ABSTRACT

Heat integration is crucial in post-combustion carbon capture (PCC) for optimising energy efficiency and reducing the cost of capture. There are different methods by which this can be effectively accomplished depending on the specific application. Combined heat and power, process integration with existing units to utilise the excess heat, and waste heat recovery from flue gas are a few of the options employed to achieve this. Another effective strategy involves integrating the energy requirement for CO₂ compression with the heat requirement for amine regeneration. This is achieved by producing high-pressure steam to drive CO₂ compression via a steam turbine. The letdown steam from the turbine is then utilised for amine regeneration, maximising energy efficiency and reducing operational costs. This paper evaluates the impact of heat integration strategies on the levelised cost of PCC, considering both the capital and operating costs. Cost analysis integrates case study data from existing plants and estimates capital cost expenditures for full-scale PCC plants. The impact of factors like carbon emissions, taxes, credits, and sales are also considered. The discussion explores how key considerations and motivating factors influence process-design decisions at the flow sheet level regarding heat integration strategy selection. Additionally, the paper discusses how these strategies can address key challenges associated with carbon capture, such as adding a revenue stream by replacing aging assets or exporting power. Additional heat integration optimisation strategies for typical flue gas sources and existing operating units for specific applications will be included.