System for injecting reactants in an exhaust line

Abstract

A system to be fitted on an automotive vehicle for injecting reactants in an exhaust line of an engine of the vehicle includes a source of a liquid precursor of ammonia, a source of gaseous ammonia, an injection assembly designed to be fitted on the exhaust line and to inject liquid precursor and/or gaseous ammonia inside the exhaust line, the injection assembly including a single injector body to be fitted on the exhaust line, the injector body having a first inlet for the liquid precursor, a second inlet for the gaseous ammonia, and at least one outlet for injection inside the exhaust line.

Description

BACKGROUND AND SUMMARY[0001]The present invention relates to a system for injecting reactant(s) in an exhaust line of an engine. It may be used in the context of treating nitrogen oxides contained in exhaust gases flowing in an exhaust line of the engine, especially but not exclusively in a vehicle.[0002]Exhaust gases formed due to the combustion of fuel in an internal combustion engine may contain a proportion of undesirable components, in particular nitrogen oxides (NOx).[0003]Various exhaust after-treatment systems are known for removing or reducing the amount of undesirable components. Some of these systems require that at least one reactant fluid is injected in the exhaust line to react with the exhaust gases, either directly, or indirectly after having undergone one or several chemical transportation, and / or with the help of catalysts.[0004]One known example of such an exhaust after-treatment system is the so-called selective catalytic reduction (SCR) system which has been imp...

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Benefits of technology

[0021]Another advantage of the invention lies in the fact that the injector can be simplified since it is less demanding on the quality of the injection spray at some difficult functioning points. Indeed, since injection of liquid reactant can be avoided under non-optimal operating conditions, there is less of a need to have a perfectly nebulized spray. Moreover, in some embodiments of the invention, injecting simultaneously both the liquid precursor and gaseous ammonia at the same time can be sufficient to get a satisfactory quality of injection spray at said functioning points, especially at operation points where conditions are borderline with respect to the liquid reactant.

[0022]Furthermore, owing to the provision of a single injector body, the invention improves compactness and simplifies the system integration in a small allocated space. This further allows reducing the system overall cost, also because there can be provided a single protection package of the various components of the injector assembly, especially a single heat protection package. Said protection package can be fairly complicated and expensive due to the constraints resulting from the hot environment.

[0023]In practice, there may be provided one or several first inlets, as well as one or several second inlets. The first inlet(s) and second inlet(s) can be separate. Alternatively, there may be provided one or several common inlets for the liquid precursor and for gaseous ammonia.

[0024]According to an embodiment, the injector body can comprise one or several common outlets for the liquid precursor and the gaseous ammonia. In such a case, the flow path of the liquid precursor and the flow pa

Problems solved by technology

One problem with this type of exhaust gases treatment system is that, in some operating conditions of the engine, especially when the temperature of the exhaust gases is relatively low, for example around 20.0° C., urea, and/or it's the intermediate product in its transformation into ammonia, can crystallize before it has transformed into ammonia.

One consequence is that the cross section of the exhaust pipe may be progressively reduced, which may decrease the engine efficiency and which can seriously impair the engine operati

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