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  1. Samiran

    MAWP and design pressure

    Check this faq135-133
  2. Samiran

    Smart LNG regasification

    I don't think it is the capital cost that has not boosted the use of this technology, it is probably that the technolgy has not matured enough for this application & also requirement of a threshold capacity to make this viable. I had a discussion with Ormat on this. It is only recently more...
  3. Samiran

    control valve location

    My experience is that when you have such a high delta P and flashing across a control valve, the line downstream undergoes heavy vibration and frequent damage occurs on its supports which can compromise the rates through it. Hence, the most desirable location would be to locate the control...
  4. Samiran

    BYPASS, ISOLATION OF PSV WHILE UNIT IN SERVICE

    If the philosophy is to have a PRV serviced when the plant is on-line then a standby PRV must be provided. You take a risk operating in an isolated mode. However, operating plants frequently have these scenario - for which the best tool is to carry out a risk assessment and present it to the...
  5. Samiran

    HC Gas Properties above critical point

    It is extremely important to understand that thermo properties predicted by Hysis may not be accurate at that region. So if you are designing a column operating at pressures close to critical be very careful. The liquid in the trays may not be liquids any more at the top and may run into offspec...
  6. Samiran

    Cold Box HE

    liberosim, We operate one of the largest LNG Trains in the world. And, our situation is similar to yours. We do have strainer on the feed and refrigerant side going into the cold box. Having the strainers is often the manufacturer of the cold box prerogative. Understand that cold box is one of...
  7. Samiran

    PSVs...what's missing?

    To my mind, there is a certain amount of subjectivity involved regarding a PRV design. I am not talking of the design formulae but especially the philosophy & the parameters that are used in the calculation. API 520/1 are basically guidelines and many companies choose to deviate conveniently...
  8. Samiran

    Centrifugal Compressor Discharge Pressure

    I don't understand at what stage of design you are in. But once you get the compressor curves you will be able to get the max head (near about surge). Now that may or may not determine your design pressure downstream. Why I say may not because you may take advantage of surge control valves...
  9. Samiran

    Scrub Column

    That is because you allow more propane (and a little bit of butane) to pass through the overhead in LNG if you maintain around -40. If you make it colder, more C3 goes to the bottom of SC and can be separated as LPG downstream in the fractionating section. SG
  10. Samiran

    Basic Eng. Milestones

    Your keyword is "mega project". Milestones will differ from a $100K project to a $100MM project. All mega projects need to follow "gate" system which means that you have to pass through various gates (approvals) to enter the next one. Your completion of basic engineering will lead to a detail...
  11. Samiran

    Compressor Reverse Flow Relief Sizing

    I hope a HAZOP was done to analyze this situation. What do the close-out reports say of this ? Think of the recycle valve - if that opens inadvertatently will it not overpressurize the suction ? I think a suction relief valve would be designed anyway whatever is the governing flow for the...
  12. Samiran

    Gas Separator Liquid Dump Orifice

    The downstream equipment is obviously designed for lower pressure say typically 150#. Once the blowby occurs the downstream pressure would increase which may exceed the design pressures. The orifice would restrict the flow of gas to the low pressure system such that downstream pressure do not...
  13. Samiran

    Can H2S be destroyed in the firebox?

    It will indeed be very difficult to convert all the H2S - you would need a very high flame temp (> 1200 C) and adequate residence time. However, another thing to watch out is that whether your furnace tubes are properly designed to handle this acid gases. You could be seeing cold end corrosion...
  14. Samiran

    Compressor at 100% capacity

    May I say that it can be okay to run over 100% capacity of a compressor. You really ought to look at the right parameters instead only capacity. The parameters to look is potential increase in vibration, stonewall proximity, PRV available capacity on the discharge etc. This assumes you have...
  15. Samiran

    Controller tuning problem in HYSYS-help please

    Dear Napz, What do you mean by oscillation graph ? Are you trying to say that you want to see the effect of PID parameters on your process control system. Have you entered any integral time value ? If not please do so. And also use a small change to start your control. Samiran
  16. Samiran

    Using a carbon bed filter in a system with sulfolane

    Activated carbon filter is installed to remove the HCs picked up by sulfolane that may induce foaming. However, sometimes particles of activated carbon often themselves induce foaming and hence many operators keep it bypassed - like us. Samiran
  17. Samiran

    MDEA problem

    It appears you've changed the solvent without making any mods to the column. In this case you would have to readjust your operating parameters till you get your desired result. Theoretically ( and also practically) MDEA will require less circulation rate however do incresae that if it helps...
  18. Samiran

    MDEA problem

    MDEA should be better than DIPA as MDEA is a tertiary amine and is more effective to remove H2S. Have you reduced your circulation rate ? Has foaming been taking place ? Samiran
  19. Samiran

    Detailed Design: What should be done?

    I agree with OilBoiler: The statement made above about being a degreed ChE is indeed out of place in connection with the post. I am not sure whether any school goes through what the industry follows as a part of project process. Did any body hear pre-FEED, FEED, Detail Design, EPC in school ...
  20. Samiran

    OLD MOLSIEVE! IT IS OK TO USE?

    This can be an economics issue. Determine the consequence of an offspec product - what it will lead to against buying the new mol sieves. However, usually they are nitrogen sealed (if in drums) and stay good. You can send samples to the manufacturer to check the H2O and CO2 adsrption capacities...

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