Residue heat exchanger purging
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When purging the residue oil heat exchanger, we close the outlet valve and use steam to purge from the exit of the heat exchanger back toward the inlet. But why is reverse purging necessary? Why not carry out the purging in the same forward direction as when purging a diesel heat exchanger?
Backward blowing makes it easier to clean, as the residue oil is heavier; if blown in the forward direction, steam tends to take a shortcut.
Residue is generally used as a heat source, and in heat exchangers it flows from high to low pressure; therefore, it should be blown from the inlet toward the outlet. If the direction is reversed, it might be easier for residue to remain in certain areas due to gravity, making it difficult to clean those areas thoroughly
It might be a matter of getting used to the operation; according to the process design, it should be done by blowing in the correct direction； If blowing in the reverse direction, it might be advisable to send the residue back to the heavy residue outlet device at the boundary, in order to avoid sending it to the feed tank and then transporting it elsewhere.
Push hard to the third floor! That’s right; in heavy oil heat exchange, the flow is from top to bottom. Backflow doesn’t help clean things up – it’s confusing! Anyway, just blow it clean. OP, do the devices have the wax oil flowing in from above and out from below? We were being a bit presumptuous!
The key aspect of purging the residue line is multiple pressure holds
Reply to 3# xbchase: The residue oil in the device flows from bottom to top; during backwashing, it is blown from top to bottom. Does this utilize gravity to ensure a cleaner cleaning?
Reply to 7# zenghay: Does your unit use a heat exchanger to heat the residue oil? If the normal process is to flow from bottom to top with exhaust coming from above, then it’s easy to understand when the blowing direction is reversed
According to standard operating practices, the residue oil heat exchanger is cleaned in a forward cleaning manner; the oil inside the vessel is collected in the tank area. However, when there is a small amount of oil, it can also be pumped back into the tower. There is not much difference in terms of operation between forward and reverse cleaning
It can be combined with on-site installations; heavy oil generally flows through the shell side, entering from below and exiting from above. Everything I’ve seen is equipped with pipes; steam purging is provided at the shell side outlet, while a drain port is provided at the inlet.
I’ve never heard of blowing in the reverse direction. At such high temperatures, residue oil is used as a heat source in heat exchangers, with heat flowing from high to low pressure; blowing in the reverse direction creates so much resistance that it’s impossible to clean everything thoroughly. Even when blowing normally, it’s necessary to continuously regulate the pressure in the residue oil section in order to achieve thorough cleaning.