To protect the regenerative air heater against corrosion when operating the boiler at low loads and/or low ambient air temperatures, a steam coil air heater will be required in the secondary air ducts between the FD fans and the regenerative air heaters. The steam coil air heater should be designed to heat combustion air at any load from the minimum ambient temperature, ºC, up to a temperature suitable to protect the cold end elements of the regenerative air heater. Supply of the steam coil air heater will not be by Babcock & Wilcox. | Sumitomo Corporation for EVNGENCO1 Duyen Hai 3 Extension, 1 x 660 MWnet Power Project COMBUSTION AIR SYSTEM July 7, 2014 Air Heaters Steam Coil Air Heaters To protect the regenerative air heater against corrosion when operating the boiler at low loads and/or low ambient air temperatures, a steam coil air heater will be required in the secondary air ducts between the FD fans and the regenerative air heaters. The steam coil air heater should be designed to heat combustion air at any load from the minimum ambient temperature, ºC, up to a temperature suitable to protect the cold end elements of the regenerative air heater. Supply of the steam coil air heater will not be by Babcock & Wilcox. Regenerative Air Heater Two (2) Ljungstrom Tri-sector air preheater will be furnished, capable of 100% load. Design of the regenerative air heater ensures that the flue gas temperature leaving the boiler is reduced to a minimum practical value in order to maximize boiler efficiency without introducing corrosion and fouling issues in the cold end of the heater. The air preheater design is also based upon the requirement that the pulverized coal system has the drying capability to process the range of coal analyses as specified. General Description The Ljungstrom Tri-sector air preheater employs heating elements contained in a rotor which passes them alternately through the flue gas and the incoming air streams. In this type of heat exchanger, the heating surfaces are alternatively heated by the flue gas passing through and cooled by the air passing over it. The heat is absorbed by the heat transfer matrix from the flue gases and released to the air. The design of the air heater is such that it can give trouble-free service for extended periods of time without plugging of flow areas between heating element plates. The elements are arranged in the rotor in baskets. Access doors permit removal and maintenance of elements in the cold end of the unit. A geared .
