I think sshep's guess looks pretty close to what my interpretation of the sketch would be.
It looks like the recirculation line ties in *upstream* of the pump filter...
Maybe its just me, but from the sketch, there isn't enough information for me to piece together what they are trying to do. If the pump at the bottom of the page runs continuously then, depending on the N2 pressure on the vessel (is it higher than 206 psi?) the intent might be to blowcase the collected drained liquid into the downstream tank where, presumably, the blanket N2 pressure is much lower.
Given the temperatures and the fluid (heat transfer fluid?) involved, part of me, at least, thinks that a corrollary intent might be to make sure that N2 is in the system in preference over air in order to stay below a lower flammability limit.