# US 8,771,638 B2 · Method and apparatus for sequestering carbon dioxide from a spent gas

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- Number: US 8,771,638 B2
- Document ID: US8771638B2
- Status: Granted
- Kind: B2
- Application number: 13/768,331
- Filed: 2013-02-15
- Published: 2013-07-04
- Granted: 2014-07-08
- Earliest claimed: 2009-04-20
- Assignees: Midrex Technologies, Inc.
- Applicants: Gary E. Metius; James M. McClelland
- Inventors: Gary E. Metius; James M. McClelland
- Web page: https://patentgrep.com/patent/US8771638B2

## CPC

- B01D 53/00: Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols, (recovery of volatile solvents by condensation B01D5/00; sublimation B01D7/00; cold traps, cold baffles B01D8/00; working-up undefined gaseous mixtures obtained by cracking hydrocarbon oils C10G70/00; cleaning coal gas C10K; working-up of natural gas, or synthetic natural gas, C10L3/10; separation of difficult-to-condense gases or air by liquefaction F25J; for investigating materials G01N30/00)
- B01D 53/1475: {Removing carbon dioxide}
- C01B 3/384: with external heating of the catalyst
- C21B 13/0073: {Selection or treatment of the reducing gases}
- C21B 13/02: in shaft furnaces
- F27D 17/17: for preheating fluids, e.g. air or gases
- B01D 2258/025: from metallurgy plants
- B01J 2219/00006: Large-scale industrial plants
- C01B 2203/0233: the reforming step being a steam reforming step
- C01B 2203/0238: the reforming step being a carbon dioxide reforming step
- C01B 2203/0811: by combustion of fuel
- C01B 2203/0822: the fuel containing hydrogen
- C01B 2203/0827: at least part of the fuel being a recycle stream
- C01B 2203/0894: Generation of steam
- C01B 2203/1241: Natural gas or methane
- C01B 2203/148: involving a recycle stream to the feed of the process for making hydrogen or synthesis gas
- C01B 2203/84: Energy production
- C01B 2203/86: Carbon dioxide sequestration
- C21B 2100/22: by reforming
- C21B 2100/282: of carbon dioxide
- C21B 2100/66: Heat exchange
- Y02C 20/40: of CO2
- Y02P 10/122: by capturing or storing CO2
- Y02P 10/134: by avoiding CO2, e.g. using hydrogen
- Y02P 10/25: Process efficiency
- Y02P 20/10: Process efficiency
- Y02P 20/151: Reduction of greenhouse gas [GHG] emissions, e.g. CO2
- Y02P 30/00: Technologies relating to oil refining and petrochemical industry
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}
- C21B: MANUFACTURE OF IRON OR STEEL (preliminary treatment of ferrous ores or scrap C22B1/00)
- F27D: DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
- B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- Y02C: CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

A method and apparatus for sequestering carbon dioxide from a waste gas and reusing it as a recycled gas without emissions concerns, including: given a gas source divided into a process gas and a waste gas: mixing the process gas with a hydrocarbon and feeding a resulting feed gas into a reformer for reforming the feed gas and forming a reducing gas; and feeding at least a portion of the waste gas into a carbon dioxide scrubber for removing at least some carbon dioxide from the waste gas and forming a carbon dioxide lean gas that is mixed with the reducing gas. Optionally, the method also includes feeding at least a portion of the waste gas into the carbon dioxide scrubber for removing at least some carbon dioxide from the waste gas and forming a fuel gas after the addition of a hydrocarbon that is fed into the reformer. Optionally, the gas source and the reducing gas are associated with a direct reduction process for converting iron oxide to metallic iron in a reduction furnace that utilizes the reducing gas, optionally after some modification, and produces the gas source.

## Claims

### Claim 1

A method for sequestering carbon dioxide from a top gas fuel, comprising:
given a top gas divided into a process gas and a top gas fuel:
mixing the process gas with a hydrocarbon and feeding a resulting reformer feed gas into a reformer for reforming the reformer feed gas and forming a reducing gas; and
feeding at least a portion of the top gas fuel into a carbon dioxide scrubber for removing at least some carbon dioxide from the top gas fuel and forming a carbon dioxide lean gas that is selectively mixed with the reducing gas;
wherein a volume ratio of the process gas to the top gas fuel is responsive to available heat in the reformer to which the reformer feed gas is fed; and
wherein the volume ratio of the process gas to the top gas fuel is 1:1 when the carbon dioxide lean gas is fully utilized for mixing with the reducing gas and is 2:1 when the carbon dioxide lean gas is not utilized for mixing with the reducing gas.

### Claim 2 (depends on 1)

The method of claim 1, further comprising feeding at least a portion of the top gas fuel into the carbon dioxide scrubber for removing at least some carbon dioxide from the top gas fuel and forming a reformer fuel gas after the addition of a hydrocarbon that is fed into the reformer.

### Claim 3 (depends on 2)

The method of claim 2, further comprising compressing the process gas and the top gas fuel.

### Claim 4 (depends on 1)

The method of claim 1, further comprising generating steam from the top gas.

### Claim 5 (depends on 4)

The method of claim 4, further comprising scrubbing the top gas to remove dust.

### Claim 6 (depends on 1)

The method of claim 1, wherein the top gas is obtained from a reduction furnace.

### Claim 7 (depends on 1)

The method of claim 1, further comprising mixing the reducing gas with oxygen and a hydrocarbon to form bustle gas and feeding the bustle gas into a reduction furnace.

### Claim 8 (depends on 1)

The method of claim 1, further comprising preheating the carbon dioxide lean gas before mixing it with the reducing gas.

### Claim 9 (depends on 1)

The method of claim 1, wherein the reformer also produces flue gas.

### Claim 10 (depends on 9)

The method of claim 9, further comprising generating steam from the flue gas.

### Claim 11 (depends on 10)

The method of claim 10, further comprising using the flue gas to preheat another gas.

### Claim 12 (depends on 1)

The method of claim 1, wherein the top gas and the reducing gas are associated with a direct reduction process for converting iron oxide to metallic iron.