Chemical looping combustion process with multiple fuel reaction zones and gravity feed of oxidized particles

Patent metadata

Field	Value
Publication number	US-9765961-B2
Application number	US-201514660477-A
Country	US
Kind code	B2
Filing date	Mar 17, 2015
Priority date	Mar 17, 2015
Publication date	Sep 19, 2017
Grant date	Sep 19, 2017

Abstract

An improved chemical looping combustion (CLC) process and system includes a hopper containing oxygen carrier particles, e.g., metal oxides, that are gravity fed at a controlled rate of flow from the hopper into (a) a generally vertical downflow reactor where they are mixed with all of the hydrocarbon fuel feed to the system and (b) into one or more standpipes that are in communication with a plurality of staged fluidized reactor beds, the amount of the oxygen carrier particles introduced into the system being stoichiometrically predetermined to produce a syngas mixture of H 2 and CO 2 ; or to complete combustion of the fuel to CO 2 and water vapor, thereby permitting capture of a majority of the CO 2 produced in an essentially pure form.

First claim

The invention claimed is:

1. A chemical looping combustion process for the recovery of CO 2 comprising:
a. atomizing a preheated hydrocarbon feed, wherein the preheated hydrocarbon feed is intimately mixed with dispersing steam in a mixing zone and introduced into the upper portion of a downflow reactor;
b. contacting the atomized hydrocarbon feed and steam mixture with a predetermined amount of hot oxidized particles of metal oxide which are introduced by gravity feed into the upper portion of the downflow reactor, wherein the hydrocarbon feed is vaporized and reacts with the metal oxides, thereby reducing the oxidation state of the metal oxides to produce reaction products comprising CO 2 and H 2 O, and reduced metal oxide particles containing coke;
c. passing the reaction products and reduced metal oxides from the downflow reactor to a first fluidized fuel reactor containing fresh oxidized particles, wherein coke formed on the particles of metal oxide is gasified, resulting in gasification products comprising CO and H 2 which further react with the metal oxides;
d. passing the reaction products comprising CO 2 , H 2 O and unreacted gases and any unreacted fuel from the downflow reactor and first fluidized fuel reactor through a perforated plate that is dimensioned and configured to retain the metal oxide particles, and into a second fluidized fuel reactor containing fresh particles of oxidized metal oxide in which any unreacted gases are reacted;
e. passing gaseous reaction products and any entrained particulate matter from the second fluidized fuel reactor to a separation device in which the gaseous reaction products are separated from the particulate matter and recovered as a product stream and the particulate matter is recycled to the first fluidized fuel reactor;
f. passing the particles of reduced metal oxide from the first and second fluidized fuel reactors to separate bed holder loop seals from which the particles of reduced metal oxide are passed to an air reactor and into contact with a moving stream of an oxygen-containing gas to oxidize the reduced metal;
g. passing particles of freshly oxidized metal oxide from the air reactor to a hopper from which the metal oxides are gravity fed at predetermined controlled rates to each of:
i. the downflow reactor of step (a);
ii. the first fluidized fuel reactor of step (c);
iii. the second fluidized fuel reactor of step (e); and
iv. optionally, to an intake of the air reactor via a separation device which separates any gas from the metal oxide; and

h. recovering a stream of substantially pure CO 2 .

2. The method of claim 1 in which the metal oxide particles in the hopper are maintained in a fluidized state.

3. The method of claim 1 in which the rate of passage of the oxidized metal particles into each of the (a) downflow reactor, (b) first fuel reactor and (c) second fuel reactor is controlled by a preprogrammed microprocessor/controller operatively connected to particle feeding devices each of which devices are in communication with the upper portion of the downflow reactor and standpipes to the first and second fuel reactors, respectively.

4. The method of claim 1 in which the separation device at the discharge end of the air reactor is a cyclone separator.

5. A chemical looping combustion process comprising:
a. atomizing and mixing a preheated hydrocarbon feed with dispersing steam and introducing into the mixture into the upper portion of a downflow reactor;
b. contacting the atomized hydrocarbon feed and steam mixture with hot particles of metal oxide in the upper portion of the downflow reactor, wherein the hydrocarbon feed is vaporized and reacts with the metal oxides, thereby reducing the oxidation state of the metal oxide particles and producing reaction products comprising CO 2 and H 2 O, and particles of reduced metal oxides;
c. passing the reaction products and reduced metal oxide particles from the downflow reactor to a fluidized fuel reactor, wherein any unreacted hydrocarbon gases are collected in a gas collector at the exit of the downflow reactor and the remaining reaction products and particles of metal oxides are passed to the lower portion of the fuel reactor, where any coke formed on the metal oxide is gasified;
d. contacting the collected unreacted gases with particles of oxidized metal oxides which are passed in counter-current flow with the collected gas, thereby producing additional CO 2 and H 2 O;
e. passing reaction gases from the fluidized fuel reactor to a separation device, where any particles entrained in the reaction products are separated from the reaction products and the particles are recycled to the fluidized fuel reactor;
f. recovering the reaction products as a product stream;
g. passing the reduced metal oxide particles from the fluidized reactor to a bed holder loop seal from which the particles of reduced metal oxides are passed to an air reactor to oxidize the reduced metal oxides;
h. passing particles of freshly oxidized metal oxide from the air reactor to a hopper from which the metal oxides are gravity fed at predetermined controlled rates to each of:
i. the downflow reactor of step (a);
ii. the first fluidized fuel reactor of step (c);
iii. the second fluidized fuel reactor of step (e); and
iv. optionally, to an intake of the air reactor via a separation device which separates any gas from the metal oxide.

6. A chemical looping combustion reactor system comprising:
a downflow reactor having means for receiving and contacting an atomized hydrocarbon feedstream with hot oxidized metal oxide particles passed from a fluidized hopper;
a first fluidized fuel reactor positioned to receive fresh hot oxidized metal oxide particles from the hopper, the first reactor in fluid communication with the downflow reactor for receiving the downflow reactor reaction products and in fluid communication with a separating device for receiving separated particles of metal oxide;
a perforated plate separating the first fluidized fuel reactor from a second fluidized fuel reactor, the perforated plate being configured and dimensioned to prevent the passage of particles of metal oxide and to pass reaction products from the first fluidized fuel reactor to the second fluidized fuel reactor;
the second fluidized fuel reactor having means for receiving the particles of oxidized metal oxide from the hopper and contacting the particles of metal oxide with reaction products from the first fluidized fuel reactor;
the separating device being in fluid communication with the second fluidized fuel reactor and configured and dimensioned to receive and separate the reaction products from any entrained particulate material;
a first bed holder seal in fluid communication with the first fuel reactor adapted to receive the particles of reduced metal oxide particles from the first fuel reactor and a second bed holder seal in fluid communication with the second fuel reactor adapted to receive the particles of reduced metal oxide particles from the second reactor, the first and second bed holder seals operatively connected to the intake of an air reactor adapted to oxidize the reduced metal oxide particles and discharge the oxidized particles into the hopper; and
passing particles of freshly oxidized metal oxide from the air reactor to a hopper from which the metal oxides are gravity fed at predetermined controlled rates to each of:
i. the downflow reactor of step (a);
ii. the first fluidized fuel reactor of step (c);
iii. the second fluidized fuel reactor of step (e); and
iv. optionally, to an intake of the air reactor via a separation device which separates any gas from the metal oxide.

7. A chemical looping combustion reactor system comprising:
a downflow reactor having means

Assignees

• Saudi Arabian Oil Co

Inventors

• Hoteit Ali

Classifications

• F23C6/042 Primary

  with fuel supply in stages (for staged combustion F23C6/047) · CPC title

• F23C10/10

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

• F23C10/01 Primary

  in a fluidised bed of catalytic particles · CPC title

• F23C99/00

  Subject-matter not provided for in other groups of this subclass · CPC title

• 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