Proposition of a Minimum Set of Independent Chemical Reactions To Model Gas-Phase Composition during Gasification of Complex Cokes

Abstract

Petroleum coke, obtained as a product from the delayed coking of vacuum residue, could experiment with gasification, helped by oxygen and steam, to recover hydrogen and/or energy. To model and simulate this process, it is necessary to predict gas-phase composition, considering the reaction of molecules of coke, oxygen, carbon monoxide, carbon dioxide, and water. In previous works, coke has been considered as a mixture of independent elements, such as carbon, hydrogen, oxygen, sulfur, nitrogen, and ashes; however, it is important to consider coke as a whole molecule of known composition to close mass and energy balances. Departing from element analysis from five petroleum cokes, in this work, a set of three independent chemical reactions is demonstrated to be sufficient to model gasification, considering coke molecules as whole entities. The sensitivity of the rate of hydrogen production and CO/CO2 ratio with coke composition is evaluated to describe the operating zone defined by conversion of reactants in the three reactions. Results allow for the prediction of product stream composition and relative reactor volume required for gasification of each kind of coke.