Partial briquetting vs direct addition of biomass in coking blends

Abstract

In this work partial briquetting is employed as a means of biomass densification to allow for biomass inclusion in coking coal blends. The effect of increasing the bulk density was evaluated by comparison with direct addition. Two briquettes of different composition were studied. The influence of the briquettes on the Gieseler plasticity of the coals was determined. It was found that the effect of the binder was not enough to compensate for the decrease in plasticity produced by the inert components of the briquettes. Carbonizations were carried out in a movable wall oven of 17 kg capacity and the quality of the cokes produced was tested by evaluating their mechanical strength, coke reactivity to CO 2 and post-reaction strength. In addition, the porosity and ash chemistry of the cokes was determined and an attempt was made to establish a relation between these results and the quality of the cokes. Coke quality results suggest that 10-15 wt% of briquettes containing biomass can be included in coking blends.

Effect of briquette composition and size on the quality of the resulting coke

“…In a previous research paper it was shown that the direct addition of sawdust to an industrial coal blend produced a decrease in the bulk density of the charge of 17 kg/m 3 while the addition of sawdust in the form of briquettes increased it by 11 kg/m 3 [7].…”

“…At the same time, cokemaking is a process where the recycling of wastes is possible, especially high carbon and low ash wastes like sawdust and charcoal [5][6][7][8][9], plastics [10][11][12], and bituminous wastes [13][14][15]. Thus recycling in the cokemaking industry could provide a way to reduce the environmental impact of CO 2 emissions, reduce costs and widen the raw materials spectrum to include non-fossil fuels.…”

“…Partial briquetting of coal charges was introduced by the Japanese industry in the 70s, as this technique enabled the amount of expensive prime coking coal in the blend to be reduced and a cheap non-coking coal to be used instead without any deterioration of the quality of the resultant coke [19]. In a previous paper [7] a comparison of the direct addition of sawdust and addition via briquetting was carried out. However, other factors such as size and composition still need to be evaluated in order to know whether it is possible to apply sawdust briquetting to cokemaking.…”

Kinetics of co-pyrolysis of sawdust, coal and tar

“…The briquettes had an ellipsoidal shape, axes of lengths 46 and 42 mm and a weight of around 23 g (Montiano et al, 2014b). Blends resembling the composition of the briquettes were pyrolyzed up to 1000 °C at a rate of 10 °C/min in order to investigate the degree of interaction between the components of the blends.…”

“…In addition the recycling of wastes is important not only from the point of view of waste treatment and energy recovery but also for upgrading the material. The use of biomass in coking blends could serve to reduce the emission levels due to its carbon neutral content and low ash and sulphur contents (Jung et al, 2014;Montiano et al, 2014aMontiano et al, , 2014b.…”