Effect of Ash Composition (Ca, Fe, and Ni) on Petroleum Coke Ash Fusibility

Abstract

Ash fusion behavior is closely associated with ash-related problems including fouling, sintering, and slagging, which results in a negative effect on the utilization of petroleum coke (petcoke). Petcoke ash contains high levels of vanadium (V), nickel (Ni), iron (Fe), and calcium (Ca). The chemical composition of ash plays an intrinsic role in determining ash fusibility. To better understand the modification mechanism of the ash fusion temperatures (AFTs), this study investigates the influences of ash composition (CaO, Fe2O3, and NiO) on the synthetic petcoke ash fusibility from the perspectives of ash composition change and temperature rising. The AFTs of synthetic ash samples were identified by the ash fusibility tester. X-ray diffraction (XRD) and scanning electronic microscopy (SEM) were applied to explore the relationships between the experimental AFTs and the variation of mineral composition and microstructure of high-temperature ash slag. Moreover, the ash melting process was predicted by the SiO2–Al2O3–V2O5–CaO–Fe2O3–NiO system based on the FactSage modeling. The results show that the AFTs of petcoke are closely related to the ash chemical composition. As the CaO and Fe2O3 content increases, AFTs exhibit continuous decline, while first decreasing slightly and then increasing with the increasing NiO content, which is ascribed to the different mineral transformation behaviors of high-temperature ash slag. The dominant crystalline minerals formed in high-temperature ash slag with different CaO, Fe2O3, and NiO content are anorthite (CaAl2Si2O8), nickel orthosilicate (Ni2SiO4), calcium pyrovanadate (Ca2V2O7), and quartz (SiO2). Fe may form Fe-bearing amorphous matter with other minerals. The synergistic effect between high-melting Ni2SiO4 and low-melting Ca2V2O7 may contribute to the variation of AFTs, which was well validated through thermodynamic equilibrium calculations.

A FactsSage Simulation Study on the Interaction of Synthetic Petcoke Slags with Alumina Crucibles

“…Ni 2 SiO 4 was found by Li et al in petcoke ash slag obtained under oxidizing conditions [13,14]. [13,14]. In comparison with Figure 8, the plots in Figure 13 show that drop in Al 2 O 3 (solid), occurs at lower temperatures.…”

“…Ni 2 SiO 4 is present in the thermodynamic calculation results. Ni 2 SiO 4 was found by Li et al in petcoke ash slag obtained under oxidizing conditions [13,14]. [13,14].…”

Utilization of Petroleum Coke Soot as Energy Storage Material

“…The results (Figure 2, Table 3) confirmed that large quantities of organic matter were removed through annealing; however, 11.73% of residues remained even after annealing at 2700 °C. EDS mapping ( Figure 3) was performed to determine the composition of the residue Among the metal components, a large quantity of vanadium was observed in the petroleum coke soot [19][20][21]. Many prior studies have suggested various physical and chemical methods to remove this metal.…”

Effect of Silica and Alumina on Petroleum Coke Ash Fusibility

“…The ash compositional differences between petcoke and coal may cause different mineral transformation behaviors because of the presence of V and Ni in petcoke. We have investigated the effect of petcoke ash composition (V 2 O 5 , NiO, CaO, and Fe 2 O 3 ) on ash fusion behaviors in previous researches. , The acidic ash constituents SiO 2 , Al 2 O 3 , and TiO 2 are generally considered to act as receptors (network formers) and the basic oxides CaO, Fe 2 O 3 , Na 2 O, K 2 O, and MgO as oxygen donators (network modifiers) . The base-acid ratio R defined as (CaO + Fe 2 O 3 + Na 2 O + K 2 O + MgO)/(SiO 2 + Al 2 O 3 + TiO 2 ), which is the same as the effect of (SiO 2 + Al 2 O 3 ) ratio, has been used to rank the propensity of melting, fouling, and slagging. − Moreover, the S/A ratio is also an important factor for the initial evaluations of ash fusibility. , In this work, both S/A and (SiO 2 + Al 2 O 3 ) ratios are considered to characterize the influences of SiO 2 and Al 2 O 3 on petcoke ash fusion behaviors, which is expected to provide a guide for the efficient utilization of petcoke.…”

“…We have investigated the effect of petcoke ash composition (V 2 O 5 , NiO, CaO, and Fe 2 O 3 ) on ash fusion behaviors in previous researches. 24,25 The acidic ash constituents SiO 2 , Al 2 O 3 , and TiO 2 are generally considered to act as receptors (network formers) and the basic oxides CaO, Fe 2 O 3 , Na 2 O, K 2 O, and MgO as oxygen donators (network modifiers). 26 The base-acid ratio R defined as (CaO + Fe 2 O 3 + Na 2 O + K 2 O + MgO)/ (SiO 2 + Al 2 O 3 + TiO 2 ), which is the same as the effect of (SiO 2 + Al 2 O 3 ) ratio, has been used to rank the propensity of melting, fouling, and slagging.…”