Calcination process

Abstract

A process comprising the following steps: a) calcination of a metal carbonate by combustion of a fuel in the presence of a mixture of oxygen, water vapour and carbon dioxide, to generate a metal oxide, water vapour, carbon dioxide and heat; b) using the heat generated to drive an oxygen generation reaction; and c) use of the oxygen generated in step b) in calcination step a). The use of the process on carbon dioxide sequestration and/or in oxygen generation.

Claims

1. A process comprising: (a) performing calcination of a metal carbonate by combustion of a fuel in the presence of a mixture of oxygen, water vapour and carbon dioxide, to generate a metal oxide, water vapour, carbon dioxide and heat; (b) using the heat generated to drive an oxygen generation reaction; and (c) using oxygen from the oxygen generation reaction of step (b) in the performing calcination of step (a).

2. The process according to claim 1, using the heat generated in step (a) to compress the carbon dioxide generated in step (a).

3. The process according to claim 1, wherein the metal of the metal carbonate in step (a) is selected from the group consisting of a group II metal and a combination of group II metals.

4. The process according to claim 3, wherein the metal carbonate in step (a) is selected from the group consisting of magnesium carbonate, calcium carbonate, dolomite and combinations thereof.

5. The process according to claim 4, wherein the metal carbonate in step (a) comprises calcium carbonate.

6. The process according to claim 1, wherein the fuel of step (a) comprises a component selected from the group consisting of coal, coke, syngas, biomass, biogas, or one or more hydrocarbons, and combinations thereof.

7. The process according to claim 6, wherein the fuel of step (a) comprises at least one hydrocarbon.

8. The process according to claim 1, wherein the oxygen generation reaction of step (b) comprises a gas separation process which occurs in an environment selected from the group consisting of an Air Separation Unit (ASU) and a Pressure Swing Adsorption (PSA) System.

9. The process according to claim 8, wherein the oxygen generation reaction of step (b) occurs in a Pressure Swing Adsorption (PSA) system.

10. The process according to claim 1, further comprising sequestering the carbon dioxide generated in step (a).

11. The process according to claim 1, further comprising (d) hydrating the metal oxide generated in step (a) to produce a metal hydroxide and heat.

12. The process according to claim 1, further comprising using the heat generated during hydration of the metal oxide to drive the generation of oxygen in step (b).

13. The process according to claim 1, wherein a composition selected from the group consisting of the oxygen and the carbon dioxide and combinations thereof used in the combustion reaction of step (a) is greater than 95% pure.

14. The process according to claim 1, wherein oxygen generated in step (c) is greater than 95% pure.

15. The process according to claim 1, further comprising sequestering carbon dioxide generated in the recited processes.

16. The process according to claim 1, further comprising collecting the oxygen generated.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In order that the present invention may be more readily understood, it will be described further with reference to the figures.

(2) FIG. 1 is a schematic representation of a process according to the invention;

(3) FIG. 2 is a schematic representation of a process according to the invention, further comprising additional step d); and

(4) FIG. 3 is a schematic representation of a process according to the invention, further comprising additional step d) and using natural gas as the fuel.

DETAILED DESCRIPTION

(5) FIG. 1 shows the process of the invention, comprising step a), in which calcium carbonate is calcined via combustion of methane in the presence of oxygen and carbon dioxide. This results in the generation of calcium oxide, a pure stream of carbon dioxide, and water. The carbon dioxide generated can be separated from water vapour, and then directly sequestered, resulting in a carbon neutral system. The calcium oxide generated is cooled to ambient temperature and the heat energy released is then used to drive an oxygen generation reaction by a PSA system. The oxygen generation can be fed back into step a), resulting in a form of closed loop system in which in some modes of operation no gases are released to the atmosphere.

(6) FIG. 2 shows the process of the invention as outlined in FIG. 1, with the addition of step d). The calcium carbonate generated in step a) can be subsequently hydrated, forming calcium hydroxide (slaked lime), which is an exothermic reaction. The energy released in the hydration of calcium oxide can also be fed into the oxygen generation reaction.

(7) FIG. 3 shows the process of the invention comprising step a), in which calcium carbonate is calcined via combustion of natural gas in the presence of oxygen and carbon dioxide. This results in the generation of calcium oxide, and a stream of carbon dioxide and water vapour. The carbon dioxide and water vapour is then transferred to a condenser, where pure carbon dioxide is separated and can then be sequestered. The steam released from the condenser can then be partly recycled in the system, and also partly used to drive an oxygen generation reaction by a PSA system. The oxygen generated can be fed back into step a), resulting in a form of closed loop system, as described above.