Influence of the permeability of the coal plastic layer on coking pressure

Associations of physical, chemical with thermal changes during coking as coal heats – Experiments on coal maceral concentrates

“…The evolved tar was detected prior to the decrease of bed permeability, which implied that the initial softening is not only a physical phenomenon but also relates to chemical reactions, this is in agreement with the theories for coal thermoplasticity [1,4,37]. Plastic bed permeability in coking has been related to coke oven pressure development [32,33]. In previous work, a ''dangerous'' high pressure coal could be identified by its resolidification point occurring during low permeability [32], while the addition of other less fluid material had a pressure modifying effect on permeability [33].…”

“…Plastic bed permeability in coking has been related to coke oven pressure development [32,33]. In previous work, a ''dangerous'' high pressure coal could be identified by its resolidification point occurring during low permeability [32], while the addition of other less fluid material had a pressure modifying effect on permeability [33]. In this work, it was found that the greater amount of inertinite acted to delay the minimum permeability point but did not affect its extent.…”

“…With the increase of fluidity, the permeability across the heating coal pellet decreases; it becomes difficult for gases and tars to escape from the plastic coal. The change of bed permeability with temperature can be described based on permeability coefficient k (m 2 ) of gas flowing through coal pellets, which was estimated according to Darcy's law [32,33] .…”

Prediction of coking dynamics for wet coal charge

“…And, on the opposite side of the plastic layer where the intra-particle voids in coal charge are partly occupied by condensed heavy tars, the gas flow is limited (Barriocanal et al, 1998). As shown, for instance, by studies of Casal et al (2006) fissure patterns formed in the so-called dangerous coals, i.e., generating higher wall pressures, are far less developed compared to safe coals. However, a quantitative description of the relationship between fissuring structure and pressure peaks is too complex and still remain a challenge.…”

Relationship between coking pressure generated by coal blends and the composition of their primary tars

“…It seems that in the case of dangerous coals volatile matter evolves near the resolidification zone where the movement of gas might be expected to be more difficult [2,10]. For this reason, the pore structure and fissure pattern of the semicoke may play an important role in the generation of coking pressure [11][12][13]. Coals that develop high coking pressure are normally referred to as ''dangerous'' because coking such coals can cause permanent damage to the wall of the oven and difficulties when the coke is pushed out of the oven.…”