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Thursday, November 6, 2008

Simple Method For Compressor Settle Out Using HYSYS

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Compressor emergency blowdown is commonly initiated after compressor system shutdown. The compressor shutdown will also lead to Compressor System Suction shutdown valve (SDV) and Discharge SDV to shut close and the anti-surge and/or capacity control valve open. Compressor discharge with high pressure and hot, air cooler and downstream high pressure and cold and suction vessel low pressure and cold will be settled-out prior to blowdown.

How to estimate the settle out condition ?

Settle-out of compressor system can be conducted using HYSYS. The main concept is constant mass and volume before and after settle-out. It is assumed the settle out is carried out adiabatically.

Following are some steps can be used to obtain the settle-out condition. Let start with following image.



Step 1 : Calculate physical volume of Compressor Suction (V1), Compressor Discharge (V2) and Air Cooler Downstream (V3).

Step 2 : Setup the system as per above image by correct Compressor Suction, Compressor Discharge and Air Cooler Downstream operating condition and composition.

Step 3 : Adjust Compressor Suction, Compressor Discharge and Air Cooler Downstream Mass flow until the respective Actual Volumetric Flow same as V1, V2 and V3.

Step 4 : Set Balance (BAL-1) for Mole & Heat

Step 5 : Adjust Settle-out Cond stream pressure until the Actual Volumetric Flow same as V1+V2+V3.

Thus, the settle out condition can be extracted from the Settle-out Cond stream.

Do you aware of other method ? Why not share with us ?

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4 comments:

  1. Hai,
    I have used Hysys dynamic depressuring utility to calculate the settle put pressure.


    Regards,

    Kathiravan.

    ReplyDelete
  2. Kathiravan,
    Thanks for your advice.

    It should be an interesting method. Do you mind to share with us or drop me a note ?

    E-Add : webwormcpt.wwcpt@gmail.com

    Webworm

    ReplyDelete
  3. Instead of using BALANCE, why not just put a valve between the streams "mixed" and "settle-out cond" as described by Aspentech?

    KON

    ReplyDelete
  4. The Settle-out pressure will be higher than the Compressor suction. BALANCE allows higher pressure.

    ReplyDelete

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