Dear All,

I would like to hear your advice on refinery closed drain systems. To my understanding, the closed drain systems are divided into sub-drains that are light HC closed drain (LHD) and heavy HC closed drain (HHD). In the project design basis, the author stated that CDU gasoil and lighter are sent to LHD whereas the heavy residues are routed to HHD.

I would like to know the basis in the above categorization of products to closed drain systems. Also, is there any available literature that I can refer to for reading and understanding.

Regards,
VS