Energy consumption and CO2 emissions of petroleum coke-to-methanol with/without carbon capture using process modeling and life cycle analysis

Abstract

Petroleum coke is an important by-product of oil refineries. It is characterized by high carbon content and calorific value with increasing sulfur content due to the use of the inferior crude oil. The application of petroleum coke combustion will inevitably produce a large amount of greenhouse gas emissions. Gasification technology can efficiently convert it to syngas and then for methanol production. However, the petroleum coke-to-methanol also faces serious CO2 emissions when adjusting syngas composition. Therefore, this study establishes the model of the petroleum coke-to-methanol with/without carbon capture and compares their energy consumption and CO2 emissions from the production and life cycle aspect. The CO2 emissions of the petroleum coke conversion rates of 75%, 85%, and 95% without carbon capture are 2439 kg/t, 2269 kg/t, 2146 kg/t with exergy efficiencies of 38.35%, 45.31%, and 52.23%. With the help of the carbon capture devices, their CO2 emissions are reduced to 316 kg/t, 297 kg/t, and 285 kg/t with decreasing exergy efficiencies by about 1%. From the aspect of life cycle, the greenhouse gas emissions of the petroleum coke-to-methanol are 3602, 3299, and 3077 kg CO2 eq/t, which are reduced by about 54.58–55.79% with involving carbon capture.