Optical Microscopy and SEM Study of Pyrolytic Carbon Deposits from Coke Ovens

The presence of pyrolytic carbon deposits can cause a number of serious problems in the operation of a coke oven. They can inhibit the flow of gas out of the oven; their removal may cause damage to the refractories and the coke pusher equipment, in particular when the deposition is extensive, and can affect the sealing of the oven so leading to undesirable emissions. Some plants burn off the carbon deposits in an empty oven and this evidently causes loss in productivity and brickwork damage which can lead to environmental problems. There are some uncertainties regarding the formation mechanism and the nature of the pyrolytic carbon found in carbon deposits. The main objective of the investigation was to study the nature and characteristics of pyrolytic carbon deposits in industrial coke ovens, with particular emphasis on the nature of the carbon deposited adjacent to the oven walls. Study of the carbon deposits by optical microscopy and SEM showed a variable concentration of carbon entities as well as differences in packing density. The majority of the deposited carbon was found to be laminar in nature, although the major component initially deposited on the brickwork appeared to be spherulitic. Some degree of gasification of the carbon material in some samples was also apparent.