Emissions diagnostic system

An emissions diagnostic system for a compression ignition engine having an exhaust gas stream directed into an SCR catalyst capable of reducing NOx in the exhaust gas stream, the system comprising:

• a tank for storing a solution of urea;
• a pump in fluid communication with the tank for drawing the solution of urea from the tank;
• a valve in fluid communication with the pump and the exhaust gas stream for receiving the solution of urea from the pump;
• an air pump connected to the valve for providing air into the valve for mixing with the solution of urea, the valve for spraying the solution of urea into the exhaust gas stream;
• a sensor for sensing the level of NOx emissions emitted by the SCR catalyst;
• a control module connected to the sensor for determining whether the level of NOx emissions is at an acceptable level;
• and
• a sensor associated with the pump for sensing the pressure being generated by the pump, the sensor being connected to the control module for determining whether the sensed pressure is at an acceptable limit.

An emissions diagnostic system for reducing NOx emissions from an exhaust gas stream of a compression ignition engine, the exhaust gas stream being passed through an SCR catalyst effective for selective catalytic NOx reduction, the system comprising:

• a tank for storing a solution of urea, the tank further having a heat source to apply heat to the solution of urea;
• a pump connected to the tank for pumping the solution of urea from the tank;
• a valve connected to the pump and exhaust gas stream, the valve for receiving the solution of urea from the pump;
• an air pump connected to the valve for providing air into the valve for mixing with the solution of urea, the valve for controllably spraying the solution of urea into the exhaust gas stream;
• a sensor associated with an output of the SCR catalyst for sensing the level of NOx emissions emitted by the SCR catalyst;
• a controller connected to the sensor for determining whether the level of NOx emissions is within a predetermined range;
• and
• a sensor associated with the air pump for sensing the air pressure being generated by the air pump, the sensor being connected to the controller for determining whether the sensed pressure is at an acceptable limit.

An emissions diagnostic system for reducing NOx emissions from an exhaust gas stream of a compression ignition engine, the exhaust gas stream being passed through an SCR catalyst effective for selective catalytic NOx reduction, the system comprising:

• a tank for storing a solution of urea, the tank further having a heat source to apply heat to the solution of urea;
• a pump connected to the tank for pumping the solution of urea from the tank;
• a valve connected to the pump and exhaust gas stream, the valve for receiving the solution of urea from the pump;
• an air pump connected to the valve for providing air into the valve for mixing with the solution of urea, the valve for controllably spraying the solution of urea into the exhaust gas stream;
• a sensor associated with an output of the SCR catalyst for sensing the level of NOx emissions emitted by the SCR catalyst;
• a controller connected to the sensor for determining whether the level of NOx emissions is within a predetermined range;
• and
• a sensor associated with the pump for sensing the pressure being generated by the pump, the sensor being connected to the controller for determining whether the sensed pressure is at an acceptable limit.

A method for determining an abnormal operating condition for a NOx emission reducton system for use with an exhaust gas stream associated with a compression ignition engine comprising:

• spraying a solution of urea into the exhaust gas stream via a pressurized gas;
• determining a pressure of the pressurized gas;
• and
• transmitting a warning signal when the pressure of the pressurized gas is outside a predetermined range for a first predetermined time.

A method for determining an abnormal operating condition for a NOx emission reduction system for use with an exhaust gas stream associated with a compression ignition engine comprising:

• pressurizing a solution of urea;
• spraying said solution of urea into the exhaust gas stream via a pressurized gas;
• determining a pressure of the urea solution;
• and
• transmitting a warning signal when the pressure of the urea solution is outside a predetermined range for a first predetermined time.