Thermodynamic system of boiler and control method of thermodynamic system

Abstract

The invention provides a thermodynamic system of a boiler and a control method thereof.The thermodynamic system comprises the boiler, a steam pocket, a flue gas heat exchange device, an evaporator and a heat storage buffer assembly.The thermodynamic system conveys a medium into a pressure-bearing tank body to adjust fluctuation of waste heat flue gas, so that the temperature of flue gas input into a flue gas pipeline by an isolation heat exchanger is kept stable; the severe change of the flue gas temperature is effectively stabilized, and the problem of frequent fluctuation of the heat load of the evaporator caused by fluctuation of waste heat flue gas is obviously reduced; the stable flue gas temperature ensures that a medium in the first flow channel is uniformly heated, so that the risk of sudden reduction of evaporation capacity or overload operation is avoided, and the phenomena of drum water level oscillation and out-of-control steam parameters are fundamentally inhibited; according to the design, the operation stability of a power generation system is enhanced while the heat efficiency of the boiler is improved, and waste heat flue gas can be efficiently and reliably converted into boiler evaporation capacity gain.

Description

Technical Field

[0001] This application relates to the field of boiler technology, specifically to a boiler thermal system and its control method. Background Technology

[0002] Boilers generally use a natural circulation system. Deoxygenated water is pressurized by the boiler feed pump and sent into the steam drum. Then, it is distributed to the evaporator through the downcomer at the bottom of the steam drum. The steam-water mixture generated after heating rises into the steam drum through the riser and is separated by the steam-water separator in the steam drum. The water falls into the lower part of the steam drum and is redistributed to the evaporator through the downcomer for circulation heating. The separated steam is introduced into the superheater through the steam pipe at the top of the steam drum for further heating to produce qualified steam. This part of the steam is used as the main steam for power generation by the steam turbine generator.

[0003] In existing technologies, waste heat flue gas from annealing kilns and other sources is used to preheat boiler feedwater to increase evaporation. However, in actual operation, the temperature and flow rate of the waste heat flue gas flue gas flue gas flue significantly. This fluctuation directly leads to unstable outlet water temperature of the heat exchanger, which in turn causes frequent changes in the heat load of the evaporator: when the flue gas temperature drops sharply, the heat absorbed by the evaporator decreases, causing a sudden drop in evaporation; when the flue gas temperature rises sharply, it may cause the evaporator to operate under overload. At the same time, the drastic fluctuations in water temperature not only reduce the boiler thermal efficiency, but may also cause oscillations in the steam drum water level or loss of control of steam parameters, seriously affecting the stability of power generation. Summary of the Invention

[0004] The purpose of this application is to address the above-mentioned problems by providing a boiler thermal system and its control method.

[0005] In a first aspect, this application provides a boiler thermal system, comprising: boiler; The steam drum has its input end connected to the boiler via a first main line, and its output end connected to a superheater; the bottom of the steam drum is provided with a downcomer, and the top is provided with an upcomer. A flue gas heat exchange device includes a first flow channel and a flue gas flow channel that are isolated from each other; the first flow channel has a first input end and a first output end, the first input end being connected to the downcomer via a first pipe; the first output end being connected to an evaporator via a second pipe, and the output end of the evaporator being connected to the riser; the flue gas heat exchange device is configured to use the waste heat flue gas from the flue gas flow channel to heat the medium flowing through the first flow channel; A heat storage buffer assembly includes a pressure tank and an isolated heat exchanger disposed inside the pressure tank; the input end of the isolated heat exchanger is used to input waste heat flue gas, and the output end of the isolated heat exchanger is connected to the input end of the flue gas flow channel; a temperature sensor is provided at the output end of the isolated heat exchanger for detecting the temperature of the output flue gas. The pressure tank is provided with a first inlet at the top and a first outlet at the bottom; the first outlet is connected to the first main line via a first branch line, and a flow regulating device is provided on the first branch line to control the flow rate of the medium input into the pressure tank; the first outlet is connected to the first pipeline; the heat storage buffer assembly is configured to: adjust the fluctuation of waste heat flue gas through the medium in the pressure tank to keep the flue gas temperature output to the flue gas flow channel stable.

[0006] According to the technical solution provided in this application, the flue gas heat exchange device further has a second flow channel, the second flow channel has a second input end and a second output end, the second input end is connected to the output end of the evaporator through a third pipeline, and the second output end is connected to the riser pipe through a fourth pipeline; the flue gas heat exchange device is also configured to use the waste heat flue gas in the flue gas flow channel to heat the medium flowing through the second flow channel.

[0007] According to the technical solution provided in this application, an economizer is connected in parallel on the second pipeline, a first valve is provided between the input end of the economizer and the second pipeline, a second valve is provided between the output end of the economizer and the second pipeline, and a third valve is provided on the second pipeline between the first valve and the second valve.

[0008] According to the technical solution provided in this application, a fourth valve is provided on the first pipeline near the first input end, and a fifth valve is provided on the second pipeline near the first output end.

[0009] According to the technical solution provided in this application, a first bypass is connected between the first pipeline and the second pipeline, and the first bypass is located between the input end of the fourth valve and the output end of the fifth valve, and a sixth valve is provided on the first bypass.

[0010] According to the technical solution provided in this application, a seventh valve is provided on the second pipeline near the input end of the evaporator, and an eighth valve is provided on the third pipeline near the output end of the evaporator.

[0011] According to the technical solution provided in this application, a second bypass is connected between the second pipeline and the third pipeline, and the second bypass is located between the input end of the seventh valve and the output end of the eighth valve, and a ninth valve is provided on the second bypass.

[0012] According to the technical solution provided in this application, a tenth valve is provided on the third pipeline near the second input end, and an eleventh valve is provided on the fourth pipeline near the second output end.

[0013] According to the technical solution provided in this application, a third bypass is connected between the third pipeline and the fourth pipeline, and the third bypass is located between the input end of the tenth valve and the output end of the eleventh valve, and a twelfth valve is provided on the third bypass.

[0014] Secondly, this application provides a control method for a boiler thermal system, employing the thermal system of the boiler described in any one of the first aspects, comprising the following steps: The initial opening value of the preset flow regulation device is used to allow part of the medium to enter the pressure tank through the first branch; The temperature of the flue gas output from the isolated heat exchanger is obtained in real time through the temperature sensor. Calculate the deviation between the flue gas temperature and the set temperature, and determine the opening adjustment value of the flow regulating device based on the deviation value; The opening degree of the flow regulating device is dynamically adjusted according to the opening degree adjustment value to control the flow rate of the medium entering the pressure tank through the first branch. By adjusting the pressure tank to absorb the fluctuations in the waste heat flue gas in the isolation heat exchanger, the temperature of the flue gas output from the isolation heat exchanger to the flue gas flow channel is kept stable. Stable flue gas is introduced into the flue gas flow channel to heat the medium flowing through the first flow channel and increase its temperature. The heated medium is heated by the evaporator to generate a steam-water mixture, which is then separated into steam by the steam drum and fed into the superheater.

[0015] Compared with the prior art, the beneficial effects of this application are as follows: This application provides a boiler thermal system and its control method. The thermal system includes a boiler, a steam drum, a flue gas heat exchange device, an evaporator, and a heat storage buffer assembly. This application adjusts the fluctuations of waste heat flue gas by supplying a medium into the pressure tank, thereby stabilizing the flue gas temperature input to the flue gas pipeline from the isolation heat exchanger. This effectively mitigates drastic changes in flue gas temperature and significantly reduces the problem of frequent fluctuations in evaporator heat load caused by fluctuations in waste heat flue gas. The stabilized flue gas temperature ensures uniform heating of the medium in the first flow channel, not only avoiding the risk of sudden drops in evaporation or overload operation, but also fundamentally suppressing the oscillation of steam drum water level and the runaway of steam parameters. This design improves the boiler's thermal efficiency while enhancing the operational stability of the power generation system, enabling waste heat flue gas to be efficiently and reliably converted into boiler evaporation gain.

[0016] It should be understood that the descriptions of technical features, technical solutions, beneficial effects, or similar language in this application do not imply that all features and advantages can be achieved in any single embodiment. Rather, it is understood that the description of a feature or beneficial effect means that a specific technical feature, technical solution, or beneficial effect is included in at least one embodiment. Therefore, the descriptions of technical features, technical solutions, or beneficial effects in this specification do not necessarily refer to the same embodiment. Furthermore, the technical features, technical solutions, and beneficial effects described in this embodiment can be combined in any suitable manner. Those skilled in the art will understand that embodiments can be implemented without one or more specific technical features, technical solutions, or beneficial effects of a particular embodiment. In other embodiments, additional technical features and beneficial effects may be identified in specific embodiments that do not embody all embodiments. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in this embodiment, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of a boiler thermal system provided in Embodiment 1 of this application; Figure 2 This is a flowchart of a control method for a boiler thermal system provided in Embodiment 2 of this application.

[0019] In the diagram: 1. Boiler; 2. Steam drum; 3. First flow channel; 4. Flue gas flow channel; 5. Second flow channel; 6. Superheater; 7. Evaporator; 8. Economizer; 9. Isolation heat exchanger; 10. Pressure tank; 11. Exhaust fan; 12. Flow regulating device; 13. First pipeline; 14. Second pipeline; 15. Third pipeline; 16. Fourth pipeline; 17. First valve; 18. Second valve; 19. Third valve; 20. Fourth valve; 21. Fifth valve; 22. Sixth valve; 23. Seventh valve; 24. Eighth valve; 25. Ninth valve; 26. Tenth valve; 27. Eleventh valve; 28. Twelfth valve. Detailed Implementation

[0020] To enable those skilled in the art to better understand the technical solutions of this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. The descriptions in this section are merely illustrative and explanatory, and should not be construed as limiting the scope of protection of this application. Specifically, the described embodiments are only some embodiments of this application, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort should fall within the scope of protection of this application.

[0021] It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such process, method, product, or apparatus.

[0022] To make the technical solution of this application clearer and easier to understand, the following describes a boiler thermal system and its control method provided by the embodiments of this application.

[0023] Example 1 like Figure 1 As shown, this embodiment provides a boiler thermal system, including: Boiler 1; Steam drum 2 has its input end connected to boiler 1 via a first main line, and its output end connected to superheater 6; a downcomer is provided at the bottom of steam drum 2 and an upcomer is provided at the top. The flue gas heat exchange device includes a first flow channel 3 and a flue gas flow channel 4 that are isolated from each other; the first flow channel 3 has a first input end and a first output end, the first input end is connected to a downcomer through a first pipe 13; the first output end is connected to an evaporator 7 through a second pipe 14, and the output end of the evaporator 7 is connected to a riser; the flue gas heat exchange device is configured to use the waste heat flue gas in the flue gas flow channel 4 to heat the medium flowing through the first flow channel 3; The heat storage buffer assembly includes a pressure tank 10 and an isolation heat exchanger 9 disposed inside the pressure tank 10. The input end of the isolation heat exchanger 9 is used to input waste heat flue gas, and the output end of the isolation heat exchanger 9 is connected to the input end of the flue gas passage 4. A temperature sensor is provided at the output end of the isolation heat exchanger 9 to detect the temperature of the output flue gas. The pressure tank 10 has a first inlet at the top and a first outlet at the bottom. The first outlet is connected to the first main line via a first branch line. A flow regulating device 12 is installed on the first branch line to control the flow rate of the medium input into the pressure tank 10. The first outlet is connected to the first pipeline 13. The heat storage buffer assembly is configured to adjust the fluctuation of the waste heat flue gas through the medium in the pressure tank 10, so that the temperature of the flue gas output to the flue gas flow channel 4 remains stable.

[0024] Specifically, this system includes a boiler 1, a steam drum 2, and a first main line connecting the steam drum 2 and the boiler 1. The downcomer at the bottom of the steam drum 2 and the riser at the top form a circulation base. The flue gas heat exchange device adopts a first flow channel 3 and a flue gas flow channel 4 that are isolated from each other. The first flow channel 3 has a first input end and a first output end. The first input end is connected to the downcomer through a first pipe 13, and the first output end is connected to the evaporator 7 through a second pipe 14. The output end of the evaporator 7 is connected back to the riser to form a closed loop, so that the waste heat flue gas in the flue gas flow channel 4 can continuously heat the circulating medium in the first flow channel 3. Specifically, in this embodiment, the isolation heat exchanger 9 is in the form of a coil heat exchanger. When the medium flowing out from the first branch is injected into the pressure tank through the first inlet, it will come into contact with the surface of the coil heat exchanger and then exchange heat with the flue gas flowing inside the coil heat exchanger; In this embodiment, an induced draft fan 11 is provided at the output end of the flue gas duct 4. The function of the induced draft fan 11 is to provide power for the flue gas in the flue gas duct 4, guide the flue gas to be discharged smoothly, ensure the stable flow of waste heat flue gas in the flue gas duct 4, and help the smooth operation of the entire waste heat utilization and thermal cycle system. Specifically, during system operation, the initial opening value of the preset flow regulating device (in this embodiment, the initial opening value is 20%) is used to allow a portion of the medium to enter the pressure tank through the first branch and exchange heat with the flue gas inside the isolation heat exchanger 9. The temperature sensor monitors the flue gas temperature output from the isolation heat exchanger 9 in real time, calculates the difference between it and the set temperature as the deviation value, and determines the opening adjustment value of the flow regulating device based on the deviation value to accurately control the flow rate of the medium diverted from the boiler 1 to the pressure tank 10. When the deviation value is greater than 0 (i.e., the actual flue gas temperature is higher than the set temperature), the opening adjustment value is increased. In this embodiment, for every 1°C increase, the opening value increases by 0.8%. When the deviation value is less than 0 (i.e., the actual flue gas temperature is lower than the set temperature), the opening adjustment value is decreased. In this embodiment, for every 1°C decrease, the opening value decreases by 0.8%. In this embodiment, the flow regulating device is a proportional valve. As the medium is injected into the pressure tank 10, the medium and the flue gas inside the isolation heat exchanger 9 continuously exchange heat, thereby keeping the flue gas temperature output to the flue gas flow channel 4 stable. The flue gas, after being stabilized and kept at a constant temperature, enters the flue gas flow channel 4 and undergoes efficient heat exchange with the medium in the first flow channel 3. The heated medium is then transported to the evaporator 7 through the first pipeline 13, where it absorbs heat to generate a uniform steam-water mixture. This mixture is then returned to the steam drum 2 via the riser pipe to complete the steam-water separation. The separated saturated steam is then introduced into the superheater 6 for further heating to form superheated steam with stable parameters. Working principle: This application adjusts the fluctuations of waste heat flue gas by supplying a medium into the pressure tank 10, thereby stabilizing the flue gas temperature input to the flue gas pipeline from the isolation heat exchanger. This effectively suppresses drastic changes in flue gas temperature and significantly reduces the problem of frequent fluctuations in the heat load of the evaporator 7 caused by fluctuations in waste heat flue gas. The stabilized flue gas temperature ensures uniform heating of the medium in the first flow channel 3, which not only avoids the risk of sudden drops in evaporation or overload operation, but also fundamentally suppresses the phenomenon of water level oscillation in the steam drum 2 and uncontrolled steam parameters. This design improves the thermal efficiency of the boiler 1 while enhancing the operational stability of the power generation system, enabling waste heat flue gas to be efficiently and reliably converted into evaporation gain in the boiler 1.

[0025] In some embodiments, the flue gas heat exchanger also has a second flow channel 5, which has a second input end and a second output end. The second input end is connected to the output end of the evaporator 7 via a third pipe 15, and the second output end is connected to the riser via a fourth pipe 16. The flue gas heat exchanger is also configured to use the waste heat flue gas from the flue gas flow channel 4 to heat the medium flowing through the second flow channel 5.

[0026] Specifically, the flue gas heat exchange device is also equipped with a second flow channel 5. The second input end of the second flow channel 5 is connected to the output end of the evaporator 7 through the third pipe 15, and the second output end is connected back to the riser pipe through the fourth pipe 16. The steam-water mixture output by the steamer flows into the second flow channel 5, and the waste heat flue gas in the flue gas flow channel 4 is used to reheat the steam-water mixture, thereby increasing its temperature and vaporization efficiency, and thus significantly improving the evaporation capacity of the boiler 1.

[0027] In some embodiments, an economizer 8 is connected in parallel to the second pipeline 14, a first valve 17 is provided between the input end of the economizer 8 and the second pipeline 14, a second valve 18 is provided between the output end of the economizer 8 and the second pipeline 14, and a third valve 19 is provided on the second pipeline 14 between the first valve 17 and the second valve 18.

[0028] Specifically, an economizer 8 is installed between the heat exchanger and the evaporator 7. It can recover waste heat from the flue gas to preheat the medium entering the evaporator 7, allowing the medium to absorb more heat and improve the energy quality input to the evaporator 7. It can also stabilize the temperature of the medium entering the evaporator 7, avoiding problems such as disordered heat load and unstable evaporation caused by large temperature fluctuations, and ensuring stable operation of the evaporator 7. Furthermore, it can reduce heat loss from the flue gas through waste heat recovery, improve the overall thermal efficiency of the boiler 1, help improve the evaporation rate and steam quality of the boiler 1, and optimize the thermal performance of the boiler 1. Specifically, to further optimize heat utilization and enhance system adjustment flexibility, an economizer 8 is connected in parallel to the second pipeline 14. A first valve 17 is installed between the input end of the economizer 8 and the second pipeline 14 to control the on / off state of the input end of the economizer 8. A second valve 18 is installed between the output end of the economizer 8 and the second pipeline 14 to control the on / off state of the output end of the economizer 8. At the same time, a third valve 19 is installed on the second pipeline 14 between the first valve 17 and the second valve 18. When the system activates the economizer 8 as needed, the third valve 19 can be closed and the third valve 19 opened. The first valve 17 and the allowance valve allow the medium flowing through the second pipeline 14 to first enter the economizer 8, improve the energy state of the medium, and then flow back to the second pipeline 14 and into the evaporator 7, thereby enhancing heat recovery. If the economizer 8 needs maintenance or does not need to be used, the first valve 17 and the second valve 18 are closed and the third valve 19 is opened, allowing the medium to flow directly along the second pipeline 14, ensuring that the basic process of the system is not affected. This adapts to different operating conditions and helps the boiler 1 system achieve a better balance between waste heat utilization and flexible equipment control, thereby improving overall energy efficiency and operational stability.

[0029] In some embodiments, a fourth valve 20 is provided on the first pipeline 13 near the first input end, and a fifth valve 21 is provided on the second pipeline 14 near the first output end.

[0030] Specifically, a fourth valve 20 is installed on the first pipeline 13 near the first input end, and a fifth valve 21 is installed on the second pipeline 14 near the first output end. When the system is running normally, the fourth valve 20 and the fifth valve 21 are opened to ensure the smooth flow of the medium in the first flow channel 3.

[0031] In some embodiments, a first bypass is connected between the first pipeline 13 and the second pipeline 14, and the first bypass is located between the input end of the fourth valve 20 and the output end of the fifth valve 21, and a sixth valve 22 is provided on the first bypass.

[0032] Specifically, when the boiler 1 system is under specific operating conditions, the medium can be diverted or supplemented across pipelines by operating the sixth valve 22. If it is necessary to reduce the flow rate of the medium flowing through the first flow channel 3, the sixth valve 22 can be opened to allow some of the medium to flow directly from the first pipeline 13 through the first bypass into the second pipeline 14, reducing the total amount of medium entering the flue gas heat exchanger. In conjunction with the opening adjustment of the fourth valve 20 and the fifth valve 21, the load of the flue gas heat exchanger can be flexibly controlled. When the flue gas heat exchanger needs to be temporarily isolated due to a fault, after closing the fourth valve 20 and the fifth valve 21, the sixth valve 22 can be opened to allow the medium to maintain the basic connection between the first pipeline 13 and the second pipeline 14 through the first bypass, ensuring that the main steam-water circulation process is not interrupted, buying time for system fault diagnosis and equipment repair, and avoiding the shutdown of the entire boiler 1 thermal system due to the maintenance of a single piece of equipment. This improves the continuity and reliability of system operation and helps boiler 1 to have stronger adjustment resilience and risk resistance when dealing with complex operating conditions in waste heat utilization scenarios.

[0033] In some embodiments, a seventh valve 23 is provided on the second pipeline 14 near the input end of the evaporator 7, and an eighth valve 24 is provided on the third pipeline 15 near the output end of the evaporator 7.

[0034] Specifically, a seventh valve 23 is installed on the second pipeline 14 near the input end of the evaporator 7, and an eighth valve 24 is installed on the third pipeline 15 near the output end of the evaporator 7. When the system is running normally, the seventh valve 23 and the eighth valve 24 are opened to ensure the smooth flow of the medium in the evaporator 7.

[0035] In some embodiments, a second bypass is connected between the second pipeline 14 and the third pipeline 15, and the second bypass is located between the input end of the seventh valve 23 and the output end of the eighth valve 24, and a ninth valve 25 is provided on the second bypass.

[0036] Specifically, when evaporator 7 needs to be quickly isolated for maintenance due to a malfunction, after closing the seventh valve 23 to cut off the medium input and closing the eighth valve 24 to block the medium output, the ninth valve 25 is opened to allow the second pipeline 14 and the third pipeline 15 to maintain basic connectivity through the second bypass, ensuring that the medium circulation in the second flow channel 5 is uninterrupted. This buys time for troubleshooting and maintenance of evaporator 7, and at the same time prevents the complete shutdown of the boiler 1 waste heat utilization and steam-water circulation system due to the abnormality of a single piece of equipment. This improves the system's resilience in dealing with sudden equipment situations and helps boiler 1 maintain relatively stable heat output and waste heat recovery efficiency even under fluctuating waste heat flue gas conditions, even with partial equipment maintenance.

[0037] In some embodiments, a tenth valve 26 is provided on the third pipeline 15 near the second input end, and an eleventh valve 27 is provided on the fourth pipeline 16 near the second output end.

[0038] Specifically, a tenth valve 26 is installed on the third pipeline 15 near the second input end, and an eleventh valve 27 is installed on the fourth pipeline 16 near the second output end. During normal system operation, the tenth valve 26 and the eleventh valve 27 are opened to ensure that the steam-water mixture flows smoothly into the second flow channel 5. It is then reheated by the waste heat flue gas in the flue gas flow channel 4, and then efficiently returned to the riser pipe through the fourth pipeline 16, continuously improving the temperature and vaporization efficiency of the steam-water mixture and helping the boiler 1 to steadily increase its evaporation capacity.

[0039] In some embodiments, a third bypass is connected between the third pipeline 15 and the fourth pipeline 16, and the third bypass is located between the input end of the tenth valve 26 and the output end of the eleventh valve 27, and a twelfth valve 28 is provided on the third bypass.

[0040] Specifically, when the flue gas heat exchanger needs to be temporarily isolated for maintenance due to a malfunction, after closing the tenth valve 26 to cut off the medium input and closing the eleventh valve 27 to block the medium output, the twelfth valve 28 is opened to allow the third pipeline 15 and the fourth pipeline 16 to maintain basic connectivity through the third bypass. This ensures that the circulation of the steam-water mixture from the evaporator 7 to the riser is uninterrupted, buying time for troubleshooting and maintenance of the flue gas heat exchanger. At the same time, it prevents the waste heat utilization and steam-water circulation system of boiler 1 from being completely disrupted due to the abnormality of a single piece of equipment. This improves the system's resilience in the face of sudden equipment conditions and helps boiler 1 maintain a relatively stable heat output and secondary heating efficiency even under fluctuating waste heat flue gas conditions, even with localized flow channel maintenance. This optimizes the overall energy efficiency and operational reliability of boiler 1.

[0041] Example 2 like Figure 2 As shown, this embodiment provides a control method for a boiler thermal system, using a boiler thermal system provided in Embodiment 1, including the following steps: S1: The initial opening value of the preset flow regulating device is used to allow part of the medium to enter the pressure tank through the first branch. Specifically, before the system starts running, the initial opening value of the flow regulating device 12 is preset (in this embodiment, the initial opening value is 20%). Based on this opening, the boiler feedwater will be proportionally diverted to the first branch, and part of the medium will be transported to the pressure tank 10 through the first branch to prepare for the subsequent absorption of waste heat flue gas fluctuations and stabilization of flue gas temperature, thereby realizing the initial filling and flow pre-allocation of the medium in the tank.

[0042] S2: The flue gas temperature output from the isolated heat exchanger is obtained in real time through a temperature sensor; Specifically, by using a temperature sensor installed at the output end of the isolation heat exchanger 9, the temperature of the flue gas discharged from the isolation heat exchanger 9 is continuously and in real time acquired. This temperature is a key parameter reflecting the state of the waste heat flue gas after preliminary heat exchange, providing a basis for subsequent judgment of flue gas fluctuations and adjustment of flow rate, and ensuring that the system can detect changes in flue gas temperature in a timely manner.

[0043] S3: Calculate the deviation between the flue gas temperature and the set temperature, and determine the opening adjustment value of the flow regulating device based on the deviation value; Specifically, the actual flue gas temperature monitored by the temperature sensor is compared with the system set temperature, and the difference between the two is calculated as the deviation value. Based on the deviation value, the opening adjustment value of the flow adjustment device is determined to precisely control the flow rate of the medium diverted from boiler 1 to pressure tank 10. When the deviation value is greater than 0 (i.e., the actual flue gas temperature is higher than the set temperature), the opening adjustment value is increased. In this embodiment, the opening value increases by 0.8% for every 1°C increase. When the deviation value is less than 0 (i.e., the actual flue gas temperature is lower than the set temperature), the opening adjustment value is decreased. In this embodiment, the opening value decreases by 0.8% for every 1°C decrease. S4: Dynamically adjust the opening of the flow regulating device according to the opening adjustment value to control the flow rate of the medium entering the pressure tank through the first branch; Specifically, the opening of the flow regulating device 12 is dynamically adjusted according to the opening adjustment value. If the deviation value is greater than 0 (the actual flue gas temperature is higher than the set temperature), the opening is increased to allow more medium to flow into the pressure tank 10 through the first branch, thereby enhancing the heat exchange between the medium and the flue gas in the isolation heat exchanger 9 and reducing the flue gas temperature. If the deviation value is less than 0 (the actual flue gas temperature is lower than the set temperature), the opening is decreased to reduce the amount of medium flowing into the tank, weakening the heat exchange effect and increasing the flue gas temperature. Through continuous dynamic adjustment, the flow rate of the medium entering the pressure tank 10 through the first branch is precisely controlled, thereby achieving preliminary intervention in flue gas temperature fluctuations.

[0044] S5: Adjust the fluctuation of waste heat flue gas in the isolation heat exchanger by the medium in the pressure tank, so that the flue gas temperature output from the isolation heat exchanger to the flue gas flow channel remains stable. Specifically, the medium flowing into the pressure tank 10 exchanges heat with the waste heat flue gas in the isolation heat exchanger 9. Since the medium has a certain heat capacity, it can absorb heat from the flue gas (when the flue gas temperature is too high) or release heat to the flue gas (when the flue gas temperature is too low). With the help of this heat exchange, the temperature and flow fluctuations of the waste heat flue gas are buffered. Ultimately, the flue gas temperature output from the isolation heat exchanger 9 to the flue gas flow channel 4 is maintained in a stable range, laying the foundation for subsequent efficient heat exchange.

[0045] S6: Input flue gas with a stable temperature into the flue gas flow channel to heat the medium flowing through the first flow channel and increase its temperature; Specifically, the flue gas at a stable temperature after the fluctuations are smoothed is transported to the flue gas flow channel 4. Inside the flue gas flow channel 4, the flue gas exchanges heat with the medium in the first flow channel 3. The heat of the flue gas is transferred to the medium, significantly increasing the temperature of the medium and providing a high-temperature and stable input medium for the evaporator, thus ensuring the heat exchange efficiency of the evaporator.

[0046] S7: The heated medium is heated by the evaporator to generate a steam-water mixture, which is then separated by the steam drum to form steam and input into the superheater.

[0047] Specifically, the heated medium flows into the evaporator 7, absorbs heat in the evaporator 7, and generates a steam-water mixture. The steam-water mixture enters the steam drum 2 through the riser pipe, and the steam-water is separated by the built-in steam-water separator in the steam drum 2. The separated steam is introduced into the superheater 6, which is further heated to form superheated steam with stable parameters (temperature and pressure meet the standards). It can be used for power generation, industrial steam, and other scenarios, completing the entire thermal cycle and energy conversion process.

[0048] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. The above descriptions are only preferred embodiments of this application. It should be noted that due to the limitations of written expression, while there are objectively infinite specific structures, those skilled in the art can make several improvements, modifications, or changes without departing from the principles of this application, and can also combine the above technical features in an appropriate manner. These improvements, modifications, changes, or combinations, or the direct application of the inventive concept and technical solution to other situations without modification, should all be considered within the scope of protection of this application.

Claims

1. A boiler thermal system, characterized in that, include: Boiler (1); The steam drum (2) has its input end connected to the boiler (1) via a first main road and its output end connected to a superheater (6); the bottom of the steam drum (2) is provided with a downcomer and the top is provided with an upcomer. The flue gas heat exchange device includes a first flow channel (3) and a flue gas flow channel (4) that are isolated from each other; the first flow channel (3) has a first input end and a first output end, the first input end is connected to the downcomer through a first pipe (13); the first output end is connected to the evaporator (7) through a second pipe (14), and the output end of the evaporator (7) is connected to the riser; the flue gas heat exchange device is configured to heat the medium flowing through the first flow channel (3) using the waste heat flue gas of the flue gas flow channel (4); A heat storage buffer assembly includes a pressure tank (10) and an isolation heat exchanger (9) disposed inside the pressure tank (10); the input end of the isolation heat exchanger (9) is used to input waste heat flue gas, and the output end of the isolation heat exchanger (9) is connected to the input end of the flue gas passage (4); a temperature sensor is provided at the output end of the isolation heat exchanger (9), and the temperature sensor is used to detect the temperature of the output flue gas; The pressure tank (10) has a first inlet at the top and a first outlet at the bottom; the first outlet is connected to the first main road via a first branch road, and a flow regulating device (12) is provided on the first branch road. The flow regulating device (12) is used to control the flow rate of the medium input into the pressure tank (10); the first outlet is connected to the first pipeline (13); the heat storage buffer assembly is configured to: adjust the fluctuation of the waste heat flue gas through the medium in the pressure tank (10) so that the flue gas temperature output to the flue gas flow channel (4) remains stable.

2. The thermal system of a boiler according to claim 1, characterized in that, The flue gas heat exchange device also has a second flow channel (5), which has a second input end and a second output end. The second input end is connected to the output end of the evaporator (7) through a third pipe (15), and the second output end is connected to the riser pipe through a fourth pipe (16). The flue gas heat exchange device is also configured to use the waste heat flue gas from the flue gas flow channel (4) to heat the medium flowing through the second flow channel (5).

3. The thermal system of a boiler according to claim 2, characterized in that, An economizer (8) is connected in parallel to the second pipeline (14). A first valve (17) is provided between the input end of the economizer (8) and the second pipeline (14). A second valve (18) is provided between the output end of the economizer (8) and the second pipeline (14). A third valve (19) is provided on the second pipeline (14) and located between the first valve (17) and the second valve (18).

4. The thermal system of a boiler according to claim 1, characterized in that, A fourth valve (20) is provided on the first pipeline (13) and near the first input end, and a fifth valve (21) is provided on the second pipeline (14) and near the first output end.

5. The thermal system of a boiler according to claim 4, characterized in that, A first bypass is connected between the first pipeline (13) and the second pipeline (14), and the first bypass is located between the input end of the fourth valve (20) and the output end of the fifth valve (21). A sixth valve (22) is provided on the first bypass.

6. The thermal system of a boiler according to claim 2, characterized in that, A seventh valve (23) is provided on the second pipeline (14) near the input end of the evaporator (7), and an eighth valve (24) is provided on the third pipeline (15) near the output end of the evaporator (7).

7. The thermal system of a boiler according to claim 6, characterized in that, The second pipeline (14) is connected to the third pipeline (15) by a second bypass, and the second bypass is located between the input end of the seventh valve (23) and the output end of the eighth valve (24). A ninth valve (25) is provided on the second bypass.

8. The thermal system of a boiler according to claim 7, characterized in that, A tenth valve (26) is provided on the third pipeline (15) and near the second input end, and an eleventh valve (27) is provided on the fourth pipeline (16) and near the second output end.

9. The thermal system of a boiler according to claim 8, characterized in that, A third bypass is connected between the third pipeline (15) and the fourth pipeline (16), and the third bypass is located between the input end of the tenth valve (26) and the output end of the eleventh valve (27). A twelfth valve (28) is provided on the third bypass.

10. A control method for a boiler thermal system, employing the boiler thermal system according to any one of claims 1-9, characterized in that, Includes the following steps: The initial opening value of the preset flow regulation device is used to allow part of the medium to enter the pressure tank through the first branch; The temperature of the flue gas output from the isolated heat exchanger is obtained in real time through the temperature sensor. Calculate the deviation between the flue gas temperature and the set temperature, and determine the opening adjustment value of the flow regulating device based on the deviation value; The opening degree of the flow regulating device is dynamically adjusted according to the opening degree adjustment value to control the flow rate of the medium entering the pressure tank through the first branch. The fluctuations of waste heat flue gas in the isolation heat exchanger are adjusted by the medium in the pressure tank, so that the temperature of the flue gas output from the isolation heat exchanger to the flue gas flow channel remains stable. Stable flue gas is introduced into the flue gas flow channel to heat the medium flowing through the first flow channel and increase its temperature. The heated medium is heated by the evaporator to generate a steam-water mixture, which is then separated into steam by the steam drum and fed into the superheater.

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