Air curtain for urea mixing chamber

Patent metadata

Field	Value
Publication number	US-RE48525-E
Application number	US-201916575187-A
Country	US
Kind code	E1
Filing date	Sep 18, 2019
Priority date	Aug 16, 2013
Publication date	Apr 20, 2021
Grant date	Apr 20, 2021

Abstract

An exemplary embodiment includes a blending chamber having a urea inlet, a blending chamber gas inlet, and a blending chamber outlet. A urea source provides a pressurized urea solution to the urea inlet at a urea injection pressure, and a pressurized gas source transmits pressurized gas to the blending chamber gas inlet via a passageway. The passageway is configured to decrease pressure of the pressurized gas transmitted along its length from a first pressure of gas received from the pressurized gas source to a second pressure of gas provided to the blending chamber gas inlet. The first pressure of gas received from the pressurized gas source is greater than the urea injection pressure and the second pressure of gas provided to the blending chamber gas inlet is less than the urea injection pressure.

First claim

The invention claimed is:

1. A system comprising:
a urea blending chamber having a urea inlet, a blending chamber gas inlet, and a blending chamber outlet, the urea blending chamber defining a first axial flow path;
a source of pressurized urea solution configured to provide pressurized urea solution to the urea inlet at a urea injection pressure, the urea inlet axially aligned with the first axial flow path so as to insert the pressurized urea solution along the first axial flow path; and
a pressurized gas source configured to transmit pressurized gas to the blending chamber gas inlet via a gas flow passageway extending along a length from the pressurized gas source to the blending chamber gas inlet, the gas flow passageway defining a second axial flow path oriented orthogonal to the first axial flow path of the urea blending chamber, the gas flow passageway including:
an inwardly tapered gas flow seating portion including a seating portion inlet having a first diameter,
a gas flow restriction portion adjacent to and downstream of the inwardly tapered gas flow seating portion, the gas flow restriction portion having a second diameter and an axial length, the second diameter and the axial length being configured to cause an increase in a velocity of the pressurized gas passing through the gas flow restriction portion to a value above a threshold velocity at which urea crystal migration upstream through the gas flow restriction portion is inhibited, and
a gas flow diffuser including a gas flow diffuser outlet having a third diameter larger than the second diameter and smaller than the first diameter, thus forming an outward taper to decrease the velocity of the pressurized gas;

wherein the gas flow passageway is configured to provide a pressure drop along a combined length of the gas flow restriction portion and the gas flow diffuser from a first pressure of gas received from the pressurized gas source to a second pressure of gas provided to the blending chamber gas inlet; and
wherein the first pressure of gas received from the pressurized gas source is greater than the urea injection pressure and the second pressure of gas provided to the blending chamber gas inlet is less than the urea injection pressure.

2. The system of claim 1 , wherein when a pressure at the blending chamber outlet is greater than the urea injection pressure, the pressurized urea solution injected into the urea blending chamber travels along a portion of the length of the gas flow passageway in which the pressure of the pressurized gas is equal to the second pressure of gas.

3. The system of claim 1 , wherein the gas flow passageway is configured to decrease velocity of the pressurized gas transmitted along its length from a first velocity at a first location along its length to a second velocity provided to the urea blending chamber.

4. The system of claim 3 , wherein the second velocity provided to the urea blending chamber is 47 meters per second or greater.

5. The system of claim 1 , wherein the gas flow passageway is defined in a nozzle extending through a cavity formed by a wall of the urea blending chamber, an outer surface of the nozzle defining a plurality of threads matingly engaged with a plurality of counter-shaped threads defined by an inner surface of the cavity.

6. The system of claim 1 wherein the gas flow passageway has a uniform cross sectional area between a first location downstream of the pressurized gas source and a second location downstream of the first location and an increasing cross sectional area between the second location and a third location downstream from the second location and upstream from the urea blending chamber gas inlet.

7. The system of claim 6 wherein the increasing cross sectional area is defined by a frustoconical surface of the gas flow passageway.

8. The system of claim 1 , wherein the blending chamber outlet is fluidly coupled to an injector nozzle configured to inject a urea-gas mixture into an exhaust gas conduit having a selective catalytic reduction (SCR) catalyst disposed therein at a position downstream of the injector nozzle.

9. The system of claim 8 , wherein the exhaust gas conduit is configured to receive an exhaust stream from a diesel engine, the exhaust stream comprising a NO x , constituent as a byproduct of operation of the diesel engine.

10. The system of claim 1 wherein the decrease in pressure value of the pressurized gas from the first pressure to the second pressure is 2 bar or greater.

11. The system of claim 1 wherein the gas flow passageway is configured to provide the pressurized gas to the blending chamber gas inlet at a first velocity of at least 47 meters per second and to provide the pressurized gas at a second velocity greater than the first velocity at a location upstream from the blending chamber gas inlet.

12. The system of claim 1 wherein the gas flow passageway is configured to provide the pressurized gas to the blending chamber gas inlet at a first velocity of at least 50 meters per second and to provide the pressurized gas at a second velocity greater than the first velocity at a location upstream from the blending chamber gas inlet.

13. The system of claim 12 , wherein the second velocity is between 50 meters per second and 60 meters per second at the location upstream from the blending chamber gas inlet.

14. An apparatus comprising:
a urea blending chamber having a urea inlet, a gas inlet, and an outlet, the urea blending chamber defining a first axial flow path;
an injector configured to provide pressurized urea solution to the urea inlet at a urea injection pressure, the urea inlet axially aligned with the first axial flow path so as to insert the pressurized urea solution along the first axial flow path; and
a valve configured to provide pressurized gas to a gas flow passage in flow communication with the valve and the gas inlet, the gas flow passage defining a second axial flow path oriented orthogonal to the first axial flow path of the urea blending chamber, the gas flow passage including:
an inwardly tapered gas flow seating portion including a seating portion inlet having a first diameter,
a gas flow restriction portion adjacent to and downstream of the inwardly tapered gas flow seating portion, the gas flow restriction portion having a second diameter and an axial length, the second diameter and the axial length being configured to cause an increase in a velocity of the pressurized gas passing through the gas flow restriction portion to a value above a threshold velocity at which urea crystal migration upstream through the gas flow restriction portion is inhibited, and
a gas flow diffuser including a gas flow diffuser outlet having a third diameter larger than the second diameter and smaller than the first diameter, thus forming an outward taper to decrease the velocity of the pressurized gas;
wherein the gas flow passage is configured to provide a pressure drop along a combined length of the gas flow restriction portion and the gas flow diffuser from a first pressure of gas received from the pressurized gas source to a second pressure of gas provided to the blending chamber gas inlet; and

wherein the first pressure is greater than the urea injection pressure and the second pressure is less than the urea injection pressure.

15. The apparatus of claim 14 wherein the decrease from the first pressure to the second pressure is 1-2 bar gauge.

16. The apparatus of claim 14 wherein the second pressure is less than the first pressure by at least 1 bar gauge.

Assignees

• Cummins Emission Solutions Inc

Inventors

• Muntean George L
• Holl Steve
• Chakrabarti Joydeep
• Anthis John
• Henry Joshua D
• Johnson Samuel
• Myer Andrew
• Heichelbech John K

Classifications

• B01F23/2132

  using nozzles · CPC title

• B01F2025/913

  Vortex flow, i.e. flow spiraling in a tangential direction and moving in an axial direction · CPC title

• B01F25/313

  wherein additional components are introduced in the centre of the conduit · CPC title

• Y02T10/12

  Improving ICE efficiencies · CPC title

• F01N2610/146

  Control thereof, e.g. control of injectors or injection valves · CPC title