A plate heat exchanger

Abstract

The utility model relates to the field of boiler manufacturing technology especially a plate heat exchanger, including hoisting frame and by the multiple sheet metal heat exchange body superposition formed heat exchange core body. Heat exchange core body is carried by hoisting frame, and its inside interval is equipped with flue gas flow channel and air flow channel. Along the heat exchange core body height direction, multiple flue gas flow channels and multiple air flow channels are alternately arranged, and the extension direction of both is perpendicular to each other. When high-temperature flue gas and air to be preheated flow in flue gas flow channel, air flow channel respectively, realize efficient heat transfer through sheet metal heat exchange body, can effectively improve air preheating temperature, satisfy the differentiating demand of different type boiler to air preheating, give full play to the value of waste heat recovery. Furthermore, the heat exchange core body formed by the multiple sheet metal heat exchange body superposition not only ensures that heat exchange performance is stable and reliable, and significantly reduces the design volume, provides the convenience for adapting various installation scenes.

Description

Technical Field

[0001] This utility model relates to the field of boiler manufacturing technology, and in particular to a plate heat exchanger. Background Technology

[0002] In the fields of industrial production and energy supply, boilers, as core thermal energy equipment, are widely used in power generation, chemical industry, metallurgy, and residential heating. During boiler operation, the high-temperature flue gas generated by fuel combustion needs to be discharged through the tail flue. This flue gas usually carries a large amount of waste heat. Direct discharge would not only result in serious waste of thermal energy but also increase the environmental heat load. Therefore, how to efficiently recover the waste heat from the boiler tail flue gas and reduce energy consumption has become one of the key directions for boiler system optimization design. Currently, the mainstream boiler waste heat recovery equipment in the industry mainly consists of shell-and-tube heat exchangers and traditional plate heat exchangers. Among them, shell-and-tube heat exchangers are still used in some high-parameter operating conditions due to their stable structure and high pressure resistance. However, they have significant drawbacks: on the one hand, the flow channel space formed between the heat exchange tubes and the shell of the shell-and-tube heat exchanger is relatively large, resulting in a limited contact area between the flue gas and the air, and a tendency for "laminar flow effect" to occur, leading to low heat exchange efficiency; on the other hand, shell-and-tube heat exchangers are bulky and require a large installation space, especially in old boiler renovation projects, where space is often insufficient for their compatibility. While traditional plate heat exchangers are more efficient than shell-and-tube heat exchangers, their single-pass, co-current or counter-current flow channel design has significant drawbacks under boiler operating conditions, making it difficult to meet waste heat recovery requirements. Specifically, from a heat exchange principle perspective, air flows in only one direction within a single-pass channel, resulting in a short residence time. Meanwhile, the flue gas velocity at the boiler tail end is relatively high, making it difficult for the hot and cold media to fully contact and exchange heat. Boilers have specific requirements for air preheating temperatures, especially since the requirements vary significantly between different types of boilers (such as coal-fired boilers and gas-fired power plant boilers). However, air heat exchange in a single-pass channel exhibits a "gradual decrease" characteristic, meaning the actual preheating temperature is far lower than the target value, failing to meet the boiler's operational needs.

[0003] Therefore, it is urgent for technical personnel to solve the above problems. Utility Model Content

[0004] The purpose of this utility model is to provide a plate heat exchanger that addresses the problems of insufficient heat exchange efficiency, inadequate contact between hot and cold media leading to insufficient air preheating temperature to meet boiler requirements, and low waste heat recovery value in existing designs; it also solves the problem of existing equipment being too large and having limited applicability to various scenarios.

[0005] This utility model relates to a plate heat exchanger suitable for boilers, including a mounting frame and a heat exchange core. The heat exchange core is composed of multiple sheet metal heat exchange elements stacked together and supported by the mounting frame. Flue gas flow channels and air flow channels are spaced apart inside the core. Along the height direction of the heat exchange core, multiple flue gas flow channels and multiple air flow channels are arranged alternately, and the extension directions of the flue gas flow channels and air flow channels are perpendicular. When high-temperature flue gas and air flow in the flue gas flow channels and air flow channels respectively, heat exchange occurs through the sheet metal heat exchange elements.

[0006] As a further improvement to the technical solution disclosed in this utility model, the plate heat exchanger also includes an air inlet, an air outlet, and a guide fluid; the heat exchange core also includes an isolation plate; the isolation plate is disposed in the air flow channel, dividing it into a front air flow channel and a rear air flow channel; the air inlet and the air outlet are fixed on the left side of the heat exchange core, and there is a set distance between them; the guide fluid is fixed on the right side of the heat exchange core; the air inlet has an inlet channel for introducing air to be preheated, and the air outlet has an exhaust channel for discharging preheated air, and the inlet channel is connected to the rear air flow channel, and the exhaust channel is connected to the front air flow channel; a guide cavity is formed inside the guide fluid; the guide cavity is connected to both the front and rear air flow channels; the air to be preheated enters the rear air flow channel through the inlet channel, flows into the guide cavity after the first heat exchange and heating, and is reversed and enters the front air flow channel for the second heat exchange and heating under the guidance of the guide cavity, and finally the preheated air is discharged through the exhaust channel.

[0007] As a further improvement to the technical solution disclosed in this utility model, the cross-section of the guide cavity is U-shaped, with one side opening connected to the outlet of the rear air flow channel and the other side opening connected to the inlet of the front air flow channel, so as to guide the air to form a 180° turning flow between the rear air flow channel and the front air flow channel.

[0008] As a further improvement to the technical solution disclosed in this utility model, a sealing gasket is provided between the fluid guide and the right side wall of the heat exchange core; the sealing gasket is made of heat-resistant asbestos material.

[0009] As a further improvement to the technical solution disclosed in this utility model, the isolation plate is preferably made of high-temperature resistant metal material, and it is sealed to the sheet metal heat exchanger by welding.

[0010] As a further improvement to the technical solution disclosed in this utility model, the air input body is provided with an intake pressure detection interface connected to the intake channel; the air exhaust body is provided with an exhaust pressure detection interface connected to the exhaust channel; the intake pressure detection interface and the exhaust pressure detection interface are used to connect an external pressure detection device to monitor the pressure change of air flowing in the air channel in real time.

[0011] As a further improvement to the technical solution disclosed in this utility model, the edge of the sheet metal heat exchanger is provided with a sealing flange; the sealing flanges of two adjacent sheet metal heat exchangers are perpendicularly intersected at 90° to form a sealing structure for isolating the flue gas flow channel from the air flow channel.

[0012] As a further improvement to the technical solution disclosed in this utility model, the sheet metal heat exchanger has a number of raised baffles formed on the side facing the flue gas flow channel; and the baffles are distributed at intervals along the extension direction of the flue gas flow channel.

[0013] As a further improvement to the technical solution disclosed in this utility model, the hoisting frame includes a bearing frame and a lifting lug unit; the bearing frame is rectangular and surrounds the heat exchange core; the lifting lug unit is composed of a left-side lifting lug and a right-side lifting lug respectively fixed to the left and right sides of the top of the bearing frame.

[0014] As a further improvement to the technical solution disclosed in this utility model, flange connection structures are provided at both the inlet and outlet of the flue gas duct; the flange connection structures are provided with several connection holes evenly distributed along the circumference for sealing connection with the boiler flue gas duct.

[0015] In practical applications, the plate heat exchanger disclosed in this utility model can achieve at least the following beneficial technical effects, specifically: 1) The flue gas flow channel and the air flow channel are arranged alternately along the height of the heat exchange core and their extension directions are perpendicular to each other. In this way, when the high-temperature flue gas and the air to be preheated flow in the flue gas flow channel and the air flow channel respectively, efficient heat transfer is achieved through the sheet metal heat exchanger, which effectively increases the air preheating temperature, meets the differentiated air preheating needs of different types of boilers, and gives full play to the value of waste heat recovery. 2) Multiple sheet metal heat exchangers are stacked to form a heat exchange core, which significantly reduces the volume of the heat exchange core while ensuring heat exchange performance, making it suitable for various installation scenarios. Furthermore, the matching hoisting frame stably supports the heat exchange core, which not only facilitates the handling and installation of the equipment, but also prevents the heat exchange core from deforming due to uneven stress during the hoisting process. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a three-dimensional schematic diagram of the plate heat exchanger disclosed in this utility model from one perspective.

[0018] Figure 2This is a three-dimensional schematic diagram of the plate heat exchanger disclosed in this utility model from another perspective.

[0019] Figure 3 This is a three-dimensional schematic diagram of the heat exchange core in the plate heat exchanger disclosed in this utility model.

[0020] Figure 4 yes Figure 3 The front view.

[0021] Figure 5 yes Figure 4 AA sectional view.

[0022] Figure 6 yes Figure 4 BB cross-sectional view.

[0023] Figure 7 This is a three-dimensional schematic diagram of the first sheet metal heat exchanger in the plate heat exchanger disclosed in this utility model.

[0024] Figure 8 This is a three-dimensional schematic diagram of the second sheet metal heat exchanger in the plate heat exchanger disclosed in this utility model.

[0025] Figure 9 This is a three-dimensional schematic diagram of the fluid guide in the plate heat exchanger disclosed in this utility model.

[0026] Figure 10 This is a three-dimensional schematic diagram of the lifting frame in the plate heat exchanger disclosed in this utility model.

[0027] 1-Lifting frame; 11-Bearing frame; 12-Left lifting lug; 13-Right lifting lug; 2-Heat exchange core; 21-First sheet metal heat exchanger; 211-First sealing flange; 22-Second sheet metal heat exchanger; 221-Second sealing flange; 23-Flue gas flow channel; 24-Air flow channel; 241-Front air flow channel; 242-Rear air flow channel; 25-Isolation plate; 3-Air input body; 31-Inlet channel; 4-Air exhaust body; 41-Exhaust channel; 5-Guide fluid; 51-Guide cavity. Detailed Implementation

[0028] The following detailed description of the plate heat exchanger for boilers disclosed in this utility model, with reference to specific embodiments, will be provided in further detail. Figure 1 , Figure 2Two perspective views of the plate heat exchanger disclosed in this utility model are shown respectively. It can be seen that it is mainly composed of several parts, including a lifting frame 1, a heat exchange core 2, an air inlet 3, an air outlet 4, and a guide fluid 5. The heat exchange core 2 is stably supported by the lifting frame 1 and is the core component for realizing the heat exchange between high-temperature flue gas and air to be preheated. The air inlet 3 and the air outlet 4 are fixed on the left side of the heat exchange core 2 and respectively undertake the functions of introducing the air to be preheated and discharging the preheated air. The guide fluid 5 is fixed on the right side of the heat exchange core 2 and is used to guide the air to form a reverse flow in the heat exchange core to improve the heat exchange efficiency. like Figure 10 As shown, the lifting frame 1, as a key component for equipment support and handling, mainly consists of a support frame 11, a left lifting lug 12, and a right lifting lug 13. The support frame 11 has a rectangular frame structure, and its internal contour dimensions are precisely matched with the external dimensions of the heat exchange core 2, which can completely surround the heat exchange core 2, ensuring that the heat exchange core 2 is subjected to uniform force during the load-bearing process and avoiding structural deformation caused by local stress concentration. The left lifting lug 12 and the right lifting lug 13 are fixed to the left and right sides of the top of the support frame 11 by welding, respectively, and are symmetrically distributed about the longitudinal centerline of the support frame 11. In this way, during the actual lifting process, the lifting force is evenly transmitted to the support frame 11, which not only facilitates the on-site handling and installation of the equipment, but also effectively prevents the heat exchange core 2 from deforming due to uneven force during the lifting process. like Figures 3-6 As shown, the heat exchange core 2 is composed of multiple sheet metal heat exchangers stacked alternately, with flue gas channels 23 and air channels 24 spaced apart internally. Along the height of the heat exchange core 2, the multiple flue gas channels 23 and multiple air channels 24 are arranged alternately in parallel, and their extension directions are perpendicular to each other; that is, the flue gas channels 23 extend laterally along the heat exchange core 2, and the air channels 24 extend longitudinally along the heat exchange core 2. Thus, in practical applications, during the flow of high-temperature flue gas and air to be preheated, sufficient heat exchange occurs between the two through the sheet metal heat exchangers: the heat from the flue gas can be efficiently transferred to the air side, significantly increasing the air preheating temperature (the preheated air temperature can be increased by 150–300°C). This not only meets the differentiated air preheating needs of different types of boilers (such as industrial boilers and power plant boilers) but also fully utilizes the waste heat value of the flue gas, reducing the main energy consumption of the boiler and achieving energy-saving effects. Meanwhile, the structure of multiple sheet metal heat exchangers stacked together significantly reduces the volume of the heat exchange core 2 while ensuring heat exchange performance (heat exchange efficiency can reach more than 85%), making it easy to adapt to the narrow space of boiler auxiliary equipment and improving the flexibility of installation scenarios. It is worth noting that both the inlet and outlet of the flue gas duct 23 are integrally formed with flange connection structures (not shown in the figure), and the flange connection structures have several connection holes evenly distributed circumferentially. This effectively ensures a sealed connection between the flue gas duct 23 and the boiler's flue gas pipeline, preventing leakage of high-temperature flue gas during circulation. This prevents heat loss from affecting heat exchange efficiency and avoids safety hazards caused by the overflow of high-temperature flue gas, further improving the safety and operational stability of the equipment. like Figure 7 , Figure 8 As shown, the sheet metal heat exchanger is divided into two design types: a first sheet metal heat exchanger 21 and a second sheet metal heat exchanger 22. The core difference between the two lies in the different extension directions of the sealing flanges, which are perpendicular to each other. Specifically, the first sheet metal heat exchanger 21 has a first sealing flange 211 integrally formed on its edge. The first sealing flange 211 is formed by bending the front and rear sides of the first sheet metal heat exchanger 21 downwards at a 90° angle. Similarly, the second sheet metal heat exchanger 22 has a second sealing flange 221 integrally formed on its edge. The second sealing flange 221 is formed by bending the left and right sides of the second sheet metal heat exchanger 22 downwards at a 90° angle. When the first sheet metal heat exchanger 21 and the second sheet metal heat exchanger 22 are alternately stacked, the first sealing flange 211 and the second sealing flange 221 of the two adjacent sheet metal heat exchangers will form a 90° vertically interlocking mating structure to effectively isolate the flue gas flow channel 23 and the air flow channel 24, completely prevent the two fluids from flowing together during the heat exchange process, avoid the decrease in heat exchange efficiency or equipment failure caused by fluid mixing, and further ensure the reliability of heat exchange. Furthermore, both the first sheet metal heat exchanger 21 and the second sheet metal heat exchanger 22 have several raised baffles (not shown in the figure) formed on the side facing the flue gas passage 23, and these baffles are spaced apart along the extension direction of the flue gas passage 23. When high-temperature flue gas flows through the flue gas passage 23, the baffles can break the laminar flow of the flue gas, causing it to become turbulent. In the turbulent state, the contact area between the flue gas and the wall of the sheet metal heat exchanger is larger and the contact time is longer, which greatly improves the heat transfer efficiency, further enhances the waste heat recovery effect, and allows the heat carried by the flue gas to be more fully utilized. like Figures 3-6 As shown, multiple isolation plates 25 are also added inside the heat exchange core 2. The isolation plates 25 are located inside the air flow channel 24, dividing the air flow channel 24 into a front air flow channel 241 and a rear air flow channel 242. The isolation plates 25 are preferably made of high-temperature resistant metal materials (such as 304 stainless steel), and they are sealed to the first sheet metal heat exchanger 21 and the second sheet metal heat exchanger 22 by welding, thereby ensuring that there is no air crossflow between the front air flow channel 241 and the rear air flow channel 242, ensuring independent air flow in each channel, and thus avoiding insufficient heat exchange caused by crossflow in the channels. like Figure 1 , Figure 2As shown, the air inlet 3 and the air outlet 4 are fixed to the left side of the heat exchange core 2, and there is a set distance between them to avoid mutual interference between the air during the input and output processes. The air inlet 3 is formed with an air inlet channel 31 for introducing the air to be preheated. The air inlet channel 31 is connected to the rear air flow channel 242 to ensure that the air to be preheated can smoothly enter the rear air flow channel 242. The air outlet 4 is formed with an exhaust channel 41 for discharging the preheated air. The exhaust channel 41 is connected to the front air flow channel 241 so that the preheated high-temperature air can be smoothly discharged. In addition, the air inlet body 3 is equipped with an intake pressure detection interface (not shown in the figure) that communicates with the intake channel 31, and the air outlet body 4 is equipped with an exhaust pressure detection interface (not shown in the figure) that communicates with the exhaust channel 41. The intake and exhaust pressure detection interfaces are used to connect external pressure detection devices (such as pressure gauges) to monitor pressure changes in real time as air flows within the airflow channel 24. When abnormal pressure occurs (e.g., excessive pressure difference may indicate channel blockage; insufficient pressure difference may indicate seal failure), personnel can promptly detect and address the issue, preventing a sudden drop in heat exchange efficiency or equipment damage due to escalating faults, and ensuring long-term stable operation of the equipment. like Figure 9 As shown, the guide fluid 5 is fixed to the right side of the heat exchange core 2, and a guide cavity 51 is formed inside it.

[0029] As a further optimization of the above technical solution, the cross-section of the guide cavity 51 is U-shaped (not shown in the figure). One side of its opening connects to the outlet of the rear air flow channel 242, and the other side connects to the inlet of the front air flow channel 241, so as to guide the air to form a 180° turning flow between the rear air flow channel 242 and the front air flow channel 241. During operation, the preheated air enters the rear air flow channel 242 through the air intake channel 31, and after the first heat exchange and temperature increase with the high-temperature flue gas in the flue gas flow channel 23, it flows into the guide cavity 51. Under the guidance of the guide cavity 51, the air reverses and enters the front air flow channel 241, and undergoes a second heat exchange and temperature increase with the high-temperature flue gas in the flue gas flow channel 23. Finally, the preheated air that has undergone two heat exchanges is discharged through the exhaust channel 41 and enters the boiler to participate in the combustion process. It is worth noting that a sealing gasket (not shown in the figure) is provided between the guide fluid 5 and the right side wall of the heat exchange core 2. The sealing gasket is preferably made of heat-resistant asbestos material. Heat-resistant asbestos material has excellent high-temperature resistance (able to withstand working environments of 200-500℃) and sealing performance. It can adapt to the high-temperature environment during the operation of the heat exchange core 2 and effectively seal the gap between the guide fluid 5 and the heat exchange core 2, preventing air leakage during the flow process. This ensures that all air can participate in secondary heat exchange, avoiding a decrease in heat exchange efficiency due to air loss, and further guaranteeing the energy-saving effect of the "secondary heat exchange" design.

[0030] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A plate heat exchanger, suitable for boilers, characterized in that, It includes a lifting frame and a heat exchange core; the heat exchange core is composed of multiple sheet metal heat exchange elements stacked together and is supported by the lifting frame, and has flue gas flow channels and air flow channels spaced apart inside; along the height direction of the heat exchange core, multiple flue gas flow channels and multiple air flow channels are arranged alternately, and the extension direction of the flue gas flow channels and the air flow channels are perpendicular; when high-temperature flue gas and air flow in the flue gas flow channels and the air flow channels respectively, they exchange heat through the sheet metal heat exchange elements.

2. The plate heat exchanger according to claim 1, characterized in that, The plate heat exchanger further includes an air inlet, an air outlet, and a guide fluid; the heat exchange core also includes an isolation plate; the isolation plate is disposed within the air flow channel, dividing it into a front air flow channel and a rear air flow channel; the air inlet and the air outlet are fixed to the left side of the heat exchange core, and there is a set distance between them; the guide fluid is fixed to the right side of the heat exchange core; the air inlet has an inlet channel formed for introducing air to be preheated, and the air outlet has an outlet for discharging preheated air. The system includes an exhaust channel, with the intake channel communicating with the rear airflow channel and the exhaust channel communicating with the front airflow channel. A guide cavity is formed inside the guide fluid. The guide cavity communicates with both the front and rear airflow channels. Preheated air enters the rear airflow channel through the intake channel, undergoes a first heat exchange and temperature increase, then flows into the guide cavity. Under the guidance of the guide cavity, the air reverses direction and enters the front airflow channel for a second heat exchange and temperature increase. Finally, the preheated air is discharged through the exhaust channel.

3. The plate heat exchanger according to claim 2, characterized in that, The cross-section of the air guide cavity is U-shaped, with one side opening connected to the outlet of the rear air flow channel and the other side opening connected to the inlet of the front air flow channel, so as to guide the air to form a 180° turning flow between the rear air flow channel and the front air flow channel.

4. The plate heat exchanger according to claim 3, characterized in that, A sealing gasket is provided between the fluid guide and the right side wall of the heat exchange core; the sealing gasket is made of heat-resistant asbestos material.

5. The plate heat exchanger according to claim 2, characterized in that, The isolation plate is made of high-temperature resistant metal material, and it is sealed to the sheet metal heat exchanger by welding.

6. The plate heat exchanger according to claim 2, characterized in that, The air input body is provided with an intake pressure detection interface that communicates with the intake channel; the air exhaust body is provided with an exhaust pressure detection interface that communicates with the exhaust channel; the intake pressure detection interface and the exhaust pressure detection interface are used to connect an external pressure detection device to monitor the pressure change of air flowing in the air channel in real time.

7. The plate heat exchanger according to claim 1, characterized in that, The edge of the sheet metal heat exchanger is provided with a sealing flange; the sealing flanges of two adjacent sheet metal heat exchangers are perpendicularly intersected at 90° to form a sealing structure for isolating the flue gas flow channel from the air flow channel.

8. The plate heat exchanger according to claim 7, characterized in that, The sheet metal heat exchanger has several raised baffles formed on the side facing the flue gas passage; and the baffles are distributed at intervals along the extension direction of the flue gas passage.

9. The plate heat exchanger according to any one of claims 1-8, characterized in that, The hoisting frame includes a support frame and a lifting lug unit; the support frame is rectangular and surrounds the heat exchange core; the lifting lug unit is composed of a left-side lifting lug and a right-side lifting lug respectively fixed to the top left and right sides of the support frame.

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