Urea common rail

An exhaust after-treatment system, comprising:

• an exhaust passage;
• at least one exhaust treatment component located in the exhaust passage;
• a plurality of dosing modules for dosing an exhaust treatment fluid into an exhaust stream passing through the exhaust passage;
• a fluid distributor providing the exhaust treatment fluid to each of the dosing modules, the fluid distributor being divided into a first pair of legs;
• a return, the return being divided into a second pair of legs;
• a first valve positioned between and in fluid communication with a first leg of the fluid distributor and a first leg of the return, the first valve being configured to allow a flow of the exhaust treatment fluid from the first leg of return to the first leg of the fluid distributor during a purging of the exhaust treatment fluid;
• a second valve positioned between and in fluid communication with a second leg of the fluid distributor and a second leg of the return, the second valve being configured to allow a flow of the exhaust treatment fluid from the second leg of return to the second leg of the fluid distributor during the purging of the exhaust treatment fluid;
• and
• a controller in communication with each of the first and second valves, the controller configured to open the first and second valves and allow the fluid communication during the purging.

An exhaust after-treatment system, comprising:

• an exhaust passage configured to divide into a plurality of legs;
• an exhaust treatment device disposed in each of the legs;
• a plurality of dosing modules for dosing an exhaust treatment fluid into the exhaust passage, at least one of the plurality of dosing modules being associated with a corresponding leg of the exhaust passage;
• a fluid distributor configured to provide the exhaust treatment fluid to each of the dosing modules and a return configured to receive unused exhaust treatment fluid from each of the dosing modules, the fluid distributor and the return being in fluid communication via a plurality of first valves located between the fluid distributor and the return during a purge of the exhaust treatment fluid from the fluid distributor, the plurality of dosing modules, and the return, the first valves being configured to allow a flow of the exhaust treatment fluid from the return to the fluid distributor during the purge;
• a controller in communication with each of the first valves, the controller configured to open each of the first valves and allow the fluid communication between the return and the fluid distributor during the purge;
• and
• a plurality of second valves configured to control entry of exhaust from the exhaust passage into each of the plurality of legs.