Process analysis of H2 production from pyrolysis-CO2 gasification-water gas shift for oil sludge based on calcium looping

Abstract

The treatment of oil sludge (OS) from petrochemical industry is a challenge. Traditional OS gasification process has the disadvantages such as low H2 yield and high CO2 emission. In this work, a novel pyrolysis-CO2 gasification-water gas shift process of OS for efficient H2 production based on calcium looping was proposed, which includes four stages: drying, pyrolysis, char gasification with recycled CO2 and water gas shift reaction for H2 production by in-situ CO2 capture using CaO. The pyrolysis-CO2 gasification-water gas shift process of OS was thermodynamically simulated by Aspen Plus. The effects of the mass ratio of steam/OS, temperature, mass ratio of CaO/OS, the proportion of CO2 reused on H2 generation and efficiencies of CO2 capture, energy conversion, and exergy were analyzed. The OS pyrolysis and CO2 gasification of char were also studied by experiment. Compared with direct steam gasification of OS process, H2 yield (0.32 Nm3/kg-OS) and efficiencies of energy conversion (36%) and exergy (32%) increase by 0.28 Nm3/kg-OS, 13.62%, and 17.16%, respectively. The novel process is promising for energy recovery from OS.