Which of the following statements is correct for steam boiler?
1
Boiler secondary heat transfer surface includes super-heater, economizer and air pre-heater.
2
Boiler primary heat transfer surface includes evaporator section, super-heater section. and reheat section.
3
Boiler primary heat-transfer surface includes evaporator section, economizer and super-heater section.
4
Boiler secondary beat transfer surface includes evaporator section, economizer and air pre-heater