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The effect of swelling pressure during coal carbonization on coke porosity

Lookup NU author(s): Emeritus Professor Mark ThomasORCiD

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Abstract

In cokemaking, the generation of swelling pressure is an important consideration since excessive pressures result in problems with pushing the coke and in extreme cases, damage to coke ovens may occur. In this investigation, the effect of swelling pressure generated during coal carbonization in coke ovens on coke porosity was studied. The swelling pressure was measured using a movable-wall test oven. The gas pressure in the plastic layer and the swelling pressure were monitored during the carbonization of coals in the test coke ovens. The porous structure of the resultant coke was assessed. The coke macropore structure was characterized using an optical microscope coupled with an image analyser and the micropore structure was characterized using a volumetric gas adsorption method. A method to determine the extent to which the macropores were distorted under unit pressure during the thermoplastic stage was also developed. It was shown that the macropores were compressed against the coke oven wall by the gas pressure in the plastic layer, resulting in the distortion of their shape; the extent of distortion varied greatly with the type of coal. The results suggested that the macropore distortion depended not only on the swelling pressure but also on the amount of distortion per unit pressure during the thermoplastic stage. Furthermore, the characteristics of the coke pore structure from a dangerously swelling coal varied considerably over the oven width. As the oven centre, where the gas pressure was extremely high, was approached, the macroporosity and the mean macropore diameter decreased, while the microporosity increased. The changes in the macroporosity and microporosity over the oven width are discussed in relation to the gas pressure in the plastic layer and the swelling pressure developed during carbonization.

Publication metadata

Author(s): Nomura S, Thomas KM

Publication type: Article

Publication status: Published

Journal: Fuel

Year: 1996

Volume: 75

Issue: 2

Pages: 187-194

Print publication date: 01/06/1996

ISSN (print): 0016-2361

ISSN (electronic): 1873-7153

Publisher: Elsevier Ltd

URL: http://dx.doi.org/10.1016/0016-2361(95)00238-3

DOI: 10.1016/0016-2361(95)00238-3

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