Heat exchanger with H-shaped fins and ceramic film-coated elliptical tube bank

Abstract

The application of H-shaped finned elliptical tube bundles coated with ceramic films in waste heat recovery belongs to the field of industrial waste heat recovery technology. This invention solves the problems of easy ash accumulation, wear, corrosion, low heat exchange efficiency, and high cost of existing flue gas heat exchangers and ceramic tubes. The key technical points are the use of elliptical tubes with H-shaped fins to construct the heat exchanger; the ash-accumulating and wear-prone areas of the front tube bundle are coated with a common ceramic film, while the easily corroded areas of the rear tube bundle are coated with a hydrophilic ceramic film. The H-shaped fins facilitate ash removal and reduce wear resistance; the ceramic film is smooth, prevents ash accumulation, and is wear- and corrosion-resistant; the hydrophilic film can inhibit low-temperature acid corrosion. This invention is mainly used for waste heat recovery from industrial boiler tail flues and dust-laden corrosive flue gas, improving heat exchange efficiency, reducing equipment wear, and enhancing operational stability, thus achieving efficient industrial waste heat recovery and energy saving.

Description

Technical Field

[0001] This invention relates to the application of ceramic-coated elliptical tube arrays with H-shaped fins in waste heat recovery, providing a new method for the recovery of industrial waste heat resources. Background Technology

[0002] Industrial energy consumption accounts for over 70% of my country's total energy consumption, with at least 50% being converted into industrial waste heat at different temperatures and on different carriers, most of which can be recycled. However, the current industrial waste heat recovery rate in my country is only about 30%, indicating low energy utilization efficiency. Inspired by the wear resistance and good heat transfer performance of H-type finned tube heat exchangers, the non-dust accumulation and corrosion resistance of ordinary ceramic membranes, and the excellent water vapor separation characteristics of hydrophilic ceramic membranes in flue gas, this paper proposes to learn from existing technologies and innovate upon them to avoid the drawbacks of existing flue gas tail heat exchangers being prone to corrosion, dust accumulation, and wear, as well as the high cost and low efficiency of ceramic tube heat exchangers, systematically linking the two. This provides a new method for the recovery of industrial waste heat resources. Industrial flue gas is typically characterized by high dust content and corrosiveness, easily causing a series of serious problems such as dust accumulation, wear, and corrosion on the heat exchange surfaces of flue gas heat exchangers. Domestic and foreign scientists have conducted relevant research on dust accumulation, wear, and corrosion in flue gas heat exchangers for waste heat recovery, analyzing the causes and influencing factors of dust accumulation, wear, and corrosion on the heat exchange surfaces of heat exchangers from various perspectives. Among the various challenges, ash accumulation in flue gas heat exchangers within dusty flue gas can lead to decreased heat transfer efficiency and increased pressure drop, while also increasing operational instability and posing safety hazards. Therefore, studying the ash accumulation characteristics of heat exchangers in dusty airflows and proposing effective preventative measures is crucial for the economic and safe operation of various equipment. Summary of the Invention

[0003] The purpose of this invention is to provide a new heat exchanger for waste heat recovery from industrial flue gas. This heat exchanger can reduce ash accumulation and corrosion, improve heat exchange efficiency, increase equipment stability, reduce costs to a certain extent, and achieve the goal of energy saving.

[0004] To achieve the invention objective as described above, the technical solution adopted by the present invention is: a heat exchanger composed of an elliptical heat exchange tube core with H-shaped fins, wherein the heat exchange tube is partially coated with a ceramic film.

[0005] The above solutions reduce ash accumulation, wear, and corrosion in heat exchangers used for industrial flue gas waste heat utilization. Attached Figure Description

[0006] Figure 1 Example diagram of tail-end flue gas heat exchanger.

[0007] Figure 2 Example diagram of dust accumulation area in an elliptical tube.

[0008] Figure 3 Example diagram of wear area in elliptical tube.

[0009] Figure 4 Example diagram of corrosion area in elliptical tube. Detailed Implementation

[0010] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0011] Figure 1 The tail flue heat exchanger is arranged in the tail flue of the boiler. By adding boiler feedwater, heat is directly recovered into the entire system, which improves the efficiency of the boiler without affecting the operation of its original heating surface. It is a mature method for recovering waste heat from flue gas.

[0012] The impact of H-shaped fin structure on ash accumulation and wear: The gap between the two fins allows for the flow of flue gas and the flushing of ash, as the flue gas has a higher flow velocity at the gap; the tubes are arranged in parallel, resulting in low resistance and low wear; H-shaped fins can effectively utilize the flow space, maintaining a large fin area and fin ratio; the fin thickness can be arbitrarily selected according to the needs of wear resistance; the fins are independent and parallel to each other, without the influence of helix angle, thus facilitating ash removal.

[0013] like Figure 2 Due to improper flue design or changes in coal quality, ash accumulation is easily caused in the tail flue of the boiler. Therefore, ordinary ceramic film is coated in the ash accumulation area of ​​the front tube bundle. Because the ceramic surface is smooth, it is not conducive to the adhesion of particulate matter in the flue gas. When the attached dust reaches a certain thickness, it is also very easy to peel off, which can reduce ash accumulation and improve heat exchange performance.

[0014] Fly ash abrasion of the boiler's heating surface tubes is caused by the kinetic energy of the fly ash particles carried by the high-temperature flue gas. When these particles impact the metal surface, they consume kinetic energy and exert impact and cutting action on the metal surface. In other words, the fly ash in the boiler flue gas has sufficient hardness and kinetic energy at a certain temperature, causing a grinding effect on the heating surface tubes. Figure 3 Due to the high temperature resistance, wear resistance and corrosion resistance of ceramics, ordinary ceramics are plated in the wear area of ​​the tube bank to reduce the impact of fly ash particles on the heat exchanger tube bundle, reduce wear, and thus effectively protect the tubes.

[0015] like Figure 4 For the rear heat exchange tube bundles where the flue gas temperature and flow rate decrease, the effects of acid corrosion and oxygen absorption corrosion are aggravated due to the condensation of sulfuric acid vapor on the heated surfaces. This patent employs a method of coating the easily corroded areas of the rear tube bundles with a hydrophilic ceramic film.

Claims

1. A heat exchanger, characterized in that... The heat exchanger includes a multi-row heat exchanger core, which is composed of elliptical tube banks and H-shaped fins. The elliptical tube banks are partially coated with ceramic film.

2. The heat exchanger according to claim 1, characterized in that: The elliptical heat dissipation tubes of the heat exchanger core are arranged at equal intervals. In the utilization of waste heat from flue gas, each group of heat exchangers is staggered with another group of heat exchangers.

3. The heat exchanger according to claim 2, characterized in that: The first row of heat exchanger cores and the second row of heat exchanger cores are adjacent to each other.

4. The heat exchanger according to any one of claims 1 to 3, characterized in that: The first row of heat exchanger cores and the second row of heat exchanger cores are aligned with each other in the width direction of the heat exchanger cores.

5. The heat exchanger according to any one of claims 1 to 4, characterized in that: The multi-row heat exchanger core includes two rows of heat exchanger cores.

6. The heat exchanger according to claims 1 to 4, characterized in that: The heat exchanger has elliptical heat exchange tubes fitted with H-shaped fins, and the heat exchange tubes are partially coated with a ceramic film.

7. The heat exchanger according to any one of claims 1 to 4, characterized in that: The tip of the elliptical heat exchange tube in the heat exchanger is located on the windward side of the flue gas.

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