(366g) Insights in the Decarbonization of Oil Refining By Integrating High Temperature Electrolysis

Oil refining is not only one of the largest hydrogen consumers in the world, but also has a large potential waste heat resource, which makes this industry highly compatible with the high-temperature electrolysis technologies, such as SOEC (Solid Oxide Electrolysers). High-temperature electrolysis of steam is one of the most energy efficient techniques for producing hydrogen. If waste heat is effectively utilized to vaporize water, the electricity demand required to convert vapor into hydrogen will be significantly lower compared to that of low-temperature water electrolysis technologies. Furthermore, replacement of grey hydrogen production units with electrolysis is proven to be an effective decarbonization step for the refining industry since conventional hydrogen generation units have a high carbon footprint. The innovation brought by this project is coupling the SOEC technology with refining industry, to supply its hydrogen demand, while utilizing the available waste heat to achieve large reductions in electricity consumption.

Process modeling software is a powerful tool for predicting the performance of different chemical processing plants, including various refining blocks, as well as gray and green hydrogen production units. The modeling of the refining processes allows the accurate quantification of the available waste heat, while the modeling of hydrogen generation units will enable the comparison of the electricity requirements and carbon footprints of different technologies, such as high-temperature electrolysis, low temperature electrolysis, and SMR (steam methane reforming). The models and simulations are created using a proprietary computational thermodynamic process modeling software platform, called "Symmetry". In addition to the results generated by the software, data from the industry and literature are also referenced, whenever applicable.

The full integration of high temperature electrolysis will include two additional interface units, the first one being HRU (heat recovery unit), and the second one being the HPU (hydrogen processing unit). The purpose of the HRU is to convert the demineralized water at ambient conditions to low-pressure superheated steam at the required battery limit conditions of the electrolyzer, by valorizing the available waste process heat or available excess utility (e.g. LLP steam). The purpose of the HPU is to supply the hydrogen at required specifications (e.g. pressure and purity). By evaluating the overall heat and material balance for the given integration scheme, using the simulation software, the utility demand of HRU, and the electricity demand of the SOEC and HPU are determined. Based on the simulation results, confirmed by the industrial references, the full integration scheme of the high-temperature electrolysis results in more than a 25% saving in electricity consumption, compared to its low-temperature counterparts. Also, the full integration of any electrolytic hydrogen production unit results in a 15-20% reduction in carbon emissions from the refinery.

In addition to the full integration scenario, several partial integration schemes are also considered, which propose the coproduction of hydrogen using two parallel processes, one of them being the SOEC/high temperature electrolysis and its interface units, while the other one being either low-temperature electrolysis or SMR. The partial integration schemes are proposed to the scenarios when the available waste heat cannot supply the entire utility demand of the HRU of full integration scheme. Large reductions in electricity consumption are still achievable in the partial integration scenarios, if the corresponding fraction of hydrogen coming from the high-temperature electrolysis is above 20%.

Finally, the carbon abatement cost for the different options is evaluated, with both proposed partial/full integration scenarios the solutions being economically viable depending on the electricity prices and carbon taxes.