Symmetrical Component Analysis Circulating Current & KVL
Yes, you can use superposition on this linear circuit.  KVL will hold.  From your terminology I'm guessing you are talking about symmetrical components.  For this delta connected load their will be positive and negative sequence current flowing from the sources.  No zero sequence will flow because there is no path for it.  A delta connected load does not connect to the zero sequence neutral bus (in symmet analysis), whereas it does connect to the positive seq neutral bus and negative seq neutral bus.

The terminology circulating current makes no sense to me here.  There is not some mysterious current circulating.  There can't be unless you add a source inside the delta.  Circulating current has meaning if you are talking about the delta winding of a transformer that also has a grounded wye winding.  In that case current can circulate in the delta due to transformer effect while zero sequence flows in the wye winding.