Combustion method with integrated CO2 separation by means of carbonation

Abstract

The invention relates to a method for separating CO2 from combustion gases, which can be used at areas with large emissions (thermal power stations using any carbonaceous fuel). The separated CO2 stream can be used and / or contained in geological formations. The inventive method aims to reduce the high costs involved in CO2 separation which prevent large-scale use of the CO2 confinement options included in the UN's IPCC reports. Said method consists of bringing the combustion gases into contact with a calcareous sorbent (limestone, calcined dolomite) at 650-750° C., thereby producing the CO2 capture reaction by means of the rapid carbonation of the sorbent. The sorbent is regenerated in another reactor (calciner) which operates in CO2 or CO2 / H2O atmospheres.

Description

TECHNICAL FIELD Energy sector. Large scale process for generating electricity and / or heat with integrated CO2 separation from the combustion gases. PRIOR ART The UN's International Panel for Climate Change (IPCC, 2001) considers the capturing of CO2 generated from large stationary sources and its subsequent containment in a variety of geological formations as a very interesting middle and long-term option. Use of these technologies require previous obtainment of a highly concentrated stream of CO2 (Herzog et al., 1997). The CO2 content of the combustion gases in different types of thermal power stations varies between 3 and 17% by volume, which makes a previous separation stage necessary. There are a variety of commercial methods for CO2 separation in the oil industry, natural gas industry and chemistry in general, mainly based on low temperature absorption processes, but use thereof for separating CO2 from combustion gases coming from a thermal power station has big limitations ...

AI Technical Summary

Benefits of technology

The calciner (2) operates at temperatures lower than 900° C. in atmospheres of pure CO2 or of CO2 / H2O. To reduce the calcination temperature and increase the temperature gradient between (1) and (2) the partial pressure of CO2 in the calciner can be reduced by applying a certain vacuum to (2) and / or injecting steam into (2). The heat exchange between (1) and (2) may be direct through metal walls or indirect by means of using an inert solid (sand, alumina or others) that continuously circulate through (1) and (2) and that is easily separable from the active solids in CO2 capture.

Problems solved by technology

There are a variety of commercial methods for CO2 separation in the oil industry, natural gas industry and chemistry in general, mainly based on low temperature absorption processes, but use thereof for separating CO2 from combustion gases coming from a thermal power station has big limitations (Herzog et al., 1997): the huge amounts of gas to be treated require large-size and very costly installations, require a large amount of energy to regenerate the sorbent which reduces the yields in generating useful electricity and / or heat and the pollutants in the fuel (SO2, NOx) tend to damage the absorbent which creates high operating costs.

All of them are non-commercial methods which are still under development.

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