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

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.

1 . A system for keeping a solution of urea in a liquid state at normally sub-freezing temperatures or liquefying such solution if frozen, for delivery to an emissions abatement system of an internal combustion engine, comprising:
 a) a storage tank for said urea solution;   b) first apparatus for deriving a hot gas from an exhaust system of said engine; and   c) second apparatus for impinging said hot gas against an area of said storage tank to heat said solution of urea therewithin.   
     
     
         2 . A system in accordance with  claim 1  wherein said second apparatus includes said storage tank, a gas sparger disposed within said storage tank for dispersing said hot gas, and a tank vent for escape of cooled gas from said tank. 
     
     
         3 . A system in accordance with  claim 1  wherein said second apparatus includes at least one of a filter for filtering said hot gas, a temperature sensor, and a pressure sensor. 
     
     
         4 . A system in accordance with  claim 1  wherein said first apparatus includes a diverter valve mounted on said exhaust system for diverting a portion of an exhaust gas stream flowing therewithin, and wherein said hot gas is said exhaust gas portion. 
     
     
         5 . A system in accordance with  claim 1  wherein said first apparatus includes a hot air collector disposed adjacent said exhaust system. 
     
     
         6 . A system in accordance with  claim 5  wherein said first apparatus further includes a fan configured for passing said hot gas into said second apparatus. 
     
     
         7 . A system in accordance with  claim 1  wherein said impinged area of said storage tank is selected from the group consisting of within said storage tank and an outer surface of said storage tank. 
     
     
         8 . An internal combustion engine comprising a system for keeping a reservoir solution of urea in a liquid state at normally sub-freezing temperatures, or liquefying such solution if frozen, for delivery to an emissions abatement system of an internal combustion engine, wherein said system includes,
 a storage tank for said urea solution,   first apparatus for deriving a hot gas from an exhaust system of said engine, and   second apparatus for impinging said hot gas against an area of said storage tank to heat said solution of urea therewithin.   
     
     
         9 . A method for keeping a reservoir solution of urea in a liquid state at normally sub-freezing temperatures, or liquefying such solution if frozen, for delivery to an emissions abatement system of an internal combustion engine, comprising the steps of:
 a) providing a storage tank for said urea solution;   b) deriving a hot gas from an exhaust system of said engine; and   c) impinging said hot gas against an area of said storage tank to heat said solution of urea therewithin.   
     
     
         10 . A method in accordance with  claim 9  wherein said hot gas is at least a portion of an exhaust gas stream of said internal combustion engine. 
     
     
         11 . A method in accordance with  claim 9  wherein said hot gas is heated air. 
     
     
         12 . A method in accordance with  claim 9  wherein said impinging step is selected from the group consisting of impinging said hot gas within said storage tank and impinging said hot gas against an outer surface of said storage tank.