How to prevent heat exchange tubes from freezing in low-temperature fluid heat exchange
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The question is as stated in the title. An example is as follows: an ethylene glycol aqueous solution (from -10 degrees to -30 degrees, in the shell side) and LNG (-160 degrees, in the tube side); it is possible to select an appropriate concentration of the ethylene glycol aqueous solution to ensure that the fluids do not freeze during the heat exchange process. But on the outer surface of the heat exchange tubes, how can freezing be effectively prevented? Thank you!
The surface of the housing can be covered with insulating materials such as insulation foam (foam boards, glass wool), etc. The outermost section can be fitted with a galvanized metal cover for waterproofing, or it can also be wrapped in glass cloth and painted to achieve waterproofing.
Maybe I didn’t explain it clearly. What I mean is, given that the temperature of LNG is so low, how can we prevent the ethylene glycol aqueous solution, which has a relatively high freezing point, from freezing during heat exchange with it? The ethylene glycol aqueous solution flows in the shell side, with freezing mainly occurring on the outer wall of the heat exchange tubes.
One method I’m aware of seems to involve bubbling air through the shell side, which helps prevent freezing.
Temperature is kept above the freezing point with a safety margin through flow control. There must also be a certain flow rate inside to prevent a large drop in temperature at the moment of contact. (Tube wall)
Haven’t you already answered that by choosing the appropriate concentration to prevent freezing? It won’t freeze as long as it’s above the freezing point.