Comments by "David Elliott" (@davidelliott5843) on "Naval Boilers - Grates Under Pressure" video.

  1. Condensing "boilers" extract energy from the flue gas steam generated when the fuel is burnt. But they are not really boilers at all, because the water is never allowed to get hot enough. The economiser is a feed-water pre-heater sat after the super heater. Really big boilers might have an air pre-heater behind that.
    3
  2. Induced draft fans are bigger than forced draft. This puts the fire under a slight negative air pressure, less likely to blow back and any firebox leaks do not put fumes into the boiler room.
    1
  3. In water tube boilers, any scale fouling happens at the water boiling range of the water tubes. In high pressure boilers this scale can create an environment adjacent to the metal, aggressive enough to split water into hydrogen and oxygen. This eventually results in hydrogen embrittlement of the steel boiler tubes. When a brittle tube bursts it will take out adjacent tubes sometimes with enough force to blow out the fire. The burners will continue to spray hot oil making a fuel-air explosion highly likely.
    1
  4. A boiler explosion is especially nasty, becuase wet steam takes up 1000x the volume of the hot water it came from. Superheated steam is even worse due to the added energy. High pressure super-heated steam leaks are invisible and can literally slice the human body apart.
    1