• In a hydrogen production unit designed by Haldor topsoe, we have a latent heat exchanger, that vaporizes natural gas by HPsteam, and a condensate pot. The effluent entering the heat exchanger is HP Steam and the exit of the heat exchanger is steam condensate enters the condensate pot from the middle. Between the top of the pot and the heat exchanger there is a line connecting them together. Steam pressure is 70.5 kg/cm2. The operating pressure of the pot is also 70.5kg/cm2. What is the the purpose of the line connecting the condensate pot to the heat exchanger? By the way, there is a PSV installed at the top of the condensate pot The PSV pressure is set 79.5 Kg/cm2.



  • Rick Kempf, Advanced Ionics, rick.kempf@advanced-ionics.com

    The previous answers are correct. Another example of this arrangement is in home plumbing and the use of a plumbing vent line that extends usually through the roof. This allows liquid to flow out of the house with minimal resistance and no "gurgling" by letting the vapor space in the line to rush out the vent. The result is "free flow" of liquid forward.



  • Imran Malik, www.Qchem.com.qa, immalik@qchem.com.qa

    The line is provided for balancing the pressure to allow free drainage of the condensate. This is a typical arrangement for any such type of scheme where you expect some two phase flow and allow the dissociating vapors exit the vessel and not to obstruct the incoming condensate by vapor locking.

    The PRV pressure set is as per the system mechanical design MAWP, which will definitely be more than steam operating pressure.



  • Marcio Wagner da Silva, Petrobras, marciows@petrobras.com.br

    Based on the description in the question, it seems that the referred is a balancing line between the condensation vessel and the heat exchanger aiming to establish and pressure equilibria and allow adequate condensate flow. The condensate vessel avoids that the live steam flows to the condensate system and the pressure equilibrium allows that condensate to flow to the condensation recovery system with the necessary energy as well as between the heat exchanger to the condensate vessel reducing the energy efficiency issues. Probably the set of 79,5 kgf/cm2 of the pressure safety valve (PSV) is related to the maximum allowable operating pressure of the condensate vessel.