The effect of additive chemicals on the viscosity of coal-petroleum coke-water slurry fuel for a gasification process

Abstract

As a preliminary study for the gasification of an anthracite and petroleum coke mixture, viscosity was measured at various temperatures (20-50 o C), slurry concentrations (60-70 wt%) and additive amounts (0-0.8 wt%) by using an LV-II type viscometer. In addition, four types of different additives, sodium naphthalene sulfonate, poly(methyl methacrylate), polypropylene and a polypropylene glycol based additive, were applied to Korean anthracite, petroleum coke and mixtures of these materials, and the viscosity data were compared. Viscosity dependency values for coal, anthracite, bituminous and sub-bituminous coal, were compared, and it was found that a high content of moisture and particularly ash increases CWS viscosity. The four types of additives tested in this research can effectively diminish the viscosity of coal and especially petroleum coke-water slurry by more than 70% to 95%, respectively. Moreover, the sodium naphthalene sulfonate-based additive reduced the viscosity of coal and petroleum coke-water slurry best, especially at concentrations in excess of 65 wt%. Based on these results, highly loaded slurry created by mixing anthracite and petroleum coke with additives was achieved.

Enhanced Dispersion and Stability of Petroleum Coke Water Slurries via Triblock Copolymer and Xanthan Gum: Rheological and Adsorption Studies

“…Increasing the F127 concentration beyond this point seemed to have little to no effect on the slurry’s viscosity after its negligible yield stress. Other dispersants (PVA, PEO, and PCA) were measured to have approximately the same minimum concentration to take effect, and minimum dispersant concentrations have been observed previously in other slurry systems. ,, The minimum dispersant concentration is thought to be an effect of adsorbing enough polymer onto the surface of the petcoke to make a complete and sufficiently dense and uniform monolayer.…”

“…This density is close to the 60 vol % theoretical maximum volume fraction for randomly packed monodisperse spheres. Work by Yoon et al with petcoke–coal mixture slurries reported that the ionic and anionic dispersants tested were roughly equally effective for petcoke . This work supports this claim except for the enhanced performance by F127.…”

“…Work by Yoon et al with petcoke−coal mixture slurries reported that the ionic and anionic dispersants tested were roughly equally effective for petcoke. 22 This work supports this claim except for the enhanced performance by F127. Compared to other dispersants, F127 exhibits superior performance in increasing the maximum loading to the point where the original randomly packed void space did not need to be completely filled to have fluid-like behavior.…”

“…Other dispersants (PVA, PEO, and PCA) were measured to have approximately the same minimum concentration to take effect, and minimum dispersant concentrations have been observed previously in other slurry systems. 22,30,35 The minimum dispersant concentration is thought to be an effect of adsorbing enough polymer onto the surface of the petcoke to make a complete and sufficiently dense and uniform monolayer. Atomic force microscopy (AFM) images (Figure 4A−D) show dispersed aggregates below the minimum concentration at 0.1% F127 (Figure 4A) and a smooth saturated monolayer above it at 1% F127 (Figure 4B).…”

“…Polymeric dispersants have been used extensively at low concentrations to reduce the viscosity and yield stress of highly loaded slurries such as coal, ceramics, mining ores, or foods. − Polymeric dispersants are also useful in tuning the rheology for efficient wet grinding of a fuel feedstock. , Previous work on polymeric dispersants has been done on petcoke–oil slurries and coal–petcoke slurries, ,− but only limited studies have done on petcoke–water slurries. These studies predominately use anionic dispersants effective for coal dispersion rather than more general use ionic and anionic dispersants. , …”