Gas-fired boiler combined with finned tubes for heat exchange

Abstract

The utility model discloses a gas-fired boiler combined with finned tubes for heat exchange, which comprises a burner and a hearth, the side wall of the hearth is a water-cooled wall, a finned tube group is arranged in the hearth and in front of the burner, finned tubes of the finned tube group and the top end of the water-cooled wall are communicated with a steam pocket positioned at the upper part of the hearth, and the top end of the steam pocket is communicated with a heat exchanger. A settling pipe is arranged on the side, away from the combustor, in the hearth, the upper end of the settling pipe penetrates out of the top of the steam pocket and is communicated with the steam pocket through a backflow pipe, the area of the communication section of the backflow pipe and the steam pocket is smaller than that of the settling pipe, and a water level electrode is arranged in the settling pipe. And the bottom ends of the settling tube, the finned tubes of the finned tube group and the water-cooled wall tubes of the water-cooled wall are communicated with one another. The water level detection accuracy of the built-in water level electrode can be improved.

Description

Technical Field

[0001] This utility model relates to a gas-fired boiler and belongs to the field of steam boiler technology. Background Technology

[0002] The basic structure of a gas-fired boiler includes water-cooled walls, a burner, and a steam-water separator. The high-temperature flue gas produced by the burner passes through the furnace, which is enclosed by water-cooled walls, heating the water in the process. To meet capacity design requirements, small gas-fired boilers typically incorporate finned tube bundles within the furnace to fully utilize thermal energy.

[0003] Existing small boilers use external water level gauges connected via connecting pipes, which is not suitable for arranging multiple boilers side-by-side. Furthermore, built-in electrode-type water level gauges are susceptible to sudden load changes and bubbles generated during boiling, leading to false water level readings and affecting the accuracy of water level measurements.

[0004] Furthermore, the continuous heat absorption by the finned tube bundle generates thermal radiation, which affects the burner, causing the temperature of components such as the burner head and shell to rise. Under prolonged continuous operation, the burner is likely to be damaged. Currently, water cooling is commonly used to cool the burner, which undoubtedly increases the overall manufacturing cost. At the same time, due to the size limitations of gas-fired boilers, sufficient spacing cannot be maintained between the finned tube bundle and the burner to reduce the impact of thermal radiation. Therefore, under the dual constraints of boiler size and cost control, it is difficult to extend the burner's lifespan. Utility Model Content

[0005] To address the shortcomings of the existing technology, this utility model provides a gas-fired boiler with finned tube heat exchange, aiming to solve the problem of inaccurate water level measurement by water level electrodes.

[0006] The technical solution of this utility model is as follows: A gas-fired boiler with finned tube heat exchange includes a burner and a furnace. The side wall of the furnace is a water-cooled wall. A finned tube assembly is provided inside the furnace in front of the burner. The top of the finned tubes of the finned tube assembly and the top of the water-cooled wall are connected to a steam drum located at the upper part of the furnace. A settling tube is provided on the side of the furnace away from the burner. The upper end of the settling tube extends from the top of the steam drum and is connected to the steam drum through a return pipe. The cross-sectional area of ​​the return pipe connected to the steam drum is smaller than the cross-sectional area of ​​the settling tube. A water level electrode is provided inside the settling tube. The bottom ends of the settling tube, the finned tubes of the finned tube assembly, and the water-cooled wall tubes of the water-cooled wall are all interconnected.

[0007] Furthermore, the diameter of the settling tube is larger than the diameter of the finned tube in the finned tube assembly and the diameter of the water-cooled wall tube in the water-cooled wall.

[0008] By increasing the diameter of the settling pipe, the proportion of space occupied by steam bubbles of the same volume in the pipeline becomes relatively smaller, and their interference with water level measurement becomes relatively dispersed. The flow velocity of water in the pipe is relatively reduced, and the flow is more stable. This reduces the impact of disturbances generated when boiler water boils on water level measurement, thus further improving the accuracy of water level detection.

[0009] Furthermore, the return pipe is located outside the steam drum and is sleeved on the settling pipe. The top plate of the steam drum has several through holes between the return pipe and the settling pipe. The through holes serve as channels for communication between the return pipe and the steam drum. The end of the return pipe has an installation hole opposite to the settling pipe.

[0010] Furthermore, the settling pipe is fixedly connected to both the top and bottom plates of the steam drum. In addition to serving as a pipeline for water level measurement, the settling pipe also acts as a reinforcing structure for the steam drum, improving its pressure resistance.

[0011] Furthermore, a bare tube assembly is provided between the finned tube assembly and the burner. The flue gas generated by the burner passes through the bare tube assembly and then through the finned tube assembly. The top end of the bare tube of the bare tube assembly is connected to the steam drum, and the bottom end of the bare tube of the bare tube assembly is connected to the bottom end of the finned tube of the finned tube assembly.

[0012] The bare tube assembly allows it to absorb some of the heat radiation from the finned tube assembly. At the same time, since the bare tube does not have fins, the heat radiation it generates is much less than that of the finned tube assembly. Therefore, it can reduce the heat radiation received by the burner overall, avoid abnormal heating of burner components, and improve the service life of the burner.

[0013] Furthermore, the steam drum is equipped with a steam-water separator, which includes a connecting cavity and a vent pipe. The connecting cavity is connected to the steam drum. The first end of the vent pipe is closed, and the second end of the vent pipe is the outlet end. The vent pipe runs horizontally through the connecting cavity, and the upper wall of the portion of the vent pipe inside the connecting cavity has air holes. Water vapor entering the steam-water separator from the steam drum bypasses the vent pipe and enters the vent pipe from the top. The vent pipe wall can block some tiny water droplets.

[0014] Furthermore, a baffle plate is provided within the connecting cavity, dividing the connecting cavity into upper and lower cavities. A first through-hole is provided at the connection end between the connecting cavity and the steam drum, and a second through-hole is provided on the baffle plate. The orthographic projections of the first and second through-holes do not overlap. The baffle plate further blocks tiny water droplets.

[0015] Furthermore, the burner is installed on the first side wall of the furnace, and a preheater is connected to the second side wall of the furnace. The second side wall is opposite to the first side wall. The preheater is equipped with a preheated water pipe, and the outlet of the preheated water pipe is connected to the bottom end of the finned tube of the finned tube assembly. The flue gas generated by the burner combustion enters the preheater after passing through the finned tube assembly. The preheater is located on the opposite side of the burner, facilitating the lateral expansion and connection of multiple boilers.

[0016] Furthermore, the burner is a non-water-cooled burner.

[0017] Furthermore, the water-cooled wall includes a wall panel with welding slots for water-cooled wall tubes. The water-cooled wall tubes are welded to the wall panel at the welding slots. Thus, the water-cooled wall panel is a single piece, and the welding slots facilitate the positioning of each water-cooled wall tube. It also allows for automated welding of the wall panel and water-cooled wall tubes using a robotic arm, improving efficiency.

[0018] Compared with the prior art, the advantages of the technical solution provided by this utility model are as follows:

[0019] This invention utilizes the small-section flow path of the return pipe and steam drum to control the return flow of steam generated by the settling pipe to the steam drum, delaying the release of steam pressure at the bottom of the settling pipe and suppressing significant disturbances to the water level caused by air bubbles in the settling pipe, thereby improving the accuracy of water level detection. Water level detection is performed using a built-in water level electrode, reducing the number of external components connected to the furnace and facilitating lateral expansion to connect multiple boilers.

[0020] A bare tube assembly is installed between the finned tube assembly and the burner inside the furnace, which effectively reduces heat radiation to the burner, lowers the temperature of the burner body components, and extends service life. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of a gas-fired boiler with finned tube heat exchange, as shown in the embodiment.

[0022] Figure 2 This is a cross-sectional structural diagram of a gas-fired boiler with finned tube heat exchange, as shown in the embodiment.

[0023] Figure 3 This is a schematic diagram of the water-cooled wall structure of a gas-fired boiler with finned tube heat exchange, as shown in the embodiment.

[0024] Figure 4 This is a partial structural diagram of the top of the settling tube of a gas-fired boiler with finned tube heat exchange, as shown in the embodiment.

[0025] Figure 5 This is a schematic diagram of the steam-water separator structure of a gas-fired boiler with finned tube heat exchange, as shown in the embodiment. Detailed Implementation

[0026] The present invention will be further described below with reference to the embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. After reading this description, any modifications of the present invention in various equivalent forms by those skilled in the art will fall within the scope defined by the appended claims.

[0027] Please combine Figure 1 and Figure 2 As shown, the gas-fired boiler with finned tube heat exchange in this embodiment includes a burner 1, a furnace 2, a water-cooled wall 3, a finned tube assembly 4, a steam drum 5, a settling tube 6, and a return pipe 7, etc.

[0028] The furnace 2 has a laterally flattened cuboid shape. The first sidewall 201 and the second sidewall 202 of the furnace 2 are a pair of opposing sidewalls made of metal plates. Burner mounting holes are provided on the first sidewall 201 to fix and install the burner 1. The burner 1 is a non-water-cooled burner to avoid increasing structural complexity due to cooling requirements; it is generally a planar low-NOx burner that burns natural gas. The flame generated by the burner 1 directly enters the inner cavity of the furnace 2, heating the boiler water through the generated flue gas.

[0029] The third and fourth sidewalls of the furnace 2 form another set of opposing sidewalls, both connected between the first sidewall 201 and the second sidewall 202. Both the third and fourth sidewalls are composed of water-cooled walls 3. Figure 3 As shown in the preferred embodiment, in this embodiment, the wall panel 301 of the water-cooled wall 3 is a one-piece plate, and multiple vertically extending water-cooled wall tube welding slots 301a are opened on the wall panel 301. Water-cooled wall tubes 302 are welded on the side of the wall panel 301 facing the inside of the furnace 2. Specifically, the water-cooled wall tubes 302 are arranged along the water-cooled wall tube welding slots 301a. Automated welding is performed on the side of the wall panel 301 facing away from the inside of the furnace 2 through the water-cooled wall tube welding slots 301a to weld and fix the water-cooled wall tubes 302 to the wall panel 301 and close the water-cooled wall tube welding slots 301a. In this way, on the one hand, the water-cooled wall tubes 302 and the wall panel 301 can achieve rapid positioning and welding; on the other hand, the wall panel 301 is a one-piece structure, unlike the previous method of welding separately on both sides of the tube, reducing the number of welding positions and improving production efficiency.

[0030] At the bottom of the furnace 2 is the lower header 203, through which the bottom ends of the water-cooled wall tubes 302 are all connected. At the top of the furnace 2 is the steam drum 5. The lower header 203, the steam drum 5, and the first side wall 201, the second side wall 202, the third side wall, and the fourth side wall of the furnace 2 enclose the inner cavity space of the furnace 2. The top ends of the water-cooled wall tubes 302 are all connected to the steam drum 5.

[0031] Finned tube assembly 4 and bare tube assembly 8 are installed in the inner cavity of furnace 2. The finned tubes of finned tube assembly 4 and the bare tubes of bare tube assembly 8 are both vertically arranged. The top ends of the finned tubes and bare tubes are connected to steam drum 5, and the bottom ends of the finned tubes and bare tubes are connected to lower header 203. The bare tube assembly 8 is located between burner 1 and finned tube assembly 4. That is to say, the flue gas generated by burner 1 first passes through bare tube assembly 8 and then through finned tube assembly 5. The heat radiation generated by the heat accumulated on the finned tubes is partially absorbed by bare tube assembly 8, reducing the temperature around burner 1 and preventing its components from overheating and affecting its service life.

[0032] Please combine Figure 4 As shown, a settling pipe 6 is provided on the side of the furnace 2 away from the burner 1. In this embodiment, the settling pipe 6 is located in the finned tube group 5, before the last row of finned tubes (facing the burner 1). The diameter of the finned tubes is similar to that of the water-cooled wall tube 302, while the diameter of the settling pipe 6 is larger than that of the water-cooled wall tube 302 and the finned tubes (for example, 1.5-2 times the diameter of the water-cooled wall tube). The bottom end of the settling pipe 6 is connected to the lower header 203, and the top end of the settling pipe 6 passes through the steam drum 5, and then connects to the steam drum 5 through the return pipe 7. Specifically, the top end of the settling pipe 6 passes through the bottom plate 501 and the top plate 502 of the steam drum 5 in sequence, and is fixedly connected to both the bottom plate 501 and the top plate 502 of the steam drum 5. The settling pipe 6 forms a reinforcing member supporting the bottom plate 501 and the top plate 502 of the steam drum 5, which can improve the pressure resistance of the steam drum 5. A return pipe 7 is installed on the outer sleeve of the section of the settling pipe 6 that exits the steam drum 5. A water level gauge mounting hole 701 is opened at the top of the return pipe 7, corresponding to the settling pipe 6. The water level electrode is installed inside the settling pipe 6 through the water level gauge mounting hole 701. The bottom end of the return pipe 7 is fixed to the top plate 502 of the steam drum 5. Several through holes 502a are provided on the top plate 502 of the steam drum 5 between the return pipe 7 and the settling pipe 6. The through holes 502a serve as channels connecting the return pipe 7 and the steam drum 5. The water vapor generated by the settling pipe 6 does not directly enter the steam drum 5 but enters the steam drum 5 through the return pipe 7. The cross-sectional area of ​​the connection between the return pipe 7 and the steam drum 5 is smaller than the cross-sectional area of ​​the settling pipe 6, which creates a flow-limiting effect to balance the pressure inside the settling pipe 6, reduce water level fluctuations caused by air bubbles, and improve the accuracy of water level detection.

[0033] Please combine Figure 5 As shown, the steam drum 5 is also equipped with a steam-water separator 9. The steam-water separator 9 includes a connecting cavity 901, a gas guide pipe 902, and a baffle plate 903. The lower end of the connecting cavity 901 is connected to the top plate 502 of the steam drum 5. The connecting cavity 901 is connected to the steam drum 5. A first through hole 502b is opened at the connection end between the connecting cavity 901 and the steam drum 5, that is, on the top plate 502 of the steam drum 5. The first through hole 502b is fan-shaped.

[0034] A baffle plate 903 is provided inside the connecting cavity 901, dividing the connecting cavity 901 into upper and lower cavities. The baffle plate 903 has a second through hole 903a, similar to the first through hole 502b. The second through hole 903a is fan-shaped, and the orthographic projections of the first through hole 502b and the second through hole 903a do not overlap, meaning that the first through hole 502b and the second through hole 903a are staggered vertically. In addition, the column 903b supporting the baffle plate 903 extends downward from the connecting cavity 901 into the steam drum 5, and is fixedly connected to both the top plate 502 and the bottom plate 501 of the steam drum 5, serving as a reinforcing support column for the steam drum 5 and improving the pressure resistance of the steam drum 5.

[0035] The first end of the air guide tube 902 is closed, and the second end of the air guide tube 902 is the outlet end that can be connected to the valve 10. The air guide tube 902 is a transverse tube that enters the upper cavity of the connecting cavity 901, and the upper wall of the portion of the air guide tube 902 located inside the connecting cavity 901 has an air hole 902a.

[0036] Water vapor in the steam drum 5 enters the steam-water separator 9 through the first through hole 502b. When it passes the baffle plate 903, some water droplets are blocked. The water vapor then bypasses the air guide pipe 902 and enters the air guide pipe 902 from the top. The lower wall of the air guide pipe 902 can block some tiny water droplets, thereby improving the dryness of the steam.

[0037] In a preferred embodiment, a preheater 11 is further connected to the second side wall 202 of the furnace 2, and the end of the preheater 11 is connected to the flue gas outlet 12. A preheating water pipe 1101 is arranged in an S-shape inside the preheater 11. The outlet of the preheating water pipe 1101 is connected to the lower header 203 of the furnace 2, that is, it is connected to the bottom ends of the finned tubes, bare tubes, and water-cooled wall tubes 302. The flue gas generated by the burner 1 flows sequentially through the bare tube assembly 8 and the finned tube assembly 5 before entering the preheater 11. The waste heat of the flue gas preheats the water in the preheating water pipe 1101, reducing the flue gas temperature and improving thermal efficiency.

Claims

1. A gas-fired boiler incorporating finned tube heat exchange, comprising a burner and a furnace, wherein the sidewall of the furnace is a water-cooled wall, and a finned tube assembly is provided inside the furnace in front of the burner, wherein the finned tubes of the finned tube assembly and the top ends of the water-cooled wall are connected to a steam drum located at the upper part of the furnace, characterized in that, A settling tube is provided on the side of the furnace away from the burner. The upper end of the settling tube extends from the top of the steam drum and is connected to the steam drum through a return pipe. The cross-sectional area of ​​the return pipe and the steam drum is smaller than the cross-sectional area of ​​the settling tube. A water level electrode is provided inside the settling tube. The bottom ends of the settling tube, the finned tubes of the finned tube assembly, and the water-cooled wall tubes of the water-cooled wall are all interconnected.

2. The gas-fired boiler with finned tube heat exchanger according to claim 1, characterized in that, The diameter of the settling tube is larger than the diameter of the finned tube in the finned tube assembly and the diameter of the water-cooled wall tube in the water-cooled wall.

3. The gas-fired boiler with finned tube heat exchange according to claim 1, characterized in that, The return pipe is located outside the steam drum and is sleeved on the settling pipe. Several through holes are provided on the top plate of the steam drum between the return pipe and the settling pipe. The through holes serve as channels for communication between the return pipe and the steam drum. The end of the return pipe is provided with an installation hole opposite to the settling pipe.

4. The gas-fired boiler with finned tube heat exchange according to claim 1, characterized in that, The settling pipe is fixedly connected to both the top and bottom plates of the steam drum.

5. The gas-fired boiler with finned tube heat exchange according to claim 1, characterized in that, A bare tube assembly is provided between the finned tube assembly and the burner. The flue gas generated by the burner passes through the bare tube assembly and then through the finned tube assembly. The top end of the bare tube of the bare tube assembly is connected to the steam drum, and the bottom end of the bare tube of the bare tube assembly is connected to the bottom end of the finned tube of the finned tube assembly.

6. The gas-fired boiler with finned tube heat exchange according to claim 1, characterized in that, The steam drum is equipped with a steam-water separator, which includes a connecting cavity and a gas guide pipe. The connecting cavity is connected to the steam drum. The first end of the gas guide pipe is closed, and the second end of the gas guide pipe is the outlet end. The gas guide pipe passes through the connecting cavity, and the upper wall of the portion of the gas guide pipe inside the connecting cavity has air holes.

7. The gas-fired boiler with finned tube heat exchanger according to claim 6, characterized in that, The connecting cavity is provided with a baffle plate, which divides the connecting cavity into upper and lower cavities. The connecting end of the connecting cavity and the steam drum is provided with a first through hole, and the baffle plate is provided with a second through hole. The orthographic projections of the first through hole and the second through hole do not overlap.

8. The gas-fired boiler with finned tube heat exchange according to claim 1, characterized in that, The burner is installed on the first side wall of the furnace, and a preheater is connected to the second side wall of the furnace. The second side wall is the side opposite to the first side wall. The preheater is provided with a preheating water pipe. The outlet of the preheating water pipe is connected to the bottom end of the finned tube of the finned tube assembly. The flue gas generated by the burner combustion enters the preheater after passing through the finned tube assembly.

9. The gas-fired boiler with finned tube heat exchange according to claim 1, characterized in that, The burner is a non-water-cooled burner.

10. The gas-fired boiler with finned tube heat exchange according to claim 1, characterized in that, The water-cooled wall includes a wall panel, and the wall panel is provided with a welding groove for water-cooled wall tubes. The water-cooled wall tubes are welded to the wall panel at the welding groove.

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