Combined horizontal air preheater

Abstract

The utility model relates to air preheater technical field, concretely is a combined horizontal air preheater, including air preheater main part, air preheater main part is provided with several, this combined horizontal air preheater adopts the arrangement mode of flue gas horizontal vertical direct -through, air vertical stand -in stand -out, thoroughly solves the problem of air flow distribution unevenness caused by temperature gradient when air turning in traditional horizontal flow channel, ensures that each flow channel air temperature is consistent on horizontal section, and air flow distribution is even, the spoiler finned tube weakens fluid boundary layer through spoiler in the pipe, and the heat exchange area is expanded outside the pipe fin, and the concave-convex point heat exchange sheet is enhanced fluid turbulence degree through the concave-convex point of reverse pressing, improves Reynolds number, and the heat exchange effect of two kinds of core heat exchange elements is strengthened, and the actual heat exchange efficiency of preheater is significantly improved with the customization design of flow channel spacing, satisfies the high temperature heat exchange demand of converter waste heat recovery.

Description

Technical Field

[0001] This utility model relates to the field of air preheater technology, specifically a combined horizontal air preheater. Background Technology

[0002] Air preheaters are used to reduce the exhaust gas temperature of the furnace. The furnace's thermal efficiency is directly linked to the exhaust gas temperature; reducing the exhaust gas temperature minimizes unnecessary heat loss and improves furnace thermal efficiency. Increasing the combustion air temperature in the furnace burners improves the rate of fuel combustion and burnout, thereby reducing fuel consumption.

[0003] Existing horizontal converter air preheaters mostly adopt a horizontal straight-through flow of flue gas and a horizontal side-entry and horizontal-exit air configuration. The biggest problem with this configuration is that air is a cold medium, and its temperature rises during the flow process due to heat absorption. Taking a plate-type heat exchange module as an example, the air and flue gas side channels are horizontal. When the air flows through a turning point, due to the cross-heat exchange between air and flue gas, the air temperature changes in a gradient across a vertical cross-section. Furthermore, because the density rises slightly at higher temperatures and falls significantly at lower temperatures, the airflow distribution becomes severely uneven when the air turns to enter the next stage, thus affecting the overall heat exchange performance of the preheater and preventing it from meeting the standards. Due to the process characteristics of converter units, unlike the waste heat recovery systems of cylindrical (square) furnaces such as atmospheric and vacuum distillation furnaces, coking furnaces, hydrogenation furnaces, and reforming furnaces, the flue gas / air ratio cannot be controlled between 1.05 and 1.1. In conventional converter waste heat recovery systems, the flue gas / air ratio is typically around 1.25-1.3. Compared to other systems, the flue gas volume in a converter waste heat recovery system is much greater than the air volume. This necessitates a more rational structural design for the converter preheater to prevent internal leakage. This is because the flue gas volume in a converter is inherently much larger than the air volume, and the flue gas volume fluctuates significantly (the designed air volume is much smaller than the flue gas volume, and large fluctuations on the flue gas side will make it difficult to lower the flue gas temperature). Furthermore, conventional cylindrical / square furnace systems are mostly bottom-fired with top-out flue gas and are equipped with convection sections, typically using preheated air. The flue gas temperature in the air preheater is maintained within the range of 200-380℃. Within this range, the thermal stress caused by the thermal expansion of the core heat exchange elements is relatively small, and in most cases, it can be avoided through the flexible deformation of the material itself. However, for the converter, taking a hydrogen production unit as an example, its process characteristics determine that the temperature of the flue gas entering the high-temperature section of the preheater is relatively high, generally between 700-750℃. This temperature is much higher than the flue gas heat exchange temperature of waste heat recovery systems in general units. This means that if the high-temperature preheater does not have good thermal stress compensation capabilities, it is very easy for the high-temperature heat exchange components to twist and deform, leading to leakage. Once a leak occurs, due to the positive pressure on the air side and the negative pressure on the flue gas side, a large amount of air will leak to the flue gas side, further increasing the ratio between the two. Ultimately, this results in the flue gas outlet temperature falling far short of the designed cooling requirements, causing significant heat loss and severely affecting the overall furnace efficiency. Utility Model Content

[0004] In view of the problems existing in the prior art, this utility model discloses a combined horizontal air preheater. The technical solution adopted is as follows: it includes an air preheater body, and several air preheater bodies are arranged. The flue gas inlets and flue gas outlets of the several air preheater bodies are horizontally connected. The air inlets and air outlets of two adjacent air preheater bodies are connected by an air pipe. The air preheater body includes a shell, and a heat exchange module is installed inside the shell. The heat exchange module includes a finned tube heat exchange core and a plate heat exchange core. One end of the heat exchange module is fixedly connected to the inner side of one end of the shell, and the other end of the heat exchange module is fixedly connected to one end of an expansion joint. The other end of the expansion joint is fixedly connected to the inner side of the other end of the shell.

[0005] As a preferred embodiment of this utility model, the finned tube heat exchanger core includes a stuffing box, an end tube sheet, a finned tube, a gland, a weld ring, a sealing packing, and a second end tube sheet. The side of the end tube sheet is fixedly connected to the end face of one end of the expansion joint, and the side of the expansion joint is fixedly connected to the inner side of one end of the shell air inlet side. The side of the end of the stuffing box is circumferentially welded to the end tube sheet to form a weld ring. One end of the finned tube is inserted into the stuffing box. The gap between the finned tube and the stuffing box is filled with sealing packing. A gland is fitted onto the end of the finned tube. The side of the gland is fixedly connected to the inner side of the stuffing box and presses the sealing packing into the gap between the stuffing box and the finned tube. The side of the second end tube sheet is fixedly connected to the inner side of one end of the shell air outlet side. The other end of the finned tube passes through a through hole on the side of the second end tube sheet and is circumferentially welded to the second end tube sheet to form a weld ring.

[0006] As a preferred technical solution of this utility model, the plate-type heat exchange core is a concave-convex point heat exchange plate or a cast iron heat exchange plate. One end of the plate-type heat exchange core is fixedly connected to the inner side of one end of the shell, and the other end is fixedly connected to the inner side of the other end of the shell through an expansion joint.

[0007] As a preferred technical solution of this utility model, the plate-type heat exchange core uses a concave-convex point heat exchange plate when the flue gas temperature is above 120°C, and a cast iron heat exchange plate when the flue gas temperature is below 120°C.

[0008] As a preferred embodiment of this utility model, a number of reinforcing ribs are fixedly connected to the side of the cast iron heat exchange plate.

[0009] As a preferred embodiment of this utility model, the sealing packing is a graphite packing.

[0010] The beneficial effects of this utility model are as follows: 1. This utility model adopts a horizontal and vertical straight-through flue gas and vertical air inlet and outlet arrangement, which completely solves the problem of uneven airflow distribution caused by temperature gradient when air turns in traditional horizontal flow channels, ensuring that the air temperature in each flow channel on the transverse section is consistent and the airflow distribution is uniform; the finned tube with turbulence weakens the fluid boundary layer through the turbulence inside the tube and expands the heat exchange area through the fins outside the tube, and the concave and convex point heat exchange plate enhances the degree of fluid turbulence and increases the Reynolds number through the concave and convex points of reverse pressing. Both of the core heat exchange elements enhance the heat exchange effect. Combined with the customized design of the flow channel spacing, the actual heat exchange efficiency of the preheater is significantly improved, meeting the high-temperature heat exchange requirements of the waste heat recovery of the conversion furnace.

[0011] 2. The finned tube heat exchanger core uses a combination of a fixed second end tube sheet, a movable end tube sheet, and an expansion joint. The hot end is sealed with a sealed packing gland to achieve axial expansion and contraction compensation of the heat exchange tube. The concave-convex plate core has an end expansion joint on one side, which can absorb axial and longitudinal thermal stress. Both schemes avoid the twisting and deformation of heat exchange components at high temperatures, fundamentally solving the internal leakage problem caused by thermal expansion in traditional preheaters, preventing air leakage from positive pressure on the air side to negative pressure on the flue gas side, ensuring a stable flue gas-air ratio, and avoiding the expansion of heat loss.

[0012] 3. The low-temperature section uses a special cast iron flat plate heat exchange element, which can effectively resist dew point corrosion at exhaust temperatures of 120℃ and below. The flat plate structure is not prone to scale buildup and blockage, solving the core pain point of heat exchange in the low-temperature section. By flexibly adjusting the distance between the flue gas and the air flow channel in the low-temperature section, a reasonable flow velocity matching can be achieved, so that the extreme exhaust temperature can be reduced to below 120℃, further improving the waste heat recovery efficiency and reducing energy waste. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0014] Figure 2 This is a schematic cross-sectional view of the main body of the air preheater of this utility model;

[0015] Figure 3 This is a schematic diagram of the cross-sectional structure of the finned tube heat exchanger core of this utility model.

[0016] Figure 4 This is a partially enlarged structural diagram of point A in this utility model;

[0017] Figure 5 This is a partially enlarged structural diagram of section B of the present invention;

[0018] Figure 6 This is a partially enlarged structural diagram of point C in this utility model;

[0019] Figure 7This is a schematic diagram of the cross-sectional structure of the plate-type heat exchange core of this utility model;

[0020] Figure 8 This is a partially enlarged structural diagram of point D in this utility model;

[0021] Figure 9 This is a schematic diagram of the concave-convex point heat exchange plate structure of this utility model;

[0022] Figure 10 This is a schematic diagram of the cast iron heat exchange plate structure of this utility model.

[0023] In the figure: 1 Air preheater body, 101 Shell, 2 Heat exchange module, 21 Turbine finned tube heat exchange core, 211 Stuffing gland, 212 End tube sheet, 213 Turbine finned tube, 214 Pressure cap, 215 Weld ring, 216 Sealing packing, 217 Second end tube sheet, 22 Plate heat exchange core, 221 Concave-convex point heat exchange plate, 222 Cast iron heat exchange plate, 3 Expansion joint, 4 Reinforcing rib, 5 Air pipe. Detailed Implementation

[0024] Example 1

[0025] like Figures 1 to 10As shown, this utility model discloses a combined horizontal air preheater. The technical solution adopted is as follows: it includes an air preheater body 1, which is provided with several air preheater bodies 1. The flue gas inlets and outlets of the several air preheater bodies 1 are horizontally connected. The air inlets and outlets of two adjacent air preheater bodies 1 are connected by air pipes 5. The air preheater body 1 includes a shell 101. A heat exchange module 2 is installed inside the shell 101. The heat exchange module 2 includes a finned tube heat exchange core 21 and a plate heat exchange core 22. One end of the heat exchange module 2 is fixedly connected to the inner side of one end of the shell 101, and the other end of the heat exchange module 2 is fixedly connected to the inner side of one end of the shell 101. One end of the expansion joint 3 is fixedly connected to the expansion joint 3, and the other end of the expansion joint 3 is fixedly connected to the inner side of the other end of the shell 101. The finned tube heat exchange core 21 includes a stuffing box 211, an end tube sheet 212, a finned tube 213, a gland 214, a weld ring 215, a sealing packing 216, and a second end tube sheet 217. The side of the end tube sheet 212 is fixedly connected to the end face of one end of the expansion joint 3, and the side of the expansion joint 3 is fixedly connected to the inner side of one end of the air inlet side of the shell 101. The side of the end of the stuffing box 211 is circumferentially welded to the end tube sheet 212 to form a weld ring 215. One end of the finned tube 213 is inserted into the stuffing box 211. The gap between the finned tube 213 and the stuffing box 211 is filled with sealing packing 216. A gland 214 is fitted onto the end of the finned tube 213. The side of the gland 214 is fixedly connected to the inner side of the stuffing box 211, pressing the sealing packing 216 into the gap between the stuffing box 211 and the finned tube 213. The side of the second end tube sheet 217 is fixedly connected to the inner side of one end of the air outlet of the shell 101. The other end of the finned tube 213 passes through a through hole on the side of the second end tube sheet 217 and is circumferentially welded to the second end tube sheet 217 to form a weld ring 215. The plate-type heat exchange core 22 is either a raised / concave point heat exchange plate 221 or a cast iron heat exchange plate 222. One end of the plate-type heat exchange core 22 is fixedly connected to the inner side of one end of the shell 101, and the other end is fixedly connected to the inner side of the other end of the shell 101 through the expansion joint 3. The plate-type heat exchange core 22 uses a concave-convex point heat exchange plate 221 when the flue gas temperature is above 120℃, and a cast iron heat exchange plate 222 when the flue gas temperature is below 120℃. Several reinforcing ribs 4 are fixedly connected to the side of the cast iron heat exchange plate 222. The arrangement of horizontal and vertical straight flue gas and vertical air inlet and outlet completely solves the problem of uneven airflow distribution caused by temperature gradient when the air turns in the traditional horizontal flow channel, ensuring that the air temperature of each flow channel on the transverse section is consistent and the airflow distribution is uniform.The finned tube 213 weakens the fluid boundary layer through internal turbulence and expands the heat transfer area through external fins. The concave-convex point heat exchange plate 221 enhances fluid turbulence and increases the Reynolds number through reverse-pressed concave-convex points. Both core heat exchange elements enhance heat exchange performance. Combined with the customized design of the flow channel spacing, the actual heat exchange efficiency of the preheater is significantly improved, meeting the high-temperature heat exchange requirements for waste heat recovery from the converter.

[0026] The working principle of this utility model is as follows: Several air preheater bodies 1 are connected in a horizontal series through the flue gas inlet and outlet to form a through flue gas channel. The air inlet and outlet of adjacent air preheater bodies 1 are connected through air pipes 5 to form an air circulation channel. During operation, the flue gas flows directly through each air preheater body 1 in a horizontal and vertical direction, while the air flows between each air preheater body 1 in a vertical inlet and outlet manner through the air pipes 5, which completely avoids the problem of uneven airflow distribution caused by the turning of the traditional horizontal flow channel. The high-temperature flue gas and the air exchange heat through the heat exchange module 2. In the high-temperature section (700-750℃), an air preheater with a finned tube heat exchange core 21 can be selected. The finned tube heat exchange core 21 is connected to the expansion joint 3 through the end tube plate 212. A weld ring 215 is formed by circumferential welding of the stuffing box 211 to the end tube plate 212. After the finned tube 213 is inserted into the stuffing box 211, the gap is filled with sealing packing 216, and then it is pressed and fixed by the gland 214 to achieve end sealing. The finned tube inside the tube weakens the fluid boundary layer, and the finned tube outside the tube expands the heat exchange area. In the high-temperature section, the flue gas temperature is high and the thermal stress is large. At this time, the expansion joint 3 can expand freely to release the tube plate temperature difference stress caused by the change of heat exchange temperature gradient. At the same time, the end of the finned tube 213 is sealed by the stuffing box 211 and the gland 214 to solve the individual temperature difference thermal stress of each tube at high temperature. The sealing packing 216 adopts The graphite packing, under the clamping force of the pressure cap 214, compresses and seals through its flexibility and self-lubricating properties, ensuring the sealing of the gaps and providing thermal stress compensation for the heat exchange tubes in the axial direction. In the low-temperature range (120-300℃), the plate-type heat exchange core 22 with concave-convex point heat exchange plate 221 is selected. The concave-convex point or plate structure with reverse pressing adapts to the heat exchange requirements of different temperature ranges. In the extreme flue gas temperature below 120℃, the cast iron heat exchange plate 222 with reinforcing ribs 4 fixed on the side is selected. By adjusting the spacing of the flue gas and air flow channels, the flue gas and air flow rates are matched. Due to the characteristics of its plate, it is not easy to accumulate scale and blockage in the low-temperature range. Ultimately, it achieves efficient heat exchange by gradually releasing heat from the high-temperature flue gas and continuously absorbing heat to raise the temperature of the air, ensuring a stable flue gas-air ratio and improving the overall furnace efficiency and waste heat recovery efficiency.

[0027] Components not described in detail in this article are existing technologies.

[0028] While the specific embodiments of this utility model have been described in detail above, this utility model is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of this utility model. Modifications or variations that do not involve creative labor are still within the protection scope of this utility model.

Claims

1. A combined horizontal air preheater, characterized in that, The system includes an air preheater body (1), which is provided in several parts. The flue gas inlets and outlets of the several air preheater bodies (1) are horizontally connected. The air inlets and outlets of two adjacent air preheater bodies (1) are connected by an air pipe (5). The air preheater body (1) includes a shell (101). A heat exchange module (2) is installed inside the shell (101). The heat exchange module (2) includes a finned tube heat exchange core (21) and a plate heat exchange core (22). One end of the heat exchange module (2) is fixedly connected to the inner side of one end of the shell (101). The other end of the heat exchange module (2) is fixedly connected to one end of an expansion joint (3). The other end of the expansion joint (3) is fixedly connected to the inner side of the other end of the shell (101).

2. The combined horizontal air preheater according to claim 1, characterized in that: The finned tube heat exchange core (21) includes a stuffing box (211), an end tube sheet (212), a finned tube (213), a gland (214), a weld ring (215), a sealing packing (216), and a second end tube sheet (217). The side of the end tube sheet (212) is fixedly connected to the end face of one end of the expansion joint (3). The side of the expansion joint (3) is fixedly connected to the inner side of one end of the air inlet side of the shell (101). The side of the end of the stuffing box (211) is circumferentially welded to the end tube sheet (212) to form a weld ring (215). One end of the finned tube (213) is inserted into the stuffing box (211). 3) The gap between the packing gland (211) and the stuffing box (211) is filled with sealing packing (216). The end of the finned tube (213) is fitted with a cap (214). The side of the cap (214) is fixedly connected to the inner side of the stuffing gland (211) and presses the sealing packing (216) into the gap between the stuffing gland (211) and the finned tube (213). The side of the second end plate (217) is fixedly connected to the inner side of one end of the air outlet of the housing (101). The other end of the finned tube (213) passes through the through hole on the side of the second end plate (217) and is welded to the circumference of the second end plate (217) to form a weld ring (215).

3. A combined horizontal air preheater according to claim 1, characterized in that: The plate-type heat exchange core (22) is a concave-convex point heat exchange plate (221) or a cast iron heat exchange plate (222). One end of the plate-type heat exchange core (22) is fixedly connected to the inner side of one end of the shell (101), and the other end is fixedly connected to the inner side of the other end of the shell (101) through an expansion joint (3).

4. A combined horizontal air preheater according to claim 3, characterized in that: The plate-type heat exchange core (22) uses a concave-convex point heat exchange plate (221) when the flue gas temperature is above 120°C, and a cast iron heat exchange plate (222) when the flue gas temperature is below 120°C.

5. A combined horizontal air preheater according to claim 3, characterized in that: Several reinforcing ribs (4) are fixedly connected to the side of the cast iron heat exchange plate (222).

6. A combined horizontal air preheater according to claim 2, characterized in that: The sealing packing (216) is a graphite packing.

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