Method and device for chemical loop combustion of liquid hydrocarbon feedstocks

1. A method of performing chemical looping oxidation-reduction combustion of a liquid hydrocarbon feedstock in a fluidized bed, comprising:

in a first reaction zone partially vaporizing the liquid hydrocarbon feedstock by contact with a hot particulate solid to form a partially vaporized hydrocarbon feedstock and a coke coating on the hot particulate solid with particles of the hot particulate solid being within group A of Geldart's classification;

moving effluents from the first reaction zone to a second reaction zone where vaporizing of the partially vaporized hydrocarbon feedstock occurs and contact with a particulate redox active mass distinct from the hot particulate solid causes combustion of the vaporized hydrocarbon feedstock and gas resulting from gasification of the coke coated on the hot particulate solid with particles of the particulate redox mass being within group B of Geldart's classification;

conveying effluents from the second reaction zone to a third reaction zone and therein continuing combustion of at least one of the partially vaporized liquid hydrocarbon feedstock and the gas resulting from gasification of the coke;

separating from a mixture of effluents in a separation zone of the third reaction zone a major part of the particulate redox active mass and a gas stream containing a major part of the hot particulate solid; and

conveying effluents from the third reaction zone to a fourth reaction zone and carrying out therein reoxidation of the particulate redox active mass conveyed from the separation zone prior to sending at least part of the particulate redox active mass back to the second reaction zone.

2. A method as claimed in claim 1 , wherein the hot particulate solid and the gas resulting from gasification are separated in the separation zone from the gas stream containing the major part of the hot particulate solid particles prior to sending the hot particulate solid back to the first reaction zone.

3. A method as claimed in claim 1 , comprising atomizing the liquid hydrocarbon feed with a gas to form liquid droplets dispersed in the gas prior to contact with the hot particulate solid in the first reaction zone.

4. A method as claimed in claim 1 , wherein:

the hot particulate solid is selected from a used catalytic cracking catalyst, petroleum coke, sand, and limestone.

5. A method as claimed in claim 1 , wherein:

a size distribution of grains of the hot particulate solid and density of the hot particulate solid is lower than a distribution of grains of the particulate redox active mass and density of particles in the particulate redox active mass.

6. A method as claimed in claim 5 , wherein:

a size distribution of grains of the hot particulate solid is that more than 90% of particles having a size ranging from between 50 micrometers and 150 micrometers, and a density thereof ranges between 1000 kg/m3 and 1500 kg/m3, a size distribution of grains of the particulate redox active mass is that more than 90% of the particles have a size ranging between 100 micrometers and 500 micrometers and a density thereof ranges between 2500 kg/m3 and 4500 kg/m3.

7. A method as claimed in claim 1 , wherein:

a mass proportion of coke deposited on the hot particulate solid in the first reaction zone ranges between 1% and 20%.

8. A method as claimed in claim 1 , wherein:

the hot particulate solid contacted with the liquid hydrocarbon feedstock in the first reaction zone has a temperature ranging between 600° C. and 1000° C.

9. A method as claimed in claim 1 , wherein:

a superficial velocity of gas in the first reaction zone ranges between 1 m/s and 15 m/s and an average residence time for all particles in the first reaction zone ranges between 1 second and 20 seconds;

a superficial velocity of gas in the second reaction zone ranges between 0.3 m/s and 3 m/s and an average residence time for all particles in the second reaction zone ranges between 0.25 minutes and 20 minutes; and

a superficial velocity of gas in the third reaction zone ranges between 1 m/s and 30 m/s, an average residence time of the gas in the third reaction zone ranges between 1 second and 20 seconds, and an average residence time for all particles in the third reaction zone ranges between 2 seconds and 1 minute.

10. A system for chemical looping redox combustion of a liquid hydrocarbon feedstock carried out in a fluidized bed, comprising:

a first reaction zone in which the hydrocarbon liquid feedstock is partially vaporized and in which coke is deposited on a hot particulate solid and includes an injector of the liquid hydrocarbon feedstock, means for feeding the hot particulate solid to a second reaction zone, and means for injecting a fluidization gas;

the second reaction zone is disposed downstream from the first reaction zone in which the coke coated on the hot particulate solid is gasified and contacts a particulate redox active distinct from the hot particulate solid to combust vaporized liquid feedstock and gas resulting from gasification of the coke from contact with the hot particulate solid and comprises means for feeding the particulate redox active mass into the second reaction zone;

means for feeding effluents from the second reaction zone to a third reaction zone for completing combustion of at least one of the vaporized liquid feedstock and gas resulting from gasification of the coke coated on the hot particulate solid and includes a separation zone for separating from a mixture in the third reaction zone a major part of the particulate redox active mass and a gas stream containing a major part of the hot particulate solid, a delivery line for the mixture, a discharge of the particulate redox active mass, and an outlet for a gas stream containing the major part of the hot particulate solid; and

a fourth reaction zone for reoxidation of the particulate redox active mass obtained from the separation zone including means for feeding the particulate redox active mass from the separation zone to the fourth reaction zone, means for injecting an oxidation gas, and means for conveying a gas stream containing the particulate reoxidized redox active mass particles to the second reaction zone.

11. A system as claimed in claim 9 , wherein:

the injector for injecting the liquid hydrocarbon feed of the first reaction zone comprises means for mixing the hydrocarbon liquid feed with an atomizing gas and means for atomizing the hydrocarbon liquid feedstock.

12. A system as claimed in claim 10 , wherein:

the separation zone separates gas and solids within the third reaction zone from the hot particulate particles and the gas within a gas stream containing the major part of the hot particulate solid coming from the separation zone and recycles the hot particulate solid to the first reaction zone.

13. A system as claimed in claim 11 , wherein:

the first, second and third reaction zones are successive parts in a single reactor, a first part of the single reactor being at a base of the single reactor comprising an elongated and vertical reaction zone opening into a second part of the single reactor at a center of the single reactor comprising the second reaction zone, the second part of the single reactor extending to a third part of the reactor comprising the third reaction zone which is elongated and vertical and an area of section of the second part of the reactor is greater than that aa area of a section of the first and third parts of the reactor.

14. A system as claimed in claim 10 , wherein the first, second and third reaction zones are independent reactors connected by lines for transporting effluents between the zones.