Modelagem computacional do processo de gaseificação de borra de petróleo visando à geração de energia elétrica utilizando o software Aspen Plus™

Abstract

The present work studies the gasification process of oily sludge from the refining and storage petroleum process, through a computer modeling that considers the chemical equilibrium and whose objective is to evaluate the production of producer gas and its potential use for electricity generation. For this purpose, four scenarios were considered for the thermochemical conversion of oily sludge, which differs in the gasification agent used, being air for scenario 1 (C1), oxygen for scenario 2 (C2), air/steam mixture for scenario 3 (C3) and oxygen/steam mixture for (C4). The results showed that the composition of the producer gas had the same behavior for C1, C2, and C3, with the molar fractions of CO and H2 increasing with the increase of equivalence ratio (ER) until reaching a maximum value and then decreased. In the case of C4 for all steam to oily sludge ratio (SOR) values analyzed, H2 decreased, CO remained constant and CH4 was almost zero for the whole range of RE studied. For a range of ER between 0.25 and 0.45, the producer gas yield increased from 0.81 to 1.15 Nm3 /kg oily sludge for C1, from 0.59 to 0.67 Nm3 /kg oily sludge for C2 and for mixtures with steam (C3 and C4) the highest yields were obtained for the SOR of 1.5. Meanwhile, the lower heating value (LHV) decreased when the ER increased from 0.25 to 0.45, from 5.69 to 3.44 MJ/Nm3 for C1, for C2 the change was from 8.64 to 6.81 MJ/Nm3 , in C3 varied from 4.79 to 3.17 MJ/Nm3 and for C4 from 6.97 to 5.98 MJ/Nm3 (SOR=0.5). The producer gases obtained in the four scenarios were fed to three prime movers (internal combustion engine, gas microturbine, and steam cycle) for electric generation. The internal combustion engine was the one that produced the highest electric power, being possible to obtain powers in the range between 335 and 183 kW when the producer gas obtained in the C4 with a SOR of 0.5 was used, while the gas microturbine has higher technical requirements to be operated with producer gas. Based on the properties of the producer gas, it is verified that oily sludge gasification could be a viable alternative for the treatment and energetic use of this residue.