Flue gas waste heat recovery
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Regarding the air preheater installed behind the heat transfer oil furnace, the design institute generally requires that the flue gas flow through the shell side; however, we believe that it is easier to clean the dust when the flue gas flows through the tube side. We’re not sure what the purpose of this requirement from the design institute is!
It is not easy to clean the ash from the tube side, but it is easier to do so from the shell side.
Current flue gas soot removal devices are generally designed for cleaning the shell side, allowing for online soot removal.
1. When the flue gas flows in the shell side, the tube wall temperature is higher than when it flows in the tube side, which helps to reduce low-temperature corrosion. After corrosion occurs, only the lowest rows of tubes need to be replaced; the tube arrays can be made of elliptical cast iron that is resistant to corrosion and has good heat transfer properties. This approach is often used with heavy oil containing high levels of sulfur, in conjunction with steel ball soot blowing； 2. Heat-tube air preheater, with both air and flue gas flowing outside the tubes.