Controlling Gas Mixture for Minimum Emissions

Continental Controls Corp. (CCC), based in San Diego, California, has introduced an emissions control valve, the model ECV-5, that is designed to control the air-fuel mixture of natural gas-fueled, reciprocating engines. CCC said the ECV-5 controls the air-fuel ratio in a closed loop manner, works with an oxygen sensor, is located in the exhaust, and has a three way catalytic converter. The ECV-5 and its O2 sensor, is designed for use with carbureted natural gas engines from 75 to 750 kW, both naturally aspirated and turbocharged.

The O2 sensor, installed in the engine exhaust, provides a measure of the oxygen content in the exhaust gas near stoichiometric mixture, CCC said. The voltage from the O2 sensor is feedback to the emissions control valve. The valve and sensor operate in a closed loop manner to control the fuel mixture to be slightly rich of stoichiometric. This mixture is optimized for a three-way catalytic converter.