Fresh air preheating and waste heat recovery device for hot air oven

Abstract

This utility model discloses a fresh air preheating and waste heat recovery device for a hot drying chamber, aiming to solve the technical problems of limited heat exchange efficiency, easy fouling and clogging, difficult cleaning and maintenance, and lack of automated control in existing waste heat recovery devices for hot drying chambers. The device includes a waste heat recovery chamber, a heat exchanger installed inside, a blower, a spray cleaning system, and an automated electrical control system. The fresh air channel and the hot waste gas channel inside the heat exchanger are separated; fresh air flows inside the heat exchanger, while hot waste gas flows around it externally. The internal fresh air channel adopts a sandwich flow guide design to extend the residence time, and the surface in contact with the hot waste gas is designed with a corrugated structure to increase the heat exchange area. The outer shell of the waste heat recovery chamber is equipped with a spray cleaning system for periodically cleaning the outer surface of the heat exchanger and the inner wall of the chamber. This effectively improves heat exchange efficiency, solves the cleaning and maintenance problems, enhances system safety and automation, and has advantages such as high efficiency, energy saving, and convenient operation and maintenance.

Description

Technical Field

[0001] This utility model relates to the field of industrial thermal energy utilization and energy-saving control technology, specifically a fresh air preheating waste heat recovery device for a hot drying room. Background Technology

[0002] Hot drying ovens are widely used in industrial production processes such as printing and dyeing, coating, textiles, and food processing for drying, heat setting, or curing products. During operation, these ovens continuously exhaust large amounts of high-temperature, humid waste gas. Simultaneously, to maintain indoor and outdoor air pressure balance, an equal amount of fresh air must be introduced. Since the fresh air is mostly at room temperature, it needs to be heated to the set drying temperature via a heating system, resulting in significant energy consumption and increased operating costs.

[0003] To improve energy efficiency, existing technologies have proposed waste heat recovery devices based on the principle of heat exchange. A common approach is to install a heat exchanger between the exhaust system and the fresh air inlet duct, allowing the high-temperature exhaust gas to exchange heat with the room-temperature fresh air, thereby preheating the fresh air and reducing the burden on the main heating system. A related technology, for example, is patent CN203037009U, which discloses an energy-saving drying room device that recovers heat from exhaust gas through a heat exchange structure.

[0004] However, existing similar technologies still have the following main problems and technical bottlenecks: 1. Difficult to clean and maintain, posing safety hazards: Because the exhaust gas contains impurities such as fibers, oil fumes, and dust, the heat exchanger is prone to blockage after long-term operation. This not only affects the heat exchange efficiency, but also may cause excessive heat accumulation if not cleaned in time, posing a fire risk. The maintenance cost is high and the operation safety is poor.

[0005] 2. High system cost and long investment recovery period: Existing waste heat recovery devices have complex structures, high material costs, and complicated installation and commissioning processes. The initial investment is large, and the payback period is long in actual enterprise applications, which limits the promotion and application of the technology.

[0006] 3. Limited heat exchange efficiency: Some heat exchangers are poorly designed, with insufficient heat exchange area or short heat transfer paths, resulting in low thermal energy utilization and affecting the overall energy-saving effect.

[0007] 4. Low system integration: The waste heat recovery device has poor compatibility with the original drying room system, complex interfaces, low overall integration, and is difficult to construct and modify, affecting system stability and maintenance convenience.

[0008] 5. Insufficient automatic control capabilities: Most existing solutions lack automatic control methods such as temperature linkage, air volume adjustment and fault feedback, making it difficult to dynamically adjust the operating status according to changes in the drying room load, resulting in discontinuous and unstable energy-saving effects.

[0009] Therefore, the existing market needs a waste heat recovery device for hot drying rooms that has high heat exchange efficiency, automatic control, easy cleaning and maintenance, high system integration, and controllable cost to solve the above-mentioned technical problems and achieve efficient energy recovery and safe and stable system operation. Utility Model Content

[0010] The purpose of this utility model is to solve the following technical problems existing in the waste heat recovery device of the existing hot drying room: 1. The heat exchange efficiency is limited and cannot effectively improve the preheating temperature of fresh air; 2. The heat exchanger is difficult to clean, easily accumulates scale and clogs, affecting the long-term stable operation of the system and posing a fire hazard; 3. The equipment has a complex structure, high cost, and low system integration, making it difficult to be easily adapted to existing drying room equipment, which affects its promotion and application. Fourth, it lacks automated control functions and cannot dynamically adjust the heat exchange conditions according to the operating status of the drying room, making it difficult to achieve stable and efficient energy-saving effects.

[0011] To achieve the above objectives, this utility model provides the following technical solution: A fresh air preheating and waste heat recovery device for a hot drying room includes: Waste heat recovery chamber, wherein the waste heat recovery chamber is provided with a hot waste gas inlet and a hot waste gas outlet; A heat exchanger is installed inside the waste heat recovery chamber. The heat exchanger is used for heat exchange between fresh air and hot exhaust gas. The fresh air channel inside the heat exchanger is separated from the hot exhaust gas channel outside. Fresh air flows inside the heat exchanger, while hot exhaust gas flows outside the heat exchanger and inside the waste heat recovery chamber, thereby preventing impurities in the exhaust gas from directly entering the fresh air channel. The heat exchanger's internal fresh air channel adopts a sandwich flow guide design, which guides the fresh air to flow through multiple paths inside to prolong the residence time; the surface of the fresh air channel that comes into contact with the hot exhaust gas is designed with a corrugated structure to significantly increase the heat exchange area and improve the heat transfer efficiency.

[0012] Furthermore, a spray cleaning system is provided outside the waste heat recovery chamber. The spray cleaning system includes spray pipes evenly distributed along the four longitudinal sides and the middle of the chamber. The spray pipes are equipped with evenly distributed nozzles for periodically spray cleaning the outer surface of the heat exchanger and the inner wall of the chamber. The spray cleaning system can be connected to a mobile water tank (with a water pump) to perform cleaning operations through the spray inlet and outlet.

[0013] Furthermore, the device is equipped with an automated electronic control system, which includes a PLC controller and a frequency converter, used to automatically adjust the speed of the blower according to the real-time detected exhaust gas temperature. This control system can automatically adjust the speed of the blower according to the real-time detected exhaust gas temperature, so that the fresh air volume entering the heat exchanger matches the heat of the exhaust gas, thereby achieving optimal heat exchange efficiency and energy-saving operation.

[0014] Furthermore, a blower is used to drive fresh air into the heat exchanger through the fresh air inlet, and the heated fresh air is sent back to the drying room through the fresh air outlet.

[0015] Furthermore, the spray cleaning system can be connected to a mobile water tank, and the cavity is provided with a spray inlet and a spray outlet for connecting the mobile water tank.

[0016] Furthermore, the waste heat recovery chamber is provided with a high-temperature visual inspection port, which is made of high-temperature resistant glass, so that users can directly observe the surface contamination of the heat exchanger and the internal structural condition of the chamber.

[0017] Furthermore, the device adopts a modular structure design, which makes it easy to customize and adjust according to the size of the drying room or customer needs, and has good adaptability and expandability.

[0018] Compared with the prior art, the beneficial effects of this utility model are: 1. Separation of cleaning and heat recovery channels to avoid blockage and improve equipment stability: This device adopts an independent channel structure for hot exhaust gas and fresh air, so that the fresh air entering the heat exchanger is always clean and not easy to scale or blockage. This fundamentally solves the problem of traditional systems where exhaust gas impurities block the channels and are difficult to clean, and significantly improves the stability and lifespan of the equipment.

[0019] 2. Optimized heat exchanger structure for higher heat exchange efficiency: The heat exchanger adopts a sandwich flow guide design and a corrugated heat exchange surface structure, which effectively increases the heat exchange area and the flow path of fresh air inside, improves heat transfer efficiency, and significantly enhances the utilization rate of recovered heat energy.

[0020] 3. Modular design, flexible installation, and greater adaptability: The overall modular structure design makes it easy to customize and adjust according to the size of the drying room or customer needs, and has good adaptability and expandability. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of this utility model; Figure 2 This is a schematic diagram of the internal structure of the present invention; Figure 3 This is a schematic diagram of the heat exchanger of this utility model.

[0022] In the diagram: 1. Hot exhaust gas inlet; 2. Hot exhaust gas outlet; 3. Fresh air inlet; 4. Fresh air outlet; 5. Heat exchanger; 6. Blower; 7. Spray pipe; 8. Spray water inlet; 9. Spray water outlet; 10. Nozzle; 5.1. Jacket; 5.2. Corrugated structure. Detailed Implementation

[0023] In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention can be practiced without one or more of these details. In other instances, certain technical features well-known in the art have not been described in order to avoid confusion with the present invention.

[0024] See attached document Figure 1-3 This utility model provides a fresh air preheating waste heat recovery device for a hot drying room.

[0025] Hot exhaust gas enters the waste heat recovery chamber from the drying oven through hot exhaust gas inlet 1. Inside the chamber, the hot exhaust gas flows around the outside of the heat exchanger, transferring heat to the fresh air flowing inside the heat exchanger. Subsequently, the hot exhaust gas is discharged from the system through hot exhaust gas outlet 2.

[0026] Fresh air at room temperature is driven by blower 6 and enters the heat exchanger through fresh air inlet 3. After being heated by heat from the exhaust gas inside the heat exchanger, the fresh air is discharged through fresh air outlet 4 and returned to the drying room for use, thereby achieving energy recovery.

[0027] The key improvement of this invention lies in the design of the heat exchanger and the flow pattern of exhaust gas and fresh air. Unlike the traditional design where exhaust gas and fresh air share a common channel, this device uses separate flow for exhaust gas and fresh air. Fresh air enters the heat exchanger under the drive of blower 6, and its channel remains clean at all times. The heat exchanger itself is located inside the waste heat recovery chamber through which the hot exhaust gas flows. Under the negative pressure created by the exhaust fan of the drying chamber, the exhaust gas flows naturally and continuously heats the fresh air flowing in the heat exchanger. The heated fresh air returns to the drying chamber through the outlet, achieving heat recovery and reducing energy consumption.

[0028] To improve heat exchange efficiency, the heat exchanger of this invention adopts an optimized structure. Its internal fresh air channel features a sandwiched flow-guiding structure 5.1, guiding the fresh air to form a multi-path flow within the heat exchanger, effectively extending the residence time of the fresh air within the heat exchanger and ensuring that the fresh air can fully absorb heat. Simultaneously, the surface of the heat exchanger that contacts the hot exhaust gas is designed with a corrugated structure 5.2, greatly increasing the effective heat exchange area, thereby significantly improving the overall heat exchange effect.

[0029] Considering that the exhaust gas may contain impurities such as fibers, oil fumes, and dust, which may accumulate on the outer surface of the heat exchanger and the inner wall of the waste heat recovery chamber, affecting heat exchange efficiency and posing safety hazards, this invention features a specially designed spray cleaning system. A continuous spray pipe 7 is installed along the four longitudinal sides and the center of the chamber, with nozzles 10 evenly distributed on this pipe to ensure comprehensive coverage of the entire outer surface of the heat exchanger and the inner wall of the chamber during cleaning. The cleaning operation is convenient and efficient. A mobile water tank (with its own pump) can be used, with its inlet connected to the spray inlet 8 on the chamber and its outlet connected to the spray outlet 9. After starting the pump, the entire heat exchanger system 5 can be thoroughly spray-cleaned, effectively avoiding the complex process of traditional manual disassembly and cleaning, and significantly reducing maintenance difficulty and labor costs.

[0030] In addition, to facilitate users' monitoring of equipment operation status and maintenance needs at any time, this device is equipped with a high-temperature visual inspection port on the cavity. This inspection port is made of high-temperature resistant glass, allowing users to directly observe the contamination status of the heat exchanger surface and the internal structural condition of the cavity through this window. This design facilitates the determination of whether cleaning is needed and also helps to promptly detect structural damage or operational abnormalities during equipment operation, thereby effectively improving the maintainability and operational safety of the equipment.

[0031] To further improve the system's energy efficiency and automation level, this device is equipped with an automated electrical control system, consisting of a PLC controller and a frequency converter. This system can monitor the exhaust gas temperature in real time and automatically adjust the speed of blower 6 according to temperature changes. This intelligent control method ensures dynamic matching between the fresh air volume entering the heat exchanger and the heat of the exhaust gas, thereby achieving optimal heat exchange efficiency, avoiding the energy waste caused by traditional constant-speed operation, and extending the equipment's lifespan.

[0032] This device, through its separate flow channel design for exhaust gas and fresh air, enhanced heat exchange structure, comprehensive automatic cleaning system, visual inspection window, and intelligent control system, significantly improves energy utilization efficiency, ease of operation and maintenance, and equipment reliability in practical applications, demonstrating remarkable practical advantages.

[0033] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A fresh air preheating waste heat recovery device for a hot air oven, characterized by, include: Waste heat recovery chamber, wherein the waste heat recovery chamber is provided with a hot waste gas inlet and a hot waste gas outlet; A heat exchanger is installed inside the waste heat recovery chamber. The heat exchanger is used for heat exchange between fresh air and hot waste gas, and the fresh air channel inside the heat exchanger is separated from the external hot waste gas channel. The internal fresh air duct of the heat exchanger adopts a sandwich flow guide design, and its surface in contact with the hot exhaust gas is designed with a corrugated structure.

2. A fresh air preheating and waste heat recovery device for a hot air oven according to claim 1, characterized in that, The waste heat recovery chamber is equipped with a spray cleaning system. The spray cleaning system includes spray pipes evenly distributed along the four longitudinal sides and the middle of the chamber, and the spray pipes are equipped with evenly distributed nozzles.

3. A fresh air preheating and waste heat recovery device for a hot air oven according to claim 1, characterized in that, The device is equipped with an automated electrical control system, which includes a PLC controller and a frequency converter, used to automatically adjust the speed of the blower according to the real-time detected exhaust gas temperature.

4. A fresh air preheating and waste heat recovery device for a hot air oven according to claim 1, characterized in that, The device also includes a blower for driving fresh air into the heat exchanger through the fresh air inlet, and the heated fresh air is sent back to the drying room through the fresh air outlet.

5. A fresh air preheating and waste heat recovery device for a hot drying room according to claim 2, characterized in that, The spray cleaning system can be connected to a mobile water tank, and the cavity is provided with a spray inlet and a spray outlet for connecting to the mobile water tank.

6. A fresh air preheating and waste heat recovery device for a hot air oven according to claim 1, characterized in that, The waste heat recovery chamber is provided with a high-temperature visual inspection port, which is made of high-temperature resistant glass.

7. A fresh air preheating and waste heat recovery device for a hot drying room according to claim 1, characterized in that, The device adopts a modular structure design.

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