# US 12,760,673 B2 · Flue gas treatment device and design method of flue gas treatment device

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- Number: US 12,760,673 B2
- Document ID: US12760673B2
- Status: Granted
- Kind: B2
- Application number: 18/881,473
- Filed: 2023-05-26
- Published: 2026-01-01
- Granted: 2026-10-13
- Earliest claimed: 2022-07-07
- Assignees: Mitsubishi Heavy Industries, Ltd.
- Applicants: Mitsubishi Heavy Industries, Ltd.
- Inventors: Tomotsugu Masuda; Keiichiro Kai; Shimpei Kaneda
- Web page: https://patentgrep.com/patent/US12760673B2

## CPC

- F01N 3/2066: {Selective catalytic reduction [SCR]}
- F01N 2570/14: Nitrogen oxides
- F01N 2900/1402: Exhaust gas composition
- F01N 2900/1404: Exhaust gas temperature
- F01N: GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES (arrangements in connection with gas exhaust of propulsion units in vehicles B60K13/00; combustion-air intake silencers specially adapted for, or arranged on, internal-combustion engines F02M35/00; protecting against, or damping, noise in general G10K11/16)

## Abstract

Provided is a flue gas treatment device configured to treat a flue gas discharged from a combustion device that combusts fuel containing ammonia, and the flue gas treatment device includes: an ammonia decomposition unit having an ammonia decomposition catalyst that decomposes ammonia contained in the flue gas; and a nitrogen oxide decomposition unit having a second catalyst that decomposes nitrous oxide and NOx contained in the flue gas in which ammonia was decomposed by the ammonia decomposition unit.

## Claims

### Claim 1

A flue gas treatment device configured to treat a flue gas from a combustion device that combusts fuel containing ammonia, the flue gas treatment device comprising:
a first treatment unit having a first catalyst that decomposes ammonia contained in the flue gas;
a second treatment unit having a second catalyst that decomposes nitrous oxide and NOx contained in the flue gas in which ammonia was decomposed by the first treatment unit;
a detection unit configured to determine a concentration of nitrous oxide contained in the flue gas that passed through the second treatment unit; and
a first supply unit configured to supply ammonia or urea water into the flue gas supplied from the first treatment unit to the second treatment unit when the concentration of nitrous oxide contained in the flue gas is higher than a first predetermined concentration,
wherein the second catalyst is a catalyst that reduces and decomposes nitrous oxide contained in the flue gas by ammonia, and
wherein the first treatment unit removes, by the first catalyst, NOx produced when ammonia contained in the flue gas is decomposed.

### Claim 2 (depends on 1)

The flue gas treatment device according to claim 1, further comprising:
a bypass pipe configured to guide, to the second treatment unit, the flue gas from the combustion device without causing the flue gas to pass through the first treatment unit; and
a bypass valve arranged on the bypass pipe.

### Claim 3 (depends on 1)

The flue gas treatment device according to claim 1, further comprising a third treatment unit configured to decompose ammonia contained in the flue gas that passed through the second treatment unit.

### Claim 4 (depends on 1)

The flue gas treatment device according to claim 1, wherein
the detection unit is to measure a concentration of NOx contained in the flue gas that passed through the second treatment unit,
the first supply unit is configured to supply ammonia or urea water into the flue gas supplied from the first treatment unit to the second treatment unit when the concentration of NOx contained in the flue gas is higher than a second predetermined concentration,
wherein the second catalyst is a catalyst that reduces and decomposes NOx contained in the flue gas by ammonia.

### Claim 5 (depends on 4)

The flue gas treatment device according to claim 4, further comprising:
a temperature detection unit configured to determine a temperature of the flue gas from the first treatment unit; and
a second supply unit configured to supply ammonia or urea water into the flue gas supplied from the combustion device to the first treatment unit when the temperature determined by the temperature detection unit is lower than or equal to a predetermined temperature.

### Claim 6 (depends on 5)

The flue gas treatment device according to claim 5 further comprising a third treatment unit configured to decompose ammonia contained in the flue gas that passed through the second treatment unit.

### Claim 7 (depends on 5)

The flue gas treatment device according to claim 5, wherein the predetermined temperature is a temperature that is higher than or equal to 450° C. and lower than or equal to 530° C.