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Pressure Safety Valve for Coke Drums

Home Forums Coking Maintenance Pumps, Valves, Rotary Joints, Cranes Valves Pressure Safety Valve for Coke Drums

This topic contains 2 replies, has 2 voices, and was last updated by  antonio saura Cebrian 11 years, 8 months ago.

  • Author
    Posts
  • #2735

    Freddy Martinez
    Participant

    We are the engineering company involved in Delayed Coker construction in Russia, Volgograd Region.

    At the moment we are in the stage of selection of Pressure Relieve Valves (PRV) for the Coke Drums. We have two drums coker with 12 hours cycle, each of the coke drum is equipped with 3 flanged outlets for PRV mounting. Coke feed temperature is +940F, minimum ambient temperature is minus 31F.

    Please advise and/or express your experience what PRV design is superior for such service Direct Spring Operated or Pilot Operated Valves?
    We want your expert knowledge in order to make right decision for reliable and safe operation.

  • #5718

    In the coker unit that Ive been involved we have installed this kind of safety valve, they are working properly, I dont know if there are some problem with the minimum temperatura for this type of material (bellow), only for reference
     

     
    Tag Number
     
     
     
     
     
     
     
     
     
     
     
     

     
    P&ID Dwg. No.
     
     
     
     
     
     
     
     
     
     
     

     
    Service
     
     
     
     
     
    Coke Drum 
     
     

     
    Line No. / Equip. No.
     
     
     
     
     
     
     
     
     
     

     
    Full / Semi / Base Nozzle
     
    Semi
     
     

     
    Safety or Relief
     
     
     
    Relief
     
     

     
    Conv. or Bellows
     
     
     
    Balanced Bellows
     
     

     
    Bonnet Type
     
     
     
    Closed
     
     

     
    Size:  Inlet  |Outlet
     
     
     
    12 INCH
    12 INCH
     
     

     
    Flange Rating / Scrwd: In | Out
    900#
    900#  
     
     

     
    Flange Facing
     
     
     
    RF
    RF
     
     

     
    Body and Bonnet
     
     
    5 Cr – 1/2 Mo A217 / 304 SS
     
     

     
    Seat and Disc
     
     
     
    316 SS
     
     

     
    Resilient Seat Seal
     
     
    N/A
     
     

     
    Guide and Rings
     
     
     
    ASTM A297 Gr. HE / 316 SS
     
     

     
    Spindle
     
     
     
     
     
    416 SS
     
     

     
    Spring
     
     
     
     
     
    Alloy Steel
     
     

     
    Bellows
     
     
     
     
     
    Inconel 625
     
     

     
     
     
     
     
     
     
     
    Note (**)
     
     

     
    Cap:  Screwed / Bolted
     
    Screwed
     
     

     
    Lever:  Plain / Packed
     
     
    No
     
     

     
    Test Gag
     
     
     
     
    No
     
     

     
    Vent with Bug Screen
     
     
    Yes
     
     

     
    Bonnet / Spring Coating
     
    Aluminized
     
     

     
    Manufacturer
     
     
     
     
     
     
     
     
     
     
     

     
    Model No.
     
     
     
     
     
     
     
    12 V 12
     
     
     
     

     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     

     
    Outline Dimensions
     
     
    Certified Dimension Outline
     
     

     
    1.
    Two relief valves required for adequate capacity
     
     

     


     

    Code  |  Stamp
     
     
     
     
    ASME VIII,  UV

    Fire / P.F. / B.D. / C.W.F.
     
     
    B.D. During Max Quench

    Other
     
     
     
     
     
     
     
     
     
     
     
     
     

    Fluid and State
     
     
     
     
    Hydrocarbon Vapor / Steam

    Discharges To
     
     
     
     
    Coker Blowdown Drum 

    Required Capacity
     
     
     
    167747 lbs/hr (Note 1)

    Mol. Wt. or Oper. Spec. Grav.
     
    18.02
     
     
     
     
     

    Press.:  Oper.  |  Set
     
     
    psig
    659660
    661662

    Temp.:  Oper.  |  Release
     
    F
    825
    825

    Design  Press. 
    psig
    Temp
    F
    681682
    890

     
     
     
    Constant
     
     
     
     
     
     

    707708
    Center Center
    713714
    Center Center

     
     
     

    Back Press.
    Variable
     
     
     
    13 (Note 2)

     
    psig
     
    Built-up
     
     
     
    749750

     
     
     
    Total
     
     
     
    28,0

    % Blowdown
     
     
     
     
     
    779780

    % Allowable Overpressure
     
     
    787788

    Overpressure Factor
     
     
     
    1.16

    Compressibility Factor
     
     
    1.0

    Ratio of Specific Heats
     
     
    1.28

    Oper. Viscosity
     
     
     
    cP
    0.02

    Wt. % Flash  |  MW of Vapor
     
     
     
     
     
     
     
     

    Barometric Press.
     
     
    psia
    14.689

     
     
     
     
     
     
     
     
     
     
     
     
     
     
     

     
     
     
     
     
     
     
     
     
     
     
     
     
     

    915916
    Center Center

     

    Calculated Area
     
     
     
    in
    70.64
     

  • #5710

    Anonymous

    In my experience, the use of a balanced type valve (direct spring operated) is the way to go. Just make sure you do a proper material selection for the bellows (ie. Inco 625) and the spring. In regards to your -31F temperature, this should not be an issue since I imagine your valves will be located inside the winterized cutting deck enclosure.
     
    Regards, Canadian Coker.

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