Integration of a carbon capture-ready cogeneration plant: From requirements to design, facilities optimization and energy efficiency opportunities

Abstract

Abstract TOTAL Exploration and Production is involved in a number of production and/or processing projects such as Heavy oil, Oil sands and LNG which require substantial amounts of energy (heat and power). Alongside this, sustainable development of energy resources is a prime target for the Total group, which strives constantly to reduce the GHG intensity of its production activities. On new projects and for major plant modifications, this is achieved by optimizing energy efficiency and preventing continuous flaring of produced gas, which is marketed or re-injected instead. On current producing installations, a continuous improvement process to address flaring reduction and energy efficiency is on-going. However in view of the coming development challenges, Total is further considering the development of facilities with a limited GHG footprint, by the means of emissions reduction through carbon capture and sequestration. Designing capture-ready installations is the first step on this path. It is a challenging task owing to the evolving nature of available technology, the high energy demand and correlative emissions of carbon and the unusual specific constraints in dedicated Oil and Gas energy plants. This paper presents our experience in this learning process applied to the oil & gas industrial environment. With the collaboration of Technip, Total initiated a study on the integration of carbon-capture solutions within cogeneration plants. On the strength of its in-house experience of oxy-combustion and acid gas removal, of transport and re-injection of acid gases, Total considered both oxy-combustion and post-combustion as promising technologies. The objective of the study was to assess the potential of each technology to tackle carbon capture on the two main types of thermo-mechanic converters present in a cogeneration plant: turbines and boilers, as well as evaluate the constraints. Alternative cogeneration plant concepts, with or without combined cycle were considered, to challenge further the impact of capture on cogeneration design. The actual operating conditions of a typical cogeneration plant burning clean natural gas, particularly its flue gas emissions, compatible with the target project’s constraints, were proposed as the design basis for capture systems of various scales. The requirement to keep to simple capture concepts was critical in view of the challenging economic environment of carbon capture, the evolving technology and the probable tightening of emission-reduction targets. Due to the uncertainties as to the final fate of the carbon dioxide, EOR or/and geo-storage, nearby or distant, in depleted fields or saline aquifers, being considered, several CO2 conditioning process options were defined. The integration of capture-ready building blocks within the plants was a significant step in the design process for alternative cogeneration plants, and enabled the synergies and constraints of operating the capture systems to be identified. The key risk items were highlighted, offering insight into the expected roadmap of the capture technology development. The results of this work compare the main features of the oxy-combustion and post-combustion CO2 capture technologies for steam-boiler and/or gas-turbine effluents and flag up some essential local constraints affecting the performance of the various capture-ready cogeneration schemes.