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  1. georgeverghese

    Wash water for CDU OVHD AFC

    Error in my last post : Also air flowing over the upper tubes is higher may hence be lower than that over the lower tube rows.
  2. georgeverghese

    Use of Gate Valve for Throttling

    Since this is a DN600 gate valve, think the shear force generated at the gate stem could be considerable - check what diff press is required, and see if the gate stem could cause some internal damage that may make it inoperable.
  3. georgeverghese

    Air India 787 crashes on take off

    How is it possible to pull and switch BOTH these toggles almost simultaneously without using both hands ? I read from some earlier post that the fuel supply control valves that these switches activate are fail close (on loss of hydraulic pressure ?). If so, if the control valve were to close on...
  4. georgeverghese

    PSV for solvent thermal expansion

    Agreed, these patchwork diagrams dont seem to add up. Assuming you've adopted the blowdown drum solution for good reason with no alternate safe solution, then I dont see a way out of purging this blowdown drum if solvent vapors are flammable. A not so ideal alternate to purging is to install a...
  5. georgeverghese

    PSV for solvent thermal expansion

    Why is inerting the blowdown drum with N2 a problem ?
  6. georgeverghese

    Pressure vessel under negative Pressure

    Is this precoat filter fed by a pump taking suction from the pool? If so, will a check valve on pump discharge help prevent reverse flow on pump stop?
  7. georgeverghese

    Front End Acetylene Hydrogenation

    Though I am not an expert on the pros and cons for various configurations for C2H2 hydrogenation, I suspect there is a higher risk that valuable propylenes and propadienes may also get hydrogenated in the upstream reactor option, while this cannot happen in the tail end setup. These heavier...
  8. georgeverghese

    Closed Loop Piping-Vacuum Issue

    The other problem I see here is that the feed connection to the HX is at the top of the HX. So on pump stop, air will reverse flow into the HX top section also. This will vapor lock the top section of the HX and reduce HX thermal performance. It would be better to have the feed to the HX at the...
  9. georgeverghese

    Wash water for CDU OVHD AFC

    Suspect this common problem in fin fan ovhd condensors is in part also caused by poor air flow at the upper rows of the fintube bank. Also air flowing over the upper tubes is higher than that over the lower tube rows. Poor quality fins on tubes may also have corroded leading to higher pressure...
  10. georgeverghese

    Practical Implications of Impact Testing

    Aside from low temp toughness tests and grain quality, all carbon steel / low alloy carbon steel grades used in subzero temp applications are silicon killed steels as far as I know. What about this batch of A53 pipe ?
  11. georgeverghese

    Request for Aspen Plus Triamine (MEA + MDEA + PZ) CO2 Absorption Model (.bkp) or Guidance

    Interesting, didnt know folks are adding MEA into MDEA - PZ these days for CO2 absorption. Good luck.
  12. georgeverghese

    Acid scrubber 'spitting' issue

    Salt deposition in the mesh pad as @TiCl4 says ? If so, this will bung up just about everything in its path where water does not collect.
  13. georgeverghese

    Multiphase Flow Meter for emulsified crude oil Production

    If this meter is only for 2 phase oil / water mix with minimal gas content, then a diff head meter may do the job, provided you have a flow weighted sampling device ( such as a Welker sampler ) which you can send to the plant lab for oil-water content determination. Then do a correction for the...
  14. georgeverghese

    Use of Gate Valve for Throttling

    Not ideal, but would be okay for short term non erosive throttling.
  15. georgeverghese

    Closed Loop Piping-Vacuum Issue

    Suspect you dont have a check valve immediately downstream of the gear pump discharge, which is why the pump discharge riser sees reverse flow and fills up with air on pump stop. See if you can install a check valve on pump discharge.
  16. georgeverghese

    Free Vent for API 650 Tank - Bug Screen / Bird Screen Requirement

    Discussion on screen pressure drop estimate may be found in Perry Chem Eng Handbook 7th edn on page 6-19 - subsection on Screens.
  17. georgeverghese

    Gas Pipeline faces Higher velocity in pipeline network.

    I dont see a high pressure problem either. Yes, given the higher throughput, you'd have higher pressure drop. As long as velocities are kept below 25m/sec or so, there wont be an erosion concern. I see from the Mellitah GP brief on Google, that LPG - NGL is extracted out of the feedgas, so water...
  18. georgeverghese

    Front End Acetylene Hydrogenation

    In the naphtha cracker plant drawings I have, the C2H2 hydrogenation unit treats the raw combined ethane - ethylene stream from the de ethanizer tops, which I presume is what you call back end hydrogenation ? Where would the front end unit be located - upstream of primary or upstream of...
  19. georgeverghese

    Gas Pipeline faces Higher velocity in pipeline network.

    Trip pressure setting is somewhat arbitrary, but typically it is say 95% of design pressure if there is no overpressure relief requirement. If there is a possibility that the feed source can deliver pressure at or more than 780psig, then you may wish to trip out the source on PAHH at 90% of DP...
  20. georgeverghese

    Gas Pipeline faces Higher velocity in pipeline network.

    Max permissible gas velocity in corrosion inhibitor injected CS gas - condensate pipelines is approx 25m/sec in the gas phase to maintain inhibitor stability/ avoid film erosion. Running at 740psig inlet pressure in a 780psig MAWP CS pipeline may be too high for normal operating pressure range -...

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