Process design of a hydrogen production plant from natural gas with CO2 capture based on a novel Ca/Cu chemical loop

Abstract

A detailed and comprehensive design of a H2 production plant based on a novel Ca/Cu chemical looping process is presented in this work. This H2 production process is based on the sorption-enhanced reforming concept using natural gas together with a CaO/CaCO3 chemical loop. A second Cu/CuO loop is incorporated to supply energy for the calcination of the CaCO3 via the reduction of CuO with a fuel gas. A comprehensive energy integration description of the different gas streams available in the plant is provided to allow a thermodynamic assessment of the process and to highlight its advantages and drawbacks. Hydrogen equivalent efficiencies of up to 77% are feasible with this novel Ca/Cu looping process, using an active reforming catalyst based on Pt, high oxidation temperatures and moderate gas velocities in the fixed bed system, which are around 6% points above the efficiency of a reference H2 production plant based on conventional steam reforming including CO2 capture with MDEA. Non-converted carbon compounds in the reforming stage are removed as CO2 in the calcination stage of the Ca/Cu looping process, which will be compressed and sent for storage. Carbon capture efficiencies of around 94% can be obtained with this Ca/Cu looping process, which are significantly higher than those obtained in the reference plant that uses MDEA absorption (around 85%). Additional advantages, such as its compact design and the use of cheaper materials compared to other commercial processes for H2 production with CO2 capture, confirm the potential of the Ca/Cu looping process as a pre-combustion CO2 capture technology for H2 production.