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Thread: Motor sizing!!!

  1. #1
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    Motor sizing!!!



    Hello Everyone....
    I am wondering how you choose kW rating of the motor in terms of compressor cooling capacity??(talking about open drive single screw ammonia compressor)..
    For example what motor capacity i should pick for a compressor block with 300kW cooling capacity for given conditions???
    Thanks in advance



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    Re: Motor sizing!!!

    Quote Originally Posted by bjkmiami View Post
    Hello Everyone....
    I am wondering how you choose kW rating of the motor in terms of compressor cooling capacity??(talking about open drive single screw ammonia compressor)..
    For example what motor capacity i should pick for a compressor block with 300kW cooling capacity for given conditions???
    Thanks in advance
    Need compressor type exactly & conditions sct & sst, economizer, liquid injection cooling if used, speed etc

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    Re: Motor sizing!!!

    Quote Originally Posted by RANGER1 View Post
    Need compressor type exactly & conditions sct & sst, economizer, liquid injection cooling if used, speed etc
    J&E Hall
    speed:2980rpm
    Full load capacity:275kW
    suction mass flow rate:0.24kg/s
    External oil cooling:37.5kW(no liquid injection)
    No economizer
    Design conditions -10C/+35C

  4. #4
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    Re: Motor sizing!!!

    At least 110 kW for NH3,
    It's better to keep your mouth shut and give the impression that you're stupid than to open it and remove all doubt.

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    Re: Motor sizing!!!

    Quote Originally Posted by Peter_1 View Post
    At least 110 kW for NH3,
    Hello Peter,
    can you tell me the correlation between them please..how did you come up with that number?
    Thanks.....

  6. #6
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    Re: Motor sizing!!!

    There's no exact correlation, as soon you change 1 parameter, needed power will change. I did a simulation via another brand.
    You also can plot this on a log p/h chart and calculate it very precisely. Or you can use Coolpack or any other simulation like Solkane,...
    It's better to keep your mouth shut and give the impression that you're stupid than to open it and remove all doubt.

  7. #7
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    Re: Motor sizing!!!

    Hi, bjkmiami

    Quote Originally Posted by bjkmiami View Post
    J&E Hall
    speed:2980rpm
    Full load capacity:275kW
    suction mass flow rate:0.24kg/s
    External oil cooling:37.5kW(no liquid injection)
    No economizer
    Design conditions -10C/+35C
    For your capacity seems you need or have HSO 3220 compressor ... actual power consumption is about 72 kW (Q=272kW at -10/+35 NH3 data from J&H brochure), but you need to contact J&H and ask for compressor starting torque and then to order electrical motor with adequate starting and pull up torque otherwise you won't start the compressor (believe me-I was there) ... this is not a question only about motor power in kW ...

    Check links below and see by yourself .... a lot to read, but worth all the time spent ...

    http://www.johnsoncontrols.com/conte..._-_610_sed.pdf page 14 ...

    http://www05.abb.com/global/scot/sco...32060m0201.pdf

    http://www.asercom.org/fileadmin/use...Guide-book.pdf

    http://www.schneider-electric.hu/doc...-and-loads.pdf

    http://www.fjb.co.uk/wp-content/them...ompressors.pdf

    My suggestion is, if you are not sure what do you need ask someone for professional help ...

    Hope this is of some help to you ..

    Best regards, Josip

    It's impossible to make anything foolproof because fools are so ingenious...

    Don't ever underestimate the power of stupid people when they are in large groups.

    Please, don't teach me how to be stupid....
    No job is as important as to jeopardize the safety of you or those that you work with.

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