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  1. chemjock

    Lethal Service: To categorize a process as lethal service (or not), to use a U-stamped vessel in th

    My experience is in oil refining where there are streams at high pressure and temperature with high concentrations of H2S and none of the equipment was classified as lethal service. The only time I have ever seen it applied was in a plant for destroying chemical weapon mustard agent and when...
  2. chemjock

    storage standard for world class methanol plant

    4 x 150,000 BBL IFR tanks are proposed for a new methanol plant. Is nitrogen blanketting required for the vapor space or are circulation vents sufficient?
  3. chemjock

    switch to oil&gas - interview tips more than welcome

    Employment tracks the price of oil and gas. It is not stable. There were big layoffs in 2009 and now there is a mad scramble for people again.
  4. chemjock

    Environmental factor always 0.3 or how often do you commonly use lower

    Always use 1 now. Can't assume the insulation will stay on in a fire with fire monitors knocking it off.
  5. chemjock

    Combined Feed Heat Exchanger Fouling

    There should be no ammonia if your upstream NHT is operating properly.
  6. chemjock

    oil and gas separator pressure drop

    As I recall, API 12J is just a tank with minimal internals so pressure drop should be small <1 psi if the nozzles aren't undersized. Add a demister and the drop goes up slighty. Add a filter coalescer and you start to add real pressure drop.
  7. chemjock

    burner flowrate

    You need the heat release curve for the burner.
  8. chemjock

    SWS_sripped water high ammonia content

    Are you injecting caustic?
  9. chemjock

    Small Scale Naphtha Hydrotreating and Naphtha Reforming Units

    The NHT and CRU will generally be purchased together because you will need a naphtha splitter. In this flow range a semi regenerative scheme will be the most economic. yield will be about 90%. Pay attention to product spec. Benzene and aromatics may be a problem. There are modular fabricaton...
  10. chemjock

    Liquid residence time for FKOD sizing?

    This is not unusual. I have seen 30 minutes. The time allows pumpout of the drum at a reasonsible rate to a slop tank. If there is a two phase relief then the answer is obvious. Even if the drum has only vapor relief there is usually condensation from saturated vapors after a reliving indident.
  11. chemjock

    API 43 Crude

    Fig 2B2.2 in the API data book correlates Mole wt vs API gravity. You need the Watson K factor though.
  12. chemjock

    Z factor (compressibility factor)

    The Z factor in Hysys is 0 for a saturated vapor. If you move away from the saturation point, ie raise the temperature a bit, a degree or two, then then Hysys should report the Z factor.
  13. chemjock

    Simple question about PSV location

    If the valve relieves, cooling water has to flow through the exchanger to discharge. This is almost always safer than no flow through the exchanger. But if the relieving case is when the cooling water is blocked in, it probably does not matter whether the PSV is on the supply or return.
  14. chemjock

    Converting a pump curve from water to oil

    Your discharge pressure is going down. Take a look at the downstream hydraulics to see where your new operating point is.
  15. chemjock

    Blowdown with liquids

    Hopefully, your liquid will remain in the blowdown vessel. If you don't have a dynamic simulator then run successive flashes at about 1-2 minutes interval. You should be trying to reduce pressure by half in 15 minutes. Calculate the mass removed during the interval, recalculate the liquid...
  16. chemjock

    How to calculate the saturated flow volume of natural gas in scf

    If you don't have a simulator, use y (mole frac water)= vapor pressure water @ T / operating pressure
  17. chemjock

    Head rise to Shut off

    Do you want a really flat pump curve?
  18. chemjock

    Cost of a 35.000 BPSD atmospheric unit ?

    Correction that is a 30,000 bpd.
  19. chemjock

    Cost of a 35.000 BPSD atmospheric unit ?

    Cost for modularized refinery is $1000/bbl ex works. Needs to be transported, installed and hooked up. Does not include u and o. 35,000 bpd used refinery has 11' id atm column.
  20. chemjock

    Cost of a 35.000 BPSD atmospheric unit ?

    Very rough order of magnitude is about $1500 per bbl. At that size unit the big E and C s will laugh at you.
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