STEAM GENERATOR SYSTEM OPERATION

摘要

The flue gas temperature coming from an air preheater to a particulate collection device such as an electrostatic precipitation or fabric filter is reduced to improve the operation of the particulate collection device. This may be done by reducing the exit flue gas temperature from the air preheater or reducing the temperature after exiting. In one embodiment, air in excess of that needed for combustion is passed through the air preheater with the heated excess air either being dumped or used for a variety of purposes in the plant. A particular embodiment involves segmenting the air outlet side of a rotary regenerative air preheater and withdrawing the excess air from the segment where the dust loading is the lowest. Further, additional cooling of the flue gas can be provided by reducing the quantity of primary air that typically bypasses the air preheater and then providing other ways to control the primary air temperature to the pulverizers. The flue gas temperature may also be cooled after the air preheater by heat exchange or spray cooling with water.