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  • Users: Orsiz
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  1. Orsiz

    Effect of present of methanol in ethane feed to olefin plants

    I only have experience with methanol present in propane feedstocks and there it is intentionally added to prevent freezing of the free water present in this feed. The methanol can act as a poison for the catalytic reaction in the downstream process, handling the propane feed, and is therefore...
  2. Orsiz

    Restriction Orifice sized but choke

    The pressure downstream the RO is the available back pressure plus the frictional losses between the orifice and downstream pressure source, calculated for the specified flow rate. The additional drop in pressure energy beyond the choked flow condition will be converted in other forms of energy...
  3. Orsiz

    DP for designing a control valve

    When you design for example a flow control valve, the differential pressure is determined by the process system in which the control valve will operate. Imagine you have a source at a pressure of 5 barg and a receiver at a pressure of 1 barg. The source and pressure are connected by a process...
  4. Orsiz

    Vent sizing

    The first step here is to determine the maximum inbreathing and outbreathing flow rates (thermal effects, filling/emptying of tank, ...). Based on this information and the MAWP of the vessel, the vent can be sized. The length and size of the vent determines the maximum over- and underpressure...
  5. Orsiz

    Determining pump flow from pump curve and pressure gauge

    What does the suction side look like? Is the fluid pumped out of an atmospheric vessel? Do you know the static head? Is the amount of suction piping and corresponding fittings small? Based on this information, the suction head can be estimated. As you know the discharge pressure, the TDH and...
  6. Orsiz

    Heating Hot Water Differential Pressure Bypass Valve

    Can you provide a PFD/P&ID of the system? You can use a self-acting backpressure regulator at the end of the line which will prevent the pumps from dead heading. The valve can be sized for the full pump flow.
  7. Orsiz

    API 521 Noise Calc, Figure 18

    Is 14.7 the absolute pressure at the PSV outlet? Did you include the pressure drop across the discharge pipe at the relief flow rate?
  8. Orsiz

    Steam control valve sizing

    You know the inlet pressure and flow rates. The next step is to calculate the pressure drop, at the specified flow rates, in each segment taking into account al system components (pipe, fittings, steam trap, elevation, ...). The resulting pressure between the steam supply pressure and downstream...
  9. Orsiz

    Check PSV Required Capacity

    The link below provides an example of a product bulletin for the MR95 pressure regulator series: https://www.emerson.com/documents/automation/product-bulletin-mr95-series-en-122532.pdf On page 9, the wide open coefficients are given. These are used when sizing a PSV for this particular type of...
  10. Orsiz

    Governing scenario for PSV?

    @LittleInch: The shell is designed for 6 barg, which is the set pressure of the mentioned PSV (that's basically the only process related thing I know about this relief valve). The PSV is the only form of relief, no other form present. ODDR is the orignal design data report, the relief valve was...
  11. Orsiz

    Governing scenario for PSV?

    Dear all, I need your help in determining the reasoning behind a PSV in on of our water heating systems. The system is as follows: a shell-and-tube heat exchanger in which water (tube side, 6 barg, 20°C) is heated by low pressure saturated steam (shell side, 1,7 barg; 131°C) to approximately...
  12. Orsiz

    What is the pressure drop across a flow control valve?

    The pressure drop across the control valve is up to you as you know the system in which the valve is operating. Search for two points (up- and downstream of the control valve) in your system where the pressure is known. The pressure difference between those two points is the driving force in...
  13. Orsiz

    Outlet of PSV on shell-and-tube heat exchanger

    Ehzin, I still have to check the presence of a bleed hole in the outlet piping of the PSV. If this would be the case, then I indeed believe the original designer assumed liquid relief in the beginning. After some time (HX discharge still blocked), steam would be relieved. Do you agree? Orsiz
  14. Orsiz

    Centrifugal pump effieciency

    You know the flow rate. I would suggest to check the discharge pressure on a local gauge or transmitter. The suction pressure can also be checked or calculated. You then know the differential pressure and thus the required pump head for the given flow rate. Now select a pump that can provide...
  15. Orsiz

    Is a Safety Relief Valve required if protecting against a Fail-Open Valve failure?

    Although these valves are FO, I think you can't exclude that these valves get stuck in the closed position. In that case, the pressure should be relieved via the PRV.
  16. Orsiz

    Outlet of PSV on shell-and-tube heat exchanger

    Ehzin, The normal water flow is 26 m3/h. There is a control valve upstream of the HX which regulates the steam flow depending on the water temperature. There is no control valve on the water side. The steam works off a simpele steam trap. Steam (130°C) design flow: 1500 kg/h Water (15°C ->...
  17. Orsiz

    Outlet of PSV on shell-and-tube heat exchanger

    We indeed don't want any hot water in the building but the problem in my case is that the outlet of the PSV immediately goes upward vertically. If the PSV should open, the releasing hot water can't escape the outlet piping.
  18. Orsiz

    Outlet of PSV on shell-and-tube heat exchanger

    The water flow through the HX is provided by a centrifugal pump. The max discharge pressure at zero flow condition is 8,7 barg (system design pressure is 10 barg). The normal operating pressure is around 7,9 barg. Regarding the flashing of to steam. How can you know that the water temperature...
  19. Orsiz

    Outlet of PSV on shell-and-tube heat exchanger

    Latexman, These documents should be indeed available but they aren't for our plant (I looked in the original design documents of the plant, but no success). I could only find a datasheet with specified set pressure, relief area and construction materials.
  20. Orsiz

    Outlet of PSV on shell-and-tube heat exchanger

    Thank you for your insights. No flammable liquids are present near/below the HX. The only surrounding fluids are hot air, low pressure steam and water. Is a tube rupture scenario possible hear as a scenario? The tube (water) side is the HP side, the shell (steam) side is the LP side.

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