14. Boilers. Flashcards
- Boiler Horsepower (BHP).
It is the evaporation of 34.5 Lb./Hr. of water at a temperature of 212F. One BHP is equivalent to 33,472 BTU/Hr. Steam produced in a boiler has a corresponding temperature and pressure. For example, water boilers and turns to steam when it reached212F at atmospheric pressure (14.7 PSI at sea level).
- High pressure boiler.
It is a boiler that has a MAWP above 15 PSI and over 6 boiler horsepower (BHP).
- Package boiler.
It is a boiler that is preassembled at the factory. The package boiler is a self-contained unit complete with all fittings for hook-up and operation in place. At the installation site, package boilers only require connection of feed-water lines, fuel lines, electrical connections, and breaching and chimney. Package boilers can be Fire-tube or Water tube boilers.
- Fire-tube boilers.
They were originally designed for use on ships, and were called Scotch Marine Boilers. Fire-tube boilers are long, horizontal, cylindrical-shaped vessels with an internal furnace and gases of combustion inside the tubes. The internal furnace and tubes are housed within a larger vessel that contains water and steam. The tubes are supported by tube sheets. Heat from the flame and gases of combustion make two, three, or four passes, depending on the design. Fire-tube boilers contain a large amount of water. Because of their vessel size, fire-tube boilers can respond to load changes with minimal variation in steam pressure.
- Tube sheet.
It is a metal sheet into which boiler tubes are mounted. A fire=tube boiler has front and rear tube sheets.
- Pass.
It is the path or area where gases of combustion travel the length of the boiler.
- Dry-back boiler.
In a dry-back boiler, a refractory lined chamber outside of the vessel directs the gases of combustion from the furnace to the tubes.
- Wetback fire-tube boiler.
A water-cooled turn-around chamber directs gases of combustion from the furnace to the tube bank.
- Tube bank.
It is an assembly of tubes in the boiler.
- Fire=box boiler.
It is a furnace boiler that has a round top and flat sides. The fire-box boiler has an internal furnace that houses the flames from the burner and water legs that expend down the sides of the boiler. Steam produced in the steam apace is routed out the steam outlet at the top of the boiler. Firebox boilers are used for low-pressure steam or hot water heating appliances.
- Water column.
It is a bailer that reduces the movement of boiler water to provide an accurate water level in the gauge glass.
- Safe valve capacity.
It is amount of steam, in pounds per hour (Lb./Hr.) that the safety valve is capable of venting at the rated pressure of the safety valve. The safety valve capacity is listed on the data plate attached to the safety valve.
- What is a surface blowdown valve?
It controls the amount of water released from the boiler at the NOWL, and used to drain surface impurities and matter.
