System for dosing reagent

摘要

A reagent dosing system for dosing a reagent into the exhaust gas stream of an internal combustion engine (3), comprising a reagent tank (21) for storing a supply of reagent; an injector module (40) comprising an atomising dispenser (42) and a positive-displacement metering pump (41) which draws reagent from the reagent tank (21) and delivers it to the dispenser (42); a supply line (35) coupling the reagent tank (21) to the injector module (40); a dosing control unit (70) operable to control the injector module (40) to inject reagent into the exhaust gas stream; and an additional priming pump (80) arranged, in use, to urge reagent along the supply line (35) toward the injector module (40) under selected conditions.