Heating nitrogen with heat transfer oil – selection of shell-and-tube exchangers
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The nitrogen is heated using heat transfer oil; selection of the heat exchanger type: Nitrogen flow rate: 15,000 m³/h. Inlet and outlet temperatures of nitrogen: 85–115°C. Pressure: 3 kPa. Note: The nitrogen contains 15% (by volume) methanol vapor, as well as a small amount of dust at ≤50 mg/Nm³. Inlet and outlet temperatures of the heat transfer oil: 160–180°C. Due to the presence of dust, there is concern that the finned heat exchangers originally selected might accumulate dust, so it is planned to switch to a tubular heat exchanger, with the gas flowing through the tube side and the heat transfer oil flowing through the shell side. Help 1: What should be the appropriate heat transfer coefficient? 2: There is currently a shell-and-tube heat exchanger with an outer tube diameter of 25 mm, a wall thickness of 2 mm, a length of 3 meters, and 248 tubes. The indicated heat exchange area is 60 m² – is this sufficient?
It’s not economical! It can be made in coiled tube style! Nitrogen pretreatment!
Nitrogen pretreatment is rather troublesome; coiled tubes have also been considered. The existing shell-and-tube type will do as long as it can be used. I calculated it using a heat transfer coefficient of 50 W, and the result was ≈40㎡. Could the heat transfer coefficient be too high?
As soon as I see a post about this kind of technology, I dare not speak out loud