Results 1 to 3 of 3
  1. #1
    Join Date
    Nov 2009
    Location
    USA
    Posts
    14
    Rep Power
    0

    Outsider Alert.....Need your expertise..Level controls



    It has been awhile, since I needed to come back and beg for your great knowledge. Firstly, so that you are not concerned - I do not touch nor operate ammonia systems - my job is to evaluate the Process Safety Management programs. I have come across something - that is making my eye lids twitch....not good. But I do not know enough about the technical ammonia stuff to know to trust my instincts.

    So couple of basic questions: All to do with level controls
    1.) Should all oil pots/seperators have level controls? In this facility some do and most do not - so logic would tell me what is good for the goose is good for the.....

    2.) same question for heat exchangers - I know that levels inside of the heat exchanger are rather important, and most systems I have looked at have a means for level of liquid in the exchanger - but again in this facility one has one and one does not.....

    3.) Thermosiphon vessel - I would think that this should have a level control - because if it is starved for liquid - then your cooling capacity is shot - right????

    I am seeing a trend here - so maybe the better question is should all vessels (regardless of use: heat exchanger, thermosiphon, oil pot, intercooler....) have a level control/cutoff?

    I want to make sure that if these types of vessels should have level controls but don't- I want to ask enough follow-up questions about how they are ensuring the system is not overfed liquid (like to compressors) or underfed (like to heat exchangers) - and does the process hazard analysis also look at the correct "what if questions" and control methods.

    I always appreciate your forum's insight. I know you probably are annoyed by the simplicity of the questions - but I will never know if I do not ask. I hope all had a wonderful EASTER. Thanks in advance for any responses.... Seaturtle....



  2. #2
    Join Date
    Jan 2006
    Location
    Croatia
    Age
    62
    Posts
    2,121
    Rep Power
    23

    Re: Outsider Alert.....Need your expertise..Level controls

    Hi, bsh3239

    Quote Originally Posted by bsh3239 View Post
    It has been awhile, since I needed to come back and beg for your great knowledge. Firstly, so that you are not concerned - I do not touch nor operate ammonia systems - my job is to evaluate the Process Safety Management programs. I have come across something - that is making my eye lids twitch....not good. But I do not know enough about the technical ammonia stuff to know to trust my instincts.

    So couple of basic questions: All to do with level controls
    1.) Should all oil pots/seperators have level controls? In this facility some do and most do not - so logic would tell me what is good for the goose is good for the.....
    No, not need always, but it will be good almost always to have some kind of control, electrical - sensor or float or visual-sight glasses ... for oil pots at least will be good to have sight glasses...


    Quote Originally Posted by bsh3239 View Post
    2.) same question for heat exchangers - I know that levels inside of the heat exchanger are rather important, and most systems I have looked at have a means for level of liquid in the exchanger - but again in this facility one has one and one does not.....
    some types of HE (S&T) should have a level control devices to control the level, but some time if we have controlled/calculated charge of refrigerant and feeding with float valve it is not needed to have some control giving electrical signal ...


    Quote Originally Posted by bsh3239 View Post
    3.) Thermosiphon vessel - I would think that this should have a level control - because if it is starved for liquid - then your cooling capacity is shot - right????
    on thermosiphon HE level control meaning to control level of refrigerant within is not needed - it will be OK to have sight glasses on liquid and return line close to HE, but many manufacturers are not installing this one ... technicaly, if you have liquid in the priority vessel where from you feed your thermosiphon HE, there must be liquid within thermosipon HE i.e. it is flooded ... is it that HE working OK or not is another qestion...


    Quote Originally Posted by bsh3239 View Post
    I am seeing a trend here - so maybe the better question is should all vessels (regardless of use: heat exchanger, thermosiphon, oil pot, intercooler....) have a level control/cutoff?
    if you need control/cutoff, then you should have it or sometimes if needed to have some sort of warning signal i.e. empty at some level/full at some level is also OK, but all of vessels not need to have it .....


    Quote Originally Posted by bsh3239 View Post
    I want to make sure that if these types of vessels should have level controls but don't- I want to ask enough follow-up questions about how they are ensuring the system is not overfed liquid (like to compressors) or underfed (like to heat exchangers) - and does the process hazard analysis also look at the correct "what if questions" and control methods.

    I always appreciate your forum's insight. I know you probably are annoyed by the simplicity of the questions - but I will never know if I do not ask. I hope all had a wonderful EASTER. Thanks in advance for any responses.... Seaturtle....
    if we have controlled,calculated charge of refrigerant and some other mechanical devices (float valve) to control level it is valid both for

    ... your questions are simple, but answers are not at all ... it is not easy to give a good simple answer, especially like in your case .... can be YES and NO, but not always and not at all places...

    Process hazard analysis-cannot cover all and give you correct answers (read my sig-first row), with all my respect to your job (sometimes it is like hunting on witches-not sure is this right expression) especially nowadays .... many, usually ignorant persons are trying to represent ammonia as a public enemy - what is not correct at all ... it is dangerous matter, but with correct manage ammonia is our big friend, created by mother nature .... and you know in the nature we have a lot of nice things, but some dangerous too ...

    To give some better answer you must ask very concise question ....

    I believe some other RE members will attribute to your question with their views to your question/s.

    Hope this will be of some help.

    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.

  3. #3
    Join Date
    Nov 2009
    Location
    USA
    Posts
    14
    Rep Power
    0

    Smile Re: Outsider Alert.....Need your expertise..Level controls

    Josip:

    THANKS - your response has given me exactly what I needed. Each system has its own pulse - so I do not make assumptions. I need people like you that take the time to share with me the tricks of the trade. I really appreciate it.....Seaturtle....

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •