Developments in the control of packaged boilers

Packaged boilers have historically been controlled with pneumatic combustion control systems and electromechanical burner management systems. The low cost and flexibility of microprocessor based systems, coupled with ever tightening environmental requirements, makes the use of these new systems an obvious choice. In the past, with low energy costs and relatively low labor rates, packaged boilers providing saturated steam for building or process heat were operated with large amounts of excess air, at moderate firing rates and in full attendance of one or more operators. Spurious trips off the boilers were tolerated due to the availability of the operator and, in most cases, sufficient capacity available from other boilers on the same header to pick up the load. In today`s economic climate, and with the advent of low excess air burners, proper operation dictates a minimum number of boilers on the line at any one time with each boiler operating at or near its highest efficiency, or higher firing rate. Under these conditions, a greater premium is placed on the accuracy, characterizable nature and reliability of the combustion and burner management controls. In addition, the newly imposed air quality standards, frequently requiring Best Available Control Technology of emissions, place greater demandmore » on the control system and strategy.« less