EC sensor: flame safety and fuel savings integrated into one system

Safety is the most important consideration in the operation of any combustion system. To that effect, operators of combustion equipment monitor the presence of a flame in various ways. The most common flame monitoring sensors include flame rods, infrared scanners and ultra-violet scanners. Although these systems have gained wide industry acceptance, in some instances they may suffer from disadvantages related to longevity, reliability or unexpected nuisance shutdowns. A system that eliminates these disadvantages would be highly beneficial. Monitoring the flame alone does not yield information about stoichiometry of the fuel-air mixture. Fuel-air ratio control is generally accomplished by measuring the oxygen concentration in the stack. To accommodate proper fuel-air mixing in diffusion-style burners and avoid carbon monoxide emissions, 15%-20% excess air (3%-4% excess O2 in the stack) is commonly the set point. Unfortunately, furnaces with multiple burners can only perform global control, leaving the potential for individual burner fuel-air ratio conditions that highly deviate from the global set point creating the potential for unsafe and fuel inefficient conditions. This can happen in natural draft furnaces because of wind conditions or improper air register positioning and can be an even bigger problem in forced draft furnaces with common air plenums where air flow maldistribution is not uncommon. ClearSign Combustion Corporation has developed the EC Sensor (Electrical Capacitance Sensor), a highly-reliable, innovative monitoring and diagnostic system that integrates the capability of continuous flame monitoring while measuring fuel-air ratio at the same time. The sensor incorporates ClearSign's patented technology on the use of electric fields in combustion systems that discriminates flames from other burners and does not require immersed probes in the flame, adjustments in the field of view or reliability on infrared or ultraviolet radiation.