Pressurized oxycombustion process

1. An oxycombustion process wherein a combustor is fed with a fuel, a comburent, and compounds, the compounds having a form of coherent aggregates and comprising a Young modulus ≥10 4 MPa and sizes higher than 75 μm for at least 60% by weight of granulometric distribution,

wherein the aggregates have the above properties when the aggregates are introduced into the combustor, and wherein an amount of aggregates with respect to fuel ashes, which are generated by the combustion process, ranges from ≥5% in % by weight up to at most 1:1 by weight, the combustor being isothermal and flameless.

2. The oxycombustion process according to claim 1 wherein the combustor is operated at temperatures between 1,400K and 2,200K.

3. The oxycombustion process according to claim 1 wherein the combustor is operated under a pressure ranging from 103 kPa to 6,000 kPa.

4. The oxycombustion process according to claim 1 wherein the comburent is oxygen, the oxygen being used in admixture with water or steam and/or in admixtures with recycle fumes.

5. The oxycombustion process according to claim 4 wherein the admixture of oxygen and water or steam has a ratio by moles oxygen:water or oxygen:steam comprised between 1:0.4 and 1:3.

6. The oxycombustion process according to claim 4 wherein the admixture of oxygen and water or steam and/or recycle fumes have an amount of water or steam higher than 30% by volume and have a molar ratio oxygen:water or oxygen:steam comprised between 1:0.4 and 1:3.

7. The oxycombustion process according to claim 1 wherein the fuel is fed into the combustor in admixture with water or steam, the admixture of fuel and water or steam having an amount in percent with respect to the weight of the fuel of at least 30% and not higher than 90%.

8. The oxycombustion process according to claim 1 wherein the fuel is a liquid, solid, and/or gaseous fuel and is selected from the group consisting of hydrocarbon solids, brought to melting/liquefaction by heating, and fed as viscous liquids, biomasses, animal flours, coal, industrial wastes from neutralization reactions, high-boiling refinery fractions, bitumens and oil shales, processing scraps of tar sands, peats, exhausted solvents, pitches, industrial process scraps and waste, emulsions of liquid fuels of oil origin, liquid hydrocarbons, methane, low molecular weight hydrocarbons, and syngas.

9. The oxycombustion process according to claim 1 wherein the aggregates have particle sizes not higher than 900 μm.

10. The oxycombustion process according to claim 1 wherein the Young modulus of the aggregates is not higher than 10 6 MPa.

11. The oxycombustion process according to claim 1 wherein the aggregates are fed to the combustor separately from the fuel or in admixture thereof.

12. The oxycombustion process according to claim 1 wherein the aggregates are contained in the fuel.

13. The oxycombustion process according to claim 1 wherein the aggregates are minerals.

14. The oxycombustion process according to claim 1 wherein the aggregates are vitreous slags coming from combustion processes separated at the bottom of the combustor.

15. The oxycombustion process according to claim 1 wherein the aggregates have a hardness higher than 3 according to Mohs scale.

16. The oxycombustion process according to claim 1 wherein the fuel in the combustor has a residence time ranging from 0.5 seconds up to 30 minutes.

17. The oxycombustion process according to claim 1 wherein the combustor is refractored.

18. Flue gases obtainable with the process of claim 1 .

19. The flue gases according to claim 18 having:

a TOC content determined as carbon, lower than 0.01 mg/Nm 3 flue gas dry basis; and

inorganic ashes, whose integral of numerical distribution of particles having sizes <1 μm is lower than 650,000/cm 3 and whose integral of numerical distribution of particles having sizes <0.1 μm is lower than 400,000/cm 3 ;

when a following test is used:

in a thermal 3 MW combustor, operating at a pressure of 13 absolute bar at a temperature of 1430° C. by feeding carbon as fuel and oxygen 90% by volume as comburent, the flue gas having an oxygen concentration equal to 3% by volume, coal being fed as a slurry with water at 35% by weight, and oxygen being fed in admixture with water or steam and with recycle fumes,

wherein the admixture contains 55% by volume of steam and the integrals of the numeral distribution are determined with an electrical low pressure impactor particle size spectrometer.