Former state Comptroller Bob Milligan has applied for the now-empty seat on the Public Service Commission vacated when Jimmy Patronis stepped down to become the state’s new CFO. Milligan’s name is among 18 applicants so far for the seat, which will be vetted by the Public Service Commission Nominating Council and appointed by Gov. Rick Scott. The deadline to apply is Friday; a working list was released Thursday. The five-member commission regulates the state’s investor-owned utilities.