The switch from naptha to ethane as the preferred feedstock for petrochemical plants has resulted in less U.S. propylene production - since cracking ethane yields mostly ethene and little propylene. At the same time, the huge increase in NGL production has lead to a surplus of propane. Hence, EPD plans to build a PDH plant - so named because it removes two hydrogen atoms from propane (C3H8) converting it to propylene (C3H6).
The plant will process 35,000b/d of propane (current US production is about 350,000b/d) and produce 1.65B lbs of polymer grade propylene per annum. The plant will be pipeline connected to 18 chemical plants which produce polypropylene. EPD's own fractionation plants will produce the needed propane.
Hint/guesses on names: propylene is the chemical industry name for propene. Ethene is ethane with two less hydrogen atoms. Propene or propylene is propane with two less hydrogen atoms. An ethane cracker can use ethane or propane (or possibly a mix) as the feedstock. So they needed a new name for a propane cracker; hence "PDH".
Meanwhile, Penn. is arranging tax incentives for Shell's ethane cracker in Beaver county on the Ohio river.