Atmospheric and vacuum distillation unit slag cooling water cooler
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The residue from the vacuum distillation column was originally designed to be cooled to 98 degrees Celsius by heat exchange with cooling water at 170°C and 32°C before leaving the unit; however, in actual operation, this residue could not be cooled sufficiently and left the unit at 150°C. After analysis: It is possible that the large temperature difference between the circulating water and the residue oil results in the formation of an air film on the pipe walls, thereby reducing heat transfer efficiency. In the current renovation plan, the circulating water is intended to be replaced with a heating medium at 140 degrees Celsius, after which the water is cooled again using circulating water. It is not clear whether an air film will still form, nor whether it will be possible to achieve the desired cooling level Does anyone know? Thanks.
The flow rate of the vacuum residue must be high; several coolers can be connected in series.
Okay, thank you. What do you think of the heat exchange effect between 140°C slag and cooling water? Thank you
If there are fluctuations in the circulating water pressure or something similar, it can easily damage the structure of the residue oil cooler, leading to a failure in cooling
Oh, thank you, but it’s not scaling
Utilize waste heat recovery for power generation and implement energy cooperation management – this allows for both heat recovery and power production! However, a venue needs to be provided.
Could you say something practical? Thanks
Could you say something practical? Thanks
Your analysis might be incorrect; if a gas film is formed in the circulating water, it’s easy to detect. It can be observed from the pressure of the circulating water and the drain valves of the heat exchanger.
As you described, it is likely that the temperature difference between the residue and the circulating water is too large; as a result, the temperature of the residue near the pipe wall becomes too low, its fluidity decreases, and it adheres to the pipe wall, thereby affecting the heat exchange between the two fluids. As a solution, using hot water at 70-80 degrees as the cooling medium can basically meet the requirements of the process you described.
There are many reasons why the temperature of the residue cannot be reduced through water cooling. Insufficient heat absorption by the crude oil leads to high temperatures at the inlet of the heat exchanger for the residue, going from the end of the distillation column to the water cooler. Improper operation of the vacuum tower, as well as an excessive amount of residue, can all contribute to high temperatures of the residue as it leaves the plant