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[SP500]

I am aware of how to size a PFR , but I am rather confused concerning its actual structure, is a PFR effectively a pipe?

 

What aspects are involved in designing a PFR from a mechanical point of view?

 

Ofcourse I would be considering the materials of construction, the thickness of the vessel and nozzles sizes, but is that it:?

Edited by SP500, 17 January 2017 - 11:20 AM.

[sgkim]

Hi,

 

Plug-flow-reactors (PFR's) can be a vacant tube or packed.   Naphtha or gas oil cracking furnaces are vacant tubes externally heated by fuel combustion.   Reformers charged with catalysts are examples of packed bed reactors.  Conversion is increased throughout the tube along.  If the pressure drop or fluid velocity is too high, then increase the number of the tubes running in parallel.  Tube bundle type reactor either vacant or charged is also a kind of PFR's.   

 

PFR's are basically long, horizontal or vertical tubes which are to be usually installed in the heating(radiation and/or convection) zone of the reactor.   Supports materials shall be heat-resistant, so the high-temperature service casting materials are greatly employed.  Homogeneous heating flux are key issues for the PFR design.  Thermal stresses exerted in the tube shall be relieved and lots of supports shall have sliding shoes. For vertical tubes, spring hangers shall mitigate the vertical displacement of PFR tubes.  Various flexible devices and repeated u-turns can also absorb the extended or contracted length from heating and cooling thermal cycles.

 

The material shall be so selected as to be bearable for continuous service at the design temperatures.  Quite often, alloys, stainless steels, nickel alloys, etc. are used for high temperatures.  Limited service conditions are specified for each material selected.

 

Other issues could be queued...

 

Stefano G. Kim