Abstract
The volatilization characteristics and occurrence forms of V and Ni in petroleum coke (petcoke) were investigated during steam (H2O) and carbon dioxide (CO2) gasification on a fixed bed reactor at 800–1100 °C. The Tessier sequential chemical extraction procedure was employed to determine the different forms of V and Ni. The results showed their volatilities were not dependent on the gasification atmosphere, but rather relied mainly on the reaction temperature. The CO2 atmosphere accelerated the conversion of organic-bound nickel to residual form at low temperature and promoted Fe-Mn oxides formation at high temperature. However, the H2O atmosphere was conducive to form vanadium bound to Fe-Mn oxides and promoted the decomposition of residual forms. In addition, the thermodynamic equilibrium calculations showed the volatilization of Ni mainly released Ni3S2 between 800–1100 °C. The H2O atmosphere was favorable to generate the more stable NixSy compound, thereby suppressing the volatilization of Ni, while the presence of CO2 led to an increase in residual V and decrease of Fe-Mn oxides. The V and Ni mainly caused erosion problems under the CO2 atmosphere while the fouling and slagging obviously increased under the H2O atmosphere with impacts gradually weakened with the increase of temperature.
Highlights
The shortage of energy resources and the improvement of petroleum processing capacity have led to a continuous increase in the production of petcoke [1,2,3]
Wang et al [7] investigated that the formation of ash and slag was closely related to the conversion of vanadium, nickel, and sulfur during the gasification process
The V and Ni contents in petcoke and its gasification char and their extracted solutions were measured by inductively coupled plasma mass spectrometry (ICP-MS)
Summary
The shortage of energy resources and the improvement of petroleum processing capacity have led to a continuous increase in the production of petcoke [1,2,3]. Petcoke has high calorific value, low ash and low price qualities, which endow petcoke with the potential to be a gasification feedstock to produce synthetic gas and recycle sulfur through the Claus process. The high temperature accelerates the fouling, slagging and erosion problems caused by vanadium and nickel in the petcoke. V2 O3 in petcoke ash remained solid at the typical gasification temperature and the solid V2 O3 caused the slag viscosity to increase. Wang et al [7] investigated that the formation of ash and slag was closely related to the conversion of vanadium, nickel, and sulfur during the gasification process. Li et al [18] reported that the vanadium reacted with the mineral component to form a new thermal stable compound when the gasification temperature was above 1300 ◦ C. A detailed assessment on the pernicious effects on gasification equipment by the mineral elements V and Ni was gained
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