Targeting excess heat recovery in an oil refinery plant implementing large-scale carbon capture and power-to-hydrogen

Paper in proceeding, 2022

This paper discusses how far-reaching measures to reduce on-site CO2 emissions can affect the potential for heat recovery and co-generation of power at an oil refinery. Specifically, we assessed the impact on excess heat availability of implementation of 90 % post-combustion Carbon Capture (CC) from the main CO2 emission sources at a large oil refinery. In additional scenarios, we also investigated implementation of CC in combination with electrification of the Hydrogen Production Unit (HPU) by replacing the existing steam methane reforming (SMR) unit by either a Proton Exchange Membrane (PEM) electrolyser plant or a solid oxide steam electrolyser (SOSE) plant. A total site approach based on constrained heat integration analysis was used to solve the energy targeting problem assuming heat integration between the process plant units via the steam utility network. The main impact of the carbon capture integration is that the target for excess heat available at the temperature of low-pressure steam is significantly reduced, as expected. The reduction is estimated to 62-98 % depending on which measures are implemented in the HPU. However, availability of heat below 135 °C but above 60 °C, which would be suitable for district heating, is increased by 27-49 %. The steam flows available for co-generation are not affected by carbon capture integration, but they are affected by the replacement of the SMR plant by a new electrolysis plant in the HPU. The overall effect depends on whether a low-temperature (PEM) or high-temperature (SOSE) process is assumed, with co-generation target increased by 4 % in the PEM electrolysis case and reduced by 12 % in the SOSE case. PEM electrolysis is also characterized by higher excess heat availability. However, the small advantage in co-generation potential and excess heat availability of the PEM electrolyser comes at the expense of significantly higher electricity consumption.