Three-dimensional structure and control method of flue gas molten salt heat exchange system driven by boiler flue gas

Abstract

The application provides a boiler flue gas driven flue gas molten salt heat exchange system three-dimensional structure and a control method, which comprises a boiler, a first network structure comprising at least two flue gas taking flues connected to different temperature zone flue sections, a second network structure comprising a plurality of flue gas-molten salt heat exchange units, a plurality of flue gas shunt manifolds, and an outlet of a last-stage flue gas shunt manifold and an inlet of a flue gas-molten salt heat exchange unit being communicated, and further comprising a plurality of flue gas shunt manifolds, an inlet of a first-stage flue gas shunt manifold and an outlet of a flue gas-molten salt heat exchange unit being communicated, a flow cross-sectional dimension of the plurality of flue gas shunt manifolds gradually decreasing, a flow cross-sectional dimension of the plurality of flue gas shunt manifolds gradually increasing, and a flue gas mixing device, an inlet of which is communicated with the first network structure and an outlet of which is communicated with a first-stage flue gas shunt manifold of the second network structure. The scheme can reduce the flow resistance of the flue system, provide the molten salt heat exchange with flue gas of moderate and uniform temperature, and improve the safety of the boiler and the molten salt system.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of boiler and flue gas molten salt heat exchange technology, in particular to a three-dimensional structure of a flue gas molten salt heat exchange system driven by boiler flue gas and a control method. BACKGROUND

[0002] Increasing the molten salt heat storage system is the main way to improve the flexibility of coal-fired generating units. Compared with the steam molten salt heat storage technology, extracting boiler flue gas to heat molten salt heat storage is a technology with high energy storage efficiency, simple system and easy maintenance. However, the design and operation of the flue gas molten salt heat exchange system need to consider the process requirements of the molten salt heat exchange system and the boiler at the same time, and face many challenges.

[0003] Firstly, the temperature range between the solidification point and the decomposition point of molten salt is relatively narrow, only about 200-400℃, and the molten salt temperature needs to be strictly controlled within the operating range during operation to avoid problems such as molten salt solidification and pipe blockage or decomposition. The flue gas from the boiler changes with the load and has instantaneous fluctuations, and the molten salt flow is small when the flue gas molten salt heat exchange system starts and stops, which is prone to over-temperature decomposition.

[0004] Secondly, the safe operation of each stage of heating surface in the boiler is closely related to the characteristics of the flue gas flow field and temperature field. The extraction of flue gas by the flue gas molten salt heat exchange system changes the spatial distribution of flue gas temperature and flow in the boiler, which may cause problems such as overheating and pipe explosion of the heating surface, and coking.

[0005] Therefore, it is an urgent problem for those skilled in the art to provide flue gas with uniform temperature to the flue gas molten salt heat exchanger, optimize the design of the boiler flue gas extraction structure, and improve the safety of the operation of the flue gas molten salt heat exchange system and the boiler. SUMMARY

[0006] The purpose of the present application is to provide a three-dimensional structure of a flue gas molten salt heat exchange system driven by boiler flue gas, which is beneficial to providing flue gas with uniform, stable, moderate high and low temperature to the flue gas molten salt heat exchanger, safely extracting flue gas from the boiler, and reducing the overall flow resistance of the flue gas.

[0007] To solve the above technical problems, the present application provides a three-dimensional structure of a flue gas molten salt heat exchange system driven by boiler flue gas, comprising:

[0008] a boiler, the boiler comprising a plurality of different temperature zone flue sections distributed along the flue gas flow direction;

[0009] a first network structure comprising at least two flue gas extraction flues, the at least two flue gas extraction flues being communicated with different temperature zone flue sections; each flue gas extraction flue is provided with a flow adjusting component;

[0010] The second network structure comprises a flue gas molten salt heat exchanger, which comprises a plurality of flue gas-molten salt heat exchange units; the second network structure further comprises a plurality of flue gas shunt headers which are shunted step by step along the flue gas flow direction, and the outlet of the flue gas shunt header of the last stage and the flue gas inlet of the flue gas-molten salt heat exchange unit are communicated; the second network structure comprises a plurality of flue gas shunt headers which are shunted step by step along the flue gas flow direction, and the inlet of the flue gas shunt header of the first stage and the flue gas outlet of the flue gas-molten salt heat exchange unit are communicated;

[0011] The cross-sectional dimension of the plurality of flue gas shunt headers gradually decreases along the flue gas flow direction; the cross-sectional dimension of the plurality of flue gas shunt headers gradually increases along the flue gas flow direction;

[0012] A flue gas mixing device, the inlet of which is communicated with the first network structure, and the outlet of which is communicated with the flue gas shunt header of the first stage of the second network structure.

[0013] Optionally, the boiler comprises a plurality of flue sections of different temperature zones which are distributed along the flue gas flow direction, and at least two of the flue gas taking flues are communicated with flue sections of different temperature zones.

[0014] Optionally, the first network structure further comprises a first centralized flue, the inlet of which is connected with each of the flue gas taking flues, and the outlet of which is connected with the inlet of the flue gas mixing device; the cross-sectional dimension of the first centralized flue is larger than that of the flue gas taking flues.

[0015] Optionally, at least one second centralized flue is further comprised, the inlet of which is connected with at least two of the flue gas taking flues, and the outlet of which is connected with the inlet of the first centralized flue; the cross-sectional dimension of the second centralized flue is larger than that of the flue gas taking flues, and smaller than that of the first centralized flue.

[0016] Optionally, at least one third centralized flue is further comprised, the inlet of which is connected with the outlet of the second centralized flue and at least one of the flue gas taking flues, and the outlet of which is connected with the inlet of the first centralized flue; the cross-sectional dimension of the third centralized flue is larger than that of the flue gas taking flues, and smaller than that of the first centralized flue.

[0017] Optionally, the flue gas mixing device comprises at least one gas inlet flue, which is communicated with the flue gas taking flues, or with the first centralized flue, or with the second centralized flue, or with the third centralized flue;

[0018] The flue gas mixing device comprises a main cylinder, each of the flue gas inlets is tangent to the main cylinder; a plurality of the flue gas inlets are distributed along the circumference of the main cylinder, or a plurality of the flue gas inlets are distributed along the height direction of the main cylinder.

[0019] Optionally, the flue gas mixing device comprises an exhaust cylinder coaxially arranged with the main cylinder, the lower end of the exhaust cylinder penetrates the upper end surface of the main cylinder and extends into the interior of the main cylinder, and the flue gas outlet of the flue gas mixing device is the outlet of the exhaust cylinder; the flue gas mixing device further comprises a variable-diameter cylinder, which is located below the main cylinder.

[0020] Optionally, the multi-stage flue gas shunt manifold of the second-level network structure comprises a first-stage flue gas shunt manifold, a second-stage flue gas shunt manifold, a third-stage flue gas shunt manifold, and a fourth-stage flue gas shunt manifold; the first-stage flue gas shunt manifold is the primary flue gas shunt manifold, and the fourth-stage flue gas shunt manifold is the final flue gas shunt manifold.

[0021] The first-stage flue gas shunt manifold is arranged in a vertically downward direction, the second-stage flue gas shunt manifold and the third-stage flue gas shunt manifold are both arranged in a horizontal direction and perpendicular to each other, and the fourth-stage flue gas shunt manifold is arranged in a vertically downward direction.

[0022] The first-stage flue gas shunt manifold is connected with at least two second-stage flue gas shunt manifolds, the second-stage flue gas shunt manifold is connected with at least two third-stage flue gas shunt manifolds, and the third-stage flue gas shunt manifold is connected with at least two fourth-stage flue gas shunt manifolds.

[0023] The fourth-stage flue gas shunt manifold is connected with the flue gas inlet of the flue gas-molten salt heat exchange unit.

[0024] Optionally, the multi-stage flue gas shunt manifold of the second-level network structure comprises a first-stage flue gas shunt manifold, a second-stage flue gas shunt manifold, a third-stage flue gas shunt manifold, and a fourth-stage flue gas shunt manifold; the first-stage flue gas shunt manifold is the primary flue gas shunt manifold, and the fourth-stage flue gas shunt manifold is the final flue gas shunt manifold.

[0025] The first-stage flue gas shunt manifold and the first-stage flue gas shunt manifold are arranged in parallel, the second-stage flue gas shunt manifold and the second-stage flue gas shunt manifold are arranged in parallel, the third-stage flue gas shunt manifold and the third-stage flue gas shunt manifold are arranged in parallel, and the fourth-stage flue gas shunt manifold and the fourth-stage flue gas shunt manifold are arranged in parallel.

[0026] The fourth-stage flue gas shunt manifold is connected with the flue gas inlet of the flue gas-molten salt heat exchange unit.

[0027] The primary flue gas manifold is connected with at least two secondary flue gas manifolds, the secondary flue gas manifolds are connected with at least two tertiary flue gas manifolds, and the tertiary flue gas manifolds are connected with at least two quaternary flue gas distribution manifolds.

[0028] Optionally, the second network structure comprises a plurality of groups of heat exchanger modules, each group of the heat exchanger modules comprising at least two flue gas-molten salt heat exchange units;

[0029] The inlets of the flue gas-molten salt heat exchange units in the same group of the heat exchanger modules are connected to the same tertiary flue gas distribution manifold through the quaternary flue gas distribution manifolds, and the outlets of the flue gas-molten salt heat exchange units in the same group of the heat exchanger modules are connected to the same tertiary flue gas collection manifold through the quaternary flue gas collection manifolds.

[0030] Optionally, the application further comprises a back smoke flue and an induced draft fan, the outlet of the last-stage flue gas collection manifold is connected to the back smoke flue, the back smoke flue is connected to the boiler, and the induced draft fan is arranged in the back smoke flue or between the back smoke flue and the last-stage flue gas collection manifold.

[0031] Optionally, the application further comprises a second connecting flue, the outlet of the last-stage flue gas collection manifold and the back smoke flue are connected through the second connecting flue, and further comprises a flow meter, which is arranged in the back smoke flue or the second connecting flue and is used for detecting the flow of flue gas.

[0032] The application further provides a control method based on the three-dimensional structure of the flue gas-molten salt heat exchanger system driven by the flue gas of the boiler according to any one of the above-mentioned embodiments, each of the flue gas-water heat exchangers arranged in the temperature zone flue section, the control method comprising:

[0033] According to the heat load working condition requirement of the flue section of the boiler and the flue gas requirement of the flue gas-molten salt heat exchanger, the flow of each smoke taking flue is adjusted through the flow adjusting component.

[0034] Optionally, when the steam temperature of the flue gas-water heat exchanger arranged in any flue section connected with the smoke taking flue exceeds a preset value, the flue gas flow of the smoke taking flue of the flue section where the flue gas-water heat exchanger is arranged is increased.

[0035] The temperature zone flue section corresponding to the flue gas-water heat exchanger whose steam temperature exceeds the preset value is defined as temperature zone flue section one, and any temperature zone flue section connected with the smoke taking flue downstream of the temperature zone flue section one is defined as temperature zone flue section two, and the flue gas flow of the smoke taking flue corresponding to the temperature zone flue section two is simultaneously increased.

[0036] Optionally, the boiler comprises a boiler denitration zone, and the last-stage flue gas manifold is communicated with the boiler denitration zone through a back-smoke flue, or a warm zone flue section adjacent to the boiler denitration zone.

[0037] When the temperature of the boiler denitration zone is lower than a preset value, the molten salt of the flue gas molten salt heat exchanger is controlled to flow into a molten salt tank, and at least one smoke flue is opened.

[0038] The three-dimensional structure design of the boiler flue gas driven flue gas molten salt heat exchange system in the application has the following technical effects:

[0039] 1. The hierarchical structure with different sizes is adopted to effectively reduce the flow resistance of the flue system.

[0040] In the embodiment, the flue gas flow path of the flue gas extracted and returned to the boiler is optimized and designed to form a multi-stage flow network, which can reduce the flow resistance. Specifically, the first-stage network structure is adopted to realize that the flue gas is extracted from the boiler through the smoke flue and then gathered to the flue gas mixing device, and the second-stage network structure is adopted to realize that the flue gas is dispersed from the centralized flue of the flue gas mixing device to the plurality of flue gas-molten salt heat exchange units and then gathered again. It can be seen that the flue gas flow path of the above-mentioned flue gas molten salt heat exchange system three-dimensional structure is a multi-stage flow network, which makes the flue gas flow more regular and more organized. In actual engineering, the flow resistance can be further reduced by further optimizing the pipe size design.

[0041] 2. The flue gas temperature is adjustable, which is beneficial to the safe and stable operation and start-stop of the flue gas molten salt heat exchange system.

[0042] In the flue gas molten salt heat exchange system, the flue gas can be taken from two or more warm zone flue sections of the boiler as a heat source. On the one hand, by changing the mixing ratio of the multiple flue gases taken from the smoke flue, the flue gas temperature can be adjusted in a large range, which can reduce the influence of the flue gas temperature fluctuation of the boiler on the flue gas molten salt heat exchange system, make the flue gas temperature more stable and moderate, and improve the operation safety and flexibility of the flue gas molten salt heat exchange system. On the other hand, during start-up, lower temperature flue gas can be first introduced to preheat the flue gas molten salt heat exchanger, so as to realize the safe start-up of the flue gas molten salt heat exchange system.

[0043] 3. The flue gas temperature field is uniform, which is beneficial to realizing the molten salt operation safety of the flue gas molten salt heat exchange system.

[0044] This flue gas molten salt heat exchange system includes a flue gas mixing device. This device mixes multiple flue gas streams, ensuring they enter the molten salt heat exchanger more uniformly and improving the safety of molten salt operation. Especially when multiple flue gas streams have different temperatures, the mixing device can combine them into a single stream with minimal temperature deviation, serving as the inlet gas for the molten salt heat exchange unit. This effectively prevents localized overheating and decomposition of the molten salt, guaranteeing safe operation.

[0045] 4. Decentralized smoke extraction helps improve boiler safety.

[0046] The flue gas intake ducts draw flue gas from the boiler, which is connected to multiple ducts. This allows for a large number of small individual intake ports, effectively reducing the flue gas flow rate at each port, minimizing disturbance to the flue gas flow field within the boiler, and improving boiler operational safety. Furthermore, the intake ports are distributed across different temperature zones (representing different flue gas temperature levels) within the boiler's flue gas ducts. Each temperature zone section can also have intake ports at different locations, meaning at least two intake ports can be installed in a single temperature zone section. This more dispersed arrangement of the intake ports further reduces their disturbance to the flue gas flow field within the boiler. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the first embodiment of the three-dimensional structure of the flue gas driven molten salt heat exchange system of this application;

[0048] Figure 2 for Figure 1 Schematic diagram of the structure of multiple temperature zone flue sections of a medium-sized boiler;

[0049] Figure 3 for Figure 2 Schematic diagram of the first type of smoke intake distribution structure in the flue section of the medium-temperature zone;

[0050] Figure 4 for Figure 2 Schematic diagram of the second type of smoke intake distribution structure in the flue section of the medium-temperature zone;

[0051] Figure 5 for Figure 2 Schematic diagram of the third type of smoke intake distribution structure in the flue section of the medium-temperature zone;

[0052] Figure 6 for Figure 1 A schematic diagram of the first structure of a flue gas mixing device;

[0053] Figure 7 for Figure 1 A schematic diagram of the second structure of the flue gas mixing device;

[0054] Figure 8 This is a schematic diagram of a second-level network structure in an embodiment of this application;

[0055] Figure 9 Schematic diagram of the second embodiment of the three-dimensional structure of the flue gas molten salt heat exchange system driven by the boiler flue gas of the present application;

[0056] Figure 10 Schematic diagram of the third embodiment of the three-dimensional structure of the flue gas molten salt heat exchange system driven by the boiler flue gas of the present application;

[0057] Figure 11 Schematic diagram of the third embodiment of the three-dimensional structure of the flue gas molten salt heat exchange system driven by the boiler flue gas of the present application; Figure 10 Heat load distribution diagram of different temperature zone flue sections of the medium boiler and the flue gas molten salt heat exchange system.

[0058] The reference signs in the drawings are explained as follows:

[0059] 100 - boiler;

[0060] 101 - first temperature zone flue section; 102 - second temperature zone flue section; 103 - third temperature zone flue section; 104 - fourth temperature zone flue section; 105 - fifth temperature zone flue section;

[0061] 106 - smoke taking port;

[0062] 107 - boiler denitration zone; 107a - back smoke port;

[0063] 200 - flue gas mixing device; 201 - main cylinder; 202 - reducing cylinder; 203 - inlet flue; 204 - exhaust cylinder;

[0064] 300 - smoke taking flue; 301 - first smoke taking flue; 302 - second smoke taking flue; 303 - third smoke taking flue; 304 - fourth smoke taking flue; 305 - fifth smoke taking flue;

[0065] 401 - shut-off baffle; 402 - flow regulating component; 404 - flow meter;

[0066] 500 - back smoke flue;

[0067] 600 - induced draft fan;

[0068] 801 - first connecting flue; 802 - second connecting flue;

[0069] 901 - second centralized flue; 902 - third centralized flue; 903 - first centralized flue;

[0070] 1000 - Second-level network structure; 1001 - Primary flue gas branch main pipe; 1002 - Secondary flue gas branch main pipe; 1003 - Tertiary flue gas branch main pipe; 1004 - Quaternary flue gas branch main pipe; 1005 - Flue gas-molten salt heat exchanger unit; 1006 - Primary flue gas manifold main pipe; 1007 - Secondary flue gas manifold main pipe; 1008 - Tertiary flue gas manifold main pipe; 1009 - Quaternary flue gas manifold main pipe;

[0071] 2001 - First flue gas-water heat exchanger; 2002 - Second flue gas-water heat exchanger; 2003 - Third flue gas-water heat exchanger; 2004 - Fourth flue gas-water heat exchanger; 2005 - Fifth flue gas-water heat exchanger; 2006 - Sixth flue gas-water heat exchanger; 2007 - Seventh flue gas-water heat exchanger. Detailed Implementation

[0072] To enable those skilled in the art to better understand the technical solutions of this application, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0073] In the embodiments of this application, the terms "first", "second", "third", "fourth", "fifth", etc. are used only for the purpose of distinguishing different components and should not be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated.

[0074] Please refer to Figure 1 , 2 , Figure 1 This is a schematic diagram of one embodiment of the three-dimensional structure of the flue gas driven molten salt heat exchange system of this application; Figure 2 for Figure 1 A schematic diagram of the structure of multiple temperature zone flue sections of a medium-sized boiler.

[0075] The flue gas molten salt heat exchange system in this embodiment includes a boiler 100, a first-stage network structure, a second-stage network structure 1000, and a flue gas mixing device 200. Each part is described in detail below.

[0076] Boiler 100 includes boiler flue and boiler denitrification zone 107 (shown in...) Figure 10 The boiler flue is a broad term encompassing the boiler furnace, the location where combustion takes place in the boiler 100. It typically houses burners for ignition and combustion. After combustion, the materials produce flue gas, which flows downstream into the flue. This flue contains relatively high-temperature flue gas. To utilize the heat from the flue gas, multiple stages of heating surfaces, such as superheaters and reheaters, are typically installed within the flue to absorb heat from the flue gas within the boiler 100, causing the flue gas temperature to gradually decrease along the flow direction. Downstream of the boiler flue is the boiler denitrification zone 107, equipped with a denitrification device for treating the flue gas to reduce its nitrogen content.

[0077] Please continue to refer to Figure 1 、 2 , and understand in conjunction with Figures 3 to 5 , Figure 3 is Figure 2 a schematic diagram of a first type of smoke extraction port distribution structure in a temperature zone flue section of the boiler; Figure 4 is Figure 2 a schematic diagram of a second type of smoke extraction port distribution structure in a temperature zone flue section of the boiler; Figure 5 is Figure 2 a schematic diagram of a third type of smoke extraction port distribution structure in a temperature zone flue section of the boiler.

[0078] Figure 3 In the boiler of the present application, two smoke extraction ports are arranged symmetrically on opposite furnace walls, compared with the arrangement of only one smoke extraction port, Figure 3 the area of the single smoke extraction port is reduced, and the smoke is extracted symmetrically, which is beneficial to maintaining the uniformity of the flue gas flow field in the boiler. Figure 4 In the boiler of the present application, smoke is extracted from four side walls of the flue, compared with Figure 3 the arrangement, the area of the single smoke extraction port can be further reduced, and the flue gas flow field in the boiler is more uniform and stable. Figure 5 In the boiler of the present application, smoke is extracted from two adjacent side walls, and the total number of smoke extraction ports is four, which is beneficial to reducing the size of the single smoke extraction port; and the adjacent side wall extraction is beneficial to the arrangement of the smoke extraction flue network structure, and the structure is compact.

[0079] The flue gas molten salt heat exchange system in the embodiment includes a first level network structure, the first level network structure includes at least two smoke extraction flues 300, the smoke extraction flues 300 are connected to the furnace wall of the boiler 100 to extract part of the flue gas in the boiler 100, the furnace wall of the boiler 100 is provided with a smoke extraction port 106 to realize the communication between the smoke extraction flue 300 and the inside of the boiler 100, Figures 3 to 5 is shown. In addition, each smoke extraction flue 300 is provided with a flow adjusting component 402, for example, an adjusting baffle shown in Figure 1 , for adjusting the flow of flue gas in each smoke extraction flue 300. Since at least two smoke extraction flues 300 are provided, flue gas can be extracted from at least two places in the boiler 100. The flue gas extracted by the plurality of smoke extraction flues 300 enters the flue gas mixing device 200 for mixing, and the extraction of flue gas by the plurality of smoke extraction flues 300 is beneficial to the flow of the extracted flue gas.

[0080] In detail, the flue of the boiler 100 can be divided into different temperature zone flue sections according to different temperatures, for example, the boiler 100 can be divided into a high-temperature zone flue section, a medium-temperature zone flue section, and a low-temperature zone flue section. The boiler 100 is provided with at least two smoke taking openings 106, one smoke taking opening 106 is connected with one smoke taking flue 300, and the at least two smoke taking openings 106 are located in different temperature zone flue sections, so that at least two kinds of flue gas with different smoke temperatures can be extracted, and the flow adjusting component 402 can also adjust the flue gas flow in each smoke taking flue 300, thereby adjusting the proportion of flue gas with different smoke temperatures. In this way, on the one hand, by changing the mixing ratio of the multiple flue gas taken by the smoke taking flue 300, the flue gas temperature can be adjusted in a large range, the influence of the flue gas temperature fluctuation of the boiler 100 on the flue gas molten salt heat exchange system can be reduced, the flue gas temperature is more stable, and the operation safety and flexibility of the flue gas molten salt heat exchange system are improved. On the other hand, during startup, lower temperature flue gas can be first introduced to preheat the flue gas molten salt heat exchanger, thereby realizing safe startup of the flue gas molten salt heat exchange system.

[0081] For example, each smoke taking opening 106 is located in the medium-temperature zone flue section or the low-temperature zone flue section, and each smoke taking opening 106 is connected with one smoke taking flue 300, so that the smoke taking flue 300 can take smoke from the medium-temperature zone flue section, take smoke from the low-temperature zone flue section, or take smoke from the high-temperature zone flue section and the low-temperature zone flue section at the same time.

[0082] Figure 2 In the embodiment, the high-temperature zone flue section includes a first temperature zone flue section 101, and the first temperature zone flue section 101 is a furnace and flue section with flue gas temperature higher than 900°C.

[0083] The medium-temperature zone flue section includes a second temperature zone flue section 102 and a third temperature zone flue section 103, the flue gas temperature of the second temperature zone flue section 102 ranges from 700°C to 900°C, and the flue gas temperature of the third temperature zone flue section 103 ranges from 500°C to 700°C.

[0084] The low-temperature zone flue section includes a fourth temperature zone flue section 104 and a fifth temperature zone flue section 105, the flue gas temperature of the fourth temperature zone flue section 104 ranges from 400°C to 500°C, and the flue gas temperature of the fifth temperature zone flue section 105 ranges from 300°C to 400°C.

[0085] The first temperature zone flue section 101, the second temperature zone flue section 102, the third temperature zone flue section 103, the fourth temperature zone flue section 104, and the fifth temperature zone flue section 105 are sequentially connected.

[0086] At this time, the second temperature zone flue section 102, the third temperature zone flue section 103, the fourth temperature zone flue section 104, and the fifth temperature zone flue section 105 can be provided with smoke taking openings 106 in at least two of them,Figure 1 The middle boiler 100 is connected with five smoke taking flues 300, and five smoke taking openings 106 are arranged correspondingly.

[0087] The multiple smoke flues 300 take out multiple smoke gas, which is mixed in the smoke gas mixing device 200, and can be premixed before entering the smoke gas mixing device 200.

[0088] Continuing to refer to Figure 1 The first level network structure in this embodiment further includes a first centralized flue 903, the inlet of the first centralized flue 903 is connected with each smoke taking flue 300, which can be directly connected or indirectly connected, and the outlet of the first centralized flue 903 is connected with the inlet of the smoke gas mixing device 200. That is, the multiple smoke flues 300 take out multiple smoke gas, which is premixed in the first centralized flue 903 and then further mixed in the smoke gas mixing device 200. The multiple smoke flues 300 are the roots, and the first centralized flue 903 is the trunk, so as to converge the multiple smoke gas into the first centralized flue 903. Therefore, the flow cross-sectional dimension of the first centralized flue 903 in this embodiment is set to be larger than the flow cross-sectional dimension of the smoke taking flue 300, which refers to the diameter or the side length, and can represent the flow cross-sectional area, so as to make the smoke gas amount taken out and the flow cross-sectional dimension match as much as possible, so that the smoke gas remains in a relatively stable flow rate state.

[0089] The first level network structure in this embodiment further includes at least one second centralized flue 901, the inlet of the second centralized flue 901 is connected with at least two smoke taking flues 300, and the outlet of the second centralized flue 901 is connected with the inlet of the first centralized flue 903, which can be directly connected or indirectly connected. That is, part of the smoke taking flues 300 are indirectly connected through the second centralized flue 901 and the first centralized flue 903, that is, the multiple smoke gas is first converged in a small range through the second centralized flue 901 and then further converged into the first centralized flue 903. At this time, the flow cross-sectional dimension of the second centralized flue 901 is larger than the flow cross-sectional dimension of the smoke taking flue 300 and smaller than the flow cross-sectional dimension of the first centralized flue 903, which is not described herein again.

[0090] In some embodiments, the first level network structure further includes at least one third centralized flue 902, the inlet of the third centralized flue 902 is connected with the outlet of the second centralized flue 901 and at least one smoke taking flue 300, and the outlet of the third centralized flue 902 is connected with the inlet of the first centralized flue 903. As Figure 1As shown, two of the five flue gas ducts 300 are connected to a second centralized flue 901, and the second centralized flue 901 is connected to a third centralized flue 902, and the remaining three flue gas ducts 300 are directly connected to the third centralized flue 902, and the flue gas is gathered in the third centralized flue 902 and then enters the first centralized flue 903. The third centralized flue 902 facilitates the connection of different flues, Figure 1 In this embodiment, the third centralized flue 902 is a variable-diameter structure with a gradually changing radial dimension, and the end with a smaller radial dimension is connected to the second centralized flue 901, and the remaining three flue gas ducts 300 are directly connected to the side wall of the third centralized flue 902.

[0091] At this time, the flow cross-sectional dimension of the third centralized flue 902 is larger than the flow cross-sectional dimension of the flue gas duct 300, and smaller than the flow cross-sectional dimension of the first centralized flue 903. The purpose of the above-mentioned flow cross-sectional dimension setting is the same, and will not be repeated here.

[0092] The first-stage network structure is described in detail above, and now the flue gas mixing device 200 is described. As shown, Figure 6 Figure 6 The flue gas mixing device 200 of the first structure is shown in the figure. Figure 1

[0093] The flue gas mixing device 200 in this embodiment specifically includes a main cylinder 201, a variable-diameter cylinder 202, an inlet flue 203, and an exhaust cylinder 204. In detail, the main cylinder 201 is generally cylindrical, the variable-diameter cylinder 202 is located below the main cylinder 201, the variable-diameter cylinder 202 is tapered or substantially tapered in structure with a gradually decreasing diameter from top to bottom, and the main cylinder 201 and the variable-diameter cylinder 202 can be provided with a wear-resistant layer, an inner thermal insulation layer, and / or an outer thermal insulation layer (not shown in the figure). The multiple layers of the inner thermal insulation layer, the wear-resistant layer, and the outer thermal insulation layer can be achieved by selection of the thickness and type of the material, which is not limited and is selected according to specific conditions. For example, the main cylinder 201 and the variable-diameter cylinder 202 are both carbon steel bodies, and double-layer inner linings are provided inside, which are wear-resistant castable and thermal insulation material from inside to outside.

[0094] The inlet flue 203 of the flue gas mixing device 200 is connected to the main cylinder 201 in a tangential manner, and the inlet direction is tangent to the inner wall of the main cylinder 201. The diameter of the exhaust cylinder 204 is smaller than that of the main cylinder 201, and the exhaust cylinder 204 is coaxially arranged with the main cylinder 201. The lower end of the exhaust cylinder 204 penetrates the upper end surface of the main cylinder 201 and extends into the main cylinder 201 by a certain distance.

[0095] As shown, Figure 6 ​​As shown, when the flue gas introduced by the plurality of flue gas taking flues 300 from the boiler 100 enters the flue gas mixing device 200 from the inlet flue 203, the flue gas can enter the main cylinder 201 in a tangential direction and then flow in the main cylinder 201 in a rotary manner, so as to increase the sufficiency of multi-path flue gas mixing. In addition, since the diameter of the variable-diameter cylinder 202 gradually decreases, after the flue gas flows in the main cylinder 201 and then enters the variable-diameter cylinder 202, the flue gas is compressed and then changes direction to flow upward, and finally flows out from the upper exhaust cylinder 204 and enters the downstream second-level network structure 1000, Figure 1 The specific layout of the first connecting flue 801 connecting the second-level network structure 1000 and the flue gas mixing device 200 can be designed according to the connection requirements. The first connecting flue 801 is not provided with a merging point with other flues, so as to ensure the reliability of the flue gas flowing to the second-level network structure 1000.

[0096] In the flue gas mixing device 200 in this embodiment, the flue gas enters and then flows downward and upward. In addition to further increasing the mixing effect, the dust in the flue gas is also separated in the variable-diameter cylinder 202 and then flows out from the lower part of the variable-diameter cylinder 202. That is, the purpose of arranging the variable-diameter cylinder 202 can achieve the separation of the dust in the flue gas, so as to achieve the purpose of purification, so that the relatively clean flue gas enters the flue gas molten salt heat exchanger, so as to reduce the abrasion of the pipeline for the flow of the molten salt in the flue gas molten salt heat exchanger, prolong the service life, and improve the heat exchange efficiency. It can be known that only the main cylinder 201 is arranged to perform spiral mixing, and the flue gas mixing device 200 can also be other types of mixers, such as a plurality of orifice plates arranged in the flue gas mixing device 200 to perform uniform flow mixing.

[0097] The flue gas mixing device 200 includes at least two inlet flues 203, Figure 6 In this embodiment, three inlet flues 203 are shown. At this time, when the partial flue gas taking flues 300 are connected to different temperature zone flue sections, the flue gas taking flues 300 connected to the same temperature zone flue section are connected to one inlet flue 203, that is, the flue gas entering different inlet flues 203 has different temperatures. The flue gas mixing device 200 in this embodiment includes the main cylinder 201, the variable-diameter cylinder 202, and the exhaust cylinder 204, and the structures and functions of each part can be understood with reference to the above, Figure 6 Each inlet flue 203 is tangent to the main cylinder 201, so that the flue gas can enter the main cylinder 201 in a tangential direction, which is beneficial to the connection of the flue gas taking flues 300 with different flue gas temperatures and the main cylinder 201, meets the multi-path inlet requirement, and is flexible in the arrangement direction of the inlet of the inlet flue 203, so as to facilitate the arrangement of the flue gas taking flues 300. In addition, it is also beneficial to the uniform mixing of the flue gas, and can also reduce the flue resistance, facilitate the control of the ash accumulation, and also achieve the separation of the dust. The plurality of inlet flues 203 can be uniformly distributed along the circumference of the main cylinder 201, so as to more uniformly mix the flue gas.

[0098] Please refer to Figure 7 , Figure 7 for Figure 1 the second structure diagram of the flue gas mixing device 200.

[0099] The flue gas mixing device 200 includes at least two inlet flues 203, Figure 7 two inlet flues 203 are schematically shown, and the flue gas taking flue 300 and one inlet flue 203 can also be connected, that is, the flue gas entering different inlet flues 203 has different temperatures. The flue gas mixing device 200 in this embodiment also includes the main cylinder 201, the variable-diameter cylinder 202, and the exhaust cylinder 204. Each inlet flue 203 is tangent to the main cylinder 201, and the flue gas enters the main cylinder 201 in a tangential direction. Similarly, this arrangement can also achieve similar effects as the arrangement in Figure 6 . Figure 7 The multiple inlet flues 203 in are distributed along the height direction of the main cylinder 201, providing another arrangement to adapt to the arrangement of different flue gas taking flues 300.

[0100] Figure 8 Now looking at the second-level network structure 1000 in the embodiments of the present application, as shown in Figure 8 , which is a schematic diagram of one second-level network structure 1000 in the embodiments of the present application.

[0101] The second-level network structure 1000 includes a flue gas molten salt heat exchanger, which includes a plurality of flue gas-molten salt heat exchange units 1005. The second-level network structure 1000 also includes multiple stages of flue gas shunt mother pipes that are sequentially shunted in the flue gas flow direction. The multiple stages of flue gas shunt mother pipes are sequentially shunted one by one in the flue gas flow direction. In the flue gas flow direction, the flue gas shunt mother pipe located at the most upstream is the primary flue gas shunt mother pipe or the first-stage flue gas shunt mother pipe 1001, and the flue gas shunt mother pipe located at the most downstream is the final flue gas shunt mother pipe. In the flue gas flow direction, the number of flue gas shunt mother pipes at each stage gradually increases, that is, each flue gas shunt mother pipe is connected to multiple flue gas shunt mother pipes at the next stage to distribute flue gas to the multiple flue gas shunt mother pipes at the next stage.

[0102] Figure 8 In the embodiment, a total of four stages of flue gas shunt mother pipes are provided, which are the first-stage flue gas shunt mother pipe 1001, the second-stage flue gas shunt mother pipe 1002, the third-stage flue gas shunt mother pipe 1003, and the fourth-stage flue gas shunt mother pipe 1004, which is also the final flue gas shunt mother pipe. Of course, more stages of flue gas shunt mother pipes can also be provided, and the multiple stages of flue gas shunt mother pipes referred to in the present application refer to at least two stages.

[0103] The primary flue gas diversion header 1001 is connected to at least two secondary flue gas diversion headers 1002, the secondary flue gas diversion headers 1002 are connected to at least two tertiary flue gas diversion headers 1003, and the tertiary flue gas diversion headers 1003 are connected to at least two quaternary flue gas diversion headers 1004. Let N be the number of stages of the flue gas diversion headers, and M be the number of next-stage flue gas diversion headers connected to each header. Then, after the flue gas flow path is diverted through the second-stage network structure 1000, the number of parallel flue gas flow paths is (N-1)×M. Figure 8 In this process, each flue gas branch header is connected to three next-level flue gas branch headers, so the final number of flue gas flow paths is (3-1)×3=9, and correspondingly 9 flue gas-molten salt heat exchange units 1005 are set up.

[0104] In this embodiment, the flue gas diversion header and the flue gas-molten salt heat exchange unit 1005 are arranged in an array. For example... Figure 8 As shown, the primary flue gas diversion header 1001 is arranged vertically downwards, while the secondary and tertiary flue gas diversion headers 1002 and 1003 are both arranged horizontally and perpendicular to each other; the quaternary flue gas diversion header 1004 is arranged vertically downwards; and the flue gas-molten salt heat exchange unit 1005 is correspondingly arranged vertically between the tertiary flue gas diversion header 1003 and the tertiary flue gas junction header 1008. This arrangement is based on structured design theory, which facilitates flue gas flow, reduces flow resistance, and has a relatively compact structure, making it easy to lay out.

[0105] The second-level network structure 1000 in this embodiment also includes a multi-stage flue gas manifold that merges sequentially along the flue gas flow direction. The multi-stage flue gas manifold merges one stage at a time along the flue gas flow direction. Along the flue gas flow direction, the downstream flue gas manifold is either the final-stage flue gas manifold or the first-stage flue gas manifold 1006, while the upstream flue gas manifold is the primary flue gas manifold. Along the flue gas flow direction, the number of flue gas manifolds gradually decreases at each stage; that is, multiple flue gas branching manifolds connect to one flue gas branching manifold at the next stage to collect the flue gas to the next stage.

[0106] Figure 8 The system comprises four levels of flue gas manifolds: Level 1 (1006), Level 2 (1007), Level 3 (1008), and Level 4 (1009). Level 1 (1006) is the final level flue gas manifold. More levels of flue gas manifolds can be installed; the term "multi-level flue gas manifold" in this application refers to at least two levels.

[0107] The primary flue gas manifold 1006 is connected with at least two secondary flue gas manifolds 1007, the secondary flue gas manifold 1007 is connected with at least two tertiary flue gas manifolds 1008, and the tertiary flue gas manifold 1008 is connected with at least two quaternary flue gas manifolds 1009. The number of flue gas manifolds is defined as P, and the number of the upper level flue gas manifolds connected with each flue gas manifold is Q. After the flue gas flow passes through the second level network structure 1000, the flue gas flow is finally collected into one flue gas flow. In this embodiment, the number and grading ratio of the flue gas distribution manifolds and the flue gas distribution manifolds are the same, the ratio of the upper level and the lower level of the flue gas distribution manifold is one to three, and the ratio of the upper level and the lower level of the flue gas manifold is three to one, which is beneficial to the uniform flow of the flue gas manifold. It can be seen that the arrangement of the flue gas distribution manifold and the flue gas manifold is not limited to this, and the grading ratio of the adjacent two levels can also be different. For example, for the flue gas distribution manifold, it can be divided into three and then divided into four, and it is not limited to always being divided according to the ratio of one to three, and the flue gas manifold is the same, which will not be described here.

[0108] The array arrangement of the flue gas distribution manifold is the same as that of the flue gas distribution manifold. The primary flue gas manifold 1006 and the primary flue gas distribution manifold 1001 are arranged in parallel, the secondary flue gas manifold 1007 and the secondary flue gas distribution manifold 1002 are arranged in parallel, the tertiary flue gas manifold 1008 and the tertiary flue gas distribution manifold 1003 are arranged in parallel, and the quaternary flue gas manifold 1009 and the quaternary flue gas distribution manifold 1004 are arranged in parallel. In this way, the flue gas distribution manifold and the flue gas manifold are arranged in an array, and the structure is compact.

[0109] In this embodiment, the outlet of the last flue gas distribution manifold is in communication with the flue gas inlet of the flue gas-molten salt heat exchange unit 1005, and the inlet of the primary flue gas manifold is in communication with the flue gas outlet of the flue gas-molten salt heat exchange unit 1005. Figure 8 As shown in the figure, the outlet of the quaternary flue gas distribution manifold 1004 is in communication with the flue gas inlet of one flue gas-molten salt heat exchange unit 1005, and the inlet of the quaternary flue gas manifold 1009 is in communication with the flue gas outlet of the flue gas-molten salt heat exchange unit 1005. In this way, the flue gas flowing out of the flue gas mixing device 200 is multi-staged after being distributed, and then enters the plurality of flue gas-molten salt heat exchange units 1005 for heat exchange, and then is gradually collected into the last flue gas manifold, and can be returned to the boiler 100 through the return flue 500.

[0110] At this time, the flue gas-molten salt heat exchanger can include a plurality of groups of heat exchanger modules, each group of heat exchanger modules includes at least two flue gas-molten salt heat exchange units 1005, Figure 8Each three flue gas-molten salt heat exchange units 1005 is a group of heat exchanger modules, the inlets of the flue gas-molten salt heat exchange units 1005 of the same group of heat exchanger modules are connected to the same three-stage flue gas shunt manifold 1003 through the four-stage flue gas shunt manifold 1004, and the outlets of the flue gas-molten salt heat exchange units 1005 of the same group of heat exchanger modules are connected to the same three-stage flue gas shunt manifold 1008 through the four-stage flue gas shunt manifold 1009, which is compact and reliable.

[0111] In this embodiment, the flow cross-sectional size of the flue gas shunt manifold can be set to be greater than that of the next stage, and the flow cross-sectional size of the flue gas shunt manifold can be set to be greater than that of the flue gas shunt manifold of the previous stage, that is, the flow cross-sectional size of the multi-stage flue gas shunt manifold gradually decreases along the flue gas flow direction; the flow cross-sectional size of the multi-stage flue gas shunt manifold gradually increases along the flue gas flow direction. The same as the setting principle of the above-mentioned centralized flue, it is also to make the flow cross-sectional size and the flue gas flow as much as possible.

[0112] It can be seen that the three-dimensional structure of the flue gas-molten salt heat exchange system driven by the boiler flue gas in this application has the following technical effects:

[0113] 1. The use of different sizes of hierarchical structure effectively reduces the flow resistance of the flue system.

[0114] In this embodiment, the flue gas flow path for flue gas extraction and return to the boiler 100 is optimally designed to form a multi-stage flow network, which can reduce the flow resistance. Specifically, the first-stage network structure is used to realize the collection of the flue gas taken from the boiler 100 through the flue gas taking flue 300 to the flue gas mixing device 200, and the second-stage network structure 1000 is used to realize the collection of the flue gas after being dispersed from the centralized flue of the flue gas mixing device 200 to multiple flue gas-molten salt heat exchange units. It can be seen that the flue gas flow path of the above-mentioned three-dimensional structure of the flue gas-molten salt heat exchange system is a multi-stage flow network, which makes the flue gas flow more regular and organized. In actual engineering, the flow resistance can be further reduced by further optimizing the pipe size design.

[0115] 2. The flue gas temperature can be adjusted, which is beneficial to the safe and stable operation and start-stop of the flue gas-molten salt heat exchange system.

[0116] In this flue gas-molten salt heat exchange system, flue gas can be taken from two or more temperature zone flue sections of the boiler 100 as a heat source. On the one hand, by changing the mixing ratio of the multiple flue gas taken by the flue gas taking flue 300, the flue gas temperature can be adjusted in a large range, which can reduce the influence of the flue gas temperature fluctuation of the boiler 100 on the flue gas-molten salt heat exchange system, make the flue gas temperature more stable and moderate, and improve the operation safety and flexibility of the flue gas-molten salt heat exchange system. On the other hand, during start-up, lower temperature flue gas can be first introduced to preheat the flue gas-molten salt heat exchanger, realizing the safe start-up of the flue gas-molten salt heat exchange system.

[0117] 3. The flue gas temperature field is uniform, which is beneficial to realize the safety of the molten salt operation of the flue gas-molten salt heat exchange system.

[0118] The flue gas-molten salt heat exchange system comprises a flue gas mixing device 200. The flue gas mixing device 200 can mix multiple flue gases, so that the flue gas enters the flue gas-molten salt heat exchanger in a more uniform manner, thereby improving the safety of the molten salt operation. In particular, when the temperatures of the multiple flue gases are different, the flue gas mixing device 200 can mix the flue gases with different temperatures into one flue gas with a smaller temperature deviation, which is used as the inlet flue gas of the flue gas-molten salt heat exchange unit 1005, thereby effectively avoiding the local over-temperature decomposition of the molten salt and ensuring the safety of the molten salt operation.

[0119] 4. The dispersed flue gas extraction is beneficial to improve the safety of the boiler.

[0120] The flue gas extraction flue 300 extracts flue gas from the boiler 100. The boiler 100 is connected with multiple flue gas extraction flues 300, so that the flue gas extraction port 106 has the characteristics of small size and large quantity, thereby effectively reducing the flue gas extraction flow of the single flue gas extraction port 106, reducing the disturbance to the flue gas flow field in the boiler 100, and improving the safety of the boiler operation. Moreover, the flue gas extraction port 106 can be distributed in different temperature zone flue sections (representing different flue gas temperature levels) of the boiler 100. The flue gas extraction port 106 can also be arranged at different positions in each temperature zone flue section, that is, at least two flue gas extraction ports 106 can be arranged in one temperature zone flue section. In this way, the flue gas extraction port 106 is more dispersedly arranged, thereby improving the disturbance of the flue gas extraction port 106 to the flue gas flow field in the boiler 100.

[0121] Please refer to Figure 9 , Figure 9 which is a schematic view of a second embodiment of the three-dimensional structure of the flue gas-molten salt heat exchange system driven by the boiler flue gas of the present application. Figure 9 The structure shown in the figure is basically the same as Figure 1 , and the difference lies in the different arrangement positions of the flue gas extraction port 106.

[0122] In this embodiment, the boiler 100 is a π-type furnace. Specifically, the boiler 100 can be a coal-fired π-type furnace with a capacity of 350 MW. The boiler 100 is divided into different temperature zones according to the flue gas temperature, which is the same as Figure 1 the embodiment, and also comprises a first temperature zone flue section 101, a second temperature zone flue section 102, a third temperature zone flue section 103, a fourth temperature zone flue section 104, and a fifth temperature zone flue section 105.

[0123] The flue gas molten salt heat exchange system in the embodiment includes five flue gas taking flues, namely, a first flue gas taking flue 301, a second flue gas taking flue 302, a third flue gas taking flue 303, a fourth flue gas taking flue 304, and a fifth flue gas taking flue 305. The first flue gas taking flue 301, the second flue gas taking flue 302, and the third flue gas taking flue 303 take flue gas from the second temperature zone flue section 102, and the fourth flue gas taking flue 304 and the fifth flue gas taking flue 305 take flue gas from the fifth temperature zone flue section 105.

[0124] Suppose that the molten salt in the flue gas molten salt heat exchanger 1000 specifically adopts binary nitrate (i.e., solar salt), the cold salt temperature is 300°C, and the hot salt temperature is 500°C. Suppose that the flue gas molten salt heat exchanger is under the design condition (at this time, the boiler is under 75% THA load), the thermal power is 15 MW, the inlet flue gas temperature is 600°C, and the outlet flue gas temperature is 360°C. According to the calculation under the above conditions, the flue gas molten salt heat exchanger needs to extract a total flue gas flow of 193741 kg / h under the rated condition.

[0125] Under the condition that the boiler is under 75% THA load, suppose that the flue gas taking temperature of the first flue gas taking flue 301, the second flue gas taking flue 302, and the third flue gas taking flue 303 is 750°C, and the flue gas taking temperature of the fourth flue gas taking flue 304 and the fifth flue gas taking flue 305 is 330°C. According to the calculation, the flue gas flow taken from the second temperature zone flue section 102 is 117092 kg / h, and the flue gas flow taken from the fifth temperature zone flue section 105 is 76649 kg / h. Suppose that the flue gas flow in the flue gas taking port 106 in the same temperature zone flue section is evenly distributed, and the flue gas design flow velocity in the flue is 14-18 m / s according to the industry experience value, the flow-through cross-sectional size of each flue gas taking flue 300 can be calculated: the first flue gas taking flue 301, the second flue gas taking flue 302, and the third flue gas taking flue 303 are square flues, and the side length is 1.3 m; the fourth flue gas taking flue 304 and the fifth flue gas taking flue 305 are circular flues, and the diameter is 1.3 m. At the same time, the flow-through cross-sectional size of other flues can be calculated: the inlet cross section of the flue gas mixing device 200 is rectangular, the outlet cross section is circular, and the diameter is 3.4 m; the diameters of the primary flue gas shunt main pipe 1001, the secondary flue gas shunt main pipe 1002, and the tertiary flue gas shunt main pipe 1003 are 3.4 m, 2.4 m, and 1.7 m respectively, and it can be seen that the flow-through cross-sectional size of the flue gas shunt main pipe gradually decreases along the flue gas flow direction; the back flue 500 is a square flue, and the side length is 2.6 m.

[0126] From the above size results, it can be seen that the flue gas taking flues 300 in the first level network structure are small in size and large in number, and converge to the flue gas mixing device 200; the flue sizes in the second level network structure 1000 gradually decrease and then gradually increase, and converge to the whole; the size span of the three-dimensional structured component formed by the two level network structures is about 1 m to 3 m.

[0127] The branch design of the first network structure reduces the size of the smoke taking port 106, improves the safety of smoke taking, and has little effect on the internal flow field of the boiler 100. If a single smoke taking port is used, the length of the side of the smoke taking port in the second temperature zone flue section 102 will need to reach 2.9 m, and the diameter of the smoke taking port in the fifth temperature zone flue section 105 will need to reach 1.9 m. The smoke taking by the smoke taking ports with the above two sizes will cause serious deflection of the flue gas flow field of the boiler, resulting in uneven heat transfer of the heating surface (the flue gas-water heat exchanger inside the boiler 100), which is easy to cause over-temperature pipe explosion and seriously affects the safety of the boiler. In comparison, the multiple smoke taking flues 300 in the embodiment of the application take smoke, which greatly reduces the size of the smoke taking port 106 and improves the safety of the boiler operation.

[0128] It should be noted that the above flue cross-section values are selected according to the empirical value of the flue gas flow rate. It can be understood that in actual application, the flue gas flow resistance can be combined for further optimization design to obtain the design size with the best comprehensive performance, so as to better improve the flow characteristics of the flue gas.

[0129] Please continue to refer to Figure 1 The flue gas molten salt heat exchange system in the embodiment of the application further includes a return flue 500, a first connecting flue 801, and a second connecting flue 802. The flue gas outlet of the flue gas mixing device 200 is connected to a primary flue gas shunt manifold 1001 in the second network structure 1000 through the first connecting flue 801. The primary flue gas shunt manifold 1006 in the second network structure 1000 is connected to the return flue 500 through the second connecting flue 802. The return flue 500 is connected to the boiler 100, Figure 1 The return flue 500 is connected upstream of the boiler blowdown zone of the boiler 100. The boiler 100 is provided with a return port 107a (shown in Figure 10 ) for connecting the return flue 500. The return flue 500 is further provided with an induced draft fan 600. The induced draft fan 600 can be arranged in the return flue 500 or between the return flue 500 and the second network structure 1000, as shown in Figure 1 The induced draft fan 600 is specifically arranged at the position where the return flue 500 and the second connecting flue 802 are connected. The induced draft fan 600 can provide power to ensure that the flue gas can flow from the smoke taking port 106 to the return port 107a.

[0130] In some embodiments, as mentioned above, multiple smoke outlets 106 can be arranged in the same temperature zone flue section of the boiler 100, which is conducive to reducing the influence of smoke extraction on the flow field of the flue gas in the boiler 100. Similarly, the smoke return port 107a can also be arranged in multiple, which can make the flue gas returned to the boiler 100 mix more uniformly with the flue gas in the flue of the boiler 100, and is conducive to the safe and efficient operation of the heat exchanger or denitration device downstream of the smoke return port 107a in the boiler 100. When multiple smoke outlets 106 or multiple smoke return ports 107a are arranged, in the present embodiment, a flue gas rectifier can be arranged at the smoke outlet 106 or the smoke return port 107a, so that the connection of the multiple smoke outlets 106 or the multiple smoke return ports 107a with the smoke extraction flue 300 has the effect of uniform flow field and small flue gas resistance. At this time, the multiple smoke outlets 106 arranged in the same temperature zone flue section can be connected to the same smoke extraction flue 300 through the flue gas rectifier, and the multiple smoke return ports 107a can be connected to the same smoke return flue 500 through the flue gas rectifier.

[0131] In addition, each smoke extraction flue 300 in the present embodiment can also be provided with a shut-off baffle 401 for shutting off the flue gas, which only has an on-off function and can respond faster to the requirements of opening and closing. In cooperation with the flow regulating component 402, the control is more convenient and fast. It can be seen that only the flow regulating component 402 can be arranged, and the adjustment stroke of the flow regulating component 402 can be between full opening and full closing. The smoke extraction flue 300 and the smoke return flue 500 can also be provided with an expansion joint, which is arranged at the position where the smoke extraction flue 300 is connected to the boiler 100 and at the position where the smoke return flue 500 is connected to the boiler 100. As long as it can adapt to the deformation caused by the temperature difference, the reliability of the connection between the smoke extraction flue 300, the smoke return flue 500 and the boiler 100 can be ensured.

[0132] The flue gas molten salt heat exchange system in the present embodiment also comprises a flow meter 404 arranged in the smoke return flue 500 for detecting the flow of the flue gas in the smoke return flue 500, which is conducive to obtaining the flue gas flow in the second network structure 1000 in real time, so as to adjust the flue gas flow according to the actual demand. It can be seen that the flow meter 404 can also be arranged in the first connecting flue 801 or the second connecting flue 802, and the total flue gas flow through the second network structure 1000 can be detected. The bottom of the second connecting flue 802 can be provided with a dust hopper for collecting the dust by gravity settling, improving the cleanliness of the flue gas returned to the smoke return flue 500, and reducing the damage of the dust to the induced draft fan 600.

[0133] Please continue to refer to Figure 1The flue gas molten salt heat exchange system further comprises at least one temperature detection point, and a temperature sensor can be installed at the position of the temperature detection point. The temperature sensor can detect the temperature of the flue gas entering the flue gas-molten salt heat exchange unit 1005, so as to timely grasp the flue gas temperature, and adjust the mixing ratio of the flue gas according to the heat exchange requirement of the molten salt, for example, if the temperature is low, the proportion of flue gas with relatively high temperature can be increased or the proportion of flue gas with relatively low temperature can be reduced, and if the temperature is high, the proportion of flue gas with relatively low temperature can be increased or the proportion of flue gas with relatively high temperature can be increased. The number of temperature detection points can be multiple.

[0134] It is worth noting that the flue gas molten salt heat exchange system in this embodiment also has the effect of “coupling” flue gas molten salt heat exchange and boiler operation.

[0135] In combination with Figure 10 understand, Figure 10 FIG. 3 is a schematic view of a third embodiment of a three-dimensional structure of a boiler flue gas driven flue gas molten salt heat exchange system according to the present application, Figure 10 and Figure 1 、 9 The three-dimensional structure of the flue gas molten salt heat exchanger system in the above-mentioned embodiments is basically the same, and the difference lies in that three flue gas taking flues 300 are arranged.

[0136] Still taking the boiler 100 as a π-shaped furnace as an example, specifically, the boiler 100 can be a coal-fired π-shaped furnace with a capacity of 350 MW. In this embodiment, the second temperature zone flue section 102, the third temperature zone flue section 103, and the fourth temperature zone flue section 104 are all connected with the flue gas taking flues 300, and the flue gas taking ports communicated by the flue gas taking flues 300 are located at the middle sections of the temperature flue sections. In this embodiment, at least one flue gas-water heat exchanger is arranged in each temperature zone flue section, for example, the first flue gas-water heat exchanger 2001 is arranged in the first temperature zone flue section 101, the second flue gas-water heat exchanger 2002 and the third flue gas-water heat exchanger 2003 are arranged in the second temperature zone flue section 102, the third flue gas-water heat exchanger 2004 and the fourth flue gas-water heat exchanger 2005 are arranged in the third temperature zone flue section 103, the fifth flue gas-water heat exchanger 2006 is arranged in the fourth temperature zone flue section 104, and the sixth flue gas-water heat exchanger 2007 is arranged in the fifth temperature zone flue section 105. The above-mentioned flue gas-water heat exchangers can absorb the heat of the flue gas in the boiler 100 to heat the steam or water of the boiler 100. The above-mentioned flue gas-water heat exchangers are only schematic, and each temperature zone flue section can also include multiple stages of flue gas-water heat exchangers. The downstream of the fifth temperature zone flue section 105 is connected with the boiler denitration zone 107.

[0137] The flue gas molten salt heat exchange system in this embodiment includes flue gas temperature and flow rate measurement points. Flow meters 404 and thermometers can be installed at the outlets of each flue gas intake duct 300 and the flue gas mixing device 200. During operation, these flue gas temperature and flow rate measurement points can display the local flue gas temperature or flow rate in real time, participate in the control of the flue gas molten salt heat exchange system, and are of great significance to the safe operation of the system.

[0138] Assume that the molten salt in the flue gas molten salt heat exchanger 1000 is a binary nitrate (i.e., solar salt), with a cold salt temperature of 300℃ and a hot salt temperature of 500℃. Taking a boiler at 75% THA load as an example, this embodiment illustrates the impact of the flue gas molten salt heat exchange system on the boiler's heat load distribution. Compare the following three operating conditions:

[0139] (1) Operating Condition 1: When the flue gas molten salt heat exchange system is shut down (i.e., the flue gas does not enter the flue gas molten salt heat exchanger), the total flue gas flow rate of boiler 100 is 968 t / h. The inlet flue gas temperatures of the first temperature zone flue section 101, the second temperature zone flue section 102, the third temperature zone flue section 103, the fourth temperature zone flue section 104, and the fifth temperature zone flue section 105 are 900℃, 700℃, 500℃, 400℃, and 300℃, respectively. The temperature division is the same as... Figure 2 According to the heat balance, the heat loads of the second temperature zone flue section 102, the third temperature zone flue section 103, the fourth temperature zone flue section 104, and the fifth temperature zone flue section 105 are 68.3MW, 65.6MW, 31.6MW, and 30.8MW, respectively; at this time, the heat load of the flue gas molten salt heat exchanger is 0.

[0140] (2) Operating Condition 2: Flue gas molten salt heat exchanger heat storage. Assume that the total flue gas flow rate of boiler 100 is still 968t / h, and the inlet flue gas temperatures of the five temperature zones are still 900℃, 700℃, 500℃, 400℃, and 300℃ respectively. The temperature division is the same as above. Figure 2 At this time, the flue gas temperatures at the intake ports of the first, second, and third flue gas ducts are 800℃, 600℃, and 450℃, respectively. By adjusting the opening of the flow regulating components 402 of the multiple flue gas ducts 300, the flue gas flow rates of the first, second, and third flue gas ducts 301, 302, and 303 are made 97t / h, 145t / h, and 145t / h, respectively. According to the heat balance, the heat loads of the second temperature zone flue section 102, the third temperature zone flue section 103, the fourth temperature zone flue section 104, and the fifth temperature zone flue section 105 are 65.1MW, 54.3MW, 21.4MW, and 18.5MW, respectively. At this time, the inlet flue gas temperature of the flue gas molten salt heat exchanger is approximately 596℃, the flue gas flow rate is 387t / h, the outlet flue gas temperature of the flue gas molten salt heat exchanger is 350℃, and the heat load is 31.3MW.

[0141] (3) Working condition three: flue gas molten salt heat exchanger storage heat, assuming that the total flue gas flow of boiler 100 is still 968 t / h, and the inlet flue gas temperatures of the five temperature zones are still 900℃, 700℃, 500℃, 400℃, and 300℃, respectively, and the temperature division is the same as Figure 2 At this time, the flue gas temperatures at the smoke extraction ports of the first smoke extraction flue 301, the second smoke extraction flue 302, and the third smoke extraction flue 303 are 800℃, 600℃, and 450℃, respectively. By adjusting the opening degree of the flow adjusting component 402 of the plurality of smoke extraction flues 300, the flue gas flows of the first smoke extraction flue 301, the second smoke extraction flue 302, and the third smoke extraction flue 303 are 0 t / h, 100 t / h, and 100 t / h, respectively. According to the heat balance, the heat loads of the second temperature zone flue section 102, the third temperature zone flue section 103, the fourth temperature zone flue section 104, and the fifth temperature zone flue section 105 are 68.5 MW, 62.4 MW, 26.8 MW, and 24.5 MW, respectively. At this time, the inlet flue gas temperature of the flue gas molten salt heat exchanger is approximately 526℃, the flue gas flow is 200 t / h, the outlet flue gas temperature of the flue gas molten salt heat exchanger is 350℃, and the heat load is 14.6 MW.

[0142] Please continue to combine Figure 11 understand, Figure 11 for Figure 10 the heat load distribution diagram of the different temperature zone flue sections of the middle boiler and the flue gas molten salt heat exchange system.

[0143] The heat load distribution of the above three working conditions is shown in the a, b, and c subgraphs of Figure 10 At 75% THA load, the flue gas temperature of the boiler 100 decreases from 900℃ to 300℃, and the total heat load is 196.3 MW. The heat load proportions of each temperature zone flue section of the boiler 100 and the flue gas molten salt heat exchange system are shown in the graph, wherein the flue gas temperature of the first temperature zone flue section 101 is relatively high, the molten salt heat exchange system in this embodiment does not extract flue gas from this flue section, and therefore is not shown in the graph. As can be seen from the graph, the extraction of flue gas by the flue gas molten salt heat exchange system has a significant impact on the heat load distribution of the boiler 100, and the heat load of the temperature zone flue section changes with the change in the extraction flow of each smoke extraction flue 300. During operation, the flue gas amount of each smoke extraction flue 300 can be adjusted according to the heat load demand of each temperature zone flue section of the boiler 100, to realize the auxiliary adjustment of the flue gas molten salt heat exchange system to the boiler 100. At the same time, according to the change in the flue gas amount, the flue gas molten salt heat exchanger 1000 can adjust the heat exchange units put into operation according to the demand, to flexibly respond to variable working conditions.

[0144] The comparison of the above three working conditions illustrates from the principle how the flue gas-molten salt heat exchange system of the coupled boiler 100 extracts multiple flue gases for mixing and heat exchange, and how the flue gas extraction changes the heat load distribution of the boiler 100 to assist the regulation of the boiler 100. Specifically, the following will illustrate how the flue gas-molten salt heat exchange system achieves the above functions through control regulation in actual operation.

[0145] The flue gas-molten salt heat exchange system coupled with the boiler can achieve five functions, including: flue gas and molten salt heat exchange, assisting the boiler 100 in load reduction, assisting the boiler 100 in regulating steam temperature, assisting the boiler 100 in wide load denitration, and assisting the boiler 100 in emergency protection. Among them, the first function is the most basic function, and the second to fifth functions are all auxiliary boiler regulation.

[0146] Please continue to describe the embodiments shown in the drawings. Figure 10 Generally, the flue gas-molten salt heat exchange system is connected with a molten salt tank storage system and a molten salt heat release system to achieve heat storage and heat release under certain conditions, and the released heat can be used for heating or generating steam for power generation. The molten salt tank storage system and the molten salt heat release system are not detailed in the drawings of the present application and will not be described again. The following describes each function and control method:

[0147] (1) Flue gas and molten salt heat exchange: around the flue gas-molten salt heat exchange system, the flue gas in the boiler 100 is extracted to heat the molten salt, aiming to achieve heat storage. The flue gas-molten salt heat exchange system can operate in design conditions or variable conditions. The determination of the design condition parameters of the flue gas-molten salt heat exchange system needs to consider the maximum flue gas temperature allowed by the molten salt, the flue gas amount allowed to be extracted by the boiler 100, and the back smoke temperature meeting the operation of the denitration device, etc. The molten salt heat absorption power is the highest in the design condition. In the variable condition, the flue gas temperature or flow of the boiler 100 changes, and the molten salt can adapt by changing the flow to obtain high-temperature molten salt that meets the outlet temperature requirement, and the molten salt heat absorption power is smaller. During operation, the flue gas flow at the outlet of the flue gas mixing device 200 is adjusted by changing the frequency of the induced draft fan 600, and the flue gas flow of each flue gas extraction flue 300 is adjusted by changing the flue gas flow adjusting device, including the shut-off damper 401 and the flow adjusting component 402 Figure 9

[0148] ​(2) Auxiliary boiler load reduction: when the boiler 100 has a load reduction requirement, the flue gas molten salt heat exchange system is operated at rated load, reducing the heat load of the heat exchanger in the boiler 100, and achieving the requirement of reducing the load of the boiler 100. And with the reduction of the load of the boiler 100, the flue gas temperature of each smoke port 106 gradually decreases, and under the allowable conditions of the boiler 100, the flue gas molten salt heat exchange system can appropriately increase the flue gas extraction amount to maintain a high heat absorption power.

[0149] (3) Auxiliary boiler steam temperature adjustment: the steam temperature refers to the outlet steam temperature of each stage heat exchanger in the boiler 100, for example, the outlet steam temperature of the second flue gas-water heat exchanger. Generally, the boiler 100 has multiple steam temperature adjustment means, such as adjusting the flame center, spraying desuperheating water, etc. However, the traditional adjustment means has certain disadvantages, such as spraying desuperheating water causing large irreversible loss, resulting in the overall efficiency of the system being reduced. After adopting the scheme of the present application, the steam temperature can be adjusted by extracting flue gas.

[0150] Specifically, when the steam temperature of the flue gas-water heat exchanger arranged in any temperature zone flue gas section connected with the smoke flue 300 exceeds the preset value, the flue gas flow of the smoke flue 300 of the temperature zone flue gas section where the flue gas-water heat exchanger is located is increased; the temperature zone flue gas section corresponding to the flue gas-water heat exchanger whose steam temperature exceeds the preset value is defined as temperature zone flue gas section one, and any temperature zone flue gas section connected with the smoke flue 300 downstream of the heat exchange section is defined as temperature zone flue gas section two, then the flue gas flow of the smoke flue 300 corresponding to the temperature zone flue gas section two is also increased. That is, the flue gas of the temperature zone flue gas section one is extracted to reduce the steam temperature of the flue gas-water heat exchanger as soon as possible, and the flue gas of the downstream temperature zone flue gas section two is extracted, that is, the relatively low temperature flue gas is mixed with the relatively high temperature flue gas extracted in large amount, so as to prevent the flue gas temperature from rising too much and causing the molten salt temperature to be too high.

[0151] For example, it is assumed that Figure 9When the temperature of the third flue gas-water heat exchanger 2003 in the second temperature zone flue section 102 is higher than the preset value, the second temperature zone flue section 102 where the third flue gas-water heat exchanger 2003 is located is the temperature zone flue section one, at this time, the flow regulating devices connected to the first smoke taking flue 301, the second smoke taking flue 302 and the third smoke taking flue 303 of the second temperature zone flue section 102 are opened or adjusted to increase the flow, so that part of the flue gas enters the flue gas mixing device 200, the flue gas flow through the third flue gas-water heat exchanger is reduced, the heat load is reduced, the steam temperature is lowered, and the function of adjusting the steam temperature is realized. In this embodiment, the smoke taking flue 300 is also provided with a flow meter 404 and a thermometer to monitor the flow and temperature. At the same time, according to the readings of the flow meters of the first smoke taking flue 301, the second smoke taking flue 302 and the third smoke taking flue 303, if it is judged that the flue gas with relatively high temperature will cause the temperature of the molten salt to be too high, the flow regulating device corresponding to the second temperature zone flue section two downstream of the second temperature zone flue section 102 can be opened to extract flue gas with relatively low temperature, such as opening the fourth smoke taking flue 304 and the fifth smoke taking flue 305 corresponding to the fifth temperature zone flue section 105 to extract flue gas with relatively low temperature, and two routes of flue gas enter the flue gas mixing device 200 to obtain the flue gas temperature allowed by the molten salt, avoid decomposition of the molten salt, and realize safe heat exchange between the flue gas and the molten salt.

[0152] It can be seen that when the flue gas-molten salt heat exchange system is designed, the position of the smoke taking flue 300 and the smoke taking port 106 of the boiler 100 is fully considered according to the requirement of boiler variable condition adjustment, and the smoke taking port 106 can be arranged before the flue gas-water heat exchanger of the boiler where the over-temperature of the pipe wall is prone to occur, i.e. arranged upstream of the flue gas-water heat exchanger. When the boiler 100 is running, the heat load distribution of the boiler can be changed by changing the flue gas flow of the multiple smoke taking ports 106, and the flexibility is improved; in a severe working condition, when the pipe wall of the heating surface of the boiler 100 faces the risk of over-temperature, the flue gas upstream of the heating surface can be extracted in time to reduce the heat load of the heating surface and prevent over-temperature.

[0153] (4) Auxiliary boiler wide load denitration: when the boiler 100 is running at a low load of 30% or less, the inlet flue gas temperature of the denitration device is low due to the decrease of the flue gas temperature in the furnace, which does not meet the requirement of the denitration device. To solve this problem, when the inlet temperature of the denitration device is low, the molten salt in the flue gas-molten salt heat exchanger flows into the molten salt tank connected thereto, so that there is no molten salt remaining in the flue gas-molten salt heat exchanger; according to the flue gas temperature, at least one of the first smoke taking flue 301, the second smoke taking flue 302 and the third smoke taking flue 303 is opened, and the induced draft fan 600 is started to extract the flue gas into the inlet of the denitration device to improve the flue gas temperature entering the denitration device. At this time, the flue gas-molten salt heat exchanger is dry burning, but since the flue gas temperature is low, the metal temperature resistance of the flue gas-molten salt heat exchanger can meet the requirement, i.e. is not affected by dry burning. When the molten salt needs to be stored, the molten salt can be re-injected into each flue gas-molten salt heat exchange unit 1005 of the flue gas-molten salt heat exchanger.

[0154] (5) Auxiliary boiler emergency protection: In conventional boilers, the flue gas-water heat exchanger may have a heat exchange tube wall over-temperature condition, affecting the service life of the heat exchange tube, and in severe cases, causing an explosion tube accident. The scheme of the present application can provide protection for the boiler 100 under harsh working conditions, for example, when Figure 9 When the second flue gas-water heat exchanger in the second temperature zone flue section 102 appears a heating surface over-temperature alarm, the first smoke taking flue 301, the second smoke taking flue 302, and the third smoke taking flue 303 can increase the smoke taking flow, reduce the amount of flue gas in the second temperature zone flue section 102, and timely alleviate the over-temperature condition of the flue gas-water heat exchanger; at the same time, in order to avoid over-temperature of the molten salt, the fourth smoke taking flue 304 and the fifth smoke taking flue 305 can be simultaneously increased to maintain the inlet flue gas temperature of the flue gas molten salt heat exchanger 1000 within an appropriate range.

[0155] The above specifically describes the functions that can be achieved by the flue gas molten salt heat exchange system in the embodiments of the present application, and the implementation process of achieving these functions. As can be seen, the flue gas molten salt heat exchange system in the present application not only can provide flue gas with uniform and adjustable temperature, adjustable flow, and stable parameters for the flue gas molten salt heat exchanger, but also, due to the use of two or more smoke taking methods, the flow of each smoke taking flue 300 can be adjusted to achieve the redistribution of the flue gas heat of the boiler 100, adding an adjustment means for the boiler 100, and significantly improving the flexibility of the boiler 100 adjustment.

[0156] In system design, the selection of the positions of the smoke taking flues 300 and the smoke taking ports 106 of the boiler 100, and the adjustment range of the flue gas flow under different working conditions, not only need to consider the process requirements of the flue gas molten salt heat exchange system, but also need to consider the demand for improving the flexibility of the boiler 100.

[0157] Figure 9In the embodiment, five flue gas extraction flues, i.e., the first flue gas extraction flue 301, the second flue gas extraction flue 302, the third flue gas extraction flue 303, the fourth flue gas extraction flue 304, and the fifth flue gas extraction flue 305, are arranged in the flue gas molten salt heat exchange system during design. The first three flue gas extraction flues are located in the second temperature zone flue section 102, and the last two flue gas extraction flues are located in the fifth temperature zone flue section 105. It can be seen that the flue gas extraction flues 300 can also be arranged in other temperature zone flue sections. The flue gas extraction flues 300 are arranged in the temperature zone flue section in which the high-temperature heating surface of the flue gas-water heat exchanger is prone to over-temperature. The design can protect the flue gas-water heat exchanger. During the operation of the boiler 100, the heat load distribution of the boiler 100 can be changed by changing the flue gas flow rate of the flue gas extraction flues 300, thereby improving the flexibility of the boiler 100. When the boiler 100 is operated at a low load, the flue gas extraction flue gas molten salt heat exchange system can extract flue gas directly into the flue gas return port 107a (without flue gas molten salt heat exchange), thereby improving the inlet flue gas temperature of the denitration device. In a severe working condition, when the flue gas-water heat exchanger of the boiler 100 is at risk of over-temperature, the flue gas upstream of the flue gas-water heat exchanger can be extracted in time, thereby reducing the heat load of the flue gas-water heat exchanger and preventing over-temperature.

[0158] It can be seen that the heat load of the heating surface of each heat exchanger in the boiler 100 changes after the flue gas extraction flue gas molten salt heat exchange system extracts a part of the flue gas. In the embodiment, the extraction of the flue gas is controlled in a targeted manner, which is beneficial to ensure that each heat exchanger does not over-temperature and that the heat meets the needs of the steam-water system. For a traditional boiler 100 with many thick-walled components and large thermal inertia, it is difficult to improve flexibility. The flue gas heat exchange system coupled with the boiler provided in the embodiment provides a new improvement idea for improving the flexibility of the boiler 100.

[0159] It can be seen that, based on the three-dimensional structure theory, the boiler flue gas driven flue gas molten salt heat exchange system is designed in three-dimensional structure, including the first level network structure formed from at least two flue gas taking flues 300 taking flue gas from the boiler 100 to the inlet of the flue gas mixing device 200, and the second level network structure formed from the outlet of the flue gas mixing device 200 to the outlet of the modular flue gas molten salt heat exchanger. The outlet of the flue gas molten salt heat exchanger is further connected with the centralized back flue 500 and the induced draft fan 600. The flue gas is sequentially flowed through the above network structure after being taken out from the boiler 100, and finally returned to the boiler 100, constituting the flue gas flow of the flue gas molten salt heat exchange system. In the scheme of the application, the fluid network composed of the hierarchical size flue gas taking flue 300, the centralized flue, the multi-stage shunt main pipe, the modular array of the flue gas molten salt heat exchanger (the array distributed multiple flue gas-molten salt heat exchange units 1005), and the multi-stage shunt main pipe realizes the comprehensive performance improvement of the flue gas molten salt heat storage system, including the hierarchical structure of different sizes to reduce the total resistance of the flue gas duct system, the dispersed flue gas taking flue 300 from the different temperature zone flue section position (representing different flue gas temperature levels) and different wall flue gas taking of the boiler 100, realizing the flexible adjustment of the flue gas flow and temperature parameters of the flue gas molten salt heat exchanger, and the dispersed flue gas entering the flue gas mixing device 200 to realize the uniformity of the flue gas temperature and pre-removal of the ash particles in the flue gas. It can be seen that the flue gas molten salt system in the embodiment of the application provides an original new method for realizing heat storage and improving the flexibility of the coal-fired generating unit.

[0160] The above is only the preferred embodiment of the application, and it should be pointed out that for those skilled in the art, without departing from the principle of the application, some improvements and refinements can be made, which should also be regarded as the protection scope of the application.

Claims

1. A method for controlling the three-dimensional structure of a flue gas molten salt heat exchange system driven by boiler flue gas, characterized in that, The three-dimensional structure of the flue gas molten salt heat exchange system includes: Boiler (100), the boiler (100) includes multiple flue sections with different temperature zones distributed along the flue gas flow direction; The first-level network structure includes at least two flue gas intake ducts (300), which are connected to different temperature zone flue gas sections; each flue gas intake duct (300) is equipped with a flow regulating component (402); each temperature zone flue gas section is provided with at least two flue gas inlets (106); each temperature zone flue gas section is provided with a flue gas-water heat exchanger, and the flue gas inlets (106) are located upstream of the flue gas-water heat exchanger; The second-level network structure (1000) includes a flue gas molten salt heat exchanger, which includes multiple flue gas-molten salt heat exchange units (1005); the second-level network structure (1000) also includes a multi-stage flue gas branching header that branches off in stages along the flue gas flow direction, with the outlet of the final stage flue gas branching header connected to the flue gas inlet of the flue gas-molten salt heat exchange unit (1005); the second-level network structure (1000) includes a multi-stage flue gas converging header that converges in stages along the flue gas flow direction, with the inlet of the primary flue gas converging header connected to the flue gas outlet of the flue gas-molten salt heat exchange unit (1005); the cross-sectional dimensions of the multi-stage flue gas branching header gradually decrease along the flue gas flow direction; the cross-sectional dimensions of the multi-stage flue gas converging header gradually increase along the flue gas flow direction. A flue gas mixing device (200) is provided, wherein the inlet of the flue gas mixing device (200) is connected to the first-level network structure, and the outlet of the flue gas mixing device (200) is connected to the primary flue gas diversion header of the second-level network structure (1000). The control method includes: According to the heat load requirements of the flue section of the temperature zone of the boiler (100) and the flue gas requirements of the flue gas molten salt heat exchanger, the flow rate of each of the flue gas intake flues (300) is adjusted by the flow rate regulating component (402). When the steam temperature of the flue gas-water heat exchanger installed in any of the temperature zone flue sections connected to the flue gas intake flue (300) exceeds the preset value, the flue gas flow rate of the flue gas intake flue (300) of the temperature zone flue section where the flue gas-water heat exchanger is located is increased. The flue gas section corresponding to the flue gas-water heat exchanger whose steam temperature exceeds the preset value is defined as flue gas section one, and any flue gas section downstream of flue gas section one that is connected to the flue gas intake duct (300) is defined as flue gas section two. Then, the flue gas flow rate of the flue gas intake duct (300) corresponding to flue gas section two is increased at the same time.

2. The control method for the three-dimensional structure of the boiler flue gas driven molten salt heat exchange system according to claim 1, characterized in that, The first-level network structure also includes a first centralized flue (903), the inlet of which is connected to each of the smoke extraction flues (300), and the outlet of which is connected to the inlet of the flue gas mixing device (200); the flow cross-sectional dimension of the first centralized flue (903) is larger than that of the smoke extraction flue (300).

3. The control method for the three-dimensional structure of the boiler flue gas driven molten salt heat exchange system according to claim 2, characterized in that, It also includes at least one second centralized flue (901), the inlet of which is connected to at least two of the smoke extraction flues (300), and the outlet of which is connected to the inlet of the first centralized flue (903); the flow cross-sectional dimension of the second centralized flue (901) is larger than that of the smoke extraction flue (300) and smaller than that of the first centralized flue (903).

4. The control method for the three-dimensional structure of the boiler flue gas driven molten salt heat exchange system according to claim 3, characterized in that, It also includes at least one third centralized flue (902), the inlet of which is connected to the outlet of the second centralized flue (901) and at least one of the smoke extraction flues (300), and the outlet of the third centralized flue (902) is connected to the inlet of the first centralized flue (903); the flow cross-sectional dimension of the third centralized flue (902) is larger than that of the smoke extraction flue (300) and smaller than that of the first centralized flue (903).

5. The control method for the three-dimensional structure of the boiler flue gas driven molten salt heat exchange system according to claim 4, characterized in that, The flue gas mixing device (200) includes at least one air intake flue (203), which is connected to the smoke extraction flue (300), or to the first centralized flue (903), or to the second centralized flue (901), or to the third centralized flue (902). The flue gas mixing device (200) includes a main cylinder (201), and each of the air inlet flues (203) is tangent to the main cylinder (201); a plurality of air inlet flues (203) are distributed circumferentially along the main cylinder (201), or a plurality of air inlet flues (203) are distributed along the height direction of the main cylinder (201).

6. The control method for the three-dimensional structure of the boiler flue gas driven molten salt heat exchange system according to claim 5, characterized in that, The flue gas mixing device (200) includes an exhaust cylinder (204), which is coaxially arranged with the main cylinder (201). The lower end of the exhaust cylinder (204) passes through the upper end face of the main cylinder (201) and extends into the interior of the main cylinder (201). The flue gas outlet of the flue gas mixing device (200) is the outlet of the exhaust cylinder (204). The flue gas mixing device (200) also includes a variable diameter cylinder (202), which is located below the main cylinder (201).

7. The control method for the three-dimensional structure of the boiler flue gas driven molten salt heat exchange system according to any one of claims 1-6, characterized in that, The second-level network structure (1000) includes a multi-stage flue gas diversion header (1001), a second-level flue gas diversion header (1002), a third-level flue gas diversion header (1003), and a fourth-level flue gas diversion header (1004); the first-level flue gas diversion header (1001) is the primary flue gas diversion header, and the fourth-level flue gas diversion header (1004) is the final flue gas diversion header; The primary flue gas diversion main pipe (1001) is arranged vertically downwards; the secondary flue gas diversion main pipe (1002) and the tertiary flue gas diversion main pipe (1003) are both arranged horizontally and perpendicular to each other; the quaternary flue gas diversion main pipe (1004) is arranged vertically downwards. The primary flue gas diversion header (1001) is connected to at least two secondary flue gas diversion headers (1002), the secondary flue gas diversion headers (1002) are connected to at least two tertiary flue gas diversion headers (1003), and the tertiary flue gas diversion headers (1003) are connected to at least two quaternary flue gas diversion headers (1004). The fourth-stage flue gas diversion header (1004) is connected to the flue gas inlet of the flue gas-molten salt heat exchange unit (1005).

8. The control method for the three-dimensional structure of the boiler flue gas driven molten salt heat exchange system according to claim 7, characterized in that, The second-level network structure (1000) includes a multi-stage flue gas manifold, a first-stage flue gas manifold (1006), a second-stage flue gas manifold (1007), a third-stage flue gas manifold (1008), and a fourth-stage flue gas manifold (1009); the first-stage flue gas manifold (1006) is the final-stage flue gas manifold, and the fourth-stage flue gas manifold (1009) is the primary-stage flue gas manifold. The primary flue gas manifold (1006) and the primary flue gas branch manifold (1001) are arranged in parallel; the secondary flue gas manifold (1007) and the secondary flue gas branch manifold (1002) are arranged in parallel; the tertiary flue gas manifold (1008) and the tertiary flue gas branch manifold (1003) are arranged in parallel; and the quaternary flue gas manifold (1009) and the quaternary flue gas branch manifold (1004) are arranged in parallel. The fourth-stage flue gas manifold (1009) is connected to the flue gas outlet of the flue gas-molten salt heat exchange unit (1005); The primary flue gas manifold (1006) is connected to at least two secondary flue gas manifolds (1007), the secondary flue gas manifolds (1007) are connected to at least two tertiary flue gas manifolds (1008), and the tertiary flue gas manifolds (1008) are connected to at least two quaternary flue gas manifolds (1009).

9. The control method for the three-dimensional structure of the boiler flue gas driven molten salt heat exchange system according to claim 8, characterized in that, The flue gas molten salt heat exchanger includes multiple sets of heat exchanger modules, and each set of heat exchanger modules includes at least two flue gas-molten salt heat exchange units (1005). The inlets of each of the flue gas-molten salt heat exchange units (1005) in the same group of heat exchanger modules are connected to the same tertiary flue gas branch header (1003) through the fourth-stage flue gas branch header (1004); the outlets of each of the flue gas-molten salt heat exchange units (1005) in the same group of heat exchanger modules are connected to the same tertiary flue gas branch header (1008) through the fourth-stage flue gas manifold header (1009).

10. The control method for the three-dimensional structure of a boiler flue gas driven molten salt heat exchange system according to any one of claims 1-6, characterized in that, It also includes a return flue (500) and an induced draft fan (600). The outlet of the flue gas manifold of the last stage is connected to the return flue (500). The return flue (500) is connected to the boiler (100). The induced draft fan (600) is located in the return flue (500) or between the return flue (500) and the flue gas manifold of the last stage.

11. The control method for the three-dimensional structure of the boiler flue gas driven molten salt heat exchange system according to claim 10, characterized in that, It also includes a second connecting flue (802), through which the outlet of the final stage flue gas manifold and the return flue (500) are connected; it also includes a flow meter (404), which is installed in the return flue (500) or the second connecting flue (802), and the flow meter (404) is used to detect the flow rate of the flue gas.

12. The control method for the three-dimensional structure of a boiler flue gas driven molten salt heat exchange system according to any one of claims 1-6, characterized in that, The boiler (100) includes a boiler denitrification zone (107), and the final stage flue gas manifold is connected to the boiler denitrification zone (107) through a return flue (500), or connected to the temperature zone flue section adjacent to the boiler denitrification zone (107). When the temperature of the boiler denitrification zone (107) is lower than the preset value, the molten salt of the flue gas molten salt heat exchanger is controlled to flow into the molten salt tank, and at least one of the flue gas intake ducts (300) is opened.

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