Study Finds Compact Carbon-Capture Modules Feasible on Offshore Production Facilities

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper OTC 34825, “Implementation of Compact Carbon-Capture Modules on Offshore Hydrocarbon Production Facilities,” by Jaime H. Tan and Rizal A. Hassan, Technip Energies, and Umberto Cornelis, KANFA, et al. The paper has not been peer reviewed. Copyright 2024 Offshore Technology Conference. _ Carbon capture and storage has been implemented onshore successfully by different industries, including utilities and waste treatment, to capture CO2 from flue gases after the combustion of fossil fuels. Duplicating this success for offshore hydrocarbon processing facilities can be challenging because of deck-space constraints and marine environmental conditions. The complete paper describes the development of a compact carbon-capture module design for post-combustion carbon capture and its potential implementation on typical offshore hydrocarbon production facilities. Solvent Absorption Technology for Post-Combustion Carbon Capture The process technology at the core of the compact carbon-capture module is based on a solvent-absorption technique and a proprietary amine-based solvent. First, feed gas is quenched and saturated in a circulated water prescrubber. The gas contacts the lean amine solution in a countercurrent mass-transfer packed absorption column, and CO2 is absorbed while the treated gas exits to the atmosphere. Midway through the column, partially loaded amine is removed from the tower, cooled, and reintroduced over a layer of mass-transfer packing. CO2-rich amine from the absorption column is pumped through a lean-rich amine heat exchanger and then to the regeneration column. The rising, low-pressure saturated steam in the column regenerates the lean amine solution. CO2 is recovered as a pure, water-saturated product. Lean amine is pumped from the stripper reboiler to the absorption column for reuse in capturing CO2. Finally, the CO2 is directed to byproduct-management systems. The pure CO2 streams produced from the system may be sequestrated or used for applications such as enhanced oil recovery. Design of Offshore Carbon-Capture Modules For offshore applications, the carbon-capture modules must be more compact and lighter compared with carbon-capture systems developed for onshore applications. The absorber column is the critical component of the carbon-capture module because of its weight, footprint, and height. To reduce the overall height of the absorber for offshore application, an innovative configuration has been adopted: The bottom section of the absorber is placed on top of the prescrubber/direct contact cooler (DCC), and the top section of the absorber and the wash-water section comprise the second column. With this arrangement, the maximum height of the columns is limited to approximately 25 m. Because the lower absorber section is placed on top of the prescrubber/DCC, the in-between chimney tray is designed to be totally leakage-free to avoid losses of amines into the DCC water loop. A patent-pending compact absorber column design has been developed. The column wall construction will be a part of the overall module support structure, with cantilevered platforms for supporting carbon-capture equipment. The equipment for compression, injection, and treatment of CO2 is placed on a separate submodule. This module design benefits from footprint and weight savings of potentially more than 20% compared with typical cylindrical absorber column designs.