Optimized Configuration to Reduce H2 Carbon Footprint in a Refinery

Abstract

As hydrogen is increasingly being recognized as a critical energy vector in the energy transition, capturing CO2 from existing H2 production facilities plays a significant role towards decarbonisation. In a refinery, the H2 production process contains the most concentrated CO2 streams, namely the off-gas from the H2 PSA (containing 40-50%v CO2), and the flue gas from SMR burners (containing 20-25%v CO2). Air Liquide, as one of the leaders for H2 production, has industrialized Cryocap™ H2, combining membranes and cryogenic solutions to capture CO2 most efficiently, at the lowest cost, and at a very high purity. On top of capturing and liquefying the CO2 in one step, one of its salient features is the ability to boost the hydrogen production of a plant by ~10% to 20% further decreasing the SMR carbon footprint. This paper illustrates the impact of cost-effective partial capture technology choices (e.g. amine wash versus Cryocap™ H2) and optimization path on the CO2 emissions reduction rate for various scopes of emissions, power grid footprint, and network configuration within a refinery. It was found that the CO2 emissions reduction rate on Scope 1 for an Amine Wash is decreased to 56% (compared to the typical 60% reduction rate) due to additional steam consumption. On the contrary, it is increased to 62% with Cryocap™ H2, and further to 80% thanks to the additional hydrogen production allowing a reduced load on other H2 production on the network. All emission scopes considered, Cryocap™ H2 is significantly more efficient in terms of carbon footprint reduction than the solvent technology regardless of the power grid footprint and the way additional steam is produced (i.e. natural gas versus electric boiler).