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  1. greenche

    Improving HRSG performance if air side pressure loss is not an issue

    Increasing pressure loss alone does not increase output, it only allows you to do other things in the design that may. One way to look at HRSG efficiency is by looking at gas outlet temperature. This can be limited by pinch, but there are also ways around this. This article by Ganapathy may...
  2. greenche

    Improving HRSG performance if air side pressure loss is not an issue

    Ed is correct, heat transfer in an HRSG is usually gas-side limiting, so a well designed unit is designed to use the maximum pressure loss that the GT can handle. If a higher pressure loss is available for the design, it can be used to make the HRSG smaller which should result in lower cost.
  3. greenche

    Acid gas dew point corrosion phenomenon in incinerators

    Cold end corrosion is primarily dependent on the sulfur content of the fuel and the temperature of the cold surface. For example in boilers, raising combustion temperature doesn't mitigate it much since the temperature of the tube metal is primarily dependent on water temperature. So you should...
  4. greenche

    ACHE Air Side Control

    The thought process is likely that for low air flows, the on/off-controlled fan is off and the VFD-controlled fan provides adjustment. For higher air flows, the on/off-controlled fan is on and the VFD-controlled fan provides adjustment. As to whether this would provide the desired results would...
  5. greenche

    Team work schedules

    I'll put in a second vote for Trello. We used it for almost exactly what you are describing. Can use it from the desktop (browser-based), or mobile app. Typically we would have a Board for each person and "To Do", "Doing", and "Done" lists on each person's board. Its easy to move items...
  6. greenche

    Car seals

    I would expect valves car sealed for safety to have some sort of administrative procedure to document that the process was in a safe condition for the valve to be operated when the car seal is removed. We do not use this term specifically, but we do identify valves on the P&ID that are car...
  7. greenche

    Toroidal Ring.

    The above link is not the type of toroidal ring you need. Vent stack toroidal rings are essentially a small (1/2" to 1") diameter piece of SS tubing bent into a circle (ends welded together) with the same center line diameter as the vent stack pipe and welded to the end of the vent stack. A...
  8. greenche

    External fire on equipment: standard practice re: associated pipe

    In the refining industry I have seen it both excluded and added as a percentage of the equipment area (e.g. an additional 10-20%) but more often excluded. This can be interrelated with how the company handles calculation of the heat of vaporization and the confidence level in the description of...
  9. greenche

    Emergency vent sizing for ATM Tank - API 2000

    API 2000 does not in all cases give absolute requirements on which potential causes of overpressure are applicable to a particular tank. This may require evaluation based on the particulars of the tank. It's good to have a sound engineering basis for determining applicability of scenarios and...
  10. greenche

    Emergency vent sizing for ATM Tank - API 2000

    Nik, See NFPA 30 section 22.7.1 for this exception.
  11. greenche

    PORV during and after steaming operation

    We have had the scenario hageye describes actually happen. We considered this a very serious near-miss. As a result, in pilot operated RVs that could encounter water (from the process or steaming) we have changed the soft goods to withstand higher temperatures and have added steam tracing and...
  12. greenche

    self secure design

    Could they mean "overpressure protection by system design?" See ASME Sec VIII Div I, UG-140.
  13. greenche

    Double Precision and Modules

    Instead of integer, parameter :: dbl = selected_real_kind(p=7) Try integer, parameter :: dbl = selected_real_kind(1.D0) and specify all real constants like 0.1 as 0.1_dbl
  14. greenche

    Solid floor: air coolers: fire zone increase due to???

    For liquid coolers, see API STD521 (5th ed) section 5.15.7.4. It becomes a question of whether your solid floors qualify as a "surface at which a major fire could be sustained". If so then it requires relief. If your floors are designed so that the drainage is adequate then it does not. If...
  15. greenche

    Super Capacity Pressure Relief Valves

    We use Farris valves extensively, mainly the 2600 series you are referring to. No specific experience with the super capacity valves, but the main drawback I see is weight. Those things are heavy! Otherwise, they are built to ASME Section VIII and capacity certified. Acceptability beyond...
  16. greenche

    What is this thing on a deaerator?

    It is a chemical injection quill. The threaded rods prevent the quill from being ejected when it is removed so that the quill can be changed on-line while there is still internal pressure. This type of design is common, although I have usually seen it used with a full-port ball valve to allow...
  17. greenche

    Calculation of Constant backpressure, superimposed pressure and variab

    If RV "A" is relieving due to fire and you want to know the backpressure on non-flowing RV "B", it is the pressure in the main flare line due to the flow from RV "A" where the tailpipe from RV "B" ties into the main flare line. To generalize, look at the pressure in the main flare line due to...
  18. greenche

    Calculation of Constant backpressure, superimposed pressure and variab

    If you want to look at the scenario where only one valve is relieving, calculate backpressure by calculating the pressure drop from the RV outlet through the flare tip. Base your flow rate on RV capacity at the overpressure for the scenario you are evaluating. If backpressure is high enough...
  19. greenche

    Calculation of Constant backpressure, superimposed pressure and variab

    While using a balanced bellows RV as JAlton suggests can allow the RV to handle higher variable backpressures, I respectfully disagree that you can simply install a bellows and "forget the issue." Even with a balanced bellows RV it is still possible for the variable backpressure to be greater...
  20. greenche

    Flow resistance in piping bends

    http://rapidshare.com/files/170379460/Pressure_Losses_For_Fluid_Flow_in_90_Degree_Pipe_Bends.pdf.html

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