Parallel Positioning / Linkageless Controls | F.W. Starrett Company, Inc.

Parallel Positioning/Linkage less Controls information

Parallel Positioning / Linkage less Controls

Many boiler burners are controlled by a single modulating motor with jackshafts to the fuel valve and air damper. This arrangement, set during startup, fixes the air-to-fuel ratio over the firing range. Unfortunately, environmental changes such as temperature, pressure and relative humidity alter the fixed air-to-fuel ratio, making combustion inefficient. To account for these conditions, boilers with jackshaft systems are typically set up with a high amount Cof excess air. This higher excess air level reduces boiler efficiency and, over time, linkages wear -- making repeatability impossible. To solve this problem, consider incorporating parallel positioning into the controls system. It’s a process using dedicated actuators for the fuel and air valves. Burners that incorporate parallel positioning can be set with lower excess air levels. Energy savings of up to 5 percent can be realized by introducing a parallel positioning system

O₂Trim

Another way to ensure peak efficiency is to use an oxygen sensor/transmitter in the exhaust gas. The sensor/transmitter continuously senses oxygen content and provides a signal to the controller that “trims” the air damper and/or fuel valve, maintaining a consistent oxygen concentration. This minimizes excess air while optimizing the air-to-fuel ratio.