parallel between the inlet and outlet pipes of the upper-stage economizer 14 and the lower-stage economizer 16. The regulating valve is linked to the inlet temperature sensor of the denitrification reactor 15, forming a closed-loop temperature control. During boiler startup or low-load operation, the bypass valve can be opened to divert some feedwater, preventing overheating of the economizer tube walls due to excessively high flue gas temperature or excessively low water flow velocity. When the flue gas temperature fluctuates abnormally, the control system automatically adjusts the bypass opening based on data collected by the temperature sensor, stabilizing the inlet flue gas temperature of the denitrification reactor 15 within the optimal reaction range of 300℃-380℃, ensuring a denitrification efficiency of over 90% and an ammonia slip rate controlled below 3ppm.

[0046] The air preheater is a tubular air preheater, with its cold air inlet connected to the blower and its hot air outlet connected to the secondary air inlet of the burner 2 via a pipe. It can heat the air required for combustion from ambient temperature (e.g., 20°C) to over 300°C, enhancing fuel combustion completeness and reducing exhaust heat loss. The tubular air preheater 17 has spiral baffles inside its pipes, with a baffle height of 1 / 5 to 1 / 3 of the pipe's inner diameter. This enhances the turbulence of the cold air within the pipe, improving the heat transfer coefficient. The outer surface of the pipe adopts an alternating corrugated structure with a corrugation height of 3-5 mm and a spacing of 15-20 mm. Vibration is generated by the pressure difference during flue gas flow, achieving self-cleaning of the outer surface and reducing soot adhesion.

[0047] A denitrification reactor 15 is arranged between the upper economizer 14 and the lower economizer 16. It adopts SCR denitrification technology, injecting a reducing agent into the flue gas through an ammonia injection grid. Under the action of the catalyst, NOx is converted into nitrogen and water, and the denitrification efficiency is ≥90%.

[0048] The burner 2 adopts a staged air distribution and fuel atomization synergistic optimization structure, including a main combustion zone nozzle, a transition zone nozzle, and a burnout zone nozzle. These three nozzles are arranged in layers along the furnace height, with a spacing of 800-1200 mm. The main combustion zone nozzle is responsible for 70%-80% of fuel combustion, while the transition zone and burnout zone nozzles are responsible for 15%-20% and 5%-10% of fuel combustion, respectively. This staged combustion reduces localized high temperatures in the furnace and decreases the formation of thermal NOx. Simultaneously, the fuel nozzles of burner 2 employ a dual-fluid internal mixing atomization design, with an atomized particle size controlled at 50-80 μm and an adjustable atomization angle of 60°-90°. The boiler control system adjusts the atomization parameters in real time based on flame morphology monitoring data within the furnace, ensuring thorough mixing of fuel and air, a combustion efficiency ≥99.5%, and unburned carbon content ≤0.05%.

[0049] The workflow of this invention is as follows:

[0050] Combustion stage: Natural gas is injected into the furnace 1 through the staged nozzles of burner 2. The fuel nozzles adjust the atomization particle size (50-80μm) and angle (60°-90°) according to the instructions of the control system. It mixes and burns with the hot air (above 300°C) heated by air preheater 17 in an optimized ratio. The main combustion zone, transition zone and burnout zone are staged to reduce local high temperature, generate high temperature flue gas and flow upward along the furnace.

[0051] Furnace heat absorption stage: High-temperature flue gas passes through the water-cooled wall, transferring heat to the working fluid inside the tube. The wall temperature sensors configured in sections of the water-cooled wall collect data in real time. The control system dynamically adjusts the flow valves through the PID-Smith algorithm. Water partially vaporizes inside the spiral tube water-cooled wall 4 and becomes saturated steam after entering the vertical tube water-cooled wall 5. The wall temperature deviation of each section of the water-cooled wall is controlled within ±10℃.

[0052] Superheating and Reheating Stages: Saturated steam is sequentially heated to its rated temperature by the screen-type superheater 6 and the high-temperature superheater 7, and then sent to the high-pressure cylinder of the steam turbine. Exhaust steam from the high-pressure cylinder is heated to its rated temperature by the low-temperature reheater 11 and the high-temperature reheater 8, and then sent to the intermediate-pressure cylinder to perform work. The internal thread structure and inclined fins of the heating surfaces guide the smooth flow of flue gas, reducing ash accumulation and resistance, improving heat transfer efficiency, and controlling the ash accumulation rate to below 5%.

[0053] Waste heat recovery and denitrification stage: After passing through the heating surface, the flue gas temperature drops to 400℃ and enters the upper economizer 14 to heat the feedwater. The composite coating on the surface of the economizer tube bundle enhances heat exchange and corrosion protection. Then, the flue gas enters the denitrification reactor 15. The control system maintains the optimal reaction temperature of 300℃-380℃ through the economizer bypass closed-loop control based on the inlet temperature sensor data to complete the denitrification reaction (NOx removal rate ≥90%). The feedwater is then further heated by the lower economizer 16 to recover waste heat.

[0054] During the flue gas exhaust stage: the flue gas enters the tubular air preheater 17, where the internal baffles enhance the heating of the cold air and the external corrugated structure enables self-cleaning. After heating the cold air, the flue gas is discharged by the induced draft fan and enters the subsequent dust removal and desulfurization system. At the same time, the wall temperature probes of the suspended pipes 12 and 13 monitor the temperature in real time, and the adaptive adjustment loop responds quickly (≤3s) to maintain the temperature of the suspended pipes in the range of 450℃-580℃.

[0055] During boiler operation, the full-condition thermodynamic parameter adaptive coupling control system integrates modules such as water-cooled wall variable flow control, suspension tube adaptive adjustment, burner staged air distribution, and economizer bypass linkage, and optimizes parameters in real time based on multiple factors such as load (30%-110%), fuel composition, and ambient temperature.

[0056] The supercritical gas-fired boiler and thermal optimization control method based on tower layout of the present invention effectively solves the multiple technical shortcomings of traditional boiler layout and existing tower boilers through the deep integration of structural innovation and control optimization. It has higher thermal efficiency, better environmental performance, longer service life and more reliable operation stability, and is suitable for the core needs of the current energy industry for efficient, clean and flexible gas-fired power generation equipment.

[0057] The PID-Smith predictive control algorithm is a composite control algorithm optimized for systems with large time lag (control systems where the output signal takes a long time to respond after the input signal changes). Its core is to combine the deviation adjustment capability of traditional PID (proportional-integral-derivative) control with the lag compensation function of the Smith predictor. By predicting the lag response of process variables through a mathematical model, the control output is corrected in advance, thereby overcoming the adverse effects of large time lag on control accuracy and stability, and achieving precise and rapid control of the controlled object.

[0058] PID-Smith predictive control workflow:

[0059] The system sets a target value (e.g., a target wall temperature of 500℃ for water-cooled walls) and simultaneously collects the current actual wall temperature through sensors.

[0060] The Smith predictor, based on the heat conduction model of the water-cooled wall and the flow characteristics of the working fluid, predicts "the wall temperature will reach after a lag time following the current control action (such as flow regulation);

[0061] The controller simultaneously receives the "actual wall temperature" and the "estimated wall temperature" and calculates the combined deviation between the two and the target value;

[0062] The PID module outputs proportional, integral, and derivative control signals based on the overall deviation to control the opening of the flow valve;

[0063] Because the predictor compensates for the lag in advance, the control action can "respond in advance" to changes in heat load, avoiding the "lag adjustment" of traditional PID, and ultimately achieving rapid stabilization of the wall temperature near the set value (e.g., within ±10℃ deviation).

[0064] In previous supercritical gas-fired boiler designs, this algorithm was mainly used for segmented variable flow control of water-cooled walls. By predicting the lag effect of heat load changes on wall temperature, the working fluid flow rate was adjusted in advance to ensure that the wall temperature deviation of each water-cooled wall segment was controlled within ±10℃, thus meeting the needs of rapid load changes in the boiler.

[0065] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A supercritical gas-fired boiler based on a tower arrangement, characterized in that, Includes furnace (1), burner (2), water-cooled wall, furnace heating surface, furnace header, economizer, and air preheater; The furnace (1) is arranged in a single-furnace tower type and is surrounded by water-cooled walls; The burner (2) has a graded air distribution structure, including the main combustion zone nozzle, the transition zone nozzle and the burnout zone nozzle arranged in layers along the height of the furnace; The water-cooled wall includes an ash hopper water-cooled wall (3), a spiral tube coil water-cooled wall (4), and a vertical tube coil water-cooled wall (5); the ash hopper water-cooled wall (3) is located at the bottom of the furnace (1), the spiral tube coil water-cooled wall (4) is located in the lower part of the furnace (1), and the vertical tube coil water-cooled wall (5) is located in the upper part of the furnace; the spiral tube coil water-cooled wall (4) and the vertical tube coil water-cooled wall (5) adopt a segmented variable flow control structure, each segment is equipped with an independent flow regulating valve and a wall temperature monitoring sensor, and the sensor is connected to the boiler control system signal; The furnace heating surface includes, in sequence along the flue gas flow direction, a screen-type superheater (6), a high-temperature superheater (7), a high-temperature reheater (8), an evaporator (9), a low-temperature reheater (11), and a low-temperature superheater (10); the fins of the furnace heating surface are inclined flow guiding structures. The furnace heating surface is suspended by the furnace suspension pipe (12), and the furnace external header is suspended by the furnace external suspension pipe (13); The economizer includes an upper economizer (14) and a lower economizer (16), which are arranged in the flue gas duct with the tail outlet pointing downwards along the flue gas direction; The air preheater is located inside the steel frame at the rear of the furnace.

2. The supercritical gas-fired boiler based on a tower arrangement according to claim 1, characterized in that, The spiral tube coil water-cooled wall (4) and the ash hopper water-cooled wall (3) are seamlessly connected, and the pipe diameter at the connection point is the same.

3. The supercritical gas-fired boiler based on a tower arrangement according to claim 1, characterized in that, The heat-receiving surfaces of the screen-type superheater (6), high-temperature superheater (7), high-temperature reheater (8), evaporator (9), low-temperature reheater (11), and low-temperature superheater (10) are all made of alloy steel with good thermal conductivity and high-temperature corrosion resistance.

4. The supercritical gas-fired boiler based on a tower arrangement according to claim 1, characterized in that, The in-furnace suspension pipe (12) and the out-of-furnace suspension pipe (13) are made of high-strength alloy steel; there is working fluid flowing inside the in-furnace suspension pipe (12) and the out-of-furnace suspension pipe (13); the in-furnace suspension pipe (12) and the out-of-furnace suspension pipe (13) are equipped with a working fluid flow adaptive adjustment loop, the loop includes a flow sensor, an electric regulating valve and a wall temperature monitoring probe, and the wall temperature monitoring probe is connected to the boiler control system signal.

5. The supercritical gas-fired boiler based on a tower arrangement according to claim 1, characterized in that, The tube bundles of the upper economizer (14) and the lower economizer (16) are arranged in a parallel manner, and the spacing between the tube bundles is designed according to the flue gas flow rate and velocity.

6. The supercritical gas-fired boiler based on a tower arrangement according to claim 1, characterized in that, The upper economizer (14) and the lower economizer (16) are equipped with economizer bypasses; the regulating valve of the economizer bypass is linked to the inlet temperature sensor of the denitrification reactor (15).

7. The supercritical gas-fired boiler based on a tower arrangement according to claim 1, characterized in that, The air preheater is a tubular air preheater; the tubular air preheater has spiral baffles inside the pipe and the outer surface of the pipe has a corrugated structure with alternating concave and convex shapes.

8. The supercritical gas-fired boiler based on a tower arrangement according to any one of claims 1-7, characterized in that, A denitrification reactor (15) is arranged between the upper economizer (14) and the lower economizer (16).

9. A thermal optimization control method for a supercritical gas-fired boiler based on any one of claims 1-9, characterized in that, Includes the following steps: (1) The wall temperature and heat load signals of each section of the water-cooled wall are collected by the wall temperature monitoring sensors configured in sections of the water-cooled wall. The boiler control system adopts the PID-Smith prediction control algorithm to dynamically adjust the opening of the flow regulating valve of each section of the water-cooled wall and control the flow rate of the working fluid in the pipe. (2) Using the temperature data collected by the suspended pipe wall temperature monitoring probe, the opening of the electric regulating valve is adjusted in real time through the working fluid flow adaptive adjustment loop to control the flow rate of the working fluid in the suspended pipe; (3) Based on the monitoring data of the inlet temperature sensor of the denitrification reactor (15), the opening of the bypass valve is adjusted through the temperature closed-loop control logic of the economizer bypass to maintain the optimal temperature range of the denitrification reaction. (4) Based on the monitoring data of flame shape and combustion efficiency in the furnace, adjust the air distribution ratio of each stage nozzle of the burner (2) and the atomization parameters of the fuel nozzle to optimize the combustion conditions.

10. The thermal optimization control method according to claim 9, characterized in that, In step (4), the atomization particle size of the fuel nozzle is controlled at 50-80μm, and the atomization angle is adjusted within the range of 60°-90°.

Images