Secondary heat exchanger for radiant tube burner
By designing a secondary heat exchanger in the radiant tube burner and utilizing annular baffles and circular baffle structures to extend the cold air flow path and enhance disturbance, the problem of insufficient heat exchange area of the heat exchanger is solved, achieving efficient heat recovery and improved thermal efficiency.
Patent Information
- Application Number
- CN202423051120.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-11
- Publication Date
- 2025-10-28
- Estimated Expiration
- 2034-12-11
AI Technical Summary
The heat exchange area of the heat exchanger of the existing radiant tube burner is limited, resulting in high temperature flue gas emission and low thermal efficiency.
A two-stage heat exchanger for radiant tube burners is designed. The structure adopts a flue gas inlet section, a flue gas outlet section, an inlet sealing plate and an outlet sealing plate. A plurality of through-hole heat exchange tubes are arranged in the shell. Combined with annular baffles and circular baffles, cold air flows through the central opening and the outer edge gaps, extending the flow distance, enhancing disturbance and improving heat exchange efficiency.
The design of the two-stage heat exchanger significantly improves the heat transfer coefficient and efficiency on the air side, avoids the problem of airflow dead zones, and achieves efficient heat recovery.
Smart Images
Figure CN223484264U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of heat exchanger technology, specifically to a two-stage heat exchanger for radiant tube burners. Background Technology
[0002] Radiant tube heating is widely used in many applications requiring specific furnace atmospheres. Common radiant tubes include W-type, U-type, and linear radiant tubes. In practical applications, both W-type and U-type radiant tubes place the burner at one end and the heat exchanger at the other. Combustion air first enters the heat exchanger, exchanges heat with the high-temperature flue gas generated by combustion, and then enters the burner as combustion air, thus achieving heat recovery. The specific process is as follows: Figure 1 As shown.
[0003] The linear radiant tube burner integrates the burner and heat exchanger into one unit. After entering the burner, the combustion air first exchanges heat with the high-temperature flue gas through the integrated heat exchanger, preheating it before mixing it with the fuel gas and igniting it for combustion, thus achieving heat recovery. Specifically, as shown below... Figure 2 As shown.
[0004] Due to the size limitations of radiant tubes, the heat exchange area of both types of heat exchangers is very limited. Even after adding fins on both sides of the heat exchanger, the final exhaust temperature of the flue gas is still very high in some high-temperature heat treatment furnaces. For example, in conventional carbon steel strip continuous annealing furnaces or thick plate quenching roller hearth furnaces, the final exhaust temperature is basically above 600℃. These high-temperature flue gases carry away a large amount of heat generated by fuel combustion, resulting in low thermal efficiency of these furnaces. Utility Model Content
[0005] The purpose of this invention is to provide a two-stage heat exchanger for radiant tube burners, which has high heat exchange efficiency.
[0006] To solve the above-mentioned technical problems, the present invention adopts the following solution:
[0007] A two-stage heat exchanger for a radiant tube burner includes a shell, a flue gas inlet section for receiving flue gas discharged from the radiant tube, and a flue gas outlet section for discharging the flue gas. A heat exchange section is provided between the flue gas inlet section and the flue gas outlet section. An inlet sealing plate is provided between the flue gas inlet section and the heat exchange section, and an outlet sealing plate is provided between the flue gas outlet section and the heat exchange section. Multiple heat exchange tubes are disposed within the shell, penetrating the inlet sealing plate and the outlet sealing plate. A cold air inlet and a hot air outlet are connected to the heat exchange section. The heat exchange tubes are sealed to the inlet sealing plate and to the outlet sealing plate. Its function is to allow high-temperature flue gas to enter the shell from the flue gas inlet section, then be cooled by heat exchange tubes and discharged from the flue gas outlet section by setting up the flue gas inlet section, flue gas, inlet and outlet sealing plates, and cold air inlet and hot air outlet on the heat exchange section. At the same time, cold air enters the heat exchange section from the cold air inlet to cool the heat exchange tubes in the heat exchange section, and the hot air discharged from the hot air outlet after heat exchange.
[0008] Furthermore, the heat exchange section is equipped with multiple annular baffles and circular baffles at intervals. These annular baffles and circular baffles are coaxially arranged, with the outer diameter of the circular baffles being smaller than that of the annular baffles. Both the annular and circular baffles have through holes for the heat exchange tubes to pass through. The annular and circular baffles are welded to the heat exchange tubes. Their function is to allow cold air to sequentially pass through the central opening of the annular baffle and the gap between the outer edge of the circular baffle and the inner wall of the heat exchange section. This allows the cold air to pass through all the heat exchange tubes distributed both internally and externally, extending the flow path of the cold air, enhancing its turbulence, avoiding the dead zone problem of conventional flue-tube heat exchangers, and greatly improving the heat transfer coefficient on the air side, thereby significantly increasing the heat exchange efficiency.
[0009] Furthermore, the outer diameter of the annular baffle is the same as the inner diameter of the heat exchange section. Its function is to ensure that, through the design of the dimensional relationship between the annular baffle and the heat exchange section, the airflow passing through the annular baffle can only pass through the opening at the center of the annular baffle.
[0010] Furthermore, the annular baffles are evenly spaced from each other. This uniform spacing ensures that the cold air flows evenly within the heat exchange section, resulting in better cooling for all sections along the length of the heat exchange tubes.
[0011] Furthermore, the inner diameter of the annular baffle is smaller than the outer diameter of the circular baffle. Its function is that, through the design of the dimensional relationship between the annular baffle and the circular baffle, cold air, after passing through the central opening of the annular baffle, diffuses outward a certain distance before passing through the circular baffle, thus achieving heat exchange with the outermost heat exchange tubes; conversely, cold air, after passing through the outer edge of the circular baffle, diffuses inward a certain distance before passing through the annular baffle, thus achieving heat exchange with the innermost heat exchange tubes.
[0012] Furthermore, the number of the annular partitions is one more than the number of the circular partitions.
[0013] Furthermore, the cold air inlet is located between the outlet sealing plate and the nearest annular baffle, while the hot air outlet is located between the inlet sealing plate and the nearest annular baffle. This design, through the numerical relationship between the annular baffles and their spatial arrangement, as well as the spatial relationship between the cold air inlet and hot air outlet within the casing, ensures that the cold air, upon entering the heat exchange section, first travels towards the center of the section before passing through the annular baffles. This allows the cold air to exchange heat with both the outer and inner heat exchange tubes upon entering the section, resulting in excellent heat exchange performance.
[0014] Furthermore, the angle between the cold air inlet and the hot air outlet is 180°.
[0015] Furthermore, the heat exchange tubes are evenly distributed in a circular array. This ensures uniform heat exchange across all areas within the heat exchange section.
[0016] Furthermore, at least one of the heat exchange tubes is simultaneously connected to both the circular partition and the annular partition. At least one heat exchange tube is connected only to the circular partition, and at least one heat exchange tube is connected only to the annular partition. This arrangement, by connecting the heat exchange tubes simultaneously to both the circular and annular partitions, improves the heat exchange effect, as both partitions and annular partitions also exchange heat. Furthermore, since the heat exchange tubes connected to both partitions are located in the middle layer of all heat exchange tubes, the heat exchange effect is enhanced from the middle layer inwards and outwards.
[0017] The beneficial effects of this utility model are:
[0018] 1. By setting up the flue gas inlet section, flue gas outlet section, inlet sealing plate and outlet sealing plate, and setting the cold air inlet and hot air outlet on the heat exchange section, the high-temperature flue gas enters the shell from the flue gas inlet section, then passes through the heat exchange tubes for heat exchange and cooling, and is discharged from the flue gas outlet section. At the same time, cold air enters the heat exchange section from the cold air inlet to exchange heat and cool the heat exchange tubes in the heat exchange section. The hot air after heat exchange is discharged from the hot air outlet.
[0019] 2. By setting up the annular baffle and the circular baffle, cold air can pass through the central opening of the annular baffle and the gap between the outer edge of the circular baffle and the inner wall of the heat exchange section in sequence. This allows the cold air to pass through all the heat exchange tubes distributed inside and outside, extending the flow path of the cold air, strengthening the turbulence of the cold air, avoiding the airflow dead zone problem of conventional flue tube heat exchangers, greatly improving the heat transfer coefficient on the air side, and thus significantly improving the heat exchange efficiency.
[0020] 3. By setting up heat exchange tubes that are simultaneously connected to both circular and annular partitions, the heat exchange effect of the heat exchange tubes passing through both circular and annular partitions is better. Furthermore, since the heat exchange tubes connected to both circular and annular partitions are located in the middle layer of all heat exchange tubes, the heat exchange effect can be improved from the middle layer inwards and outwards. Attached Figure Description
[0021] Figure 1 This is a schematic diagram of the structure of a U-shaped radiating tube in the prior art;
[0022] Figure 2 This is a schematic diagram of the structure of a linear radiant tube in the prior art;
[0023] Figure 3 This is a schematic diagram of the structure of Example 1;
[0024] Figure 4 This is a schematic diagram of the annular partition in Example 1;
[0025] Figure 5 This is a schematic diagram of the circular partition in Example 1;
[0026] Figure 6 This is a schematic diagram of the structure in use when installed on a U-shaped radiating tube, as shown in Example 1.
[0027] Figure 7 This is a schematic diagram of the structure in use when installed on a linear radiant tube, as shown in Example 1.
[0028] Reference numerals: 1. Shell; 2. Flue gas inlet section; 3. Flue gas outlet section; 4. Heat exchange section; 5. Inlet sealing plate; 6. Outlet sealing plate; 7. Heat exchange tube; 8. Cold air inlet; 9. Hot air outlet; 10. Circular baffle; 11. Circular baffle; 12. Through hole; 13. Gas inlet; 14. Flue gas outlet; 15. Air inlet; a. Gas; b. Cold air; c. Flue gas; d. Preheated air. Detailed Implementation
[0029] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.
[0030] In the description of this utility model, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "longitudinal", "lateral", "horizontal", "inner", "outer", "front", "rear", "top", "bottom", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the utility model product is in use. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.
[0031] In the description of this utility model, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set up," "have," "install," "connect," and "connect" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.
[0032] Example 1
[0033] A two-stage heat exchanger for radiant tube burners, such as Figure 3 As shown, the device includes a housing 1, a flue gas inlet section 2 for receiving flue gas c discharged from the radiant tube, and a flue gas outlet section 3 for discharging flue gas c. A heat exchange section 4 is provided between the flue gas inlet section 2 and the flue gas outlet section 3. An inlet sealing plate 5 is provided between the flue gas inlet section 2 and the heat exchange section 4, and an outlet sealing plate 6 is provided between the flue gas outlet section 3 and the heat exchange section 4. Multiple heat exchange tubes 7 are provided inside the housing 1, penetrating the inlet sealing plate 5 and the outlet sealing plate 6. A cold air inlet 8 and a hot air outlet 9 are connected to the heat exchange section 4. The heat exchange tubes 7 are sealed to the inlet sealing plate 5 and to the outlet sealing plate 6. Its function is to allow the high-temperature flue gas c to enter the shell 1 from the flue gas inlet section 2 through the arrangement of the flue gas inlet section 2, the flue gas outlet section 3, the inlet sealing plate 5 and the outlet sealing plate 6, and the design of setting the cold air inlet 8 and the hot air outlet 9 on the heat exchange section 4, so that the high-temperature flue gas c enters the shell 1 from the flue gas inlet section 2, is cooled by heat exchange tube 7, and is discharged from the flue gas outlet section 3. At the same time, the cold air b enters the heat exchange section 4 from the cold air inlet 8 to cool the heat exchange tube 7 in the heat exchange section 4, and the hot air after heat exchange is discharged from the hot air outlet 9.
[0034] Specifically, such as Figure 3 As shown, the heat exchange section 4 is provided with multiple annular baffles 10 and circular baffles 11 spaced apart. The annular baffles 10 and circular baffles 11 are coaxially arranged, and the outer diameter of the circular baffle 11 is smaller than the outer diameter of the annular baffle 10. Figure 4 , Figure 5 As shown, both the annular baffle 10 and the circular baffle 11 are provided with through holes 12 for the heat exchange tubes 7 to pass through. Both the annular baffle 10 and the circular baffle 11 are welded to the heat exchange tubes 7. Their function is to allow cold air b to pass sequentially through the central opening of the annular baffle 10 and the gap between the outer edge of the circular baffle 11 and the inner wall of the heat exchange section 4, thus enabling the cold air b to pass through all the heat exchange tubes 7 distributed both internally and externally. This extends the flow path of the cold air b, strengthens the turbulence of the cold air b, avoids the airflow dead zone problem of conventional flue-tube heat exchangers, greatly improves the heat transfer coefficient on the air side, and thus significantly improves the heat exchange efficiency.
[0035] Specifically, such as Figure 3 As shown, the outer diameter of the annular baffle 10 is the same as the inner diameter of the heat exchange section 4. Its function is to ensure that the airflow passing through the annular baffle 10 can only pass through the opening at the center of the annular baffle 10 through the design of the dimensional relationship between the annular baffle 10 and the heat exchange section 4.
[0036] Specifically, such as Figure 3 As shown, the annular partition 10 and the circular partition 11 are evenly spaced. Their function is that, through the uniform spacing between the annular partition 10 and the circular partition 11, the cold air b can flow evenly within the heat exchange section 4, resulting in a better cooling effect on each section along the length of the heat exchange tube 7.
[0037] Specifically, such as Figure 3 As shown, the inner diameter of the annular partition 10 is smaller than the outer diameter of the circular partition 11. Its function is that, through the design of the dimensional relationship between the annular partition 10 and the circular partition 11, cold air b, after passing through the central opening of the annular partition 10, diffuses outward a certain distance before reaching the circular partition 11, thus achieving heat exchange with the outermost heat exchange tube 7; conversely, cold air b, after passing through the outer edge of the circular partition 11, diffuses inward a certain distance before reaching the annular partition 10, thus achieving heat exchange with the innermost heat exchange tube 7.
[0038] Specifically, such as Figure 3 As shown, the number of annular partitions 10 is one more than the number of circular partitions 11.
[0039] Specifically, such as Figure 3As shown, the cold air inlet 8 is located between the outlet sealing plate 6 and the annular partition 10 closest to the outlet sealing plate 6, and the hot air outlet 9 is located between the inlet sealing plate 5 and the annular partition 10 closest to the inlet sealing plate 5. Its function is to, through the design of the numerical relationship between the annular partitions 10 and 11, the spatial relationship of the annular partitions 10 and 11, and the spatial relationship between the cold air inlet 8 and the hot air outlet 9 within the shell 1, ensure that after the cold air b enters the heat exchange section 4, it first travels towards the middle of the heat exchange section 4 and then passes through the annular partition 10. This allows the cold air b to exchange heat with both the outer and inner heat exchange tubes 7 upon entering the heat exchange section 4, resulting in a good heat exchange effect.
[0040] Specifically, such as Figure 3 As shown, the angle between the cold air inlet 8 and the hot air outlet 9 is 180°.
[0041] Specifically, such as Figure 3 As shown, the heat exchange tubes 7 are evenly distributed in a circular array. Their function is to ensure uniform heat exchange in all areas within the heat exchange section 4.
[0042] Specifically, such as Figure 3 As shown, at least one heat exchange tube 7 is simultaneously connected to both the circular partition 11 and the annular partition 10. At least one heat exchange tube 7 is connected only to the circular partition 11, and at least one heat exchange tube 7 is connected only to the annular partition 10. This arrangement, by connecting the heat exchange tube 7 to both the circular partition 11 and the annular partition 10, ensures better heat exchange efficiency, as both the circular partition 11 and the annular partition 10 also exchange heat. Furthermore, since the heat exchange tube 7 connected to both the circular partition 11 and the annular partition 10 is located in the middle layer of all the heat exchange tubes 7, it enhances the heat exchange effect from the middle layer inwards and outwards.
[0043] The application scenario of this embodiment is described as follows: The flue gas inlet section 2 is connected to the flue gas outlet 14 of the U-shaped radiant tube, and the hot air outlet 9 is connected to the air inlet 15 of the U-shaped radiant tube. The heat exchange section 4 performs secondary heat exchange on the flue gas c after the first heat exchange through the U-shaped radiant tube, which further improves the overall heat exchange effect. The hot air after heat exchange can be transported back into the U-shaped radiant tube from the air inlet 15 of the U-shaped radiant tube as preheated air d and mixed with the gas a input from the gas inlet 13.
[0044] The flue gas inlet section 2 is connected to the flue gas outlet 14 of the straight radiant tube, and the hot air outlet 9 is connected to the air inlet 15 of the straight radiant tube. The heat exchange section 4 performs secondary heat exchange on the flue gas c after the first heat exchange through the straight radiant tube, which further improves the overall heat exchange effect. The hot air after heat exchange can be transported back into the straight radiant tube from the air inlet 15 of the straight radiant tube as preheated air d and mixed with the gas a input from the gas inlet 13.
[0045] The working principle of this embodiment is explained as follows: After the secondary heat exchanger is installed at the flue gas outlet 14 of the radiant tube system, the high-temperature flue gas c enters from the flue gas inlet section 2 of the secondary heat exchanger, passes through the heat exchange tubes 7 and is discharged to the flue gas outlet section 3. Cold air b enters from the cold air b inlet on the shell 1 into the gap between the heat exchange tubes 7 inside the heat exchange section 4. Due to the obstruction of the annular baffle 10, the cold air b flows downward through the bundle of heat exchange tubes 7 from the central opening (circular hole) of the annular baffle 10. Due to the obstruction of the circular baffle 11, this cold air b flows downward along the space around the annular baffle 11 after passing through the bundle of heat exchange tubes 7 again, and then encounters the next stage annular baffle 10. This cycle repeats until it flows out from the hot air outlet 9. When cold air b flows across the bundles of heat exchange tubes 7, it exchanges heat with the high-temperature flue gas c inside the heat exchange tubes 7 through the tube walls. The temperature of the high-temperature flue gas c decreases, and the temperature of the cold air b increases, thus achieving high-efficiency heat recovery. The air, preheated by the secondary heat exchanger, continues to enter the primary heat exchanger in the radiant tube burner system to continue exchanging heat with the high-temperature flue gas c, resulting in an even higher air preheating temperature, thereby achieving efficient recovery and utilization of the heat from the flue gas c.
[0046] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model in any way. Any simple modifications, equivalent substitutions, and improvements made to the above embodiments based on the technical essence of the present utility model and within the spirit and principles of the present utility model shall still fall within the protection scope of the present utility model.
Claims
1. A two-stage heat exchanger for a radiant tube burner, characterized in that: The device includes a housing (1), a flue gas inlet section (2) for inputting flue gas discharged from the radiant tube and a flue gas outlet section (3) for discharging flue gas. A heat exchange section (4) is provided between the flue gas inlet section (2) and the flue gas outlet section (3). An inlet sealing plate (5) is provided between the flue gas inlet section (2) and the heat exchange section (4). An outlet sealing plate (6) is provided between the flue gas outlet section (3) and the heat exchange section (4). Multiple heat exchange tubes (7) are provided inside the housing (1) and pass through the inlet sealing plate (5) and the outlet sealing plate (6). A cold air inlet (8) and a hot air outlet (9) are connected to the heat exchange section (4).
2. A two-stage heat exchanger for a radiant tube burner according to claim 1, characterized in that: The heat exchange section (4) is provided with multiple annular baffles (10) and circular baffles (11) spaced apart. The annular baffles (10) and circular baffles (11) are coaxially arranged. The outer diameter of the circular baffle (11) is smaller than the outer diameter of the annular baffle (10). Both the annular baffles (10) and the circular baffles (11) are provided with through holes (12) for the heat exchange tubes (7) to pass through.
3. A two-stage heat exchanger for a radiant tube burner according to claim 2, characterized in that: The outer diameter of the annular partition (10) is the same as the inner diameter of the heat exchange section (4).
4. A two-stage heat exchanger for a radiant tube burner according to claim 2, characterized in that: The annular partition (10) and the circular partition (11) are evenly spaced.
5. A two-stage heat exchanger for a radiant tube burner according to claim 2, characterized in that: The inner diameter of the annular partition (10) is smaller than the outer diameter of the circular partition (11).
6. A two-stage heat exchanger for a radiant tube burner according to claim 2, characterized in that: The number of the annular partitions (10) is one more than the number of the circular partitions (11).
7. A two-stage heat exchanger for a radiant tube burner according to claim 6, characterized in that: The cold air inlet (8) is located between the outlet sealing plate (6) and the annular partition (10) closest to the outlet sealing plate (6), and the hot air outlet (9) is located between the inlet sealing plate (5) and the annular partition (10) closest to the inlet sealing plate (5).
8. A two-stage heat exchanger for a radiant tube burner according to claim 1, characterized in that: The angle between the cold air inlet (8) and the hot air outlet (9) is 180°.
9. A two-stage heat exchanger for a radiant tube burner according to claim 2, characterized in that: The heat exchange tubes (7) are evenly distributed in a circular array.
10. A two-stage heat exchanger for a radiant tube burner according to claim 9, characterized in that: At least one of the heat exchange tubes (7) is connected to both the circular partition (11) and the annular partition (10).