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Means of Temporarily Reducing Heat Transfer Area in Shell-and-Tube Heat Exchangers Disclosure Number: IPCOM000244407D
Publication Date: 2015-Dec-09
Document File: 8 page(s) / 927K

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Typically, the tubes of a Shell-and-Tube Heat Exchanger (STHE) are plugged due to damage (leaks) and immediate replacement is not possible or recommended. This plugging procedure effectively removes the tube from the thermal-hydraulic performance of the unit. The tube side fluid no longer passes through this tube and the overall effective heat transfer surface area of the unit is reduced by the heat transfer surface area of that tube. The plugged tube cannot be unplugged and placed back into service. The following presents various methods to achieve purposeful, temporary tube plugging, such that the plugged tube can be unplugged and placed back into service at some later time.

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     Typically, the tubes of a Shell‐and‐Tube Heat Exchanger (STHE) are plugged due to damage  (leaks) and immediate replacement is not possible or recommended. This plugging procedure effectively  removes the tube from the thermal‐hydraulic performance of the unit. The tube side fluid no longer  passes through this tube and the overall effective heat transfer surface area of the unit is reduced by the  heat transfer surface area of that tube. Part of the plugging procedure involves actively venting the  plugged tube by putting a hole in it to prevent overpressure inside the tube during operation. Plugging is  a permanent method. The plugged tube cannot be unplugged and placed back into service. The effective  heat transfer surface area of the plugged tube is lost forever. What if you desired to purposely and to  temporarily plug tubes to reduce the overall effective heat transfer surface area of the unit by that of  heat transfer surface area of the total number of tubes plugged? The following disclosure presents  means to achieve this end. 

     Shell‐and‐Tube Heat Exchangers (STHE) (Figure 1), comprised of a bundle of tubes placed inside  a shell, represent the heat exchange workhorses of the petroleum, natural gas, and chemicals  production and refining industries. They are as ubiquitous on an industrial plant site as they are  mechanically and thermally reliable for long run times. As with other heat exchange equipment, the  thermal‐hydraulic engineer designs them to process certain streams and exchange energy in the form of  heat between those streams with one stream passing through the inside of the tubes (tube side) and the  other across the outside of the tubes in the shell (shell side). 



Means of Temporarily Reducing Heat Transfer Area 

in Shell‐and‐Tube Heat Exchangers 

Figure 1: One‐(1)‐Shell Pass, Two‐(2) Tube Pass Shell‐and‐Tube Heat Exchanger (Simplified) 


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  Those familiar with the art will recognize that shell‐and‐tube heat exchangers possess many  configurations (e.g., tube passes, shell configurations, front and rear assemblies, etc.) For the purpose of  explanation, the remainder of this paper will refer to a one‐(1)‐pass shell, two‐(2) tube pass shell‐and‐ tube heat exchanger similar to that depicted in Figure 1.  

  Figure 2 presents a view looking at the tubesheet (Figure 1, Item 1). The shell side fluid enters  via the upper nozzle (Figure 1, Item 2), travels the length of the shell, and exits via the lower nozzle  (Figure 1, Item 3). The tube side fluid ent...