The Sunday Times, which published its 30th Rich List at the weekend, listed Jim Ratcliffe, who owns the Grangemouth site, as being worth an estimated £21.05 billion, making him the wealthiest person in the UK.
He was previously only the 18th richest in 2017 - but his net worth has increased by over £15b in just 12 months.
The 65-year-old was born in Lancashire and spent his early years growing up in a council house.
He graduated with a degree in chemical engineering in 1974 and his first job was with petrochemical firm Esso.
He founded Ineos in 1998, and it was in 2006 that he bought BP’s refining and petrochemical business Innovene, which included the Grangemouth plant.