Plate heat exchanger for hot rolling heating furnace in iron and steel industry

Abstract

The utility model discloses a plate heat exchanger for a hot rolling heating furnace in the iron and steel industry. The plate heat exchanger is provided with a cold side outlet air bellow, a cold side inlet air bellow, a hot side inlet, a hot side outlet, a bottom air flue and two heat exchange assemblies. The heat exchange assembly comprises a plurality of heat exchange assembly units arranged side by side, each heat exchange assembly unit comprises two sheets, a heat exchange area is arranged in the middle of each sheet, the two ends of each heat exchange area are each provided with a windward area and a welding area, the included angle between each windward area and the corresponding welding area is 30-45 degrees, the two sheets are connected through the welding areas in a pressure welding mode, and a cold side channel is formed between the two sheets. A hot side channel is formed between every two adjacent heat exchange assembly units. The cold side outlet air box and the cold side inlet air box are arranged above the two heat exchange assemblies correspondingly, and the lower portions of the two heat exchange assemblies communicate with each other through a bottom air duct. Smoke sequentially passes through the hot side inlet, one heat exchange assembly, the other heat exchange assembly and the hot side outlet. The heat exchanger is not easy to accumulate dust, good in heat exchange performance and capable of meeting long-term safe and stable operation requirements of the hot rolling heating furnace.

Description

Technical Field

[0001] This utility model relates to plate heat exchangers, specifically to a plate heat exchanger used in hot rolling heating furnaces in the steel industry. Background Technology

[0002] In the steel industry, hot rolling furnaces are equipped with air preheaters and gas preheaters to recover waste heat from high-temperature flue gas. The heated air and gas are then returned to the furnace. Currently, both air and gas preheaters use tubular heat exchangers. However, due to severe ash accumulation in these tubular heat exchangers, their heat exchange efficiency has been decreasing year by year, directly affecting the furnace's thermal efficiency and safe operation. In actual production, the air preheating temperature is low, resulting in a high flue gas temperature exiting the air preheater. Even when using dilution fans to introduce cold air into the flue to lower the temperature, the gas preheating temperature in the subsequent gas preheater often reaches above 320°C, triggering an over-temperature alarm (the gas over-temperature alarm temperature is 320°C). This increases the frequency of dilution fan operation, increases power consumption, wastes waste heat from the flue gas, and poses significant safety hazards. Utility Model Content

[0003] Purpose of the utility model: The purpose of this utility model is to provide a plate heat exchanger for hot rolling heating furnaces in the steel industry that can maintain excellent heat exchange performance in high temperature and high dust environments and is not prone to clogging and dust accumulation, so as to ensure the long-term safe and stable operation of the hot rolling heating furnace.

[0004] Technical solution: The present invention provides a plate heat exchanger for a hot rolling heating furnace in the steel industry, comprising a cold-side outlet air box, a cold-side inlet air box, a hot-side inlet, a hot-side outlet, a bottom air duct, and two sets of heat exchange components.

[0005] The heat exchange assembly includes several heat exchange assembly units arranged side by side. Each heat exchange assembly unit includes two plates, with a heat exchange zone in the middle. Both ends of the heat exchange zone are provided with a windward zone and a welding zone. The windward zone is located between the heat exchange zone and the welding zone, and the included angle between the windward zone and the welding zone is 30° to 45°. The two plates are pressure welded together to form a heat exchange assembly unit. A cold-side channel is formed between the two plates, and a hot-side channel is formed between adjacent heat exchange assembly units.

[0006] The cold-side outlet air box and the cold-side inlet air box are respectively installed above the two sets of heat exchange components, and the two sets of heat exchange components are connected below by a bottom air duct; the flue gas passes sequentially through the hot-side inlet, one set of heat exchange components, the other set of heat exchange components, and the hot-side outlet.

[0007] Furthermore, the outer wall of the windward area is evenly distributed with several raised patterns from top to bottom. The raised patterns have horizontal sections and settling sections. The angle between the settling sections and the horizontal sections is 30° to 45°, and the junction of the horizontal sections and the settling sections is smoothly transitioned.

[0008] Furthermore, the heat exchange area is divided into a heat exchange enhancement section and a flat plate section arranged at intervals from top to bottom. The heat exchange enhancement section has several first protrusions evenly distributed on one side of the hot side channel, and several second protrusions evenly distributed on one side of the cold side channel.

[0009] Furthermore, the number of first protrusions is less than that of second protrusions, and the size of the first protrusions is larger than that of the second protrusions.

[0010] Furthermore, the settling section of the raised pattern remains flush with the flat section of the heat exchange zone in terms of height.

[0011] Furthermore, wear-resistant coatings are applied to both sides of the heat exchange zone and the windward zone.

[0012] Furthermore, the cold-side outlet air box and the cold-side inlet air box are respectively connected to the heat exchange components through an expansion structure.

[0013] Furthermore, the hot and cold media exchange heat in a countercurrent manner.

[0014] Furthermore, the plate is made of stainless steel with a thickness of 1.0 mm or more.

[0015] Furthermore, the number of plate heat exchangers is multiple, and they are modularly arranged in the tunnel; the number of plate heat exchangers is determined according to the requirements and the size of the tunnel.

[0016] Beneficial effects: Compared with the prior art, this utility model has the following advantages:

[0017] (1) Because the windward area is set at a certain angle, it blocks the airflow less than a right angle and is less prone to dust accumulation;

[0018] (2) Plate heat exchangers have better heat exchange efficiency than tube heat exchangers, and because they are less prone to dust accumulation, they can ensure long-term stable heat exchange requirements.

[0019] (3) It has a compact structure and occupies only about one-third of the area of ​​a tubular heat exchanger, making it particularly suitable for the limited space requirements of heating furnace tunnels. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the plate heat exchanger placed in a tunnel according to an embodiment of the present invention;

[0021] Figure 2 yes Figure 1 The left view;

[0022] Figure 3 This is a top view of the heat exchange component unit in an embodiment of this utility model;

[0023] Figure 4 This is a front view of the heat exchange component unit in an embodiment of this utility model. Detailed Implementation

[0024] The present invention will be further described below with reference to the accompanying drawings.

[0025] Appendix Figures 1 to 4 The accompanying figure labels are as follows:

[0026] 1. Cold-side outlet air box; 2. Cold-side inlet air box; 3. Heat exchange component; 4. Expansion structure; 5. Bottom air duct; 6. Hot-side inlet; 7. Hot-side outlet; 8. Cold-side channel; 9. Hot-side channel; 10. Welding area; 11. Windward area; 12. Heat exchange area; 13. Rough texture; 14. First protrusion; 15. Second protrusion.

[0027] like Figures 1 to 2 As shown, this utility model embodiment provides a plate heat exchanger for a hot rolling heating furnace in the steel industry, which has a cold side outlet air box 1, a cold side inlet air box 2, a hot side inlet 6, a hot side outlet 7, a bottom air duct 5, and two sets of heat exchange components 3.

[0028] Heat exchange component 3 includes several heat exchange component units, such as Figure 3 and Figure 4 As shown, the heat exchange component unit includes two plates, with a heat exchange zone 12 in the middle. Both ends of the heat exchange zone 12 are provided with an air-facing zone 11 and a welding zone 10. The air-facing zone 11 is located between the heat exchange zone 12 and the welding zone 10. In this embodiment, the included angle between the air-facing zone 11 and the welding zone 10 is 30°. The two plates are pressure-welded together through the welding zone 10 to form the heat exchange component unit, creating a cold-side channel 8 between the two plates. Several heat exchange component units are arranged side-by-side and welded together to form a heat exchange component 3. A hot-side channel 9 is formed between adjacent heat exchange component units. The 30° included angle between the air-facing zone 11 and the welding zone 10 allows the flue gas to flow tangentially along the plates, greatly reducing the resistance of the air-facing zone 11 to the flue gas flow.

[0029] The heat exchange plates are made of stainless steel with a thickness of 1.0 mm or more. In the two sets of heat exchange components 3, the heat exchange component 3 closer to the hot-side inlet 6 uses 310S material with a thickness of 1.5 mm and a high temperature resistance of 1100℃. The heat exchange component 3 closer to the hot-side outlet 7 uses 321 material with a thickness of 1.2 mm. Stainless steel has good thermal conductivity; using different stainless steel materials for the two sets of heat exchange components 3 ensures better heat exchange efficiency while also being more economical.

[0030] The outer wall of the windward zone 11 is evenly distributed with several raised patterns 13 from top to bottom. The raised patterns 13 have horizontal sections and settling sections, with the settling sections forming an angle of 30° with the horizontal sections. The joint between the horizontal sections and the settling sections is smoothly transitioned. The function of the raised patterns 13 is to allow dust to settle and fall smoothly, further preventing dust accumulation and blockage, while also increasing the heat exchange area.

[0031] The heat exchange zone 12 is divided into a heat exchange enhancement section and a flat plate section arranged at intervals from top to bottom. The heat exchange enhancement section has several first protrusions 14 evenly distributed on one side of the hot-side channel 9, and several second protrusions 15 evenly distributed on one side of the cold-side channel 8. The number of first protrusions 14 is less than the number of second protrusions 15, and the size of the first protrusions 14 is larger than that of the second protrusions 15. The protrusions serve to create turbulence during flue gas and air flow, thereby enhancing heat transfer. Verification has shown that this turbulence-enhanced thin-plate heat exchanger, through turbulence, achieves a heat exchange efficiency nearly twice that of a conventional tubular heat exchanger, significantly improving heat exchange performance and substantially reducing gas consumption costs. However, the increase in pressure drop is not significant; the pressure drop on the hot side can be controlled within 400–500 Pa, and on the cold side within 1500 Pa.

[0032] The settling section of the raised texture 13 is flush with the flat plate section of the heat exchange zone 12 in terms of height, which facilitates a more uniform distribution of airflow as it passes over the plates, resulting in a more even distribution of airflow resistance when entering and exiting the plates and reducing flow deviation. The heat exchange zone 12 and the windward zone 11 are coated with a wear-resistant coating on both sides, with a thickness of 10-20 micrometers. The main components of the wear-resistant coating are ceramic materials such as silicon dioxide and alumina, balancing heat exchange and service life. The ceramic coating can prevent the wear of ash-containing hot flue gas on the stainless steel plates, increasing the service life of the equipment.

[0033] The cold-side outlet air box 1 and the cold-side inlet air box 2 are respectively installed above the two sets of heat exchange components 3, and are connected to the corresponding heat exchange components 3 through an expansion structure 4. The expansion structure 4 can provide a certain expansion margin to prevent the heat exchange components 3 from misaligning due to thermal expansion at high temperatures, which could crack the air duct plate. The two sets of heat exchange components 3 are connected below each other through a bottom air duct 5; the flue gas sequentially passes through the hot-side inlet 6, one set of heat exchange components 3, the other set of heat exchange components 3, and the hot-side outlet 7. In this embodiment, the hot and cold media exchange heat in a countercurrent manner, such as... Figure 2 As shown, the cold-side gas enters the bottom air duct 5 through the cold-side inlet air box 2 and a set of heat exchange components 3, and then enters the cold-side outlet air box 1 and is discharged after passing through another set of heat exchange components 3. During the flow of the cold-side gas in the heat exchanger, it exchanges heat with the hot-side flue gas through the two sets of heat exchange components 3, thereby achieving preheating.

[0034] In this embodiment, the heat exchange component 3, the hot and cold side air ducts, etc. are all made of stainless steel and are fully brazed, which has strong sealing performance, no leakage, and greatly extends service life.

[0035] Combination Figure 1 In this embodiment, there are two plate heat exchangers, which are fixed side by side in the tunnel by a suspension structure.

Claims

1. A plate heat exchanger for a hot rolling furnace in the iron and steel industry, characterized in that, The heat exchanger comprises a cold side outlet air bellow (1), a cold side inlet air bellow (2), a hot side inlet (6), a hot side outlet (7), a bottom air duct (5) and two groups of heat exchange assemblies (3). The heat exchange assembly (3) comprises a plurality of heat exchange assembly units arranged side by side, each heat exchange assembly unit comprises two plates, the middle part of the plate is a heat exchange zone (12), both ends of the heat exchange zone (12) are provided with a windward zone (11) and a welding zone (10), the windward zone (11) is located between the heat exchange zone (12) and the welding zone (10), and the included angle between the windward zone (11) and the welding zone (10) is 30°-45°; the two plates are pressure-welded to form a heat exchange assembly unit through the welding zone (10), a cold side channel (8) is formed between the two plates, and a hot side channel (9) is formed between adjacent heat exchange assembly units. The cold side outlet air bellow (1) and the cold side inlet air bellow (2) are arranged above the two groups of heat exchange assemblies (3), and the two groups of heat exchange assemblies (3) are connected in communication through the bottom air duct (5) below; the flue gas sequentially passes through the hot side inlet (6), one group of heat exchange assemblies (3), another group of heat exchange assemblies (3) and the hot side outlet (7).

2. The plate heat exchanger for hot rolling heating furnace in the iron and steel industry according to claim 1, characterized in that, The outer wall of the windward zone (11) is uniformly provided with a plurality of convex patterns (13) from top to bottom, the convex pattern (13) has a horizontal section and a settlement section, the included angle between the settlement section and the horizontal section is 30°-45°, and the junction between the horizontal section and the settlement section is smoothly transitioned.

3. The plate heat exchanger for hot rolling furnaces of the iron and steel industry according to claim 2, characterized in that, The heat exchange zone (12) is divided into heat exchange strengthening sections and flat plate sections which are arranged in intervals from top to bottom, wherein the hot side channel (9) of the heat exchange strengthening section is uniformly provided with a plurality of first convex points (14) on one side, and the cold side channel (8) of the heat exchange strengthening section is uniformly provided with a plurality of second convex points (15) on one side.

4. The plate heat exchanger for hot rolling furnaces of the iron and steel industry according to claim 3, characterized in that, The number of the first convex points (14) is less than that of the second convex points (15), and the size of the first convex points (14) is greater than that of the second convex points (15).

5. The plate heat exchanger for hot rolling heating furnace in iron and steel industry according to claim 3, characterized in that, The settlement section of the convex pattern (13) is kept flush with the flat plate section of the heat exchange zone (12) in height.

6. The plate heat exchanger for hot rolling heating furnace in iron and steel industry according to claim 1, characterized in that, The surfaces on both sides of the heat exchange zone (12) and the windward zone (11) are provided with a wear-resistant coating.

7. The plate heat exchanger for hot rolling furnaces in the iron and steel industry according to claim 1, characterized in that, The cold side outlet air bellow (1) and the cold side inlet air bellow (2) are connected with the heat exchange assemblies (3) through expansion structures (4) respectively.

8. The plate heat exchanger for hot rolling heating furnace in iron and steel industry according to claim 1, characterized in that, The cold and hot media counterflow heat exchange.

9. The plate heat exchanger for hot rolling furnaces in the iron and steel industry according to claim 1, characterized in that, The plate is made of a stainless steel plate with a thickness of 1.0 mm or more.

10. The plate heat exchanger for hot rolling furnaces of the iron and steel industry according to any one of claims 1 to 9, characterized in that, The number of the plate heat exchangers is multiple, and the plate heat exchangers are modularly arranged in the tunnel.

Images