72h visa - doubt

Ni hao :)

I hold a Spanish passport and a tourist L (just 1 entry). I'm already in Shanghai, but I'm planning to go to Seoul (Korea) for couple of days just before i go back to Spain. So i will come back to Shanghai to catch my flight back to Spain, but then L won't have more valid entries.

It will be then: spain - china - s korea - china (less than 24h) - spain

Is possible to do my last entry to china with the 72h free transit?

Xie xie! Thank you so much for your help :)