Hard to be definitive without knowing their development concept,...

Hard to be definitive without knowing their development concept, but my guess would be 12-18 months for a project like this. There's nothing particularly challenging about it in terms of engineering complexity, its all been done many times before, but these things take time and shortcuts taken at FEED often lead to project cost and/or schedule blow-outs. Remember that this is just for the FEED, detailed engineering then follows at the EPC stage, assuming that is their contracting strategy. Often the FEED is contracted to an EPC company anyway.