Water vapor and fused salt double-medium gas-fired boiler system and operation method thereof

Abstract

The invention provides a water vapor and fused salt double-medium gas-fired boiler system which comprises a double-medium gas-fired boiler, a water vapor medium convection heat exchange area, a high-temperature fused salt heat exchange area, a water vapor medium convection heat exchange area, a high-temperature fused salt heat exchange area and a high-temperature fused salt heat exchange area, and the upper portion of the double-medium gas-fired boiler is provided with a boiler water inlet and a low-temperature fused salt inlet. A fused salt medium convection heat exchange area is arranged between the low-temperature fused salt inlet and the high-temperature fused salt outlet, a water vapor medium radiation heat exchange area and a fused salt medium radiation heat exchange area which are arranged in parallel and are independently partitioned are arranged on the lower portion of the double-medium gas-fired boiler, and a smoke distribution device is further arranged on the lower portion of the double-medium gas-fired boiler. A gas burner is arranged at the bottom of the double-medium gas boiler; a low-temperature fused salt storage tank; a high-temperature fused salt storage tank; an air preheater; provided is a gas heater. Two media of water vapor and fused salt are adopted, gas heat can be fully utilized, higher heat efficiency is achieved, smoke heat is reasonably utilized in the radiation heat exchange area and the convection heat exchange area, and the heat exchange efficiency is improved.

Description

Technical Field

[0001] This invention relates to a gas-fired boiler system and its operation method, specifically to a dual-medium gas-fired boiler system using steam and molten salt and its operation method, belonging to the field of energy equipment technology. Background Technology

[0002] In the existing technology, there are already steam power generation systems that combine molten salt energy storage devices with blast furnace gas combustion. However, with the increasing demand for peak shaving during peak and valley periods, how to store system heat during valley periods and release heat during peak periods to increase power generation and achieve better peak shaving is receiving increasing attention in this field.

[0003] In existing technologies, blast furnace gas-fired power generation systems that combine molten salt energy storage devices utilize molten salt to heat molten salt in the thermal storage system during off-peak hours, while the remaining blast furnace gas powers the power generation unit. During peak hours, boiler feedwater is heated by the molten salt heat exchanger in the thermal storage system, and the resulting steam is fed into the power generation system, releasing heat from the thermal storage system. Since the steam generated by the molten salt energy storage device and the steam generated by the boiler are fed into the turbine for power generation, the power output of the turbine unit is increased.

[0004] This system requires a complex molten salt energy storage device. In addition to a conventional gas-fired boiler, a dedicated heating system is needed to heat the molten salt from the blast furnace gas. This heating system is equipped with a separate combustion unit. Therefore, the entire system requires two separate blast furnace gas combustion units, each controlled independently, which increases the system's construction and operating costs and adds to the complexity of control. Summary of the Invention

[0005] Based on the above background, the purpose of this invention is to provide a dual-medium gas-fired boiler system of steam and molten salt to solve the problems described in the background art.

[0006] Another objective of this invention is to provide an operating method for a dual-medium gas-fired boiler system consisting of steam and molten salt.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0008] A dual-medium gas-fired boiler system consisting of steam and molten salt media includes:

[0009] A dual-medium gas-fired boiler is provided with a flue gas outlet at the top, a boiler water inlet and a low-temperature molten salt inlet at the upper part, a steam outlet and a high-temperature molten salt outlet at the middle part, a water-steam convection heat exchange zone between the boiler water inlet and the steam outlet, a molten salt convection heat exchange zone between the low-temperature molten salt inlet and the high-temperature molten salt outlet, and parallel and separately zoned water-steam radiation heat exchange zone and molten salt radiation heat exchange zone at the lower part. A flue gas distribution device is also provided at the lower part of the boiler. The water-steam radiation heat exchange zone and the molten salt radiation heat exchange zone are respectively connected to the bottom of the boiler through the flue gas distribution device. A gas burner is provided at the bottom of the boiler.

[0010] A low-temperature molten salt storage tank, wherein the low-temperature molten salt storage tank is connected to a low-temperature molten salt inlet via a pipeline, and the low-temperature molten salt storage tank is also connected to a high-temperature molten salt outlet via a pipeline;

[0011] A high-temperature molten salt storage tank, wherein the high-temperature molten salt storage tank is connected to a high-temperature molten salt outlet via a pipeline;

[0012] An air preheater, wherein the air outlet of the air preheater is connected to the air inlet of the gas burner, and the flue gas inlet of the air preheater is connected to the exhaust port of the dual-medium gas boiler;

[0013] A gas heater, wherein the gas outlet of the gas heater is connected to the gas inlet of the gas burner, and the flue gas inlet of the gas heater is connected to the flue gas outlet of the air preheater.

[0014] Preferably, the water vapor medium convection heat exchange zone is provided with at least two water vapor medium convection heat exchange components, and the molten salt medium convection heat exchange zone is provided with at least two molten salt medium convection heat exchange components, with the water vapor medium convection heat exchange components and the molten salt medium convection heat exchange components alternately arranged along the flue gas flow direction.

[0015] Preferably, the water vapor medium radiant heat exchange zone is provided with a water vapor medium radiant heat exchange component, which includes a water vapor medium radiant heat exchange header and a water vapor medium radiant heat exchange tube bundle, which is arranged along the flue gas flow direction. The molten salt medium radiant heat exchange zone is provided with a molten salt medium radiant heat exchange component, which includes a molten salt medium radiant heat exchange header and a molten salt medium radiant heat exchange tube bundle, which is arranged along the flue gas flow direction.

[0016] Preferably, the flue gas distribution device includes a flue gas distribution frame, a flue gas distribution baffle, and a flue gas distribution motor. The flue gas distribution frame and the flue gas distribution baffle are located inside the dual-medium gas boiler, and the flue gas distribution motor is located outside the dual-medium gas boiler. The flue gas distribution frame is fixedly connected to the dual-medium gas boiler, and a flue gas distribution channel is provided on the surface of the flue gas distribution frame. The flue gas distribution baffle is hinged to the flue gas distribution frame and located on the flue gas distribution channel. The output end of the flue gas distribution motor is connected to the hinge part of the flue gas distribution baffle. The flue gas distribution baffle can rotate relative to the flue gas distribution frame under the drive of the flue gas distribution motor, thereby allowing the flue gas distribution channel to be unobstructed and closed.

[0017] Preferably, the steam and molten salt dual-medium gas boiler system also includes an induced draft fan and a chimney, with the flue gas outlet of the gas heater connected to the chimney via the induced draft fan.

[0018] An operating method for a dual-medium gas-fired boiler system containing both steam and molten salt as described above, the method comprising the following steps:

[0019] The gas burner located at the bottom of the dual-medium gas boiler burns the gas supplied by the gas heater and the air supplied by the air preheater to generate high-temperature flue gas. Through the distribution of the flue gas distribution device, part of the high-temperature flue gas passes through the water steam medium radiation heat exchange zone for heat exchange, and the other part of the high-temperature flue gas passes through the molten salt medium radiation heat exchange zone for heat exchange. The two parts of high-temperature flue gas mix in the upper part of the dual-medium gas boiler, and after passing through the water steam medium convection heat exchange zone and the molten salt medium convection heat exchange zone for heat exchange, it is discharged from the exhaust port. Then, it passes through the air preheater to preheat the air and the gas heater to preheat the gas before being discharged.

[0020] The low-temperature molten salt stored in the low-temperature molten salt storage tank undergoes heat exchange in the molten salt medium convection heat exchange zone, and then in the molten salt medium radiation heat exchange zone, and is heated into high-temperature molten salt, which is then stored in the high-temperature molten salt storage tank.

[0021] The boiler feedwater undergoes heat exchange in the convective heat exchange zone of the steam medium and then in the radiative heat exchange zone of the steam medium, where it is heated into high-temperature steam and enters the external steam pipeline network.

[0022] Preferably, the method further includes the following steps:

[0023] Set the target temperature of molten salt at the high-temperature molten salt outlet and the target temperature of steam at the steam outlet, and measure the actual molten salt temperature at the high-temperature molten salt outlet and the actual steam temperature at the steam outlet in real time;

[0024] Based on the difference between the target temperature and the measured temperature of the molten salt, and the difference between the target temperature and the measured temperature of the steam, the flue gas flow adjustment of the flue gas distribution device corresponding to the molten salt medium radiation heat exchange zone and the water steam medium radiation heat exchange zone is calculated using the robust PID control method.

[0025] The flue gas flow rate entering the molten salt medium radiation heat exchange zone and the water vapor medium radiation heat exchange zone is controlled according to the flue gas flow rate adjustment, so that the difference between the target temperature of the molten salt and the measured temperature of the molten salt approaches zero.

[0026] Preferably, the mathematical expression of the robust PID control method is:

[0027]

[0028] In the formula, ΔQ is the flue gas flow rate adjustment, ΔT is the difference between the target temperature and the measured temperature, and K... p K is the proportionality coefficient. i K is the integral coefficient. d denoted as differential coefficients, and G is the structured singular value weight function.

[0029] Preferably, the structured singular value weight function G is obtained by the following method:

[0030] Collect input parameter data such as gas flow rate and combustion temperature, and output parameter data such as steam flow rate, steam temperature, steam pressure, molten salt flow rate, and molten salt temperature of the dual-medium gas boiler to obtain the frequency response of the dual-medium gas boiler;

[0031] The parameter data of the receipt is preprocessed by removing noise, filtering, and data alignment.

[0032] The frequency response model of the dual-medium gas boiler was obtained by identifying the preprocessed parameter data using the least squares method.

[0033] Frequency domain analysis of the frequency response model was performed using singular value decomposition.

[0034] Structured singular values ​​are extracted from frequency domain analysis and normalized so that the value range of the structured singular value weight function is within [0,1], thus generating the structured singular value weight function.

[0035] Preferably, the flue gas distribution device includes a flue gas distribution frame, a flue gas distribution baffle, and a flue gas distribution motor. The flue gas distribution frame and the flue gas distribution baffle are located inside the dual-medium gas-fired boiler, and the flue gas distribution motor is located outside the dual-medium gas-fired boiler. The flue gas distribution frame is fixedly connected to the dual-medium gas-fired boiler, and a flue gas distribution channel is provided on the surface of the flue gas distribution frame. The flue gas distribution baffle is hinged to the flue gas distribution frame and located on the flue gas distribution channel. The output end of the flue gas distribution motor is connected to the hinge portion of the flue gas distribution baffle. The flue gas distribution baffle can distribute the flue gas... Driven by the motor, the flue gas distribution motor rotates relative to the flue gas distribution frame, thereby opening and closing the flue gas distribution channel. In the robust PID control method, the flue gas flow adjustment ΔQ is a linear function of the angle between the flue gas distribution baffle and the flue gas distribution frame. The step of controlling the flue gas flow entering the molten salt medium radiative heat exchange zone and the water vapor medium radiative heat exchange zone according to the flue gas flow adjustment includes converting the flue gas flow adjustment into the change value of the angle between the flue gas distribution baffle and the flue gas distribution frame, and controlling the flue gas distribution motor to rotate by the corresponding angle according to the change value of the angle, thereby controlling the flue gas flow entering the molten salt medium radiative heat exchange zone and the water vapor medium radiative heat exchange zone.

[0036] Compared with the prior art, the present invention has the following advantages:

[0037] This invention discloses a dual-medium gas-fired boiler system using both steam and molten salt media. This system fully utilizes the heat from the gas, resulting in higher thermal efficiency. The radiant and convective heat exchange zones rationally utilize flue gas heat, further improving heat exchange efficiency. Compared to existing single-medium boilers, the thermal efficiency is increased by more than 5%. This dual-medium gas-fired boiler system effectively reduces pollutants generated during combustion, promotes complete fuel combustion, and saves fuel costs.

[0038] The present invention discloses an operation method for a dual-medium gas-fired boiler system of steam and molten salt. The method introduces a robust PID control method to control the system, which reduces the system's sensitivity to disturbances, enables it to respond quickly to load changes, and accurately control the output temperature of steam and molten salt. Furthermore, the robust PID control method is relatively simple to implement, does not require complex algorithms and hardware, and reduces the system control cost. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0040] Figure 1This is a schematic diagram of the structure of a dual-medium gas-fired boiler system of steam and molten salt according to the present invention;

[0041] Figure 2 This is a schematic diagram of the dual-medium gas boiler in this invention;

[0042] Figure 3 This is a schematic diagram of the flue gas distribution device in this invention.

[0043] In the diagram: 1. Dual-medium gas-fired boiler; 2. Low-temperature molten salt storage tank; 3. High-temperature molten salt storage tank; 4. Air preheater; 5. Gas heater; 6. Exhaust fan; 7. Chimney; 101. Flue gas outlet; 102. Boiler inlet; 103. Low-temperature molten salt inlet; 104. Steam outlet; 105. High-temperature molten salt outlet; 106. Flue gas distribution device; 107. Gas burner; 108. Water-steam medium convection heat exchange component; 109. Molten salt medium convection heat exchange component; 110. Water-steam medium radiant heat exchange component; 111. Molten salt medium radiant heat exchange component; 1061. Flue gas distribution frame; 1062. Flue gas distribution baffle; 1063. Flue gas distribution motor. Detailed Implementation

[0044] The technical solution of the present invention will be further described in detail below through specific embodiments and in conjunction with the accompanying drawings. It should be understood that the implementation of the present invention is not limited to the following embodiments, and any modifications and / or alterations made to the present invention will fall within the protection scope of the present invention.

[0045] In this invention, unless otherwise specified, all parts and percentages are by weight, and the equipment and raw materials used are commercially available or commonly used in the art. Unless otherwise specified, the methods in the following embodiments are conventional methods in the art. Unless otherwise specified, the components or equipment in the following embodiments are general standard parts or components known to those skilled in the art, and their structures and principles can be learned by those skilled in the art through technical manuals or conventional experimental methods.

[0046] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings. In this detailed description, numerous specific details are set forth to facilitate explanation and provide a thorough understanding of the embodiments of the present invention. However, one or more embodiments may be practiced by those skilled in the art without these specific details.

[0047] like Figure 1As shown, an embodiment of the present invention discloses a dual-medium gas-fired boiler system (steam and molten salt), comprising a dual-medium gas-fired boiler 1, a low-temperature molten salt storage tank 2, a high-temperature molten salt storage tank 3, an air preheater 4, and a gas heater 5. The dual-medium gas-fired boiler system also includes an induced draft fan 6 and a chimney 7, with the flue gas outlet of the gas heater 5 connected to the chimney 7 via the induced draft fan 6.

[0048] like Figure 2 As shown, the dual-medium gas boiler 1 has a flue gas outlet 101 at the top, a boiler inlet 102 and a low-temperature molten salt inlet 103 at the upper part, a steam outlet 104 and a high-temperature molten salt outlet 105 at the middle part, a water-steam convection heat exchange zone between the boiler inlet 102 and the steam outlet 104, a molten salt convection heat exchange zone between the low-temperature molten salt inlet 103 and the high-temperature molten salt outlet 105, a water-steam convection heat exchange zone between the lower part of the dual-medium gas boiler 1 and a water-steam radiant heat exchange zone and a molten salt radiant heat exchange zone arranged in parallel and separately partitioned at the lower part of the dual-medium gas boiler 1, a flue gas distribution device 106 at the lower part of the dual-medium gas boiler 1, the water-steam radiant heat exchange zone and the molten salt radiant heat exchange zone being connected to the bottom of the dual-medium gas boiler 1 through the flue gas distribution device 106, and a gas burner 107 at the bottom of the dual-medium gas boiler 1.

[0049] Specifically, the steam convection heat exchange zone is equipped with two steam convection heat exchange components 108, and the molten salt convection heat exchange zone is equipped with two molten salt convection heat exchange components 109. The steam convection heat exchange components 108 and molten salt convection heat exchange components 109 are alternately arranged along the flue gas flow direction. Of course, the number of steam convection heat exchange components 108 and molten salt convection heat exchange components 109 can be increased as appropriate, depending on the specific application scenario and heat exchange requirements.

[0050] Specifically, the steam medium radiation heat exchange zone is provided with a steam medium radiation heat exchange component 110, which includes a steam medium radiation heat exchange header and a steam medium radiation heat exchange tube bundle. The steam medium radiation heat exchange tube bundle is arranged along the flue gas flow direction. The molten salt medium radiation heat exchange zone is provided with a molten salt medium radiation heat exchange component 111, which includes a molten salt medium radiation heat exchange header and a molten salt medium radiation heat exchange tube bundle. The molten salt medium radiation heat exchange tube bundle is arranged along the flue gas flow direction.

[0051] Specifically, such as Figure 3As shown, the flue gas distribution device 106 includes a flue gas distribution frame 1061, a flue gas distribution baffle 1062, and a flue gas distribution motor 1063. The flue gas distribution frame 1061 and the flue gas distribution baffle 1062 are located inside the dual-medium gas boiler 1, and the flue gas distribution motor 1063 is located outside the dual-medium gas boiler 1. The flue gas distribution frame 1061 is fixedly connected to the dual-medium gas boiler 1, and a flue gas distribution channel is provided on the surface of the flue gas distribution frame 1061. The flue gas distribution baffle 1062 is hinged to the flue gas distribution frame 1061 and located on the flue gas distribution channel. The output end of the flue gas distribution motor 1063 is connected to the hinge part of the flue gas distribution baffle 1062. The flue gas distribution baffle 1062 can rotate relative to the flue gas distribution frame 1061 under the drive of the flue gas distribution motor 1063, thereby opening and closing the flue gas distribution channel.

[0052] The low-temperature molten salt storage tank 2 is connected to the low-temperature molten salt inlet 103 via a pipeline, and is also connected to the high-temperature molten salt outlet 105 via a pipeline. The high-temperature molten salt storage tank 3 is connected to the high-temperature molten salt outlet 105 via a pipeline. The air outlet of the air preheater 4 is connected to the air inlet of the gas burner 107, and the flue gas inlet of the air preheater 4 is connected to the exhaust port 101 of the dual-medium gas boiler 1. The gas outlet of the gas heater 5 is connected to the gas inlet of the gas burner 107, and the flue gas inlet of the gas heater 5 is connected to the flue gas outlet of the air preheater 4.

[0053] The dual-medium gas-fired boiler system 1, which uses both steam and molten salt as media, can fully utilize the heat of the gas and has higher thermal efficiency. The radiant heat exchange zone and the convective heat exchange zone make reasonable use of the heat of the flue gas, improving the heat exchange efficiency. Compared with the existing single-medium boiler, the thermal efficiency can be improved by more than 5%. The dual-medium gas-fired boiler system 1 can effectively reduce the pollutants generated by combustion, promote the complete combustion of fuel, and save fuel costs.

[0054] An embodiment of the present invention also discloses an operation method for a dual-medium gas-fired boiler system consisting of steam and molten salt, the method comprising the following steps:

[0055] The gas burner 107 located at the bottom of the dual-medium gas boiler 1 burns the gas supplied by the gas heater 5 and the air supplied by the air preheater 4 to generate high-temperature flue gas. Through the distribution of the flue gas distribution device 106, part of the high-temperature flue gas passes through the water steam medium radiation heat exchange zone for heat exchange, and the other part of the high-temperature flue gas passes through the molten salt medium radiation heat exchange zone for heat exchange. The two parts of high-temperature flue gas mix in the upper part of the dual-medium gas boiler 1, and after passing through the water steam medium convection heat exchange zone and the molten salt medium convection heat exchange zone for heat exchange, it is discharged from the exhaust port 101. Then, it passes through the air preheater 4 to preheat the air and through the gas heater 5 to preheat the gas before being discharged.

[0056] The low-temperature molten salt stored in the low-temperature molten salt storage tank 2 undergoes heat exchange in the molten salt medium convection heat exchange zone and then in the molten salt medium radiation heat exchange zone, and is heated into high-temperature molten salt, which is then stored in the high-temperature molten salt storage tank 3.

[0057] The boiler feedwater undergoes heat exchange in the convective heat exchange zone of the steam medium and then in the radiative heat exchange zone of the steam medium, where it is heated into high-temperature steam and enters the external steam pipeline network.

[0058] The method also includes the following steps:

[0059] Set the target temperature of molten salt at the high-temperature molten salt outlet 105 and the target temperature of steam at the steam outlet 104, and measure the actual molten salt temperature at the high-temperature molten salt outlet 105 and the actual steam temperature at the steam outlet 104 in real time using a temperature sensor.

[0060] Based on the difference between the target temperature of molten salt and the measured temperature of molten salt, and the difference between the target temperature of steam and the measured temperature of steam, the flue gas flow adjustment of the flue gas distribution device 106 corresponding to the molten salt medium radiation heat exchange zone and the water steam medium radiation heat exchange zone is calculated using the robust PID control method.

[0061] The flue gas flow rate entering the molten salt medium radiation heat exchange zone and the water vapor medium radiation heat exchange zone is controlled according to the flue gas flow rate adjustment, so that the difference between the target temperature of the molten salt and the measured temperature of the molten salt approaches zero.

[0062] Specifically, the mathematical expression for the robust PID control method is:

[0063]

[0064] In the formula, ΔQ is the flue gas flow rate adjustment, ΔT is the difference between the target temperature and the measured temperature, and K... p K is the proportionality coefficient. i K is the integral coefficient. d denoted as differential coefficients, and G is the structured singular value weight function.

[0065] In the robust PID control method described above, the flue gas flow adjustment ΔQ is a linear function of the angle between the flue gas distribution baffle 1062 and the flue gas distribution frame 1061. Controlling the flue gas flow entering the molten salt medium radiant heat exchange zone and the water vapor medium radiant heat exchange zone based on the flue gas flow adjustment includes converting the flue gas flow adjustment into the change value of the angle between the flue gas distribution baffle 1062 and the flue gas distribution frame 1061, and controlling the flue gas distribution motor 1063 to rotate by the corresponding angle based on the change value of the angle, thereby controlling the flue gas flow entering the molten salt medium radiant heat exchange zone and the water vapor medium radiant heat exchange zone.

[0066] Specifically, the structured singular value weight function G is obtained through the following method:

[0067] Collect input parameter data such as gas flow rate and combustion temperature, and output parameter data such as steam flow rate, steam temperature, steam pressure, molten salt flow rate, and molten salt temperature of the dual-medium gas boiler 1 to obtain the frequency response of the dual-medium gas boiler 1;

[0068] The parameter data of the receipt is preprocessed by removing noise, filtering, and data alignment.

[0069] The frequency response model of the dual-medium gas boiler 1 was obtained by identifying the preprocessed parameter data using the least squares method.

[0070] Frequency domain analysis of the frequency response model was performed using singular value decomposition.

[0071] Structured singular values ​​are extracted from frequency domain analysis and normalized so that the value range of the structured singular value weight function is within [0,1], thus generating the structured singular value weight function.

[0072] This operating method introduces a robust PID control method to control the system, which reduces the system's sensitivity to disturbances, enables it to respond quickly to load changes, and accurately control the output temperature of steam and molten salt. Furthermore, the robust PID control method is relatively simple to implement, requiring no complex algorithms or hardware, thus reducing system control costs.

[0073] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A dual-medium gas-fired boiler system (1) consisting of steam and molten salt, characterized in that: The dual-medium gas-fired boiler (1) system, consisting of steam and molten salt, includes: A dual-medium gas-fired boiler (1) is provided with a flue gas outlet (101) at the top, a boiler water inlet (102) and a low-temperature molten salt inlet (103) at the upper part of the dual-medium gas-fired boiler (1), a steam outlet (104) and a high-temperature molten salt outlet (105) at the middle part of the dual-medium gas-fired boiler (1), a water-steam convection heat exchange zone between the boiler water inlet (102) and the steam outlet (104) of the dual-medium gas-fired boiler (1), and a low-temperature molten salt inlet (105) of the dual-medium gas-fired boiler (106) at the low-temperature molten salt inlet (107). 3) A molten salt medium convection heat exchange zone is provided between the high temperature molten salt outlet (105). The lower part of the dual-medium gas boiler (1) is provided with a water steam medium radiation heat exchange zone and a molten salt medium radiation heat exchange zone arranged in parallel and separately partitioned. The lower part of the dual-medium gas boiler (1) is also provided with a flue gas distribution device (106). The water steam medium radiation heat exchange zone and the molten salt medium radiation heat exchange zone are respectively connected to the bottom of the dual-medium gas boiler (1) through the flue gas distribution device (106). The bottom of the dual-medium gas boiler (1) is provided with a gas burner (107). The low-temperature molten salt storage tank (2) is connected to the low-temperature molten salt inlet (103) via a pipeline, and the low-temperature molten salt storage tank (2) is also connected to the high-temperature molten salt outlet (105) via a pipeline; A high-temperature molten salt storage tank (3) is connected to the high-temperature molten salt outlet (105) via a pipeline; Air preheater (4), the air outlet of the air preheater (4) is connected to the air inlet of the gas burner (107), and the flue gas inlet of the air preheater (4) is connected to the exhaust port (101) of the dual-medium gas boiler (1); A gas heater (5) is provided, wherein the gas outlet of the gas heater (5) is connected to the gas inlet of the gas burner (107), and the flue gas inlet of the gas heater (5) is connected to the flue gas outlet of the air preheater (4).

2. The dual-medium gas-fired boiler (1) system of steam and molten salt according to claim 1, characterized in that: The water vapor medium convection heat exchange zone is provided with at least two water vapor medium convection heat exchange components (108), and the molten salt medium convection heat exchange zone is provided with at least two molten salt medium convection heat exchange components (109). The water vapor medium convection heat exchange components (108) and the molten salt medium convection heat exchange components (109) are alternately arranged along the flue gas flow direction.

3. The dual-medium gas-fired boiler (1) system of steam and molten salt according to claim 1, characterized in that: The water vapor medium radiation heat exchange zone is provided with a water vapor medium radiation heat exchange component (110), which includes a water vapor medium radiation heat exchange header and a water vapor medium radiation heat exchange tube bundle. The water vapor medium radiation heat exchange tube bundle is arranged along the flue gas flow direction. The molten salt medium radiation heat exchange zone is provided with a molten salt medium radiation heat exchange component (111), which includes a molten salt medium radiation heat exchange header and a molten salt medium radiation heat exchange tube bundle. The molten salt medium radiation heat exchange tube bundle is arranged along the flue gas flow direction.

4. The dual-medium gas-fired boiler (1) system of steam and molten salt according to claim 1, characterized in that: The flue gas distribution device (106) includes a flue gas distribution frame (1061), a flue gas distribution baffle (1062), and a flue gas distribution motor (1063). The flue gas distribution frame (1061) and the flue gas distribution baffle (1062) are located inside the dual-medium gas boiler (1), and the flue gas distribution motor (1063) is located outside the dual-medium gas boiler (1). The flue gas distribution frame (1061) is fixedly connected to the dual-medium gas boiler (1). The surface of the frame (1061) is provided with a flue gas distribution channel. The flue gas distribution baffle (1062) is hinged to the flue gas distribution frame (1061) and located on the flue gas distribution channel. The output end of the flue gas distribution motor (1063) is connected to the hinge part of the flue gas distribution baffle (1062). The flue gas distribution baffle (1062) can rotate relative to the flue gas distribution frame (1061) under the drive of the flue gas distribution motor (1063), thereby making the flue gas distribution channel unobstructed and closed.

5. The dual-medium gas-fired boiler (1) system of steam and molten salt according to claim 1, characterized in that: The steam and molten salt dual-medium gas boiler (1) system also includes an induced draft fan (6) and a chimney (7), and the flue gas outlet of the gas heater (5) is connected to the chimney (7) through the induced draft fan (6).

6. A method for operating a dual-medium gas-fired boiler (1) system of steam and molten salt as described in any one of claims 1-5, characterized in that: The method includes the following steps: The gas burner (107) located at the bottom of the dual-medium gas boiler (1) burns the gas supplied by the gas heater (5) and the air supplied by the air preheater (4) to generate high-temperature flue gas. Through the distribution of the flue gas distribution device (106), part of the high-temperature flue gas passes through the water steam medium radiation heat exchange zone for heat exchange, and the other part of the high-temperature flue gas passes through the molten salt medium radiation heat exchange zone for heat exchange. The two parts of high-temperature flue gas mix in the upper part of the dual-medium gas boiler (1), and after passing through the water steam medium convection heat exchange zone and the molten salt medium convection heat exchange zone for heat exchange, it is discharged from the exhaust port (101). Then, it passes through the air preheater (4) to preheat the air and through the gas heater (5) to preheat the gas before being discharged. The low-temperature molten salt stored in the low-temperature molten salt storage tank (2) is heated to high-temperature molten salt by passing through the molten salt medium convection heat exchange zone and then through the molten salt medium radiation heat exchange zone, and then enters the high-temperature molten salt storage tank (3) for storage. The boiler feedwater undergoes heat exchange in the convective heat exchange zone of the steam medium and then in the radiative heat exchange zone of the steam medium, where it is heated into high-temperature steam and enters the external steam pipeline network.

7. The operating method of a dual-medium gas-fired boiler (1) system of steam and molten salt according to claim 6, characterized in that: The method also includes the following steps: Set the target temperature of molten salt at the high-temperature molten salt outlet (105) and the target temperature of steam at the steam outlet (104), and measure the actual molten salt temperature at the high-temperature molten salt outlet (105) and the actual steam temperature at the steam outlet (104) in real time. Based on the difference between the target temperature of molten salt and the measured temperature of molten salt, and the difference between the target temperature of steam and the measured temperature of steam, the flue gas flow adjustment of the flue gas distribution device (106) corresponding to the molten salt medium radiation heat exchange zone and the water steam medium radiation heat exchange zone is calculated by using the robust PID control method. The flue gas flow rate entering the molten salt medium radiation heat exchange zone and the water vapor medium radiation heat exchange zone is controlled according to the flue gas flow rate adjustment, so that the difference between the target temperature of the molten salt and the measured temperature of the molten salt approaches zero.

8. The operating method of a dual-medium gas-fired boiler (1) system of steam and molten salt according to claim 7, characterized in that: The mathematical expression for the robust PID control method is: In the formula, ΔQ is the flue gas flow rate adjustment, ΔT is the difference between the target temperature and the measured temperature, and K... p K is the proportionality coefficient. i K is the integral coefficient. d denoted as differential coefficients, and G is the structured singular value weight function.

9. The operating method of a dual-medium gas-fired boiler (1) system of steam and molten salt according to claim 8, characterized in that: The structured singular value weight function G is obtained through the following method: Collect input parameter data such as gas flow rate and combustion temperature and output parameter data such as steam flow rate, steam temperature, steam pressure, molten salt flow rate and molten salt temperature of the dual-medium gas boiler (1) to obtain the frequency response of the dual-medium gas boiler (1); The parameter data of the receipt is preprocessed by removing noise, filtering, and data alignment. The frequency response model of the dual-medium gas boiler (1) was obtained by identifying the preprocessed parameter data using the least squares method. Frequency domain analysis of the frequency response model was performed using singular value decomposition. Structured singular values ​​are extracted from frequency domain analysis and normalized so that the value range of the structured singular value weight function is within [0,1], thus generating the structured singular value weight function.

10. The operating method of a dual-medium gas-fired boiler (1) system of steam and molten salt according to claim 7, characterized in that: The flue gas distribution device (106) includes a flue gas distribution frame (1061), a flue gas distribution baffle (1062), and a flue gas distribution motor (1063). The flue gas distribution frame (1061) and the flue gas distribution baffle (1062) are located inside the dual-medium gas boiler (1), and the flue gas distribution motor (1063) is located outside the dual-medium gas boiler (1). The flue gas distribution frame (1061) is fixedly connected to the dual-medium gas boiler (1), and a flue gas distribution channel is provided on the surface of the flue gas distribution frame (1061). The flue gas distribution baffle (1062) is hinged to the flue gas distribution frame (1061) and located on the flue gas distribution channel. The output end of the flue gas distribution motor (1063) is connected to the hinge part of the flue gas distribution baffle (1062). The flue gas distribution baffle (1062) can rotate relative to the flue gas distribution frame (1061) under the drive of the flue gas distribution motor (1063), thereby opening and closing the flue gas distribution channel; in the robust PID control method, the flue gas flow adjustment amount ΔQ is a linear function of the angle between the flue gas distribution baffle (1062) and the flue gas distribution frame (1061), and the control of the flue gas flow entering the molten salt medium radiation heat exchange zone and the water vapor medium radiation heat exchange zone according to the flue gas flow adjustment amount includes converting the flue gas flow adjustment amount into the change value of the angle between the flue gas distribution baffle (1062) and the flue gas distribution frame (1061), and controlling the flue gas distribution motor (1063) to rotate by the corresponding angle according to the change value of the angle, thereby controlling the flue gas flow entering the molten salt medium radiation heat exchange zone and the water vapor medium radiation heat exchange zone.

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