Gas-fired boiler combined with finned tubes for heat exchange

Abstract

The invention 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 cooling 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 cooling wall are both communicated with a steam pocket positioned at the upper part of the hearth, and the top end of the water cooling wall is communicated with the top end of the burner. 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] The invention relates to a gas boiler and belongs to the technical field of steam boilers. Background Art

[0002] The basic structure of a gas boiler includes a water-cooled wall, a burner, and a steam-water separator. The high-temperature flue gas generated by the burner will pass through the furnace surrounded by the water-cooled wall, heating the water in the process. In order to meet the capacity design requirements, small gas boilers usually have finned tube bundles in the furnace to make full use of the heat energy.

[0003] Existing small boilers use external water level gauges through connecting pipes, which is not conducive to the lateral arrangement of multiple boilers. The built-in electrode water level gauge is easily affected by sudden load changes and bubbles generated by boiling, which can produce false water levels and affect the accuracy of water level measurement.

[0004] In addition, the finned tube bundle will generate heat radiation after continuous heat absorption, which will affect the burner, causing the temperature of the burner head, shell and other parts of the burner to rise. In the case of long-term continuous operation, the burner is likely to be damaged. At present, water cooling is usually used to cool the burner, which undoubtedly leads to an increase in the overall manufacturing cost. At the same time, due to the size limitation of the gas boiler, it is impossible to maintain a sufficient distance between the finned tube bundle and the burner to reduce the impact of heat radiation. Therefore, under the dual factors of boiler size limitation and cost control, it is difficult to improve the life of the burner. Summary of the invention

[0005] In view of the above-mentioned defects of the prior art, the present invention provides a gas boiler combined with fin tube heat exchange, aiming to solve the problem of inaccurate measurement of the water level in the boiler by the water level electrode.

[0006] The technical solution of the present invention is as follows: A gas boiler combined with finned tube heat exchange comprises a burner and a furnace, the side wall of the furnace is a water-cooled wall, a finned tube group is arranged inside the furnace in front of the burner, the finned tubes of the finned tube group and the top end of the water-cooled wall are connected to the steam drum located at the upper part of the furnace, a settling tube is arranged on the side of the furnace away from the burner, the upper end of the settling tube passes through the top of the steam drum and is connected to the steam drum through a reflux pipe, the connecting cross-sectional area of ​​the reflux pipe and the steam drum is smaller than the cross-sectional area of ​​the settling tube, a water level electrode is arranged in the settling tube, 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 all connected to each other.

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

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

[0009] Furthermore, the return pipe is located on the outside of the steam drum, and the return pipe is sleeved outside the settling pipe. A plurality of 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 connecting the return pipe and the steam drum, and the pipe end of the return pipe is provided with a mounting hole opposite to the settling pipe.

[0010] Furthermore, the settling pipe is fixedly connected to the top plate and the bottom plate of the steam drum. The settling pipe is not only a pipeline for measuring the water level, but also a reinforcement structure of the steam drum to improve the pressure resistance of the steam drum.

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

[0012] The setting of the bare tube group allows it to absorb part of the heat radiation from the finned tube group. At the same time, since the bare tube does not have fins, the heat radiation generated is much smaller than the finned tube group. Therefore, it can generally reduce the heat radiation received by the burner, avoid abnormal heating of the burner components, and increase the service life of the burner.

[0013] Furthermore, the steam drum is provided with a steam-water separator, the steam-water separator includes a connecting cavity and an air duct, the connecting cavity is connected to the steam drum, the first end of the air duct is closed, the second end of the air duct is an outlet end, the air duct crosses the connecting cavity, and the upper wall of the part of the air duct located in the connecting cavity is provided with air holes. The water vapor entering the steam-water separator from the steam drum bypasses the air duct and enters the air duct from the upper side, and some tiny water droplets can be blocked by the wall of the air duct.

[0014] Furthermore, a water baffle is provided in the connecting cavity, the water baffle divides the connecting cavity into an upper cavity and an lower cavity, a first through hole is provided at the connecting end of the connecting cavity and the drum, and a second through hole is provided on the water baffle, and the orthographic projections of the first through hole and the second through hole do not overlap. The water baffle is used to further block tiny water droplets.

[0015] Furthermore, the burner is mounted on the first side wall of the furnace, the second side wall of the furnace is connected to a preheater, the second side wall is the side opposite to the first side wall, a preheating water pipe is arranged in the preheater, the outlet of the preheating water pipe is connected to the bottom end of the fin tube of the fin tube group, and the flue gas generated by the burner passes through the fin tube group and enters the preheater. The preheater is arranged on the opposite side of the burner to facilitate the lateral expansion connection of multiple boilers.

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

[0017] Furthermore, the water-cooled wall comprises a wall plate, and a water-cooled wall tube welding notch is provided on the wall plate, and the water-cooled wall tube is welded and connected to the wall plate at the position of the water-cooled wall tube welding notch. In this way, the water-cooled wall plate is an integrated plate, and the water-cooled wall tube welding notch is provided to facilitate the positioning of each water-cooled wall tube, and also facilitate the automatic welding of the wall plate and the water-cooled wall tube by a robot arm, thereby improving efficiency.

[0018] Compared with the prior art, the advantages of the technical solution provided by the present invention are: The present invention utilizes the small cross-section flow passage between the reflux pipe and the drum to control the reflux of the steam generated by the settling pipe to the drum, delay the release of the steam pressure at the bottom of the settling pipe, and suppress the large disturbance of the water level by the bubbles in the settling pipe, thereby improving the accuracy of water level detection. The water level is detected by the built-in water level electrode, reducing the external components outside the furnace, and facilitating the lateral expansion and connection of multiple boilers.

[0019] A smooth tube group is arranged between the finned tube group and the burner in the furnace, which effectively reduces the heat radiation to the burner, reduces the temperature of the burner body components, and increases the service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic structural diagram of a gas boiler combined with fin tube heat exchange according to an embodiment.

[0021] Figure 2 It is a schematic cross-sectional structure diagram of a gas boiler combined with fin tube heat exchange according to an embodiment.

[0022] Figure 3 It is a schematic diagram of the water-cooled wall structure of a gas boiler combined with finned tube heat exchange according to an embodiment.

[0023] Figure 4 It is a schematic diagram of the local structure of the top end of the settling tube of the gas boiler combined with fin tube heat exchange according to the embodiment.

[0024] Figure 5 It is a schematic structural diagram of a steam-water separator of a gas boiler combined with fin tube heat exchange according to an embodiment. DETAILED DESCRIPTION

[0025] The present invention is further described below in conjunction with examples. It should be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention. After reading this description, various equivalent modifications to this description by those skilled in the art fall within the scope defined by the claims attached to this application.

[0026] Please combine Figure 1 and Figure 2 As shown, the gas boiler combined with fin tube heat exchange in this embodiment includes a burner 1, a furnace 2, a water-cooled wall 3, a fin tube group 4, a steam drum 5, a settling pipe 6 and a reflux pipe 7, etc.

[0027] The furnace 2 is in the shape of a rectangular parallelepiped that is relatively flat in the side direction. The first side wall 201 and the second side wall 202 of the furnace 2 are a set of opposite side walls, which are made of metal plates. A burner mounting hole is provided on the first side wall 201 to fix and install the burner 1. The burner 1 is a non-water-cooled burner to avoid increasing the structural complexity due to cooling requirements. Generally, a flat low-nitrogen burner that burns natural gas is used. The flame generated by the combustion of the burner 1 directly enters the inner cavity of the furnace 2, and the boiler water is heated by the generated flue gas.

[0028] The third side wall and the fourth side wall of the furnace 2 are another set of opposite side walls, and the third side wall and the fourth side wall are connected between the first side wall 201 and the second side wall 202. The third side wall and the fourth side wall are both formed by the water-cooled wall 3. Figure 3 As shown, as a preferred embodiment, in this embodiment, the wall plate 301 of the water-cooled wall 3 is an integrated plate, and a plurality of water-cooled wall tube welding notches 301a extending in a vertical direction are provided on the wall plate 301. The water-cooled wall tube 302 is welded on the side of the wall plate 301 facing the inner side of the furnace 2, and specifically, the water-cooled wall tube 302 is arranged along the water-cooled wall tube welding notches 301a, and the water-cooled wall tube 302 is welded and fixed to the wall plate 301 through the water-cooled wall tube welding notches 301a on the side of the wall plate 301 facing away from the inner side of the furnace 2, and the water-cooled wall tube welding notches 301a are closed. In this way, on the one hand, the water-cooled wall tube 302 and the wall plate 301 can be quickly positioned and welded, and on the other hand, the wall plate 301 is an integrated structure, which is different from the previous welding on both sides of the tube, reducing the welding position and improving production efficiency.

[0029] 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, which is surrounded by 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 to form the inner cavity space of the furnace 2, and the top ends of the water-cooled wall tubes 302 are all connected to the steam drum 5.

[0030] The finned tube group 4 and the light tube group 8 are arranged in the inner cavity space of the furnace 2. The finned tubes of the finned tube group 4 and the light tubes of the light tube group 8 are arranged vertically. The top ends of the finned tubes and the light tubes are connected to the steam drum 5, and the bottom ends of the finned tubes and the light tubes are connected to the lower header 203. The light tube group 8 is arranged between the burner 1 and the finned tube group 4, that is, the flue gas generated by the burner 1 first passes through the light tube group 8 and then passes through the finned tube group 5. The heat radiation generated by the heat accumulated in the fins of the finned tubes is partially absorbed by the light tube group 8, thereby reducing the ambient temperature of the burner 1 and preventing its components from overheating and affecting their service life.

[0031] Please combine Figure 4 As shown, a settling tube 6 is provided on the side of the furnace 2 away from the burner 1. In this embodiment, the settling tube 6 is located in the fin tube group 5, before the last row of fin tubes in the fin tube group 5 (on the side facing the burner 1). The diameter of the fin tube is equivalent to the diameter of the water-cooled wall tube 302, while the diameter of the settling tube 6 is larger than the diameter of the water-cooled wall tube 302 and the fin tube (for example, 1.5-2 times the diameter of the water-cooled wall tube). The bottom end of the settling tube 6 is connected to the lower header 203, and the top end of the settling tube 6 passes through the steam drum 5, and then communicates with the steam drum 5 through the reflux pipe 7. Specifically, the top end of the settling tube 6 passes through the bottom plate 501 and the top plate 502 of the steam drum 5 in turn, and is fixedly connected to the bottom plate 501 and the top plate 502 of the steam drum 5. The settling tube 6 is used to form a reinforcement 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 provided on the outer sleeve of the pipe section of the settling pipe 6 passing through the steam drum 5. A water level gauge mounting hole 701 is provided at the top of the return pipe 7. The water level gauge mounting hole 701 corresponds to the settling pipe 6. The water level electrode is installed in 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. A plurality of 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 for the return pipe 7 to communicate with 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 produces a flow limiting effect to balance the pressure in the settling pipe 6, reduce the water level fluctuation caused by bubbles, and improve the water level detection accuracy.

[0032] Please combine Figure 5 As shown, a steam-water separator 9 is also provided on the steam drum 5, and the steam-water separator 9 includes a connecting cavity 901, an air guide pipe 902 and a water retaining plate 903. The lower end of the connecting cavity 901 is connected to the top plate 502 of the steam drum 5, and the connecting cavity 901 is connected to the steam drum 5. A first through hole 502b is opened at the connecting end of the connecting cavity 901 and the steam drum 5, that is, on the top plate 502 of the steam drum 5, and the first through hole 502b is fan-shaped.

[0033] A water baffle 903 is provided in the connecting cavity 901, and the water baffle 903 divides the connecting cavity 901 into an upper cavity and an lower cavity. The water baffle 903 is provided with a second through hole 903a, which is 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, that is, the first through hole 502b and the second through hole 903a are staggered up and down. In addition, the column 903b supporting the water baffle 903 penetrates downward from the connecting cavity 901 into the steam drum 5, and is fixedly connected to the top plate 502 and the bottom plate 501 of the steam drum 5 as a reinforcing support column of the steam drum 5, thereby improving the pressure resistance of the steam drum 5.

[0034] The first end of the air guide tube 902 is closed, and the second end of the air guide tube 902 is an outlet end that can be connected to the valve 10. The air guide tube 902 is a top cavity that crosses into the connecting cavity 901, and the upper wall of the air guide tube 902 located in the connecting cavity 901 is provided with an air hole 902a.

[0035] The water vapor in the steam drum 5 enters the steam-water separator 9 through the first through hole 502b, blocks some water droplets when passing through the water baffle 903, and then bypasses the air duct 902 and enters the air duct 902 from the upper side, and can block some tiny water droplets through the tube wall on the lower side of the air duct 902, thereby improving the dryness of the steam.

[0036] As a preferred embodiment, the second side wall 202 of the furnace 2 is further connected with a preheater 11, and the end of the preheater 11 is connected to the smoke outlet 12. A preheating water pipe 1101 is arranged in an S shape inside the preheater 11, and 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 fin tube, the light tube, and the water-cooled wall tube 302. The flue gas generated by the burner 1 flows through the light tube group 8 and the fin tube group 5 in sequence and then enters the preheater 11. The waste heat of the flue gas preheats the water in the preheating water pipe 1101, reduces the smoke exhaust temperature, and improves the thermal efficiency.

Claims

1. A gas boiler combined with finned tube heat exchange, comprising a burner and a furnace, wherein the side wall of the furnace is a water-cooled wall, a finned tube group is arranged in front of the burner inside the furnace, and the finned tubes of the finned tube group and the top of the water-cooled wall are both connected to the 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 passes through the top of the steam drum and is connected to the steam drum through a reflux pipe, the connecting cross-sectional area between the reflux pipe and the steam drum is smaller than the cross-sectional area of ​​the settling tube, a water level electrode is provided in the settling tube, and the bottom ends of the settling tube, the fin tubes of the fin tube group and the water-cooled wall tubes of the water-cooled wall are all connected to each other.

2. The gas boiler combined with finned tube heat exchange according to claim 1, characterized in that: The diameter of the settling tube is larger than the diameter of the fin tubes in the fin tube group and the diameter of the water-cooled wall tubes in the water-cooled wall.

3. The gas boiler combined with finned tube heat exchange according to claim 1, characterized in that: The return pipe is located on the outside of the steam drum, and the return pipe is sleeved outside the settling pipe. A plurality of 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 connecting the return pipe and the steam drum. The end of the return pipe is provided with a mounting hole opposite to the settling pipe.

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

5. The gas boiler combined with finned tube heat exchange according to claim 1, characterized in that: A light tube group is provided between the fin tube group and the burner. The flue gas generated by the combustion of the burner passes through the light tube group and then passes through the fin tube group. The top end of the light tube of the light tube group is connected to the steam drum, and the bottom end of the light tube of the light tube group is connected to the bottom end of the fin tube of the fin tube group.

6. The gas boiler combined with finned tube heat exchange according to claim 1, characterized in that: The steam drum is provided with a steam-water separator, which includes a connecting cavity and an air duct. The connecting cavity is connected to the steam drum, the first end of the air duct is closed, the second end of the air duct is an outlet end, the air duct crosses the connecting cavity, and an air hole is opened on the upper wall of the part of the air duct located in the connecting cavity.

7. The gas boiler combined with finned tube heat exchange according to claim 6, characterized in that: A water baffle is provided in the connecting cavity, and the water baffle separates the connecting cavity into upper and lower cavities. A first through hole is provided at the connecting end of the connecting cavity and the steam drum, and the water baffle 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 boiler combined 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 the second side wall of the furnace is connected to a preheater, the second side wall is the side opposite to the first side wall, a preheating water pipe is arranged in the preheater, the outlet of the preheating water pipe is connected to the bottom end of the fin tube of the fin tube group, and the flue gas generated by the combustion of the burner enters the preheater after passing through the fin tube group.

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

10. The gas boiler combined with finned tube heat exchange according to claim 1, characterized in that: The water-cooled wall comprises a wall plate, on which a water-cooled wall tube welding notch is arranged, and the water-cooled wall tube is welded and connected to the wall plate at the position of the water-cooled wall tube welding notch.

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