# US 2014/0196438 A1 · Assembly and method for reducing nitrogen oxides, carbon monoxide and hydrocarbons in exhausts of internal combustion engines

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- Number: US 2014/0196438 A1
- Document ID: US20140196438A1
- Status: Published application
- Kind: A1
- Application number: 14/077,607
- Filed: 2013-11-12
- Published: 2014-07-17
- Earliest claimed: 2010-04-28
- Assignees: Tecogen, Inc.
- Applicants: Tecogen, Inc.
- Inventors: Joseph B. Gehret; Robert A. Panora; Ranson Roser
- Web page: https://patentgrep.com/patent/US20140196438A1

## CPC

- F01N 3/2882: {Catalytic reactors combined or associated with other devices, e.g. exhaust silencers or other exhaust purification devices (combined with absorbents or adsorbents only F01N3/0814; combined with particulate filters F01N3/035)}
- F01N 3/0205: {using heat exchangers}
- F01N 3/04: using liquids
- F01N 3/05: by means of air, e.g. by mixing exhaust with air (silencers working by addition of air to exhaust F01N1/14; arrangements for the supply of additional air for the thermal or catalytic conversion of noxious components of exhaust F01N3/30)
- F01N 3/101: {Three-way catalysts}
- F01N 3/2046: {Periodically cooling catalytic reactors}
- F01N 13/009: {having two or more separate purifying devices arranged in series}
- F01N 13/0097: {the purifying devices are arranged in a single housing}
- F01N 2240/36: an exhaust flap
- Y02T 10/12: Improving ICE efficiencies
- 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)
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

An assembly and method for reducing nitrogen oxides, carbon monoxide and hydrocarbons in exhausts of internal combustion engines, wherein the exhaust is acted upon in a first stage catalytic converter. A first portion of the first stage catalytic converter output is cooled and a second portion of the catalytic converter output is not cooled. The cooled and not cooled exhausts are united and directed to a second stage catalytic converter. Air is injected into a selected one of (1) the not cooled exhaust prior to the juncture thereof with the cooled exhaust, and (2) the combined cooled and not cooled exhausts after the juncture thereof.

## Claims

### Claim at position 1

-23. (canceled)

### Claim 24

A method of operating a catalytic system for reducing emissions from a rich burn spark-ignited engine, comprising:
controlling intake air and fuel (AFR) to produce first exhaust gases substantially free of oxygen;
passing said first exhaust gases into a first-stage catalyst chamber containing a three-way catalyst (TWC) operating above 800° F., which minimizes NOx content by reducing NOx (to N2 and O2), without minimizing CO content;
passing exhaust gases exiting from the first-stage catalyst chamber to an inter-stage cooling chamber having
a) cooling means, and cooling by-pass means, which are used to adjust gas temperature to a controlled Tmix=390−520° F., and
b) secondary air injection means, which enriches the oxygen content to about 0.25-1.0%;
passing exhaust gases exiting from the inter-stage cooling chamber to a second-stage catalyst chamber containing a catalyst that minimizes CO content by oxidizing CO to CO2, without substantially increasing NOx emissions.

### Claim 25 (depends on 24)

The method of claim 24, wherein the engine is a stationary engine in combined heat and power (CHP) application.

### Claim 26 (depends on 25)

The method of claim 25, wherein Tmix=390−420° F.

### Claim 27 (depends on 25)

The method of claim 25, wherein the AFR is provided using a gaseous fuel/air mixer, a computer controlled fuel valve, and gaseous fuel is provided to the fuel/air mixer at atmospheric pressure.

### Claim 28 (depends on 27)

The method of claim 27, wherein said gaseous fuel is Natural Gas.

### Claim 29 (depends on 25)

The method of claim 25, wherein emissions of NOx exiting the first stage catalyst chamber are less than 3.7 ppm (at 15% O2), and emissions of CO exiting the second stage catalyst chamber are less than 8.9 ppm (at 15% O2), said emissions based on time-average data taken over an extended interval.

### Claim 30 (depends on 24)

The method of claim 24, wherein the inter-stage cooling chamber provides for injection of water.