Highly Reactive Coke

Figure 6.5.19 Conversion of coke with COj length needed for 5% conversion with a ve high reactive coke (factor of 10 higher) and a low reactive coke (factor 10 lower).

Ke)ovoids Blast furnace. Highly reactive coke, Gasification reaction. Microscopic... 

Fig 4 is the comparison between practical and weighted average weight loss ratio of mixed coke. It could be concluded that the two kinds of weight loss ratio are nearly the same, which means with proportion 50% for each, the increase of weight loss for high reactivity coke is equal with decrease of low reactivity coke. 

The reaction degree of surface and interior of lowly reactive coke is relatively uniform with the reaction time increased. And the reaction degree of surface of highly reactive coke is obviously higher than that of interior. 

Seiji NOMURA et al., Post-reaction Strength of Catalyst-added Highly Reactive Coke, ISIJ int, 47(2007), 831-839. 

Production. Silicon is typically produced in a three-electrode, a-c submerged electric arc furnace by the carbothermic reduction of silicon dioxide (quartz) with carbonaceous reducing agents. The reductants consist of a mixture of coal (qv), charcoal, petroleum coke, and wood chips. Petroleum coke, if used, accounts for less than 10% of the total carbon requirements. Low ash bituminous coal, having a fixed carbon content of 55—70% and ash content of <4%, provides a majority of the required carbon. Typical carbon contribution is 65%. Charcoal, as a reductant, is highly reactive and varies in fixed carbon from 70—92%. Wood chips are added to the reductant mix to increase the raw material mix porosity, which improves the SiO (g) to solid carbon reaction. Silica is added to the furnace in the form of quartz, quartzite, or gravel. The key quartz requirements are friability and thermal stability. Depending on the desired silicon quality, the total oxide impurities in quartz may vary from 0.5—1%. 

In this model, there are four common features that apply to resid conversion and these features are 1) an induction period prior to coke formation 2) a maximum concentration of asphaltenes in the reacting liquid 3) a decrease in the asphaltene concentration that parallels the decrease in heptane-soluble material and 4) the high reactivity of the unconverted asphaltenes. Thus, the model can be represented as ... 

While the first process represents a positive event because acetoxyaceto-phenones are convertible into HAPs and can give further intermolecular phenol acylation affording both ortho- and para-HAP, the second process produces ketene, which, being highly reactive, represents the most important source of coke responsible for heterogeneous catalyst deactivation. 

One benefit of near- and supercritical water applies in all these processes for the conversion of biomass. The good solubility of organic compounds, which could be the precursor of tar, and the high reactivity of biomass in near- and supercritical water, decrease the formation of char and coke, and increase the yields of the desired products. 

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