Steam boiler requirements

Discussion in 'Boat Design' started by JamesC, Feb 1, 2016.

  1. JamesC
    Joined: Feb 2016
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    Location: Malaysia

    JamesC New Member

    Hi all, Im currently doing a barge design carrying palm oil and currently having problems with the steam boiler capacity. The requirements calls for the heating up of palm oil from 50 to 60 deg cel. in 48 hours time, so as not to exceed heating more than 5 deg cel. per day. My palm oil tank capacity is 5000m3 and after calculating heating require to raise the temperature and factoring in the heat loss to D.B, side void tank and atmosphere my steam requirement is ~54000kg/h, which calls for a very huge boiler, hence i was unsure if my calculations had gone haywire. Was wondering if anyone have any ideas on how the capacity could be reduce?
     
  2. Heimfried
    Joined: Apr 2015
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    Heimfried Senior Member

    The needed power to heat up the oil without heat losses should be about 600 kW.
    54000 kg/h Steam (you didn't specify the conditions) could provide a power of 28000 kW.
    Maybe I'm wrong.
    High losses.
     
  3. TANSL
    Joined: Sep 2011
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    TANSL Senior Member

    You can improve system efficiency by increasing the length of the coil or reducing heat losses, for example, isolating the outside of the walls.
    I hope I have not said many nonsense.
     
  4. JamesC
    Joined: Feb 2016
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    JamesC New Member

    I think i might have gotten a formula wrong;

    My total heat requirement - 620kW (heating up) + 420kW (heat loss) = 1040kW
    Steam Enthalpy at heating coil inlet = 2762.75 kJ/kg
    Steam Enthalpy at heating coil outlet = 2693.11 kJ/kg

    Steam requirement = 1040 * (2762.75 - 2693.11) * 3600 = ~54000kg/h
     
  5. philSweet
    Joined: May 2008
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    philSweet Senior Member

    1040kW * 3600 kJ/hr per kW / (delta h kJ/kg) = kg/hr, yes?

    Are you not condensing any of the steam?
     
  6. JamesC
    Joined: Feb 2016
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    JamesC New Member

    Yes;

    There will be a steam condenser in the system.
     
  7. JRD
    Joined: May 2010
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    Location: New Zealand

    JRD Senior Member

    You are missing the latent heat of steam. If you condense in your coil you end up with water. At 100 deg C the enthalpy of water is 419kj/kg That increases your available specific energy massively.
    Depending on the available pressure, you could install an orifice plate in the condensate line to flash it back into LP steam and use it as a preheat.
    I don't know if palm oil is sensitive to shear, but you could install the heating coil into a recirculation pumping loop which could give very precise temperature control.
     
  8. JamesC
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    JamesC New Member

    Oh.

    That means my steam requirement would be 1040kW * 3600 / (latent heat of steam at heating coil outlet = 2226.23kJ/kg); which would reduce my boiler size considerably. Thanks!
     
  9. daiquiri
    Joined: May 2004
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    Location: Italy (Garda Lake) and Croatia (Istria)

    daiquiri Engineering and Design

    These calculations and the plant design seem to be necessary for your business. Thus, you should consider them as very important for you and your (or your client's) finances.
    So why are you doing these calculations (with evident conceptual and calculation errors) on your own instead of seeking a professional help from an engineer with experience in steam plants, or at least in thermotechnics?
    Once you have these basic numbers, who will design the actual plant and who will build it? A 1 MW steam plant is not something you can improvise.
     

  10. JRD
    Joined: May 2010
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    JRD Senior Member

    daiquiri is right, in addition there will be regulations in your country governing the design, construction and operation of steam boilers. All the equipment and pipelines will need to be certified and tested. You may require a qualified steam engineer to run it depending on the size.
    I'm not familiar with Malaysia but most countries recognise either ASME from USA, BS5500 UK or PED directive in Europe for pressure equipment design. Probably additional codes to follow in marine situation.

    Surely there are existing designs being use Palm oil shipment already. Find out who designed and built them and talk to the engineer to find out which rules apply to you.

    You will have no choice but to employ a certified engineer to design the boiler system, you may as well let them do the whole job.
     
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