Ana Martínez

Operation of a cyclonic preheater in the Ca-looping for CO2 capture.

Calcium looping is an emerging technology for CO2 capture that makes use of the calcium oxide as a sorbent. One of its main issues is the significant energy consumption in the calciner, where the regeneration of the sorbent takes place. Nevertheless, as a high temperature looping technology, the surplus heat flows may be used to reduce the energy needs in this reactor. The addition of a cyclonic preheater similar to those used in the cement industry is proposed in this work. A calcium looping system was modeled and simulated to assess the advantages and disadvantages of the inclusion of a cyclonic preheater. Despite the negative effect on the maximum average capture capacity of the sorbent, a reduction on the coal and oxygen consumptions and on the extra CO2 generated in the calciner is obtained.

Reductive elimination of the alkenyl fragment and a phosphine ligand from [Rh(acac){(E)-CHCHR}(PCy3)2]BF4 (R=Cy, Ph, H): preparation of [(E)-RHCCHPCy3]BF4 from alkynes

Abstract In dichloromethane under reflux, the five-coordinate alkenyl complexes [Rh(acac){(E)-CHCHR}(PCy3)2]BF4 [R=Cy (1), Ph (2), H (3)] evolve into the alkenylphosphonium derivatives [Rh(acac){η2-(E)-CH(PCy3)CHR}(PCy3)]BF4 [R=Cy (4), Ph (5), H(6)], by reductive elimination reactions involving the one-electron alkenyl fragments and one of the two-electron phosphine ligands of 1–3. Complexes 4–6 react with carbon monoxide to afford Rh(acac)(CO)(PCy3) and [(E)-RHCCHPCy3]BF4 [R=Cy (8), Ph (9), H (10)]. In addition, we describe a new route for the preparation of alkenylphophonium salts starting from terminal alkynes, PCy3 and HBF4, and using the Rh(acac)(PCy3) unit as a template.

Energy and exergy pertaining to solid looping cycles

Abstract This chapter describes why calcium looping and chemical looping combustion technologies are more efficient than their rivals, particularly when the aim is to produce a stream of CO2 for storage or utilization. The focus is on causes of inefficiency, and the development of solid looping cycle energy and exergy analyses as key tools to achieving designs with low efficiency penalties. The chapter concludes with a discussion of other CO2 capture technologies, and makes comparisons to highlight the advantages of solid looping processes. Future trends, especially in advanced process layouts of solid looping cycles, are also summarized.

Energy Intensity Reduction of Ca-Looping CO2 Capture by Applying Mixing Loop Seals and Cyclonic Systems

Abstract This work faces the challenge of cutting the specific energy demand in the CO2 capture process based on Ca-looping technology. The use of high-temperature sorbents allows an efficient integration of the excess heat flows. Up to now, several investigations studied the Ca-looping integration with external systems such as a steam cycle. In this research, a further step is done by comparing technological solutions for the internal heat integration with the aim of reducing the energy needs. Particles preheating before entering the regeneration reactor appears as an opportunity for energy saving since solids have to be heated up around 250–300°C from one reactor to another. Two different internal heat integration possibilities making use of a particle separation device and a mixing valve are presented and compared. The former consists of the inclusion of a cyclonic preheater. This configuration presents the a priori advantage of a more developed technology since it is widely used in the cement industry but the drawback of a worse gas–solid heat exchange. Although there is a lack of practical experience regarding the use of a single seal valve to feed two reactors, this configuration presents a promising prospective related to the excellent heat exchange features of the solid flows. The aim is to obtain comparative results by means of implementing advanced thermochemical models, in order to make progress on the development of less energy-intensive configurations of the calcium looping.