Heat exchange problem of high-temperature flue gas generating high-temperature heat transfer oil
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As the title suggests, high-temperature heat transfer oil is produced using high-temperature flue gas (around 1000 degrees). Is it appropriate to use finned tubes for this purpose? According to JBT11249-2012, the maximum operating temperature for aluminum finned tubes is 300 degrees; however, the maximum operating temperature for steel finned tubes is not specified. If finned tubes cannot be used at high temperatures, is it because the fins deform at such high temperatures? Must only plain tubes be used at high temperatures? Are there any corresponding standards?
1000 degrees? The three common series of tubes used in heat carrier boilers can reach a maximum temperature of around 620°C, I think. This is also because if carbon deposits, or what we commonly call sludge, accumulate in the pipes carrying the heat medium, large molecules will form in the boundary layer, resulting in much more severe damage to the pipes compared to ordinary water pipes. As for the denaturation of fins at high temperatures, we don’t understand that; it belongs to biology, right? It’s worth exploring – it turns out metals also have genders... haha, just joking
1. Carbon steel cannot be used at temperatures of 1,000 degrees, let alone aluminum. 2. As for whether to use smooth tubes or finned tubes, it depends on the dust content in the flue gas; you can add me on QQ at 275484462 for assistance
The maximum allowable temperature for domestically produced heat transfer oil is 350 degrees; Daosheng oil claims to be able to handle 400 degrees, but it is still used at 350 degrees.
A regular coiled tube structure is sufficient; excessive smoke and dust actually hinder heat transfer in finned tubes. You can try using threaded tubes; some manufacturers in the south produce threaded coiled tubes.
1000℃ – that’s too high a temperature; aluminum definitely won’t work. Tubes rated for use in boilers, with a thickness of 20g, will suffice.
Metal temperature of the actual components during operation?
This kind of waste heat recovery and reuse is also seen in equipment manufacturing; the materials used in this area are generally heat-resistant steels, such as heat-strengthened steels like 1Cr5Mo. The weldability is very poor. Aluminum fins definitely won’t work, as the melting point of aluminum is over 660 degrees.
The poster probably wants to use heat transfer oil instead of steam to make use of the waste heat, right?
The goal is to recover waste heat using heat transfer oil, which raises the issue of equipment selection. Can’t we use finned tubes? From what I understand, the temperature of the fins is close to that of the hot air, while the surface temperature of the bare tubes is close to that of the heat transfer oil; even finned tubes made of heat-resistant steel wouldn’t be able to withstand such conditions. Therefore, only bare tubes can be used, but this results in a larger heat exchange area. It involves equipment processing costs.
Should the heat exchanger use polished tubes? How to choose materials?