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    Sunday, 8 October 2017

    [How To] Calculate the height of vapor line of a batch reactor

    Gud day readers........!!!

    Have received some comments asking me to calculate the vapor line height of a batch reactor. Usually everybody will ask about the dia calculation, but this is something that caught my focus, because being frank i too donno the exact way to calculate the height of vapor line.

    So here today, i'll demonstrate my idea to calculate the height. If you are a new reader and searching for Dia calculation of vapour line, then follow this,



    This post is requested by Mr. Ram prasad.






    How to calculate the column dia required for a reactor ?

    How to calculate the dia of vapour column


    But before going in depth calculation, i want you to know that this is just my way of calculation, there may be a direct calculation or something, but i donno those all, and openly speaking i don't like remembering all the equations, if required i'll try to derive those equations.

    Is there any relation between the height and dia of vapour column ?
    There is nothing like that, if there is something like that earlier i should have demonstrated you, As vapour column is meant for vapour / gas transferring from reactor to condenser, and the dia depends on the boil-up that is generated in the reactor,  height should be designed based on the vapour density, if the vapour density of a solvent that i need to distill out is high then automatically the vapour won't reach much height and in between it will get condensed. 

    Anyhow, i think this knowledge is enough for getting started, if anything you need to grab just comment in the below section.




    The relation between pressure, density, height / head is given by 

    P ressure = D ensity x G ravitional constant x H eight 

    simply, P = ꝭ x g x h.

    Here today i'll calculate the vapour column height required for distilling methanol in a batch reactor.

    Now lets calculate the vapour density

    Lets make use of ideal gas law,




    P x V = n x R x T.

    P x V = ( w / W ) x R x T.

    ( P x W ) / ( R x T ) = w / V

    ꝭ = ( P x W ) / (  R x T ).

    W - boilup, R - universal gas constant, T - Boiling point or any other temp.

    P - Vapour pressure.




    Lets need to calculate the vapour pressure ( P ) and boil up ( W ),

    Vapour pressure from Antonie equation,




    Antonie equation: Log P = A - B / ( T + C ).

    A, B, C are antonie constants.

    These constants can be retrieved from google, anyway i'll provide those here,

    Open this in new tab for antonie constants.

    As the old calculation is creating some controversies, i've decided to add a new way to calculate the height of vapour line required.

    Lets the case be, a 5 KL SSR with 60% methanol inside and we need to calculate the vapour line size.

    The heat transfer area of 5 KL SSR is ~ 12.5 Sq.m,

    The effective heat transfer area will be 12.5 x 0.6 = 7.5 Sq.m [with 60% occupancy],

    Lets say the utility temp will be 80 C, and 

    Initial reaction mass temperature will be 30 C,
    Final reaction mass temperature will be 64 C,

    Lets consider 3 C of temperature difference between jacket utility in and out,

    So out let temperature will be 77 C.

    LMTD = ((80 - 30)-(77-64)) / Ln((80-30)/(77-64)) = 27.46 C.

    Overall Heat transfer coefficient will be ~200 KCal/Hr.Sq.m.C,


    Learn how to calculate overall Heat transfer coefficient

    Latent heat of Methanol is 264 KCal/Kg,

    Density of Methanol is 0.79 Kg/L, Mol wt. of methanol is 32.05 g/mol.

    Boil up rate based on effective heat transfer area is 155.97 Kg/hr,


    Learn how to calculate the boil-up rate of solvent in reactor

    Volumetric boilup is Mass boilup / Density = 197.43 L/hr,

    Lets calculate the relevant vapour pressure using volumetric flow rate from the ideal gas law,

    P x V = n x R x T,

    P = n x R x T / V,

    P = ( 155.97 / 32.05 ) x 8.314 x ( 64 + 273.15 ) / 197.43

    P = 69.09 KPas = 69092.71 Pas.

    You may like this:


    How to calculate Vent size for vessels ? 
    What is vacuum steam technology ?

    Lets calculate height based on the above mentioned relation, P = ꝭ x g x h.

    h = P / ( ꝭ x g ),

    h = 69092.71 / ( 1.1 x 1000 x 9.81 ) = 6.40 m.

    1.1 is the vapour density of methanol

    Above mentioned 1000 is to convert density from Kg/L to Kg/cu.m.


    That's it......!!!

    Now you got the height of vapour column that need to be arranged for a 5KL SS reactor for getting a boil up of 197 L methanol with 60% occupancy,

    Hope you enjoyed the calculation here....!!!

    Any queries most welcome, reach me through message / comments,

    Comments are most appreciated.....!!!!

    [**Calculation is slightly modified, thanks to Bhaskar for pointing out the error in unit conversion]


    ** The case study is changed a the previous is based on antonie equation and it'll slightly cause controversies, thats why i've modified with a fresh calculation.


    Related Articles:


    How to calculate Heat transfer area theoretically ? 
    How to produce steam at 60 C ?
    How to Design a chiller plant ?
              How to calculate U (Overall Heat Transfer Co-efficient) value ?


    About The Author


    Hi! I am Ajay Kumar Kalva, Currently serving as the CEO of this site, a tech geek by passion, and a chemical process engineer by profession, i'm interested in writing articles regarding technology, hacking and pharma technology.
    Follow Me on Twitter AjaySpectator & Computer Innovations

    68 comments:

    1. What is lowest and highest withstand temperature for GLR....

      ReplyDelete
      Replies
      1. Dear Anand,

        as per my experience, its -50 to 250 degC

        Regards,
        AJAY K

        Delete
    2. please how u got lambda value

      ReplyDelete
      Replies
      1. methanol latent heat is 264 KCal / Kg

        Regards,
        AJAY K

        Delete
    3. how got P,Lamda and Lmtd values please provide clear calculations for better understanding
      Thank you

      ReplyDelete
      Replies
      1. Latent heat (lamda) you can google it, LMTD value i've considered averagely instead of calculating

        Dear Anonymous,

        pl comment next time with identity as your comments were getting detected as spam.

        Regards,
        AJAY K

        Delete
    4. Replies
      1. convert 630.95 mmHg to Pascals, it shall be 84119pas

        Regards,
        AJAY K

        Delete
    5. AJ.. Im having one doubt reg no of moles = w/W i.e weight / molecular weight. How u considered Molecular weight W as Boilup parameter ? U done boilup calc r8, bt how molecular weight will b related to boilup.. Pl gve me proper justification.. Thank you

      ReplyDelete
      Replies
      1. Dear Jai,

        For a gas or a liquid the molecular weight will remain same and the chemical formula will also remain the same, but density varies, that's how i've taken the the molecular weight for boilup.

        Any queries feel free to comment.

        Regards,
        AJAY K

        Delete
      2. Mathematical justification please

        Delete
    6. Boil up ( W ) = U x A x LMTD / ƛ,
      Ajay please simplify this formula ,if this is M*lemda=U*A*Lmtd then
      how Mass (M) Consider as a boil up

      regards
      raj

      ReplyDelete
      Replies
      1. Dear Raj,

        M is nothing but the amount of mass that is distilled out, that's how i meant it as boil up, and what you have mentioned is correct, i've just changed the terminology, don't mind it.

        Regards,
        AJAY K

        Delete
    7. Hello ajay,

      I don"t know the process, but i can say clearly that the entire calculation is wrong. Once check the unit consisttancy and also try to find the mistake by calculating it with using units for each and every value you have taken.

      ReplyDelete
      Replies
      1. Dear Sai,

        Glad to receive a comment like this, pl spot out the section where i went wrong, so that i will change it, and as these post's were of my own knowledge there may be chance for mistakes, so pl don't mind.

        Regards,
        AJAY K.

        Delete
      2. 1. while you are calculating boilup value "U" value you have taken as 200 w/m.k and at the same time latent heat as 264 kcal/kg. Here you have to convert watts to KCal.

        2. And once check unit consistancy for density caluculation.

        3. And finally for height calculation something went wrong.

        Delete
      3. Dear Sai,

        Answering to your queries,

        1. in this whole blog, when ever i consider something as U value, the units that i consider shall be KCal/hr.Sq.m.K, and the units(w/m.K) you have mentioned belongs to thermal conductivity not overall heat transfer coefficient.

        2. coming to density calculations, i'm pretty sure, the units were just perfect, once follow this link for reference, http://www.science.uwaterloo.ca/~cchieh/cact/c120/idealgas.html

        3. In the height calculation, i've extended calculating the height in m, may be i should have ended it in the main formula itself, now i've edited, just check it now.

        Regards,
        AJAY K

        Delete
      4. Ohh sorry, Thank you for clarrifying me.

        Delete
      5. No issue Sai, no need of sorry, keep on visiting

        Regards,
        AJAY K

        Delete
    8. Replies
      1. Thanks for landing on this page and reading this post.

        Delete
    9. Hello there! Do you know if they make any plugins to
      protect against hackers? I'm kinda paranoid about
      losing everything I've worked hard on. Any tips?

      ReplyDelete
      Replies
      1. Thanks for reaching me, but this is not the perfect page for your query, reach me at

        www.computerinnovations.info

        Regards,
        AJAY K

        Delete
    10. Spot on with this write-up, I honestly believe this
      web site needs much more attention. I'll probably be returning to see
      more, thanks for the info!

      ReplyDelete
      Replies
      1. Dear,

        By the next time you visit, kindly add comments with your name, if any hurdles were there while commenting with you real name, lemme know those.

        Regards,
        AJAY K

        Delete
    11. Are you saying that if the boil up is increased then height of vapor column will come down ? At least the formula says so. Do the calcs by considering 75% reactor filling and boil up there of.

      ReplyDelete
      Replies
      1. Dear Joshi,

        As the boil-up decreased then the line size should be reduced in order to enhance the pressure inside the line and for effective transfer of the boil up towards the condenser.

        And what are you have mentioned is a inverse relation and that cant be done practically.

        Regards,
        AJAY K

        Delete
    12. I’m not that much of a internet reader to be honest but your sites really nice, keep it up!
      I'll go ahead and bookmark your website to come back
      in the future. Many thanks

      ReplyDelete
    13. Dear Ajay Kumar , u have written that PV= nRT
      P*V= (Weight/molecular weight)*R*T
      (Weight/volume) = (pressure* molecular weight)/(R*T)
      BUT ( Weight/volume)=density
      i dont understand this



      plz let me know what temp u have taken in while calculating LMTD for methanol?
      u have taken value is 28

      ReplyDelete
    14. Very good but can you find vacuum pump requirement for 3kl SSR using methanol as solvent.

      ReplyDelete
      Replies
      1. Dear ,

        Usually vacuum pump shall be selected based on the system capacity and leakage rate irrespective of solvent.
        follow the link : http://pharmacalc.blogspot.com/2016/03/how-to-select-required-pump-capacity.html

        Regards,
        AJAY K

        Delete
    15. Thanks
      But I need brief calculation of heat load calculation Q=mcpdt+m*lamda
      Here can we take m constant

      ReplyDelete
      Replies
      1. Dear,

        Pl read this full post,
        http://pharmacalc.blogspot.com/2016/03/theoretical-way-to-determine-time.html

        M you cannot take constant everytime, because hour to hour during distillation it will vary.

        Next time, kindly comment with your good name plz.

        Regards,
        AJAY K

        Delete
    16. What about the R value? u have taken it as 62

      ReplyDelete
    17. R value.. Can you tell me how you got the Universal gas constant value?

      ReplyDelete
      Replies
      1. Dear Abdul Haleem,

        Pl refer the below link,
        http://www.cpp.edu/~lllee/gasconstant.pdf

        Regards,
        AJAY K

        Delete
    18. helloo ajay

      i am installing 5 kl reactor & 20m2 condesor (temp of cooling water is 25 25 deg avg. )to cool down vapor of VAM at time of vam & catalyst reaction.
      is this installation ok to cool down VAM vapor ?

      ReplyDelete
      Replies
      1. Dear ,

        What does this VAM means exactly ?
        Next time kindly comment with your name,

        Thanks,
        AJAY K

        Delete
    19. Dear sir,
      Doesn't the height of vapor column change with size of vapor column? Please explain me.

      ReplyDelete
      Replies
      1. Dear ,

        Yeah, it may change inversely, because as the dia increases the built in pressure will decrease.

        Next time kindly comment with your name,

        Regards,
        AJAY K

        Delete
    20. VENKATA NARAYANA5 July 2018 at 20:26

      Dear sir,
      How to calculate the size of vapor column for a batch reactor?

      ReplyDelete
      Replies
      1. Dear ,

        There is no mystery behind the size calculation, its so simple,
        What ever the boilup that is generated during distillation should pass through the column, that's it,

        Boilup rate ( V ) = A x v,

        where, A is cross sectional area, v is velocity of vapour,
        usually the velocity during,
        Normal distillation shall be considered as 1 to 3 m/sec, if its a
        Vacuum distillation, the velocity should be considered as 65 to 70 m/sec.

        if the boil up rate is known, you can calculate the dia from the above mentioned equation, still any queries pl feel free to contact / comment,

        Regards,
        AJAY K

        Delete
    21. THOTA VENKATA NARAYANA6 July 2018 at 21:52

      Dear sir,
      Why steam is given from top of the reactor jacket and others from bottom?

      ReplyDelete
      Replies
      1. Dear Venkat,

        Usually the steam condensate will have more density than the steam, so if steam is given from bottom the condensate will create some pressure on the incoming steam, so the steam will loose its efficiency,

        If liquid utilities were given from top then there wont be any pressure buildup in the jacket as the incoming utility will get discharged from the jacket through gravity and also will result in air locks generation, hence liquid utility shall be given from bottom and the steam shall be given from top.

        Regards,
        AJAY K

        Delete
    22. THOTA VENKATA NARAYANA6 July 2018 at 21:55

      Dear sir,
      Does boil up change for vacuum distillation and normal distillation? If yes, how? Please explain me.

      ReplyDelete
      Replies
      1. Dear Venkat,

        Use the formula P x V = n x R x T,

        In case of normal distillation, P = 760 mmHg, T = boiling point of respective solvent,
        if its vcuum distillation, P = desired / maintained pressure, T = maintained temperature,

        V = volumetric boil-up.

        Regards,
        AJAY K

        Delete
    23. Ajay why used 1000 in density calculation

      ReplyDelete
    24. Dear sir,
      Nice information provide you to all.
      My self Dheeraj, in this case at the time of density calc.
      =(630.95 mmHg*132.15 Kg)/[62.363(L mmHg/mol K)*(333.15 K]
      = 4.013 Kg mol/L
      = 4013 Kg mol/ cub. m
      in that you say unit is Kg/ cub m
      please explain.

      ReplyDelete
    25. am prakash.
      How to calculate the vapor pressure? please provide clear calculations for better understanding.

      log P = 8.08 - 1582.27 / ( 60 + 239.73 ),

      P = 630.95 mmHg.

      ReplyDelete
      Replies
      1. Dear Prakash,

        Follow the below link, http://pharmacalc.blogspot.com/2016/12/how-boiling-point-varies-with-vapor.html

        Regards,
        AJAY K

        Delete
    26. Dear sir,

      through your calculation MeOH vapor density was 4010Kg/m3, is it practically true? please justify for me.

      Thanks and Regards,
      P.B.Pradeep

      ReplyDelete
      Replies
      1. Dear Pradeep,

        Modified the calculation slightly, as the existing calculation which uses antonie equation is creating some sort of controversies.

        Best regards,
        AJAY K

        Delete
    27. Dear sir,
      Am ok with the calculation part. i tried it by my own applying it to our reactors also. My doubt is can we have the height less than we calculated also. Because above the calculated height we may experience self condensation. But i think height lesser may also be used. Its right or wrong? please clarify.
      Thanks and Regrds,
      Rakeshkumar

      ReplyDelete
      Replies
      1. Exactly, you got it,

        This post will be modified slightly to make it clear, as currently it is creating some controversies.

        Best Regards,
        AJAY K

        Delete
    28. Dear Sir

      I am Bala Raju Kinjangi

      i have doubt in Antonic eqn calculation ,how the P value is coming 630.95 mm hg,please reply sir. any conversion is there.

      ReplyDelete
      Replies
      1. Dear Bala,

        Pl refer this post, http://pharmacalc.blogspot.com/2016/12/how-boiling-point-varies-with-vapor.html

        Regards,
        AJAY K

        Delete
    29. Dear Sir,

      I am BalaRaju Kinjangi,

      in Boil up Calculation why r u not taken Q=SENSIBLE HEAT+LATENT HEAT. PLEASE REPLY SIR.

      Regards,
      K.BalaRaju

      ReplyDelete
      Replies
      1. Dear Bala,

        In the boil up calculation, we need to determine the amount of vaporization, so i've considered only latent heat.

        Regards,
        AJAY K

        Delete
    30. Thank you very much sir,Ajay Garu

      Regards,
      K.BalaRaju

      ReplyDelete
    31. Dear Sir,

      I want P & ID software for Pharma industry.atleast Names sir.

      Regards,
      K.BalaRaju

      ReplyDelete
      Replies
      1. Dear Bala,

        share me your mail id, through contact me page, i'll share you the equipment symbols.

        Best Regards,
        AJAY K

        Delete
    32. Dear sir

      Thank you sir for your information. my Mail id is : kinjangi.balaraju@gmail.com

      Regards,
      K.BalaRaju

      ReplyDelete
    33. why you have used liquid methanol density in height calculation. i think it should be vapor density

      ReplyDelete
      Replies
      1. Dear ,

        Great point you made here, thanks, actually it need to be considered, correcting the post now.
        Keep on visiting, next time kindly comment with your good name.

        Best Regards,
        AJAY K

        Delete
    34. Please post the operating procedure for vacuum tray drier

      ReplyDelete

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