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Title: Selective exhaust gas recirculation in combined cycle gas turbine power plants with post-combustion carbon capture
Author: Herraiz Palomino, Laura
ISNI:       0000 0004 6059 8497
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2017
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Gas-fired power plants with Carbon Capture and Storage (CCS) are expected to play a significant role to reduce carbon dioxide (CO2) emissions from the power generation sector. They can provide dispatchable low-carbon electricity to maintain the flexibility required in an electricity system with high penetration of renewables. The low CO2 concentration and large volumes of flue gas generated in natural gas-fired power plants make CO2 separation with post-combustion capture technologies more challenging, compared to coal-fired power plants. This thesis investigates options for increasing CO2 concentration upstream of the capture system by selectively transferring CO2 from a flue gas stream into an air stream used for natural gas combustion. Other components in the flue gas are not recirculated back to the inlet of the gas turbine system and a large excess of air is maintained. Strategies to enhance capture should aim to introduce minimal modification in the gas turbine engine, as current gas turbine technology presents high efficiency and plays an important role in achieving high combined cycle net power output. Process simulations in a linked model of a natural gas combined cycle plant with a carbon capture and compression system conducted in this thesis show that high CO2 levels at the exhaust of the gas turbine can be achieved maintaining levels of oxygen for efficient combustion, and that existing class of gas turbine engines can be operated with Selective Exhaust Gas Recirculation (S-EGR). For capture technologies using amine solvents, a reduction in equipment size and energy requirements are achieved. A novel system for selective CO2 transfer between a flue gas stream and an air stream is proposed consisting on rotary physical adsorption. A conceptual design assessment shows that a step change in the performance of adsorbent materials is necessary before this novel system can be commercially deployed. Finally, a novel contribution is made to show that the availability of cooling might not necessarily constitute a limitation for the full scale deployment of CCS, particularly in regions with increasingly restricted access to cooling water and limited availability of fresh or sea water abstraction licences. Process simulations showed that cooling and process water demand can be drastically reduced in natural gas-fired power plants with carbon capture by using dry cooling systems.
Supervisor: Lucquiaud, Mathieu Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: carbon capture ; power plant ; gas turbine