Techno-economic study of CO 2 capture from natural gas based hydrogen plants

Abstract

Canadian oil sands are considered to be the second largest oil reserves in the world. However, the upgrading of bitumen from oil sands to synthetic crude oil (SCO) requires nearly ten times more hydrogen (H 2) than conventional crude oils. The current H 2 demand for oil sands operations is met mostly by steam reforming of natural gas (SMR). The future expansion of oil sands operations is likely to quadruple the demand of H 2 for oil sand operations in the next decade. This paper presents modified process schemes that capture CO 2 at minimum energy penalty in modern SMR plants. The approach is to simulate a base case H 2 plant without CO 2 capture and then look for the best operating conditions that minimize the energy penalty associated with CO 2 capture while maximizing H 2 production. The two CO 2 capture schemes evaluated in this study include a membrane separation process and the monoethanolamine (MEA) absorption process. A low energy penalty is observed when there is lower CO 2 production and higher steam production. The process simulation results show that the H 2 plant with CO 2 capture has to be operated at lower steam to carbon ratio (S/C), higher inlet temperature of the SMR and lower inlet temperatures for the water gas-shift (WGS) converters to attain lowest energy penalty. Also it is observed that both CO 2 capture processes, the membrane process and the MEA absorption process, are comparable in terms of energy penalty and CO 2 avoided when both are operated at conditions where lowest energy penalty exists.