Abstract: A method for purging reductant from a reductant supply system is disclosed. The method includes dispensing reductant into an exhaust system via a dispensing device. The method also includes purging the dispensing device by urging reductant from the dispensing device to a reductant source.

Abstract: Methods and apparatus for injecting reagent, such as an aqueous urea solution, into an exhaust stream in order to reduce emissions from an engine exhaust. The present teachings can use a whirl plate having a plurality of whirl slots surrounding an exit orifice of an injector, which produce a high velocity rotating flow in the whirl chamber. When the rotating flow of reagent is passed through the exit orifice into an exhaust stream, atomization occurs from a combination of centrifugal force and shearing of the reagent by air as it jets into the exhaust stream.

Abstract: A method for purging reductant from a reductant supply system is disclosed. The method includes dispensing reductant into an exhaust system via a dispensing device. The method also includes purging the dispensing device by urging reductant from the dispensing device to a reductant source.

Abstract: Methods and apparatus for injecting reagent, such as an aqueous urea solution, into an exhaust stream in order to reduce emissions from an engine exhaust. The present teachings can use a whirl plate having a plurality of whirl slots surrounding an exit orifice of an injector, which produce a high velocity rotating flow in the whirl chamber. When the rotating flow of reagent is passed through the exit orifice into an exhaust stream, atomization occurs from a combination of centrifugal force and shearing of the reagent by air as it jets into the exhaust stream.

Abstract: The present invention provides methods and apparatus for injecting reagent, such as an aqueous urea solution, into an exhaust stream in order to reduce oxides of nitrogen (NOx) emissions from diesel engine exhaust The present invention uses mechanical spill return atomization techniques to produce droplets approximately 50 ?m SMD (Sauter mean diameter) or smaller. This size range is appropriate to allow urea to react into ammonia within the residence time associated with an on-road diesel engine. This effect is achieved through the use of a whirl plate having a plurality of whirl slots surrounding an exit orifice of the injector, which produce a high velocity rotating flow in the whirl chamber. When the rotating flow of reagent is passed through the exit orifice into an exhaust stream, atomization occurs from a combination of centrifugal force and shearing of the reagent by air as it jets into the exhaust stream.

Abstract: The present invention provides for the retrofitting diesel truck engines with a system to reduce NOx emissions. The SCR system of the present invention, including a controller, a reagent tank, and an injection system, is installed on a vehicle. A NOx detector is temporarily installed as part of the system. The vehicle is then operated to collect engine parameters including fuel injection timing, RPM, load, exhaust heat, exhaust flow rate, and the like, together with measurements of the NOx emissions under various operating conditions. Based on the recorded data at various operating conditions, a reagent injection strategy is developed and installed at the reagent injection controller. During vehicle operation, the injector injects reagent into the exhaust system based on control signals from the reagent injection controller in accordance with the injection strategy in order to reduce NOx emissions at the various operating conditions.

Abstract: The present invention provides for the retrofitting diesel truck engines with a system to reduce NOx emissions. The SCR system of the present invention, including a controller, a reagent tank, and an injection system, is installed on a vehicle. A NOx detector is temporarily installed as part of the system. The vehicle is then operated to collect engine parameters including fuel injection timing, RPM, load, exhaust heat, exhaust flow rate, and the like, together with measurements of the NOx emissions under various operating conditions. Based on the recorded data at various operating conditions, a reagent injection strategy is developed and installed at the reagent injection controller. During vehicle operation, the injector injects reagent into the exhaust system based on control signals from the reagent injection controller in accordance with the injection strategy in order to reduce NOx emissions at the various operating conditions.

Abstract: A method for reducing emissions of oxides of nitrogen from a combustion process using a temperature sensitive liquid reagent injected into a stream of exhaust gases from the combustion process and passing the exhaust gases and the reagent through a catalytic reactor which reduces the oxides of nitrogen in the presence of the reagent is disclosed. The steps of the method include providing an injector having an orifice for atomizing the liquid reagent; positioning a portion of the injector having the orifice within the stream of exhaust gases; cooling the injector by continuously circulating the reagent therethrough, thereby keeping both the injector and the reagent within the injector below a critical temperature at which the reagent will solidify; and injecting a portion of the reagent into the exhaust stream upstream of the reactor.

Abstract: An injector for delivery of a fluid into a stream of hot gas is disclosed. The injector has a valve body with an elongated chamber in fluid communication with an orifice. A valve seat surrounds the orifice. A valve plunger is disposed within the chamber, an end of the plunger being adapted to sealingly interengage the seat. The plunger is slidably movable between an open and a closed position to open and close the orifice. A fluid inlet and an outlet are disposed within the valve body to deliver fluid to an annular fluid passageway in the chamber adjacent to the valve seat. Fluid is circulated through the annular passageway to cool the valve and a portion of the fluid is expelled through the orifice when the orifice is opened. The plunger is biased into the closed position by a coil spring and movable into the open position by a solenoid actuator mounted atop the valve body.

Abstract: Urea is pyrolyzed in a chamber designed to facilitate gasification of the urea by pyrolysis with conversion of urea to ammonia and isocyanic acid (HNCO) with water vapor and carbon dioxide. The product gases are introduced into exhaust gases from a lean-burn engine, preferably upstream of a turbocharger. The exhaust gases are then contacted with an SCR catalyst.

Abstract: A safe, reliable SCR system for reducing NO.sub.x emissions from a lean-burn internal combustion engine utilizes urea in aqueous solution. A modular assembly is provided for mounting inside a urea reagent tank enables controlled feeding an aqueous urea solution to an injector. The assembly includes a reagent quality sensor, a reagent temperature sensor, a reagent level sensor and a pump.

Abstract: A safe, reliable SCR system for reducing NO.sub.x emissions from a lean-burn internal combustion engine utilizes urea in aqueous solution. Overheating and hydrolysis of the solution are prevented by maintaining the temperature of the urea solution sufficiently low that it is not permitted sufficient time at elevated temperature to hydrolyze the urea to such an extent that solids precipitate. In a preferred embodiment, an injector system similar to those used for fuel injection provides a constant feed to injectors and a return line. The feed and injection can be controlled to provide sufficient urea for NO.sub.x reduction and sufficient cooling capacity for the feed and injection system to avoid hydrolysis and deposits of hydrolysis products.

Abstract: Urea is pyrolyzed in a chamber designed to facilitate gasification of the urea by pyrolysis with conversion of urea to ammonia and isocyanic acid (HNCO) with water vapor and carbon dioxide. The product gases are introduced into exhaust gases from a lean-burn engine, preferably upstream of a turbocharger. The exhaust gases are then contacted with an SCR catalyst.

Abstract: Exhaust gas recirculation and selective catalytic reduction with urea or other NO.sub.x - reducing reagent are employed to enable good fuel economy and low emissions from diesel and lean-burn gasoline engines. EGR is operated at low-load, as well as when problems are experienced with reagent supply or the SCR unit. The SCR is run at its optimum operating conditions of normal to high load, supplanting the need for EGR. The net effect is a circumvention of the known tradeoff between NO.sub.x and poor fuel economy. The novel application of SCR and EGR in combination will provide engines that meet low emissions requirements with existing technology.

Abstract: Diesel and other lean-burn engines emit less NO.sub.x, when the of fuel comprises an emulsion of hydrocarbon fuel and an aqueous solution of a nitrogenous NO.sub.x -reducing reagent which is separated into its two principal portions prior to combustion. The hot exhaust gases produced by burning the fuel contain NO.sub.x, but the NO.sub.x is reduced by introducing the separated aqueous solution of nitrogenous NO.sub.x -reducing reagent into at least a portion of the exhaust gases and directing them to a catalyst for selective catalytic reduction of NO.sub.x. The fuel emulsion preferably comprises a continuous phase comprising diesel fuel and from about 1 to about 20% (most preferably, from about 2 to about 10%) of a discontinuous phase comprising an aqueous solution of nitrogenous NO.sub.x -reducing reagent. It is also preferred to include in the fuel a corrosion inhibitor and biocide, and optionally a lubricity additive and emulsifier.

Abstract: Urea or other solid NO.sub.x -reducing reagent is employed in a selective catalytic reduction process on emissions from diesel and lean-burn gasoline engines. The solid reagent is fed to a gas generator that produces a reactant gas by heating. In one embodiment the reactant gas is maintained at elevated temperatures to prevent condensation products from forming. The reactant gas contains ammonia and is fed to the exhaust on an as-needed basis.