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Use of water or crude oil pumps to pump ethanol

  • 1.  Use of water or crude oil pumps to pump ethanol

    Posted 04-15-2020 19:21
    Good day,

    I am currently tasked with pumping out a tank which contains ethanol. unfortunately, the only pumps that can be used for this are either a hydrant water pump or a pump used in crude oil service. Are there any considerations for using the water or crude oil pump in ethanol service? My concern lies with the seals on the pump and the fact that ethanol is more volatile and has a higher RVP than both water and crude oil which can lead to early pump cavitation.

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    Shantal Ramdeo PE
    Senior Process Engineer
    Heritage Petroleum Company Limited
    Princes Town
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  • 2.  RE: Use of water or crude oil pumps to pump ethanol

    Posted 04-16-2020 07:53
    Shantal,
    Your concerns are valid.

    Once I had to use a Coker Fuel Oil (CFO) pump from Delayed Coker Unit (DCU) for the Desalter De-sludging pump in Crude Distillation Unit (CDU) in our refinery. The process conditions of the CFO pump were far superior than the process conditions required for the Desalter De-sludging pump. For example, the CFO pump was designed to handle the fluid at 325 Deg C against the required temperature of 150 Deg C for the Desalter De-Sludging pump. Moreover, the NPSHA was more than NPSHR (minimum difference should be 1 MLC, in our case it was more than 2 MLC)​.

    So my suggestion would be:
    1. Check that the NPSHA is at least 1 MLC more than NPSHR.
    2. Regarding the seals, I suggest you get the confirmation from the pump manufacturer regarding its suitability for the proposed services.
    3. You should also check the suitability of the motor for the proposed service. The motor should be able to take the required load in the new service.

    If the above check points are satisfied, then it can be easily used for the proposed service.
    Good Luck.

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    Imran Khan
    Senior Technical Services Manager
    Indian Oil Corporation Ltd
    Guwahati AS
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  • 3.  RE: Use of water or crude oil pumps to pump ethanol

    Posted 04-16-2020 07:57
    This sounds like a situation that could lead to an accident.  Please do not proceed without performing a Hazop, or at least a What-If analysis, with a team composed of people from various disciplines.  Prior to that exercise, do some investigating on the seal materials' compatibility with ethanol.  Even if not the best materials for ethanol, if only exposed for a short time they may be acceptable.  Also, do a calculation of the available NPSH versus the pump requirements at the liquid temperature and flow rate.  I assume the motor is not XP, so any leakage from valves or seals could lead to a fire.  Best of luck with this, and kudos for reaching out.  Let us know afterwards how it went.