Addition Effect of Model Compounds of Coal Extract on Coke Strength

Abstract

Eight polyaromatic hydrocarbons that are model compounds of coal extract were added to coal blends to clarify the mechanism of the effects of coal extract (HyperCoal) on coke strength. Addition of large aromatic ring compounds (coronene, perylene, naphtho[2,3-a]pyrene) greatly enhanced coke strength, whereas three-ring aromatics (anthracene, phenanthrene) had no significant effect on coke strength. Because large polyaromatic compounds have greater affinity for coal molecules, they co-fused with the coal particles. As a result, formation of large pores during coking was suppressed, leading to increased coke strength.

Relationship between Chemical Structure of Caking Additives Produced from Low Rank Coals and Coke Strength

“…mentioned before, in case of model compounds, improvement of coke strength was observed from more than 4 rings and the effect was better in peri-type structure. 5) Thus, this result of structural analysis also indicates that BIT-380 has enough improvement effect for coke strength.…”

“…Similar result was reported in the previous study. 5) In that report, the coke strength was decreased by adding model compound which is consisted of less than 3 aromatic rings. In this work, R a of Mu-400 and Pa-400 was less than 3, however, these additives improved the coke strength.…”

“…In this work, R a of Mu-400 and Pa-400 was less than 3, however, these additives improved the coke strength. Koyano et al 5) reported that if molecular weight of additive is larger, its boiling point is higher, and much more fraction of poly-aromatic hydrocarbons should contribute to co-fusing. As a result, the additive improves the coal plastic property.…”

“…Also comparing between the poly-aromatics with the same ring size, the coke strength improved more with peri-type compounds than cata-type ones. 5) It is previously reported that the average number of aromatic rings in low-rank coals is around 1-2. 6) If the number of aromatic rings in HPC produced from low-rank coals is nearly equal (1-2 rings), the improvement of coke strength may not be expected, although it should not be easily compared with model compounds since their polarity or molecular weight are different.…”

“…Koyano et al 5) reported that when adding various poly-aromatic hydrocarbons to coals as caking additive, the coke strength increased in the cases of more than 4 aromatic rings and the effect enhanced with increasing the number of aromatic rings. Also comparing between the poly-aromatics with the same ring size, the coke strength improved more with peri-type compounds than cata-type ones.…”