At BP’s Toledo Refinery, we commissioned a 27.5 MBPD sour (3 API feed) 2-drum coker. This unit was designed with a switching interlock system which uses ball valves actuated by 480-volt motors as the interlocked devices, in combination with manual valves which form double block capability. This concept forces operator presence at the switch/cutting decks during drum turnaround activities, but is thought to be a good compromise between total double-blocks via MOV’s in interlocks and total manual-valved situations which have led to mistakes/accidents in the past.
The MOV positions are displayed on a Honeywell 3000 graphic, but the board operator has no control of the valves. All of the MOV’s are actuated in the field from a switch panel, and in the case of valves on the drum tops, by switches located at the cutting deck level.
Field operators still have to open/close block valves to steam the drums, pressure test, line up drum cooling water, and drain the drums to the coke pit. This unit was commissioned April 13th, and so far, the only problems associated with this system have revolved around proximity switches and torque switches in the MOV’s. The local switch panel has an interlock matrix bolted onto it for operator reference which shows red/green light displays for various steps in drum turnaround.
The new unit is open-art, has 27′ ID drums, and the biggest single coker furnace in the world (according to the designer). This furnace is a double-fired design.