Dra. Yolanda López

Among the main challenges of Carbon Capture and Storage (CCS) technologies, the reduction of energy penalties associated with the capture process and the integration of the new process in the design of a complex system - original power plant and capture facility - are major issues. Traditionally, the Second Law of Thermodynamics is an essential tool for process optimization through

ABSTRACT This technology makes use of the idea that lime may be reused in a cyclic process to remove CO2 from a mixture of gases where carbonate is calcined to generate a pure stream of CO2 ready for sequestration. Flue gas from an existing power plant is introduced in the carbonator where the CO2 reacts with CaO to form CaCO3. This process must occur at elevated temperatures (600-650 ºC depending on CO2 partial pressure). Removal rates around 80-90% seem to be a reasonable target for this technology. The formed calcium carbonate is circulated to a different reactor where sorbent regeneration takes place. CaCO3 is calcined and produces a concentrated stream of CO2 suitable for capture and compression. Calcination step is highly energy demanding and it will likely occur at temperatures above 920 ºC. Heat requirements for sorbent calcination are covered by oxyfuel combustion in the second reactor itself. Once regenerated, the sorbent is returned to the carbonator to begin a new sorption cycle. Because of the elevated temperatures, the entire cycle might be integrated in a steam cycle, reducing energy penalties of the capture system by several percentage points. The cost of natural sorbents for these cycles is significantly low, reducing operation costs. This chapter examines the energy penalties of the Ca-looping CO2 capture system, different types of sorbents and their performance subjected to repeated cycles of carbonation and calcination, the CO2 capture efficiency and the possibility of integration of Ca-looping and power plants to reduce energetic penalties.

Calcium looping has attracted a great deal of attention among researchers investigating CO2 capture systems. Energy consumption in the regeneration reactor is one of the most important issues. However, as a high-temperature process, calcium looping enables an efficient heat recovery in the capture process itself. The objective of this study is to reduce the energy consumption in the calciner by increasing the temperature of the solids entering this reactor. A calcium looping system including a mixing seal valve is modeled and analyzed to determine the potential advantages this configuration entails. The influence of different seal valve aeration gases, carbonator inventories and solid circulation between reactors is assessed. The reduction of the fuel consumption when the mixing seal valve is aerated with flue gas tends to dilute the CO2 stream. When using CO2, the achievement of substantial energy savings may imply an important increase of the solid flows in the system. Aeration of the mixing seal valve with both gases, so that each gas aerates one exit, is also proposed to address these issues. Results show a significant potential in terms of coal and oxygen savings and reduction of the CO2 generated in the capture system.

Compression of CO2 is an essential process in the development of carbon capture and storage (CCS) technologies. In spite of power requirements for CO2 compression could be as much as 100kWe per tonne CO2, the minimization of energy requirements has received little attention in the literature. Although intercooling compression reduces power requirements, it introduces important cooling necessities that could be

Carbon capture and storage are considered one of the most promising technologies to reduce emissions in a midterm. Its main drawback is the energy penalty caused by the CO2 separation and compression processes. It increases the CO2 avoided cost and it is an important driving force to propose new and improved capture methods with lower energy requirements. In the case