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Apparatus for Maintaining a Urea Solution in a Liquid State for Treatment of Diesel Exhaust

Inactive Publication Date: 2011-01-13
DELPHI TECH INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

A serious problem in the prior art is that at temperatures below about −11° C., the urea solution can freeze.
In prior art systems when the solution in the storage tank is frozen, meeting this requirement can be difficult because of limited heat flow through the walls of the reservoir tank module, which typically is formed of a plastic polymer having relatively low thermal conductivity.

Method used

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  • Apparatus for Maintaining a Urea Solution in a Liquid State for Treatment of Diesel Exhaust
  • Apparatus for Maintaining a Urea Solution in a Liquid State for Treatment of Diesel Exhaust
  • Apparatus for Maintaining a Urea Solution in a Liquid State for Treatment of Diesel Exhaust

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Embodiment Construction

[0017]Referring to FIG. 1, a portion of an exemplary prior art system 10 for supplying a solution of urea to a diesel exhaust emissions abatement system 12 for a diesel engine 14 comprises a reservoir tank module 16 disposed within a storage tank 18 for urea solution 20. Solution 20 enters tank module 16 via an inlet 22 and is dispensed via an outlet 24. A heater 26 is disposed within tank module 16 for liquefying solution 20 within module 16. Excess heat from heater 26 is intended to pass through the walls 28 of tank module 16 and locally liquefy solution 20 in proximity to tank module 16 and inlet 22 to allow gravitational replenishment of solution into tank module 16. As described above, a problem exists in operation of prior art systems 10 in that walls 28 of reservoir tank module 16 are typically formed of a plastic polymer having relatively low thermal conductivity such that at extreme low temperature conditions insufficient heat is passed into storage tank 18 to maintain an a...

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Abstract

A system for keeping a reservoir solution of urea in a liquid state at normally sub-freezing temperatures comprising a reservoir tank module disposed in a solution storage tank. Solution in the storage tank is heated partially by passage of heat through the walls of the reservoir tank module. Additional heat is derived from waste heat in engine exhaust gas and is added to the system either by passing a portion of the exhaust gas stream directly onto or through the solution or by passing air heated by the exhaust gas stream directly onto or through the solution. Alternatively, the hot gas may be impinged onto an outer surface of the storage tank.

Description

TECHNICAL FIELD[0001]The present invention relates to emissions control in compression-ignited internal combustion engines; more particularly, to systems for injecting urea into diesel exhaust to scavenge nitrogen oxides and rejuvenating a diesel particulate filter; and most particularly, to a system for heating and liquefying a storage tank solution of urea at normally sub-freezing urea-solution temperatures.BACKGROUND OF THE INVENTION[0002]To scavenge oxides of nitrogen (NOx) from the exhaust of compression-ignited (CI) engines, and especially diesel engines, urea injection systems are commonly in use in the prior art. An aqueous urea solution is injected into the hot exhaust pipe, where urea is hydrolyzed into ammonia ahead of a selective catalytic reduction (SCR) converter. Ammonia reacts with NOx trapped on the catalyst face to form N2, CO2, and H2O, thereby lowering the level of noxious emissions in the exhaust.[0003]A serious problem in the prior art is that at temperatures b...

Claims

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Application Information

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IPC IPC(8): F01N5/02F01N3/28
CPCF01N3/2066F01N5/02F01N2610/10Y02T10/24F01N2610/1466Y02T10/16F01N2610/1406Y02T10/12
Inventor LI, BOB X.BONADIES, JOSEPH V.
Owner DELPHI TECH INC