What Can Cause A Shell And Tube Heat Exchanger To Block The Flow Of Steam On The Tubes Side?

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  alpha b said,

  - calcium build up internal to the heat exchanger(if it’s old) De ionized water in the boiler system would prevent that after cleaned out really good.
  - busted seal from a valve transfered in through the steam flow, blocking a portion of the tubing of the heat exchanger. try blowing it out from the exit side with high pressure air possibly (be smart and safe about it…it will be icky and full of junk, and don’t exceed 2 x the rating of the heat exchanger for burst reasons (they are rated at 2.5 times max pressure usually))
  - water in the heat exchanger (is it bursted internally allowing a leak to come in from the process side)
  one of those is probably it.

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  baheej59 said,

  *Un till and unless there is a improperly maintained boiler,the quality of steam is good enough.If otherwise boiler will become very in efficient.
  As per your data,steam pressure from boiler is OK.
  So, we have to look for the steam line connecting from boiler to shell and tube type heat exchanger.
  If it is ok , then there is a problem in the shell and tube type heat exchanger.
  Above is required for diagnosing the area of concern.
  Blockage is nothing but fouling of the tubes or inlet or outlet port of channel box is choked.Check for the blank or blind provided in the inlet for any maintenance purpose.
  It is a good practice to have a stream trap in the condensate line for better heat transfer.Steam trap assembly is provided with two nos. of isolation valves and 1 no. of bypass valve.And also there is a suction strainer in the trap itself .
  So, check above all for any problem.Open the by-pass valve of the trap and prime the system.Shell and tube type heat exchanger tubes may be filled with condensate if IN-OPERATIVE for a certain period and need to be removed.
  Since, this is a swimming pool , there must be a control.Check the control assembly.
  There must be a PRV in the steam line going to shell and tube type heat exchanger.
  Check whether it is in a good condition or not or simply open the by-pass valve of the PRV.
  Lastly , check the extreme out let valve , i mean nearest to the swimming pool. People generally use to close the inlet and outlet valve.
  **Seesaw fouling. Here, fouling loading generally increases with time (often assuming a generally linear or falling rate), but, when looked at in more detail, the fouling progress is periodically interrupted and takes the form of sawtooth curve. The periodic sharp decreases in the apparent fouling amount often correspond to the moments of system shutdowns or other transients in operation. The periodic decreases are often interpreted as periodic removal of some of the deposit (perhaps deposit re-suspension due to pressure pulses, spalling due thermal stresses, or exfoliation due to redox transients). However, other reasons are possible, e.g., trapping of air inside the surface deposits during a boiler shutdown, resulting in enhanced steam nucleation (therefore improved boiling heat transfer) during the initial period of subsequent operation.
  Read fouling of HX tubes at:http://en.wikipedia.org/wiki/Foulinghttp://www.wlv.com/products/databook/ch1…

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  ELEcTrIc said,

  Depending on the quality of the steam, it may have deposited minerals in the exchanger tubes and blocked them off.
  Depending on the pressure to drive the steam through the tubes, there might not be sufficient to do the job if the tubes become full of steam condensate.
  How is the steam flow controlled? Do it use a control valve? steam trap? or is it just open to the atmosphere?

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