Sunoco coke ovens operate on a regenrative principle that separates coal into solid carbon and transforms volatile matter into gases, that are then thermally destroyed. The ovens handle large batch coal charges (i.e., loads of coal) and long coking cycles (typically 48 hours).

The process:

• A horizontal bed of coal (in granulated form) approximately 3 feet deep, 12 feet wide and 42 feet long is loaded into the side of a hot oven (1,500° F at its coolest) using a leveling conveyor.
• The coal immediately absorbs heat from the surrounding refractory brick. Volatile matter in the coal is driven from the bed and burned, transferring heat from combustion back to the refractory brick.
• Partial combustion of volatile gases occurs in the oven top above the bed of coal. Gases are then drawn into sole flues beneath the oven floor where more air is introduced to complete combustion and provide underfiring to the process. This allows the coal to form into chunks of coke about the size of a football or smaller.
• The gases then pass into an afterburner tunnel where any remaining uncombusted gases are oxidized.
• The afterburner tunnel system routes the hot gases to waste heat generators.
• Resulting steam can be used for process steam applications in various types of plants or for electrical power generation.
• The coke is pushed out and moved first to a quenching facility where it is cooled and then to an area where it is crushed and prepared for transport.
• Coke is shipped to customers by conveyor belt, by rail and by barge. All coke leaving the Haverhill site will be shipped by rail car.

At the Haverhill coke plant, 47 tons of coke are loaded (charged) into each oven every 48 hours. Heat is neither gained nor lost by the refractory (bricks that line the oven walls) over a normal coking cycle. This feature allows the SunCoke oven to be a self-sustaining operation without any requirement for auxiliary fuel.