Final Flashcards
safety valves - uses, types, how they work
- prevent overpressure
- open completely when set pressure is reached and stay open until pressure drops
- 2 common types: huddling chamber type and nozzle reaction type
- typically 3 on a propulsion boiler: 2 on steam drum, 1 on superheater
when calcium carbonate or magnesium carbonate is deposited on hot metal surfaces, forming a hard brittle substance. causes hot spots and blistering on the side of the tube
Waterside Deposits (Scale)
types of feed water contamination
Waterside Corrosion, Caustic Embrittlement, Foaming, Priming and Carryover, scaling
sources of feed water contamination
condenser leaks, fuel and lube oil, Distilling Plant Evaporators, Make-Up Feed Tanks, Drain Collecting Tanks
ideal pH levels - boiler water
9 to 11
Total Dissolved Solids - what, problems, solutions
amount of sludge that is suspension in the boiler water. Excessive TDS can cause foaming, priming, and carryover. Can be reduced with either bottom blowdown or continuous bottom blowdown
purpose of adding phosphates
control scaling. they react with calcium and magnesium to from cal/mag phosphates that can easily be removed by surface or bottom blowdown
a heat exchanger which removes the latent heat from exhaust steam so that it condenses and can be pumped back into the boiler
main condenser
problem of air in the main condenser
- corrosion
- back pressure, loss of condensing
a series of steel doors that open when the burner is one, to allow air from the forced draft fan in and close when the burner is off. air volume is controlled by the forced draft fan, not the register. either open or closed
register (air register)
ideal pH levels - condensate
8.9 to 9
what do chlorides indicate?
too many impurities in the water
Superheated steam uses
Main Engine, Main Generator(s), possibly feed pumps and cargo pumps
