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  1. #1
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    Arrow Modern NH3 Refrigeration Plants



    Hi,
    I have attached a photo of a NH3 refrigeration plant, this plant has two 150hp compressors fitted to a common oil separator and Low Pressure Receiver. This is a 5 year old plant, with the picture taken last week when I was on site.
    The photo is a side veiw with the black insulated LPR on the left and the screw pack on the right.
    All comments apreciated good or bad, I hope the photo comes out alright give us a shout if it doesn't.
    Regards. Andy.
    Attached Images Attached Images



  2. #2
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    Errrr.....

    Looks..."compact" doesn't it. Which generally means you cannot get to anything important without hanging by your toes off some steel beam.

    Perhaps we ought to have new thread here...do the people who design plants and machinery ever get to think about servicing them..

    Integrated hydraulics - there's a good phrase - means you have to be a triple jointed midget to get at anything - perhaps these designers have something in common with the makers of these packaged units that equipment makers are trying to sell us.

    I realise now why I have never seen an overweight fridge engineer - they would never stand a chance getting to the gear to service it

    Steve

  3. #3
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    Talking Compact Plant

    Hi, Steve
    I suppose from that side it does look compact, that's the side that I normally wouldn't be working at much. I have attached another photo of the unit from the frount showing the two Howdens. The whole thing is 20' long, not so compact really, not a bad unit to work on, the big bits are very easy to get at.
    But you are right, some units are real pigs to work at, that ice rink pack was a bit tight for working at, especially if you had to take the heads off No3 compressor.
    I hope the picture below looks a little better to you.
    Regards. Andy.
    Attached Images Attached Images

  4. #4
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    Hi Andy, doesnt look to bad to work on. What kind of screws are those? I do alot of work on the Frick screws and am curious to find out about some of the other brands out there.

  5. #5
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    Hi Industrial Tech,
    welcome to the Industrial Section
    Theses are Howden screws, built in Glasgow. 165-145 rotor profiles and the smallest product we use from Howden.
    Quite a nice screw to work on and simple to work on.
    Everlasting, given a little care and maintenance.
    On this side of the pond, Fricks were sold by Gram under licience
    I have worked on a few, with little bother, except the dinky little LVDT used to give the slide position to PLC controller.
    Regards. Andy

  6. #6
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    Alright Andy
    Have you worked on any Stal screws I have worked on the vertical mini screw using thermo syphon oil coolers seemed a decent machine
    regards Dave

  7. #7
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    Hi, Dave,
    I have not worked on any Stall screws recently. I am afraid to say the Stal mini-screw has a bad name in Ireland, or at least in the circles I move in. Although this is probably down to one contractor who mis-applied them on most of his industrial plants. These plants were nearly alway DX R22, with a hot gas defrost that dumped liquid into a suction accumulator, which had no boil off coil, leading to flood back.
    Worked on a few Stal Recips, now those are a great machine
    Are they still made. I doubt it as they were far to good and nearly everlasting, not what manufacturers want today
    Marc
    As I recall, the twin screw is still made under licence from the original patent and profile developed in Sweden
    SRC or something similar profile name.
    Regards. Andy

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    Hi Marc,
    roughly translated as Swedish Rotor Machine
    Regards. Andy

  9. #9
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    The last Stahls I voluntarily worked on had just catastrophically failed.... They had shaft-driven oil pumps. As those shaft drive bearings failed, they fell out of the race, and straight into the suction of the screw.... Screaming one minute, and a sound like a buzzsaw... then silence. Those were probably 1970s models. Since Stahl is now associated with one those larger manufacturers...

  10. #10
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    Re: Modern NH3 Refrigeration Plants

    hey,

    I am a finaly year chemical engineering student studying in the UK. I have my final design project which is due in two weeks. I am a bit stuck with this as I haven't got much knowledge on this subject. My project is to design a chiller with NH3 as the refrigerant. this chiller is used to cool a water stream that comes out of a condenser at 20 C down to 3C. I specified the temperatures of the NH3 stream to be -45 C to 15 C and calculated the flow rate. Anyways I just wanted to get some basic idea about the main components of such a system and thing that you think might be useful for my design. Gosh you would be a life saviour if you could help out.. thank you...hope to hear from you soon

  11. #11
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    Re: Modern NH3 Refrigeration Plants

    Hi, ask

    Quote Originally Posted by ask View Post
    hey,

    I am a finaly year chemical engineering student studying in the UK. I have my final design project which is due in two weeks. I am a bit stuck with this as I haven't got much knowledge on this subject. My project is to design a chiller with NH3 as the refrigerant. this chiller is used to cool a water stream that comes out of a condenser at 20 C down to 3C.
    .... so you have to cool water having freezing point at 0*C

    Quote Originally Posted by ask
    I specified the temperatures of the NH3 stream to be -45 C to 15 C and calculated the flow rate. Anyways I just wanted to get some basic idea about the main components of such a system and thing that you think might be useful for my design. Gosh you would be a life saviour if you could help out.. thank you...hope to hear from you soon
    ... why you decide to use ammonia with temperature of -45*C

    .... can you make a sketch of your system showing where you think to have ammonia with -45*C to 15*C

    ... try to think about chiller with evaporating temperature of ammonia at 0*C

    BTW you should open a new thread with your question and not to use this one 5 years old

    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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