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  1. georgeverghese

    Use of Gate Valve for Throttling

    Not ideal, but would be okay for short term non erosive throttling.
  2. 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.
  3. 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.
  4. 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...
  5. 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...
  6. 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...
  7. 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 -...
  8. georgeverghese

    Dew point for RNG

    At the discharge of the 4000psig, 3 stage compressor, assuming water cooling on the aftercooler, water content after demisting appears to be 30 lb/mmscf - too high. If you use chilled glycol to get a discharge gas at say 50degF instead, ( given chilled glycol is at 35-40degF), then water content...
  9. georgeverghese

    Dew point for RNG

    So where is your concern here ? Are you uncertain of the dehydration effectiveness at the 200psig, -40degF unit, guessing from your post that you dont wish to take credit for the water vapor removed at the downstream alumina and activated carbon units ? Is this where you are currently relying on...
  10. georgeverghese

    Dew point for RNG

    Most facilities / process engineers in the gas business should have a copy of the GPSA Handbook -see the chapter on Gas Dehydration where you will find the McKetta charts for water content of natural gas streams, covering pressures up to 10 000psia. At 4000psig, some extrapolation is required to...
  11. georgeverghese

    Real or ideal cp/cv for orifice sizing

    In all cases, it should be real gas isentropic exponent. There are pressure and temp ranges when real values approach ideal - see your thermo textbooks. Semi ideal and ideal values may be used as an approximation for low pressures, ambient temp ranges typically.
  12. georgeverghese

    U-bend before pump suction inlet.

    That is one way to keep the pump casing primed on shutdown, but I dont see a way to prime the suction riser going down to the cold well if it all dribbles out through a leaking foot valve.
  13. georgeverghese

    Wet scrubber - what happens if you continue to re-circulate a scrubbing liquid?

    Calcs I've done now tell me that at 50% DMF solution ( ie. 500grams DMF per litre of solution, assuming no volume change of mixing) the saturation ppmv for DMF in the vapor space is 2800ppmv at 40degC. ( H drops from 160 at 25degC to 48 at 40degC). So, in this batch mode 100% solvent recirc...
  14. georgeverghese

    Wet scrubber - what happens if you continue to re-circulate a scrubbing liquid?

    What are the units for your value of H? Compilation on the net tell me H at 298degK, 1 atm is 160gm moles/m3 of solution per 1Pa partial pressure of DMF in the vapor space, while d(ln H)/d(1/T) = 7500 (units in deg K) - does this match up with your value of H ? If you dont have the value of...
  15. georgeverghese

    Process Chill Water Loop for Multiple Machines with varying requirement.

    What about the pump performance - does it match the duty case Q- h requirement ? Ask a process engineer to sort this out for you. a) The "return line shutoff valve" can be replaced with a constant dP control loop, which should then act as a pump min flow control mechanism and provide a...
  16. georgeverghese

    TEMA DEU/CEU Heat Exchanger - Connection Challenges & Analysis

    If tube side fluid leakage to shellside is a significant safety or production related concern, then a double tubesheet may be used. Here, the tube bundle goes through 2 tubesheets in series. The interspace between the 2 tubesheets is operated at a pressure less than the min normal operating...
  17. georgeverghese

    Wet scrubber - what happens if you continue to re-circulate a scrubbing liquid?

    It depends on the gas flowrate and the number of NTUs' you have in this packed bed. Do you have this value for the NTUs' ( or some other similar data) for your column? Run the calcs for this with the expressions you find for rating packed beds in your chem engg textbook on mass transfer. For...
  18. georgeverghese

    TEMA DEU/CEU Heat Exchanger - Connection Challenges & Analysis

    Is there some key concern with tubeside to shellside leakage past tube to tube sheet joints in this case: "Exchanger Tubes: SAF 625 (Strength expanded and strength welded)" If it helps, at a considerable cost adder, use a double tubesheet.
  19. georgeverghese

    Wet scrubber - what happens if you continue to re-circulate a scrubbing liquid?

    Mass transfer is also affected when you have maldistribution of liquid over the cross section of the absorber column. The configuration of the first distributor, redistributors every several ft of length also are key factors, especially for packed bed units. Keep vapor velocity within...
  20. georgeverghese

    pumps

    It is very likely that you've got vapor carry under in to the suction line of P102 - this will result in reduced pumping capacity at P102 and erroneous readings from that flowmeter. Can you describe how this de aerator works ?

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