Water circulation structure of gas corner tube water boiler

Abstract

The present application relates to water circulation structure technical field, specifically disclose a kind of gas angle tube hot water boiler water circulation structure, hot flue gas ascending chamber inner cavity bottom is provided with front preheater, front preheater includes placing seat, placing seat is provided with liquid guide grate, first water collector pipe and second water collector pipe are respectively communicated with the both sides of liquid guide grate, first water collector pipe is connected with backwater preheating pipe wall, second water collector pipe is connected with water inlet preheating pipe wall;By setting front preheater including water inlet preheating pipe wall, liquid guide grate and backwater preheating pipe wall in the bottom of hot flue gas ascending chamber, the heat energy of high-temperature flue gas at the bottom of combustion chamber in traditional design can be efficiently recycled and utilized, the water temperature entering economizer and main circulation system is improved, so that the thermal efficiency of boiler is improved as a whole, and fuel consumption is reduced;Inclined arrangement backwater preheating pipe wall and water inlet preheating pipe wall ingeniously change the straight ascending path of flue gas, guide its oblique flow.

Description

Technical Field

[0001] This invention relates to the field of water circulation structure technology, specifically to a water circulation structure for a gas-fired corner tube hot water boiler. Background Technology

[0002] Gas-fired corner tube hot water boilers, as a common heating device, rely on a water circulation system to absorb the heat energy generated by fuel combustion. In traditional designs, boiler feedwater is typically preheated in an economizer before directly entering the main circulation system. However, this structure has several drawbacks. For example, the high-temperature flue gas generated at the bottom of the combustion chamber has an extremely high calorific value, but in traditional structures, this heat is not fully and progressively absorbed by the feedwater, resulting in a significant waste of high-quality heat energy. The single economizer preheating stage has limited capacity, especially during boiler startup or low-load operation, when the feedwater temperature is low. Direct entry into the main circulation system creates a large temperature difference with high-temperature components, affecting thermal efficiency and potentially even generating thermal stress. Furthermore, the flue gas tends to rise linearly within the rising chamber, limiting the effective contact area and time with the water-cooled tube walls, thus preventing optimal heat transfer efficiency. Therefore, designing a water circulation structure that can more efficiently and fully recover and utilize the heat energy at each stage within the boiler, particularly the heat energy from the high-temperature flue gas at the bottom of the combustion chamber, is a pressing technical problem that needs to be solved in this field. Summary of the Invention

[0003] In view of the shortcomings of the prior art, the present invention provides a water circulation structure for a gas-fired corner tube hot water boiler, which solves the problems of insufficient utilization of the high-temperature flue gas generated at the bottom of the combustion chamber and low contact rate between the flue gas and the water-cooled tube wall.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a water circulation structure for a gas-fired angle tube hot water boiler, comprising a first water-cooled tube wall, a second water-cooled tube wall, and a downcomer tube wall disposed within a boiler chamber. A hot flue gas rising chamber is formed between the first and second water-cooled tube walls, and a hot flue gas falling chamber is formed between the second water-cooled tube wall and the downcomer tube wall. An economizer is disposed within the hot flue gas falling chamber, and a preheater is disposed at the bottom of the hot flue gas rising chamber. The preheater includes a mounting base, on which a liquid-guiding grate is disposed. The first and second water collection pipes are connected to both sides of the liquid guiding grate, respectively. A return water preheating pipe wall is connected to the first water collection pipe. A third water collection pipe is connected to the top of the return water preheating pipe wall. A fourth water collection pipe is connected to one side of the third water collection pipe through a connecting pipe bank. A return liquid connecting pipe is connected to one side of the fourth water collection pipe. The return liquid connecting pipe is connected to the economizer. A water inlet preheating pipe wall is connected to the second water collection pipe. A fifth water collection pipe is connected to the top of the water inlet preheating pipe wall. A liquid inlet connecting pipe is connected to the fifth water collection pipe. The liquid inlet connecting pipe is connected to the liquid inlet pipe.

[0005] Preferably, the return water preheating pipe wall and the inlet water preheating pipe wall form a third chamber.

[0006] Preferably, the return water preheating pipe wall is located on one side of the first water-cooling pipe wall, the return water preheating pipe wall gradually slopes outward from the bottom to the top, and forms a first chamber with the first water-cooling pipe wall, the first chamber being connected to the hot flue gas rising chamber.

[0007] Preferably, the water inlet preheating pipe wall is located on one side of the second water cooling pipe wall, the water inlet preheating pipe wall gradually slopes outward from bottom to top, and a second chamber is formed between the water inlet preheating pipe wall and the second water cooling pipe wall, the second chamber being connected to the hot flue gas rising chamber.

[0008] Preferably, the placement seat has an ignition chamber inside, and igniters are provided on both the left and right side walls of the placement seat. An air vent is provided between two adjacent igniters on the placement seat.

[0009] Preferably, the top surface of the placement seat has a first opening on both sides, which communicates with the first chamber and the second chamber respectively; the top surface of the placement seat has a second opening in the middle, which communicates with the third chamber.

[0010] Preferably, the liquid guiding grate includes a shell, and water inlet winglets and water outlet winglets are respectively provided on both sides of the shell. The first water collecting pipe is connected to the water outlet winglet, and the second water collecting pipe is connected to the water inlet winglet.

[0011] Preferably, the interior of the housing is provided with a plurality of flat tubes from top to bottom, and the flat tubes are through cavities that run vertically through each other.

[0012] Preferably, the shell includes an upper cover plate, a lower cover plate, and an annular cylindrical wall arranged circumferentially between the upper cover plate and the lower cover plate. The annular cylindrical wall, together with the upper cover plate and the lower cover plate, forms a heat exchange chamber. Each of the flat tubes penetrates the heat exchange chamber and divides the heat exchange chamber into several interconnected small chambers.

[0013] The beneficial effects of the present invention are as follows: By using the gas-fired corner tube hot water boiler water circulation structure provided by the present invention, the following technical effects are achieved:

[0014] 1. By installing a preheater containing inlet water preheating pipe wall, liquid guiding grate and return water preheating pipe wall at the bottom of the hot flue gas rising chamber, the heat energy of the high-temperature flue gas at the bottom of the combustion chamber, which is easily wasted in traditional designs, can be efficiently recovered and utilized. This significantly increases the water temperature entering the economizer and main circulation system, thereby improving the overall thermal efficiency of the boiler and reducing fuel consumption.

[0015] 2. The inclined arrangement of the return water preheating pipe walls and the inlet water preheating pipe walls alters the straight upward path of the flue gas, guiding it to flow at an angle. This not only prolongs the contact time between the flue gas and the preheating pipe walls but also forces the flue gas to flow more closely against the first and second water-cooled pipe walls, enhancing the heating effect on the main circulation system. Simultaneously, the design of the third chamber enables double-sided heating of the preheating pipe walls, further maximizing the heat exchange potential.

[0016] 3. Through multi-stage preheating, the water temperature entering the main circulation system is higher and more uniform, reducing thermal stress caused by thermal shock, which helps to extend the service life of key boiler components and improves the stability and safety of equipment operation. Attached Figure Description

[0017] Figure 1 This is an isometric drawing of the water circulation pipeline of the present invention;

[0018] Figure 2 This is an isometric view of the preheater of the present invention;

[0019] Figure 3 This is a diagram showing the usage state of the preheater of the present invention located in the hot flue gas rising chamber;

[0020] Figure 4 This is a schematic diagram of the placement base structure of the present invention;

[0021] Figure 5 This is a schematic diagram of the three-dimensional structure of the liquid-guiding grate of the present invention;

[0022] Figure 6 This is a cross-sectional view of the liquid-conducting grate of the present invention;

[0023] Figure 7 This is a schematic diagram of liquid flow according to the present invention.

[0024] Explanation of reference numerals in the diagram: 1. First water-cooled tube wall; 2. Second water-cooled tube wall; 3. Downcomer tube wall; 4. Hot flue gas rising chamber; 5. Hot flue gas falling chamber; 6. Economizer; 7. Preheater; 71. Placement seat; 72. Ignition device; 73. Tubular outlet; 74. Liquid guiding grate; 741. Water inlet wing; 742. Water outlet wing; 743. Upper cover plate; 744. Lower cover plate; 745. Annular cylindrical wall; 746. Heat exchange chamber; 747. Flat... Pipe; 748, Through cavity; 75, First water collection pipe; 76, Second water collection pipe; 77, Return water preheating pipe wall; 78, Inlet water preheating pipe wall; 79, Third water collection pipe; 710, Fourth water collection pipe; 711, Connecting pipe bank; 712, Return liquid connecting pipe; 713, Inlet liquid connecting pipe; 714, First opening; 715, Second opening; 716, Ignition chamber; 717, Fifth water collection pipe; 8, First chamber; 9, Second chamber; 10, Third chamber. Detailed Implementation

[0025] To better explain and facilitate understanding of the present invention, a detailed description of the invention is provided below with reference to the accompanying drawings and specific embodiments. This embodiment provides a water circulation structure for use in a corner tube boiler. A preheater 7 is installed at the bottom of the hot flue gas rising chamber 4 formed between the first water-cooled tube wall 1 and the second water-cooled tube wall 2 to preheat the water flow before it enters the economizer. The preheater 7 includes a placement seat 71 fixed on a base at the bottom of the hot flue gas rising chamber 4. A liquid guiding grate 74 is installed on the placement seat 71. An inlet preheating tube wall 78 and a return preheating tube wall 77 are respectively arranged on both sides of the liquid guiding grate 74. The inclined arrangement of the return preheating tube wall and the inlet preheating tube wall alters the straight upward path of the flue gas, forcing the flue gas to flow more closely against the first and second water-cooled tube walls, enhancing the heating effect on the main circulation system. This allows for efficient recovery and utilization of the heat energy of the high-temperature flue gas at the bottom of the combustion chamber, which is easily wasted in traditional designs. This significantly increases the water temperature entering the economizer and the main circulation system, thereby improving the overall thermal efficiency of the boiler and reducing fuel consumption.

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Various changes can be made to the implementation schemes as long as the effects of the present invention can be achieved.

[0027] Those skilled in the art can connect the components in this case sequentially. The specific connection and operation sequence should refer to the working principle described below. The detailed connection methods are well-known technologies in the field. The working principle and process are mainly described below.

[0028] like Figures 1-7 As shown in the figure, this embodiment discloses a water circulation structure for a gas-fired angle tube hot water boiler, specifically including a first water-cooled pipe wall 1, a second water-cooled pipe wall 2, and a downcomer pipe wall 3 arranged in the boiler chamber; wherein, a hot flue gas rising chamber 4 is formed between the first water-cooled pipe wall 1 and the second water-cooled pipe wall 2, and the bottom of the hot flue gas rising chamber 4 is a combustion chamber; a hot flue gas falling chamber 5 is formed between the second water-cooled pipe wall 2 and the downcomer pipe wall 3, wherein the hot flue gas rising chamber 4 and the hot flue gas falling chamber 5 are interconnected; an economizer 6 is arranged in the hot flue gas falling chamber 5; in implementation, the hot flow flows along the hot flue gas rising chamber 4 to the hot flue gas falling chamber 5, and the water flow flows in the opposite direction to the hot flow, so that when the water flows into the boiler, it is preheated by the hot air flow that is about to flow out of the hot flue gas falling chamber 5; correspondingly, the gradually heated water flow repeatedly flows in the first water-cooled pipe wall 1, the second water-cooled pipe wall 2, and the steam drum and is heated by the high temperature flue gas in the hot flue gas rising chamber 4, and the heated hot water steam flows out of the steam drum.

[0029] In order to increase the utilization rate of the hot flue gas inside the hot flue gas rising chamber 4, this embodiment provides a preheater 7 at the bottom of the inner cavity of the hot flue gas rising chamber 4 to preheat the water flow before it enters the economizer.

[0030] Specifically, in this embodiment, the preheater 7 includes a placement seat 71 fixed to the bottom of the inner cavity of the hot flue gas rising chamber 4. A liquid guiding grate 74 is provided on the placement seat 71. A first water collecting pipe 75 and a second water collecting pipe 76 are respectively connected to both sides of the liquid guiding grate 74. A return water preheating pipe wall 77 is connected to the first water collecting pipe 75. The return water preheating pipe wall 77 is composed of multiple stainless steel pipes. A third water collecting pipe 79 is connected to the top of the return water preheating pipe wall 77. One side of the third water collecting pipe 79 is connected to... The connecting pipe 711 is connected to the fourth water collection pipe 710. The fourth water collection pipe 710 is connected to a return liquid connecting pipe 712 on one side. The return liquid connecting pipe 712 is connected to the economizer 6. The second water collection pipe 76 is connected to the inlet preheating pipe wall 78, which is composed of multiple stainless steel pipes. The top of the inlet preheating pipe wall 78 is connected to the fifth water collection pipe 717. The fifth water collection pipe 717 is connected to the liquid inlet connecting pipe 713, which is connected to the liquid inlet pipe.

[0031] In a preferred embodiment, such as Figures 1 to 3 As shown, the external liquid inlet pipe flows through the hot flue gas descending chamber 5 and then through the liquid inlet connecting pipe 713 into the fifth water collection pipe 717. The liquid is then evenly distributed into each tube of the water inlet preheating pipe wall 78. At this point, the water inlet preheating pipe wall 78 contacts the rising hot flue gas generated after ignition for the first stage of heat exchange. The liquid continues to flow and converges in the second water collection pipe 76, then enters the liquid guiding grate 74, where it contacts the rising hot flue gas again to form the second stage of heat exchange. The liquid continues to flow out of the liquid guiding grate 74 and converges in the first water collection pipe. Inside the first water collection pipe 75, the water after the second heat exchange is evenly distributed to each stainless steel pipe of the return water preheating pipe wall 77 for the third heat exchange. After the third heat exchange, the water is collected in the third water collection pipe 79, and then enters the fourth water collection pipe 710 through the connecting pipe bank 711. Finally, it enters the economizer 6 through the return liquid connecting pipe 712. Through the three-stage preheating, the water flows through the inlet preheating pipe wall, the liquid guiding grate and the return water preheating pipe wall in sequence, realizing three continuous heat exchanges with the high temperature flue gas, which greatly improves the preheating effect and heat recovery rate.

[0032] Furthermore, specifically as follows Figure 3 As shown, in the above embodiment, the return water preheating pipe wall 77 is located on one side of the first water cooling pipe wall 1, and a first chamber 8 is formed between it and the first water cooling pipe wall 1. The first chamber 8 is connected to the hot flue gas rising chamber 4. In addition, the return water preheating pipe wall 77 gradually slopes outward from the bottom to the top.

[0033] Furthermore, the water inlet preheating pipe wall 78 is located on one side of the second water cooling pipe wall 2. The water inlet preheating pipe wall 78 gradually slopes outward from the bottom to the top, and forms a second chamber 9 between it and the second water cooling pipe wall 2. The second chamber 9 is connected to the hot flue gas rising chamber 4.

[0034] The return water preheating pipe wall 77 and the inlet water preheating pipe wall 78 are both arc-shaped. This design causes the hot flue gas to change from a straight upward path to an oblique upward path due to the influence of the return water preheating pipe wall 77 and the inlet water preheating pipe wall 78 when it rises, guiding and reshaping the flow path of the flue gas, thereby simultaneously achieving enhanced heat exchange with the preheating pipe wall and the main water-cooling pipe wall. The hot flue gas is guided to contact and exchange heat with the return water preheating pipe wall 77 and the inlet water preheating pipe wall 78, and can also make the hot flue gas flow upward along the wall surface of the first water-cooling pipe wall 1 and the second water-cooling pipe wall 2, increasing the contact effect between the hot flue gas and the first water-cooling pipe wall 1 and the second water-cooling pipe wall 2, thereby improving the heating effect of the water in the first water-cooling pipe wall 1 and the second water-cooling pipe wall 2.

[0035] Furthermore, a third chamber 10 is formed between the return water preheating pipe wall 77 and the inlet water preheating pipe wall 78. This chamber is used to guide the hot flue gas upwards during the initial stage of generating hot flue gas after ignition. After entering the third chamber 10, the hot flue gas contacts the back wall surfaces of the return water preheating pipe wall 77 and the inlet water preheating pipe wall 78, forming a heat exchange and temperature increase on both sides of the return water preheating pipe wall 77 and the inlet water preheating pipe wall 78 in conjunction with the first chamber 8 and the second chamber 9. This causes the hot flue gas after ignition to be diverted and rise upwards in the first chamber 8, the second chamber 9, and the third chamber 10, and then converge in the hot flue gas rising chamber 4.

[0036] Furthermore, such as Figure 4 As shown, an ignition chamber 716 is formed inside the placement seat 71. Igniters 72 are provided on both the left and right side walls of the placement seat 71. An air vent 73 is provided between two adjacent igniters 72 and is opened on the placement seat 71. The air inlet pipe of the boiler itself is connected to the air vent 73.

[0037] In addition, there are first openings 714 on both sides of the top surface of the placement seat 71, and the two first openings 714 are respectively connected to the first chamber 8 and the second chamber 9; there is a second opening 715 in the middle of the top surface of the placement seat 71, and the second opening 715 is connected to the third chamber 10; the function of the placement seat 71 is to support the liquid guiding grate 74 and the return water preheating pipe wall 77 and the inlet water preheating pipe wall 78, and it integrates the functions of ignition, air distribution and flue gas guidance, and distributes the initial flame and airflow of combustion to each heat exchange chamber in an orderly manner through the opening.

[0038] In this embodiment, the liquid-guiding grate 74 is as follows: Figure 5 and Figure 6As shown, it specifically includes a shell, with water inlet wing 741 and water outlet wing 742 respectively provided on both sides of the shell; wherein, the water inlet wing 741 and water outlet wing 742 are hollow inside, the first water collection pipe 75 is connected to the water outlet wing 742, and the second water collection pipe 76 is connected to the water inlet wing 741.

[0039] Furthermore, the interior of the shell is provided with several flat tubes 747 from top to bottom. The flat tubes 747 are through cavities 748 that run vertically through the shell and serve as conduits for the flow of hot flue gas.

[0040] Furthermore, the shell includes an upper cover plate 743, a lower cover plate 744, and an annular cylindrical wall 745 arranged circumferentially between the upper cover plate 743 and the lower cover plate 744. The annular cylindrical wall 745, the upper cover plate 743, and the lower cover plate 744 enclose a heat exchange chamber 746. Each flat tube 747 penetrates the heat exchange chamber 746 and divides the heat exchange chamber 746 into several interconnected small chambers. The upper and lower ends of the flat tube 747 are sealed and welded to the upper cover plate 743 and the lower cover plate 744.

[0041] During implementation, the water that has undergone heat exchange through the preheating pipe wall 78 enters the heat exchange chamber 746 through the inlet lug 741. During its flow in the heat exchange chamber 746, the water comes into contact with the wall of each flat tube 747. At this time, hot flue gas is flowing from bottom to top inside the flat tube 747. The water comes into contact with the flat tube 747 to exchange heat and raise the temperature of the water. The heated water then flows out through the outlet lug 742.

[0042] A detailed working principle of the above embodiment is as follows: the boiler return water or cold water to be heated first enters the hot flue gas descending chamber 5, and is preheated by the flue gas that is about to be discharged from the boiler and still has a certain residual temperature.

[0043] The water then flows through the inlet connection pipe 713 into the fifth water collection pipe 717, and is then evenly distributed into multiple stainless steel pipes of the inlet preheating pipe wall 78, directly contacting the high-temperature flue gas generated by combustion, thus preheating the water in the first step. Afterward, the water converges into the second water collection pipe 76 and then enters the heat exchange chamber 746 of the liquid-conducting grate 74. Within this chamber, the water flows around a flat tube 747 that runs through it, used to pass through the high-temperature flue gas. At this time, hot flue gas rises from bottom to top within the flat tube 747, and the water fully interacts with the wall surface of the flat tube 747. Heat exchange completes the second step of preheating; water flows out from the liquid guide grate 74 and converges into the first water collection pipe 75, and is then evenly distributed into multiple stainless steel pipes in the return water preheating pipe wall 77, completing the third step of preheating; after being heated three times by the preheater, the water temperature has been significantly increased; the water flows through the third water collection pipe 79, the connecting pipe bank 711, and the fourth water collection pipe 710 in sequence, and finally enters the economizer 6 through the return liquid connecting pipe 712; in the economizer 6, the water is heated again by the flue gas in the hot flue gas descending chamber 5, and then enters the main circulation of the boiler.

[0044] The basic principles, main features, and advantages of the present invention have been described above. However, the above description is only a specific embodiment of the present invention, and the technical features of the present invention are not limited thereto. Any other embodiments derived by those skilled in the art without departing from the technical solution of the present invention should be covered within the patent scope of the present invention.

[0045] In the description of this invention, each embodiment focuses on its differences from other embodiments, and similar or identical parts between embodiments can be referred to interchangeably. As the apparatus disclosed in the embodiments corresponds to the methods disclosed in the embodiments, the description is relatively simple, and relevant parts can be referred to the method section.

[0046] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A gas corner tube water boiler water circulation structure, comprising a first water-cooled tube wall (1), a second water-cooled tube wall (2) and a downcomer wall (3) arranged in a boiler chamber, a hot flue gas rising chamber (4) is formed between the first water-cooled tube wall (1) and the second water-cooled tube wall (2), a hot flue gas descending chamber (5) is formed between the second water-cooled tube wall (2) and the downcomer wall (3), and an economizer (6) is arranged in the hot flue gas descending chamber (5), characterized in that: The hot flue gas rising chamber (4) is provided with a front preheater (7) at the bottom of the inner cavity, the front preheater (7) comprises a placing seat (71), the placing seat (71) is provided with a liquid guide grate (74), the liquid guide grate (74) is respectively communicated with a first water collecting pipe (75) and a second water collecting pipe (76) on the two sides, the first water collecting pipe (75) is connected with a backwater preheating pipe wall (77), the backwater preheating pipe wall (77) is communicated with a third water collecting pipe (79) at the top, the third water collecting pipe (79) is communicated with a fourth water collecting pipe (710) through a connecting pipe row (711) on one side, the fourth water collecting pipe (710) is connected with a back liquid connecting pipe (712) on one side, and the back liquid connecting pipe (712) is communicated with the economizer (6); the second water collecting pipe (76) is connected with a water inlet preheating pipe wall (78), the water inlet preheating pipe wall (78) is communicated with a fifth water collecting pipe (717) at the top, the fifth water collecting pipe (717) is communicated with a liquid inlet connecting pipe (713), and the liquid inlet connecting pipe (713) is communicated with a liquid inlet pipeline; The backwater preheating pipe wall (77) and the water inlet preheating pipe wall (78) constitute a third cavity (10); The backwater preheating pipe wall (77) is located on one side of the first water cooling pipe wall (1), the backwater preheating pipe wall (77) is gradually inclined outward from the bottom to the top, and a first cavity (8) is formed between the backwater preheating pipe wall (77) and the first water cooling pipe wall (1), and the first cavity (8) is communicated with the hot flue gas rising chamber (4); The water inlet preheating pipe wall (78) is located on one side of the second water cooling pipe wall (2), the water inlet preheating pipe wall (78) is gradually inclined outward from the bottom to the top, and a second cavity (9) is formed between the water inlet preheating pipe wall (78) and the second water cooling pipe wall (2), and the second cavity (9) is communicated with the hot flue gas rising chamber (4).

2. A water circulation structure for a gas corner tube water boiler according to claim 1, characterized in that: The placing seat (71) is internally formed with an ignition cavity (716), and the left and right side walls of the placing seat (71) are both provided with an igniter (72), and adjacent two igniters (72) are provided with an air inlet (73) formed in the placing seat (71).

3. A water circulation structure for a gas corner tube water boiler according to claim 2, characterized in that: First openings (714) are formed on the two sides of the top surface of the placing seat (71), the first openings (714) are respectively communicated with the first cavity (8) and the second cavity (9), and a second opening (715) is formed in the middle of the top surface of the placing seat (71), and the second opening (715) is communicated with the third cavity (10).

4. A water circulation structure for a gas corner-tube water boiler according to claim 3, characterized in that: The liquid guide grate (74) comprises a shell, the shell is provided with a water inlet wing ear (741) and a water outlet wing ear (742) on the two sides, the first water collecting pipe (75) is communicated with the water outlet wing ear (742), and the second water collecting pipe (76) is communicated with the water inlet wing ear (741).

5. A water circulation structure for a gas corner tube water boiler according to claim 4, characterized in that: A plurality of flat tubes (747) are arranged in the shell from top to bottom, and the flat tubes (747) are through cavities (748) penetrating from top to bottom.

6. A water circulation structure for a gas corner-tube water boiler according to claim 5, characterized in that: The shell comprises an upper cover plate (743), a lower cover plate (744), and an annular cylinder wall (745) arranged circumferentially between the upper cover plate (743) and the lower cover plate (744), a heat exchange chamber (746) is enclosed between the upper cover plate (743) and the lower cover plate (744), each flat tube (747) penetrates the heat exchange chamber (746) and divides the heat exchange chamber (746) into a plurality of small chambers in communication.

Images