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• What is the typical particle size for HCGO Backwash filters? The frequency of the HCGO backwash filter has increased significantly when the wash oil amount is decreased in the unit. I have checked the data sheet which states that coke particle size>20 microns. Have you encountered any issues with HCGO backwash filters before? If the problem is not related to the filter size, what other factors might be causing it?

  Apr-2024

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Answers

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• Marcio Wagner da Silva, Petrobras, marciows@petrobras.com.br

  Unfortunately, issues related to HCGO (Heavy Coker Gas Oil) filters are not uncommon in the refineries. If the HCGO feed is coming cold from a storage tank, it's possible to face high pressure drop due to high viscosity, due to be a chemically unstable feed the the storage tank should rely with a nitrogen blanketing to avoid the olefins oxidation which will raise the pressure drop in the filters due to gums and polymers precipitation.

  Another key point is the operating performance of the main fractionator of the delayed coking unit. Disturbances in the delayed coking unit can cause coke fines dragging to the downstream processes, an alternative is to check if the wash oil flow rate of HCGO fractionating section is adequate, lower flow rates can cause coking deposition and worse quality of the stream.

  Other points to be checked are the backwash flow rate as well as a good characterization of the particles, especially to determine if the main issues are the organic or inorganic particles. If there was a significant reduction in the feed temperature to the HCGO filter system this also can lead to poor performance and the process needs to be checked to get around this issue.

   

  Apr-2024