Q & A > Question Details
I am engineer in a CDU. The lube vacuum column used stripping steam of 25 psig to 750F, the superheater will go to maintenance. Is it possible during the maintenance to use stripping steam of 50 psig to 750°C in this tower? This tower produce distillates for lube naphthenic and paraffinic.
02/02/2010 A: Ralph Ragsdale, Ragsdale Refining Courses, ralph.ragsdale@att.net
Yes, it will be O.K. because the steam will superheat as it "sees" the lower pressure.
01/02/2010 A: Celso Pajaro, Sulzer Chemtech, celso.pajaro@sulzer.com
Yes it is possible to use 50 psig steam at 750 C (I guessing you meant F), you have to made sure the steam is dry, and there will not be water coming with the steam into the column, if liquid gets into the column it will expand more than 100,000 times (specific volume of water is 0.0173 ft3/lb, and steam at 70 mm of Hg is 2272.4 ft3/lb) which will create a pressure surge that will dislodge the bottom trays and upper internals (as a function of the amount of liquid water getting into the column).
If the 750 degrees are Celsius, then you have to review the mechanical strength of pipes and flanges which will have to support a little more pressure but with a lot higher temperate which significantly reduce the maximum stress allow by the pipe and flange material.
31/01/2010 A: keith bowers, B and B Consulting, kebowers47@gmail.com
You should install a de-superheating station so the resulting steam is at the dew point where it is injected into the tower. Otherwise the steam acts as an inert with much lower tower efficiency until it cools to dew-point.