Chemical-looping combustion method with ashes and fines removal in the reduction zone and plant using same

Patent metadata

Field	Value
Publication number	US-9726369-B2
Application number	US-201214346133-A
Country	US
Kind code	B2
Filing date	Aug 9, 2012
Priority date	Sep 20, 2011
Publication date	Aug 8, 2017
Grant date	Aug 8, 2017

Abstract

The invention relates to an improved method for chemical-looping combustion of a solid hydrocarbon-containing feed using a particular configuration of the reduction zone with: a first reaction zone R 1 operating under dense fluidized bed conditions; a second reaction zone R 2 ; a fast separation zone S 3 for separation of the unburnt solid feed particles, of fly ashes and of the oxygen-carrying material particles within a mixture coming from zone R 2 ; fumes dedusting S 4 ; a particle stream division zone D 7 , part of the particles being directly recycled to first reaction zone R 1 , the other part being sent to an elutriation separation zone S 5 in order to collect the ashes through a line 18 and to recycle the dense particles through a line 20 to first reaction zone R 1 .
The invention also relates to a chemical-looping combustion plant allowing said method to be implemented.

First claim

The invention claimed is:

1. A method for chemical-looping combustion of a hydrocarbon-containing feed of solid particles in which an oxygen-carrying material in form of particles circulates, said method comprising at least:
contacting of the hydrocarbon-containing solid feed particles with the oxygen-carrying material particles in a first reaction zone R 1 operating under dense fluidized bed conditions to produce gaseous effluents carrying the oxygen-carrying material particles,
combustion of the gaseous effluents from the first reaction zone R 1 in the presence of the oxygen-carrying material particles in a second reaction zone R 2 ,
separation of unburnt solid feed particles, of fly ashes and of the oxygen-carrying material particles within a mixture coming from the second zone R 2 in a fast separation zone S 3 yielding a first stream comprising combustion fumes that contain a major part of the unburnt solid feed particles and the fly ashes, and a second stream comprising a major part of the oxygen-carrying material particles, the second stream being sent to an oxidation zone R 0 ,
dedusting of the combustion fumes from the fast separation zone S 3 in a fumes dedusting zone S 4 so as to discharge a dedusted gas stream and a stream of particles containing fly ashes and dense particles predominantly comprising oxygen-carrying material particles and unburnt solid feed particles,
division of the stream of particles separated in dedusting stage S 4 into two streams in a stream division zone D 7 , one stream being recycled to first reaction zone R 1 operating under dense fluidized bed conditions, the other stream being sent to an elutriation separation zone S 5 ,
elutriation separation of the fly ashes from the dense particles in said elutriation separation zone S 5 so as to recover the fly ashes and to recycle the dense particles to the first reaction zone R 1 .

2. A method as claimed in claim 1 , comprising:
sedimentation of furnace ashes agglomerated in the bottom of first reaction zone R 1 in a fluidization zone S 6 located beneath first reaction zone R 1 ,
extraction of a particle stream comprising at least 10 mass % of agglomerated furnace ashes.

3. A method as claimed in claim 2 , wherein zone S 6 is fluidized by a gas with a fluidization gas rate in the largest cross-section of flow of the zone S 6 that does not exceed 3 times the minimum rate of fluidization of the oxygen-carrying material.

4. A method as claimed in claim 3 , wherein extraction of the agglomerated ashes in fluidization zone S 6 is performed using a cooled screw.

5. A method as claimed in claim 1 , wherein the solid feed is selected from among coal, coke, pet coke, biomass, bituminous sands and domestic waste.

6. A method as claimed in claim 1 , wherein the oxygen-carrying material is a pulverulent solid whose particle size is such that 90% of the grain size distribution ranges between 150 and 300 microns.

7. A method as claimed in claim 1 , wherein said one stream recycled to the first dense fluidized-bed reaction zone R 1 represents at least 50% of the stream of particles separated in the dedusting zone S 4 flowing into the stream division zone D 7 .

8. A method as claimed in claim 7 , wherein said one stream recycled to first dense fluidized-bed reaction zone R 1 represents at least 80% of the stream division zone D 7 .

9. A method as claimed in claim 1 , wherein the fly ash concentration in the mixture circulating in the combustion zone of the second reaction zone R 2 is below 5 wt. %.

10. A method as claimed in claim 9 , wherein the fly ash concentration in the mixture circulating in the combustion zone of the second reaction zone R 2 is below 1 wt. %.

11. A plant for carrying out chemical-looping redox combustion of a solid hydrocarbon feed according to the method as claimed in claim 1 , said plant comprising at least:
a first reaction zone R 1 comprising a solid feed supply line, a fluidization gas supply line and a supply line for the oxygen-carrying particles from oxidation zone R 0 ,
a second reaction zone R 2 receiving a gaseous effluent containing particles from the first reaction zone R 1 ,
a fast solid particle separation zone S 3 receiving combustion fumes from the second reaction zone R 2 containing fly ashes, oxygen-carrying material particles and unburnt solid feed particles, and comprising a discharge line for discharging a major part of the oxygen-carrying material particles to the oxidation zone R 0 ,
a fumes dedusting zone S 4 receiving through an inlet lighter particles entrained by the combustion fumes from the fast separation zone S 3 ,
a stream division zone D 7 receiving through an inlet a stream of particles separated from the fumes the fumes dedusting zone S 4 , said stream of particles separated from the fumes dedusting zone S 4 comprising fly ashes and dense particles predominantly made up of oxygen-carrying material particles and unburnt solid feed particles,
an elutriation separation zone S 5 receiving through an inlet a minor part of the particle stream divided in stream division zone D 7 , comprising a supply line allowing a supply of a fluidization gas and a discharge line allowing discharge of lighter particles comprising fly ashes and oxygen-carrying material fines,
a line coming from the stream division zone D 7 for recycling directly a major part of the particle stream divided in the stream division zone D 7 to the first reaction zone R 1 ,
a line coming from the elutriation separation zone S 5 for recycling dense particles separated by the elutriation separation zone S 5 to the first reaction zone R 1 .

12. A plant as claimed in claim 11 , wherein the cross-section of flow of second reaction zone R 2 is smaller than the cross-section of flow of the first reaction zone R 1 .

13. A plant as claimed in claim 11 , comprising a sedimentation zone for the agglomerated furnace ashes arranged beneath first reaction zone R 1 and comprising:
an agglomerated ashes supply line,
a fluidization zone S 6 ,
one or more lines allowing a fluidization gas to be fed,
a discharge line for recycling the oxygen-carrying material particles to the first reaction zone R 1 ,
a line for extraction of a particle stream containing at least 10 mass % of agglomerated furnace ashes.

14. A plant as claimed in claim 13 , wherein fluidization zone S 6 is a truncated zone with a half angle with respect to the vertical less than or equal to 15°.

Assignees

• Gauthier Thierry
• Hoteit Ali
• Guillou Florent
• Rifflart Sébastien
• Total Sa
• Ifp Energies Now

Inventors

• Gauthier Thierry
• Hoteit Ali
• Guillou Florent
• Rifflart Sébastien

Classifications

• F23C2900/99008

  Unmixed combustion, i.e. without direct mixing of oxygen gas and fuel, but using the oxygen from a metal oxide, e.g. FeO · CPC title

• F23C10/01 Primary

  in a fluidised bed of catalytic particles · CPC title

• F23C10/10

  the separation apparatus being located outside the combustion chamber · CPC title

• B01J8/1827

  the fluidising gas being a reactant · CPC title

• B01J8/26

  with two or more fluidised beds, e.g. reactor and regeneration installations · CPC title