NOx Reduction Without Urea Using a Dual Stage Catalyst System With Intercooling in Vehicle Gasoline Engines

• US 20180230882A1
• Filed: 11/01/2017
• Published: 08/16/2018
• Est. Priority Date: 02/11/2017
• Status: Active Grant

• Current Assignee: Tecogen Inc.
• Original Assignee: Tecogen Inc.
• Inventors: Ghoniem, Ahmed F., Roy, Jean
• Granted Patent: US 10,774,720 B2
• Time in Patent Office: Days
• CPC Class Codes: F01N 2240/02 a heat exchanger
• CPC Class Codes: F01N 2240/22 a condensation chamber
• CPC Class Codes: F01N 2560/025 for measuring or detecting O2, e.g. lambda sensors
• CPC Class Codes: F01N 2560/06 the means being a temperature sensor
• CPC Class Codes: F01N 2900/1404 Exhaust gas temperature
• CPC Class Codes: F01N 3/02 for cooling, or for removing solid constituents of, exhaust by means of electric or electrostatic separators F01N3/01 ; mixing air with exhaust in tailpipes F01N13/082, F01N13/20
• CPC Class Codes: F01N 3/0205 using heat exchangers
• CPC Class Codes: F01N 3/021 by means of filters
• CPC Class Codes: F01N 3/035 with catalytic reactors , e.g. catalysed diesel particulate filters
• CPC Class Codes: F01N 3/043 without contact between liquid and exhaust gases
• CPC Class Codes: F01N 3/101 Three-way catalysts
• CPC Class Codes: F01N 3/106 Auxiliary oxidation catalysts
• CPC Class Codes: F01N 3/225 Electric control of additional air supply
• CPC Class Codes: F01N 3/30 Arrangements for supply of additional air control, e.g. using by-passes or variable air pump drives, F01N3/22
• CPC Class Codes: F01N 3/32 using air pump using jet air pumps F01N3/34; pumps in general F04
• CPC Class Codes: F01N 9/002 of filter regeneration, e.g. detection of clogging
• CPC Class Codes: Y02A 50/20 Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

An exhaust aftertreatment system includes a first catalytic converter, an oxidation catalyst including a storage catalyst, an air injector, and a cooling unit. The exhaust aftertreatment system is fluidly coupled to an output of a spark-ignited internal combustion engine that operates in the rich regime during acceleration and the lean regime during deceleration. In one aspect, the storage catalyst stores ammonia produced while the engine operates in the rich regime. The stored ammonia reacts with nitrogen oxide compounds produced when the engine operates in the lean regime. In another aspect, the nitrogen oxide compounds react with ammonia produced while the engine operates in the rich regime.

Claims

1. A system comprising:

a first catalytic converter including a three-way catalyst, the first catalytic converter receiving an exhaust generated by a spark-ignited internal combustion engine in a vehicle;

an oxidation catalyst comprising a storage catalyst, the oxidation catalyst in fluid communication with an output of the first catalytic converter;

an exhaust conduit extending from the first catalytic converter to the oxidation catalyst;

an air injector in fluid communication with the exhaust conduit; and

an exhaust gas intercooler in thermal communication with the exhaust in the exhaust conduit, the exhaust gas intercooler configured to lower a temperature of the exhaust to about 350°

F. to about 500°

F.

2. The system of claim 1, further comprising:

a radiator;

an EGI radiator cooling fluid circuit in thermal communication with said exhaust gas intercooler and said radiator; and

an engine radiator cooling fluid circuit in thermal communication with said engine and said radiator, wherein said engine radiator cooling fluid circuit is fluidically in parallel with said EGI radiator cooling fluid circuit.

3. The system of claim 2, wherein said EGI radiator cooling fluid circuit and said engine radiator cooling fluid circuit share a common radiator cooling fluid path that extends through a common radiator coil in said radiator.

4. The system of claim 1, wherein said oxidation catalyst comprises at least one of the following:

Pt, Ir, Rh, or Pd.

5. The system of claim 4, wherein said storage catalyst comprises at least one of a zeolite, vanadium or a titanium oxide carrier.

6. The system of claim 1, further comprising a gas particulate filter coupled to said exhaust conduit or said oxidation catalyst.

7. The system of claim 6, wherein said gas particulate filter and said oxidation catalyst are integrated as a catalyzed gas particulate filter.

8. The system of claim 1, wherein said air injector comprises an engine charger compressor.

9. The system of claim 8, further comprising:

a compressed air conduit extending from said engine charger compressor to an intake of said engine; and

an air ejection conduit extending from (a) said engine charger compressor or (b) said compressed air conduit to (c) said exhaust conduit, whereby said air ejection conduit introduces a stream of compressed air into said exhaust conduit.

10. The system of claim 9, further comprising an oxygen sensor disposed in said exhaust conduit between (a) an inlet port for said compressed air conduit and (b) said oxidation catalyst, the oxygen sensor outputting an oxygen content of said exhaust to a controller.

11. The system of claim 10, wherein said controller is configured to adjust said operating position of a flow control valve disposed in the air ejection conduit such that said oxygen content is at least about 0.1% by volume.

13. The apparatus of claim 1, wherein the exhaust gas intercooler is configured to lower the temperature of the exhaust to about 400°

F.

14. A method for reducing emissions from a spark-ignited internal combustion engine, the method comprising:

when said engine operates with a rich air-fuel ratio (AFR);

passing a rich exhaust generated by said engine with said rich AFR through a first stage catalytic converter;

with said rich exhaust, generating ammonia in the first stage catalytic converter;

cooling the rich exhaust, including the ammonia, in an exhaust gas intercooler to about 350°

F. to about 500°

F. to form cooled rich exhaust;

passing the cooled rich exhaust through an oxidation catalyst comprising a storage catalyst; and

storing at least some of the ammonia in the storage catalyst;

when said engine operates with a lean AFR;

passing a lean exhaust generated by said engine with said lean AFR through said first stage catalytic converter;

cooling the lean exhaust in said exhaust gas intercooler to about 350°

F. to about 500°

F. to form a cooled lean exhaust;

passing the cooled lean exhaust through the oxidation catalyst; and

reacting nitrogen oxide compounds in the cooled lean exhaust with the ammonia stored in the storage catalyst, thereby reducing a concentration of the ammonia and nitrogen oxide compounds in the rich and lean exhausts.

15. The method of claim 14, further comprising:

when said engine operates with said rich AFR, reacting at least some of the ammonia with the nitrogen oxide compounds, slipped by the first stage catalyst, in the second stage catalyst with air injection.

16. The method of claim 14, further comprising increasing an oxygen content of the cooled rich exhaust to at least about 0.1% by volume.

17. The method of claim 14, wherein the rich and lean exhausts are cooled to about 400°

F.